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dependent on r by varying the parameter r the following behaviour is observed with r between zero and one the population will eventually die independent of the initial population with r between one and two the population will quickly stabilize on the value frac independent of the initial population with r between two and three the population will also eventually stabilize on the same value frac but first oscillates around that value for some time the rate of convergence is linear except for r three when it is dramatically slow less than linear with r between three and one six approximately three four five the population will oscillate between two values forever these two values are dependent on r but independent of the initial population with r between three four five and three five four approximately the population will oscillate between four values forever again this behavior does not depend on the initial population with r slightly bigger than three five four the population will oscillate between eight va |
lues then one six three two etc the lengths of the parameter intervals which yield the same number of oscillations decrease rapidly the ratio between the lengths of two successive such bifurcation intervals approaches the feigenbaum constant four six six nine dots all of these behaviors do not depend on the initial population at r three five seven approximately is the onset of chaos we can no longer see any oscillations slight variations in the initial population yield dramatically different results over time a prime characteristic of chaos most values beyond three five seven exhibit chaotic behaviour but there are still certain isolated values of r that appear to show non chaotic behavior these are sometimes called islands of stability for instance around three eight two there is a range of parameters r which show oscillation between three values and for slightly higher values of r oscillation between six values then one two etc there are other ranges which yield oscillation between five values etc all oscil |
lation periods do occur these behaviours are again independent of the initial value beyond r four the values eventually leave the interval zero one and diverge for almost all initial values a bifurcation diagram summarizes this the horizontal axis shows the values of the parameter r while the vertical axis shows the possible long term values of x bifurcation diagram for the logistic map the bifurcation diagram is a fractal if you zoom in on the above mentioned value r three eight two and focus on one arm of the three say the situation nearby looks just like a shrunk and slightly distorted version of the whole diagram the same is true for all other non chaotic points this is an example of the deep and ubiquitous connection between chaos and fractals a gnu octave script to generate bifurcation diagrams chaos and the logistic map the relative simplicity of the logistic map makes it an excellent point of entry into a consideration of the concept of chaos a rough description of chaos is that chaotic systems exhibi |
t a great sensitivity to initial conditions a property of the logistic map for most values of r between about three five seven and four as noted above a common source of such sensitivity to initial conditions is that the map represents a repeated folding and stretching of the space on which it is defined in the case of the logistic map the quadratic difference equation one describing it may be thought of as stretching and folding operation on the interval zero one two and three dimensional phase diagrams show the stretching and folding structure of the logistic map the following figure illustrates the stretching and folding over a sequence of iterates of the map figure a left gives a two dimensional phase diagram of the logistic map for r four and clearly shows the quadratic curve of the difference equation one however we can embed the same sequence in a three dimensional phase space in order to investigate the deeper structure of the map figure b right demonstrates this showing how initially nearby points be |
gin to diverge particularly in those regions of x t corresponding to the steeper sections of the plot this stretching and folding does not just produce a gradual divergence of the sequences of iterates but an exponential divergence see lyapunov exponents evidenced also by the complexity and unpredictability of the chaotic logistic map in fact exponential divergence of sequences of iterates explains the connection between chaos and unpredictability a small error in the supposed initial state of the system will tend to correspond to a large error later in its evolution hence predictions about future states become progressively indeed exponentially worse when there are even very small errors in our knowledge of the initial state since the map is confined to an interval on the real number line its dimension is less than or equal to unity numerical estimates yield a correlation dimension of zero five zero zero zero zero zero five grassberger one nine eight three a hausdorff dimension of about zero five three eight |
grassberger one nine eight one and an information dimension of zero five one seven zero nine seven six grassberger one nine eight three for r three five six nine nine four five six onset of chaos note it can be shown that the correlation dimension is certainly between zero four nine two six and zero five zero two four it is often possible however to make precise and accurate statements about the likelihood of a future state in a chaotic system if a possibly chaotic dynamical system has an attractor then there exists a probability measure that gives the long run proportion of time spent by the system in the various regions of the attractor in the case of the logistic map with parameter r four and an initial state in zero one the attractor is also the interval zero one and the probability measure corresponds to the beta distribution with parameters a zero five and b zero five unpredictability is not randomness but in some circumstances looks very much like it hence and fortunately even if we know very little a |
bout the initial state of the logistic map or some other chaotic system we can still say something about the distribution of states a long time into the future and use this knowledge to inform decisions based on the state of the system all hope is not lost in a chaotic world see also malthusian growth model chaos theory list of chaotic maps logistic function external links logistic model at cut the knot emergence of chaos at cut the knot logistic map contains an interactive computer simulation of the logistic map the chaos hypertextbook an introductory primer on chaos and fractals interactive logistic map with iteration and bifurcation diagrams in java macintosh quadratic map program references textbooks journal articles chaotic maps for other uses of the terms levant levante or levantine see levant disambiguation the levant levant is an imprecise geographical term historically referring to a large area in the middle east south of the taurus mountains bounded by the mediterranean sea on the west and by the no |
rthern arabian desert and upper mesopotamia to the east the levant does not include the caucasus mountains any part of the arabian peninsula proper or anatolia although at times cilicia may be included the sinai peninsula may also be included but may be excluded as a marginal area forming a land bridge between the levant and northern egypt at times levantine cultures and peoples dominated the region between the sinai and the nile river but that region is usually excluded from the geographical levant for what the levant has been called by natives and others over time see names of the levant the term levant is first attested in english in one four nine seven originally used in the wider sense of mediterranean lands east of italy it derives from the middle french levant the participle of lever to raise as in soleil levant rising sun from the latin levare it thus refered to the direction of the rising sun from the perspective of those who first used it as such it is broadly equivalent to the arabic term mashriq t |
he land where the sun rises the term became current in english in the one six th century along with the first english merchant adventurers in the region english ships appeared in the mediterranean in the one five seven zero s and the english merchant company signed its agreement capitulations with the grand turk in one five seven nine braudel the name levantine was applied to people of italian especially venetian and genoese french or other mediterranean origin who lived in asia minor during the period of the ottoman empire the majority of these people were descendants of traders or of the inhabitants of crusader states when the british took over palestine in the aftermath of the first world war some of the new rulers adapted the term pejoratively to refer to inhabitants of mixed arab and european descent and to europeans usually french italian or greek who had gone native and adopted local dress and customs the french mandates of syria and lebanon from one nine two zero to one nine four six were called the l |
evant states the term became common in archaeology at that time as many important early excavations were made then such as at ebla mari and ugarit since these sites could not be classified as mesopotamian north african or arabian they came to be referred to as levantine today levant is most typically used by archaeologists and historians with reference to the prehistory and the ancient and medieval history of the region as when discussing the crusades but the term is still employed occasionally to refer to modern or contemporary events peoples states or parts of states in the same region namely israel jordan lebanon palestine or syria see also levantine arabic history of the levant southern levant canaan greater syria bilad al sham mesopotamia council for british research in the levant references braudel fernand the mediterranean and the mediterranean world in the age of phillip ii levant near east league of nations mandates were territories established under article two two of the covenant of the league of n |
ations two eight june one nine one nine upon the entry into force of the charter of the united nations in late one nine four five the mandates of the league of nations became united nations trust territories as agreed earlier at the yalta conference all the territories subject to league of nations mandates were previously controlled by states defeated in world war i principally imperial germany and the ottoman empire the mandates were fundamentally different from protectorates in that the mandatory power undertook obligations to the inhabitants of the territory and to the league of nations the process of establishing the mandates consisted of two phases the formal removal of sovereignty of the previously controlling states the transfer of mandatory powers to individual states among the allied powers the exact level of control by the mandatory power over each mandate was decided on an individual basis by the league of nations however in every case the mandatory power was forbidden to construct fortifications o |
r raise an army within the mandate and was required to present an annual report on the territory to the league of nations despite this mandates were seen as de facto colonies of the empires of the victor nations the mandates were divided into three distinct groups based upon the level of development each population had achieved at that time class a mandates the first group or class a mandates were areas fomerly controlled by the ottoman empire deemed to have reached a stage of development where their existence as independent nations can be provisionally recognized subject to the rendering of administrative advice and assistance by a mandatory until such time as they are able to stand alone the wishes of these communities must be a principal consideration in the selection of the mandatory the class a mandates assigned to france were syria and lebanon iraq palestine which then included transjordan was assigned to the united kingdom uk by one nine four nine all of these mandates had been replaced by new governme |
nts class b mandates the second group or class b mandates which included the region of central africa were deemed to require a greater level of control by the mandatory power the mandatory must be responsible for the administration of the territory under conditions which will guarantee freedom of conscience and religion the mandatory power was forbidden to construct military or naval bases within the mandates the class b mandate assigned to belgium was ruanda urundi togoland and the cameroons were assigned in part to france and in part to the uk tanganyika was assigned to the uk class c mandates a final group the class c mandates including south west africa and certain of the south pacific islands were considered to be best administered under the laws of the mandatory as integral portions of its territory the class c mandates consisted of south west africa which was administered by south africa former german samoa assigned to new zealand new guinea and nauru assigned to australia and the german islands in the |
pacific north of the equator which were assigned to japan as the japanese mandate of the pacific islands treaties germany s divestiture of territories was accomplished in the treaty of versailles of one nine one nine and alloted to the allied powers on may seven one nine one nine ottoman territorial claims were first dispensed with in the treaty of sevres of one nine two zero and later finalized in the treaty of lausanne of one nine two three the turkish territories were alloted to the allied powers in the conference of san remo of one nine two zero all of the former mandates are now independent states the last mandate to gain independence were south west africa which gained independence as namibia in one nine nine zero after a long war with south africa references league of nations mandates the loudon classic held at the new hampshire international speedway formerly the loudon racetrack is the longest running motorcycle race in the united states lincoln is a town located in grafton county new hampshire as o |
f the two zero zero zero census the town had a total population of one two seven one lincoln which includes the villages of north lincoln and stillwater is home to the new hampshire highland games and to the flume gorge state park parts of the white mountain national forest are in the east and west the appalachian trail crosses in the northeast history lincoln in c one nine one five in one seven six four colonial governor benning wentworth granted three two four five six acres to a group of approximately seven zero land investors from connecticut lincoln was named after henry fiennes pelham clinton two nd duke of newcastle nine th earl of lincoln a cousin of the wentworth governors he held the position of comptroller of customs for the port of london under george ii and george iii which was important to trade between america and england the town would be settled about one seven eight two the one seven nine zero census indicates that it had two two inhabitants rocky soil yielded poor farming but the area s abu |
ndant timber combined with water power to run sawmills on the pemigewasset river and its east branch helped lincoln develop into a center for logging by one eight five three the merrimack river lumber company was operating the railroad transported freight and increasingly brought tourists to the beautiful mountain region in one eight nine two james e henry bought approximately one zero zero zero zero zero acres of virgin timber and established a logging enterprise at what is today the center of lincoln in one nine zero two he built a pulp and paper mill he erected the lincoln house hotel in one nine zero three although a one nine zero seven fire would nearly raze the community until he died in one nine one two henry controlled his company town installing relatives in positions of civic authority in one nine one seven henry s heirs sold the business to the parker young company which in turn sold it to the marcalus manufacturing company in one nine four six franconia paper took over in one nine five zero produc |
ing one five zero tons of paper a day until bankruptcy in one nine seven one at which time new river classification standards discouraged further paper making in lincoln tourism is today the principal business and the flume is one of the most visited attractions in the state discovered in one eight zero eight it is a natural gorge extending eight zero zero feet at the base of mount liberty walls of conway granite rise to a height of seven zero to nine zero feet and are one two to two zero feet apart cultural sites one three zero nine mi three three eight five km one three zero seven mi of it is land and zero six km zero two mi of it is water the total area is zero one seven water lincoln is drained by the pemigewasset river and its east branch kancamagus pass elevation two eight six zero feet eight seven two meters is on the kancamagus highway at the eastern boundary demographics the flume in one nine zero five as of the census two of two zero zero zero there are one two seven one people five eight three hous |
eholds and three two four families residing in the town the population density is three eight km nine seven mi there are two three three nine housing units at an average density of six nine km one seven nine mi the racial makeup of the town is nine seven four zero white zero three nine native american zero eight seven asian zero one six from other races and one one eight from two or more races zero seven one of the population are hispanic or latino of any race there are five eight three households out of which two two eight have children under the age of one eight living with them four three four are married couples living together eight nine have a female householder with no husband present and four four four are non families three five seven of all households are made up of individuals and one two seven have someone living alone who is six five years of age or older the average household size is two one eight and the average family size is two eight three in the town the population is spread out with one ni |
ne eight under the age of one eight seven one from one eight to two four two seven nine from two five to four four two seven nine from four five to six four and one seven four who are six five years of age or older the median age is four three years for every one zero zero females there are nine nine two males for every one zero zero females age one eight and over there are nine six seven males the median income for a household in the town is two eight five two three and the median income for a family is four four zero six three males have a median income of two five two six three versus two two seven eight four for females the per capita income for the town is one seven nine nine nine eight zero of the population and three four of families are below the poverty line out of the total population five three of those under the age of one eight and five five of those six five and older are living below the poverty line external links town of lincoln new hampshire official website the flume gorge visitor center hi |
story of lincoln new hampshire lincoln public library white mountain art artists grafton county new hampshire towns in new hampshire lasers were used in the two zero zero five classical spectacular concert soon after the invention of the laser in one nine six zero it was described as a solution in search of a problem however since that time the laser has found a place as a useful tool in many scientific military medical and industrial applications scientific spectroscopy most types of laser are an inherently pure source of light they emit near monochromatic light with a very well defined range of wavelengths by careful design of the laser components it is possible to improve the purity of the laser light measured as the linewidth beyond that of any other light source this makes the laser a very useful source for spectroscopy the high intensity of light that can be achieved in a small well collimated beam can also be used to induce a nonlinear optical effect in a sample which makes techniques such as raman spe |
ctroscopy possible other spectroscopic techniques based on lasers can be used to make extremely sensitive detectors of various molecules able to measure molecular concentrations in the parts per trillion ppt level due to the high power densities achievable by lasers beam induced atomic emission is possible this technique is termed laser induced breakdown spectroscopy libs lasers may also be indirectly used in spectroscopy as a micro sampling system a technique termed laser ablation la which is typically applied to icp ms apparatus resulting in the powerful la icp ms lunar laser ranging when the apollo astronauts visited the moon they planted retroreflector arrays to make possible the lunar laser ranging experiment laser beams are focused through large telescopes on earth aimed toward the arrays and the time taken for the beam to be reflected back to earth measured to determine the distance between the earth and moon with high precision photochemistry some laser systems through the process of modelocking can p |
roduce extremely brief pulses of light as short as picoseconds or femtoseconds one zero one two one zero one five seconds such pulses can be used to initiate and analyse chemical reactions a technique known as photochemistry the short pulses can be used to probe the process of the reaction at a very high temporal resolution allowing the detection of short lived intermediate molecules this method is particularly useful in biochemistry where it is used to analyse details of protein folding and function laser cooling a technique that has had recent success is laser cooling this involves ion trapping a method where a number of ions are confined in a specially shaped arrangement of electric and magnetic fields by shining particular wavelengths of laser light at the ions it is possible to transfer momentum from the ions to the light photons causing the ions to lose energy and to slow down thus cooling the ions if this process is continued eventually all the ions in the trap are slowed and have the same energy level |
forming an unusual arrangement of matter known as a bose einstein condensate nuclear fusion the most extravagant use of lasers in science is in the field of fusion research some of the world s most powerful and complex arrangements of multiple lasers and optical amplifiers are used to produce extremely high intensity pulses of light of extremely short duration these pulses are arranged such that they impact pellets of tritium deuterium simultaneously from all directions hoping that the squeezing effect of the impacts will induce atomic fusion in the pellets this technique known as inertial confinement fusion so far has not been able to achieve breakeven that is less power is generated by the fusion reaction than is used to power the lasers but research continues as a finderscope for amateur telescopes with the advent of higher power green laser pointers came a new product line for observational astronomers the laser finder akin to the laser sighting device used in military rifles a green laser mounted to the |
tube of a telescope and properly collimated can reveal the precise location in the sky that the telescope is pointed in most outdoor night locales the green beam of the laser is visible to the eye by moving the telescope and the laser beam to the proper location in the sky observers can more easily locate the intended celestial target microscopy confocal laser scanning microscopy and two photon excitation microscopy make use of lasers to obtain blur free images of thick specimens at various depths military defensive applications recently some progress has been made in the use of the laser as a directed energy weapon mostly in defensive applications by using a chemical laser one in which the laser operation is powered by an energetic chemical reaction the requirement for generating and storing a large amount of electrical energy which directly or indirectly is used to power most high power lasers is removed this makes the laser system much more compact and easier to transport one example is a laser system whi |
ch is designed to destroy missiles in flight it is mounted in a converted commercial airliner and could be used for example to protect assets such as awacs aircraft or to destroy ballistic missiles see airborne laser however the practical problems of reliably generating and aiming the laser beam remain formidable the mobile tactical high energy laser mthel is another defensive laser system under development this is envisioned as a field deployable weapon system able to track incoming artillery projectiles and cruise missiles by radar and destroy them with a powerful deuterium fluoride laser for a discussion and list of laser based weapon systems see also directed energy weapon lasers strategic defense initiative another example of direct use of a laser as a defensive weapon was researched for the strategic defense initiative sdi nicknamed star wars and its successor programs this project would use ground based or space based laser systems to destroy incoming intercontinental ballistic missiles icbms again the |
practical problems of using and aiming these systems would be many particularly the problem of destroying icbms at the most opportune moment the boost phase just after launch this would involve directing a laser through a large distance in the atmosphere which due to optical scattering and refraction would bend and distort the laser beam complicating the aiming of the laser and reducing its efficiency another idea to come from the sdi project was the nuclear pumped x ray laser this was essentially an orbiting atomic bomb surrounded by laser media in the form of glass rods when the bomb exploded the rods would be bombarded with highly energetic gamma ray photons causing spontaneous and stimulated emission of x ray photons in the atoms making up the rods this would lead to optical amplification of the x ray photons producing an x ray laser beam which would be minimally affected by atmospheric distortion and capable of destroying icbms in flight the x ray laser would be a strictly one shot device destroying its |
elf on activation some initial tests of this concept were performed with underground nuclear testing however the results were not encouraging research into this approach to missile defense was discontinued after the cancellation of the sdi program in recent years the united states air force has begun experimenting with using lasers combined with high altitude airships as a potential means for a missile defense shield but also as a means to destroy enemy spacecraft or satellites in low earth orbit for more information see evolutionary air and space global laser engagement laser sight the laser has in most military applications been used as a tool to enhance the targeting of other weapon systems for example a laser sight is a small usually visible light laser placed on a handgun or rifle aligned to emit a beam parallel to the barrel since a laser beam typically has low divergence the laser light appears as a small spot even at long distances the user simply places the spot on the desired target and the barrel o |
f the gun is aligned recent studies two zero zero one have shown that laser sight has become an effective deterring tool for law enforcement criminals are more likely to surrender without resistance when they find a red laser dot on their chest most laser sights utilize a red six seven zero six three three nm diode with the six three three six three five nm diodes being an estimated one zero times as bright as their six seven zero nm counterparts some laser sights used an infrared diode which produced a dot invisible to the naked human eye but would show up when special optics were employed by the user in the late nine zero s green diodes five three two nm became available modern laser sights are so small that they can fit below the barrel as part of gun instead of a separate attachment some laser sights such as ones produced by lasermax are actually integrated into a unit that replaces the entire guide rod of a pistol thus adding no bulk to the weapon others like crimson trace lasergrips are built into the g |
rip so that activation is automatic as soon as the weapon is used another type of laser sight is the reflex or red dot sight this gives the illusion of a red dot being projected onto the target once the shooter looks through the sight but it is only visible to the user this has advantages where multiple weapons are aimed at the same target and it is also more visible than a conventional laser in bright sunny conditions illuminator saber two zero three laser illuminator u s air force this menacing but allegedly non lethal laser weapon shown in the accompanying photo attached to an m one six rifle was developed by the u s air force to temporarily impair an adversary s ability to fire a weapon or to otherwise threaten enemy forces the saber two zero three briefly illuminates an opponent with harmless low power laser light realizing he has been targeted the aggressor according to the air force hides or flees rather than risk death by aiming his weapon and attracting defensive fire rangefinder main article laser r |
ange finder a laser range finder is a device consisting of a pulsed laser and a light detector by measuring the time taken for light to reflect off a far object and knowing the speed of light the range to the object can be found a laser rangefinder is thus a simple form of lidar the distance to the target can then be used to aim a weapon such as a tank s main gun target designator another military use of lasers is as a laser target designator this is a low power laser pointer used to indicate a target for a precision guided munition typically launched from an aircraft the guided munition adjusts its flight path to home in to the laser light reflected by the target enabling a great precision in aiming the laser designator can be shone onto the target by an aircraft or nearby infantry lasers used for this purpose are usually infrared lasers to prevent easy detection of the guiding laser light by the enemy fictional military uses death ray the first role envisioned for the laser in military applications was as a |
death ray a hand held device that might replace the gun as a weapon for infantry or a vehicle mounted laser cannon able to destroy tanks ships and aircraft however practical considerations have severely constrained these ideas any laser capable of seriously wounding a human would with its requisite power supply be inevitably too heavy for a single soldier to lift and a high power laser capable of burning through tank armour would be extremely complex and very sensitive to misalignment from any knocks or vibration it might suffer making it unsuitable for field deployment there remains the possibility of using lasers to blind since this requires much lower power levels and is easily achievable in a man portable unit however most nations regard the deliberate blinding of the enemy as forbidden by the rules of war russia china and jordan possess such weapons which were banned in most western countries in one nine eight zero medical cosmetic surgery tattoo scar stretch mark sunspot wrinkle birthmark and hair remo |
val eye surgery lasik lasek prk laser scalpel gynecological urology laparoscopic dental procedures photobiomodulation imaging no touch removal of tumors especially of the brain and spinal cord industrial commercial cutting welding marking rangefinder surveying lidar pollution monitoring cd player dvd player laser printers digital minilabs barcode readers laser engraving of printing plates laser pointers holography laser light displays photolithography optical communications over optical fiber or in free space guidance systems e g ring laser gyroscopes optical tweezers writing subtitles onto motion picture films space elevator a possible solution transfer energy to the climbers by laser or microwave power beaming three d measurement laser scanning lasers a plot of the trajectory lorenz system for values r two eight one zero b eight three image lorenzattractor png the lorenz attractor introduced by edward lorenz in one nine six three is a non linear three dimensional deterministic dynamical system derived from |
the simplified equations of convection rolls arising in the dynamical equations of the atmosphere for a certain set of parameters the system exhibits chaotic behavior and displays what is today called a strange attractor this was proven by w tucker in two zero zero one the strange attractor in this case is a fractal of hausdorff dimension between two and three grassberger one nine eight three has estimated the hausdorff dimension to be two zero six zero zero one and the correlation dimension to be two zero five zero zero one the system arises in lasers dynamos and specific waterwheels frac a y x frac x b z y frac xy c z where a is called the prandtl number and b is called the rayleigh number a b c zero but usually a one zero b eight three and b is varied the system exhibits chaotic behavior for b two eight but displays knotted periodic orbits for other values of b for example with b nine nine nine six it becomes a t three two torus knot the butterfly like shape of the lorenz attractor may have inspired the na |
me of the butterfly effect in chaos theory see also list of chaotic maps takens theorem references jonas bergman knots in the lorentz system undergraduate thesis uppsala university two zero zero four external links lorenz attractor mathworld article lorenz equation on planetmath org levitated net computational art and design three d vrml lorenz attractor you need a vrml viewer plugin chaotic maps animation of a slow left arm delivery left arm orthodox spin is a style of bowling in the sport of cricket it is bowled by a left arm bowler using his fingers to spin the ball anticlockwise this action is the mirror image of that of an off spinner a right arm finger spinner and causes the ball to turn from right to left from the bowler s perspective or from the leg side to the off side of a right handed batsman it is usually considered to be harder for a right hander to play against than off spin because of the direction of turn but easier than leg spin since left arm spinners generally have a smaller repertoire of d |
elivery types and do not turn the ball as much left arm orthodox spin is one of the harder bowling styles to master because it requires long hours of practice to get the right line the flight dip sharp turn and drift in the air are potent weapons of a left arm spin bowler the major variations of a left arm spinner are the topspinner which turns less than expected the arm ball which doesn t turn at all and the left arm spinner s version of a doosra which turns the other way the chinaman spun with the wrist rather than the fingers like a leg break is also a rare variation especially potent when mixed up with the chinaman googly a great exponent of this was sir garfield sobers of the west indies greater attacking depth can be achieved with the help of variation of amount of spin examples of current left arm orthodox spinners are daniel vettori a member of the new zealand cricket team ashley giles a member of the england cricket team monty panesar a member of the england cricket team mohammad rafique a member of |
the bangladesh cricket team murali kartik a member of the indian cricket team sanath jayasuriya a member of the sri lanka cricket team ray price a member of the zimbabwe cricket team nicky boje a member of the south african cricket team enamul haque jr a member of the bangladesh cricket team yuvraj singh a member of the indian cricket team michael clarke a member of the australian cricket team historic left arm orthodox spinners include palwankar baloo india bishen bedi india phil edmonds england tony lock england maninder singh india wilfred rhodes england ravi shastri india sir garfield sobers west indies phil tufnell england derek underwood england johnny wardle england iqbal qasim pakistan inzamam ul haq pakistan aamir sohail pakistan cricket terminology bowling cricket a laser system generally consists of three important parts an energy source usually referred to as the pump or pump source a gain medium or laser medium a mirror or system of mirrors forming an optical resonator schematic diagram of a typi |
cal laser showing the three major parts the pump source is the part that provides energy to the laser system examples of pump sources include electrical discharges flashlamps arc lamps light from another laser chemical reactions and even explosive devices the type of pump source used principally depends on the gain medium and this also determines how the energy is transmitted to the medium a helium neon hene laser uses an electrical discharge in the helium neon gas mixture a nd yag laser uses a light focussed from a xenon flash lamp and excimer lasers use a chemical reaction the gain medium is the major determining factor of the wavelength of operation and other properties of the laser there are hundreds if not thousands of different gain media in which laser operation has been achieved the gain medium is excited by the pump source to produce a population inversion and it is in the gain medium that spontaneous and stimulated emission of photons takes place leading to the phenomenon of optical gain amplificati |
on examples of different gain media include liquids such as dye lasers these are usually organic chemical solvents such as methanol ethanol or ethylene glycol to which are added chemical dyes such as coumarin rhodamine and fluorescein the exact chemical configuration of the dye molecules determines the operation wavelength of the dye laser gases such as carbon dioxide argon krypton and mixtures such as helium neon these lasers are often pumped by electrical discharge solids such as crystals and glasses the solid host materials are usually doped with an impurity such as chromium neodymium erbium or titanium ions typical hosts include yag yttrium aluminium garnet ylf yttrium lithium fluoride sapphire aluminium oxide and various glasses examples of solid state laser media include nd yag ti sapphire cr sapphire usually known as ruby cr lisaf chromium doped lithium strontium aluminium fluoride er ylf nd glass and er glass solid state lasers are usually pumped by flashlamps or light from another laser semiconductor |
s a type of solid in which the movement of electrons between material with differing dopant levels can cause laser action semiconductor lasers are typically very small and can be pumped with a simple electric current enabling them to be used in consumer devices such as compact disc players see laser diode the optical resonator or optical cavity in its simplest form is two parallel mirrors placed around the gain medium which provide feedback of the light light from the medium produced by spontaneous emission is reflected by the mirrors back into the medium where it may be amplified by stimulated emission the light may reflect from the mirrors and thus pass through the gain medium many hundreds of times before exiting the cavity in more complex lasers configurations with four or more mirrors forming the cavity are used the design and alignment of the mirrors with respect to the medium is crucial to determining the exact operating wavelength and other attributes of the laser system the mirrors are given optical |
coatings which determine their reflective properties other optical devices such as spinning mirrors modulators filters and absorbers may be placed within the optical resonator to produce a variety of effects on the laser output such as altering the wavelength of operation or the production of pulses of laser light some lasers do not use an optical cavity but instead rely on very high optical gain to produce significant amplified spontaneous emission ase without requiring feedback of the light back into the gain medium such lasers are said to be superluminescent and emit light with low coherence but high bandwidth since they do not use optical feedback these devices are often not catergorized as lasers at all see also list of laser types references koechner walter one nine nine two solid state laser engineering three rd ed springer verlag isbn zero three eight seven five three seven five six two lasers and logic gate in mathematics logical conjunction usual symbol and is a logical operator that results in fals |
e if either of the operands is false definition in logic and technical fields that use it conjunction or and is a logical operator in logical calculi and a rule of inference in deductive systems the result of conjoining two propositions is also called their conjunction the conjunction is true if both of the combined propositions are true else it is false for two inputs a and b the truth table of the operator is as follows intuitively the logical operator works the same as the common english word and the sentence it s raining and i m inside asserts that two things are simultaneously true that it is raining outside and that i am inside logically this would be denoted by saying that a stands for it s raining b stands for i m inside together a and b for example consider x one three and x one three is true but x a b vdash a and b the argument form has two premises the first premise is the left conjunct the second premise the right conjunct from these two premises it can be logically concluded that a and b must be |
true as well here is an example of an argument that fits the form conjunction everyone should vote democracy is the best system of government therefore everyone should vote and democracy is the best system of government symbol the mathematical symbol for logical conjunction varies in the literature in addition to the abbreviation and one may also see a wedge or x two two two seven is typically used for conjunction for example a b is read as a and b such a conjunction is true if both a and b are true in all other cases it is false all the following are conjunctions a b a b a b c d e the equivalent notion in set theory is the set theoretic intersection associativity and commutativity one can also chain conjunctions such as a and b and c which is logically equivalent both to a and b and c and to a and b and c this statement is true if a b and c are simultaneously true in fancier language conjunction is associative it s also commutative a and b is the same as b and a bitwise operation logical conjunction is often |
used for bitwise operations examples zero and zero zero zero and one zero one and zero zero one and one one one one zero zero and one zero one zero one zero zero zero note that in computer science the and operator can be used to set a bit to zero by and ing the bit with zero a and zero zero for any binary value of a this principle is called a bit mask for example if you have a four byte integer holding a color value which could be described as zero xaabbggrr r red g green b blue a alpha you may want to select one of the colors the bit mask for green would be zero x zero zero zero zero ff zero zero if you apply this bit mask to the four byte integer it only leaves the bits belonging to green intact zero x zero zero zero zero gg zero zero intersection the intersection used in set theory is defined in terms of a logical conjunction x a b if and only if x a x b because of this logical conjunction satisfies many of the same identities as set theoretic intersection such as associativity commutativity distributivit |
y and de morgan s laws and and wedge at least on the face of it english and has properties not captured by logical conjunction unlike wedge and is not commutative they got married and had a baby is not equivalent to they had a baby and got married some lists conjoined by and do not allow an operation analogous to logical wedge elimination the american flag is red white and blue does not permit us to infer that the american flag is white but a minor issue of logic and language is the role of the word but logically the sentence it s raining but the sun is shining is equivalent to it s raining and the sun is shining so logically but is equivalent to and however in natural language but and and are semantically distinct the former sentence suggests that the latter sentence is usually a contradiction one way to resolve this problem of correspondence between symbolic logic and natural language is to observe that the first sentence using but implies the existence of a hidden but mistaken assumption namely that the su |
n does not shine when it rains we might say that given probability p that it rains and the sun shines and probability one p that it rains and the sun does not shine or that it does not rain at all we would say but in place of and when p was low enough to warrant our incredulity that implication captures the semantic difference of and and but without disturbing their logical equivalence on the other hand in brazilian logic the logical equivalence is broken between a but not b where but not is a single operator and a and not b which is a weaker statement but is also sometimes disjunctive it never rains but it pours sometimes minutive she was but a girl at the time sometimes contrastive it s not black but blue sometimes a spatial preposition he s waiting but the house and sometimes interjective my but that s a lovely boat these uses await semantic assimilation with conjunctive but like and but is sometimes non commutative he got here but he got here late is not equivalent to he got here late but he got here this |
example shows also that unlike and but can be felicitously used to conjoin sentences that entail each other compare he got here late and he got here see also boolean algebra or nand nor xor xnor external links wolfram mathematics conjunction logic binary operations in formal logic logical connectives also known as logical connectors and sometimes logical constants serve to connect statements into more complicated compound statements in algebraic logic the more refined term logical operator is preferred for example considering the assertions it s raining and i m inside we can form the compound assertions it s raining and i m inside or it s not raining or if it s raining then i m inside a new statement or proposition combining two statements is called a compound statement or compound proposition the basic operators are not or and land or or conditional or and biconditional iff not is a unary operator it takes a single term p the rest are binary operators taking two terms to make a compound statement p q p q p |
q p q note the similarity between the symbols for and land and set theoretic intersection likewise for or and set theoretic union this is not a coincidence the definition of the intersection uses and and the definition of union uses or truth tables for these connectives in order to reduce the number of necessary parentheses one introduces precedence rules has higher precedence than higher than and higher than so for example p q r s is short for p q r s not all of these operators are necessary for a full blooded logical calculus certain compound statements are logically equivalent for example p q is logically equivalent to p q so the conditional operator is not necessary if you have not and or for the sake of convenience and brevity only the five most commonly used operators in math are listed above one can also consider other connectives such as nand not and xor not biconditional and nor not or logical operators are implemented as logic gates in digital circuits practically all digital circuits the major exce |
ption is dram are built up from nand nor not and transmission gates nand and nor gates with three or more inputs rather than the usual two inputs are fairly common although they are logically equivalent to a cascade of two input gates all other operators are implemented by breaking them down into a logically equivalent combination of two or more of the above logic gates if you throw away all the operators that are not necessary what operators are you left with which conditionals are the crucial must have ones surprisingly there is more than one answer to that question all connectives can be expressed with nand alone all connectives can be expressed with nor alone as demonstrated by the apollo guidance computer since nand can be built from not and and and we know that all connectives can be built from nand alone clearly all connectives can be built from combinations of not and and and several other answers the logical equivalence of nand alone nor alone and not and and is similar to turing equivalence is some |
new technology such as reversible computing clockless logic quantum dots computing or tinker toys logically complete in that it can be used to build computers that can do all the sorts of computation that cmos based computers can do if it can implement the nand operator only then is it logically complete references article on logical constants at the stanford encyclopedia of philosophy see also laws of logic truth values boolean domain boolean function boolean valued function bitwise operations boolean algebra topics conjunction and disjunction or distinction neq xor equivalence eq xnor negation not not both nand both not nor boolean algebra in mathematical logic the propositional calculus or sentential calculus is a formal deduction system whose atomic formulae are propositional variables compare this to the predicate calculus which is quantificational and whose atomic formulae are propositional functions and modal logic which may be non truth functional a calculus is a logical system which is used to prove |
valid formulae i e its theorems and arguments it is a set of axioms which may be an empty or countably infinite set or axiom schemata and inference rules for deriving valid inferences a formal grammar or syntax recursively defines the expressions and well formed formulae wffs of the language in addition a semantics is given which defines truth and valuations or interpretations it allows us to determine which wffs are valid i e theorems in the propositional calculus the language consists of propositional variables or placeholders and sentential operators or connectives a wff is any atomic formula or a formula built up from sentential operators in what follows we will outline a standard propositional calculus many different formulations exist which are all more or less equivalent but differ in one their language i e which operators and variables are part of the language two which if any axioms they have three which inference rules are employed grammar the language consists of the capital letters of the alphabet |
standing as propositional variables these are atomic formulae conventionally either the latin alphabet a b c or the greek alphabet is used but the two are not mixed symbols denoting the following connectives or logical operators we may do with fewer operators and thus symbols by having some abbreviate others e g p q is equivalent to p q many authors prefer the tilde to represent the logical not the ampersand or equivalently which has an empty axiom set derivations using our calculus will be laid out in the form of a list of numbered lines with a single wff and a justification on each line any premises will be at the top with a p for their justification the conclusion will be on the last line a derivation will be considered complete if every line follows from previous ones by correct application of a rule for a contrasting approach see proof trees axioms our axiom set is the empty set inference rules our propositional calculus has ten inference rules these rules allow us to derive other true formulae given a |
set of formulae that are assumed to be true the first eight simply state that we can infer certain wffs from other wffs the last two rules however use hypothetical reasoning in the sense that in the premise of the rule we temporarily assume an unproven hypothesis to be part of the set of inferred formulae to see if we can infer a certain other formula since the first eight rules don t do this they are usually described as non hypothetical rules and the last two as hypothetical rules double negative elimination from the wff we may infer conjunction introduction from any wff and any wff we may infer conjunction elimination from any wff we may infer and disjunction introduction from any wff we may infer and where is any wff disjunction elimination from the wff s of the form and we may infer biconditional introduction from the wff s of the form and we may infer biconditional elimination from the wff we may infer and modus ponens from the wff s of the form and we may infer conditional proof if can be derived while |
assuming the hypothesis we may infer reductio ad absurdum if we can derive both and while assuming the hypothesis we may infer example of a proof the following is an example of a syntactical demonstration prove a rightarrow a proof interpret a vdash a as assuming a infer a read vdash a rightarrow a as assuming nothing infer that a implies a or it is a tautology that a implies a or it is always true that a implies a soundness and completeness of the rules the crucial properties of this set of rules are that they are sound and complete informally this means that the rules are correct and that no other rules are required these claims can be made more formal as follows we define a truth assignment as a function that maps propositional variables to true or false informally such a truth assignment can be understood as the description of a possible state of affairs or possible world where certain statements are true and others are not the semantics of formulae can then be formalized by defining for which state of a |
ffairs they are considered to be true which is what is done by the following definition we define when such a truth assignment a satisfies a certain wff with the following rules a satisfies the propositional variable p iff a p true a satisfies iff a does not satisfy a satisfies iff a satisfies both and a satisfies iff a satisfies at least one of either or a satisfies iff it is not the case that a satisfies but not a satisfies iff a satisfies both and or satisfies neither one of them with this definition we can now formalize what it means for a formula to be implied by a certain set s of formulae informally this is true if in all worlds that are possible given the set of formulae s the formula also holds this leads to the following formal definition we say that a set s of wffs semantically entails or implies a certain wff if all truth assignments that satisfy all the formulae in s also satisfy finally we define syntactical entailment such that is syntactically entailed by s iff we can derive it with the infere |
nce rules that were presented above in a finite number of steps this allows us to formulate exactly what it means for the set of inference rules to be sound and complete soundness if the set of wffs s syntactically entails wff then s semantically entails completeness if the set of wffs s semantically entails wff then s syntactically entails for the above set of rules this is indeed the case sketch of a soundness proof for most logical systems this is the comparatively simple direction of proof notational conventions let g be a variable ranging over sets of sentences let a b and c range over sentences for g syntactically entails a we write g proves a for g semantically entails a we write g implies a we want to show a g if g proves a then g implies a we note that g proves a has an inductive definition and that gives us the immediate resources for demonstrating claims of the form if g proves a then so our proof proceeds by induction i basis show if a is a member of g then g implies a ii basis show if a is an axi |
om then g implies a iii inductive step a assume for arbitrary g and a that if g proves a then g implies a if necessary assume this for arbitrary b c etc as well b for each possible application of a rule of inference to a leading to a new sentence b show that g implies b n b basis step ii can be omitted for the above calculus which is a natural deduction system and so has no axioms basically it involves showing that each of the axioms is a semantic logical truth the basis step s demonstrate s that the simplest provable sentences from g are also implied by g for any g the is simple since the semantic fact that a set implies any of its members is also trivial the inductive step will systematically cover all the further sentences that might be provable by considering each case where we might reach a logical conclusion using an inference rule and shows that if a new sentence is provable it is also logically implied for example we might have a rule telling us that from a we can derive a or b in iii a we assume that |
if a is provable it is implied we also know that if a is provable then a or b is provable we have to show that then a or b too is implied we do so by appeal to the semantic definition and the assumption we just made a is provable from g we assume so it is also implied by g so any semantic valuation making all of g true makes a true but any valuation making a true makes a or b true by the defined semantics for or so any valuation which makes all of g true makes a or b true so a or b is implied generally the inductive step will consist of a lengthy but simple case by case analysis of all the rules of inference showing that each preserves semantic implication by the definition of provability there are no sentences provable other than by being a member of g an axiom or following by a rule so if all of those are semantically implied the deduction calculus is sound sketch of completeness proof this is usually the much harder direction of proof we adopt the same notational conventions as above we want to show if g |
implies a then g proves a we proceed by contraposition we show instead that if g does not prove a then g does not imply a i g does not prove a assumption ii if g does not prove a then we can construct an infinite maximal set g which is a superset of g and which also does not prove a a place an ordering on all the sentences in the language e g alphabetical ordering and number them e one e two b define a series gn of sets g zero g one inductively as follows i g zero g ii if proves a then g k one gk iii if does not prove a then g k one c define g as the union of all the gn that is g is the set of all the sentences that are in any gn d it can be easily shown that i g contains is a superset of g by b i ii g does not prove a because if it proves a then some sentence was added to some gn which caused it to prove a but this was ruled out by definition and iii g is a maximal set with respect to a if any more sentences whatever were added to g it would prove a because if it were possible to add any more sentences they |
should have been added when they were encountered during the construction of the gn again by definition iii if g is a maximal set wrt a then it is truth like this means that it contains the sentence a only if it does not contain the sentence not a if it contains a and contains if a then b then it also contains b and so forth iv if g is truth like there is a g canonical valuation of the language one that makes every sentence in g true and everything outside g false while still obeying the laws of semantic composition in the language v a g canonical valuation will make our original set g all true and make a false vi if there is a valuation on which g are true and a is false then g does not semantically imply a q e d alternative calculus it is possible to define another version of propositional calculus which defines most of the syntax of the logical operators by means of axioms and which uses only one inference rule axioms let and stand for well formed formulae the wff s themselves would not contain any greek l |
etters but only capital roman letters connective operators and parentheses then the axioms are then one then two and one and two and three or one or two or three not one not two not three axiom then two may be considered to be a distributive property of implication with respect to implication axioms and one and and two correspond to conjunction elimination the relation between and one and and two reflects the commutativity of the conjunction operator axiom and three corresponds to conjunction introduction axioms or one and or two correspond to disjunction introduction the relation between or one and or two reflects the commutativity of the disjunction operator axiom not one corresponds to reductio ad absurdum axiom not two says that anything can be deduced from a contradiction axiom not three is called tertium non datur latin a third is not given and reflects the semantic valuation of propositional formulae a formula can have a truth value of either true or false there is no third truth value at least not in |
classical logic intuitionistic logicians do not accept the axiom not three inference rule the inference rule is modus ponens phi phi rightarrow chi vdash chi if the double arrow equivalence operator is also used then the following natural inference rules may be added iff one phi leftrightarrow chi vdash chi rightarrow phi iff two phi rightarrow chi chi rightarrow phi vdash phi leftrightarrow chi meta inference rule let a demonstration be represented by a sequence with hypotheses to the left of the turnstile and the conclusion to the right of the turnstile then the deduction theorem can be stated as follows if the sequence phi one phi two phi n chi vdash psi has been demonstrated then it is also possible to demonstrate the sequence phi one phi two phi n vdash chi rightarrow psi this deduction theorem dt is not itself formulated with propositional calculus it is not a theorem of propositional calculus but a theorem about propositional calculus in this sense it is a meta theorem comparable to theorems about the |
soundness or completeness of propositional calculus on the other hand dt is so useful for simplifying the syntactical proof process that it can be considered and used as another inference rule accompanying modus ponens in this sense dt corresponds to the natural conditional proof inference rule which is part of the first version of propositional calculus introduced in this article the converse of dt is also valid if the sequence phi one phi two phi n vdash chi rightarrow psi has been demonstrated then it is also possible to demonstrate the sequence phi one phi two phi n chi vdash psi in fact the validity of the converse of dt is almost trivial compared to that of dt if phi one phi n vdash chi rightarrow psi then one phi one phi n chi vdash chi rightarrow psi two phi one phi n chi vdash chi and from one and two can be deduced three phi one phi n chi vdash psi by means of modus ponens q e d the converse of dt has powerful implications it can be used to convert an axiom into an inference rule for example the axi |
om and one vdash phi wedge chi rightarrow phi can be transformed by means of the converse of the deduction theorem into the inference rule phi wedge chi vdash phi which is conjunction elimination one of the ten inference rules used in the first version in this article of the propositional calculus example of a proof the following is an example of a syntactical demonstration involving only axioms then one and then two prove a a reflexivity of implication proof one a a a a a a a a a axiom then two with a a a a two a a a a axiom then one with a a a three a a a a a from one and two by modus ponens four a a a axiom then one with a a five a a from three and four by modus ponens other logical calculi propositional calculus is about the simplest kind of logical calculus in any current use aristotelian syllogistic calculus which is largely supplanted in modern logic is in some ways simpler but in other ways more complex than propositional calculus it can be extended in several ways the most immediate way to develop a |
more complex logical calculus is to introduce rules that are sensitive to more fine grained details of the sentences being used when the atomic sentences of propositional logic are broken up into terms variables predicates and quantifiers they yield first order logic or first order predicate logic which keeps all the rules of propositional logic and adds some new ones for example from all dogs are mammals we may infer if rover is a dog then rover is a mammal with the tools of first order logic it is possible to formulate a number of theories either with explicit axioms or by rules of inference that can themselves be treated as logical calculi arithmetic is the best known of these others include set theory and mereology modal logic also offers a variety of inferences that cannot be captured in propositional calculus for example from necessarily p we may infer that p from p we may infer it is possible that p many valued logics are those allowing sentences to have values other than true and false for example nei |
ther and both are standard extra values continuum logic allows each sentence to have any of an infinite number of degrees of truth between true and false these logics often require calculational devices quite distinct from propositional calculus see also list of boolean algebra topics g del escher bach boolean logic frege s propositional calculus external links article on propositional logic at the internet encyclopedia of philosophy introduction to mathematical logic elements of propositional calculus mathematical logic in computer programming lazy evaluation is a technique that attempts to delay computation of expressions until the results of the computation are known to be needed it has two related yet different meanings that could be described as delayed evaluation and minimal evaluation the benefits of lazy evaluation include performance increases due to avoiding unnecessary calculations the ability to construct infinite data structures and the ability to define control structures as regular functions ra |
ther than built in primitives languages that use lazy evaluation can be further subdivided into those that use a call by name evaluation strategy and those that use a call by need evaluation strategy most realistic lazy languages such as haskell use call by need for performance reasons but theoretical presentations of lazy evaluation often use call by name for simplicity the opposite of lazy evaluation is eager evaluation also known as strict evaluation eager evaluation is the evaluation behavior used in most programming languages delayed evaluation delayed evaluation is used particularly in functional languages when using delayed evaluation an expression is not evaluated as soon as it gets bound to a variable but when the evaluator is forced to produce the expression s value some programming languages delay evaluation of expressions by default and some others provide functions or special syntax to delay evaluation in miranda and haskell evaluation of function arguments is delayed by default in many other lan |
guages evaluation can be delayed by explicitly suspending the computation using special syntax as with scheme s delay and force or more generally by wrapping the expression in a thunk delayed evaluation has the advantage of being able to create calculable infinite lists without infinite loops or size matters interfering in computation for example one could create a function that creates an infinite list often called a stream of fibonacci numbers the calculation of the n th fibonacci number would be merely the extraction of that element from the infinite list forcing the evaluation of the first n members of the list only for example in the haskell programming language the list of all fibonacci numbers can be written as fibs one one zipwith fibs tail fibs in haskell syntax prepends an element to a list tail returns a list without its first element and zipwith uses a specified function in this case addition to combine corresponding elements of two lists to produce a third provided the programmer is careful only |
the values that are required to produce a particular result are evaluated however certain calculations may result in the program attempting to evaluate an infinite number of elements for example requesting the length of the list or trying to sum the elements of the list with a fold operation would result in the program either failing to terminate or running out of memory see also minimal evaluation non strict programming language functional programming lambda calculus combinatory logic currying graph reduction corn programming language compare lazy initialization lookahead external links functional programming in python becomes lazy references steve summit s c faqs programming paradigms programming evaluation lemuridae is one of the four families of lemurs and are part of a class of primates known as prosimians these animals are the evolutionary predecessors of monkeys and apes simians genus lemur has only one member lemur catta or the ring tailed lemur it is easily recognized by its black and white striped t |
ail and is found in many zoos lemurs get their name from the ancient roman belief that they were ghosts or spirits they were mistaken for specters spirits because many species are nocturnal classification order primates suborder strepsirrhini non tarsier prosimians family cheirogaleidae dwarf and mouse lemurs family lemuridae genus lemur ring tailed lemur lemur catta genus eulemur brown lemurs black lemur eulemur macaco brown lemur eulemur fulvus sanford s lemur eulemur sanfordi white headed lemur eulemur albifrons red fronted lemur eulemur rufus red collared lemur eulemur collaris white collared lemur eulemur albocollaris mongoose lemur eulemur mongoz crowned lemur eulemur coronatus red bellied lemur eulemur rubriventer gray headed lemur eulemur cinereiceps genus hapalemur lesser gentle or bamboo lemurs gray bamboo lemur hapalemur griseus sambriano bamboo lemur hapalemur occidentalis bandro hapalemur alaotrensis golden bamboo lemur hapalemur aureus genus prolemur greater bamboo lemur prolemur simus genus var |
ecia ruffed lemurs black and white ruffed lemur varecia variegata red ruffed lemur varecia rubra family lepilemuridae sportive lemurs family indridae woolly lemurs and allies family daubentoniidae aye aye family lorisidae lorises pottos and allies family galagidae galagos suborder haplorrhini tarsiers monkeys and apes prosimians on september three zero one nine nine six at these customers had previously shown reluctance at purchasing from a direct competitor bell labs brought prestige to the new company as well as the revenue from thousands of patents richard mcginn succeeded henry schacht as ceo in one nine nine seven lucent became a darling stock of the investment community in the late one nine nine zero s rising from a split adjusted spin off price of seven five six share to a high of eight four however on january six two zero zero zero lucent announced the first of a string of announcements that it had missed its quarterly estimates and when it was later revealed that it had used dubious accounting and sa |
les practices to generate some of its earlier quarterly numbers lucent fell from grace by october two zero zero two when its stock price bottomed at five five cents per share henry schacht had been brought back to replace rich mcginn in one nine nine eight lucent sold its consumer telephone equipment business to vtech who renamed the division advanced american telephones in one nine nine nine lucent acquired ascend communications an alameda ca based manufacturer of communications equipment for two four b usd in october two zero zero zero lucent spun off its business telecommunications arm into avaya inc and in june two zero zero two it spun off its microelectronics division into agere systems in two zero zero two lucent began making significant cuts to the health care and retirement benefits of many of its one two five zero zero zero retirees although lucent contends these and future cuts are necessary for its survival they have nevertheless generated a continuing flow of negative publicity in the news media |
today lucent has three zero five zero zero employees down from about one six five zero zero zero employees at its zenith lucent is active in the areas of telephone switching optical data and wireless networking patricia russo currently heads the company business groups lucent is divided into three core groups all three of which mainly serve business and corporate customers network solutions group serves landline cellular telephone service providers by providing equipment one zero zero best companies for working mothers in two zero zero four by working mother magazine murray hill facility the murray hill anechoic chamber built in one nine four zero is the world s oldest wedge based anechoic chamber the interior room measures approximately three zero feet high by two eight feet wide by three two feet deep the exterior cement and brick walls are about three feet thick to keep outside noise from entering the chamber the chamber absorbs over nine nine nine nine five of the incident acoustic energy above two zero z |
ero hz at one time the murray hill chamber was cited in the guinness book of world records as the world s quietest room it is possible to hear the sounds of bone joints and heart beats very prominently the murray hill facility is currently the global headquarters for lucent technologies the murray hill facility also has the largest copper roof in the world when lucent technologies was experiencing financial troubles in two zero zero zero and two zero zero one one out of every three fluorescent lights was turned off in the facility the same was done in the naperville facilities for a while the facility has a cricket field and nearby features a station from which enthusiasts can control rc airplanes and helicopters fcpa case according to its sec filing in april two zero zero four lucent fired its president coo a marketing executive and a finance manager at its china operations for fcpa violations these violations were uncovered through internal investigations triggered by the unrelated us doj and sec probe into |
possible lucent s fcpa violations in saudi arabia logo the lucent logo was designed by landor associates a prominent san francisco based branding consultancy one source inside lucent says that the logo is actually a zen buddhist symbol for eternal truth the enso turned nine zero degrees and modified in the dilbert comic strip when dogbert was asked to design a new company logo he takes a piece of paper that his coffee cup was sitting on and calls it the brown ring of quality this may have been a parody of the lucent logo external links lucent website bell system companies based in new jersey companies listed on the new york stock exchange networking companies telecommunications equipment vendors the lupercalia was an annual roman festival held on february one five to honour faunus god of fertility and forests justin martyr identified faunus as lupercus the one who wards off the wolf but his identification is not supported by any earlier classical sources in fact a she wolf is a protective totem of rome since |
one was the mythological foster mother of the eternal city s founding twins romulus and remus the festival was celebrated near the cave of lupercal on the palatine one of the seven roman hills to expiate and purify new life in the spring this festival s origins are older than the founding of rome the religious ceremonies were directed by the luperci the brothers of the wolf lupus priests of faunus dressed only in a goatskin during lupercalia a dog and two male goats were sacrificed two patrician youths were anointed with their blood which was wiped off with wool soaked in milk after which they were expected to smile and laugh the luperci afterwards dressed themselves in the skins of the sacrificed goats in imitation of lupercus and ran round the palatine hill with thongs cut from the skins in their hands these were called februa girls and young women would line up on their route to receive lashes from these whips this was supposed to ensure fertility and ease the pains of childbirth this tradition itself may |
survive christened and shifted to spring in certain easter monday ritual whippings the feast of st valentine was first declared to be on february one four by pope gelasius i in four nine six there is a widespread theory that he created the day to counter the practice held on lupercalia of young men and women pairing off as lovers by drawing their names out of an urn but this practice is not attested in any sources from that era the name of the month of february is derived from the latin februare to purify meant as one of the effects of fever which has the same linguistic root the william shakespeare play julius caesar begins during lupercalia see also roman festivals roman mythology st valentine s day references and external links faunus in pantheon org william smith dictionary of greek and roman antiquities one eight seven five lupercalia pauly wissowa legendary lupercalia lottery ancient roman festivals the people in this list have been included because they are were atheists that is they do not or did not |
believe in god or gods and this disbelief can be asserted because they themselves have expressed it openly on the record or in their works personal correspondence diaries etc presumed atheists are not included here given the different possible qualifications of the word atheist and its varied uses through time some people listed here would be called agnostics or anti religionists rather than simply atheists but the list attempts to be inclusive on this matter the reader should consult the relevant biographical articles for details the list has two sections the first one is for atheists who are or were notable defenders of the cause of atheism or who advocated views of the human condition society economy etc that were compatible with atheism in short these people are or were important for other atheists since they contribute d to the popularization understanding and acceptance of atheism in society either through their works or through their deeds the other section is for famous people who just happen happene |
d to be atheists and whose unbelief is was relevant in their life but who do not did not actively fight for its cause there might not be a consensus on whether a given person belongs in the second section since obviously there is no way of listing all famous people who just happen to be atheists there is no point either many of these profess their atheism as just a peripheral issue in their lives or simply keep quiet about it and they will not be listed here influential or outspoken atheists by primary occupation activists ellen johnson current president of american atheists emma goldman one eight six nine one nine four zero lithuanian born radical known for her writings and speeches defending anarcho communism feminism and atheism madalyn murray o hair one nine one nine one nine nine five american militant atheist founder of american atheists campaigner for the separation of church and state filed the lawsuit that led the us supreme court to ban teacher led prayer and bible reading in public schools michael |
newdow american citizen dr and attorney who sued his daughter s school claiming the words under god in the u s pledge of allegiance constitute a breach in church state separation e v ramasami naicker one eight seven nine one nine seven three commonly known as periyar was an indian rationalist freedom fighter and activist against the caste system vinayak damodar savarkar one eight eight three one nine six six indian revolutionary freedom fighter and hindu nationalist leader ali sina founder of faithfreedom international a movement that denounces islam barbara smoker one nine two three british humanist activist and freethought advocate wrote the book freethoughts atheism secularism humanism selected egotistically from the freethinker entertainment phillip adams one nine three nine australian broadcaster writer film maker left wing radical thinker iconoclast australian humanist of the year one nine eight seven woody allen one nine three five american filmmaker actor and writer ingmar bergman one nine one eight s |
wedish film director and playwright george carlin one nine three seven american comedian actor and author wrote a number of monologues about the non existence of god adam carolla one nine six four american tv personality co host of the man show kathleen hanna one nine six nine front woman of the nine zero s band bikini kill and currently le tigre theo van gogh one nine five seven two zero zero four dutch filmmaker critic of christianity and islam victim of islamic fundamentalism tom leykis one nine five six radio talk show host penn and teller american magicians and hosts of bullshit teller born one nine four eight as raymond joseph teller and penn fraser jillette one nine five five julia sweeney one nine six one american actor and comedian alumna of saturday night live author performer of one woman autobiographical stage show about finding atheism letting go of god literature h l mencken one eight eight zero one nine five six american editor journalist and social critic jean meslier one six seven eight one s |
even three three author and french erstwhile priest camille paglia one nine four seven american post feminist literary and cultural critic philip pullman one nine four six cbe british author of his dark materials fantasy trilogy for young adults ayn rand one nine zero five one nine eight two american novelist and philosopher founder of objectivism her philosophy and her fiction emphasize her notions of individualism egoism rational self interest and capitalism percy bysshe shelley one seven nine two one eight two two british romantic poet contemporary and associate of john keats and lord byron author of the necessity of atheism warren allen smith author of who s who in hell philosophy jeremy bentham one seven four eight one eight three two british jurist eccentric philosopher and social reformer founder of utilitarianism he had john stuart mill as his disciple albert camus one nine one three one nine six zero french philosopher and novelist a luminary of existentialism auguste comte one seven nine eight one e |
ight five seven french philosopher considered the father of sociology andr comte sponville one nine five two french materialist philosopher paul henry thiry baron d holbach one seven two three one seven eight nine french homme de lettres philosopher and encyclopedist member of the philosophical movement of french materialism attacked christianity and religion as counter to the moral advancement of humanity marquis de condorcet one seven four three one seven nine four french philosopher and mathematician of the enlightenment marquis de sade donatien alphonse fran ois de sade one seven four zero one eight one four french aristocrat writer of philosophy laden pornography and pure philosophy who denied the existence of morality based on a mandate from divine authority daniel dennett one nine four two american philosopher leading figure in evolutionary biology and cognitive science well known for his book darwin s dangerous idea denis diderot one seven one three one seven eight four french philosopher author edito |
r of the first encyclopedia known for the quote man will never be free until the last king is strangled with the entrails of the last priest ludwig andreas feuerbach one eight zero four one eight seven two german philosopher postulated that god is merely a projection by humans of their own best qualities paul kurtz one nine two six american philosopher skeptic founder of committee for the scientific investigation of claims of the paranormal csicop and the council for secular humanism karl marx one eight one eight one eight eight three german philosopher sociologist political economist journalist and revolutionary founder of marxism his famous formulation was religion is the sigh of the oppressed creature the sentiment of a heartless world and the soul of soulless conditions it is the opium of the people james mill one seven seven three one eight three six british historian and philosopher father of john stuart mill he supported the utilitarian principles of jeremy bentham friedrich nietzsche one eight four fo |
ur one nine zero zero german existentialist philosopher who wrote beyond good and evil which refuted the traditional notions of morality nietzsche is forever associated with the phrase god is dead from his book also sprach zarathustra sir karl popper one nine zero two one nine nine four austrian born british philosopher of science who claimed that empirical falsifiability should be the criterion for distinguishing scientific theory from non science richard rorty one nine three one american philosopher whose ideas combine pragmatism with a wittgensteinian ontology that declares that meaning is a social linguistic product of dialogue he actually rejects the theist atheist dichotomy and prefers to call himself anti clerical m n roy one eight eight seven one nine five four indian political thinker founder his radical humanism school of philosophy bertrand russell three rd earl russell om one eight seven two one nine seven zero british mathematician philosopher logician political liberal activist popularizer of ph |
ilosophy and one nine five zero nobel laureate in literature on the issue of atheism agnosticism he wrote the essay why i am not a christian jean paul sartre one nine zero five one nine eight zero french existentialist philosopher dramatist novelist and critic henry sidgwick one eight three eight one nine zero zero british philosopher follower of utilitarianism peter singer one nine four six australian philosopher and teacher working on practical ethics from a utilitarian perspective controversial for his opinions on abortion and euthanasia politics outspoken atheist and popularizer of science joseph fletcher one nine zero five one nine nine one founder of the theory of situational ethics pioneer in the field of bioethics transhumanist sigmund freud one eight five six one nine three nine austrian neurologist father of psychoanalysis considered the belief in god to stem from an unconscious fear of one s own biological father jonathan miller one nine three four british doctor theatre director journalist and bro |
adcaster recently made a programme atheism a rough history of disbelief discussing the history of atheism julien offray de la mettrie one seven zero nine one seven five one french physician and philosopher earliest of the materialist writers of the enlightenment steven pinker one nine five four influential american experimental psychologist cognitive scientist and popular science writer professor of psychology harvard university carl sagan one nine three four one nine nine six american astronomer author science popularizer and proponent of the search for extraterrestrial life burrhus frederic skinner one nine zero four one nine nine zero american psychologist and author a pioneer on experimental psychology advocate of behaviorism and writer of two books on social engineering max stirner one eight zero six one eight five six german philosopher young hegelian one of the literary grandfathers of nihilism existentialism and anarchism matt ridley one nine five eight british zoologist science writer and journalist |
open supporter of libertarianism in politics and reductionism in biology james d watson one nine two nine nobel prize laureate co discoverer of the structure of dna classical anaxagoras five zero zero four two eight bce greek philosopher freethinker regarded the conventional gods as mythic abstractions endowed with anthropomorphic attributes brihaspati traditionally taken to be the founder of the lokayata philosophical school in india along with carvaka carvaka materialist philosopher in ancient india democritus four six zero three five seven bce greek philosopher father of materialism viewed everything as matter composed of indestructible particles atoms diagoras called diagoras the atheist of melos five th cent bce greek poet and sophist epicurus three four one two seven zero bce greek materialist philosopher lucretius nine six five five bce roman philosopher and poet epicurean atomist wrote on the nature of things protagoras four eight one four one one bce greek philosopher lucius annaeus seneca the younge |
r bce four six five ce roman stoic philosopher writer and politician other known atheists by primary occupation activism godmen and paranormal claims margaret sanger one eight eight three one nine six six american birth control activist founder of planned parenthood elizabeth cady stanton one eight one five one nine zero two american suffragist voltairine de cleyre one eight six six one nine one two american feminist and activist leon trotsky one eight seven nine one nine four zero russian revolutionary and soviet statesman mao zedong one eight nine three one nine seven six chinese revolutionary and statesman former chairman of the communist party of china and leader of the people s republic of china creator of the variant of marxist leninist theory called maoism entertainment jello biafra one nine five eight punk rock musician and political activist greg graffin singer of bad religion luis bu uel one nine zero zero one nine eight three spanish born mexican filmmaker and important activist of the surrealist m |
ovement famous for his one liner thank god i m still an atheist asia carrera one nine seven three pornographic actress sir charles spencer chaplin one eight eight nine one nine seven seven british actor director and producer david cross one nine six four actor and stand up comedian ricky gervais one nine six one actor and co writer of the original version of the office kamal haasan one nine five four indian actor self professed rationalist atheist activist and a follower of periyar katharine hepburn one nine zero seven two zero zero three actress possibly agnostic gary numan one nine five eight british new wave and industrial musician whose albums sacrifice one nine nine four exile one nine nine seven and pure two zero zero zero stridently debunked religious beliefs basava premanand one nine three zero amateur magician eminent skeptic and rationalist from tamil nadu india james randi one nine two eight american professional magician and debunker of psychics and other kinds of pseudoscience has also denounced |
blasphemy laws nikolai rimsky korsakov one eight four four one nine zero eight russian nationalist composer member of the five best known for the tone poem scheherazade gene roddenberry one nine two one one nine nine one american television producer and creator of star trek doug stanhope one nine six nine stand up comedian joss whedon one nine six four american television and film producer writer director perhaps best known for creating the buffyverse literature and art tariq ali one nine four three british author filmmaker historian one of the founders of the new left and spokesman for anti imperialism isaac asimov one nine two zero one nine nine two russian born american writer of fiction and nonfiction works scientist and science popularizer iain banks one nine five four scottish writer and left wing activist dave barry one nine four seven best selling american author george gordon byron six th baron byron one seven eight eight one eight two four british romantic poet sir arthur c clarke one nine one seven |
british scientist and science fiction author joseph conrad one eight five seven one nine two four polish born english author harry harrison one nine two five american science fiction author anthologist and artist whose short story the streets of ashkelon took as its hero an atheist who tries to prevent a christian missionary from contaminating a tribe of irreligious but ingenuous alien beings ernest hemingway one eight nine nine one nine six one american novelist who wrote in a farewell to arms all thinking men are atheists the non existence of god was a regular theme in many of his novels james joyce one eight eight two one nine four one irish writer h p lovecraft one eight nine zero one nine three seven american author of fantasy and horror fiction christopher marlowe one five six four one five nine three english dramatist and poet arthur miller one nine one five two zero zero five american playwright essayist and author ron reagan one nine five eight american magazine journalist board member of the politi |
cally activistic creative coalition son of former u s president ronald reagan george bernard shaw one eight five six one nine five zero irish playwright michael shermer one nine five four american skeptic and science writer founder of the skeptics society sarah vowell one nine six nine american author journalist writer and voice actor ibn warraq one nine four six best selling author and secularist scholar of islam currently living in the united states he is a muslim apostate and an outspoken critic of islam who has written extensively on what he views as the oppressive nature of islam philosophy noam chomsky one nine two eight american philosopher linguist radical left wing political activist describes himself as libertarian socialist and anarcho syndicalist politics the first atheist state in history kun b la one eight eight six one nine three eight one nine three nine international soviet hungarian german communist leader vladimir ilich lenin one eight seven zero one nine two four russian revolutionary lead |
er benito mussolini one eight eight three one nine four five italian fascist dictator jawaharlal nehru one eight eight nine one nine six four indian statesman ture nerman one eight eight six one nine six nine one of the founders of swedish communism culbert olson one eight seven six one nine six two american politician former governor of california then president of the united secularists of america john sholto douglas nine th marquess of queensberry one eight four four one nine zero zero scottish aristocrat president of the british secular union josef stalin one eight seven nine one nine five three soviet politician revolutionary and leader of the ussr science and medicine peter atkins one nine four zero chemist former husband of baroness susan greenfield professor at oxford university nathaniel branden one nine three zero canadian psychologist and philosopher associated with objectivism mario bunge one nine one nine argentine philosopher and physicist left wing liberal author of a monumental treatise on bas |
ic philosophy francis crick one nine one six two zero zero four nobel prize laureate biophysicist co discoverer of the structure of dna a figure of molecular biology and also neuroscience pierre simon de laplace one seven four nine one eight two seven french mathematician and astronomer albert ellis one nine one three american psychologist creator of rational emotive behavior therapy richard feynman one nine one eight one nine eight eight american physicist and expert lecturer nobel prize in physics for his work on quantum electrodynamics alfred kinsey one eight nine four one nine five six researcher in the field of human sexuality and entomology jacques lacan french psychoanalyst richard m stallman one nine five three american computer programmer and founder of the free software foundation david suzuki one nine three six canadian geneticist and environmentalist see also list of people by belief list of people list of agnostics external links the celebrity atheist list includes living atheists and agnostics f |
amous black freethinkers lists of people by belief atheists a number of noted individuals have been buddhists historical buddhist thinkers and founders of schools individuals are grouped by nationality except in cases where the vast majority of their influence was felt elsewhere indian the buddha shakyamuni siddhartha gautama ananda siddhartha s cousin and one of his chief disciples aryadeva foremost disciple of nagarjuna continued the philosophical school of madhyamika asanga founder of the yogachara school widely considered the most important mahayana philosopher with nagarjuna atisha holder of the mind training tib lojong teachings considered an indirect founder of the geluk school of tibetan buddhism bhavaviveka early expositor of the svatantrika madhyamikha buddhaghosa theravadin commentator buddhapalita early expositor of the prasangika madhyamikha candragomin renowned grammarian chandrakirti considered the greatest exponent of prasangika madhyamika dharmakirti famed logician author of the seven treatis |
es student of dignana s student ishvarasena said to have debated famed hindu scholar shankara dignaga famed logician gunaprabha foremost student of vasubandhu known for his work the vinayasutra kamalashila eight th century author of important texts on meditation luipa one of the eighty four tantric mahasiddas mahakassapa pali mahakashyapa sanskrit a disciple of the buddha moggallana pali maudgalyayana sanskrit one of the two chief disciples of the buddha nagarjuna founder of the madhyamika school widely considered the most important mahayana philosopher with asanga nagpopa one of the eighty four tantric mahasiddas nadapada tib naropa tilopa s primary disciple teacher of marpa the translator and khungpo nyaljor sakyaprabha prominent expositor of the vinaya saraha famed mahasiddha forefather of the tibetan kagyu lineage sariputta pali shariputra sanskrit one of the two chief disciples of the buddha shantarakshita abbot of nalanda founder of the yogachara madhyamika who helped padmasambhava establish buddhism in |
tibet shantideva eight th century indian author of the bodhisattvacaryavatra talika tib tilopa recipient of four separate transmissions from nagarjuna nagpopa luipa and khandro kalpa zangmo naropa s teacher vasubandhu author of the abhidharmakosha vimuktisena commentator on texts of asanga s indo greek dharmaraksita three rd century bce greek buddhist missionary of emperor ashoka and a teacher of nagasena mahadharmaraksita two nd century bce greek buddhist master during the time of menander n gasena two nd century bce buddhist sage questioned about buddhism by milinda the indo greek king in the milinda pa ha central asian an shih kao a parthian monk and the first known buddhist missionary to china in one four eight ce dharmaraksa a yueh chih buddhist monk the first known translator of the lotus sutra into chinese jnanagupta five six one five nine two a monk and tranlator from gandhara pakistan kumarajiva c four zero one a kuchean monk and one of the most important translators lokaksema a kushan monk the firs |
t translator of mahayana scriptures into chinese around one eight zero ce prajna c eight one zero a monk and translator from kabul who translated important texts into chinese and educated the japanese kukai in sanskrit texts chinese baizhang huaihai bodhidharma legendary first patriarch of zen in china fazang ba tuo fo tuo fa xian translator and pilgrim seng chou joshu nine th century chinese zen monk huangbo xiyun fu yu jinaluo fa ru hui guang huineng six th patriarch of zen in china ingen one seven th century chinese zen monk founder of the baku sect of zen pu ji daoji buddhist monk revered as a deity in taoism jnanayasas translator linji nine th century chinese monk founder of the linji school of zen sanghapala six th century monk mon khmer who translated many texts to chinese shen xiu tang dynasty the chief of shao lin temple made great contribution to zen xuanzang brought yogacara to china to found faxiang school significant pilgrim translator ji gong yi jing pilgrim and translator yunmen wenyan founder |
of one of the five chan schools zhiyi founder of tiantai school zongmi wg tsung mi fifth patriarch of chinese huayan school ou yang jin wu hong yi also calligraphist painter master of seal carving tibetan gampopa a student of jetsun milarepa and founder of the karma kagy lineage of tibetan buddhism dolpopa founder of the jonang school and the shentong philosophy khungpo nyaljor founder of the shangpa kagy lineage longchenpa one of the greatest nyimgma philosophers marpa marpa the translator marpa of lhobrag student of naropa and a founder of the kagy lineage of tibetan buddhism milarepa a foremost student of marpa lotsawa padmasambhava tib guru rinpoche indian semi legendary founder of nyingma school of tibetan buddhism sakya pandita one of the greatest sakya philosphers tsongkhapa one four th century tibetan monk founder of the geluk school of tibetan buddhism based upon the kadam tradition japanese dogen zenji founder of soto zen based upon the chinese caodong tradition eisai one two th century japanese mon |
k travelled to china and returned to found the japanese rinzai sect of zen ippen founder of the japanese pure land ji sect ji shu ikkyu hakuin ekaku one six eight six one seven six nine rinzai zen honen founder of the japanese pure land jodo sect jodo shu kukai nine th century japanese monk founder of shingon myoe japanese monk of the shingon and kegon schools known for his propagation of the mantra of light nichiren founder of nichiren buddhism nikko founder of nichiren shoshu buddhism r ben eight th century japanese monk invited simsang to japan and founded the kegon tradition based upon the korean hwaeom school ryokan one eight th century japanese zen monk and poet saicho nine th century japanese monk founder of tendai tradition based upon the chinese tiantai school shinran founder of the japanese pure land jodo shin sect jodo shinshu takuan soho zen teacher and according to legend mentor of the swordsman miyamoto musashi korean gihwa one three seven six one four three three korean seon monk wrote commenta |
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