Posts by Jai Ganesh

Jai Ganesh · Dark Discussions at Cafe Infinity

2420) Peter Medawar

Gist:

Work

Our immune system protects us against attacks by microorganisms and rejects foreign tissue. Part of our immunity has a hereditary basis, but part of it is acquired and is not present in the fetus. After Macfarlane Burnet theorized that the ability to distinguish between one’s own and foreign tissue is acquired during the fetus stage, Peter Medawar successfully transplanted tissue between mouse fetuses without rejection in 1951. He could perform new transplants on the mice when they became adults, something that did not work when the transplants were not performed during the fetus stage. The results had significance for organ transplants.

Summary

Sir Peter B. Medawar (born Feb. 28, 1915, Rio de Janeiro, Brazil—died Oct. 2, 1987, London, Eng.) was a Brazilian-born British zoologist who received, with Sir Frank Macfarlane Burnet, the Nobel Prize for Physiology or Medicine in 1960 for developing and proving the theory of acquired immunological tolerance, a model that paved the way for successful organ and tissue transplantation.

Medawar was born in Brazil and moved to England as a young boy. In 1935 he took a degree in zoology from Magdalen College, Oxford, and in 1938 he became a fellow of the college. During World War II at the Burns Unit of the Glasgow Royal Infirmary in Scotland, he carried out research on tissue transplants, particularly skin grafting. That work led him to recognize that graft rejection is an immunological response. After the war, Medawar continued his transplant research and learned of the work done by Australian immunologist Frank Macfarlane Burnet, who first advanced the theory of acquired immunological tolerance. According to that hypothesis, during early embryological development and soon after birth, vertebrates develop the ability to distinguish between substances that belong to its body and those that are foreign. The idea contradicted the view that vertebrates inherit this ability at conception. Medawar lent support to Burnet’s theory when he found that fraternal cattle twins accept skin grafts from each other, indicating that certain substances known as antigens “leak” from the yolk sac of each embryo twin into the sac of the other. In a series of experiments on mice, he produced evidence indicating that, although each animal cell contains certain genetically determined antigens important to the immunity process, tolerance can also be acquired because the recipient injected as an embryo with the donor’s cells will accept tissue from all parts of the donor’s body and from the donor’s twin. Medawar’s work resulted in a shift of emphasis in the science of immunology from one that assumed a fully developed immune mechanism to one that attempts to alter the immune mechanism itself, as in the attempt to suppress the body’s rejection of organ transplants.

Medawar was professor of zoology at the University of Birmingham (1947–51) and University College, London (1951–62), director of the National Institute for Medical Research, London (1962–71), professor of experimental medicine at the Royal Institution (1977–83), and president of the Royal Postgraduate Medical School (1981–87). He was knighted in 1965 and awarded the Order of Merit in 1981.

Medawar’s works include The Uniqueness of the Individual (1957), The Future of Man (1959), The Art of the Soluble (1967), The Hope of Progress (1972), The Life Science (1977), Pluto’s Republic (1982), and his autobiography, Memoir of a Thinking Radish (1986).

Details

Sir Peter Brian Medawar (28 February 1915 – 2 October 1987) was a British biologist and writer, whose works on graft rejection and the discovery of acquired immune tolerance have been fundamental to the medical practice of tissue and organ transplants. For his scientific works, he is regarded as the "father of transplantation". He is remembered for his wit both in person and in popular writings. Richard Dawkins referred to him as "the wittiest of all scientific writers"; Stephen Jay Gould as "the cleverest man I have ever known".

Medawar was the youngest child of a Lebanese father and a British mother, and was both a Brazilian and British citizen by birth. He studied at Marlborough College and Magdalen College, Oxford, and was professor of zoology at the University of Birmingham and University College London. Until he was partially disabled by a cerebral infarction, he was Director of the National Institute for Medical Research at Mill Hill. With his doctoral student Leslie Brent and postdoctoral fellow Rupert E. Billingham, he demonstrated the principle of acquired immunological tolerance (the phenomenon of unresponsiveness of the immune system to certain molecules), which was theoretically predicted by Sir Frank Macfarlane Burnet. This became the foundation of tissue and organ transplantation. He and Burnet shared the 1960 Nobel Prize in Physiology or Medicine "for discovery of acquired immunological tolerance".

Early life and education

Medawar was born in Petrópolis, a town 40 miles north of Rio de Janeiro, Brazil, where his parents were living. He was the third child of Lebanese Nicholas Agnatius Medawar, born in the village of Jounieh, north of Beirut, Lebanon, and British mother Edith Muriel (née Dowling). He had a brother Philip and a sister Pamela. (Pamela was later married to Sir David Hunt, who served as Private Secretary to prime ministers Clement Attlee and Winston Churchill.) His father, a Maronite Catholic, became a naturalised British citizen and worked for a British dental supplies manufacturer that sent him to Brazil as an agent. He later described his father's profession as selling "false teeth in South America". His status as a British citizen was acquired at birth, as he said, "My birth was registered at the British Consulate in good time to acquire the status of 'natural-born British subject'."

Medawar left Brazil with his family for England at the end of World War I, in 1918 and he lived there for the rest of his life. According to other accounts, he moved to England when he was 13 (i.e., 1928–1929) or 14 (i.e., 1929–1930). Under Brazilian nationality law, he had Brazilian citizenship from having been born there (jus soli). When he turned 18, the age at which Brazilians are liable to conscription, he applied for exemption to Joaquim Pedro Salgado Filho, his godfather and the then Minister of Aviation. This was denied by President Eurico Gaspar Dutra, so Medawar renounced his Brazilian citizenship.

In 1928, Medawar went to Marlborough College in Marlborough, Wiltshire. He hated the college because "they were critical and querulous at the same time, wondering what kind of person a Lebanese was—something foreign you can be sure", and also because of its preference for sports, in which he was weak. An experience of bullying and racism made him feel the rest of his life "resentful and disgusted at the manners and mores of [Marlborough's] essentially tribal institution," and likened it to the training schools for the Nazi SS as all "founded upon the twin pillars of sex and sadism." His proudest moments at the college were with his teacher Ashley Gordon Lowndes, to whom he credited the beginning of his career in biology. He said Lowndes was "barely literate" but "a very, very good biology teacher". Lowndes had taught eminent biologists including John Z. Young and Richard Julius Pumphrey. Yet Medawar was inherently weak in dissection and was constantly irked by their dictum: "Bloody foolish is the boy whose drawing of his dissection differs in any way whatsoever from the diagram in the textbook."

In 1932, he went on to Magdalen College, Oxford, graduating with a first-class honours degree in zoology in 1935. Medawar was appointed Christopher Welch scholar and senior demy of Magdalen in 1935. He also worked at the Sir William Dunn School of Pathology supervised by Howard Florey (later Nobel laureate, and who inspired him to take up immunology) and completed his doctoral thesis in 1941. In 1938, he became Fellow of Magdalen through an examination, the position he held until 1944. It was there that he started working with J. Z. Young on the regeneration of nerves. His invention of a nerve glue proved useful in surgical operations of severed nerves during World War II.

The University of Oxford approved his Doctor of Philosophy thesis titled "Growth promoting and growth inhibiting factors in normal and abnormal development" in 1941, but because of the prohibitive cost of supplication (the process by which the degree is officially conferred), he spent the money on his urgent appendicectomy instead. The University of Oxford later awarded him a Doctor of Science degree in 1947.

Career and research

After completing his PhD, Medawar was appointed a Rolleston Prizeman in 1942, senior research fellow of St John's College, Oxford, in 1944, and a university demonstrator in zoology and comparative anatomy, also in 1944. He was re-elected fellow of Magdalen from 1946 to 1947. In 1947, he became Mason Professor of Zoology at the University of Birmingham and worked there until 1951. He transferred to University College London in 1951 as Jodrell Professor of Zoology and Comparative Anatomy.

In 1962, he was appointed director of the National Institute for Medical Research. His predecessor Sir Charles Harrington was an able administrator such that taking over his post was, as he described, "[N]o more strenuous than ... sliding over into the driving-seat of a Rolls-Royce". He was head of the transplantation section of the Medical Research Council's clinical research centre at Harrow from 1971 to 1986. He became professor of experimental medicine at the Royal Institution (1977–1983), and president of the Royal Postgraduate Medical School (1981–1987).

Jai Ganesh · Dark Discussions at Cafe Infinity

27) Girard Desargues

Girard Desargues (21 February 1591 – September 1661) was a French mathematician and engineer, who is considered one of the founders of projective geometry. Desargues' theorem, the Desargues graph, and the crater Desargues on the Moon are named in his honour.

Biography

Born in Lyon, Desargues came from a family devoted to service to the French crown. His father was a royal notary, an investigating commissioner of the Seneschal's court in Lyon (1574), the collector of the tithes on ecclesiastical revenues for the city of Lyon (1583) and for the diocese of Lyon.

Girard Desargues worked as an architect from 1645. Prior to that, he had worked as a tutor and may have served as an engineer and technical consultant in the entourage of Richelieu. Yet his involvement in the Siege of La Rochelle, though alleged by Ch. Weiss in Biographie Universelle (1842), has never been testified.

As an architect, Desargues planned several private and public buildings in Paris and Lyon. As an engineer, he designed a system for raising water that he installed near Paris. It was based on the use of the epicycloidal wheel, the principle of which was unrecognized at the time.

His research on perspective and geometrical projections can be seen as a culmination of centuries of scientific inquiry across the classical epoch in optics that stretched from al-Hasan Ibn al-Haytham (Alhazen) to Johannes Kepler, and going beyond a mere synthesis of these traditions with Renaissance perspective theories and practices.

His work was rediscovered and republished in 1864. A collection of his works was published in 1951, and the 1864 compilation remains in print. One notable work, often cited by others in mathematics, is "Rough draft for an essay on the results of taking plane sections of a cone" (1639).

Late in his life, Desargues published a paper with the cryptic title of DALG. The most common theory about what this stands for is Des Argues, Lyonnais, Géometre (proposed by Henri Brocard).

He died in Lyon.

Jai Ganesh · This is Cool

2482) Skeletal Muscle

Gist

Skeletal muscle is a type of muscle tissue attached to bones by tendons, responsible for voluntary movements like walking, lifting, and maintaining posture, and is characterized by its striped (striated) appearance and control by the nervous system for conscious action. It's a vital organ, making up a significant portion of body weight, and also generates heat, protects organs, and stores nutrients.

People with problems of skeletal muscle usually present with complaints of pain, stiffness or weakness. Muscle pain and pain caused by other structures in the body can be difficult to identify because muscle overlies many different types of structures including the bursa , joints, and bone.

Summary

Skeletal muscle, in vertebrates, is the most common of the three types of muscle in the body. Skeletal muscles are attached to bones by tendons, and they produce all the movements of body parts in relation to each other. Unlike smooth muscle and cardiac muscle, skeletal muscle is under voluntary control. Similar to cardiac muscle, however, skeletal muscle is striated; its long, thin, multinucleated fibres are crossed with a regular pattern of fine red and white lines, giving the muscle a distinctive appearance. Skeletal muscle fibres are bound together by connective tissue and communicate with nerves and blood vessels.

Details

Skeletal muscle (commonly referred to as muscle) is one of the three types of vertebrate muscle tissue, the others being cardiac muscle and smooth muscle. They are part of the voluntary muscular system and typically are attached by tendons to bones of a skeleton. The skeletal muscle cells are much longer than in the other types of muscle tissue, and are also known as muscle fibers. The tissue of a skeletal muscle is striated – having a striped appearance due to the arrangement of the sarcomeres.

A skeletal muscle contains multiple fascicles – bundles of muscle fibers. Each individual fiber and each muscle is surrounded by a type of connective tissue layer of fascia. Muscle fibers are formed from the fusion of developmental myoblasts in a process known as myogenesis resulting in long multinucleated cells. In these cells, the nuclei, termed myonuclei, are located along the inside of the cell membrane. Muscle fibers also have multiple mitochondria to meet energy needs.

Muscle fibers are in turn composed of myofibrils. The myofibrils are composed of actin and myosin filaments called myofilaments, repeated in units called sarcomeres, which are the basic functional, contractile units of the muscle fiber necessary for muscle contraction. Muscles are predominantly powered by the oxidation of fats and carbohydrates, but anaerobic chemical reactions are also used, particularly by fast twitch fibers. These chemical reactions produce adenosine triphosphate (ATP) molecules that are used to power the movement of the myosin heads.

Skeletal muscle comprises about 35% of the body of humans by weight. The functions of skeletal muscle include producing movement, maintaining body posture, controlling body temperature, and stabilizing joints. Skeletal muscle is also an endocrine organ. Under different physiological conditions, subsets of 654 different proteins as well as lipids, amino acids, metabolites and small RNAs are found in the secretome of skeletal muscles.

Skeletal muscles are substantially composed of multinucleated contractile muscle fibers (myocytes). However, considerable numbers of resident and infiltrating mononuclear cells are also present in skeletal muscles. In terms of volume, myocytes make up the great majority of skeletal muscle. Skeletal muscle myocytes are usually very large, being about 2–3 cm long and 100 μm in diameter. By comparison, the mononuclear cells in muscles are much smaller. Some of the mononuclear cells in muscles are endothelial cells (which are about 50–70 μm long, 10–30 μm wide and 0.1–10 μm thick), macrophages (21 μm in diameter) and neutrophils (12-15 μm in diameter). However, in terms of nuclei present in skeletal muscle, myocyte nuclei may be only half of the nuclei present, while nuclei from resident and infiltrating mononuclear cells make up the other half.

Additional Information

Skeletal muscles comprise 30% to 40% of your total body mass. They’re the muscles that connect to your bones and allow you to perform a wide range of movements and functions. Skeletal muscles are voluntary, meaning you control how and when they work. It’s important to keep your skeletal muscles as strong and healthy as possible.

Overview:

What is skeletal muscle?

The majority of the muscles in your body are skeletal muscles (striated muscles). They make up between 30% and 40% of your total body mass. Tendons (tough bands of connective tissue) attach skeletal muscle tissue to bones throughout your body. Your shoulder muscles, hamstring muscles and abdominal muscles are all examples of skeletal muscles.

There are three types of muscles in your body: skeletal, cardiac and smooth muscle. Skeletal muscles are voluntary muscles, meaning you control how and when they move and work. Nerves in your somatic nervous system send signals to make them function. If you reach for a book on a shelf, you’re using skeletal muscles in your neck, arm and shoulder.

Cardiac and smooth muscle are involuntary muscles that your autonomic nervous system controls. That means they work without you having to think about it. For example, muscles in your urinary system help rid your body of waste and toxins.

Skeletal muscle mass varies from person to person. Males have more skeletal muscle mass than females. People who are tall or have overweight also tend to have higher muscle mass. Muscle mass decreases with age.

Function:

What do skeletal muscles do?

Your striated muscles are a vital part of your musculoskeletal system. They serve a variety of functions, including:

* Chewing and swallowing, which are the first parts of digestion
* Expanding and contracting your chest cavity so you can inhale and exhale
* Maintaining body posture
* Moving the bones in different parts of your body
* Protecting your joints and holding them in place
* Storing nutrients
* Sustaining body temperature

Anatomy:

Where are the skeletal muscles located?

Your skeletal muscles are located between the bones (skeletal system) throughout your body. They consist of flexible muscle fibers that range from less than half an inch to just over 3 inches in diameter. These fibers usually span the length of the muscle. The fibers contract (tighten), which allows the muscles to move bones so you can perform lots of different movements.

What are the parts of skeletal muscles?

Each muscle can contain thousands of fibers. Different types of sheaths, or coverings, surround the fibers:

* Epimysium. The outermost layer of tissue surrounding the entire muscle.
* Perimysium. The middle layer surrounding bundles of muscle fibers.
* Endomysium. The innermost layer surrounding individual muscle fibers.

What do skeletal muscles look like?

Skeletal muscle fibers are red and white. They look striated, or striped, so they’re often called striated muscles. Cardiac muscles are also striated, but smooth muscles aren’t.

Conditions and Disorders:

What are the common conditions and disorders that affect striated muscles?

A wide range of conditions can affect skeletal muscles, from mild injuries to serious or even life-threatening myopathies (diseases that affect skeletal muscles). A few are:

* Muscular dystrophies
* Myasthenia gravis (MG)
* Rhabdomyolysis
* Sarcopenia
* Strains
* Tendonitis.

Jai Ganesh · Jai Ganesh's Puzzles

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Jai Ganesh · Dark Discussions at Cafe Infinity

Combat Quotes - I

1. Errors of opinion may be tolerated where reason is left free to combat it. - Thomas Jefferson

2. Virtue is a state of war, and to live in it we have always to combat with ourselves. - Jean-Jacques Rousseau

3. There should be an honest attempt at the reconciliation of differences before resorting to combat. - Jimmy Carter

4. In the re-creation of combat situations, and this is coming from a director who's never been in one, being mindful of what these veterans have actually gone through, you find that the biggest concern is that you don't look at war as a geopolitical endeavor. - Steven Spielberg

5. I think I'd be a better president because I was in combat. - George H. W. Bush

6. I exhort you also to take part in the great combat, which is the combat of life, and greater than every other earthly conflict. - Plato

7. One thing that was amazing about World War II was that everybody signed up for the duration plus six months. Fliers got to leave combat after 25 missions, or 35 missions, but other than that, you were in it. You were part of the great effort, until, oh boy, six months after it was over. - Tom Hanks

8. I've led a life of such structured discipline and always had a goal in mind of knowing what I was doing, from West Point to the Air Force combat, MIT, looking for new things to study and get involved in. And then I got into the space program, and how disciplined can you get? - Buzz Aldrin.

Jai Ganesh · Jokes

Q: Why does the jellybean go to school?
A: Because he wants to become a smartie.
* * *
Q: What do you get when you cross Ice, chocolate, a big strawberry, a giant pineapple, and cold milk?
A: The world's best Sundae!
* * *
Q: How many grams of protein are there in that slice of chocolate pie?
A: 3.14159265...
* * *
Q: What do you call people who like to drink hot chocolate all year long?
A: Cocoa-Nuts.
* * *
Life is like a box of chocolates, It doesn't last too long for fat people.
* * *

Jai Ganesh · Jai Ganesh's Puzzles

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#9840.

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#6334.

Jai Ganesh · Exercises

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2691.

Jai Ganesh · This is Cool

Madagascar

Gist

Madagascar, an island nation off Africa's southeastern coast in the Indian Ocean, is the world's fourth-largest island, renowned for its incredible biodiversity, with over 90% of its wildlife—including lemurs—found nowhere else on Earth. Known for baobabs and unique landscapes, its capital is Antananarivo, and it features a blend of Malagasy, African, and Asian cultural influences.

Madagascar is known for its extraordinary biodiversity, especially its unique wildlife like lemurs and chameleons, found nowhere else, alongside unique landscapes such as the Avenue of the Baobabs, tropical rainforests, and spiny deserts, making it a biodiversity hotspot and a top destination for nature lovers seeking adventure. Its rich culture blends Indonesian and African influences, while it's also famous for vanilla and pepper production.

Summary

Details

Madagascar is an island country lying off the southeastern coast of Africa. Madagascar is the fourth largest island in the world, after Greenland, New Guinea, and Borneo.

Although located some 250 miles (400 km) from the African continent, Madagascar’s population is primarily related not to African peoples but rather to those of Indonesia, more than 3,000 miles (4,800 km) to the east. The Malagasy peoples, moreover, do not consider themselves to be Africans, but, because of the continuing bond with France that resulted from former colonial rule, the island developed political, economic, and cultural links with the French-speaking countries of western Africa. The animal life and vegetation of the island are equally anomalous, differing greatly from that of nearby Africa and being in many respects unique. Although the coastlands have been known to Europeans for more than 400 years and to Arabs for much longer, recent historical development has been more intense and concentrated in the central plateau, which contains the capital city of Antananarivo (formerly Tananarive).

Land

Madagascar is located in the southwestern Indian Ocean and is separated from the African coast by the 250-mile- (400-km-) wide Mozambique Channel.

Relief

Madagascar consists of three parallel longitudinal zones—the central plateau, the coastal strip in the east, and the zone of low plateaus and plains in the west.

Situated between 2,500 and 4,500 feet (800 and 1,400 metres) above sea level, the plateau has been uplifted and worn down several times and is tilted to the west. Three massifs are more than 8,500 feet (2,600 metres) high. The Tsaratanana region in the north is separated from the rest of the plateau by the Tsaratanana Massif, whose summit, Maromokotro, reaches 9,436 feet (2,876 metres) and is the highest point on the island. Ankaratra Massif in the centre is an enormous volcanic mass whose summit, Tsiafajavona, is 8,671 feet (2,643 metres) high. Ankaratra is a major watershed divide separating three main river basins. Farther south, Andringitra is a vast granite massif north of Tôlan̈aro (Faradofay); it rises to 8,720 feet (2,658 metres) at Boby Peak.

The plateau slopes with some regularity toward the extreme southern plain, but its boundaries to the east and west are more abrupt. To the east it descends in a sharp fault, by vertical steps of 1,000 to 2,000 feet (300 to 600 metres). This cliff, which is called the Great Cliff or the Cliff of Angavo, is often impassable and is itself bordered by the Betsimisaraka Escarpment, a second and lower cliff to the east, which overhangs the coastal plain. Behind the scarp face are the remains of ancient lakes, including one called Alaotra. To the south the two steep gradients meet and form the Mahafaly and the Androy plateaus, which overhang the sea in precipitous cliffs. Toward the west the descent is made in a series of steps. However, in places the central plateau is bordered by an impassable escarpment, such as the Cliff of Bongolava in the west-central part of the island. To the extreme north the plateau is bordered by the low belt of the Ambohitra Mountains, which include a series of volcanic craters.

The coastal strip has an average width of about 30 miles (50 km). It is a narrow alluvial plain that terminates in a low coastline bordered with lagoons linked together by the Pangalanes (Ampangalana) Canal, which is more than 370 miles (600 km) long. To the south of Farafangana the coast becomes rocky, and in the southeast there occur many little bays. To the northeast is the deep Bay of Antongil (Antongila).

The western zone is between 60 and 125 miles (100 and 200 km) wide. Its sedimentary layers slope toward the Mozambique Channel and produce a succession of hills. The inland (eastern) side of these steep hills dominates the hollows formed in the soft sediments of the interior, while the other side descends to the sea in rocky slopes. The coastline is straight, bordered by small dunes and fringed with mangroves. The currents in the Mozambique Channel have favoured the offshore deposit of alluvium and the growth of river deltas. On the northwestern coast there are a number of estuaries and bays. This coast is bordered by coral reefs and volcanic islands, such as Nosy Be (Nossi-Bé), which protects Ampasindava Bay.

Drainage

The steep eastern face of the plateau is drained by numerous short, torrential rivers, such as the Mandrare, the Mananara, the Faraony, the Ivondro, and the Maningory, which discharge either into the coastal lagoons or directly into the sea over waterfalls and rapids. The more gently sloping western side of the plateau is crossed by longer and larger rivers, including the Onilahy, the Mangoky, the Tsiribihina, and the Betsiboka, which bring huge deposits of fertile alluvium down into the vast plains and many-channeled estuaries; the river mouths, while not completely blocked by this sediment, are studded with numerous sandbanks.

There are many lakes of volcanic origin on the island, such as Lake Itasy. Alaotra is the last surviving lake of the eastern slope. Lake Tsimanampetsotsa, near the coast south of Toliara (formerly Tuléar), is a large body of saline water that has no outlet.

Soils

The central plateau and the eastern coast are mainly composed of gneiss, granite, quartz, and other crystalline rock formations. The gneiss decomposes into red murrum, laterite, and deeper and more fertile red earths, giving Madagascar its colloquial name the Great Red Island. Fertile alluvial soils in the valleys support intensive cultivation. There also are scattered volcanic intrusions that produce fertile but easily erodible soils. Lake Alaotra is a large sedimentary pocket in the central plateau containing some of the island’s most productive farmland. The western third of the island consists entirely of deposits of sedimentary rock, giving rise to soils of medium to low fertility.

Climate of Madagascar

The hot, wet season extends from November to April and the cooler, drier season from May to October. The climate is governed by the combined effects of the moisture-bearing southeast trade and northwest monsoon winds as they blow across the central plateau. The trade winds, which blow throughout the year, are strongest from May to October. The east coast is to the windward and has a high annual rate of precipitation, reaching nearly 150 inches (3,800 mm) at Maroantsetra on the Bay of Antongil. As the winds cross the plateau, they lose much of their humidity, causing only drizzle and mists on the plateau itself and leaving the west in a dry rain shadow. The southwest in particular is almost desert, with the dryness aggravated by a cold offshore current.

The monsoon, bringing rain to the northwest coast of Madagascar and the plateau, is most noticeable during the hot, humid season. The wind blows obliquely onto the west coast, which receives a moderate amount of precipitation annually; the southwest, which is protected, remains arid. Annual precipitation drops from about 80 inches (about 2,000 mm) on the northwestern island of Nosy Be to about 40 inches (1,000 mm) at Maintirano on the west coast to about 14 inches (360 mm) at Toliara in the southwest. The plateau receives moderate levels of precipitation, with about 50 inches (1,200 mm) falling annually at both Antananarivo and Fianarantsoa, which lies about 200 miles (320 km) farther south.

July is the coolest month, with mean monthly temperatures around the island ranging from the low 50s F (low 10s C) to the high 70s F (mid-20s C), and December is the hottest month, with temperatures between the low 60s and mid-80s F (mid 10s and high 20s C). Temperatures generally decrease with elevation, being highest on the northwest coast and lowest on the plateau.

Tropical cyclones are an important climatic feature. They form far out over the Indian Ocean, especially from December to March, and approach the eastern coast, bringing torrential rains and destructive floods.

Plant and animal life

Much of the island was once covered with evergreen and deciduous forest, but little now remains except on the eastern escarpment and in scattered pockets in the west. The plateau is particularly denuded and suffers seriously from erosion. The forest has been cut in order to clear rice fields, to obtain fuel and building materials, and to export valuable timber such as ebony, rosewood, and sandalwood. About seven-eighths of the island is covered with prairie grasses and bamboo or small thin trees. There also are screw pines, palms, and reeds on the coasts. In the arid south of the island grow thorn trees, giant cacti, dwarf baobab trees, pachypodium succulents, and other xerophytes (drought-resistant plants) that are peculiar to the island.

Because of the island’s isolation, many zoologically primitive primates have survived and evolved into unique forms. About 40 species of lemurs are indigenous to Madagascar. Several unique hedgehoglike insectivores, such as the tenrec, have evolved there, and there are also many kinds of chameleons of varying size. Birds are numerous and include guinea fowl, partridges, pigeons, herons, ibis, flamingos, egrets, cuckoos, Asian robins, and several kinds of birds of prey. There are about 800 species of butterflies, many moths, and a variety of spiders. The only large or dangerous animals are the crocodiles, which occupy the rivers. The snakes, including the do, which is 10 to 13 feet (3 to 4 metres) in length, are harmless.

Inland waters contain tilapia (an edible perchlike fish), rainbow trout, and black bass. Marine fish and crustaceans abound on the coasts and in the lagoons, estuaries, and even in some upland streams. They include groupers, giltheads, tuna, sharks, sardines, whitings, crayfish, crabs, shrimps, mussels, and oysters. The coelacanth, referred to as a living fossil and once thought extinct for millions of years, inhabits offshore waters.

Additional Information

Located off the east coast of Africa in the Southwest Indian Ocean, Madagascar is the world’s fourth largest island; at 146 million acres, it’s almost the size of Texas. Madagascar’s climate is tropical along the coast, temperate inland, and arid in the south. The island harbors lush rain forests, tropical dry forests, plateaus, and deserts. Its more than 3,000 miles of coastline and over 250 islands are home to some of the world’s largest coral reef systems, tidal marshes, seagrass beds, and most extensive mangrove areas in the Western Indian Ocean.

More than 11,000 endemic plant species, including seven species of baobab tree and all lemur species, share Madagascar with a vast variety of mammals, reptiles, fish, amphibians, and birds. Along the Northern Mozambique Channel, in the northwest, is Nosy Hara National Park, a world hotspot of marine diversity where an incredible 265 species of corals can be found. The country’s interior has several critically threatened species including the smallest chameleon in the world, Brookesia micra, and Verreaux’s sifaka, a lemur found in the southwest forests.

People and communities of Madagascar

Madagascar has a population of more than 21 million people with a wide array of faiths and customs, more than 20 ethnic groups coexist on the island. A majority of the population—70 percent of which is estimated to live below the international poverty line—depends completely on natural resources via subsistence farming and fishing. The ocean surrounding Madagascar has long been an important resource for coastal populations. 1.5 million people depend on fishing for their livelihoods and marine ecotourism is a growing sector of the national economy. Well over half of fishers are women and women are the primary cleaners, processors, and sellers of marine products.

Climate change

Climate change is causing increased and more severe drought in the south and more intense cyclones and flooding in the middle and north regions of Madagascar. This extreme weather forces millions of people to migrate across the country and puts added pressure on resources, including forests and fisheries. Warming oceans due to climate change is also leading to mass mortality in coral reefs.

Deforestation

The small-scale but widespread clearance of inland forest and coastal mangroves, primarily for firewood and charcoal production, is jeopardizing the island’s habitats and species such as lemurs and chameleons. Deforestation increases sediment flow out to the ocean and can smother coral reefs and reduce the productivity of fisheries.

Climate change has also increased the severity of droughts. Droughts are causing a surge in migration towards the country’s coastal areas and people are transitioning from agriculture to fishing, putting additional pressure on coastal environments and increasing demand for mangrove charcoal and timber. Over 12,000 acres of mangroves have been lost since 1996.

Governance and security

Only 3.1% of marine areas are formally protected in Madagascar and limited staff capacity and resources to manage and create marine protected areas hinder effective legislation. Management issues can impact distribution of industrial fisheries licenses and fish trader permits while inadequate monitoring, control, surveillance, and enforcement can exacerbate overfishing and illegal fishing.

The complicated history of Madagascar and its legal system contributes to significant policy variations across the country, complicating integration across economic sectors and with the broader Southwest Africa region to address cross-cutting policy and governance issues.

Unsustainable Fishing

It is estimated that some 130,000 tons of fish are illegally fished from Madagascar’s marine territories every year, amounting to a loss of $142.8 million in potential income. Bottom trawling and seine netting degrade and damage coral reefs, threatening the long-term resource availability and food security for coastal communities. As reefs degrade, fishers are forced to find different, less exploited reefs and may repeat the same damaging practices. Under weak governance and rising insecurity, unsustainable fishing practices thrive and threaten coastal livelihoods and food security. Illegal, unreported, and unregulated fishing is a pervasive problem and contributes to overfishing.

Jai Ganesh · Science HQ

Keyhole Surgery

Gist

Keyhole or minimally invasive surgery is a method of carrying out an operation without having to make a large incision. It is also known as laparoscopic surgery when used to operate on the abdomen and thoracoscopic surgery when used on the chest area.

Keyhole surgery, also known as laparoscopic or minimally invasive surgery, lets surgeons operate inside the body through tiny incisions (like keyholes) using a camera (laparoscope) and specialized instruments, avoiding large cuts for faster healing, less pain, and smaller scars compared to traditional open surgery. A camera transmits images to a screen, guiding the surgeon who uses long, thin tools inserted through separate small cuts to perform procedures in the abdomen, pelvis, joints, or chest.

Summary

Laparoscopy is an operation performed in the abdomen or pelvis using small incisions (usually 0.5–1.5 cm) with the aid of a camera. The laparoscope aids diagnosis or therapeutic interventions with a few small cuts in the abdomen.

Laparoscopic surgery, also called minimally invasive procedure, bandaid surgery, or keyhole surgery, is a modern surgical technique. There are a number of advantages to the patient with laparoscopic surgery versus an exploratory laparotomy. These include reduced pain due to smaller incisions, reduced hemorrhaging, and shorter recovery time. The key element is the use of a laparoscope, a long fiber optic cable system that allows viewing of the affected area by snaking the cable from a more distant, but more easily accessible location.

Laparoscopic surgery includes operations within the abdominal or pelvic cavities, whereas keyhole surgery performed on the thoracic or chest cavity is called thoracoscopic surgery. Specific surgical instruments used in laparoscopic surgery include obstetrical forceps, scissors, probes, dissectors, hooks, and retractors. Laparoscopic and thoracoscopic surgery belong to the broader field of endoscopy. The first laparoscopic procedure was performed by German surgeon Georg Kelling in 1901.

Details

Laparoscopy is a type of keyhole surgery used to diagnose and treat conditions. It allows a surgeon to use only small cuts and a camera for procedures inside the tummy or pelvis.

Why a laparoscopy is done

A laparoscopy can be used to diagnose conditions such as appendicitis, pelvic inflammatory disease, endometriosis and some cancers, such as liver cancer and ovarian cancer.

It's also used for surgery to treat conditions, such as:

* removing organs such as the appendix or gallbladder
* repairing hernias or burst or bleeding stomach ulcers
* removing organs affected by cancer, such as the ovaries, prostate or liver
* treating an ectopic pregnancy
* removing the womb (hysterectomy) or fibroids
* weight loss surgery

A laparoscopy is often recommended because the recovery time is faster than other types of surgery.

Preparing for a laparoscopy

The hospital will give you information about how to prepare for a laparoscopy.

Depending on why you're having a laparoscopy, you may be asked to do certain things, such as:

* not eating or drinking
* stop taking certain medicines, such as anticoagulants
* stop smoking

You cannot drive after having a laparoscopy, so you'll need to organise for someone to drive you home.

What happens during a laparoscopy

If you're having a laparoscopy to diagnose a condition, it usually takes between 30 and 60 minutes. It'll be longer if you're having surgery to treat a condition.

A laparoscopy is done under general anaesthetic, so you'll be asleep during the operation and will not feel any pain.

1) The surgeon will make a small cut, usually near your belly button.
2) Air is pumped into your tummy through the cut so the surgeon can see inside your tummy more easily.
3) A thin, flexible tube with a camera inside (a laparoscope) is then put into the cut so video images of the inside of your tummy can be shown on a screen.
4) If you're having surgery, more small cuts may need to be made in your tummy for the surgeon to pass their tools through.
5) When it's finished, the air is let out of your tummy and the cuts are closed with stitches or clips, and a dressing is placed on top.

After the operation

You'll spend some time in the recovery room and have medicine to help with pain and swelling.

After the operation, you may:

* feel sick or be sick
* feel more tired than normal
* have a sore throat
* have bloating, cramps or pain and discomfort in your tummy
* get shoulder pain
* have bruises around your wounds

Most people can leave hospital either on the same day or the day after.

Recovering from a laparoscopy

How long it takes to recover from a laparoscopy varies.

It usually takes up to 10 days if you had it to diagnose a condition, but it may be up to 3 weeks before you can return to work. If you've had surgery, it can take up to 6 to 8 weeks to fully recover.

There are things you can do to help your recovery.

Do

* take paracetamol or ibuprofen to help with any pain
* make sure you drink lots of fluids and have a healthy diet
* wear compression stockings if you've been given some
* move around as much as you can
* do foot and leg exercises, such as moving your ankles in circles, while you're resting
* keep your wound dry for the first 24 hours – you can shower after this, but make sure the water is not too hot, as it can make the wounds bleed

Don’t

* do not have a bath for the first 2 weeks, or until the wound has healed
* do not drive for 48 hours or until you can do an emergency stop (but check with your insurer first)
* do not fly for 48 hours after having a laparoscopy
* do not drink alcohol for 48 hours
* do not smoke as it can take your body longer to heal

Possible complications of a laparoscopy

A laparoscopy is a common procedure.

Complications are rare, but can include:

* needing to have open surgery with a larger cut
* a hernia
* damage to an organ, such as your bladder
* damage to a blood vessel
* a serious allergic reaction (anaphylaxis) to the general anaesthetic
* blood clots, such as a DVT (deep vein thrombosis) or pulmonary embolism.

Additional Information

Laparoscopy is a procedure that permits visual examination of the abdominal cavity with an optical instrument called a laparoscope, which is inserted through a small incision made in the abdominal wall. The term comes from the Greek words laparo, meaning “flank,” and skopein, meaning “to examine.”

The laparoscope is a type of endoscope—i.e., a device similar to a small telescope that is equipped with a light source. Laparoscopy came into use early in the 20th century. It was first used as a means of diagnosing abdominal pain. By the 1960s gynecologists were using the laparoscope in operations such as tubal ligations. Modern laparoscopes have been fitted with fibre-optic lights and small video cameras that allow a surgical team to view the abdominal tissues and organs on a monitor in the operating room. These improvements have expanded the applications of laparoscopy. Today the technique is not only used to obtain diagnostic information but employed in a variety of surgeries, including removal of the gallbladder (cholecystectomy), appendectomy, hysterectomy, repair of hernias, and removal of cancerous tumours.

Laparoscopy is a minimally invasive surgical procedure because it requires a much smaller incision than traditional surgery does, causing less damage to nerves, muscles, and skin. It can be performed with only local anesthesia and a mild sedative. To begin the procedure, carbon dioxide is pumped into the abdomen, thereby expanding the abdominal cavity to provide the physician with space to maneuver instruments. Next a small incision is made for the laparoscope. Additional tiny cuts can be made if surgical instruments such as forceps and scissors are needed in the procedure. Valuable diagnostic information can be obtained by examining a biopsy specimen of the liver or abdominal lesions. The benefits of laparoscopic surgery include a reduction in postoperative pain, brief recovery times, and shortened hospital stays.

Jai Ganesh · This is Cool

Borneo

Gist

Borneo is the world's third-largest island, covering approximately 748,168 square kilometers (288,869 sq miles). Located in Southeast Asia, it is the largest island in Asia and is divided among three countries: Indonesia (roughly 73%), Malaysia (around 26%), and Brunei (about 1%). Known for its immense biodiversity and ancient rainforests, it is also a major center for wildlife.

Borneo is famous for its ancient, biodiverse rainforests, unique wildlife (orangutans, proboscis monkeys, pygmy elephants), world-class diving, and stunning landscapes, including Mount Kinabalu, making it a prime destination for eco-tourism, adventure, and experiencing rich indigenous cultures. It's known as a hotspot for endemic species and hosts the world's largest flower, Rafflesia arnoldii.

Summary

Borneo is the third-largest island in the world, with an area of 748,168 sq km (288,869 sq mi), and population of 23,053,723 (2020 national censuses). Situated at the geographic centre of Maritime Southeast Asia, it is one of the Greater Sunda Islands, located north of Java, west of Sulawesi, and east of Sumatra. The island is crossed by the equator, which divides it roughly in half. In Indonesia, the island is also known as Kalimantan, which is also the name of the Indonesian region located on the island.

The geology of Borneo was formed beginning in the Mesozoic. It formed part of Sundaland, a region connected to mainland Asia, until it became isolated by sea level rise at the end of the last ice age. With seven unique ecoregions, including large expanses of some of the oldest tropical rainforests in the world, Borneo is rich in biodiversity and endemic species.

Archaeological evidence suggests Borneo has been inhabited by humans for more than 65,000 years. Borneo is home to hundreds of different Indigenous groups, cultures and languages, loosely grouped under the term "Dayak". International trading ports were well established on Borneo by the first millennium. It was later subsumed into the Majapahit Empire. The Sultanate of Sulu later ruled much of the island's North, and at its peak in the 14th century, the Sultanate of Brunei governed most of its coast; meanwhile, Borneo's interior remained largely outside of their control. Borneo was later colonised by the British and Dutch, and occupied by Japan during World War II.

Since the decolonisation of Asia, the island has been politically divided among three states, with the borders broadly following previous demarcation between the British and Dutch. The sovereign state of Brunei in the north makes up 1% of the territory. Approximately 73% of Borneo is Indonesian territory, and in the north, the East Malaysian states of Sabah and Sarawak make up about 26% of the island. The Malaysian federal territory of Labuan is situated on a small island just off the coast of Borneo.

The majority of Borneo's inhabitants reside in coastal cities. It is the site of Indonesia's planned future capital, Nusantara. Major economic sectors include oil and gas, agriculture, timber and tourism. Industrial deforestation in Indonesian and Malaysian Borneo for timber and agricultural conversion has taken place during the past century.

Details

Borneo is an island in the extreme southwestern part of the Pacific Ocean. It is the third largest island in the world, surpassed in size by only Greenland and New Guinea.

Borneo is situated southeast of the Malay Peninsula in the Greater Sunda Islands group of the Malay Archipelago. The island is bounded by the South China Sea to the northwest, the Sulu Sea to the northeast, the Celebes Sea to the east, and the Java Sea to the south—the latter separating Borneo from the island of Java. The Makassar Strait separates Borneo from the island of Celebes (Sulawesi) to the east and southeast, and a series of shallow seas and straits lie between Borneo and the island of Sumatra to the west.

Indonesia constitutes the largest political component of the island (in Indonesian known as Kalimantan), its territory divided into five provinces: Central Kalimantan, East Kalimantan, North Kalimantan, South Kalimantan, and West Kalimantan. Along the northwest coast and northern tip lie Sarawak and Sabah, two constituent states of Malaysia that are often collectively called East Malaysia, and between them is the Islamic sultanate of Brunei. Area (including adjacent islands), about 292,000 square miles (755,000 square km). Pop. (2015) five provinces of Kalimantan (including adjacent islands), 15,320,017; (2010) Sabah and Sarawak, 5,677,882; (2014 est.) Brunei, 411,900.

Land

Borneo lies astride the Equator. It has a length of 830 miles (1,336 km) from northeast to southwest and a maximum breadth of 600 miles (960 km). The island is largely mountainous, although there are extensive lowlands, especially in Central Kalimantan and Sarawak, that are often swampy along the coasts. A long series of mountain ranges extend southwest across the island from Mount Kinabalu in the far northeast, which, at an elevation of 13,455 feet (4,101 metres), is the island’s greatest height and is also the tallest peak in Malaysia. Ranges in the central spine include the Crocker, the Nieuwenhuis, and the Muller mountains. The Kapuas Hulu Mountains branch westward from the central core along the border between Sarawak and West Kalimantan, and a separate and discontinuous series of ranges parallel the east and southeast coasts in East and South Kalimantan.

A large part of Borneo is drained by navigable rivers, which represent the principal and often the only lifelines of trade and commerce. The main rivers of Kalimantan are the Kapuas in the west and the Mahakam in the east. Farther north, as the island narrows, few rivers are navigable for more than 100 miles (160 km), often much less, a condition largely responsible for the northern interior of Borneo remaining, until recently, one of the least-known parts of the world. The main river of East Malaysia is the Rajang in Sarawak.

Borneo’s climate is equatorial—hot and humid with a fairly distinct division into two seasons, consisting of a wet monsoonal period (landas) between October and March and a relatively drier, calmer period of summer (tedoh) for the rest of the year. The average annual rainfall is about 150 inches (3,800 mm).

Borneo is largely covered in dense rainforest, and both the floral and the faunal populations of the island are extremely varied. There are extensive stands of teak, oak, conifers, and hardwoods of the Dipterocarpaceae family (including members the commercially valuable genus Shorea). The forests are also noted for their epiphytes and for the monster flower (Rafflesia arnoldii), the largest flower in the world. Mammals endemic to the island include the Bornean clouded leopard (Neofelis diardi) and the proboscis monkey (Nasalis larvatus). Other notable animals include orangutans, gibbons, and elephants, but the Sumatran rhinoceros is now extinct there. There are also a great many species of birds, insects, and fish.

People and economy

The island is sparsely inhabited by Asian standards. The population, of which more than two-thirds is in Indonesian territory, is varied. It includes non-Muslim Dayaks, Islamic Malays, Chinese, and a small minority of Europeans. The highest population densities are in South Kalimantan and in eastern, western, and northern coastal areas.

Borneo is poor in commercial mineral resources. Gold, diamonds, antimony, mercury, gypsum, and iron have all at some time since the beginning of the 19th century been exploited on an individual producer basis, using small-scale methods. There are oil fields at Tanjung Balikpapan, in Brunei, and at more than a dozen other sites on the continental shelf off the north shore of the island. East coast development is centred on the Attaka area. Bauxite has been developed near Cape Datu in the southwest since the late 1950s, and coal has been mined in the southwest.

Generally, Borneo soils are poor, with a few exceptions of fertile volcanic areas. Rice, the staple food, is supplemented with corn (maize), cassava (manioc), cucumber, and pumpkin. Rubber is grown on small native plantations. Pepper is grown on a large scale by the resident Chinese. Newer markets are for the seeds of the shorea tree and for chicle. Coastal area exports are sago, copra, cutch (a dye extracted from mangrove bark), and marine products. Tobacco is grown in the uplands and traded to the lowlands. Experimental plantings of coffee, cocoa, and hemp have been made.

History of Borneo

Evidence for prehistoric human occupation of Borneo has been found at Neah Cave in Sarawak, including fossil bones, stone tools, and wall and ceiling paintings. Borneo is first mentioned in Ptolemy’s Guide to Geography of about 150 ce. Roman trade beads and Indo-Javanese artifacts have been discovered that give evidence of a flourishing civilization dating to the 2nd or 3rd century ce. Three rough foundation stones with an inscription recording a gift to a Brahman priest dated from the early 5th century, found at Kutai, provide evidence of a Hindu kingdom in eastern Kalimantan. Brahmanic and Buddhist images in the Gupta style have been found in the valleys of the Kapuas and other rivers in western Kalimantan. Later Kalimantan rulers were probably feudatories of the Majapahit empire of eastern Java (c. 1293–1520). With the arrival of Islam early in the 16th century, a number of Muslim kingdoms were founded, including the Banjarmasin, Sambas, Sukadana, and Landak. The Sukadana rulers owed allegiance to the Muslim Mataram kingdom of Java.

Modern European knowledge of Borneo dates from travelers who passed through Southeast Asia in the 14th century. The first recorded European visitor was the Franciscan friar Odoric of Pordenone, who visited Talamasim on his way from India to China in 1330. The Portuguese, followed by the Spanish, established trading relations on the island early in the 16th century. At the beginning of the 17th century the Portuguese and Spanish trade monopoly was broken by the Dutch, who, intervening in the affairs of the Muslim kingdoms, succeeded in replacing Mataram influence with their own. The coastal strip along the South China and Sulu seas was long oriented toward the Philippines to the northeast and was often raided by Sulu pirates. British interests, particularly in the north and west, diminished that of the Dutch. The Brunei sultanate was an Islamic kingdom that at one time had controlled the whole island but by the 19th century ruled only in the north and northwest. In 1841 Sarawak was split away on the southwest, becoming an independent kingdom ruled by the Brooke Raj. North Borneo (later Sabah) to the northeast was obtained by a British company to promote trade and suppress piracy, but it was not demarcated until 1912. Those losses left a much-reduced Brunei, which became a British protectorate in 1888.

During World War II the Japanese invasions of Borneo (1941–42) quickly eliminated the token British and Dutch forces on the island, which was not retaken until 1945. In July 1946 both Sarawak and North Borneo were made British crown colonies. In Dutch Borneo a strong nationalist sentiment developed and led to fighting between Indonesian and Dutch forces as the latter attempted to reimpose Netherlands control. Sovereignty passed to the Indonesians in 1949, and in 1950 a new constitution proclaimed Dutch Borneo part of the Republic of Indonesia.

The British government relinquished its sovereignty over Sabah and Sarawak in 1963, when those territories joined the Malaysian federation. That marked the commencement of Indonesian hostilities in the form of guerrilla raids across the border. Those raids ceased by agreement in 1966. Except for the period of Japanese occupation, Brunei remained a British protectorate until 1983. It became fully independent on January 1, 1984.

Additional Information

Borneo is the world's third-largest island and the largest island of Asia. It is part of the Indonesian archipelago. Borneo is surrounded by the Java Sea to its south, the Celebes Sea on its east, and the South China Sea to its north. It has an area of 288,869 square miles (748,168 square kilometers).

From neighboring islands, Borneo is north of Java, west of Sulawesi, and east of Sumatra. The island is bisected by the equator, with approximately half of its land area in the northern hemisphere and half in the southern hemisphere.

The island is divided between three countries: Indonesia (73%), Malaysia (26%), and Brunei (1%). The Indonesian provinces of North Kalimantan, South Kalimantan, East Kalimantan, West Kalimantan, and Central Kalimantan make up the southeastern part of the island. The Malaysian states of Sabah and Sarawak make up the northwestern part of the island. Brunei is a sovereign state located almost entirely on Borneo. It consists of two coastal tracts within the Malaysian state of Sarawak, and also includes several small adjacent islands.

The island of Borneo is rich in natural resources. Known metal deposits include: gold, silver, copper, tin, aluminum (as bauxite), and iron ore. Most of the island is covered by tropical forests that produce tropical timber and other forest products. The coastal and offshore areas are underlain by deposits of coal, peat, oil, and natural gas.

Jai Ganesh · Science HQ

Microprocessor

Gist

A microprocessor is a silicon-based, multi-purpose, programmable integrated circuit (IC) that acts as the central processing unit (CPU) of a computer or embedded system. It executes stored binary instructions, performing arithmetic, logic, and control operations for devices ranging from calculators to smartphones. It consists of an Arithmetic Logic Unit (ALU), registers, and control circuitry.

The microprocessor is a multipurpose, clock driven, register based, digital- integrated circuit which accepts binary data as input, processes it according to instructions stored in its memory, and provides results as output.

How does a microprocessor work?

It does these three steps at incredible speeds of billions of times per second: Fetch: The microprocessor gets a software instruction from the memory telling it what to do with the data. Decode: The microprocessor determines what the instruction means. Execute: The microprocessor performs the instruction.

Summary

A microprocessor is a computer processor for which the data processing logic and control is included on a single integrated circuit (IC), or a small number of ICs. The microprocessor contains the arithmetic, logic, and control circuitry required to perform the functions of a computer's central processing unit (CPU). The IC is capable of interpreting and executing program instructions and performing arithmetic operations. The microprocessor is a multipurpose, clock-driven, register-based, digital integrated circuit that accepts binary data as input, processes it according to instructions stored in its memory, and provides results (also in binary form) as output. Microprocessors contain both combinational logic and sequential digital logic, and operate on numbers and symbols represented in the binary number system.

The integration of a whole CPU onto a single or a few integrated circuits using very-large-scale integration (VLSI) greatly reduced the cost of processing power. Integrated circuit processors are produced in large numbers by highly automated metal–oxide–semiconductor (MOS) fabrication processes, resulting in a relatively low unit price. Single-chip processors increase reliability because there are fewer electrical connections that can fail. As microprocessor designs improve, the cost of manufacturing a chip (with smaller components built on a semiconductor chip the same size) generally stays the same, according to Rock's law.

Before microprocessors, small computers had been built using racks of circuit boards with many medium- and small-scale integrated circuits. These were typically of the TTL type. Microprocessors combined this into one or a few large-scale ICs. While there is disagreement over who deserves credit for the invention of the microprocessor, the first commercially available microprocessor was the Intel 4004, designed by Federico Faggin and introduced in 1971. (TTL: Transistor–transistor logic).

Continued increases in microprocessor capacity have since rendered other forms of computers almost completely obsolete (see history of computing hardware), with one or more microprocessors used in everything from the smallest embedded systems and handheld devices to the largest mainframes and supercomputers.

A microprocessor is distinct from a microcontroller including a system on a chip. A microprocessor is related but distinct from a digital signal processor, a specialized microprocessor chip, with its architecture optimized for the operational needs of digital signal processing.

Details:

Introduction of Microprocessor

A Microprocessor is is a programmable device that takes in input, performs some arithmetic and logical operations over it and produces the desired output. In simple words, a Microprocessor is a digital device on a chip that can fetch instructions from memory, decode and execute them, and give results. It is an important part of a computer architecture without which you will not be able to perform anything on your computer.

Block Diagram of a Microprocessor

A Microprocessor takes a bunch of instructions in machine language and executes them, telling the processor what it has to do. The microprocessor performs three basic things while executing the instruction:

* It performs some basic operations like addition, subtraction, multiplication, division, and some logical operations using its Arithmetic and Logical Unit (ALU). New Microprocessors also perform operations on floating-point numbers.
* Data in microprocessors can move from one location to another.
* It has a Program Counter (PC) register that stores the address of the next instruction based on the value of the PC, Microprocessor jumps from one location to another and makes decisions.

A typical Microprocessor structure looks like this.

Clock Speed of different Microprocessor:

* 16-bit Microprocessor

** 8086: 4.7MHz, 8MHz, 10MHz

** 8088: more than 5MHz

** 80186/80188: 6MHz

** 80286: 8MHz

* 32-bit Microprocessor

** INTEL 80386: 16MHz to 33MHz

** INTEL 80486: 16MHz to 100MHz

** PENTIUM: 66MHz

* 64-bit Microprocessor

** INTEL CORE-2: 1.2GHz to 3GHz

** INTEL i7: 2.66GHz to 3.33GHz

** INTEL i5: 2.4GHz to 3.6GHz

** INTEL i3: 2.93GHz to 3.33GHz

We do not have any 128-bit Microprocessor at work at present one of the reasons for this is that we are a long way from exhausting the 64-bit address space itself, we use it at a constant rate of roughly 2 bits every 3 years. At present we have only used 48 bits of 64 bits so why require 128-bit address space. Also, 128-bit Microprocessor would be much slower than the 64 bit Microprocessor.

Types of Processor:

Complex Instruction Set Computer (CISC)

CISC or Complex Instruction Set Computer is a computer architecture where instructions are such that a single instruction can execute multiple low-level operations like loading from memory, storing into memory, or an arithmetic operation, etc. It has multiple addressing nodes within a single instruction. CISC makes use of very few registers.

Example of CISC are

* Intel 386
* Intel 486
* Pentium
* Pentium Pro
* Pentium II
* Pentium III
* Motorola 68000
* Motorola 68020
* Motorola 68040 etc.

Reduced Instruction Set Computer (RISC)

RISC or Reduced Instruction Set Computer is a computer architecture where instruction is simple and designed to get executed quickly. Instructions get completed in one clock cycle this is because of the optimization of instructions and pipelining (a technique that allows for simultaneous execution of parts, or stages, of instructions more efficiently process instructions). RISC makes use of multiple registers to avoid large interactions with memory. It has few addressing nodes.

Example of RISC are

* IBM RS6000
* MC88100
* DEC Alpha 21064
* DEC Alpha 21164
* DEC Alpha 21264

Explicitly Parallel Instruction Computing (EPIC)

EPIC or Explicitly Parallel Instruction Computing permits computers to execute instructions parallel using compilers. It allows complex instructions execution without using higher clock frequencies. EPIC encodes its instruction into 128-bit bundles. each bundle contains three instructions which are encoded in 41 bits each and a 5-bit template field(contains information about types of instructions in a bundle and which instructions can be executed in parallel).

Example of EPIC is

* IA-64 (Intel Architecture-64)

Evolution of Microprocessors

The Evolution of Microprocessors are categorize as

* First Generation (4-bit Microprocessors): The Intel Corporation first introduced the microprocessor in 1971-1972, naming it the Intel 4004. This initial microprocessor could perform basic arithmetic and logical functions. It also contained a control unit capable of fetching, decoding, and executing instructions.
* Second Generation (8-bit Microprocessor): The intel corporation first introduced the 8 bit microprocessor in 1973 with the intel 8008. This was followed by an enhanced model, the intel 8088.
* Third Generation (16-bit Microprocessors): The Third Generation introduced microprocessors capable of performing 16 bit operations. Introduced in 1978, this generation was represented by processors like the Intel 8086, Zilog Z800 and 80286.
* Fourth Generation (32 - bit Microprocessors):The most Used and famous 32 bit microprocessor was intel 80386.
* Fifth Generation (64 - bit Microprocessors):Since 1995, microprocessors with 64-bit processors which features 64 bit processors like Intel's Pentium pro which allows multiple CPU's in one.

Basic Terms used in Microprocessor

Given below are the some basic term used in the microprocessors

* Instruction Set: Instruction set is a group of instructions in the microprocess which can be executed. It is the Interface between hardware and software.
* Bus: Buses are used to carry data, address and control information within a microprocessor. There are three types of Bus which are data buses, address buses, and control buses.
* IPC (Instructions Per Cycle): It is Measured as the number of instructions that a CPU can execute in a Single clock cycle.
* Clock Speed: It refers to the number of operations a processor can perform per second. It is Measured in megahertz (MHz) or gigahertz (GHz).
* Bandwidth: It is measured as is the number of bits processed during a single instruction.
* Word Length :It Shows the number of bits a processor can handle at a time.
* Data Types: It Supports various formats such as binary, ASCII, Signed and Unsigned Bits.

Applications of Microprocessor

Given below are the Applications of the Microprocessors

* Computer: The Microprocessors are the CPU's in computers.
* Embedded Systems: It is utilized as the main processing block in the Embedded systems such as Washing machines, microwaves and other equipments.
* Industrial Automation: It can be used to control Industrial machinery and equipments.
* Automotive: The Modern day Vehicles uses Microprocessors in there ECUs.
* Telecommunications: The Microprocessors are utilized in the Telecommunications systems such as routers, modems, and switches.

Conclusion

In the following article we have gone through the Microprocessor, we have seen its definition along with its block diagram and different types, we also gone through Evolution of Microprocessors with its Applications.

Additional Information

A microprocessor is the predominant type of modern computer processor. It combines the components and function of a central processing unit (CPU) into a single integrated circuit (IC) or a few connected ICs.

Like CPUs, microprocessors are commonly thought of as the “brain” of the computer. Unlike traditional CPUs, microprocessors integrate the arithmetic, logic and control circuits of more traditional CPUs into a single multipurpose, clock-driven and register-based digital circuit.

While the terms CPU and microprocessor are often used interchangeably, a microprocessor is essentially an all-in-one CPU on a single chip. This single-chip design reduces the number of vulnerable electrical connections, improving reliability by reducing potential points of failure. As such, microprocessors have almost completely replaced traditional, multicomponent CPUs.

Before microprocessors, computers used racks of ICs to accomplish the computer’s main computing functions. In 1971, a significant shift occurred in computing technology with the introduction of the Intel 4004, the first commercially available microprocessor. This groundbreaking device, designed by Federico Faggin, was not just a response to a request for 12 custom microchips for a calculator from Japanese electronics maker Busicom. It was a landmark moment that revolutionized the way we think about computing, as Intel, instead of producing 12 individual chips, created a general-purpose logic device.

Underpowered by today’s standards, the Intel 4004’s architecture operated at a clock speed of 740 kHz and could only process data streams with a maximum of 4 bits, also known as a “nibble.” While the 4004 is weak compared to modern 8-bit to 64-bit microprocessors, it is universally considered to be a revolutionary breakthrough in circuitry. As predicted by Moore’s law, rapid semiconductor technology development led to major processing power improvements. Manufactured by leading suppliers, such as Intel and Pentium, and used by all major tech companies, such as IBM®, Microsoft and Apple, microprocessors power thousands of systems and applications from TV remote controls to the International Space Station.

How do microprocessors work?

Modern microprocessors combine millions of small transistors, resistors and diodes assembled on a semiconductor material to create the key components of a CPU. These components are arranged into various types of unique computer architecture to perform computations and run instructions. An average microprocessor's functions can be broken down into four main steps.

Key microprocessor steps

1. Fetch: The microprocessor retrieves (or "fetches") instructions from computer memory. The fetch process can be initiated by automatic or manual input.
2. Decode: The microprocessor "decodes" the instructions, essentially interpreting the input or command into a request and instigating a specific process or computation.
3. Execute: Simply put, the microprocessor performs the required or requested operation.
4. Store: The result of the execution is committed to the computer’s memory.

Microprocessor components

Microprocessors can complete these processes by combining the main components of a CPU into a singular circuit. The key components of a microprocessor are the following:

* Arithmetic logic unit (ALU): The main logic unit of the CPU, this component performs logical operations, including mathematical calculations and data comparisons.

* Control unit (CU): The CU circuit interprets instructions and initiates their execution, directing the processor's basic operations.

* Registers: Registers provide small, fast memory storage used by a CPU to temporarily hold data and instructions during computational processes.

* Cache memory: Microprocessors and CPUs use cache memory, a high-speed form of memory located close to the CPU, to store frequently accessed data to accelerate performance.

* Busses and bus interfaces: Bus interfaces provide entry and exit points for data to travel across various groups of wires (referred to as busses), such as the address bus or data bus. Busses and interfaces physically connect different internal components, enabling and facilitating communication within the CPU and other peripherals like input/output (I/O) units.

* Transistors: One of the main building blocks of ICs, transistors are small semiconductors that regulate, amplify and generate electrical currents and signals. They can also act as simple switches or be combined to form logic gates. The number of transistors is a common indicator of microprocessor power.

* Processor cores: Individual processing units within microprocessors are known as cores. Modern processors frequently incorporate multiple cores (dual-core, quad-core) allowing for parallel processing by enabling the performance of multiple tasks simultaneously.

* Clock: Although not all microprocessors contain an internal clock, they are all clock-driven. Some rely on external clock chips, which are known for improved accuracy. Whether internal or external, a microprocessor's clock cycle determines the frequency at which it will carry out commands. Modern clock speeds are measured in megahertz (MHz) and gigahertz (GHz).

Microprocessor architecture

The architecture of a microprocessor refers to various design and organization methodologies of the processor’s various CPU components. These are the key architectural elements of a microprocessor:

* Instruction Set Architecture (ISA): The microprocessor’s ISA defines the instruction set that the processor can perform. ISAs like the Reduced Instruction Set Computer (RISC) and Complex Instruction Set Computer (CISC) architectures provide various methods for data processing, offering varying levels of performance, reliability and speed suitable for different types of applications.

* Data path: A microprocessor’s data path dictates the order in which data moves through the microprocessor’s components (buses, ALU, registers), influencing overall performance.

* Control path: Similar to the data path, the control path element of a microprocessor’s architecture instructs the sequence of operations and manages data transmission within the CPU.

* Memory hierarchy: The memory hierarchy is a critical component of the processor’s architecture, providing a structure for different levels of memory (cache, registers, RAM) to optimize for efficient data access and retrieval speed.

Jai Ganesh · This is Cool

2481) New Guinea

Gist

The New Guinea bioregion, located in the Australasia realm, is the world's second largest island (after Greenland) separated from Australia by the Torres Strait. New Guinea and its surrounding islands make up the northernmost grouping of islands in Melanesia.

Summary

New Guinea is a big island north of Australia. It is the second largest island in the world. Geologically and biologically it is related to Australia. It was first surveyed by Alfred Russel Wallace in the 19th century, who noted that it was, like Australia, on the eastern side of the Wallace line. That means it is closer to Australia than to Indonesia in its flora and fauna.

On the east side of New Guinea is the country Papua New Guinea. On the west side of the island are the Indonesian provinces of Papua, Central Papua, Highland Papua, South Papua, Southwest Papua, and West Papua. These provinces together are called Western New Guinea. The Indonesian "capture" of western Papua New Guinea was a modern act by dictator Suharto of Indonesia. The Australian "capture" of the eastern half was meant to make sure the peoples of this part of Indonesia were left alone.

An early BBC David Attenborough program showed that the country was wooded with many groups of humans speaking many languages. The most notable animals still alive were the birds of paradise. Of marsupials, the quolls are notable. They are small, solitary carnivores. There are six species surviving, two in New Guinea and four in Australia. Echidnas are mammals also known as spiny anteaters.

The number of people on New Guinea is unknown. Indonesia and Papua New Guinea estimated the number around 2020. They say there are about 15 million people. However, the real number could be 23 million or more.

New Guinea is important for its nature and biology. Its largest marsupial, the Diprotodon, is now extinct. Native humans live in sparsely wooded, hilly ground in small groups which speak different languages. New Guinea has over 1000 languages. This is more languages than anywhere else in the world.

Still surviving are the birds of paradise, with marsupials, including wallabies and possums, and the egg-laying monotreme, the echidna. Other than bats and some two dozen indigenous rodents, there are no pre-human indigenous placental mammals. Pigs, several additional species of rats, and the ancestor of the New Guinea singing dog were introduced with human colonization.

Details

New Guinea (also known as Papua or historically Irian) is the world's second-largest island, with an area of 785,753 sq km (303,381 sq mi). It has the third-largest remaining rainforest globally, and the highest plant biodiversity of any island. Located in Melanesia in the southwestern Pacific Ocean, the island is separated from Australia by the 150-kilometre (81-nautical-mile; 93-mile) wide Torres Strait, though both landmasses lie on the same continental shelf, and were united during episodes of low sea level in the Pleistocene glaciations as the combined landmass of Sahul. Numerous smaller islands are located to the west and east. The island's name was given by Spanish explorer Yñigo Ortiz de Retez during his maritime expedition of 1545 because of the perceived resemblance of the indigenous peoples of the island to those in the African region of Guinea.

The eastern half of the island is the major land mass of the nation of Papua New Guinea. The western half, known as Western New Guinea, forms a part of Indonesia and is organized as the provinces of Papua, Central Papua, Highland Papua, South Papua, Southwest Papua, and West Papua. The two major cities on the island are Port Moresby and Jayapura.

Names

The island has been known by various names:

The name Papua was used to refer to parts of the island before contact with the West. Its etymology is unclear; one theory states that it derived from Tidore, the language used by the Sultanate of Tidore. An expedition by the Sultan of Tidore, together with Sahmardan, the Sangaji of Patani, and the Papuan Gurabesi, managed to conquer some areas in New Guinea, which was then reorganised to form Korano Ngaruha ("Four Kings") or Raja Ampat, Papoua Gam Sio (lit. "The Papua Nine Negeri"), and Mafor Soa Raha (lit. The Mafor "Four Soa"). The name comes from the words papo ("to unite") and ua (negation), which means "not united", i.e. an outlying possession of Tidore.

Anton Ploeg reports that the word papua is often said to be derived from the Malay word papua or pua-pua, meaning "frizzly-haired", referring to the very curly hair of the island's inhabitants. However Sollewijn Gelpke in 1993 considered this unlikely as it had been used earlier, and he instead derived it from the Biak phrase sup i babwa, which means "the land below [the sunset]", and refers to the Raja Ampat Islands.

When Portuguese and Spanish explorers arrived via the Spice Islands, they also used the name Papua. However, Westerners, beginning with Spanish explorer Yñigo Ortiz de Retez in 1545, used the name New Guinea, due to the resemblance between the indigenous peoples of the island and Africans of the Guinea region. The name is one of several toponyms sharing similar etymologies, ultimately meaning "land of the blacks" or similar meanings.

The Dutch, who arrived later under Jacob Le Maire and Willem Schouten, called it Schouten island. They later used this name only to refer to islands off the north coast of Papua proper, the Schouten Islands or Biak Island. When the Dutch colonized the main island as part of the Dutch East Indies, they called it Nieuw Guinea.

The name Irian was used in the Indonesian language to refer to the island and Indonesian province, as Irian Barat (West Irian) Province and later Irian Jaya Province. The name Irian was suggested during a tribal committee meeting in Tobati, Jayapura, formed by Soegoro Atmoprasodjo under governor J. P. van Eechoed, to decide on a new name because of the negative association of Papua. Frans Kaisiepo, the committee leader, suggested the name from Mansren Koreri myths, Iri-an from the Biak language of Biak Island, meaning "hot land" (referring to the climate), but also from Iryan which means heated process as a metaphor for a land that is entering a new era. In Serui Iri-an (lit. "land-nation") means "pillar of nation", while in Merauke Iri-an (lit. "placed higher-nation") means "rising spirit" or "to rise". The name was promoted in 1945 by Marcus Kaisiepo, brother of Frans Kaisiepo. The name was politicized later by Corinus Krey, Marthen Indey, Silas Papare, and others with the Indonesian backronym Ikut Republik Indonesia Anti Nederland ("Join the Republic of Indonesia Oppose the Netherlands"). Irian was used somewhat in 1972. The name was used until 2001, when Papua was again used for the island and the province. The name Irian, which was originally favored by natives, is now considered to be a name imposed by the Indonesian government.

Geography

New Guinea is an island to the north of the Australian mainland, south of the equator. It is isolated by the Arafura Sea to the west, and the Torres Strait and Coral Sea to the east. Sometimes considered to be the easternmost island of the Indonesian archipelago, it lies north of Australia's Top End, the Gulf of Carpentaria and Cape York Peninsula, and west of the Bismarck Archipelago and the Solomon Islands archipelago. Biologically, New Guinea may also be considered part of Australia, as there is a continuity of flora and fauna between the two countries.

Politically, the western half of the island comprises six provinces of Indonesia: Papua, Central Papua, Highland Papua, South Papua, West Papua and Southwest Papua. The eastern half forms the mainland of the country of Papua New Guinea.

The shape of New Guinea is often compared to that of a bird-of-paradise (indigenous to the island), and this results in the usual names for the two extremes of the island: the Bird's Head Peninsula in the northwest (Vogelkop in Dutch, Kepala Burung in Indonesian; also known as the Doberai Peninsula), and the Bird's Tail Peninsula in the southeast (also known as the Papuan Peninsula).

A spine of east–west mountains, the New Guinea Highlands, dominates the geography of New Guinea, stretching over 1,600 km (1,000 mi) across the island, with many mountains over 4,000 m (13,100 ft). The western half of the island contains the highest mountains in Oceania, with its highest point, Puncak Jaya, reaching an elevation of 4,884 m (16,023 ft). The tree line is around 4,000 m (13,100 ft) elevation, and the tallest peaks contain equatorial glaciers—which have been retreating since at least 1936. Various other smaller mountain ranges occur both north and west of the central ranges. Except in high elevations, most areas possess a warm humid climate throughout the year, with some seasonal variation associated with the northeast monsoon season.

Another major habitat feature is the vast southern and northern lowlands. Stretching for hundreds of kilometres, these include lowland rainforests, extensive wetlands, savanna grasslands, and some of the largest expanses of mangrove forest in the world. The southern lowlands are the site of Lorentz National Park, a UNESCO World Heritage Site. The northern lowlands are drained principally by the Mamberamo River and its tributaries on the western side, and by the Sepik on the eastern side. The more extensive southern lowlands are drained by a larger number of rivers, principally the Digul in the west and the Fly in the east. The largest island offshore, Dolak, lies near the Digul estuary, separated by a strait so narrow it has been named a "creek".

New Guinea contains many of the world's ecosystem types: glacial, alpine tundra, savanna, montane and lowland rainforest, mangroves, wetlands, lake and river ecosystems, seagrasses, and some of the richest coral reefs on the planet.

The entire length of the New Guinea Highlands system passes through New Guinea as a vast watershed. The northern rivers flow into the Pacific Ocean, the southern rivers into the Arafura Sea and the Gulf of Papua. On the north side, the largest rivers are the Mamberamo, Sepik and Ramu. Mamberamo was born from the confluence of two large inland rivers. Tariku comes from the west to the east and Taritatu from the east. These rivers meander through swamps with huge internal descents and then merge. The Mamberamo thus formed reaches the ocean by breaking through the Coastal Mountains. Mamberamo River is navigable to Marine Falls. The Sepik is a much more important river. Similarly, it collects water from a spacious pool. It is 1,100 kilometers from the Victor Emanuel Range to the estuary, making it the longest river in New Guinea. The winding, muddy, sluggish river can be navigated for 500 km. Ramu is a 650 km long river. Its lower section is navigable, but its upper flow is high-falling, fast-flowing. The energy of the river is used by a power plant near the city of Kainantu.

On the south side, the most significant rivers are Pulau, Digul, Fly, Kikori and Purari. The largest river in the western part of the island is Digul. It originates from the Star Mountains, which rise to an altitude of 4,700 m. The coastal plain is bordered by a swamp world hundreds of kilometers wide. Digul is the main transport route to the fertile hills and mountains within the island. The river Fly is born near the eastern branches of the Digul. It is named after one of the ships of the English Royal Fleet, which first sailed into the mouth of the river in 1845. The total length of the river is 1,050 km. Smaller boats can sail 900 km on the river. The estuary section, which decomposes into islands, is 70 km wide. The tide of the sea can have an effect of up to 300 kilometers. Strickland, a tributary of the Fly, reaches the Papuan Plain through wild gorges. Fly and Strickland together form the largest river in New Guinea. The many rivers flowing into the Gulf of Papua form a single delta complex. The rivers of the island are extremely rich in water due to the annual rainfall of 2,000–10,000 mm. According to a modest calculation, the New Guinea River carries about 1,500 {km}^{3}/a/(48,000 {m}^{3}/s) of water into the sea. Fly alone carries more water 238 {km}^{3}/a (7,500 {m}^{3}/s) than all the rivers in Australia combined.

Additional Information

New Guinea is an island of the eastern Malay Archipelago, in the western Pacific Ocean, north of Australia. It is bounded by the Pacific Ocean to the north, the Bismarck and Solomon seas to the east, the Coral Sea and Torres Strait to the south, and the Arafura Sea to the southwest. New Guinea is administratively divided into two parts: its western half comprises the Indonesian propinsi (or provinsi; provinces) of Papua and West Papua (collectively, formerly called Irian Jaya); and its eastern half comprises the major part of Papua New Guinea, an independent country since 1975.

New Guinea is the second largest island in the world, exceeded in size only by Greenland. It is about 1,500 miles (2,400 km) long (from northwest to southeast) and about 400 miles (650 km) wide at its widest (north to south) part. Area island, 317,150 square miles (821,400 square km). Pop. (2010) Papua and West Papua provinces including nearby islands, 3,593,803; (2011) Papua New Guinea excluding islands, 6,178,781.

Land

An unbroken chain of mountains with peaks above 13,000 feet (4,000 metres) in elevation extends across New Guinea from the northwest to the southeast, rising to 16,024 feet (4,884 metres) at Jaya Peak in western Papua province—the highest point in Indonesia. The summits of the chain are glaciated, and the mountains incorporate extinct volcanoes and elongated, fertile highland basins usually above 4,900 feet (1,490 metres) in elevation. To the north of the mountain chain is a deep structural trench occupied by the valleys of the Mamberamo, Sepik, Ramu, and Markham rivers. Fronting the north-central coastal plains of New Guinea is a series of fault-rimmed mountains that generally lie below 11,500 feet (3,500 metres). The mostly lowland Bomberai Peninsula and the more mountainous Doberai Peninsula constitute the extreme northwestern part of the island.

South of the central mountain chain is the Fly-Digul shelf, a vast swampy plain crossed by numerous rivers including the Fly, Bian, Digul, Mapi, Pulau, and Lorentz. To the southeast the Owen Stanley Range extends about 200 miles (320 km) and forms a wide peninsula, separating the Solomon Sea to the north from the Coral Sea to the south.

The climate of New Guinea is basically tropical, with mean annual maximum temperatures ranging between 86 and 90 °F (30 and 32 °C) in the lowlands; daytime temperatures in the highlands generally exceed 72 °F (22 °C) year-round. The southeast trade winds blow for about seven months each year, and rainfall on the southward-facing slopes of the central highlands frequently exceeds 300 inches (7,620 mm) annually. Consequently, the Fly-Digul shelf and bordering highlands are one of the world’s wettest places and also one of the least-inhabited. The central highlands receive rain throughout the year totaling between 100 and 160 inches (2,540 and 4,065 mm). Port Moresby on the southeastern coast receives only about 40 inches (1,000 mm) of rain per year.

New Guinea has a rich variety of plant life, including orchids, figs, and species of false beech. Mangrove swamps are found along the coastline almost everywhere. Farther inland mangroves are succeeded by nipa palms. Large stands of sago palms are found along the deltas and rivers of the southern coast. Primary lowland rainforest covers much of New Guinea up to about 3,300 feet (1,000 metres) above sea level. In the central highlands above 3,300 feet, stands of oak, beech, and pine are common. Wildlife includes many reptiles and such marsupials as the tree kangaroo and phalanger. Notable birds are the cassowary (a large, flightless bird), the spectacular birds of paradise, and parrots.

People

Almost the whole of New Guinea is occupied by speakers of Papuan languages, the original settlers of the island, who live mainly in the interior and southern sections. Papuan societies are characterized by leadership invested in local “big men” and by reciprocal gift giving. Ethnic composition is complex among the Papuans, who speak some 700 different languages. Constituting a small minority are communities of speakers of Austronesian (Melanesian) languages on the western, northern, and eastern coasts and on many of the affiliated offshore islands. There are also some Polynesians, Chinese, and Europeans. Several pidgins, such as Tok Pisin and Hiri Motu, are widely spoken; Indonesian (the official language of Indonesia) and English (the official language of Papua New Guinea) are also spoken. Although about two-thirds of Papua New Guinea’s population is Christian, traditional religious beliefs and rituals are still widely practiced.

Throughout most of the highland basins, much of the natural vegetation has been removed by the relatively intensive agriculture of the highlanders. The central highlands are the most densely populated part of the island. Swidden (slash-and-burn, or shifting) cultivation is practiced in the forested foothills to the north of the central highlands and in the grasslands of the Mamberamo and Sepik river basins, where the population is sparse. The north coast is also generally well populated.

Economy

Copper and gold are the main mineral resources of the island. One of the largest concentrations of copper in the world is at Tembagapura, about 25 miles (40 km) southwest of Mount Jaya in Papua. Another major deposit of copper has been developed just inside Papua New Guinea among the headwaters of the Fly River at Ok Tedi. Large amounts of gold also are produced at Ok Tedi. Petroleum is extracted in the Doberai Peninsula area of Papua and near Lake Kutubu in the central highlands of Papua New Guinea. Natural gas has been discovered in the Fly-Kikori area in Papua New Guinea.

The bulk of New Guinea’s population are subsistence farmers. Yams, taro, sago, and bananas are the lowland staple foods, and the sweet potato is the main highland food; pig husbandry is widespread. Cash crops in Papua New Guinea include coffee, cacao, copra, palm oil, tea, and rubber; skyjack tuna, prawns, and timber are also exported. Internal transport consists of a few secondary coastal roads, riverboats, and airways, with the latter becoming increasingly important.

History

New Guinea was possibly occupied as early as 50,000 years ago. By about 7000 bce sedentary agriculture with extensive swamp drainage and irrigation was practiced in the highland basins. The island, especially the western half, was known to Indonesian and Asian seafarers centuries before it was known to Europeans. The Portuguese in 1511 were the first Europeans to sight the island but made no landing until 1527.

The Dutch claimed the western half of the island in 1828 as part of the Dutch East Indies. In the 1870s Captain John Moresby of Great Britain surveyed the southeastern coast, and by 1884 the southeastern quadrant of New Guinea had been annexed by Great Britain. The German New Guinea Company took over administration of the northeast quadrant in the same year. The administration of British New Guinea was passed to Australia in 1904, and its name was changed to the Territory of Papua.

Following World War I, German New Guinea was taken over by Australia as a mandated territory of the League of Nations in 1921. After Japan temporarily occupied large parts of the island during the early years of World War II, Australia combined its administration of the Territory of Papua and the New Guinea mandate into the Territory of Papua and New Guinea. Also after the war, the western half of the island, then known as Irian Barat, was returned to Dutch control. Indonesia became independent in 1949, and a plebiscite was held in 1969 to decide Irian Barat’s future; as a result it was annexed to Indonesia. Papua New Guinea was granted independence within the British Commonwealth in 1975.

Jai Ganesh · Dark Discussions at Cafe Infinity

2419) Macfarlane Burnet

Gist:

Work

Our immune system protects us against attacks by microorganisms and rejects foreign tissue. Part of our immunity has a hereditary basis, but part of it is acquired and is not present in the fetus. In 1949 Macfarlane Burnet theorized that the ability to distinguish between one’s own and foreign tissue is not hereditary but is acquired during the fetus stage. The theory was substantiated when Peter Medawar succeeded in performing transplants of tissue between different mouse fetuses. The results had significance for organ transplants.

Summary

Sir Frank Macfarlane Burnet (3 September 1899 – 31 August 1985), usually known as Macfarlane or Mac Burnet, was an Australian virologist known for his contributions to immunology. He won a Nobel Prize in 1960 for predicting acquired immune tolerance. He also developed the theory of clonal selection.

Burnet received his Doctor of Medicine degree from the University of Melbourne in 1924, and his PhD from the University of London in 1928. He went on to conduct pioneering research in microbiology and immunology at the Walter and Eliza Hall Institute of Medical Research, Melbourne, and served as director of the Institute from 1944 to 1965. From 1965 until his retirement in 1978, Burnet worked at the University of Melbourne. Throughout his career he played an active role in the development of public policy for the medical sciences in Australia and was a founding member of the Australian Academy of Science (AAS), and served as its president from 1965 to 1969.

Burnet's major achievements in microbiology included discovering the causative agents of Q-fever and psittacosis; developing assays for the isolation, culture and detection of influenza virus; describing the recombination of influenza strains; demonstrating that the myxomatosis virus does not cause disease in humans. Modern methods for producing influenza vaccines are still based on Burnet's work improving virus growing processes in hen's eggs.

For his contributions to Australian science, Burnet was made the first Australian of the Year in 1960, and in 1978 a Knight of the Order of Australia. He was recognised internationally for his achievements: in addition to the Nobel, he received the Lasker Award and the Royal and Copley Medal from the Royal Society, honorary doctorates, and distinguished service honours from the Commonwealth of Nations and Japan.

Details

Sir Macfarlane Burnet (born Sept. 3, 1899, Traralgon, Australia—died Aug. 31, 1985, Melbourne) was an Australian physician, immunologist, and virologist who, with Sir Peter Medawar, was awarded the 1960 Nobel Prize for Physiology or Medicine for the discovery of acquired immunological tolerance, the concept on which tissue transplantation is founded.

Burnet received his medical degree in 1924 from the University of Melbourne and performed research (1925–27) at the Lister Institute of Preventive Medicine, London. After receiving his Ph.D. from the University of London (1928), he became assistant director of the Walter and Eliza Hall Institute of Medical Research at Royal Melbourne Hospital in 1934 and later (1944–65) was its director and professor of experimental medicine at the University of Melbourne. He was knighted in 1951.

Early in his career, Burnet conducted fundamental experiments with bacteriophages, and he developed a technique—now standard laboratory practice—of culturing viruses in living chick embryos. He increased knowledge of the way influenza viruses cause infection, and he carried out or was associated with research on myxomatosis, Murray Valley encephalitis, toxic staphylococcal infection, polio, psittacosis, herpes simplex, poxviruses, and Q fever. He isolated the causal organism of Q fever, Rickettsia burnetii (Coxiella burnetii).

Although Burnet’s work in virology was important, his most significant achievements in science were made in immunology. He helped unravel the question of how the vertebrate immune system learns to distinguish between its own cells and foreign materials (antigens), such as those of infectious agents, and how during development a vertebrate becomes able to tolerate those components belonging to itself—the concept called immunological tolerance. He also developed a model, called the clonal selection theory of antibody formation, that explains how the body is able to recognize and respond to a virtually limitless number of foreign antigens. The theory states that an antigen entering the body does not induce the formation of an antibody specific to itself—as some immunologists believed—but instead it binds to one unique antibody selected from a vast repertoire of antibodies produced early in the organism’s life. Although controversial at first, this theory became the foundation of modern immunology.

Among Burnet’s publications are Viruses and Man (1953), Principles of Animal Virology (1955), The Clonal Selection Theory of Acquired Immunity (1959), Immunological Surveillance (1970), and Credo and Comment: A Scientist Reflects (1979).

Jai Ganesh · This is Cool

Superconductivity

Gist

Superconductivity is a quantum mechanical phenomenon occurring in certain materials cooled below a specific critical temperature, characterized by exactly zero electrical resistance and the expulsion of magnetic fields (Meissner effect). It allows for lossless energy transmission and magnetic levitation. Key applications include MRI machines, particle accelerators, and maglev trains.

Superconductivity is when a material, cooled to very low temperatures, lets electricity flow through it with zero resistance, meaning no energy is lost as heat, and it also perfectly pushes away magnetic fields. Think of it like a perfect, frictionless highway for electrons, allowing current to flow forever without a power source once started, and even levitating magnets above it.

Summary

Superconductivity is a set of physical properties observed in superconductors: materials where electrical resistance vanishes and magnetic fields are expelled from the material. Unlike an ordinary metallic conductor, whose resistance decreases gradually as its temperature is lowered, even down to near absolute zero, a superconductor has a characteristic critical temperature below which the resistance drops abruptly to zero. An electric current through a loop of superconducting wire can persist indefinitely with no power source.

The superconductivity phenomenon was discovered in 1911 by Dutch physicist Heike Kamerlingh Onnes. Like ferromagnetism and atomic spectral lines, superconductivity is a phenomenon which can only be explained by quantum mechanics. It is characterized by the Meissner effect, the complete cancellation of the magnetic field in the interior of the superconductor during its transitions into the superconducting state. The occurrence of the Meissner effect indicates that superconductivity cannot be understood simply as the idealization of perfect conductivity in classical physics.

In 1986, it was discovered that some cuprate-perovskite ceramic materials have a critical temperature above 35 K (−238 °C). It was shortly found (by Ching-Wu Chu) that replacing the lanthanum with yttrium, i.e. making YBCO, raised the critical temperature to 92 K (−181 °C), which was important because liquid nitrogen could then be used as a refrigerant. Such a high transition temperature is theoretically impossible for a conventional superconductor, leading the materials to be termed high-temperature superconductors. The cheaply available coolant liquid nitrogen boils at 77 K (−196 °C) and thus the existence of superconductivity at higher temperatures than this facilitates many experiments and applications that are less practical at lower temperatures.

Details

superconductivity, complete disappearance of electrical resistance in various solids when they are cooled below a characteristic temperature. This temperature, called the transition temperature, varies for different materials but generally is below 20 K (−253 °C).

The use of superconductors in magnets is limited by the fact that strong magnetic fields above a certain critical value, depending upon the material, cause a superconductor to revert to its normal, or nonsuperconducting, state, even though the material is kept well below the transition temperature.

Suggested uses for superconducting materials include medical magnetic-imaging devices, magnetic energy-storage systems, motors, generators, transformers, computer parts, and very sensitive devices for measuring magnetic fields, voltages, or currents. The main advantages of devices made from superconductors are low power dissipation, high-speed operation, and high sensitivity.

Discovery

Superconductivity was discovered in 1911 by the Dutch physicist Heike Kamerlingh Onnes; he was awarded the Nobel Prize for Physics in 1913 for his low-temperature research. Kamerlingh Onnes found that the electrical resistivity of a mercury wire disappears suddenly when it is cooled below a temperature of about 4 K (−269 °C); absolute zero is 0 K, the temperature at which all matter loses its disorder. He soon discovered that a superconducting material can be returned to the normal (i.e., nonsuperconducting) state either by passing a sufficiently large current through it or by applying a sufficiently strong magnetic field to it.

For many years it was believed that, except for the fact that they had no electrical resistance (i.e., that they had infinite electrical conductivity), superconductors had the same properties as normal materials. This belief was shattered in 1933 by the discovery that a superconductor is highly diamagnetic; that is, it is strongly repelled by and tends to expel a magnetic field. This phenomenon, which is very strong in superconductors, is called the Meissner effect for one of the two men who discovered it. Its discovery made it possible to formulate, in 1934, a theory of the electromagnetic properties of superconductors that predicted the existence of an electromagnetic penetration depth, which was first confirmed experimentally in 1939. In 1950 it was clearly shown for the first time that a theory of superconductivity must take into account the fact that free electrons in a crystal are influenced by the vibrations of atoms that define the crystal structure, called the lattice vibrations. In 1953, in an analysis of the thermal conductivity of superconductors, it was recognized that the distribution of energies of the free electrons in a superconductor is not uniform but has a separation called the energy gap.

The theories referred to thus far served to show some of the interrelationships between observed phenomena but did not explain them as consequences of the fundamental laws of physics. For almost 50 years after Kamerlingh Onnes’s discovery, theorists were unable to develop a fundamental theory of superconductivity. Finally, in 1957 such a theory was presented by the physicists John Bardeen, Leon N. Cooper, and John Robert Schrieffer of the United States; it won for them the Nobel Prize for Physics in 1972. It is now called the BCS theory in their honour, and most later theoretical work is based on it. The BCS theory also provided a foundation for an earlier model that had been introduced by the Russian physicists Lev Davidovich Landau and Vitaly Lazarevich Ginzburg (1950). This model has been useful in understanding electromagnetic properties, including the fact that any internal magnetic flux in superconductors exists only in discrete amounts (instead of in a continuous spectrum of values), an effect called the quantization of magnetic flux. This flux quantization, which had been predicted from quantum mechanical principles, was first observed experimentally in 1961.

In 1962 the British physicist Brian D. Josephson predicted that two superconducting objects placed in electric contact would display certain remarkable electromagnetic properties. These properties have since been observed in a wide variety of experiments, demonstrating quantum mechanical effects on a macroscopic scale.

The theory of superconductivity has been tested in a wide range of experiments, involving, for example, ultrasonic absorption studies, nuclear-spin phenomena, low-frequency infrared absorption, and electron-tunneling experiments. The results of these measurements have brought understanding to many of the detailed properties of various superconductors.

Additional Information

At what most people think of as “normal” temperatures, all materials have some amount of electrical resistance. This means they resist the flow of electricity in the same way a narrow pipe resists the flow of water. Because of resistance, some energy is lost as heat when electrons move through the electronics in our devices, like computers or cell phones. For most materials, this resistance remains even if the material is cooled to very low temperatures. The exceptions are superconducting materials. Superconductivity is the property of certain materials to conduct direct current (DC) electricity without energy loss when they are cooled below a critical temperature (referred to as Tc). These materials also expel magnetic fields as they transition to the superconducting state.

Superconductivity is one of nature’s most intriguing quantum phenomena. It was discovered more than 100 years ago in mercury cooled to the temperature of liquid helium (about -452°F, only a few degrees above absolute zero). Early on, scientists could explain what occurred in superconductivity, but the why and how of superconductivity were a mystery for nearly 50 years.

In 1957, three physicists at the University of Illinois used quantum mechanics to explain the microscopic mechanism of superconductivity. They proposed a radically new theory of how negatively charged electrons, which normally repel each other, form into pairs below Tc. These paired electrons are held together by atomic-level vibrations known as phonons, and collectively the pairs can move through the material without resistance. For their discovery, these scientists received the Nobel Prize in Physics in 1972.

Following the discovery of superconductivity in mercury, the phenomenon was also observed in other materials at very low temperatures. The materials included several metals and an alloy of niobium and titanium that could easily be made into wire. Wires led to a new challenge for superconductor research. The lack of electrical resistance in superconducting wires means that they can support very high electrical currents, but above a “critical current” the electron pairs break up and superconductivity is destroyed. Technologically, wires opened whole new uses for superconductors, including wound coils to create powerful magnets. In the 1970s, scientists used superconducting magnets to generate the high magnetic fields needed for the development of magnetic resonance imaging (MRI) machines. More recently, scientists introduced superconducting magnets to guide electron beams in synchrotrons and accelerators at scientific user facilities.

In 1986, scientists discovered a new class of copper-oxide materials that exhibited superconductivity, but at much higher temperatures than the metals and metal alloys from earlier in the century. These materials are known as high-temperature superconductors. While they still must be cooled, they are superconducting at much warmer temperatures—some of them at temperatures above liquid nitrogen (-321°F). This discovery held the promise of revolutionary new technologies. It also suggested that scientists may be able to find materials that are superconducting at relatively high temperatures.

Since then, many new high-temperature superconducting materials have been discovered using educated guesses combined with trial-and-error experiments, including a class of iron-based materials. However, it also became clear that the microscopic theory that describes superconductivity in metals and metal alloys does not apply to most of these new materials, so once again the mystery of superconductivity is challenging the scientific community.

DOE Office of Science & Superconductivity

The DOE Office of Science, Office of Basic Energy Sciences has supported research on high-temperature superconducting materials since they were discovered. The research includes theoretical and experimental studies to unravel the mystery of superconductivity and discover new materials. Even though a complete understanding of the quantum mechanism is yet to be discovered, scientists have found ways to enhance superconductivity (increase the critical temperature and critical current) and have discovered many new families of high-temperature superconducting materials. Each new superconducting material offers scientists an opportunity to get closer to understanding how high-temperature superconductivity works and how to design new superconducting materials for advanced technological applications.

Superconductivity Facts

* Superconductivity was discovered in 1911 by Heike Kamerlingh-Onnes. For this discovery, the liquefaction of helium, and other achievements, he won the 1913 Nobel Prize in Physics.
* Five Nobel Prizes in Physics have been awarded for research in superconductivity (1913, 1972, 1973, 1987, and 2003).
* Approximately half of the elements in the periodic table display low temperature superconductivity, but applications of superconductivity often employ easier to use or less expensive alloys. For example, MRI machines use an alloy of niobium and titanium.

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Jai Ganesh · Dark Discussions at Cafe Infinity

Colorful Quotes

1. Your purpose is to make your audience see what you saw, hear what you heard, feel what you felt. Relevant detail, couched in concrete, colorful language, is the best way to recreate the incident as it happened and to picture it for the audience. - Dale Carnegie

2. You've got to remember even the Apple regeneration started with colorful iMacs. So let us first get the colorful iMacs. I think with what we're doing with Lumia, we're at that stage. I want to do good devices that people like, and then we will go on to doing the next thing and the next thing. - Satya Nadella

3. There are large numbers of people in India below the poverty line; there are large numbers of people who lead a meager existence. They want to find a little escape from the hardships of life and come and watch something colorful and exciting and musical. Indian cinema provides that. - Amitabh Bachchan

4. I never wanted to be the great guy or the colorful guy or the interesting guy. I wanted to be the guy who won titles. - Pete Sampras

5. We really have the most beautiful planet in our solar system. None other can sustain life like we know it. None other has blue water and white clouds covering colorful landmasses filled with thriving, beautiful, living things like human beings. - Sunita Williams

6. A lot of times I watch TV and I watch film and there's so many things I'd love to talk about that I feel don't get the opportunity to be shown. Sometimes things become very stereotypical and one-sided, and I feel like it's such a colorful world. - Alicia Keys

7. There are so many colorful characters in Florida. There's a lot of money, development - not all of it good - and corruption. - John Grisham.

Jai Ganesh · Jokes

Q: Why did the Oreo go to the dentist?
A: Because it lost its filling.
* * *
Q: What do you call an ant dipped in chocolate?
A: Decad-ant.
* * *
Q: What happens when you try to eat 5 candy bars at once?
A: Your gonna choke alot.
* * *
Q: What does it do before it rains candy?
A: It sprinkles!
* * *
Q: What do you call dancing chocolate bar?
A: Nestle Crunk bar.
* * *

Jai Ganesh · Science HQ

Chemical Equilibrium

Gist

Chemical equilibrium is the state in a reversible reaction where the rates of the forward and backward reactions are equal, resulting in constant concentrations of reactants and products over time. It is a dynamic process in a closed system where no net change occurs. The equilibrium constant quantifies the ratio of products to reactants.

Chemical equilibrium is the state in a reversible reaction where the rate of the forward reaction (reactants to products) equals the rate of the reverse reaction (products to reactants), resulting in constant, unchanging concentrations of both reactants and products over time, even though individual molecules are still reacting. It's a dynamic process, meaning reactions haven't stopped but are balanced, and is typically observed in a closed system, often shown with a double arrow in chemical equations.

Summary

In a chemical reaction, chemical equilibrium is the state in which both the reactants and products are present in concentrations which have no further tendency to change with time, so that there is no observable change in the properties of the system. This state results when the forward reaction proceeds at the same rate as the reverse reaction. The reaction rates of the forward and backward reactions are generally not zero, but they are equal. Thus, there are no net changes in the concentrations of the reactants and products. Such a state is known as dynamic equilibrium. It is the subject of study of equilibrium chemistry.

Historical introduction

The concept of chemical equilibrium was developed in 1803, after Berthollet found that some chemical reactions are reversible. For any reaction mixture to exist at equilibrium, the rates of the forward and backward (reverse) reactions must be equal. In the following chemical equation, arrows point both ways to indicate equilibrium.

Details

Chemical equilibrium is the condition in the course of a reversible chemical reaction in which no net change in the amounts of reactants and products occurs. A reversible chemical reaction is one in which the products, as soon as they are formed, react to produce the original reactants. At equilibrium, the two opposing reactions go on at equal rates, or velocities, and hence there is no net change in the amounts of substances involved. At this point the reaction may be considered to be completed; i.e., for some specified reaction condition, the maximum conversion of reactants to products has been attained.

Chemical equilibrium can be considered analogous to equilibrium in physical systems. For example, water in an insulated container with a temperature at the freezing point exists in both liquid and solid forms. The mass of the water does not change, but nevertheless there is physical activity with liquid water freezing onto the ice and ice melting back into liquid, with both processes occuring at the same time and at the same rate so the proportion of ice to water does not change.

The value of the equilibrium constant varies with the molar concentration, temperature, and pressure according to the principle of Le Chatelier, which states that any change in those conditions will change the equilibrium in such a way to counteract the effect of the change. For example, if the concentration of a reactant is increased, the reaction will proceed to convert the extra reactant into product until equilibrium is reached. If pressure increases, the forward reaction happens faster until a new equilibrium is reached. For increases in temperature, for an exothermic reaction (which releases heat), the equilibrium constant decreases, and the equilibrium constant increases for a endothermic reaction (which absorbs heat).

When the product and reactants are in the same phase (e.g, gas, liquid), the equilibrium is a homogeneous equilibrium. When the reactants are in different phase, such as salt (solid) dissolving in water (liquid), the equilibrium is a heterogenous equilibrium.

Solubility and equilibrium

The solubility product constant, Ksp, specifically describes the equilibrium between a solid ionic compound and its dissociated ions in a solution. For example for salt dissolving in water, the equilibrium constant Ksp does not include the concentration of the water, since water is not a product or a reactant, and thus the equilibrium constant is the concentrations of the sodium and chlorine ions divided by the concentration of the salt.

The solubility of an ionic compound is determined by various factors, including the common ion effect, which is a direct application of Le Chatelier’s principle. This principle relates to ionic equilibrium by explaining how changes in concentration, temperature, or pressure affect the equilibrium of reactions involving ions. The common ion effect occurs when an ion that is already present in a solution is added to the solution; the effect reduces the solubility of a weak electrolyte or suppresses the ionization of a weak acid or base.

For systems that are not in equilibrium, one can use the reaction quotient Q, which is calculated in the same way as the equilibrium constant K. If Q is greater than K, the reverse reaction happens, favoring the reactants until equilibrium is reached. If Q is greater than K, the forward reaction happens, favoring the products until equilibrium is reached.

Additional Information

Chemical equilibrium refers to the final mixture of a chemical reaction, where the reactants and products are done changing. In a chemical reaction, reactants are converted into products. A general belief is that all chemical reactions proceed to completion (where all reactants are converted into products). But this is not true in all cases. A lot of chemical reactions proceed only to a certain extent, i.e. the reactants are not fully converted into products and the resulting mixture contains both reactants and products. After some time, the concentration of reactants or products becomes constant and we get a state of equilibrium for the system.

Irreversible reaction

A chemical reaction which proceeds only in the forward direction so that the reactants are converted into products and products do not react with each other to reform reactants is called an irreversible reaction.

Reversible reaction

A chemical reaction in which reactants react together to form products and products formed react with each other directly to reform the original reactant back is known as a reversible reaction.

Characteristics of Chemical Equilibrium

These are some of the characteristics of chemical equilibrium:

* The chemical reaction should be reversible.
* The equilibrium can be attained only if the system is closed, i.e. the reaction should be carried out in a closed vessel.
* The opposing processes (i.e. forward and backward reactions) occur at the same rate and there is a dynamic but stable condition.
* The observable properties of the system such as concentration, pressure, color, etc. becomes constant at equilibrium and remains unchanged thereafter.
* By bringing a change in conditions such as temperature, pressure or concentration, the equilibrium point can be shifted to the right or left hand side as required. Thus the reaction can be controlled to get more yield of products.
* The equilibrium can be approached from either direction.
* A catalyst does not alter the equilibrium point. It only increases the rate of reaction. The equilibrium is attained however.

Jai Ganesh · Jai Ganesh's Puzzles

Hi,

#10719. What does the term in Biology Facultative anaerobic organism mean?

#10720. What does the term in Biology Family mean?

Jai Ganesh · Jai Ganesh's Puzzles

Hi,

#5915. What does the adjective jocose mean?

#5916. What does the noun joiner mean?

Jai Ganesh · Jai Ganesh's Puzzles

Hi,

#2554. What does the medical term Pallium (neuroanatomy) mean?

Jai Ganesh · Jai Ganesh's Puzzles

Hi,

#9839.

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