The Green Revolution :


The Green Revolution The impetus towards increased food production in the era following World War II was a result of a new population explosion. A so-called green revolution, involving selective breeding of traditional crops for high yields, new hybrids, and intensive cultivation methods adapted to the climates and cultural conditions of densely populated countries such as India, temporarily stemmed the pressure for more food. A worldwide shortage of petroleum in the mid-1970s, however, reduced the supplies of nitrogen fertilizer helpful to the success of the new varieties. Erratic weather and natural disasters such as drought and floods continue to reduce crop levels throughout the world.
Famine is still widespread in many parts of the developing world, particularly in Africa. These problems still determine the pace and nature of agricultural change and development. SeeEnvironment; Food Supply, World.

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A Tale of Two Cities :



Novel by Charles Dickens, first published in serial form in 1859 in Dickens’s own periodical All the Year Round. The second of Dickens’s two historical novels (see Barnaby Rudge), A Tale of Two Cities is largely event—rather than character—driven, and its tone is less comic than many of Dickens’s other works.
Set in London and Paris at the time of the French Revolution, the novel is critical both of mob violence and of the aristocratic abuses that prompted the revolution. The story begins with the release of Dr Manette, who has been imprisoned in the Bastille for 18 years. He travels to England to recover his health and his memory, and here his daughter, Lucie, marries Charles Darnay, nephew of the wicked Marquis de St Evremonde who imprisoned Lucie’s father. During the revolution, Darnay travels to Paris to save a faithful servant who has been accused of collusion with the aristocracy. Himself arrested, Darnay is only saved by the intervention of Sydney Carton, a barrister’s reckless son, who is devoted to Lucie. Carton’s remarkable likeness to Darnay enables the latter to escape, and the heroic Carton goes to the guillotine in his place: “It is a far, far better thing that I do, than I have ever done; it is a far, far better rest that I go to than I have ever known.”

FAMOUS PERSON QUOTATIONS IV :


Albert Einstein

Gravitation can not be held responsible for people falling in love.

Gravitation :



I INTRODUCTION
Gravitation, property of mutual attraction possessed by all bodies. The term “gravity” is sometimes used synonymously. Gravitation is one of four basic forces controlling the interactions of matter; the others are the strong and weak nuclear forces and the electromagnetic force (seePhysics). Attempts to unite these forces in one grand unification theory have not yet been successful (seeUnified Field Theory), nor have attempts to detect the gravitational waves that relativity theory suggests might be observed when the gravitational field of some very massive object in the universe is perturbed.
The law of gravitation, first formulated by Isaac Newton in 1684, states that the gravitational attraction between two bodies is directly proportional to the product of the masses of the two bodies and inversely proportional to the square of the distance between them. In algebraic form the law is statedwhere F is the gravitational force, m1 and m2 the masses of the two bodies, d the distance between the bodies, and G the gravitational constant.

The value of this constant was first measured by the British physicist Henry Cavendish in 1798 by means of the torsion balance. The best modern value for this constant is 6.67 × 10-11 N m2 kg-2. The force of gravitation between two spherical bodies, each with a mass of 1 kilogram and with a distance of 1 metre between their centres, is therefore 6.67 × 10-11 newtons. This is a very small force; it is equal to the weight (at the Earth’s surface) of an object with a mass of about 0.007 micrograms (a microgram is one millionth of a gram).


II EFFECT OF ROTATION
The measured force of gravity on an object is not the same at all locations on the surface of the Earth, principally because the Earth is rotating. The measured, or apparent, weight of the object is the force with which the object presses down on, for example, the pan of a spring scale. This is equal to the reaction force with which the pan presses upward on the object. Any object travelling at constant speed in a circle is constantly accelerating towards the centre of the circle (seeMechanics: Kinetics). This centre-directed acceleration has to be sustained by a centre-directed force, or centripetal force. In the case of the object being weighed at the Earth’s surface, the centripetal force is the result of the fact that the upward supporting force from the pan of the spring balance is slightly less than the object’s weight.


III ACCELERATION
Gravity is commonly measured in terms of the amount of acceleration that the force gives to an object on the Earth. At the equator the acceleration of gravity is 977.99 cm s-2 (centimetres per second per second) (32 9/100 ft s-2 ) and at the poles it is more than 983 cm s-2. The generally accepted international value for the acceleration of gravity used in calculations is 980.665 cm s-2 (32 1/6 ft s-2). Thus, neglecting air resistance, any body falling freely will increase its speed at the rate of 980.665 cm s-1 (32 1/6 ft s-1) during each second of its fall. The apparent absence of gravitational attraction during space flight is known as zero gravity or microgravity.

VOLCANO :



Volcano, fissure or vent through which molten rock material, or magma, and gases from the interior of the Earth erupt on to its surface, and the landform which is produced as a result of this eruption. The word “volcano” derives from Vulcano, one of the volcanic Lipari Islands in the Mediterranean Sea, and the place where, according to Roman mythology, Vulcan, the god of fire, kept his forge. The processes that create volcanoes and other volcanic structures are called volcanism or vulcanism.
As landforms, volcanoes are formed by the deposition of the magma that flows or is ejected, normally from one or several circular vents, as molten or solid material. Molten magma is known as lava when it reaches the Earth's surface; the solid material—classified as dust, ash, cinders, and bombs depending on size and shape—is called tephra. Volcanoes which form round circular vents are known as central volcanoes; the basin-like mouth of the vent is known as the crater. Most volcanoes tend to be conical in shape; some, however, are much larger structures with very gentle slopes. Often covering many square kilometres, they are known as shield volcanoes.
(For a detailed discussion of the processes which are involved in creating both conical and shield volcanoes, and of the various types of eruptions associated with them, see Volcanism.)
Some volcanoes are much more active than others. A few may be said to be in a state of permanent eruption, at least during the geological present. Stromboli, in the Lipari Islands, has been constantly active since ancient times; Izalco, in El Salvador, has been active since it first erupted in 1770. Other constantly active volcanoes are found in a belt, called the Ring of Fire, that encircles the Pacific Ocean.
Many other volcanoes, such as Vesuvius, in Italy, continue in a state of moderate activity and then become quiescent, or dormant, for periods ranging from months to centuries. The eruption that succeeds prolonged dormancy is usually violent. This was the case with the 1980 eruption, after 123 years of quiescence, of Mount St Helens in Washington state, United States. The massive eruption of Mount Pinatubo in the Philippines during June 1991 came after more than 600 years of dormancy.
For a long period after it has ceased to erupt either lava or tephra, a volcano continues to emit acid gases and vapour in what is called the fumarolic stage. After this phase, hot springs may arise from the volcano. Examples of this type of activity include the geysers of Yellowstone National Park in the United States, and of the central area of the North Island of New Zealand. Eventually, the last traces of volcanic heat may disappear; springs of cold water may issue from the volcano and from the ground in its vicinity.
After becoming inactive, a volcano is progressively reduced in size as a result of weathering and erosion. Finally, the cone may be obliterated, leaving only a volcanic pipe—a chimney filled with lava or tephra, and extending from the Earth's surface down to the former magma reservoir under the volcano. The diamond-rich mines of South Africa are found in volcanic pipes.

Geyser :



Geyser, hot spring that erupts intermittently in a column of steam and hot water. Some geysers erupt at regular intervals, but most erupt irregularly, the intervals ranging from a matter of minutes to years. The length of time of the eruption varies with the geyser, from seconds to hours. The height of the column ranges from about 1 m (3 ft) to about 100 m (328 ft), and the amount of water ejected in a single eruption varies from a few litres to hundreds of thousands of litres.
A geyser erupts when the base of a column of water resting in the Earth is vaporized by hot volcanic rock. The force with which the water column is expelled depends on its depth. The weight of the water column increases with its depth. The weight, in turn, increases the pressure exerted on the base of the column, thereby increasing the boiling point of the water there. When the water finally boils, it expands, driving some water out into the air. With the weight of the column reduced, the pressure correspondingly drops, and the boiling point of the water remaining in the column falls below its actual temperature. Thereupon, the entire column instantly vaporizes, causing the geyser to erupt.
Almost all known geysers are located in three countries of the world—New Zealand, Iceland, and the United States. The most famous geyser in the world is Old Faithful in Yellowstone National Park in the United States, which expels about 38,000 to 45,000 litres (10,000 to 12,000 gallons) at each eruption. Old Faithful erupts at intervals of between 37 and 93 minutes, its column rising to a height of between 38 and 52 m (125 and 170 ft). The geyser gives warning of its impending activity by ejecting jets of water 3 to 7.6 m (10 to 25 ft) high.
Eruption intervals depend on such variables as the supply of heat, the amount and rate of inflow of subsurface water, and the nature of the geyser tube and its underground connections.

Fiber :



While grocery shopping this weekend, I noticed the increasing number of products on the shelves that contain fiber. Gone are the days of grainy laxative drinks that are difficult to swallow or tolerate. There is now an array of fiber drinks and fiber-supplemented products, such as yogurt and breakfast cereals. With this in mind, it’s surprising to learn that most Americans consume only about 50 percent of the recommended daily fiber intake of 25 grams for a 2000-calorie diet.
Fiber is an important part of your diet. It has been linked to prevention of a number of diseases, including colon cancer and heart disease. In addition, adequate amounts of dietary fiber in the diet prevent constipation. Many dieters are increasing their fiber intake in an effort to add bulk to their diet, but in some instances fiber may also help to alter absorption of fat or cholesterol in the intestine. Studies have shown that this alteration in absorption may result in a decrease in LDL or “bad” cholesterol without affecting the HDL or “good” cholesterol, another great health benefit of fiber!
One word of warning: if you add sources of fiber to your diet, especially as part of a weight loss plan, be sure to increase your fluid consumption or you may notice signs of constipation.

FAMOUS PERSON QUOTATIONS III :



Hector Berlizo

Time is a great teacher , but unfortunately it kills its pupils.

Tide :



I INTRODUCTION
Tide, periodic rise and fall of all ocean waters, including those of open sea, gulfs, and bays, resulting from the gravitational attraction of the Moon and the Sun upon the water and upon the Earth itself.


II LUNAR TIDES
The Moon, being much nearer to the Earth than the Sun, is the principal cause of tides. When the Moon is directly over a given point on the surface of the Earth, it exerts a powerful pull on the water, which therefore rises above its normal level. Water covering the part of the Earth farthest from the Moon is also subject to this pull, so that another distinct dome of water is formed on the farther side of the Earth providing the basis for a second wave. The lunar wave crest directly beneath the Moon is called direct tide, and the crest on the side of the Earth diametrically opposite is called opposite tide. At both crests, the condition known as high water prevails, while along the circumference of the Earth perpendicular to the direct-opposite tidal axis, phases of low water occur.
Low and high waters alternate in a continuous cycle. The variations that naturally occur in the level between successive high water and low water are referred to as the range of the tide. At most shores throughout the world, two high waters and two low waters occur every lunar day, the average length of a lunar day being 24 hr, 50 min, and 28 sec. One of these high waters is caused by the direct-tide crest and the other by the opposite-tide crest. Two successive high waters or low waters are generally of about the same height. At various places outside the Atlantic Ocean, however, these heights vary considerably; this phenomenon, which is known as diurnal inequality, is not completely understood.



III SOLAR TIDES
The Sun likewise gives rise to two oppositely situated wave crests, but because the Sun is far from the Earth, its tide-raising force is only about 46 per cent that of the Moon. The sum of the forces exerted by the Moon and Sun result in a wave consisting of two crests, the positions of which depend on the relative positions of the Sun and Moon at the time. During the periods of new and full moon, when the Sun, Moon, and Earth are directly in line, the solar and lunar waves coincide. This results in the condition known as spring tides, in which the high water is higher and the low water lower than usual. When the Moon is in its first or third quarter, however, it is at right angles to the Sun relative to the Earth, and the height of the waves is subject to the opposing forces of the Sun and Moon. This condition produces neap tides, in which the high water is lower, and the low water higher, than normal. Spring and neap tides occur about 60 hr after the corresponding phases of the Moon, the intervening period of time being known as the age of the tide or age of the phase inequality. The interval of time between the crossing of a meridian by the Moon at one point and the next high water at that point is called the lunitidal interval, or the high-water interval for that point. The low-water interval is the period between the time the Moon crosses the meridian and the next low water. Average values for the high-water lunitidal intervals during periods of new and full moon are known as the establishment of a port. Values for the intervals during other periods of the month are often referred to as the corrected establishment.



IV TIDAL CURRENTS AND WAVES
Accompanying the vertical rise and fall of water are various horizontal or lateral movements commonly known as tidal currents or tidal streams, which are very different from the common ocean currents. In confined areas, a tidal current flows for about 6 hr, 12 min in an upstream or shoreward direction, corresponding to high water; it then reverses and flows for approximately the same time in the opposite direction, corresponding to low water. During the period of reversal, the water is characterized by a state of rest, or calm, known as slack water. A current flowing towards the shore or upstream is called flood current; that flowing in a direction away from land or downstream is known as ebb current.
At various times on the open sea gigantic waves, called tsunamis or tidal waves, strike the surrounding shore with tremendous force and cause considerable damage to life and property. These waves are not caused by natural tidal phenomena, but by earthquakes, midocean volcanic eruptions, and serious atmospheric disturbances.
Another related phenomenon is the seiche, which usually occurs in landlocked seas or lakes, such as San Francisco Bay in California and Lake Geneva in Switzerland. The water surface is observed to oscillate between a few centimetres and several metres mainly because of local variations in atmospheric pressure aided by high winds, but sometimes as a result of a distant seismic shock. The movement of water occurs in long waves and may last from a few minutes to several hours.



V TIDAL ENERGY
The energy of tides has been harnessed to produce electricity. In the summer of 1966, a tidal power plant with a capacity of 240,000 kw went into operation on the estuary of the River Rance in north-western France. The incoming tide of the river flows through a dam, driving turbines, and then is trapped behind the dam. When the tide ebbs, the trapped water is released and flows back through the dam, again driving the turbines. Such tidal power plants are most efficient if the difference between high and low tides is great, as in the Rance estuary, where the difference is 8.5 m (28 ft). The highest high tides in the world occur in the Bay of Fundy in Canada, where the difference between high and low tide is about 18 m (about 60 ft). The erection of a tidal power plant across Passamaquoddy Bay, an arm of the Bay of Fundy, has long been contemplated; however, the project has not yet been begun.

Cholera :



Cholera, severe infectious disease endemic to India and some other tropical countries and occasionally spreading to temperate climates. The symptoms of cholera are diarrhoea and the loss of water and salts in the stool. In severe cholera, the patient develops violent diarrhoea with characteristic “rice-water stools”, vomiting, thirst, muscle cramps, and, sometimes, circulatory collapse. Death can occur as quickly as a few hours after the onset of symptoms. The mortality rate is more than 50 per cent in untreated cases, but falls to less than 1 per cent with effective treatment.
The causative agent of cholera is the bacterium Vibrio cholerae, which was discovered in 1883 by the German doctor and bacteriologist Robert Koch. Virtually the only means by which a person can be infected is from food or water contaminated by bacteria from the stools of cholera patients. Prevention of the disease is therefore a matter of sanitation. Cholera epidemics swept through Europe and the United States in the 19th century but did not recur in those areas after improvement of the water supply. The connection between the disease and infected water sources was discovered by a London anaesthetist, Dr John Snow, during an epidemic that occurred in London in the 1850s, when he established that the source of infection came from contaminated water in a water pump in Broad Street.
Control of the disease is still a major medical problem in several Asian countries. The World Health Organization (WHO) estimates that 78 per cent of the population in developing countries is without clean water and 85 per cent without adequate faecal waste disposal. Epidemics of cholera occurred in 1953 in Calcutta, India; between 1964 and 1967 in South Vietnam; among Bangladeshi refugees fleeing to India during the civil war of 1971; and in Peru in 1991. The 1971 outbreak killed about 6,500 people.
Treatment consists mainly of intravenous or oral replacement of fluids and salts. Packets for dilution containing the correct mixture of sodium, potassium, chloride, bicarbonate, and glucose have been made widely available by WHO. Most patients recover in three to six days. Antibiotics such as tetracyclines, ampicillin, chloramphenicol, and trimethoprim-sulphamethoxazole can shorten the duration of the disease.
A vaccine made from dead bacteria is commercially available and offers partial protection for a period of three to six months after immunization. Experimental studies have shown that the cholera bacterium produces a toxin that causes the small intestine to secrete large amounts of fluid, which leads to the fluid loss characteristic of the disease. This has led to work on a vaccine containing inactivated toxin. Attempts are also being made to develop a vaccine containing live bacteria that have been altered so that they do not produce the toxin.

APRIL FOOL'S DAY :


April Fool's Day or All Fools' Day, falls on April 1. It is so called from the custom of playing harmless practical jokes on people or sending them on some fruitless errand on this day. The origin of the name is unknown but in France the April fool is called poisson d'avril (April fish) and in Scotland a “gowk” or cuckoo. The custom has been observed in many countries for centuries—in India, similar tricks are played at the Holi Festival (March 31)—and it has been suggested that, when New Year fell on March 25, April 1 was the last day of the eight-day festivities which celebrated this important event in the calendar.
It is recorded that one particularly elaborate hoax took place in London in 1860 when several hundred important people received invitations to watch the ceremony of the Washing of the White Lions at the Tower of London. Admission would be by the White Gate said the invitation card. On the day, crowds of people made their way to the Tower only to find that there was neither a White Gate nor any white lions.
April Fool's Day customs are still observed by both children and adults in English-speaking countries and elsewhere. In recent years, most newspapers, television stations, and broadcastng services have run an “April Fool's” story to hoax their audience.

Human Immunodeficiency Virus (HIV) :



I INTRODUCTION
member of the Retroviridae family of viruses (commonly known as retroviruses), and classified in the subfamily lentiviruses. Human infection with HIV results in a complex clinical disease known as acquired immune deficiency syndrome (AIDS), which may take ten years or more to develop. Three groups of scientists are credited with discovering HIV in association with AIDS: first in 1983 was Luc Montagnier’s group at the Pasteur Institute in Paris, followed by Robert Gallo’s group at the National Cancer Institute, and then a group headed by Jay Levy at University College San Francisco. The viruses have several common features: a long asymptomatic period before the onset of clinical disease, infection of blood cells and the nervous system, and an association with suppression of the immune system. Although no preventative AIDS vaccine as yet exists, scientists from Britain, France, and the United States announced in February 1999 that the source of the HIV virus is a subspecies of endangered chimpanzee, Pan troglodytes troglodytes, that is native to west Central Africa. It is believed that the virus passed from the chimpanzees—who have developed an immunity to the virus—via human beings hunting them for food.


II STRUCTURE
Retroviruses are classified by their unique feature: the need to convert their genomic RNA into DNA (the process of reverse transcription) using an enzyme that they carry (reverse transcriptase). The outer surface of HIV is a lipid “envelope” derived from the cell membrane. Protruding from the surface are the viral transmembrane glycoprotein (gp41) and the envelope glycoprotein (gp120) that allow HIV to bind and fuse with a target cell. Within the envelope, the viral core protein, p17, forms the matrix of the virion particle and the core protein, p24, forms an inner cylindrically shaped nucleoid. The nucleoid contains two strands of viral genomic RNA (the genetic material of HIV) and the associated reverse transcriptase enzyme.


III HOW HIV CAUSES INFECTION
HIV infects a human cell by binding its envelope glycoprotein gp120 to molecules on the surface of the cell. Only cells that carry the appropriate molecules are susceptible to infection by HIV. In the 1980s scientists quickly recognized that a molecule called CD4, which is found particularly on certain T-lymphocytes (a type of white blood cell), was the primary binding site, but it was only in 1996 that the other co-receptors were also identified. Fusion of the virus with the cell membrane permits the viral nucleoid to enter the cell.
One of the co-receptors is called chemokine receptor 5 (CKR5). Because of their inherited genetic make-up, about 14 per cent of Caucasians have unusually small numbers of these receptors on the surface of their cells and a smaller proportion do not express CKR5 on their cells at all, rendering these cells less susceptible to infection with HIV. Studies suggest that this may help to explain why some people appear to be resistant to HIV infection and remain HIV-negative despite multiple exposures to the virus, and why some HIV-positive people experience slower disease progression than others.
As HIV disease progresses, HIV variants called syncytium-inducing (SI) strains evolve within the individual’s body. SI variants can use an additional co-receptor on human cells, called fusin. This may allow HIV to infect a wider range of cells and may help to explain why the emergence of SI variants is associated with a worse prognosis. Again, a small proportion of Caucasians (about 1 per cent) do not produce this co-receptor.
Once fusion has taken place, reverse transcription then occurs to convert the viral genomic RNA into double-stranded DNA. The viral DNA is transported to the cell nucleus and is integrated, or inserted, into the normal cellular chromosomal DNA. When the right activation signals are present, the process of making new virions begins. Using the replication machinery of the host cell, the integrated viral DNA is transcribed to make messenger RNA (mRNA) and new strands of viral genomic RNA. The viral mRNA is then translated into new viral proteins and assembly of new virions takes place within the cell. The new HIV particles are released by budding from the cell surface, taking a piece of the cell membrane as their envelope.
HIV replication can directly kill CD4 T-lymphocytes. The loss of these cells paralyses the immune system and is one mechanism by which HIV infection causes AIDS. Recent advances in the management of HIV infection have led to the use of a new class of anti-retroviral drugs known as protease inhibitors. These drugs are enabling HIV-positive patients to live longer and experience an improved quality of life. As the protease enzyme is responsible for the maturation of newly formed HIV virion particles, inhibiting this enzyme has the effect of reducing the infectivity of the resultant virions.

DNA Fingerprinting :


I INTRODUCTION
DNA Fingerprinting, use of a person's body samples as a means of identification. Deoxyribonucleic acid (DNA) is a genetic blueprint found in the double strand or “double helix” of molecules called chromosomes located within the cell nuclei of all living beings. With the exception of identical twins, the complete DNA of each individual is unique.
In order to obtain a DNA “fingerprint”, DNA is first extracted from body tissue or fluid such as blood or saliva. Areas of DNA that can be used to distinguish one individual from another are segmented and arranged. Probes are used to mark the segments and X-ray film is placed on the probes and developed to form a pattern of black bars—the DNA “fingerprint”. DNA “fingerprints” are then compared for similarities.


II USES OF DNA FINGERPRINTING
DNA testing was originally developed for medical purposes in order to detect the presence of genetically inherited diseases. DNA fingerprinting, or DNA typing as it is often called, was first developed as an effective identification technique in 1985. The uses of DNA fingerprinting have expanded to include criminal investigations and forensic science. DNA fingerprinting was first used in a criminal investigation in the United Kingdom in 1987.
DNA evidence has a variety of applications in criminal investigations and forensic science. DNA evidence can confirm someone as a suspect to a crime by comparing DNA specimens found at a crime scene to a suspect's DNA. DNA evidence can also be used to exonerate a suspect.


III THE ADMISSIBILITY OF DNA EVIDENCE IN COURTS
Generally, courts have accepted the reliability of DNA testing and have admitted DNA test results into evidence. However, there have been criticisms of DNA fingerprinting for investigative or forensic purposes.


A
Accuracy of Results The accuracy of DNA fingerprinting has been challenged. First, because DNA segments rather than complete DNA strands are “fingerprinted”, there is a possibility that DNA samples taken from two individuals may yield identical results. For this reason, a finding that DNA fingerprints are identical is accompanied by the probability that the particular DNA pattern could appear in a particular segment of the population. As yet, widespread research confirming the uniqueness of DNA fingerprinting test results has not been conducted. In addition, because humans interpret the results there is always a possibility that mistakes will be made.


B
Prohibitive Costs Because DNA testing is expensive, suspects who are unable to provide their own DNA experts may not be able to adequately defend themselves if charges are brought against them based on DNA evidence and DNA experts are not provided for them. Furthermore, experts hired to testify either in support of or in opposition to the accuracy of DNA evidence may be biased.


C
Misuse of Results DNA fingerprint results may be used for unauthorized purposes such as to identify individuals with certain stigmatizing illnesses such as Acquired Immune Deficiency Syndrome (AIDS). The potential for misuse increases if DNA fingerprint results are databased.

FAMOUS PERSON QUOTATIONS II :


Mohammad Ali

When you're as great as I am , it's hard to be humble .

William Shakespeare :


I Introduction
Shakespeare, William (1564-1616), English poet and playwright, recognized in much of the world as the greatest of all dramatists.


II Life
A complete, authoritative account of Shakespeare’s life is lacking; much supposition surrounds relatively few facts. His day of birth is traditionally held to be April 23; it is known he was baptized on April 26, 1564, in Stratford-upon-Avon, Warwickshire. The third of eight children, he was the eldest son of John Shakespeare, a locally prominent merchant, and Mary Arden, daughter of a Roman Catholic member of the landed gentry. He was probably educated at the local grammar school. As the eldest son, Shakespeare ordinarily would have been apprenticed to his father’s shop so that he could learn and eventually take over the business, but according to one apocryphal account he was apprenticed to a butcher because of reverses in his father’s financial situation. In recent years, it has more convincingly been argued that he was caught up in the secretive network of Catholic believers and priests who strove to cultivate their faith in the inhospitable conditions of Elizabethan England. At the turn of the 1580s, it is claimed, he served as tutor in the household of Alexander Houghton, a prominent Lancashire Catholic and friend of the Stratford schoolmaster John Cottom. While others in this network went on to suffer and die for their beliefs, Shakespeare must somehow have extricated himself, for there is little evidence to suggest any subsequent involvement in their circles. In 1582 he married Anne Hathaway, the daughter of a farmer. He is supposed to have left Stratford after he was caught poaching in the deer park of Sir Thomas Lucy, a local justice of the peace. Shakespeare and Anne Hathaway produced a daughter, Susanna, in 1583 and twins—a boy and a girl—in 1585. The boy died 11 years later.
Shakespeare apparently arrived in London in about 1588, and by 1592 had attained success as an actor and a playwright. Shortly thereafter, he secured the patronage of Henry Wriothesley, 3rd Earl of Southampton. The publication of Shakespeare’s two fashionably erotic narrative poems Venus and Adonis (1593) and The Rape of Lucrece (1594) and of his Sonnets (published 1609, but circulated previously in manuscript) established his reputation as a gifted and popular Renaissance poet. The Sonnets describe the devotion of a character, often identified as the poet himself, to a young man whose beauty and virtue he praises and to a mysterious and faithless dark lady with whom the poet is infatuated. The ensuing triangular situation, resulting from the attraction of the poet’s friend to the dark lady, is treated with passionate intensity and psychological insight. They are prized for their exploration of love in all its aspects, and a poem such as “Sonnet 18” is one of the most famous love poems of all time.
While the poem may be familiar, it is less well known that it is an exquisite celebration of a young man’s beauty. The fact that 126 of the 154 sonnets are apparently addressed by a male poet to another man has caused some critical discomfort over the years. However, Shakespeare’s modern reputation is based mainly on the 38 plays that he apparently wrote, modified, or collaborated on. Although generally popular in his day, these plays were frequently little esteemed by his educated contemporaries, who considered English plays of their own day to be only vulgar entertainment.
Shakespeare’s professional life in London was marked by a number of financially advantageous arrangements that permitted him to share in the profits of his acting company, the Lord Chamberlain’s Company, later called the King’s Men, and its two theatres, the Globe Theatre and the Blackfriars. His plays were given special presentation at the courts of Elizabeth I and James I more frequently than those of any other contemporary dramatists. It is known that he risked losing royal favour only once, in 1599, when his company performed “the play of the deposing and killing of King Richard II“ at the request of a group of conspirators against Elizabeth. They were led by Elizabeth’s unsuccessful court favourite, Robert Devereux, 2nd Earl of Essex, and by the Earl of Southampton. In the subsequent inquiry, Shakespeare’s company was absolved of complicity in the conspiracy.
After about 1608, Shakespeare’s dramatic production lessened and it seems that he spent more time in Stratford. There he had established his family in an imposing house called New Place, and had become a leading local citizen. He died on April 23, 1616, and was buried in the Stratford church.


III Works
Although the precise date of many of Shakespeare’s plays is in doubt, his dramatic career is generally divided into four periods: the first period, involving experimentation, although still clearly influenced by or imitating Classical models; the second period, in which Shakespeare appears to achieve a truly individual style and approach; a third, darker period, in which he wrote not only his major tragedies but also the more difficult comedies, known as the “problem plays” because their resolutions leave troubling and unanswered questions; and his final period, when his style blossomed in the romantic tragicomedies—exotic, symbolic pieces which while happily resolved involve a greater complexity of vision.
These divisions are necessarily arbitrary ways of viewing Shakespeare’s creative development, since his plays are notoriously hard to date accurately, either in terms of when they were written or when they were first performed. Commentators differ and the dates in this article should be seen as plausible approximations. In all periods, the plots of his plays were frequently drawn from chronicles, histories, or earlier fiction, as were the plays of other contemporary dramatists... .

To be continued .

Here I'd like to thank MS. JAFARI helping me to manage the subjects at this weblog.

Asthma and Allergy on the March :


Asthma and Allergy on the March
In recent weeks we’ve seen that the hygiene hypothesis is the best explanation yet for why allergies and asthma are increasing worldwide. In this final entry on this topic, let’s examine the pros and cons of this theory.
Several findings provide the best evidence in favor of the hygiene hypothesis. One is that children raised in farm environments, where they’re exposed to bacterial products from farm animals at an early age, are far less likely to develop hay fever and asthma than children who grow up in cities. Another is that children placed in day care environments during the first six months of life, where they’re exposed to a high number of infections, are protected from developing asthma later on.
But other studies have not consistently supported this theory. Viral infections like hepatitis do not seem to be protective. The presence of cats or dogs in the home was found to be protective in some studies but not in others. Endotoxin levels (a bacterial by-product) in the homes of newborns do not seem to be linked to the infants’ risk of developing asthma. Finally, the use of antibiotics in the first year of life, presumably reflecting bacterial infections in these infants, is associated with a lower risk of developing asthma and allergies in some, but not all, studies. So the validity of the hygiene hypothesis is still a subject of disagreement among allergists and epidemiologists.
Does the theory have any implications for how you should act to minimize the likelihood that your children or children-to-be will develop of asthma and allergic disorders? Personally, I don’t think so, at least not yet. Moving to a farm, taking in domestic animals, or putting your child in day care with a lot of infections are pretty drastic undertakings for, at best, marginal benefits.
If the hygiene hypothesis is correct, these environmental changes could decrease by two- to fourfold the chance that your infant will develop asthma. Still, most of the risk for asthma actually comes from inherited predispositions and from the allergen content in the indoor home environment. We have no control over the genetics of our children, but we can minimize their exposure to dust mites, molds, and furry animals in our homes. Yet even this is easier said than done. Many efforts to reduce allergen exposure in early childhood have failed to demonstrate clinical benefits, in part because it’s nearly impossible to eliminate these major indoor allergens entirely from our homes.
For the time being, you can watch from a distance as this fascinating inquiry into a well-founded hypothesis to explain the epidemic of asthma and allergies continues. It will be some time before what’s being learned in our research translates into specific medical recommendations that may help to turn around this pandemic. Until then, research on how the early life experiences of individual infants can influence the development of asthma and allergies is likely to benefit the next generation.

Microphone :


Microphone, device used to transform sound energy into electrical energy in sound recording and reproduction. Microphones are a vital component of many kinds of communications systems and in instruments that measure sound and noise. The inventor Alexander Graham Bell built the first microphone in 1876 when he constructed his telephone transmitter.
The simplest type of modern microphone is the carbon microphone, used in telephones. This microphone consists of a metallic cup filled with carbon granules; a movable metallic diaphragm mounted in contact with the granules covers the open end of the cup. Wires attached to the cup and diaphragm are connected to an electrical circuit so that a current flows through the carbon granules. Sound waves vibrate the diaphragm, varying the pressure on the carbon granules. The electrical resistance of the carbon granules changes with the varying pressure, causing the current in the circuit to change according to the vibrations of the diaphragm. The varying current may either actuate a nearby telephone receiver or may be amplified and transmitted to a distant receiver. If the current variation is suitably amplified, it may also be used to modulate a radio transmitter.
Another common type, the crystal microphone, utilizes piezoelectric crystals, in which a voltage develops between two faces of the crystal when pressure is applied to the crystal—the piezoelectric effect. In this microphone sound waves vibrate a diaphragm, which in turn varies the pressure on a piezoelectric crystal. This generates a small voltage, which is then amplified.
Examples of dynamic microphones include ribbon microphones and moving-coil microphones. In ribbon microphones, a thin metallic ribbon is attached to the diaphragm and placed in a magnetic field. When sound waves strike the diaphragm and vibrate the ribbon, a small voltage is generated in the ribbon by electromagnetic induction. A moving-coil microphone operates on essentially the same principle but has a coil of light wire, instead of a ribbon, attached to the diaphragm. Some modern microphones, designed to pick up sound from one direction only, combine both ribbon and coil elements.
Another type of microphone is the condenser microphone. The condenser microphone has two thin metallic plates placed close to each other that serve as a capacitor. The back plate of the capacitor is fixed, and the front plate serves as the diaphragm. Sound waves alter the spacing between the plates, changing the electrical capacitance between them. By placing such a microphone in a suitable circuit, these variations may be amplified, producing an electrical signal. Condenser microphones can be very small. A common type of condenser microphone, the electret condenser microphone, is used in hearing aids.
Among the important characteristics of microphones are their frequency response, directionality, sensitivity, and immunity to outside disturbances such as shock or vibration.

Leap Year :


Leap Year, calendar year in which an extra day is added at the end of February, giving a total of 366 days instead of the usual 365. Leap years are necessary because the orbital period of the Earth around the Sun (on which the length of the year is based) is not an exact number of days—its actual length is 365.242 days. The rule for adding days to the Gregorian calendar (the one currently in use in most of the world) is that every fourth year is a leap year, but century years are not leap years unless they are divisible by 400. Hence, the year 2000 is a leap year but 1900 was not and 2100 will not be. This arrangement ensures that the calendar remains in step with the seasons.

Seven Wonders of the World :


Seven Wonders of the World
works of art and architecture regarded by ancient Greek and Roman observers as the most extraordinary structures of antiquity.

(1) The Pyramidsof Egypt, built at Giza during the 4th Dynasty (c. 2680-c. 2544 BC) are the oldest of the seven wonders and the only ones remaining relatively intact today.

(2) The Hanging Gardens of Babylon, perhaps built by King Nebuchadnezzar II about 600 BC, were a mountain-like series of planted terraces.

(3) The 12-m (40-ft) Statue of Zeus (mid-5th century BC) by the Greek sculptor Phidias was the central feature of the Temple of Zeus at Olympia, Greece.

(4) The Temple of Artemis at Ephesus in Greece (356 BC), which combined great size with elaborate ornamentation, was destroyed by the Goths in AD 262.

(5) The Mausoleum of Halicarnassus (c. 353 BC) was a monumental marble tomb, decorated by the leading sculptor of the age, for King Mausolus of Caria in Asia Minor; only fragments remain.

(6) The Colossus of Rhodes was a 30-m (100-ft) bronze statue of the Greek sun god Helios, erected about 280 BC to guard the entrance to the harbour at Rhodes; it was destroyed about 55 years later.

(7) The Pharos of Alexandria (c. 280 BC), located on an island in the harbour of Alexandria, Egypt, was a famous ancient lighthouse standing more than 134 m (440 ft) tall; it was destroyed in the 14th century.

FAMOUS PERSON QUOTATIONS I :


ALBERT EINSTEIN

Gravitation can not be held responsible for people falling in love.