JBS Haldane said when asked by a theologian "what can we infer from the mind of he creator by his creation". Haldane is a very famous biologist. He said "he has an inordinate fondness of beatles" because beatles are the most diverse species. However there are four orders of beatles so Aldane was correct, the quadrant model can be seen through them. There was a fifth order but it went extinct. The fifth is always questionable. They are
† Protocoleoptera
Many beetles were prominent in ancient cultures.[78] Of these, the most prominent might be the dung beetle in Ancient Egypt. Several species of dung beetle, most notably the species Scarabaeus sacer (often referred to as the sacred scarab), enjoyed a sacred status among the ancient Egyptians.[79] Popular interpretation in modern academia theorizes the hieroglyphic image of the beetle represents a triliteral phonetic that Egyptologists transliterate as xpr or ḫpr and translate as "to come into being", "to become", or "to transform".
And the fourth order is different from the other three.
The scarab was linked to Khepri ("he who has come into being"), the god of the rising sun. The ancients believed the dung beetle was only male in gender, and reproduced by depositing semen into a dung ball. The supposed self-creation of the beetle resembles that of Khepri, who created himself out of nothing. Moreover, the dung ball rolled by a dung beetle resembles the sun.
It is no coincidence the group representing becoming (the 19th square) reflects the quadrant pattern

Cockroaches are insects of the order Blattodea, which also includes termites. About 30 cockroach species out of 4,600 are associated with human habitats. About four species are well known as pests.

Laing's 1993 Tetrahedron of Bonding

In 1993 Michael Laing published an expansion of the two dimensional van Arkel-Ketelaar triangle of bonding into a tetrahedron by dividing covalent materials into two types, Covalent Network and van der Waals Molecular: M. Laing, A Tetrahedron of Bonding, Education in Chemistry, November, pp160-163…/38_laing/tetrahedra.html

The Grimm Tetrahedron (1928, but rather forgotten)

William Jensen reports, below, that Grimm and Dehlinger developed an early form of tetrahedron in the nineteen thirties. However, this knowledge appears to have been forgotten. The Grimm Tetrahedron symbolically reflects with the four vertices of a tetrahedron the four main types of bonding in solid chemical compounds: metallic (metallisch), ionic (heteropolar), van der Waals (molecular) & network (homopolar).

From William B. Jensen's paper: Logic, History, and the Chemistry Textbook, J.Chem.Educ. 817-828, 75, 1998:

Dehlinger's 1934 drawing of Grimm's tetrahedron:

Grimm’s two-dimensional projection of his 1934 bond- type tetrahedron redrawn by Jensen using corrected and updated examples:

i = Ionenbindung
a = Atombindung
m = metallische Bindung
z = zwischenmolekulare Kräfte

The six edges between these vertices correspond to the intermediate types of bonds. It is clear that the idea of isolated molecules can be most naturally applied only to one vertex of this diagram (the central one, where the intermolecular interactions are the weak van der Waals forces).

From the Concept of Chemical Periodicity: from Mendeleev Table to Molecular Hyper-Periodicity Patterns E. V. Babaev & Ray Hefferlin, here.…/38_laing/tetrahedra.html
Brothers Jim Weiner and Jack Weiner with friends Charles Foltz and Charles Rak claim that they were abducted by aliens during a camping trip in Allagash, Maine on August 20, 1976. According to the four men, hypnotic regression enabled them to recall being taken aboard a circular UFO and being "probed and tested by four-fingered beings with almond-shaped eyes and languid limbs". The first two were twins and are the duality. The fourth actually ended up kind of questioning the experience. The fourth is always different.

Protein quaternary structure

From Wikipedia, the free encyclopedia

The image above contains clickable linksInteractive diagram of protein structure, using PCNA as an example. (PDB: 1AXC​)

Protein quaternary structure is the number and arrangement of multiple folded protein subunits in a multi-subunit complex. It includes organisations from simple dimers to large homooligomers and complexes with defined or variable numbers of subunits.[1] It can also refer to biomolecular complexes of proteins with nucleic acids and other cofactors.


The quaternary structure- the fourth, is different

In structure, the proteasome is a cylindrical complex containing a "core" of four stacked rings forming a central pore. Each ring is composed of seven individual proteins. The inner two rings are made of seven β subunits that contain three to seven protease active sites. These sites are located on the interior surface of the rings, so that the target protein must enter the central pore before it is degraded. The outer two rings each contain seven α subunits whose function is to maintain a "gate" through which proteins enter the barrel. These α subunits are controlled by binding to "cap" structures or regulatory particles that recognize polyubiquitin tags attached to protein substrates and initiate the degradation process. The overall system of ubiquitination and proteasomal degradation is known as the ubiquitin-proteasome system.[3]

proteasome (four heptameric rings = 28 subunits)

There is one 20s particle.All 20S particles consist of four stacked heptameric ring structures that are themselves composed of two different types of subunits; α subunits are structural in nature, whereas β subunits are predominantly catalytic.
There are two 19s particles.
There is one 11s particle. The fourth is different

A homotetramer is a protein complex made up of four identical subunits which are associated but not covalently bound.[1] A heterotetramer is a 4-subunit complex where one or more subunits differ.[2]

Examples of homotetramers include:

enzymes like beta-glucuronidase (pictured)
export factors such as SecB from Escherichia coli[3]
magnesium ion transporters such as CorA.[4]
lectins such as Concanavalin A

Beta-glucuronidases are members of the glycosidase family of enzymes that catalyze breakdown of complex carbohydrates.[2] Human β-glucuronidase is a type of glucuronidase (a member of glycosidase Family 2) that catalyzes hydrolysis of β-D-glucuronic acid residues from the non-reducing end of mucopolysaccharides (also referred to as glycosaminoglycans) such as heparan sulfate.[2][3][4] Human β-glucuronidase is located in the lysosome.[5] In the gut, brush border β-glucuronidase converts conjugated bilirubin to the unconjugated form for reabsorption. Beta-glucuronidase is also present in breast milk, which contributes to neonatal jaundice. The protein is encoded by the GUSB gene.[6][7]…/File:Beta-Glucuronidase_Homotetr…

A homotetrameric complex, beta-glucuronidase (a glycosidase). Each subunit has the same amino acid sequence.…/…/faq/antoines-elements.shtml

Lavoisier is considered the "Father of chemistry". He was the first chemist to recognize that the air earth fire and water model of the four elements was not suitable for describing the elements of nature (although those who understand the quadrant model know that metaphorically it did describe reality). He is the first person to isolate oxygen and other elements and recognize that the four elements themselves were made of other elements.
He classified the known elements into four groups:
Elastic fluids
Lavoisier included light, heat, oxygen, nitrogen, and hydrogen in this group.
This group includes "oxidizable and acidifiable nonmetallic elements". Lavoisier lists sulfur, phosphorus, carbon, hydrochloric acid, hydrofluoric acid, and boric acid.
These elements are "metallic, oxidizable, and capable of neutralizing an acid to form a salt." They include antimony and arsenic (which are not considered metals today), silver, bismuth, cobalt, copper, tin, iron, manganese, mercury, molybdenum, nickel, gold, platinum, lead, tungsten, and zinc.
Lavoisier's salt-forming earthy solid "elements" included lime, magnesia (magnesium oxide), baryta (barium oxides), alumina (aluminum oxide), and silica (silicon dioxide).
This was a huge leap forward in chemistry and a realization that there was order to the elements and grand pattern to the building blocks of reality. Although the way he classified them is now considered incorrect.
This was the first modern classification of elements from which modern chemistry evolved. It fit the quadrant model pattern.…/…/faq/antoines-elements.shtml


There are four species of horseshoe crab.

Horseshoe crabs were traditionally grouped with the extinct eurypterids (sea scorpions) as the Merostomata. They may have evolved in the shallow seas of the Paleozoic Era (570–248 million years ago) with other primitive arthropods like the trilobites. The four species of horseshoe crab are the only remaining members of the Xiphosura, one of the oldest classes of marine arthropods.


The Atlantic horseshoe crab (Limulus polyphemus) is a marine chelicerate arthropod. Despite its name, it is more closely related to spiders, ticks, and scorpions than to crabs.[2] Horseshoe crabs are most commonly found in the Gulf of Mexico and along the northern Atlantic coast of North America. A main area of annual migration is Delaware Bay, although stray individuals are occasionally found in Europe.[3]


The other three extant species in the family Limulidae are also called horseshoe crabs.[4] These are Tachypleus tridentatus, Tachypleus gigas and Carcinoscorpius rotundicauda, which all are restricted to Asia.[4][5] All four are quite similar in form and behavior.


In 1956, Hartline revisited this concept of lateral inhibition in horseshoe crab (Limulus polyphemus) eyes, during an experiment conducted with the aid of Henry G Wagner and Floyd Ratliff. Hartline explored the anatomy of ommatidia in the horseshoe crab because of their similar function and physiological anatomy to photoreceptors in the human eye.

Mesothelae- spinnerets. Four pairs, in some species one pair fused, under middle of abdomen.

Spiders have primarily four pairs of eyes on the top-front area of the cephalothorax, arranged in patterns that vary from one family to another

Spiders also have four pairs of legs.

Tetrahymena are free-living ciliate protozoa that can also switch from commensalistic to pathogenic modes of survival. They are common in freshwater ponds. Tetrahymena species used as model organisms in biomedical research are T. thermophila and T. pyriformis. Tetra hymena means four membrane.

Tetrahymena possess hundreds of cilia and has complicated microtubule structures, making it an optimal model to illustrate the diversity and functions of microtubule arrays.

Tetra means four. They have four nuclei.

Studies on Tetrahymena have contributed to several scientific milestones including:

First cell which showed synchronized division, which led to the first insights into the existence of mechanisms which control the cell cycle.[3]

Identification and purification of the first cytoskeleton based motor protein such as dynein.[3]

Aid in the discovery of lysosomes and peroxisomes.[3]

Early molecular identification of somatic genome rearrangement.[3]

Discovery of the molecular structure of telomeres, telomerase enzyme, the templating role of telomerase RNA and their roles in cellular senescence and chromosome healing (for which a Nobel Prize was won).[3]

Nobel Prize–winning co-discovery (1989, in Chemistry) of catalytic ribonucleic acid (ribozyme).[3]

Discovery of the function of histone acetylation.[3]

Demonstration of the roles of posttranslational modification such as acetylation and glycylation on tubulins and discovery of the enzymes responsible for some of these modifications (glutamylation)

Crystal structure of 40S ribosome in complex with its initiation factor eIF1

First demonstration that two of the "universal" stop codons, UAA and UAG, will code for the amino acid glutamine in some eukaryotes, leaving UGA as the only termination codon in these organisms. [4]

Discovery of self-splicing RNA. [5]


The fourth is always different


Sponges were traditionally distributed in three classes: calcareous sponges (Calcarea), glass sponges (Hexactinellida) and demosponges (Demospongiae). However, studies have shown that the Homoscleromorpha, a group thought to belong to the Demospongiae, is actually phylogenetically well separated. Therefore, they have recently been recognized as the fourth class of sponges.[26][27]


Griffith's experiment, reported in 1928 by Frederick Griffith, was the first experiment suggesting that bacteria are capable of transferring genetic information through a process known as transformation. This experiment was revolutionary to the discovery of DNA and gene transference. The experiment fit the quadrant model pattern.

Griffith tried four things.

Square 1: He injected a mouse with a non virulent bacteria and it lived

Square 2: He injected a mouse with a virulent bacteria and it died

Square 3: He injected the mouse with the virulent bacteria and heated it thinking it would kill the virulent part of the bacteria and the mouse lived

Square 4: This was the transcendent square and was the shock of the experiment which lead to the revelation. The fourth square is always transcendent. Griffith then injected the mouse with the heated virulent bacteria and the non virulent bacteria. Since both of them had not killed the mouse he thought the mouse would survive. But he found that the mouse died and he found deadly bacteria in their blood. This means that the genes of the bacteria must have carried the DNA although Griffith did not know this and it took until the discovery of genes for this to be understood. He discovered something in the heated bacteria survived and transformed into killer cells. He had discovered genes and gene transfer.

This experiment is one of the most legendary experiments in biology history. It is no coincidence that the quadrant model is reflected.…/File:Griffith_experiment.svg's_experiment
Griffith's experiment, reported in 1928 by Frederick Griffith, was the first experiment suggesting that bacteria are capable of transferring genetic information through a process known as transformation. This experiment was revolutionary to the discovery of DNA and gene transference. The experiment fit the quadrant model pattern. 
Griffith tried four things.
Square 1: He injected a mouse with a non virulent bacteria and it lived
Square 2: He injected a mouse with a virulent bacteria and it died
Square 3: He injected the mouse with the virulent bacteria and heated it thinking it would kill the virulent part of the bacteria and the mouse lived
Square 4: This was the transcendent square and was the shock of the experiment which lead to the revelation. The fourth square is always transcendent. Griffith then injected the mouse with the heated virulent bacteria and the non virulent bacteria. Since both of them had not killed the mouse he thought the mouse would survive. But he found that the mouse died and he found deadly bacteria in their blood. This means that the genes of the bacteria must have carried the DNA although Griffith did not know this and it took until the discovery of genes for this to be understood. He discovered something in the heated bacteria survived and transformed into killer cells. He had discovered genes and gene transfer.
This experiment is one of the most legendary experiments in biology history. It is no coincidence that the quadrant model is reflected.


Structural homogeneity has been able to partially distinguish between cytokines that do not demonstrate a considerable degree of redundancy so that they can be classified into four types:


The four-α-helix bundle family: member cytokines have three-dimensional structures with four bundles of α-helices. This family, in turn, is divided into three sub-families:

the IL-2 subfamily

the interferon (IFN) subfamily

the IL-10 subfamily.

The first of these three, the IL-2 subfamily, is the largest. It contains several non-immunological cytokines including erythropoietin (EPO) and thrombopoietin (TPO). Furthermore, four-α-helix bundle cytokines can be grouped into long-chain and short-chain cytokines.[citation needed]

the IL-1 family, which primarily includes IL-1 and IL-18

the IL-17 family, which has yet to be completely characterized, though member cytokines have a specific effect in promoting proliferation of T-cells that cause cytotoxic effects.

the cysteine-knot cytokines include members of the transforming-growth-factor-beta superfamily, including TGF-β1, TGF-β2 and TGF-β3.



The four-α-helix bundle family: member cytokines have three-dimensional structures with four bundles of α-helices.

A mechanoreceptor is a sensory receptor that responds to mechanical pressure or distortion. Normally there are four main types in glabrous mammalian skin: lamellar corpuscles, tactile corpuscles, Merkel nerve endings, and bulbous corpuscles. There are also mechanoreceptors in hairy skin, and the hair cells in thoreceptors of primates like rhesus monkeys and other mammals are similar to those of humans and also studied even in early 20th century anatomically and neurophysiologically.[1]


The medial collateral ligament, posterior cruciate ligament, anterior cruciate ligament, and lateral collateral ligament are the four primary ligaments of the knee


The fourth is different and often not mentioned


The hamstrings are a group of four muscles on the back of the thigh. Three of them are two-joint muscles (performing both knee flexion and hip extension) while the fourth performs only knee flexion. As a group, the hamstrings can therefore be trained by exercises that involve either hip extension or knee flexion.


The four hamstrings muscles are: the biceps femoris (long head), the biceps femoris (short head), the semitendinosus, and the semimembranosus. The two biceps femoris muscles are located on the lateral part of the thigh. The semitendinosus and the semimembranosus are located on the medial part of the thigh.

The ventricular system is a set of four interconnected cavities (ventricles) in the brain, where the cerebrospinal fluid (CSF) is produced. Within each ventricle is a region of choroid plexus, a network of ependymal cells involved in the production of CSF. The ventricular system is continuous with the central canal of the spinal cord (from the fourth ventricle) allowing for the flow of CSF to circulate. All of the ventricular system and the central canal of the spinal cord is lined with ependyma, a specialised form of epithelium.
Some of the common names applied to this snake are terciopelo, fer-de-lance,[2] barba amarilla (Guatemala, Honduras; "yellow beard"), equis (Ecuador & Panama; "x"),[5] taya equis (Colombia), cuaima (Venezuela), nauyaca (México; from Nahuatl nahui, four, and yacatl, nose; "four noses"),[6] and yellow-jaw tommygoff (Belize).

In terms of anatomy, the basal ganglia are divided by anatomists into four distinct structures, depending on how superior or rostral they are (in other words depending on how close to the top of the head they are): Two of them, the striatum and the pallidum, are relatively large; the other two, the substantia nigra and the subthalamic nucleus, are smaller. In the illustration to the right, two coronal sections of the human brain show the location of the basal ganglia components. Of note, and not seen in this section, the subthalamic nucleus and substantia nigra lie farther back (posteriorly) in the brain than the striatum and pallidum.


Aulus Cornelius Celsus (c. 25 BC – c. 50 AD) was a Roman encyclopaedist, known for his extant medical work, De Medicina, which is believed to be the only surviving section of a much larger encyclopedia. The De Medicina is a primary source on diet, pharmacy, surgery and related fields, and it is one of the best sources concerning medical knowledge in the Roman world.

Aulus Cornelius Celsus is credited with recording the cardinal signs of inflammation known as "Celsus tetrad": calor (warmth), dolor (pain), tumor (swelling) and rubor (redness and hyperaemia). He goes into great detail regarding the preparation of numerous ancient medicinal remedies including the preparation of opioids. In addition, he describes many 1st century Roman surgical procedures which included removal of a cataract, treatment for bladder stones, and the setting of fractures.

Chiasma means cross

A chiasma (plural: chiasmata), in genetics, is thought to be the point where two homologous non-sister chromatids exchange genetic material during chromosomal crossover during meiosis (sister chromatids also form chiasmata between each other (also known as a chi structure), but because their genetic material is identical, it does not cause any change in the resulting daughter cells). The chiasmata become visible during the diplotene stage of prophase I of meiosis, but the actual "crossing-over" of genetic material is thought to occur during the previous pachytene stage. When each tetrad, which is composed of two pairs of sister chromatids, begins to split, the only points of contact are at the chiasmata.
Chiasma means cross

Chiasm means cross

The optic chiasm or optic chiasma (pronunciation: /ɒptɪk kaɪæzəm/; Greek χίασμα, "crossing", from the Greek χιάζω 'to mark with an X', after the Greek letter 'Χ', chi) is the part of the brain where the optic nerves partially cross. The optic chiasm is located at the bottom of the brain immediately below the hypothalamus.[1] The optic chiasm is found in all vertebrates, although in cyclostomes (lampreys and hagfishes) it is located within the brain.[2] [3]


Tetrad is another word for chromosomes, which carry genetic information for all creatures. It is no coincidence they resemble the quadrant.

Prophase I is typically the longest phase of meiosis. During prophase I, homologous chromosomes pair and exchange DNA in a process called homologous recombination. This often results in chromosomal crossover. This process is critical for pairing between homologous chromosomes and hence for accurate segregation of the chromosomes at the first meiosis division. The new combinations of DNA created during crossover are a significant source of genetic variation, and result in new combinations of alleles, which may be beneficial. The paired and replicated chromosomes are called bivalents or tetrads, which have two chromosomes and four chromatids, with one chromosome coming from each parent. The process of pairing the homologous chromosomes is called synapsis. At this stage, non-sister chromatids may cross-over at points called chiasmata (plural; singular chiasma).[10] Prophase I has historically been divided into a series of substages which are named according to the appearance of chromosomes

Four cells are created, one is different.

Meiosis Listeni/maɪˈoʊsᵻs/ is a specialized type of cell division that reduces the chromosome number by half, creating four haploid cells, each genetically distinct from the parent cell that gave rise to them.[1] This process occurs in all sexually reproducing single-celled and multicellular eukaryotes, including animals, plants, and fungi.[2][3][4][5] Errors in meiosis resulting in aneuploidy are the leading known cause of miscarriage and the most frequent genetic cause of developmental disabilities.[6]


In meiosis, DNA replication is followed by two rounds of cell division to produce four potential daughter cells, each with half the number of chromosomes as the original parent cell. The two meiotic divisions are known as Meiosis I and Meiosis II. Before meiosis begins, during S phase of the cell cycle, the DNA of each chromosome is replicated so that it consists of two identical sister chromatids, which remain held together through sister chromatid cohesion. This S-phase can be referred to as "premeiotic S-phase" or "meiotic S-phase." Immediately following DNA replication, meiotic cells enter a prolonged G2-like stage known as meiotic prophase. During this time, homologous chromosomes pair with each other and undergo genetic recombination, a programmed process in which DNA is cut and then repaired, which allows them to exchange some of their genetic information. A subset of recombination events results in crossovers, which create physical links known as chiasmata (singular: chiasma, for the Greek letter Chi (X)) between the homologous chromosomes. In most organisms, these links are essential to direct each pair of homologous chromosomes to segregate away from each other during Meiosis I, resulting in two haploid cells that have half the number of chromosomes as the parent cell. During Meiosis II, the cohesion between sister chromatids is released and they segregate from one another, as during mitosis. In some cases all four of the meiotic products form gametes such as sperm, spores, or pollen. In female animals, three of the four meiotic products are typically eliminated by extrusion into polar bodies, and only one cell develops to produce an ovum.




In females "three of the four meiotic products are eliminated"- "one of the four becomes the ovum"

The tetrad is the four spores of a yeast, other Ascomycota or Chlamydomonas produced after meiosis. After parent haploids mate, they produce diploids. Under appropriate environmental conditions, diploids sporulate and undergo meiosis. The meiotic products, spores, remain packaged in the parental cell body to produce the tetrad. If the two parents have a mutation in two different genes, the tetrad can segregate these genes as the parental ditype (PD), the non-parental ditype (NPD) or as the tetratype (TT).[1]

Tetrad analysis can be used to confirm whether a phenotype is caused by a specific mutation, construction of strains, and for investigating gene interaction. Since the frequency of tetrad segregation types is influenced by the recombination frequency for the two markers, the segregation data can be used to calculate the genetic distance between the markers if they are close on the same chromosome. Tetrad analyses have also contributed to detection and study of the phenomena of gene conversion and post-meiotic segregation.[2] These studies have proven central to understanding the mechanism of meiotic recombination, which in turn is a key to understanding the adaptive function of sexual reproduction. The use of tetrads in fine-structure genetic analysis is described in the articles Neurospora crassa and Gene conversion.
General procedure[edit]
Crosses are performed between haploid MATa and MATα mating strains, then the resulting diploids are transferred to sporulation media to form a tetrad containing four haploid spores. Tetrads can then be prepared with Zymolyase, or another enzyme, to digest the wall of the ascus. The spores are then separated with a micromanipulator needle and deposited in separate positions on a petri dish.
Traditionally, tetrad dissection has a reputation as "dark art".[3] However, instruments have since been developed specifically for tetrad dissection; the most advanced allow easy and semi-automated separation of tetrads [2] . Most micromanipulators use a glass fiber needle to which the spores adhere due to the formation of a water meniscus between the agar and the needle.

A theory associated with James Cossar Ewart in Scotland and Johann Ulrich Duerst in Germany postulated three primitive horse types, considered subspecies of Equus caballus, as ancestors of modern breeds of horse. They were:[4]

Square 1: "Forest Horse", Equus caballus germanicus, descendant of a "Diluvial Horse", Equus caballus silvaticus

Square 2: Asiatic Wild Horse or Przewalski horse, then considered Equus caballus przewalskii

Square 3: Tarpan, then considered Equus caballus gmelini.

Square 4: To these Elwyn Hartley Edwards adds a fourth, the "Tundra Horse", supposedly ancestor of the Yakut pony, and "largely unconsidered by hippologists".


American paleontologist Deb Bennett[5][6] postulated that the early form of E. caballus developed into seven subspecies,[7] of which four supposedly contributed most to the ancestry of the domesticated horse, both directly and via assorted crossbred lineages between them.[8] These were:

"Warmblood subspecies", Equus caballus mosbachensis, the oldest hypothetical subspecies, supposedly ancestor of the Latvian horse, Groningen horse and some warmblood breeds.

"Draft subspecies", Equus caballus caballus, ancestor of the Exmoor Pony, Shetland pony, Suffolk Punch and Belgian horse.

"Oriental subspecies", Equus caballus pumpelli, adapted to arid climates, thought to be the progenitor of the modern Arabian horse, Plateau Persian and Marwari horse.

"Tarpan", Equus caballus gmelini[9] or Equus caballus ferus, supposed ancestor of Przewalski's Horse as well as the Konik, Vyatka horse, Hucul and most Mongolian horses.


European scholars such as Jimmy Speed, Ruy d'Andrade, Hermann Ebhardt and Edward Skorkowski, postulated four basic body types, which were not considered to be named species.[4] They were:

Pony Type 1, in northwestern Europe, resistant to cold and wet, similar to the modern Exmoor pony

Pony Type 2, in northern Eurasia, larger than type 1, resistant to cold, similar to the modern Highland pony and Fjord horse

Horse Type 1, in central Asia, resistant to heat and drought, similar to the modern Sorraia and Akhal-Teke

Horse Type 2, in western Asia, small and fine-boned, resistant to heat, similar to the modern Caspian horse.


The horse is the animal whose family tree is known to the highest precision by biologists.

Before the availability of DNA techniques to resolve the questions related to the domestication of the horse, various hypothesis were proposed. One classification was based on body types and conformation, suggesting the presence of four basic prototypes, labeled the "Tarpan", "Forest horse", Draft and "Oriental", each of which was hypothesized to have adapted to their environment prior to domestication. However, more recent studies suggest that all domesticated horses originated from a single wild species and that the different body types of horses were entirely a result of selective breeding after domestication,[3] or possibly landrace adaptation.

Before the availability of DNA techniques to resolve the questions related to the domestication of the horse, various hypotheses were proposed. One classification was based on body types and conformation, suggesting the presence of four basic prototypes that had adapted to their environment prior to domestication. Another hypothesis held that the four prototypes originated from a single wild species and that all different body types were entirely a result of selective breeding after domestication. However, the lack of a detectable substructure in the horse has resulted in a rejection of both hypotheses


All horses move naturally with four basic gaits: the four-beat walk, which averages 6.4 kilometres per hour (4.0 mph); the two-beat trot or jog at 13 to 19 kilometres per hour (8.1 to 11.8 mph) (faster for harness racing horses); the canter or lope, a three-beat gait that is 19 to 24 kilometres per hour (12 to 15 mph); and the gallop.[80] The gallop averages 40 to 48 kilometres per hour (25 to 30 mph),[81] but the world record for a horse galloping over a short, sprint distance is 88 kilometres per hour (55 mph).[82] Besides these basic gaits, some horses perform a two-beat pace, instead of the trot.[83] There also are several four-beat "ambling" gaits that are approximately the speed of a trot or pace, though smoother to ride. These include the lateral rack, running walk, and tölt as well as the diagonal fox trot. Ambling gaits are often genetic in some breeds, known collectively as gaited horses. Often, gaited horses replace the trot with one of the ambling gaits.

16 is the squares of the quadrant model. The comet presented a 12 plus four pattern, which is the quadrant modle pattern. I studied comet landings and all sorts of stuff and saw the quadrant model everywhere, but can't remember a lot of it now


Results from the Rosetta and Philae spacecraft show that the nucleus of 67P/Churyumov–Gerasimenko has no magnetic field, which suggests that magnetism may not have played a role in the early formation of planetesimals.[30][31] Further, the ALICE spectrograph on Rosetta determined that electrons (within 1 km (0.62 mi) above the comet nucleus) produced from photoionization of water molecules by solar radiation, and not photons from the Sun as thought earlier, are responsible for the degradation of water and carbon dioxide molecules released from the comet nucleus into its coma.[32][33] Instruments on the Philae lander found at least sixteen organic compounds at the comet's surface, four of which (acetamide, acetone, methyl isocyanate and propionaldehyde) have been detected for the first time on a comet…/receptors-in-the-skin-are-sen…/…

Purebred dogs of one breed are genetically distinguishable from purebred dogs of other breeds, but the means by which kennel clubs classify dogs is unsystematic. Systematic analyses of the dog genome has revealed only four major types of dogs that can be said to be statistically distinct.These include the "old world dogs" (e.g., Malamute and Shar Pei), "Mastiff"-type (e.g., English Mastiff), "herding"-type (e.g., Border Collie), and "all others" (also called "modern"- or "hunting"-type).
I had an English Mastiff growing up.

The kangaroo /ˌkæŋɡəˈruː/ is a marsupial from the family Macropodidae (macropods, meaning "large foot"). In common use the term is used to describe the largest species from this family, especially those of the genus Macropus: the red kangaroo, antilopine kangaroo, eastern grey kangaroo, and western grey kangaroo. Kangaroos are endemic to Australia. The Australian government estimates that 34.3 million kangaroos lived within the commercial harvest areas of Australia in 2011, up from 25.1 million one year earlier.
There are four species that are commonly referred to as kangaroos:
The red kangaroo (Macropus rufus) is the largest surviving marsupial anywhere in the world. The Red Kangaroo occupies the arid and semi-arid centre of the country. The highest population densities of the Red Kangaroo occur in the rangelands of western New South Wales. Red kangaroos are commonly mistaken as the most abundant species of kangaroo, but eastern greys actually have a larger population.[18] A large male can be 2 metres (6 ft 7 in) tall and weigh 90 kg (200 lb).[19]
The eastern grey kangaroo (Macropus giganteus) is less well-known than the red (outside Australia), but the most often seen, as its range covers the fertile eastern part of the country. The range of the Eastern Grey Kangaroo extends from the top of the Cape York Peninsula in north Queensland down to Victoria, as well as areas of south-eastern Australia and Tasmania. Population densities of Eastern Grey Kangaroos usually peak near 100 per km2 in suitable habitats of open woodlands. Populations are more limited in areas of land clearance, such as farmland, where forest and woodland habitats are limited in size or abundance.[18]
The western grey kangaroo (Macropus fuliginosus) is slightly smaller again at about 54 kg (119 lb) for a large male. It is found in the southern part of Western Australia, South Australia near the coast, and the Darling River basin. The highest population densities occur in the western Riverina district of New South Wales and in western areas of the Nullarbor Plain in Western Australia. Populations may have declined, particularly in agricultural areas. The species has a high tolerance to the plant toxin sodium fluoroacetate, which indicates a possible origin from the south-west region of Australia.[18]
The antilopine kangaroo (Macropus antilopinus) is, essentially, the far-northern equivalent of the eastern and western grey kangaroos. It is sometimes referred to as the ‘Antilopine Wallaroo,’ but in behaviour and habitat it is more similar to Red and grey kangaroos. Like them, it is a creature of the grassy plains and woodlands, and gregarious. Their name comes from their fur, which is similar in colour and texture to that of antelopes. Characteristically, the noses of males swell behind the nostrils. This enlarges nasal passages and allows them to release more heat in hot and humid climates

Reptile Classification
Today, scientists classify reptiles into four major groups known as "orders." These four reptile orders are as follows:

Crocodilia — crocodiles, gharials, caimans and alligators: 23 species
Sphenodontia — tuataras from New Zealand: 2 species
Squamata — lizards, snakes and amphisbaenids ("worm-lizards"): about 7,900 species
Testudines — turtles and tortoises: approximately 300 species

Read more:


The 2010 Sharm el-Sheikh shark attacks were a series of attacks by sharks on swimmers off the Red Sea resort of Sharm el-Sheikh, Egypt. On 1 December 2010, three Russians and one Ukrainian were seriously injured within minutes of each other. This was the first four squares. The fourth was different. After this the beaches were closed for a long time and authorities went on a killing spree killing all of the sharks that they could find in the area. Then the beaches were reopened and right when they were reopeneda 5 December 2010 a German woman was killed, when they were attacked while wading or snorkeling near the shoreline. The attacks were described as "unprecedented" by shark experts. It was seen as bizarre as nothing like that had ever happened before. The fifth is always ultra transcendent the fourth is always different.

In response to the attacks, beaches in the popular tourist resort were closed for over a week, dozens of sharks were captured and killed, and the local government issued new rules banning shark feeding and restricting swimming. A variety of theories were put forward to explain the attacks. By late December 2010, the most plausible theory to emerge was that the dumping of sheep carcasses in the Red Sea by a livestock transport during the Islamic festival of Eid al-Adha had attracted the sharks to the shore. Other theories focused on overfishing in the Red Sea or on the illegal or inadvertent feeding of sharks or smaller fish close to the shore, which produced scents that attracted more sharks.

The attacks fit the quadrant model pattern.

The attacks also sparked conspiracy theories about possible Israeli involvement. Egyptian television broadcast claims that Israeli divers captured a shark with a GPS unit planted on its back. Describing the theory as "sad", Professor Mahmoud Hanafy of the Suez Canal University pointed out that GPS devices are used by marine biologists to track sharks, not to remote-control them. Governor Mohamed Abdel Fadil Shousha himself ultimately said he thought the dumping of sheep carcasses during the Islamic festival of Eid al-Adha on 16 November was the most likely explanation.

These are the two very famous shark attack sprees and they fit the quadrant model pattern.



The fourth is always different (the white tip)

Only a few sharks are dangerous to humans. Out of more than 480 shark species, only three are responsible for two-digit number of fatal unprovoked attacks on humans: the great white, tiger and bull; however, the oceanic whitetip has probably killed many more castaways, not recorded in the statistics.

The great white shark is one of only four kinds of sharks that have been involved in a significant number of fatal unprovoked attacks on humans.

Cockroaches are widespread, and are one of the hardest household pests to control. Four types of cockroaches cause problems for people. These are the four cockroaches known as pests.
Brown Banded


Ingerophrynus quadriporcatus is a species of toad in the Bufonidae family. Its common names are long-glanded toad,[4] four-ridged toad and greater Malacca toad. It is found in Peninsular Malaysia, Singapore, Borneo (Sabah, Brunei, Sarawak, and Kalimantan), Sumatra, and the Natuna Islands. Its natural habitats are swamp forests, but it has also been found on rubber plantations. It breeds in standing water.

Many chelicerates have four pairs of walking legs. These include scorpions and spiders.…/2010_Sharm_El_Sheikh_shark_attac…

The 2010 Sharm el-Sheikh shark attacks were a series of attacks by sharks on swimmers off the Red Sea resort of Sharm el-Sheikh, Egypt. On 1 December 2010, three Russians and one Ukrainian were seriously injured within minutes of each other. This was the first four squares. The fourth was different. After this the beaches were closed for a long time and authorities went on a killing spree killing all of the sharks that they could find in the area. Then the beaches were reopened and right when they were reopeneda 5 December 2010 a German woman was killed, when they were attacked while wading or snorkeling near the shoreline. The attacks were described as "unprecedented" by shark experts. It was seen as bizarre as nothing like that had ever happened before. The fifth is always ultra transcendent the fourth is always different.
In response to the attacks, beaches in the popular tourist resort were closed for over a week, dozens of sharks were captured and killed, and the local government issued new rules banning shark feeding and restricting swimming. A variety of theories were put forward to explain the attacks. By late December 2010, the most plausible theory to emerge was that the dumping of sheep carcasses in the Red Sea by a livestock transport during the Islamic festival of Eid al-Adha had attracted the sharks to the shore. Other theories focused on overfishing in the Red Sea or on the illegal or inadvertent feeding of sharks or smaller fish close to the shore, which produced scents that attracted more sharks.
The attacks fit the quadrant model pattern.
The attacks also sparked conspiracy theories about possible Israeli involvement. Egyptian television broadcast claims that Israeli divers captured a shark with a GPS unit planted on its back. Describing the theory as "sad", Professor Mahmoud Hanafy of the Suez Canal University pointed out that GPS devices are used by marine biologists to track sharks, not to remote-control them. Governor Mohamed Abdel Fadil Shousha himself ultimately said he thought the dumping of sheep carcasses during the Islamic festival of Eid al-Adha on 16 November was the most likely explanation.
These are the two very famous shark attack sprees and they fit the quadrant model pattern.


I described that dragonflies are known for their flight by biologists and studied for their amazing flight capacities and that their flight reflects the quadrant model pattern. The mantis shrimp is studied by biologists for its sight, which reflects the quadrant model pattern. Ruminants like giraffes and cows are known for having to digest cellulose which other animals cannot do so they have four stomachs, reflecting the quadrant pattern.

The catfish is studied by biologists for its incredible capacity of perception called chemical perception. Catfish are known for their amazing ability to eat in muddy water where it cannot see. The way that it detects food is through its four pairs of barbels.

Catfish also have a maxilla reduced to a support for barbels; this means that they are unable to protrude their mouths as other fish such as carp.

Catfish may have up to four pairs of barbels: nasal, maxillary (on each side of mouth), and two pairs of chin barbels, even though pairs of barbels may be absent depending on the species. Catfish barbels always come as pairs. Many larger catfish also have chemoreceptors across their entire bodies, which means they "taste" anything they touch and "smell" any chemicals in the water. "In catfish, gustation plays a primary role in the orientation and location of food". Because their barbels and chemoreception are more important in detecting food, the eyes on catfish are generally small. Like other ostariophysans, they are characterized by the presence of a Weberian apparatus. Their well-developed Weberian apparatus and reduced gas bladder allow for improved hearing as well as sound production.

Catfish are known for their capacity to eat and survive in muddy waters. The four pairs of barbels are what makes it possible for a catfish to live.

The channel catfish is an example of a catfish with four pairs of barbels.


Ciliates reproduce asexually, by various kinds of fission. An example of a ciliate is paramecium. During fission, the micronucleus undergoes mitosis and the macronucleus elongates and splits in half (except among the Karyorelictean ciliates, whose macronuclei do not divide). The cell then divides in two, and each new cell obtains a copy of the micronucleus and the macronucleus.

The process of conjugation reflects the quadrant model pattern.

During conjugation, two cells form a bridge between their cytoplasms, the micronuclei undergo meiosis, the macronuclei disappear, and the haploid micronuclei are exchanged over the bridge. In some ciliates (such as Vorticella), conjugating cells become permanently fused, and one conjugant is absorbed by the other. In most ciliate groups, however, the cells separate after conjugation, and both form new macronuclei from their micronuclei. Conjugation and autogamy are always followed by fission.

In general the process is as follows:

Compatible mating strains meet and partly fuse.

The micronuclei undergo meiosis producing four micronuclei per cell.

Three of these micronuclei disintegrate. The fourth undergoes mitosis. Notice how this is the quadrant pattern. Three disintegrate, the fourth which is different undergoes mitosis.

The two cells exchange a micronucleus.

The cells then separate.

The micronuclei in each cell fuse.

This is followed by mitosis which occurs three times giving rise to eight micronuclei.

Four of the new micronuclei transform into macronuclei

Finally binary fission occurs twice yielding four daughter cells.

At the end four daughter cells are produced

16 is the squares of the quadrant model- four rows of four 16- the mantis shrimp has the most complex vision of any creature and has four rows of four photoreceptors- the fourth row is different.

The mantis shrimp, or stomatopod, is used in biology as an example of an organism with an extraordinary visual mechanism. They are upheld by biologists as the organism that sees the world in an incredible way and of an organism that has developed a completely different mechanism of seeing than that of humans. But the seeing mechanism of the mantis shrimp fits the quadrant model pattern.
Compared to the three types of color receptive cones that humans possess (and one rod) in their eyes, the eyes of a mantis shrimp carry 16 types of color receptive cones. It was once thought that this gives the crustacean the ability to recognize colors that are unimaginable by other species.
The midband region of its eye is made up of six rows of specialised ommatidia. Four rows carry up to 16 different photoreceptor pigments, 12 for colour sensitivity, others for colour filtering. The vision of the mantis shrimp can perceive both polarised light and multispectral images. Their eyes (mounted on mobile stalks and capable of moving independently of each other) are similarly variably colored and are considered to be the most complex eyes in the animal kingdom
Rows 1–4 of the midband are specialised for color vision, from ultra-violet to longer wavelengths. Their UV-vision can detect five different frequency bands in the deep ultraviolet. To do this they use two photoreceptors in combination with four different colour filters.[
It has four rows with 16 different photoreceptors. The four is the quadrant. 16 is the number of squares in the quadrant model. 12 of the squares are for color sensitivity. That is the first three quadrants. The fourth quadrant is always different. The fourth quadrant has four photoreceptors for colour filtering. Therefore the mantis shrimp, the creature that biologists see as having the most special and unique visual mechanism, has a visual mechanism that fulfills the quadrant model pattern.
Some species have at least 16 different photoreceptor types, which are divided into four classes (their spectral sensitivity is further tuned by colour filters in the retinas), 12 of them for colour analysis in the different wavelengths (including six which are sensitive to ultraviolet light) and four of them for analysing polarised light. By comparison, most humans have only four visual pigments, of which three are dedicated to see colour, and the human lenses block ultraviolet light. The visual information leaving the retina seems to be processed into numerous parallel data streams leading into the central nervous system, greatly reducing the analytical requirements at higher levels.
The species Gonodactylus smithii is the only organism known to simultaneously detect the four linear and two circular polarization components required to measure all four Stokes parameters, which yield a full description of polarization. It is thus believed to have optimal polarization vision.
The vision of the stomatopod is the quadrant model pattern, and for biologists, that is what the creature is special for and what it is studied for.

From the top it looks like a quadrant


The medusa form of a box jellyfish has a squarish, box-like bell. From each of the four lower corners of this hangs a short pedalium or stalk which bears one or more long, slender, hollow tentacles.The interior of the bell is known as the gastrovascular cavity. It is divided by four equidistant septa into a central stomach and four gastric pockets.
16 squares quadrant model
Chiropsalmus quadrumanus, commonly known as the four-handed box jellyfish, is a species of box jellyfish in class Cubozoa. It is found in the west Atlantic Ocean, the Gulf of Mexico and the Pacific Ocean. The sting is venomous and dangerous to humans, especially children.

Chiropsalmus quadrumanus is a cube-shaped, colourless, transparent jellyfish with a diameter of about 14 centimetres (5.5 in) and height a little less than this. The body is composed of a gelatinous material and the top edges are rounded while the top surface is flat. Bundles of 7 to 9 tentacles dangle from pedalia, palmate appendages at the four lower corners of the bell, with a tentacle on each "finger". The outer two tentacles are pinkish and the inner ones yellowish white and they can be up to 3 to 4 metres (9.8 to 13.1 ft) long. Halfway up the inside of the bell is the velarium, a horizontal ring of tissue partially blocking the aperture. The manubrium is a central column hanging down inside the bell with the mouth at its tip. The rounded stomach has four pouches connecting to radial sinuses along the edges of the bell. The gonads are on either side of the radial canals.[2]

The long tentacles of Chiropsalmus quadrumanus are armed with nematocysts, the purpose of which is to capture prey such as small fish and to deter predators. They can inflict an extremely painful sting on people that encounter them. There is a documented case of a four-year-old boy in the Gulf of Mexico dying within forty minutes of being stung.[5][6] Of forty nine people stung by jellyfish off the coast of Brazil over a five-year period, twenty were by identifiable species. Sixteen of these were identified as being caused by Chiropsalmus quadrumanus and four by the Portuguese man o' war (Physalia physalis). All these stings were linear in nature, causing both intense pain and systemic symptoms.[7] Apart from pain, the symptoms include cardiac dysfunction and respiratory depression. The rash lasts for several months. Antivenom administered within a few hours relieves the pain somewhat, reduces the severity of the rash, and improves other symptoms. In extreme cases, cardiopulmonary resuscitation can be effective if started promptly.[8]

It looks like a quadrants

Aurelia aurita (also called the moon jelly, moon jellyfish, common jellyfish, or saucer jelly) is a widely studied species of the genus Aurelia. All species in the genus are closely related, and it is difficult to identify Aurelia medusae without genetic sampling; most of what follows applies equally to all species of the genus.

The jellyfish is translucent, usually about 25–40 cm (10–16 in) in diameter, and can be recognized by its four horseshoe-shaped gonads, easily seen through the top of the bell. It feeds by collecting medusae, plankton, and mollusks with its tentacles, and bringing them into its body for digestion. It is capable of only limited motion, and drifts with the current, even when swimming.

It has four bright gonads that are under the stomachègne_Animal

From the website quadriformisratio
Cuvier's most admired work was his Le Règne Animal. It appeared in four octavo volumes in 1817; a second edition in five volumes was brought out in 1829–1830. In this classic work, Cuvier presented the results of his life's research into the structure of living and fossil animals. With the exception of the section on insects, in which he was assisted by his friend Latreille, the whole of the work was his own. It was translated into English many times, often with substantial notes and supplementary material updating the book in accordance with the expansion of knowledge
For the Règne Animal, using evidence from comparative anatomy and palaeontology—including his own observations—Cuvier divided the animal kingdom into four principal body plans. Taking the central nervous system as an animal's principal organ system which controlled all the other organ systems such as the circulatory and digestive systems, Cuvier distinguished four types of organisation of an animal's body:
I. with a brain and a spinal cord (surrounded by parts of the skeleton)
II. with organs linked by nerve fibres
III. with two longitudinal, ventral nerve cords linked by a band with two ganglia positioned below the oesophagus
IV. with a diffuse nervous system which is not clearly discernible
Grouping animals with these body plans resulted in four "embranchements" or branches (vertebrates, molluscs, the articulata that he claimed were natural (arguing that insects and annelid worms were related) and zoophytes (radiata)). This effectively broke with the mediaeval notion of the continuity of the living world in the form of the great chain of being. It also set him in opposition to both Saint-Hilaire and Lamarck: Lamarck claimed that species could transform through the influence of the environment, while Saint-Hilaire argued in 1820 that two of Cuvier's branches, the molluscs and radiata, could be united via various features, while the other two, articulata and vertebrates, similarly had parallels with each other. Then in 1830, Saint-Hilaire argued that these two groups could themselves be related, implying a single form of life from which all others could have evolved, and that Cuvier's four body plans were not fundamental.
The classification adopted by Cuvier to define the natural structure of the animal kingdom, including both living and fossil forms,[17] was as follows, the list forming the structure of the Règne Animal. Where Cuvier's group names correspond (more or less) to modern taxa, these are named, in English if possible, in parentheses. The table from the 1828 Penny Cyclopaedia indicates species that were thought to belong to each group in Cuvier's taxonomy.
I. Vertébrés. (Vertebrates)
Mammifères (Mammals): 1. Bimanes, 2. Quadrumanes, 3. Carnassiers (Carnivores), 4. Rongeurs (Rodents), 5. Édentés (Edentates), 6. Pachydermes (Pachyderms), 7. Ruminants (Ruminants), 8. Cétacés (Cetaceans).
Oiseaux (Birds): 1. Oiseaux de proie (Birds of prey), 2. Passereaux (Passerines), 3. Grimpeurs (Piciformes), 4. Gallinacés (Gallinaceous birds), 5. Échassiers (Waders), 6. Palmipèdes (Anseriformes).
Reptiles (Reptiles, inc. Amphibians): 1. Chéloniens (Chelonii), 2. Sauriens (Lizards), 3. Ophidiens (Snakes), 4. Batraciens (Amphibians).
Poissons (Fishes): 1. Chrondroptérygiens à branchies fixes (Chondrichthyes), 2. Sturioniens ou Chrondroptérygiens à branchies libres (Sturgeons), 3. Plectognates (Tetraodontiformes), 4. Lophobranches (Syngnathidae), 5. Malacoptérygiens abdominaux, 6. Malacoptérygiens subbrachiens, 7. Malacoptérygiens apodes, 8. Acanthoptérygiens (Acanthopterygians).
II. Mollusques. (Molluscs)
Céphalopodes. (Cephalopods)
Ptéropodes. (Pteropods)
Gastéropodes (Gastropods): 1. Nudibranches (Nudibranchs), 2. Inférobranches, 3. Tectibranches, 4. Pulmonés (Pulmonata), 5. Pectinibranches, 6. Scutibranches, 7. Cyclobranches.
Acéphales (Bivalves etc.): 1. Testacés, 2. Sans coquilles.
Brachiopodes. (Brachiopods, now a separate phylum)
Cirrhopodes. (Barnacles, now in Crustacea)
III. Articulés. (Articulated animals: now Arthropods and Annelids)
Annélides (Annelids): 1. Tubicoles, 2. Dorsibranches, 3. Abranches.
Crustacés (Crustaceans): 1. Décapodes (Decapods), 2. Stomapodes (Stomatopods), 3. Amphipodes (Amphipods), 4. Isopodes (Isopods), 5. Branchiopodes (Branchiopods).
Arachnides (Arachnids): 1. Pulmonaires, 2. Trachéennes.
Insectes (Insects, inc. Myriapods): 1. Myriapodes, 2. Thysanoures (Thysanura), 3. Parasites, 4. Suceurs, 5. Coléoptères (Coleoptera), 6. Orthoptères (Orthoptera), 7. Hémiptères (Hemiptera), 8. Névroptères (Neuroptera), 9. Hyménoptères (Hymenoptera), 10. Lépidoptères (Lepidoptera), 11. Ripiptères (Strepsiptera), 12. Diptères (Diptera).
IV. Zoophytes. (Zoophytes, now Cnidaria] and other phyla)
Échinodermes (Echinoderms): 1. Pédicellés, 2. Sans pieds.
Intestinaux (Intestinal worms): 1. Cavitaires, 2. Parenchymateux.
Acalèphes (Jellyfish and other free-floating polyps): 1. Fixes, 2. Libres.
Polypes (Cnidaria): 1. Nus, 2. À polypiers.
Infusoires (Infusoria, various protistan phyla): 1. Rotifères (Rotifers), 2. Homogènes.
The book was in the library of HMS Beagle for Charles Darwin's voyage.[21] In The Origin of Species (1859), in a chapter on the difficulties facing the theory, Darwin comments that "The expression of conditions of existence,[b] so often insisted on by the illustrious Cuvier, is fully embraced by the principle of natural selection." In fact Darwin did not argue that God could not have created the first living organism, but Darwin did believe that organisms evolved.


The fourth domain is different


Characteristics of the three domains of life[edit]

A speculatively rooted tree for RNA genes, showing major branches Bacteria, Archaea, and Eukaryota

The three-domains tree and the Eocyte hypothesis(Two domains tree).[4]

Phylogenetic tree showing the relationship between the eukaryotes and other forms of life.[5] Eukaryotes are colored red, archaea green and bacteria blue.

Each of these three domains of life recognized by biologists today contain rRNA which is unique to them, and this fact in itself forms the basis of the three-domain system. While the presence of a nuclear membrane differentiates the Eukarya domain from the Archaea and Bacteria domains, both of which lack a nuclear membrane, distinct biochemical and RNA markers differentiate the Archaea and Bacteria domains from each other.


Archaea are prokaryotic cells which are typically characterized by membrane lipids that are branched hydrocarbon chains attached to glycerol by ether linkages. The presence of these ether linkages in Archaea adds to their ability to withstand extreme temperatures and highly acidic conditions, but many archea live in mild environments. Halophiles, organisms which thrive in highly salty environments, and hyperthermophiles, organisms which thrive in extremely hot environments, are examples of Archaea. Archaea evolved many cell sizes, but all are relatively small. Their size ranges from 0.1 to 15 μ diameter and up to 200 μ long. They are about the size of bacteria or similar to the size of a mitochondrion in a eukaryotic cell. Members of the genus Thermoplasma are the smallest of the archaea.


Even though bacteria are prokaryotic cells just like Archaea, their membranes are made of unbranched fatty acid chains attached to glycerol by ester linkages. Cyanobacteria and mycoplasmas are two examples of bacteria. They characteristically do not have ether linkages like Archaea, and they are grouped into a different category—and hence a different domain. There is a great deal of diversity in this domain, and between that and horizontal gene transfer, it is next to impossible to determine how many species of bacteria exist on the planet.


Organisms in the domain Eukarya are eukaryotic cells, or consist of them, which have membranes that are similar to those of bacteria. Eukaryotes are further grouped into Kingdom Fungi (yeast, mold, etc.), Kingdom Plantae (flowering plants, ferns, etc.) and Kingdom Animalia (insects, vertebrates, etc.) and the now-defunct, paraphyletic Kingdom Protista (algae, protozoans, etc.).

Not all Eukaryotes have a cell wall, and even in those which do, the walls do not contain peptidoglycan, which bacteria do have. While cells are organized into tissues in the kingdom Plantae as well as the kingdom Animalia, cell walls are never found in animal cells.

Exclusion of viruses[edit]

Main article: Virus

None of the three systems currently include non-cellular life. As of 2011 there is talk about Nucleocytoplasmic large DNA viruses possibly being a fourth branch domain of life, a view supported by researchers in 2012.[6]

Stefan Luketa in 2012 proposed a five-domain system, adding Prionobiota (acellular and without nucleic acid) and Virusobiota (acellular but with nucleic acid) to the traditional three domains.[2]

from wiki

The fourth is always transcendent

None of the three systems currently include non-cellular life. As of 2011 there is talk about Nucleocytoplasmic large DNA viruses possibly being a fourth branch domain of life, a view supported by researchers in 2012.[6]

Named by William Jackson Hooker in 1840, the name Tetracarpaea refers to the four conspicuous and separate carpels.[10] At that time, he wrote:


This beautiful little shrub is altogether new to me: but much as it differs in certain characters, both of the foliage and fructification, from the Order Cunoniaceae, I think it may safely be referred to it. The 4 carpels, which have suggested the Generic name, are perfectly free even in the earliest state of the ovary.


— William Jackson Hooker

The following description is based on information from several sources.[1][2][6][8][9]


Tetracarpaea tasmannica is a glabrous, evergreen, erect and bushy shrub. It is variable in height, usually from 1.5 to 6 dm, but sometimes attaining a height of 1 m and a width of 7 dm.


The leaves are elliptic to oblanceolate, about 25 mm long and 8 mm wide, on a petiole about 2 mm long. The veins are prominent and end near the margin. The margins are serrate or crenate. On both surfaces, the epidermis is covered by a thick cuticle.


The inflorescences are dense, erect, terminal racemes, up to 5 cm long. The flowers appear in autumn. They are bisexual, actinomorphic, and 5 to 10 mm wide. The 4 sepals persist to the maturity of the fruit. The 4 petals are white and spatulate in shape.


The stamens are either 4 or 8 in number. If 4, they are opposite (along the same radii as) the sepals. The anthers are basifixed.


The ovary is superior and consists of 4 carpels that are large compared to the rest of the flower. The carpels are usually separate, but occasionally 2 or 3 of them are fused at the base, or rarely, as far as halfway up. They are erect and stipitate with a suture along the ventral side. A placenta runs along each side of the suture and bears 1 to 3 rows of numerous, tiny ovules. The ovules have been described as having one integument[8] or two.[6]


The ovary hardly enlarges after anthesis. The fruit consists of 4 follicles joined at the base. The seeds are numerous and about ½ mm long.


These chloroplasts, which can be traced back directly to a cyanobacterial ancestor, are known as primary plastids[26] ("plastid" in this context means almost the same thing as chloroplast[9]). All primary chloroplasts belong to one of four chloroplast lineages—the glaucophyte chloroplast lineage, the amoeboid Paulinella chromatophora lineage, the rhodophyte (red algal) chloroplast lineage, or the chloroplastidan (green) chloroplast lineage.[27] The rhodophyte and chloroplastidan lineages are the largest,[16] with chloroplastidan (green) being the one that contains the land plants.[16]


Chloroplast lineages

A primary endosymbiosis

event gave rise to four main

lineages of chloroplasts in

the glaucophytes, Paulinella, chlorophyta,

and rhodophyta.[27]

Some of these algae were

subsequently engulfed by

other algae, becoming

secondary (or tertiary)



Cryptophytes, or cryptomonads are a group of algae that contain a red-algal derived chloroplast. Cryptophyte chloroplasts contain a nucleomorph that superficially resembles that of the chlorarachniophytes.[16] Cryptophyte chloroplasts have four membranes, the outermost of which is continuous with the rough endoplasmic reticulum. They synthesize ordinary starch, which is stored in granules found in the periplastid space—outside the original double membrane, in the place that corresponds to the red alga's cytoplasm. Inside cryptophyte chloroplasts is a pyrenoid and thylakoids in stacks of two.[14]


Signs and symptoms

Syphilis can present in one of four different stages: primary, secondary, latent, and tertiary,[3] and may also occur congenitally.[12] It was referred to as "the great imitator" by Sir William Osler due to its varied presentations.[3][13]




Primary chancre of syphilis at the site of infection on the penis

Primary syphilis is typically acquired by direct sexual contact with the infectious lesions of another person.[14] Approximately 3 to 90 days after the initial exposure (average 21 days) a skin lesion, called a chancre, appears at the point of contact. This is classically (40% of the time) a single, firm, painless, non-itchy skin ulceration with a clean base and sharp borders 0.3–3.0 cm in size.[3] The lesion may take on almost any form. In the classic form, it evolves from a macule to a papule and finally to an erosion or ulcer.[15] Occasionally, multiple lesions may be present (~40%),[3] with multiple lesions more common when coinfected with HIV. Lesions may be painful or tender (30%), and they may occur in places other than the genitals (2–7%). The most common location in women is the cervix (44%), the penis in heterosexual men (99%), and anally and rectally relatively commonly in men who have sex with men (34%).[15] Lymph node enlargement frequently (80%) occurs around the area of infection,[3] occurring seven to 10 days after chancre formation.[15] The lesion may persist for three to six weeks without treatment.[3]




Typical presentation of secondary syphilis with a rash on the palms of the hands


Reddish papules and nodules over much of the body due to secondary syphilis

Secondary syphilis occurs approximately four to ten weeks after the primary infection.[3] While secondary disease is known for the many different ways it can manifest, symptoms most commonly involve the skin, mucous membranes, and lymph nodes.[16] There may be a symmetrical, reddish-pink, non-itchy rash on the trunk and extremities, including the palms and soles.[3][17] The rash may become maculopapular or pustular. It may form flat, broad, whitish, wart-like lesions known as condyloma latum on mucous membranes. All of these lesions harbor bacteria and are infectious. Other symptoms may include fever, sore throat, malaise, weight loss, hair loss, and headache.[3] Rare manifestations include liver inflammation, kidney disease, joint inflammation, periostitis, inflammation of the optic nerve, uveitis, and interstitial keratitis.[3][18] The acute symptoms usually resolve after three to six weeks;[18] about 25% of people may present with a recurrence of secondary symptoms. Many people who present with secondary syphilis (40–85% of women, 20–65% of men) do not report previously having had the classic chancre of primary syphilis.[16]



Latent syphilis is defined as having serologic proof of infection without symptoms of disease.[14] It is further described as either early (less than 1 year after secondary syphilis) or late (more than 1 year after secondary syphilis) in the United States.[18] The United Kingdom uses a cut-off of two years for early and late latent syphilis.[15] Early latent syphilis may have a relapse of symptoms. Late latent syphilis is asymptomatic, and not as contagious as early latent syphilis.[18]




Person with tertiary (gummatous) syphilis. Bust in Musée de l'Homme, Paris.

Tertiary syphilis may occur approximately 3 to 15 years after the initial infection, and may be divided into three different forms: gummatous syphilis (15%), late neurosyphilis (6.5%), and cardiovascular syphilis (10%).[3][18] Without treatment, a third of infected people develop tertiary disease.[18] People with tertiary syphilis are not infectious.[3]


Gummatous syphilis or late benign syphilis usually occurs 1 to 46 years after the initial infection, with an average of 15 years. This stage is characterized by the formation of chronic gummas, which are soft, tumor-like balls of inflammation which may vary considerably in size. They typically affect the skin, bone, and liver, but can occur anywhere.[3]


Neurosyphilis refers to an infection involving the central nervous system. It may occur early, being either asymptomatic or in the form of syphilitic meningitis, or late as meningovascular syphilis, general paresis, or tabes dorsalis, which is associated with poor balance and lightning pains in the lower extremities. Late neurosyphilis typically occurs 4 to 25 years after the initial infection. Meningovascular syphilis typically presents with apathy and seizure, and general paresis with dementia and tabes dorsalis.[3] Also, there may be Argyll Robertson pupils, which are bilateral small pupils that constrict when the person focuses on near objects but do not constrict when exposed to bright light.


Cardiovascular syphilis usually occurs 10–30 years after the initial infection. The most common complication is syphilitic aortitis, which may result in aneurysm formation.[3]


The '16 cancers' campaign highlights the fact that smoking causes a range of cancers including liver, bowel, kidney, cervical and ovarian, and that you have one clear way to reduce your risk by quitting today.


The fourth is always different/transcendent


In 1953, Cambridge researchers Watson and Crick published a paper describing the interweaving ‘double helix’ DNA structure – the chemical code for all life.

Now, in the year of that scientific landmark’s 60th Anniversary, Cambridge researchers have published a paper proving that four-stranded ‘quadruple helix’ DNA structures – known as G-quadruplexes – also exist within the human genome. They form in regions of DNA that are rich in the building block guanine, usually abbreviated to ‘G’.

The findings mark the culmination of over 10 years investigation by scientists to show these complex structures in vivo – in living human cells – working from the hypothetical, through computational modelling to synthetic lab experiments and finally the identification in human cancer cells using fluorescent biomarkers.

The research, published today in Nature Chemistry and funded by Cancer Research UK, goes on to show clear links between concentrations of four-stranded quadruplexes and the process of DNA replication, which is pivotal to cell division and production.

By targeting quadruplexes with synthetic molecules that trap and contain these DNA structures – preventing cells from replicating their DNA and consequently blocking cell division – scientists believe it may be possible to halt the runaway cell proliferation at the root of cancer.

“We are seeing links between trapping the quadruplexes with molecules and the ability to stop cells dividing, which is hugely exciting,” said Professor Shankar Balasubramanian from the University of Cambridge’s Department of Chemistry and Cambridge Research Institute, whose group produced the research.

“The research indicates that quadruplexes are more likely to occur in genes of cells that are rapidly dividing, such as cancer cells. For us, it strongly supports a new paradigm to be investigated – using these four-stranded structures as targets for personalised treatments in the future.”

Physical studies over the last couple of decades had shown that quadruplex DNA can form in vitro – in the ‘test tube’, but the structure was considered to be a curiosity rather than a feature found in nature. The researchers now know for the first time that they actually form in the DNA of human cells.

“This research further highlights the potential for exploiting these unusual DNA structures to beat cancer – the next part of this pipeline is to figure out how to target them in tumour cells,” said Dr Julie Sharp, senior science information manager at Cancer Research UK.

“It’s been sixty years since its structure was solved but work like this shows us that the story of DNA continues to twist and turn.”

16 is the squares of the quadrant model


The Canon then describes when temperaments are unequal, in other words, illness. Avicenna separates these into two categories, which are fairly self explainable within the context of what he had already defined as the four temperaments.


A. Simple "intemperaments"[8]:63

Hot temperament (hotter than normal)

Cold temperament (colder than normal)

Dry temperament (drier than usual)

Moist temperament (more moist than usual)

B. Compound "intemperaments"

The compound intemperaments are where two things are wrong with the temperament, i.e. hotter and moister; hotter and drier; colder and moister; colder and drier. There are only four because something cannot be simultaneously hotter and colder or drier and moister. The four simple temperaments and four compound intemperaments can each be divided into "Those apart from any material substance" and "Those in which some material substance is concerned", for a total of sixteen intemperaments. Examples of the sixteen intemperaments are provided in the "third and fourth volumes."[8]:64
This is in one of my books
Avicenna begins part one by dividing theoretical medicine and medical practice. He describes what he says are the "four causes" of illness, based on Aristotelian philosophy: The material cause, the efficient cause, the formal cause, and the final cause:[8]:29–31
Material Cause Avicenna says that this cause is the human subject itself, the "members or the breath" or "the humours" indirectly.
Efficient Cause The efficient cause is broken up into two categories: The first is "Extrinsic", or the sources external to the human body such as air or the region we live in. The second efficient cause is the "Intrinsic", or the internal sources such as our sleep and "its opposite-the waking state", the "different periods of life", habits, and race.
Formal Cause The formal cause is what Avicenna called "the constitutions ; the compositions". According to Oskar Cameron Gruner, who provides a treatise within Avicenna's Canon of Medicine, this was in agreement with Galen who believed that the formal cause of illness is based upon the individual's temperament.
Final Cause The final cause is given as "the actions or functions".
Thesis II The Elements of Cosmology[edit]
Avicenna's thesis on the elements of the cosmos is described by Gruner as "the foundation of the whole Canon".[8]:39 Avicenna insists here that a physician must assume the four elements that are described by natural philosophy,[8]:34 although Avicenna makes it clear that he distinguishes between the "simple" element, not mixed with anything else, and what we actually experience as water or air, such as the sea or the atmosphere. The elements we experience are mixed with small amounts of other elements and are therefore not the pure elemental substances.[8]:202 The "light" elements are fire and air, while the "heavy" are earth and water:
The Earth Avicenna upholds Aristotelian philosophy by describing Earth as an element that is geocentric. The Earth is at rest, and other things tend towards it because of its intrinsic weight. It is cold and dry.[8]:35
The Water Water is described as being exterior to the sphere of the Earth and interior to the sphere of the Air, because of its relative density. It is cold and moist. "Being moist, shapes can be readily fashioned (with it), and as easily lost (and resolved)."[8]:35
The Air The position of Air above Water and beneath Fire is "due to its relative lightness". It is "hot and moist", and its effect is to "rarefy" and make things "softer".[8]:36
The (sphere of the) Fire Fire is higher than the other elements, "for it reaches to the world of the heavens". It is hot and dry; it traverses the substance of the air, and subdues the coldness of the two heavy elements; "by this power it brings the elementary properties into harmony."[8]:37
Thesis III The Temperaments[edit]
The Canon of Medicine divides the thesis on temperaments into three subsections; a general overview, one based on members of the body, and temperaments based on age.
I The Temperaments (General description)[edit]
The temperaments are reported to be the interaction between the four different element's qualities, such as the conflict between dryness, wetness, cold, and hot. Avicenna suggests that these qualities battle between each other until an equilibrium state is reached and this state is known as the temperaments.[8]:57–65
The Canon also adopted the ancient theory of Four Temperaments and extended it to encompass "emotional aspects, mental capacity, moral attitudes, self-awareness, movements and dreams." This expanded theory of four temperaments is given in the following table:[10]
Evidences of the four primary temperaments
Evidence Hot Cold Moist Dry
Morbid states Inflammations become febrile
Loss of vigour Fevers related to serous humour
Rheumatism Lassitude 
Functional power Deficient energy Deficient digestive power Difficult digestion 
Subjective sensations Bitter taste
Excessive thirst
Burning cardiac orifice Lack of desire for fluids Mucoid salivation
Sleepiness Insomnia, wakefulness
Physical signs High pulse rate,
approaching lassitude Flaccid joints Diarrhea
Swollen eyelids Rough skin
Acquired habit
Foods & medicines Calefacients harmful Infrigidants harmful Moist aliments harmful Dry regimen harmful
Infrigidants beneficial Calefacients beneficial Humectants beneficial
Relation to weather Worse in summer Worse in winter Bad in autumn
The Eight Varieties of Equipoise
Canon describes humans as having eight different "varieties of equipoise", or differing temperaments.[8]:59 The temperaments fall under two categories; In relation to beings other than men and in relation to the individual himself.
A. In relation to beings other than men
i. "the equability of the temperament seen in man as compared with other creatures"
ii. the temperament of other human beings
Avicenna describes a hot versus cold / moist versus dry equilibrium between the members of the human body. The heart, for example, is hot and must be in equilibrium of other cold parts of the body such as the brain. When this equilibrium between these members are achieved, the person is considered to be in "ideal equability." [8]:59–60
iii. external factors "such as race, climate, atmosphere"
This third gauge for temperament assumes that each race has their own equilibrium. As an example he says, "The Hindus, in health, have a different equability to the Slaves, and so on." Avicenna explains that the differing climates contribute to differing temperaments among the races.[8]:60
iv. in relation to extreme climates
B. In relation to the individual himself
v. "as compared to another person"
Although Avicenna had listed the fifth mode "as compared to another person", he seems to contradict that statement by explaining that every individual has a temperament that is unique to themselves and unlike anyone else.[8]:59–61
vi. comparison of the individual himself
vii. comparing one member of the body with another member of the body
The Canon here makes the distinction of the members into categories of their individual "moistness", "dryness", "hotness", and "coldness".
viii. comparison of a member to itself
The Canon continues to explain the sun's position in relation to ideal temperament and the role that climate and human skin play. Organs are nowhere near ideal in temperament, but skin comes the closest. Avicenna says that the hand, especially the palm and the tip of the index finger, is the most sensitive of all and attuned to tactile contact. Medicine is described as "hot" or "cold", not based upon its actual temperature but with regard to how it relates to the temperament of the human body.[8]:62–63
The Canon then describes when temperaments are unequal, in other words, illness. Avicenna separates these into two categories, which are fairly self explainable within the context of what he had already defined as the temperaments.
A. Simple "intemperaments"[8]:63
Hot temperament (hotter than normal)
Cold temperament (colder than normal)
Dry temperament (drier than usual)
Moist temperament (more moist than usual)
B. Compound "intemperaments"
The compound intemperaments are where two things are wrong with the temperament, i.e. hotter and moister; hotter and drier; colder and moister; colder and drier. There are only four because something cannot be simultaneously hotter and colder or drier and moister. The four simple temperaments and four compound intemperaments can each be divided into "Those apart from any material substance" and "Those in which some material substance is concerned", for a total of sixteen intemperaments. Examples of the sixteen intemperaments are provided in the "third and fourth volumes."[8]:64
II The Temperament of the Several Members[edit]
Each member of the body is described to be given each its individual temperament, each with its own degree of heat and moisture. Avicenna lists members of the body in "order of degree of Heat", from hottest to coldest.[8]:66
the breath and "the heart in which it arises"
the blood; which is said to be generated from the liver
the liver; "which may be looked upon as concentrated blood."
the flesh
the muscles
the spleen
the kidneys
the arteries
the veins
the skin of the palms and soles
Then a list is given of coldest members to hottest.[8]:66
serious humour
the hairs
the bones
the cartilage
the ligaments
the tendon
the membranes
the nerves
the spinal cord
the brain
the fat
the oil of the body
the skin
Then a list is given in order of moisture. Avicenna credits Galen with this particular list.[8]:67
serious humour
the serious humour
the blood
the oil
the fat
the brain
the spinal cord
the breasts and the testicles
the lung
the liver
the spleen
the kidneys
the muscles
the skin
Finally, a list is given in order of dryness<[8]:67–68
the hair
the bone
sereous membranes
motor nerves
sensory nerves
III The Temperaments Belonging to Age[edit]
The Canon divides life into four "periods" and then subdivides the first period into five separate categories.
The following table is provided for the four periods of life:[8]:68
Period Title Name Year of Age
I The Period of Growth Adolescence Up to 30
II The Prime of Life Period of beauty Up to 35 or 40
III Elderly life Period of decline. Senescence. Up to about 60
IV Decrepit Age Senility To the end of life
Avicenna says that the third period shows signs of decline in vigor and some decline in intellectual power. In the fourth period, both vigor and intelligence decline.
Avicenna divides the beginning stage of life in the following table, according to Oskar Cameron Gruner's edition of the Canon of Medicine:[8]:69
Sub-division Name Distinctive Characters
First Infancy The period before the limbs are fitted for walking
Second Babyhood The period of formation of the teeth. Walking has been learnt, but is not steady. The gums are not full of teeth.
Third Childhood The body shows strength of movement. The teeth are fully out. Pollutions have not yet appeared
Fourth Juvenility. "Puberty" The period up to the development of hair on the face and pubes. Pollutions begin.
Fifth Youth The period up to the limit of growth of the body (to the beginning of adult life). Period of athletic power.
Avicenna generalizes youth as having a "hot" temperament, but comments that there is controversy over which periods of youth are hotter. The general notion that youth are "hot" in temperament is due to youth's supposed relationship to members of the body that are hot. For example, blood was considered "hot" as was mentioned earlier, therefore youth is assumed to be hot partially due to blood being more "plentiful" and "thicker", according to Avicenna. Evidence for youth having an excess of blood is suggested by Avicenna's observation that nose bleeds are more frequent within youth. Other contributing factors are the youth's association with sperm and the consistency of their bile. Further description of youth in regards to heat and moisture is given with respect to sex, geographical location, and occupation. The Canon says, for example, that females are colder and more moist.[8]:69–74
The Humours[edit]
The Canon of Medicine is based upon the Four Humours of Hippocratic medicine, but refined in various ways. In disease pathogenesis, for example, Avicenna "added his own view of different types of spirits (or vital life essences) and souls, whose disturbances might lead to bodily diseases because of a close association between them and such master organs as the brain and heart".[11] An element of such belief is apparent in the chapter of al-Lawa", which relates "the manifestations to an interruption of vital life essence to the brain." He combined his own view with that of the Four Humours to establish a new doctrine to explain the mechanisms of various diseases in another work he wrote, Treatise on Pulse:[citation needed]
“From mixture of the four [humors] in different weights, [God the most high] created different organs; one with more blood like muscle, one with more black bile like bone, one with more phlegm like brain, and one with more yellow bile like lung.
[God the most high] created the souls from the softness of humors; each soul has its own weight and amalgamation. The generation and nourishment of proper soul takes place in the heart; it resides in the heart and arteries, and is transmitted from the heart to the organs through the arteries. At first, it [proper soul] enters the master organs such as the brain, liver or reproductive organs; from there it goes to other organs while the nature of the soul is being modified in each [of them]. As long as [the soul] is in the heart, it is quite warm, with the nature of fire, and the softness of bile is dominant. Then, that part which goes to the brain to keep it vital and functioning, becomes colder and wetter, and in its composition the serous softness and phlegm vapor dominate. That part, which enters the liver to keep its vitality and functions, becomes softer, warmer and sensibly wet, and in its composition the softness of air and vapor of blood dominate.
In general, there are four types of proper spirit: One is brutal spirit residing in the heart and it is the origin of all spirits. Another – as physicians refer to it – is sensual spirit residing in the brain. The third – as physicians refer to it – is natural spirit residing in the liver. The fourth is generative – i.e. procreative – spirits residing in the gonads. These four spirits go-between the soul of absolute purity and the body of absolute impurity.”


The Game of Life, also known simply as Life, is a cellular automaton devised by the British mathematician John Horton Conway in 1970.[1] It is a hugely important game in the study of biology. It is played in quadrants.

The "game" is a zero-player game, meaning that its evolution is determined by its initial state, requiring no further input. One interacts with the Game of Life by creating an initial configuration and observing how it evolves or, for advanced players, by creating patterns with particular properties.

The universe of the Game of Life is an infinite two-dimensional orthogonal grid of square cells, each of which is in one of two possible states, alive or dead. Every cell interacts with its eight neighbours, which are the cells that are horizontally, vertically, or diagonally adjacent. At each step in time, the following transitions occur:

Square 1: Any live cell with fewer than two live neighbours dies, as if caused by under-population.

Square 2: Any live cell with two or three live neighbours lives on to the next generation.

Square 3: Any live cell with more than three live neighbours dies, as if by over-population.

Square 4: Any dead cell with exactly three live neighbours becomes a live cell, as if by reproduction

Conway chose his rules carefully, after considerable experimentation, to meet these criteria:

Square 1: There should be no explosive growth.

Square 2: There should exist small initial patterns with chaotic, unpredictable outcomes.

Square 3: There should be potential for von Neumann universal constructors.

Square 4: The rules should be as simple as possible, whilst adhering to the above constraints.[9]

Patterns relating to fractals and fractal systems may also be observed in certain Life-like variations. For example, the automaton B1/S12 generates four very close approximations to the Sierpiński triangle when applied to a single live cell. The Sierpiński triangle can also be observed in Conway's Game of Life by examining the long-term growth of a long single-cell-thick line of live cells,[38] as well as in Highlife, Seeds (B2/S), and Wolfram's Rule 90.[39]

Immigration is a variation that is very similar to Conway's Game of Life, except that there are two ON states (often expressed as two different colours). Whenever a new cell is born, it takes on the ON state that is the majority in the three cells that gave it birth. This feature can be used to examine interactions between spaceships and other "objects" within the game.[40] Another similar variation, called QuadLife, involves four different ON states. When a new cell is born from three different ON neighbours, it takes on the fourth value, and otherwise, like Immigration, it takes the majority value.[41] Except for the variation among ON cells, both of these variations act identically to Life


I discussed how there are four "great apes". There are also four "big cats"

I put this in one of my books

The informal term "big cat" is typically used to refer to any of the four largest (living) members of the entire Panthera genus. Among the five total species within the Panthera genus, these four are the only animals that are able to roar.[1] In descending order of their maximum potential size, these four species are: tigers, lions, jaguars, and leopards.[1]


Quadrantanopia, quadrantanopsia, or quadrant anopia refers to an anopia affecting a quarter of the field of vision.

It can be associated with a lesion of an optic radiation.[1] While quadrantanopia can be caused by lesions in the temporal and parietal lobes, it is most commonly associated with lesions in the occipital lobe.[2] If Meyer's loop (temporal pathway) is lesioned, the vision loss is superior (colloquially referred to as "pie in the sky"); if Baum's loop (parietal pathway) is lesioned, the vision loss is inferior.[3]



In the absence of a large concentration of yolk, four major cleavage types can be observed in isolecithal cells (cells with a small even distribution of yolk) or in mesolecithal cells (moderate amount of yolk in a gradient) – bilateral holoblastic, radial holoblastic, rotational holoblastic, and spiral holoblastic, cleavage.[2] These holoblastic cleavage planes pass all the way through isolecithal zygotes during the process of cytokinesis. Coeloblastula is the next stage of development for eggs that undergo these radial cleavaging. In holoblastic eggs, the first cleavage always occurs along the vegetal-animal axis of the egg, the second cleavage is perpendicular to the first. From here, the spatial arrangement of blastomeres can follow various patterns, due to different planes of cleavage, in various organisms.



The first cleavage results in bisection of the zygote into left and right halves. The following cleavage planes are centered on this axis and result in the two halves being mirror images of one another. In bilateral holoblastic cleavage, the divisions of the blastomeres are complete and separate; compared with bilateral meroblastic cleavage, in which the blastomeres stay partially connected.


Radial cleavage is characteristic of the deuterostomes, which include some vertebrates and echinoderms, in which the spindle axes are parallel or at right angles to the polar axis of the oocyte.


Mammals display rotational cleavage, and an isolecithal distribution of yolk (sparsely and evenly distributed). Because the cells have only a small amount of yolk, they require immediate implantation onto the uterine wall in order to receive nutrients.

Rotational cleavage involves a normal first division along the meridional axis, giving rise to two daughter cells. The way in which this cleavage differs is that one of the daughter cells divides meridionally, whilst the other divides equatorially.


Spiral cleavage is conserved between many members of the lophotrochozoan taxa, referred to as Spiralia.[3] Most spiralians undergo equal spiral cleavage, although some undergo unequal cleavage (see below).[4] This group includes annelids, molluscs, and sipuncula. Spiral cleavage can vary between species, but generally the first two cell divisions result in four macromeres, also called blastomeres, (A, B, C, D) each representing one quadrant of the embryo. These first two cleavages are oriented in planes that occur at right angles parallel to the animal-vegetal axis of the zygote.[3] At the 4-cell stage, the A and C macromeres meet at the animal pole, creating the animal cross-furrow, while the B and D macromeres meet at the vegetal pole, creating the vegetal cross-furrow.[5] With each successive cleavage cycle, the macromeres give rise to quartets of smaller micromeres at the animal pole.[6][7] The divisions that produce these quartets occur at an oblique angle, an angle that is not a multiple of 90°, to the animal-vegetal axis.[7] Each quartet of micromeres is rotated relative to their parent macromere, and the chirality of this rotation differs between odd and even numbered quartets, meaning that there is alternating symmetry between the odd and even quartets.[3] In other words, the orientation of divisions that produces each quartet alternates between being clockwise and counterclockwise with respect to the animal pole.[7] The alternating cleavage pattern that occurs as the quartets are generated produces quartets of micromeres that reside in the cleavage furrows of the four macromeres.[5] When viewed from the animal pole, this arrangement of cells displays a spiral pattern.


D quadrant specification through equal and unequal cleavage mechanisms. At the 4-cell stage of equal cleavage, the D macromere has not been specified yet. It will be specified after the formation of the third quartet of micromeres. Unequal cleavage occurs in two ways: asymmetric positioning of the mitotic spindle, or through the formation of a polar lobe (PL).

Specification of the D macromere and is an important aspect of spiralian development. Although the primary axis, animal-vegetal, is determined during oogenesis, the secondary axis, dorsal-ventral, is determined by the specification of the D quadrant.[7] The D macromere facilitates cell divisions that differ from those produced by the other three macromeres. Cells of the D quadrant give rise to dorsal and posterior structures of the spiralian.[7] Two known mechanisms exist to specify the D quadrant. These mechanisms include equal cleavage and unequal cleavage.

In equal cleavage, the first two cell divisions produce four macromeres that are indistinguishable from one another. Each macromere has the potential of becoming the D macromere.[6] After the formation of the third quartet, one of the macromeres initiates maximum contact with the overlying micromeres in the animal pole of the embryo.[6][7] This contact is required to distinguish one macromere as the official D quadrant blastomere. In equally cleaving spiral embryos, the D quadrant is not specified until after the formation of the third quartet, when contact with the micromeres dictates one cell to become the future D blastomere. Once specified, the D blastomere signals to surrounding micromeres to lay out their cell fates.[7]

In unequal cleavage, the first two cell divisions are unequal producing four cells in which one cell is bigger than the other three. This larger cell is specified as the D macromere.[6][7] Unlike equally cleaving spiralians, the D macromere is specified at the four-cell stage during unequal cleavage. Unequal cleavage can occur in two ways. One method involves asymmetric positioning of the cleavage spindle.[7] This occurs when the aster at one pole attaches to the cell membrane, causing it to be much smaller than the aster at the other pole.[6] This results in an unequal cytokinesis, in which both macromeres inherit part of the animal region of the egg, but only the bigger macromere inherits the vegetal region.[6] The second mechanism of unequal cleavage involves the production of an enucleate, membrane bound, cytoplasmic protrusion, called a polar lobe.[6] This polar lobe forms at the vegetal pole during cleavage, and then gets shunted to the D blastomere.[5][6] The polar lobe contains vegetal cytoplasm, which becomes inherited by the future D macromere.[7]

D quadrant specification through equal and unequal cleavage mechanisms. At the 4-cell stage of equal cleavage, the D macromere has not been specified yet. It will be specified after the formation of the third quartet of micromeres. Unequal cleavage occurs in two ways: asymmetric positioning of the mitotic spindle, or through the formation of a polar lobe (PL).


The hormone T4 has four atoms of iodine, while T3 has three atoms of iodine. T4 and T3 regulate metabolism, growth, heart rate, body temperature, and affect protein synthesis. The hormone calcitonin is produced by thyroid parafollicular cells. Calcitonin helps to regulate calcium concentrations by lowering blood calcium levels when the levels are high.

Thyroid Hormone Regulation

Thyroid hormones T4 and T3 are regulated by the pituitary gland. This small endocrine gland is located in the middle of the base of the brain. It controls a multitude of important functions in the body. The pituitary gland is termed the "Master Gland" because it directs other organs and endocrine glands to suppress or induce hormone production. One of the many hormones produced by the pituitary gland is thyroid stimulating hormone (TSH). When levels of T4 and T3 are too low, TSH is secreted to stimulate the thyroid to produce more thyroid hormones. As levels of T4 and T3 rise and enter the blood stream, the pituitary senses the increase and reduces its production of TSH. This type of regulation is an example of a negative feedback mechanism. The pituitary gland is itself regulated by the hypothalamus. Blood vessel connections between the hypothalamus and pituitary gland allow hypothalamic hormones to control pituitary hormone secretion. The hypothalamus produces thyrotropin-releasing hormone (TRH). This hormone stimulates the pituitary to release TSH.

Thyroid Problems

When the thyroid gland is not functioning properly, several thyroid disorders may develop. These disorders can range from a slightly enlarged gland to thyroid cancer. An iodine deficiency may cause the thyroid to become enlarged. An enlarged thyroid gland is referred to as a goiter. When the thyroid produces hormones in excess of the normal amount, it causes a condition called hyperthyroidism. When the thyroid does not produce enough thyroid hormone, hypothyroidism occurs. Many instances of hyperthyroidism and hypothyroidism are caused by autoimmune thyroid diseases. In autoimmune disease, the immune system attacks the body's own normal tissues and cells. Autoimmune thyroid diseases can cause the thyroid to become overactive or to stop producing hormones entirely.

Parathyroid Glands

Parathyroid glands are four small tissue masses located on the posterior side of the thyroid. These glands vary in number, but typically two or more may be found in the thyroid. Parathyroid glands contain many cells that secrete hormones and have access to extensive blood capillary systems. Parathyroid glands produce and secrete parathyroid hormone. This hormone helps to regulate calcium concentrations by increasing blood calcium levels when these levels dip below normal. Parathyroid hormone counteracts calcitonin, which decreases blood calcium levels. Parathyroid hormone increases calcium levels by promoting the break down of bone to release calcium, by increasing calcium absorption in the digestive system, and by increasing calcium absorption by the kidneys. Calcium ion regulation is vital to the proper functioning of organ systems such as the nervous system and muscular system.

quadrant streak
a technique for microbial inoculation in which a single colony is isolated on a culture plate divided into four sections.
Robert Heinrich Herman Koch (/ˈkɔːx/;[3] German: [ˈkɔχ]; 11 December 1843 – 27 May 1910) was a celebrated German physician and pioneering microbiologist. As the founder of modern bacteriology, he is known for his role in identifying the specific causative agents of tuberculosis, cholera, and anthrax and for giving experimental support for the concept of infectious disease.[4] In addition to his trail-blazing studies on these diseases, Koch created and improved laboratory technologies and techniques in the field of microbiology, and made key discoveries in public health.[5] His research led to the creation of Koch’s postulates, a series of four generalized principles linking specific microorganisms to specific diseases that remain today the "gold standard" in medical microbiology.[5] As a result of his groundbreaking research on tuberculosis, Koch received the Nobel Prize in Physiology or Medicine in 1905.
Koch's postulates revolutionized science and biology.
Koch's four postulates are the following:
Square 1: The microorganism must be found in abundance in all organisms suffering from the disease, but should not be found in healthy organisms.
Square 2: The microorganism must be isolated from a diseased organism and grown in pure culture.
Square 3: The cultured microorganism should cause disease when introduced into a healthy organism.
Square 4: The microorganism must be reisolated from the inoculated, diseased experimental host and identified as being identical to the original specific causative agent.
During his time as the government advisor with the Imperial Department of Health in Berlin in the 1880s, Robert Koch became interested in tuberculosis research.[4] At the time, it was widely believed that tuberculosis was an inherited disease.[4] However, Koch was convinced that the disease was caused by a bacterium and was infectious, and tested his four postulates using guinea pigs.[4] Through these experiments, he found that his experiments with tuberculosis satisfied all four of his postulates.[4] In 1882, he published his findings on tuberculosis, in which he reported the causative agent of the disease to be the slow-growing Mycobacterium tuberculosis.[11] His work with this disease won Koch the Nobel Prize in Physiology and Medicine in 1905.[4] Additionally, Koch's research on tuberculosis, along with his studies on tropical diseases, won him the Prussian Order Pour le Merite in 1906 and the Robert Koch medal, established to honour the greatest living physicians, in 1908.[4]


Tics are classified as either motor or phonic, and simple or complex.

Simple motor tics are typically sudden, brief, meaningless movements that usually involve only one group of muscles, such as eye blinking, head jerking, or shoulder shrugging.[6] Motor tics can be of an endless variety and may include such movements as hand clapping, neck stretching, mouth movements, head, arm or leg jerks, and facial grimacing.

A simple phonic tic can be almost any sound or noise, with common vocal tics being throat clearing, sniffing, or grunting.[6]

Complex motor tics are typically more purposeful-appearing and of a longer nature. They may involve a cluster of movements and appear coordinated.[6] Examples of complex motor tics are pulling at clothes, touching people, touching objects, echopraxia (repeating or imitating another person's actions) and copropraxia (involuntarily performing obscene or forbidden gestures).

Complex phonic tics include echolalia (repeating words just spoken by someone else), palilalia (repeating one's own previously spoken words), lexilalia (repeating words after reading them), and coprolalia (the spontaneous utterance of socially objectionable or taboo words or phrases). Coprolalia is a highly publicized symptom of Tourette syndrome; however, only about 10% of TS patients exhibit coprolalia.[6]


Calculating the QRS Quadrant for the heart.

One method used to calculate QRS quadrant is to look at leads I and aVF. Remember from earlier, the electrical impulse originates in the SA node of the right atrium and travels through the AV node down through the ventricles. The impulse follows the pathway of Lead II, right arm to the left leg.

When the QRS in Lead I is positive, it means the electricity is moving through the persons heart from right to left (normal pathway).

If the QRS is negative in lead I, then the electricity is moving left to right (abnormal).

This means that if the electricity is traveling to the left, the QRS axis quadrant will either be NORMAL AXIS or LAD.

If the electricity is traveling to the right, the QRS axis quadrant will either be RAD or UNKNOWN.

Now we will look at aVF. If the QRS is positive, it means the electricity is moving through the heart from top to bottom (normal pathway).

If the QRS in aVF is negative, the electricity is moving from the bottom to the top (abnormal).

This means that if the electricity is moving from the top to the bottom, the QRS axis quadrant is NORMAL AXIS of RAD.

However, if the electricity is traveling upward, the QRS axis quadrant is Unknown or LAD.

The diagram below illustrates these rules in their corresponding quadrants. For instance, If the QRS in Lead I is (+) and aVF is (-), that places the axis in the LAD quadrant.

image from…/eldridge_j/KINE3351/quadrant_1.gif

Causes of QRS Deviation

Causes of Left Axis Deviation (LAD), where the QRS axis is in the LAD quadrant:

Left Ventricular Hypertrophy (LVH): requires more electricity due to the increase size of the ventricle causing the electricle path to swing further to the left.

Left Bundle Branch Block (LBBB): Since the left bundle is blocked, the electrical path travels down the right bundle, then the electrical stimulation has to travel from cell to cell to stimulate the left ventricle to depolarize causing the QRS axis to deviate to the left.

Inferior Wall MI: In an Inferior MI, the elctrical path has to deviate to the left to go up and around the infarcted tissue, swing the pathway to the left side.

Causes of Right Axis Deviation (RAD), where the QRS axis is in the RAD quadrant:

Dextrocardia: born with heart on the right side

Anterior MI

Right Ventricular Hypertrophy (RVH)

Right Bundle Branch Block (RBBB)

Ventricular Tachycardia

COPD/Pulmonary Hypertension


Since that first outbreak in 1976, four subtypes or versions of the Ebola virus have been identified so far. The first three, called Ebola-Zaire, Ebola-Sudan, and Ebola-Ivory Coast, are known to have caused disease in humans. The fourth, called Ebola-Reston after the Reston, Virginia, primate laboratory where it was first discovered, seems to only be transmitted by monkeys to monkeys, although it may be the only one of the four viruses that is airborne (meaning it can be spread through particles floating in the air).

Read more:

Ebola Virus - humans, body, oxygen, air, cells, parts, part

The Ebola (pronounced ee-BO-luh) virus is the common name for a severe, often-fatal bleeding or hemorrhagic (pronounced hem-or-RAD-jik) fever that…


nuclear receptors may be subdivided into the following four mechanistic classes:[4][5]
Type I[edit]
Ligand binding to type I nuclear receptors in the cytosol results in the dissociation of heat shock proteins, homo-dimerization, translocation (i.e., active transport) from the cytoplasm into the cell nucleus, and binding to specific sequences of DNA known as hormone response elements (HREs). Type I nuclear receptors bind to HREs consisting of two half-sites separated by a variable length of DNA, and the second half-site has a sequence inverted from the first (inverted repeat). Type I nuclear receptors include members of subfamily 3, such as the androgen receptor, estrogen receptors, glucocorticoid receptor, and progesterone receptor.[24]
It has been noted that some of the NR subfamily 2 nuclear receptors may bind to direct repeat instead of inverted repeat HREs. In addition, some nuclear receptors that bind either as monomers or dimers, with only a single DNA binding domain of the receptor attaching to a single half site HRE. These nuclear receptors are considered orphan receptors, as their endogenous ligands are still unknown.
The nuclear receptor/DNA complex then recruits other proteins that transcribe DNA downstream from the HRE into messenger RNA and eventually protein, which causes a change in cell function.
Type II[edit]
Type II receptors, in contrast to type I, are retained in the nucleus regardless of the ligand binding status and in addition bind as hetero-dimers (usually with RXR) to DNA. In the absence of ligand, type II nuclear receptors are often complexed with corepressor proteins. Ligand binding to the nuclear receptor causes dissociation of corepressor and recruitment of coactivator proteins. Additional proteins including RNA polymerase are then recruited to the NR/DNA complex that transcribe DNA into messenger RNA.
Type II nuclear receptors include principally subfamily 1, for example the retinoic acid receptor, retinoid X receptor and thyroid hormone receptor.[25]
Type III[edit]
Type III nuclear receptors (principally NR subfamily 2) are similar to type I receptors in that both classes bind to DNA as homodimers. However, type III nuclear receptors, in contrast to type I, bind to direct repeat instead of inverted repeat HREs.
Type IV[edit]
Type IV nuclear receptors bind either as monomers or dimers, but only a single DNA binding domain of the receptor binds to a single half site HRE. Examples of type IV receptors are found in most of the NR subfamilies.


Cnidarians were for a long time grouped with Ctenophores in the phylum Coelenterata, but increasing awareness of their differences caused them to be placed in separate phyla. Modern cnidarians are generally classified into four main classes:[9] sessile Anthozoa (sea anemones, corals, sea pens); swimming Scyphozoa (jellyfish) and Cubozoa (box jellies); and Hydrozoa, a diverse group that includes all the freshwater cnidarians as well as many marine forms, and has both sessile members such as Hydra and colonial swimmers such as the Portuguese Man o' War. Staurozoa have recently been recognised as a class in their own right rather than a sub-group of Scyphozoa, and the parasitic Myxozoa and Polypodiozoa are now recognized as highly derived cnidarians rather than more closely related to the bilaterians.[28]


Medusae and complex swimming colonies such as siphonophores and chondrophores sense tilt and acceleration by means of statocysts, chambers lined with hairs which detect the movements of internal mineral grains called statoliths. If the body tilts in the wrong direction, the animal rights itself by increasing the strength of the swimming movements on the side that is too low. Most species have ocelli ("simple eyes"), which can detect sources of light. However the agile Box Jellyfish are unique among Medusae because they possess four kinds of true eyes that have retinas, corneas and lenses.[23] Although the eyes probably do not form images, Cubozoa can clearly distinguish the direction from which light is coming as well as negotiate around solid-colored objects.[9][23]…/A/Cell_receptor.html

Type 1: L (ionotropic receptors)– These receptors are typically the targets of fast neurotransmitters such as acetylcholine (nicotinic) and GABA and activation of these receptor results in changes in ion movement across the membrane. They have a hetero structure. Each subunit consists of the extracellular ligand-binding domain and a transmembrane domain where the transmembrane domain in turn includes four transmembrane alpha helixes. The ligand binding cavities are located at the interface between the subunits.…/A/Cell_receptor.html

Type 1: L (ionotropic receptors)– These receptors are typically the targets of fast neurotransmitters such as acetylcholine (nicotinic) and GABA and activation of these receptor results in changes in ion movement across the membrane. They have a hetero structure. Each subunit consists of the extracellular ligand-binding domain and a transmembrane domain where the transmembrane domain in turn includes four transmembrane alpha helixes. The ligand binding cavities are located at the interface between the subunits.…/A/Cell_receptor.html


Transmembrane receptor:E=extracellular space; I=intracellular space; P=plasma membrane
The structures of receptors are very diverse and can broadly be classified into the following four categories:

Type 1: L (ionotropic-receptors)– These receptors are typically the targets of fast-neurotransmitters such as acetylcholine (nicotinic) and GABA; and, activation of these receptors results in changes in ion-movement across a membrane. They have a hetero-structure. Each subunit consists of the extracellular-ligand-binding domain and a transmembrane-domain where the transmembrane-domain in turn includes four transmembrane-alpha helixes. The ligand-binding cavities are located at the interface between the subunits.
Type 2: G protein-coupled receptors (metabotropic) – This is the largest family of receptors and includes the receptors for several hormones and slow transmitters e.g. dopamine, metabotropic-glutamate. They are composed of seven transmembrane-[alpha helix|alpha helices]]. The loops connecting the alpha-helices form extracellular and intracellular-domains. The binding-site for larger peptidic-ligands is usually located in the extracellular-domain whereas the binding-site for smaller non-peptidic ligands is often located between the seven alpha-helices and one extracellular-loop.[1] The aforementioned receptors are coupled to different intracellular-effector systems via G-proteins.[2]
Type 3: kinase linked and related receptors (see "Receptor tyrosine kinase", and "Enzyme-linked receptor") - They are composed of an extracellular-domain containing the ligand-binding site and an intracellular-domain, often with enzymatic-function, linked by a single transmembrane-alpha helix. e.g. the insulin-receptor.
Type 4: nuclear receptors – While they are called nuclear-receptors, they are actually located in the cytosol and migrate to the nucleus after binding with their ligands. They are composed of a C-terminal-ligand-binding region, a core-DNA-binding domain (DBD) and an N-terminal-domain that contains the AF1(activation function 1) region. The core-region has two zinc-fingers that are responsible for recognising the DNA-sequences specific to this receptor. The N-terminal interacts with other cellular-transcription factors in a ligand-independent manner; and, depending on these interactions it can modify the binding/activity of the receptor. Steroid and thyroid-hormone receptors are examples of such receptors.[3]


Scientists have analysed the largest collection of human fossils on the planet, dating back 430,000 years, and have found that the human body went through four main stages of evolution before settling on the shape and size we see around us today.

The fossils were from the Sima de los Huesos site in northern Spain, and the humans located there are often referred to as Atapuerca humans. The researchers found that these ancient humans shared many anatomical features with the late Neanderthals, but not modern humans, and therefore represent the third stage of human body evolution.

"This is really interesting since it suggests that the evolutionary process in our genus is largely characterised by stasis (i.e. little to no evolutionary change) in body form for most of our evolutionary history," lead author Rolf Quam, an anthropologist from Binghamton University in the US, said in a press release.

The team's analysis of these fossils revealed that the Atapuerca individuals, who lived around 430,000 years ago, were relatively tall, with wide, muscular bodies and less brain mass relative to body mass than the Neanderthals.

Using this information, the researchers were able to hypothesise that there were four main stages that got the Homo genus to where it is today. The first stage occurred hundreds of thousands of years ago, when our hominid ancestors began to migrate out of Africa. The second stage was the evolution of Neanderthals, while the third stage brought about the Atapuerca humans, who finally evolved into our modern body shape.

Each of these stages can be characterised by the amount of walking on two legs versus living in trees the hominids participated in. By the third stage, there was no evidence of tree-dwelling in the human skeleton.

But despite the differences, the researchers explain that the Atapuerca humans likely shared the same wide and robust body forms as our ancestors Homo erectus and the Neanderthals, and that the body form was probably around in the Homo genus for more than a million years.

"It was not until the appearance of our own species, Homo sapiens, when a new taller, lighter and narrower body form emerged," the press release explains. "Thus, the authors suggest that the Atapuerca humans offer the best look at the general human body shape and size during the last million years before the advent of modern humans."


In anatomy, a nasal concha (/ˈkɒnkə/), plural conchae (/ˈkɒnki/), also called a turbinate or turbinal, is a long, narrow, curled shelf of bone that protrudes into the breathing passage of the nose in humans and various animals. The conchae are shaped like an elongated seashell, which gave them their name (Latin concha from Greek κόγχη). A turbinate bone is any of the scrolled spongy bones of the nasal passages in vertebrates.[1]


In humans, the turbinates divide the nasal airway into 4 groove-like air passages, and are responsible for forcing inhaled air to flow in a steady, regular pattern around the largest possible surface area of nasal mucosa, which, as a ciliated mucous membrane with shallow blood supply, cleans and warms the inhaled air in preparation for the lungs.


The Quadrant Shopping Centre is the principal under-cover shopping centre in Swansea, Wales. The centre opened in 1979.[1] Since the 1980s it has been home to the Swansea Devil, a controversial carved wooden statue of the Devil.


The centre and surrounding areas are owned by the City and County of Swansea council.[2]


The movements of the nose are affected by

the elevator muscle group — which includes the procerus muscle and the levator labii superioris alaeque nasi muscle.

the depressor muscle group — which includes the alar nasalis muscle and the depressor septi nasi muscle.

the compressor muscle group — which includes the transverse nasalis muscle.

the dilator muscle group — which includes the dilator naris muscle that expands the nostrils; it is in two parts: (i) the dilator nasi anterior muscle, and (ii) the dilator nasi posterior muscle.
The dentition is divided into four quarters. The two dental arches form an oval, which is divided into quadrants:
Upper right quadrant: upper right first incisor to upper right wisdom tooth
Upper left quadrant: upper left first incisor to upper left wisdom tooth
Lower right quadrant: lower right first incisor to lower right wisdom tooth
Lower left quadrant: lower left first incisor to lower left wisdom tooth


The human abdomen is divided into regions by anatomists and physicians for purposes of study, diagnosis, and therapy.[1] [2] In the four-region scheme, four quadrants allow localisation of pain and tenderness, scars, lumps, and other items of interest, narrowing in on which organs and tissues may be involved. The quadrants are referred to as the left lower quadrant, left upper quadrant, right upper quadrant and right lower quadrant, as follows.

The left lower quadrant (LLQ) of the human abdomen is the area left of the midline and below the umbilicus. The LLQ includes the left iliac fossa and half of the left flank region.

The term is not used in comparative anatomy, since most other animals do not stand erect. The equivalent term for animals is left posterior quadrant.

The left upper quadrant (LUQ) extends from the median plane to the left of the patient, and from the umbilical plane to the left ribcage.

The equivalent term for animals is 'left anterior quadrant'.

The right upper quadrant (RUQ) extends from the median plane to the right of the patient, and from the umbilical plane to the right ribcage.

The equivalent term for animals is 'right anterior quadrant'.

The right lower quadrant (RLQ) extends from the median plane to the right of the patient, and from the umbilical plane to the right inguinal ligament.

The equivalent term for animals is 'right posterior quadrant'.

In the LLQ if abdominal pain or signs of peritonitis are localised, colitis, diverticulitis, ureteral colic or pain due to ovarian cysts or pelvic inflammatory disease, may be suspected. Examples of tumours in the left lower quadrant include colon cancer or ovarian tumour.

The LUQ may be painful or tender in appendicitis, and in the case of intestinal malrotation.

The RUQ may be painful or tender in hepatitis, cholecystitis, and peptic ulcer.

The RLQ may be painful and/or tender in such conditions as appendicitis.

Four Fish: The Future of the Last Wild Food is a 2010 nonfiction book by author Paul Greenberg. This work explores the state of commercial fishing and aquaculture. Greenberg frames his observations by commenting on the status of four specific fish: cod, salmon, bass, and tuna. Choosing four fish was a decision influenced by author Michael Pollan's selection of four plants in his book, The Botany of Desire. [1]
The New York Times gave the book a positive review.[2] David Helvarg gave the book a positive review on[3] The book was reviewed by The Los Angeles Times.



The four types of arrangement for flagellum are

square 1: peritrichous

square 2: lophotrichous

sqaure 3: Amphitrichous

square 4: monotrichous

Flowers have four basic parts.the floral organs of eudicotyledonous angiosperms (flowers) are arranged in 4 different verticils, containing the Square 1: sepals,
Square 2: petals, 
Square 3: stamen 
Square 4: carpels. The ABC model states that the identity of these organs is determined by the homeotic genes 
Square 1: A, 
Square 2: A+B, 
Square 3B+C 
Square 4: C
Flowers should fit the quadrant model pattern because in the plant world they are the paragon. Like humans who are the paragon of animals, flowers project the quadrant model image


The (VRG) is a column of neurons located in the ventrolateral region of the medulla, extending from the caudal facial nucleus to -400μm obex. The four cell groups of the VRG are the rostral nucleus retrofacialis, caudal nucleus retroambiguus, nucleus para-ambiguus, and the pre-Bötzinger complex.


there are four minor ones

Pathways [edit]

There are eight dopaminergic pathways. The four major ones are listed in the table below.


Pathway name Description Associated processes Associated disorders





The mesolimbic pathway transmits dopamine from the ventral tegmental area (VTA) to the nucleus accumbens. The VTA is located in the midbrain, and the nucleus accumbens is in the ventral striatum. The "meso" prefix in the word "mesolimbic" refers to the midbrain, or "middle brain", since "meso" means "middle" in Greek.

reward-related cognition

incentive salience ("wanting")

pleasure ("liking") response from certain stimuli

positive reinforcement

aversion-related cognition






The mesocortical pathway transmits dopamine from the VTA to the prefrontal cortex. The "meso" prefix in "mesocortical" refers to the VTA, which is located in the midbrain, and "cortical" refers to the cortex.

executive functions




Nigrostriatal pathway

The nigrostriatal pathway transmits dopamine from the substantia nigra pars compacta (SNc) to the caudate nucleus and putamen. The substantia nigra is located in the midbrain, while both the caudate nucleus and putamen is located in the dorsal striatum.

motor function

reward-related cognition

associative learning



Parkinson's disease

Tuberoinfundibular pathway

The tuberoinfundibular pathway transmits dopamine from the hypothalamus (arcuate nucleus aka "infundibular nucleus") to the pituitary gland. This pathway influences the secretion of certain hormones, including prolactin. "Infundibular" in the word "tuberoinfundibular" refers to the cup or infundibulum, out of which the pituitary gland develops.

activity of this pathway inhibits the release of prolactin.




The Four Dopamine Pathways Relevant to Antipsychotics Pharmacology

By Flavio Guzmán, MD

This video describes the 4 dopamine pathways relevant to the mechanism of action and adverse effects of antipsychotic drugs.


Presentation outline:

There are 4 main dopamine pathways in the brain:

Nigro-Striatal: substantial nigra to basal ganglia, involved in movement (what gets affected to cause EPS: tardive dyskinesia, akatisia)

Meso-Limbic: VTA to nucleus accumbens, “reward” pathway (causes the positive symptoms of schizophrenia)

Meso-Cortical: VTA to cortex, motivation and emotional response (thought to cause the negative symptoms of schizophrenia)

Tubulo-Infundibular: hypothalamus to posterior pituitary (hypoprolactinemia in untreated individuals, but D2 blockade with antipsychotics can cause a hyperprolactenemia)


The molecules responsible for creating cell junctions include various cell adhesion molecules. There are four main types: selectins, cadherins, integrins, and the immunoglobulin superfamily.[12]


Selectins are cell adhesion molecules that play an important role in the initiation of inflammatory processes.[13] The functional capacity of selectin is limited to leukocyte collaborations with vascular endothelium. There are three types of selectins found in humans; L-selectin, P-selectin and E-selectin. L-selectin deals with lymphocytes, monocytes and neutrophils, P-selectin deals with platelets and endothelium and E-selectin deals only with endothelium. They have extracellular regions made up of an amino-terminal lectin domain, attached to a carbohydrate ligand, growth factor-like domain (EGF) and short repeat units (numbered circles) that match the complimentary binding protein domains.[14]


Cadherins are calcium-dependent adhesion molecules. Cadherins are extremely important in the process of morphogenesis – fetal development. Together with an alpha-beta catenin complex, the cadherin can bind to the microfilaments of the cytoskeleton of the cell. This allows for homophilic cell–cell adhesion.[15] The β-catenin–α-catenin linked complex at the adherens junctions allows for the formation of a dynamic link to the actin cytoskeleton.[16]


Integrins act as adhesion receptors, transporting signals across the plasma membrane in multiple directions. These molecules are an invaluable part of cellular communication, as a single ligand can be used for many integrins. Unfortunately these molecules still have a long way to go in the ways of research.[17]


Immunoglobulin superfamily are a group of calcium independent proteins capable of homophilic and heterophilic adhesion. Homophilic adhesion involves the immunoglobulin-like domains on the cell surface binding to the immunoglobulin-like domains on an opposing cell’s surface while heterophilic adhesion refers to the binding of the immunoglobulin-like domains to integrins and carbohydrates instead.[18]


There have been approximately 40 proteins identified to be involved in tight junctions. These proteins can be classified into four major categories; scaffolding proteins, signalling proteins, regulation proteins, and transmembrane proteins.


Roles of Tight Junction Proteins[edit]

Scaffolding Proteins — organise the transmembrane proteins, couple transmembrane proteins to other cytoplasmic proteins as well as to actin filaments.


Signaling Proteins — involved in junctions assembly, barrier regulation, and gene transcription.


Regulation Proteins — regulate membrane vesicle targeting.


Transmembrane Proteins — including junctional adhesion molecule (JAM), occludin, and claudin. It is believed that claudin is the protein molecule responsible for the selective permeability between epithelial layers.

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The colon consists of four parts: descending colon, ascending colon, transverse colon, and sigmoid colon.

Upon dissection, the duodenum may appear to be a unified organ, but it is divided into four segments based upon function, location, and internal anatomy. The four segments of the duodenum are as follows (starting at the stomach, and moving toward the jejunum): bulb, descending, horizontal, and ascending.



The gastrointestinal tract has a form of general histology with some differences that reflect the specialization in functional anatomy.[18] The GI tract can be divided into four concentric layers in the following order:




Muscular layer

Ascending colon[edit]
The ascending colon is the first of FOUR sections of the large intestine. It is connected to the small intestine by a section of bowel called the cecum. The ascending colon runs upwards through the abdominal cavity toward the transverse colon for approximately eight inches (20 cm).

One of the main functions of the colon is to remove the water and other key nutrients from waste material and recycle it. As the waste material exits the small intestine through the ileocecal valve, it will move into the cecum and then to the ascending colon where this process of extraction starts. The unwanted waste material is moved upwards toward the transverse colon by the action of peristalsis. The ascending colon is sometimes attached to the appendix via Gerlach's valve. The appendix, traditionally seen as a vestigial organ, has been shown to have a high concentration of lymphatic cells. In ruminants, the ascending colon is known as the spiral colon.[14][15][16]

Transverse colon[edit]
The transverse colon is the part of the colon from the hepatic flexure to the splenic flexure (the turn of the colon by the spleen). The transverse colon hangs off the stomach, attached to it by a large fold of peritoneum called the greater omentum. On the posterior side, the transverse colon is connected to the posterior abdominal wall by a mesentery known as the transverse mesocolon.

The transverse colon is encased in peritoneum, and is therefore mobile (unlike the parts of the colon immediately before and after it). Cancers form more frequently further along the large intestine as the contents become more solid (water is removed) in order to form feces.[citation needed]

The proximal two-thirds of the transverse colon is perfused by the middle colic artery, a branch of the superior mesenteric artery (SMA), while the latter third is supplied by branches of the inferior mesenteric artery (IMA). The "watershed" area between these two blood supplies, which represents the embryologic division between the midgut and hindgut, is an area sensitive to ischemia.

Descending colon[edit]
The descending colon is the part of the colon from the splenic flexure to the beginning of the sigmoid colon. One function of the descending colon in the digestive system is to store feces that will be emptied into the rectum. It is retroperitoneal in two-thirds of humans. In the other third, it has a (usually short) mesentery.[17] The arterial supply comes via the left colic artery. The descending colon is also called the distal gut, as it is further along the gastrointestinal tract than the proximal gut. Gut flora are very dense in this region.

Sigmoid colon[edit]
The sigmoid colon is the part of the large intestine after the descending colon and before the rectum. The name sigmoid means S-shaped (see sigmoid; cf. sigmoid sinus). The walls of the sigmoid colon are muscular, and contract to increase the pressure inside the colon, causing the stool to move into the rectum.

The sigmoid colon is supplied with blood from several branches (usually between 2 and 6) of the sigmoid arteries, a branch of the IMA. The IMA terminates as the superior rectal artery.

Sigmoidoscopy is a common diagnostic technique used to examine the sigmoid colon.

The rectum is the last section of the large intestine. It holds the formed feces awaiting elimination via defecation.


Ye Tianshi

From Wikipedia, the free encyclopedia

(Redirected from Four stages)

Ye Tianshi

Native name 葉天士

Born 1667

Died 1747

Occupation Physician

Era Qing dynasty

Ye Tianshi (1667-1747) was a Chinese medical scholar who was the major proponent of the "school of warm diseases".[1] His major work, Wen-re Lun (Discussion of Warm Diseases) published in 1746,[2] divided the manifestations of diseases into four stages: wei (defensive phase), qi (qi-phase), ying (nutrient-phase), and xue (blood-phase).[1]



Ye Tianqi was born in 1666. His father as well as his grandfather, Ye Shi, were also physicians.[3] He learned medicine from his father and, following his father's death, from his father's pupil of the surname Zhu.[3]



Ye Tianshi wrote little and most works attributed to him were compiled by his followers after his death.[3] He is best known for proposing that feverish diseases progressed along four stages, a theory he laid out in his book Discussion of Warm Diseases.[1] Those stages are wei (defensive phase), qi (qi-phase or active qian phase), ying (nutrient-phase), and xue (blood-phase).[1] The characteristics of wei are fever, sensitivity to cold, headache, and rapid pulse. Next qi is the phase of most active disease, characterized by high fever, sweating, dry mouth, and rapid pulse. Ying is characterized by rising fever at night, agitation, confusion, and weak pulse. Finally, xue consists of agitation, rash, and in some cases vomiting of blood or blood in the stool or urine.[3] In his treatments for feverish diseases, Ye recommended cooling substances.[1]

In classical anatomy, the stomach is divided into four sections, beginning at the Gastric cardia,[6] each of which has different cells and functions.


The cardia is where the contents of the oesophagus empty into the stomach. The cardia is defined as the region following the "z-line" of the gastroesophageal junction, the point at which the epithelium changes from stratified squamous to columnar. Near the cardia is the lower esophageal sphincter.[7]

The fundus (from Latin, "bottom") is formed by the upper curvature of the organ.

The body is the main, central region.

The pylorus (from Greek, "gatekeeper") is the lower section of the organ that facilitates emptying the contents into the small intestine.


The vestibular nuclei are the cranial nuclei for the vestibular nerve.


In Terminologia Anatomica they are grouped in both the pons and the medulla in the brainstem.


There are 4 subnuclei; they are situated at the floor of the fourth ventricle.


Name Location Notes

medial vestibular nucleus (dorsal or chief vestibular nucleus) medulla (floor of fourth ventricle) corresponding to the lower part of the area acustica in the rhomboid fossa;[citation needed] the caudal end of this nucleus is sometimes termed the descending or spinal vestibular nucleus.

lateral vestibular nucleus or nucleus of Deiters medulla (upper) consisting of large cells and situated in the lateral angle of the rhomboid fossa; the dorso-lateral part of this nucleus is sometimes termed the nucleus of Bechterew.

inferior vestibular nucleus medulla (lower)

superior vestibular nucleus pons

The fourth ventricle is one of the four connected fluid-filled cavities within the human brain. These cavities, known collectively as the ventricular system, consist of the left and right lateral ventricles, the third ventricle, and the fourth ventricle. The fourth ventricle extends from the cerebral aqueduct (aqueduct of Sylvius) to the obex, and is filled with cerebrospinal fluid (CSF).

The ventricular system is a set of four interconnected cavities (ventricles) in the brain, where the cerebrospinal fluid (CSF) is produced. Within each ventricle is a region of choroid plexus, a network of ependymal cells involved in the production of CSF. The ventricular system is continuous with the central canal of the spinal cord (from the fourth ventricle) allowing for the flow of CSF to circulate. All of the ventricular system and the central canal of the spinal cord is lined with ependyma, a specialised form of epithelium.

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This layer of protective tissues is collectively named the “meninges” but is actually composed of 3 main layers: The Dura mater, the Arachnoid layer, and the Pia mater.

The CSF, pia mater, and other layers of the meninges work together as a protection device for the brain, with the CSF often referred to as the FOURTH layer of the meninges.

The dura mater (Latin: tough mother) (also rarely called meninx fibrosa or pachymeninx) is a thick, durable membrane, closest to the skull and vertebrae. The dura mater, the outermost part, is a loosely arranged, fibroelastic layer of cells, characterized by multiple interdigitating cell processes, no extracellular collagen, and significant extracellular spaces. The middle region is a mostly fibrous portion. It consists of two layers: the endosteal layer, which lies closest to the calvaria (skullcap), and the inner meningeal layer, which lies closer to the brain. It contains larger blood vessels that split into the capillaries in the pia mater. It is composed of dense fibrous tissue, and its inner surface is covered by flattened cells like those present on the surfaces of the pia mater and arachnoid mater. The dura mater is a sac that envelops the arachnoid mater and surrounds and supports the large dural sinuses carrying blood from the brain toward the heart.

The dura has four areas of infolding:

Falx cerebri, the largest, sickle-shaped; separates the cerebral hemispheres. Starts from the frontal crest of frontal bone and the crista galli running to the internal occipital protuberance.
Tentorium cerebelli, the second largest, crescent-shaped; separates the occipital lobes from cerebellum. The falx cerebri attaches to it giving a tentlike appearance.
Falx cerebelli, vertical infolding; lies inferior to the tentorium cerebelli, separating the cerebellar hemispheres.
Diaphragma sellae, smallest infolding; covers the pituitary gland and sella turcica.



Four subspecies of the common chimpanzee have been recognised,[11][12] with the possibility of a fifth:[13]


Central chimpanzee or tschego, P. t. troglodytes, in Cameroon, the Central African Republic, Equatorial Guinea, Gabon, the Republic of the Congo, and the Democratic Republic of the Congo

Western chimpanzee, P. t. verus, in Guinea, Guinea Bissau, Mali, Senegal, Sierra Leone, Liberia, Ivory Coast, and Ghana

Nigeria-Cameroon chimpanzee, P. t. ellioti (also known as P. t. vellerosus),[11] in Nigeria and Cameroon

Eastern chimpanzee, P. t. schweinfurthii, in the Central African Republic, South Sudan, the Democratic Republic of the Congo, Uganda, Rwanda, Burundi, Tanzania, and Zambia


Vocalizations are also important in chimp communication. The most common and important call in adults is the "pant-hoot". These calls are made when individuals are excited.[21] Pant-hoots are made of four parts, starting with soft "hoos" that get louder and louder and climax into screams and sometimes barks; the former die down to soft "hoos" again as the call ends.[53] Submissive individuals will make "pant-grunts" towards their superiors.[21][44] Chimps use distance calls to draw attention to danger, food sources, or other community members.[21] "Barks" may be made as "short barks" when hunting and "tonal barks" when sighting large snakes.[53]


P. troglodytes is divided into four subspecies


The Hominidae (/hɒˈmɪnᵻdiː/), whose members are known as great apes[note 1] or hominids, are a taxonomic family of primates that includes seven extant species in four genera: Pongo, the Bornean and Sumatran orangutan; Gorilla, the eastern and western gorilla; Pan, the common chimpanzee and the bonobo; and Homo, the human (and though not extant, the near-human ancestors and relatives (e.g., the Neanderthal)).[1]


Gibbons are apes in the family Hylobatidae. The family historically contained one genus, but now is split into four genera.ón_hylobatidae.png


The family is divided into four genera based on their diploid chromosome number: Hylobates (44), Hoolock (38), Nomascus (52), and Symphalangus (50).[2][9]


Family Hylobatidae: gibbons[1][9][10]

Genus Hoolock

Western hoolock gibbon, H. hoolock

Eastern hoolock gibbon, H. leuconedys

Skywalker hoolock gibbon, H. tianxing[11]

Genus Hylobates: dwarf gibbons

Lar gibbon or white-handed gibbon, H. lar

Malaysian lar gibbon, H. l. lar

Carpenter's lar gibbon, H. l. carpenteri

Central lar gibbon, H. l. entelloides

Sumatran lar gibbon, H. l. vestitus

Yunnan lar gibbon, H. l. yunnanensis

Bornean white-bearded gibbon, H. albibarbis

Agile gibbon or black-handed gibbon, H. agilis

Müller's Bornean gibbon, H. muelleri

Müller's grey gibbon, H. m. muelleri

Abbott's grey gibbon, H. m. abbotti

Northern grey gibbon, H. m. funereus

Silvery gibbon, H. moloch

Western silvery gibbon or western Javan gibbon, H. m. moloch

Eastern silvery gibbon or central Javan gibbon, H. m. pongoalsoni

Pileated gibbon or capped gibbon, H. pileatus

Kloss's gibbon, Mentawai gibbon or bilou, H. klossii

Genus Symphalangus

Siamang, S. syndactylus

Genus Nomascus: crested gibbons

Northern buffed-cheeked gibbon, N. annamensis

Concolor or black crested gibbon, N. concolor

N. c. concolor

N. c. lu

N. c. jingdongensis

N. c. furvogaster

Eastern black crested gibbon or Cao Vit black crested gibbon, N. nasutus

Hainan black crested gibbon, N. hainanus

Northern white-cheeked gibbon, N. leucogenys

Southern white-cheeked gibbon, N. siki

Yellow-cheeked gibbon, N. gabriellae



The classification of this gibbon has changed several times in the past few years. Classically, all gibbons were classified in the genus Hylobates, with the exception of the siamang. After some studies, the genus was divided into three subgenera (including the siamang's Symphalangus), and then into four (recognizing Bunopithecus as the hoolock subgenus distinct from other gibbon subgenera). These four subgenera were elevated to full genus status

The genus Hylobates /ˌhaɪloʊˈbeɪtiːz/ is one of the four genera of gibbons. Its name means ‘forest walker’, from the Greek hūlē (ὕλη, ‘forest’) and bates (βάτης, ‘one who treads’).[3][4]


It was once considered the only genus, but recently its subgenera (Hoolock [formerly Bunopithecus], Nomascus, and Symphalangus) have been elevated to the genus level.[1][5] Hylobates remains the most speciose and widespread of gibbon genera, ranging from southern China (Yunnan) to western and central Java.



Siamang duetting differs from other species because it has a particularly complex vocal structure. Four distinct classes of vocalizations have been documented: booms, barks, ululating screams, and bitonal screams. Females typically produce long barks and males generally produce bitonal screams, but both sexes have been known to produce all four classes of vocalizations.[17]

New Research Says There Are Only Four Emotions

The thing was, as time went on, the face showed the distinction between the two, but when the emotion first hit, the face signals are very similar, suggesting, the researchers say, that the distinction between anger and disgust and between surprise and fear, is socially, not biologically based.


This leaves us with four "basic" emotions, according to this study: happy, sad, afraid/surprised, and angry/disgusted. These, the researchers say, are our biologically based facial signals—though distinctions exist between surprise and fear and between anger and disgust, the experiment suggests that these differences developed later, more for social reasons than survival ones.


"Our data reflect that the six basic facial expressions of emotion, like languages, are likely to represent a more complex set of modern signals and categories evolved from a simpler system of communication in early man developed to subserve developing social interaction needs," the authors wrote. By that they mean these four emotions are the basic building blocks from which we develop our modern, complex, emotional stews.

Four Stages of Sleep – How They Impact You as an Athlete

Sleep occurs in cycles throughout the night, with each sleep cycle taking approximately 90 minutes. Our body’s biological clock controls all of this, and technically the sleep cycle is one of our many “circadian rhythms”. There are 4 identifiable stages in each sleep cycle, and each of them has a significant impact on athletic performance and improvement.

Stage 1 – Lasts for approximately 20 minutes and is the stage where the heart rate slows and the body temperature begins to cool down. The brain activity during this time shows up in “spindles”, which are essentially tightly packed brain wave patterns. These spindles have been linked to muscle memory and internalizing movements learned during the day.

Stages 2 and 3 – Stage 2 is the transition from light to deep sleep, and Stage 3 is complete deep sleep where the body produces very slow waves called Delta Waves. This stage of sleep is often called Slow Wave Sleep (SWS). During this stage HGH is released, blood rushes from the brain to the muscles to initiate recovery and re-energize your body. Additionally, elements of the parasympathetic nervous system are triggered while the sympathetic nervous system is suppressed. All of this supports immune function and normal glucose metabolism during the day.

Stage 4 – Otherwise known as REM sleep, this is the stage where we dream. Our arms and legs are paralyzed, and this is the only stage of sleep where the body doesn’t actually move. This stage of sleep is associated with learning and memory retention, where the hippocampus transfers and filters the day’s information to the neo-cortex, kind of like a computer uploading information and clearing it’s RAM onto a hard drive. During the first few cycles deep sleep periods are longer and REM periods are shorter, but after the 4th cycle the REM periods become much longer and the deep sleep phases much shorter.


Crop Rotation – the Key to Organic Gardening?

Written by patrickw on January 25, 2014. Posted in Uncategorized

Crop rotation is generally held to be the absolute keystone of organic growing. But in one of my recent videos I said that I don’t really follow a strict rotation in my home garden. The truth is that I do in theory but the practice is never quite the same thing.

Rotation of crops simply means that you don’t grow the same thing in the same bed one year after another. You grow it in another bed and put another crop in that one. Gardening books show neat diagrams of how you divide your plot into four and rotate the crops around over four years, like this.

It also begs the question as to why, if the Qur'an really is giving us a highly precise scientific account of human development, it only mentions four stages, nutfah, alaqa, mudghah, plus the clothing of bones with flesh.



The account of the different stages in embryology as described by the Qur'an, ar-Razi and al-Quff is identical to that taught by Galen, writing in around AD 150 in Pergamum (Bergama in modern Turkey). Galen taught that the embryo developed in four stages as detailed below.


Galen: De Semine in Greek




English translation:


But let us take the account back again to the first conformation of the animal, and in order to make our account orderly and clear, let us divide the creation of the foetus overall into four periods of time. The first is that in which. as is seen both in abortions and in dissection, the form of the semen prevails (Arabic nutfah). At this time, Hippocrates too, the all-marvelous, does not yet call the conformation of the animal a foetus; as we heard just now in the case of semen voided in the sixth day, he still calls it semen. But when it has been filled with blood (Arabic alaqa), and heart, brain and liver are still unarticulated and unshaped yet have by now a certain solidarity and considerable size, this is the second period; the substance of the foetus has the form of flesh and no longer the form of semen. Accordingly you would find that Hippocrates too no longer calls such a form semen but, as was said, foetus. The third period follows on this, when, as was said, it is possible to see the three ruling parts clearly and a kind of outline, a silhouette, as it were, of all the other parts (Arabic mudghah). You will see the conformation of the three ruling parts more clearly, that of the parts of the stomach more dimly, and much more still, that of the limbs. Later on they form "twigs", as Hippocrates expressed it, indicating by the term their similarity to branches. The fourth and final period is at the stage when all the parts in the limbs have been differentiated; and at this part Hippocrates the marvelous no longer calls the foetus an embryo only, but already a child, too when he says that it jerks and moves as an animal now fully formed (Arabic ‘a new creation’) ...


... The time has come for nature to articulate the organs precisely and to bring all the parts to completion. Thus it caused flesh to grow on and around all the bones, and at the same time ... it made at the ends of the bones ligaments that bind them to each other, and along their entire length it placed around them on all sides thin membranes, called periosteal, on which it caused flesh to grow [19].



Qur'an: Sura 23:13-14 in Arabic for comparison




English translation:


Thereafter We made him (the offspring of Adam) as a Nutfah (mixed drops of the male and female sexual discharge and lodged it) in a safe lodging (womb of the woman). Then We made the Nutfah into a clot (Alaqa, a piece of thick coagulated blood), then We made the clot into a little lump of flesh (Mudghah), then We made out of that little lump of flesh bones, then We clothed the bones with flesh, and then We brought it forth as another creation. So blessed be Allah, the Best of Creators!


The first stage, geniture, corresponds to [nutfah], the drop of semen; the second stage, a bloody vascularised foetus with unshaped brain, liver and heart ("when it has been filled with blood") corresponds to [alaqa], the blood clot; the third stage "has the form of flesh" and corresponds to [mudghah], the morsel of chewed flesh. The fourth and final stage, puer, was when all the organs were well formed, joints were freely moveable, and the foetus began to move [20]. If the reader is in any doubt about the clear link being described here between the Galenic and the Qur'anic stages, it may be pointed out that it was early Muslim doctors, including Ibn-Qayyim, who first spotted the similarity. Basim Musallam, Director of the Centre of Middle Eastern Studies at the University of Cambridge concludes


"The stages of development which the Qur'an and Hadith established for believers agreed perfectly with Galen's scientific account ... There is no doubt that medieval thought appreciated this agreement between the Qur'an and Galen, for Arabic science employed the same Qur'anic terms to describe the Galenic stages" [21].

QMRHistory of Embryology

I discussed in my books that there is actually four stages in embryos and that there are four parts of the embryo the fourth being the neural crest (the different part)

Hippocrates said there were four stages of the embryo

460-370 BC Hippocrates 1st stage: "Sperm is a product which comes from the whole body of each parent, weak sperm coming from the weak parts, and strong sperm from the strong parts."[4]

2nd stage: "The seed (embryo), then, is contained in a membrane ... Moreover, it grows because of its mother's blood, which descends to the womb. For once a woman conceives, she ceases to menstruate..."[5] 3rd stage: "At this stage, with the descent and coagulation of the mother's blood, flesh begins to be formed, with the umbilicus."[6]

4th stage: "As the flesh grows it is formed into distinct members by breath ... The bones grow hard ... moreover they send out branches like a tree ..."[7]

129-210 AD Claudius Galenus "let us divide the creation of the foetus overall into four periods of time.

The first is that in which. as is seen both in abortions and in dissection, the form of the semen prevails [Arabic nutfah]. At this time, Hippocrates too, the all-marvelous, does not yet call the conformation of the animal a foetus; as we heard just now in the case of semen voided in the sixth day, he still calls it semen. But when it has been filled with blood [Arabic alaqa], and heart, brain and liver are still unarticulated and unshaped yet have by now a certain solidarity and considerable size,

this is the second period; the substance of the foetus has the form of flesh and no longer the form of semen. Accordingly you would find that Hippocrates too no longer calls such a form semen but, as was said, foetus.

The third period follows on this, when, as was said, it is possible to see the three ruling parts clearly and a kind of outline, a silhouette, as it were, of all the other parts [Arabic mudghah]. You will see the conformation of the three ruling parts more clearly, that of the parts of the stomach more dimly, and much more still, that of the limbs. Later on they form "twigs", as Hippocrates expressed it, indicating by the term their similarity to branches.

The fourth and final period is at the stage when all the parts in the limbs have been differentiated; and at this part Hippocrates the marvelous no longer calls the foetus an embryo only, but already a child, too when he says that it jerks and moves as an animal now fully formed."[11]

"... The time has come for nature to articulate the organs precisely and to bring all the parts to completion. Thus it caused flesh to grow on and around all the bones, and at the same time ... it made at the ends of the bones ligaments that bind them to each other, and along their entire length it placed around them on all sides thin membranes, called periosteal, on which it caused flesh to grow."[12]

ca. 200 AD Talmud (Jewish text) The embryo was called peri habbetten (fruit of the body) and develops as:

1. golem (formless, rolled-up thing);

2. shefir meruqqam (embroidered foetus - shefir means amniotic sac); 

3. 'ubbar (something carried); v'alad (child); v'alad shel qayama (noble or viable child) and 

4. ben she-kallu chadashav (child whose months have been completed).[13

Merk Diezle shared a link.

Aug 29, 2016 5:57pm

Ramachandran plot - Wikipedia, the free encyclopedia

In my qmr books i discussed the ramachandran plot is a quadrant with the fourth square being different as well as many other things in biology you would be amazed ((i went to classes all day everyday in biology and chemistry it was all quadrant model i wrote it in notebooks but i havent gone through the notebooks yet)


Merk Diezle shared a link.
Aug 29, 2016 5:39pm
Penrose diagram - Wikipedia, the free encyclopedia
Penrose diagrams the basis of black hole studies are quadrants as well as kruskal szekeres diagrams are also quadrants with four aspects


This is in my first book- the fourth is always different

Spermatogenesis has equivalent meiotic divisions resulting in four equivalent spermatids while oogenic meiosis is asymmetrical: only one egg is formed together with three polar bodies (four all together)


Thus, the primary spermatocyte gives rise to two cells, the secondary spermatocytes, and the two secondary spermatocytes by their subdivision produce four spermatozoa.[1]



Some algae and the oomycetes produce eggs in oogonia. In the brown alga Fucus, all four egg cells survive oogenesis, which is an exception to the rule that generally only one product of female meiosis survives to maturity.



The liver is a reddish-brown wedge-shaped organ with four lobes of unequal size and shape. A human liver normally weighs 1.44–1.66 kg (3.2–3.7 lb).[9] It is both the heaviest internal organ and the largest gland in the human body. Located in the right upper quadrant of the abdominal cavity, it rests just below the diaphragm, to the right of the stomach and overlies the gallbladder.[4]


Other anatomical landmarks exist, such as the ligamentum venosum and the round ligament of the liver (ligamentum teres), which further divide the left side of the liver in two sections. An important anatomical landmark, the porta hepatis, also known as the transverse fissure of the liver, divides this left portion into four segments, which can be numbered starting at the caudate lobe as I in an anticlockwise manner. From this visceral view, seven segments can be seen, because the eighth segment is only visible in the parietal view.[15]


The heart pumps oxygenated blood to the body and deoxygenated blood to the lungs. In the human heart there is one atrium and one ventricle for each circulation, and with both a systemic and a pulmonary circulation there are four chambers in total: left atrium, left ventricle, right atrium and right ventricle

Tetrad of Narcolepsy
Sleep Paralysis 

Quadrumana and Bimana form an obsolete division of the primates: the Quadrumana are primates with four hands (two attached to the arms and two attached to the legs), and the Bimana are those with two hands and two feet. The attempted division of "Quadrumana" from "Bimana" forms a stage in the long campaign to find a secure way of distinguishing Homo sapiens from the rest of the great apes, a distinction that was culturally essential.[according to whom?]

Quadrumana is Latin for "four-handed ones", which is a term used for apes since they do not have feet attached to their legs as humans do, but instead have hands, as both pairs of hands look almost alike (with the exception of the orangutan, whose hands look exactly the same) and operate exactly like hands.

Bimana is Latin for "two-handed ones", which is a term used for humans, as humans have only two hands, but have two feet which apes do not.

The division was proposed by Johann Friedrich Blumenbach in the first edition of his Manual of Natural History (1779) and taken up by other naturalists, most notably Georges Cuvier.[1] Some elevated the distinction to the level of an order.

However, the many affinities between humans and other primates – and especially the great apes – made it clear that the distinction made no scientific sense. In 1863, however, Thomas Henry Huxley in his Evidence as to Man's Place in Nature demonstrated that the higher apes might fairly be included in Bimana.[2] Charles Darwin wrote, in The Descent of Man (1871):

“ The greater number of naturalists who have taken into consideration the whole structure of man, including his mental faculties, have followed Blumenbach and Cuvier, and have placed man in a separate Order, under the title of the Bimana, and therefore on an equality with the orders of the Quadrumana, Carnivora, etc. Recently many of our best naturalists have recurred to the view first propounded by Linnaeus, so remarkable for his sagacity, and have placed man in the same Order with the Quadrumana, under the title of the Primates. The justice of this conclusion will be admitted: for in the first place, we must bear in mind the comparative insignificance for classification of the great development of the brain in man, and that the strongly marked differences between the skulls of man and the Quadrumana (lately insisted upon by Bischoff, Aeby, and others) apparently follow from their differently developed brains. In the second place, we must remember that nearly all the other and more important differences between man and the Quadrumana are manifestly adaptive in their nature, and relate chiefly to the erect position of man; such as the structure of his hand, foot, and pelvis, the curvature of his spine, and the position of his head.


The older term, autecology (from Greek: αὐτο, auto, "self"; οίκος, oikos, "household"; and λόγος, logos, "knowledge"), refers to roughly the same field of study as population ecology. It derives from the division of ecology into autecology—the study of individual species in relation to the environment—and synecology—the study of groups of organisms in relation to the environment—or community ecology. Odum (1959, p. 8) considered that synecology should be divided into population ecology, community ecology, and ecosystem ecology, defining autecology as essentially "species ecology."[1] However, for some time biologists have recognized that the more significant level of organization of a species is a population, because at this level the species gene pool is most coherent. In fact, Odum regarded "autecology" as no longer a "present tendency" in ecology (i.e., an archaic term), although included "species ecology"—studies emphasizing life history and behavior as adaptations to the environment of individual organisms or species—as one of four subdivisions of ecology.

Several animal species, including humans, tend to live in groups. Group size is a major aspect of their social environment. Social life is probably a complex and effective survival strategy. It may be regarded as a sort of symbiosis among individuals of the same species: a society is composed of a group of individuals belonging to the same species living within well-defined rules on food management, role assignments and reciprocal dependence.

When biologists interested in evolution theory first started examining social behaviour, some apparently unanswerable questions arose, such as how the birth of sterile castes, like in bees, could be explained through an evolving mechanism that emphasizes the reproductive success of as many individuals as possible, or why, amongst animals living in small groups like squirrels, an individual would risk its own life to save the rest of the group. These behaviours may be examples of altruism.[34] Of course, not all behaviours are altruistic, as indicated by the table below. For example, revengeful behaviour was at one point claimed to have been observed exclusively in Homo sapiens. However, other species have been reported to be vengeful including chimpanzees,[35] as well as anecdotal reports of vengeful camels.[36]

Classification of social behaviours
Type of behaviour Effect on the donor Effect on the receiver
Egoistic Increases fitness Decreases fitness
Cooperative Increases fitness Increases fitness
Altruistic Decreases fitness Increases fitness
Revengeful Decreases fitness Decreases fitness

Jonathan P. Niednagel developed a system that categorizes brain types, which he claims was inspired by the Myers Briggs and Socionics personality models. They are

Square 1: Empirical-Animate' types (FEAL, FEAR, BEAL, BEAR), are thought to be the best in the region of the brain responsible for gross motor skills

Square 2: EI, or 'Empirical-Inanimate' types (FEIL, FEIR, BEIL, BEIR) are believed to excel with fine motor skills of the four groups

Square 3: CA, or 'Conceptual-Animate' types (FCAL, FCAR, BCAL, BCAR), excel in the auditory cortex

Square 4:CI, or 'Conceptual-Inanimate' types (FCIL, FCIR, BCIL, BCIR), are thought to be the best in the cerebral cortex, where there is abstract levels of reasoning

CHON is a mnemonic acronym for the four most common elements in living organisms: carbon, hydrogen, oxygen, and nitrogen. They make up like 99 percent of life.


The questionable fifth is phosophorous. Nitrogen is somewhat rare, but phosphorous is extremely rare (but very important, being a part of DNA). The fourth is always different/transcendent. The fifth ultra transcendent.

Four elements make up most living things — including you! The elements are carbon, hydrogen, oxygen, and nitrogen. Download this free lesson sheet and help give kids an understanding of these four essential elements and their basic attributes.

One of the first things learned in biology class in college is the amino acid structure. Amino acids are the building blocks of proteins. The structure consists of four parts. They are

Square 1: the H group

Square 2: the Amino group

Square 3: the Carboxyl group

Square 4: the R group

In the first few weeks of biology class in college the professors also teach the levels of protein structure. The levels fit the quadrant model pattern. They are

Square 1: The primary structure. The primary structure of a protein is the linear sequence of amino acids in the polypeptide chain. The primary structure is held together by covalent bonds such as peptide bonds.

Square 2: The secondary structure. Secondary structure is highly regular local sub-structures on the polypeptide backbone chain. Two main types of secondary structure are the alpha helix and the beta strand or beta sheets.

Square 3: The tertiary structure. Tertiary structure is a three-dimensional structure of monomeric and multimeric protein molecules. The alpha-helixes and beta pleated-sheets are folded into a compact globular structure. The third square is always more solid and more physical. That is the nature of the territory structure.

Square 4: Quaternary structure. Quaternary structure is the three-dimensional structure of a multi-subunit protein and how the subunits fit together. Quaternary structure is stabilized by the same non-covalent interactions and disulfide bonds as the tertiary structure. Complexes of two or more polypeptides (i.e. multiple subunits) are called multimers.


Amino acids are usually classified by the properties of their side-chain into four groups. The side-chain can make an amino acid a weak acid or a weak base, and a hydrophile if the side-chain is polar or a hydrophobe if it is nonpolar.[34] The chemical structures of the 22 standard amino acids, along with their chemical properties, are described more fully in the article on these proteinogenic amino acids.


22 amino acids like 22 letters of Hebrew Alphabet

Proteins are much more complicated than just a chain of amino-acids because proteins fold spontaneously depending on the R groups in their amino-acid sequence. The structure of proteins is very important for their function. The protein folding process can be divided up into four stages, which we can think of as stages in putting together a book:


Primary structure: a chain of amino-acids joined together (letters coming together to form words)

Secondary structure: the chains fold into sheets or coils (sentences)

Tertiary structure: the sheets or coils fold in on one another (chapters of a book) 4. Quaternary structure: amino-acid chains folded in their tertiary structure interact with one another to give the final functional protein (e.g. haemoglobin has 4 chains) (a book)


Figure 3. The standard Genetic Code Table with designation of four diversity types of protein amino acids and corresponding codons: first and second type without color (in light and dark tones, respectively), but third and forth in color. The codon number: first 08, second 17, third 10 and fourth 26 [just as in algebraic system in Solution (4.2)]. The roman numbers designate class I and class II of aminoacyl-tRNA synthetases as in Table E3. The details see in the text.

I'm a paragraph. Click here to add your own text and edit me. It's easy.

I'm a paragraph. Click here to add your own text and edit me. It's easy.

I'm a paragraph. Click here to add your own text and edit me. It's easy.

Here is an excerpt from my book QMR
The monarch butterfly is considered the king of the butterflies, and the phenomena associated with the monarch butterfly fit the quadrant model pattern. Monarch butterflies go through four stages during one life cycle. They are
Square 1: the egg
Square 2: the larvae (caterpillar)
Square 3: the pupa (chrysalis)
Square 4: the adult butterfly (the transformation)
The life cycles of the Monarch butterfly are four generations. They fit the quadrant model pattern. They are
Square 1: in March and April eggs are laid in milkweed plants. The monarch butterflies that are born live for two to six weeks. and lay eggs
Square 2: in May and June the same the Monarch butterflies do the same thing as square 1.
Square 3: in July and August the Monarch butterflies do the same thing as square 1 and 2.
Square 4: The fourth generation is born in September and October and goes through exactly the same process as the first, second and third generations except for one part. The fourth generation of monarch butterflies does not die after two to six weeks. Instead, this generation of monarch butterflies migrates to warmer climates like Mexico and California and will live for six to eight months until it is time to start the whole process over again. The fourth square is always different from the previous three squares. The life of the Monarch butterfly reveals the quadrant model pattern. The first three are the same and almost identical. The fourth has a transcendent quality to it.

The human sexual response cycle is a FOUR-stage model of physiological responses to sexual stimulation,[1] which, in order of their occurrence, are the excitement phase, plateau phase, orgasmic phase, and resolution phase. The cycle was first proposed by William H. Masters and Virginia E. Johnson in their 1966 book Human Sexual Response.[1][2] Since then, other human sexual response models have been formulated.

Excitement phase[edit]
The excitement phase (also known as the arousal phase or initial excitement phase) is the first stage of the human sexual response cycle. It occurs as the result of physical or mental erotic stimuli, such as kissing, petting, or viewing erotic images, that leads to sexual arousal. During the excitement stage, the body prepares for sexual intercourse, initially leading to the plateau phase.[1] There is wide socio-cultural variation regarding preferences for the length of foreplay and the stimulation methods used.[citation needed] Physical and emotional interaction and stimulation of the erogenous zones during foreplay usually establishes at least some initial arousal.[citation needed]

Excitement in both sexes[edit]
See also: Flushing (physiology)
Among both sexes, the excitement phase results in an increase in heart rate, breathing rate, and a rise in blood pressure.[1] A survey in 2006 has found that sexual arousal in about 82% of young females and 52% of young males arises or is enhanced by direct stimulation of nipples, with only 7–8% reporting that it decreased their arousal.[3] Vasocongestion of the skin, commonly referred to as the sex flush, will occur in approximately 50-75% of females and 25% of males. The sex flush tends to occur more often under warmer conditions and may not appear at all under cooler temperatures.

During the female sex flush, pinkish spots develop under the breasts, then spread to the breasts, torso, face, hands, soles of the feet, and possibly over the entire body.[1] Vasocongestion is also responsible for the darkening of the clitoris and the walls of the vagina during sexual arousal. During the male sex flush, the coloration of the skin develops less consistently than in the female, but typically starts with the epigastrium (upper abdomen), spreads across the chest, then continues to the neck, face, forehead, back, and sometimes, shoulders and forearms. The sex flush typically disappears soon after orgasm occurs, but this may take up to two hours or so and, sometimes, intense sweating will occur simultaneously. The flush usually diminishes in reverse of the order in which it appeared.[2]

An increase in muscle tone (myotonia) of certain muscle groups, occurring voluntarily and involuntarily, begins during this phase among both sexes. Also, the external anal sphincter may contract randomly upon contact (or later during orgasm without contact).

Excitement in males[edit]
In males, the beginning of the excitement phase is observed when the penis becomes partially erect, often after only a few seconds of erotic stimulation.[1] The erection may be partially lost and regained repeatedly during an extended excitement phase. Both testicles become drawn upward toward the perineum, notably in circumcised males where less skin is available to accommodate the erection. Also, the scrotum can tense and thicken during the erection process.

Excitement in females[edit]
In females, the excitement phase can last from several minutes to several hours. The onset of vasocongestion results in swelling of the woman's clitoris, labia minora and vagina. The muscle that surrounds the vaginal opening grows tighter and the uterus elevates and grows in size. The vaginal walls begin to produce a lubricating organic[clarification needed] liquid.[1] Meanwhile, the breasts increase slightly in size and nipples become hardened and erect.

Plateau phase[edit]
The plateau phase is the period of sexual excitement prior to orgasm. The phase is characterised by an increased circulation and heart rate in both sexes, increased sexual pleasure with increased stimulation, and further increased muscle tension. Also, respiration continues at an elevated level.[1] Both men and women may also begin to vocalize involuntarily at this stage. Prolonged time in the plateau phase without progression to the orgasmic phase may result in frustration if continued for too long (see orgasm control).

Plateau in males[edit]
During this phase, the male urethral sphincter contracts (so as to prevent urine from mixing with semen, and to guard against retrograde ejaculation) and muscles at the base of the penis begin a steady rhythmic contraction.[1] Males may start to secrete seminal fluid or pre-ejaculatory fluid and the testicles rise closer to the body.[2]

Plateau in females[edit]
The plateau stage in females is basically a continuation of the same changes evident in the excitement stage. The clitoris becomes extremely sensitive and withdraws slightly and the Bartholin glands produce further lubrication. The tissues of the outer third of the vagina swell, and the pubococcygeus muscle tightens, reducing the diameter of the opening of the vagina.[1] Masters and Johnson refer to the changes that take place during the plateau stage as the orgasmic platform. For those who never achieve orgasm, this is the peak of sexual excitement.

Orgasmic phase[edit]
Main article: Orgasm
Orgasm is the conclusion of the plateau phase of the sexual response cycle and is experienced by both males and females. It is accompanied by quick cycles of muscle contraction in the lower pelvic muscles, which surround both the anus and the primary sexual organs. Women also experience uterine and vaginal contractions. Orgasms are often associated with other involuntary actions, including vocalizations and muscular spasms in other areas of the body, and a generally euphoric sensation. Heart rate is increased even further.[1]

Orgasm in males[edit]
In men, orgasm is usually associated with ejaculation. Each ejection is accompanied with continuous pulses of sexual pleasure, especially in the penis and loins.[1] Other sensations may be felt strongly among the lower spine, or lower back. The first and second convulsions are usually the most intense in sensation, and produce the greatest quantity of semen. Thereafter, each contraction is associated with a diminishing volume of semen and a milder sensation of pleasure.[1]

Orgasm in females[edit]
Orgasms in females can vary widely from woman to woman. The overall sensation is similar to that of the male orgasm. They are commonly associated with an increase in vaginal lubrication, a tightening of the vaginal walls, and overall pleasure.[1]

Resolution phase[edit]
Main article: Refractory period (sex)
The resolution phase occurs after orgasm and allows the muscles to relax, blood pressure to drop and the body to slow down from its excited state.[1] The refractory period, which is part of the resolution phase, is the time frame in which usually a man is unable to orgasm again, though women can also experience a refractory period.

Resolution in males[edit]
Masters and Johnson described the two-stage detumescence of the penis: In the first stage, the penis decreases from its erect state to about fifty percent larger than its flaccid state. This occurs during the refractory period. In the second stage (and after the refractory period is finished), the penis decreases in size and returns to being flaccid.[2] It is generally impossible for men to achieve orgasm during the refractory period.[2][4][5] Masters and Johnson argue that this period must end before men can become aroused again.[6]

Resolution in females[edit]
According to Masters and Johnson, women have the ability to orgasm again very quickly, as long as they have effective stimulation. As a result, they are able to have multiple orgasms in a relatively short period of time.[2][6] Though generally reported that women do not experience a refractory period and thus can experience an additional orgasm, or multiple orgasms, soon after the first,[4][5] some sources state that men and women experience a refractory period because women may also experience a period after orgasm in which further sexual stimulation does not produce excitement.[7][8] For some women, the clitoris is very sensitive after climax, making additional stimulation initially painful.[9] After the initial orgasm, subsequent orgasms for women may also be stronger or more pleasurable as the stimulation accumulates.[9]

Here is another excerpt from my book the quadrant model of reality.
The layers of the stomach and gastrointestinal tract represent the quadrant model pattern. They are
Square 1: the mucosa layer. This layer sort of helps against pathogens. The first square is kind of a protective square, representing the idealist.
Square 2: the submucosa layer. The first two squares are the duality. This layer is made of connective tissue and kind of holds things together. The second square is homeostasis.
Square 3: the muscular layer. The third square is the doing square. This is the part of the digestive system that contracts that allows the food to pass through.
Square 4: serous membrane. The fourth square is different from the previous three.
Here is another excerpt from my book the quadrant model of reality.
The layers of the stomach and gastrointestinal tract represent the quadrant model pattern. They are
Square 1: the mucosa layer. This layer sort of helps against pathogens. The first square is kind of a protective square, representing the idealist.
Square 2: the submucosa layer. The first two squares are the duality. This layer is made of connective tissue and kind of holds things together. The second square is homeostasis.
Square 3: the muscular layer. The third square is the doing square. This is the part of the digestive system that contracts that allows the food to pass through.
Square 4: serous membrane. The fourth square is different from the previous three.
Stanislov Grof is a celebrated transpersonal psychologist who studied birth trauma. According to Grof there are four "hypothetical dynamic matrices in charge of the processes related to the perinatal level of the unconsciousness", called "basic perinatal matrices". These BPM's correspond to the stages of birth during the process of childbirth. Grof argued that during times of extraordinary distress, you undergo a kind of death in which these birth experiences are relived. They are
Square 1: BPM 1- the amniotic universe. This is the symbiotic unity between the Mother and the fetus.This state can be connected with experiences of a lack of boundaries and obstructions, such as the ocean and the cosmos. The extraordinary sentiment of the sacred and spiritual quality of BPM I is the experience of cosmic unity. The first square is the idealist, and the idealist is associated with spirituality and optimism.
Square 2: BPM 2-Cosmic Engulfment and No Exit. This matrix begins with the onset of labor. The experience of chemicals and the pressures of labor "interrupt the fetus’ blissful connection with the mother and alter its pristine universe." Experiencing this layer gives rise to a sense of "no escape", loneliness and helplessness is overwhelming.
Square 3: BPM 3- The Death-Rebirth Struggle.This matrix is associated with the move of the fetus through the birth channel. The third square is always the doing square. This matrix is concerned with a struggle for survival. When experiencing this layer, strong aggression and demonic forces are contacted. Memories associated with this matrix involve struggles, fights, and adventurous activities. The third square is always considered bad and violent.
Square 4: BPM 4-The Death-Rebirth Experience. The fourth square is associated with death. According to Grof, this matrix is connected to the stage of delivery, the actual birth of the child. Tension, pain and anxiety is released. The symbolic counterpart is the Death-Rebirth Experience. The transition from BPM III to BPM IV may involve a sense of total annihilation. Grof refers to this stage as an ego death. I discussed that the fourth square is the flow and knowledge. and is related to the death of the ego.…/the-four-stages-of-bir…/
Eighty years ago, Austrian psychoanalyst Otto Rank theorized that when we are born, we experience a “birth trauma” that affects us for the rest of our lives. More recently, psychiatrist Stanislav Grof has created a model for understanding in greater depth the kinds of effects that birth can have upon our later lives. He writes that there are four distinct stages of birth, or what he calls Basic Perinatal Matrices (BPM) that give rise to different kinds of traumas (as well as positive experiences), and that have different types of effects upon our future development. 

Basic Perinatal Matrix I (BPM I)represents that point in the birth process when labor has not yet started and we are still fully inside of the mother’s uterus. This can be a “good womb” or “bad womb” situation (or a combination of both), depending upon the circumstances. Stress hormones from our mothers might create anxiety in utero and/or nurturing hormones could create pleasant feelings. The surrealist artist Salvador Dali wrote in his autobiography that his own bad womb experience (his parents were in despair over the death of his brother at the time) haunted him for the rest of his life.

Basic Perinatal Matrix II (BPM II) is that point in the birth when labor has started and we are being pushed up against the cervix by the mother’s contractions but the cervix has not yet begun to dilate or open. This can be a very scary experience, and people in later life who were traumatized at this point in their birth may feel claustrophobia, existential angst, depression, feelings of terror, or other negative consequences. Edgar Allen Poe may have been a BPM II baby as evidenced by his short story “The Pit and the Pendulum” where a character finds himself in a prison where walls are closing in on him and the only way out is down a bottomless pit. 

Basic Perinatal Matrix III (BPM III) is when the cervix has opened and we start to move out (or push out) through the birth canal. This can be both thrilling and also violent or dangerous (for example, the umbilical cord might strangle the fetus at this point). People who get fixated at this point in their births may grow up to become thrill-seekers, but also potentially dangerous individuals. Adolf Hitler may have been a BPM III baby with his violent policies and his fixation on strangulation (he often had his enemies strangled).

The final stage of birth, Basic Perinatal Matrix IV (BPM IV) is when we have left the womb and are now outside in the world. This stage may be associated in later life with feelings of expansion (possibly even agoraphobia), feelings of rebirth (perhaps associated with religious experiences), and also feelings of separation and loneliness. People who have undergone dramatic religious conversions, such as the French philosopher Blaise Pascal or the Apostle Paul of Tarsus, may have re-experienced this stage of birth during their spiritual transformations in adulthood.

Grof originally discovered the presence of these four basic perinatal matrices when using psychedelic (LSD) therapy with patients suffering from mental disorders in Europe and the United States (he was the Chief of Psychiatric Research at the Maryland Psychiatric Research Center in the late 1960’s and early 1970’s). He is currently using a method he developed called Holotropic Breathwork that both reveals and heals the traumas associated with these basic perinatal matrices (as well as experiences associated with other stages of development such as early childhood). To find out more about Grof’s birth model, or other aspects of his important work, see the following resources:–Urey_experiment

The Miller Urey experiement was an unprecedented experiment in origins of life research, which demonstrated that amino acids, which are necessary to create DNA and life, could be produced with the combination of just four natural components. These components were

Square 1: water

Square 2: methane

Square 3: ammonia

Square 4: hydrogen

If these four components were put in a steel flask, and lighting was added (the fifth component; the fifth square is representative of God and light is related with God), then amino acids would generate. It was thought that this experiment could prove that there may have been a "natural" genesis of life on Earth.

The 4 “P’s” of Birth – The Need to Sync your Body, your Baby and Your Mind


When most of us hear about birth it’s in the singular, “When I was in labor…” or “The baby just didn’t budge.” or “They told me my pelvis was just too small.” or “I felt really strong and proud of giving birth naturally.” All of these things describe just one component of labor and birth. The reality is, that birth is a complex event and all four aspects need to come together to make this birth happen.

These 4 components to the birth process are: the passageway (pelvis), the passenger, the powers and the psyche. All of these must work together in synchronicity to achieve a successful, vaginal birth. Think of them as gears in a machine. If one of the gears is misaligned, then the whole machine malfunctions.

The Passageway (a.k.a The Pelvis):

I want to first talk about the pelvic inlet and the pelvic outlet. The pelvic inlet is the top opening of the pelvis. This is the part the baby’s head enters first. The pelvic outlet is where the baby’s head (and body!) exits mom. These dimensions need to be sized sufficiently to allow baby to maneuver comfortably through the pelvis for birth.

The tailbone (sacrum or coccyx) needs to be sufficiently mobile to be gently pressed back out of the way when baby moves through. Your sacroiliac joint allows this nutation or counter-nutation of the sacrum.

The symphisis pubis is a cartilaginous joint in the front of the pelvis. It also needs to be properly mobile to help the pelvis flex to allow baby to pass through. The relaxin hormone in your body helps both the tailbone and the symphisis pubis become more mobile to facilitate birth.

So, all of the physical components of the pelvis need to be working, moving, properly to facilitate birth.

The Passenger:

Yep. This would be the baby. Mom carries the baby, hence the term passenger. The baby needs to be positioned properly to make it through the pelvis. The optimal position for birth is Occiput Anterior (OA). However, babies can be born vaginally in a number of positions. To learn more about their positions in the womb (and how you can influence it) check out Spinning Babies.

What’s important to know here is that if baby is mal-positioned, she will have trouble fitting through the passageway, possibly necessitating a c-section.

The other things to note in regards to baby is their desire to be born and their sense of safety outside the womb. Our babies are strongly intuitive beings. They know when mom is fearful, or uncomfortable emotionally. This can have an impact on how baby will choose to be born. (see Psyche below for mom’s mental state)

The Powers:

These are your contractions and your additional efforts for pushing. Your contractions need to be strong enough to dilate the cervix and aid the baby in his decent. They need to be at regular intervals, moving closer together and increasing in strength throughout labor. On the flip side, they can’t be too strong, or too intense or you have a case of fetal distress and / or a mom who can’t cope with her contractions without medical interventions. If the contractions are too weak or not at regular enough intervals, your care provider might suggest using Pitocin (synthetic oxytocin) to amp them up.

The Psyche:

The Psyche is another word for you your emotional state during birth. If mom is afraid, tense, stressed out, angry, feels unsafe or unsupported, she will not likely do well during birth. For some, the fear is intense enough to schedule a c-section and to avoid a vaginal birth all together. For others, it may prevent cervical dilation, fetal decent, or prevent mom from pushing effectively. (Think Ina May’s “Sphincter Law”).

A good emotional state helps mom cope with the pain effectively; helps her tune in to her body; helps guide her to her baby’s needs and allows the other 3 P’s to sync up effectively. A mom who’s psyche is healthy, strong and who has good support during labor, will have a good birth. Regardless of the medical interventions she may need, she will ride her labor to a birth experience she will remember with a strong heart and a peaceful mind.

There is no one “P” that can work without the others. All four must be working properly for baby to join the world in the way they are intended. The “P’s” can be influenced by mom’s movements, position, her care provider, her support people, and medical intervention. Birth is a complicated, multifaceted, life-changing event. Get yourself in a good head-space and you will be able to work with issues that may arise with the Passageway, the Passenger and the Powers.

There are four articulations within the pelvis:

Sacroiliac Joints (x2) – Between the ilium of the hip bones, and the sacrum

Sacrococcygeal symphysis – Between the sacrum and the coccyx.

Pubic symphysis – Between the pubis bodies of the two hip bones.


Caldwell-Moloy classification[edit]

Throughout the 20th century pelvimetric measurements were made on pregnant women to determine whether a natural birth would be possible, a practice today limited to cases where a specific problem is suspected or following a caesarean delivery. William Edgar Caldwell and Howard Carmen Moloy studied collections of skeletal pelves and thousands of stereoscopic radiograms and finally recognized three types of female pelves plus the masculine type. In 1933 and 1934 they published their typology, including the Greek names since then frequently quoted in various handbooks: Gynaecoid (gyne, woman), anthropoid (anthropos, human being), platypelloid (platys, flat), and android (aner, man). [40][41]


The gynaecoid pelvis is the so-called normal female pelvis. Its inlet is either slightly oval, with a greater transverse diameter, or round. The interior walls are straight, the subpubic arch wide, the sacrum shows an average to backward inclination, and the greater sciatic notch is well rounded. Because this type is spacious and well proportioned there is little or no difficulty in the birth process. Caldwell and his co-workers found gynaecoid pelves in about 50 per cent of specimens.

The platypelloid pelvis has a transversally wide, flattened shape, is wide anteriorly, greater sciatic notches of male type, and has a short sacrum that curves inwards reducing the diameters of the lower pelvis. This is similar to the rachitic pelvis where the softened bones widen laterally because of the weight from the upper body resulting in a reduced anteroposterior diameter. Giving birth with this type of pelvis is associated with problems, such as transverse arrest. Less than 3 per cent of women have this pelvis type.

The android pelvis is a female pelvis with masculine features, including a wedge or heart shaped inlet caused by a prominent sacrum and a triangular anterior segment. The reduced pelvis outlet often causes problems during child birth. In 1939 Caldwell found this type in one third of white women and in one sixth of non-white women.

The anthropoid pelvis is characterized by an oval shape with a greater anteroposterior diameter. It has straight walls, a small subpubic arch, and large sacrosciatic notches. The sciatic spines are placed widely apart and the sacrum is usually straight resulting in deep non-obstructed pelvis. Caldwell found this type in one quarter of white women and almost half of non-white women.

The sacrum and coccyx also begin life as multiple bones before fusing. Five short, wide vertebrae fuse to form the wedge-shaped sacrum, while four tiny vertebrae fuse to form the coccyx.

The bones of the adult pelvis join together to form four joints: the left and right sacroiliac joints, the sacrococcygeal joint, and the pubic symphysis.

There are four major types of neurons based on their shape. Unipolar neurons are the most common neurons in invertebrates. These neurons are characterized by one primary projection that serves as both the axon and the dendrites.

Another type of neurons is the bipolar neurons, each having an axon that transmits signals from the cell body going to the brain and the spinal cord, and dendrites that send signals from the body organs to the cell body. These bipolar neurons are usually found in sensory organs such as the eyes, nose and ears.


Pseudo-unipolar neurons resemble unipolar neurons because each of them has an axon, but no true dendrites. However, pseudo-unipolar neurons are actually variants of bipolar neurons. The reason for this is that the single axon attached to the cell body proceeds to two opposite “poles” or directions – one towards the muscle, joints and skin, and the other towards the spinal cord. Pseudo-unipolar neurons are responsible for the sense of touch, pain and pressure.


Multipolar neurons are the dominating neurons in vertebrates in terms of number. These neurons are the ones that are the closest to the model neuron that we usually see in neuron structure diagrams. Each of them has a cell body, a long axon, and short dendrites.

In the female, there are four columns of erectile tissue in the superficial pouch: two crura of the clitoris, which fuse anteriorly to form the clitoris; and the two bulbs of the vestibule.

Each uterine tube is situated in the superior, free border and between the layers of the broad ligament. The uterine tube is subdivided into four parts, from lateral to medial: the infundibulum, ampulla, isthmus, and uterine part. The infundibulum, which is closely related to the ovary, contains the abdominal opening of the uterine tube, by which the tube is in communication with the peritoneal cavity. Oocytes pass from the ovary through the abdominal opening and along the uterine tube. The fimbriae are irregular fringes that project from the margin of the infundibulum, and one (ovarian fimbria) may be longer than the others. The ampulla, the longest and widest part, continues gradually into the isthmus. The uterine part, which lies in the wall of the uterus, contains the uterine opening of the uterine tube.

Figure 35-9 The blood supply to the female reproductive system. Extensive anastomoses occur between the ovarian and uterine arteries. Cervical branches of the uterine arteries anastomose across the median plane. The four-tiered concept of the reproductive system (A,B,C,D) is based on anatomical, physiological, and pathological data and may perhaps have embryological implications. For details see R. Contamin et al., Gynecol., 28:235-252, 1977.

Vaginal fornices:

At the upper end of the vagina, the anterior wall is pierced by the cervix which projects into it. The area of vaginal lumen, which surrounds the cervix, is divided into four fornices: anterior, posterior, right lateral and left lateral. These fornices are the deepest portions of the vagina, extending into the recesses created by the vaginal portion of the cervix.


All of this stuff is in my books

Stages. The estrous cycle can be divided into four stages: proestrus, estrus, metestrus, and diestrus. During proestrus the CL regresses (progesterone declines) and a preovulatory follicle undergoes its final growth phase (estradiol increases). Ovulation usually occurs during estrus (cows ovulate during metestrus). Proestrus and estrus comprise the follicular phase. Corpora lutea develop during metestrus and function at optimum during diestrus. Metestrus and diestrus make up the luteal phase.

The wall of the vagina from the lumen outwards consists firstly of a mucosa of non-keratinized stratified squamous epithelium with an underlying lamina propria of connective tissue, secondly a layer of smooth muscle with bundles of circular fibers internal to longitudinal fibers, and thirdly an outer layer of connective tissue called the adventitia. Some texts list FOUR layers by counting the two sublayers of the mucosa (epithelium and lamina propria) separately.[22][23] The lamina propria is rich in blood vessels and lymphatic channels. The muscular layer is composed of smooth muscle fibers, with an outer layer of longitudinal muscle, an inner layer of circular muscle, and oblique muscle fibers between. The outer layer, the adventitia, is a thin dense layer of connective tissue, and it blends with loose connective tissue containing blood vessels, lymphatic vessels and nerve fibers that is present between the pelvic organs.[11][23][15]

Folds of mucosa (or vaginal rugae) are shown in the front third of a vagina

A normal cervix of an adult as seen through the vagina (per vaginam or PV) using a bivalved vaginal speculum. The blades of the speculum are above and below and stretched vaginal walls are seen on the left and right.

The mucosa forms folds or rugae, which are more prominent in the caudal third of the vagina; they appear as transverse ridges and their function is to provide the vagina with increased surface area for extension and stretching. Where the vaginal lumen surrounds the cervix of the uterus, it is divided into FOUR continuous regions or vaginal fornices; these are the anterior, posterior, right lateral, and left lateral fornices.[9][10] The posterior fornix is deeper than the anterior fornix.[10] While the anterior and posterior walls are placed together, the lateral walls, especially their middle area, are relatively more rigid; because of this, the vagina has a H-shaped cross section.[10] Behind, the upper one-fourth of the vagina is separated from the rectum by the recto-uterine pouch. Superficially, in front of the pubic bone, a cushion of fat called the mons pubis forms the uppermost part of the vulva.

The uterus can be divided anatomically into four regions: The fundus, corpus (body), cervix and the internal os. The cervix protrudes into the vagina. The uterus is held in position within the pelvis by condensations of endopelvic fascia, which are called ligaments. These ligaments include the pubocervical, transverse cervical ligaments or cardinal ligaments, and the uterosacral ligaments. It is covered by a sheet-like fold of peritoneum, the broad ligament.[2]

A cross section of Fallopian tube shows four distinct layers: serosa, subserosa, lamina propria and innermost mucosal layer


The male urethra is comprised of four main segments. The preprostatic urethra runs in front of the prostate, while the prostatic urethra courses through that gland. The membranous urethra travels through the external urethral sphincter, while the spongy urethra travels the length of the penis and terminates at the meatus at the tip of the sexual organ.

The bony pelvis has four joints. In the front of the pelvis is the symphysis pubis joint. Movement here really isn’t that comfortable. Sometimes a pregnancy belt holds this joint stable for walking and rolling over in bed. Symmetry in the symphysis pubis (pubic bone) reduces spasm in the round ligaments and helps the sacrum, around back, to be aligned properly.

On either side of the sacrum are the SI joints (Sacroilliac joints). These are located where the dimples are. Many plastic baby dolls have SI dimples above their bum. The SI joints are a common location for aches when the pelvis is weak or crooked.

Symmetry in the SI joints will help the sacrum be lined up with the pelvic brim. Then the baby can get into a nice, head down position. A chiropractic adjustment helps get the symphysis and the SI joints aligned.

The sacrum, rather than fused, is slightly mobile and in the birth process actually moves to allow the head past.

The tailbone is connected by a joint to the lower end of the sacrum. Sometimes this needs an adjustment, too, especially after birthing a baby. Ligaments connecting to the sacrum and tailbone (coccyx) will become more symmetrical and their tone will be more relaxed and less in spasm after bodywork on the pelvis.

Four pelvic types

Pelvic types

Four general pelvic types are taught in midwifery and obstetrical schools. Caldwell-Malloy (1933) taught that nearly half of Caucasian women have a Gynecoid pelvis (rounder at the inlet, but wider side-to-side and a little less room front-to-back) while nearly half of women of African descent are said to have an Anthropoid pelvis (oval at the inlet, roomiest front-to-back of all pelvic types).

About 1/4 of all women have an android pelvis, with it’s triangular inlet and a bit smaller outlet than its own inlet. Only about 5% of women are said to have a platypelloid pelvis.

Kuliukas (2015). looked at 64 women and did not find a clustering of four types but a range throughout.

Kuliukas, A., Kuliukas, L., Franklin, D., & Flavel, A. (2015). Female pelvic shape: Distinct types or nebulous cloud?. British Journal of Midwifery, 23(7).

Some research is suggestive of pelvic shape, especially width, having to do with physical activity habits in childhood.

Cardadeiro, G., Baptista, F., Janz, K. F., Rodrigues, L. A., & Sardinha, L. B. (2014). Pelvis width associated with bone mass distribution at the proximal femur in children 10–11 years old. Journal of bone and mineral metabolism, 32(2), 174-183.

The variety of pelvic shapes, combined with the variety of fetal head presentations, plus size variations, mean that labors vary greatly.

In the drawing above, we see pelvic inlet shape and the correlating shape of the pubic arch at the outlet.


The Gynecoid pelvis has a roundish brim which allows fetal rotation when the muscles and ligaments in and around the pelvis aren’t tight and twangy.

gynecoid pelvis xray radiopaedia

The pelvic arch in front would allow three fingers to cover the urethra during a “potty dance” – the type of grab yourself and try not to pee your pants dance of a child waiting to get to the bathroom. Buttocks are round.

Hip size doesn’t indicate the roomy inside and a petite woman can birth a large baby. When the pelvic floor and other soft tissues aren’t overly tight, the birth tends to go well and a posterior baby can rotate at several various phases of labor.


The android pubic arch may hang quite low, giving a fundal height reading higher than the compact bump may seem to justify. Closely-set, small buttock “muscles” of the android make small roundish or triangular cheeks to her “bottom.” The android pelvis definitely has a 2 finger arch, rather than the 3 finger of the gynecoid.

Posterior arrest is slightly highAnatomy drawings by Gail Gynecoid or Androider for women with an android pelvis. Good fetal positioning, good flexibility in the pelvic joints and balance in the soft tissues help the natural labor progress. The posterior baby will hope to rotate before engagement or may not be able to rotate until the head fully passes the pelvis rotating on the perineum. Some posterior babies, the larger ones or if a mom can’t get out of bed to do some rotation exercises, will need a cesarean, even with a skilled baby spinner present. Manually rotating the baby’s head may be an option if a skilled doctor or midwife is present. A little help for the shoulders may be needed as the result of those women with low slung pubic bones. They may catch a shoulder.

Tall women with average size babies often birth without an issue. I recommend flexible and balanced muscles before labor begins. Some women will need to start working out chronic pelvic torsion early in pregnancy or even before.

Recently a woman told me her doctor felt she may not be able to have a vaginal birth after she previously had a cesarean for birthing her first child. She asked me what I thought. While I acknowledge there are more challenges with an android pelvis for some of these labors, most births through an android pelvis are going to be able to finish by the woman’s own efforts -and her baby’s. I said:

I do know that women in your shoes…in your hips… do give birth every day. 24% of Caucasian women have android pelvis, and, almost that for women of African descent. And these womens’ great great grandmothers were birthing their great grandmothers, and their grandmothers were birthing their mothers, and one of them birthed you.

Anthropoid pelvisAnthropoid

Long pelvis front-to-back, perhaps a narrow arch, perhaps not. Buttocks muscles look longer up and down than the round buttocks of a gynecoid. The Anthropoid pelvic arch can vary.

The arch could be a narrow 2 fingers or a wider 3 fingers at the pubic arch (as shown here in the illustration). Measure the pubic arch about 1/3 of the way between the clitoris and the sitz bones, rather than the very top.

Common for breeches that don’t flip. More posterior babies who are born vaginally may be arriving through the anthropoid pelvis. Vertical maternal positions aid these fetal positions and help birth be more protected and finish by the mother’s own efforts.


The pubic arch is a wide 4 finger span in the platypelloid, that is quite wide. A woman’s hips may seem slightly wider side-to-side than her weight would demand.

In other words, a thin woman with a platypelloid pelvis has wide hips but her pelvis from front and back is quite narrow. Her sitz bones are quite wide apart, more than the width of her fist (if she can reach between them while lying down).

Baby really needs to be in the LOT position to get INTO the pelvic brim for engagement. Long early labor is common, but if baby isn’t LOT, the two days of labor will be all about getting baby rotated and strong contractions and mobility are essential. Once baby is into the pelvis labor tends to move along, within 5-8 hours of engagement. Pushing may not be very long because the outlet of the pelvis is large. Using Daily Essentials: Activities for Pregnancy Comfort & Easier Childbirth, and Spinning Babies Parent Class may help your baby get into an LOT or other ideal position.

four pelvic cavities

The pelvic cavities of Gynecoid, Anthropoid, Android (narrowest at the bottom) and Platypelloid (widest at the bottom, narrow at the front to back at the top)


Which conclusions about how to fit pelvic shape into a label or category is less important to me than having a set of skills to identify what is going on between the baby and the mother at the inlet or other diameters of the pelvis and what we can do to help when help is indeed appropriate.

Here’s a story of how a woman who had a cesarean for her first baby who couldn’t engage in her pelvis went on to use The 3 Principles of Spinning Babies for her second birth:

Dear Gail: Just wanted you to know that the VBAC mom with the platypelloid pelvis had a successful unmedicated birth; surges were very intense with back labor for about 2 1/2 hours, mom was about 8cm dilated until the quality changed into a much more do-able intensity.

What helped was being on all fours, knee-chest position, strong hip squeezes, rebozo > standing did not work for a long time, just too intense, I think the walk to the car to transition to the hospital was helpful though – from there on it seemed so much easier. Active labor lasted just 3 hours, ½ hour pushing – the baby was sitting on the right side throughout the pregnancy, I think ROT; this mom was very dedicated, did chiropractic work (Webster technique) & craniosacral therapy – but the baby stayed on the right side; once we arrived in the hospital baby’s heartbeat was found on the left – I think the baby was born LOA; just saw this mom yesterday – she says hello to you – she worked with every bit of information.

All of this is in my books

In the human male, the urethra is about 8 inches (20 cm) long and opens at the end of the external urethral meatus.{{[4]}} The urethra provides an exit for urine as well as semen during ejaculation.[1]

The urethra is divided into four parts in men, named after the location:

Region Description Epithelium

pre-prostatic urethra This is the intramural part of the urethra and varies between 0.5 and 1.5 cm in length depending on the fullness of the bladder. Transitional

prostatic urethra Crosses through the prostate gland. There are several openings: (1) the ejaculatory duct receives sperm from the vas deferens and ejaculate fluid from the seminal vesicle, (2) several prostatic ducts where fluid from the prostate enters and contributes to the ejaculate, (3) the prostatic utricle, which is merely an indentation. These openings are collectively called the verumontanum. Transitional

membranous urethra A small (1 or 2 cm) portion passing through the external urethral sphincter. This is the narrowest part of the urethra. It is located in the deep perineal pouch. The bulbourethral glands (Cowper's gland) are found posterior to this region but open in the spongy urethra. Pseudostratified columnar

spongy urethra (or penile urethra) Runs along the length of the penis on its ventral (underneath) surface. It is about 15–16 cm in length, and travels through the corpus spongiosum. The ducts from the urethral gland (gland of Littre) enter here. The openings of the bulbourethral glands are also found here.[5] Some textbooks will subdivide the spongy urethra into two parts, the bulbous and pendulous urethra. The urethral lumen runs effectively parallel to the penis, except at the narrowest point, the external urethral meatus, where it is vertical. This produces a spiral stream of urine and has the effect of cleaning the external urethral meatus. The lack of an equivalent mechanism in the female urethra partly explains why urinary tract infections occur so much more frequently in females. Pseudostratified columnar – proximally, Stratified squamous – distally


These primitive mammals produce a shelled egg like their reptilian ancestors. Only four species exist today: three species of spiny anteater (echidna) and the duckbill platypus. [More]

The embryos of reptiles, birds, and mammals produce 4 extraembryonic membranes, the


yolk sac

chorion, and


In birds and most reptiles, the embryo with its extraembryonic membranes develops within a shelled egg.

The amnion protects the embryo in a sac filled with amniotic fluid.

The yolk sac contains yolk — the sole source of food until hatching. Yolk is a mixture of proteins and lipoproteins.

The chorion lines the inner surface of the shell (which is permeable to gases) and participates in the exchange of O2 and CO2 between the embryo and the outside air.

The allantois stores metabolic wastes (chiefly uric acid) of the embryo and, as it grows larger, also participates in gas exchange.

With these four membranes, the developing embryo is able to carry on essential metabolism while sealed within the egg. Surrounded by amniotic fluid, the embryo is kept as moist as a fish embryo in a pond.


Illustration of the four different types of glial cells found in the central nervous system: ependymal cells (light pink), astrocytes (green), microglial cells (dark red), and oligodendrocytes (light blue).


Peters A (May 2004). "A fourth type of neuroglial cell in the adult central nervous system". Journal of Neurocytology. 33 (3): 345–57. doi:10.1023/B:NEUR.0000044195.64009.27. PMID 15475689.

Ependyma is one of the four types of neuroglia in the central nervous system (CNS). It is involved in the production of cerebrospinal fluid (CSF), and is shown to serve as a reservoir for neuroregeneration.

Malaria is a parasitic infection caused by the 4 species of Plasmodium that infect humans: vivax, ovale, malariae, and falciparum. Of these, Plasmodium falciparum is the most deadly.

Pregnant women have an increased susceptibility to malaria infection. Malarial infection of the placenta by sequestration of the infected red blood cells leading to low birth weight and other effects. There are four types of malaria caused by the protozoan parasite Plasmodium falciparum (main), Plasmodium vivax, Plasmodium ovale, Plasmodium malariae). This condition is common in regions where malaria is endemic with women carrying their first pregnancy (primigravida).



The "zone" classification is more often used in pathology. The idea of "zones" was first proposed by John E. McNeal in 1968. McNeal found that the relatively homogeneous cut surface of an adult prostate in no way resembled "lobes" and thus led to the description of "zones".[12]

The prostate gland has four distinct glandular regions, two of which arise from different segments of the prostatic urethra:

Name Fraction of gland Description

Peripheral zone (PZ) Up to 70% in young men The sub-capsular portion of the posterior aspect of the prostate gland that surrounds the distal urethra. It is from this portion of the gland that ~70–80% of prostatic cancers originate.[13][14]

Central zone (CZ) Approximately 25% normally This zone surrounds the ejaculatory ducts. The central zone accounts for roughly 2.5% of prostate cancers although these cancers tend to be more aggressive and more likely to invade the seminal vesicles.[15]

Transition zone (TZ) 5% at puberty ~10–20% of prostate cancers originate in this zone. The transition zone surrounds the proximal urethra and is the region of the prostate gland that grows throughout life and is responsible for the disease of benign prostatic enlargement. (2)[13][14]

Anterior fibro-muscular zone (or stroma) Approximately 5% This zone is usually devoid of glandular components, and composed only, as its name suggests, of muscle and fibrous tissue.

The "lobe" classification is more often used in anatomy. There are four lobes

Anterior lobe (or isthmus) roughly corresponds to part of transitional zone

Posterior lobe roughly corresponds to peripheral zone

Lateral lobes spans all zones

Median lobe (or middle lobe) roughly corresponds to part of central zone

Zones of the Pulp

The pulp cavity exhibits four zones as you progress from the dentin-pulp junction toward the center of the pulp cavity: 1) the odontoblast zone, 2) cell-free zone (basal layer of Weil), 3) cell-rich zone, and 4) the pulp core. A cell-free zone is not present in developing teeth but becomes prominent in the coronal pulp after development. The cell-rich zone lies immediately under the cell-free zone and contains numerous fibroblasts, macro-phages and capillaries. The capillaries arise from arterioles (C) deeper in the pulp but are commonly found adjacent to, or even within, the odontoblast layer. A large nerve bundle (B) is evident in this image forming part of the subondontoblastic plexus (of Raschkow). Nerve fibers pass from the plexus out toward the dentin. Occasionally a nerve fiber extends a short distance into the dentinal tubule with the odontoblast process. Pain is the only sensation carried from the pulp to the conscious level.

Oceanic Zones

There are four major oceanic zones where plants and animals live in the ocean. The four major zones are intertidal zone, neritic zone, open ocean zone and benthic zone. These zones contain the largest ecosystem on Earth.

Abundant life is found on the summit of a seamount near Guam, NOAA

Major zones in the oceans

Intertidal zone

The intertidal zone is the area of the seafloor between high tide and low tide. It bridges the gap between land and water. Tide pools, estuaries, mangrove swamps and rocky coastal areas are all part of the intertidal zone.

Neritic zone

The water above the continental shelf is the neritic zone. Underwater forest of kelp and grassy meadows of sea grass are home to tiny fish, green turtles, sea cows, seahorses and tiny shrimp. Coral reefs have thousands of animals and plants that live in the waters of the neritic zone.

Open ocean zone

The open ocean zone lies beyond the continental slope and contains 65% of the water in the oceans. This zone is divided further into three subzones. The sunlit zone is where photosynthesis takes place. Plankton and jellyfish are drifters that inhabit this zone. Most animals living in the open ocean live in the sunlit zone.

Twilight zone

Below the sunlit zone is the twilight zone where some light penetrates the ocean to a depth of 3000 feet. Viper fish, firefly squid, and the chambered nautilus live in this zone. The midnight zone extends from a depth of 3000 feet to the seafloor. Animals found in this zone include the giant squid, deep sea hatchetfish and bioluminescent jellyfish.

Benthic zone

The benthic zone includes the entire seafloor. About 200,000 species of plants and animals live here. They live on the continental shelf and continental slope. Hydrothermal vents discovered in 1977 are also teeming with life. These plants and animals doe not need sunlight to exist.


Four areas of the young root traditionally are recognized, but except for the terminal area, are not distinctly separate. Their descriptive names are only partially correct in describing the activities taking place in each area. These regions, starting at the tip and moving upwards towards the stem, are the root cap, zone of active cell division, zone of cell elongation, and zone of maturation.

The first two are compacted in the first centimeter or less of the axis with the latter two no more than 4–5 centimeters from the tip. Only the root cap and the cell division regions actually move through the soil. After cells start to elongate and mature, no further extension takes place, and the root is stationary for the rest of its life.

Root cap

The root cap is a cup-shaped, loosely cemented mass of parenchyma cells that covers the tip of the root. As cells are lost among the soil particles, new ones are added from the meristem behind the cap. The cap is a unique feature of roots; the tip of the stem has no such structure. From its shape, structure, and location, its primary function seems clear: It protects the cells under it from abrasion and assists the root in penetrating the soil. Phenomenal numbers of cap cells are produced to replace those worn off and lost as root tips push through the soil.

The movement is assisted by a slimy substance, mucigel, which is produced by cells of the root cap and epidermis. The mucigel

Lubricates the roots.

Contains materials that are inhibitory to roots of other species.

Influences ion uptake.

Attracts beneficial soil microorganisms.

Glues soil particles to the roots thereby improving the soil-plant contact and facilitating water movement from the soil into the plant.

Protects the root cells from drying out.

Root cap cells sense light in some as yet unexplained way and direct root growth away from light. The root cap also senses gravity to which roots respond by growing downward, bringing them into contact with the soil, the reservoir of nutrients and water used by plants. The root cap also responds to pressures exerted by the soil particles.

Zone of cell division

An apical meristem lies under and behind the root cap and, like the stem apical meristem, it produces the cells that give rise to the primary body of the plant. Unlike the stem meristem, it is not at the very tip of the root; it lies behind the root cap. Between the area of active division and the cap is an area where cells divide more slowly, the quiescent center. Most cell divisions occur along the edges of this center and give rise to columns of cells arranged parallel to the root axis. The parenchyma cells of the meristem are small, cuboidal, with dense protoplasts devoid of vacuoles and with relatively large nuclei.

The apical meristem of the root organizes to form the three primary meristems:protoderm, which gives rise to the epidermis; procambium, which produces xylem and phloem; and the ground meri-stem, which produces the cortex. Pith, present in most stems and produced from the ground meristem, is absent in most dicot (eudicot) roots, but is found in many monocot roots.

Zone of cell elongation

The cells in this zone stretch and lengthen as small vacuoles within the cytoplasm coalesce and fill with water. One or two large vacuoles occupy almost all of the cell volume in fully elongated cells. Cellular expansion in this zone is responsible for pushing the root cap and apical tip forward through the soil.

Zone of maturation

The elongating cells complete their differentiation into the tissues of the primary body in this zone. It is easily recognized because of the numerous root hairs that extend into the soil as outgrowths of single epidermal cells. They greatly increase the absorptive surface of roots during the growth period when large amounts of water and nutrients are needed. An individual root hair lives for only a day or two, but new ones form constantly nearer the tip as old ones die in the upper part of the zone.

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Pine Tree Cross

Pine shootPine Tree Cross

Pine trees are grown for timber, wood pulp and also for use as Christmas Trees. But long before Christmas, by a curious quirk of nature, tiny crosses sprout from pine trees (in the northern hemisphere) just a couple of weeks before Easter.

How do these trees know it's Easter? Do they know that Christmas Trees are pagan, and display their little crosses at Easter to somehow compensate for that?

There are many different styles of cross; the ones on this photo are Bent Crosses, the style favoured by the pope. How on earth do these pine trees know all these things?

Well, they know because trees are remarkably clever. For example, they know that the taller they grow, the more sunlight they will get. At the same time, they know if they grow too tall, they won't be able to suck up sufficient moisture from the ground for survival.

They know that as soon as the male cones have shed their pollen, they are redundant and dumped onto the forest floor. They know that the female cones need to hang around a couple of years longer to mature after pollination.


Some varieties of pine know when to open their cones to release the seeds to the wind, and others attract birds to take and disperse the seeds. Yet other species hang on to their seeds for as many years as it takes before lightning strikes the forest and starts a fire. The heat opens the cones and the seeds fall to the burnt ground to start the life cycle all over again.

That's what trees do. They grow, and they generate seeds to perpetuate their species. It's called 'life' and the shoots that appear in spring, some of which happen to have a couple of perpendicular lateral shoots that make them look like crosses, are just part of that natural life cycle.

While Easter might be the same date in different parts of the world, spring isn't. So new shoot growth in north Africa appears several weeks before the same is seen in Norway. And in the southern hemisphere, Easter is in autumn.

Pine trees 'know' how to grow and there's plenty of evidence that pine trees are as intelligent as any other tree. However, there is no evidence to suggest that pine trees have any knowledge of human customs. Neither is there any mention in non-pagan sacred texts to suggest that trees have a soul.

Conversely, humans do have a soul but unfortunately we're not too sure how to grow. Fortunately, however, there are lessons in the sacred texts that can teach us.

Pine tree shoots do not appear as crosses by accident. They are there to remind us of the love shown by Jesus on the cross. See the meaning of the Cross.…
But Does the Flower Really Look Like a Maltese Cross?
The Lychnis chalcedonica plants encountered most commonly in North America at present (apparently, this wasn't always the case) bear mainly flowers with five petals. But as any Maltese cross graphic will reveal, the Maltese cross symbol has four parts: namely, four "arrowheads" that intersect at their narrowest points. So if you, yourself own one of these plants sporting the five-petal look, you may start to wonder if the name "Maltese cross" is not perhaps a misnomer. The more you look at one of the five-petaled Maltese cross flowers, the more the discrepancy will bother you.
One can speculate that gardeners over the centuries have grown two versions of what we now know as "Maltese cross." Folks used to distinguish between the two. But, as time passed, the two came to be lumped together. One version, which has four petals, was first to claim the name "Maltese cross." The other, with five petals, may once have been called "Scarlet Lightning." So the latter now shares the name "Maltese cross" with the original perennials of that name, even though they are not, technically, cross-shaped (and to confuse matters further, the name "Scarlet Lighting" now doubles as an alternative common name for all Lychnis chalcedonica plants). Perhaps cross-breeding over the years reached a point where it was no longer deemed necessary to draw a distinction between the two.
The plant with the four-petaled flowers can best lay claim to the name "Maltese cross," because of the cross shape of its blooms. At least the five-petaled type does also display, at the tips of its petals, the signature indented Vs made famous by Maltese cross graphics.
There is still hope of witnessing a perfect Maltese cross even if you grow the five-petaled type. A stray four-petaled flower does crop up occasionally in a red sea of otherwise five-petaled blooms. When that happens, you will be as delighted as if you had just discovered a four-leaf clover.


A tree is a tall plant with a trunk and branches made of wood. Trees can live for many years. The oldest tree ever discovered is approximately 5,000 years old. The four main parts of a tree are the roots, the trunk, the branches, and the leaves.


This is in one of my books

The zones of the lung divide the lung into four vertical regions, based upon the relationship between the pressure in the alveoli (PA), in the arteries (Pa), in the veins (Pv) and the pulmonary interstitial pressure (Pi) :

Zone 1: PA > Pa > Pv

Zone 2: Pa > PA > Pv

Zone 3: Pa > Pv > PA

Zone 4: Pa > Pi > Pv > PA

This concept is generally attributed to an article by West et al. in 1964,[1] but was actually proposed two years earlier by Permutt et al.[2] In this article, Permutt suggests "The pressure in the pulmonary arteries and veins is less at the top than at the bottom of the lung. It is quite likely that there is a portion of the lung toward the top in an upright subject in which the pressure in the pulmonary arteries is less than alveolar pressure."

The concept is as follows: Alveolar pressure (PA) at end expiration is equal to atmospheric pressure (0 cm H20 differential pressure, at zero flow), plus or minus 2 cm H2O (1.5 mmHg) throughout the lung. On the other hand, gravity causes a gradient in blood pressure between the top and bottom of the lung of 20 mmHg in the erect position (roughly half of that in the supine position). Overall, mean pulmonary venous pressure is ~5 mmHg. Local venous pressure falls to -5 at the apexes and rises to +15 mmHg at the bases, again for the erect lung. Pulmonary blood pressure is typically in the range 25 - 10 mmHg with a mean pressure of 15 mmHg. Regional arterial blood pressure is typically in the range 5 mmHg near the apex of the lung to 25 mmHg at the base.

Zone 1 is not observed in the normal healthy human lung. In normal health pulmonary arterial (Pa) pressure exceeds alveolar pressure (PA) in all parts of the lung. It is generally only observed when a person is ventilated with positive pressure or hemorrhage. In these circumstances, blood vessels can become completely collapsed by alveolar pressure (PA) and blood does not flow through these regions. They become alveolar dead space

Zone 2 is the part of the lungs about 3 cm above the heart. In this region blood flows in pulses. At first there is no flow because of obstruction at the venous end of the capillary bed. Pressure from the arterial side builds up until it exceeds alveolar pressure and flow resumes. This dissipates the capillary pressure and returns to the start of the cycle. Flow here is sometimes compared to a starling resistor or waterfall effect.

Zone 3 comprises the majority of the lungs in health. There is no external resistance to blood flow and blood flow is continuous throughout the cardiac cycle. Flow is determined by the Ppa-Ppv difference (Ppa - Ppv), which is constant down this portion of the lung. However, transmural pressure across the wall of the blood vessels increases down this zone due to gravity. consequently the vessels wall are more stretched so the caliber of the vessels increases causing an increase in flow due to lower resistance.

Zone 4 can be seen at the lung bases at low lung volumes or in Pulmonary oedema. Pulmonary interstitial pressure (Pi) rises as lung volume decreases due to reduced radial tethering of the lung Parenchyma Pi is highest at the base of the lung due to the weight of the above lung tissue. Pi can also rise due to an increased volume of 'leaked' fluid fluid from the pulmonary vasculature aka Pulmonary oedema . An increase in Pi causes extralveolar blood vessels to reduce in caliber and so blood flow decreases. Extralveolar blood vessels are those blood vessels outside alveoli. Intralveolar Blood vessels aka Pulmonary capillaries are considered to be the thin walled vessels adjacent to alveoli which are subject to the pressure changes described by zones 1-3. Flow in zone 4 is governed by the arteriointerstitial pressure difference (Pa − Pi). This is because as Pi rises further the arterial caliber is further reduced and so resistance to flow rises, the Pa/Pv difference remains absolute since Pi is applied over both vessels.

The Ventilation/perfusion ratio is higher in zone #1 (the apex of lung) when a person is standing than it is in zone #3 (the Base of lung) because perfusion is nearly absent. However, ventilation and perfusion are highest in base of the lung, resulting in a comparatively lower V/Q ratio.

The divisions of the human spine are based on the quadrant model pattern. Biologists say that the human structure is based on random evolutionary processes. Humans may indeed be products of random evolution, but perceptions are not always to be trusted. An alternate interpretation is that humans have evolved to reveal the Quadrant Model of Reality—humans are made in the image and likeness of God. Existence may indeed express the quadrant model pattern through the form of the human. The quadrant model pattern is the expression of Being; it is the way existence manifests. God is Being.
The spine is divided as follows:
*Square one: the cervical
*Square two: the thoracic is the structure, and holds the ribs--the second square is always structure, order, and foundation
*Square three: lumbar. The third square is solid, physical, and associated with
movement; it is extremely robust and mobile.
*Square four: sacral. The fourth section of the spine is called the sacral, connoting a transcendent quality associated with the sacred or divine. It points to the fifth, which is associated with God. The qualities of the fourth always indicate the qualities of the fifth. The fifth is ultra transcendent, being very different from the other three parts of the spine. The discs in the sacrum are fused, whereas the discs in the previous three are not.
*Square five: cocygeal. known as the tailbone, and known as vestigial. Evolutionary biologists think that it is left over from the time when human ancestors had tails. The fourth never seems to belong, while the fifth always seems unneeded and is questionable. The fourth indicates the qualities of the fifth, both having fused discs.'

Most scientsists say there are four divisions leaving the cocygeal out

The human brain is arranged in accord with the quadrant model pattern. Earlier the suggestion was made that in the quadrant model pattern the first square is the light, the second is the word, the third is the flesh, the fourth is the true word and the fifth is true light. Another way to verbalize this is in the terminology used by Wilbur. He calls the first square “mind”, second “culture”, third “body”, and the fourth “social/society”. The fifth may be “God”.
The lobes of the brain are divided into four parts.
*Square one: occipital lobe--this is the light. The occipital lobe is responsible for vision, and corresponds to the Idealist square.
*Square two: temporal lobe- this is the word. The temporal lobe is responsible for hearing. Hearing or listening brings to mind culture. Listening is a social act that people do. This is the guardian square. Guardians are the most into friends and maintaining cultural harmony. Guardians are hearers. A fascinating thing about the temporal lobe is that this is where the fusiform facial area of the brain is. This area of the brain is responsible for distinguishing faces. Again, the second square is social. Recognizing face s is social. Guardians are very into social relationships. Also the temporal lobe is where the area of the brain associated with religiosity is located. The second square is the religious square. The second quadrant is belief, faith, behavior, and belonging. Religion maintains order and homeostasis. Guardians are very religious in their mentalities in that they often do not question things extremely deeply, but they are driven more by faith. The temporal lobe is where wernickes area of the brain is. This area is responsible for understanding language/hearing. This is the listening area of the brain. The temporal lobe is described as being the section of the brain associated with religiosity and relationships. This is the nature of the second square.
*Square three: parietal lobe--this is the flesh. The parietal lobe is associated with the sense of touch and movement. The parietal lobe is responsible for movement of the body. Recall that the third square is Wilber's body square. This is the artisan square. Artisans are the doers.
*Square four: frontal lobe--this is the true word--Wilbur's social/society square. It is associated with the personality type of the Rational. The fourth quadrant is contemplation and knowledge; the frontal lobe is where abstract reasoning occurs. The frontal lobe is also where brocas area is located. Brocas area is not responsible for hearing speech; it occurs in
the temporal lobe in the wernickes area. Brocas area is responsible for speaking. The fourth square is philosophy. The second square is religion. The philosopher speaks; the religious person listens and obeys. Both are needed and need each other. The qualities of each square are fulfilled.

Paranasal sinuses are a group of four paired air-filled spaces that surround the nasal cavity.[1] The maxillary sinuses are located under the eyes; the frontal sinuses are above the eyes; the ethmoidal sinuses are between the eyes and the sphenoidal sinuses are behind the eyes. The sinuses are named for the facial bones in which they are located.


There are the four paranasal sinuses. They include

*Square one: maxillary sinus

*Square two: frontal sinus

*Square three: ethmoid sinus

*Square four: sphenoid sinus.

The first three sinuses are close to each other, but the fourth, the sphenoid sinus, is off by itself. This is the nature of the quadrant model--the fourth is always different from the previous three--a pattern expressed in the arrangement of the sinuses. Existence organizes itself along this pattern in areas that stand out to show that this pattern is significant and fundamental to reality.

The types of teeth fit the quadrant model pattern. Interestingly there are 16 teeth on the

top and bottom like the 16 squares of the quadrant model. The types of teeth are

*Square one: Incisors-- the first square is always the weakest

*Square two: Canines

*Square three: Premolars--the third square is always the most physical and solid. The premolars are large and grind food.

*Square four: Molars--the molars are the fourth and very different. The forth is always different.


The human teeth function to mechanically break down items of food by cutting and crushing them in preparation for swallowing and digestion. Humans have four types of teeth: incisors, canines, premolars, and molars, each with a specific function. The incisors cut the food, the canines tear the food and the molars and premolars crush the food. The roots of teeth are embedded in the maxilla (upper jaw) or the mandible (lower jaw) and are covered by gums. Teeth are made of multiple tissues of varying density and hardness.




Main article: Tooth enamel

Enamel is the hardest and most highly mineralized substance of the body. It is one of the four major tissues which make up the tooth, along with dentin, cementum, and dental pulp.[7] It is normally visible and must be supported by underlying dentin. 96% of enamel consists of mineral, with water and organic material comprising the rest.[8] The normal color of enamel varies from light yellow to grayish white. At the edges of teeth where there is no dentin underlying the enamel, the color sometimes has a slightly blue tone. Since enamel is semitranslucent, the color of dentin and any restorative dental material underneath the enamel strongly affects the appearance of a tooth. Enamel varies in thickness over the surface of the tooth and is often thickest at the cusp, up to 2.5mm, and thinnest at its border, which is seen clinically as the CEJ.[9] The wear rate of enamel, called attrition, is 8 micrometers a year from normal factors.[citation needed]


Enamel's primary mineral is hydroxyapatite, which is a crystalline calcium phosphate.[10] The large amount of minerals in enamel accounts not only for its strength but also for its brittleness.[9] Dentin, which is less mineralized and less brittle, compensates for enamel and is necessary as a support.[10] Unlike dentin and bone, enamel does not contain collagen. Proteins of note in the development of enamel are ameloblastins, amelogenins, enamelins and tuftelins. It is believed that they aid in the development of enamel by serving as framework support, among other functions.[11]



Main article: Dentin

Dentin is the substance between enamel or cementum and the pulp chamber. It is secreted by the odontoblasts of the dental pulp.[12] The formation of dentin is known as dentinogenesis. The porous, yellow-hued material is made up of 70% inorganic materials, 20% organic materials, and 10% water by weight.[13] Because it is softer than enamel, it decays more rapidly and is subject to severe cavities if not properly treated, but dentin still acts as a protective layer and supports the crown of the tooth.


Dentin is a mineralized connective tissue with an organic matrix of collagenous proteins. Dentin has microscopic channels, called dentinal tubules, which radiate outward through the dentin from the pulp cavity to the exterior cementum or enamel border.[14] The diameter of these tubules range from 2.5 μm near the pulp, to 1.2 μm in the midportion, and 900 nm near the dentino-enamel junction.[15] Although they may have tiny side-branches, the tubules do not intersect with each other. Their length is dictated by the radius of the tooth. The three dimensional configuration of the dentinal tubules is genetically determined.



Main article: Cementum

Cementum is a specialized bone like substance covering the root of a tooth.[12] It is approximately 45% inorganic material (mainly hydroxyapatite), 33% organic material (mainly collagen) and 22% water. Cementum is excreted by cementoblasts within the root of the tooth and is thickest at the root apex. Its coloration is yellowish and it is softer than dentin and enamel. The principal role of cementum is to serve as a medium by which the periodontal ligaments can attach to the tooth for stability. At the cementoenamel junction, the cementum is acellular due to its lack of cellular components, and this acellular type covers at least ⅔ of the root.[16] The more permeable form of cementum, cellular cementum, covers about ⅓ of the root apex.[17]


Dental Pulp[edit]

Main article: Pulp (tooth)

The dental pulp is the central part of the tooth filled with soft connective tissue.[13] This tissue contains blood vessels and nerves that enter the tooth from a hole at the apex of the root.[18] Along the border between the dentin and the pulp are odontoblasts, which initiate the formation of dentin.[13] Other cells in the pulp include fibroblasts, preodontoblasts, macrophages and T lymphocytes.[19] The pulp is commonly called "the nerve" of the tooth.

Excerpt from my book Quadrant Model of Reality
Human taste receptors also fit the quadrant model pattern. They include
*Square one: bitter
*Square two: sweet
*Square three: sour
*Square four: salty (salt is NaCl)
*Square five: umami is Mono sodium glutamate. Sodium is Na. The fourth always points to the fifth. The fourth contains sodium, as does the fifth. Salty is different from the previous three, and the difference in fifth transcends all.
Bitter and sweet, the first two squares, form the duality. Sour is the third square, which always implies attributes of being bad and destructive.

A mechanoreceptor is a sensory receptor that responds to mechanical pressure or distortion. Normally there are four main types in glabrous mammalian skin: lamellar corpuscles, tactile corpuscles, Merkel nerve endings, and bulbous corpuscles

There are four types of mechanoreceptors embedded in ligaments. As all these types of mechanoreceptors are myelinated, they can rapidly transmit sensory information regarding joint positions to the central nervous system.[10]


Type I: (small) Low threshold, slow adapting in both static and dynamic settings

Type II: (medium) Low threshold, rapidly adapting in dynamic settings

Type III: (large) High threshold, slowly adapting in dynamic settings

Type IV: (very small) High threshold pain receptors that communicate injury

Neurulation occurs in somewhat different ways in different regions of the body. The head, trunk, and tail each form their region of the neural tube in ways that reflect the inductive relationship of the pharyngeal endoderm, prechordal plate, and notochord to its overlying ectoderm (Chapters 10 and 11). The head and trunk regions both undergo variants of primary neurulation, and this process can be divided into four distinct but spatially and temporally overlapping stages: (1) formation of the neural plate; (2) shaping of the neural plate; (3) bending of the neural plate to form the neural groove; and (4) closure of the neural groove to form the neural tube (Smith and Schoenwolf 1997; see Figure 12.2).


The hair cells are arranged in four rows in the organ of Corti along the entire length of the cochlear coil. Three rows consist of outer hair cells (OHCs) and one row consists of inner hair cells (IHCs). The inner hair cells provide the main neural output of the cochlea. The outer hair cells, instead, mainly receive neural input from the brain, which influences their motility as part of the cochlea's mechanical pre-amplifier. The input to the OHC is from the olivary body via the medial olivocochlear bundle.


Animal tissues are grouped into four basic types: connective, muscle, nervous, and epithelial. Collections of tissues joined in structural units to serve a common function compose organs. While all animals can generally be considered to contain the four tissue types, the manifestation of these tissues can differ depending on the type of organism. For example, the origin of the cells comprising a particular tissue type may differ developmentally for different classifications of animals.


Animal tissues are grouped into four basic types: connective, muscle, nervous, and epithelial. Collections of tissues joined in structural units to serve a common function compose organs. While all animals can generally be considered to contain the four tissue types, the manifestation of these tissues can differ depending on the type of organism. For example, the origin of the cells comprising a particular tissue type may differ developmentally for different classifications of animals.

Animal tissues are grouped into four basic types: connective, muscle, nervous, and epithelial. Collections of tissues joined in structural units to serve a common function compose organs. While all animals can generally be considered to contain the four tissue types, the manifestation of these tissues can differ depending on the type of organism. For example, the origin of the cells comprising a particular tissue type may differ developmentally for different classifications of animals.

Pines have four types of leaf:

Seed leaves (cotyledons) on seedlings, born in a whorl of 4–24.

Juvenile leaves, which follow immediately on seedlings and young plants, 2–6 cm long, single, green or often blue-green, and arranged spirally on the shoot. These are produced for six months to five years, rarely longer.

Scale leaves, similar to bud scales, small, brown and non-photosynthetic, and arranged spirally like the juvenile leaves.

Needles, the adult leaves, are green (photosynthetic) and bundled in clusters called fascicles. The needles can number from one to seven per fascicle, but generally number from two to five. Each fascicle is produced from a small bud on a dwarf shoot in the axil of a scale leaf. These bud scales often remain on the fascicle as a basal sheath. The needles persist for 1.5–40 years, depending on species. If a shoot is damaged (e.g. eaten by an animal), the needle fascicles just below the damage will generate a bud which can then replace the lost leaves.

I'm a paragraph. Click here to add your own text and edit me. It's easy.

Four Classes of Biological Macromolecules


There are four major classes of biological macromolecules:





nucleic acids



Source: Boundless. “Types of Biological Macromolecules.” Boundless Biology Boundless, 26 May. 2016. Retrieved 22 Mar. 2017 from


Four motor symptoms are considered cardinal in PD: slowness of movement (bradykinesia), tremor, rigidity and postural instability.[1] Typical for PD is an initial asymmetric distribution of these symptoms, where in the course of the disease a gradual progression to bilateral symptoms develop although some asymmetry usually persists. Other motor symptoms include gait and posture disturbances such as decreased arm swing, a forward-flexed posture and the use of small steps when walking; speech and swallowing disturbances; and other symptoms such as a mask-like face expression or small handwriting are examples of the range of common motor problems that can appear.[1]


Cardinal symptoms[edit]

Four symptoms are considered cardinal in PD: bradykinesia, tremor, rigidity and postural instability also referred to as parkinsonism.[1]


Tremor is the most apparent and well-known symptom.[1] It is also the most common; though around 30% of individuals with PD do not have tremor at disease onset, most develop it as the disease progresses.[1] It is usually a rest tremor: maximal when the limb is at rest and disappearing with voluntary movement and sleep.[1] It affects to a greater extent the most distal part of the limb, and at onset typically appears in only a single arm or leg, becoming bilateral later during the course of the disease.[1] Frequency of PD tremor is between 4 and 6 hertz (cycles per second). It is a pronation-supination tremor that is described as "pill-rolling," that is the index finger of the hand tends to get into contact with the thumb and perform a circular movement together.[1][2] Such term was given due to the similarity of the movement in PD patients with the former pharmaceutical technique of manually making pills.[2] PD tremor is not improved with alcohol intake, as opposed to essential tremor.[1]

Rigidity is a characterized by an increased muscle tone (an excessive and continuous contraction of the muscles) which produces stiffness and resistance to movement in joints.[1] Rigidity may be associated with joint pain; such pain being a frequent initial manifestation of the disease.[1] When limbs of the person with PD are passively moved by others a "cogwheel rigidity" is commonly seen.[1] Cogwheel-like or ratchety jerks are characterized by the articulation moving as opposed to the normal fluid movement; when a muscle is externally tried to move it resists at first but with enough force it is partially moved until it resists again and only with further force it will be moved.[1][3][4] The combination of tremor and increased tone is considered to be at the origin of cogwheel rigidity.[5]

Bradykinesia and akinesia: the former is slowness of movement while the latter is the absence of it.[1] It is the most characteristic clinical feature of PD, and is associated with difficulties along the whole course of the movement process, from planning to initiation and finally execution of a movement.[1] The performance of sequential and simultaneous movements is also hindered.[1] Bradykinesia is the most disabling symptom in the early stages of the disease.[3] Initial manifestations of bradykinesia are problems when performing daily life tasks requiring fine motor control such as writing, sewing or getting dressed.[1] Clinical evaluation is based in similar tasks consisting such as alternating movements between both hands or feet.[3] Bradykinesia is not equal for all movements or times. It is modified by the activity or emotional state of the subject to the point of some patients barely able to walk being capable of riding a bicycle.[1] Generally patients have less difficulties when some sort of external cue is provided.[1][6]

... immobile patients who become excited may be able to make quick movements such as catching a ball (or may be able to suddenly run if someone screams "fire"). This phenomenon (kinesia paradoxica) suggests that patients with PD have intact motor programmes but have difficulties accessing them without an external trigger, such as a loud noise, marching music or a visual cue requiring them to step over an obstacle.[1]


Postural instability: In the late stages postural instability is typical, which leads to impaired balance and frequent falls, and secondarily to bone fractures.[1] Instability is often absent in the initial stages, especially in younger people.[3] Up to 40% of the patients may experience falls and around 10% may have falls weekly, with number of falls being related to the severity of PD. It is produced by a failure of postural reflexes, along other disease related factors such as orthostatic hypotension or cognitive and sensory changes[1]



Tetrad Analysis in Higher Plants. A Budding Technology

Gregory P. Copenhaver * , Kevin C. Keith and Daphne Preuss

+ Author Affiliations

1 Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, Illinois 60637

doi: http:/​/​dx.​doi.​org/​10.​1104/​pp.​124.​1.​7

Plant Physiology September 1, 2000 vol. 124 no. 1 7-16

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Tetrad analysis, the ability to manipulate and individually study the four products of a single meiotic event, has been critical to understanding the mechanisms of heredity. The Arabidopsis quartet (qrt) mutation, which causes the four products of male meiosis to remain attached, enables plant biologists to apply this powerful tool to investigations of gamete development, cell division, chromosome dynamics, and recombination. Here we highlight several examples of how qrt has been used to perform tetrad analysis and suggest additional applications including a genetic screen for gametophytic mutants and methods for investigating gene interactions by synthetic lethal analysis.

In 1883 Van Beneden made an amazing observation: In newly fertilized Ascaris megalocephala eggs, the sperm and the egg nuclei each contained two chromosomes whereas the somatic cells contained four. Building on this observation, Weismann (1887) proposed that there must be a reductive cell division during the sexual life cycle to compensate for the fusion of gametes at fertilization. Farmer and Moore (1905)coined the term meiosis to describe this division. The cellular processes surrounding meiosis and the rules governing genetic inheritance have been the subjects of intense scientific scrutiny in the century since these early observations. During meiosis the cell reorganizes cytoplasmic components, initiates transcriptional programs, and activates specialized biosynthetic pathways. Equally dramatic events impact the genome: Each DNA strand is replicated, chromosomal homologs pair and recombine, and two cell divisions are executed to produce four haploid cells. Geneticists have employed several techniques to unravel the mechanisms of meiosis. Chief among these techniques is tetrad analysis, a method for investigating genetic mechanisms based upon the analysis of all four products of meiosis.

Tetrad analysis is particularly useful for examining meiotic recombination, and it has the flexibility to provide insight into many aspects of inheritance. Tetrad analysis can be used to detect chromosomal translocations, prove synthetic lethality in double mutants, and distinguish nuclear from organellar segregation. Similar to other methods for measuring recombination frequencies, tetrad analysis establishes linkage relationships that enable the construction of genetic maps (Mather and Beale, 1942). The most remarkable aspects of tetrad analysis are that it uniquely allows monitoring of every genetic exchange in an individual meiosis, unequivocal detection of gene conversion events, establishment of chromatid interference, and high precision genetic mapping of centromeres (Whitehouse, 1942; Mitchell, 1955; Fogel and Hurst, 1967). Because tetrad analysis requires the recovery of all four products of a meiosis, the analysis of complete tetrads has been historically restricted to fungal organisms and single-cell algae (Pascher, 1918). In contrast, the four meiotic products of higher eukaryotes either separate (male meiosis) or undergo selective cell death (female meiosis). The discovery of the quartet(qrt) mutant of Arabidopsis, a mutation that causes pollen grains to remain attached after cytokinesis (Fig.1), allowed the extension of tetrad analysis to a multicellular genetic model system (Preuss et al., 1994). While an understanding of the theory and practice of tetrad analysis is essential for anyone exploring genetic mechanisms, these techniques can be extended into many other areas, including development and cell biology. Here we describe the use of tetrad analysis in a higher plant, review recent examples from the literature, and suggest additional opportunities.

Fig. 1.

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Fig. 1.

Arabidopsis pollen development. The diploid pollen mother cell undergoes a round of DNA replication resulting in a meiocyte in which n = 4. During meiosis I, first division segregation (FDS) separates homologous chromosome pairs generating two cells in which n = 2. During meiosis II, second division segregation (SDS) separates sister chromatids and gives rise to four haploid cells. In Arabidopsis, pectin components in the exine wall of the pollen grains are degraded resulting in separation of the pollen tetrad. In qrt mutants, failure to degrade the pectin components leaves the pollen tetrad intact.

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The four meiotic products produced by qrt mutants, like those of Saccharomyces cerevisiae, are unordered, forming symmetrical tetrads with a geometry that does not reflect spindle orientation or the order of chromosome assortment. Marker pairs in these unordered tetrads assort in three possible patterns (Fig.2). In parental ditype (PD) tetrads, each meiotic product contains the same pair of alleles as one or the other parent. In non-parental ditype (NPD) tetrads, each meiotic product is recombinant, with novel allelic combinations. In tetratype tetrads (TT), each of the four meiotic products has a different genotype: two parental and two recombinant. These patterns of allelic segregation reveal the linkage relationships between genetic loci, including centromeres.

Fig. 2.

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Fig. 2.

Segregation analysis in tetrads. A, Two pairs of chromosomes are diagrammed progressing through meiosis. Each chromosome pair is composed of four chromatids; two from each parent (green and yellow, respectively). Upon completion of meiosis each member of the tetrad (i–iv) inherits one chromatid. The segregation of markers (X–Z) with different alleles (upper and lowercase) depends on the alignment of chromosomes at meiosis I and the distribution of recombination events (dashed lines). B, Scoring marker pairs in each tetrad member reveals three possible segregation patterns: parental ditype (PD), non-parental ditype (NPD), or tetratype (TT). Recombination can result in TT patterns. With markers on different chromosomes (Z and Y), crossovers between one of the markers and its centromere yields a TT; similarly, with linked markers (X and Y), a single crossover between them results in TT (not shown). C, Assigning each parental allele a “1” or a “0” value allows PD, NPD, and TT tetrad patterns to be converted to numerical data (2, 0, and 1, respectively).

When two loci are linked, PD tetrads are more abundant than NPD tetrads; if all of the tetrads are PD, the loci are completely linked. Single crossover events between linked loci yield TT tetrads, whereas double crossover events yield PD, TT, or NPD tetrads depending on the number of chromatids involved. The frequencies of each of these classes of tetrads can be used to calculate distances between linked markers with the equation: centiMorgans (cM) = [(1/2TT + 3NPD) ÷ total no. of tetrads] × 100.

Unlinked loci alternatively yield an equal number of PD and NPD tetrads; in such cases, the percentage of TT tetrads can be used to calculate the linkage of each locus to its centromere. During meiosis I, homologous chromosomes are drawn to opposite poles via their connection to the spindle apparatus at the centromere. Thus centromeres and centromere-linked genetic markers always segregate to opposite poles; pairs of centromere-linked markers that reside on different chromosomes yield only PD and NPD patterns. In contrast, recombination frequently separates distal markers from their centromeres, yielding a TT pattern when compared to centromere-linked markers (Fig. 2). The distance between these markers and their centromeres is determined by the equation: cM = (1/2TT) ÷ total no. of tetrads.

Similar calculations can be made using half-tetrad analysis, a special case of tetrad analysis that is possible when only two of the four meiotic products can be analyzed. This method has been used in several plant and animal species, including fruitflies (Drosophila melanogaster), zebra fish (Danio rerio), humans, alfalfa (Medicago sativa), potatoes (Solanum tuberosum), and corn (Zea mays) (Anderson, 1925;Rhoades and Dempsey, 1966; Mendiburu and Peloquin, 1979; Johnson et al., 1995; Tavoletti, 1996). Although half-tetrads can be used to map centromeres, they are less helpful when analyzing genetic events that require knowledge of all four meiotic products (such as gene conversion or chromatid interference).

The genetic segregation data that result from tetrad analysis often require repetitive calculations that can easily be accommodated with a computer spreadsheet program. Each marker allele can be represented by a “1” or “0,” making it possible to calculate PD, NPD, and TT frequencies quickly for any pair of markers (Fig. 2C). The frequencies of these classes can then be used with the mapping functions described above to determine genetic map distances. It is important to note that the frequency of TT tetrads for unlinked marker pairs can be used to calculate centromere positions.

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Since the discovery of the Arabidopsis qrt mutation, tetrad analysis has become an efficient tool for plant biologists. Lesions in either the QRT1 or QRT2 genes of Arabidopsis lead to defects in pectin degradation following male meiosis, preventing the normal separation of developing pollen grains from one another (Rhee and Somerville, 1998). This absence of normal separation results in fusion of the pollen exine walls, but leaves qrt pollen viable and fertile in every other respect (Preuss et al., 1994; Copenhaver et al., 1998). Because the fusion ofqrt pollen grains does not involve the inner intine wall, there is no mixing of cytoplasmic or nuclear components between the meiotic products. Although many other plants possess the capacity to package their meiotic products into pollen tetrads, including water lilies (Nymphaea), cattails (Typhaceae), heath (Ericaceae and Epacridceae), evening primroses (Onagraceae), sundews (Droseraceae), orchids (Orchidaceae), acacias (Mimosaceae), Dysoxylumspp. (Meliaceae), and petunias (Solanaceae) (Levan, 1942; Large and Mabberley, 1994; Preuss et al., 1994; Smyth, 1994), these organisms do not yet have the extensive genetic resources of Arabidopsis.

To determine the genotype of each member of a pollen tetrad, one could perform PCR analysis on individual grains (Matsunaga et al., 1999), a procedure that would require separation of the pollen, disruption of the exine layer, and efficient DNA amplification. The inherent technical difficulties, however, coupled with the limited number of loci that could be analyzed in each grain, make it preferable instead to obtain pollen tetrads that are segregating alleles of interest and to cross them to appropriate females and analyze the resulting progeny. For example, crossing two qrt plants from different ecotypes yields an F1 plant that is heterozygous for multiple polymorphisms (Fig. 3). These polymorphic markers segregate in the expected 2:2 ratio in the pollen tetrads produced by the F1 plant (Copenhaver et al., 1998). Pollen is collected from mature anthers by tapping them on a glass slide. A hair is attached to the end of a small wooden dowel and is subsequently used to lift a single pollen tetrad onto a stigma of an appropriate female. To avoid contamination from self-pollination, it is convenient to use stigmas from a male-sterile strain, such as ms1 (van der Veen and Wirtz, 1967). Crosses with individual pollen tetrads yield three or four seeds approximately 40% of the time. The tissue produced by these progeny yields sufficient DNA for thousands of PCR reactions, and their seeds provide a permanent resource for genetic analysis. The segregation of any type of genetic marker can be followed in the four progeny plants. Codominant PCR-based molecular markers such as simple sequence length polymorphisms, cleaved-amplified polymorphic sequences, and single nucleotide polymorphisms SNPs are reliable, easy to score even in large numbers, and require only a small amount of purified DNA (Konieczny and Ausubel, 1993; Bell and Ecker, 1994; Cho et al., 1999). RFLPs can also be used, but these markers require larger DNA preparations. Morphological markers have the advantage of rapid analysis if multiply marked parental lines are used to create the F1.

Fig. 3.

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Fig. 3.

Performing tetrad crosses in plants. Twoqrt parental strains (A and B) are crossed to produce aqrt F1 plant that is heterozygous for all the polymorphisms between the two parents. Individual pollen tetrads from the F1 plant are placed onto the stigmas of a receptor plant of known genotype (B). Each pollen grain in the tetrad fertilizes a different ovule resulting in four tetrad progeny.

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In addition to investigating the mechanisms of meiosis and recombination, tetrad analysis can also be used to identify key genes required for pollen development. Moreover, the ability to monitor the expression of genes within pollen grains provides practical tools that could enhance the efficiency of plant genetic screens. Below, we summarize recent studies that employed qrt for tetrad analysis and suggest future applications for this technology.

Analyzing Genes Required for Pollen Development

Although some gene products contained within pollen grains are derived from the sporophytic (diploid) parent, including the pre-meiotic pollen mother cell and the surrounding tapetal tissues, a large fraction of the pollen contents are expressed during the gametophytic (haploid) phase that follows meiosis. In some species, as many as 60% of the genes expressed during vegetative development are also expressed in haploid pollen, and approximately 10% of all genes in these species are pollen specific (Stinson et al., 1987). Theqrt mutation tremendously facilitates investigation of these haploid-specific genes. In heterozygotes, gametophytic mutant phenotypes segregate 2:2 in pollen tetrads; in contrast, genes under sporophytic control segregate in a 4:0 or 0:4 pattern for dominant or recessive mutations, respectively.

Tetrad analysis was used to prove the gametophytic function of two genes required for normal cell division in Arabidopsis pollen development: SIDECAR POLLEN (SCP) andGEMINI POLLEN1 (GEM1) (Chen and McCormick, 1996;Park et al., 1998). In the Nossen-0 and Columbia-0 ecotypes the scp mutation causes a mixture of wild-type, aborted, and extra-cell pollen, but in the Landsberg erecta ecotype it causes pollen lethality. By crossing scp to qrt, Chen and McCormick generated +/scp;qrt/qrt plants in a Nossen-0/Landsbergerecta mixed background. These plants produced pollen tetrads with two wild-type grains and two aborted grains, indicating that scp was acting as a gametophytic pollen lethal (Fig. 4). A similar strategy was used to examine gem1 mutants that produce twin-cell pollen grains due to an extra mitotic division during pollen development. Pollen produced by +/gem1; qrt/qrtplants never contained more than two aberrant grains but often contained fewer, indicating that gem1 is an incompletely penetrant gametophytic mutation. The qrt mutant was further utilized to examine the geometry of the extra mitotic divisions in gem1 pollen; in the aberrant pollen grains, these divisions were aligned on the normal division axis.

Fig. 4.

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Fig. 4.

Gametophytic segregation. Gametophytic genes are expressed in the haploid products of meiosis. Plants that are heterozygous for a male-specific gametophytic allele (g) will yield pollen grains that segregate the phenotype in a 2:2 ratio, which can be readily verified with qrt. Tetrads containing two aborted and two viable pollen grains occur with gametophytic lethal allele.

The qrt mutation can also be used to examine the uniformity of developmental events associated with individual meioses. Mutants in the Arabidopsis MEI1 gene undergo an aberrant meiosis, resulting in more than four pollen grains that vary in size and DNA content (He et al., 1996). To discern exactly how many cells are produced by individual meioses in MEI1 plants, He and Mascarenhas (1998) constructedMEI1-qrt double mutants, making it possible to isolate and count the meiotically related pollen clusters. The authors found significant variation in the number and size of cells within individual clusters and concluded that MEI1 could function in several stages of meiosis.

These studies demonstrate that qrt is useful for analyzing a variety of defects in pollen development. In fact, qrt can be used as the basis for a genetic screen designed to detect lesions in any gametophytically important gene. We have expressed a visible marker, green fluorescent protein, under the control of a pollen-specific promoter (G.P. Copenhaver, J. MacGurn, and D. Preuss, unpublished data). Following Agrobacterium tumefaciens-mediated transformation we found that insertions into gametophytic genes required for pollen development resulted in pollen tetrads with green fluorescent protein-marked, inviable pollen grains. Of 143 primary transformants surveyed, eight show a clear 2:2 aborted:viable phenotype in the pollen tetrads.

Constructing Genetic Maps

As diagrammed in Figure 2, marker assortment in tetrads can be used to construct genetic maps. With this approach, fewer recombinant individuals are required to obtain map distances, gene order can be readily defined by examining all four chromatids, and the distance at which linkage can be detected expands. We have used tetrad analysis to analyze recombination across the entire Arabidopsis genome, scoring all of the crossovers that occurred in individual meioses in Arabidopsis (Copenhaver et al., 1998). The number and distribution of crossover events in 57 meioses were measured by analyzing the segregation of 52 PCR-based markers spaced at approximately 10-cM intervals. This study revealed that the number of crossover events in each meiosis ranged from five to 13 with an average of 8.9 ± 1.8 (SD). Almost every chromosome experienced at least one crossover, suggesting that recombination is required for proper chromosome disjunction in Arabidopsis.

Crossover interference, a bias in the expected frequency of double crossovers, can also be measured with these techniques (Whitehouse, 1942). Chromosomal interference is detected when the expected frequency of double crossovers in adjacent genetic intervals differs significantly from the observed frequency of single crossovers in the individual intervals (Fig. 5A). In contrast, chromatid interference results in a non-random distribution of double crossovers on DNA strands, producing a deviation from the expected 1:2:1 ratio of two:three:four-strand double crossovers (Fig. 5B). Although chromosomal interference can be measured with other methods, chromatid interference requires knowledge of the crossover status of all four DNA strands at meiosis I and thus can be determined only with tetrad analysis. In our previous study of genomic recombination in Arabidopsis, significant chromosomal interference was observed (33 double crossovers observed versus 93 predicted), but chromatid interference was not detected on any chromosome (Copenhaver et al., 1998).

Fig. 5.

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Fig. 5.

Crossover interference. A, If crossovers are independent of one another the product of the frequencies (k) of single crossovers within adjacent intervals (k 1 and k 2) equals the frequency of double crossovers (k 3) in the combined interval (bracket). If the observed number of double crossovers within this region is less than the expected frequency then the interval is experiencing positive interference; in contrast, negative interference will yield more crossovers than expected. B, If crossovers are distributed randomly among the four chromatids (a–d), double crossovers should occur in a 1:2:1 ratio of two-strand:three-strand:four-strand events.

Detecting Gene Conversion

The physical replacement of one allele with another is known as gene conversion, an event that can result from mismatched repair of heteroduplex DNA during recombination (Mitchell, 1955; Meselson and Radding, 1975; Paques and Haber, 1999). Meiotic gene conversion events can be formally proven only with tetrad analysis; in contrast, when genetic analysis is performed with random gametes, closely spaced double crossovers are assumed to reflect gene conversion. Examination of all four chromatids, however, can discriminate between actual gene conversion events and other possibilities such as local negative interference. With tetrad analysis, an allele that undergoes gene conversion segregates in a 3:1 pattern (Fig.6), whereas flanking alleles segregate 2:2. It is surprising that in our work with Arabidopsis, we have yet to detect a gene conversion event. This observation may stem from insufficient marker density or may reflect an unexpectedly low frequency of gene conversion events.

Fig. 6.

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Fig. 6.

Detecting gene conversion in tetrads. Gene conversion occurs when genetic information is non-reciprocally transferred from one chromatid to another (orange and green bars) resulting in a non-Mendelian (3:1) segregation pattern. These events can be definitively detected with tetrad analysis because all four products of meiosis are available for inspection.

Identifying Regions That Provide Centromere Function

A number of methods have been used to map centromeres in higher eukaryotes, including plants. Chromosome breakage experiments localize centromeres by identifying chromosome fragments capable of autonomous segregation (Sears and Lee-Chen, 1970; Koornneef et al., 1983;Tyler-Smith et al., 1993; Murphy and Karpen, 1995; Sacchi et al., 1996). This method can be limited by the difficulty of obtaining desired breakpoints and by the activation of cryptic centromeres on acentric DNA fragments. Cytological methods alternatively reveal heterochromatic regions of the chromosome or localize proteins implicated in centromere function (Rattner, 1991; Sunkel and Coelho, 1995; Fransz et al., 1998). Such techniques can have limited resolution and cannot precisely identify the DNA sequences critical for centromere function. Several classes of repetitive DNA are known to colocalize with cytologically defined centromeres, but it is still unclear if these classes of DNA are required for centromere activity (Round et al., 1997).

As detailed above (Fig. 2), tetrad analysis can uniquely define the region of each chromosome that segregates to the cell pole in meiosis I. We took advantage of this property to map, with high precision, all five centromeres in Arabidopsis (Copenhaver et al., 1998, 1999). The same set of 57 tetrads used for the genome-wide scan of recombination provided an initial centromere position for each chromosome. By developing additional PCR-based markers, assembling contigs of bacteria artificial chromosome (BAC) clones, and scoring over 1,000 tetrads, we refined these initial centromere positions. This study revealed that the recombinationally suppressed centromeric regions of Arabidopsis encompass an array of repetitive elements and are flanked by regions rich in mobile DNA elements. Despite their repetitive nature, the Arabidopsis centromeres contain many genes. We are currently extending these studies by using tetrad analysis to assess the assortment of chromosome fragments, aberrant chromosomes containing two centromeres, and synthetic minichromosomes (K.C. Keith and D. Preuss, unpublished data).

Detecting Chromosome Rearrangements

Since the construction of the earliest fruitfly mapping strains, balancer chromosomes that contain translocations or inversions have been recognized as important genetic tools (Casso et al., 2000). In plants, these rearrangements can often occur inadvertently as a consequence of Agrobacterium tumefaciens-mediated plant transformation (Castle et al., 1993; Nacry et al., 1998). Tetrad analysis is a useful method for rapidly detecting and analyzing these aberrations.

A plant that is heterozygous for a balanced translocation can undergo two types of meiotic segregation: adjacent or alternate (Fig.7). In the latter case, all four meiotic products contain a balanced set of chromosomes, but in the former case, all four meiotic products have duplications and deficiencies that are usually lethal. Because the frequencies of adjacent and alternate segregation patterns are approximately equal, a qrt plant heterozygous for a translocation will yield equal numbers of tetrads containing all aborted or all wild-type pollen grains. Ray et al. (1997) took advantage of this property to confirm that they had found a desired reciprocal translocation, TL-1, caused by T-DNA mutagenesis. In their strains, qrt plants showed an aborted pollen phenotype that segregated in a 4:0 and 0:4 pattern with equal frequency. This line also produced some pollen tetrads segregating aborted pollen in 3:1, 2:2, and 1:3 patterns, suggesting that recombination events capable of restoring a balanced chromosome set were occurring. Using these strains, Ray et al. (1997) subsequently showed that, as expected, one-half of the female meioses were also aberrant and that the resulting defective female gametophytes were incapable of attracting pollen tubes.

Fig. 7.

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Fig. 7.

Chromosome segregation in translocation heterozygotes. In individuals heterozygous for a reciprocal translocation, the affected chromosomes form a tetravalent structure upon pairing. During meiosis I homologous centromeres (1–4) disjoin and migrate to the cell poles. Segregation in a tetravalent can occur in two ways: either adjacent chromosomes (1 and 3) or alternate chromosomes (1 and 4) can migrate to the same pole. In rare cases, homologous centromeres fail to disjoin and a second form of adjacent segregation (adjacent-2) can occur.

Non-Mendelian Inheritance

Whereas tetrad segregation patterns of 2:2 indicate that a particular phenotype is under the control of the nuclear genome, consistent 0:4 or 4:0 patterns suggest that the phenotype is determined by an organelle, such as the mitochondrial or chloroplast genome, or is a cytoplasmic component inherited from the precursor diploid cell. When plants with two different organelle genotypes are crossed, the resulting F1 will typically have the composition of the maternal parent, since most plants show maternal inheritance of organelles (Birky, 1978). The pollen tetrads from the F1 will consequently segregate in a 4:0 pattern, reflecting the maternal allele. A similar effect is seen in yeast; although both parent cells contribute organelles to the F1 zygote, subsequent mixing and distribution of organelles results in uniform 4:0 inheritance in the spores (Wolf et al., 1978).

During our effort to map the centromeres in Arabidopsis, the ability to distinguish between nuclear and organelle inheritance with tetrad analysis was critically important. As DNA clones were identified for sequencing on chromosome II, a BAC clone that contained nDNA fused to DNA that was highly similar to the sequence of the Arabidopsis mitochondrial genome was characterized (Unseld et al., 1997; Lin et al., 1999). The identification of a second BAC clone with a different mitochondrial-nuclear junction raised the possibility that these clones corresponded to a large insertion of mitochondrial DNA into the nuclear genome rather than chimeric constructs formed during construction of the libraries. To test whether there was indeed a large mitochondrial insertion into the chromosome, we designed PCR primers that detected polymorphisms at the junction of the nuclear and mitochrondrial DNA. Scoring these markers in the tetrads used to map the centromeres showed, in every case, a 2:2 pattern, confirming a large (270 kb) insert of the mitochondrial genome into chromosome II.

Previous Section

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The enormous number of duplicated genes within the Arabidopsis genome will require creative approaches aimed at discerning gene function. It is imperative to investigate mutations in combinations that can reveal genetic interactions, including those interactions that result in synthetic lethality. The latter is a particularly useful phenomenon that has been important for discerning the functions of numerous genes in yeast and other organisms (Huffaker et al., 1987). Two mutations are described as having a synthetically lethal phenotype when their combination results in a non-viable double mutant. Such lethality raises the possibility that the genes contribute to the same biological process. Tetrad analysis provides essential proof that the desired double mutant is indeed lethal. By analyzing only a few NPD tetrads one can conclude that the mutations are synthetically lethal if the two surviving individuals always have a wild-type genotype. In contrast, providing such proof with a randomly segregating population requires large numbers of progeny and relies on statistical analysis.

We recommend the following methods when incorporating this approach in plants. Two qrt parental strains each homozygous for a different mutation should be crossed to each other to generate an F1. In the pollen tetrads from this F1, the mutant and wild-type alleles will segregate into PD, NPD, and TT patterns. If the genes play a gametophytic role in pollen development, then synthetic lethality will result in pollen tetrads that segregate viable:aborted pollen grains in 4:0, 3:1, and 2:2 patterns. Those tetrads exhibiting a 2:2 segregation pattern should then be crossed to an appropriate female to ensure that the two surviving pollen grains contain only wild-type gametes.


Tetrad dissection is a vital tool for yeast geneticists. It is a method by which sporulating yeast cells are teased apart, and the individual cells isolated. Specially designed micromanipulation tools are used to carefully separate the cells of interest, which are then transferred to a new growth medium for further study.

The tetrad is an addition to the famous dark triad. The fourth is always different

"Dark Tetrad" of personality traits: Everyday sadists take pleasure in others' pain

Anna Mikulak

Association for Psychological Science

Thu, 12 Sep 2013 12:23 UTCMap

Most of the time, we try to avoid inflicting pain on others - when we do hurt someone, we typically experience guilt, remorse, or other feelings of distress. But for some, cruelty can be pleasurable, even exciting. New research suggests that this kind of everyday sadism is real and more common than we might think.

Two studies led by psychological scientist Erin Buckels of the University of British Columbia revealed that people who score high on a measure of sadism seem to derive pleasure from behaviors that hurt others, and are even willing to expend extra effort to make someone else suffer.

The new findings are published in Psychological Science, a journal of the Association for Psychological Science.

"Some find it hard to reconcile sadism with the concept of 'normal' psychological functioning, but our findings show that sadistic tendencies among otherwise well-adjusted people must be acknowledged," says Buckels. "These people aren't necessarily serial killers or sexual deviants but they gain some emotional benefit in causing or simply observing others' suffering."

Based on their previous work on the "Dark Triad" of personality, Buckels and colleagues Delroy Paulhus of the University of British Columbia and Daniel Jones of the University of Texas El Paso surmised that sadism is a distinct aspect of personality that joins with three others - psychopathy, narcissism, and Machiavellianism - to form a "Dark Tetrad" of personality traits.

To test their hypothesis, they decided to examine everyday sadism under controlled laboratory conditions. They recruited 71 participants to take part in a study on "personality and tolerance for challenging jobs." Participants were asked to choose among several unpleasant tasks: killing bugs, helping the experimenter kill bugs, cleaning dirty toilets, or enduring pain from ice water.

Participants who chose bug killing were shown the bug-crunching machine: a modified coffee grinder that produced a distinct crunching sound so as to maximize the gruesomeness of the task. Nearby were cups containing live pill bugs, each cup labeled with the bug's name: Muffin, Ike, and Tootsie.

The participant's job was to drop the bugs into the machine, force down the cover, and "grind them up." The participants didn't know that a barrier actually prevented the bugs from being ground up and that no bugs were harmed in the experiment.

Of the 71 participants, 12.7% chose the pain-tolerance task, 33.8% chose the toilet-cleaning task, 26.8% chose to help kill bugs, and 26.8% chose to kill bugs.

Participants who chose bug killing had the highest scores on a scale measuring sadistic impulses, just as the researchers predicted. The more sadistic the participant was, the more likely he or she was to choose bug killing over the other options, even when their scores on Dark Triad measures, fear of bugs, and sensitivity to disgust were taken into account.

Participants with high levels of sadism who chose to kill bugs reported taking significantly greater pleasure in the task than those who chose another task, and their pleasure seemed to correlate with the number of bugs they killed, suggesting that sadistic behavior may hold some sort of reward value for those participants.

And a second study revealed that, of the participants who rated high on one of the "dark" personality traits, only sadists chose to intensify blasts of white noise directed at an innocent opponent when they realized the opponent wouldn't fight back. They were also the only ones willing to expend additional time and energy to be able to blast the innocent opponent with the noise.

Together, these results suggest that sadists possess an intrinsic motivation to inflict suffering on innocent others, even at a personal cost - a motivation that is absent from the other dark personality traits.

The researchers hope that these new findings will help to broaden people's view of sadism as an aspect of personality that manifests in everyday life, helping to dispel the notion that sadism is limited to sexual deviants and criminals.

Buckels and colleagues are continuing to investigate everyday sadism, including its role in online trolling behavior.

"Trolling culture is unique in that it explicitly celebrates sadistic pleasure, or 'lulz,'" says Buckels. "It is, perhaps, not surprising then that sadists gravitate toward those activities."

And they're also exploring vicarious forms of sadism, such as enjoying cruelty in movies, video games, and sports.

The researchers believe their findings have the potential to inform research and policy on domestic abuse, bullying, animal abuse, and cases of military and police brutality.

"It is such situations that sadistic individuals may exploit for personal pleasure," says Buckels. "Denying the dark side of personality will not help when managing people in these contexts."…/266289-Dark-Tetrad-of-personality-tr…


What Is a Tetrad?

Imagine two pairs of identical twins standing next to each other to make a group of four. Now, imagine that the people are strands of DNA during meiosis. Bingo, a tetrad.

Okay, it is not a perfect example, but it is a good start.

A tetrad is the foursome during meiosis made by two homologous chromosomes that have each already replicated into a pair of sister chromatids.

If that is confusing, don't worry. The nitty gritty details are coming right up.

Basic Meiosis Reminder

Humans have 23 different chromosomes (numbered 1-23), but they have two versions of each one. This means that all cells in the human body have 46 chromosomes. Well, except for the sex cells.

If the sperm and egg each had 46 chromosomes, then their offspring would end up with 92 chromosomes. Instead, humans make their sperm and egg cells with only 23 chromosomes each. Then, when they join to make a baby it will have 46 chromosomes, the magic number.

The process of making cells with only half the DNA is called meiosis.

When an egg is fertilized by a sperm, it receives one version of each chromosome from the mother and one from the father. So, two versions of chromosome #1, two versions of chromosome #2, all the way up until two versions of chromosome #23. The two versions of each chromosome are called homologous chromosomes.

Think of your chromosomes like a deck of cards from 1-23. Your father gave you 1-23 of clubs and your mother gave you 1-23 of diamonds. The five of clubs and the five of diamonds are homologous chromosomes. Similar, because they are both number 5…but slightly different.

Forming the Tetrad

Before meiosis can begin, a regular cell replicates its 46 chromosomes. The original version and the new copy remain attached together like conjoined twins and are called sister chromatids. So, just before meiosis, a cell has 46 chromosomes (23 pairs of homologous chromosomes), and each one consists of two sister chromatids. If we think back to our cards, now imagine that you copied each card and stapled the copy to the original. In other words, your five of clubs is stapled to an identical five of clubs.

Meiosis. The long and short chromosomes are different chromosomes. The red and grey are different versions of each. Step 1 replicated them. Step 2 is alignment and formation of the tetrad. Step 3 is crossing over. Step 4 is separation of the homologous chromosomes. Step 5 is separation of the sister chromatids.

Meiosis Process

The first stage of meiosis is called prophase I, and this is when the tetrad forms. The two homologous chromosomes will align next to each other. But, since each is made up of two sister chromatids it will look like a group of four. In card version: the two fives of clubs stapled together are aligned with the two fives of diamonds that are also stapled together.



In Allen's world-historical theory of kinship, humanity began with a tetradic-Dravidian system based on cross-cousin marriage and defined by alternate generation, prescriptive, and classificatory equations



The ligaments in the knee connect the femur (thighbone) to the tibia (shin bone), and include the following:

Anterior cruciate ligament (ACL). ...

Posterior cruciate ligament (PCL). ...

Medial collateral ligament (MCL). ...

Lateral collateral ligament (LCL).

The form of an amino acid is a quadrant with the fourth part being different

Amino acids are the monomeric building blocks of proteins. The α carbon atom (Cα) of amino acids, which is adjacent to the carboxyl group, is bonded to four different chemical groups: an amino (NH2) group, a carboxyl (COOH) group, a hydrogen (H) atom, and one variable group, called a side chain or R group (Figure 3-1). All 20 different amino acids have this same general structure, but their side-chain groups vary in size, shape, charge, hydrophobicity, and reactivity.

The Cerebrum: The cerebrum or cortex is the largest part of the human brain, associated with higher brain function such as thought and action. The cerebral cortex is divided into four sections, called "lobes": the frontal lobe, parietal lobe, occipital lobe, and temporal lobe. Here is a visual representation of the cortex:

In the developing vertebrate embryo, the neural tube is subdivided into FOUR unseparated sections which then develop further into distinct regions of the central nervous system; these are the prosencephalon (forebrain), the mesencephalon (midbrain) the rhombencephalon (hindbrain) and the spinal cord.[

A quadrat is a plot used in ecology and geography to isolate a standard unit of area for study of the distribution of an item over a large area. While originally rectangular, modern quadrats can be rectangular, circular, irregular, etc.,.[1][2] The quadrat is suitable for sampling plants, slow-moving animals (such as millipedes and insects), and some aquatic organisms.

When an ecologist wants to know how many organisms there are in a particular habitat, it would not be feasible to count them all. Instead, he or she would be forced to count a smaller representative part of the population, called a sample. Sampling of plants or animals that do not move much (such as snails), can be done using a sampling square called a quadrat. A suitable size of a quadrat depends on the size of the organisms being sampled. For example, to count plants growing on a school field, one could use a quadrat with sides 0.5 or 1 meter in length.

It is important that sampling in an area is carried out at random, to avoid bias. For example, if you were sampling from a school field, but for convenience only placed quadrats next to a path, this might not give a sample that was representative of the whole field. It would be an unrepresentative, or biased, sample. One way one can sample randomly is to place the quadrats at coordinates on a numbered grid. Quadrats may also be used sampling oneself.

Long-term studies may require that the same quadrats be revisited months or even years after initial sampling. Methods of relocating the precise area of study vary widely in accuracy, and include measurement from nearby permanent markers, use of total station theodolites, consumer-grade GPS, and differential GPS.[3]

A helix bundle is a small protein fold composed of several alpha helices that are usually nearly parallel or antiparallel to each other.

Contents [hide]

1 Three-helix bundles

2 Four-helix bundles

3 See also

4 References

5 External links

Three-helix bundles[edit]

An example of the three-helix bundle fold, the headpiece domain from the protein villin as expressed in chickens (PDB ID 1QQV).

Three-helix bundles are among the smallest and fastest known cooperatively folding structural domains.[1] The three-helix bundle in the villin headpiece domain is only 36 amino acids long and is a common subject of study in molecular dynamics simulations because its microsecond-scale folding time is within the timescales accessible to simulation [2][3] The 40-residue HIV accessory protein has a very similar fold and has also been the subject of extensive study.[4] There is no general sequence motif associated with three-helix bundles, so they cannot necessarily be predicted from sequence alone. Three-helix bundles often occur in actin-binding proteins and in DNA-binding proteins.

Four-helix bundles[edit]

Four-helix bundles typically consist of four helices packed in a coiled-coil arrangement with a sterically close-packed hydrophobic core in the center. Pairs of adjacent helices are often additionally stabilized by salt bridges between charged amino acids. The helix axes typically are oriented about 20 degrees from their neighboring helices, a much shallower incline than in the larger helical structure of the globin fold.[5]

The specific topology of the helices is dependent on the protein - helices that are adjacent in sequence are often antiparallel, although it is also possible to arrange antiparallel links between two pairs of parallel helices. Because dimeric coiled-coils are themselves relatively stable, four-helix bundles can be dimers of coiled-coil pairs, as in the Rop protein. Four-helix bundle can have thermal stability more than 100℃. Other examples of four-helix bundles include cytochrome, ferritin, human growth hormone, cytokine,[5] and Lac repressor C-terminal. The four-helix bundle fold has proven an attractive target for de novo protein design, with numerous de novo four-helix bundle proteins having been successfully designed by rational[6] and by combinatorial[7] methods. Although sequence is not conserved among four-helix bundles, sequence patterns tend to mirror those of coiled-coil structures in which every fourth and seventh residue is hydrophobic.





A Ramachandran plot (also known as a Ramachandran diagram or a [φ,ψ] plot), originally developed in 1963 by G. N. Ramachandran, C. Ramakrishnan, and V. Sasisekharan,[1] is a way to visualize backbone dihedral angles ψ against φ of amino acid residues in protein structure and identify sterically allowed regions for these angles. The figure at left illustrates the definition of the φ and ψ backbone dihedral angles[2] (called φ and φ' by Ramachandran). The ω angle at the peptide bond is normally 180°, since the partial-double-bond character keeps the peptide planar.[3] The figure at top right shows the allowed φ,ψ backbone conformational regions from the Ramachandran et al. 1963 and 1968 hard-sphere calculations: full radius in solid outline, reduced radius in dashed, and relaxed tau (N-Calpha-C) angle in dotted lines.[4] Because dihedral angle values are circular and 0° is the same as 360°, the edges of the Ramachandran plot "wrap" right-to-left and bottom-to-top. For instance, the small strip of allowed values along the lower-left edge of the plot are a continuation of the large, extended-chain region at upper left.

The plot is in the form of a quadrant.

A Ramachandran plot can be used in two somewhat different ways. One is to show in theory which values, or conformations, of the ψ and φ angles are possible for an amino-acid residue in a protein (as at top right). A second is to show the empirical distribution of datapoints observed in a single structure (as at right, here) in usage for structure validation, or else in a database of many structures (as in the lower 3 plots at left). Either case is usually shown against outlines for the theoretically favored regions.

The fourth square of a Rakmachandran plot is empty. The fourth square is always different.


Structurally, the lac repressor protein is a homo-tetramer. The tetramer contains two DNA binding subunits composed of two monomers each (sometimes called "dimeric lac repressor"). These subunits dimerize to form a tetramer capable of binding two operator sequences. Each monomer [3][4][5] consists of four distinct regions:


an N-terminal DNA-binding domain (in which two LacI proteins bind a single operator site)

a regulatory domain (sometimes called the core domain, which binds allolactose, an allosteric effector molecule)

a linker that connects the DNA-binding domain with the core domain (sometimes called the hinge helix, which is important for allosteric communication[5])

a C-terminal tetramerization region (which joins four monomers in an alpha-helix bundle)

DNA binding occurs via an N-terminal helix-turn-helix structural motif and is targeted to one of several operator DNA sequences (known as O1, O2 and O3). The O1 operator sequence slightly overlaps with the promoter, which increases the affinity of RNA polymerase for the promoter sequence such that it cannot enter elongation and remains in Abortive initiation. Additionally, because each tetramer contains two DNA-binding subunits, binding of multiple operator sequences by a single tetramer induces DNA looping.[6]

The winged helix-turn-helix (wHTH) motif is formed by a 3-helical bundle and a 3- or 4-strand beta-sheet (wing). The topology of helices and strands in the wHTH motifs may vary. In the transcription factor ETS wHTH folds into a helix-turn-helix motif on a four-stranded anti-parallel beta-sheet scaffold arranged in the order α1-β1-β2-α2-α3-β3-β4 where the third helix is the DNA recognition helix.[13][14]

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A protein contact map is in the form of a quadrant.

A protein contact map represents the distance between all possible amino acid residue pairs of a three-dimensional protein structure using a binary two-dimensional matrix. For two residues i and j, the ij element of the matrix is 1 if the two residues are closer than a predetermined threshold, and 0 otherwise. Various contact definitions have been proposed: The distance between the Cα-Cα atom with threshold 6-12 Å; distance between Cβ-Cβ atoms with threshold 6-12 Å (Cα is used for Glycine); and distance between the side-chain centers of mass.

In representations of the HB plot, characteristic patterns of secondary structure elements can be recognised easily, as follows:


Helices can be identified as strips directly adjacent to the diagonal.

Antiparallel beta sheets appear in HB plot as cross-diagonal.

Parallel beta sheets appears in the HB plot as parallel to the diagonal.

Loops appear as breaks in the diagonal between the cross-diagonal beta-sheet motifs.

A wobble base pair is a pairing between two nucleotides in RNA molecules that does not follow Watson-Crick base pair rules.[1] The FOUR main wobble base pairs are guanine-uracil (G-U), hypoxanthine-uracil (I-U), hypoxanthine-adenine (I-A), and hypoxanthine-cytosine (I-C). In order to maintain consistency of nucleic acid nomenclature, "I" is used for hypoxanthine because hypoxanthine is the nucleobase of inosine;[2] nomenclature otherwise follows the names of nucleobases and their corresponding nucleosides (e.g., "G" for both guanine and guanosine). The thermodynamic stability of a wobble base pair is comparable to that of a Watson-Crick base pair. Wobble base pairs are fundamental in RNA secondary structure and are critical for the proper translation of the genetic code.


Wobble hypothesis[edit]

These notions led Francis Crick to the creation of the wobble hypothesis, a set of FOUR relationships explaining these naturally occurring attributes.


The first two bases in the codon create the coding specificity, for they form strong Watson-Crick base pairs and bond strongly to the anticodon of the tRNA.

When reading 5' to 3' the first nucleotide in the anticodon (which is on the tRNA and pairs with the last nucleotide of the codon on the mRNA) determines how many nucleotides the tRNA actually distinguishes.

If the first nucleotide in the anticodon is a C or an A pairing is specific and acknowledges original Watson-Crick pairing, that is only one specific codon can be paired to that tRNA. If the first nucleotide is U or G, the pairing is less specific and in fact two bases can be interchangeably recognized by the tRNA. Inosine displays the true qualities of wobble, in that if that is the first nucleotide in the anticodon then any of three bases in the original codon can be matched with the tRNA.

Due to the specificity inherent in the first two nucleotides of the codon, if one amino acid codes for multiple anticodons and those anticodons differ in either the second or third position (first or second position in the codon) then a different tRNA is required for that anticodon.

The minimum requirement to satisfy all possible codons (61 excluding three stop codons) is 32 tRNAS. That is 31 tRNA's for the amino acids and one initiation codon.[8]



Four-base codons ACCA, ACCU and ACCC are recognized by frameshift suppressor sufJ

Lionello Bossi∗, John R. Roth

Department of Biology University of Utah Salt Lake City, Utah 84112, USA

∗Present address: Howard Hughes Medical Institute, University of Utah, Salt Lake City, Utah 84112.






The frameshift suppressor sufJ acts to correct a set of +1 frameshift mutations having very different sequences at their mutant sites. This suppressor acts by reading a 4 base codon located near, but not at, the site of each suppressible mutation. Suppression thus necessitates out-of-phase translation of the short stretch of mRNA between the site of action of the suppressor tRNA and the site of the frameshift mutation. We have identified the site read by sufJ by mutationally creating a series of such sites in the neighborhood of a previously nonsuppressible frameshift mutation. Each of the newly generated sites was formed by base substitution. Four independently generated sites were analyzed by DNA sequencing. At each site the quadruplet codon ACCX was generated (where X is A, U or C). Thus sufJ is able to read a 4 base codon in which any of three bases is acceptable in the fourth position. This is the first frameshift suppressor that does not read a run of three repeated bases in the first three positions of its codon.

The flanks have four indistinct dark vertical stripes and rows of diffused spots. The outer surface of the thighs has 3–4 distinct vertical or oblique dark bands which merge into transverse stripes in the lower portion of the legs. The tip of the tail is black with white underfur.[14]

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Laminin, an Important Protein that Looks Like a Cross-Truth!



Summary of eRumor:


The eRumor talks of a substance called “laminin” that is described as part of a family of proteins that “hold us together.” Then there is a picture of laminin—which looks like a cross.


The Truth:


This story leads into complex considerations of science and biology but the main questions it prompts are whether laminin is as important as the eRumor claims and does it have a shape like a cross.



The simple answer to both questions seems to be yes.

Laminin is defined by the Webster Medical Dictionary as a “glycoprotein that is a component of connective tissue basement membrane and that promotes cell adhesion.” In other words, looking at laminin as a kind of glue isn’t far from the truth. There are several different laminins.


In their book The Laminins authors Peter Elkblom and Rupert Timpl go into more detail about both the importance of laminins and their structure. They describe laminins that, together with other proteins, “hold cells and tissues together.” They also say, “Electron microscopy reveals a cross-like shape for all laminins investigated so far.” They went on to say that in solution the laminin shapes were more like a flower than a cross. The strands of laminins do not always stand straight and at right angles, but they do consists of arms, three of which are short and one of which is long.



Research has been conducted on laminins in connection with numerous conditions and diseases. It has been found, for example, that people with congenital muscular dystrophies do not have laminin-alpha2, which is normally found in the layer of cells around muscle fibers and other cells important to the structural integrity of muscle cells.


Updated 5/14/08

In fact, it’s much more commonplace to observe laminin in a swastika configuration than in a cross-like one.



The writings Bagdasarova have interesting information about the swastika for people prone to the scientific knowledge of the world. "Archetype swastika played at all levels of the universe. Confirmation of this — follow the migration of cells and cell layers, in which the structure of fixed micro-shaped swastika. It is a cell adhesion molecules. (Adhesion, one of the primary processes of development, means sticking, cell attachment to each other, without which there can be no embryo).


Adhesion molecule (IAC) form structures, each branch of which is a protein chain. " IAC photos taken with an electron microscope, look like three-and four-armed swastika. "Thus, the expression of the MAC process (creation of the microcosm), available human eye in the form of a swastika, the model reproduces the shape of the universe (the macrocosm) …" has the same structure as our galaxy, seen pictures of the universe from space. Therefore, the swastika is very attractive for astrophysics and geophysics. And perhaps it is with these facts relate mystical and esoteric aspects of the symbolism of the swastika.


Thus, we see that the sign of the swastika permeates our being from micro to macro and occurs everywhere in our lives, but our contemporaries (particularly in the former Soviet Union), have lost the ancient knowledge and cultural traditions of generations, sometimes about it and not know it. And it becomes clear why our ancestors thought the swastika sign Creator called sacred symbol and so carefully carried the tradition of transmission of knowledge from generation to generation.


Tamara Bogdanova.

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Prokaryotic cells have various shapes; the four basic shapes of bacteria are:[9]


Cocci – spherical

Bacilli – rod-shaped

Spirochaete – spiral-shaped

Vibrio – comma-shaped

APPEAR IN TETRADS (groups of four)


Micrococcus (mi’ krō kŏk’ Əs) is a genus of bacteria in the Micrococcaceae family. Micrococcus occurs in a wide range of environments, including water, dust, and soil. Micrococci have Gram-positive spherical cells ranging from about 0.5 to 3 micrometers in diameter and typically appear in tetrads

Cuvier, 1817[edit]


Haeckel's 'Monophyletischer Stambaum der Organismen' from Generelle Morphologie der Organismen (1866) with the three branches Plantae, Protista, Animalia

In his 1817 work, Le Règne Animal, the French zoologist Georges Cuvier combined evidence from comparative anatomy and palaeontology[3] to divide the animal kingdom into four body plans. Taking the central nervous system as the main organ system which controlled all the others, such as the circulatory and digestive systems, Cuvier distinguished four body plans:[4]


I. with a brain and a spinal cord (surrounded by skeletal elements)[4]

II. with organs linked by nerve fibres[4]

III. with two longitudinal, ventral nerve cords linked by a band with two ganglia below the oesophagus[4]

IV. with a diffuse nervous system, not clearly discernible[4]

Grouping animals with these body plans resulted in four branches: vertebrates, molluscs, articulata (including insects and annelids) and zoophytes or radiata.

Von Baer instead recognised four distinct animal body plans: radiate, like starfish; molluscan, like clams; articulate, like lobsters; and vertebrate, like fish. Zoologists then largely abandoned recapitulation, though Ernst Haeckel revived it in 1866.[2][3][4][5][6]

The four-species taxonomic classification, proposed in 2016 but criticized since then, has the genus Giraffa composed of the species Giraffa giraffa (southern giraffe), Giraffa tippelskirchi (Masai giraffe), Giraffa reticulata (reticulated giraffe) and Giraffa camelopardalis (northern giraffe).

Blood is a specialized body fluid. It has four main components: plasma, red blood cells, white blood cells, and platelets.


Jehovah's Witnesses[edit]

Main article: J- Witnesses and blood transfusions

Based on their interpretation of scriptures such as Acts 15:28, 29 ("Keep abstaining...from blood."), many J- Witnesses neither consume blood nor accept transfusions of whole blood or its major components: red blood cells, white blood cells, platelets (thrombocytes), and plasma. Members may personally decide whether they will accept medical procedures that involve their own blood or substances that are further fractionated from the four major components.[39]


The lacteals were termed the fourth kind of vessels (the other three being the artery, vein and nerve, which was then believed to be a type of vessel), and disproved Galen's assertion that chyle was carried by the veins.

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Individuals of the Styracosaurus genus were approximately 5.5 metres (18 ft) long as adults and weighed around 2.7 tonnes.[2] The skull was massive, with a large nostril, a tall straight nose horn, and a parietosquamosal frill (a neck frill) crowned with at least four large spikes. Each of the four longest frill spines was comparable in length to the nose horn, at 50 to 55 centimetres long (19.7 to 21.7 in).[3] The nasal horn is estimated at 57 centimeters long (19.7 in) in the type specimen,[4] but the horn is only partially complete. Based on other nasal horn cores from Styracosaurus and Centrosaurus, this horn may have come to a rounded point at around half of that length.[5]


Aside from the large nasal horn and four long frill spikes, the cranial ornamentation was variable. Some individuals had small hook-like projections and knobs at the posterior margin of the frill, similar to but smaller than those in Centrosaurus. Others had less prominent tabs. Some, like the type individual, had a third pair of long frill spikes. Others had much smaller projections, and small points are found on the side margins of some but not all specimens. Modest pyramid-shaped brow horns were present in subadults, but were replaced by pits in adults.[5] Like most ceratopsids, Styracosaurus had large fenestrae (skull openings) in its frill. The front of the mouth had a toothless beak.


Growth and ontogeny[edit]


Skull growth series

In 2006, the first extensive ontogenetic study of Triceratops was published in the journal Proceedings of the Royal Society. The study, by John R. Horner and Mark Goodwin, found that individuals of Triceratops could be divided into four general ontogenetic groups, babies, juveniles, subadults, and adults. With a total number of 28 skulls studied, the youngest was only 38 cm (15 in) long. 10 of the 28 skulls could be placed in order in a growth series with one representing each age. Each of the four growth stages were found to have identifying features. Multiple ontogenetic trends were discovered, including the size reduce of the epoccipitals, development and reorientation of postorbital horns, and hollowing out of the horns.[82]


Diabloceratops means “devil horned face”. Its spectacular remains were found in Utah. It had a very small nasal horn, but its brow horns were quite large, and the ones in top of the frill were even larger. These four horns, along with the forward-curving frill, gave this animal a strange appearance, different from all other horned dinosaurs known. Diabloceratops seems to be a primitive horned dinosaur, since it shares some anatomical traits with the protoceratopsids, a closely related but less advanced family. Its jaws were massive, which suggests that its bite was very powerful. The same is true for most other ceratopsians and it is possible that many species used their huge beaks as much as their horns, as weapons against predators.



The ferocious vegetarian: Two ton, 20ft long 'alien horned-face' dinosaur discovered in Canada

Scientists re-examining old fossils found in Canada have named a massive new species of dinosaur which wielded four horns and weighed as much as two tons.


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Scientists re-examining old fossils found in Canada have named a massive new species of dinosaur which wielded four horns and weighed as much as two tons.


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Fearsome: Xenoceratops foremostensis, which was up to 20ft long and weighed two tons, has been identified from fossils collected in the Fifties in Canada



Fearsome: Xenoceratops foremostensis, which was up to 20ft long and weighed two tons, has been identified from fossils collected in the Fifties in Canada



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The magical number four: A biological, historical and mythological enigma

Hans J. Grosscorresponding author

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Precise recognition of small object numbers without counting is a widespread phenomenon. It is well documented for humans and for a series of non-human vertebrates. Recently this has been confirmed for an invertebrate, the honeybee.1 This type of inborn numerical competence has been named “subitizing”, from the Latin subito = suddenly, immediately. It differs from the classical, sequential counting which has to be trained, starting with the help of our fingers. For humans it had been established since 1871 by Jevons2 that only up to four objects are precisely recognized and memorized. Under conditions which do not allow sequential counting, mistakes start to occur in case of more than four objects. This result has been confirmed whenever the range of visual attention has been carefully tested under a variety of rigorous conditions. It provides the basis for a novel hypothesis about the evolution of counting and numbering systems in ancient civilizations.3


Keywords: honeybee, magical number four, numerical competence, subitizing

Using a “delayed match-to-sample” setup in a Y-maze we determined the numerical capacity of honeybees. Even under variable and complex conditions, the insects were able to choose the correct object numbers in more than 80% of the decisions after only 4 rounds of training. Thus, up to 3 objects were memorized for about 5 sec during the flight from the entrance to the decision chamber of our setup, but 4 objects were recognized with less precision and with some difficulties,1 indicating that the borderline of numerical capacity in this species is between 3 and 4 objects. We were especially careful to avoid any possibility of pattern recognition which would render our results meaningless. Similar numerical capacities have previously been observed for a number of vertebrates.1 Partly those results were obtained under less stringent conditions because the very rigorous “delayed match-to-sample” setup had not been used or could not be used for all species. Moreover, many such studies, especially with “counting” animals, do not differentiate strictly enough between genuine counting, “subitizing” and pattern recognition. However, under rigorous testing conditions animals “subitize,” i.e., recognize and memorize object numbers without the ability of real counting.4


In summary, object numbers of more than three or four consequently have the meaning of “many” for honeybees and for other, rigorously examined animals. This seemingly innate ability of humans, of non-human vertebrates and of an insect, the honeybee, to recognize and memorize up to four objects correctly without sequential counting raises the following questions:


(a) What is the benefit for humans and animals to be able to “subitize” object numbers up to four precisely?


We can only speculate about the benefits of this ability. For early hominids, who certainly were not able to count as we do, the ability to estimate within the fraction of a second whether two, four or “many” lions are watching them, the decision to attack and fight, to defend or to try to escape might have been a matter of life and death. For animals the ability to estimate whether two, four or “many” hungry carnivores are approaching may also have been crucial for survival. In case of the honeybee we have speculated that the memorization of object numbers (trees, houses or other landmarks) may be useful for their orientation and help them to find back home. In addition it may help the foraging bee to recognize branches with less than three to four or with “many” blossoms, or to estimate the number of foraging bees on a blossom, allowing the decision to join or to quit.1


(b) Why is there a limit of up to 4 objects in case of humans and animals, even in case of honeybees?


We obviously are dealing with an inborn ability of many species but we do not know the answer – maybe we ask the wrong question.


(c) What is the underlying neurobiological process?


The underlying neurobiological process is still unknown, although neuroimaging techniques like functional magnetic resonance imaging have revealed that defined regions of the brain are activated during calculations.


(d) What is the driving force or evolutionary pressure which sustains this numerical competence from bees to humans?


The driving force for having the inborn numerical competence to differentiate between 2, 3, 4 or “many” objects in a fraction of a second without counting may be or may have been an advantage in the struggle for survival for humans and non-human vertebrates. For honeybees, such a selective advantage appears less essential. Although the ability to “subitize” is a primitive, archaic ability, it appears justified to rule out the possibility of divergent evolution because the enormous evolutionary distances between humans and honeybees. If we consider the possibility of convergent evolution, we end up again with the question of selective advantage for the survival of a species involving exactly the same magical number four in humans and honeybees. What is the benefit for a pigeon mother to know whether she has four or “many” eggs in her nest? Pigeons have been shown to have numerical competence – but does this have any meaning for the survival and for the evolutionary success of the species? We have to admit that we do not know the answer. Does a look at the role of the magical number four in history and mythology help us to understand its biological significance?


(e) The role of the “magical” number 4 in history.


The earliest use of number 4 is the puzzling presentation of honeybees and honeybee hieroglyphs with 4 legs as early as 4.600 y ago throughout the history of ancient Egypt. There is no explanation why the correct number of 6 legs was not implemented by the Egyptian artists although an efficient numbering and counting system had been available.3


Another puzzling episode goes back to Aristotle (384–322 B.C.) who knew that animals with 4 legs never have wings. He wondered that the dayfly, whose short life-cycle he precisely described (4) is an exception in that this insect has wings despite of having 4 legs. Other examples for the importance of number four are the 4 seasons, the 4 sides and the 4 corners of a square, the rare four-leafed clover, a symbol of good luck in some cultures, in Hinduism the 4 faces of Brahma the creator, the 4 directions, the 4 elements water, fire earth and air and, finally, the 4 human temperaments: sanguine, choleric, melancholic and phlegmatic.


The 4 Cardinal Virtues sapientia (wisdom), iustitia (justice), fortitudo (courage) and temperantia (moderation) are frequently associated with Christian religion. Historically, however, these virtues go back to Plato (428/427–348/347 B.C.).


In a religious context the following examples for the importance of the “magical” number 4 come to mind:


(i) The possibility for a Muslim to have up to 4 legal wives if he can support them. This rule has often been misinterpreted and misunderstood, but it had the function to support widows, with and without children, whose husbands had lost their lives on the battlefields. But why precisely 4?


(ii) The 4 gospels and their corresponding evangelists. It was the Roman emperor Konstantin I. who decided that an obligatory, state-controlled religion with a single god – instead of the vast variety of gods, goddesses, half-gods, god-like previous emperors and cryptic oriental rites - would be an enormous advantage for ruling his huge but heterogeneous empire. He assembled more than 300 bishops at the Council of Nicaea in the year 325, and under his guidance – the religious delegates held different opinions about the existence of one single God or of a Trinity – only 4 out of more than hundred gospels existing at that time were selected as authentic. But why 4 and not 3 or 5 gospels? Could this be a reference to the 4 corners of the quadratic celestial Jerusalem5 or because 4 is the first non-prime in the endless sequence of numbers?


(f) The occurrence of the “magical” number 4 in mythology.


Among the oldest cases presented here are the 4 celestial emblems of the Chinese emperor: The Black Tortoise ( = North), the White Tiger ( = West), the Red Bird (Phoenix = South) and the Blue Dragon ( = East), ancient symbols which are several thousand years old.


In summary, questions about the evolution and the putative evolutionary advantage to “subitize” up to 4 objects without counting for the survival of a species remain without answer. We do not know why is this “magical number four” is common among humans, non-human vertebrates and honeybees. Moreover, a synopsis of the occurrence of this magical number in culture, religion and mythology highlights its universal significance but does not enlighten our understanding of the widespread, archaic, inborn ability for “subitinization.” The “magical number four” remains a biological, historical and mythological enigma.


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I thank my colleagues Profs. H. Beier, H. Hoehn and J. Tautz for critical reading of this manuscript and Dr. Mario Pahl for helpful suggestions.



Since the discovery of CTE in American football legend Mike Webster, whose experience of CTE was immortalised in the recent Hollywood movie “Concussion”, many other cases are being unearthed within the sport and our knowledge of the disease is expanding. Work from Neurophysiologist Dr Ann McKee has identified four stages of the disease: