query: polar bodies are produced during the formation of

pos: Polar body Polar body A polar body is a small haploid cell that is formed concomitantly as an egg cell during oogenesis, but which generally does not have the ability to be fertilized. When certain diploid cells in animals undergo cytokinesis after meiosis to produce egg cells, they sometimes divide unevenly. Most of the cytoplasm is segregated into one daughter cell, which becomes the egg or ovum, while the smaller "polar bodies" only get a small amount of cytoplasm. They frequently die (apoptosis) and disappear, but in some cases they remain and can be important in the life cycle of the organism.

pos: Polar body risk of diagnostic error, for instance due to the degradation of the genetic material or events of recombination that lead to heterozygous first polar bodies. Polar body A polar body is a small haploid cell that is formed concomitantly as an egg cell during oogenesis, but which generally does not have the ability to be fertilized. When certain diploid cells in animals undergo cytokinesis after meiosis to produce egg cells, they sometimes divide unevenly. Most of the cytoplasm is segregated into one daughter cell, which becomes the egg or ovum, while the smaller "polar bodies" only get a small amount

pos: Preimplantation genetic diagnosis the removal of PBs and blastomeres, and herniation of the trophectoderm cells. A "polar body biospy" is the sampling of a polar body, which is a small haploid cell that is formed concomitantly as an egg cell during oogenesis, but which generally does not have the ability to be fertilized. Compared to a blastocyst biopsy, a polar body biopsy can potentially be of lower costs, less harmful side-effects, and more sensitive in detecting abnormalities. The main advantage of the use of polar bodies in PGD is that they are not necessary for successful fertilisation or normal embryonic development, thus ensuring

pos: Polar body Polar body A polar body is a small haploid cell that is formed concomitantly as an egg cell during oogenesis, but which generally does not have the ability to be fertilized. When certain diploid cells in animals undergo cytokinesis after meiosis to produce egg cells, they sometimes divide unevenly. Most of the cytoplasm is segregated into one daughter cell, which becomes the egg or ovum, while the smaller "polar bodies" only get a small amount of cytoplasm. They frequently die (apoptosis) and disappear, but in some cases they remain and can be important in the life cycle of the organism.

neg: Polar body polar body can induce the formation of an aneuploid polar body. Therefore, the formation of the first polar body is an especially important factor in forming a healthy zygote. However, chromosomally abnormal polar bodies are not guaranteed to induce the development of an abnormal zygote. A euploid zygote can be produced if the aneuploidy is reciprocal: one polar body has an extra chromosome and the other lacks the same chromosome (see also uniparental disomy). If the extra chromosome is absorbed into a polar body rather than being passed into the oocyte, trisomy can be avoided. Whether this is a chance

neg: Polar body fibers, the rotation of which promotes invagination at the edge of the cell membrane and splits the polar body away from the oocyte. Meiotic errors can lead to aneuploidy in the polar bodies, which, in the majority of cases, produces an aneuploid zygote. Errors can occur during either of the two meiotic divisions that produce each polar body, but are more pronounced if they occur during the formation of the first polar body, because the formation of the first polar body influences the chromosomal makeup of the second. For example, predivision (the separation of chromatids before anaphase) in the first

neg: Polar body E.L. Mark. They were described as non-functioning egg cells which disintegrated because the spermatozoon, with rare exceptions, could not fertilize them and instead chemically triggered their dissolution. Polar bodies serve to eliminate one half of the diploid chromosome set produced by meiotic division in the egg, leaving behind a haploid cell. To produce the polar bodies, the cell must divide asymmetrically, which is fueled by furrowing (formation of a trench) near a particular point on the cell membrane. The presence of chromosomes induces the formation of an actomyosin cortical cap, a myosin II ring structure and a set of spindle

neg: Cortical granule includes increased quantities of cortical granules surrounding the CGFDs and a decreased overall quantity of the cell's cortical granules during the meiotic cycle. Additionally, some pre-fertilization cortical granule exocytotic events occur in the cell's cleavage furrow simultaneously with polar body formation. An assortment of hypotheses exist concerning the biological function of CGFDs and pre-fertilization cortical granule exocytosis. For instance, the formation of the CGFDs may be the oocyte's mechanism for retaining more cortical granules for future use rather than losing them to the polar bodies as the polar bodies extrude from the cell. Because some cortical granules released are from

neg: Selfish genetic element encompasses all of them is segregation distortion. Some elements can preferentially be transmitted in egg cells as opposed to polar bodies during meiosis, where only the former will be fertilized and transmitted to the next generation. Any gene that can manipulate the odds of ending up in the egg rather than the polar body will have a transmission advantage, and will increase in frequency in a population. Segregation distortion can happen in several ways. When this process occurs during meiosis it is referred to as . Many forms of segregation distortion occur in male gamete formation, where there is differential

neg: Drone (bee) one set from each parent. Since all the sperm cells produced by a particular drone are genetically identical, full sisters are more closely related than full sisters of other animals where the sperm is not genetically identical. A laying worker bee exclusively produces totally unfertilized eggs, which develop into drones. As an exception to this rule, laying worker bees in some subspecies of honey bees may also produce diploid (and therefore female) fertile offspring in a process called thelytoky, in which the second set of chromosomes comes not from sperm, but from one of the three polar bodies during anaphase

neg: Polar stratospheric cloud Polar stratospheric cloud Polar stratospheric clouds (PSCs), also known as nacreous clouds (, from "nacre", or mother of pearl, due to its iridescence), are clouds in the winter polar stratosphere at altitudes of . They are best observed during civil twilight, when the Sun is between 1 and 6 degrees below the horizon, as well as in winter and in more northerly latitudes. They are implicated in the formation of ozone holes. The effects on ozone depletion arise because they support chemical reactions that produce active chlorine which catalyzes ozone destruction, and also because they remove gaseous nitric acid, perturbing

neg: Polar body "Polar body twinning" is a hypothesized form of twinning in meiosis, where one or more polar bodies do not disintegrate and are fertilized by sperm. Twinning would occur, in principle, if the egg cell and a polar body were both fertilized by separate sperms. However, even if fertilization occurs, further development would usually not occur because the zygote formed by the fusion of the sperm and polar body would not have enough cytoplasm or stored nutrients to feed the developing embryo. Polar bodies were first identified and characterized in the early 20th century, primarily by O. Hertwig, T. Boveri, and

neg: Polar auxin transport transport inhibitors. 9-Hydroxyfluorene-9-carboxylic acid (HFCA), TIBA, and trans-cinnamic acid (TCA) are also example of Polar Auxin Transport Inhibitors. They prevent the development of the bilateral growth of the plant embryo during the globular stage. All 3 inhibitors induce the formation of fused cotyledons in globular but not heart-shaped embryo. Polar auxin transport can be regulated by reversible protein phosphorylation; protein kinases and protein phosphatases mediate the phosphorylation and dephosphorylation, respectively. A study suggests that phosphatase inhibition can alter the activities of acropetal and basipetal auxin transport. Polar auxin transport Polar auxin transport is the regulated transport of the plant hormone

neg: South Polar region of the Cretaceous in the Early Cretaceous, and likely the ancestors of the endemic mammals of Australia arrived during the Jurassic across the supercontinent Pangaea. Several fossils of insects and crustaceans are known from South Polar Cretaceous sediments of New Zealand. The Late Cretaceous Mangaotanean Monro Conglomerate was situated at 68°S and provided fossils of "Helastia sp.", and the crab "Hemioon novozelandicum" was found in the Swale Siltstone, located at 76°S during the late Albian. Several specimens of insects were also found in the Tupuangi Formation of the Chatham Islands at a latitude of 79°S during the Cenomanian to Turonian. South Polar region

neg: Reproductive biology gives rise to four spermatids through meiosis. Spermatids are now haploid and undergo differentiation into sperm cells. Later in reproduction the sperm will fuse with a female oocyte to form the zygote. Oogenesis is the formation of a cell who will produce one ovum and three polar bodies. Oogenesis begins in the female embryo with the production of oogonia from primordial germ cells. Like spermatogenesis, the primordial germ cell undergo mitotic division to form the cells that will later undergo meiosis, but will be halted at the prophase I stage. This is known as the primary oocyte. Human females are

neg: Polar body biopsy with normal first polar bodies can still be affected by errors. This method was initially performed with fluorescence in situ hybridization (FISH), then by hybridizing a sample into lymphocytes to observe it in metaphase, and more recently by microarrays, which are fully automated and make it easier to distinguish between chromosome vs. chromatid abnormalities. The main advantage of the use of polar bodies in PGD is that they are not necessary for successful fertilisation or normal embryonic development, thus ensuring no deleterious effect for the embryo. One of the disadvantages of PB biopsy is that it only provides information about

neg: Polar body biopsy the maternal contribution to the embryo, which is why cases of autosomal dominant and X-linked disorders that are maternally transmitted can be diagnosed, and autosomal recessive disorders can only partially be diagnosed. Another drawback is the increased risk of diagnostic error, for instance due to the degradation of the genetic material or events of recombination that lead to heterozygous first polar bodies. It is generally agreed that it is best to analyse both polar bodies in order to minimize the risk of misdiagnosis. This can be achieved by sequential biopsy, necessary if monogenic diseases are diagnosed, to be able to

neg: Polar vortex the Antarctic is considered an "ozone hole". This said, chemical ozone destruction in the 2011 Arctic polar vortex attained, for the first time, a level clearly identifiable as an Arctic "ozone hole". Other astronomical bodies are also known to have polar vortices, including Venus (double vortex—that is, two polar vortices at a pole), Mars, Jupiter, Saturn, and Saturn's moon Titan. Saturn's south pole is the only known hot polar vortex in the solar system. Polar vortex A polar vortex is an upper level low-pressure area lying near the Earth's poles. There are two polar vortices in the Earth's atmosphere, overlying

neg: Grizzly–polar bear hybrid born at Osnabrück Zoo in Osnabrück, Germany, in 2004, and their physical traits are generally an intermediate between the polar bear and the grizzly bear. For example, their bodies are smaller than polar bears, but larger than grizzlies, while their heads fall between the broader grizzly head and the leaner polar bear head. They have long necks like polar bears, but small shoulder humps like grizzlies. The soles of their feet are partially covered in hair; polar bears have hair-covered soles, which act as insulation, and grizzlies have hairless soles. Similarly, the hair of the hybrids exhibits a pattern of

neg: Agaricales by the fungus. The actual conditions necessary for fruit body formation and spore production are not clearly understood. Humidity, light, temperature, aeration, and nutrition are all factors thought to be important in fruit body formation. The genetic makeup and the general physiology of the fungus hyphae are also important in the initiation and formation of young fruit bodies and their development to a mature stage. The spores produced by a fruit body are released when it is mature. When they land in a suitable environment, the spores germinate and the hyphae grow to initiate the life cycle anew. There are

neg: Prince Creek Formation Leafy plants, roots and pollen are known from the formation, and they show that trampling by dinosaurs was common. It can be proven that during the Maastrichtian the Prince Creek Formation bordered a large body of water by the presence of gypsum and pyrite in nearby rock. Large amounts of plants material are represented by peridonoid dinocysts, algae, fungal hyphae, fern and moss spores, projectates, "Wodehouseia edmontonicola", hinterland bisaccate pollen, and pollen from trees, shrubs, and herbs. Concluded on the large amounts of dinosaurs and flora, the Prince Creek Formation was likely a polar woodland lacking ground ice with dinosaurs

neg: Myxococcus xanthus in large numbers. The tools of classical and molecular genetics are relatively well-developed in "M. xanthus". Although the fruiting bodies of "M. xanthus" are relatively primitive compared with, say, the elaborate structures produced by "Stigmatella aurantiaca" and other myxobacteria, the great majority of genes known to be involved in development are conserved across species. In order to make agar cultures of "M. xanthus" grow into fruiting bodies, one simply can plate the bacteria on starvation media. Furthermore, it is possible to artificially induce the production of myxospores without the intervening formation of fruiting bodies, by adding compounds such as glycerol

neg: Polar ice cap are over land, and cover less than 50,000 km: larger bodies are referred to as ice sheets. The composition of the ice will vary. For example, Earth's polar caps are mainly water ice, whereas Mars's polar ice caps are a mixture of solid carbon dioxide and water ice. Polar ice caps form because high-latitude regions receive less energy in the form of solar radiation from the Sun than equatorial regions, resulting in lower surface temperatures. Earth's polar caps have changed dramatically over the last 12,000 years. Seasonal variations of the ice caps takes place due to varied solar energy absorption

neg: Doñana National Park polar front and the subtropical ridge of high pressure. The rainy seasons are intermediate, occurring in spring and in autumn; autumn especially can produce torrential rains caused by the accumulation during the summer of heat in nearby large bodies of water, and the arrival of polar air masses. In winter, however, thermal anticyclones may occur locally. Temperatures are mild throughout the year, with maximum temperatures varying about 17 °C from winter to summer. The most significant feature of the climate is the three to five months of dry weather in the summer, when it is dominated by the subtropical anticyclone.

neg: South Polar region of the Cretaceous diversity terrestrial flora and fauna of the Late Cretaceous polar region. Seymour Island is similar in this respect, the area of discovery for vertebrate and invertebrate creatures–such as plesiosaurs–of the Late Cretaceous, extending into the Eocene. Other Cretaceous fossil-bearing formations in Antarctica are the Snow Hill Island Formation, the Lopez de Bertodano Formation, and the Hidden Lake Formation, also on James Ross Island. The Eumeralla Formation of Dinosaur Cove and the Wonthaggi Formation in Victoria, Australia, contain a number of dinosaur fossils and tracks from the Early Cretaceous. The Tahora Formation represents the reptile assemblage of Cretaceous New Zealand. The

neg: Vitrification with a liquid such as water, usually through very rapid cooling or the introduction of agents that suppress the formation of ice crystals. This is in contrast to ordinary freezing which results in ice crystal formation. Additives used in cryobiology or produced naturally by organisms living in polar regions are called cryoprotectants. Vitrification is used in cryo-electron microscopy to cool samples so quickly that they can be imaged with an electron microscope without damage. In 2017, the Nobel prize for chemistry was awarded for the development of this technology, which can be used to image objects such as proteins or

neg: Polyvinylidene fluoride ferroelectric polar phase, resulting in the formation of nano-polar domains. When an electric field is applied, the disordered nano-polar domains change their conformation to all-trans conformation, which leads to large electrostrictive strain and a high room-temperature dielectric constant of ~50. Polyvinylidene fluoride Polyvinylidene fluoride or polyvinylidene difluoride (PVDF) is a highly non-reactive thermoplastic fluoropolymer produced by the polymerization of vinylidene difluoride. PVDF is a specialty plastic used in applications requiring the highest purity, as well as resistance to solvents, acids and bases. Compared to other fluoropolymers, like polytetrafluoroethylene (Teflon), PVDF has a low density (1.78 g/cm). It is available as

neg: Polar ice cap Polar ice cap A polar ice cap or polar cap is a high-latitude region of a planet, dwarf planet, or natural satellite that is covered in ice. There are no requirements with respect to size or composition for a body of ice to be termed a polar ice cap, nor any geological requirement for it to be over land; only that it must be a body of solid phase matter in the polar region. This causes the term "polar ice cap" to be something of a misnomer, as the term ice cap itself is applied more narrowly to bodies that

neg: Pesticide degradation receptor. Such products should receive particular attention because they are often smaller and more polar than their parents. This increases their potential to reach drinking water resources such as groundwater and surface waters, where polar products are found at fairly constant concentrations. Products in drinking water resources may cause problems such as formation of carcinogenic N-nitroso-dimethylamine from dimethylsulfamide, a microbial product of the fungicides tolylfluanide and dichlofluanide, during water treatment with ozone. The issue is specifically addressed in major regulatory frameworks. In Europe, for instance, “nonrelevant” metabolites are distinguished from metabolites that are “relevant for groundwater resources” or even “ecotoxicologically

neg: Polar wander concentration where they are located, the planet tries to re-orient the supercontinent towards the equator. True polar wander may have been observed in other planetary bodies. Data suggests that Mars’s polar wander resembles Earth’s true polar wander; that is, when Mars had an active lithosphere its structure allowed slow polar drift to stabilize the moment of inertia. Unlike the Earth and Mars, Venus’s structure does not seem to allow the same slow polar wander; when observed the maximum moment of inertia of Venus is largely offset from the geographic pole. Therefore, the deviation of the maximum moment of inertia will

neg: Cloud altitude of tropospheric high clouds. From ground level, they can occasionally be seen illuminated by the sun during deep twilight. Ongoing research indicates that convective lift in the mesosphere is strong enough during the polar summer to cause adiabatic cooling of small amount of water vapour to the point of saturation. This tends to produce the coldest temperatures in the entire atmosphere just below the mesopause. These conditions result in the best environment for the formation of polar mesospheric clouds. There is also evidence that smoke particles from burnt-up meteors provide much of the condensation nuclei required for the formation

neg: Astrocompass Astrocompass An astrocompass is a navigational tool for determining the direction of true north through the positions of various astronomical bodies. There are certain circumstances when magnetic compasses and gyrocompasses are unreliable. The most obvious is in polar regions, where the force exerted on the needle of a magnetic compass is nearly vertical and gyrocompasses become unstable due to the rotation of the Earth. Magnetic compasses are also susceptible to disruption from magnetic fields other than the Earth's, such as those produced by the hulls of some metal vehicles or craft. Before the advent of electronic navigational aids such as

neg: Sandra Carson eggs could be salvaged and frozen before chemotherapy or radiation, and then matured outside the patient in the artificial ovary. In parallel with this effort and a scientific first, Carson co-directed a research team by extracting information about gene expression from fertile human egg cells without hurting them. In this work the team was able to sequence the transcribed genetic material, or mRNA, in egg cells, in smaller structures pinched off from them called polar bodies. Polar bodies are nonfunctional and incapable of being fertilized. This new technique could ultimately give parents and doctors a preview of which eggs are

neg: Pxr sRNA Pxr sRNA Pxr sRNA is a regulatory RNA which downregulates genes responsible for the formation of fruiting bodies in "Myxococcus xanthus". Fruiting bodies are aggregations of myxobacteria formed when nutrients are scarce, the fruiting bodies permit a small number of the aggregated colony to transform into stress-resistant spores. Pxr exists in two forms: Pxr-L (a long form) and Pxr-S which is shorter. The short form was found to be expressed in cells during growth but is rapidly repressed during starvation. This finding implies that Pxr-S is specifically responsible for inhibiting the fruiting body development during cell growth when nutrients are

neg: Parthenogenesis first two blastomeres. Other species restore their ploidy by the fusion of the meiotic products. The chromosomes may not separate at one of the two anaphases (called "restitutional meiosis"), or the nuclei produced may fuse or one of the polar bodies may fuse with the egg cell at some stage during its maturation. Some authors consider all forms of automixis sexual as they involve recombination. Many others classify the endomitotic variants as asexual, and consider the resulting embryos parthenogenetic. Among these authors the threshold for classifying automixis as a sexual process depends on when the products of anaphase I or

neg: ATP-binding cassette transporter to accommodate the sugar groups from lipopolysaccharides (LPS). As has been suggested by several groups, binding of substrate initiates the transport cycle. The "power stroke", that is, ATP binding that induces NBD dimerization and formation of the ATP sandwich, drives the conformational changes in the TMDs. In MsbA, the sugar head groups are sequestered within the chamber during the "power stroke". The cavity is lined with charged and polar residues that are likely solvated creating an energetically unfavorable environment for hydrophobic substrates and energetically favorable for polar moieties in amphiphilic compounds or sugar groups from LPS. Since the lipid cannot

neg: Polar coordinate system point positions lie on a single two-dimensional plane. They are most appropriate in any context where the phenomenon being considered is inherently tied to direction and length from a center point. For instance, the examples above show how elementary polar equations suffice to define curves—such as the Archimedean spiral—whose equation in the Cartesian coordinate system would be much more intricate. Moreover, many physical systems—such as those concerned with bodies moving around a central point or with phenomena originating from a central point—are simpler and more intuitive to model using polar coordinates. The initial motivation for the introduction of the polar

neg: Protogalaxy The established theory is that the groups of small protogalaxies were attracted together by gravity and collided, which resulted in the formation of the much larger "adult" galaxies we have today. This follows the process of hierarchical assembly, which is an ongoing process where larger bodies are continually formed from the merging of smaller ones. Since there had been no previous star formation to create other elements, protogalaxies would have been made up almost entirely of hydrogen and helium. The hydrogen would bond to form H molecules, with some exceptions. This would change as star formation began and produced more

neg: McMurray Formation reached more than ; 53% of this was produced by surface mining and 47% by in-situ methods. The Alberta government estimates that production could reach by 2020 and possibly by 2030. The Lower Member of the McMurray Formation consists predominantly of poorly consolidated, discontinuous sand bodies. These sands are commonly saturated with water rather than with bitumen, and lie beneath bitumen-saturated sands that are aquitards. They are commonly referred to as the Basal Water Sand (BWS) aquifers. Where these aquifers are deep-lying and recharge occurs from the underlying Devonian formations, they are saline, but where they lie at relatively shallow

neg: Polyethylene of the disturbed crystal formation. With higher proportions it approaches to the one of polyvinyl acetate (1.17 g/cm). Due to decreasing crystallinity ethylene vinyl acetate copolymers are getting softer with increasing comonomer content. The polar side groups change the chemical properties significantly (compared to polyethylene): weather resistance, adhesiveness and weldability rise with comonomer content, while the chemical resistance decreases. Also mechanical properties are changed: stress cracking resistance and toughness in the cold rise, whereas yield stress and heat resistance decrease. With a very high proportion of comonomers (about 50%) rubbery thermoplastics are produced (thermoplastic elastomers). Ethylene-ethyl acrylate copolymers behave similarly

neg: Cyathus of time and under the appropriate environmental conditions, the dikaryotic mycelia may enter the reproductive stage of the life cycle. Fruit body formation is influenced by external factors such as season (which affects temperature and air humidity), nutrients and light. As fruit bodies develop they produce peridioles containing the basidia upon which new basidiospores are made. Young basidia contain a pair of haploid sexually compatible nuclei which fuse, and the resulting diploid fusion nucleus undergoes meiosis to produce basidiospores, each containing a single haploid nucleus. The dikaryotic mycelia from which the fruit bodies are produced is long lasting, and will

neg: Germ cell ribosomes, and the mRNA needed for protein synthesis during early embryonic growth. These intensive RNA biosynthese are mirrored in the structure of the chromosomes, which decondense and form lateral loops giving them a lampbrush appearance (see Lampbrush chromosome). Oocyte maturation is the following phase of oocyte development. It occurs at sexual maturity when hormones stimulate the oocyte to complete meiotic division I. The meiotic division I produces 2 cells differing in size: a small polar body and a large secondary oocyte. The secondary oocyte undergoes meiotic division II and that results in the formation of a second small polar body

neg: Lipid lamellar phase lipid bilayer. The formation of lipid bilayers is an energetically preferred process when the glycerophospholipids described above are in an aqueous environment. This is known as the hydrophobic effect. In an aqueous system, the polar heads of lipids align towards the polar, aqueous environment, while the hydrophobic tails minimize their contact with water and tend to cluster together, forming a vesicle; depending on the concentration of the lipid, this biophysical interaction may result in the formation of micelles, liposomes, or lipid bilayers. Other aggregations are also observed and form part of the polymorphism of amphiphile (lipid) behavior. Phase

neg: Stratosphere around at midlatitudes, and at about at the poles. Temperatures range from an average of near the tropopause to an average of near the mesosphere. Stratospheric temperatures also vary within the stratosphere as the seasons change, reaching particularly low temperatures in the polar night (winter). Winds in the stratosphere can far exceed those in the troposphere, reaching near in the Southern polar vortex. The mechanism describing the formation of the ozone layer was described by British mathematician Sydney Chapman in 1930. Molecular oxygen absorbs high energy sunlight in the UV-C region, at wavelengths shorter than about 240 nm. Radicals produced

neg: Microstructure biological materials, certain hydrated minerals, polymers, and some mixed–composite materials. Weak nonpolar bonds or hydrophobic bonds are formed by repulsion. In a polar liquid, the molecules try to establish a maximum number of bonds between each other. If nonpolar molecules are added to the solution, their presence disrupts the formation of this network of bonds, and they will be rejected. Uniquely nonpolar molecules are rare in nature and for the most part are found in hydrocarbons. Fatty acids are amphiphilic molecules, containing a polar end and a nonpolar end. These molecules will then form complex structures, with the polar end

neg: Lemna gibba small water plants, which forms familiar green mats covering stagnant water bodies. Widespread throughout Great Britain, but is absent from much of Scotland and Shetland. In Ireland, it is found mainly in the north and east. Elsewhere, the species has a very wide global distribution, absent only from polar areas and the tropics. Distribution information for this species can be accessed via the Charms of Duckweed (worldwide) and National Biodiversity Network Gateway (Britain only). This species spreads mainly through vegetative reproduction, but flowers are occasionally produced in shallow water exposed to full sun. When covering the entire surface of a

neg: Inclusion bodies that inclusion bodies are dynamic structures formed by an unbalanced equilibrium between aggregated and soluble proteins of "Escherichia coli". There is a growing body of information indicating that formation of inclusion bodies occurs as a result of intracellular accumulation of partially folded expressed proteins which aggregate through non-covalent hydrophobic or ionic interactions or a combination of both. Inclusion bodies are dense electron-refractile particles of aggregated protein found in both the cytoplasmic and periplasmic spaces of "E. coli" during high-level expression of heterologous protein. It is generally assumed that high level expression of non-native protein (higher than 2% of cellular protein)

neg: Nematology Nematologists in the 1800s also contributed to other scientific fields in important ways. Butschli (1875) first observed the formation of polar bodies by nuclear subdivision in a nematode, Beneden (1883) was studying "Ascaris megalocephala" when he discovered the separation of halves of each of the chromosomes from the two parents and the mechanism of Mendelian heredity, and Boveri (1893) showed evidence for continuity of the germ plasm and that the soma may be regarded as a by-product without influence upon heredity. Caenorhabditis elegans is a widely used model species, initially for neural development, and then for genetics. WormBase collates research

neg: Planetesimal planetesimal as a general term to refer to many small Solar System bodies – such as asteroids and comets – which are left over from the formation process. A group of the world's leading planet formation experts decided at a conference in 2006 on the following definition of a planetesimal: A planetesimal is a solid object arising during the accumulation of planets whose internal strength is dominated by self-gravity and whose orbital dynamics is not significantly affected by gas drag. This corresponds to objects larger than approximately 1 km in the solar nebula. Bodies large enough not only to keep

neg: Trisynaptic circuit bodies are two clusters of cell bodies found at the ends of the posterior fibres of the fornix within the diencephalon. The mammillary bodies relay information from the hippocampal formation (via the fornix) to the thalamus (via the mammillothalamic tract). The mammillary bodies are integral parts of the limbic system and have been shown to be important in recollective memory. The thalamus is a bundle of nuclei located between the cerebral cortex and the midbrain. Many of the thalamic nuclei receive inputs from the hippocampal formation. The mammillothalamic tract relays information received from the mamillary bodies (via the fornix) and

neg: Polar overdominance who inherit this mutant allele from their father are more likely to show signs of obesity because the DLK1 gene is key in adipogenesis, or more simply the formation of fat cells. Polar overdominance Polar overdominance is a unique form of inheritance originally described in livestock, with relevant examples in humans and mice being discovered shortly after. The term polar is used to describe this type of overdominance because the phenotype of the heterozygote is more prevalent than the other genotypes. This polarity is shown as differential phenotype is only present in one of the heterozygote configurations when the recessive

neg: Meiosis cell, which enlarges to become an ovum. Therefore, in females each primary oocyte that undergoes meiosis results in one mature ovum and one or two polar bodies. Note that there are pauses during meiosis in females. Maturing oocytes are arrested in prophase I of meiosis I and lie dormant within a protective shell of somatic cells called the follicle. At the beginning of each menstrual cycle, FSH secretion from the anterior pituitary stimulates a few follicles to mature in a process known as folliculogenesis. During this process, the maturing oocytes resume meiosis and continue until metaphase II of meiosis II,

neg: Lanthanum aluminate-strontium titanate interface growth conditions, multiple mechanisms can coexist. A systematic study across a wide growth parameter space demonstrated different roles played by oxygen vacancy formation and the polar gating at different interfaces. An obvious difference between oxygen vacancies and polar gating in creating the interface conductivity is that the carriers from oxygen vacancies are thermally activated as the donor level of oxygen vacancies is usually separated from the SrTiO conduction band, consequently exhibiting the carrier freeze-out effect at low temperatures; in contrast, the carriers originating from the polar gating are transferred into the SrTiO conduction band (Ti 3d orbitals) and are therefore

neg: Glycerophospholipid step in this metabolism involves the addition or transfer of the fatty acid chains to the glycerol backbone to form the first intermediate, lysophosphatidic acid (LPA). LPA then becomes acylated to form the next intermediate phosphatidic acid (PA). PA can be dephosphorylated leading to the formation of diacylglycerol which is essential in the synthesis of phosphatidylcholine (PC). PC is one of the many species of glycerophospholipids. In a pathway called the Kennedy pathway, the polar heads are added to complete the formation of the entire structure consisting of the polar head regions, the two fatty acid chains and the phosphate

neg: Field desorption (M-H) ions are often produced in polar organics in the NI mode. The first three ionization mechanisms discussed above all have their analogues in NI-FD-MS. In field ionization, molecular anions (M ̇ ) can be generated. Anion attachment can also lead to the formation of negative ions for some molecules, for example, (M + Cl). Thermal desorption usually produces anion (A) and cluster ion (e.g. CA) for salts. Several different emitter configurations have been used for FD emitters, such as single tips, sharp blades and thin wires. Single metal tips can be made from etching wires either by periodically dipping

neg: Polar bear jail bodies are adapted to going without food for extended time. Dangerous bears are tranquilized when captured and are marked with a bright paint on the neck. Closer to the winter, when the ice in the Hudson bay has set, the bears are released. They are tranquilized again and transported by helicopter far from the town. Lately the jail was extended to 28 cells. Nevertheless, the inhabitants of Churchill have to be careful outside. The outskirts of the city are said to be visited by about a thousand polar bears in the summer. The reason is that with the ice gone

neg: Polyethylene as polyethylene. Polyethylene may either be modified in the polymerization by polar or non-polar comonomers or after polymerization through polymer-analogous reactions. Common polymer-analogous reactions are in case of polyethylene crosslinking, chlorination and sulfochlorination. In the low pressure process α-olefins (e.g. 1-butene or 1-hexene) may be added, which are incorporated in the polymer chain during polymerization. These copolymers introduce short side chains, thus crystallinity and density are reduced. As explained above, mechanical and thermal properties are changed thereby. In particular, PE-LLD is produced this way. Metallocene polyethylene (PE-M) is prepared by means of metallocene catalysts, usually including copolymers (z. B. ethene

neg: Chemical chaperone expression of protein in "Escherichia coli" often results in the formation of insoluble protein aggregates called inclusion bodies. These protein bodies require refolding "in vitro" once extracted from "E.coli" cells by strong detergent. Proteins are thought to unfold during the solubilization process, and subsequent removal of detergent by dilution of analysis allows their refolding. Both folding enhancers and aggregation suppressors are often employed during the removal of denaturant to facilitate folding to the native structure and to prevent aggregation. Folding enhancers assist protein to assume the native structure as soon as possible when the concentration of detergent is drastically decreased

neg: Jupiter trojan tholins, organic polymers formed by the Sun's radiation. The Jupiter trojans' densities (as measured by studying binaries or rotational lightcurves) vary from 0.8 to 2.5 g·cm. Jupiter trojans are thought to have been captured into their orbits during the early stages of the Solar System's formation or slightly later, during the migration of giant planets. The term "trojan" has come to be used more generally to refer to other small Solar System bodies with similar relationships to larger bodies: for example, there are both Mars trojans and Neptune trojans, and Saturn has trojan moons. NASA has announced the discovery of

neg: Reference ellipsoid aid of GPS and will therefore be geocentric, e.g., WGS 84. Reference ellipsoids are also useful for geodetic mapping of other planetary bodies including planets, their satellites, asteroids and comet nuclei. Some well observed bodies such as the Moon and Mars now have quite precise reference ellipsoids. For rigid-surface nearly-spherical bodies, which includes all the rocky planets and many moons, ellipsoids are defined in terms of the axis of rotation and the mean surface height excluding any atmosphere. Mars is actually egg shaped, where its north and south polar radii differ by approximately , however this difference is small enough

neg: Döhle bodies maturation during active granulocytopoiesis. Just like a left shift, the presence of toxic neutrophils suggests increased granulocytopoiesis. However, in a freshly prepared blood smear, the presence of vacuolation in addition to toxic neutrophils, reflects endotoxemia resulting in autolysis of neutrophils. This autodigestion is responsible for the cytoplasmic vacuolation. It is the single toxic change that does not result from the "manufacturing" process. Döhle bodies Döhle bodies are light blue-gray, oval, basophilic, leukocyte inclusions located in the peripheral cytoplasm of neutrophils. They measure 1-3 µm in diameter. Not much is known about their formation, but they are thought to be remnants

neg: International Code for Ships Operating in Polar Waters into effect only in 2017 for new ships and 2018 for existing ships On December 22, 2016 the Russian shuttle tanker "Shturman Albanov" became the first ship to be certified in compliance with the Polar Code. Many industry bodies and environmental groups termed the final draft Polar code of 2014 as "too weak" and "diluted". The pollution requirements in the arctic waters are even more lax than those in the Mediterranean sea, allowing ships to throw food waste overboard in arctic waters 12 miles from ice. The structural requirements too were found lax: for instance, being ice classed is not

neg: HD 113766 bodies up to 1 km in radius which are currently thought to be the basic building blocks of rocky planet formation. Comparison with current planetary formation theories suggests that the disk is in the early stages of terrestrial (rocky) planet formation. This can be also inferred by the presence of metals in the rocky material making up the disk. If planets had already formed the high density metals should have sunk to their cores during the molten stage of planet formation; a process known as planetary differentiation. While no water gas was found to be associated with the warm dust

neg: Climate of Buenos Aires at Buenos Aires. This is because as the cold air masses from the South Pacific High move over the Pacific Ocean and the Andes and reach the land south of 35S (where the Andes are shorter in height), anticyclogenesis leads to the formation of a strong high pressure system in the center of the country (at around 40S). This high pressure system brings cold and dry, polar continental air masses to Buenos Aires. Cold fronts are more common during winter than in summer as the South Atlantic and South Pacific highs are at their southernmost positions during summer, making it

neg: Polar body biopsy differentiate the first from the second polar body, or simultaneous biopsy if FISH is to be performed. In theory, molecular analysis of polar bodies may include epigenetic profiling in the near future. Several studies have suggested that polar body screening for aneuploidy may not be optimal. When the majority of errors occur in chromatids rather than entire chromosomes (a condition correlated with the age of the mother), screening only the first polar body will fail to detect a large percentage of defective eggs. As mentioned earlier, chromosomal abnormality in the first polar body can result in a healthy embryo, meaning

neg: Mars polar cap has a diameter of and a thickness of . The total volume of ice in the south polar cap plus the adjacent layered deposits has been estimated at 1.6 million cubic km. Both polar caps show spiral troughs, which recent analysis of SHARAD ice penetrating radar has shown are a result of katabatic winds that spiral due to the Coriolis Effect. The seasonal frosting of areas near the southern ice cap results in the formation of transparent 1-metre-thick slabs of dry ice above the ground. With the arrival of spring, sunlight warms the subsurface and pressure from subliming

neg: Ketone bodies Ketone bodies Ketone bodies are three water-soluble molecules (acetoacetate, beta-hydroxybutyrate, and their spontaneous breakdown product, acetone) containing the ketone group that are produced by the liver from fatty acids during periods of low food intake (fasting), carbohydrate restrictive diets, starvation, prolonged intense exercise, alcoholism or in untreated (or inadequately treated) type 1 diabetes mellitus. These ketone bodies are readily picked up by the extra-hepatic tissues (tissues outside the liver) and converted into acetyl-CoA which then enters the citric acid cycle and is oxidized in the mitochondria for energy. In the brain, ketone bodies are also used to make acetyl-CoA into

neg: Polar 3 for a Moroccan spy plane. All three of the "Polar 3"'s crew memberspilot Herbert Hampel (age 47), co-pilot Richard Möbius (also age 47) and mechanic Josef Schmid (age 28)were killed. "Polar 2", five minutes ahead of "Polar 3", escaped unharmed. The bodies of the "Polar 3" crew were eventually recovered five days later. The German government did not recognize Morocco's claim to Western Sahara at the time, remaining neutral in the conflict. They heavily criticized this incident. Polisario admitted to shooting down "Polar 3" but pointed ultimate blame at Morocco for the incident, claiming Morocco used Dornier 228s as spy

neg: Polar body biopsy that eggs may in fact be wasted as a result of the screening. Polar body testing will also be unable to detect post-zygotic errors in an oocyte. Because euploid polar bodies contain the same chromosomes as the oocyte, they can be used as a source of genetic material that is easily accessed without destroying the egg. This presents a research advantage by minimizing damage to the oocytes under investigation. Polar body biopsy is used mainly by two PGD groups in the USA and by groups in countries where cleavage-stage embryo selection is banned. Polar body biopsy Polar body biopsy is

neg: Van der Waals force forces dominate the interaction of non-polar molecules, and are often more significant than Keesom and Debye forces in polar molecules. London dispersion forces are also known as 'dispersion forces', 'London forces', or 'instantaneous dipole–induced dipole forces'. The strength of London dispersion forces is proportional to the polarizability of the molecule, which in turn depends on the total number of electrons and the area over which they are spread. Any connection between the strength of London dispersion forces and mass is coincidental. For macroscopic bodies with known volumes and numbers of atoms or molecules per unit volume, the total van der

neg: Pleurotolysin of the Equinatoxin Family (TC# 1.C.38). The aegerolysin family consists of several bacterial and eukaryotic aegerolysin-like proteins. It has been found that aegerolysin and ostreolysin are expressed during formation of primordia and fruiting bodies and possibly play a role in the initial phase of fungal fruiting. The bacterial members of this family are expressed during sporulation. Ostreolysin is cytolytic to various erythrocytes and tumor cells because of pore formation. Several members of the Aegerolysin family have been used as tools to detect and visualize ceramide phosphoethanolamine, a major sphingolipid in invertebrates but not in animals. It may be distantly related

neg: Canadian Coast Guard the Polar 8 class which would be used primarily for sovereignty patrols. However the proposed Polar 8 class was abandoned during the late 1980s as part of general government budget cuts; in their place a program of vessel modernizations was instituted. Additional budget cuts to CCG in the mid-1990s following a change in government saw many of CCG's older vessels built during the 1960s and 1970s retired. From its formation in 1962 until 1995, CCG was the responsibility of the Department of Transport. Both the department and CCG shared complementary responsibilities related to marine safety, whereby DOT had responsibility for

neg: Tricarbon monoxide though oxygen is 20 times more common than sulfur. The difference is due to the higher rate of formation and that CS is less polar. CO can be produced by heating Meldrum's acid. This also produces acetone, carbon monoxide and carbon dioxide. R. L. DeKock and W. Waltner were the first to identify CO by reacting atomic carbon with carbon monoxide in an argon matrix. They observed an infrared absorption line at 2241 cm. They produced carbon atoms by heating graphite inside a thin tantalum tube. M. E. Jacox photolysed CO in an argon matrix to produce CO with an

neg: Thunderstorm warm season over land has been noted across North America, Europe, and Asia, with a maximum in activity noted during the late afternoon and evening hours. Forms of MCS that develop in the tropics are found in use either the Intertropical Convergence Zone or monsoon troughs, generally within the warm season between spring and fall. More intense systems form over land than over water. One exception is that of lake-effect snow bands, which form due to cold air moving across relatively warm bodies of water, and occurs from fall through spring. Polar lows are a second special class of MCS.

neg: Polar bear months, particularly in North Canada, traveling farther inland. This may cause an increased reliance on terrestrial diets, such as goose eggs, waterfowl and caribou, as well as increased human–bear conflict. Polar bears accumulate high levels of persistent organic pollutants such as polychlorinated biphenyl (PCBs) and chlorinated pesticides. Due to their position at the top of the ecological pyramid, with a diet heavy in blubber in which halocarbons concentrate, their bodies are among the most contaminated of Arctic mammals. Halocarbons are known to be toxic to other animals, because they mimic hormone chemistry, and biomarkers such as immunoglobulin G and retinol

neg: Ketone bodies sometimes called nutritional ketosis, but the level of ketone body concentrations are on the order of whereas the pathological ketoacidosis is . The process of ketosis is currently being investigated for efficacy in ameliorating the symptoms of Alzheimer's disease. Ketone bodies Ketone bodies are three water-soluble molecules (acetoacetate, beta-hydroxybutyrate, and their spontaneous breakdown product, acetone) containing the ketone group that are produced by the liver from fatty acids during periods of low food intake (fasting), carbohydrate restrictive diets, starvation, prolonged intense exercise, alcoholism or in untreated (or inadequately treated) type 1 diabetes mellitus. These ketone bodies are readily picked up

neg: Aqueous normal-phase chromatography to HILIC phases that can have from 6–8 monolayers. In addition the substantial negative charge on the surface of hydride phases is the result of hydroxide ion adsorption from the solvent rather than silanols. An interesting feature of these phases is that both polar and nonpolar compounds can be retained over some range of mobile phase composition (organic/aqueous). The retention mechanism of polar compounds has recently been shown to be the result of the formation of a hydroxide layer on the surface of the silica hydride. Thus positively charged analytes are attracted to the negatively charged surface and other polar

neg: Martian polar ice caps volume of ice in the south polar cap plus the adjacent layered deposits has also been estimated at 1.6 million cubic km. Both polar caps show spiral troughs, which recent analysis of SHARAD ice penetrating radar has shown are a result of roughly perpendicular katabatic winds that spiral due to the Coriolis Effect. The seasonal frosting of some areas near the southern ice cap results in the formation of transparent 1 m thick slabs of dry ice above the ground. With the arrival of spring, sunlight warms the subsurface and pressure from subliming CO builds up under a slab, elevating

neg: Wetland summers are warm and winters are cold, but temperatures are not extreme. In a temperate zone wetland, such as one along the Gulf of Mexico, a typical temperature might be . Wetlands in the tropics are much warmer for a larger portion of the year. Wetlands on the Arabian Peninsula can reach temperatures exceeding and would therefore be subject to rapid evaporation. In northeastern Siberia, which has a polar climate, wetland temperatures can be as low as . Peatlands insulate the permafrost in subarctic regions, thus delaying or preventing thawing of permafrost during summer, as well as inducing the formation

neg: ANLN anillin couples the actomyosin cytoskeleton to microtubules by binding MgcRacGAP/CYK-4/RacGAP50C. Anillins have also been shown to organize the actomyosin cytoskeleton into syncytial structures observed in Drosophila embryos or C. elegans gonads. ANI-1 and ANI-2 (proteins homologous to anillin) are essential for embryonic viability in both organisms. ANI-1 is required for cortical ruffling, pseudocleavage, and all contractile events that occur in embryos prior to mitosis. ANI-1 is also crucial for segregation of polar bodies during meiosis. ANI-2 functions in the maintenance of the structure of the central core of the cytoplasm, the rachis, during oogenesis. ANI-2 ensures oocytes do not disconnect

neg: Mesoscale convective system maximum in activity noted during the late afternoon and evening hours. Forms of MCS that develop within the tropics use either the Intertropical Convergence Zone or monsoon troughs as a focus for their development, generally within the warm season between spring and fall. One exception is that of lake-effect snow bands, which form due to cold air moving across relatively warm bodies of water, and occurs from fall through spring. Polar lows are a second special class of MCS which form at high latitudes during the cold season. Once the parent MCS dies, later thunderstorm development can occur in connection

neg: Lactylate the production of analytical standards of the individual lactylate components. Due to differences in physical properties, oil does not readily mix with water. Many food and non-food systems require stabilization of mixtures of oil and water in order to prevent phase separation. Therefore, additives are used to provide stability. Lactylates are such additives. Lactylates are surface active and are therefore surfactants. Lactylates contain hydrophilic polar groups, which interact with water, and non-polar lipophilic groups, which interact with fats and oils. These interactions provide stability to an oil/water system resulting in the formation of an emulsion. Therefore, lactylates are often referred

neg: 1,3-Butadiene and other alkenes. When mixed with steam and briefly heated to very high temperatures (often over 900 °C), aliphatic hydrocarbons give up hydrogen to produce a complex mixture of unsaturated hydrocarbons, including butadiene. The quantity of butadiene produced depends on the hydrocarbons used as feed. Light feeds, such as ethane, give primarily ethylene when cracked, but heavier feeds favor the formation of heavier olefins, butadiene, and aromatic hydrocarbons. Butadiene is typically isolated from the other four-carbon hydrocarbons produced in steam cracking by extractive distillation using a polar aprotic solvent such as acetonitrile, N-methylpyrrolidone, furfural, or dimethylformamide, from which it is

neg: Polar body body biopsy can potentially be of lower costs, less harmful side-effects, and more sensitive in detecting abnormalities. The main advantage of the use of polar bodies in PGD is that they are not necessary for successful fertilisation or normal embryonic development, thus ensuring no deleterious effect for the embryo. One of the disadvantages of PB biopsy is that it only provides information about the maternal contribution to the embryo, which is why cases of autosomal dominant and X-linked disorders that are maternally transmitted can be diagnosed, and autosomal recessive disorders can only partially be diagnosed. Another drawback is the increased

neg: 2-Hydroxyethyl terephthalic acid 2-Hydroxyethyl terephthalic acid 2-Hydroxyethyl terephthalic acid is an organic compound with the formula HOCHOCCHCOH. It is the monoester of terephthalic acid and ethylene glycol. The compound is a precursor to poly(ethylene terephthalate) (PET), a polymer that is produced on a large scale industrially. 2-Hydroxyethyl terephthalic acid is a colorless solid that is soluble in water and polar organic solvents. Near neutral pH, 2-hydroxyethyl terephthalic acid converts to 2-hydroxyethyl terephthalate, HOCHOCCHCO. 2-Hydroxyethyl terephthalic acid is an intermediate in both the formation and hydrolysis of PET. It is produced on a massive scale as the first intermediate in certain routes to PET.

neg: Polynya Polar bears are known to be able to swim as far as 65 kilometres across open waters of a polynya. The presence of polynyas in McMurdo Sound in the Antarctic provides an ice-free area where penguins can feed, thus they are important for the survival of the Cape Royds penguin colony. Antarctic Bottom Water is the dense water with high salinity that exists in the abyssal layer of the Southern Ocean and it plays a major role in the global overturning circulation. Coastal Polynyas (Latent heat polynyas) are a source of AABW as brine rejection during the formation of sea

neg: Anoxic event from some commercial oil wells, are found on all major continents and this event seems similar in kind to the two major Cretaceous examples. The boundary between the Ordovician and Silurian periods is marked by repetitive periods of anoxia, interspersed with normal, oxic conditions. In addition, anoxic periods are found during the Silurian. These anoxic periods occurred at a time of low global temperatures (although levels were high), in the midst of a glaciation. Jeppsson (1990) proposes a mechanism whereby the temperature of polar waters determines the site of formation of downwelling water. If the high latitude waters are below

neg: Geology of Jersey in a matrix of 10 to 20% clay. The minerals contained are very diverse indicating a broad source area. Conglomerate, termed Association I from the upper parts of the fan, is found in lenticular bodies near St Peter's Valley, at Gargate Mill. The pebbles in the conglomerate are of multiple kinds of rock. The granite intrusions at the boundary of the formation have caused metamorphism and intrusion by dykes. In the L'Êtacq area, the metamorphism has produced spotted hornfels with a grey colour. The spots are darker, containing cordierite and biotite. At St. Ouën's Bay the metamorphosis of greywacke has

neg: Lake Harper on the former shores testify to the existence of a lake there. Other lakes nourished by the Mojave River are Lake Manix, the Cronese Lakes, Lake Mojave in the present day Soda Lake and Silver Lake basins and Lake Manly in present-day Death Valley; presently the river ends in Soda Lake after . The formation of these pluvial lakes depends on the southward shift of the polar jet stream during the ice ages. The highest shorelines are dated to 24,400 ± 2,190 and 25,000 ± 310 radiocarbon years ago; further dates are 40,460 ± 550 and 33,830 ± 340 calibrated

neg: Odontoblast saved by a simple restoration. In contrast, reparative dentin is secreted when the tooth has a poor prognosis. Teeth in the molluscan radula are also produced by cells termed "odontoblasts". Odontoblast In vertebrates, an odontoblast is a cell of neural crest origin that is part of the outer surface of the dental pulp, and whose biological function is dentinogenesis, which is the formation of dentin, the substance beneath the tooth enamel on the crown and the cementum on the root. Odontoblasts are large columnar cells, whose cell bodies are arranged along the interface between dentin and pulp, from the crown

neg: Polar body biopsy preimplantation genetic screening (PGS). Compared to a blastocyst biopsy, a polar body biopsy can potentially be of lower costs, less harmful side-effects, and more sensitive in detecting abnormalities. The first polar body is removed from the unfertilised oocyte, and the second PB from the zygote, shortly after fertilization. The biopsy and analysis of the first and second polar bodies can be completed before fertilization, which is the moment from which the zygote is generally considered an embryo and may become protected by law. By screening the first polar body for chromosomal anomalies, non-viable eggs can be reliably identified, though eggs

neg: Polar wander axis to its position of maximum inertia. The difference is that unlike Earth, the spinning top’s mass distribution is constant through its volume over time. Evidence for true polar wander has been observed from the study of large apparent polar wander datasets which, when corrected for the motion of the magnetic pole, display this polar wander. Modern polar wander can be evaluated from precise measurement using stars or satellite measurements, however filtering to remove the wobble of the Earth is required. The formation of supercontinents could initiate a faster polar wander. That is, because the supercontinent creates an extra mass

neg: Giant-impact hypothesis Alex N. Halliday in 2000 and has become accepted in the scientific community. According to modern theories of planet formation, Theia was part of a population of Mars-sized bodies that existed in the Solar System 4.5 billion years ago. One of the attractive features of the giant-impact hypothesis is that the formation of the Moon and Earth align; during the course of its formation, the Earth is thought to have experienced dozens of collisions with planet-sized bodies. The Moon-forming collision would have been only one such "giant impact" but certainly the last significant impactor event. The Late Heavy Bombardment by

neg: Aqueous two-phase system chemical industries. It is a common observation that when oil and water are poured into the same container, they separate into two phases or layers, because they are immiscible. In general, aqueous (or water-based) solutions, being polar, are immiscible with non-polar organic solvents (chloroform, toluene, hexane etc.) and form a two-phase system. However, in an ABS, both immiscible components are water-based. The formation of the distinct phases is affected by the pH, temperature and ionic strength of the two components, and separation occurs when the amount of a polymer present exceeds a certain limiting concentration (which is determined by the

neg: Hatcher Pass bodies of serpentinite are contained within the schist. West of Government Peak, the Arkose Ridge Formation lies to the south of the schist, the contact is a low-angle detachment fault. The Arkose Ridge Formation is unmetamorphosed but tilted and slightly folded, and consists of Tertiary (Late Paleocene to middle Eocene) sedimentary arkose, shale, sandstone, and conglomerate rocks that are clearly derived from the schists and intrusive rocks to the north. Locally, quartz diorite or gneiss bodies occur on the arkose-schist contact west of Government Peak. Minor basalt flows occur within the Arkose Ridge Formation. On Government Peak a 90 mya

neg: Mitosis the cell successfully passes through the metaphase checkpoint, it proceeds to anaphase. During "anaphase A", the cohesins that bind sister chromatids together are cleaved, forming two identical daughter chromosomes. Shortening of the kinetochore microtubules pulls the newly formed daughter chromosomes to opposite ends of the cell. During "anaphase B", polar microtubules push against each other, causing the cell to elongate. In late anaphase, chromosomes also reach their overall maximal condensation level, to help chromosome segregation and the re-formation of the nucleus. In most animal cells, anaphase A precedes anaphase B, but some vertebrate egg cells demonstrate the opposite order of

neg: Polar-ring galaxy were NGC 5128, NGC 5363, NGC 1947 and Cygnus A, while the polar-ring S0 galaxies NGC 2685 and NGC 4650A were at that time indicated as resulting from similar formation processes. Only some years later, when the first observations of the stellar and gas motion of polar-ring elliptical and S0 galaxies were possible with a better spectroscopic technology, the external origin of the gaseous rings was clarified. In addition to the best-known example, NGC 5128 (Cen A), a very regular polar ring elliptical, is NGC 5266 The SPRC is the Sloan Polar-Ring Catalogue, an atlas of 157 polar-ring galaxies. It

neg: Solvent effects be neglected. A comparison of S1 to S2 reactions is to the right. On the left is an S1 reaction coordinate diagram. Note the decrease in ΔG for the polar-solvent reaction conditions. This arises from the fact that polar solvents stabilize the formation of the carbocation intermediate to a greater extent than the non-polar-solvent conditions. This is apparent in the ΔE, ΔΔG. On the right is an S2 reaction coordinate diagram. Note the decreased ΔG for the non-polar-solvent reaction conditions. Polar solvents stabilize the reactants to a greater extent than the non-polar-solvent conditions by solvating the negative charge on the

neg: Geysers on Mars activity on Mars. Their characteristics, and the process of their formation, are still a matter of debate. These features are unique to the south polar region of Mars in an area informally called the 'cryptic region', at latitudes 60° to 80° south and longitudes 150°W to 310°W; this 1 meter deep carbon dioxide (CO) ice transition area—between the scarps of the thick polar ice layer and the permafrost—is where clusters of the apparent geyser systems are located. The seasonal frosting and defrosting of carbon dioxide ice results in the appearance of a number of features, such dark dune spots with

neg: Trimethylenemethane cycloaddition reactions with oxygen. Tetrahydrofuran (THF) at reflux is the most commonly employed solvent system, but photodissociation conditions at low temperature may also be used. Reactions employing polar MCPs are usually carried out in a polar solvent to facilitate formation of the TMM intermediate. Although rigorous exclusion of air and water is not required, it is generally preferred. For transition-metal catalyzed MCP reactions, the choice of catalyst and ligand system is key. Generally, phosphine or phosphite ligands are required in conjunction with a palladium(0) or nickel(0) source; the most common are Pd(dba) and Ni(cod). Tri(isopropyl)phosphine is the most common ligand used

neg: Rotating locomotion in living systems gradient set up by the cell's metabolism. (In species of the genus "Vibrio", there are two kinds of flagella, lateral and polar, and some are driven by a sodium ion pump rather than a proton pump.) Flagella are quite efficient, allowing bacteria to move at speeds of up to 60 cell lengths per second. The rotary motor at the base of the flagellum is similar in structure to ATP synthase. "Spirillum" bacteria have helical bodies with flagella at either end, and they spin about the central axis of their bodies as they move through the water. Archaea, a group of