AcharyaChanakya/simple-wikipedia huggingface dataset:
Birds that live in bushes and branches have triangular wings that help the bird change direction. Many forest birds are expert at getting up speed by flapping and then gliding steadily among the trees, tilting to avoid things as they go. Members of the kingfisher family are expert at this type of flying.
Birds such as owls that hunt at night have wings with soft rounded feathers so that they do not flap loudly. Birds that are awake at night are called "nocturnal" birds. Birds that are awake during the day are "diurnal".
A wandering albatross and Arctic tern might spend several years without coming to land. They can sleep while gliding and have wings which, when they are stretched right out, look like the wings of a jet plane.
Flocks of birds can be very highly organised in a way that takes care of all the flock members. Studies of small flocking birds like tree sparrows show that they clearly communicate with each other, as sometimes thousands of birds may fly in close formation and spiral patterns without colliding (or flying into each other).
Two common behaviours in flocking birds are guarding and reconnaissance. When a flock of birds is feeding it is common for one bird to perch on a high place to keep guard over the flock. In the same way, when a flock is asleep, often, one bird will remain awake. It is also common for large flocks to send one or two birds ahead of them when they are flying to a new area. The look-out birds can spy the lie of the land to find food, water and good places to perch.
Some birds do not fly. These include running birds like ostriches and emus and ocean-living birds, the large penguin family.
Ostriches and emus do not need to fly because although they feed and nest on the ground, their great size and their speed is their protection. Some other ground-feeding birds have not been so lucky. Some birds such as the dodo and the kiwi were ground-feeding birds that lived in safety on islands where there was nothing dangerous to eat them. They lost the power of flight. Kiwis are endangered because European settlement to New Zealand brought animals like cats, dogs and rats which kill kiwis and eat their eggs. However, kiwis and also the rare New Zealand ground parrot have survived. In the case of dodos, they were fat and delicious. They were killed and eaten by sailors until there was none left. Other flightless birds which have disappeared are the great auk and the moa.
Penguins spend a great deal of time at sea, where they are in danger from seals. On land, they usually live in areas where there were few dangers, until the arrival of European settlers with dogs and cats. Their wings have adapted to life in the sea and have become flippers which help them in swimming very fast.
Modern birds do not have teeth, and many swallow their prey whole. Nevertheless, they must break up food before it is digested. First of all, along their throat (oesophagus) they have a crop. This stores food items before digestion. That way a bird can eat several items, and then fly off to a quiet spot to digest them.
Their stomach comes next, with two very different parts. One part is like a straight hollow rod which secretes mild hydrochloric acid and an enzyme to break down protein. The other part of the stomach is the gizzard. This is muscular, and grinds up the contents. In herbivorous birds the gizzard contains some gastroliths (small stones or pieces of grit). Bones of fish will mostly be dissolved by the stomach acid. The partly digested and ground-up food now goes to the intestine, where digestion is completed, and most contents are absorbed. Anything indigestible, for example remains of feathers, is regurgitated via the mouth, not the cloaca.
The system is effective, and carnivorous birds can swallow quite large prey. A blue heron can swallow a fish as large as a carp successfully. Raptors eat by holding the prey down with a foot, and tearing it apart with their beak.
Although birds are warm-blooded creatures like mammals, they do not give birth to live young. They lay eggs as reptiles do, but the shell of a bird's egg is hard. The baby bird grows inside the egg, and after a few weeks hatches (breaks out of the egg).
Birds in cold climates usually have a breeding season once a year in the spring. Migratory birds can have two springs and two mating seasons in a year.
When the breeding season arrives, the birds choose partners.
Ninety-five per cent of bird species are socially monogamous. These birds pair for at least the length of the breeding season. In some cases this arrangement lasts until the death of one of the pair. Monogamy helps where females need males' help to raise a brood successfully.
Many birds mate for life, like married couples. These birds include pigeons, geese, and cranes. Other birds look for new partners each year.
For birds that choose new mates, part of the breeding season is display. The male bird will do all sorts of things to attract females. These include singing, dancing, showing off the feathers and building a beautiful nest. Some male birds have splendid feathers for attracting females. The most famous is the peacock who can spread the feathers above his tail into a huge fan.
Other mating systems do occur in some species. Polygyny, polyandry, polygamy, polygynandry, and promiscuity do happen. Polygamous breeding systems arise when females are able to raise broods without the help of males. Some species may use more than one system depending on the circumstances.
Once the birds have found partners, they find a suitable place to lay eggs. The idea of what is a suitable place differs between species, but most build bird nests. Robins will make a beautiful little round nest of woven grass and carefully line it with feathers, bits of fluff and other soft things. Swallows like to nest near other swallows. They make nests from little blobs of clay, often on a beam near the roof of a building where it is well sheltered. Many birds like a hollow tree to nest in. Eagle's nests are often just piles of dead wood on the top of the tallest tree or mountain. Scrub turkeys scratch together a huge pile of leaves that may be 10 metres across. Guillemots lay their eggs on rock shelves with no nest at all. Their eggs are shaped so that they roll around in circles and do not fall off cliffs. A cuckoo does not make its own nest. It lays its egg in the nest of another bird and leaves it for them to care for. The cuckoo eggs are camouflaged to look like the host's eggs.
When the nest has been prepared, the birds mate so that the eggs are fertilised and the chicks will start growing. Unlike mammals, birds only have one opening as the exit hole for body fluids, and for reproduction. The opening is called the cloaca. A female bird, called a hen, has two ovaries, of which the left one usually produces eggs.
Most male birds have no sex organs that can be seen. But inside the male are two testes which produce sperm which is stored in the cloaca. Birds mate by rubbing their cloacas together, although with some birds, particularly large water birds, the male has a sort of a penis inside the cloaca.
Once the hen has mated, she produces fertile eggs which have chicks growing inside them. She lays the eggs in the nest. There might be just one egg or a number of them, called a clutch. Emus might lay as many as fifteen huge dark green eggs in a clutch. After the eggs are laid, they are incubated, or kept warm so the chicks form inside. Most birds stay together for the whole nesting season, and one advantage is that the work is shared. Many birds take turns sitting on the eggs, so that each adult can feed.
This is not always the case. With emus, the male does all the sitting and all the baby-minding. With emperor penguins it is also the male that cares for the egg. There is only one egg, which he keeps on his feet and under his feathers, standing in a big group of males without feeding until the chick is hatched. While the eggs are hatching, the females are at sea, feeding, so that they can care for the chicks when they return.
Some birds put the eggs inside or on top of the mound of leaves and twigs. The mound acts like a compost heap. The decomposition of the rotting leaves causes the temperature to rise. This is heat released by the chemical action of bacterial and fungal respiration. It is the same reaction as that which keeps mammals and birds at a high temperature. The parents leave the mound. When the chicks hatch, they are able to feed themselves.
Many small birds take 2–4 weeks to hatch eggs. Albatrosses take 80 days. During this time the female loses a lot of her body weight.
The quickest hatching time is for the cuckoo. Some types of cuckoos take only 10 days. This means that when they hatch in the nest of their <nowiki>"foster parents"</nowiki>, the eggs that the parents have laid are not yet ready. Newborn cuckoos are naked, blind and ugly, but they are strong. They get under any eggs that are in the nest and throw them out before they hatch. That means that the cuckoo has the whole care of both parents. Baby cuckoos grow fast and often get bigger than the parents who feed them.
When baby birds hatch, in most types of birds, they are fed by both parents, and sometimes by older aunties as well. Their mouths are open all the time and are often very brightly coloured, which acts as a ''releaser<nowiki>"</nowiki>, a trigger which stimulates the parent to feed them. For birds that eat grain and fruit, the parents eat and partly digest the food for the babies. It is then vomited carefully into the baby's mouth.
Many birds, particularly those that mate for life, are very sociable and keep together in a family group which might be anything from 4 or 6 adult birds and their young to a very large flock.
As chicks grow they change the fluffy down that covers them as babies for real feathers. At this stage they are called fledglings. Other family members may help care for fledgling chicks, feeding them and protecting them from attack while parents are feeding. When the fledglings have their new feathers, they come out of the nest to learn to fly. In some types of birds, like pigeons, the parents watch over this and as the young ones get stronger, will give them flying lessons, teaching them how to glide, how to fly in spirals and how to land like an expert.
Most birds are social animals, at least part of the time. They communicate to each other using sounds and displays.
Almost all birds make sounds to communicate. The types of noises that vary greatly. Some birds can sing, and they are called songbirds or passerines. Examples are robins, larks, canaries, thrushes, nightingales. Corvids are passerines, but they do not sing. Birds that are not songbirds include: pigeons, seagulls, eagles, owls and ducks. Parrots are not songbirds, even though they can be taught to sing human songs.
All birds make noises (<nowiki>"bird vocalisation"</nowiki>), but not all sing. Songbirds are passerines, many of which have beautiful melodic songs. Songs have different functions. Danger cries are different from territorial songs and mating calls are a third type. Fledgling may also have different calls from adults. Recognition calls for partners are quite common.
As to where the song comes from, there are three kinds of species:
Most singing birds that are kept as pets, like canaries, have several tunes and some variations.
The same species of bird will sing different songs in different regions. A good example of this is the currawong. This is an Australia bird which is like a black and white crow. In the autumn, families get together in large flocks and do a lot of singing. Currawongs from some areas sing much more complex songs than others. Generally, currawongs from the Blue Mountains are the finest singers. The song of the currawong can be sung as a solo, but is often performed as a choir. One bird will take the lead and sing "Warble-warble-warble-warble!" All the other birds will join in and sing "Wooooooo!". When all the birds know the song, the choir will sing the "Warble" part and the soloist will sing the "Woo!". The song changes from year to year and from place to place.
The Austrian naturalist Konrad Lorenz studied the way in which birds communicate, or talk to each other. He found that each type of bird had a number of sounds which they made automatically, when ever they felt a certain way. Every sound had an action that went with it. So, if the bird was frightened, it acted frightened and made a frightened sound. This told the other birds around it that something frightening was happening.
If a flock of birds were flying over a field, they would be calling "Fly! Fly!" But a hungry bird, seeing something good to eat down below might start calling "Food! Food!" If other birds were also hungry, they would make the same call until more birds were calling "Food! Food!" than "Fly! Fly!". At this point, the mind of the flock would be changed. Some of the birds would start to yell "Fly downwards! Fly downwards!" as they sank from the sky, until the whole flock was all noisily calling the same thing.
These communication sounds are often short hard sounds like: chirps, squeaks, squawks and twitters. Sometimes the calls are longer and more musical. They include the "Rookety-coo" sound of a pigeon and the "Cockadoodledoo!" of a rooster. The bird cannot change these sounds. They always make them in the same way. The bird is locked into making each sound every time a particular idea comes into its head. The connection between how they feel and how they call is innate: they are born with it. Some calls in some species are learnt. Then, it is the tendency to learn which is inherited.
Konrad Lorenz noticed that when birds sing, they often use a lot of their regular calls as part of the song. Lorenz had a flock of jackdaws which were scattered during World War II. One day, an old bird returned. For many months she sat on the chimney singing her song, but in the song she kept making the call which Lorenz knew meant "Come home! Come home!" One day, to the great surprise of Lorenz, a male bird flew from a passing flock and joined her on the chimney. Lorenz was sure that it was her long-lost "husband" who had found his way home at last.
Palaeontologists have found some exceptional places (lagerstätten) where fossils of early birds are found. The preservation is so good that on the best examples impressions of their feathers can be seen, and sometimes even the remains of meals they have eaten. From these remains we know that birds evolved from small carnivorous dinosaurs (theropods) in the Jurassic period. They radiated into a huge variety in the Lower Cretaceous. At the same time, their direct competitors, the pterosaurs, dwindled in numbers and variety, and became extinct at the end of the Mesozoic.
Birds are classified by taxonomists as 'Aves' (Avialae). Birds are the only living descendants of dinosaurs (strictly speaking, they "are" dinosaurs). Birds and Crocodilia are the only living members of the once-dominant Archosaur reptiles.
The class Aves is now defined as all the descendants of the most recent common ancestor of modern birds and "Archaeopteryx lithographica".
"Archaeopteryx", from the Upper Jurassic some 150–145 million years ago (mya), was for a long time the earliest known bird which could fly. It is famous, because it was one of the first important fossils found after Charles Darwin published his ideas about evolution in the 19th century. By modern standards, "Archaeopteryx" could not fly very well. Other early fossil birds are, for example, "Confuciusornis", "Anchiornis huxlei" and other Paraves.
Many fossils of early birds and small dinosaurs have been discovered in the Liaoning Province of Northeast China. These include "Anchiornis huxlei", from about 160 mya. The fossils show that most small theropod dinosaurs had feathers. These deposits have preserved them so well that the impressions of their feathers can be clearly seen. This leads us to think that feathers evolved first as heat insulation and only later for flight. The origin of birds lies in these small feathered dinosaurs.
Palaeontologists now agree that birds are included in Maniraptora group of dinosaurs. This explains why we say that birds are living dinosaurs.
Some birds are eaten as food. Most usually it is the chicken and its eggs, but people often also eat geese, pheasants, turkeys and ducks. Other birds are sometimes eaten are: emus, ostriches, pigeons, grouse, quails, doves, woodcocks and even songbirds. Some species have died out because they have been hunted for food, for example the dodo and the passenger pigeon.
Many species have learned how to get food from people. The number of birds of these species has grown because of it. Seagulls and crows find food from garbage dumps. The feral pigeon ("Columba livia"), sparrows ("Passer domesticus" and starlings ("Sturnus vulgaris") live in large numbers in towns and cities all over the world.
Sometimes people also use working birds. For example, homing pigeons carry messages. Nowadays people sometimes race them for sport. People also use falcons for hunting, and cormorants for fishing. In the past, people in mines often used a canary to see if there were bad gas methane in the air.
People often have colorful birds such as parrots and mynahs as pets. These intelligent birds are popular because they can copy human talking. Because of this, some people trap birds and take them to other countries to sell. This is not usually allowed these days. Most pet birds are specially bred and are sold in pet shops.
People can catch some bird diseases, for example: "psittacosis", "salmonellosis", "campylobacteriosis", Newcastle's disease, "mycobacteriosis", influenza, "giardiasis" and "cryptosporiadiosis". In 2005, there was an epidemic of bird influenza spreading through some parts of the world, often called avian flu.
Some people have birdboxes in their gardens to give birds a place to nest and bird tables where birds can get food and water in very cold or very dry weather. This lets people see some small birds close up which are normally hidden away in bushes and trees.
The following is a listing of all bird orders:
A report produced by BirdLife International every five years measures the population of birds worldwide. In 2018 the number of bird species has decreased by 40%. One in every eight types of birds is now almost extinct.
Freedom of speech is the right to state one's opinions and ideas without being stopped or punished. Sometimes this is also called Freedom of expression. Freedom of speech is thought to also include Freedom of information. However, new laws are usually needed to allow information to be used easily.
Most people think freedom of speech is necessary for a democratic government. In countries without free speech, people might be afraid to say what they think. Then, the government does not know what the people want. If the government does not know what they want, it cannot respond to their wants. Without free speech, the government does not have to worry as much about doing what the people want. Some people say this is why some governments do not allow free speech: they do not want to be criticised, or they fear there would be revolution if everyone knew everything that was happening in the country.
A well-known liberal thinker, John Stuart Mill, believed that freedom of speech is important because the society that people live in has a right to hear people's ideas. It's not just important because everyone should have a right to express him or herself.
Few countries with "free speech" let everything be said. For example, the United States Supreme Court said that it was against the law to shout "fire" in a crowded theater if there is no fire, because this might cause people to panic. The International Covenant on Civil and Political Rights also says that it is not okay to cause national, racial or religious hatred. Also, some countries have laws against hate speech.
As Tocqueville pointed out, people may be hesitant to speak freely not because of fear of government punishment but because of social pressures. When an individual announces an unpopular opinion, he or she may face the disdain of their community or even be subjected to violent reactions. While this type of suppression of speech is even more difficult to prevent than government suppression is, there are questions about whether it truly falls within the ambit of freedom of speech, which is typically regarded as a legal right to be exercised against the government, or immunity from governmental action.
A banana is the common name for a type of fruit and also the name for the herbaceous plants that grow it. These plants belong to the genus "Musa". They are native to the tropical region of southeast Asia.
It is thought that bananas were grown for food for the first time in Papua New Guinea. Today, they are cultivated in tropical regions around the world. Most banana plants are grown for their fruits, which botanically are a type of berry. Some are grown as ornamental plants, or for their fibres.
There are about 110 different species of banana. In popular culture and commerce, "banana" usually refers to the soft and sweet kind, also known as "dessert bananas". Other kinds, or cultivars, of banana have a firmer, starchier fruit. Those are usually called plantains. Plantains are mostly used for cooking or fibre.
Other than being used as food, beer can be made by fermenting the juice of certain cultivars in Africa, known as "beer bananas". The ash of bananas can be used to make soap. In Asia, bananas are often planted to provide shade to plants that like shade, for example coffee, cocoa, nutmeg or black pepper. Because of this, banana plants can often be found in plantations of other crops.
The banana plant is the largest herbaceous flowering plant. Banana plants are often mistaken for trees. Bananas have a "false stem" (called "pseudostem"), which is made by the lower part of the leaves. This pseudostem can grow to be two to eight meters tall. Each pseudostem grows from a corm. A pseudostem is able to produce a single bunch of bananas. After fruiting, the pseudostem dies and is replaced. When most bananas are ripe, they turn yellow or, sometimes, red. Unripe bananas are green.
Banana leaves grow in a spiral and may grow long and wide. They are easily torn by the wind, which results in a familiar, frayed look.
The banana fruits grow from a banana blossom in hanging clusters, also called a "bunch" or "banana stem". The fruits grow in rows called "tiers" or "hands". There can be as many as twenty fruits to a hand, and as many as twenty tiers in a bunch. A bunch usually weighs between 30 and 50 kilograms (65 to 110 pounds).
A single fruit weighs about 125 grams (4.4 ounces) on average; about three quarters of this is water.
Each banana (or "finger") has a protective outer layer (called "peel" or "skin"). There is a fleshy part inside that readily spilts into three segments. It is the only known tri-segmented fruit in the world. Both the skin and inner part can be eaten. Western cultures generally eat the inside raw and throw away the skin. Some Asian cultures eat both the skin and the inside cooked. Each fruit has many "strings" that run between the skin and the inner part.
Bananas have a lot of vitamin B, vitamin C, and potassium.
Bananas are grown in at least 107 countries. The banana species growing in the wild have fruits with many hard, large seeds, but almost all bananas grown to be eaten have seedless fruits. Bananas are classified either as dessert bananas or as green cooking bananas. Almost all export bananas are of the dessert types. Only about ten to fifteen percent of all production is for export. Dessert bananas change their color and usually turn yellow, when they are ripe; plantains and bananas generally used for cooking stay green. Certain bananas have other colors when ripe.
The countries that produce the most bananas include India, Brazil, China, Ecuador and the Philippines. The top five countries that exported bananas were Ecuador, Costa Rica, the Philippines, Colombia and Guatemala. The United States, the European Union and Japan buy the most bananas. Bananas are among the most valuable agricultural export products; They provided about sixty percent of export earnings of Saint Lucia and about twelve percent of the Gross Domestic Product of the country, between 1994 and 1996.
Some people are allergic to bananas. There are two basic forms of these allergies. The first is known as oral allergy syndrome. Within an hour of eating a banana, swelling starts inside the mouth or throat. This allergy is related to allergies caused by pollen, like that of the birch tree. The other is similar to latex allergies. It causes urticaria and potentially serious upper gastrointestinal symptoms.
The fibre gained from the banana plant has been used to make textiles for a long time. In Japan, bananas have been grown to be used for clothing and in the house since at least the 13th century. In the Japanese system, the leaves and shoots are cut from the plant periodically to make sure they are soft. The harvested shoots must first be boiled in lye to prepare the fibres for the making of the yarn. These banana shoots produce fibres of varying degrees of softness. They can be used for yarns and textiles of different qualties, and for specific uses. For example, the outermost fibres of the shoots are the coarsest - they are good for tablecloths. The softest innermost fibres are desirable for kimono and kamishimo. This traditional Japanese banana cloth making process has many steps, all performed by hand.
Another system is used in Nepal. There the trunk of the banana plant is harvested instead. Small pieces of this trunk are then softened. The fibres are extracted mechanically, bleached, and dried. They are then sent to the Kathmandu Valley, where high-end rugs are produced. These rugs have a texture and general qualities similar to that of silk. These banana fibre rugs are woven by traditional Nepalese hand-knotted methods.
A medium-sized banana will provide around 320–400 mg of potassium, which meets about 10% of your daily potassium needs. Potassium helps your body maintain a healthy heart and blood pressure. In addition, bananas are low in sodium. The low sodium and high potassium combination helps to control high blood pressure.
Banana fiber is also used to make "banana paper". There are two different kinds of banana paper: paper made from the bark, and paper made from the fibre and from unused fruits.
Biel/Bienne, Switzerland
Biel/Bienne (official name; "Biel" is German, "Bienne" is French) is an industrial town in Switzerland. It is in the part of Switzerland named Bern and near the city also named Bern. The town is known for many companies that make watches and machines.
The town of Biel, the capital of Swiss watch-making, lies at the end of Lake Biel, at the foot of the Jura Hills in the Lake Region.
The wonderful old town with its town church and its location as the gateway to the three Jura lakes (Lakes Biel, Lake Neuchâtel and Lake Murten) with vineyards on the hillsides and extensive vegetable cultivation make the town very attractive.
Biel is the only town in Switzerland in which German and French are spoken side by side We can feel the relaxed mentality here coming from the mixture of these three languages.
Biel was awarded the Wakker Prize in 2004 by the Swiss Heritage Society for the way it conserved its 20th century buildings, especially the ‘new construction’ from the 1920s and 30s.
Swatch, Rolex, Omega, Tissot, Movado and Mikron all come from this town. But Biel has also become important in the field of other industries and in communication.
It is possible to travel on various routes along the lakes on passenger boats in summer. The day trip through all three Jura lakes is especially popular. Of course there are all types of water sports on Lake Biel.
The town of Biel was built by the Prince-Bishop of Bale between 1220 and 1230. The old town is the smallest part of Biel with only . Most buildings there still look as in the 18th century. The biggest part of the old town is without any traffic. There aren’t any big stores or industries or any big companies. Each Saturday there is a market. The castle, “the ring” and the theatre are very popular. The town church is on the “Ringplatz” and was built between 1451 and 1470.There they burned the witches in the 18th century. From the 6 medieval city gates only one and two towers survived.
The entire town of Biel is part of the Inventory of Swiss Heritage Sites. Several individual buildings in the old town have also been protected for their cultural heritage.
The Reformed City Church is one of the most important late-Gothic buildings in the Canton of Bern. The church has a main floor, two second floors and four small chapels. There are some wall-paintings in the church. Most windows are among the oldest ones in Switzerland. The church was first written about in an index in 1228. After a horrible fire in the old town the church was destroyed. It was rebuilt between 1367 and 1451. The town church got on a new organ on 6th November 2011. The church was closed for more than half a year to put the new organ in and to improve the inside of the church. It cost about 1,74 million Swiss francs. The old organ was sent to Poland.
About 57% of the people in Biel speak German as their mother tongue. The remaining 43% speak French as their mother tongue. That is why the city has two names.
Test tube
A test tube is a kind of laboratory glassware, composed of a fingerlike length of glass tubing, open at the top, usually with a rounded lip at the top, and a rounded 'U' shaped bottom.
They range in size from a couple inches to several inches long, from a few millimeters to a couple centimeters in diameter. They are designed to allow easy heating of samples, to be held in a flame, and often are made of expansion-resistant glasses, such as borosilicate glass (known by brand-names such as Pyrex and Kimax).
Tests tubes are often preferred above beakers when multiple small chemical or biological samples have to be handled and/or stored.
Vacutainers are a type of test tube that can be used for both collection and storage of blood.
A beaker is a kind of laboratory glassware. A beaker is a cylinder with a lip and a spout (a bend in the rim of the beaker which makes it easier to pour liquids without spilling any). A beaker is usually about the same width as its height. This makes beakers very stable and easy to handle. They may be made of plastic, glass, or borosilicate glass. Some beakers have marks on them to show about how much volume of liquid they hold - these can not be used for exact measurements.
Beakers are often used to make solutions and they are probably the most used piece of laboratory glassware.
Lithium (from Greek "lithos" 'stone') is a soft, silver-white metal with symbol Li. It is the third chemical element in the periodic table. This means that it has 3 protons in its nucleus and 3 electrons around it. Its atomic number is 3. Its mass number is 6.94. It has two common isotopes, Li and Li. Li is more common. 92.5% of lithium is Li. Lithium is a soft silvery metal that is very reactive. It is used in lithium batteries and certain medicines.
Lithium is one of the alkali metals. Lithium is a silvery solid metal (when freshly cut). It is very soft. Thus it can be cut easily with a knife. It melts at a low temperature. It is very light, similar to wood. It is the least dense metal and the least dense element in a solid or liquid state. It can hold more heat than any other solid element. It conducts heat and electricity easily.
It will react with water, giving off hydrogen to form a basic solution (lithium hydroxide). Because of this, lithium must be stored in petroleum jelly. Sodium and potassium can be stored in oil but lithium cannot because it is so light. It will just float on the oil and not be protected by it.
Lithium also reacts with halogens. It can react with nitrogen gas to make lithium nitride. It reacts with air to make a black tarnish and then a white powder of lithium hydroxide and lithium carbonate.
Lithium forms chemical compounds with only one oxidation state: +1. Most of them are white and unreactive. They make a bright red color when heated in a flame. They are a little toxic. Most of them dissolve in water. Lithium carbonate is less soluble in water than the other alkali metal carbonates like sodium carbonate.
It does not occur as an element in nature. It only is in the form of lithium compounds. The ocean has a large amount of lithium in it. Certain granites have large amounts of lithium. Most living things have lithium in them. There are some places where much lithium is in the salt. Some silicates have lithium in them.
Lithium (Greek "lithos", meaning "stone") was discovered by Johann Arfvedson in 1817. In 1818, Christian Gmelin observed that lithium salts give a bright red color in flame. W.T. Brande and Sir Humphrey Davy later used electrolysis on lithium oxide to isolate the element. Lithium was first used in greases. Then nuclear weapons became a big use of lithium. Lithium was also used to make glass melt easier and make aluminium oxide melt easier in making aluminium. Now lithium is used mainly in batteries.
It was apparently given the name "lithium" because it was discovered from a mineral, while other common alkali metals were first discovered in plant tissue.
It is made by getting lithium chloride from pools and springs. The lithium chloride is melted and electrolyzed. This makes liquid lithium and chlorine.
Its main use is in batteries. Lithium is used as an anode in the lithium battery. It has more power than batteries with zinc, like alkaline cells. Lithium ion batteries also have lithium in them, though not as an element. It is also used in heat transfer alloys. Lithium is used to make organolithium compounds. They are used for very strong bases.
It is used to make special glasses and ceramics, including the Mount Palomar telescope's 200 inch mirror. Lithium is the lightest known metal and can be alloyed with aluminium, copper, manganese, and cadmium to make strong, lightweight metals for aircraft.
Lithium compounds are used in some drugs known as mood stabilizers. Lithium niobate is used in radio transmitters in cell phones. Some lithium compounds are also used in ceramics. Lithium chloride can absorb water from other things. Some lithium compounds are used to make soap and grease. Lithium carbonate is used as a drug to treat manic depression disorder. Lithium carbonate is used for the treatment of bipolar disease and other mental illness conditions.
Organolithium compounds are used to make polymers and fine chemicals. Many lithium compounds are used as reagents to make organic compounds. Some lithium compounds like lithium aluminium hydride, lithium triethylborohydride, n-butyllithium and tert-butyllithium are commonly used as very strong bases called superbases.
Lithium compounds are used as pyrotechnic colorants and oxidizers in red fireworks and flares. Lithium chloride and lithium bromide are used as desiccants for gas streams. Lithium hydroxide and lithium peroxide are used to remove carbon dioxide and purify the air in spacecrafts and submarines. Lithium hydroxide, lithium peroxide and lithium perchlorate are used in oxygen candles that supply submarines with oxygen.
Lithium aluminum hydride can also be used as a solid fuel by itself. Lithium hydride that contains lithium-6 is used in thermonuclear weapons.
Lithium reacts with water, making irritating smoke and heat. It is not as dangerous as the other alkali metals. Lithium hydroxide is very corrosive.
There are 5 isotopes of Lithium having respectively 2, 3, 4, 5 and 6 neutrons in the nucleus. The most common isotope in nature is Li which makes up 92.58 % of the total. The second isotope which is widely available is Li which makes up 7.42 % of the total. The other 3 isotopes exist in very small quantities. The atomic mass of Lithium is 6.939.
Beryllium is in group 2 of the periodic table, so it is an alkaline earth metal. It is grayish (slightly gray) in color. It has an atomic number of 4 and is symbolized by the letters Be. It is toxic and should not be handled without proper training.
Beryllium has 4 electrons, 4 protons, and 5 neutrons.
Beryllium has one of the highest melting points of the light metals: 1560 K (1287 °C). It is added to other metals to make stronger alloys. Beryllium-copper alloy is used in tools because it does not make sparks.
At standard temperature and pressure, beryllium resists oxidation when exposed to oxygen.
Beryllium is best known for the chemical compounds it forms. Beryllium combines with aluminium, silicon and oxygen to make a mineral called beryl. Emerald and aquamarine are two varieties of beryl which are used as gemstones in jewelry.
Since it has a very high stiffness to weight ratio, beryllium is used to make the diaphragms in some high-end speakers.
Beryllium is used to make jet aircrafts, guided missiles, spacecraft, and satellites, including the James Webb telescope. Beryllium can reflect neutrons, and thin foils of beryllium are sometimes used in nuclear weapons as the outer layer of the plutonium pits. Beryllium is also used in fuel rods for CANDU reactors. Beryllium is used to make many dental alloys.
It is a relatively rare element in the universe. It usually occurs when larger atomic nuclei have split up. In stars, beryllium is depleted because it is fused and builds larger elements.
Data compression is a set of steps for packing data into a smaller space, while allowing for the original data to be seen again. Compression is a two-way process: a compression algorithm can be used to make a data package smaller, but it can also be run the other way, to decompress the package into its original form. Data compression is useful in computing to save disk space, or to reduce the bandwidth used when sending data (e.g., over the internet).
Lossless compression packs data in such a way that the compressed package can be decompressed, and the data can be pulled out exactly the same as it went in. This is very important for computer programs and archives, since even a very small change in a computer program will make it unusable.
This type of compression works by reducing how much waste space is in a piece of data. For example, if you receive a data package which contains "AAAAABBBB", you could compress that into "5A4B", which has the same meaning but takes up less space. This type of compression is called "run-length encoding", because you define how long the "run" of a character is. In the above example, there are two runs: a run of 5 A's, and another of 4 B's.
The problem with run-length encoding is that it only works on long pieces of the same value of data. If you receive a package with "ABBAABAAB" inside, that can be compressed into "1A2B2A1B2A1B"; but that's longer than the original! In this case, there's another method that can be used: checking how often a particular value comes up in the whole data package. This is often called frequency compression.
The most common kind of frequency compression is called Huffman coding, after the scientist who came up with the idea. The basic plan is to give each distinct value in a piece of data a code:- values that crop up all the time get shorter codes, and values that only show up once or twice get longer codes.
For some types of data, lossy compression can go much further; this is most often the case with media files, like music and images. Lossy compression loses some of the data so that there's less to store. Depending on what information is lost, people do not notice it is missing. As a result, it can simply be removed from the data.
Of course, this will not work for computer programs and other such data where every piece is important; throwing away pieces of a computer program is generally unhealthy for the program.
A compiler is a computer program that translates computer code written in one programming language into another programming language. The first language is called the source language, and the code is called source code. The second language is called the target and can usually be understood by computers. In that case, the instructions become machine code.
If a compiler can convert the same instruction text into machine code for different computers (like smartphones or video game machines), it is a 'cross-compiler'. If the compiler can make instruction text that is easier for people to read, it is a 'de-compiler'. People who write these instructions are called programmers. Some even made programs that can translate the instructions that describe how a compiler should work, into a compiler. That kind of program is called a compiler-compiler.
A compiler usually has three steps. It reads the text and makes notes about how the words and sentences go together. If the words don't make sense, it will try to tell the programmer. Then it will use what it knows about the target language to make the instructions fit better. It then writes down the instructions in the target language. If the source instructions are on different pages, it may have to compile several before it can write everything down.
A compiler has six parts :
The first piece, a lexical analyzer, reads a page of instruction text and splits it into words and sentences. It also marks the type for each word. For example, a word may be number, a variable, a verb, a math sign, or an adjective. The output of a lexical analyzer is a list of tokens.
A parser reads in the output of the lexical analyzer, and verifies the syntax of the language. If the input program is syntactically incorrect or has a type error, it generates errors and warnings. This is called semantic analysis. For example, the parser might complain about the example above, if it "had not" already seen codice_3 with its type adjective. The parser uses all the information to make a structure typically called an Abstract Syntax Tree (AST).
`( sentence
The next piece, an optimizer rearranges the tree structure so the target language is optimized. 'Optimized' includes using fewer instructions to perform the same work. This could be important if the final program needs to check a lot of data. (Like seeing how many people, in the whole country, are fifty years old "and" buy medicine.) An 'optimized' result might also mean breaking long instructions into smaller ones. Unused and unaccessible code will be removed at this step.
A programmer usually tries to write instructions in small, related groups. That way, they can keep track of fewer changes in the program. But, that means the code may go on several pages. When a compiler sees that the target program uses several pages to explain the whole recipe, it may use a linker. The linker will put instructions that say where to find the code that's next. Finally, the compiler writes down the instructions in the target language.
ADD 0, 5, spot_1
LOAD location_y, , spot_2
ADD spot_1, spot_2, spot_3
SAVE spot_3, , location_x
Programmers who write compiler code try to make it as perfect as possible. If the programmer writes incorrect code, the compiler informs of them an error, but if the compiler code itself contains errors, it may be hard to tell where exactly the problem lies.
At the end of each compilation step the partial finished product could be stored and then only processed later on. A language like Java uses this successfully, where they lack the final translation step to instructions the processor understands. They only do the final translation step once the Java program is running on a computer. This is either called "interpreting" or "JIT"ting, depending on the technique used.
For example, the source code might contain an equation, such as "x = 5*10 ". The lexical analyzer would separate each number and symbol (such as "*" or "+") into separate tokens. The parser would note the pattern of tokens, as being an equation. The intermediate-code generator would write a form of coding which defines a storage variable named "x" and assigns the numerical product of 5*10 plus 6 and 1. The optimizer would simplify the calculation, of 5*10+6+1, as being just 57. Hence, the target machine-code generator would set a variable named "x" and put the value 57 into that storage place in the computer's memory, using the instructions of whichever computer chip is being used.
The eye is a round organ for sensing light so organisms can see. It is the first part of the visual system. About 97 percent of animals have eyes. Image-resolving eyes are present in cnidaria, molluscs, vertebrates, annelids and arthropods.
In mammals, two kinds of cells, "rods" and "cones", allow sight by sending signals through the optic nerve to the brain.
Some animals can see light that humans cannot see. They can see ultraviolet or infrared light.
The "lens" on the front part of the eye acts like a camera lens. It can be pulled flatter by muscles inside the eye, or allowed to become rounder. As some people get older, they may not be as able to do this perfectly. Many people are born with other small problems or get them later in life, and they may need eyeglasses (or "contact lenses") to fix the problem.
Like different cameras, different eyes have different abilities. They may have higher or lower resolution, the ability to detect small details. They may have different performance in low light; nocturnal animals can see better at night than daytime animals. They may have different ability to distinguish colors.
The human eye is composed of several different parts. These parts may or may not be the same in other animals. They are:
Today, ten different types of eyes are known. Most ways of capturing an image have evolved at least once.
One way to categorize eyes is to look at the number of "chambers". "Simple eyes" are made of only one concave chamber, perhaps with a lens. Compound eyes have many such chambers with their lenses on a convex surface.
Eyes also can be grouped according to how the photoreceptor is made. Photoreeptors are either cillated, or rhabdomic. and some annelids possess both.
Pit eyes are set in a depression in the skin. This reduces the angles at which light can enter. It allows the organism to say where the light is coming from.
Such eyes can be found in about 85% of phyla. They probably came before the development of more complex eyes. Pit eyes are small. They are made of up to about hundred cells, covering about 100 µm. The directionality can be improved by reducing the size of the opening, and by putting a reflective layer behind the receptor cells.
The pinhole eye is an advanced form of pit eye. It has several bits, most notably a small aperture and deep pit. Sometimes, the aperture can be changed. It is only found in the "Nautilus". Without a lens to focus the image, it produces a blurry image. Consequently, nautiloids can not discriminate between objects with a separation of less than 11°. Shrinking the aperture would produce a sharper image, but let in less light.
The resolution of pit eyes can be improved a lot by adding a material to make a lens. This will reduce the radius of the blurring, and increase the resolution that can be achieved. The most basic form can still be seen in some gastropods and annelids. These eyes have a lens of one refractive index. It is possible to get a better image with materials that have a high refractive index which decreases towards the edges. This decreases the focal length and allows a sharp image to form on the retina.
This eye creates an image that is sharp enough that motion of the eye can cause significant blurring. To minimize the effect of eye motion while the animal moves, most such eyes have stabilizing eye muscles.
The ocelli of insects have a simple lens, but their focal point always lies behind the retina.They can never form a sharp image. This limits the function of the eye. Ocelli (pit-type eyes of arthropods) blur the image across the whole retina. They are very good at responding to rapid changes in light intensity across the whole visual field — this fast response is accelerated even more by the large nerve bundles which rush the information to the brain. Focusing the image would also cause the sun's image to be focused on a few receptors. These could possibly be damaged by the intense light; shielding the receptors would block out some light and reduce their sensitivity.
This fast response has led to suggestions that the ocelli of insects are used mainly in flight, because they can be used to detect sudden changes in which way is up (because light, especially UV light which is absorbed by vegetation, usually comes from above).