Archives October 2013

The stent, a mesh tube device designed to hold open blood vessels, has revolutionized management of coronary artery disease. The first successful stent was invented by Argentinian doctor Julio Palmaz (b. 1945). Palmaz had heard that blood vessels had a tendency to close up after balloon angioplasty, in which narrowed heart vessels are opened with a catheter. Pafma'z had the idea of puttihg a "scaffold" inside the vessels to prevent them from closing over. Palmaz began working on creating prototypes of an implantable stent, using simple materials such as copper wire and a soldering iron. He modeled the mesh with a structure of staggered openings he just happened to find lying on his garage floor. The design proved perfect—the structure was collapsible but remained rigid when inserted into the blood vessel. After testing his device on pigs and rabbits, Palmaz secured funding from the unlikely partnership of Phil Romano, a more...

"The fuse starts from the bottom ... (black powder), is compressed into it to form an explosive mine." Jiao Yu and Liu Ji, Fire Dragon Manual (c. 1368-1398) Land mines—explosive weapons triggered by pressure or proximity—have been in use for many hundreds of years, and as such their exact history is somewhat clouded. There is evidence to suggest, however, that the first self-contained land mines for military purposes were used in China in 1277 against Mongol invaders. Today their use has prompted great controversy, due to the high civilian casualties that can be caused many years after conflict has ended. The name "mine" is derived from their original use in Europe in the Middle Ages as "tunnel mines." During the siege of a castle or fort, tunnels would be dug under the walls and explosives detonated just beneath them in a bid to cause them to collapse. True anti-personnel land more...

Hydraulic means moved or operated by water or liquid and refers to a method of engineering that has-been used since records began. The ancient Chinese and Egyptians used water as a method of transport and the Romans relied heavily on-it to move weighty objects. The arrival of the hydraulic jack in 1851, therefore, was not especially novel, but it was extremely useful. Essentially, a jack is a device that is capable of lifting heavy objects with relative ease. Hydraulic jacks make use of Pascal's Law that, in simple terms, says that if there is an increase in pressure at any point in a container of liquid, there is an equal increase in pressure at every other point within the. container. Richard Dudgeon, Inc., was founded as a machine shop in New. York in the mid-1800s, and its owner, founder, and namesake Richard Dudgeon was given a patent in 1851 for more...

In India there are different communities living peacefully together with complete harmony. Though there are some differences of opinion all the communities’ celebrate their festivals with joy and feasts. Hindus celebrate Dussehra, Diwali and Holi etc. Christians Christmas Day, New Year's Day and Mohammedans enjoy Id-ul-Fitr and Id-ul-Zuha. Like certain sad moments in every community, Mohammmedans observe the Moharrum which is a sad occasion for them. The Moharrum, is observed to mourn the death of Hussain, the grandson of the holy prophet of Islam, Mohammad. Beautifully decorated Tazias are taken out in procession. The mourners march through the streets and roads of cities and towns. They sing funeral songs. A white beautiful horse covered with a scarlet sheet heads the procession. Generally the marchers beat their chests with their fists, a way of expressing their grief. Some are bold enough to ooze their blood out of their body by lashing more...

Every one who wants to become an engineer or doctor goes through this once in a life.Here are my tips to deal with itHow prepared are you?It comes down to two things, how many questions of exam level you have practiced so far and how many were you able to solve correctly. Questions of at least 20 different types would suffice.Decide now if want to drop a yearDropping a year to prepare again isn't necessarily bad. Many smart people take that call. You just need to know how prepared you are and whether that will take you through your exam. If not, drop a year and prepare well for board exams! Even if you decide to drop, take the entrance exam this year to get the feel.Still, how to do it along with boards?Understand that the basic concepts asked are the same only, application is different. So make sure that more...

THE first step in your preparation and your journey into one of the IITs is the belief in yourself that you have it in you to realise this dream. You will not reach far if you think getting into IIT is too tough for you and it is only for the super-smart. This is an absolutely wrong perception.A very crucial issue facing JEE aspirants is the problem of time management. Manage your time well. Give proper importance to all the three subjects i.e. Physics, Chemistry and Mathematics.  You also need proper study material which can guide you in the subjects. Lots of study material is available in the market for the JEE, including numerous books (both good and bad) and study material of various institutes (again, both good and bad). You must choose a good study material and stick to it. Switching from one book to another will harm your preparation.  more...

"A Worker may be the hammer's master, but the hammer still prevails...." Milan Kundera, writer Hammers—tools for striking or pounding—have been around for millions of years in the form of specially shaped stones used to break or shape other stones, bones, or wood. They are most commonly associated with woodworking. But after the invention of the nail, someone realized it would be very useful to be able to insert and remove nails with the same tool. Nails were valuable, and a carpenter who hammered one at the wrong angle would have rescued and reused it. Thus, the claw hammer was born. A claw hammer has a two-sided head attached to a handle and can be said to be roughly T-shaped. One side of the head is the striking surface and is usually flat. The other side is a rounded or angled wedge and is used for removing nails. Archeologists found more...

"Clothes make the man. Naked people have little or no influence in society." Mark Twain, More Maxims of Mark (1927) Around 400,000 years ago, Homo sapiens devised a solution to protect the vulnerable naked human body from the environment—clothes. Anthropologists believe the earliest clothing was made from the fur of hunted animals or leaves creatively wrapped around the body to keep out the cold, wind, and rain. Determining the date of this invention is difficult, although sewing needles made from animal bone dating from about 30,000 B.C.E. have been found by archeologists. However, genetic analysis of human body lice reveals that they evolved at the same time as clothing. Scientists originally thought the lice evolved 107,000 years ago, but further investigations placed their evolution a few hundred thousand years earlier. Clothing has changed dramatically over the centuries, although its ancient role as an outward indication of the status, wealth, and more...

“... people like to stare at: a flowing stream, a crackling fire, and a Zamboni clearing the ice." Charlie Brown, Peanuts character The Zamboni name is synonymous with ice rink resurfacing in the United States, although few people outside of ice-skating would recognize it. Frank Zamboni (1901-1988) was born just after the turn of the twentieth century to Italian immigrant parents. As a young man he worked on the family farm and as a mechanic in a local garage. Frank opened an ice-making plant, with his younger brother Lawrence, producing blocks of ice for refrigeration. When electrical refrigerators were invented in the mid 1930s, making the production of ice blocks redundant, the Zambonis transformed their ice-making equipment and expertise into an ice rink. "Iceland" proved a popular local attraction, with 150,000 visitors a year. Cleaning, or resurfacing, of the rink was a time-consuming business, requiring three men and taking an more...

Since Viagra® (sildenafil citrate)—the first oral drug to treat erectile dysfunction—went on sale ten years ago, more than 27 million men in 120 countries have been prescribed it for impotence. Initially the drug was designed to treat high blood pressure, but in clinical trials this use proved disappointing. One side effect, shyly reported by the healthy volunteers, was that the drug produced super-charged erections. It was known that sexual arousal messages from the brain spark the production of cyclic guanosine monophosphate (cyclic GMP), a chemical that relaxes the pelvic muscles and allows the penis to become engorged with eight times its normal supply of blood. Sildenafil suppresses an enzyme (phosphodiesterase type 5), whose normal role is to break down cyclic GMP and cause the erection to subside. Pharmaceutical company Pfizer conducted twenty-one randomized, placebo-controlled clinical trials involving more than 3,700 participants aged from nineteen to eighty-seven suffering from varying degrees more...