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Monday, March 31, 2008

What is Ultrasound Scanning.

Ultrasound scanning is used to analyze the structure of internal organs, muscle and their size. Ultrasound scanning (Obstetrical ultrasound) is commonly used to scan and analyze the pregnancy period. Ultrasound scanners operating frequency is between two to eighteen mega hertz. Lower frequencies also uses in scanning to get deeper image from body. The Ultrasound scanner operators are called sonographers. A gel is applied on the body of patient before scanning, a probe called transducer produces ultrasound frequency. This probe directly placed on the patient and ultrasound passes from the transducer through the applied water based gel to body. Mainly ultrasound scanning is used to observe the development of fetus during pregnancy. Another applications of ultrasound is in Dental section to clean tooth, cancer treatment, surgery, eye treatment etc.

The working principle of ultrasound scanner : It produces a wave and analyze the echo of that wave, especially how strong the echo was and how long the echo to be received. From these things it produces a digital image as output.

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Monday, March 24, 2008

What is MRI Scan

Magnetic Resonance Imaging (MRI) Scan is the latest system to scan and analyze the functions of human body. Normally MRI scanning is used to find brain diseases. MRI is used to scan all organs in our body very successfully. But MRI scanning is harmful to pregnant ladies. MRI Scanning is more secure than X-rays and CT scan. An electromagnetic radiation is used in MRI scanner. If atoms comes in a high electromagnetic field the nucleus of each atom produces radio signals, these signals are fed to a computer and creates an image of internal body parts. The good cells and weak cells produces different type of radio waves. Working of MRI scanner is depend upon the different types of radio waves from the cells. In 1977 Raeymond V Damadian make a MRI scanner and he named it as Indomitable.

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Sunday, March 23, 2008

What does the future have in store for our planet?

This question has many parts to it. We know, for example, that eventually our star, the Sun, will die and in doing so will destroy the Earth. The very distant future, then means the end of the Earth, but this will not occur for many millions of year and need not concern us here. It has also been suggested that our climate is changing and that we are at the beginning if another Ice Age, but opinion is divided. It is enough to say that large scale changes to the planet as a whole take place so slowly when compared to our short life span that they may go unnoticed, disguised by the much more rapid changes which man is causing to his own life and that of all other living creatures on Earth.

The usual way of attempting to ‘see’ into the future is to look at the way changes have occurred in the past up to the present day and then try to project into the future, but this is not easy because it is not always possible to anticipate the effects of a particulars set of circumstances. Try a simple experime4nt. Draw two lines on a piece of paper at right angles to one another to form the axes of graph. The graph could represent, say, the rate at which a hot water bottle cooled after it was placed in your bed. Suppose one axis represented temperature and the other time. Suppose also that you had measured the temperature on two occasions so that you could plot two points on your graph. These could be joined by a straight line, and if you wanted to know the temperature of the bottle sometime later, you would simply project that straight line to the required point in time. But, if, in the meantime, someone removed the blankets from the bed, the bottle would cool much more quickly and your prediction would be wrong.

The subject of many science fiction stories deals with ideas of what conditions might be like in years to come. Some suggestions seem to be widely far fetched, but a hundred years ago who would have believed in the possibility of supersonic flight or submarines that can stay under the Arctic ice for two years without surfacing, or even in satellites circling Venus? On the other hand in the heyday of the motor car a few years ago, most of us would have laughed at the idea of fuel shortage. How do we know what the world’s population might be in a hundred or even twenty years time? Can we predict whether science and technology will be able to find solutions to the problems of overcrowding, food shortage, and pollution choking our rivers and seas, or the ever-decreasing numbers of wild animals and plants with the accompanying dangers to our own species. Will be able to able to take a rocket to a distant planet as easily as we can now take a bus to the next town, or will we return to more rural living, each community growing its own food and making clothes by hand? Then there are the danger of nuclear war. If man is to survive in peace and plenty, the watchword seems to be to try to foresee the consequence of any action rather than wait and see, by which time it may be too late.

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Saturday, March 22, 2008

Why don’t we see the Moon on some Nights?

There are several reasons why we do not see the Moon on some nights. The moon does not give out its own light but reflects light from the Sun. Therefore, when the Earth comes between the Sun and the Moon. It casts a shadow over the Moon. This is known as an eclipse. When the Moon moves between the Earth and the Sun only its far side is lit by the Sun’s rays. The side facing Earth is in total darkness. We call this a ‘new’ Moon. Finally, on nights when the sky is over cast, the clouds hide the moon from us.

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Friday, March 21, 2008

Where do budgerigars live in the wild?

The parakeets are a widespread group of small old World parrots. Best Known is the Grass Parakeet or Budgerigar which is popular as a cage bird in so many homes. Budgerigars come from Australia. Large, chattering flocks feed among the grasses of the wide, inland plains. They eat the seeds of a variety of grasses, the fresh shoots of plants and any small insects they may discover while foraging. If you keep a budgie, do not be surprised if its snaps at a fly or other insects, for it is merely supplementing its diet like its wild relatives. Wild budgerigars are predominantly grass green in color with yellow head and blue tails. They make a spectacular sight as they flock each morning and evening to drink at a waterhole.

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Which tree’s berries are used to flavor gin and can be used in cookery?

The juniper. This evergreen tree is small and resembles a gorse bush with its spiky needles and fragrant grey bark. Juniper wood is used for small decorative carving and inlay, but it is the berries which make it useful. These are distilled into oil of juniper, which is then used in perfumery and exotic cookery. Another of its uses was in medicine, but nowadays its main function is to flavor gin.

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Sunday, March 16, 2008

Does a comet foretell disaster?

Before we can answer this question, we must look at exactly what a comet is. As you probably know, a comet looks rather like a star with a long, milky ‘tail’ stretching across the sky. In fact these ‘ tails’ are not tails at all because they always point away from the Sun and do not trail behind.

A comet seems to be made up of three main parts. The nucleus in the center of the star-like part is composed mainly of ice and dust particles, surrounded by a coma of much smaller particles and gas. The coma results from the melting of the ice and other substances as the comet approaches the Sun on it’s extremely stretched out elliptical orbit. The Sun’s radiation also tends to force some of these tiny pieces of ice away from the comet and out into space, which explains why the tail is always directed away from the Sun.

A Scientist called Halley, after whom a particularly bright comet is named, discovered how comets moved. He also predicted when some comets which had already been seen would return. For example, Halley’s Comet made its closest approach to Earth for 76 years as predicted in 1986.

Why are comets associated with disaster? It is true that a comet appeared before the Norman conquest of Britain in 1066, and that two more comets were seen before the Great Fire of London in 1666 and the Great Plague in the previous year, but in world terms these cannot be regarded as major events. Perhaps it is the result of people’s belief that what happens in their own country is of world importance that has led to this idea that comets predict disaster. On the other hand, it has been suggested that the Star of Bethlehem that told of the birth of Christ was in fact a comet. It does seem unlikely, however that a body of ice and gas moving around the sky in a quite regular orbit can have anything to do with the events here on Earth. This particularly true of comets because they have such a low density. Although they may have a diameter of as much as 128000 Kilometers they do not have enough gravitational pull to affect the bodies they pass. In fact, their own orbits may be completely changed.

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