BY Draconis variables are main sequence variable star s of stellar classification late spectral types , usually K or M. The name comes from the archetype for this category of variable star system, BY Draconis . They exhibit variations in their luminosity due to rotation of the star coupled with star spot s, and other chromosphere chromospheric activity. ref name MLM Resultant brightness fluctuations are generally less than 0.5 Apparent magnitude magnitudes ref name MLM on timescales equivalent to the star s rotational period, typically from a fraction of a day to several months. Oddly enough, Procyon the 8th brightest night time star which is an F5 sub giant or dwarf has also been classified as a BY Draconis variable. Source Schaaf, The Brightest Stars , Wiley, 2008. Some of these stars may exhibit flare star flares , resulting in additional variations of the UV Ceti variable UV Ceti type . ref name schrijver zwaan2000 Likewise, the spectra of BY Dra variables particularly in their H and K lines are similar to RS CVn stars, which are another class of variable stars that have active chromospheres. ref name jaschek1990 References reflist refs ref name schrijver zwaan2000 citation first1 Carolus J. last1 Schrijver first2 Cornelis last2 Zwaan title Solar and stellar magnetic activity volume 34 series Cambridge astrophysics series publisher Cambridge University Press year 2000 isbn 0521582865 page 343 url http books.google.com books?id Ik0nNfABUrMC&pg PA343 ref ref name MLM citation last1 Lopez Morales first1 Mercedes last2 Morrell first2 N. I. last3 Butler first3 R. P. last4 Seager ... variable. This type of variable is characterized by quasiperiodic photometric variations over ... of Variable Stars GCVS4.2, 2004 Ed. Schaaf, Fred, The Brightest Stars , Wiley, 2008 Variable star topics DEFAULTSORT By Draconis Variable Category BY Draconis variables Category Variable stars var star stub ca Variable BY Draconis de BY Draconis Stern es Estrella variable BY Draconis fr Variable de ... more details
In mathematical logic , a propositional variable also called a sentential variable or sentential letter is a Variable mathematics variable which can either be true or false . Propositional variables are the basic building blocks of propositional formula s, used in propositional logic and higher logics. Formulas in logic are typically built up recursively from some propositional variables, some number of logical connective s, and some logical quantifier s. Propositional variables are the atomic formula s of propositional logic. For example, in a given propositional logic, we might define a formula as follows Every propositional variable is a formula. Given a formula X the negation X is a formula. Given two formulas X and Y , and a binary connective b such as the logical conjunction , then X b Y is a formula. Note the parentheses. In this way, all of the formulas of propositional logic are built up from propositional variables as a basic unit. Propositional variables are represented as nullary Predicate mathematical logic predicates in first order logic . See also col begin col break Boolean algebra logic Boolean datatype Boolean domain col break Boolean function Logical value Propositional logic col end References Smullyan, Raymond M. First Order Logic . 1968. Dover edition, 1995. Chapter 1.1 Formulas of Propositional Logic. Category Propositional calculus Category Concepts in logic Category Logic symbols logic stub cs V rokov prom nn es Variable proposicional pl Zmienna zdaniowa zh ... more details
Taxobox name Variable Darner image Aeshnainterrupta.jpg regnum Animal ia phylum Arthropod a classis Insect a ordo Odonata familia Aeshnidae genus Aeshna species A. interrupta binomial Aeshna interrupta binomial authority Edmund Murton Walker Walker , 1904 range map Variable Darner Map.jpg The Variable Darner Aeshna interrupta is a dragonfly of the family Aeshnidae , native from Alaska through the Northwest Territories to Newfoundland and Labrador Newfoundland , south to New Hampshire and Michigan in the eastern United States , and to the mountains of New Mexico , Arizona , and California in the west. It s named after the distinctive broken stripes on the sides of the thorax of many male specimens. It lives in many habitats from northern and mountain peatlands to cattail marshes and temporary pools. It is the characteristic species of grassland ponds. References ITIS id 185979 taxon Aeshna interrupta accessdate 13 February 2006 External links http www.livinglandscapes.bc.ca cbasin www dragon aeshna interrupta.html Living Landscapes of the Royal British Columbia Museum http www.azodes.com dragons darners darn vari.asp Variable Darner at AzOdes http www.royalbcmuseum.bc.ca nh papers aeshnareport aeshnarep.html interrupta Variable Darner profile Category Aeshnidae Category Animals described in 1904 dragonfly stub nl Aeshna interrupta pl Aeshna interrupta vi Variable Darner ... more details
In computer programming , variable interpolation also variable substitution or variable expansion is the process of evaluating an expression or string literal containing one or more variables, yielding a result in which the variables are replaced with their corresponding values in memory. It is a specialized instance of concatenation . Languages that support variable interpolation include Perl , PHP , Ruby programming language Ruby , Tcl , and most Unix shell s. In these languages, variable interpolation only occurs when the string literal is double quoted, but not when it is single quoted. The variables are recognized because variables start with a sigil computer programming sigil typically code code in these languages. For example, the following Perl code which would work identically in PHP source lang perl name Alice print name said Hello World to the crowd of people. source produces the output pre Alice said Hello World to the crowd of people. pre Ruby programming language Ruby uses the code number sign code symbol for interpolation, and allows one to interpolate any expression, not just variables. Other languages may support more advanced interpolation with a special formatting function, such as code printf code , in which the first argument, the format , specifies the pattern in which the remaining arguments are substituted. Category Variable computer programming Category Programming constructs ... more details
In object oriented programming with Class computer science class es, a class variable is a Variable programming variable defined in a class i.e. a member variable of which a single copy exists, regardless of how many Instance computer science instance s of the class exist. ref name TheJavaTurotialVariables cite web url http download.oracle.com javase tutorial java nutsandbolts variables.html title The Java Tutorial, Variables accessdate 2010 10 21 ref ref name TheJavaTutorialUnderstandingInstanceAndClassMembers cite web url http download.oracle.com javase tutorial java javaOO classvars.html title The Java Tutorial, Understanding Instance and Class Members accessdate 2010 10 21 ref ref name ThePythonLanguageReferenceCompoundStatements cite web url http docs.python.org reference compound stmts.html class definitions title The Python Language Reference, Compound Statements accessdate 2010 10 21 ref ref name ObjectiveCRuntimeReference cite web url http developer.apple.com library mac documentation Cocoa Reference ObjCRuntimeRef Reference reference.html title Objective C Runtime Reference accessdate 2010 10 21 ref A class variable is the opposite of an instance variable . It is a special type of Class computer science Structure class attribute or class property, field, or data member . In Java programming language Java , C Sharp programming language C , and C , class variables are declared with the keyword computer programming keyword code static code , and may therefore be referred ... number Request number count modifies the instance variable this number count modifies the class variable Request count int Request count 0 source In this C example, the class variable code Request count ... object is given a code number code in sequential order. Since code count code is a class variable ... own distinct code number code field. Notes Reflist 2 DEFAULTSORT Class Variable Category Object oriented programming Category Variable computer programming es Variable de clase ja ta ... more details
In computer science , a local variable is a Variable programming variable that is given local scope programming scope . Such a variable is accessible only from the subroutine function or block programming block in which it is declared. In programming language s with only two levels of visibility, local variables are contrasted with global variables . On the other hand, many ALGOL derived languages allow any number of levels of nested function s with private variables, functions, constants and types hidden within them. In most languages, local variables are automatic variable s stored on the call stack directly. This means that when a recursion computer science recursive function calls itself ... issues with side effect computer science side effects that can occur with global variable global variables . Static local variables A special type of local variable, called a static local, is available ... allocated variable. In all of the above languages, static variables are declared as such with a special ... has Static variable several different meanings in various languages. code local code in Perl Perl has ... ref It gives a temporary, scope programming dynamically scoped value to a global package variable, which lasts until the end of the enclosing block. However, the variable is visible to any function ... variable a is modified to a new temporary local meaning inside f , but the global value is restored ... have printed 1 three times since in that case the code a code variable is really local to the scope ... also by Perl, but in this case, the notation was made simpler a global variable name must be preceded by a sign, like code variable name code , while a local variable has simply no sign in front of its name, like code variable name code while in perl all scalar values have a in front . See also Global variable Non local variable References references DEFAULTSORT Local Variable Category Variable computer programming et Lokaalne muutuja es Variable local fr Variable locale is Sta v r breyta ja ... more details
Taxobox name Variable Damselfly image Fledermaus Azurjungfer Coenagrion pulchellum 1.jpg image width 200px regnum Animal ia phylum Arthropod a classis Insect a ordo Odonata subordo Zygoptera familia Coenagrionidae genus Coenagrion species C. pulchellum binomial Coenagrion pulchellum binomial authority Pierre L onard Vander Linden Vander Linden , 1825 Coenagrion pulchellum , the Variable Damselfly or Variable Bluet , is a Europe an damselfly . Despite its name, it is not the only blue damselfly prone to variable patterning. Its behaviour is much like that of the Azure Damselfly it usually stays close to vegetation. Immatures are often found in adjacent meadows or uncut grassy areas. Description File Coenagrion pulchellum m 4344.jpg thumb left top 150px alt male damselfly Male C. pulchellum The male Variable Damselfly has a distinctive wine glass marking on the second Segmentation biology segment of the abdomen . This is a black U shaped mark with a black line joining the segment s narrow terminal black band. ref name Brooks cite book last Brooks first Steve title Field Guide to the Dragonflies and Damselflies of Great Britain and Ireland year 1997 publisher British Wildlife Publishing isbn 0953139905 ref This distinguishes it from the Azure Damselfly which has the U shape but no line connecting it to the terminal band. ref name Brooks Distribution The Variable Damselfly occurs throughout Europe. Scattered and uncommon in mainland Britain but widespread and common in Ireland. ref name BDS cite web title Variable Damselfly url http british dragonflies.org.uk species variable damselfly publisher British Dragonfly Society accessdate 27 May 2011 ref References reflist External links http www.brocross.com dfly species pulch.htm commons Coenagrion pulchellum damselfly stub Category Damselflies of Europe Category Coenagrionidae de Fledermaus Azurjungfer et Sarvikliidrik lt Gra ioji str liuk hu Gyakori l givad sz nl Variabele waterjuffer no Variabel bl vannymfe pl tka wczesna ... more details
NOTOC In computer programming , an automatic variable is a scope programming lexically scoped Variable programming variable which is allocated and de allocated automatically when program flow enters and leaves the variable s scope programming scope . The term local variable is usually synonymous with automatic variable, since these are the same thing in many programming languages. main Stack based memory allocation Automatic variables may be allocated in the stack frame of the procedure in which they are declared this has the useful effect of allowing recursion and reentrant subroutine re entrancy . For efficiency, the compiler optimization optimizer will try to allocate some of these variables in processor register s. In specific programming languages C programming language C , C Called automatic variables. All variables declared within a block programming block of code are automatic by default, but this can be made explicit with the code auto code keyword. ref Note the current C standard, C 11 , adds an additional meaning to the code auto code keyword, meaning a type that is Type inference inferred . ref An uninitialized automatic variable has an undefined behavior undefined value ... of code auto code is a hint to the compiler to cache the variable in a processor register. Other than not allowing the referencing operator code & code to be used on the variable or any of its subcomponents ... compiler will not allow the usage of a not explicitly initialized local variable and will give a compilation ... demands that every local variable must be explicitly initialized before being used. ref cite web ... publisher accessdate 2008 10 17 ref Perl also has a code Local variable local code operator ... scoped to the enclosing block. When the scope of the variable is left, the old value is restored. See also C syntax Storage duration specifiers Variable length array C99 new feature References and footnotes references DEFAULTSORT Automatic Variable Category Memory management Category Variable computer ... more details
Unreferenced date December 2009 Orphan date February 2009 Generalize date August 2009 A prognostic variable is a variable that a global climate model predicts by integration of a physical equation , typically vorticity , divergence , temperature , surface pressure , and water vapour concentration. The term prognostic is given to some values or variables that are directly predictive by the model, such as temperature, water vapour, salinity, depth in atmospheric or ocean models variables that can be directly obtained as a model outcome. On the other hand, there are some other variables that need to be calculated separately as derived variables, such as relative humidity which may be a diagnostic variable obtained from the model s prognostic variables, temperature and water vapour. Category Numerical climate and weather models climate stub pl Zmienna prognostyczna ... more details
Image CVP TC FC VC.svg thumb right 240px Decomposing Total Costs as Fixed Costs plus Variable cost Variable Costs . Variable costs are expenses that change in proportion to the activity of a business. ref name GNB pp 48 Garrison, Noreen, Brewer. Ch 2 Managerial Accounting and Costs Concepts, pp 48 ref Variable cost is the sum of marginal cost s over all units produced. It can also be considered normal costs. Fixed cost s and variable costs make up the two components of total cost . Direct Costs , however, are costs that can easily be associated with a particular cost object . ref name GNB pp 51 Garrison, Noreen, Brewer. Ch 2 Managerial Accounting and Costs Concepts, pp 51 ref However, not all variable costs are direct costs. For example, variable manufacturing Overhead business overhead costs are variable costs that are indirect costs , not direct costs. Variable costs are sometimes called unit level costs as they vary with the number of units produced. Direct labor and overhead are often called conversion cost , ref name GNB pp 39 Garrison, Noreen, Brewer. Ch 2 Managerial Accounting and Costs Concepts, pp 39 ref while direct material and direct labor are often referred to as prime cost . ref name GNB pp 39 In marketing , it is necessary to know how costs divide between variable and fixed ... marketing managers, 60 percent responded that they found the variable and fixed costs metric very ... in expenses happen with little or no need for managerial intervention. These costs are variable ... as variable. In retail the cost of goods is almost entirely a variable cost this is not true of manufacturing ... a variable cost. For some employees, salary is paid on monthly rates, independent of how many ... often be varied, so this type of labour cost is a variable cost. See also Multicol Cost Cost accounting Cost curve Cost driver Multicol break Semi variable cost Fixed cost Total cost Contribution margin ... ar ca Cost variable cs Variabiln n klady de Variable Kosten es Costo variable eu Kostu ... more details
Unreferenced stub auto yes date December 2009 An undefined variable in the source code of a computer program is a variable programming variable that is accessed in the code but has not been previously Declaration computer science declared by that code. In some programming languages an implicit declaration is provided the first time such a variable is encountered at compile time . In other languages such a usage is considered to be sufficiently serious that a diagnostic being issued and the compilation fails. Some language definitions initially used the implicit declaration behavior and as they matured provided an option to disable it e.g. Perl s code use strict code or Visual Basic s code Option Explicit code . Examples The following provides some examples of how various programming language implementations respond to undefined variables. Each code snippet is followed by an error message if any . CLISP GNU CLISP 2.35 source lang lisp setf y x source code EVAL variable X has no value code C programming language C GNU GCC 3.4 source lang c int main int y x return 0 source code foo.c In function main foo.c 2 error x undeclared first use in this function foo.c 2 error Each undeclared identifier is reported only once foo.c 2 error for each function it appears in. code JavaScript Mozilla Firefox 1.0 source lang javascript y x source code Error x is not defined Source File file c temp foo.js code Standard ML ML Standard ML of New Jersey v110.55 code val y x code code stdIn 1.9 Error unbound variable or constructor x code MUMPS code Set Y X code code UNDEF code OCaml 3.08 source lang ocaml let y x source code Unbound value x code Perl 5.8 source lang perl my y x source code no error ... variable x in foo.php on line 3 code Python programming language Python 2.4 source lang python ... local variable or method x for main Object from irb 1 code VBScript WSH 5.6 source lang vb Dim ... VBScript runtime error Variable is undefined x code DEFAULTSORT Undefined Variable Category Variable ... more details
refimprove date September 2010 In mathematics , a variable is a value mathematics value that may change ... as being either a dependent variable or an independent variable . Independent variables are regarded ... variable and the other values are independent variables. The notation f x is used for the value of the function f with x representing the independent variable. Similarly, notation such as f x , y ... for a variable to vary Varying, in the context of mathematical variables, does not mean change in the course of time, but rather dependence on the context in which the variable is used. This can be the immediate context of the expression mathematics expression in which the variable occurs, as in the case ... being defined. The context can also be larger, for instance when a variable is used to designate ..., and alternative names can be used instead of variable a parameter is a value that is fixed in the statement of the problem being studied although its value may not be explicitly known , an unknown is a variable ... for anything else but is an abstract value in itself. In all these cases the term variable is often ... is a variable standing for the argument of the function being defined, which can be any real number. In the identity math sum i 1 n i frac n 2 n 2 math the variable i is a summation variable which designates ... while x is called a variable. When studying this polynomial for its polynomial function this x ... notion of a variable, because the quantities E , m , P , V , n , and T are instead used to designate ... are conventionally called x , y , and z , while random variable s in statistics are usually named ... is to use X , Y , Z for the names of random variable s, with these being replaced by x , y ... are used in open sentence s. For instance, in the formula x 1 5, x is a variable which represents an unknown ... we want. 2 1 1 1 2 or 1 2 2 3 3 3 6 or 3 2 2 55 55 55 110 or 55 2 etc. So in this example, the variable x is a placeholder for any number that is to say, a variable. One important thing we assume is that the value ... more details
Lyrae variable s and W Ursae Majoris variable s, where the two components are so close that gravitation ... of this type of variable star , Bayer designation Beta Perseus Persei , first had its variability recorded in 1667 by Geminiano Montanari . The mechanism for its being variable was first correctly ... edition of the http www.sai.msu.su gcvs gcvs General Catalogue of Variable Stars 2003 lists 3,554 of them 9 of all variable stars . Data for some interesting Algol variables are given in the list of known variable stars . References reflist http www.physics.sfasu.edu astro ebstar ebstar.html Eclipsing Binary Stars , D. Bruton Stephen F. Austin State University Variable star topics Category Algol variables Category Eclipsing binaries Category Binary stars Category Variable stars ca Variable Algol cs Z krytov dvojhv zda de Algolstern fr Variable de type Algol it Variabile Algol lb Algolst ren pl ... more details
Taxobox name Variable Sunbird image Variable sunbird.jpg status LC status system IUCN3.1 regnum Animal ia phylum Chordate Chordata classis Bird Aves ordo Passeriformes familia Nectariniidae genus Cinnyris species C. venustus binomial Cinnyris venustus binomial authority George Shaw Shaw , 1799 Image Variable Sunbird male RWD3.jpg left thumb Male in Tanzania Image Variable Sunbird female RWD.jpg left thumb Female in Tanzania The Variable Sunbird , Cinnyris venustus formerly Nectarinia venusta , is a sunbird . The sunbirds are a group of very small Old World passerine bird s which feed largely on nectar, although they will also take insects, especially when feeding young. Flight is fast and direct on their short wings. Most species can take nectar by hovering like a hummingbird, but usually perch to feed most of the time. The Variable Sunbird is a fairly common resident breeder in equatorial Africa . Two eggs are laid in a suspended nest in a tree. This species is found in open woodland and cultivation. Variable Sunbirds are small, only 10cm long. They have medium length thin down curved bills and brush tipped tubular tongues, both adaptations to their nectar feeding. The adult male has a glossy green head, throat and nape with maroon breast band and a yellowish belly. The female has grey brown upperparts and yellowish underparts, and an obvious pale supercilium. The eclipse male is like the female, but shows some green, especially on the throat. The call is a clear tew tew tew tew tew . References FieldianaZool51 91. Birds of The Gambia by Barlow, Wacher and Disley, ISBN 1 873403 32 1 Category Cinnyris es Cinnyris venustus ... more details
Variable retention is a relatively new silviculture silvicultural system that retains forest structural ... silvicultural approaches to timber harvest ing Variable retention harvest systems. In textbook ... preservation. Variable retention also aids in emulation of natural disturbances by leaving behind .... are focused on maximizing timber production and future regeneration of the trees. Variable retention ... system Reconciling variable retention with the principles of silvicultural systems. Forestry chronicle, 78, 397. ref Value of variable retention Variable retention is gradually becoming a popularly ... the forest. Variable retention is believed by some forestry experts to minimize the impact of logging ... trees can be retained under the variable retention system, and trees can be retained in patches aggregated retention or left uniformly throughout a stand dispersed retention hence the name variable ... related processes. There are four key mechanisms through which variable retention is presumed ... diversity of managed stands Variable retention Harvesting methods The method of variable retention ... truck use. Some logging operations that use variable retention try to emulate Disturbance ecology forest ... s. Loggers also leave younger trees that will continue to grow. Variable retention harvesting .... Some timber companies have restricted the use of variable retention silviculture to only ... Ecology Ecologist s regard the variable retention method of harvesting as being far less detrimental to the forest ecosystem than clearcutting . However, opponents claim that variable retention ..., such as the Forest Stewardship Council FSC , approve of variable retention and are now declaring ... the variable retention method to harvest timber in the Pacific temperate rain forests WWF ecoregion ... commitment to phasing out clearcutting and embracing variable retention harvesting, and even MacMillan ... markets are beginning to ask for certified wood obtained entirely through variable retention harvesting ... more details
as random variables. More recently, nuisance variable has been used in the same context. ref Irving ... 0471385131 ref Nuisance variable has been used in the context of statistical surveys to refer information ... Sanderman, Jim C. Coyne, Adelita V. Ranchor 2006 Age Nuisance variable to be eliminated with statistical ... of interest. The term nuisance variable is sometimes also used in more general contexts ... Category Stochastic processes Category Latent variable models Category Statistical terminology ca Variable destorb es Variable estorbo ... more details
of things under discussion. The use of a metasyntactic variable is helpful in freeing a programmer from creating a logically named variable, which is often useful when creating or teaching examples ... rfc3092.html RFC 3092 rfc3092 Etymology of Foo ref The term metasyntactic variable is primarily found ... which does not violate the rules of the language can be used as a metasyntactic variable, but nonsense ... such as schematic variable see logical form . By mathematical analogy A metasyntactic variable is a word that is a Variable programming variable for other words, just as in algebra letters are used ... language, and a Variable programming variable is something that can assume a value, or something likely to vary. So metasyntactic variable denotes a word that transcends grammar and can assume ..., and reduplication is also used for pluralizing. The origin of hoge as a metasyntactic variable ... example of the C programming language the function name foo and the variable name bar are both ... foo void Declare the variable bar and set the value to 1 int bar 1 return bar source Python Spam ... python Define a function named spam def spam define the variable ham ham Hello World define the variable ... variables and lines beginning with are comments. source lang ruby Declare the variable foo and set equal to 1 foo 1 Declare the variable bar and set equal to 2 bar 2 Declare the method function named ... jargon html M metasyntactic variable.html Definition of metasyntactic variable , with examples ... archives 000375.html Variable foo and Other Programming Oddities DEFAULTSORT Metasyntactic Variable Category Placeholder names Category Metalogic Category Variable computer programming Category Syntax logic de Metasyntaktische Variable fr Variable m tasyntaxique it Variabile metasintattica he ... more details
Taxobox name Variable Checkerspot image Euphydryas chalcedona 16862.JPG image caption E. chalcedona in William O. Douglas Wilderness image width regnum Animal ia phylum Arthropoda classis Insecta ordo Lepidoptera familia Nymphalidae genus Euphydryas species E. chalcedona binomial Euphydryas chalcedona binomial authority Henry Doubleday 1808 1875 Doubleday , 1847 The Variable Checkerspot or Chalcedon Checkerspot Euphydryas chalcedona is a species of butterfly , common in western North America from Alaska to Baja California and from the Rocky Mountains to the Pacific Ocean . A highly variable species, the wing upper surface is black to dark brown. The forewing is narrow and pointed compared to similar species. The wingspan is convert 32 mm in &ndash convert 57 mm in . ref name Sommer cite web last Sommer first Stefan authorlink coauthors Denise Knight, Stephanie McDowell, Stephen Burton, Ean Harker title Euphydryas chalcedona work Digital Atlas of Idaho publisher date url http www.butterfliesandmoths.org species?l 1751 format doi accessdate 2008 06 22 ref ref name Opler cite web last Opler first Paul A. authorlink coauthors Harry Pavulaan, Ray E. Stanford, Michael Pogue, coordinators title Chalcedon Checkerspot work Butterflies and Moths of North America publisher Bozeman, MT NBII Mountain Prairie Information Node date 2006 url http www.butterfliesandmoths.org format doi accessdate 2008 06 22 ref Image Variable Checkerspot Butterfly.jpg thumb left 200px Adult butterflies feed on nectar from flower s. Caterpillars feed on a variety of plants including snowberry Symphoricarpos , paintbrush Castilleja and Buddleja . See also Euphydryas editha References references External links Commons category inline Euphydryas chalcedona Variable Checkerspot http www.cbif.gc.ca spp pages butterflies species VariableCheckerspot e.php Variable Checkerspot , Butterflies of Canada Nymphalinae stub Category Butterflies of Canada Category Euphydryas Category Butterflies and moths of North America ... more details
Taxobox name Variable dorid br Aphelodoris brunnea image Aphelodoris brunnea may09 pyramid.jpg image caption regnum Animal ia phylum Mollusca classis Gastropoda unranked ordo clade Heterobranchia br clade Euthyneura br clade Nudipleura br clade Nudibranchia superfamilia Doridoidea familia Dorididae genus Aphelodoris species A. brunnea binomial Aphelodoris brunnea binomial authority Rudolph Bergh Bergh , 1907 The variable dorid , Aphelodoris brunnea , is a species of Dorididae dorid nudibranch . It is a marine ocean marine gastropod mollusc in the family biology family Dorididae . Distribution This species is endemism endemic to South Africa, where it is known from Buffels Bay near Cape Point to East London. It is common off Port Elizabeth and is found from the low intertidal to 15 m ref GOSLINER, T.M. 1987. Nudibranchs of Southern Africa ISBN 0 930118 13 8 ref . Description Image Aphelodoris brunnea pe june09 rhinophores.jpg left thumb A close up of the rhinophores of the variable dorid The variable dorid is a drably coloured nudibranch with a pale body and variable brown patterning. It has eight gill s arranged around the anus and its rhinophore s are perfoliate . It may reach a total length of 45 mm ref ZSILAVECZ, G. 2007. Nudibranchs of the Cape Peninsula and False Bay . ISBN 0 620 38054 3 ref . Ecology The variable dorid probably feeds on sponge s. When disturbed, the animal tries to escape by swimming, flexing its body up and down. References reflist External links Category Dorididae Dorididae stub vi Aphelodoris brunnea ... more details
Taxobox name Variable Dancer image Argia fumipennis female .jpg image caption A. f. violacea image width 230px regnum Animal ia phylum Arthropod a classis Insect a ordo Odonata subordo Zygoptera familia Coenagrionidae genus Argia species A. fumipennis binomial Argia fumipennis binomial authority Hermann Burmeister Burmeister , 1839 subdivision ranks Subspecies subdivision A. f. violacea The Variable Dancer Argia fumipennis is a widespread damselfly of the family Coenagrionidae , native to North America . The subspecies A. f. violacea , native to the eastern United States is also known as the Violet Dancer . It is called this because of its purple iridescent color. References ITIS id 102143 taxon Argia fumipennis accessdate 14 February 2006 External links http www.azodes.com damsels pond damsels danc vari.asp Argia fumipennis at AzOdes http www.greglasley.net variabledan.html Variable Dancer photo and profile TaxonIds eol 2764492 Category Coenagrionidae Category Odonata of North America Category Animals described in 1839 damselfly stub nl Argia fumipennis pl Argia fumipennis vi Argia fumipennis ... more details
Taxobox name Variable Pitohui image status LC status system IUCN3.1 regnum Animalia phylum Chordata classis Aves ordo Passeriformes familia Colluricinclidae genus Pitohui species P. kirhocephalus binomial Pitohui kirhocephalus binomial authority Ren Primev re Lesson Lesson & Garnot, 1827 synonyms The Variable Pitohui Pitohui kirhocephalus is a species of bird in the Colluricinclidae family. It is found in Indonesia and Papua New Guinea . Its natural habitat is subtropical or tropical moist lowland forest s. It is also one of the few known poisonous birds. References BirdLife International 2004. http www.iucnredlist.org search details.php 51086 all Pitohui kirhocephalus . http www.iucnredlist.org 2006 IUCN Red List of Threatened Species. Downloaded on 26 July 2007. External links http animaldiversity.ummz.umich.edu site accounts pictures Pitohui kirhocephalus.html Image at ADW Category Pitohui Pachycephalidae stub fr Pitohui variable ja sv V xelpitohui ... more details
In probability and statistics , a random variable or stochastic variable is, roughly speaking, a Variable mathematics variable whose value results from a measurement on a system that is subject to variations due to chance. Intuitively, a random variable is a numerical description of the outcome of an experiment ... variable can be thought of as a quantity whose value can not exist, as a constant e.g., unchanging ... presents itself more than once . But it is a variable which can only take on a calculable range .... Realizations of a random variable are called random variate s. A random variable s possible values ... or imprecise measurements . Random variables can be classified as either Discrete random variable discrete i.e. it may assume any of a specified list of exact values or as Continuous random variable ... variables are usually real valued, but one can consider arbitrary types such as indicator random variable ... random variables, and then the mapping function included in the definition of a random variable becomes important. As an example, the square of a random variable distributed according to a standard normal distribution is itself a random variable, with a chi squared distribution . One way to think ... variable, the sample mean is a function of random variables and hence a random variable itself, whose ... of the spread , or extent to which the values are dispersed of the variable can be computed ... Press year 1999 isbn 0534209343 ref A Discrete probability distribution discrete random variable ... continuous random variable maps outcomes to values of an uncountable set e.g., the real number s . For a continuous random variable, the probability of any specific value is zero, whereas the probability ... variable can be mixed , with part of its probability spread out over an interval like a typical continuous variable, and part of it concentrated on particular values like a discrete variable. These classifications ... . We can introduce a real valued random variable Y as follows math Y omega begin cases 1, & text ... more details
No footnotes date October 2011 In an optimization problem , a slack variable is a variable that is added to an inequality constraint to transform it to an equality. Introducing a slack variable replaces an inequality constraint with an equality constraint and a nonnegativity constraint. sfn Boyd Vandenberghe 2004 p 131 In linear programming , this is required to turn an inequality into an equality where a linear combination of variables is less than or equal to a given constant in the former. As with the other variables in the augmented constraints, the slack variable cannot take on negative values, as the Simplex algorithm requires them to be positive or zero. If the slack variable associated with a constraint is zero in a given state, the constraint is binding constraint binding , as the constraint restricts the possible changes of the point. If a slack variable is positive in a given state, the constraint is non binding constraint non binding , as the constraint does not restrict the possible changes of the point. If a slack variable is negative in a given state, the point is infeasible , and not allowed, as it does not satisfy the constraint. Example By introducing the slack variable math mathbf y ge 0 math , the inequality math mathbf A mathbf x le mathbf b math can be converted to the equation math mathbf A mathbf x mathbf y mathbf b math . http apmonitor.com online view pass.php?f slack.apm Solve slack variable problem . Embedding in orthant see Orthant Generalized barycentric coordinates Slack variables give an embedding of a polytope math P hookrightarrow mathbf R geq 0 f math into the standard f orthant , where f is the number of constraints facets of the polytope . This map is one to one slack variables are uniquely determined but not onto not all combinations can be realized , and is expressed in terms of the constraints linear functionals, covectors . Slack variables are Dual linear program dual to generalized barycentric coordinates , and, dually to generalized ... more details
For the novel by Robert A. Heinlein and Spider Robinson Variable Star Image V838 Monocerotis expansion.jpg 300px right thumb Images showing the expansion of the light echo of a red variable star, the V838 Monocerotis A star is classified as variable if its apparent magnitude as seen from Earth changes ... to classify variable stars as belonging to one of two types Intrinsic variables, whose luminosity ... The first variable star was identified in 1638 when Johannes Phocylides Holwarda Johannes Holwarda ... ancient philosophers had taught. In this way, the discovery of variable stars contributed to the astronomical revolution of the sixteenth and early seventeenth centuries. The second variable star to be described was the eclipsing variable Algol , by Geminiano Montanari in 1669 John Goodricke ... Kirch G. Kirch , then R Hydrae in 1704 by Giovanni Domenico Maraldi G. D. Maraldi . By 1786 ten variable ... the number of known variable stars has increased rapidly, especially after 1890 when it became possible to identify variable stars by means of photography. The latest edition of the General Catalogue of Variable Stars ref http www.sai.msu.su gcvs gcvs iii html ref 2008 lists more than 46,000 variable ... data with observed spectral changes, astronomers are often able to explain why a particular star is variable. Variable star observations Variable stars are generally analysed using photometry astronomy ... amplitude can be very well established for many variable stars, though, these quantities may vary ... scientific study of variable stars by visually comparing the star with other stars within the same telescope telescopic field of view of which the magnitudes are known and constant. By estimating the variable ... Association of Variable Star Observers collects such observations from participants around ... light curves with spectral data often gives a clue as to the changes that occur in a variable ... moves to and from us, in the same tempo as its brightness varies. About two thirds of all variable ... more details
Taxobox name Variable Oystercatcher image Variable Oyster Catcher 01.jpg image caption Mottled variant status LC status system IUCN3.1 regnum Animalia phylum Chordata classis Aves ordo Charadriiformes familia Haematopodidae genus Haematopus species H. unicolor binomial Haematopus unicolor binomial authority Raymond Robert Forster Forster , 1844 synonyms The Variable Oystercatcher Haematopus unicolor is a species of wader in the Haematopodidae family. It is Endemism endemic to New Zealand . The Maori name is torea pango ref name retrieved 2008 http www.awana.co.nz flora birdlife oyster fact.html retrieved 2008 ref . They are also known as red bills ref http www.awana.co.nz flora birdlife oyster fact.html retirieved 2008 ref . Variable refers to the frontal plumage, which ranges from pied through mottled to all black. They are polymorphic meaning they have different genetic variants ref http www.newzealandfauna.com variableoystercatcher.php retrieved 2008 ref . Blacker birds are more common in the south. All Stewart Island variable oystercatchers are black. The have pink legs, an orange eye ring and red beaks. They are often seen in pairs on the coast all around New Zealand. During breeding, the pair will defend their territory, sometimes aggressively. Once mated pairs rarely divorce ref name retrieved 2008 . After breeding they may be seen within flocks, or on the edges of flocks ... larger at around 724 grams ref http animals.jrank.org pages 678 Oystercatchers Haematopodidae VARIABLE OYSTERCATCHER Haematopus unicolor SPECIES ACCOUNT.html Oystercatchers Haematopodidae Variable ... be easily confused with SIPO. The variable species has less definition between the black and the white ... although the SIPO does. Image Variable oyster catcher chicks.jpg thumb left Black variant oystercatcher ... af Swarttobie br Morbig Zeland Nevez ca Garsa de mar variable de Neuseel ndischer Austernfischer fr Hu trier variable it Haematopus unicolor ru fi Nokimeriharakka sv Nya ... more details
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