Aug 31, 2013

Languages – their primitive and evolutionary development

Human beings are unique in their use of language. Only humans have the innate, hardwired ability to employ a large vocabulary of words with a complex grammar to create language itself. Linguistic abilities are surprisingly uniform across the entire human species, and all normal human beings learn to speak the language of their native community.

Many theories exist concerning when and how language began, and because there are no fossil records related to the earliest linguistic development, the true beginnings of spoken language are lost in time. Early cultures believed that language was a gift from the gods, and the origins of language are an integral part of creation myths throughout world mythology. Ironically, the diversity of language is usually seen as a curse - a punishment for human arrogance or disobedience – a belief best exemplified by the "Tower of Babel" passage in Genesis, in the Hebrew Bible.

Although some scholars assume there was a primitive language system dating as far back as two million years, fully developed language is thought to have been an evolutionary innovation of Homo sapiens, which facilitated the spread of the species around the globe. Many scientists believe that at some point in their evolutionary development, humans developed larger and more sophisticated brains that allowed for the development of language, although there is no agreement on when this occurred. Richard Leakey, the noted paleoanthropologist, suggests that Homo sapiens did not originally possess the necessary anatomy to produce language until 300,000 years ago, while Steven Pinker, the cognitive scientist, argues that because all modem humans have identical language abilities, language must have emerged with the first appearance of modern humans about 200,000 years ago.

Aug 30, 2013

Designing for the Space Environment

When designing vehicles for Earth orbit, the most important force to take into account is gravity, which causes both linear acceleration and rotational torque. For example, unless the space shuttle orbiter fires its maneuvering thrusters, gravity will inevitably turn the orbiter so that its nose is pointing down and one wing is pointing in the direction of travel. Building spacecraft to be durable means carrying extra weight into orbit, which is expensive, but the alternative - building a light, flimsy vehicle - is dangerous, because gravity could easily deform it.

Spacecraft designers also have to take into account harmful solar radiation. The Sun produces both electromagnetic radiation (EMR) and penetrating charged particles (PCPs). Earth's atmosphere protects life on the surface from the harmful effects of high-energy EMR, just as the planet's magnetic field shields surface life from dangerous PCPs; but in low Earth orbit, where the atmosphere is thin and the magnetic field is weak, these defenses are inadequate.

EMR travels through substances as well as empty space in waves of energy that move at the speed of light. Light is itself a form of EMR, which is generated by the vibration of charged particles. Radio waves and microwaves are relatively benign forms of low-energy EMR. On the other hand, at the high-energy end of the electromagnetic spectrum (above the range of visible light), EMR becomes ionizing, which means that it can alter the structure of molecules, including molecules of human DNA. Ultraviolet (UV) light and X-rays are examples of high-energy EMR against which astronauts and electronic equipment need to be protected.

Aug 29, 2013

How did the dandelion get its name?

Not surprisingly, the name refers to a part of the lion. In England, before the sixteenth century, the weed was called lion's tooth because of its serrated leaf's resemblance to the lion's incisor. Later, the French translation - dent de lion - was adopted into English and eventually became anglicized to "dandelion." (The Book of Answers, by Barbara Berliner)

Aug 28, 2013

Sultan Abdu’l-Aziz

Abdu’l-Aziz (1830-1876), was the 32nd sultan of the Ottoman Empire and 2nd sultan of the Tanzimat period of Ottoman reforms (1839-1876). This reform era was built on the changes instituted under Sultan Mahmud II, who sought to centralize and modernize government during his reign from 1808 to 1839. The Tanzimat period was inaugurated by Abdu’l-Aziz’s brother, Sultan Abdu’l-Medjid I. Abdu’l-Aziz succeeded Abdu’l-Medjid I to power in 1861. The reforms instituted by Abdu’l-Medjid and continued by Abdu’l-Aziz were numerous and affected many areas of the government, including the election of officials and military service. The reforms were supported by many countries throughout Europe. In the end, however, these reforms failed to contain nationalism or to stave off foreign aggression or internal corruption.

In administration, a highly centralized provincial organization and bureaucracy began to replace the old fief system. Central executive functions were gradually distributed to newly established councils of experts, which evolved from advisory councils to more modern ministries. In the field of justice, the "men of the Tanzimat," as the reformers were known, tried to assure security of life, honor, and property for all subjects, regardless of race, religion, or wealth. The old system of internal communal organization was preserved, but non-Muslim members, called rayas, were given legal equality with Muslims.

Aug 27, 2013

Ancient Astronomy

The roots of astronomy extend to before written records, but it is clear that humans have always observed the sky. The earliest known records of astronomical observations come from the Sumerian and Babylonian cultures (in what is modern-day Iraq) and date from as far back as 3000 B.C. Careful observations by court-sponsored astronomers led to the first known star maps, the zodiac, and many of the other constellations still referred to today, as well as the sexigesimal (base-60) counting system on which our angular measures are based.

Babylonian astronomers knew the length of the year to high precision. These measurements were probably used for political and agricultural purposes. During the same epoch, a number of astronomical monuments, including Stonehenge, were being constructed as calendar devices around what is now Great Britain. Egyptian astronomers undertook similar cataloging and mapping work, using stars as references in alignment of construction projects like the Great Pyramids.

Greek philosophers were the first to speculate on the structure of the universe, but were constrained by philosophical traditions relying on pure geometrical forms. Aristotle (ca.350 B.C.), established a model of the universe described as nested spheres with the Earth at the center, while the Sun, Moon, planets and stars moved around the Earth in constant motion each with its own rate.

Aug 26, 2013

Is the moon ever actually blue?

The moon does occasionally appear blue because of dust conditions in the atmosphere. The most famous widely observed blue moon of recent times occurred on September 26, 1950, owing to dust raised by Canadian forest fires. (The Book of Answers, by Barbara Berliner)

Aug 25, 2013

What was the distribution of radioactive fallout after the Chernobyl accident in Byelorussia?

Radioactive fallout, containing the isotope cesium 137, and nuclear contamination covered an enormous area including Byelorussia, Latvia, Lithuania, the central portion of the then Soviet Union, the Scandinavian countries, the Ukraine, Poland, Austria, Czechoslovakia, Germany, Switzerland, northern Italy, eastern France, Romania, Bulgaria, Greece, Yugoslavia, the Netherlands, and the United Kingdom. The fallout, extremely uneven because of the shifting wind patterns, extended 1,200 to 1,300 miles (1,930 to 2,090 kilometers) from the point of the accident. Roughly 5% of the reactor fuel or seven tons of fuel containing 50 to 100 million curies were released. Estimates of the effects of this fallout range from 28,000 to 100,000 deaths from cancer and genetic defects within the next 50 years. In particular, livestock in high rainfall areas received unacceptable dosages of radiation. (The Handy Science Answer Book, compiled by the Science and Technology department of the Carnegie Library of Pittsburgh)          

Aug 24, 2013

Charles Darwin and the Theory of Evolution

Charles Darwin, the son of a wealthy British doctor, was sent as a young man to study medicine in Edinburgh, then to Cambridge to study for the ministry. There he came under the influence of scientists and naturalists who inspired new interests in him. After a few years, his tutors suggested that he sail on a navy ship to South America, Australia, and various islands (most notably the Gblapagos, off the coast of Ecuador) to study the flora and fauna there.

Darwin's five-year voyage (1831-37) aboard the HMS Beagle would not only change his life, but the very way in which we understand life itself. It was on this trip that he made his first fossil discoveries, witnessed a volcanic eruption, and absorbed the concept of "deep time" explored in the recently published Principles of Geology by Charles Lyell. Darwin observed special adaptations organisms had for obtaining food and avoiding predators. He reasoned that organisms evolved from simpler states through what he called "survival of the fittest." Over time, he wrote, "the result of this [natural selection] would be the formation of a new species."

Aug 23, 2013

The single greatest risk factor for heart disease

Today, heart disease is the number one killer of Americans.[American Heart Association, Heart Attack and Angina Statistics, 1999] More people die from heart and blood vessel diseases each year in the United States than from all other causes of death combined.

What is the single greatest risk factor for heart disease? A high blood cholesterol level. [Roberts, William, "Atherosclerotic Risk Factors: Are There Ten or Is There Only One?", American Journal of Cardiology 64 (1989):552 ] And what is the single most important factor in raising blood cholesterol levels? The consumption of saturated fat. The correlations between cholesterol levels, saturated fat intake, and heart disease are among the strongest and most consistent in the history of world medical research. This is why every authoritative health body in the world, from the American Heart Association to the World Health Organization to the National Heart, Lung and Blood Institute, is calling for reductions in saturated fat consumption.

It is also, however, why the meat and dairy industries sometimes have not been happy with what has been learned. . . . (‘The Food Revolution: how your diet can help save your life and our world’, by John Robbins)

Aug 22, 2013

The invention of wristwatch

Two designers can claim to have invented the modern wristwatch: Louis Cartier (France), who in 1904 made one for the aviator Santos-Dumont; and, in the same year, Hans Wilsdorf (Switzerland), founder of Rolex. Earlier versions date back to around 1800, but they were essentially items of jewelry rather than a watchmaker's product. Wristwatches quickly achieved widespread popularity among women, but it was not until World War I that they were generally adopted by men. 
In 1910 Rolex produced the first wrist chronometer. 
(Inventions and Discoveries) 

Aug 21, 2013

The emergence of the science of Zoology

Some 2,300 years ago, the Greek philosopher Aristotle collected animals, dissected them, and wrote extensive descriptions of their anatomy. He grouped together animals with similar characteristics, described the social organization of bees, the embryological development of chickens, and distinguished whales and dolphins from fish. Modem scientists point to Aristotle as the father of the scientific method. In the centuries after Aristotle’s era, however, superstitions and fantasies about animals often buried facts. For example, after the fall of Rome, a book called the Physiologus by an unknown author examined 49 different animals (some fictional, such as the unicorn), giving each an allegorical interpretation. The Physiologus gained popularity as a teaching companion for the Bible and remained in widespread use for more than a thousand years.

In the 12th and 13th centuries, zoology - the study of animals and animal life - emerged as a science, driven by the work of the German scholar St. Albertus Magnus (ca. 1193-1280). Magnus rejected the superstitions associated with biology and reintroduced the work of Aristotle. In the 15th and 16th centuries, Leonardo da Vinci dissected and compared the structure of human and animals, establishing the concept of homology, the correspondence of parts in different kinds of animals.

Aug 20, 2013

The First Clock

The first "clock,” the gnomon, was invented in the 3rd millennium B.C. and has been attributed to both the Chinese and the Chaldeans. The gnomon was the precursor of the sundial, invented, according to some sources, by Anaximander of Miletus (Greece) in the 6th century B.C. and, according to others, by the Chinese and the Egyptians at a much earlier date.

The first artificial clock the water clock, or clepsydra, appeared at about the same time. The Egyptians in 3000 used the clepsydra alongside the sundial. (Inventions and Discoveries)

Aug 19, 2013

The numbering system used for U.S. Highways

Odd-numbered highways move north and south, while those with even numbers move east and west. Highways with one- or two-digit numbers are through routes, often long ones used for distance driving. Three-digit routes that begin with an even number are usually beltways around a city. Three-digit routes that begin with an odd number are spur routes in a city or town. (The Book of Answers, by Barbara Berliner)

Aug 18, 2013

Who invented the peace symbol?

It was created in 1958 as a nuclear disarmament symbol by the Direct Action Committee, and it was first shown that year at peace marches in England. The forked symbol is actually a composite of the semaphore signals N and D, representing nuclear disarmament. (The Book of Answers, by Barbara Berliner)

Aug 17, 2013

What's in a Face? - male mandrill

The male mandrill beats even the king vulture in the colorful face category. The mandrill, a kind of baboon, is an endangered species found in the rain forests of Africa. Only the males sport these vivid red and blue markings. (Grolier New Book of Knowledge Encyclopedia)

Aug 16, 2013

The five qualities that happy families have

Modern living puts a strain on family harmony, but there are things we can do to keep the home fires burning brightly. Experts point to at least five qualities that happy families have:
• love
• appreciation for each other
• open communication
• a willingness to spend time together
• strong leadership

Most specialists say that a loving family starts with a loving marriage. It's the flame that lights the stove that warms the house. "The family is a by-product of the relationship between husband and wife," says Daniel Araoz, Ed.D., past president of the Academy of Psychologists in Marital Sex and Family Therapy, a division of the American Psychological Association.

"The family will stay strong only if the couple keeps the original motivation that brought them together," he says. "They need to feel they are happier together than they are alone, and that they accept each other as they accept themselves. If a couple has those feelings, they'll be passed along to the children."

Aug 15, 2013

Broad functional components of human brain

('Boost Your Brain Power', by Ellen Michaud, Russell Wild and the editors of Prevention Magazine)

Aug 14, 2013

keeping brain drain at bay

If you need another reason to eat right and exercise, remember this one: These habits will not only keep your body in shape but may also preserve your memory and mental clarity.

Take the oldest diet advice you've ever heard: Eat your vegetables. Researchers at Chicago's Rush Institute for Healthy Aging found that people over 65 who consume about four servings per day slow cognitive decline by 38 percent. The same researchers found that eating fish as infrequently as once a week may lower the risk of Alzheimer's disease by up to 60 percent.

Jogging, swimming, and other forms of aerobic exercise-essential to any disease prevention plan - appear to protect the brain, too. One study of nearly 19,000 women found that the most active participants were the least likely to show signs of memory loss or fuzzy thinking. Studying, reading, and other mental challenges are also linked to a lower risk of dementia. The same is true of coping effectively with emotional stress.

Need further motivation? In a recent study, UCLA researchers asked a group of volunteers to eat healthy diets, exercise, perform brain teasers and memory exercises, and practice stress-reduction techniques. After two weeks, the participants improved their scores on word tests, and MRI scans showed that their brains worked more efficiently. The study's lead author, Gary W. Small, MD, director of the UCLA Center on Aging, concludes, "Living a healthy lifestyle can have an impact." (‘Simple Health Secrets’, by Reader’s Digest)

Aug 13, 2013

America’s Other Eagle

Though wise in so many ways, America's Founding Fathers were perhaps poor judges when it came to birds. By an act of Congress in 1782, they chose to adorn the Great Seal of the United States with the bald eagle, an undeniably beautiful bird, but also a mere scavenger and catcher of fish.

Presumably, the members of the Continental Congress sought a symbol of courage and independence to match their hopes for the infant republic; undoubtedly, they wanted a bird embodying the splendor of the new nation and its magnificent virgin lands. So how come they overlooked a choice as good as gold - the golden eagle, that is?

America's "other eagle" is more aggressive, more numerous, more skilled as a hunter, and even a bit larger than its white-headed cousin. Yet it has traditionally been overshadowed by the national symbol. Many Americans, particularly people in parts of the East, where the golden eagle infrequently flies, may not even know the bird exists. Meanwhile, in some areas of the West, the creature's taste for mutton long ago earned it the enmity of sheep ranchers. Today a symbol of the country's wide-open spaces, the magnificent raptor is also a lightning rod for controversy.

Weighing up to 13 pounds (6 kilograms) and with a wingspan of 7 feet (2 meters) or more, the golden eagle is one of the world's largest birds of prey. In North America the only larger raptor is the nearly extinct California condor, now confined to zoos. With that great size comes power, "truly awesome power," in the words of Mike Kochert, research leader at the Snake River Birds of Prey Area in Idaho. "Some smaller raptors may be more aggressive, but for pure energy on the wing," he says, " the golden eagle is tops. "

Aug 12, 2013

Early Music (4000 B.C. - 400 A.D.)

Archeological findings of ancient instruments demonstrate that humans have made music from the earliest times. While we don't know how this early music sounded, it's clear that Western music, as we know it, evolved from ancient Near Eastern culture.

Ancient Egyptian society regarded music as a gift from the gods. The appearance and the sound of early musical instruments had symbolic significance in Egyptian culture, where music played an important role in religious practice.

Some of the earliest-known instruments were stringed harps and lutes, known to be played in Egypt as early as 4000 B.C.; lyres and double clarinets were played as early as 3500 B.C. and percussion instruments were added to Egyptian orchestral music ca. 2000 B.C., while the tambourine was known to be used by the Hittites ca. 1500 B.C., along with the guitar, lyre, and trumpet.

All ancient Mesopotamian societies - including the kingdoms of Akkadia, Assyria, Babylonia, Chaldea, and Sumeria - made music central to their religious rites and festivals. Starting around 1800 B.C., Babylonian liturgical services were known to include a variety of psalms and hymns. The musical style was antiphonal, with two different voices alternating in chant. Instruments of the time included harps, flutes, drums, and lyres.

Aug 11, 2013

The 1960s – a time of dramatic political and cultural upheaval

The 1960s were a time of dramatic political and cultural upheaval both in the United States and around the globe. Many date the decade's true cultural beginning to November 22, 1963, when President John E Kennedy was assassinated in Dallas, Texas. Kennedy's shocking murder seemed to be the starting point of one of the nation's most turbulent eras, a time marked by further assassinations, urban riots, mass protests, failed presidencies, an unpopular war, and new demands for equal rights and social justice. In that sense, the tumult of the 1960s did not truly end until noon on Aug. 9, 1974, when Richard Nixon became the first U.S. president to resign his office in the wake of the Watergate scandal.

It was Kennedy himself who detected change in the air as he sought to become the nation's first Roman Catholic president in 1960. Kennedy's campaign was based on an explicit critique of the 1950s and the gray-flannel administration of President Dwight D. Eisenhower. Kennedy, as the Democratic Party's nominee, argued that it was time to get the country moving again, a sentiment that many young people - the advance guard of that giant cohort known as the "baby boom” - shared.

But in fields far removed from the campaign trail, the country was already moving in a new direction. Leading the way were thousands of ordinary African Americans who were demanding an end to blatant discrimination in the South and equal justice throughout the country. The civil rights movement was already a powerful force by the time the calendar turned from 1959 to 1960. The new decade ushered in not the movement’s birth but its maturity. (The New York Times ‘Smarter by Sunday – 52 Weekends of Essential Knowledge for the Curious Mind’)

Aug 10, 2013

Is an airplane’s black box actually black?

No, it is orange. Inside the box, a stainless-steel tape contains information on the airspeed, altitude, and vertical acceleration. A second orange box contains a tape of the last half-hour of conversation in the cockpit. (The Book of Answers, by Barbara Berliner) 

Aug 9, 2013

What language contains the most words?

English is the wordiest language, with approximately 455,000 active words and 700,000 dead words. (The Book of Answers, by Barbara Berliner)

Aug 8, 2013

The many health benefits of garlic

Garlic is an herb. It is best known as a flavoring for food. But over the years, garlic has been used as a medicine to prevent or treat a wide range of diseases and conditions. The fresh clove or supplements made from the clove are used for medicine.

Garlic is used for many conditions related to the heart and blood system. These conditions include high blood pressure, high cholesterol, coronary heart disease, heart attack, and “hardening of the arteries” (atherosclerosis). Some of these uses are supported by science. Garlic actually may be effective in slowing the development of atherosclerosis and seems to be able to modestly reduce blood pressure.

Some people use garlic to prevent colon cancer, rectal cancer, stomach cancer, breast cancer, prostate cancer, and lung cancer. It is also used to treat prostate cancer and bladder cancer.

Garlic has been tried for treating an enlarged prostate (benign prostatic hyperplasia; BPH), diabetes, osteoarthritis, hayfever (allergic rhinitis), traveler's diarrhea, high blood pressure late in pregnancy (pre-eclampsia), cold and flu. It is also used for building the immune system, preventing tick bites, and preventing and treating bacterial and fungal infections.

Other uses include treatment of fever, coughs, headache, stomach ache, sinus congestion, gout, rheumatism, hemorrhoids, asthma, bronchitis, shortness of breath, low blood pressure, low blood sugar, high blood sugar, and snakebites. It is also used for fighting stress and fatigue, and maintaining healthy liver function.

Aug 7, 2013

Animal products and heart disease

When it comes to heart disease, the evidence against animal products has today become so convincing and so thorough that even many in the livestock industry can see the handwriting on the wall. Dr. Peter R. Cheeke is a professor of animal science at Oregon State University and serves on the editorial boards of the Journal of Animal Science and Animal Feed Science and Technology. In his widely used animal science textbook, he says,

"Many studies, involving hundreds of thousands of people, have shown . . . a positive relationship between coronary heart disease and serum (blood) cholesterol. The higher the serum cholesterol, the higher the risk for coronary heart disease. Populations in which the average serum cholesterol level is (low) . . . are those on the lower end of the per capita meat consumption scale, while those (with high cholesterol levels) are populations with high intakes of animal products. . . . It's more useful to the livestock industries and animal scientists to come to grips with the demonstrated relationships among saturated fat and cholesterol intakes and coronary heart disease, than to claim that there is no relationship or that there's some sort of conspiracy against animal products by the medical community." (‘The Food Revolution: how your diet can help save your life and our world’, by John Robbins) 

Aug 6, 2013

The reason why twenty-one is considered the age of legal adulthood

The practice grew out of British common law. Before the Norman invasion, thirteen or fourteen was considered the age of adulthood, at least among the nobility. But during battles, it was observed that thirteen – and fourteen-year-old nobles were not large or strong enough to carry the heavy armor and lance used in fighting. The age was changed to nineteen and then raised to twenty-one, because nineteen-year-olds who inherited estates did not gain their property until two years later, owing to the lengthy legal processes involved. (The Book of Answers, by Barbara Berliner)

Aug 5, 2013

Emergence of modern European novel

While fiction has been a part of Western culture since the time of Homer and the ancient Greeks, the modem European novel did not emerge until the early 17th century. Derived from the Italian word novella, the term novel implied the newness of the form. In other European languages, the novel is known as a roman, which refers to the romances of the medieval period. At its most basic level, a novel is defined as an extended prose narrative. The modem elements of the novel include characterization, plot, and theme.

The novel first appeared in Spain in the form of Miguel de Cervantes's two-volume work, Don Quixote de la Mancha (1605-15). Written in the picaresque (from picaro or "rogue”) style, it depicts in episodic form the adventures of a poor, roguish hero as he travels throughout Spain, surviving by his wits. About 50 years after appearing in Spain, the novel became popular in Germany, then France, England, and much later, Russia. (The New York Times ‘Smarter by Sunday – 52 Weekends of Essential Knowledge for the Curious Mind’)

Aug 4, 2013

The ideal ratio of total cholesterol to HDL

Another important risk factor in determining your risk of heart disease is the ratio of your total cholesterol to your HDL (highdensity lipoprotein) level. The higher the ratio, the greater your danger of heart disease. The ideal ratio of total cholesterol to HDL is 3.0 to 1 or lower. The average American male's ratio is 5.1 to 1." The average vegetarian's ratio, on the other hand, is 2.9 to 1." (‘The Food Revolution: how your diet can help save your life and our world’, by John Robbins)

Aug 3, 2013

Why is radon a hazard?

Radon is a colorless, odorless, tasteless, radioactive gaseous element produced by the radioactive decay of radium. Its three naturally occurring isotopes are found in many natural materials, such as soil, rocks, well water, and building materials. Because the gas is continually released into the air, it makes up the largest source of radiation that, humans encounter. Some believe that radon may be a significant cause of cancer, especially lung cancer. It has been estimated that radon may cause as much as l0%, or 5,000 to 20,000 cases, of lung cancer deaths annually. Smokers seem to be at a higher risk than nonsmokers. The Environmental Protection Agency (EPA) recommends that the level should not be more than 4 picocuries per liter. The estimated national average is 1.5 picocuries per liter. Because EPA's "safe level" is equivalent to 200 chest x-rays per year, others believe that lower levels should be established. The American Society of Heating, Refrigeration, and Air-Conditioning Engineers (ASHRAE) recommends 2 picocuries/liter. The EPA estimates that nationally 8% to 12% of all houses are above the 4 picocuries/liter; whereas in another survey in 1987, it was estimated that 21% of homes were above this level. (The Handy Science Answer Book, compiled by the Science and Technology department of the Carnegie Library of Pittsburgh)

Aug 2, 2013

Cholesterol and its effect on one’s health

Cholesterol is the complex alcohol constituent of all animal fats and oils. It can be activated to form vitamin D. Cholesterol is one of a group of compounds known as sterols and is related to such other sterols as the sex hormones and the hormones of the adrenal cortex.

A close relationship exists among levels of blood cholesterol in the body, those of other fats or lipids, and the development of atherosclerosis. In this disorder, plaques containing cholesterol are deposited on the walls of arteries, particularly those of small and medium size, reducing their inside diameter and the flow of blood. Clotting of blood, such as may occur in the coronary arteries to cause a heart attack, is most likely to develop at places where arterial walls are roughened by such plaques.

Although many foods, particularly dairy products and meat fat, contain cholesterol, the body also synthesizes this sterol from cholesterol-free substances. Nevertheless, investigation indicates that a cholesterol-rich diet causes abnormally high levels of cholesterol and the related fats and lipids in the blood. Evidence strongly indicates that people with such high levels are more likely to develop atherosclerosis and heart attacks than those with lower levels. Also significant is the fact that scientists have identified two forms of cholesterol-carrying proteins in the blood, called high-density and low-density lipoproteins. The low-density form is thought to promote atherosclerosis, whereas the high-density component may retard it. In 1984, the United States National Heart, Lung and Blood Institute reported results of a study indicating that high levels of low-density lipoproteins also increased the risk of heart attacks and heart disease. (Encarta encyclopedia)

Aug 1, 2013

Why is exposure to asbestos a health hazard?

Exposure to asbestos has long been known to cause asbestosis. This is a chronic, restrictive lung disease caused by the inhalation of tiny mineral asbestos fibers, which, scar lung tissues. Asbestos has also been linked with cancers of the larynx, pharynx, oral cavity, pancreas, kidneys, ovaries, and gastrointestinal tract. The American Lung Association reports that prolonged exposure doubles the likelihood that a smoker will develop lung cancer. It takes cancer 15 to 30 years to develop from asbestos. These, fibers were used in building materials between 1900 and early 1970s as insulation for walls and pipes, as fireproofing for walls and fireplaces, in soundproofing and in acoustic ceiling tiles, as a strengthener for vinyl flooring and joint compounds, and as a paint texturizer. Asbestos poses a health hazard only if the tiny fibers are released into the air, but this can happen with any normal fraying or cracking. Asbestos removal aggravates this normal process and multiplies the danger level - it should only be handled by a contractor trained in handling asbestos. Once released, the particles can hang suspended in the air for more than 20 hours. (The Handy Science Answer Book, compiled by the Science and Technology department of the Carnegie Library of Pittsburgh)