difficult another problem instance problem ''x'' solved using algorithm ''y'' ''x'' difficult ''y'' say ''x'' ' 'reduces'' ''y'' many different types reductions based method reduction cook reductions karp reductions levin reductions bound complexity reductions polynomial time reductions log space reductions commonly used reduction polynomial time reduction means reduction process takes polynomial time example problem squaring integer reduced


problem multiplying two integers means algorithm multiplying two integers used square integer indeed done giving input inputs multiplication algorithm thus see squaring difficult multiplication since squaring reduced multiplication motivates concept problem hard complexity class problem ''x'' ''hard'' class problems ''c'' every problem ''c'' reduced ''x'' thus problem ''c'' harder ''x''

Formal science
Computer science
Theory of computation
Computational complexity theory


would mean p nbsp nbsp np ref name sipser important open problems journal journal acm volume year pages doi issue cid postscript ref p versus np problem complexity class p often seen mathematical abstraction modeling computational tasks admit efficient algorithm hypothesis called cobham edmonds thesis complexity class np hand contains many problems people would like solve efficiently efficient algorithm known boolean satisfiability problem hamiltonian path problem vertex cover problem since deterministic turing machines special non deterministic turing machines easily observed


problem p also member class np question whether p equals np one important open questions theoretical computer science wide implications solution ref name sipser see ref answer yes many important problems shown efficient solutions include various types integer programming problems operations research many problems logistics protein structure prediction biology ability find formal proofs pure mathematics theorems p versus np problem one millennium prize problems proposed


clay mathematics institute us prize resolving problem problems np known p np complete shown ladner '''p''' '''np''' exist problems '''np''' neither '''p''' '''np complete''' ref name ladner problems called np intermediate problems graph isomorphism problem discrete logarithm problem integer factorization problem examples problems believed np intermediate np problems known '''p''' '''np complete''' graph isomorphism problem


computational problem determining whether two finite graphs isomorphic important unsolved problem complexity theory whether graph isomorphism problem '''p''' '''np complete''' np intermediate answer known believed problem least np complete ref name ak ref graph isomorphism np complete polynomial time hierarchy collapses second level since widely believed polynomial hierarchy collapse finite level believed graph isomorphism np complete best algorithm problem due l szl babai eugene luks


co problem '''np complete''' polynomial time hierarchy collapse first level ie '''np''' equal '''co np''' best known algorithm integer factorization general number field sieve takes time math e left sqrt frac right sqrt log n sqrt log log n math factor odd integer ''n'' however best known quantum algorithm problem shor 's algorithm run polynomial time unfortunately fact n't say much problem lies respect non quantum complexity classes separations complexity classes many known complexity classes suspected unequal proved


instance '''p''' '''np''' '''pp''' '''pspace''' possible '''p''' '''pspace''' '''p''' equal '''np''' '''p''' equal '''pspace''' either since many known complexity classes '''p''' '''pspace''' '''rp''' '''bpp''' '''pp''' '''bqp''' '''ma''' '''ph''' etc possible complexity classes collapse one class proving classes unequal would major breakthrough complexity theory along lines '''co np''' class containing complement problems ie problems ''yes'' ''no'' answers reversed


distinct equal classes suspected '''p''' '''bpp''' equal however currently open '''bpp''' '''nexp''' intractability problem solved theory eg given large finite resources especially time practice ''any'' solution takes many resources useful known '''''' conversely problem solved practice called '''''' literally problem handled term ''infeasible'' literally cannot done sometimes used interchangeably ''intractable'' though risks confusion feasible solution


mathematical optimization tractable problems frequently identified problems polynomial time solutions '''p''' '''ptime''' known cobham edmonds thesis problems known intractable sense include exptime hard np p np hard problems also intractable sense however identification inexact polynomial time solution large degree large leading coefficient grows quickly may impractical practical size problems conversely exponential time solution grows slowly may practical realistic input solution takes long time


worst case may take short time cases average case thus still practical saying problem p imply large cases problem hard even example decision problem presburger arithmetic shown p yet algorithms written solve problem reasonable times cases similarly algorithms solve np complete knapsack problem wide range sizes less quadratic time sat


solvers routinely handle large instances np complete boolean satisfiability problem see exponential time algorithms generally unusable practice consider program makes sup ''n'' sup operations halting small ''n'' say assuming sake example computer sup sup operations second program would run nbsp nbsp sup sup years order magnitude age universe even much faster computer program would useful small instances sense intractability problem somewhat independent


technological progress however exponential time algorithm takes sup ''n'' sup operations practical ''n'' gets relatively large similarly polynomial time algorithm always practical running time say ''n'' sup sup unreasonable consider efficient still useless except small instances indeed practice even ''n'' sup sup ''n'' sup sup algorithms often impractical realistic sizes problems continuous complexity theory continuous complexity theory refer complexity theory problems involve continuous functions approximated discretizations studied numerical analysis one approach complexity theory numerical analysis


information based complexity continuous complexity theory also refer complexity theory use analog computation uses continuous dynamical systems differential equations control theory considered form computation differential equations used modelling continuous time hybrid discrete continuous time systems history early example algorithm complexity analysis running time analysis euclidean algorithm done gabriel lam actual research explicitly devoted complexity algorithmic problems started numerous foundations laid various researchers influential among


definition turing machines alan turing turned robust flexible simplification computer beginning systematic studies computational complexity attributed seminal paper computational complexity algorithms juris hartmanis richard e stearns laid definitions time complexity space complexity proved hierarchy theorems ref name fortnow ref addition edmonds suggested consider good algorithm one running time bounded polynomial input size earlier papers studying problems solvable


turing machines specific bounded resources include ref name fortnow john myhill 's definition linear bounded automata myhill raymond smullyan 's study rudimentary sets well hisao yamada 's paper real time computations somewhat earlier boris trakhtenbrot pioneer field ussr studied another specific complexity measure remembers manuel blum formulated set axioms known blum axioms specifying desirable properties complexity measures set computable functions proved important result called speed theorem field began flourish


stephen cook leonid levin proved existence practically relevant problems np complete richard karp took idea leap forward landmark paper reducibility among combinatorial problems showed diverse combinatorial graph theoretical problems infamous computational intractability np complete see also context computational complexity descriptive complexity theory game complexity leaf language limits computation list complexity classes list computability complexity topics list important publications theoretical computer science list unsolved problems computer science parameterized complexity proof complexity quantum


complexity theory structural complexity theory transcomputational problem computational complexity mathematical operations works complexity references citations textbooks surveys external links https complexityzoonet complexity zoo complexity zoo https mathoverflownet q important results papers complexity theory every one know https wwwscottaaronsoncom papers philospdf scott aaronson philosophers care computational complexity computational fields study


crystalline solid atomic resolution image strontium titanate brighter spots columns strontium atoms darker ones titanium oxygen columns '''crystallography''' experimental science determining arrangement atoms crystalline solids see crystal structure word crystallography derived greek words ''crystallon'' cold drop frozen drop meaning extending solids degree transparency ''graphein'' write july united nations recognised importance science crystallography proclaiming would international year crystallography ref name un resolution http wwwiycr org resolution un announcement

Applied science
Engineering and technology
Materials Science and Engineering
Crystallography


index final plot allows symmetry crystal established crystallographic methods depend analysis diffraction patterns sample targeted beam type x rays commonly used beams used include electrons neutrons crystallographers often explicitly state type beam used terms ''x ray crystallography neutron diffraction'' ''electron diffraction'' three types radiation interact specimen different ways x rays interact spatial distribution electrons sample electrons charged particles therefore interact total charge


small object requires collecting light magnifying lens resolution optical system limited diffraction limit light depends wavelength thus overall clarity resulting crystallographic electron density maps highly dependent upon resolution diffraction data categorized low medium high atomic example visible light wavelength ngstr three orders magnitude longer length typical atomic bonds atoms nbsp therefore conventional optical microscope cannot resolve


features sample highly ordered repetitive atomic structure bravais lattice crystals diffract x rays coherent manner also referred bragg 's reflection notation coordinates ' 'square brackets'' ''' nowiki nowiki ''' denote direction vector real space coordinates ''angle brackets'' ''chevrons'' ''' lt gt ''' denote ''family'' directions related symmetry operations cubic crystal system example ''' ''' would mean nowiki nowiki negative directions miller indices ''parentheses'' ''' ''' denote plane crystal structure


regular repetitions plane particular spacing cubic system normal hkl plane direction hkl lower symmetry cases normal hkl parallel hkl indices ''curly brackets'' ''braces'' ''' nowiki nowiki ''' denote family planes normals cubic materials symmetry makes equivalent way angle brackets denote family directions non cubic materials hkl necessarily perpendicular hkl techniques materials analyzed crystallographically proteins occur naturally crystals typically


molecules placed solution allowed slowly crystallize vapor diffusion drop solution containing molecule buffer precipitants sealed container reservoir containing hygroscopic solution water drop diffuses reservoir slowly increasing concentration allowing crystal form concentration rise quickly molecule would simply precipitate solution resulting disorderly granules rather orderly hence usable crystal crystal obtained data collected using beam radiation although many universities


part crystals molecules coaxed crystallize sake measurement spite certain amount molecular information deduced patterns generated fibers powders perfect solid crystal may exhibit degree order level order sufficient deduce structure simple molecules determine coarse features complicated molecules example double helical structure dna deduced x ray diffraction pattern generated


fibrous sample materials science crystallography used materials scientists characterize different materials single crystals effects crystalline arrangement atoms often easy see macroscopically natural shapes crystals reflect atomic structure addition physical properties often controlled crystalline defects understanding crystal structures important prerequisite understanding crystallographic defects mostly materials occur single crystal poly crystalline form ie aggregate small crystals different orientations powder diffraction method takes diffraction patterns


polycrystalline samples large number crystals plays important role structural determination physical properties also linked crystallography example minerals clay form small flat platelike structures clay easily deformed platelike particles slip along plane plates yet remain strongly connected direction perpendicular plates mechanisms studied crystallographic texture measurements another example iron transforms body centered cubic bcc structure called ferrite face centered cubic fcc structure called austenite heated


fcc structure close packed structure unlike bcc structure thus volume iron decreases transformation occurs crystallography useful phase identification manufacturing using material generally desirable know compounds phases present material composition structure proportions influence material 's properties phase characteristic arrangement atoms x ray neutron diffraction used identify patterns present material thus compounds present crystallography covers enumeration symmetry patterns


formed atoms crystal reason related group theory biology x ray crystallography primary method determining molecular conformations biological macromolecules particularly protein nucleic acids dna rna fact double helical structure dna deduced crystallographic data first crystal structure macromolecule solved three dimensional model myoglobin molecule obtained x ray analysis protein data bank pdb freely accessible repository structures proteins biological macromolecules computer programs rasmol pymol


vmd used visualize biological molecular structures neutron crystallography often used help refine structures obtained x ray methods solve specific bond methods often viewed complementary x rays sensitive electron positions scatter strongly heavy atoms neutrons sensitive nucleus positions scatter strongly even many light isotopes including hydrogen deuterium electron crystallography used determine protein structures notably membrane proteins viral capsids contribution women x ray crystallography number women pioneers


x ray crystallography time excluded branches physical science kathleen lonsdale research student william henry bragg son lawrence founded science x ray crystallography beginning th century bragg women research students total kathleen joined crystallography research team royal institution london getting married children went back work bragg researcher confirmed structure benzene ring carried studies


diamond one first two women elected royal society appointed first female tenured professor chemistry head department crystallography university college london kathleen always advocated greater participation women science said country wants make full use potential scientists technologists could must expect get women quite simply gets men utopian suggest country really


wants married women return scientific career children longer need physical presence make special arrangements encourage period kathleen began collaboration william astbury set space group tables published became essential tool crystallographers molecular model penicillin dorothy hodgkin dorothy hodgkin joined laboratory physicist john desmond bernal former student bragg cambridge uk bernal took first x ray photographs


crystalline proteins awarded nobel prize chemistry work using x ray techniques study structures penicillin insulin vitamin b british woman ever nobel prize science subject photograph dna photo rosalind franklin rosalind franklin took x ray photograph dna fibre proved key james watson francis crick 's discovery double helix nobel prize physiology medicine watson revealed autobiographic account


discovery structure dna ''the double helix'' used rosalind 's x ray photograph without permission franklin died cancer watson received nobel prize franklin also carried important structural studies carbon coal graphite plant animal viruses isabella karle united states naval research laboratory developed experimental approach mathematical theory crystallography work improved speed accuracy chemical biomedical analysis yet husband jerome shared nobel prize chemistry herbert hauptman outstanding


achievements development direct methods determination crystal structures prize giving bodies showered isabella awards right women written many textbooks research papers field x ray crystallography many years lonsdale edited ''international tables crystallography'' provide information crystal lattices symmetry space groups well mathematical physical chemical data structures olga kennard university cambridge founded ran cambridge crystallographic data centre internationally recognized source structural data small molecules jenny pickworth


glusker british scientist co authored ''crystal structure analysis primer'' first published third edition eleanor dodson australian born biologist began dorothy hodgkin 's technician main instigator behind ccp collaborative computing project currently shares software tools protein crystallographers worldwide reference literature ''international tables crystallography'' eight book series outlines standard notations formatting describing testing crystals series contains books covers analysis methods mathematical procedures determining organic structure x ray crystallography electron diffraction


neutron diffraction international tables focused procedures techniques descriptions list physical properties individual crystals book pages titles books vol ''space group symmetry'' vol ''symmetry relations space groups'' vol b ''reciprocal space'' vol c ''mathematical physical chemical tables'' vol ''physical properties crystals'' vol e ''subperiodic groups'' vol f ''crystallography biological macromolecules'' vol g ''definition exchange crystallographic data'' scientists note see also


abnormal grain growth atomic packing factor beevers lipson strip condensed matter physics crystal engineering crystal growth crystal optics crystal structure crystallite crystallization processes crystallographic database crystallographic point group crystallographic group dynamical theory diffraction electron crystallography euclidean plane isometry fixed points isometry groups euclidean space fractional coordinates group action international year crystallography laser heated pedestal growth materials science metallurgy mineralogy modeling polymer crystals neutron crystallography neutron diffraction opal neutron diffraction ill nmr crystallography permutation group point group precession electron diffraction quantum mineralogy quasicrystal solid state chemistry space group symmetric group x ray crystallography lattice constant references


external links http wwwamercrystalassnorg american crystallographic association https wwwxtaliqfrcsices cristalografia index enhtml learning crystallography easily https webarchiveorg web http cst wwwnrlnavymil lattice spcgrp crystal lattice structures https wwwyoutubecom watchv uqqlwyv vqi years crystallography royal institution animation http wwwvegaorguk vega science trust interviews crystallography freeview video interviews max perutz rober huber aaron klug https webarchiveorg web http wwwiucrorg iucr top comm cteach pamphletshtml commission crystallographic teaching pamphlets https webarchiveorg web http wwwmcbmmameslabgov indexhtml ames laboratory us doe crystallography research resources http wwwiucrorg international union crystallography http rigborg history history research crystallography timeline interactive crystallography timeline royal institution http wwwnaturecom milestones milecrystal indexhtml nature milestones crystallography http journalsiucrorg issues indexhtml crystallography st century editorial acta crystallographica section chemistry condensed matter physics instrumental analysis materials science neutron related techniques synchrotron related techniques


two modern dancers members contemporary dance troop performing group routine saman dance indonesia dance characterized fast paced rhythm common harmony dancers '''dance''' performing art form consisting sequences movement either improvised purposefully selected movement aesthetic often symbolic value ref br br dance transient mode expression performed given form style human body moving space dance occurs purposefully selected controlled rhythmic movements resulting phenomenon recognized dance performer


called performance concert dance intended primarily spectacle usually performance upon stage virtuoso dancers often tells story perhaps using mime costume scenery else may simply interpret musical accompaniment often specially composed performed theatre setting requirement examples western ballet modern dance classical indian dance bharatanatyam chinese japanese song dance dramas dragon dance classical forms centered upon dance alone performance dance may also appear opera


forms musical theatre participatory dance hand whether folk dance social dance group dance line circle chain square dance partner dance common western ballroom dancing undertaken primarily common purpose social interaction exercise building flexibility participants rather serve benefit onlookers dance seldom narrative group dance ''corps de ballet'' social partner dance ''pas de deux'' differ profoundly even solo dance may


undertaken solely satisfaction dancer participatory dancers often employ movements steps example rave culture electronic dance music vast crowds may engage free dance uncoordinated around hand cultures lay strict rules particular dances example men women children may must participate history mesolithic dancers bhimbetka archeological evidence early dance includes year old paintings india rock shelters bhimbetka egyptian tomb paintings depicting dancing figures dated c bc


proposed invention written languages dance important part oral performance methods passing stories one generation next ref name lecomte nathalie comte europe encyclopedia early modern world ed jonathan dewald vol new york charles scribner 's sons pp nbsp ref use dance ecstatic trance states healing rituals observed today many contemporary primitive cultures brazilian rainforest kalahari desert thought another early factor social development dance ref name guenther guenther mathias georg


oracle bones dance described ''l shi chunqiu'' ref name aesthetic tradition ref primitive dance ancient china associated sorcery shamanic rituals greek bronze statuette veiled masked dancer rd nd century bc alexandria egypt first millennium bce india many texts composed attempted codify aspects daily life bharata muni 's ''natyashastra'' literally '' text dramaturgy '' one earlier texts mainly deals drama dance plays important part indian culture categorizes dance four types secular ritual abstract interpretive four regional varieties


text elaborates various hand gestures ''mudras'' classifies movements various limbs steps strong continuous tradition dance since continued india modern times continues play role culture ritual notably bollywood entertainment industry many contemporary dance forms likewise traced back historical traditional ceremonial ethnic dance music two women dance pop music concert sofia bulgaria dance generally however exclusively performed accompaniment music may may performed ''in time''


music dance tap dance may provide audible accompaniment place addition music many early forms music dance created frequently performed together notable examples traditional dance music couplings include jig waltz tango disco salsa musical genres parallel dance form baroque music baroque dance varieties dance music may share nomenclature developed separately classical music classical ballet choreography music go hand hand complement


metre basic rhythmic pattern basic pulse roughly equal duration simple step gesture basic tango rhythm dances generally characteristic tempo rhythmic pattern tango example usually danced time approximately beats per minute basic slow step called slow lasts one beat full right left step equal one measure basic forward backward walk dance counted slow slow many additional figures counted slow quick quick musical rhythms


defined pattern strong weak beats repetitive body movements often depend alternating strong weak muscular movements ref name kirstein lincoln kirstein ''dance'' dance horizons incorporated new york p ref given alternation left right forward backward rise fall along bilateral symmetry human body natural many dances much music duple quadruple meter since movements require time one phase longer time required lift hammer strike dance rhythms fall


musical rhythm still found renaissance europe works dancing master guglielmo ebreo da pesaro speaks dance physical movement arises expresses inward spiritual motion agreeing measures perfect concords harmony fall upon human ear ref name kirstein earlier mechthild magdeburg seizing upon dance symbol holy life foreshadowed jesus' saying piped ye danced writes thoinot arbeau 's celebrated th century dance treatise ''orch sographie'' indeed begins definitions eighty distinct drum rhythms helen moller waltz''


camille claudel cast shown dance represented ages emerged response music yet lincoln kirstein implied least likely primitive music arose dance shawn concurs stating dance first art human race matrix arts grew even metre poetry today result accents necessitated body movement dancing reciting performed simultaneously ref name shawn assertion somewhat supported


whole organism develop special training designed regulate nervous reactions effect co ordination muscles nerves ultimately seek connections art music art dance formulated system eurhythmics concluded musical rhythm transposition sound movements dynamisms spontaneously involuntarily expressing emotion hence though doubtless shawn asserts quite possible develop dance without music music perfectly capable standing feet without assistance dance nevertheless


two arts always related relationship profitable dance music precedence one art moot point common ballad measures hymns folk songs takes name dance carol originally circle dance many purely musical pieces named waltz minuet example many concert dances produced based upon abstract musical pieces '' part inventions adams violin concerto'' ''andantino'' similarly poems often structured named dances


musical works dance music drawn conception measure metre poetry shawn quotes approval statement dalcroze art musical rhythm consists differentiating combining time durations pauses accents according physiological law plastic rhythm ie dance designate movement space interpret long time values slow movements short ones quick movements regulate pauses divers successions express sound accentuations multiple nuances additions bodily weight means muscular innervations shawn nevertheless points


dancers theatrical concert dance like opera generally depends large scale form upon narrative dramatic structure movements gestures choreography primarily intended mime personality aims characters part plot theatrical requirements tend towards longer freer movements usual non narrative dance styles hand ''ballet blanc'' developed th century allows interludes rhythmic dance developed entirely plotless ballets th century allowed fast rhythmic dance steps ''petit allegro'' well known example


''the cygnets' dance'' act two ''swan lake'' ballet developed courtly dramatic productions th th century france italy time dancers performed dances developed familiar musical suite defined definite rhythms closely identified dance appeared character dances era romantic nationalism ballet reached widespread vogue romantic era accompanied larger orchestra grander musical conceptions lend easily rhythmic clarity dance emphasised dramatic mime broader concept


rhythm needed rudolf laban terms rhythm shape movement communicates character emotion intention certain scenes required exact synchronisation step music essential dance styles laban modern europeans seemed totally unable grasp meaning primitive rhythmic movements situation began change th century productions igor stravinsky 's ''the rite spring'' new rhythmic language evoking primal feelings primitive past indian classical dance styles like ballet often dramatic form


similar complementarity narrative expression pure dance case two separately defined though always separately performed rhythmic elements abstract technical known ''nritta'' expressive dance '' nritya '' though closely tied rhythmic system ''tala'' teachers adapted spoken rhythmic mnemonic system called ''bol'' needs dancers japanese classical dance theatre styles kabuki noh like indian dance drama distinguish narrative abstract dance productions three main categories kabuki ''jidaimono'' historical ' 'sewamono'' domestic ' 'shosagoto'' dance pieces ref


dance rhythm dancers' feet may even form essential part music tap dance african dance example rooted fixed basic steps may also allow high degree rhythmic interpretation feet trunk mark basic pulse cross rhythms picked shoulders knees head best dancers simultaneously giving plastic expression elements polyrhythmic pattern cultural traditions africa kuduro angolan dance ugandan youth dance cultural celebration peace dance africa deeply integrated


society major events community frequently reflected dances dances performed births funerals weddings wars ref name welshhanley ref traditional dances impart cultural morals including religious traditions sexual standards give vent repressed emotions grief motivate community members cooperate whether fighting wars grinding grain enact spiritual rituals contribute social cohesiveness ref name hanna ref thousands dances performed around continent may divided traditional neotraditional classical styles folkloric dances particular society dances created recently imitation traditional styles dances transmitted


formally schools private lessons ref name welshhanley african dance altered many forces european missionaries colonialist governments often suppressed local dance traditions licentious distracting ref name hanna dance contemporary african cultures still serves traditional functions new contexts dance may celebrate inauguration hospital build community rural migrants unfamiliar cities incorporated christian church ceremonies ref name hanna asia indian classical dancer indian classical dances varying degrees rooted ''natyashastra'' therefore share common features example ''mudra' 's


hand positions body positions leg movement inclusion dramatic expressive acting abhinaya indian classical music provides accompaniment dancers nearly styles wear bells around ankles counterpoint complement percussion many regional varieties indian classical dance dances like '' odra magadhi '' decades long debate traced present day mithila odisha region 's dance form odissi orissi indicate influence dances cultural interactions different regions punjab area overlapping india pakistan place origin bhangra widely known


style music dance mostly related ancient harvest celebrations love patriotism social issues music coordinated musical instrument called 'dhol' bhangra music dance celebration harvest people beat dhol drum sing boliyaan lyrics dance developed vaisakhi festival sikhs dances sri lanka include devil dances ''yakun natima'' carefully crafted ritual reaching far back sri lanka 's pre buddhist past combines ancient ayurvedic concepts disease causation psychological


manipulation combines many aspects including sinhalese cosmology influence seen classical dances sri lanka indonesian balinese dancer indonesian dances reflect richness diversity indonesian ethnic groups cultures ethnic groups indonesia seen cultural roots austronesian melanesian peoples various cultural influences asia west dances indonesia originate ritual movements religious ceremonies kind dance usually begins rituals war dances shaman dances cure ward disease dances


call rain types dances acceptance dharma religion st century indonesia hinduism buddhist rituals celebrated various artistic performances hindu epics ramayana mahabharata also panji became inspiration shown dance drama called sendratari resembling ballet western tradition elaborate highly stylized dance method invented survived day especially islands java bali javanese wayang wong dance takes footage ramayana mahabharata episodes dance different


indian version indonesian dances pay much attention mudras indian dances even show local forms sacred javanese ritual dance bedhaya believed date back majapahit period th century even earlier dance originated ritual dances performed virgin girls worship hindu gods shiva brahma vishnu bali dance become integral part sacred hindu dharma rituals experts believe balinese dance comes older dance tradition java reliefs temples east java


th century feature crowns headdresses similar headdresses used balinese dance today islam began spread indonesian archipelago indigenous dances dharma dances still popular artists dancers still use styles previous era replacing stories islamic interpretations clothing closed according islamic teachings ref name folk dances indonesia ref dances middle east usually traditional forms circle dancing modernized extent would include dabke tamzara assyrian folk dance kurdish dance armenian dance turkish dance among others ref


name badley pp badley bill zein al jundi europe meets asia broughton simon ellingham mark mcconnachie james duane orla ed world music vol africa europe middle east pp rough guides ltd penguin books ref forms dances would usually involve participants engaging holding hands arms depending style dance would make rhythmic moves legs shoulders curve around dance floor head dance would generally hold cane handkerchief ref name badley pp


europe north america ''dance bougival'' pierre auguste renoir folk dances vary across europe may date back hundreds thousands years many features common group participation led caller hand holding arm linking participants fixed musical forms known caroles ref name lee ref maypole dance common many nations others c ilidh polka deeply rooted single culture european folk dances square dance brought new world subsequently became part american culture


paris shortly thereafter first institutionalized ballet troupe associated academy formed troupe began male ensemble opened include women well ref name lecomte th century concert dance brought explosion innovation dance style characterized exploration freer technique early pioneers became known modern dance include loie fuller isadora duncan mary wigman ruth st denis relationship music dance serves basis eurhythmics devised emile jaques dalcroze influential development modern dance modern


relationship rock roll music rock roll dance global influence dance styles fusing classical ballet technique african american dance also appeared st century including hiplet ref name kourlas ref latin america street samba dancers perform carnival parades contests dance central latin american social life culture brazilian samba argentinian tango cuban salsa internationally popular partner dances national dances merengue cueca plena jarabe joropo marinera cumbia bachata others important components respective countries' cultures ref name chasteen ref traditional carnival festivals incorporate dances enormous celebrations ref


name musmonhanley ref dance played important role forging collective identity among many cultural ethnic groups latin america ref name delgadomu oz ref dance served unite many african european indigenous peoples region ref name chasteen certain dance genres capoeira body movements especially characteristic ''quebradas'' pelvis swings variously banned celebrated throughout latin american history ref name delgadomu oz education dance studies offered arts humanities programs many higher education institutions universities offer bachelor arts higher academic degrees dance dance study curriculum may encompass


diverse range courses topics including dance practice performance choreography ethnochoreology kinesiology dance notation dance therapy recently dance movement therapy integrated schools math lessons students learning disabilities emotional behavioral disabilities attention deficit hyperactivity disorder adhd dancer practices dance studio primary setting training classical dance many styles occupations dancers professional dancers usually employed contract particular performances productions professional life dancer generally one constantly changing work situations strong competitive pressure low


pay consequently professional dancers often must supplement incomes achieve financial stability us many professional dancers belong unions american guild musical artists screen actors guild actors' equity association establish working conditions minimum salaries members professional dancers must possess large amounts athleticism lead successful career advantageous versatile many styles dance strong technical background utilize forms physical training remain fit healthy study focused dance participation attendance denmark found


dancers typically attend dance performances lower income non dancers study also found dancers consume books video games significantly using internet degree non dancers teachers dance teachers typically focus teaching dance performance coaching competitive dancers typically performance experience types dance teach coach example dancesport teachers coaches often tournament dancers former dancesport performers dance teachers may self employed employed dance schools general education institutions dance programs work


university programs schools associated professional classical dance eg ballet modern dance companies others employed smaller privately owned dance schools offer dance training performance coaching various types dance choreographers choreographers ones design dancing movements within dance often university trained typically employed particular projects rarely may work contract resident choreographer specific dance company competitions amateur dancesport competition featuring viennese waltz '' 'dance competition''' organized event contestants


perform dances judge judges awards cases monetary prizes several major types dance competitions distinguished primarily style styles dances performed major types dance competitions include '''dancesport''' focused exclusively ballroom latin dance '''competitive dance''' variety theater dance styles acro ballet jazz hip hop lyrical tap permitted '''single style''' competitions highland dance dance team irish dance permit single dance style '''open''' competitions permit wide variety dance styles


example tv program ''so think dance'' '''olympic''' dance trying part olympic sport since addition numerous dance competitions shows presented television mass media gallery gallery mode packed hover heights px file irish dancers team costume davis academy usajpg '''folk dance''' trio irish stepdancers performing competition file rka vanemuise suures majas tants kodukotusjpg folk dance estonia file nwfusionangelaleapjpg contemporary dancer performs stag split leap file nwfusion jpg '''dance partnering''' male dancer assists female dancer performing arabesque part


copenhagen denmark file popping dancergif hip hop dancer demonstrates popping file striptease pole dancing belovskaya belgorodskaya oblast russiajpg '''erotic dance''' pole dancer performs routine file spark fire dance art ice jpg '''prop dance''' fire dancer performance file imdt jpg '''modern dance''' female dancer performs leg split balanced back partner file belogolovtsev abderahmanjpg '''stage dance''' professional dancer bolshoi theatre file la bailaora josefa vargas jpg nineteenth century artist 's representation flamenco dancer file jpg '''ritual dance''' armenian folk dancers celebrate neo pagan new year file samba atlason jakobsdottir jpg latin ballroom couple perform


articles list dance awards human body notes references reading abra allison going palais social cultural history dancing dance halls britain ''contemporary british history'' sep pp nbsp blogg martin ''dance christian faith form knowing'' lutterworth press carter ''the routledge dance studies reader'' routledge cohen j ''dance theatre art source readings dance history present'' princeton book co daly ''critical gestures writings dance culture'' wesleyan university press miller


james l ''measures wisdom cosmic dance classical christian antiquity'' university toronto press external links https wwwgutenbergorg ebooks historic illustrations dancing bc ad project gutenberg https webarchiveorg web http wwwdancemuseumorg united states national museum dance hall fame entertainment occupations theatrical occupations articles containing video clips performing arts


ref ref group nb whether dentists referred doctor subject geographic variation example called doctor us uk dentists traditionally referred mister identified barber surgeons physicians surgeons uk see surgeon titles however uk dentists refer doctor although considered potentially misleading british public single report see costley fawcett ref type

Applied science
Medicine and health
Dentistry


profession activity sector health care anatomy physiology pathology medicine pharmacology surgery competencies formation dental degree employment field related occupation meshid ops othercodes hcpcslevel


oral surgeon dental assistant removing wisdom tooth '''dentistry''' also known '' 'dental medicine''' '''oral medicine''' branch medicine consists study diagnosis prevention treatment diseases disorders conditions oral cavity mouth commonly dentition development arrangement teeth well oral mucosa adjacent related structures tissues particularly associated maxillofacial jaw facial area field dentistry dental medicine includes teeth well aspects craniofacial complex including temporomandibular joint


supporting muscular lymphatic nervous vascular anatomical structures practitioner called dentist dentistry often also understood subsume largely defunct medical specialty stomatology study mouth disorders diseases reason two terms used interchangeably certain regions instance australia stomatology considered specialty dentistry however specialties oral maxillofacial surgery facial reconstruction may require medical dental degrees accomplish dentistry branches medicine european history considered stemmed


trade barber surgeons however fields evolved since heavier emphasis life sciences evidence based research evidence based practice dental treatments carried dental team often consists dentist dental auxiliaries dental assistants dental hygienists dental technicians well dental therapists dentists either work private practices primary care dental hospitals secondary care institutions prisons armed forces bases etc history dentistry almost ancient history humanity civilization earliest evidence dating bc bc ref name bbc ref skeletal


remains mehgarh pakistan dated time show evidence teeth drilled flint tools remove decay method found surprisingly effective ref name bbc dentistry thought first specialization medicine gone develop accredited degree specialisations ref name suddick ref modern movement evidence based dentistry calls use high quality scientific research evidence guide decision making manual tooth conservation use fluoride water treatment fluoride toothpaste dealing oral diseases tooth decay


periodontitis well systematic diseases osteoporosis diabetes celiac disease cancer hiv aids could also affect oral cavity practices relevant evidence based dentistry include radiology mouth inspect teeth deformity oral malaises haematology study blood avoid bleeding complications dental surgery cardiology due various severe complications arising dental surgery patients heart disease etc terminology term dentistry comes ' 'dentist'' comes french ' 'dentiste'' comes french latin words tooth term associated scientific study teeth '''odontology'''


study structure development abnormalities teeth dental treatment dentistry usually encompasses practices related oral cavity ref name gambhir ref according world health organization oral diseases major public health problems due high incidence prevalence across globe disadvantaged affected socio economic groups ref name whooraldisease ref majority dental treatments carried prevent treat two common oral diseases dental caries tooth decay periodontal disease gum disease pyorrhea common treatments involve restoration teeth extraction surgical removal


teeth scaling root planing endodontic root canal treatment cosmetic dentistry dentists united states undergo least three years undergraduate studies nearly complete bachelor 's degree schooling followed four years dental school qualify doctor dental surgery dds doctor dental medicine dmd specialization dentistry available fields anesthesiology dental public health endodontics oral radiology oral maxillofacial surgery oral medicine orofacial pain pathology orthodontics pediatric dentistry periodontics prosthodontics nature general training carry


majority dental treatments restorative fillings crowns bridges prosthetic dentures endodontic root canal therapy periodontal gum therapy extraction teeth well performing examinations radiographs x rays diagnosis dentists also prescribe medications antibiotics sedatives drugs used patient management depending licensing boards general dentists may required complete additional training perform sedation dental implants etc irreversible enamel defects caused untreated celiac disease may clue diagnosis even absence gastrointestinal symptoms often confused fluorosis tetracycline


discoloration acid reflux causes ref name nihcddiagnosis ref ref name nihcddentalenamel http celiacnihgov pdf dental enamel defects pdf dental enamel defects celiac disease national institute health nih ref ref name pastorecarroccio ref national institutes health include dental exam diagnostic protocol celiac disease ref name nihcddiagnosis dentists also encourage prevention oral diseases proper hygiene regular twice yearly checkups professional cleaning evaluation oral infections inflammations may affect overall health conditions oral cavity may indicative systemic diseases osteoporosis diabetes celiac disease cancer ref name gambhir ref name nihcddiagnosis ref name estrellaboynton ref ref name dafonseca ref many studies also shown


gum disease associated increased risk diabetes heart disease preterm birth concept oral health affect systemic health disease referred oral systemic health education licensing sagittal cross section molar tooth crown root enamel dentin dentin tubules pulp chamber blood vessels nerve periodontal ligament apex periapical region alveolar bone early dental chair pioneer west museum shamrock texas john harris started world 's first dental school bainbridge ohio helped establish dentistry


health profession opened february today dental museum first dental college baltimore college dental surgery opened baltimore maryland us second united states ohio college dental surgery established cincinnati ohio philadelphia college dental surgery followed temple university accepted bid incorporate school studies show dentists graduated different countries even different dental schools one country may make different clinical decisions clinical condition


example dentists graduated israeli dental schools may recommend removal asymptomatic impacted third molar wisdom teeth often dentists graduated latin american eastern european dental schools united kingdom first dental schools london school dental surgery metropolitan school dental science london opened ref name medhist ref british dentists act dentists register limited title dentist dental surgeon qualified registered practitioners ref name years gelbier stanley http wwwnaturecom bdj journal v n full ahtml years developments dentistry british dental journal


mandatory many dentists choose complete internship residency focusing specific aspects dental care received dental degree specialties modern dental clinic lappeenranta finland dentists undertake training initial degree order specialize exactly subjects recognized dental registration bodies varies according location examples include cosmetic dentistry focuses improving appearance mouth teeth smile anesthesiology specialty dentistry deals advanced use general anesthesia sedation pain management facilitate dental procedures dental public


health study epidemiology social health policies relevant oral health endodontics also called ''endodontology'' root canal therapy study diseases dental pulp periapical tissues forensic odontology gathering use dental evidence law may performed dentist experience training field function forensic dentist primarily documentation verification identity geriatric dentistry ''geriodontics'' delivery dental care older adults involving diagnosis prevention treatment problems associated normal aging age related diseases


part interdisciplinary team health care professionals oral maxillofacial pathology study diagnosis sometimes treatment oral maxillofacial related diseases oral maxillofacial radiology study radiologic interpretation oral maxillofacial diseases oral maxillofacial surgery also called ''oral surgery'' extractions implants surgery jaws mouth face ref group nb scope oral maxillofacial surgery variable countries medical dental degree required training scope includes head neck oncology craniofacial deformity ref oral biology research


maxillofacial prosthetics discipline originally concerned rehabilitation patients congenital facial oral defects cleft lip palate patients born underdeveloped ear microtia today maxillofacial prosthodontists return function esthetics patients acquired defects secondary surgical removal head neck tumors secondary trauma war motor vehicle accidents special needs dentistry also called ' 'special care dentistry'' dentistry developmental acquired disabilities sports dentistry branch sports medicine dealing prevention treatment dental injuries oral


diseases associated sports exercise sports dentist works individual consultant member sports medicine team veterinary dentistry field dentistry applied care animals specialty veterinary medicine history wealthy patient falling tooth extracted vigour fashionable dentist c history dentistry ''farmer dentist'' johann liss tooth decay low pre agricultural societies advent farming society years ago correlated increase tooth decay cavities


infected tooth italy partially cleaned flint tools years old represents oldest known dentistry although study suggests years ago neanderthals already used rudimentary dentistry tools indus valley yielded evidence dentistry practised far back bc stone age ref name coppa coppa et al http wwwnaturecom nature journal v n pdf apdf early neolithic tradition dentistry pdf ''nature'' volume april ref neolithic site mehrgarh pakistan 's south western province balochistan indicates form dentistry involved curing tooth related disorders bow


code hammurabi referenced dental extraction twice related punishment examination remains ancient egyptians greco romans reveals early attempts dental prosthetics however possible prosthetics prepared death aesthetic reasons ref name blomstedt ancient greek scholars hippocrates aristotle wrote dentistry including eruption pattern teeth treating decayed teeth gum disease extracting teeth forceps using wires stabilize loose teeth fractured jaws ref name history dentistry ref say first use dental appliances bridges comes etruscans early


bc ancient egypt hesy ra first named dentist greatest teeth egyptians bound replacement teeth together gold wire roman medical writer cornelius celsus wrote extensively oral diseases well dental treatments narcotic containing emollients astringents earliest dental amalgams first documented tang dynasty medical text written chinese physician su kung appeared germany ref name bj rklund ref ref name czarnetzki ref islamic golden age dentistry discussed several famous books medicine canon medicine written avicenna al tasreef


al zahrawi considered greatest surgeon middle ages avicenna said jaw fracture reduced according occlusal guidance teeth principle still valid modern times al zahrawi made lot surgical tools resemble modern tools historically dental extractions used treat variety illnesses middle ages throughout th century dentistry profession often dental procedures performed barbers general physicians barbers usually limited practice extracting teeth alleviated pain associated


english called operator teeth charles allen ref name bdatimeline http wwwbdaorg museum story dentistry timelineaspx story dentistry dental history timeline hosted british dental association website page accessed march ref united kingdom formal qualification providers dental treatment practice dentistry limited professionally qualified royal commission national health service reported twice many registered dentists per population uk


dentistry introduced dental fillings treatment dental cavities asserted sugar derived acids like tartaric acid responsible dental decay also suggested tumors surrounding teeth gums could appear later stages tooth decay ref name besombes ref ref name weinberger ref panoramic radiograph historic dental implants made fauchard pioneer dental prosthesis invented many methods replace lost teeth suggested substitutes could made carved blocks ivory bone also introduced dental braces although initially made gold discovered


teeth position could corrected teeth would follow pattern wires waxed linen silk threads usually employed fasten braces contributions world dental science consist primarily publication le chirurgien dentiste surgeon dentist french text included basic oral anatomy function dental construction various operative restorative techniques effectively separated dentistry wider category surgery ref name besombes ref name weinberger modern dentist 's chair fauchard study dentistry rapidly expanded two important books ''natural history human teeth''


''practical treatise diseases teeth'' published british surgeon john hunter entered period collaboration london based dentist james spence began theorise possibility tooth transplants one person another realised chances successful tooth transplant initially least would improved donor tooth fresh possible matched size recipient principles still used transplantation internal organs hunter conducted series pioneering operations


attempted tooth transplant although donated teeth never properly bonded recipients' gums one hunter 's patients stated three lasted six years remarkable achievement period major advances science made th century dentistry evolved trade profession profession came government regulation end th century uk dentist act passed british dental association formed year francis brodie imlach first ever dentist


elected president royal college surgeons edinburgh raising dentistry onto par clinical surgery first time hazards modern dentistry long term occupational noise exposure contribute permanent hearing loss referred noise induced hearing loss nihl tinnitus noise exposure cause excessive stimulation hearing mechanism damages delicate structures inner ear nihl occur individual exposed sound levels dba according occupational safety health administration osha regulations state permissible noise exposure levels


individuals dba national institute occupational safety health niosh exposure limits set dba exposures dba considered hazardous time limits placed long individual stay environment dba causes hearing loss osha places limitation hours dba exposure time becomes shorter dba level increases within field dentistry variety cleaning tools used including piezoelectric sonic scalers ultrasonic scalers cleaners majority


tools exceed dba prolonged exposure many years lead hearing loss complaints tinnitus dentists reported using personal hearing protective devices could offset potential hearing loss tinnitus evidence based dentistry movement modern dentistry place greater emphasis high quality scientific evidence decision making evidence based dentistry ebd uses current scientific evidence guide decisions approach oral health requires application examination relevant scientific data related patient 's oral medical health along dentist 's professional skill


expertise ebd allows dentists stay date latest procedures patients receive improved treatment new paradigm medical education designed incorporate current research education practice developed help practitioners provide best care patients first introduced gordon guyatt evidence based medicine working group mcmaster university ontario canada part larger movement toward evidence based medicine evidence based practices especially since major part dentistry involves dealing oral systemic diseases issues relevant


dental field terms evidence based research evidence based practice include population oral health dental clinical practice tooth morphology etc dental chair university michigan school dentistry ethical medicolegal issues dentistry unique requires dental students competence based clinical skills acquired supervised specialized laboratory training direct patient care necessitates need scientific professional basis care foundation extensive research based education accreditation dental schools plays large role enhancing quality professionalism


dental education see also list dental organizations dental aerosol dental instrument notes references external links


juno minerva venus isaac oliver c '''divinity''' '' 'divine''' things either related devoted proceeding deity ref name dictionarycom http dictionaryreferencecom browse divine divine dictionarycom ref divine may loosely defined used different belief systems root word ' 'divine'' literally godly use varies significantly depending deity discussed specific related academic terms see divinity academic discipline divine anglican usages divinity quality two distinct usages divine force power


powers forces universal transcend human capacities divinity applied mortals qualities individuals considered special access relationship divine overlap occurs usages deities godly entities often identical identified powers forces credited nbsp many cases deity merely power force personified nbsp powers forces may extended granted mortal individuals instance jehovah closely associated storms thunder throughout much old testament


said speak thunder thunder seen token anger power extended prophets like moses samuel caused thunderous storms rain enemies divinity always carries connotations goodness beauty beneficence justice positive pro social attributes monotheistic faiths equivalent cohort malefic supernatural beings powers demons devils afreet etc conventionally referred divine ' 'demonic'' often used instead pantheistic polytheistic faiths make distinction gods beings transcendent power often


complex ignoble even irrational motivations acts note terms ' 'demon'' ' 'demonic'' used monotheistic faiths antonyms ' 'divine'' fact derived greek word ' 'daim n'' translates ' 'divinity'' three distinct usages ' 'divinity'' ' 'divine'' religious discourse entity monotheistic faiths word ' 'divinity'' often used refer singular god central faith often word takes definite article capitalized nbsp '' divinity '' nbsp though proper name definitive honorific ''divine'' nbsp


forces may invoked independently leads second usage word ' 'divine'' less common usage ' 'divinity'' refer operation transcendent power world direct form operation transcendent power implies form divine intervention pan polytheistic faiths usually implies direct action one god another course human events greek legend instance poseidon god sea raised storms blew odysseus 's craft course return journey


japanese tradition holds god sent wind saved mongol invasion prayers propitiations often offered specific gods pantheisms garner favorable interventions particular enterprises eg safe journeys success war season bountiful crops many faiths around world nbsp japanese shinto chinese traditional religion certain african practices faiths derived caribbean native american beliefs nbsp hold ancestral household deities offer daily protection blessings monotheistic religions divine intervention may take direct forms miracles visions intercessions blessed figures transcendent


force power may also operate subtle indirect paths monotheistic faiths generally support version divine providence acknowledges divinity faith profound unknowable plan always unfolding world unforeseeable overwhelming seemingly unjust events often thrown 'the divine' deferences like muslim ''inshallah'' 'as god wills it' christian 'god works mysterious ways' often faiths hold possibility divine retribution well divinity unexpectedly bring evil doers justice conventional workings world


subtle redressing minor personal wrongs large scale havoc destruction sodom gomorrah biblical great flood faiths even subtle doctrine ''karma'' shared buddhism hinduism divine law similar divine retribution without connotation punishment acts good bad intentional unintentional reflect back us part natural working universe philosophical taoism also proposes transcendent operant principle nbsp transliterated english ''tao'' ' 'dao'' meaning 'the way' nbsp neither entity


numerous practices peace love new age thinking mortals third usage extensions divinity divine power credited living mortal individuals political leaders known claimed actual divinity certain early societies nbsp ancient egyptian pharaohs premier case nbsp taking role objects worship credited superhuman status powers commonly pertinent recent history leaders merely claim form divine mandate suggesting rule accordance god doctrine divine right


kings introduced late th century proposing kings rule divine decree japanese emperors ruled divine mandate inception japanese constitution world war ii less politically faiths number people believed touched divine forces saints prophets heroes oracles martyrs enlightened beings among others saint francis assisi catholicism said received instruction directly god believed grants plenary indulgence confess sins visit chapel appropriate


day greek mythology achilles' mother bathed river styx give immortality hercules nbsp son zeus nbsp inherited near godly powers religious taoism lao tsu venerated saint powers various individuals buddhist faith beginning siddhartha considered enlightened religious forms buddhism credited divine powers christ bible said god 's son said performed divine miracles general mortals divine qualities carefully distinguished deity deities


live needs brought fore appropriate spiritual practices christianity new testament greek word ''theion'' douay version translated divinity examples acts therefore offspring god must suppose divinity like unto gold silver stone graving art device man romans invisible things creation world clearly seen understood things made eternal power also divinity


inexcusable revelation saying loud voice lamb slain worthy receive power divinity wisdom strength honour glory benediction word translated either deity godhead divinity greek new testament also greek word ''theot tos'' one verse contains colossians quia ipso inhabitat omnis plenitudo divinitatis divinity corporaliter vulgate dwelleth fulness godhead bodily kjv fullness divine


quality dwells bodily nwt fullness deity lives bodily form net full content divine nature lives christ tev word divine new testament greek word ''theias'' adjective form divinity biblical examples king james bible peter according divine power hath given unto us things pertain unto life godliness knowledge hath called us glory virtue peter whereby given unto us exceeding great


also introduced existence heavenly mother king follett discourse little acknowledged known beyond existence mormons hold belief divine potential humanity smith taught form divinization mortal men women become like god salvation exaltation lorenzo snow succinctly summarized using couplet often repeated within lds church man god god man may epicureanism epicurean philosophy admits existence gods since accept supernatural


teaches things material posits theology epicurean gods physical beings whose bodies made atoms live region words intermundia needless say gods need worship creators maintainers cosmos answer prayers therefore epicurean theology belongs properly realm speculation super evolved intelligent extraterrestrial life however epicurus samos founder school recognized utility religiosity central unifying symbols adamant requirement disciples


pious established two taboos concerning conception gods believe gods immortal indestructible fully self sufficient blessed happy blissful outside epicureans free speculate concerning nature highest life forms cosmos see also apotheosis christology deity divinization christian ho'oponopono morrnah section list deities sacred notes references external links conceptions god religious belief doctrine philosophy religion deities


'''developmental biology''' study process animals plants grow develop developmental biology also encompasses biology regeneration asexual reproduction metamorphosis growth differentiation stem cells adult organism perspectives main processes involved embryonic development animals '''tissue patterning''' via regional specification patterned cell differentiation tissue growth tissue morphogenesis regional specification refers processes create spatial pattern ball sheet initially similar cells generally involves action cytoplasmic determinants located within parts

Natural science
Biology
Developmental biology


fertilized egg inductive signals emitted signaling centers embryo early stages regional specification generate functional differentiated cells cell populations committed develop specific region part organism defined expression specific combinations transcription factors cell differentiation relates specifically formation functional cell types nerve muscle secretory epithelia etc differentiated cells contain large amounts specific proteins associated cell function morphogenesis relates formation three dimensional shape mainly involves orchestrated movements cell sheets


individual cells morphogenesis important creating three germ layers early embryo ectoderm mesoderm endoderm building complex structures organ development tissue growth involves overall increase tissue size also differential growth parts allometry contributes morphogenesis growth mostly occurs cell proliferation also changes cell size deposition extracellular materials development plants involves similar processes animals however plant cells mostly immotile morphogenesis achieved differential growth without cell movements also


inductive signals genes involved different control animal development developmental processes cell differentiation notch delta system neurogenesis slack essential dev biol fig cell differentiation process whereby different functional cell types arise development example neurons muscle fibers hepatocytes liver cells well known types differentiated cells differentiated cells usually produce large amounts proteins required specific function gives characteristic appearance enables recognized light microscope genes encoding proteins


highly active typically chromatin structure open allowing access transcription enzymes specific transcription factors bind regulatory sequences dna order activate gene expression example neurod key transcription factor neuronal differentiation myogenin muscle differentiation hnf hepatocyte differentiation cell differentiation usually final stage development preceded several states commitment visibly differentiated single tissue formed single type progenitor cell stem cell often consists several differentiated cell types control formation involves


process lateral inhibition based properties notch signaling pathway example neural plate embryo system operates generate population neuronal precursor cells neurod highly expressed regeneration regeneration indicates ability regrow missing part prevalent amongst plants show continuous growth also among colonial animals hydroids ascidians interest developmental biologists shown regeneration parts free living animals particular four models subject much investigation


two ability regenerate whole bodies ''hydra'' regenerate part polyp small fragment planarian worms usually regenerate heads tails ref name reddien pw alvarado ref examples continuous cell turnover fed stem cells least planaria least stem cells shown pluripotent two models show distal regeneration appendages insect appendages usually legs hemimetabolous insects cricket limbs urodele


amphibians considerable information available amphibian limb regeneration known cell type regenerates except connective tissues considerable interconversion cartilage dermis tendons terms pattern structures controlled activation signals active embryo still debate old question whether regeneration pristine adaptive property former case improved knowledge might expect able improve regenerative ability humans latter instance regeneration


presumed arisen natural selection circumstances particular species general rules would expected embryonic development animals generalized scheme embryonic development slack essential developmental biology fig initial stages human embryogenesis sperm egg fuse process fertilization form fertilized egg zygote undergoes period divisions form ball sheet similar cells called blastula blastoderm cell divisions usually rapid growth daughter cells half size mother


cell whole embryo stays size called cleavage divisions mouse epiblast primordial germ cells see figure initial stages human embryogenesis undergo extensive epigenetic reprogramming ref name pmid ref process involves genome wide dna demethylation chromatin reorganization epigenetic imprint erasure leading totipotency ref name pmid dna demethylation carried process utilizes dna base excision repair pathway ref name pmid ref morphogenetic movements convert cell mass three layered structure consisting multicellular sheets called ectoderm mesoderm endoderm sheets known germ layers process


gastrulation cleavage gastrulation first regional specification events occur addition formation three germ layers often generate extraembryonic structures mammalian placenta needed support nutrition embryo also establish differences commitment along anteroposterior axis head trunk tail regional specification initiated presence cytoplasmic determinants one part zygote cells contain determinant become signaling center emit inducing factor inducing factor produced one place diffuses away decays


forms concentration gradient high near source cells low away remaining cells embryo contain determinant competent respond different concentrations upregulating specific developmental control genes results series zones becoming set arranged progressively greater distance signaling center zone different combination developmental control genes upregulated genes encode transcription factors upregulate new combinations gene activity region among functions transcription factors control expression genes conferring specific adhesive motility properties


cells active different morphogenetic properties cells germ layer move form sheets ectoderm ends outside mesoderm middle endoderm inside morphogenetic movements change shape structure embryo bringing cell sheets new spatial relationships also make possible new phases signaling response growth embryos mostly autonomous territory cells growth rate controlled combination genes active free living


embryos grow mass external food supply embryos fed placenta extraembryonic yolk supply grow fast changes relative growth rate parts organisms help produce final overall anatomy whole process needs coordinated time controlled understood may master clock able communicate parts embryo controls course events timing may depend simply local causal sequences events metamorphosis developmental processes


evident process metamorphosis occurs various types animal well known examples seen frogs usually hatch tadpole metamorphoses adult frog certain insects hatch larva become remodeled adult form pupal stage developmental processes listed occur metamorphosis examples especially well studied include tail loss changes tadpole frog ''xenopus'' biology imaginal discs generate adult body parts fly ''drosophila melanogaster''


plant development plant '' 'development''' process structures originate mature plant grows studied plant anatomy plant physiology well plant morphology plants constantly produce new tissues structures throughout life meristems located tips organs mature tissues thus living plant always embryonic tissues contrast animal embryo early produce body parts ever life animal born hatches egg body


parts point grow larger mature properties organization seen plant emergent properties sum individual parts assembly tissues functions integrated multicellular organism yields characteristics separate parts processes also quite new set characteristics would predictable basis examination separate parts growth vascular plant begins single celled zygote formed fertilisation egg cell


shoot secondary growth results widening root shoot divisions cells cambium addition growth cell division plant may grow '''cell elongation''' occurs individual cells groups cells grow longer plant cells grow length cells one side stem grow longer faster cells side stem bend side slower growing cells result directional growth occur via plant 's response particular


stimulus light phototropism gravity gravitropism water hydrotropism physical contact thigmotropism plant growth development mediated specific plant hormones plant growth regulators pgrs ross et al ref name ross ref endogenous hormone levels influenced plant age cold hardiness dormancy metabolic conditions photoperiod drought temperature external environmental conditions exogenous sources pgrs eg externally applied rhizospheric origin morphological variation plants exhibit natural variation form structure organisms vary individual individual plants exhibit additional type variation within


single individual parts repeated may differ form structure similar parts variation easily seen leaves plant though organs stems flowers may show similar variation three primary causes variation positional effects environmental effects juvenility evolution plant morphology transcription factors transcriptional regulatory networks play key roles plant morphogenesis evolution plant landing many novel transcription factor families emerged preferentially wired networks multicellular development reproduction organ development


contributing complex morphogenesis land plants ref name mbe ref land plants share common ancestor multicellular algae example evolution plant morphology seen charophytes studies shown charophytes traits homologous land plants two main theories evolution plant morphology theories homologous theory antithetic theory commonly accepted theory evolution plant morphology antithetic theory antithetic theory states multiple mitotic divisions take place meiosis cause development sporophyte


sporophyte development independent organism developmental model organisms much developmental biology research recent decades focused use small number model organisms turned much conservation developmental mechanisms across animal kingdom early development different vertebrate species use essentially inductive signals genes encoding regional identity even invertebrates use similar repertoire signals genes although body parts formed significantly different model organisms particular experimental advantages enabled become


gallus'' early stages similar mammal microsurgery easier low cost mouse ''mus musculus'' mammal ref name friedman well developed genetics invertebrates fruit fly ''drosophila melanogaster'' good embryo supply well developed genetics nematode ''caenorhabditis elegans'' good embryo supply well developed genetics low cost unicellular algae ''chlamydomonas'' ref name friedman yeast ''saccharomyces'' ref name friedman others also popular purposes sea urchins ref name friedman ascidians studies regeneration urodele amphibians axolotl ''ambystoma mexicanum'' used also planarian worms ''schmidtea mediterranea'' ref name reddien pw alvarado organoids also demonstrated


efficient model development plant development focused thale cress ''arabidopsis thaliana'' model organism see also references reading external links http wwwsdbonlineorg society developmental biology http wwwsdbcoreorg collaborative resources http edevbiocom developmental biology th edition http bcswileycom bcs booksaction index bcsid itemid essential developmental biology rd edition philosophy biology


'''''developmental biology''''' peer reviewed scientific journal established official journal society developmental biology publishes research mechanisms development differentiation growth animals plants molecular cellular genetic levels journal published twice month elsevier abstracting indexing journal abstracted indexed according ''journal citation reports'' journal impact factor ref name wos ref references external links developmental biology journals english language journals elsevier academic journals delayed open


access journals publications established biweekly journals


'''distributed computing '''is field computer science studies distributed systems ' 'distributed system'' system whose components located different networked computers communicate coordinate actions passing messages one another system ref name tanenbaum ref components interact one another order achieve common goal three significant characteristics distributed systems concurrency components lack global clock independent failure components ref name tanenbaum deals central challenge components system fails n't imply entire system fails examples

Formal science
Computer science
Distributed computing


passing ref name andrews p p ref introduction word ' 'distributed'' terms distributed system distributed programming distributed algorithm originally referred computer networks individual computers physically distributed within geographical area terms nowadays used much wider sense even referring autonomous processes run physical computer interact message passing ref name andrews single definition distributed system ref name harvtxt ghosh p ref following defining properties commonly used several autonomous computational entities ''computers'' ''nodes''


local memory entities communicate message passing distributed system may common goal solving large computational problem user perceives collection autonomous processors unit alternatively computer may user individual needs purpose distributed system coordinate use shared resources provide communication services users typical properties distributed systems include following system tolerate failures individual computers structure system


network topology network latency number computers known advance system may consist different kinds computers network links system may change execution distributed program computer limited incomplete view system computer may know one part input parallel distributed computing b distributed system br c parallel system distributed systems groups networked computers share common goal work terms concurrent computing parallel computing distributed computing much overlap clear distinction


exists system may characterized parallel distributed processors typical distributed system run concurrently parallel parallel computing may seen particular tightly coupled form distributed computing distributed computing may seen loosely coupled form parallel computing ref name harvtxt ghosh nevertheless possible roughly classify concurrent systems parallel distributed using following criteria parallel computing processors may access shared memory exchange information processors distributed computing processor private memory distributed memory


information exchanged passing messages processors figure right illustrates difference distributed parallel systems figure schematic view typical distributed system system represented network topology node computer line connecting nodes communication link figure b shows distributed system detail computer local memory information exchanged passing messages one node another using available communication links figure c shows parallel


system processor direct access shared memory situation complicated traditional uses terms parallel distributed ''algorithm'' quite match definitions parallel distributed ' 'systems'' see detailed discussion nevertheless rule thumb high performance parallel computation shared memory multiprocessor uses parallel algorithms coordination large scale distributed system uses distributed algorithms ref name betalebparallel ref history use concurrent processes communicate message passing roots operating system architectures studied first widespread


distributed systems local area networks ethernet invented arpanet one predecessors internet introduced late arpanet e mail invented early e mail became successful application arpanet probably earliest example large scale distributed application addition arpanet successor global internet early worldwide computer networks included usenet fidonet used support distributed discussion systems ref name banksonthe ref study distributed computing became branch


computer science late early first conference field symposium principles distributed computing podc dates back counterpart international symposium distributed computing disc first held ottawa international workshop distributed algorithms graphs ref name telintro ref architectures various hardware software architectures used distributed computing lower level necessary interconnect multiple cpus sort network regardless whether network printed onto circuit board made loosely coupled devices cables


applications three tier ''n'' tier architectures refer typically web applications forward requests enterprise services type application one responsible success application servers peer peer architectures special machines provide service manage network resources ref name vigna vigna p casey mj ''the age cryptocurrency bitcoin blockchain challenging global economic order'' st martin 's press january ref instead responsibilities uniformly divided among machines known peers peers serve clients servers examples


architecture include bittorrent bitcoin network another basic aspect distributed computing architecture method communicating coordinating work among concurrent processes various message passing protocols processes may communicate directly one another typically master slave relationship alternatively database centric architecture enable distributed computing done without form direct inter process communication utilizing shared database database centric architecture particular provides relational processing analytics schematic architecture allowing live environment relay enables distributed computing functions within beyond parameters networked database applications


reasons using distributed systems distributed computing may include nature application may ' 'require'' use communication network connects several computers example data produced one physical location required another location many cases use single computer would possible principle use distributed system ''beneficial'' practical reasons example may cost efficient obtain desired level performance using cluster several low end computers comparison single high end


computer distributed system provide reliability non distributed system single point failure moreover distributed system may easier expand manage monolithic uniprocessor system examples examples distributed systems applications distributed computing include following telecommunication networks telephone networks cellular networks computer networks internet wireless sensor networks routing algorithms network applications world wide web peer peer networks massively multiplayer online games virtual reality communities distributed databases distributed database management systems network file systems distributed cache burst buffers distributed


task algorithm designer concurrent distributed equivalent sequential general purpose computer discussion focuses case multiple computers although many issues concurrent processes running single computer three viewpoints commonly used parallel algorithms shared memory model processors access shared memory algorithm designer chooses program executed processor one theoretical model parallel random access machines pram used however classical pram model assumes synchronous access shared memory shared memory programs


extended distributed systems underlying operating system encapsulates communication nodes virtually unifies memory across individual systems model closer behavior real world multiprocessor machines takes account use machine instructions compare swap cas ''asynchronous shared memory'' wide body work model summary found literature parallel algorithms message passing model algorithm designer chooses structure network well program executed computer models


boolean circuits sorting networks used boolean circuit seen computer network gate computer runs extremely simple computer program similarly sorting network seen computer network comparator computer distributed algorithms message passing model algorithm designer chooses computer program computers run program system must work correctly regardless structure network commonly used model graph one finite state machine per node case distributed algorithms computational problems


string however multiple computers access string parallel computer might focus one part graph produce coloring part main focus high performance computation exploits processing power multiple computers parallel distributed algorithms graph ''g'' structure computer network one computer node ''g'' one communication link edge ''g'' initially computer knows immediate neighbors graph ''g'' computers must exchange messages discover


structure ''g'' computer must produce color output main focus coordinating operation arbitrary distributed system field parallel algorithms different focus field distributed algorithms much interaction two fields example cole vishkin algorithm graph coloring originally presented parallel algorithm technique also used directly distributed algorithm moreover parallel algorithm implemented either parallel system using shared memory distributed system using


message passing traditional boundary parallel distributed algorithms choose suitable network vs run given network lie place boundary parallel distributed systems shared memory vs message passing complexity measures parallel algorithms yet another resource addition time space number computers indeed often trade running time number computers problem solved faster computers running parallel see speedup decision problem solved polylogarithmic time


using polynomial number processors problem said class nc class nc defined equally well using pram formalism boolean circuits pram machines simulate boolean circuits efficiently vice versa analysis distributed algorithms attention usually paid communication operations computational steps perhaps simplest model distributed computing synchronous system nodes operate lockstep fashion model commonly known local model ''communication round'' nodes parallel nbsp receive latest messages


running time algorithm much smaller ''d'' communication rounds nodes network must produce output without possibility obtain information distant parts network words nodes must make globally consistent decisions based information available ''local neighbourhood'' many distributed algorithms known running time much smaller ''d'' rounds understanding problems solved algorithms one central research questions field typically algorithm solves problem polylogarithmic time


network size considered efficient model another commonly used measure total number bits transmitted network cf communication complexity ref name schneidertrading ref features concept typically captured congest b model similarly defined local model single messages contain b bits problems traditional computational problems take perspective user asks question computer distributed system processes question produces answer stops however also problems system required stop including


dining philosophers problem similar mutual exclusion problems problems distributed system supposed continuously coordinate use shared resources conflicts deadlocks occur also fundamental challenges unique distributed computing example related ''fault tolerance'' examples related problems include consensus problems byzantine fault tolerance self stabilisation much research also focused understanding ''asynchronous'' nature distributed systems synchronizers used run synchronous algorithms asynchronous systems logical clocks provide causal happened ordering events clock synchronization algorithms provide globally


consistent physical time stamps election ''coordinator election'' ''leader election'' process designating single process organizer task distributed among several computers nodes task begun network nodes either unaware node serve coordinator leader task unable communicate current coordinator coordinator election algorithm run however node throughout network recognizes particular unique node task coordinator ref name haloiapache ref network nodes communicate among order decide get


coordinator state need method order break symmetry among example node unique comparable identities nodes compare identities decide node highest identity coordinator ref name haloiapache definition problem often attributed lelann formalized method create new token token ring network token lost coordinator election algorithms designed economical terms total bytes transmitted time algorithm suggested


gallager humblet spira general undirected graphs strong impact design distributed algorithms general dijkstra prize influential paper distributed computing many algorithms suggested different kinds network graphs undirected rings unidirectional rings complete graphs grids directed euler graphs others general method decouples issue graph family design coordinator election algorithm suggested korach kutten moran order perform coordination distributed systems employ concept coordinators coordinator


election problem choose process among group processes different processors distributed system act central coordinator several central coordinator election algorithms exist properties distributed systems far focus ' 'designing'' distributed system solves given problem complementary research problem ' 'studying'' properties given distributed system halting problem analogous example field centralised computation given computer program task decide whether halts runs forever halting problem


undecidable general case naturally understanding behaviour computer network least hard understanding behaviour one computer ref name svozilindet ref however many interesting special cases decidable particular possible reason behaviour network finite state machines one example telling whether given network interacting asynchronous non deterministic finite state machines reach deadlock problem pspace complete ie decidable likely efficient centralised parallel distributed algorithm solves problem case


large networks see also distributed networking decentralized computing federation information technology appscale boinc code mobility distributed algorithm distributed algorithmic mechanism design distributed cache distributed operating system edsger w dijkstra prize distributed computing fog computing folding home grid computing inferno jungle computing layered queueing network library oriented architecture loa list distributed computing conferences list distributed computing projects list important publications concurrent parallel distributed computing model checking parallel distributed processing parallel programming model plan bell labs shared nothing architecture notes references books


articles web sites reading books http docstoremikua orelly java ent dist indexhtm java distributed computing jim faber articles conference papers external links decentralization


leonardo da vinci ''vitruvian man'' accademia venice albrecht rer ''self portrait age '' alt '''drawing''' form visual art artist uses instruments mark paper two dimensional surface drawing instruments include graphite pencils pen ink various kinds paints inked brushes colored pencils crayons charcoal chalk pastels erasers markers styluses metals silverpoint digital drawing act drawing graphics software computer common methods digital drawing include stylus finger touchscreen device stylus finger touchpad

Humanities
Visual arts
Fine arts
Drawing


common artistic activities addition artistic forms drawing frequently used commercial illustration animation architecture engineering technical drawing quick freehand drawing usually intended finished work sometimes called sketch artist practices works technical drawing may called drafter draftsman draughtsman overview galileo galilei ''phases moon'' drawing one oldest forms human expression within visual arts generally concerned marking lines areas tone onto paper material accurate representation


visual world expressed upon plane surface traditional drawings monochrome least little colour modern colored pencil drawings may approach cross boundary drawing painting western terminology drawing distinct painting even though similar media often employed tasks dry media normally associated drawing chalk may used pastel paintings drawing may done liquid medium applied brushes pens similar supports likewise serve painting generally involves application liquid paint onto prepared canvas panels sometimes


underdrawing drawn first support drawing often exploratory considerable emphasis observation problem solving composition drawing also regularly used preparation painting obfuscating distinction drawings created purposes called studies''madame palmyre dog'' henri de toulouse lautrecthere several categories drawing including figure drawing cartooning doodling freehand also many drawing methods line drawing stippling shading surrealist method entopic graphomania dots made sites impurities blank sheet paper lines


made dots tracing drawing translucent paper ''tracing paper'' around outline preexisting shapes show paper quick unrefined drawing may called ' 'sketch'' fields outside art technical drawings plans buildings machinery circuitry things often called drawings even transferred another medium printing history communication drawing one oldest forms human expression evidence existence preceding written communication ref name tversky ref believed drawing used


specialised form communication invention written language ref name tversky demonstrated production cave rock paintings around years ago art upper paleolithic drawings known pictograms depicted objects abstract concepts sketches paintings produced neolithic times eventually stylised simplified symbol systems proto writing eventually early writing systems manuscripts widespread availability paper th century monks european monasteries used intricate drawings prepare illustrated illuminated manuscripts vellum parchment drawing also


used extensively field science method discovery understanding explanation science drawing diagrams observations important part scientific study astronomer galileo galilei explained changing phases venus also sunspots observational telescopic drawings ref name kovats geophysicist alfred wegener used illustrations visually demonstrate origin continents ref name kovats artistic expression drawing used express one 's creativity therefore prominent world art throughout much history drawing regarded


foundation artistic practice initially artists used reused wooden tablets production drawings following widespread availability paper th century use drawing arts increased point drawing commonly used tool thought investigation acting study medium whilst artists preparing final pieces work renaissance brought great sophistication drawing techniques enabling artists represent things realistically revealing interest geometry philosophy invention first widely available


form photography led shift hierarchy arts photography offered alternative drawing method accurately representing visual phenomena traditional drawing practice given less emphasis essential skill artists particularly western society ref name kovats ref notable artists draftsmen drawing became significant art form around late th century artists master engravers albrecht rer martin schongauer c first northern engraver known name schongauer came alsace born family goldsmiths albrecht rer


master next generation also son goldsmith old master drawings often reflect history country produced fundamental characteristics nation time th century holland protestant country almost religious artworks king court art bought privately drawings landscapes genre scenes often viewed sketches highly finished works art italian drawings however show influence catholicism church played major role artistic patronage


often true french drawings although th century disciplines french classicism meant drawings less baroque free italian counterparts conveyed greater sense movement th century modernism encouraged imaginative originality artists' approach drawing became less literal abstract world renowned artists pablo picasso andy warhol jean michel basquiat helped challenge status quo drawing much centre practice often interpreting traditional technique basquiat 's drawings produced many different mediums commonly ink pencil felt tip marker


oil stick drew surface came hand doors clothing refrigerators walls baseball helmets centuries produced canon notable artists draftsmen distinct language drawing including th th th leonardo da vinci albrecht rer hans holbein younger michelangelo pisanello raphael th claude jacques de gheyn ii guercino nicolas poussin rembrandt peter paul rubens pieter saenredam th fran ois boucher jean honor fragonard giovanni battista tiepolo antoine watteau th aubrey beardsley


paul c zanne jacques louis david honor daumier edgar degas th odore g ricault francisco goya jean auguste dominique ingres pierre paul prud'hon odilon redon john ruskin georges seurat henri de toulouse lautrec vincent van gogh th max beckmann jean dubuffet c escher arshile gorky george grosz paul klee oscar kokoschka k kollwitz alfred kubin andr masson alphonse mucha jules pascin pablo picasso egon schiele jean michel basquiat andy warhol materials ''medium'' means ink pigment