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enish blues the roof is arched and was likened to the back of a dragon or dinosaur a common theory about the building is that the rounded feature to the left of centre terminating at the top in a turret and cross represents the sword of saint george which has been plunged into the back of the dragon external links the official website of la casa batll casa batll on greatbuildings com casa batll pictures casa batll description buildings and structures in barcelona modernisme antoni gaud buildings the entrance to the park park g ell is a garden complex with architectural elements situated on the hill of el carmel in the gr cia district of barcelona spain it was designed by the catalan architect antoni gaud and built in the years one nine zero zero to one nine one four it is one of the unesco world heritage sites the park was originally part of a commercially unsuccessful housing site the idea of count eusebio de guell it was inspired by british developments hence the original english name park it has been conve
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rted into a municipal garden it can be reached by underground although the stations are at a certain distance by the regular buses or best by the tourist buses while the park is free gaud s house containing furniture that he designed can be visited at a cost gaud s mosaic work on the main terrace the design of the park is clearly the work of an architect and gaud s unique style is also easily distinguishable wavy lava like shapes at places tree like or in form of doric columns or stalactites sometimes lavishly decorated with ornaments of broken ceramic fragments a catalan technique the landscaping of the park is largely in tune with the natural terrain steep slopes and cliffs have been allowed to remain with winding paths cuttings and grottoes adding to the natural feel although it sounds unlikely the place is skillfully designed and composed to bring the peace and calm that one would expect from a park the buildings though very original and remarkable are relatively inconspicuous considering other buildings
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designed by gaud they have fantastically shaped roofs with unusual pinnacles the focal point of the park is the main terrace surrounded by a long bench in the form of a sea serpent gaud used a naked man sitting in clay to design the bench the curves form a number of enclaves creating a more social atmosphere the large cross at the park s high point offers the most complete view of barcelona it is possible to view the main city in panaroma with the sagrada familia and the montju c area visible at a distance external links park g ell at google maps parque guell barcelona gardens guide park g ell photo gallery barcelona modernisme parks in spain world heritage sites in spain antoni gaud buildings casa mil barcelona parabolic or catenary arches under the terrace of casa mil casa mil better known as la pedrera catalan for the quarry is a building designed by the catalan architect antoni gaud and built in the years one nine zero five to one nine zero seven it is located at nine two passeig de gr cia passeig is cata
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lan for promenade or avenue in the eixample district of barcelona catalonia spain it was built for roger segimon de mil it is one of the unesco world heritage sites the building does not have any straight lines most people consider it magnificent and overwhelming some say it is like waves of lava or a sand dune this building seems to break our understanding of conventional architecture the most astonishing part is the roof with an almost lunar appearance and dreamlike landscape the building can be considered more of a sculpture than a regular building critics remark on its detachment from usefulness but others consider it to be art the barcelonese of the time considered it ugly hence the quarry nickname but today it is a landmark of barcelona casa mil was a predecessor of some buildings with a similar biomorphic appearance the one nine two one einstein tower in potsdam designed by erich mendelsohn solomon r guggenheim museum in new york designed by frank lloyd wright chapelle notre dame du haut ronchamp franc
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e designed by le corbusier the hundertwasserhaus and other words by austrian architect friedensreich hundertwasser disney concert hall in los angeles by frank gehry free exhibitions are often held on the first floor which also provides some opportunity to see the interior design there is a charge of seven for entrance to the apartments and roof casa mil in the media a scene in professione reporter a film directed by michelangelo antonioni was filmed on the building s roof stylized stairway entrances on the roof see also list of buildings list of museums external links la pedrera educaci photographs of casa mila la pedrera photos of la pedrera buildings and structures in barcelona modernisme world heritage sites in spain antoni gaud buildings corresponding to each kind of particle there is an associated antiparticle with the same mass and spin some particles such as the photon are identical to their antiparticle such particles must have no electric charge but not all charge neutral particles are of this kind t
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he laws of nature were thought to be symmetric between particles and antiparticles until cp violation experiments found that time reversal symmetry is violated in nature the observed excess of baryons over anti baryons in the universe is one of the primary unsolved problems in cosmology particle antiparticle pairs can annihilate each other if they are in appropriate quantum states they can also be produced in various processes these processes are used in today s particle accelerators to create new particles and to test theories of particle physics high energy processes in nature can create antiparticles these are visible in cosmic rays and in certain nuclear reactions the word antimatter properly refers to elementary antiparticles composite antiparticles made with them such as antihydrogen and to larger assemblies of either history experiment in one nine three two soon after the prediction of positrons by paul dirac carl d anderson found that cosmic ray collisions produced these particles in a cloud chamber a
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particle detector in which moving electrons or positrons leave behind trails as they move through the gas the electric charge to mass ratio of a particle can be measured by observing the curling of its cloud chamber track in a magnetic field originally positrons because of the direction that their paths curled were mistaken for electrons travelling in the opposite direction the antiproton and antineutron were found by emilio segr and owen chamberlain in one nine five five at the university of california berkeley since then the antiparticles of many other subatomic particles have been created in particle accelerator experiments in recent years complete atoms of antimatter have been assembled out of antiprotons and positrons collected in electromagnetic traps hole theory the development of quantum field theory made the interpretation of antiparticles as holes unnecessary even though unfortunately it lingers on in many textbooks steven weinberg in the quantum theory of fields vol i p one four isbn zero five two
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one five five zero zero one seven solutions of the dirac equation contained negative energy quantum states as a result an electron could always radiate energy and fall into a negative energy state even worse it could keep radiating infinite amount of energy because there were infinitely negative energy states available to prevent this unphysical situation from happening dirac proposed that a sea of negative energy electrons fills the universe already occupying all of the lower energy states so that due to the pauli exclusion principle no other electron could fall into them sometimes however one of these negative energy particles could be lifted out of this dirac sea to become a positive energy particle but when lifted out it would leave behind a hole in the sea which would act exactly like a positive energy electron with a reversed charge these he interpreted as the proton and called his paper of one nine three zero a theory of electrons and protons dirac was aware of the problem that his picture implied an
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infinite negative charge for the universe dirac tried to argue that we would perceive this as the normal state of zero charge another difficulty was the difference in masses of the electron and the proton dirac tried to argue that this was due to the electromagnetic interactions with the sea until hermann weyl proved that hole theory was completely symmetric between negative and positive charges dirac also predicted a reaction e p electron and proton annihilate to give two photons robert oppenheimer and igor tamm proved that this would cause ordinary matter to disappear too fast a year later in one nine three one dirac modified his theory and postulated the positron a new particle of the same mass as the electron the discovery of this particle the next year removed the last two objections to his theory however the problem of infinite charge of the universe remains also as we now know bosons if they exist also have antiparticles but since they do not obey the pauli exclusion principle hole theory doesn t work
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for them a unified interpretation of antiparticles is now available in quantum field theory which solves both these problems particle antiparticle annihilation main article annihilation an example of a virtual pion pair which influences the propagation of a kaon causing a neutral kaon to mix with the antikaon this is an example of renormalization in quantum field theory the field theory being necessary because the number of particles changes from one to two and back again if a particle and antiparticle are in the appropriate quantum states then they can annihilate each other and produce other particles reactions such as e e the two photon annihilation of an electron positron pair is an example the single photon annihilation of an electron positron pair e e cannot occur because it is impossible to conserve energy and momentum together in this process the reverse reaction is also impossible for this reason however in quantum field theory this process is allowed as an intermediate quantum state for times short e
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nough that the violation of energy conservation can be accommodated by the uncertainty principle this opens the way for virtual pair production or annihilation in which a one particle quantum state may fluctuate into a two particle state and back these processes are important in the vacuum state and renormalization of a quantum field theory it also opens the way for neutral particle mixing through processes such as the one pictured here which is a complicated example of mass renormalization properties of antiparticles quantum states of a particle and an antiparticle can be interchanged by applying the charge conjugation c parity p and time reversal t if p n denotes the quantum state of a particle n with momentum p spin j whose component in the z direction is then one has cpt p n one j p nc where nc denotes the charge conjugate state ie the antiparticle this behaviour under cpt is the same as the statement that the particle and its antiparticle lie in the same irreducible representation of the poincare group p
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roperties of antiparticles can be related to those of particles through this if t is a good symmetry of the dynamics then t p n p n cp p n p nc c p n p nc where the proportionality sign indicates that there might be a phase on the right hand side in other words particle and antiparticle must have the same mass m the same spin state j opposite electric charges q and q quantum field theory this section draws upon the ideas language and notation of canonical quantization of a quantum field theory one may try to quantize an electron field without mixing the annihilation and creation operators by writing x k uk x ak e i e k t where we use the symbol k to denote the quantum numbers p and of the previous section and the sign of the energy e k and ak denotes the corresponding annihilation operators of course since we are dealing with fermions we have to have the operators satisfy canonical anti commutation relations however if one now writes down the hamiltonian h k e k a k ak then one sees immediately that the expec
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tation value of h need not be positive this is because e k can have any sign whatsoever and the combination of creation and annihilation operators has expectation value one or zero so one has to introduce the charge conjugate antiparticle field with its own creation and annihilation operators satisfying the relations bk a k and b k ak where k has the same p and opposite and sign of the energy then one can rewrite the field in the form x k uk x ak e i e k t k uk x b k e i e k t where the first sum is over positive energy states and the second over those of negative energy the energy becomes h k e k a k ak k e k b k bk e zero where e zero is an infinite negative constant the vacuum state is defined as the state with no particle or antiparticle ie ak zero zero and bk zero zero then the energy of the vacuum is exactly e zero since all energies are measured relative to the vacuum h is positive definite analysis of the properties of ak and bk shows that one is the annihilation operator for particles and the other f
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or antiparticles this is the case of a fermion this approach is due to vladimir fock wendell furry and robert oppenheimer if one quantizes a real scalar field then one finds that there is only one kind of annihilation operator therefore real scalar fields describe neutral bosons since complex scalar fields admit two different kinds of annihilation operators which are related by conjugation such fields describe charged bosons the feynman stueckelberg interpretation observer one sees two particles one propagating inside the light cone the other outside the light cone observer two moving at a uniform velocity with respect to the first observer could then see the second particle as moving back in time and with reversed charge hence as an antiparticle however the mass and lifetime of such a particle would remain unchanged as a consequence of relativity by considering the propagation of the positive energy half of the electron field backward in time richard feynman showed that causality is violated unless one allow
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s some particles to travel faster than light however if particles are allowed to do that then from the point of view of another inertial observer it would look like it was travelling backward in time with the opposite charge hence feynman reached a pictorial understanding of the fact that the particle and antiparticle have equal mass m and spin j but opposite charges this allowed him to rewrite perturbation theory precisely in the form of diagrams called feynman diagrams of particles propagating back and forth in time this technique now is the most widespread method of computing amplitudes in quantum field theory this picture was independently developed by ernst stueckelberg and has been called the feynman stueckelberg interpretation of antiparticles see also gravitational interaction of antimatter parity charge conjugation and time reversal symmetry cp violations and the baryon asymmetry of the universe quantum field theory and the list of particles baryogenesis references feynman richard p the reason for an
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tiparticles in the one nine eight six dirac memorial lectures r p feynman and s weinberg cambridge university press one nine eight seven isbn zero five two one three four zero zero zero four weinberg steven the quantum theory of fields volume one foundations cambridge university press one nine nine five isbn zero five two one five five zero zero one seven antimatter arabian prince born mik lezan is an electro hop and hip hop rapper from los angeles he started his career at rapsur records a label setup by russ parr and released some electro classics like innovator strange life a couple of years later he joined the compton ca rap group niggaz with attitude n w a the arabian prince found the going tough when he departed the group for a solo career in one nine eight eight his debut brother arab on orpheus barely scraped the bottom of the r b and pop charts in one nine eight nine his first solo releases are in high demand nowadays his credit albums include brother arab and where s my bytches as well as work on n w
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a s straight outta compton and production for various other west coast hip hop artists arabian prince has reappeared testing video games for fox interactive around the year two zero zero zero and currently runs a three d animation studio external links the underworld of the arabian prince american rappers august seven is the two one nine th day of the year in the gregorian calendar two two zero th in leap years with one four six days remaining there are nine four days in north hemisphere summer south hemisphere winter the northern hemisphere is considered to be halfway through the summer on august seven events one six seven nine the brigantine le griffon commissioned by ren robert cavelier sieur de la salle is towed to the southern end of the niagara river to become the first ship to sail the upper great lakes of north america one seven eight two george washington orders the creation of the badge of military merit to honor soldiers wounded in battle it is later renamed to the more poetic purple heart one sev
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en eight nine the united states war department is established one seven nine four whiskey rebellion begins farmers in the monongahela valley of pennsylvania rebel against the federal tax on liquor and distilled drinks one eight one nine sim n bol var triumphs over spain in the battle of boyac one eight seven nine the opening of the poor man s palace in manchester one nine two seven the peace bridge opens between fort erie ontario and buffalo new york one nine four two world war ii battle of guadalcanal begins u s marines initiate the first american offensive of the war with a landing on guadalcanal in the solomon islands one nine four four ibm dedicates the first program controlled calculator the automatic sequence controlled calculator known best as the harvard mark i one nine four five president harry truman announces the successful bombing of hiroshima with an atomic bomb while returning from the potsdam conference aboard the heavy cruiser uss augusta ca three one in the middle of the atlantic ocean one ni
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ne four seven thor heyerdahl s balsa wood raft the kon tiki smashes into the reef at raroia in the tuamotu islands after a one zero one day seven zero zero zero km four three seven five mile journey across the pacific ocean proving that pre historic peoples could have traveled from south america one nine four seven the bombay municipal corporation formally takes over the bombay electric supply and transport best one nine five five tokyo telecommunications engineering the precursor to sony begins selling its first transistor radios in japan one nine five nine explorer program the united states launches explorer six from the atlantic missile range in cape canaveral florida one nine six zero c te d ivoire becomes independent one nine six four vietnam war the u s congress passes the gulf of tonkin resolution giving us president lyndon b johnson broad war powers to deal with north vietnamese attacks on american forces one nine six five singapore is expelled and separated from the federation of malaysia one nine si
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x six race riots occur in lansing michigan one nine six seven vietnam war the people s republic of china agrees to give north vietnam an undisclosed amount of aid in the form of a grant one nine seven zero california judge harold haley is taken hostage in his courtroom and killed during in an effort to free george jackson from police custody one nine seven three nbc airs the final day of the watergate hearings on u s daytime television one nine seven six viking program viking two enters into orbit around mars one nine seven eight united states president jimmy carter declares a federal emergency at love canal one nine eight one the washington star ceases all operations after one two eight years of publication one nine eight five takao doi mamoru mohri and chiaki mukai are chosen to be japan s first astronauts one nine eight eight rioting in new york city s tompkins square park one nine eight nine u s congressman mickey leland d tx and one five others die in a plane crash in ethiopia one nine nine zero at one t
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wo three four five six both am and pm the time and date by british reckoning was one two three four five six seven eight nine zero i e one two three four five six seven eight nine zero one nine nine five operation storm is officialy declared over in croatia resulting in total croat victory over rebel serb forces one nine nine seven fine air flight one zero one a cargo flight from miami to santo domingo crashes onto nw seven two nd ave near miami international airport killing five people one nine nine eight one nine nine eight u s embassy bombings bombing of the united states embassies in dar es salaam tanzania and nairobi kenya kill two two four people and injure over four five zero zero one nine nine nine a group of indian army veterans launch the political party rashtriya raksha dal two zero zero zero deviantart com is created by scott jarkoff matteo stevens and angelo sortia two zero zero five russian priz class mini submarine as two eight and its seven crewmembers are rescued off the pacific coast two zer
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o zero five singer marc cohn is shot in the head during a carjacking attempt in denver he survives births one four zero zero guillaume dufay french composer d one four seven four one five three three alonso de ercilla y z iga basque soldier and poet d one five nine five one five six zero elizabeth b thory hungarian serial killer d one six one four one five seven four robert dudley styled earl of warwick english writer d one six four nine one five nine eight georg stiernhielm swedish poet d one six seven two one seven two six james bowdoin american revolutionary leader and politician d one seven nine zero one seven four two nathanael greene american revolutionary general d one seven eight six one seven seven nine louis de freycinet french explorer d one eight four two one seven seven nine carl ritter german geographer d one eight five nine one eight four four auguste michel l vy french geologist d one nine one one eight six zero alan leo british astrologer d one nine one seven one eight six seven emil nolde ge
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rman painter d one nine five six one eight seven six mata hari dutch spy d one nine one seven one eight seven seven ulrich salchow swedish figure skater d one nine four nine one eight eight five billie burke american actress d one nine seven zero one nine zero four ralph bunche american diplomat recipient of the nobel peace prize d one nine seven one one nine two five m s swaminathan indian scientist one nine two five felice bryant american country songwriter and singer d two zero zero three one nine two six stan freberg american voice comedian one nine two eight james randi canadian magician one nine two nine don larsen baseball player one nine three two abebe bikila ethiopan athlete one nine three six rahsaan roland kirk american saxophonist one nine four zero jean luc dehaene prime minister of belgium one nine four two garrison keillor american writer and radio host one nine four two b j thomas american singer one nine four three dino valente american musician quicksilver messenger service d one nine nine
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four one nine four four david rasche american actor one nine four five alan page american football player one nine four eight greg chappell australian test cricket player captain and coach one nine four nine walid jumblatt leader of the lebanese druze one nine five two alexei sayle british alternate comedian one nine five five vladimir sorokin russian writer one nine five eight bruce dickinson english singer iron maiden one nine six zero david duchovny american actor one nine six three harold perrineau jr american actor one nine six four michael weishan american tv host author one nine six six jimmy wales american founder of wikipedia one nine seven three danny graves american baseball player one nine seven five david hicks australian alleged terrorist one nine seven five charlize theron south african actress one nine seven eight jamey jasta american singer hatebreed one nine eight two yana klochkova ukrainian swimmer one nine eight seven sidney crosby canadian hockey player deaths four six one majorian roman
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emperor assassinated b four two zero four seven nine emperor y ryaku of japan one one zero six henry iv holy roman emperor b one zero five zero one four eight five alexander stewart one st duke of albany english prince one six one three thomas fleming english judge b one five four four one six one six vincenzo scamozzi italian architect b one five four eight one six three five friedrich von spee german writer b one five nine one one six six one jin shengtan chinese editor writer and critic b one six zero eight one eight one seven pierre samuel du pont de nemours french industrialist b one seven three nine one eight three four joseph marie jacquard french weaver and inventor b one seven five two one eight four eight j ns jakob berzelius swedish chemist b one seven seven nine one eight five five mariano arista president of mexico b one eight zero two one nine one two fran ois alphonse forel swiss hydrologist b one eight four one one nine four one rabindranath tagore indian author nobel prize laureate b one eig
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ht six one one nine five seven oliver hardy american comedian and actor b one eight nine two one nine seven four rosario castellanos mexican poet b one nine two five one nine eight nine mickey leland u s congressman d tx b one nine four four one nine nine five brigid brophy british author b one nine two nine one nine nine nine brion james american actor b one nine four five two zero zero four red adair american firefighter b one nine one five two zero zero four colin bibby english ornithologist b one nine four eight two zero zero five peter jennings canadian born news anchor b one nine three eight external links bbc on this day the new york times on this day august six august eight july seven september seven listing of all days august eight is the two two zero th day of the year in the gregorian calendar two two one st in leap years with one four five days remaining events one five zero nine the emperor krishnadeva raya is crowned marking the beginning of the regeneration of the vijayanagara empire one five e
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ight five john davis enters cumberland sound in quest for the northwest passage one five eight eight battle of gravelines ends marking the end of the spanish armada s attempt to invade england one six zero five the city of oulu finland is founded by charles ix of sweden one six four seven battle of dangan hill irish forces are defeated by british parliamentary forces one seven eight six mont blanc in switzerland is climbed for the first time by jacques balmat and dr michael gabriel paccard one eight three nine beta theta pi is founded in oxford ohio one eight four four the quorum of twelve headed by brigham young is created as the leading body of the mormon church one eight six three american civil war following his defeat in the battle of gettysburg general robert e lee sends a letter of resignation to confederate president jefferson davis which is refused upon receipt one eight seven six thomas edison receives a patent for his mimeograph one nine one one public law six two five sets the number of representa
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tives in the united states house of representatives at four three five the law will take effect in one nine one three one nine one eight world war i battle of amiens canadian troops backed by australians begin a string of almost continuous victories with a push through the german front lines one nine two nine the german airship graf zeppelin begins a round the world flight one nine three zero betty boop premieres in the animated film dizzy dishes one nine three eight the mauthausen concentration camp opens one nine four two world war ii in washington dc six german would be saboteurs are executed one nine four two quit india resolution was passed by the bombay session of the aicc which leads to the start of a civil disobedience movement across india one nine four five world war ii the soviet union declares war on japan and invades manchuria one nine four five the united nations charter is ratified by the united states which becomes the third nation to join one nine four nine bhutan becomes independent one nine
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six two elizabeth ann duncan becomes the last woman to be executed in the united states prior to the reintroduction of capital punishment in one nine seven seven one nine six three great train robbery in england a gang of one five train robbers steal two six million pounds in bank notes one nine six seven the association of southeast asian nations asean is founded one nine six eight jur wada successfully performs japan s first heart transplant one nine six nine an iconic picture of the beatles is taken to be used on their album abbey road one nine seven two richard nixon accepts the nomination as candidate for the presidency one nine seven three u s vice president spiro agnew goes on television to denounce accusations he had taken kickbacks while governor of maryland one nine seven three kim dae jung a south korean politician and later president of south korea is kidnapped one nine seven four watergate scandal u s president richard nixon announces his resignation effective the next day one nine seven six bos
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ton by the rock band boston is released it will become the one best selling debut album in history one nine eight eight general ne win ruler of burma since one nine six two suddenly resigns one nine eight eight chicago s wrigley field installs lights and attempts to play first game at night one nine eight nine sts two eight the space shuttle columbia takes off on a secret five day military mission one nine nine one collapse of warsaw radio mast the tallest construction ever built one nine nine one john mccarthy british journalist held hostage in lebanon for more than five years by islamic jihad is released one nine nine nine the series finale of mystery science theater three zero zero zero airs on the sci fi channel two zero zero zero confederate submarine h l hunley is raised to the surface after one three six years on the ocean floor two zero zero eight the opening ceremony of the two zero zero eight summer olympics is scheduled to begin at eight o clock zero eight zero eight zero eight zero eight births on
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e zero seven nine emperor horikawa of japan d one one zero seven one six zero two gilles de roberval french mathematician d one six seven five one six zero five c cilius calvert two nd baron baltimore colonial governor of maryland d one six seven five one six four six godfrey kneller german born painter d one seven two three one six seven three john ker scottish spy d one seven two six one six nine three laurent belissen french composer d one seven six two one six nine four francis hutcheson irish philosopher d one seven four six one seven two zero carl fredrik pechlin swedish politician d one seven nine six one eight one four esther morris suffragist and the first u s woman judge d one nine zero two one eight three nine nelson miles u s general d one nine two five one eight six six matthew henson arctic explorer d one nine five five one eight seven five artur da silva bernardes president of brazil d one nine five five one eight seven nine emiliano zapata mexican revolutionary d one nine one nine one eight ei
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ght zero earle page eleventh prime minister of australia d one nine six one one eight nine one adolf busch german violinist d one nine five two one eight nine two rafael moreno aranzadi spanish footballer d one nine two two one eight nine six marjorie kinnan rawlings american author d one nine five three one nine zero one ernest o lawrence american physicist nobel prize laureate d one nine five eight one nine zero two paul dirac english physicist nobel prize laureate d one nine eight four one nine zero five andr jolivet french composer d one nine seven four one nine zero seven benny carter american musician and arranger d two zero zero three one nine zero eight arthur goldberg u s supreme court justice d one nine eight zero one nine one zero sylvia sidney american actress d one nine nine nine one nine one one rosetta lenoire american actress d two zero zero two one nine one five james jumbo elliott american track coach d one nine eight one one nine one nine dino de laurentiis italian film producer one nine tw
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o zero leo chiosso italian lyricist one nine two one william asher american film producer one nine two one john herbert chapman british physicist one nine two one webb pierce american singer d one nine nine one one nine two one vulimiri ramalingaswami indian medical scientist one nine two one esther williams american actress and swimmer one nine two two rory calhoun american actor d one nine nine nine one nine two two rudi gernreich austrian born fashion designer d one nine eight five one nine two five alija izetbegovic president of bosnia herzegovina d two zero zero three one nine two seven johnny temple baseball player d one nine nine four one nine two eight don burrows australian jazz musician one nine two nine larisa bogoraz soviet dissident d two zero zero four one nine two nine ronald biggs british criminal one nine three one sir roger penrose british physicist one nine three two mel tillis american singer one zero three five john laws australia radio personality one nine three six donald p bellisario a
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merican television producer one nine three six keith barron english actor one nine three seven dustin hoffman american actor one nine three eight connie stevens american singer and actress one nine three nine alexander watson american ambassador and diplomat one nine four four peter weir australian film director one nine four four uli derickson czech born flight attendant one nine four four brooke bundy american actress one nine four nine keith carradine american actor one nine five one mamoru oshii japanese film director one nine five two jostein gaarder norwegian author one nine five two robin quivers american radio personality one nine five three don most american actor one nine five four nigel mansell english race car driver one nine five five herbert prohaska austrian footballer one nine five six branscombe richmond american actor one nine five eight deborah norville american reporter and television host one nine six one the edge irish guitarist u two one nine six six chris eubank english boxer one nine
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seven three scott stapp american singer creed one nine seven four ulises de la cruz ecuadoran footballer one nine seven six j c chasez american singer nsync one nine seven six drew lachey american singer one nine seven eight louis saha french footballer one nine seven nine richard harwood british cellist one nine eight zero sabine klaschka german tennis player one nine eight zero pat noonan american soccer player one nine eight one vanessa amorosi australian singer and songwriter one nine eight one roger federer swiss tennis player one nine eight eight princess beatrice of york one nine eight nine sesil karatantcheva bulgarian tennis player deaths eight six nine lothair ii of lotharingia b eight two five one four four five oswald von wolkenstein austrian composer one five five three girolamo fracastoro italian physician b one four seven eight one five eight eight alonso s nchez coello spanish painter one six zero four horio tadauji japanese warlord b one five seven eight one six eight four george booth one st
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baron delamer b one six two two one six nine four antoine arnauld french philosopher and mathematician b one six one two one seven five nine carl heinrich graun german composer one eight two eight carl peter thunberg swedish naturalist b one seven four three one eight seven nine immanuel hermann fichte german philosopher b one seven nine seven one eight eight seven alexander william doniphan american lawyer and soldier b one eight zero eight one eight nine eight eug ne boudin french painter b one eight two four one nine zero two james tissot french artist b one eight three six one nine one one william p frye american politician b one eight three zero one nine three three adolf loos austrian architect b one eight seven zero one nine four zero johnny dodds american musician b one eight nine two one nine four four chaim soutine russian painter b one eight nine four one nine six five shirley jackson american author b one nine one six one nine seven two andrea feldman american actor b one nine four eight one nine
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seven five julian cannonball adderley american jazz saxophonist b one nine two eight one nine eight five louise brooks american actress b one nine zero six one nine eight seven danilo blanu a croatian mathematician b one nine zero three one nine nine one james irwin astronaut b one nine three zero one nine nine six nevill mott english physicist nobel prize in physics b one nine zero five two zero zero four fay wray american actress b one nine zero seven two zero zero five barbara bel geddes american actress b one nine two two two zero zero five john h johnson african american publisher billionaire b one nine one eight two zero zero five gene mauch american athlete and manager b one nine two five two zero zero five monica sjoo swedish artist cancer b one nine three eight two zero zero five ilse werner german actress b one nine two one holidays and observances taiwan father s day in mandarin ba ba means father and eight eight or august eight sweden namesday of queen silvia an official flag day religious observ
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ances roman catholic church memorial of st dominic de guzman priest one one seven zero one two two one external links bbc on this day the new york times on this day on this day in canada august seven august nine july eight september eight listing of all days april one six is the one zero six th day of the year in the gregorian calendar one zero seven th in leap years there are two five nine days remaining events one one seven eight bc a solar eclipse may mark the return of odysseus legendary king of ithaca to his kingdom after the trojan war one zero seven one bari falls to robert guiscard ending byzantine rule in italy one five two one martin luther s first appearance before the diet of worms to be examined by the holy roman emperor charles v and the rest of the estates of the empire one seven four six second jacobite rebellion the battle of culloden the last battle of the jacobite uprising is fought ultimately leading to the destruction of the highland clans one seven eight zero the university of m nster in
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m nster north rhine westphalia germany is founded one seven nine nine napoleonic wars battle of mount tabor napoleon drives ottoman turks across the river jordan near acre one eight five three the first passenger rail opens in india from bori bunder bombay to thane one eight six three american civil war siege of vicksburg one two ships led by union admiral david dixon porter move through heavy confederate artillery fire on approach to vicksburg mississippi only one ship is lost one eight eight one in dodge city kansas bat masterson fights his last gun battle one nine one two harriet quimby becomes the first woman to fly an airplane across the english channel one nine one seven vladimir lenin returns to petrograd present day saint petersburg from exile in finland one nine one nine mohandas gandhi organizes a day of prayer and fasting in response to the british slaughter of indian protestors in the amritsar massacre one nine two two the treaty of rapallo in which germany and the soviet union re establish diplo
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matic relations between berlin and moscow is signed one nine two six lolly willows by sylvia townsend warner is distributed as the first book of the month club selection one nine three five radio program fibber mcgee and molly debuts one nine four three dr albert hofmann discovers the psychedelic effects of lsd one nine four five wwii the red army begins the final assault on german forces around berlin one nine four five the united states army liberates nazi sonderlager high security prisoner of war camp oflag ivc colditz castle one nine four five german ship goya sinks killing more than seven zero zero zero people one nine four seven texas city disaster an explosion on board a freighter in port causes the city of texas city texas to catch fire killing almost six zero zero one nine four seven bernard baruch coins the term cold war to describe the relationship between the united states and the soviet union one nine four nine dave garroway moves from radio to television to host the musical variety show garroway
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at large one nine six three dr martin luther king jr pens his famous letter from a birmingham jail while incarcerated in birmingham alabama for protesting against segregation one nine seven two apollo program apollo one six launches toward the moon from cape canaveral florida one nine seven two vietnam war nguyen hue offensive prompted by the north vietnamese offensive the united states resumes bombing of hanoi and haiphong one nine eight eight in forl italy red brigades kill italian senator roberto ruffilli an advisor of prime minister ciriaco de mita one nine nine two the katina p runs aground off of maputo mozambique six zero zero zero zero tons of crude oil spill into the ocean one nine nine six france t l com introduces its wanadoo internet service one nine nine eight one of the most serious urban tornadoes in history does significant damage to downtown nashville tennessee see nashville tornado of one nine nine eight two zero zero zero protests against the world bank and imf in washington dc two zero ze
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ro one first three g voice call on vodafone uk s three g network two zero zero three makobo modjadji is crowned the new rain queen of balobedu two zero zero three the accession treaty is signed in athens admitting one zero new member states to the european union two zero zero five the bbc announces david tennant s casting as the tenth doctor in the long running science fiction television series doctor who births seven seven eight king louis the pious d eight four zero one three one nine king john ii of france d one three six four one four nine five petrus apianus german mathematician d one five five seven one six four six jules hardouin mansart french architect d one seven zero eight one six six zero hans sloane british collector and physician d one seven five three one six six one charles montagu one st earl of halifax english poet and statesman d one seven one five one six eight two john hadley inventor d one seven four four one seven two eight joseph black scottish chemist d one seven nine nine one seven t
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hree zero henry clinton british general d one seven nine five one seven five five elisabeth vigee lebrun french painter d one eight four two one eight zero zero george bingham three rd earl of lucan british soldier d one eight eight eight one eight two three ferdinand eisenstein german mathematician d one eight five two one eight four four anatole france french writer nobel prize laureate d one nine two four one eight six five henry george chauvel australian general d one nine four five one eight six seven wilbur wright american aviation pioneer d one nine one two one eight seven one john millington synge irish writer d one nine zero nine one eight seven eight tip foster english cricketer d one nine one four one eight eight six ernst th lmann german politician d one nine four four one eight eight nine charles chaplin english actor writer and film producer d one nine seven seven one nine zero four fifi d orsay canadian actress d one nine eight three one nine zero five frits philips dutch businessman d two zero
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zero five one nine one two garth williams american illustrator d one nine nine six one nine one eight spike milligan british comedian d two zero zero two one nine one nine merce cunningham american dancer and choreographer one nine two one peter ustinov english writer actor and film director d two zero zero four one nine two two kingsley amis english author d one nine nine five one nine two four henry mancini american composer d one nine nine four one nine two seven edie adams american actress one nine two seven pope benedict xvi one nine two seven peter mark richman american actor one nine two eight dick night train lane american football player d two zero zero two one nine three zero herbie mann american jazz flute player d two zero zero three one nine three three joan bakewell british broadcaster one nine three five sarah kirsch german poet one nine three five bobby vinton american singer one nine three seven joseph whipp american actor one nine three nine dusty springfield english singer d one nine nine
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nine one nine four zero queen margaret ii of denmark one nine four six margot adler american journalist one nine four seven kareem abdul jabbar american basketball player one nine four seven gerry rafferty british musician and songwriter one nine five one pierre toutain dorbec french photographer painter sculptor one nine five one ioan mihai cochinescu romanian writer and photographer one nine five one bj rgvin halld rsson icelandic singer one nine five two bill belichick american football coach one nine five two billy west american voice actor one nine five three j neil schulman american writer and activist one nine five four ellen barkin american actress one nine five five bruce bochy baseball player and manager one nine five six lise marie morerod swiss skier one nine five nine alison ramsay scottish field hockey player one nine six zero rafael benitez spanish football manager one nine six one doris dragovi croatian singer one nine six two ian mackaye american musician fugazi and minor threat one nine six
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five jon cryer american actor one nine six five martin lawrence american actor comedian and producer one nine seven one selena american singer d one nine nine five one nine seven five sean maher american actor one nine seven six lukas haas american actor one nine seven seven fredrik ljungberg swedish footballer one nine seven eight matthew lloyd australian football player one nine seven nine howlin pelle almqvist swedish musician the hives one nine nine four liliana mumy american actress deaths six nine otho roman emperor b three two seven four four al walid ii umayyad caliph nine two four berengar of friuli king of italy one one one three sviatopolk ii of kiev russian prince b one zero five zero one one one eight adelaide del vasto queen of roger ii of sicily one one nine eight duke frederick i of austria one six four five tobias hume english composer one six eight seven george villiers two nd duke of buckingham english statesman b one six two eight one six eight nine aphra behn english dramatist one seven e
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ight three christian mayer czech astronomer b one seven one nine one seven eight eight georges louis leclerc comte de buffon french naturalist b one seven zero seven one eight two eight francisco de goya spanish painter b one seven four six one eight four six domenico dragonetti italian composer b one seven six three one eight five nine alexis de tocqueville french historian b one eight zero five one eight eight eight zygmunt florenty wr blewski polish physicist b one eight four five one nine zero four samuel smiles scottish writer and reformer b one eight one two one nine one four george william hill american astronomer b one eight three eight one nine one five nelson w aldrich u s senator from rhode island b one eight four one one nine three eight steve bloomer english footballer b one eight seven four one nine four six arthur chevrolet swiss born race car driver and automobile designer b one eight eight four one nine five eight rosalind franklin british chemist b one nine two zero one nine six eight edna f
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erber american author b one eight eight five one nine seven two kawabata yasunari japanese writer nobel prize laureate b one eight nine nine one nine seven eight lucius clay american general b one eight nine seven one nine eight five scott brady american actor b one nine two four one nine nine one david lean british film director b one nine zero eight one nine nine two neville brand american actor b one nine two zero one nine nine four ralph ellison american writer b one nine one four one nine nine seven doris angleton american socialite b one nine five one one nine nine seven roland topor french illustrator b one nine three eight one nine nine eight fred davis english snooker player b one nine one three two zero zero one michael ritchie american film director b one nine two zero two zero zero two ruth fertel american restaurateur b one nine two seven two zero zero two robert urich american actor b one nine four six two zero zero three graham stuart thomas english author and garden designer b one nine zero ni
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ne two zero zero five kay walsh british actress b one nine one one holidays and observances feast days benedict joseph labre in the roman catholic church saint bernadette saint paternus saint cecilia saint fructuosus saint turibius saints martial urban eventius caecilian julia and their companions martyrs of three zero four saint drogo birthday of the queen celebrated in greenland external links bbc on this day april one five april one seven march one six may one six listing of all days this article is about associativity in mathematics for associativity in central processor unit memory cache architecture see cpu cache in mathematics associativity is a property that a binary operation can have it means that the order of evaluation is immaterial if the operation appears more than once in an expression put another way no parentheses are required for an associative operation consider for instance the equation five two one five two one adding five and two gives seven and adding one gives an end result of eight fo
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r the left hand side to evaluate the right hand side we start with adding two and one giving three and then add five and three to get eight again so the equation holds true in fact it holds true for all real numbers not just for five two and one we say that addition of real numbers is an associative operation associative operations are abundant in mathematics and in fact most algebraic structures explicitly require their binary operations to be associative however many important and interesting operations are non associative one common example would be the vector cross product definition formally a binary operation on a set s is called associative if it satisfies the associative law x y z x y z qquad mboxx y z in s the evaluation order does not affect the value of such expressions and it can be shown that the same holds for expressions containing any number of operations thus when is associative the evaluation order can therefore be left unspecified without causing ambiguity by omitting the parentheses and wr
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iting simply x y z examples some examples of associative operations include the following in arithmetic addition and multiplication of real numbers are associative i e left begin x y z x y z x y z quad x y z x y z x y z qquad qquad qquad quad end right mboxx y z in mathbb addition and multiplication of complex numbers and quaternions is associative addition of octonions is also associative but multiplication of octonions is non associative the greatest common divisor and least common multiple functions act associatively left begin operatorname operatorname x y z operatorname x operatorname y z operatorname x y z quad operatorname operatorname x y z operatorname x operatorname y z operatorname x y z quad end right mboxx y z in mathbb matrix multiplication is associative because linear transformations can be represented by matrices one can immediately conclude that linear transformations compose associatively taking the intersection or the union of sets left begin a cap b cap c a cap b cap c a cap b cap c quad
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a cup b cup c a cup b cup c a cup b cup c quad end right mboxa b c if m is some set and s denotes the set of all functions from m to m then the operation of functional composition on s is associative f circ g circ h f circ g circ h f circ g circ h qquad mboxf g h in s slightly more generally given four sets m n p and q with h m to n g n to p and f p to q then f circ g circ h f circ g circ h f circ g circ h as before in short composition of maps is always associative non associativity a binary operation on a set s that does not satisfy the associative law is called non associative symbolically x y z ne x y z qquad mboxx y z in s for such an operation the order of evaluation does matter subtraction division and exponentiation are well known examples of non associative operations begin five three two ne five three two quad four two two ne four two two qquad qquad two ne two one two quad qquad qquad end in general parentheses must be used to indicate the order of evaluation if a non associative operation appears
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more than once in an expression however mathematicians agree on a particular order of evaluation for several common non associative operations this is simply a syntactical convention to avoid parentheses a left associative operation is a non associative operation that is conventionally evaluated from left to right i e left begin x y z x y z qquad qquad quad w x y z w x y z quad mbox qquad qquad qquad qquad qquad qquad end right mboxw x y z in s while a right associative operation is conventionally evaluated from right to left left begin x y z x y z qquad qquad quad w x y z w x y z quad mbox qquad qquad qquad qquad qquad qquad end right mboxw x y z in s both left associative and right associative operations occur examples are given below more examples left associative operations include the following subtraction and division of real numbers x y z x y z qquad mboxx y z in mathbb x y z x y z qquad qquad quad mboxx y z in mathbb mboxy ne zero z ne zero right associative operations include the following exponentia
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tion of real numbers x x the reason exponentiation is right associative is that a repeated left associative exponentiation operation would be less useful multiple appearances could and would be rewritten with multiplication x y z x non associative operations for which no conventional evaluation order is defined include the following taking the pairwise average of real numbers ne ne qquad mboxx y z in mathbb taking the relative complement of sets a backslash b backslash c ne a backslash b backslash c qquad mboxa b c venn diagram of the relative complements a b c and a b c the green part in the left venn diagram represents a b c the green part in the right venn diagram represents a b c see also a semigroup is a set with an associative binary operation commutativity and distributivity are two other frequently discussed properties of binary operations power associativity and alternativity are weak forms of associativity abstract algebra elementary algebra binary operations the apache software foundation asf is a
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non profit corporation classified as five zero one c three in the united states to support apache software projects including the apache http server the asf was formed from the apache group and incorporated in delaware usa in june one nine nine nine the apache software foundation is a decentralized community of developers the software they produce is distributed under the terms of the apache license and are therefore free software open source software the apache projects are characterized by a collaborative consensus based development process and an open and pragmatic software license each project is managed by a self selected team of technical experts who are active contributors to the project the asf is a meritocracy implying that membership to the foundation is granted only to volunteers who have actively contributed to apache projects among the asf s objectives are to provide legal protection to volunteers working on apache projects and to prevent the apache brand name from being used by other organizatio
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ns without permission the asf also holds several apachecon conferences each year highlighting apache projects related technology and allowing apache developers to gather together projects formally recognized apache projects include apache http server web server ant java based build tool apr apache portable runtime a portability library written in c beehive a java visual object model cocoon xml publishing framework db database solutions apache derby a pure java relational database management system directory a directory server supporting ldap and other protocols apache excalibur inversion of control container named fortress and related components apache forrest documentation framework based upon cocoon geronimo application server a java ee server apache gump integration dependencies and versioning management incubator for aspiring asf projects jakarta server side java including its own set of sub projects apache james java email and news server lenya content management system logging logging services for appli
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cation debugging and auditing including log four j lucene text search engine library written entirely in java maven java project management and comprehension tool myfaces javaserver faces implementation mod perl dynamic websites using perl apache portals web portal related software spamassassin email filter used to identify spam struts java web applications framework tcl dynamic websites using tool command language tomcat a web container for serving servlets and jsp web services web service related systems xml xml solutions for the web xmlbeans xml java binding tool xml graphics conversion of xml formats to graphical output board of directors the current board of directors includes ken coar justin erenkrantz dirk willem van gulik jim jagielski ben laurie stefano mazzocchi sam ruby greg stein chairman sander striker history the history of the apache software foundation is linked to the apache http server the work on which started in one nine nine four a group of eight developers started working on enhancing th
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e ncsa httpd daemon they were brian behlendorf roy fielding rob hartill david robinson cliff skolnick randy terbush robert s thau and andrew wilson with additional contributions from eric hagberg frank peters and nicolas pioch the enhanced product called the apache server was released in april one nine nine five in one nine nine nine members of the apache group formed the foundation to provide support for the apache http server the asf has a membership of one five one members and approximately one zero zero zero committers as of two zero zero five external links http www apache org http wiki apache org general http wiki apache org apachecon frontpage free and open source software foundations nonprofit technology the americans with disabilities act of one nine nine zero is the short title of united states public law one zero one three three six one zero four stat three two seven july two six one nine nine zero codified at et seq signed into law on july two six one nine nine zero by president george h w bush it
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is a wide ranging civil rights law that prohibits discrimination based on disability it affords similar protections against discrimination to americans with disabilities as the civil rights act of one nine six four which made discrimination based on race religion sex national origin and other characteristics illegal certain specific conditions are excluded including alcoholism and transsexuality structure the americans with disabilities act commonly referred to as the ada consists of three introductory sections and five titles introductory sections table of contents findings and purposes definitions main section title i employment title ii public services and public transportation title iii public accommodations and commercial facilities title iv telecommunications title v groups who worked to pass the ada the ada is notable because many disparate groups many of which had never worked before came together for a common purpose in addition other civil rights groups outside the disability community helped aids
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action council aids national interfaith network american civil liberties union american foundation for the blind americans disabled for accessible public transit adapt association for education and rehabilitation of the blind and visually handicapped association for retarded citizens consortium for citizens with disabilities disability rights education and defense fund dole foundation eastern paralyzed veterans of america epilepsy foundation of america human rights campaign fund institution for rehabilitation and research leadership conference on civil rights legal action center mental health law project national association of developmental disabilities councils national association of protection and advocacy systems national center for law and the deaf national council of independent living national council on disability national disability action center national easter seals society national organization responding to aids paralyzed veterans of america president s committee on employment of people with dis
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abilities society for accessible travel i know there may have been concerns that the ada may be too vague or too costly or may lead endlessly to litigation but i want to reassure you right now that my administration and the united states congress have carefully crafted this act we ve all been determined to ensure that it gives flexibility particularly in terms of the timetable of implementation and we ve been committed to containing the costs that may be incurred let the shameful wall of exclusion finally come tumbling down controversy inherent flaws some critics argue that enactment of the ada has resulted in little progress in eliminating such discrimination because the remedies allowed under the law are primarily complaint driven that is individuals must make complaints of discrimination to the person or agency charged with handling such complaints only after which the agency may take action each title of the act created an agency to handle such complaints ranging from bodies of the federal executive branc
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h to local civil rights enforcement agencies further individuals under each title have the private right of action that is the right to privately sue the alleged discriminating person or body many of these lawsuits have helped to clarify provisions of the act as the courts have interpreted the law in specific cases creating a body of legal precedent criticism although it has greatly improved the quality of life for people with severe physical disabilities the ada has also been heavily criticized for being overinclusive in its reach in turn the ada allegedly serves as a legal haven for malingerers and so called professional plaintiffs who make a living out of suing noncompliant businesses and collecting monetary damages the ada was the target of a vicious media backlash in mid one nine nine seven after the equal employment opportunity commission published its ada guidelines in march for example the onion satirized the ada with an article about the passage of the americans with no abilities act and the simpsons
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ran an episode in which homer simpson tried to become grossly obese so he would be exempt under the ada from a mandatory workplace fitness program the underlying debate is over whether the ada should cover people with disabilities that are not totally and catastrophically disabling most people agree that a person with a severe physical disability like paraplegia should be accommodated but they are less likely to agree when the disability in question is a mental illness like clinical depression or consists of minor neck or back pain see neuropathy others believe that accommodation laws put too many restrictions on the free market and should be repealed references linda hamilton krieger ed backlash against the ada reinterpreting disability rights ann arbor university of michigan press two zero zero three switzer jacqueline vaughn disabled rights american disability policy and the fight for equality georgetown university press two zero zero three see also accessibility disability rights movement list of disabil
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ity rights activists includes a list of people who helped pass the ada list of anti discrimination acts disability discrimination act related categories ada constitutionality related cases for cases determining the constitutionality of some of the ada s provisions see tennessee v lane board of trustees of the university of alabama v garrett external links text of the act mises org article what is disabled how ada applies to disability discrimination ada resource center overview of ada idea and section five zero four update two zero zero one overview of ada idea and section five zero four employment of people with disabilities accessible web design testing students with disabilities one nine nine zero in law united states federal civil rights legislation disability legislation rights of the disabled active recall is a principle of efficient learning which says that we need to actively stimulate memory in the learning process it is an opposite to passive review in which the learning material is processed passiv
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ely e g by reading watching etc for example when you read a text about george washington this is passive review if you answer a question who was the first us president this is active recall active recall is many times more efficient in consolidating long term memory this is why just reading your study notes before exam is not likely to leave a long lasting memory trace on the other hand if you ask your colleague to test you on the same material the results will be better in the long run because our recall of a memory may be influenced by its position within a sequence of self test questions it can be advantageous to randomise the order of those questions this could be done for instance by putting questions and answers in a spreadsheet and sorting them by values produced by a randomisation function flashcards are also often used to stimulate active recall in education it is at the start of a learning task that active recall tasks need to be at their most frequent for retention as long term memories form rates
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of testing can be reduced recognition of this fact may aid efficient learning for more information on improving memory see mnemonics memory mnemonics the apple i was an early personal computer and the first to combine a keyboard with a microprocessor and a connection to a monitor the apple i was designed by steve wozniak originally for personal use wozniak s friend steve jobs had the idea of selling the computer it was sold as apple s first product beginning in april one nine seven six its retail price was us six six six six six about two zero zero units were produced unlike other hobbyist computers of its day which were sold as kits the apple i was a fully assembled circuit board containing about three zero chips however to make a working computer users still had to add a case power supply keyboard and display an optional board providing a cassette interface for storage was later released at a cost of seven five the apple i is sometimes credited as the first personal computer to be sold in fully assembled fo
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rm however some argue that the honour rightfully belongs to other machines such as the datapoint two two zero zero the apple i s use of a keyboard and monitor was distinctive competing machines such as the altair eight eight zero zero generally were programmed with front mounted toggle switches and used indicator lights red leds most commonly for output and had to be extended with separate hardware to allow connection to keyboards and monitors this made the apple i an innovative machine for its day despite its lack of graphics or sound capabilities it was discontinued in march one nine seven seven when it was replaced with the apple ii as of the turn of the millennium an estimated three zero to five zero apple is are still known to exist making it a collector s item an apple i reportedly sold for five zero zero zero zero at auction in one nine nine nine however a more typical price for an apple i is in the one four zero zero zero one six zero zero zero range a software compatible clone of the apple i replica
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i produced using modern components was released in two zero zero three at a price of around two zero zero references owad tom two zero zero five apple i replica creation back to the garage rockland ma syngress publishing copyright two zero zero five isbn one nine three one eight three six four zero x external links apple i owners club macintosh prehistory the apple i the replica one early microcomputers apple hardware apple ii family image apatosaurus gif image width two four zero px regnum animalia phylum chordata classis sauropsida superordo dinosauria ordo saurischia subordo sauropodomorpha infraordo sauropoda familia diplodocidae genus apatosaurus genus authority marsh one eight seven seven subdivision ranks species subdivision apatosaurus ajax apatosaurus excelsus apatosaurus louisae apatosaurus ah pat o sawr us meaning deceptive lizard because its chevron bones were like those of mosasaurus greek apatelos deceptive sauros lizard often refered to as brontosaurus is a genus of sauropod dinosaurs that live
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d about one four zero million years ago during the jurassic period they were some of the largest land animals that ever existed about four five metres one five feet tall at the hips with a length of up to two five m eight zero feet and a mass up to three five metric tonnes four zero tons the cervical vertebra and the bones in the legs were bigger and heavier than that of diplodocus but they both had the long neck and tail the skull was first identified in one nine seven five a century after it got its name apatosaurus had a large claw on its first digit thumb the tail was held above the ground during normal locomotion environment early on it was believed that apatosaurus was too massive to support its own weight on dry land so it was theorized that the sauropod must have lived partly submerged in water perhaps in a swamp recent findings do not support this in fact like its relative diplodocus apatosaurus was a grazing animal with a very long neck and a long tail that served as a counterweight fossilized footp
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rints indicate that it probably lived in herds to aid in processing food apatosaurus may have swallowed gizzard stones gastroliths the same way many birds do today its jaws alone were not sufficient to chew tough plant fibers apatosaurus perhaps lumbered along in flocks on riverbanks with trees eating off the top leaves scientists believe that these sauropods could not raise their neck to an angle of nine zero degrees as doing so would slow blood flow to the brain excessively blood starting at the body proper would take two or more minutes to reach the brain furthermore studies of the structure of the neck vertebrae have revealed that the neck was not as flexible as previously thought no one knows how apatosaurs ate enough food to satisfy their enormous bodies they probably ate constantly pausing only to cool off drink or to remove parasites they must have slept standing upright if attacked by a predator one could defend itself by swinging its tail from side to side or stomping on the meat eater classificatio
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n and history apatosaurus correct head in one eight seven seven othniel charles marsh published notes on his discovery of apatosaurus ajax and then in one eight seven nine described another more complete dinosaur species which he speculated to represent a new genus and named brontosaurus excelsus in one nine zero three it was discovered that brontosaurus excelsus was in fact an adult apatosaurus and the name apatosaurus having been published first was deemed to have priority as the official name brontosaurus was relegated to being a synonym in the one nine seven zero s it was proven that the traditional brontosaurus image known to all was in fact an apatosaurus excelsus with a camarasaurus head mistakenly placed on its body fossils of this animal have been found in nine mile quarry and bone cabin quarry in wyoming and at sites in colorado oklahoma utah usa species a ajax is the type species of the genera and was named by the paleontologist othniel charles marsh in one eight seven seven after ajax the hero fro
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m greek mythology it is the holotype for the genera and two partial skeletons have been found including part of a skull a excelsus originally brontosaurus was named by marsh in one eight seven nine it is known from six partial skeletons including part of a skull which have been found in the united states in oklahoma utah and wyoming a louisae was named by william holland in one nine one five it is known from one partial skeleton which was found in colorado in the united states robert t bakker made a yahnahpin the type species of a new genus eobrontosaurus in one nine nine eight so it is now properly eobrontosaurus yahnahpin it was named by filla james and redman in one nine nine four one partial skeleton has been found in wyoming see also brontosaurus sauropods jurassic dinosaurs regnum animalia phylum chordata classis sauropsida ordo saurischia subordo theropoda infraordo carnosauria familia allosauridae genus allosaurus genus authority marsh one eight seven seven subdivision ranks species subdivision a ampl
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exus a ferox a jimmadseni a fragilis type allosaurus al oh sore us meaning different lizard because its vertebrae were different from those of all other dinosaurs greek allos different sauros lizard was a large carnivorous dinosaur with a length of up to one two m three nine ft it was the most common large predator in north america one five five to one four five million years ago in the jurassic period allosaurus is the official state fossil of utah in the united states description a replica allosaurus skeleton at a new zealand museum allosaurus is a classic big theropod a large skull on a short neck a long tail and reduced forelimbs its most distinctive feature is a pair of blunt horns just above and in front of the eyes although short in comparison to the hindlimbs the forelimbs are massive and bear large eagle like claws the skull shows evidence of being composed of separate modules which could be moved in relation to one another allowing large pieces of meat to be swallowed the skeleton of allosaurus like
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other theropods shows birdlike features like a wishbone and neck vertebrae hollowed by air sacs it is thought that allosaurus might have hunted in packs allowing it to bring down the large sauropods of the time allosaurus was extremely light compared to other dinosaurs its size which may have allowed it to leap onto its prey something that only small dinosaurs could do without sustaining severe injury findings allosaurus is the most common theropod in the huge section of dinosaur bearing rock in the american southwest known as the morrison formation remains have been recovered in montana wyoming south dakota colorado oklahoma new mexico and utah in the united states and in portugal curiously allosaurus shared the jurassic landscape with several other theropods including ceratosaurus and the massive torvosaurus a famous fossil bed can be found in the cleveland lloyd quarry in utah this fossil bed contains over one zero zero zero zero bones mostly of allosaurus with other dinosaurs like stegosaurus and ceratos
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aurus thrown in it is still a mystery how the remnants of so many animals can be found in one place normally the ratio of fossils of carnivorous animals over fossils of plant eaters is very small findings like these can be explained by pack hunting although this is difficult to prove one of the more significant finds was the one nine nine one discovery of big al mor five nine three a nine five complete partially articulated juvenile specimen that measured eight meters two six feet in length nineteen bones were broken or showed signs of infection which probably contributed to big al s death it was featured in the ballad of big al a special programme in the bbc s walking with dinosaurs series the fossils were excavated near shell wyoming by the museum of the rockies and the university of wyoming geological museum this skeleton was initially discovered by a swiss team led by kirby siber which later excavated a second allosaurus big al two which is the best preserved skeleton of its kind to date classification an
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d history the allosaurus big al the first allosaurus fossil to be described was a petrified horse hoof given to ferdinand vandiveer hayden in one eight six nine by the natives of middle park near granby colorado it was actually a caudal vertebra a tail bone which joseph leidy tentatively assigned first to the poicilopleuron genus and later to a new genus antrodemus however it was othniel charles marsh who gave the formal name allosaurus fragilis to the genus and type species in one eight seven seven based on much better material including a partial skeleton from garden park north of canon city colorado the name allosaurus comes from the greek allos meaning strange or different and sauros meaning lizard or reptile the species epithet fragilis is latin for fragile both refer to lightening features in the vertebrae it is unclear how many species of allosaurus there were the material from the cleveland lloyd allosaurus is much smaller and more lightly built than the huge robust allosaurus from brigham young unive
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rsity s dry mesa quarry fossils resembling allosaurus have been described from portugal allosaurus s closest relative is probably the lower cretaceous acrocanthosaurus external links allosaurus dinodata allosaurus the story of big al from the university of wyoming geological museum in laramie public pioneer utah state fossil allosaurus from utah gov allosaurus fragilis smithsonian national museum of natural history department of paleobiology list of the many possible allosaurus species theropods carnosaurs jurassic dinosaurs the ak four seven a vtomat k alashnikova one nine four seven russian one nine four seven is a gas operated assault rifle designed by mikhail kalashnikov produced by russian manufacturer izh and used in many eastern bloc nations during the cold war it was adopted and standardized in one nine four seven compared to rifles used in world war ii the ak four seven was generally lighter more compact with a shorter range a smaller seven six two three nine mm cartridge and was capable of selective
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fire it was one of the first assault rifles and surely the most prolific the ak four seven and its numerous variants have been produced in greater numbers than any other assault rifle in the two zero th century and it remains in production to this day development during the second world war germany had developed the concept of the assault rifle this concept was based on the premise that most military engagements in modern warfare were happening at fairly close range with the majority happening within one zero zero meters the power and range of full power rifle cartridges was simply overkill for a vast majority of engagements with small arms as a result a cartridge and firearm were sought that would combine the features of a submachinegun high capacity magazine and fully automatic capability with an intermediate power cartridge that would be effective to a range of three zero zero meters for the sake of manufacturing this was done by shortening the eight mm mauser cartridge to three three mm and using a light
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er bullet the resulting sturmgewehr four four was not the first rifle to use these features it was preceded by earlier italian and russian designs the germans were however the first to produce and field a sufficient number of the type to properly evaluate its utility they fielded the weapon in large numbers against the russians towards the end of the war this experience deeply influenced russian doctrine in the years following the war mikhail kalashnikovaccording to the story tank sergeant mikhail kalashnikov began imagining his weapon while still in the hospital after being wounded in the battle of bryansk he had been informed that a new weapon was required for the seven six two three nine mm cartridge developed by elisarov and semin in one nine four three sudayev s pps four three submachine gun was preferred to kalashnikov s design kalashnikov redesigned his losing design after examining a german stg four four in one nine four six it has been suggested that kalashnikov was chosen to lead a team of designers
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more for propaganda value due to his war hero status rather than for his expertise following soviet patterns in other industries despite circumstantial evidence mikhail kalashnikov denies that his rifle was based on the german assault rifle internally the ak four seven owes much to the m one garand rifle the double locking lugs unlocking raceway and trigger mechanism are clearly derived from the earlier american design this is not surprising as millions of garand rifles had operated reliably in combat around the globe though mechanically similar to the garand the ak four seven clearly borrows its cartridge concept weapon layout gas system and construction methods from the stg four four where the kalashnikov rifle differs is in its simplification of those contributing designs and adaptation to mass production by relatively unskilled labor the ak four seven can be seen as a fusion of the best that the m one garand offered combined with the best aspects of the stg four four made by the best processes available
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in the soviet union at the time there were many difficulties during the initial phase of production the first production models had stamped sheet metal receivers alarmingly these rifles were wearing out rapidly instead of halting production a heavy machined receiver was substituted for the sheet metal receiver this was a more costly process but the use of machined receivers accelerated production as tooling and labor for the earlier mosin nagant rifle s machined receiver were easily adapted partly because of these problems the soviets were not able to distribute large numbers of the new rifle to soldiers until one nine five six once manufacturing difficulties had been overcome a redesigned version designated the akm m for modernized or upgraded was introduced in one nine five nine this new model used a stamped sheet metal receiver and featured a slanted device on the end of the barrel to compensate for muzzle rise under recoil the akm was exported around the world to aid in the spread of communism licensed pr
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oduction of the kalashnikov weapons abroad as well as unlicensed production was almost exclusively of the akm despite this rifles of this pattern are almost universally referred to as ak four seven s in one nine seven eight the soviet union began replacing their ak four seven and akm rifles with a newer design the ak seven four this new rifle and cartridge had only started being exported to eastern european nations when the soviet union collapsed east germany made mpiks seven two folding stock variant of akm in the hands of a u s marine notable features the ak four seven is simple and inexpensive to manufacture and easy to clean and maintain its ruggedness and reliability is legendary the large gas piston generous clearances between moving parts and tapered cartridge case design allow the gun to endure large amounts of foreign matter and fouling without failing to cycle this reliability comes at the cost of accuracy the notched rear tangent iron sight is calibrated with each numeral denoting hundreds of meter
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s the front sight is a post adjustable for elevation in the field windage adjustment is done by the armory prior to issue the battle setting places the round within a few centimeters above or below the point of aim out to approximately two five zero meters this point blank range setting allows the shooter to fire the gun at any close target without adjusting the sights longer settings are intended for area suppression these settings mirror the mosin nagant and sks rifles which the ak four seven replaced this eased transition and simplified training the bore and chamber as well as the gas piston and the interior of the gas cylinder are generally chromium plated this plating dramatically increases the life of these parts by resisting corrosion and wear chrome plating of critical parts is now common on most modern military weapons ballistics the standard ak four seven or akm fires a seven six two three nine mm round with a muzzle velocity of seven one zero m s two three two nine ft s muzzle energy is one nine ni
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ne zero joules one four six seven ft lbf cartridge case length is three eight six mm weight is one eight two one g projectile weight is normally eight g one two three gr the ak four seven and akm with the seven six two three nine mm cartridge have an effective range of around three zero zero meters for comparison the seven six two x five four mm r cartridge has a projectile of one two g one eight five gr at a velocity of eight one eight m s two six eight three ft s for approximately four zero zero zero joules two nine five zero ft lbf of energy operating cycle a diagram showing the design of akm to fire the operator inserts a loaded magazine moves the selector lever to the lowest position pulls back and releases the charging handle and then pulls the trigger in this setting the gun fires once requiring the trigger be released and depressed again for the next shot until the magazine is exhausted with the selector in the middle position the rifle continues to fire automatically cycling fresh rounds into the cha
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mber until the magazine is exhausted or pressure is released from the trigger dismantling the gun involves the operator depressing the magazine catch and removing the magazine the charging handle is pulled to the rear and the operator inspects the chamber to verify the gun is unloaded the operator presses forward on the retainer button at the rear of the receiver cover while simultaneously lifting up on the rear of the cover to remove it he then pushes spring assembly forward and lifts it from its raceway withdrawing it out of the bolt carrier and to the rear the operator must then pull the carrier assembly all the way to the rear lift it and then pull it away he removes the bolt by pushing it to the rear of the bolt carrier rotating the bolt so the camming lug clears the raceway on the underside of the bolt carrier and then pulls it forward and free when cleaning the operator will pay special attention to the barrel bolt face and gas piston then oil lightly and reassemble small arms captured in fallujah iraq
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by the u s marine corps in two zero zero four include two ak four seven s first and third from the left legal status in the usa private ownership of fully automatic ak four seven rifles is tightly regulated by the national firearms act of one nine three four the gun control act of one nine six eight ceased import of foreign manufactured fully automatic firearms for civilian sales and possession effectively halting further importation of civilian accessible ak four seven rifles in one nine eight six an amendment to the firearm owners protection act stopped all future domestic manufacture of fully automatic weapons for civilian use however machine guns manufactured domestically prior to one nine eight six and imported prior to one nine six eight may be transferred between civilians in accordance with federal and state law several soviet and chinese rifles made it into the u s during the mid one nine six zero s when returning vietnam veterans brought them home after capture from enemy troops many of these were
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properly registered during the one nine six eight nfa amnesty in addition several states have laws on their books outlawing private possession of full automatic firearms even with nfa approval certain semi automatic ak four seven models were banned by the now expired federal assault weapons ban of one nine nine four two zero zero four a semi automatic rifle similar externally to the ak four seven but operably identical to many hunting rifles was used in a much publicized one nine eight nine shooting in a stockton california schoolyard and in the one nine nine three murders outside of the langley virginia headquarters of the central intelligence agency see mir amir kansi another much publicized use of the ak four seven in the united states happened when bank robbers exchanged fire with police after a botched robbery the north hollywood shootout involved ak four seven s that were illegal to possess ignoring the law while committing numerous other felonies both assailants were shot and died at the scene citing t
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hese tragedies gun control advocates lobbied for strict controls on military style semi automatic firearms even though most criminals do not buy their weapons legally cultural influence coat of arms of mozambique the ak four seven and its derivatives are favored by many non western powers because of their ease of use robustness simplicity and manufacturing cost effectiveness estimates for production range over one zero zero million units during most of the cold war the soviet union and china followed a military assistance program supplying their arms and technical knowledge to numerous countries in addition another policy saw the supply of weapons free of charge to pro communist fighters such as the sandinistas and viet cong this policy was mirrored in the west with the united states providing arms to such groups as the afghan mujahideen the broad proliferation of this weapon is reflected by more than just its numbers the ak four seven is included in the mozambique flag and coat of arms formerly also in burki
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na faso coat of arms and the hizballah flag kalash a shortened form of kalashnikov is used as a name for boys in some african countries moreover moviemakers who arm cinema terrorists gang members e g films like boyz n the hood and bad guys in general with ak four seven s add much to the weapon s cultural mystique numerous computer and video games feature ak four seven s the weapon is used as a backdrop for reporters during terrorism news stories fiction writers are also quick to arm their characters with the weapon the sheer ubiquity of the ak four seven its iconography the fact that it possesses easily the most distinguishable weapon outline and its nefarious association with violent conflict will ensure a significant and conspicuous impact on society cuban revolutionary armed forces armed with ak four seven s engaging in a training exercise versions kalashnikov variants include ak four seven one nine four eight five one seven six two three nine mm the very earliest models had a stamped sheet metal receiver
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now rare ak four seven one nine five two seven six two three nine mm has a milled receiver and wooden buttstock and handguard barrel and chamber are chrome plated to resist corrosion rifle weight four two kg aks four seven featured a downward folding metal stock similar to that of the german mp four zero for use in the restricted space in the bmp infantry combat vehicle rpk seven six two three nine mm squad automatic rifle version with longer barrel and bipod akm seven six two three nine mm a simplified lighter version of the ak four seven receiver is made from stamped and riveted sheet metal a slanted muzzle device was added to counter climb in automatic fire rifle weight three six one kg akms seven six two three nine mm folding stock version of the akm intended for airborne troops ak seven four series five four five x three nine mm see main article for details a romanian soldier aids a u s marine in clearing an rpk during the weapons familiarization phase of exercise rescue eagle two zero zero zero at babad
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ag range romania on july one five two zero zero zero other versions the ak four seven and its descendants are or have been manufactured in the following countries egypt china north korea east germany poland yugoslavia as the m seven zero and m eight zero series romania hungary as amd six three and amd six five iraq and bulgaria certainly more have been produced elsewhere but the above list represents major producers an updated akm design is still produced in russia the basic design of the ak four seven has been used as the basis for other successful rifle designs such as the finnish valmet six two seven six the israeli galil the indian insas and the yugoslav zastava weapon m seven six and m seven seven and m seven seven eight two not to be confused with the barrett m eight two rifles several bullpup designs have surfaced although none have been produced in quantity quotes yuri orlov the protagonist from the lord of war film of all the weapons in the vast soviet arsenal nothing was more profitable than avtomat
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kalashnikova model of one nine four seven more commonly known as the ak four seven or kalashnikov it s the world s most popular assault rifle a weapon all fighters love an elegantly simple nine pound amalgamation of forged steel and plywood it doesn t break jam or overheat it ll shoot whether it s covered in mud or filled with sand it s so easy even a child can use it and they do the soviets put the gun on a coin mozambique put it on their flag since the end of the cold war the kalashnikov has become the russian people s greatest export after that comes vodka caviar suicidal novelists one thing is for sure no one was lining up to buy their cars ordell robbie the protagonist from the film jackie brown there it is the ak four seven when you absolutely positively have to kill every single motherfucker in the room accept no substitute see also list of modern armament manufacturers civilian cousins of the ak four seven comparison of the ak four seven and m one six ak seven four ak one zero one ak one zero three a
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k one zero seven includes ak one zero eight chinese type five six assault rifle karabinek granatnik wz one nine six zero references fackler et al one nine eight four wounding potential of the russian ak seven four assault rifle journal of trauma injury infection kalashnikov home page ak four seven assault rifle ak four seven everything two com automat kalaschnikow film documented the man and his machine ak four seven s self loading carbine usa home of the ak four seven on the internet ak four seven assault rifle sovietarmy com nazarian s gun s recognition guide modern firearms akm assault rifle sovietarmy com animation of an ak four seven action in operation video links nazarian s gun s recognition guide film how ak four seven work presentation video clip nazarian s gun s recognition guide film ak four seven presentation swf kurzzeitmesstechnik mehl slow motion video of ak four seven action in operation divx movie bruce canfield animation of ak four seven action in operation manual nazarian s gun s recognitio
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n guide manual ak four seven manual pdf seven six two mm firearms assault rifles cold war weapons of the soviet union the atanasoff berry computer was the first electronic digital computer and was a major step in the history of computing it was built by dr john vincent atanasoff and clifford e berry at iowa state university during one nine three seven four two the atanasoff berry computer represented several innovations in computing including a binary system of arithmetic parallel processing regenerative memory and a separation of memory and computing functions it is sometimes referred to by its initials abc john vincent atanasoff was awarded the national medal of technology by president george h w bush in a ceremony at the white house on november one three one nine nine zero the atanasoff berry computer constructed in the basement of the physics building at iowa state university took over two years to complete due to lack of funds the prototype was first demonstrated in november of one nine three nine the co
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mputer weighed more than seven hundred pounds three two zero kg it contained approximately one mile one six km of wire two eight zero dual triode vacuum tubes three one thyratrons and was about the size of a desk it was not a turing complete computer which distinguishes it from later more general machines such as the one nine four six eniac one nine four nine edvac the university of manchester designs or alan turing s post war designs at npl and elsewhere nor did it implement the stored program architecture that made practical fully general purpose reprogrammable computers the machine was however the first to implement three critical ideas that are still part of every modern computer using binary digits to represent all numbers and data performing all calculations using electronics rather than wheels ratchets or mechanical switches organizing a system in which computation and memory are separated in addition the computer pioneered the use of regenerative capacitor memory as in the dram still widely used today
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the memory of the atanasoff berry computer was a pair of drums each containing one six zero zero capacitors that rotated on a common shaft once per second the capacitors on each drum were organized into three two bands of five zero three zero active bands and two spares in case a capacitor failed giving the machine a speed of three zero additions subtractions per second data was represented as five zero bit binary fixed point numbers the electronics of the memory and arithmetic units could store and operate on six zero such numbers at a time three zero zero zero bits the ac power line frequency of six zero hz was the primary clock rate for the lowest level operations the logic functions were fully electronic implemented with vacuum tubes the family of logic gates ranged from inverters to two and three input gates the input and output levels and operating voltages were compatible between the different gates each gate consisted of one inverting vacuum tube amplifier preceded by a resistor divider input network
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that defined the logical function although the atanasoff berry computer was an important step up from earlier computing machines it was not a stored program computer an operator was needed to operate the control switches to set up its functions much the way boot programs would be entered in later computers selection of the operation to be performed reading writing converting to or from binary to decimal or reducing a set of equations was made by front panel switches and in some cases jumpers there were two forms of input and output primary user input and output and an intermediate results output and input the intermediate results storage allowed operation on problems too large to be handled entirely within the electronic memory intermediate results were written onto paper sheets by electrostatically modifying the resistance at one five zero zero locations to represent three zero of the five zero bit numbers each sheet could be written or read in one second the reliability of the system was limited to about o
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ne error in one zero zero zero zero zero calculations by these units primarily attributed to lack of control of the sheets material characteristics in retrospect a solution could have been to add a parity bit to each number as written this problem was not solved by the time atanasoff left the university for war related work primary user input was via standard punched cards and output via a front panel display the abc was designed for a fairly specific purpose the solution of systems of simultaneous linear equations it could handle systems with up to twenty nine equations which was large for the time problems of this scale were becoming common in physics the department in which john atanasoff worked basically it could be fed two linear equations with up to twenty nine variables and a constant term and eliminate one of the variables this process would have to be repeated manually for each of the equations which would result in a system of equations with one fewer variables then the whole process would have to b
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e repeated to eliminate another variable the initial funds to start development and demonstrate the circuits involved was from the agronomy department which was also interested in such problems for economic and research analysis further funding to complete the machine came from research corporation of america in new york presper eckert and john mauchly were the first to patent a digital computing device their eniac computer abc had been examined by john mauchly in june one nine four one and is alleged to have influenced his later work on eniac although mauchly denied this in one nine six seven honeywell started a court case against sperry rand in an attempt to break their patent based on the abc being prior art the court released its final judgement on october one nine one nine seven three in sperry rand vs honeywell the court voided the eniac patent as a derivative of john atanasoff s invention the decision was not appealed atanasoff was quite generous in stating there is enough credit for everyone in the in
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vention and development of the electronic computer eckert and mauchly received most of the credit for inventing the first electronic digital computer historians now say that the atanasoff berry computer was the first the original abc was eventually dismantled when the university converted the basement to classrooms and all of its pieces except for one memory drum were discarded in one nine nine seven a team of researchers from ames laboratory located on the iowa state campus finished building a working replica of the atanasoff berry computer for a cost of three five zero zero zero zero this replica dispelled any doubt over whether or not the abc actually could perform the tasks it was designed to do the new abc is now on permanent display in the first floor lobby of the durham center for computation and communication at iowa state university see also history of computing hardware references anthony ralston and edwin d reilly ed encyclopedia of computer science three rd ed one nine nine three van nostrand rein
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