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Maximal compact subgroup	Applications	For the general linear group, this decomposition is the QR decomposition, and the deformation retraction is the Gram-Schmidt process. For a general semisimple Lie group, the decomposition is the Iwasawa decomposition of G as G = KAN in which K occurs in a product with a contractible subgroup AN.
RDH11	RDH11	Retinol dehydrogenase 11 is an enzyme that in humans is encoded by the RDH11 gene.RHD11, a member of the short-chain dehydrogenase/reductase (SDR) superfamily of oxidoreductases, is expressed at high levels in prostate epithelium, and its expression is regulated by androgens.[supplied by OMIM]
RDH11	Clinical significance	Mutations in RDH11 are associated to retinitis pigmentosa.
Glucose-6-phosphate dehydrogenase (coenzyme-F420)	Glucose-6-phosphate dehydrogenase (coenzyme-F420)	Glucose-6-phosphate dehydrogenase (coenzyme-F420) (EC 1.1.98.2, coenzyme F420-dependent glucose-6-phosphate dehydrogenase, F420-dependent glucose-6-phosphate dehydrogenase, FGD1, Rv0407, F420-dependent glucose-6-phosphate dehydrogenase 1) is an enzyme with systematic name D-glucose-6-phosphate:F420 1-oxidoreductase. This enzyme catalyses the following chemical reaction D-glucose 6-phosphate + oxidized coenzyme F420 ⇌ 6-phospho-D-glucono-1,5-lactone + reduced coenzyme F420Thus enzyme is specific for D-glucose 6-phosphate.
Dismasting	Dismasting	Dismasting, also spelled demasting, occurs to a sailing ship when one or more of the masts responsible for hoisting the sails that propel the vessel breaks. Dismasting usually occurs as the result of high winds during a storm acting upon masts, sails, rigging, and spars. Over compression of the mast owing to tightening the rigger too much and g-forces as a consequence of wave action and the boat swinging back and forth can also result in a dismasting. Dismasting does not necessarily impair the vessel's ability to stay afloat, but rather its ability to move under sail power. Frequently, the hull of the vessel remains intact, upright and seaworthy.
Dismasting	Dismasting	Modern masts are usually made of aluminum, carbon fibre, or other high-strength materials. These masts are subject to huge forces and tensions during high wind, large seas, or racing situations, and it is not uncommon even today for modern masts to be lost.
Dismasting	Dismasting	The dismasting of a vessel can be immediately life-threatening as a consequence of a mast falling atop crew or passengers. For example, two deaths and several injuries occurred in Hawaii owing to two different dismastings. These incidents resulted in more stringent enforcement of safety standards for commercially operating sailboats. A dismasting can also endanger lives after the mast has fallen. The reason is the broken tangle of mast, rigging, and sails usually remains attached to the vessel owing to the rigging. If waves bash a large broken mast section against a relatively thin modern hull, the entire vessel can be lost. Therefore, it is frequently imperative for crew members to go out of the relative safety of the interior and into the same stormy conditions that caused the dismasting. There they must cut away the mess without becoming entangled in the lines, and without getting blown or knocked off the deck into the sea. To assist in this effort, many sailboats will carry a large pair of bolt cutters, extra hack-saws, or hydraulic cutters for just such an emergency. Crew also have to go onto deck to confirm there are no ropes or lines being dragged in the water that could wrap around a propeller before starting any internal combustion engine as a secondary means of propulsion.
Dismasting	Dismasting	Dismastings are rarely life-threatening after the initial event and the broken mast is cut away. However, dismastings appear to have contributed to the loss of life at sea as a consequence of crews abandoning an otherwise perfectly seaworthy vessel in favor of a life raft. This has led to a sailing adage to always “Step up into the life raft.” In other words, to never abandon the sailboat unless it is confirmed that it is really sinking.
Dismasting	Dismasting	After a dismasting, the crew might jury rig, or fashion, a makeshift mast(s) and sails from salvaged and spare materials carried aboard. This would allow limited propulsion and navigational control. If the ship managed to make landfall near forests with suitable wood, new masts could be constructed from the locally available material. The masts of a sailing ship should be regularly inspected and replaced if necessary due to storm damage and normal wear. Most ocean-going ships would carry a large supply of rope, sailcloth, and even spars for ordinary and extraordinary repairs. It is often possible to use part of the broken mast to create a jury rig. Spinnaker poles and mizzen booms may even be used. A man-of-war would expect to carry out additional repairs due to battle damage.
Dismasting	Factors contributing to dismastings	Dismastings occur for many reasons. They tend to occur more prevalently for certain types of sailors, in particular areas, and particular types of sailing vessel. Having too much sail out for the weather conditions is perhaps the number one cause of dismastings. Novice and racing sailors in particular are more likely be flying more sail cloth area than more experienced, and non-racing sailors. Areas where sudden weather changes and wind shifts are frequent are more risky than areas where winds tend to be more consistent. For this reason sailing vessels in areas with consistently high winds may suffer fewer dismastings than vessels where winds are normally light but can suddenly change to very intense when a squall occurs.
Dismasting	Factors contributing to dismastings	Dismastings owing to rigging failures tend to occur either very soon after a vessel is launched or soon after the rigging has been modified from the original design. This is particularly true for custom designed vessels. Production vessels on the other hand benefit from all the experience of similar vessels that have the same mast and rigging. One particular problem identified has been changes in rigging cables from a smaller to a larger size. Larger diameter cables produce far more compression forces on the mast when they appear to be taunt. This in turn causes the mast to collapse in column owing to over compression. Older rigging is also the source of problems since the older the rigging is the more likely corrosion has damaged the integrity of metals. Stainless steel rigging in particular has been cited as being problematic since out strands of a wire rope might appear to be fine while at the same time inner strands are compromised. For this reason many insurance companies insist that rigging holding the mast upright, termed the standing rigging, must be replaced every 10 years.Heeling characteristics of the sailing vessel are also a contributing factor. Some vessels are more apt to lean away from the wind and "spill" a sudden wind gust harmlessly. The more likely a vessel tends to heel, the more a sudden strong wind gust is said to spill out of the sails because the vessel leans out of the way. A vessel that heels easily is termed as being tender whereas a vessel with a larger counter weight down low in the water, called the ballast, is termed as being stiffer. Racing vessels tend to be stiffer and spill the wind less and hence are at a greater risk of dismastings. However, it is also not good if a vessel is too tender. A very tender vessel can be easily rolled by a wave and flip completely upside down. Dismastings have occurred after a sailboat has been rolled. The extreme resistance of the water causes the failure to occur.
Dismasting	Factors contributing to dismastings	Multi-hull sailboats, namely catamarans and trimarans, are particularly prone to dismastings. These types of vessels don't readily spill a sudden wind gust for a different reason. It is their wide beam that causes their sails to remain closer to vertical in the face of strong wind. The wider the vessel's beam the more likely the extreme loads. Therefore, since trimarans tend to be wider than catamarans they also tend to be more prone to dismastings owing to extreme loads. It is not as if designers fail to recognize these facts. A multi-hull vessel will typically have a much stronger mast and stronger rigging than a mono-hull of the same size.
Dismasting	Factors contributing to dismastings	G-force loads is one of the less common reasons for a dismasting, however, it is still a real risk for both types of sailing vessels. Very stiff mono-hulls with a strong righting force tend to return to a near upright position much faster after being heeled by a strong gust of wind. This causes the motion to much more jerky. The mast will come to a sudden stop when the vessel returns to near upright when the wind fills the sails again. The problem is the mass of the mast still has momentum. Multi-hulls don't suffer g-forces caused by the wind to the same degree. Instead they are far more susceptible to g-force load owing to wave action. Waves coming abeam, i.e. striking the vessel sideways pick up and drop each hull of the vessels. If the amplitude of the wave and frequency of the waves corresponds to a factor similar to the distance between the hulls even relatively short waves can cause a dismasting. Trimarans in particular are prone to this type of dismasting since this type of vessel can rock back and forth between being supported on the center hull and one of the two ama at one second, and the center hull and the other ama the next. This violent rocking in turn translates to extreme g-force shocks on the rigging caused by the weight of the mast swinging back and force. Hence a trimaran can be dismasted even if no sails are up at all and waves are not extreme.
Dismasting	Factors contributing to dismastings	A particular travel direction of a sailing vessel is also more likely to lead to a dismasting. When a sailing vessel is traveling downwind, there is a chance the vessel may jibe. An accidental jibe in particular occurs when a sailing vessel is traveling downwind and the boom of the main sail suddenly swings from being on one side of the vessel to the other. The boom will come to a sudden halt when the rope controlling the boom's position becomes taunt again. At roughly the same moment the wind will fill the mainsail and a shock load will transfer into the mast and rigging and a dismasting might occur. To help prevent accidental jibes, sailors will frequently tie a line to the end of the boom to secure the boom to one side of the vessel. This line is typically called the jibe preventer.
Dismasting	Dismastings in literature and films	In Herman Melville's seminal novel, "Moby Dick," Captain Ahab is said to have been, "...dismasted off Japan," alluding to Ahab's leg having been taken off by the white whale and replaced with a polished whale-bone peg-leg. "but like his dismasted craft, he shipped another mast without coming home for it. He has a quiver of 'em."
RealPC	RealPC	RealPC was a Macintosh program that emulates an x86 PC, allowing the use of MS-DOS, Windows NT, Windows 95, and Windows 98. RealPC was compatible with PowerPC Macs running system software 7.1.2 through 9.2. Requirements were: Any Power Macintosh or Mac OS compatible, System 7.1.2 or later, Minimum 16 Mbytes of Ram, hard drive space for 50 Mbytes (MS-DOS), 60 Mbytes (Windows 3.x), 130 Mbytes (Windows 95), and any Macintosh compatible CD-ROM drive. RealPC emulated a Pentium-based PC with MMX technology, supported Sound Blaster and MMX, and allowed you to use a Macintosh joystick, allowing you to run PC programs, including MS-DOS, and Windows, games and applications, alongside your existing Macintosh applications. RealPC was provided with MS-DOS 6.22 already installed, so you could immediately run MS-DOS games and applications on your Macintosh. Linux was not supported and due to shared RAM between Mac OS and RealPC Windows 98 was the reasonable limit. RealPC was able to convert Virtual-PC hard disk files to use and run the installed OS.
RealPC	RealPC	Its box and CD featured the image of silent film star Harold Lloyd. RealPC was discontinued in 2003.
Isovalent hybridization	Isovalent hybridization	In chemistry, isovalent or second order hybridization is an extension of orbital hybridization, the mixing of atomic orbitals into hybrid orbitals which can form chemical bonds, to include fractional numbers of atomic orbitals of each type (s, p, d). It allows for a quantitative depiction of bond formation when the molecular geometry deviates from ideal bond angles.
Isovalent hybridization	Isovalent hybridization	Only bonding with 4 equivalent substituents results in exactly sp3 hybridization. For molecules with different substituents, we can use isovalent hybridization to rationalize the differences in bond angles between different atoms. In the molecule methyl fluoride for example, the HCF bond angle (108.73°) is less than the HCH bond angle (110.2°). This difference can be attributed to more p character in the C−F bonding and more s character in the C−H bonding orbitals. The hybridisation of bond orbitals is determined by Bent's rule: "Atomic s character concentrates in orbitals directed toward electropositive substituents".
Isovalent hybridization	Isovalent hybridization	The bond length between similar atoms also shortens with increasing s character. For example, the C−H bond length is 110.2 pm in ethane, 108.5 pm in ethylene and 106.1 pm in acetylene, with carbon hybridizations sp3 (25% s), sp2 (33% s) and sp (50% s) respectively.
Isovalent hybridization	Isovalent hybridization	To determine the degree of hybridization of each bond one can utilize a hybridization parameter (λ). For hybrids of s and p orbitals, this is the coefficient (λ) multiplying the p orbital when the hybrid orbital is written in the form (s+λp) . The square of the hybridization parameter equals the hybridization index (n) of an spn orbital. n=λ2 The fractional s character of orbital i is 11+λi2 , and the s character of all the hybrid orbitals must sum to one, so that ∑i11+λi2=1 The fractional p character of orbital i is λi21+λi2 , and the p character of all the hybrid orbitals sums to the number of p orbitals involved in the formation of hybrids: ∑iλi21+λi2=1,2,or3 These hybridization parameters can then be related to physical properties like bond angles. Using the two bonding atomic orbitals i and j we are able to find the magnitude of the interorbital angle. The orthogonality condition implies the relation known as Coulson's theorem: cos ⁡θij=0 For two identical ligands the following equation can be utilized: cos ⁡θii=0 The hybridization index cannot be measured directly in any way. However, one can find it indirectly by measuring specific physical properties. Because nuclear spins are coupled through bonding electrons, and the electron penetration to the nucleus is dependent on s character of the hybrid orbital used in bonding, J-coupling constants determined through NMR spectroscopy is a convenient experimental parameter that can be used to estimate the hybridization index of orbitals on carbon. The relationships for one-bond 13C-1H and 13C-13C coupling are 13 500 500 Hz)χs(i) and 13 13 550 550 Hz)χs(i)χs(j) ,where 1JX-Y is the one-bond NMR spin-spin coupling constant between nuclei X and Y and χS(α) is the s character of orbital α on carbon, expressed as a fraction of unity.
Isovalent hybridization	Isovalent hybridization	As an application, the 13C-1H coupling constants show that for the cycloalkanes, the amount of s character in the carbon hybrid orbital employed in the C-H bond decreases as the ring size increases. The value of 1J13C-1H for cyclopropane, cyclobutane and cyclopentane are 161, 134, and 128 Hz, respectively. This is a consequence of the fact that the C-C bonds in small, strained rings (cyclopropane and cyclobutane) employ excess p character to accommodate their molecular geometries (these bonds are famously known as 'banana bonds'). In order to conserve the total number of s and p orbitals used in hybridization for each carbon, the hybrid orbital used to form the C-H bonds must in turn compensate by taking on more s character. Experimentally, this is also demonstrated by the significantly higher acidity of cyclopropane (pKa ~ 46) compared to, for instance, cyclohexane (pKa ~ 52).
Capsid	Capsid	A capsid is the protein shell of a virus, enclosing its genetic material. It consists of several oligomeric (repeating) structural subunits made of protein called protomers. The observable 3-dimensional morphological subunits, which may or may not correspond to individual proteins, are called capsomeres. The proteins making up the capsid are called capsid proteins or viral coat proteins (VCP). The capsid and inner genome is called the nucleocapsid.
Capsid	Capsid	Capsids are broadly classified according to their structure. The majority of the viruses have capsids with either helical or icosahedral structure. Some viruses, such as bacteriophages, have developed more complicated structures due to constraints of elasticity and electrostatics. The icosahedral shape, which has 20 equilateral triangular faces, approximates a sphere, while the helical shape resembles the shape of a spring, taking the space of a cylinder but not being a cylinder itself. The capsid faces may consist of one or more proteins. For example, the foot-and-mouth disease virus capsid has faces consisting of three proteins named VP1–3.Some viruses are enveloped, meaning that the capsid is coated with a lipid membrane known as the viral envelope. The envelope is acquired by the capsid from an intracellular membrane in the virus' host; examples include the inner nuclear membrane, the Golgi membrane, and the cell's outer membrane.Once the virus has infected a cell and begins replicating itself, new capsid subunits are synthesized using the protein biosynthesis mechanism of the cell. In some viruses, including those with helical capsids and especially those with RNA genomes, the capsid proteins co-assemble with their genomes. In other viruses, especially more complex viruses with double-stranded DNA genomes, the capsid proteins assemble into empty precursor procapsids that include a specialized portal structure at one vertex. Through this portal, viral DNA is translocated into the capsid.Structural analyses of major capsid protein (MCP) architectures have been used to categorise viruses into lineages. For example, the bacteriophage PRD1, the algal virus Paramecium bursaria Chlorella virus-1 (PBCV-1), mimivirus and the mammalian adenovirus have been placed in the same lineage, whereas tailed, double-stranded DNA bacteriophages (Caudovirales) and herpesvirus belong to a second lineage.
Capsid	Specific shapes	Icosahedral The icosahedral structure is extremely common among viruses. The icosahedron consists of 20 triangular faces delimited by 12 fivefold vertexes and consists of 60 asymmetric units. Thus, an icosahedral virus is made of 60N protein subunits. The number and arrangement of capsomeres in an icosahedral capsid can be classified using the "quasi-equivalence principle" proposed by Donald Caspar and Aaron Klug. Like the Goldberg polyhedra, an icosahedral structure can be regarded as being constructed from pentamers and hexamers. The structures can be indexed by two integers h and k, with h≥1 and k≥0 ; the structure can be thought of as taking h steps from the edge of a pentamer, turning 60 degrees counterclockwise, then taking k steps to get to the next pentamer. The triangulation number T for the capsid is defined as: T=h2+h⋅k+k2 In this scheme, icosahedral capsids contain 12 pentamers plus 10(T − 1) hexamers. The T-number is representative of the size and complexity of the capsids. Geometric examples for many values of h, k, and T can be found at List of geodesic polyhedra and Goldberg polyhedra.
Capsid	Specific shapes	Many exceptions to this rule exist: For example, the polyomaviruses and papillomaviruses have pentamers instead of hexamers in hexavalent positions on a quasi T = 7 lattice. Members of the double-stranded RNA virus lineage, including reovirus, rotavirus and bacteriophage φ6 have capsids built of 120 copies of capsid protein, corresponding to a T = 2 capsid, or arguably a T = 1 capsid with a dimer in the asymmetric unit. Similarly, many small viruses have a pseudo T = 3 (or P = 3) capsid, which is organized according to a T = 3 lattice, but with distinct polypeptides occupying the three quasi-equivalent positions T-numbers can be represented in different ways, for example T = 1 can only be represented as an icosahedron or a dodecahedron and, depending on the type of quasi-symmetry, T = 3 can be presented as a truncated dodecahedron, an icosidodecahedron, or a truncated icosahedron and their respective duals a triakis icosahedron, a rhombic triacontahedron, or a pentakis dodecahedron.
Capsid	Specific shapes	Prolate An elongated icosahedron is a common shape for the heads of bacteriophages. Such a structure is composed of a cylinder with a cap at either end. The cylinder is composed of 10 elongated triangular faces. The Q number (or Tmid), which can be any positive integer, specifies the number of triangles, composed of asymmetric subunits, that make up the 10 triangles of the cylinder. The caps are classified by the T (or Tend) number.
Capsid	Specific shapes	The bacterium E. coli is the host for bacteriophage T4 that has a prolate head structure. The bacteriophage encoded gp31 protein appears to be functionally homologous to E. coli chaperone protein GroES and able to substitute for it in the assembly of bacteriophage T4 virions during infection. Like GroES, gp31 forms a stable complex with GroEL chaperonin that is absolutely necessary for the folding and assembly in vivo of the bacteriophage T4 major capsid protein gp23.
Capsid	Specific shapes	Helical Many rod-shaped and filamentous plant viruses have capsids with helical symmetry. The helical structure can be described as a set of n 1-D molecular helices related by an n-fold axial symmetry. The helical transformation are classified into two categories: one-dimensional and two-dimensional helical systems. Creating an entire helical structure relies on a set of translational and rotational matrices which are coded in the protein data bank. Helical symmetry is given by the formula P = μ x ρ, where μ is the number of structural units per turn of the helix, ρ is the axial rise per unit and P is the pitch of the helix. The structure is said to be open due to the characteristic that any volume can be enclosed by varying the length of the helix. The most understood helical virus is the tobacco mosaic virus. The virus is a single molecule of (+) strand RNA. Each coat protein on the interior of the helix bind three nucleotides of the RNA genome. Influenza A viruses differ by comprising multiple ribonucleoproteins, the viral NP protein organizes the RNA into a helical structure. The size is also different; the tobacco mosaic virus has a 16.33 protein subunits per helical turn, while the influenza A virus has a 28 amino acid tail loop.
Capsid	Functions	The functions of the capsid are to: protect the genome, deliver the genome, and interact with the host.The virus must assemble a stable, protective protein shell to protect the genome from lethal chemical and physical agents. These include extremes of pH or temperature and proteolytic and nucleolytic enzymes. For non-enveloped viruses, the capsid itself may be involved in interaction with receptors on the host cell, leading to penetration of the host cell membrane and internalization of the capsid. Delivery of the genome occurs by subsequent uncoating or disassembly of the capsid and release of the genome into the cytoplasm, or by ejection of the genome through a specialized portal structure directly into the host cell nucleus.
Capsid	Origin and evolution	It has been suggested that many viral capsid proteins have evolved on multiple occasions from functionally diverse cellular proteins. The recruitment of cellular proteins appears to have occurred at different stages of evolution so that some cellular proteins were captured and refunctionalized prior to the divergence of cellular organisms into the three contemporary domains of life, whereas others were hijacked relatively recently. As a result, some capsid proteins are widespread in viruses infecting distantly related organisms (e.g., capsid proteins with the jelly-roll fold), whereas others are restricted to a particular group of viruses (e.g., capsid proteins of alphaviruses).A computational model (2015) has shown that capsids may have originated before viruses and that they served as a means of horizontal transfer between replicator communities since these communities could not survive if the number of gene parasites increased, with certain genes being responsible for the formation of these structures and those that favored the survival of self-replicating communities. The displacement of these ancestral genes between cellular organisms could favor the appearance of new viruses during evolution.
IRows	IRows	iRows was a web-based spreadsheet in beta with a GUI similar to the traditional desktop-based spreadsheet applications, such as Microsoft Excel and OpenOffice.org. It was shut down on December 31, 2006, after it was announced that its two founders had been hired by Google.iRows used Ajax and XML. It was described as an example of a Web 2.0 system. iRows supported conventional spreadsheet features functions, value formatting and charts and added web oriented spreadsheet capabilities like collaboration (multiple people using a shared spreadsheet, sending a spreadsheet as a link instead of an attachment and ability to publish spreadsheets on other web pages (e.g. blogs).
R-factor (crystallography)	R-factor (crystallography)	In crystallography, the R-factor (sometimes called residual factor or reliability factor or the R-value or RWork) is a measure of the agreement between the crystallographic model and the experimental X-ray diffraction data. In other words, it is a measure of how well the refined structure predicts the observed data. The value is also sometimes called the discrepancy index, as it mathematically describes the difference between the experimental observations and the ideal calculated values. It is defined by the following equation: obs calc obs \|, where F is the so-called structure factor and the sum extends over all the reflections of X-rays measured and their calculated counterparts respectively. The structure factor is closely related to the intensity of the reflection it describes: Ihkl∝\|F(hkl)\|2 .The minimum possible value is zero, indicating perfect agreement between experimental observations and the structure factors predicted from the model. There is no theoretical maximum, but in practice, values are considerably less than one even for poor models, provided the model includes a suitable scale factor. Random experimental errors in the data contribute to R even for a perfect model, and these have more leverage when the data are weak or few, such as for a low-resolution data set. Model inadequacies such as incorrect or missing parts and unmodeled disorder are the other main contributors to R , making it useful to assess the progress and final result of a crystallographic model refinement. For large molecules, the R-factor usually ranges between 0.6 (when computed for a random model and against an experimental data set) and 0.2 (for example for a well refined macro-molecular model at a resolution of 2.5 Ångström). Small molecules (up to ca. 1000 atoms) usually form better-ordered crystals than large molecules, and thus it is possible to attain lower R-factors. In the Cambridge Structural Database of small-molecule structures, more than 95% of the 500,000+ crystals have an R-factor lower than 0.15, and 9.5% have an R-factor lower than 0.03.
R-factor (crystallography)	R-factor (crystallography)	Crystallographers also use the Free R-Factor ( RFree ) to assess possible overmodeling of the data. RFree is computed according to the same formula given above, but on a small, random sample of data that are set aside for the purpose and never included in the refinement. RFree will always be greater than R because the model is not fitted to the reflections that contribute to RFree , but the two statistics should be similar because a correct model should predict all the data with uniform accuracy. If the two statistics differ significantly then that indicates the model has been over-parameterized, so that to some extent it predicts not the ideal error-free data for the correct model, but rather the error-afflicted data actually observed.
R-factor (crystallography)	R-factor (crystallography)	The quantities sym and merge are similarly used to describe the internal agreement of measurements in a crystallographic data set.
Selenite (mineral)	Selenite (mineral)	Selenite, satin spar, desert rose, gypsum flower are crystal habit varieties of the mineral gypsum. All varieties of gypsum, including selenite and alabaster, are composed of calcium sulfate dihydrate (meaning that it has two molecules of water), with the chemical formula CaSO4·2H2O. Selenite contains no significant selenium – The similar names both derive from Greek selḗnē (σελήνη 'Moon'). Some of the largest crystals ever found are of selenite, the largest specimen found in the Naica Mine's Cave of the Crystals being 12 metres long and weighing 55 tons.
Selenite (mineral)	History and etymology	"Selenite" is mostly synonymous with gypsum, but from the 15th century, it has named the transparent variety that occurs in crystals or crystalline masses. The name derives through Middle English selenite from Latin selenites, ultimately from Greek selēnítēs líthos (σεληνίτης λίθος, lit. 'moon stone'). It got this name because people historically believed the mineral waxed and waned with the cycles of the Moon.
Selenite (mineral)	Distinguishing characteristics	The main distinguishing characteristics of crystalline gypsum are its softness (hardness 2 on Mohs scale, soft enough to scratch with a fingernail) and its three unequal cleavages. Other distinguishing characteristics include its crystal habits, pearly lustre, easy fusibility with loss of water, and solubility in hot dilute hydrochloric acid.
Selenite (mineral)	Varieties	Though sometimes grouped together as "selenite", the four crystalline varieties have differences. General identifying descriptions of the related crystalline varieties are: Selenite Most often transparent and colorless If selenite crystals show opacity or color, it is caused by the presence of other minerals, sometimes in druse Satin spar Most often silky and fibrous; chatoyant; can exhibit some coloration The satin spar name has also been applied to fibrous calcite (a related calcium mineral), which can be distinguished from gypsum by its greater hardness (Mohs 3), rhombohedral cleavage, and reaction with dilute hydrochloric acid.
Selenite (mineral)	Varieties	Desert rose Rosette-shaped gypsum with outer druse of sand or with sand throughout – most often sand colored (in all the colors that sand can exhibit) The desert rose name can also be applied to barite desert roses (another related sulfate mineral) – barite is a harder mineral with higher density Gypsum flower Gypsum flowers are curved rosettes of fibrous gypsum crystals found in solution caves.
Selenite (mineral)	Use and history	Satin spar is sometimes cut into cabochons to best display its chatoyance.
Selenite (mineral)	Crystal habit and properties	Crystal habit refers to the shapes that crystals exhibit. Selenite crystals show a variety of habits, but the most common are tabular, prismatic, or acicular (columnar) crystals, often with no imperfections or inclusions. Twinned crystals are common, and often take the form of "swallow tail" twins.Selenite crystals sometimes form in thin tabular or mica-like sheets and have been used as window panes as at Santa Sabina in Rome.Selenite crystals sometimes will also exhibit bladed rosette habit (usually transparent and like desert roses) often with accompanying transparent, columnar crystals. Selenite crystals can be found both attached to a matrix or base rock, but can commonly be found as entire free-floating crystals, often in clay beds (and as can desert roses).Satin spar is almost always prismatic and fibrous in a parallel crystal habit. Satin spar often occurs in seams, some of them quite long, and is often attached to a matrix or base rock.Desert roses are most often bladed, exhibiting the familiar shape of a rose, and almost always have an exterior druse. Desert roses form in wet sand, unattached to a matrix or base rock.Gypsum flowers are most often acicular, scaly, stellate, and lenticular. Gypsum flowers most often exhibit simple twinning (known as contact twins); where parallel, long, needle-like crystals, sometimes having severe curves and bends, will frequently form “ram’s horns”, "fishtail", "arrow/spear-head", and "swallowtail" twins. Selenite crystals can also exhibit “arrow/spear-head” as well as “duck-bill” twins. Both selenite crystals and gypsum flowers sometimes form quite densely in acicular mats or nets; and can be quite brittle and fragile. Gypsum flowers are usually attached to a matrix (can be gypsum) or base rock.
Selenite (mineral)	Crystal habit and properties	Color Gypsum crystals are colorless (most often selenite), white (or pearly – most often satin spar), or gray, but may be tinted brown, yellow, red, or blue by the presence of impurities, such as iron oxides or clay minerals. Transparency Gypsum crystals can be transparent (most often selenite), translucent (most often satin spar but also selenite and gypsum flowers), and opaque (most often the rosettes and flowers). Opacity can be caused by impurities, inclusions, druse, and crust, and can occur in all four crystalline varieties. Luster Selenite typically shows vitreous luster, but may show pearly luster on cleavage surfaces. Satin spar shows characteristic silky luster. Luster is not often exhibited in the rosettes, due to their exterior druse; nevertheless, the rosettes often show glassy to pearly luster on edges. Gypsum flowers usually exhibit more luster than desert roses.
Selenite (mineral)	Crystal habit and properties	Other optical properties Fibrous satin spar exhibits chatoyancy (cat's eye effect).When cut across the fibers and polished on the ends, satin spar exhibits an optical illusion when placed on a printed or pictured surface: print and pictures appear to be on the surface of the sample. It is often called and sold as the “television stone” (as is ulexite).Some selenite and satin spar specimens exhibit fluorescence or phosphorescence.
Selenite (mineral)	Crystal habit and properties	Tenacity All four crystalline varieties are slightly flexible, though will break if bent significantly. They are not elastic, meaning they can be bent, but will not bend back on their own.All four crystalline varieties are sectile in that they can be easily cut, will peel (particularly selenite crystals that exhibit mica-like properties), and like all gypsum varieties, can be scratched by a fingernail (hardness: 2 on Mohs Scale). The rosettes are not quite as soft due to their exterior druse; nevertheless, they too can be scratched.Selenite crystals that exhibit in either reticular or acicular habits, satin spar, in general (as fibrous crystals are thin and narrow), desert roses that are thinly bladed, and gypsum flowers, particularly acicular gypsum flowers, can be quite brittle and easily broken.
Selenite (mineral)	Crystal habit and properties	Size All four crystalline varieties can range in size from minute to giant selenite crystals measuring 11 meters long such as those found in the caves of the Naica Mine of Chihuahua, Mexico. The crystals thrived in the cave's extremely rare and stable natural environment. Temperatures stayed at 58 °C, and the cave was filled with mineral-rich water that drove the crystals' growth. The largest of those crystals weighs 55 tons, is 11 meters (36 ft) long, and is over 500,000 years old.
Selenite (mineral)	Occurrence	Gypsum occurs on every continent and is the most common of all the sulfate minerals.
Selenite (mineral)	Occurrence	Gypsum is formed as an evaporative mineral, frequently found in alkaline lake muds, clay beds, evaporated seas, salt flats, salt springs, and caves. It is frequently found in conjunction with other minerals such as, copper ores, sulfur and sulfides, silver, iron ores, coal, calcite, dolomite, limestone, and opal. Gypsum has been dated to almost every geologic age since the Silurian Period 443.7 ± 1.5 Ma.In dry, desert conditions and arid areas, sand may become trapped both on the inside and the outside of gypsum crystals as they form. Interior inclusion of sand can take on shapes such as an interior hourglass shape common to selenite crystals of the ancient Great Salt Plains Lake bed, Oklahoma, US. Exterior inclusion (druse) occurs as embedded sand grains on the surface such as, commonly seen in the familiar desert rose.
Selenite (mineral)	Occurrence	When gypsum dehydrates severely, anhydrite is formed. If water is reintroduced, gypsum can and will reform – including as the four crystalline varieties. An example of gypsum crystals reforming in modern times is found at Philips Copper Mine (closed and abandoned), Putnam County, New York, US where selenite micro crystal coatings are commonly found on numerous surfaces (rock and otherwise) in the cave and in the dump.
Comparison of mobile operating systems	Comparison of mobile operating systems	This is a comparison on mobile operating systems. Only the latest versions are shown in the table below, even though older versions may still be marketed.
Quine–McCluskey algorithm	Quine–McCluskey algorithm	The Quine–McCluskey algorithm (QMC), also known as the method of prime implicants, is a method used for minimization of Boolean functions that was developed by Willard V. Quine in 1952 and extended by Edward J. McCluskey in 1956. As a general principle this approach had already been demonstrated by the logician Hugh McColl in 1878, was proved by Archie Blake in 1937, and was rediscovered by Edward W. Samson and Burton E. Mills in 1954 and by Raymond J. Nelson in 1955. Also in 1955, Paul W. Abrahams and John G. Nordahl as well as Albert A. Mullin and Wayne G. Kellner proposed a decimal variant of the method.The Quine–McCluskey algorithm is functionally identical to Karnaugh mapping, but the tabular form makes it more efficient for use in computer algorithms, and it also gives a deterministic way to check that the minimal form of a Boolean function has been reached. It is sometimes referred to as the tabulation method.
Quine–McCluskey algorithm	Quine–McCluskey algorithm	The method involves two steps: Finding all prime implicants of the function. Use those prime implicants in a prime implicant chart to find the essential prime implicants of the function, as well as other prime implicants that are necessary to cover the function.
Quine–McCluskey algorithm	Complexity	Although more practical than Karnaugh mapping when dealing with more than four variables, the Quine–McCluskey algorithm also has a limited range of use since the problem it solves is NP-complete. The running time of the Quine–McCluskey algorithm grows exponentially with the number of variables. For a function of n variables the number of prime implicants can be as large as 3n/n , e.g. for 32 variables there may be over 534 × 1012 prime implicants. Functions with a large number of variables have to be minimized with potentially non-optimal heuristic methods, of which the Espresso heuristic logic minimizer was the de facto standard in 1995.Step two of the algorithm amounts to solving the set cover problem; NP-hard instances of this problem may occur in this algorithm step.
Quine–McCluskey algorithm	Example	Input In this example, the input is a Boolean function in four variables, f:{0,1}4→{0,1} which evaluates to 1 on the values 10 11 12 and 15 , evaluates to an unknown value on 9 and 14 , and to 0 everywhere else (where these integers are interpreted in their binary form for input to f for succinctness of notation). The inputs that evaluate to 1 are called 'minterms'. We encode all of this information by writing 10 11 12 15 14 ).
Quine–McCluskey algorithm	Example	This expression says that the output function f will be 1 for the minterms 10 11 12 and 15 (denoted by the 'm' term) and that we don't care about the output for 9 and 14 combinations (denoted by the 'd' term). The summation symbol ∑ denotes the logical sum (logical OR, or disjunction) of all the terms being summed over.
Quine–McCluskey algorithm	Example	Step 1: finding prime implicants First, we write the function as a table (where 'x' stands for don't care): One can easily form the canonical sum of products expression from this table, simply by summing the minterms (leaving out don't-care terms) where the function evaluates to one: fA,B,C,D = A'BC'D' + AB'C'D' + AB'CD' + AB'CD + ABC'D' + ABCD.which is not minimal. So to optimize, all minterms that evaluate to one are first placed in a minterm table. Don't-care terms are also added into this table (names in parentheses), so they can be combined with minterms: At this point, one can start combining minterms with other minterms. If two terms differ by only a single digit, that digit can be replaced with a dash indicating that the digit doesn't matter. Terms that can't be combined any more are marked with an asterisk (*). For instance 1000 and 1001 can be combined to give 100-, indicating that both minterms imply the first digit is 1 and the next two are 0.
Quine–McCluskey algorithm	Example	When going from Size 2 to Size 4, treat - as a third bit value. Match up the -'s first. The terms represent products and to combine two product terms they must have the same variables. One of the variables should be complemented in one term and uncomplemented in the other. The remaining variables present should agree. So to match two terms the -'s must align and all but one of the other digits must be the same. For instance, -110 and -100 can be combined to give -1-0, as can -110 and -010 to give --10, but -110 and 011- cannot since the -'s do not align. -110 corresponds to BCD' while 011- corresponds to A'BC, and BCD' + A'BC is not equivalent to a product term.
Quine–McCluskey algorithm	Example	Note: In this example, none of the terms in the size 4 implicants table can be combined any further. In general this process should be continued (sizes 8, 16 etc.) until no more terms can be combined.
Quine–McCluskey algorithm	Example	Step 2: prime implicant chart None of the terms can be combined any further than this, so at this point we construct an essential prime implicant table. Along the side goes the prime implicants that have just been generated (these are the ones that have been marked with a "*" in the previous step), and along the top go the minterms specified earlier. The don't care terms are not placed on top—they are omitted from this section because they are not necessary inputs.
Quine–McCluskey algorithm	Example	To find the essential prime implicants, we look for columns with only one "✓". If a column has only one "✓", this means that the minterm can only be covered by one prime implicant. This prime implicant is essential. For example: in the first column, with minterm 4, there is only one "✓". This means that m(4,12) is essential. Minterm 15 also has only one "✓", so m(10,11,14,15) is also essential. Now all columns with one "✓" are covered.
Quine–McCluskey algorithm	Example	The second prime implicant can be 'covered' by the third and fourth, and the third prime implicant can be 'covered' by the second and first, and neither is thus essential. If a prime implicant is essential then, as would be expected, it is necessary to include it in the minimized boolean equation. In some cases, the essential prime implicants do not cover all minterms, in which case additional procedures for chart reduction can be employed. The simplest "additional procedure" is trial and error, but a more systematic way is Petrick's method. In the current example, the essential prime implicants do not handle all of the minterms, so, in this case, the essential implicants can be combined with one of the two non-essential ones to yield one equation: fA,B,C,D = BC'D' + AB' + ACor fA,B,C,D = BC'D' + AD' + ACBoth of those final equations are functionally equivalent to the original, verbose equation: fA,B,C,D = A'BC'D' + AB'C'D' + AB'C'D + AB'CD' + AB'CD + ABC'D' + ABCD' + ABCD.
RAML (software)	RAML (software)	RESTful API Modeling Language (RAML) is a YAML-based language for describing static APIs (but not REST APIs). It provides all the information necessary to describe APIs on the level 2 of the Richardson Maturity Model. Although designed with RESTful APIs in mind, RAML is not capable of describing APIs that obey all constraints of REST (it cannot describe an API obeying HATEOAS, in particular). It encourages reuse, enables discovery and pattern-sharing and aims for merit-based emergence of best practices.
RAML (software)	History	RAML was first proposed in 2013. The initial RAML specification was authored by Uri Sarid, Emiliano Lesende, Santiago Vacas and Damian Martinez, and garnered support from technology leaders like MuleSoft, AngularJS, Intuit, Box, PayPal, Programmable Web and API Web Science, Kin Lane, SOA Software, and Cisco. Development is managed by the RAML Workgroup. The current workgroup signatories include technology leaders from MuleSoft (Uri Sarid, CTO), AngularJS (Misko Hevery, Project Founder), Intuit (Ivan Lazarov, Chief Enterprise Architect), Airware (Peter Rexer, Director of Product - Developer Platform), Programmable Web and API Science (John Musser, Founder), SOA Software (Tony Gullotta, Director of Development), Cisco (Jaideep Subedar, Senior Manager, Product Management - Application Integration Solutions Group), VMware (Kevin Duffey, Senior MTS Engineer), Akamai Technologies (Rob Daigneau, Director of Architecture for Akamai's OPEN API Platform) and Restlet (Jerome Louvel, CTO and Founder). RAML is a trademark of MuleSoft.Very few existing APIs meet the precise criteria to be classified as RESTful APIs. Consequently, like most API initiatives in the 2010s, RAML has initially focussed on the basics of APIs including resources, methods, parameters, and response bodies that need not be hypermedia. There are plans to move towards more strictly RESTful APIs as the evolution of technology and the market permits.There are a number of reasons why RAML has broken out from being a proprietary vendor language and has proven interesting to the broader API community: RAML has been open-sourced along with tools and parsers for common languages. The development of RAML will be overseen by a steering committee of API and UX practitioners, and there is an emerging ecosystem of third-party tools being developed around RAML MuleSoft originally started using Swagger (now OpenAPI Specification), but decided it was best suited to documenting an existing API, not for designing an API from scratch. RAML evolved out of the need to support up-front API design in a succinct, human-centric language API descriptions are often verbose and repetitive, which can make them difficult to understand and use, and slow adoption of the APIs. RAML has introduced language features that support structured files and inheritance that address cross-cutting concernsA new organization, under the sponsorship of the Linux Foundation, called the Open API Initiative was set up in 2015 to standardize the description of HTTP APIs. A number of companies including SmartBear, Google, IBM and Microsoft were founding members. SmartBear donated the Swagger specification to the new group. RAML and API Blueprint are also under consideration by the group.
RAML (software)	Example	This is an example RAML file. As with YAML, indentation shows nesting. Some highlights: line 7, 12: defines traits, invoked in multiple places line 12: an Include file line 13, 14: define a "resource" data type "/songs"; uses previously defined traits line 15, 19, 37: defines HTTP methods line 25, 36: MIME types.
RAML (software)	API gateways supporting RAML	Apigee MuleSoft AWS API Gateway by AWS (through AWS API Gateway Importer) Akana RestletFurthermore, you can convert your RAML specification to either OpenAPI or API Blueprint using APIMATIC, thus enabling you to use further API gateways.
Body marbling	Body marbling	Body marbling is a painting process similar to paper marbling, in which paint is floated on water and transferred to a person's skin. Unlike the traditional oil-based technique for paper, neon or ultraviolet reactive colours are typically used, and the paint is water-based and non-toxic. The term "body marbling" was coined in 2011 by Brad Lawrence of Black Light Visuals. Body marbling has become popular at festivals.
Body marbling	Painting process	The skin is bathed in a salt water solution which allows the paint to adhere. The desired pattern is created by adding drops of paint to the water surface, and transferred to the skin by dipping. The water for painting is mixed with a thickening agent such as guar gum. The skin is then dipped in a rinse bath and allowed to dry. The painting is temporary and can be removed by washing.
Kepler-33b	Kepler-33b	Kepler-33b is an extrasolar planet orbiting Kepler-33 in the constellation Cygnus. It is one of five planets orbiting Kepler-33.
Kepler-33b	Discovery	Kepler-33b was, along with twenty-six other planets in eleven different planetary systems, confirmed to be a planet on January 26, 2012.
Kepler-33b	The Kepler-33 system	Kepler-33b orbits its host star with 4 other planets. All five planets orbit its star closer than Mercury does to the Sun. Of those five, Kepler-33b is closest. All Kepler-33 planets are too close to be in the habitable zone.
Deck tennis	Deck tennis	Deck tennis is a sport that is played by mariners on the decks of both cargo and passenger vessels. The sport is a hybrid between tennis and quoits, and is played with either the rubber disk or ring, or a similarly-sized rope ring. The sport has been standardized and formalized in several countries under names such as "tennikoit" or "ring tennis".
Deck tennis	Deck tennis	American sources from the 1930s and 1940s attribute the origin, or at least formal establishment of the game, to Cleve F. Shaffer. In 1981, Mariano Herrera and Alejandro Nougues from Argentina won the first and only Deck Tennis World Championship celebrated on the beach in Punta del Este, Uruguay.
Deck tennis	Rules	Most games of deck tennis, unlike the official tennikoit form, are informal and without set rules or a governing body, so rules tend to vary. Usually it is played on a court roughly 40 to 50 feet (11 to 14 m) long and 15 to 20 feet (5 to 7 m) wide and may be played as either as singles or doubles. The midcourt net is usually the height, or higher than that of a tennis net. The goal of the game is to serve (throw) the ring into the opponent's court, and the opponent tries to catch it before it falls and immediately throw it back from the same position where it was caught, with a point being scored when the server managed to land a quoit on the opponent's side of the court.
Deck tennis	Rules	The scoring system is commonly the same as regular tennis: Love, 15, 30, 40, Deuce, Advantage, Game. This is in contrast with tennikoit, where sets are played to 21 individual points, similar to badminton.
Deck tennis	In popular culture	In the 1936 film Piccadilly Jim, Robert Montgomery as "Piccadilly Jim" is depicted playing the game with his romantic rival in the film Ralph Forbes as "Lord Frederick Priory" on the deck of an ocean liner.Boy - Roald Dahl, plays a vigerous game in the voyage out
Reports on Progress in Physics	Reports on Progress in Physics	Reports on Progress in Physics is a monthly peer-reviewed scientific journal published by IOP Publishing. The editor-in-chief as of 2022 is Subir Sachdev (Harvard University).
Reports on Progress in Physics	Scope	The focus of this journal is invited review articles covering all branches of physics. Each review will typically survey and critique a particular topic, or developments in a field. Introductions of articles are intended for a broad readership, beyond the specialist or expert. In addition to the traditional review article two other formats are available: Reports on Progress (about 20 pages) and Key Issues Reviews (about 10 pages).
Reports on Progress in Physics	Abstracting and indexing	Reports on Progress in Physics is abstracted and indexed in the following databases:
Alpha,N-DMT	Alpha,N-DMT	Alpha,N-DMT, or α,N-dimethyltryptamine, is a lesser-known psychedelic drug. It is the α,N-dimethyl analog of DMT. α,N-DMT was first synthesized by Alexander Shulgin. In his book TiHKAL (Tryptamines I Have Known and Loved), Shulgin lists the dosage as 50-100 mg, and the duration as 6–8 hours. α,N-DMT causes an unpleasant body load. Very little data exists about the pharmacological properties, metabolism, and toxicity of α,N-DMT. α,N-DMT is known to be a potent monoamine oxidase inhibitor
Lunate	Lunate	Lunate is a crescent or moon-shaped microlith. In the specialized terminology of lithic reduction, a lunate flake is a small, crescent-shaped flake removed from a stone tool during the process of pressure flaking. In the Natufian period, a lunate was a small crescent-shaped stone tool that was sometimes used to harvest grasses. In archaeology a lunate is a small stone artifact, that has a sharpened straight edge and a blunt crescent shaped back. The word originates from the Latin word lunatus which means to bend like a crescent, and from luna meaning moon in Latin. A lunate object can be typically used as a decorative piece or as a stone tool.
Lunate	Israeli lunate	In the earlier findings of Epipaleolithic lunate in the Natufian, Harifian, and Negev Kebaran periods in Israel they were roughly 10–40 mm long and were formed on small blades or bladelets. While the later findings Natufian and Harifian range of lengths varied then between 9 mm and 17 mm. In the later period the lunate resulted in three specific types: Helwan Backing (Bifacial) Plain Abrupt Backing Bipolar Backing (anvil)The differences among these three types are also associated with the length of the lunate objects, with Helwan lunate normally being the longest and bipolar being the shortest. For unknown reasons, the epipaleolithic lunate tool type disappeared and did not reappear until around the end of the 4th millennium B.C. These Lunate tools were most likely used as barbs in arrow shafts, or as transverse arrowheads coated with poison. The Lunate are also a very rare artifact from the Early Bronze Age because there was not as much emphasis on hunting during that period. The reappearance of Lunate after several millennia could shed some light on the hunting emphasis in the society. Lunate have been found as far north as the Azor tombs in Israel and was far south as south Sinai in this particular region.
Lunate	Other cultural examples	Lunate artefacts have been discovered among early Māori stone carving in New Zealand. The original lunate pendant found in New Zealand appears to be of clear transparent pounamu (greenstone), from Ruapuke Island, in Foveaux Strait. Its characteristics include a notched edge and the stone itself is thought to originate from Tangiwai, New Zealand. There was a second rare lunate-shaped object discovered in the New Zealand ethnological region as well.
Lunate	Other cultural examples	A handful of ancient societies shaped their tools in the form of lunate such as the Puebloan peoples who originated around San Juan County, Utah. There have also been findings of lunate used by Puebloan peoples dating back to the 3rd/4th millennium B.C.
MreB	MreB	MreB is a protein found in bacteria that has been identified as a homologue of actin, as indicated by similarities in tertiary structure and conservation of active site peptide sequence. The conservation of protein structure suggests the common ancestry of the cytoskeletal elements formed by actin, found in eukaryotes, and MreB, found in prokaryotes. Indeed, recent studies have found that MreB proteins polymerize to form filaments that are similar to actin microfilaments. It has been shown to form multilayer sheets comprising diagonally interwoven filaments in the presence of ATP or GTP.MreB along with MreC and MreD are named after the mre operon (murein formation gene cluster E) to which they all belong.
MreB	Function	MreB controls the width of rod-shaped bacteria, such as Escherichia coli. A mutant E. coli that creates defective MreB proteins will be spherical instead of rod-like. Also, most bacteria that are naturally spherical do not have the gene encoding MreB. Members of the Chlamydiota are a notable exception, as these bacteria utilize the protein for localized septal peptidoglycan synthesis. Prokaryotes carrying the mreB gene can also be helical in shape. MreB has long been thought to form a helical filament underneath the cytoplasmic membrane, however, this model has been brought into question by three recent publications showing that filaments cannot be seen by electron cryotomography and that GFP-MreB can be seen as patches moving around the cell circumference. It has been shown to interact with several proteins that are proven to be involved in length growth (for instance PBP2). Therefore, it probably directs the synthesis and insertion of new peptidoglycan building units into the existing peptidoglycan layer to allow length growth of the bacteria.
Hydranencephaly	Hydranencephaly	Hydranencephaly is a condition in which the brain's cerebral hemispheres are absent to a great degree and the remaining cranial cavity is filled with cerebrospinal fluid. "Cephalic" is the scientific term for "head" or "head end of body".
Hydranencephaly	Hydranencephaly	Hydranencephaly is a type of cephalic disorder. These disorders are congenital conditions that derive from damage to, or abnormal development of, the fetal nervous system in the earliest stages of development in utero. These conditions do not have any definitive identifiable cause factor. Instead, they are generally attributed to a variety of hereditary or genetic conditions, but also by environmental factors such as maternal infection, pharmaceutical intake, or even exposure to high levels of radiation.Hydranencephaly should not be confused with hydrocephalus, which is an accumulation of excess cerebrospinal fluid in the ventricles of the brain.
Hydranencephaly	Hydranencephaly	In hemihydranencephaly, only half of the cranial cavity is affected.
Hydranencephaly	Signs and symptoms	An infant with hydranencephaly may appear normal at birth or may have some distortion of the skull and upper facial features due to fluid pressure inside the skull. The infant's head size and spontaneous reflexes such as sucking, swallowing, crying, and moving the arms and legs may all seem normal, depending on the severity of the condition. However, after a few weeks the infant sometimes becomes irritable and has increased muscle tone (hypertonia). After several months of life, seizures and hydrocephalus may develop, if they did not exist at birth. Other symptoms may include visual impairment, lack of growth, deafness, blindness, spastic quadriparesis (paralysis), and intellectual deficits.Some infants may have additional abnormalities at birth including seizures, myoclonus (involuntary sudden, rapid jerks), limited thermoregulation abilities, and respiratory problems. Still other infants display no obvious symptoms at birth, going many months without a confirmed diagnosis of hydranencephaly. In some cases severe hydrocephalus, or another cephalic condition, is misdiagnosed.
Hydranencephaly	Causes	Hydranencephaly is an extreme form of porencephaly, which is characterized by a cyst or cavity in the cerebral hemispheres.Although the exact cause of hydranencephaly remains undetermined in most cases, the most likely general cause is by vascular insult, such as stroke, injury, intrauterine infections, or traumatic disorders after the first trimester of pregnancy. In a number of cases where intrauterine infection was determined to be the causing factor, most involved toxoplasmosis and viral infections such as enterovirus, adenovirus, parvovirus, cytomegalovirus, herpes simplex, Epstein-Barr, and syncytial viruses. Another cause factor is monochorionic twin pregnancies, involving the death of one twin in the second trimester, which in turn causes vascular exchange to the living twin through placental circulation through twin-to-twin transfusion, causing hydranencephaly in the surviving fetus. One medical journal reports hydranencephaly as an autosomal inherited disorder with an unknown mode of transmission, causing a blockage of the carotid artery where it enters the cranium; this causes obstruction and damage to the cerebral cortex.
Hydranencephaly	Causes	Genetic Hydranencephaly is a recessive genetic condition, so both parents must carry the asymptomatic gene and pass it along to their child. There is a 25% chance that both parents will pass the gene to their child, resulting in hydranencephaly. Genetic hydranencephaly afflicts both males and females in equal numbers. Post-natal brain injury Though hydranencephaly is typically a congenital disorder, it can occur as a postnatal diagnosis in the aftermath of meningitis, intracerebral infarction, ischemia, or a traumatic brain injury.
Hydranencephaly	Diagnosis	An accurate, confirmed diagnosis is generally impossible until after birth, though prenatal diagnosis using fetal ultrasonography (ultrasound) can identify characteristic physical abnormalities. After birth, diagnosis may be delayed for several months because the infant's early behavior appears to be relatively normal. The most accurate diagnostic techniques are thorough clinical evaluation (considering physical findings and a detailed patient history); advanced imaging techniques, such as angiography, computerized tomography (CT scan), and magnetic resonance imaging (MRI); and (more rarely) transillumination. However, diagnostic literature fails to provide a clear distinction between severe obstructive hydrocephalus and hydranencephaly, leaving some children with an unsettled diagnosis.Preliminary diagnosis may be made in utero via standard ultrasound, and can be confirmed with a standard anatomy ultrasound. Hydranencephaly is sometimes misdiagnosed as bilaterally symmetric schizencephaly (a less destructive developmental process on the brain), severe hydrocephalus (cerebrospinal fluid excess within the skull), or alobar holoprosencephaly (a neurological developmental anomaly). Once destruction of the brain is complete, the cerebellum, midbrain, thalami, basal ganglia, choroid plexus, and portions of the occipital lobes typically remain preserved to varying degrees. The cerebral cortex is absent; however, in most cases, the fetal head remains enlarged due to increased intracranial pressure, which results from inadequate reabsorption of the cerebrospinal fluid produced in the choroid plexus.
Hydranencephaly	Prognosis	There is no standard treatment for hydranencephaly. Treatment is symptomatic and supportive. An accompanying diagnosis of hydrocephalus may be treated with surgical insertion of a shunt; this often improves prognosis and quality of life.The prognosis for children with hydranencephaly is generally quite poor. Death often occurs within the first year of life, though many children live several years, or even into adulthood; in one reported case, a woman with hydranencephaly was assessed at age 32.
Hydranencephaly	Occurrence	This condition affects under 1 in 10,000 births worldwide. Hydranencephaly is a rare disorder in the United States, which is defined as affecting fewer than 1 in 250,000.
Jumping translocation breakpoint	Jumping translocation breakpoint	The jumping translocation breakpoint protein (JTB), also known as prostate androgen-regulated protein (PAR), is a protein that in humans is encoded by the JTB gene. It is an orphan receptor with unknown function.The JTB family of proteins contains several jumping translocation breakpoint proteins or JTBs. Jumping translocation (JT) is an unbalanced translocation that comprises amplified chromosomal segments jumping to various telomeres. JTB has been found to fuse with the telomeric repeats of acceptor telomeres in a case of JT. Homo sapiens JTB (hJTB) encodes a transmembrane protein that is highly conserved among divergent eukaryotic species. JT results in a hJTB truncation, which potentially produces an hJTB product devoid of the transmembrane domain. hJTB is located in a gene-rich region at 1q21, called epidermal differentiation complex (EDC). JTB has also been implicated in prostatic carcinomas.
NAD+ Five-prime cap	NAD+ Five-prime cap	In molecular biology, the NAD+ five-prime cap (NAD+ 5’ cap) refers to a molecule of nicotinamide adenine dinucleotide (NAD+), a nucleoside-containing metabolite, covalently bonded the 5’ end of cellular mRNA. While the more common methylated guanosine (m7G) cap is added to RNA by a capping complex that associates with RNA polymerase II (RNAP II), the NAD cap is added during transcriptional initiation by the RNA polymerase itself, acting as a non-canonical initiating nucleotide (NCIN). As such, while m7G capping can only occur in organisms possessing specialized capping complexes, because NAD capping is performed by RNAP itself, it is hypothesized to occur in most, if not all, organisms.The NAD+ 5’ cap has been observed in bacteria, contrary to the long-held belief that prokaryotes lacked 5’-capped RNA, as well as on the 5’ cap of eukaryotic mRNA, in place of the m7G cap. This modification also potentially allows for selective degradation of RNA]within prokaryotes as different pathways are involved in the degradation of NAD+-capped and uncapped 5′-triphosphate-RNAs.
NAD+ Five-prime cap	NAD+ Five-prime cap	In eukaryotic cells, while the more commonly observed m7G cap promotes the stability of the mRNA and supports translation, the NAD+ cap targets the RNA transcript for decay, facilitated by the non-canonical decapping enzyme, DXO. Considering the centrality of NAD in redox chemistry and post-translational protein modification, its attachment to RNA represents potentially undiscovered pathways in RNA metabolism and regulation.
NAD+ Five-prime cap	Function in prokaryotes	In prokaryotes, the 5’ NAD+ modification is established by bacterial RNAP during transcription initiation and has been shown to display functions analogous to those of the eukaryotic 5’ cap. In-vitro transcribed NAD-modified RNA was shown to be more resistant to RNase E, the main enzyme in the decay pathway of E. coli. NAD-modification further was shown to decelerate RNA processing by RNA pyrophosphohydrolase (RppH), which is known to trigger RNase-E-mediated decay through the conversion of 5′-triphosphate-RNA to 5′-monophosphate-RNA. Nudc, a nudix phosphohydrolase, can decap NAD-RNA through hydrolyzing NAD(H) into NMN(H) and AMP, causing RNase-E-mediated decay, but is inactive against 5′-triphosphate-RNA. This 5’ modification allows for the selective initiation of degradation for a subset of RNAs as the NAD-capped RNAs are stabilized in the presence of RppH, but are decapped by Nudc, while the 5′-triphosphate-RNAs are susceptible to RppH but not Nudc.Next generation sequencing (NGS) of the NAD-RNA conjugates in E. coli revealed an abundance of a specific group of small regulatory RNAs (sRNAs) which are known to be involved in stress response systems, as well as enzymes involved in cellular metabolism. The small number of RNA transcripts with a NAD cap might allow the cell to selectively degrade these RNAs separate from other pathways. Considering that the stress responses are known to affect NAD+ concentration, this finding further supports the possibility of undiscovered pathways linking the energetic state of a cell to mRNA turnover.
NAD+ Five-prime cap	Function in prokaryotes	NAD capping has also been suggested to recruit specific proteins to the 5’ end of the RNA as NAD is one of the most common protein ligands. NAD-binding pockets are well characterized in many proteins and could help the localization of the RNA to an enzyme or receptor. Many NAD-utilizing metabolic enzymes can also bind to RNA, presenting the possibility of unknown ribonucleoprotein complexes.
NAD+ Five-prime cap	Function in eukaryotes	NAD+ 5’ capped RNA have been found in yeast, humans, and Arabidopsis thaliana. In eukaryotes, the NAD+ cap is removed by non-canonical decapping enzymes from the DXO family. DeNADing by DXO results in a 5’ end monophosphate RNA distinct from NudC which results in NMN plus 5′ monophosphate RNA. Importantly, DXO is ~6 fold more efficient at decapping NAD+ compared to m7G, suggesting that it selectively degrades NAD-capped RNA rather than the more common m7G cap, similar to NudC.

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