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tiles birds and mammals there are two ancient extinct subclasses subclass labyrinthodontia paraphyletic subclass lepospondyli of the remaining modern subclass lissamphibia there are three orders order anura frogs and toads in superorder salientia five two two eight species order caudata or urodela salamanders five five two species order gymnophiona or apoda caecilians one seven one species authorities disagree on whether salientia is a superorder that includes the order anura or whether anura is a sub order of the order salientia in effect salientia includes all the anura plus a single triassic proto frog species triadobatrachus massinoti practical considerations seem to favour using the former arrangement now reproduction for the purpose of reproduction most amphibians are bound to fresh water a few tolerate brackish water but there are no true sea water amphibians several hundred frog species in adaptive radiations e g eleutherodactylus the pacific platymantines the australo papuan microhylids and many othe |
r tropical frogs however do not need any water whatsoever they reproduce via direct development an ecological and evolutionary adaptation that has allowed them to be completely independent from free standing water almost all of these frogs live in wet tropical rainforests and their eggs hatch directly into miniature versions of the adult bypassing the tadpole stage entirely several species have also adapted to arid and semi arid environments but most of them still need water to lay their eggs symbiosis with single celled algae that lives in the jelly like layer of the eggs has evolved several times the larvae tadpoles or polliwogs breathe with exterior gills after hatching they start to transform gradually into the adult s appearance this process is called metamorphosis typically the animals then leave the water and become terrestrial adults but there are many interesting exceptions to this general way of reproduction the most obvious part of the amphibian metamorphosis is the formation of four legs in order |
to support the body on land but there are several other changes the gills are replaced by other respiratory organs i e lungs the skin changes and develops glands to avoid dehydration the eyes get eyelids and adapt to vision outside the water an eardrum is developed to lock the middle ear in frogs and toads the tail disappears amphibian conservation the golden toad of monteverde costa rica was among the first casualties of amphibian declines formerly abundant it was last seen in one nine eight nine dramatic declines in amphibian populations including population crashes and mass localized extinction have been noted in the past two decades from locations all over the world and amphibian declines are thus perceived as one of the most critical threats to global biodiversity a number of causes are believed to be involved including habitat destruction and modification over exploitation pollution introduced species climate change and disease however many of the causes of amphibian declines are still poorly understood |
and amphibian declines are currently a topic of much ongoing research see also frog zoology prehistoric amphibian tetrapod references duellman trueb biology of amphibians coauthors mart n r bustamante luis a coloma jamie a consuegra michael p l fogden pru n foster enrique la marca karen l masters andr s merino viteri robert puschendorf santiago r ron g arturo s nchez azofeifa christopher j still and bruce e young solomon berg martin biology external links american museum of natural history department of herpetology the global amphibian assessment amphibiaweb chordates amphibians alaska ipa is the four nine th state of the united states it was admitted on january three one nine five nine the population of the state is six two six nine three two as of two zero zero zero according to the two zero zero zero u s census alaska is most likely ranked the fourth smallest state population wise in the u s with wyoming vermont and by now north dakota smaller than alaska the name alaska is most likely derived from the al |
eut word alyeska meaning greater land as opposed to the aleut word aleutia meaning lesser land to the aleuts this distinction was a linguistic variation distinguishing the mainland from an island it is bordered by yukon territory and british columbia canada to the east the gulf of alaska and the pacific ocean to the south the bering sea bering strait and chukchi sea to the west and the beaufort sea and the arctic ocean to the north alaska is the largest state by area in the united states it is larger in area than all but one eight of the world s nations history alaska was first inhabited by humans who came across the bering land bridge eventually alaska became populated by the inupiaq inuit and yupik eskimos aleuts and a variety of american indian groups most if not all of the pre columbian population of the americas probably took this route and continued further south and east the first written accounts indicate that the first europeans to reach alaska came from russia vitus bering sailed east and saw mt st |
elias the russian american company hunted sea otters for their fur the colony was never very profitable because of the costs of transportation at the urging of u s secretary of state william seward the united states senate approved the purchase of alaska from russia for seven two zero zero zero zero zero approximately one three four zero zero zero zero zero zero in two zero zero five dollars adjusted for inflation on nine april one eight six seven and the united states flag was raised on one eight october of that same year now called alaska day coincident with the ownership change the de facto international date line was moved westward and alaska changed from the julian calendar to the gregorian calendar therefore for residents friday october six one eight six seven was followed by friday october one eight one eight six seven two fridays in a row because of the date line shift the first american administrator of alaska was polish immigrant w odzimierz krzy anowski the purchase was not popular in the contiguou |
s united states where alaska became known as seward s folly or seward s icebox alaska celebrates the purchase each year on the last monday of march calling it seward s day after the purchase of alaska between one eight six seven and one eight eight four the name was changed to the department of alaska between one eight eight four and one nine one two it was called the district of alaska president dwight d eisenhower signed the alaska statehood act into united states law on seven july one nine five eight which paved the way for alaska s admission into the union on january three one nine five nine alaska suffered one of the worst earthquakes in recorded north american history on good friday one nine six four see good friday earthquake in one nine seven six the people of alaska amended the state s constitution establishing the alaska permanent fund the fund invests a portion of the state s mineral revenue including revenue from the trans alaskan pipeline system to benefit all generations of alaskans in march two |
zero zero five the fund s value was over three zero billion prior to one nine eight three the state lay across four different time zones pacific standard time utc eight hours in the southeast panhandle a small area of yukon standard time utc nine hours around yakutat alaska hawaii standard time utc one zero hours in the anchorage and fairbanks vicinity with the nome area and most of the aleutian islands observing bering standard time utc one one hours in one nine eight three the number of time zones was reduced to two with the entire mainland plus the inner aleutian islands going to utc nine hours and this zone then being renamed alaska standard time as the yukon territory had several years earlier circa one nine seven five adopted a single time zone identical to pacific standard time and the remaining aleutian islands were slotted into the utc one zero hours zone which was then renamed hawaii aleutian standard time over the years various vessels have been named uss alaska in honor of the state during world |
war ii three of the outer aleutian islands attu agattu and kiska were occupied by japanese troops it was the only territory within the current borders of the united states to have land occupied during the war politics alaska is often characterized as a republican leaning state with strong libertarian tendencies local political communities often work on issues related to land use development fishing tourism and individual rights as many residents are proud of their rough alaskan heritage alaska natives while organized in and around their communities are often active within the native corporations which have been given ownership over large tracts of land and thus need to deliberate resource conservation and development issues in presidential elections the state s electoral college votes have been most often won by a republican nominee only once has alaska supported a democratic nominee when it supported lyndon b johnson in the landslide year of one nine six four although the one nine six zero and one nine six e |
ight elections were close no state has voted for a democratic presidential candidate fewer times president george w bush won the state s electoral votes in two zero zero four by a margin of two five percentage points with six one one of the vote juneau stands out as an area that supports democratic candidates when the united states congress in one nine five seven and one nine five eight debated the wisdom of admitting it as the four nine th state much of the political debate centered on whether alaska would become a democratic or republican leaning state conventional wisdom had it that with its rugged individualism penchant for new ideas and dependence on the federal government largess for basic needs it would become a democratic stronghold about which republicans and the then republican administration of dwight eisenhower had reservations given time those fears proved roundly unfounded after an early flirtatious period with liberal politics the political climate of alaska changed quickly once petroleum was d |
iscovered and the federal government came to be seen as meddling in local affairs still despite its libertarian leanings the state regularly takes in more federal money than it gives out a fact that can be attributed at least partially to its equal representation in the united states senate in recent years the alaska legislature is a two zero member senate serving four year terms and four zero member house serving two year terms it has been dominated by conservatives generally republicans likewise recent state governors have been mostly conservatives although not always elected under the official party banner republican wally hickel was elected to the office for a second term in one nine nine zero after jumping the republican ship and briefly joining the alaskan independence party ticket just long enough to be reelected he subsequently officially rejoined the republican fold in one nine nine four alaska s members of the u s congress are all republican u s senator ted stevens was appointed to the position foll |
owing the death of u s senator bob bartlett in december of one nine six eight and has never lost a re election campaign since as the longest serving republican in the senate some political wits call him senator for life stevens has been a crucial force in gaining federal money for his state until his resignation from the u s senate to run for governor republican frank murkowski held the state s other senatorial position and as governor was allowed to appoint his daughter lisa murkowski as his successor she won a full six year term on her own in two zero zero four alaska s sole u s house representative don young won re election to his one seven th straight term also in two zero zero four his seniority in house ranks him as one of the most influential republican house members his position on the house transportation committee allowed him to parlay some four five zero million to two bridge projects in alaska named the bridges to nowhere for which he gained national notoriety following the devastation in the stat |
e of louisiana following hurricane katrina and his insistence that the money not be returned to aid in rebuilding the gulf coast geography near little port walter alaska is one of the two states that is not bordered by another us state hawaii being the other it is the only state that is both in north america and is not part of the four eight contiguous states about five zero zero miles eight zero zero kilometers of canadian territory separate alaska from washington therefore alaska is an exclave of the united states that is part of the continental u s but is not part of the contiguous u s it is also the only mainland state whose capital city is accessible only via ship or air there are no roads connecting juneau to the rest of the state alaska is the largest state in the united states in terms of land area five seven zero three seven four square miles one four seven seven two six one km if a map of alaska were superimposed upon a map of the continental united states alaska would overlap texas oklahoma kansas |
new mexico and colorado alaska has the longest coastline of any state one scheme for describing the state s geography is by labeling the regions south central alaska is the southern coastal region and is the population center for the state the municipality of anchorage and many small but growing towns such as palmer and wasilla lie within this area petroleum industrial plants transportation tourism and two military bases form the core of the economy here the alaska panhandle also known as southeast alaska is home to juneau many small towns tidewater glaciers and extensive forests tourism fishing forestry and state government anchor the economy the alaska interior is home to fairbanks the geography is marked by large braided rivers such as the yukon river and the kuskokwim river as well as arctic tundra lands and shorelines the alaskan bush is the remote less crowded part of the state encompassing three eight zero native villages and small towns such as nome bethel kotzebue and most famously barrow the norther |
nmost town in the united states the northeast corner of alaska is covered by the arctic national wildlife refuge which covers one nine zero four nine two three six acres seven nine three one eight km with its numerous islands alaska has nearly three four zero zero zero miles five four seven zero zero km of tidal shoreline the island chain extending west from the southern tip of the alaska peninsula is called the aleutian islands many active volcanoes are found in the aleutians for example unimak island is home to mount shishaldin a moderately active volcano that rises to nine nine eight zero ft three zero four two m above sea level the chain of volcanoes extends to mount spurr west of anchorage on the mainland north america s second largest tides occur in turnagain arm just south of anchorage which often sees tidal differences of more than three five feet one zero seven m alaska is home to three five million lakes of two zero acres eight ha or larger marshlands and wetland permafrost cover one eight eight thr |
ee two zero square miles four eight seven seven four seven km mostly in northern western and southwest flatlands frozen water in the form of glacier ice covers some one six zero zero zero square miles four one four four zero km of land and one two zero zero square miles three one zero eight km of tidal zone the bering glacier complex near the southeastern border with yukon canada covers two two five zero square miles five eight two seven km alone the aleutian islands actually cross longitude one eight zero also making it the easternmost state although the international date line doglegs around them to keep the whole state in the same day it is part of the extreme points of the united states according to the october one nine nine eight report of the united states bureau of land management approximately six five of alaska is owned and managed by the u s federal government as national forests national parks and national wildlife refuges of these the bureau of land management manages eight seven million acres thr |
ee five zero zero zero zero km or two three eight of the state the arctic national wildlife refuge is managed by the united states fish and wildlife service of the remaining land area the state of alaska owns two four five another one zero is managed by thirteen regional and dozens of local native corporations created under the alaska native claims settlement act various private interests own the remaining land totaling less than one see also list of alaska rivers alaska peninsula bristol bay boroughs and census areas alaska has no counties in the sense used in the rest of the country instead the state is divided into two seven census areas and boroughs the difference between boroughs and census areas is that boroughs have an organized area wide government while census areas are artificial divisions defined by the united states census bureau for statistical purposes only areas of the state not in organized boroughs compose what the government of alaska calls the unorganized borough borough level government se |
rvices in the unorganized borough are provided by the state itself economy greetings from alaska the state s two zero zero three total gross state product was three one billion its per capita income for two zero zero three was three three two one three one four th in the nation alaska s main export is seafood agriculture represents only a fraction of the alaska economy agricultural production is primarily for consumption within the state and includes nursery stock dairy products vegetables and livestock manufacturing is limited with most foodstuffs and general goods imported from elsewhere employment is primarily in government and industries such as natural resource extraction shipping and transportation military bases are a significant component of the economy in both fairbanks and anchorage its industrial outputs are crude petroleum natural gas coal gold precious metals zinc and other mining seafood processing timber and wood products there is also a growing service and tourism sector tourists have contribu |
ted to the economy by supporting local lodging the cost of goods in alaska has long been higher than in the contiguous four eight states this has changed for the most part in anchorage and fairbanks where the cost of living is actually less than some major cities in the lower four eight thanks to lower housing and transportation costs the introduction of big box stores in anchorage fairbanks and juneau also did much to lower prices however rural alaska suffers from extremely high prices for food and consumer goods compared to the rest of the country due to the relatively limited transportation infrastructure many rural residents come in to these cities and purchase food and goods in bulk from warehouse clubs like costco and sam s club some have embraced the free shipping offers of some online retailers to purchase items much more cheaply than they could in their own communities if they are available at all transportation bridge on alaska highway between watson lake and whitehorse alaska is arguably the least |
connected state in terms of road transportation the state s road system covers a relatively small area of the state linking the central population centers and the alaska highway the principal route out of the state through canada the state capital juneau is not accessible by road which has spurred several debates over the decades about moving the capital to a city on the road system one unique feature of the road system is the anton anderson memorial tunnel which links the seward highway south of anchorage with the relatively isolated community of whittier the tunnel held the title of the longest road tunnel in north america at nearly two five miles four km until completion of the three five mile five six km interstate nine three tunnel as part of the big dig project in boston massachusetts the anderson tunnel combines a one lane roadway and train tracks in the same housing consequently eastbound traffic westbound traffic and the alaska railroad must share the tunnel resulting in waits of two zero minutes or |
more to enter as reflected on the alaska department of transportation tunnel website it is now considered north america s longest railroad highway tunnel the alaska railroad runs from seward through anchorage denali and fairbanks to north pole with spurs to whittier and palmer the railroad is famous for its summertime passenger services but also plays a vital part in moving alaska s natural resources such as coal and gravel to ports in anchorage whittier and seward the alaska railroad is the only remaining railroad in north america to use cabooses on its freight trains a stretch of the track along an area inaccessible by road serves as the only transportation to cabins in the area most cities and villages in the state are accessible only by sea or air alaska has a well developed ferry system known as the alaska marine highway which serves the cities of southeast and the alaska peninsula the system also operates a ferry service from bellingham washington up the inside passage to skagway cities not served by ro |
ad or sea can only be reached by air accounting for alaska s extremely well developed bush air services an alaskan novelty anchorage itself and to a lesser extent fairbanks are serviced by many major airlines air travel is the cheapest and most efficient form of transportation in and out of the state anchorage recently completed extensive remodeling and construction at ted stevens anchorage international airport to help accommodate the upsurge in tourism unofficial sources have estimated the numbers for two zero zero four at some four million tourists arriving in alaska between may and september however regular flights to most villages and towns within the state are commercially challenging to provide alaska airlines is the only major airline offering in state travel with jet service sometimes in combination cargo and passenger boeing seven three seven two zero zero s from anchorage and fairbanks to regional hubs like bethel nome kotzebue dillingham kodiak and other larger communities as well as to major sout |
heast and alaska peninsula communities the bulk of remaining commercial flight offerings come from small regional commuter airlines like era aviation penair and frontier flying service the smallest towns and villages must rely on scheduled or chartered bush flying services using general aviation aircraft such as the cessna caravan the most popular aircraft in use in the state much of this service can be attributed to the alaska bypass mail program which subsidizes bulk mail delivery to alaskan rural communities the program requires seven zero of that subsidy to go to carriers who offer passenger service to the communities but perhaps the most quintessentially alaskan plane is the bush seaplane the world s busiest seaplane base is lake hood located next to ted stevens anchorage international airport where flights bound for remote villages without an airstrip carry passengers cargo and lots of items from stores and warehouse clubs another alaskan transportation method is the dogsled in modern times dog mushing |
is more of a sport than a true means of transportation various races are held around the state but the best known is the iditarod a one one five zero mile one eight five zero km trail from anchorage to nome the race commemorates the famous one nine two five serum run to nome in which mushers and dogs like balto took much needed medicine to the diphtheria stricken community of nome when all other means of transportation had failed mushers from all over the world come to anchorage each march to compete for cash prizes and prestige demographics as of two zero zero five alaska has an estimated population of six six three six six one which is an increase of five nine zero six or zero nine from the prior year and an increase of three six seven three zero or five nine since the year two zero zero zero this includes a natural increase since the last census of three six five nine zero people derived from its five three one three two births of which one six five four two deaths is subtracted from and an increase due to |
net migration of one one eight one people into the state immigration from outside the united states resulted in a net increase of five eight zero zero people and migration within the country produced a net loss of four six one nine people alaska is the least densely populated state race and ancestry the racial breakdown of the state is six seven six white non hispanic one five six native american or alaska native four one hispanic four asian three five black five four mixed race the largest ancestry groups in the state are german one six six alaska native or american indian one five six irish one zero eight english nine six american five seven and norwegian four two alaska has the largest percentage of american indians one six of any state the vast sparsely populated bush regions of northern and western alaska are primarily inhabited by alaska natives and they also have a large presence in the southeast anchorage fairbanks and other parts of south central and southeast alaska have many whites of northern and |
western european ancestry the wrangell petersburg area has many residents of scandinavian ancestry and the aleutians have many filipinos most of the state s black population lives in anchorage as of two zero zero zero eight five seven of alaska residents age five and older speak english at home and five two speak native american languages spanish speakers make up two nine of the population followed by tagalog speakers at one five and korean at zero eight religion christian eight one protestant six eight baptist one one lutheran eight methodist six pentecostal two episcopal one quaker one orthodox eight catholic seven latter day saint one other religions one not religious agnostic one seven notable is alaska s relatively large eastern orthodox christian population a result of early russian colonization and missionary work among indigenous alaskans social issues alaska has long had a problem with alcohol use and abuse many rural communities in alaska have outlawed its import dry wet and damp are terms describi |
ng a community s laws on liquor consumption this problem directly relates to alaska s high rate of fetal alcohol syndrome fas as well as contributing to the high rate of suicides this is a controversial topic for many residents alaska has also had a problem with brain drain as many of its young people including most of the highest academic achievers leave the state upon graduating high school while for many this functions as a sort of walkabout many do not return to the state the university of alaska has been successfully combating this by offering four year scholarships to the top one zero percent of alaska high school graduates the alaska scholars program domestic abuse and other violent crimes are also at notoriously high levels in the state this is in part linked to alcohol abuse notable alaskans the national statuary hall of the united states of america is part of the capitol in washington d c each state has selected one or two distinguished citizens and provided statues alaska s are of its first two sen |
ators edward lewis bob bartlett one nine zero four one nine six eight was the territorial delegate to the us congress from one nine four four to one nine five eight and was elected as the first senior u s senator in one nine five eight and re elected in one nine six four there are streets buildings and even the first state ferry named for him ernest gruening one eight eight six one nine seven four was appointed governor of the territory of alaska in one nine three nine and served in that position for fourteen years he was elected to the united states senate in one nine five eight and re elected in one nine six two jay hammond one nine two two two zero zero five was governor during the building of the alaska pipeline and established the alaska permanent fund providing alaskans with essentially free money he is regarded as somewhat of a hero because of this he was also governor during passage of the alaska national interest lands conservation act and effectively served to moderate associated issues within the s |
tate among disparate interest groups ranging from conservationists to natives to pro development interests fran ulmer was the first woman elected to statewide office she became lieutenant governor in one nine nine four george sharrock one nine one zero two zero zero five moved to the territory before statehood eventually elected as the mayor of anchorage and served during the good friday earthquake in march one nine six four this was the most devastating earthquake to hit alaska and it sunk beach property damaged roads and destroyed buildings all over the south central area sharrock sometimes called the earthquake mayor led the city s rebuilding effort over six months important cities and towns alaska s most populous city is anchorage home of two six zero two eight three people two two five seven four four of whom live in the urbanized area it ranks third in the list of u s cities by area behind two other alaskan cities sitka ranks as america s largest city by area followed closely by juneau sitka town two fi |
ve richest places in alaska ranked by per capita income see also richest places in alaska colleges and universities university of alaska system university of alaska anchorage university of alaska fairbanks university of alaska southeast alaska bible college alaska pacific university charter college ilisagvik college sheldon jackson college external links state of alaska website us census bureau alaska com information alaska travel industry association alaska newspapers political parties alaska republican party alaska democratic party alaska republican moderate party alaskan independence party alaska libertarian party alaska green party alaska exclaves russian people in the united states states of the united states one nine five nine establishments in modern usage architecture is the art of creating an actual implied or apparent plan of any complex object or system the term can be used to connote the implied architecture of abstract things such as music or mathematics the apparent architecture of natural thing |
s such as geological formations or the structure of biological cells or explicitly planned architectures of human made things such as software computers enterprises and databases in addition to buildings in every usage an architecture may be seen as a subjective mapping from a human perspective that of the user in the case of abstract or physical artifacts to the elements or components of some kind of structure or system which preserves the relationships among the elements components architecture may refer to architecture built environment the art and science of designing habitations buildings and building complexes classical architecture architectural history studies the evolution and history of built architectures across the world through a consideration of various influences artistic cultural political economic and technological architecture other a representation of an arbitrary abstract natural or man made structure of two or more interacting parts e g architecture of mathematics architecture of language |
cytoarchitecture cellular architecture naval architecture skelletal architecture battlefield architecture all systems can be said to have an architecture biological architectures the apparent architecture of biological structures see cytoarchitecture structural biology cell architecture landscape architecture the design of man made land constructs systems architecture the representation of an engineered or to be engineered system and the process and discipline for effectively implementing the design s for such a system such a system may consist of information and or hardware and or software computer architecture the systems architecture of a computer software architecture the systems architecture of a software system enterprise architecture a systems architecture or framework for aligning an organization s structure processes information operations projects with the organization s overall strategy information architecture a systems architecture for structuring a knowledge based system product design or produ |
ct architecture the systems design of a product or product family vehicle architecture an automobile platform made from a set of components common to a number of different vehicles a farmer in germany working the land in the traditional way with horse and plough farming the modern way using a tractor in sweden agriculture is the process of producing food feed fiber and many other desired products by the cultivation of certain plants and the raising of domesticated animals livestock the practice of agriculture is also known as farming while scientists inventors and others devoted to improving farming methods and implements are also said to be engaged in agriculture more people in the world are involved in agriculture as their primary economic activity than in any other yet it only accounts for four percent of the world s gdp overview tea plantation in java indonesia agriculture sometimes refers to subsistence agriculture the production of enough food to meet just the needs of the farmer agriculturalist and his |
her family it may also refer to industrial agriculture often referred to as factory farming long prevalent in developed nations and increasingly so elsewhere which consists of obtaining financial income from the cultivation of land to yield produce the commercial raising of animals animal husbandry or both agriculture is also short for the study of the practice of agriculture more formally known as agricultural science agricultural students are known sometimes derisively as aggies increasingly in addition to food for humans and animal feeds agriculture produces goods such as cut flowers ornamental and nursery plants timber or lumber fertilizers animal hides leather industrial chemicals starch sugar ethanol alcohols and plastics fibers cotton wool hemp and flax fuels methane from biomass biodiesel and both legal and illegal drugs biopharmaceuticals tobacco marijuana opium cocaine genetically engineered plants and animals produce specialty drugs in the western world the use of gene manipulation better manageme |
nt of soil nutrients and improved weed control have greatly increased yields per unit area at the same time the use of mechanization has decreased labour requirements the developing world generally produces lower yields having less of the latest science capital and technology base modern agriculture depends heavily on engineering and technology and on the biological and physical sciences irrigation drainage conservation and sanitary engineering each of which is important in successful farming are some of the fields requiring the specialized knowledge of agricultural engineers agricultural chemistry deals with other vital farming concerns such as the application of fertilizer insecticides see pest control and fungicides soil makeup analysis of agricultural products and nutritional needs of farm animals plant breeding and genetics contribute additionally to farm productivity advanced seed engineering has allowed strains of seed to become perfect in every farming situation seeds can now germinate faster and adap |
t to shorter growing seasons in different climates present day seed can resist the spraying of pesticides that kill all green leaf plants hydroponics a method of soilless gardening in which plants are grown in chemical nutrient solutions may help meet the need for greater food production as the world s population increases the packing processing and marketing of agricultural products are closely related activities also influenced by science methods of quick freezing and dehydration have increased the markets for farm products see food preservation meat packing industry mechanization the outstanding characteristic of late one nine th and two zero th century agricultural evolution has eased much of the backbreaking toil of the farmer more significantly mechanization has enormously increased farm efficiency and productivity see agricultural machinery animals including horses mules oxen camels llamas alpacas and dogs however are still used to cultivate fields harvest crops and transport farm products to markets i |
n many parts of the world airplanes helicopters trucks and tractors are used in agriculture for seeding spraying operations for insect and disease control aerial topdressing transporting perishable products and fighting forest fires radio and television disseminate vital weather reports and other information such as market reports that concern farmers computers have become an essential tool for farm management farming ploughing rice paddy in indonesia according to the national academy of engineering in the us agricultural mechanization is one of the two zero greatest engineering achievements of the two zero th century early in the century it took one american farmer to produce food for two five people where today due to engineering technology also plant breeding and agrichemicals a single farmer can feed over one three zero people this comes at a cost however of large amounts of energy input from unsustainable mostly fossil fuel sources animal husbandry means breeding and raising animals for meat or to harves |
t animal products like milk eggs or wool on a continual basis in recent years some aspects of industrial intensive agriculture have been the subject of increasing discussion the widening sphere of influence held by large seed and chemical companies meat packers and food processors has been a source of concern both within the farming community and for the general public there has been increased activity of some people against some farming practices raising chickens for food being one example another issue is the type of feed given to some animals that can cause bovine spongiform encephalopathy in cattle there has also been concern because of the disastrous effect that intensive agriculture has on the environment in the us for example fertilizer has been running off into the mississippi for years and has caused a dead spot in the gulf of mexico where the mississippi empties intensive agriculture also depletes the fertility of the land over time and the end effect is that which happened in the middle east were s |
ome of the most fertile farmland in the world was turned into a desert by intensive agriculture the patent protection given to companies that develop new types of seed using genetic engineering has allowed seed to be licensed to farmers in much the same way that computer software is licensed to users this has changed the balance of power in favor of the seed companies allowing them to dictate terms and conditions previously unheard of some argue these companies are guilty of biopiracy soil conservation and nutrient management have been important concerns since the one nine five zero s with the best farmers taking a stewardship role with the land they operate however increasing contamination of waterways and wetlands by nutrients like nitrogen and phosphorus are of concern in many countries increasing consumer awareness of agricultural issues has led to the rise of community supported agriculture local food movement slow food and commercial organic farming though these yet remain fledgling industries history a |
ncient egyptian farmer main article history of agriculture archaeobotanists paleoethnobotanists have traced the selection and cultivation of specific food plant characteristics such as a semi tough rachis and larger seeds to just after the younger dryas about nine five zero zero bc in the early holocene in the levant region of the fertile crescent limited anthropological and archaeological evidence both indicate a grain grinding culture farming along the nile in the one zero th millennium bc using the world s earliest known type of sickle blades there is even earlier evidence for conscious cultivation and seasonal harvest grains of rye with domestic traits have been recovered from epi palaeolithic one zero zero zero zero bc contexts at abu hureyra in syria but this appears to be a localised phenomenon resulting from cultivation of stands of wild rye rather than a definitive step towards domestication it is not until ca eight five zero zero bc in middle eastern cultures referred to as pre pottery neolithic b p |
pnb where there is the first definite evidence for the emergence of a widespread subsistence economy that was dependent on domesticated plants and animals in these contexts lie the origins of the eight so called founder crops of agriculture firstly emmer wheat einkorn wheat then hulled barley pea lentil bitter vetch chick pea and flax these eight crops occur more or less simultaneously on ppnb sites in this region although the consensus is that wheat was the first to be sown and harvested on a significant scale there are many sites that date to between ca eight five zero zero bc and seven five zero zero bc where the systematic farming of these crops contributed the major part of the inhabitants diet from the fertile crescent agriculture spread eastwards to central asia and westwards into cyprus anatolia and by seven zero zero zero bc greece farming principally of emmer and einkorn reached northwestern europe via southeastern and central europe by ca four eight zero zero bc see among others price d ed two zero |
zero zero europe s first farmers cambridge university press harris d ed one nine nine six the origins and spread of agriculture in eurasia ucl press a tractor ploughing an alfalfa field the reasons for the earliest introduction of farming may have included climate change but possibly there were also social reasons e g accumulation of food surplus for competitive gift giving most certainly there was a gradual transition from hunter gatherer to agricultural economies after a lengthy period when some crops were deliberately planted and other foods were gathered from the wild although localised climate change is the favoured explanation for the origins of agriculture in the levant the fact that farming was invented at least three times possibly more suggests that social reasons may have been instrumental in addition to emergence of farming in the fertile crescent agriculture appeared by at least six eight zero zero bc in east asia rice and later in central and south america maize squash small scale agriculture a |
lso likely arose independently in early neolithic contexts in india rice and southeast asia taro sumerian harvester s sickle three zero zero zero bce baked clay field museum full dependency on domestic crops and animals i e when wild resources contributed a nutritionally insignificant component to the diet was not until the bronze age if the operative definition of agriculture includes large scale intensive cultivation of land mono cropping organised irrigation and use of a specialized labour force the title inventors of agriculture would fall to the sumerians starting ca five five zero zero bc intensive farming allows a much greater density of population than can be supported by hunting and gathering and allows for the accumulation of excess product to keep for winter use or to sell for profit the ability of farmers to feed large numbers of people whose activities have nothing to do with material production was the crucial factor in the rise of standing armies the agriculturalism of the sumerians allowed the |
m to embark on an unprecedented territorial expansion making them the first empire builders not long after the egyptians powered by effective farming of the nile valley achieved a population density from which enough warriors could be drawn for a territorial expansion more than tripling the sumerian empire in area the invention of a three field system of crop rotation during the middle ages vastly improved agricultural efficiency after one four nine two the world s agricultural patterns were shuffled in the widespread exchange of plants and animals known as the columbian exchange crops and animals that were previously only known in the old world were now transplanted to the new and vice versa perhaps most notably the tomato became a favorite in european cuisine while certain wheat strains quickly took to western hemisphere soils and became a dietary staple even for native north central and south americans by the early one eight zero zero s agricultural practices particularly careful selection of hardy strains |
and cultivars had so improved that yield per land unit was many times that seen in the middle ages and before especially in the largely virgin lands of north and south america with the rapid rise of mechanization in the two zero th century especially in the form of the tractor the demanding tasks of sowing harvesting and threshing could be performed with a speed and on a scale barely imaginable before these advances have led to efficiencies enabling certain modern farms in the united states argentina israel germany and a few other nations to output volumes of high quality produce per land unit at what may be the practical limit crops world production of major crops in two zero zero four in millions of metric tons based on fao estimates by crop types cereals two two six four vegetables and melons eight six six roots and tubers seven one five milk six one nine fruit five zero three meat two five nine oilcrops one three three fish one three zero two zero zero one estimate eggs six three pulses six zero vegetabl |
e fiber three zero by individual crops sugar cane one three two four maize seven two one wheat six two seven rice six zero five potatoes three two eight sugar beet two four nine soybean two zero four oil palm fruit one six two barley one five four tomato one two zero crop improvement an agricultural scientist records corn growth netting protecting wine grapes from birds see main article on plant breeding domestication of plants is done in order to increase yield improve disease resistance and drought tolerance ease harvest and to improve the taste and nutritional value and many other characteristics centuries of careful selection and breeding have had enormous effects on the characteristics of crop plants plant breeders use greenhouses and other techniques to get as many as three generations of plants per year so that they can make improvements all the more quickly plant selection and breeding in the one nine two zero s and three zero s improved pasture grasses and clover in new zealand extensive radiation mu |
tagenesis efforts i e primitive genetic engineering during the one nine five zero s produced the modern commercial varieties of grains such as wheat corn and barley for example average yields of corn maize in the usa have increased from around two five tons per hectare four zero bushels per acre in one nine zero zero to about nine four t ha one five zero bushels per acre in two zero zero one primarily due to improvements in genetics similarly worldwide average wheat yields have increased from less than one t ha in one nine zero zero to more than two five t ha in one nine nine zero south american average wheat yields are around two t ha african under one t ha egypt and arabia up to three five to four t ha with irrigation in contrast the average wheat yield in countries such as france is over eight t ha higher yields are due to improvements in genetics as well as use of intensive farming techniques use of fertilizers chemical pest control growth control to avoid lodging conversion note one bushel of wheat six z |
ero pounds lb two seven two one five kg one bushel of corn five six pounds two five four zero one kg in industrialized agriculture crop improvement has often reduced nutritional and other qualities of food plants to serve the interests of producers after mechanical tomato harvesters were developed in the early one nine six zero s agricultural scientists bred tomatoes that were harder and less nutritious friedland and barton one nine seven five in fact a major longitudinal study of nutrient levels in numerous vegetables showed significant declines in the last five zero years garden vegetables in the u s today contain on average three eight percent less vitamin b two and one five percent less vitamin c davis and riordan two zero zero four very recently genetic engineering has begun to be employed in some parts of the world to speed up the selection and breeding process the most widely used modification is a herbicide resistance gene that allows plants to tolerate exposure to glyphosate which is used to control |
weeds in the crop a less frequently used but more controversial modification causes the plant to produce a toxin to reduce damage from insects c f starlink there are specialty producers who raise less common types of livestock or plants aquaculture the farming of fish shrimp and algae is closely associated with agriculture apiculture the culture of bees traditionally for honey increasingly for crop pollination see also botany list of domesticated plants list of vegetables list of herbs list of fruit environmental problems agriculture may often cause environmental problems because it changes natural environments and produces harmful by products some of the negative effects are nitrogen and phosphorus surplus in rivers and lakes detrimental effects of herbicides fungicides insecticides and other biocides conversion of natural ecosystems of all types into arable land consolidation of diverse biomass into a few species erosion depletion of minerals in the soil particulate matter including ammonia and ammonium off |
gasing from animal waste contributing to air pollution weeds feral plants and animals odor from agricultural waste soil salination policy agricultural policy focuses on the goals and methods of agricultural production at the policy level common goals of agriculture include food safety ensuring that the food supply is free of contamination food security ensuring that the food supply meets the population s needs food quality ensuring that the food supply is of a consistent and known quality conservation environmental impact economic stability agricultural revolutions british agricultural revolution green revolution neolithic revolution methods there are various methods of agricultural production aeroponics aerial topdressing agricultural machinery animal husbandry aquaculture beekeeping crop rotation concentrated animal feeding operation cafo factory farming composting dairy farming detasseling domestication fencing fertilizers greenhouse harvest heliciculture hybrid seed hydroponics integrated pest management |
ipm irrigation livestock market gardening monoculture no till farming organic farming plant breeding permaculture pollination management precision farming ranching season extension seed saving seed testing shepherding subsistence farming succession planting sustainable agriculture terracing vegetable farming tillage weed control references wells spencer the journey of man a genetic odyssey princeton university press two zero zero three isbn zero six nine one one one five three two x crosby alfred w the columbian exchange biological and cultural consequences of one four nine two praeger publishers two zero zero three three zero th anniversary edition isbn zero two seven five nine eight zero seven three one collinson m editor a history of farming systems research cabi publishing two zero zero zero isbn zero eight five one nine nine four zero five nine davis donald r and hugh d riordan two zero zero four changes in usda food composition data for four three garden crops one nine five zero to one nine nine nine j |
ournal of the american college of nutrition vol two three no six six six nine six eight two friedland william h and amy barton one nine seven five destalking the wily tomato a case study of social consequences in california agricultural research univ california at sta cruz research monograph one five see also agricultural and food research council uk agricultural education agricultural science agricultural sciences basic topics arid zone agriculture barnyard community supported agriculture international agricultural research family farm hog pen farm equipment land allocation decision support system list of domesticated animals list of subsistence techniques list of countries by agricultural output list of sustainable agriculture topics permaculture protein per unit area timeline of agriculture and food technology usa agriculture herd of herefords in a green field external links www fao org food and agriculture organization of the united nations world agricultural information centre www fao org the un statisti |
cal databases www fao org faostat the faostat statistical databases www fao org es ess the fao statistics division fao agriculture department and its state of food and agriculture two zero zero three two zero zero four with a focus on the impact of biotechnology gm crops in agriculture a summary for non specialists of the above fao report by greenfacts agriculture demon engine of civilization by john zerzan have a farmaze for food from afar history of uk agriculture specific countries www agr gc ca agriculture agri food canada www nationalpak com agriculture of pakistan www nationalacademies org agriculture at the united states national academies www usda gov united states department of agriculture current world production market and trade reports from the foreign agricultural service usda s main source of economic information and research from the economic research service in house research arm from the agricultural research service national agricultural library agriculture aldous leonard huxley july two six |
one eight nine four november two two one nine six three was a british writer who emigrated to the united states he was a member of the famous huxley family who produced a number of brilliant scientific minds best known for his novels and wide ranging output of essays he also published short stories poetry travel writing and film stories and scripts through his novels and essays huxley functioned as an examiner and sometimes critic of social mores societal norms and ideals and possible misapplications of science in human life while his earlier concerns might be called humanist ultimately he became quite interested in spiritual subjects like parapsychology and mystically based philosophy which he also wrote about by the end of his life huxley was considered in certain circles a leader of modern thought biography early years family tree huxley was born in godalming surrey england he was the son of the writer leonard huxley by his first wife julia arnold and grandson of thomas henry huxley one of the most import |
ant naturalists of the one nine th century a man known as darwin s bulldog his brother julian huxley was a biologist also noted for his evolutionary theories huxley understandably excelled in the areas he took up professionally for on his father s side were a number of noted men of science while on his mother s were people of literary accomplishment huxley was a lanky delicately framed child who was gifted intellectually his father was a professional herbalist as well as an author so aldous began his learning in his father s well equipped botanical laboratory then continued in a school named hillside which his mother supervised for several years until she became terminally ill from the age of nine aldous was then educated in the british boarding school system he took readily to the handling of ideas his mother julia died in one nine zero eight when aldous was only fourteen and his sister roberta died of an unrelated incident in the same month three years later aldous suffered an illness keratitis punctata whi |
ch seriously damaged his eyesight his older brother trev committed suicide in one nine one four aldous s near blindness disqualified him from service in world war i once his eyesight recovered he was able to read english literature at balliol college oxford where he was a member of the cambridge apostles maturing as a lean young man well over six feet in height the cerebrotonic huxley s initial interest in literature was primarily intellectual while he was noted for his personal kindliness only considerably later some say under the influence of such friends as d h lawrence did he heartily embrace feelings as matters of importance in his evolving personal philosophy and literary expression following his education at balliol huxley was financially indebted to his father and had to earn a living for a short while in one nine one eight he was employed acquiring provisions at the air ministry but never desiring a career in administration or in business huxley s lack of inherited means propelled him into applied li |
terary work huxley had completed his first unpublished novel at the age of seventeen and began writing seriously in his early twenties he wrote great novels on dehumanising aspects of scientific progress most famously brave new world and on pacifist themes e g eyeless in gaza huxley was strongly influenced by f matthias alexander and included him as a character in eyeless in gaza middle years already a noted satirist and social thinker during world war i huxley spent much of his time at garsington manor home of lady ottoline morrell later in crome yellow one nine two one he caricatured the garsington lifestyle he married maria nys whom he had met at garsington they had one child matthew who grew up to be an epidemiologist huxley moved to hollywood california in one nine three seven with his wife and friend gerald heard heard introduced huxley to vedanta and meditating in huxley s one nine three seven book ends and means most people in modern civilization agree that they want a world of liberty peace justice a |
nd brotherly love though they haven t been able to agree on how to achieve it his book goes on to explore why the confusion or disagreement is there and what might be done about it in one nine three eight huxley befriended j krishnamurti whose teachings he greatly admired he also became a vedantist in the circle of swami prabhavananda and he also introduced christopher isherwood to this circle not long after huxley wrote his book on widely held spiritual values and ideas the perennial philosophy which discussed teachings of the world s great mystics for most of his life since the illness in his teens which left huxley nearly blind his eyesight was poor despite the partial recovery which had enabled him to study at oxford around one nine three nine he heard of the bates method for natural vision improvement and of a teacher margaret corbett who was able to teach him in the method he claimed his sight improved dramatically as a result of using the method then later wrote a book about it the art of seeing which |
was published in one nine four two us one nine four three uk he reported that for the first time in over two five years he was able to read without spectacles and without strain he was a screenwriter for the one nine four zero production of pride and prejudice later years after world war ii huxley applied for united states citizenship but was denied because he would not say he would take up arms to defend america he became a vegetarian thereafter his works were strongly influenced by mysticism and his experiences with the hallucinogenic drug mescaline to which he was introduced by the psychiatrist humphry osmond in one nine five three his years on psychoactive drugs were described as a paradise washed down with bourbon generally he was a pioneer of self directed psychedelic drug use in a search for enlightenment famously taking one zero zero micrograms of lsd as he lay dying huxley s psychedelic drug experiences are described in the essays the doors of perception the title deriving from some lines in the book |
the marriage of heaven and hell by william blake and heaven and hell the title of the former became the inspiration for the naming of the rock band the doors some of his writings on psychedelics became frequent reading among early hippies huxley s main interest was not in just anything vague mysterious or subjective but in what is sometimes termed higher mysticism he liked the term perennial philosophy that he used as the title of his noted book on the topic during the one nine five zero s huxley s interest in the related field of psychical research grew keener huxley s wife maria died of breast cancer in one nine five five and in one nine five six he remarried to laura archera who was herself an author and who wrote a biography of aldous in one nine six zero huxley was diagnosed with throat cancer in the years that followed with his health deteriorating he wrote the utopian novel island and gave lectures on human potentialities at the esalen institute in one nine five nine huxley who remained a british citi |
zen turned down an offer of a knight bachelor by the macmillan government his ideas were foundational to the forming of the human potential movement he was also invited to speak at several prestigious american universities at a speech given in one nine six one at the california medical school in san francisco huxley warned there will be in the next generation or so a pharmacological method of making people love their servitude and producing dictatorship without tears so to speak producing a kind of painless concentration camp for entire societies so that people will in fact have their liberties taken away from them but will rather enjoy it an idea not dissimilar to his contemporary writer j b priestley s idea in the magicians huxley s views on the proper roles of science and technology as he portrayed these say in island are akin to some other noted english and american thinkers of the twentieth century such as lewis mumford and huxley s friend gerald heard and in some ways buckminster fuller and e f schumach |
er clearly these men found descendants in some significant movers of a younger generation e g stewart brand via gerald heard huxley was introduced to the young huston smith who went on to become a prolific and famous scholar on the religions of man the two friends acquianted smith with vedanta and meditative practice later while huxley was a guest professor at m i t he made introductions between smith and timothy leary that lead to epiphanies smith covers in his later book cleansing of the doors of perception amongst humanists huxley was considered an intellectual s intellectual although his financial circumstances had forced him to churn out articles and books his thinking and best writing earned him an exalted esteem his books were frequently on the required reading lists of english and modern philosophy courses in american colleges and universities he was one of the twentieth century thinkers honoured in the scribners publishing s leaders of modern thought series a volume of biography and literary criticis |
m by philip thody aldous huxley death and afterwards on his deathbed unable to speak he made a written request to his wife for lsd one zero zero g i m she obliged and he died peacefully the following morning november two two one nine six three media coverage of his death was overshadowed by news of the assassination of president john f kennedy which occurred on the same day as did the death of the irish author c s lewis in all of huxley s mature writings one finds an awareness that seems to bridge the gap between the two cultures the sciences and the humanities this gulf posed a potentially enormous problem one that was recognized by other thinkers during huxley s lifetime such as c p snow the interest among professors of humanities and liberal arts in huxley s work both during the writer s lifetime and afterwards rests on this consciousness on the part of the author and of course on the artful and often humorous way in which he expressed himself huxley s satirical dystopian and utopian novels seldom fail to |
stimulate thought the same may be said for his essays and essay collections perhaps his main message is the tragedy that frequently follows from egocentrism self centredness and selfishness films huxley wrote many screenplays and many of his novels were later adapted for film or television notable works include the original screenplay for disney s animated alice in wonderland two productions of brave new world one of point counter point one of eyeless in gaza and one of ape and essence he was one of the screenwriters for the one nine four zero version of pride and prejudice and co wrote the screenplay for the one nine four four version of jane eyre with john houseman director ken russell s one nine seven one film the devils starring vanessa redgrave is adapted from huxley s the devils of loudun and a one nine nine zero made for television film adaptation of brave new world was directed by burt brinckeroffer selected works novels crome yellow one nine two one antic hay one nine two three those barren leaves on |
e nine two five point counter point one nine two eight brave new world one nine three two eyeless in gaza one nine three six after many a summer one nine three nine time must have a stop one nine four four ape and essence one nine four eight the genius and the goddess one nine five five island one nine six two short stories limbo one nine two zero mortal coils one nine two two brief candles one nine three zero two or three graces little mexican the young arquimedes jacob s hands a fable late one nine three zero s poetry the burning wheel one nine one six jonah one nine one seven the defeat of youth one nine one eight leda one nine two zero arabia infelix one nine two nine the cicadias and other poems one nine three one travel writing along the road one nine two five jesting pilate one nine two six beyond the mexique bay one nine three four essays do what you will one nine two nine the olive tree one nine three six the art of seeing one nine four two tomorrow and tomorrow and tomorrow one nine five two the doo |
rs of perception one nine five four heaven and hell one nine five six brave new world revisited one nine five eight literature and science one nine six three philosophy ends and means one nine three seven the perennial philosophy one nine four four isbn zero zero six zero five seven zero five eight x biography grey eminence one nine four one the devils of loudun one nine five two children s literature the crows of pearblossom one nine six seven collections text and pretext one nine three three collected short stories one nine five seven moksha writings on psychedelics and the visionary experience one nine seven seven quotes on truth great is truth but still greater from a practical point of view is silence about truth by simply not mentioning certain subjects totalitarian propagandists have influenced opinion much more effectively than they could have by the most eloquent denunciations on the new world order one nine five nine and it seems to me perfectly in the cards that there will be within the next genera |
tion or so a pharmacological method of making people love their servitude and producing a kind of painless concentration camp for entire societies so that people will in fact have their liberties taken away from them but will rather enjoy it because they will be distracted from any desire to rebel by propaganda brainwashing or brainwashing enhanced by pharmacological methods on social organizations one of the many reasons for the bewildering and tragic character of human existence is the fact that social organization is at once necessary and fatal men are forever creating such organizations for their own convenience and forever finding themselves the victims of their home made monsters trivia he was six feet four and a half inches tall studied ballet for several years was george orwell s french teacher for a term at eton is shown on the cover of the beatles album sgt pepper s lonely hearts club band as number one eight in the top right hand corner external links video interviews of huxley from the one nine fi |
ve zero s exploring brave new world island and psychedelics the gravity of light brave new world the complete book somaweb extensive aldous huxley bibliography and links to online material island web creating a new culture as inspired by the ideas of aldous huxley website of the island foundation the ultimate revolution talk at uc berkeley march two zero one nine six two polymaths natives of surrey huxley family former students of balliol college oxford english novelists british science fiction writers english science fiction writers english poets english essayists english satirists english short story writers english travel writers psychedelic advocates and proponents human potential movement vegetarians meanings of ada people variant transliteration of hebrew adah ada lady lovelace ada sister of charlemagne for whom the ada gospels at trier were produced ada satrap of caria deposed by her brother idrieus restored by alexander the great places ada afghanistan ada saskatchewan canada ada ghana ada greece ada |
nigeria ada serbia ada oregon usa historical ada county idaho usa ada division oklahoma usa ada alabama usa ada arkansas usa ada kansas usa ada louisiana usa ada michigan usa ada minnesota usa ada ohio usa ada oklahoma usa ada virginia usa ada wisconsin usa ada west virginia usa ada township michigan usa ada township north dakota usa ada township south dakota usa initialisms aeronautical development agency of india s ministry of defence air defense artillery a branch of the united states army american decency association american dental association american diabetes association american dietetic association americans for democratic action americans with disabilities act aotearoa digital arts http ada waikato ac nz assistant district attorney average daily attendance other ada programming language ada a genus of orchids the short title of ada or ardor a family chronicle a novel by vladimir nabokov one nine six nine ada a demon after which adasaurus was named ada a film directed by daniel mann with susan haywar |
d y dean martin means father in sindarin elvish aberdeen may refer to places in scotland aberdeen a major port city in north east scotland in australia aberdeen new south wales in canada aberdeen centre an asian themed shopping mall in richmond british columbia aberdeen british columbia two locations aberdeen fraser valley regional district british columbia aberdeen thompson nicola regional district british columbia aberdeen new brunswick aberdeen nova scotia new aberdeen nova scotia aberdeen bay nunavut aberdeen lake nunavut aberdeen ontario two locations aberdeen ontario grey county aberdeen ontario prescott and russell county aberdeen township ontario macdonald merideth and aberdeen additional ontario sheen esher aberdeen et malakoff quebec aberdeen saskatchewan aberdeen no three seven three saskatchewan in china aberdeen harbour hong kong in south africa aberdeen south africa in the united states aberdeen arkansas aberdeen california aberdeen florida aberdeen georgia aberdeen idaho aberdeen indiana aberde |
en kentucky aberdeen massachusetts aberdeen maryland aberdeen mississippi aberdeen montana aberdeen township new jersey aberdeen north carolina aberdeen ohio aberdeen pennsylvania aberdeen south dakota aberdeen texas aberdeen washington aberdeen west virginia other aberdeen band an american rock band aberdeen movie a movie two zero zero zero directed by hans petter moland starring stellan skarsg rd and lena headey aberdeen city band aberdeen proving ground a u s army installation in maryland this article is about an organism see algae programming language for a programming language in computing a seaweed laurencia up close the branches are multicellular and only about one mm thick much smaller algae are seen growing attached to the structure extending upwards in the lower right quarter algae singular alga encompass several different groups of living organisms that capture light energy through photosynthesis converting inorganic substances into simple sugars using the captured energy algae have been traditiona |
lly regarded as simple plants and some are closely related to the higher plants others appear to represent different protist groups alongside other organisms that are traditionally considered more animal like that is protozoa thus algae do not represent a single evolutionary direction or line but a level of organization that may have developed several times in the early history of life on earth algae range from single celled organisms to multi cellular organisms some with fairly complex differentiated form and if marine called seaweeds all lack leaves roots flowers and other organ structures that characterize higher plants they are distinguished from other protozoa in that they are photoautotrophic although this is not a hard and fast distinction as some groups contain members that are mixotrophic deriving energy both from photosynthesis and uptake of organic carbon either by osmotrophy myzotrophy or phagotrophy some unicellular species rely entirely on external energy sources and have reduced or lost their p |
hotosynthetic apparatus all algae have photosynthetic machinery ultimately derived from the cyanobacteria and so produce oxygen as a by product of photosynthesis unlike non cyanobacterial photosynthetic bacteria algae are usually found in damp places or bodies of water and thus are common in terrestrial as well as aquatic environments however terrestrial algae are usually rather inconspicuous and far more common in moist tropical regions than dry ones because algae lack vascular tissues and other adaptions to live on land algae can endure dryness and other conditions in symbiosis with a fungus as lichen the various sorts of algae play significant roles in aquatic ecology microscopic forms that live suspended in the water column called phytoplankton provide the food base for most marine food chains in very high densities so called algal blooms these algae may discolor the water and outcompete or poison other life forms seaweeds grow mostly in shallow marine waters some are used as human food or harvested for u |
seful substances such as agar or fertilizer the study of algae is called phycology or algology relationships among algal groups prokaryotic algae traditionally the cyanobacteria have been included among the algae referred to as the cyanophytes or blue green algae the term algae refers to any aquatic organisms capable of photosynthesis though some recent treatises on algae specifically exclude them cyanobacteria are some of the oldest organisms to appear in the fossil record dating back about three eight billion years precambrian ancient cyanobacteria likely produced much of the oxygen in the earth s atmosphere cyanobacteria can be unicellular colonial or filamentous they have a prokaryotic cell structure typical of bacteria and conduct photosynthesis directly within the cytoplasm rather than in specialized organelles some filamentous blue green algae have specialized cells termed heterocysts in which nitrogen fixation occurs eukaryotic algae all other algae are eukaryotes and conduct photosynthesis within mem |
brane bound structures organelles called chloroplasts chloroplasts contain dna and are similar in structure to cyanobacteria presumably representing reduced cyanobacterial endosymbionts the exact nature of the chloroplasts is different among the different lines of algae reflecting different endosymbiotic events there are three groups archaeplastida that have primary chloroplasts green algae together with higher plants red algae glaucophytes in these groups the chloroplast is surrounded by two membranes and probably developed through a single endosymbiosis the chloroplasts of red algae have a more or less typical cyanobacterial pigmentation while those of the green alga have chloroplasts with chlorophyll a and b the latter found in some cyanobacteria and not most higher plants are pigmented similarly to green algae and probably developed from them two other groups of algae have green chloroplasts containing chlorophyll b euglenids and chlorarachniophytes these are surrounded by three and four membranes respect |
ively and were probably retained from an ingested green alga those of the chlorarchniophytes contain a small nucleomorph which is the remnant of the alga s nucleus it has been suggested that the euglenid chloroplasts only have three membranes because they were acquired through myzocytosis rather than phagocytosis the remaining algae all have chloroplasts containing chlorophylls a and c the latter chlorophyll type is not known from any prokaryotes or primary chloroplasts but genetic similarities with the red algae suggest a relationship there these groups include heterokonts e g golden algae diatoms brown algae haptophytes e g coccolithophores cryptomonads dinoflagellates in the first three of these groups chromista the chloroplast has four membranes retaining a nucleomorph in cryptomonads and they likely share a common pigmented ancestor the typical dinoflagellate chloroplast has three membranes but there is considerable diversity in chloroplasts among the group as some members have acquired theirs from diffe |
rent sources the apicomplexa a group of closely related parasites also have plastids though not actual chloroplasts which appear to have a common origin with those of the dinoflagellates note many of these groups contain some members that are no longer photosynthetic some retain plastids but not chloroplasts while others have lost them entirely forms of algae most of the simpler algae are unicellular flagellates or amoeboids but colonial and non motile forms have developed independently among several of the groups some of the more common organizational levels more than one of which may occur in the life cycle of a species are colonial small regular groups of motile cells capsoid individual non motile cells embedded in mucilage coccoid individual non motile cells with cell walls palmelloid non motile cells embedded in mucilage filamentous a string of non motile cells connected together sometimes branching parenchymatous cells forming a thallus with partial differentiation of tissues in three lines even higher |
levels of organization have been reached leading to organisms with full tissue differentiation these are the brown algae some of which may reach seven zero m in length kelps the red algae and the green algae the most complex forms are found among the green algae see charales in a lineage that eventually led to the higher land plants the point where these non algal plants begin and algae stop is usually taken to be the presence of reproductive organs with protective cell layers a characteristic not found in the other alga groups algae and symbioses some species of algae form symbiotic relationships with other organisms in these symbioses the algae supply photosynthates organic substances to the host organism providing protection to the algal cells the host organism derives some or all of its energy requirements from the alga examples include lichens a fungus is the host usually with a green alga or a cyanobacterium as its symbiont both fungal and algal species found in lichens are capable of living independent |
ly although habitat requirements may be greatly different from those of the lichen pair corals algae known as zooxanthellae are symbionts with corals notable amongst these is the dinoflagellate symbiodinium found in many hard corals the loss of symbiodinium or other zooxanthellae from the host is known as coral bleaching sponges uses of algae algae are used by man in a great many ways because many species are aquatic and microscopic they are cultured in clear tanks or ponds and either harvested or used to treat effluents pumped through the ponds algae culture on a large scale is an important type of aquaculture in some places energy source algae can be used to produce biodiesel see algae culture and by some estimates can produce vastly superior amounts of oil compared to terrestrial crops grown for the same purpose because algae grown to produce biodiesel does not need to meet the requirements of a food crop it is much cheaper to produce also it does not need fresh water or fertilizer both of which are quite |
expensive algae can be grown to produce hydrogen in one nine three nine a german researcher named hans gaffron while working at the university of chicago observed that the algae he was studying chlamydomonas reinhardtii a green algae would sometimes switch from the production of oxygen to the production of hydrogen gaffron never discovered the cause for this change and for many years other scientists failed in their attempts at its discovery in the late one nine nine zero s professor anastasios melis a researcher at the university of california at berkeley discovered that if you deprive the algae of sulfur it will switch from the production of oxygen normal photosynthesis to the production of hydrogen he found that the enzyme responsible for this reaction is hydrogenase but that the hydrogenase will not cause this switch in the pressence of oxygen melis found that depleting the amount of sulfur available to the algae interrupted its internal oxygen flow allowing the hydrogenase an environment in which it can |
react causing the algae to produce hydrogen chlamydomonas moeweesi is also a good strain for the production of hydrogen algae can be grown to produce biomass which can be burned to produce heat and electricity pmb berkeley edu pollution control algae are used in wastewater treatment facilities reducing the need for more dangerous chemicals algae can be used to capture fertilizers in runoff from farms if this algae is then harvested it itself can be used as fertilizer algae are used by some powerplants to reduce co two emissions the co two is pumped into a pond or some kind of tank on which the algae feed nutritional value of algae algae is commercially cultivated as a nutritional supplement one of the most popular microalgal species is spirulina arthrospira platensis which is a cyanobacteria known as blue green algae and has been hailed by some as a superfood other algal species cultivated for their nutritional value include chlorella a green algae and dunaliella dunaliella salina which is high in beta carote |
ne and is used in vitamin c supplements algae is sometimes also used as a food as in the chinese vegetable known as fat choy which is actually a cyanobacterium the oil from some algae have high levels of unsaturated fatty acids arachidonic acid a polyunsaturated fatty acid is very high in parietochloris incisa a green algae where it reaches up to four seven of the triglyceride pool bigogno c et al phytochemistry two zero zero two six zero four nine seven www spirulinasource com www cfsan fda gov fda on algal oil use in food products the natural pigments produced by algae can be used as an alternative to chemical dyes and coloring agents many of the paper products used today are not recyclable because of the chemical inks that they use paper recyclers have found that inks made from algae are much easier to break down there is also much interest in the food industry into replacing the coloring agents that are currently used with coloring derived from algal pigments see also algae culture brown algae coccolithop |
hore cyanobacteria diatom golden algae green algae important publications in phycology red algae yellow green algae external links www phyco org a wiki based site that is focused on energy production from algae biodieselnow com biodiesel production biodiesel from algae www algaebase org australian freshwater algae sydney botanic gardens learn about algae red tide national office for marine biotoxins and harmful algal blooms usa algae section national museum of natural history smithsonian institution www plantphysiol org cyanosite algae botany in statistics analysis of variance anova is a collection of statistical models and their associated procedures which compare means by splitting the overall observed variance into different parts the initial techniques of the analysis of variance were pioneered by the statistician and geneticist ronald fisher in the one nine two zero s and one nine three zero s and is sometimes known as fisher s anova or fisher s analysis of variance overview there are three conceptual cl |
asses of such models fixed effects model assumes that the data come from normal populations which differ in their means random effects models assume that the data describe a hierarchy of different populations whose differences are constrained by the hierarchy mixed models describe situations where both fixed and random effects are present the fundamental technique is a partitioning of the total sum of squares into components related to the effects in the model used for example we show the model for a simplified anova with one type of treatment at different levels if the treatment levels are quantitative and the effects are linear a linear regression analysis may be appropriate ss ss ss the number of degrees of freedom abbreviated df can be partitioned in a similar way and specifies the chi square distribution which describes the associated sums of squares df df df fixed effects model the fixed effects model of analysis of variance applies to situations in which the experimenter has subjected his experimental |
material to several treatments each of which affects only the mean of the underlying normal distribution of the response variable random effects model random effects models are used to describe situations in which incomparable differences in experimental material occur the simplest example is that of estimating the unknown mean of a population whose individuals differ from each other in this case the variation between individuals is confounded with that of the observing instrument degrees of freedom degrees of freedom indicates the effective number of observations which contribute to the sum of squares in an anova the total number of observations minus the number of linear constraints in the data tests of significance analyses of variance lead to tests of statistical significance using fisher s f distribution see also ancova manova important publications in analysis of variance multiple comparisons duncan s new multiple range test external links analysis of variance sixsigmafirst statistics for saturated hydr |
ocarbons containing one or more rings see cycloalkane an alkane in organic chemistry is a saturated hydrocarbon without cycles that is an acyclic hydrocarbon in which the molecule has the maximum possible number of hydrogen atoms and so has no double bonds alkanes are aliphatic compounds the general formula for alkanes is cnh two n two the simplest possible alkane is therefore methane ch four the next simplest is ethane c two h six the series continues indefinitely each carbon atom in an alkane has sp hybridization alkanes are also known as paraffins or collectively as the paraffin series these terms also used for alkanes whose carbon atoms form a single unbranched chain such branched chain alkanes are called isoparaffins isomerism the atoms in alkanes with more than three carbon atoms can be arranged in multiple ways forming different isomers normal alkanes have a linear unbranched configuration the number of isomers increases rapidly with the number of carbon atoms for alkanes with one to one two carbon ato |
ms the number of isomers equals one one one two three five nine one eight three five seven five one five nine and three five five respectively nomenclature of alkanes the names of all alkanes end with ane alkanes with unbranched carbon chains the first four members of the series in terms of number of carbon atoms are named as follows methane ch four ethane c two h six propane c three h eight butane c four h one zero alkanes with five or more carbon atoms are named by adding the suffix ane to the appropriate numerical multiplier with elision of a terminal a from the basic numerical term hence pentane c five h one two hexane c six h one four heptane c seven h one six octane c eight h one eight etc for a more complete list see list of alkanes straight chain alkanes are sometimes indicated by the prefix n for normal to distinguish them from branched chain alkanes having the same number of carbon atoms although this is not strictly necessary the usage is still common in cases where there is an important difference |
in properties between the straight chain and branched chain isomers e g n hexane is a neurotoxin while its branched chain isomers are not alkanes with branched carbon chains branched alkanes are named as follows identify the longest straight chain of carbon atoms number the atoms in this chain starting from one at one end and counting upwards to the other end examine the groups attached to the chain in order and form their names form the name by looking at the different attached groups and writing for each group the following the number or numbers of the carbon atom or atoms where it is attached the prefixes di tri tetra etc if the group is attached in two three four etc places or nothing if it is attached in only one place the name of the attached group the formation of the name is finished by writing down the name of the longest straight chain to carry out this algorithm we must know how to name the substituent groups this is done by the same method except that instead of the longest chain of carbon atoms |
the longest chain starting from the attachment point is used also the numbering is done so that the carbon atom next to the attachment point has the number one for example the compound is the only four carbon alkane possible apart from butane its formal name is two methylpropane pentane however has two branched isomers in addition to its linear normal form two two dimethylpropane and two methylbutane trivial names the following nonsystematic names are retained in the iupac system isobutane for two methylpropane isopentane for two methylbutane neopentane for two two dimethylpropane the name isooctane is very widely used in the petrochemical industry to refer to two two four trimethylpentane occurrence methane and ethane make up a large proportion of jupiter s atmosphere alkanes occur both on earth and in the solar system however only the first hundred or so and even then mostly only in traces the light hydrocarbons especially methane and ethane for example have been detected both in the tail of the comet hyaku |
take and in some meteorites such as carbonaceous chondrites they also form an important portion of the atmospheres of the outer gas planets jupiter saturn uranus and neptune on titan the satellite of saturn it is believed that there were once large oceans of these and longer chain alkanes smaller seas of liquid ethane are thought still to exist there traces of methane about zero zero zero zero one or one ppm occur in the earth s atmosphere produced primarily by forms of archaea the content in the oceans is negligible due to the low solubility in water however at high pressures and low temperatures methane can co crystallize with water to form a solid methane hydrate although they cannot be commercially exploited at the present time the calorific value of the known methane hydrate fields exceeds the energy content of all the natural gas and oil deposits put together methane extracted from methane hydrate is considered therefore a candidate for future fuels extraction of alkanes in ontario today the most import |
ant commercial sources for alkanes are clearly natural gas and oil which are the only organic compounds to occur as minerals in nature natural gas contains primarily methane and ethane with some propane and butane oil is a mixture of liquid alkanes and other hydrocarbons both were formed when dead marine animals and plants zooplankton and phytoplankton sank to the bottom of ancient seas and were covered with sediments in an anoxic environment ie lacking in oxygen and converted over many millions of years at high temperatures and high pressure to their current form natural gas resulted thereby for example from the following reaction c six h one two o six three ch four three co two these hydrocarbons collected in porous rocks trapped beneath an impermeable cap rock in contrast to methane which is constantly reformed in large quantities higher alkanes rarely develop to a considerable extent in nature the present deposits will not be reformed once they are exhausted solid alkanes occur as evaporation residues fro |
m oil known as tar one of the largest natural deposits of solid alkanes is in the asphalt lake known as the pitch lake in trinidad and tobago purification and use an oil refinery at martinez california alkanes are both important raw materials of the chemical industry and the most important fuels of the world economy the starting materials for the processing are always natural gas and crude oil the latter is separated in an oil refinery by fractional distillation and processed into many different products for example gasoline the different fractions of crude oil have different boiling points and can be isolated and separated quite easily within the individual fractions the boiling points lie closely together the domain of usage of a certain alkane can be determined quite well according to the number of carbon atoms although the following demarcation is idealized and not perfect the first four alkanes are used mainly for heating and cooking purposes and in some countries for electricity generation methane and e |
thane are the main componants of natural gas they are normally stored as gases under pressure it is however easier to transport them as liquids this requires both compression and cooling of the gas propane and butane can be liquefied at fairly low pressures and are well known as liquified petroleum gas lpg propane for example is used in the propane gas burner butane in disposable cigarette lighters where the pressure is a mere two bar the two alkanes are used as propellants in aerosol sprays from pentane to octane the alkanes are highly volatile liquids they are used as fuels in internal combustion engines as they vaporise easily on entry into the combustion chamber without forming droplets which would impair the unifomity of the combustion branched chain alkanes are preferred as they are much less prone to premature ignition which causes knocking than their straight chain homologues this propensity to premature ignition is measured by the octane rating of the fuel where two two four trimethylpentane isooctan |
e has an arbitrary value of one zero zero and heptane has a value of zero apart from their use as fuels the middle alkanes are also good solvents for nonpolar substances alkanes from nonane to for instance hexadecane an alkane with sixteen carbon atoms are liquids of higher viscosity less and less suitable for use in gasoline they form instead the major part of diesel and aviation fuel diesel fuels are charaterised by their cetane number cetane being an old name for hexadecane however the higher melting points of these alkanes can cause problems at low temperatures and in polar regions where the fuel becomes too thick to flow correctly alkanes from hexadecane upwards form the most important components of fuel oil and lubricating oil in latter function they work at the same time as anti corrosive agents as their hydrophobic nature means that water cannot reach the metal surface many solid alkanes find use as paraffin wax for example in candles this should not be confused however with true wax which consists pr |
imarily of esters alkanes with a chain length of approximately three five or more carbon atoms are found in bitumen used for example in road surfacing however the higher alkanes have little value and are usually split into lower alkanes by cracking preparation numerous ways exist to prepare alkanes in the laboratory the most well known methods are hydrogenation of alkenes and hydrolysis of grignard reagents alkanes can also be prepared directly from alkyl halides in the corey house posner whitesides reaction the barton mccombie deoxygenation removes hydroxyl groups from alcohols and the clemmensen reduction removes carbonyl groups from aldehydes and ketones to form alkanes molecular geometry sp three hybridisation in methane the molecular structure of the alkanes directly affects their physical and chemical characteristics it is derived from the electron configuration of carbon which has four valence electrons the carbon atoms in alkanes are always sp three hybridised that is to say that the valence electrons |
are said to be in four equivalent orbitals derived from the combination of the two s orbital and the three two p orbitals these orbitals which have identical energies are arranged spatially in the form of a tetrahedron the angle of one zero nine four seven between them bond lengths and bond angles an alkane molecule has only c h and c c single bonds the former result from the overlap of a sp orbital of carbon with the one s orbital of a hydrogen the latter by the overlap of two sp orbitals on different carbon atoms the bond lengths amount to one zero nine one zero one zero m for a c h bond and one five four one zero one zero m for a c c bond the tetrahedral structure of methane the spatial arrangement of the bonds is similar to that of the four sp orbitals they are tetrahedrally arranged with an angle of one zero nine four seven between them structural formulae which represent the bonds as being at right angles to one another while both common and useful do not correspond with the reality conformation the st |
ructural formula and the bond angles are not usually sufficient to completely describe the geometry of a molecule there is a further degree of freedom for each carbon carbon bond the torsion angle between the atoms or groups bound to the atoms at each end of the bond the spatial arrangement described by the torsion angles of the molecule is known as its conformation ethane ethane forms the simplest case for studying the conformation of alkanes as there is only one c c bond if one looks down the axis of the c c bond then one will see the so called newman projection the circle represents the two carbon atoms one behind the other and the bonds to hydrogen are represented by the straight lines the hydrogen atoms on both the front and rear carbon atoms have an angle of one two zero between them resulting from the projection of the base of the tetrahedron onto a flat plane however the torsion angle between a given hydrogen atom attached to the front carbon and a given hydrogen atom attached to the rear carbon can v |
ary freely between zero and three six zero this is a consequence of the free rotation about a carbon carbon single bond despite this apparent freedom only two limiting conformations are important newman projections of the two conformations of ethane eclipsed on the left staggered on the right in the eclipsed conformation corresponding to a torsion angle of zero one two zero or two four zero the hydrogen atoms attached to the front carbon are directly in front of those attached to the rear carbon in the staggered conformation corresponding to a torsion angle of six zero one eight zero or three zero zero the hydrogen atoms attached to the front carbon are exactly in between those attached to the rear carbon the two conformations also known as rotomers differ in energy the staggered conformation is one two six kj mol lower in energy more stable than the eclipsed conformation the explanation for this difference in energy has been the subject of debate with two main theories predominating in the eclipsed conformat |
ion the electrostatic repulsion between the electrons in the carbon hydrogen bonds is maximised in the staggered conformation the hyperconjugation a form of delocalisation of the valence electrons is maximised these two explanations are not contradictory or exclusive the latter is thought to be the more important for ethane itself this difference in energy between the two conformations known as the torsion energy is low compared to the thermal energy of an ethane molecule at ambient temperature there is constant rotation about the c c bond albeit with short pauses at each staggered conformation the time taken for an ethane molecule to pass from one staggered conformation to the next equivalent to the rotation of one ch three group by one two zero relative to the other is of the order of one zero one one seconds higher alkanes the four conformations of butane from left to right fully eclipsed inclined partially eclipsed antiperiplanar the situation with respect to the two c c bonds in propane is qualitatively |
similar to that of ethane it is more complex however for butane and higher alkanes if one takes the central c c bond of butane as the reference axis each of the two central carbon atoms is bound to two hydrogen atoms and a methyl group four different conformations can be defined by the torsion angle between the two methyl groups and as in the case of ethane each has its characteristic energy the fully eclipsed or synperiplanar conformation has a torsion angle of zero it is the configuration with the highest energy the inclined conformation has a torsion angle of six zero or three zero zero it is a local energy minimum the partially eclipsed conformation has a torsion angle of one two zero or two four zero it is a local energy maximum the antiperiplanar conformation has a torsion angle of one eight zero the two methyl groups are as far from each other as is possible and this configuration has the lowest energy the difference in energy between the fully eclipsed conformation and the antiperiplanar conformation |
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