Lasers
.... later in 1960. Three separate teams of American scientists operated the first semiconductor laser in 1962. Then in 1966, the American physicist Peter Sorokin built the first dye laser.
To begin with, I will explain the definition of a laser: It is a device that produces a very narrow powerful beam of light. A laser light is a narrow beam of light, in which all the waves are traveling exactly at the same length and moving together as one. A laser light is made up of only one wavelength and it is a si .....
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Lasers -
.... the threat of lightning causes many work stoppages and lost production increasing the time and cost required to
prepare NASA spacecraft for flight.
Benjamin Franklin performed the first systematic, scientific study of lightning during the second half of the 18th century. Prior to that time, electrical science had developed to the point where positive and negative charges could be separated. Electrical machines could, by rubbing together two different materials, store the charges in primitiv .....
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Lasers 2
.... Maiman observed the first laser action in solid ruby.
HOW A LASER WORKS
A laser is made up of several basic components. One is called active medium, which consists of atoms of a gas, molecules in a liquid, ions in a crystal, or any of several other possibilities. Another component consists of some method of introducing energy into the active medium, such as a flash lamp. The third basic component is a pair of mirrors placed on either
side of the active meduim, one of which transmits part of the .....
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Lasers 3
.... on the sides of the florescent material, and external energy source.
Theodore Maiman was the first to successfully assemble an optical laser. In 1960 Maiman produced the ruby laser. In it a strobe lamp is coiled around the core, a rod of ruby that has mirrors at its ends, one of which is only partially solid. As the strobe light flashes it excites the ruby atoms that in turn emit photons. The photons are reflected back and forth by the mirrors until they pass through the partially solid mirror. This .....
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Lasers 4
.... of some method of introducing energy into the active medium, such as a flash lamp for example. Another component is the pair of mirrors on either side of the active medium which consists of one that transmits some of the radiation that hits it. If the active component in the laser is a gas laser than each atom is characterized by a set of energy states, or energy levels, of which it may consist. An example of the energy states could be pictured as a unevenly spaced ladder which the higher rungs mean higher .....
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Lasers And Their Applications
.... Laser light is coherent because the atoms are stimulated to emit waves of light that are in phase creating constructive interference producing a powerful and intense laser light. The emitted light is monochromatic, meaning only one wavelength, and one directional. For a laser to work three components are needed. First a gain medium that can amplify light through it. Second an energy pump source to create a population inversion, (this is a condition when electrons in high energy levels are more nume .....
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Laziness
.... There are several immunological abnormalities associated with
psoriasis. Early psoriatic changes occur in advancing lesions before the
accumulation of inflammatory cells. These changes are mediated by
activated CD4+ T lymphocytes and can be detected before visible pathology
to the skin occurs. Activated T lymphocytes exhibiting an increase in
HLA-DR and IL-2R can be seen in close proximity to Langerhans cells in the
dermis before lesion formation. Since Langerhans cells are antigen
pres .....
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Le Virus Ebola (spanish Essay)
.... primats non humains, mais pas chex l'homme.
Il y a aussi le question, ou le virus d'Ebole se trouve? Les scientists, est medcins, ne savons pas. Il croien que le virus est devenu d'une centre serveru animal, comme un chauff souris, un souris est probablement un singe. L'origine exacte, les emplacements et l'habitat normal du virus d'Ebole rest inconnus.
Comment Est ce-que le virus nous tuer?
Cette question est la plus populair est aussi le plus interesant. Tous les victims d'Ebola, mort a .....
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Leprechaunism
.... relationship means that the parents are genetically related (e.g. first cousins).
Clinical traits are as follows:
Hyperpigmented skin or as otherwise known, Acanthosis nigricans. This symptom is not exclusive to Leprechaunism, as it is caused by high insulin levels. This pigmentation normally occurs in areas of the body where flexing and bending occurs, such as the back of the neck.
Reddening of the skin or erythema. This is caused by localized irritation. Most often .....
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Leprosy
.... to eat away at thebones causing people to loose parts of their body. All of these signs can be prevented with early detection.In the past chaulmoogra oil was used, thinking that it would make a good
treatment for leprosy. In today's world there are many drugs that are used to prevent it.The drugs are the best way to stop it from spreading. Another way is to watch that youget good nutrition.Doctors have made many great advancements in the fight against leprosy. In today's world if caught early it can b .....
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Leprosy 2
.... as having paucibacillary leprosy possess five or fewer skin lesions and those diagnosed with multibacillary leprosy have six or more skin lesions. The disease can be further classified on the basis of skin findings, motor and sensory changes, and biopsy findings as indeterminate (I), tuberculoid (T), borderline tuberculoid (BT), borderline (BB), borderline lepromatous (BL), and lepramtous (LL). Under the WHO classification, I, TT, and BT diseases are generally equivalent to paucibacillary leprosy while .....
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Lepus Americanus
.... critical winters of 1981-1982 the experimental grid area lost 77% of its population as compared to 79% and 96% loss for the control grids. Determining the survival rates, the authors used mark-recapture techniques, it was found that probabilities for survivorship in experimental grid (0.79+0.10) were similar to that of control grids (0.71+0.07; 0.56+0.07). Results yielded that extra food intake and cover provided from branches may have not been helpful in increasing survivorship. No differences were me .....
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Leukemia
.... are made in the Lymph glands
and bone marrow are abnormal or immature. In Granulocytic
Leukemia this causes an increase in white blood cells known
as granulocytes. Granulocytes are made in the bone marrow,
and other tissue. Granulocytes that are affected by
leukemia cannot fight of infections.
There are two ways in which leukemia can occur. One is
acute, and the other is chronic. Acute leukemia is found
most in children. It progresses rapidly. Acute leukemia
causes red blood ce .....
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Lichens
.... Such a relationship is called mutualism. The claim is that the fungus, which is unable to make food for itself, uses food made by the alga, while on the other hand the alga is protected from drying out by living on the spongelike network of the fungous threads. Other scientists believe that the alga is not benefited by the presence of the fungus, but is held in slavery by it. Such a relationship is called helotism.
In any event the combination produces a structure that is able to exist wher .....
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Lift, Weight, Thrust And Drag
.... the wing, is the primary source of lift.
The weight of the airplane is not a constant. It varies with the equipment installed, passengers, cargo, and fuel load. During the course of a flight, the total weight of the airplane decreases as fuel is consumed. Additional weight reduction may also occur during some specialized flight activities, such as crop dusting, fire fighting, or sky diving flights.
The direction in which the force of weight acts is constant. It always acts straight down toward t .....
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