Information Technology and General Knowledge

Braille

2008-06-11T21:51:00.003+05:30

Braille

Significant progress in the education of the blind came when in 1826 Louis Braille (1809-1852), blind teacher, organist, and former pupil at the Paris institution, invented the system that now bears his name. Utilizing the "night writing" principle of Charles Barber, a captain in the French cavalry, who used a combination of 12 embossed dots, Braille developed his own system, in which letters of the alphabet were represented by various combinations of embossed dots in cells not more than two dots wide by three dots high. The letters are formed by the use of all possible combinations of six dots.

The Mercury Lamp

2008-06-11T20:18:00.003+05:30

Mercury Lamp Construction and Characteristics.

Mercury lamps typical of those used in industry are constructed with these essential parts: an arc tube made of quartz, containing argon and mercury vapor; activated tungsten electrodes; a glass bulb that encloses the arc tube, to shield the arc from drafts, prevent oxidation, and provide a surface for a phosphor coating; and a base which serves as an electrical connecting and holding device. These parts vary in size and shape for such different uses as general-lighting lamps (clear mercury, fluorescent mercury, tinted mercury, reflector and semi reflector), black light (ultraviolet) lamps, sunlamps, and photochemical lamps. The average rated life of the general-lighting lamps varies from 6,000 to 12,000 hours.

In operating a mercury lamp, once the arc is established in the arc tube the current through the mercury vapor tends to increase without control. A device, therefore, must be used with the lamp to control and limit the current through the lamp; this device is known as a ballast.

Advantages and Disadvantages.

Mercury lamps have a high luminous efficacy (2 to 3 times that of general-service incandescent lamps), have a long life, and are a compact size source for good light control. These obvious advantages may or may not be outweighed by such disadvantages as high lamp and equipment cost, bluish-green color of light, and slow restarting. Although the color of mercury light is bluish-green and lacking in red energy, this deficiency can be partially compensated for by using conjunction with the clear Lamps.

A Rainy day Evening

2008-06-11T14:57:00.001+05:30

A Rainy day Evening

The Sunset

2008-06-11T14:51:00.001+05:30

The New Baby's Sleep

2008-06-11T11:19:00.004+05:30

Babies know how much sleep and rest they need and will get it if give them the chance. If their meals are satisfying and they are generally comfortable, they will usually take care of their own sleep needs. A reasonably quiet place for crib or bassinet and some fresh air during the day will help them sleep longer. They can also sleep in the carriage out of doors during the day. Many a bay who goes marketing with his mother sleeps peacefully through it all. In general, however, it is best to avoid taking a baby of any age into crowded places or public conveyances unless its is really necessary.

The young baby needs no pillow. The covers should be lightweight and no warmer than the season requires, and they should be tucked in.

There is a question about whether a baby should be put into the bassinet or crib on the back or the stomach. A baby put down on the back not long after being fed burped may still have some air in the stomach. This can cause the baby to burp and bring up some milk, which can cause gagging and possibly choking. The won't happen if the baby lies on the stomach.

Make your baby's bed with a waterproof sheet over the mattress, a crib pad during feeding, be sure to burp him before putting him down. Many young babies have a bowel movement either during or immediately after a feeding, so you will probably have to change the baby before the nap.

Measuring Earth

2008-06-11T10:59:00.003+05:30

Measuring Earth

So the ancient Greeks believed that Earth was a ball. But just how large was Earth's ball - and how were planets?

In about 240 BC, a Greek astronomer in Egypt, Eratosthenes, made am exciting discovery. He found that when the Sun was directly overhead in one city, it cast a shadow in another city, 500 miles (800 km) to the north.

Eratosthenes figured that this meant Earth's surface curved. He also figured out that Earth was a ball about 25,000 mile (40,000 km) around. Today, we know he was right.

Hipparchus later studied Earth's shadow when it eclipsed the Moon. From the size of the Moon, he decided it must be about 240,000 miles (384,000 km) from Earth. He was right about that, too!

Binesh Das

Neurosis

2008-06-11T09:00:00.001+05:30

Neurosis

A neurosis (or psychoneurosis) is characterized primarily by emotional rather than physical symptoms although physical symptoms may be present. The neuroses are usually categorized according to the type of reaction that the patient exhibits in his attempt to resolve the underlying emotional conflict. All of them involve anxiety as a prominent symptom.

Anxiety Reaction
The anxiety reaction is probably the most widespread of all the neurotic response patterns. Although, as noted above, all the neuroses share anxiety as a symptom, the most common and outstanding characteristic of the anxiety reaction is a feeling of dread or apprehension that is not related to any apparent cause. The anxiety is caused by conflicts of which the patient himself is unaware but which may be stimulated by thoughts or events in his present life. For example, the junior executive who is constantly apprehensive that his employer will ridicule his work and dismiss his ideas may be expressing an anxiety reaction to a childhood fear that equated ridicule with abandonment or mutilation. While anxiety reaction symptoms are primarily mental or emotional, the patient feels inadequate or ineffectual, or behaves irrationally, anxiety is always accompanied by physiological changes such as sweating and heart palpitations. Fatigue and feelings of panic are also common symptoms.
Conversion Reaction
The conversion reaction (or conversion hysteria) describes a type of neurotic behavior in which the patient, instead of coming to grips with his underlying psychic conflict, manages to convert it into physical symptoms involving functions over which he ordinarily exerts complete control. Sometimes the physical symptoms are unimportant, but often they are markedly dramatic. For example, the soldier who becomes deaf to the sound of explosions even though there is no organic defect that would account for a loss of hearing has effectively obliterated a sensations too painful to acknowledge.

Obsessive-Compulsive Reaction
A person beset by persistent, unwanted ideas or feelings (obsessions), who is impelled to carry out certain acts (compulsions) ritualistically, no matter how irrational they are, is reacting to a psychic conflict in an obsessive-Compulsive manner. The obsession may involve a feeing of violence or sexuality directed toward a member of his own family. Usually the feelings will never lead to any overt action of the type imagined, but the idea is nevertheless persistent and painful. Obsessive-compulsive patients are typically exceptionally meticulous and conscientious, often intelligent and gifted in their work. But they expend and enormous amount of energy and time in observing compulsive acts. For example, they may take a dozen or more showers every day because they are dirty or carrying a contagious disease. By performing an apparently harmless compulsive act, the patient is temporarily relieved of the obsession.

Depressive Reaction
Most people have blue moods from time to time in their lives. Indeed, when faced with a personal tragedy like the death of a loved one, a normal healthy individual may well undergo a period of depression. A person suffering from the depressive reaction, however, has persistent feelings of worthlessness and pessimism unrelated to events that might depress a normal person. An inability to cope with problem situations is gradually magnified into an inability to cope with anything at all. Attempts to mask the crisis by putting on a "front" feigning cheerfulness and optimism give way to episodes of total hopelessness. Suicide is often considered and sometimes attempted. Threats of suicide from a depressed person should always be regarded seriously.
Common physical symptoms accompanying depression are fatigue, loss of appetite, and insomnia.

Phobic Reaction
A phobic reaction is the result of an individual's attempt to deal with an anxiety-producing conflict, not by facing up to the actual source of that conflict but by avoiding something else. The substitute whether it be an animal, closed places, or whatever is responded to with the intense anxiety that is really felt for the true source of anxiety. This process is known as displacement, and the irrational fears or dreads are known as phobias.
Thus, a person who had been regularly punished as a child by having been forcibly confined in a closet might be unable to deal with the anxiety of the experience consciously. The anxiety might be displaced and emerge later in life in the form of terror of crowded or confined places- claustrophobia.
Phobias can involve almost anything one encounters in life-including things that go on in one's body and one's mind. Some of the most common phobias have to do with disease- bacteriophobia, for example, the fear of germs.
Scores of phobias exist, ranging alphabetically from acrophobia, the fear of heights, to xenophobia, the fear of strangers. Other well-known examples are ailurophobia, the fear of cats; cynophobia, the fear of dogs; algophobia, the fear of pain; agoraphobia, the fear of open spaces; erythophobia, the fear of blushing; mysophobia, the fear of dirt and contamination; nyctophobia, the fear of the dark; and lyssophobia, the fear of rabies.

Dissociative Reaction
The dissociative reaction involves a basic disruption of the patient's personality. The dissociative reaction permits a person to escape from a part of his personality associated with intolerable anxiety. The escape is made in various ways: by forgetfulness or absent-mindedness, dream states (including sleepwalking), amnesia, and most seriously the adoption of multiple personalities, in which the patient behaves like one person at certain times and like an altogether different person at other times.

Binesh Das