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can experience increasing reproductive isolation that correlates directly with physical, geographical distance. This has been exemplified in models of ring species; however, it has been argued that ring species are a special case, representing reproductive isolation-by distance, and demonstrate parapatric speciation in...	{ "page_id": 334986, "title": "Allopatric speciation" }
pressures, leading to the rapid fixation of an allele within the descendant population. This gives rise to the potential for genetic incompatibilities to evolve. These incompatibilities cause reproductive isolation, giving rise to rapid speciation events.: 105–106 Models of peripatry are supported mostly by species dis...	{ "page_id": 334986, "title": "Allopatric speciation" }
A sympatric population may exist in low resolution, whereas viewed with a higher resolution (i.e. on a small, localized scale within the population) it is "microallopatric". Ben Fitzpatrick and colleagues contend that this original definition, "is misleading because it confuses geographical and ecological concepts". ==...	{ "page_id": 334986, "title": "Allopatric speciation" }
pairs of related species share a range, they are distributed in abutting patterns, with borders exhibiting zones of hybridization. In regions where geographic isolation is doubtful, species do not exhibit sister pairs. Correlation of genetic differences between an array of distantly related species that correspond to k...	{ "page_id": 334986, "title": "Allopatric speciation" }
rodents. The pattern indicates repeated vicariant speciation events among these groups. It is thought that rivers may play a role as the geographic barriers to Charis,: 97 not unlike the river barrier hypothesis used to explain the high rates of diversity in the Amazon basin—though this hypothesis has been disputed. Di...	{ "page_id": 334986, "title": "Allopatric speciation" }
towards an older and more complex emergence of the Isthmus, with fossil and extant species dispersal (part of the American biotic interchange) occurring in three major pulses, to and from North and South America. Further, the changes in terrestrial biotic distributions of both continents such as with Eciton army ants s...	{ "page_id": 334986, "title": "Allopatric speciation" }
subsequent retreat caused speciation in many boreal forest birds, such as with North American sapsuckers (Yellow-bellied, Red-naped, and Red-breasted); the warblers in the genus Setophaga (S. townsendii, S. occidentalis, and S. virens), Oreothlypis (O. virginiae, O. ridgwayi, and O. ruficapilla), and Oporornis (O. tolm...	{ "page_id": 334986, "title": "Allopatric speciation" }
(genus Astrapia). Red-shafted and yellow-shafted flickers; black-headed grosbeaks and rose-breasted grosbeaks; Baltimore orioles and Bullock's orioles; and the lazuli and indigo buntings. All of these species pairs connect at zones of hybridization that correspond with major geographic barriers.: 97–99 Dugesia flatworm...	{ "page_id": 334986, "title": "Allopatric speciation" }
C} represent homogametic matings. A {\displaystyle A} and B {\displaystyle B} is one population and D {\displaystyle D} and C {\displaystyle C} is the second population. A negative value of Y {\displaystyle Y} denotes negative assortive mating, a positive value denotes positive assortive mating (i. e. expressing reprod...	{ "page_id": 334986, "title": "Allopatric speciation" }
(given as a range). Some studies provide a duration in which the experiment was conducted. The "Selection type" column indicates if the study modeled vicariant or peripatric speciation (this may not be explicitly). Direct selection refers to selection imposed to promote reproductive isolation whereas indirect selection...	{ "page_id": 334986, "title": "Allopatric speciation" }
F. J. Sulloway contends that Darwin's position on speciation was "misleading" at the least and may have later misinformed Wagner and David Starr Jordan into believing that Darwin viewed sympatric speciation as the most important mode of speciation.: 83 Nevertheless, Darwin never fully accepted Wagner's concept of geogr...	{ "page_id": 334986, "title": "Allopatric speciation" }
form of speciation taking place in nature.: 84 However, this is not without controversy, as both parapatric and sympatric speciation are both considered tenable modes of speciation that occur in nature. Some researchers even consider there to be a bias in reporting of positive allopatric speciation events, and in one s...	{ "page_id": 334986, "title": "Allopatric speciation" }
groups. Biotechnological advances have allowed for large scale, multi-locus genome comparisons (such as with the possible allopatric speciation event that occurred between ancestral humans and chimpanzees), linking species' evolutionary history with ecology and clarifying phylogenetic patterns. == References == == Furt...	{ "page_id": 334986, "title": "Allopatric speciation" }
Septate junctions are intercellular junctions found in invertebrate epithelial cells, appearing as ladder-like structures under electron microscopy. They are thought to provide structural strength and a barrier to solute diffusion through the intercellular space. They are considered somewhat analogous to the (vertebrat...	{ "page_id": 38149258, "title": "Septate junction" }
== Function == There are several functions of septate junctions. Pleated SJs(pSJs) play roles in development and cell signaling. Form the mechanical link between cells which can densely pack the epithelial sheaths. Intermediate the adjacent cells interaction. Prevent the free diffusion of water and solutes among adjace...	{ "page_id": 38149258, "title": "Septate junction" }
The characterization of nanoparticles is a branch of nanometrology that deals with the characterization, or measurement, of the physical and chemical properties of nanoparticles.,. Nanoparticles measure less than 100 nanometers in at least one of their external dimensions, and are often engineered for their unique prop...	{ "page_id": 54992011, "title": "Characterization of nanoparticles" }
properties of nanoparticles are sensitive to small variations in these properties, which has implications for process control in their industrial use. These properties also influence the health effects of exposure to nanoparticles of a given composition. An additional challenge is that sampling and laboratory procedure...	{ "page_id": 54992011, "title": "Characterization of nanoparticles" }
classes of nanoparticles to characterize concentration, size, and shape. Semiconductor quantum dots are fluorescent and metal nanoparticles exhibit surface plasmon absorbances, making both amenable to ultraviolet–visible spectroscopy. Infrared, nuclear magnetic resonance, and X-ray spectroscopy are also used with nanop...	{ "page_id": 54992011, "title": "Characterization of nanoparticles" }
nanoparticle tracking analysis, particle tracking velocimetry, size exclusion chromatography, centrifugal sedimentation, and atomic force microscopy. For dry materials, techniques for measuring size include electron microscopy, atomic force microscopy, and X-ray diffraction. Back-calculation from surface area measureme...	{ "page_id": 54992011, "title": "Characterization of nanoparticles" }
influences dispersion, functionality, and toxicity, and has similar considerations as size measurements. Evaluation of morphology requires direct visualization of the particles through techniques like scanning electron microscopy, transmission electron microscopy, and atomic force microscopy. Several metrics can be use...	{ "page_id": 54992011, "title": "Characterization of nanoparticles" }
normalized to mass or volume. Different methods measure different aspects of surface area. Direct measurement of nanoparticle surface area utilizes adsorption of an inert gas such as nitrogen or krypton under varying conditions of pressure to form a monolayer of gas coverage. The number of gas molecules needed to form ...	{ "page_id": 54992011, "title": "Characterization of nanoparticles" }
Multiple techniques are available to characterize nanoparticle surface chemistry. X-ray photoelectron spectroscopy and Auger electron spectroscopy are well-suited to characterizing a thicker surface layer of 1–5 nm. Secondary ion mass spectroscopy is more useful to characterize just the top few angstroms (10 angstroms ...	{ "page_id": 54992011, "title": "Characterization of nanoparticles" }
of the degree to which material dissolves from a nanoparticle to enter solution. Material dissolved as part of a solubiity test can be quantified using atomic absorption spectroscopy, inductively coupled plasma optical emission spectroscopy, and inductively coupled plasma mass spectroscopy, with the last being generall...	{ "page_id": 54992011, "title": "Characterization of nanoparticles" }
tolerances for uniformity and reproducibility, and require different approaches to characterization. For example, nanocomposite materials may be tolerant of a broad distribution of nanoparticle properties. By contrast, characterization is especially important for nanomedicines, as their efficacy and safety depends stro...	{ "page_id": 54992011, "title": "Characterization of nanoparticles" }
the tissue itself can interfere with the measurements. === Exposure assessment === Exposure assessment is a set of methods used to monitor contaminant release and exposures to workers and mitigate the health and safety hazards of nanomaterials in workplaces where they are handled. For engineered nanoparticles, the asse...	{ "page_id": 54992011, "title": "Characterization of nanoparticles" }
is free or contained within a matrix. Hazard identification and characterization can then be performed based on a holistic assessment of the integrated filter samples. In addition, field-portable direct reading instruments can be used for continuous recording of normal fluctuations in particle count, size distribution,...	{ "page_id": 54992011, "title": "Characterization of nanoparticles" }
Animal and cell-culture studies have shown that size and shape may be two major factors in their toxicological effects. Surface area and surface chemistry also appear to be more important than mass concentration. NIOSH has determined non-regulatory recommended exposure limits (RELs) of 1.0 μg/m3 for carbon nanotubes an...	{ "page_id": 54992011, "title": "Characterization of nanoparticles" }
and dissolved matter. Reference materials of nanoparticles often have a shorter validity period than other materials. Those in powder form are more stable than those provided in suspensions, but the process of dispersing the powder increases uncertainty in its metrics. Reference nanoparticles are produced by the U.S. N...	{ "page_id": 54992011, "title": "Characterization of nanoparticles" }
Bromine fluoride may refer to several compounds with the elements bromine and fluorine: Bromine monofluoride, BrF Bromine trifluoride, BrF3 Bromine pentafluoride, BrF5	{ "page_id": 45423757, "title": "Bromine fluoride" }
In celestial mechanics, a central configuration is a system of point masses with the property that each mass is pulled by the combined gravitational force of the system directly towards the center of mass, with acceleration proportional to its distance from the center. Central configurations are studied in n-body probl...	{ "page_id": 62528650, "title": "Central configuration" }
moving under Newtonian gravitation that all collide at a single point in time and space will approximate a central configuration, in the limit as time tends to the collision time. Similarly, a system of particles that eventually all escape each other at exactly the escape velocity will approximate a central configurati...	{ "page_id": 62528650, "title": "Central configuration" }
of the n!/2 linear orderings (up to reversal of the ordering) of the points on a line. For every set of n point masses, and every dimension less than n, there exists at least one central configuration of that dimension. For almost all n-tuples of masses there are finitely many "Dziobek" configurations that span exactly...	{ "page_id": 62528650, "title": "Central configuration" }
any desired number of lines, number of circles, and profile of the masses on each concentric circle of a spiderweb central configuration, it is possible to find a spiderweb central configuration matching those parameters. One can similarly obtain central configurations for families of nested Platonic solids, or more ge...	{ "page_id": 62528650, "title": "Central configuration" }
Sperm thermotaxis is a form of sperm guidance, in which sperm cells (spermatozoa) actively change their swimming direction according to a temperature gradient, swimming up the gradient. Thus far this process has been discovered in mammals only. == Background == The discovery of mammalian sperm chemotaxis and the realiz...	{ "page_id": 48503953, "title": "Sperm thermotaxis" }
Since temperature affects almost every process, much attention has been devoted to the question of whether the measurements, mentioned just above, truly demonstrate thermotaxis or whether they reflect another temperature-dependent process. The most pronounced effect of temperature in liquid is convection, which raised ...	{ "page_id": 48503953, "title": "Sperm thermotaxis" }
the gradient direction. When they happen to swim down the gradient, they turn again and again until their swimming direction is again up the gradient. == Temperature sensing == The response of spermatozoa to temporal temperature changes even when the temperature is kept constant spatially suggests that, as in the case ...	{ "page_id": 48503953, "title": "Sperm thermotaxis" }
phosphodiesterase. Blocking both pathways fully inhibits sperm thermotaxis. == References == == External links == Semenax Clinical Study Results	{ "page_id": 48503953, "title": "Sperm thermotaxis" }
Endodermic evagination relates to the inner germ layers of cells of the very early embryo, from which is formed the lining of the digestive tract, of other internal organs, and of certain glands, implies the extension of a layer of body tissue to form a pouch, or the turning inside out (protrusion) of some body part or...	{ "page_id": 45358225, "title": "Endodermic evagination" }
Several forms of biochemistry are agreed to be scientifically viable but are not proven to exist at this time. The kinds of living organisms currently known on Earth all use carbon compounds for basic structural and metabolic functions, water as a solvent, and DNA or RNA to define and control their form. If life exists...	{ "page_id": 7316, "title": "Hypothetical types of biochemistry" }
known Earth-based life, amino acids are almost universally of the L form and sugars are of the D form. Molecules using D amino acids or L sugars may be possible; molecules of such a chirality, however, would be incompatible with organisms using the opposing chirality molecules. Amino acids whose chirality is opposite t...	{ "page_id": 7316, "title": "Hypothetical types of biochemistry" }
Horowitz devised the experiments to determine whether life might exist on Mars that were carried out by the Viking Lander of 1976, the first U.S. mission to successfully land a probe on the surface of Mars. Horowitz argued that the great versatility of the carbon atom makes it the element most likely to provide solutio...	{ "page_id": 7316, "title": "Hypothetical types of biochemistry" }
water, and long-chain silanes spontaneously decompose. Consequently, most terrestrial silicon is "locked up" in silica, and not a wide variety of biogenic precursors. Silicones, which alternate between silicon and oxygen atoms, are much more stable than silanes, and may even be more stable than the equivalent hydrocarb...	{ "page_id": 7316, "title": "Hypothetical types of biochemistry" }
The Cronin group at Glasgow University reported self-assembly of tungsten polyoxometalates into cell-like spheres. By modifying their metal oxide content, the spheres can acquire holes that act as porous membrane, selectively allowing chemicals in and out of the sphere according to size. Sulfur is also able to form lon...	{ "page_id": 7316, "title": "Hypothetical types of biochemistry" }
of Mono Lake in eastern California, can employ such 'arsenic DNA' when cultured without phosphorus. They proposed that the bacterium may employ high levels of poly-β-hydroxybutyrate or other means to reduce the effective concentration of water and stabilize its arsenate esters. This claim was heavily criticized almost ...	{ "page_id": 7316, "title": "Hypothetical types of biochemistry" }
himself as both a carbon chauvinist and a water chauvinist; however, on another occasion he said that he was a carbon chauvinist but "not that much of a water chauvinist". He speculated on hydrocarbons,: 11 hydrofluoric acid, and ammonia as possible alternatives to water. Some of the properties of water that are import...	{ "page_id": 7316, "title": "Hypothetical types of biochemistry" }
(or solid), greatly aiding the evolution of aquatic life. A large heat of vaporization leading to stable lakes and oceans. The ability to dissolve a wide variety of compounds. The solid (ice) has lower density than the liquid, so ice floats on the liquid. This is why bodies of water freeze over but do not freeze solid ...	{ "page_id": 7316, "title": "Hypothetical types of biochemistry" }
(91 atm) of pressure, it can indeed exist in liquid form over a wide temperature range. === Ammonia === The ammonia molecule (NH3), like the water molecule, is abundant in the universe, being a compound of hydrogen (the simplest and most common element) with another very common element, nitrogen. The possible role of l...	{ "page_id": 7316, "title": "Hypothetical types of biochemistry" }
as a basis for life. The hydrogen bonds between ammonia molecules are weaker than those in water, causing ammonia's heat of vaporization to be half that of water, its surface tension to be a third, and reducing its ability to concentrate non-polar molecules through a hydrophobic effect. Gerald Feinberg and Robert Shapi...	{ "page_id": 7316, "title": "Hypothetical types of biochemistry" }
surface of Saturn's largest moon Titan. === Methane and other hydrocarbons === Methane (CH4) is a simple hydrocarbon: that is, a compound of two of the most common elements in the cosmos: hydrogen and carbon. It has a cosmic abundance comparable with ammonia. Hydrocarbons could act as a solvent over a wide range of tem...	{ "page_id": 7316, "title": "Hypothetical types of biochemistry" }
of molecular hydrogen in the upper atmospheric layers of Titan compared to the lower layers, arguing for a downward diffusion at a rate of roughly 1025 molecules per second and disappearance of hydrogen near Titan's surface. As Strobel noted, his findings were in line with the effects Chris McKay had predicted if metha...	{ "page_id": 7316, "title": "Hypothetical types of biochemistry" }
boiling point is 292.69 K (19.54 °C); the difference between the two is a little more than 100 K. HF also makes hydrogen bonds with its neighbor molecules, as do water and ammonia. It has been considered as a possible solvent for life by scientists such as Peter Sneath and Carl Sagan. HF is dangerous to the systems of ...	{ "page_id": 7316, "title": "Hypothetical types of biochemistry" }
temperature range where it is liquid. However, its melting point is 1,600 to 1,725 °C (2,912 to 3,137 °F), so it would be impossible to make organic compounds in that temperature, because all of them would decompose. Silicates are similar to silicon dioxide and some have lower melting points than silica. Feinberg and S...	{ "page_id": 7316, "title": "Hypothetical types of biochemistry" }
"super-Venus"-type planets with dense high-pressure atmospheres may be common. == Other speculations == === Non-green photosynthesizers === Physicists have noted that, although photosynthesis on Earth generally involves green plants, a variety of other-colored plants could also support photosynthesis, essential for mos...	{ "page_id": 7316, "title": "Hypothetical types of biochemistry" }
view, most of them are Alanine-derivatives particularly suitable for the construction of α-helices and β-sheets – basic secondary structural elements of modern proteins. Direct evidence of this is an experimental procedure in molecular biology known as alanine scanning. A hypothetical "Proline World" would create a pos...	{ "page_id": 7316, "title": "Hypothetical types of biochemistry" }
energy output, the luminosity would also fall. For this reason, it is thought that such life might exist inside stars observed to be cooling faster or dimmer than current cosmological models predict. === Life on a neutron star === Frank Drake suggested in 1973 that intelligent life could inhabit neutron stars. Physical...	{ "page_id": 7316, "title": "Hypothetical types of biochemistry" }
Screw theory is the algebraic calculation of pairs of vectors, also known as dual vectors – such as angular and linear velocity, or forces and moments – that arise in the kinematics and dynamics of rigid bodies. Screw theory provides a mathematical formulation for the geometry of lines which is central to rigid body dy...	{ "page_id": 1318037, "title": "Screw theory" }
this line, and form a pair of vectors called a screw. For comparison, the six parameters that define a spatial displacement can also be given by three Euler angles that define the rotation and the three components of the translation vector. === Screw === A screw is a six-dimensional vector constructed from a pair of th...	{ "page_id": 1318037, "title": "Screw theory" }
has zero pitch. A torque, on the other hand, is a pure moment that is not bound to a line in space and is an infinite pitch screw. The ratio of these two magnitudes defines the pitch of the screw. == Algebra of screws == Let a screw be an ordered pair S = ( S , V ) , {\displaystyle {\mathsf {S}}=(\mathbf {S} ,\mathbf {...	{ "page_id": 1318037, "title": "Screw theory" }
S , V ) × ( T , W ) = ( S × T , S × W + V × T ) , {\displaystyle {\mathsf {S}}\times {\mathsf {T}}=(\mathbf {S} ,\mathbf {V} )\times (\mathbf {T} ,\mathbf {W} )=(\mathbf {S} \times \mathbf {T} ,\,\,\mathbf {S} \times \mathbf {W} +\mathbf {V} \times \mathbf {T} ),} which is a screw. The dot and cross products of screws ...	{ "page_id": 1318037, "title": "Screw theory" }
and ẑ = (φ, d) is the dual angle between these axes, then S × T = \| S \| \| T \| sin ⁡ z ^ N . {\displaystyle {\mathsf {S}}\times {\mathsf {T}}=\left\|{\mathsf {S}}\right\|\left\|{\mathsf {T}}\right\|\sin {\hat {\mathsf {z}}}{\mathsf {N}}.} == Wrench == A common example of a screw is the wrench associated with a force acting ...	{ "page_id": 1318037, "title": "Screw theory" }
is a rotation matrix and d is a translation vector. This causes a point p that is fixed in moving body coordinates to trace a curve P(t) in the fixed frame given by P ( t ) = [ A ( t ) ] p + d ( t ) . {\displaystyle \mathbf {P} (t)=[A(t)]\mathbf {p} +\mathbf {d} (t).} The velocity of P is V P ( t ) = [ d A ( t ) d t ] ...	{ "page_id": 1318037, "title": "Screw theory" }
ω ) , {\displaystyle {\mathsf {L}}=(\omega ,\mathbf {d} \times \omega ),} and (ii) when [Ω] = 0, that is the body does not rotate but only slides in the direction v, then the twist is a pure slide given by T = ( 0 , v ) . {\displaystyle {\mathsf {T}}=(0,\mathbf {v} ).} === Revolute joints === For a revolute joint, let ...	{ "page_id": 1318037, "title": "Screw theory" }
] ( p × q ) + d × [ A ] ( q − p ) ) {\displaystyle {\mathsf {Q}}=(\mathbf {Q} -\mathbf {P} ,\mathbf {P} \times \mathbf {Q} )=([A](\mathbf {q} -\mathbf {p} ),[A](\mathbf {p} \times \mathbf {q} )+\mathbf {d} \times [A](\mathbf {q} -\mathbf {p} ))} Thus, a spatial displacement defines a transformation for Plücker coordina...	{ "page_id": 1318037, "title": "Screw theory" }
= [ A ( t ) d ( t ) 0 1 ] { p 1 } . {\displaystyle {\textbf {P}}(t)=[T(t)]{\textbf {p}}={\begin{Bmatrix}{\textbf {P}}\\1\end{Bmatrix}}={\begin{bmatrix}A(t)&{\textbf {d}}(t)\\0&1\end{bmatrix}}{\begin{Bmatrix}{\textbf {p}}\\1\end{Bmatrix}}.} This notation does not distinguish between P = (X, Y, Z, 1), and P = (X, Y, Z), ...	{ "page_id": 1318037, "title": "Screw theory" }
( t ) ] = [ S ] [ T ( t ) ] , {\displaystyle [{\dot {T}}(t)]=[S][T(t)],} and ask for the movement [T(t)] that has a constant twist matrix [S]. The solution is the matrix exponential [ T ( t ) ] = e [ S ] t . {\displaystyle [T(t)]=e^{[S]t}.} This formulation can be generalized such that given an initial configuration g(...	{ "page_id": 1318037, "title": "Screw theory" }
and under the translation (1 + εr)(1 + εs) = 1 + ε(r + s) for any vector quaternions r and s. F is a 3-flat in the eight-dimensional space of dual quaternions. This 3-flat F represents space, and the homography constructed, restricted to F, is a screw displacement of space. Let a be half the angle of the desired turn a...	{ "page_id": 1318037, "title": "Screw theory" }
r, s ∈ H. These six parameters generate a subgroup of the units, the unit sphere. Of course it includes F and the 3-sphere of versors. == Work of forces acting on a rigid body == Consider the set of forces F1, F2 ... Fn act on the points X1, X2 ... Xn in a rigid body. The trajectories of Xi, i = 1,...,n are defined by ...	{ "page_id": 1318037, "title": "Screw theory" }
{\omega }}\times (\mathbf {X} _{i}-\mathbf {d} )+\mathbf {v} )\delta t.} Expand this equation and collect coefficients of ω and v to obtain δ W = ( ∑ i = 1 n F i ) ⋅ d × ω → δ t + ( ∑ i = 1 n F i ) ⋅ v δ t + ( ∑ i = 1 n X i × F i ) ⋅ ω → δ t = ( ∑ i = 1 n F i ) ⋅ ( v + d × ω → ) δ t + ( ∑ i = 1 n X i × F i ) ⋅ ω → δ t ...	{ "page_id": 1318037, "title": "Screw theory" }
)\delta t.} The 6×6 matrix [Π] is used to simplify the calculation of work using screws, so that δ W = ( W ⋅ T ∘ + W ∘ ⋅ T ) δ t = W [ Π ] T δ t , {\displaystyle \delta W=(\mathbf {W} \cdot \mathbf {T} ^{\circ }+\mathbf {W} ^{\circ }\cdot \mathbf {T} )\delta t={\mathsf {W}}[\Pi ]{\mathsf {T}}\delta t,} where [ Π ] = [ ...	{ "page_id": 1318037, "title": "Screw theory" }
1876 for application in kinematics and statics of mechanisms (rigid body mechanics). Felix Klein saw screw theory as an application of elliptic geometry and his Erlangen Program. He also worked out elliptic geometry, and a fresh view of Euclidean geometry, with the Cayley–Klein metric. The use of a symmetric matrix for...	{ "page_id": 1318037, "title": "Screw theory" }
In fluid mechanics, displacement occurs when an object is largely immersed in a fluid, pushing it out of the way and taking its place. The volume of the fluid displaced can then be measured, and from this, the volume of the immersed object can be deduced: the volume of the immersed object will be exactly equal to the v...	{ "page_id": 859285, "title": "Displacement (fluid)" }
the object, which is the same as the volume of the suspended object times the density of the liquid. The concept of Archimedes' principle is that an object immersed in a fluid is buoyed up by a force equal to the weight of the fluid displaced by the object. The weight of the displaced fluid can be found mathematically....	{ "page_id": 859285, "title": "Displacement (fluid)" }
Haplogroup D-Z27276 also known as Haplogroup D1a1 is a Y-chromosome haplogroup. It is one of two branches of Haplogroup D1, one of the descendants of Haplogroup D. The other is D-M55 which is only found in Japan. This group is found in about 46.6% Tibetan people. It branched off D-M55 35,000-40,000 years before present...	{ "page_id": 55385240, "title": "Haplogroup D-Z27276" }
Foodborne illness (also known as foodborne disease and food poisoning) is any illness resulting from the contamination of food by pathogenic bacteria, viruses, or parasites, as well as prions (the agents of mad cow disease), and toxins such as aflatoxins in peanuts, poisonous mushrooms, and various species of beans tha...	{ "page_id": 531611, "title": "Foodborne illness" }
There is a consensus in the public health community that regular hand-washing is one of the most effective defenses against the spread of foodborne illness. The action of monitoring food to ensure that it will not cause foodborne illness is known as food safety. === Bacteria === Bacteria are a common cause of foodborne...	{ "page_id": 531611, "title": "Foodborne illness" }
Staphylococcus aureus Streptococcus Vibrio cholerae, including O1 and non-O1 Vibrio parahaemolyticus Vibrio vulnificus Yersinia enterocolitica and Yersinia pseudotuberculosis Less common bacterial agents: Brucella spp. Corynebacterium ulcerans Coxiella burnetii or Q fever Plesiomonas shigelloides ==== Emerging foodborn...	{ "page_id": 531611, "title": "Foodborne illness" }
however, are not destroyed by heat treatment. Techniques that help prevent food borne illness in the kitchen are hand washing, rinsing produce, preventing cross-contamination, proper storage, and maintaining cooking temperatures. In general, freezing or refrigerating prevents virtually all bacteria from growing, and he...	{ "page_id": 531611, "title": "Foodborne illness" }
humans are the main cause of contamination as a substantial percentage of humans are persistent carriers of S. aureus. The CDC has estimated about 240,000 cases per year in the United States. Clostridium botulinum Clostridium perfringens Bacillus cereus The rare but potentially deadly disease botulism occurs when the a...	{ "page_id": 531611, "title": "Foodborne illness" }
to alimentary toxic aleukia (ALA). In Kenya, mycotoxins led to the death of 125 people in 2004, after consumption of contaminated grains. In animals, mycotoxicosis targets organ systems such as the liver and digestive system. Other effects can include reduced productivity and suppression of the immune system, thus pre-...	{ "page_id": 531611, "title": "Foodborne illness" }
FDA and the EC have regulated the content levels of toxins in food and animal feed. Fusaric acid Fusarochromanone Kojic acid Lolitrem alkaloids Moniliformin 3-Nitropropionic acid Nivalenol Ochratoxins – In Australia, The Limit of Reporting (LOR) level for ochratoxin A (OTA) analyses in 20th Australian Total Diet Survey...	{ "page_id": 531611, "title": "Foodborne illness" }
of cases are viral and noroviruses are the most common foodborne illness, causing 57% of outbreaks in 2004. Foodborne viral infection are usually of intermediate (1–3 days) incubation period, causing illnesses which are self-limited in otherwise healthy individuals; they are similar to the bacterial forms described abo...	{ "page_id": 531611, "title": "Foodborne illness" }
Shellfish toxin, including paralytic shellfish poisoning, diarrhetic shellfish poisoning, neurotoxic shellfish poisoning, amnesic shellfish poisoning and ciguatera fish poisoning Scombrotoxin Solanine (green potato poisoning) Tetrodotoxin (fugu fish poisoning) Tremetol (milk sickness stemming from a cow that ate white ...	{ "page_id": 531611, "title": "Foodborne illness" }
over 150 people in Chicago were hospitalized with ptomaine poisoning, apparently from rice pudding served by a restaurant chain. == Mechanism == === Incubation period === The delay between the consumption of contaminated food and the appearance of the first symptoms of illness is called the incubation period. This rang...	{ "page_id": 531611, "title": "Foodborne illness" }
minimum infectious dose; for example, Shigella sonnei has a low estimated minimum dose of < 500 colony-forming units (CFU) while Staphylococcus aureus has a relatively high estimate. Importantly, prior exposure to pathogens can significantly increase an individual's tolerance to subsequent exposures. Locals in a region...	{ "page_id": 531611, "title": "Foodborne illness" }
to foodborne disease. The World Health Organization has issued recommendations for the preparation, use and storage of prepared formulas. Breastfeeding remains the best preventive measure for protection from foodborne infections in infants. === United States === A CDC report for the period 2017–2019 found that 41% of o...	{ "page_id": 531611, "title": "Foodborne illness" }
have contracted their infections from food). === Australia === A study by the Australian National University published in 2022 for Food Standards Australia New Zealand estimated there are 4.67 million cases of food poisoning in Australia each year that result in 47,900 hospitalisations, 38 deaths and a cost to the econ...	{ "page_id": 531611, "title": "Foodborne illness" }
proportion of episodes due to food to the incidence of gastroenteritis circa 2000, there were an estimated 4.3 million (90% CrI: 2.2–7.3 million) episodes of foodborne gastroenteritis circa 2000, although credible intervals overlap with 2010. Taking into account changes in population size, applying these equivalent met...	{ "page_id": 531611, "title": "Foodborne illness" }
by local health jurisdictions and is inconsistent from district to district. It is estimated that 1–2% of outbreaks are detected. == Society and culture == === United Kingdom === In Aberdeen, in 1964, a large-scale (>400 cases) outbreak of typhoid occurred, caused by contaminated corned beef which had been imported fro...	{ "page_id": 531611, "title": "Foodborne illness" }
through media (TV cookery programmes) and advertisement. She points to the examples set by Scandinavian societies. === United States === In 2001, the Center for Science in the Public Interest petitioned the United States Department of Agriculture to require meat packers to remove spinal cords before processing cattle c...	{ "page_id": 531611, "title": "Foodborne illness" }
methods of risk analysis. These methods provide efficient, science-based tools to improve food safety, thereby benefiting both public health and economic development. === International Food Safety Authorities Network (INFOSAN) === The International Food Safety Authorities Network (INFOSAN) is a joint program of the WHO...	{ "page_id": 531611, "title": "Foodborne illness" }
tool concluding that Taenia solium was the most relevant, followed by Echinococcus granulosus, Echinococcus multilocularis, and Toxoplasma gondii. The same method was used regionally to rank the most important foodborne parasites in Europe ranking Echinococcus multilocularis of highest relevance, followed by Toxoplasma...	{ "page_id": 531611, "title": "Foodborne illness" }
NSW Food Authority Food safety and foodborne illness, WHO, Fact sheet N°237, revised January 2002 UK Health protection Agency US PulseNet Food poisoning from NHS Direct Online Food Safety Network hosted at the University of Guelph, Canada. Food Standard Agency website	{ "page_id": 531611, "title": "Foodborne illness" }
Paraffin oxidation is a historical industrial process for the production of synthetic fatty acids. The fatty acids are further processed to consumer products such as soaps and fats as well as to lubricating greases for technical applications. Coal slack wax, a saturated, high molecular weight hydrocarbon mixture and by...	{ "page_id": 45620379, "title": "Paraffin oxidation" }
oxidation process C5-C9: Reduced to alcohols C9-C11: Froth flotation C9-C16: Reacted with glycerol to produce edible fats such as synthetic margarine C10-C18: Soap C18-C24: Metallic soap, lithium soap, etc. == Mechanism == The first explanation for oxidation mechanism was given by the peroxide theory, developed by Alex...	{ "page_id": 45620379, "title": "Paraffin oxidation" }
In machine learning (ML), feature learning or representation learning is a set of techniques that allow a system to automatically discover the representations needed for feature detection or classification from raw data. This replaces manual feature engineering and allows a machine to both learn the features and use th...	{ "page_id": 38870173, "title": "Feature learning" }
data label allows the system to compute an error term, the degree to which the system fails to produce the label, which can then be used as feedback to correct the learning process (reduce/minimize the error). Approaches include: === Supervised dictionary learning === Dictionary learning develops a set (dictionary) of ...	{ "page_id": 38870173, "title": "Feature learning" }
parameterized by the weights. With appropriately defined network functions, various learning tasks can be performed by minimizing a cost function over the network function (weights). Multilayer neural networks can be used to perform feature learning, since they learn a representation of their input at the hidden layer(...	{ "page_id": 38870173, "title": "Feature learning" }
RBF networks). Coates and Ng note that certain variants of k-means behave similarly to sparse coding algorithms. In a comparative evaluation of unsupervised feature learning methods, Coates, Lee and Ng found that k-means clustering with an appropriate transformation outperforms the more recently invented auto-encoders ...	{ "page_id": 38870173, "title": "Feature learning" }
which may not be the case. PCA only relies on orthogonal transformations of the original data, and it exploits only the first- and second-order moments of the data, which may not well characterize the data distribution. Furthermore, PCA can effectively reduce dimension only when the input data vectors are correlated (w...	{ "page_id": 38870173, "title": "Feature learning" }
to be on the manifold. This is why the same weights are used in the second step of LLE. Compared with PCA, LLE is more powerful in exploiting the underlying data structure. === Independent component analysis === Independent component analysis (ICA) is a technique for forming a data representation using a weighted sum o...	{ "page_id": 38870173, "title": "Feature learning" }

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