... can produce the hormone insulin, which is used to treat diabetes. Such uses of transgenic organisms are widely referred to as genetic engineering. Transgenic organisms have proved very useful in analyzing the function of gene products because a specific gene can be expressed in all the cells of a transgenic organism and the effect on the organism's development and function can then be monitored. It is also possible to use transgenic procedures to produce animals in which a specific gene has been deactivated in all its body cells. Certain genetic disorders of humans can be studied with this technique in laboratory animals if the disease-associated gene occurs na ...
... to Lord Shelburne at the time of his most significant experimental work, and Carl Wilhelm SCHEELE (1742-86), a Swedish pharmacist and chemist. It is generally believed that Scheele was the first to isolate oxygen, but that Priestley, who independently achieved the isolation of oxygen somewhat later, was the first to publicly announce his findings. The interpretation of the findings of Priestley and the resultant clarification of the nature of oxygen as an element was accomplished by the French scientist Antoine-Laurent LAVOISIER (1743-94). Lavoisier's experimental work, which extended and improved upon Priestley's experiments, was principally responsible for the u ...
... The speed with which you need to throw the rock in order that it just barely escapes the planet's gravity is called the "escape velocity." As you would expect, the escape velocity depends on the mass of the planet: if the planet is extremely massive, then its gravity is very strong, and the escape velocity is high. A lighter planet would have a smaller escape velocity. The escape velocity also depends on how far you are from the planet's center: the closer you are, the higher the escape velocity . The Earth's escape velocity is 11.2 kilometers per second (about 25,000 M.P.H.), while the Moon's is only 2.4 kilometers per second (about 5300 M.P.H.).We cannot see i ...
... the balance of charge on objects is disturbed. An on an object that causes the object to attract or repel other objects is called static electricity. The adjective static describes something that does not move. Charges on an object are called static electricity to contrast then with the moving charges in an electric current. How can you disturb the balance of charge on objects so they exert electric force? The easiest way is the same way the ancient Greeks did it – by rubbing the 2 objects together. Rubbing neutral objects together allows charged pieces of matter to move from one object to another. The invisible bits of negatively charged matter that move b ...
... at Clemson University of 1997 in order to develop a sports prosthesis that would stand up to every day flexing of the knee for performance in sports. In order to develop this prosthesis they had to go through two main phases, the analysis of a jogger wearing a standard walking prosthesis and computer simulation of the flexing of the knee on this walking prosthesis. They had to measure rotation, weight bearing, moments, and the stress of the joints acting on this limb. After the mechanical actions were mapped out they had to use many mathematical equations to spring force and spring stiffness. All of this was accomplished and the conclusion was that by varying ...
... of a substance. This brings into play the processes of diffusion, osmosis, and active transport, all of which involve only small simple molecules. Diffusion is the movement of a substance from a region of high concentration, to a region of low concentration of that substance. In other words, a movement down the concentration gradient. Osmosis is very similar to diffusion, however it involves the concentration of water. Osmosis, like diffusion, is a passive process, and does not require energy to occur. Active transport does require energy though, as it involves movement up the concentration gradient. This involves protein carrier molecules binding to the s ...
... and chemical compounds, and ease of recycling. Its versatility, as well as its physical and chemical properties, accounted for its extensive use. Lead can be rolled into sheets which can be made into rods and pipes. It can also be molded into containers and mixed with other metallic elements. Lead was used in ancient times for making coinage, art objects and water pipes. One of the first known toxic substances, lead was used by the Romans for lining aqueducts and in glazes on containers used for food and wine storage; and it is suspected to have resulted in widespread lead poisoning. Members of the famous Franklin Expedition to the Northwest Passage in the mid-18 ...
... consumption surpasses two drinks a day, risks increase for some kinds of cancer. Doctors at UT Southwestern Medical Center at Dallas say before you start drinking for your health, talk to your doctor. For some people, the risks of alcohol outweigh the benefits. And remember that while one drink a day can be helpful, more can be harmful. Could a drink a day keep the doctor away? One study says alcohol can have beneficial effects. Doctors recently determined that people who drank moderately, about one or two drinks per day, had a lower chance of developing blocked arteries in their legs. This condition results when the arteries in the legs become hardened. Resea ...
... periodic table. Though widely distributed at the Earth's surface, gallium does not occor free or concentrated in independant minerals, except for gallite. It is extracted as a by-product from zinc blende, iron pyrites, bauxite, and germanite. Silvery white and soft enough to be cut with a knife, gallium takes on a bluish tinge because of superficial oxidation. Unusual for its low melting point ( about 30 degrees C, 86 degrees F ), gallium also expands upon solidification and supercools readily, remaining a liquid at temperatures as low as 0 degrees C ( 32 degrees F ). Gallium has the longest usefull liquid range of any element. The liquid metal clings to ...
... and motor functions. In sensory functions, your body’s sensory receptors detect many different stimuli in and outside of your body. For example, your sensory receptors may detect a change in your blood temperature, or a change outside of your body such as a touch on the arm. Your body then goes through a process know as its integrative function. This is when your nervous system processes information sent via your sensory neurons and in a way “makes decisions” regarding appropriate responses. When all is said and done during this process a decision is made and sent through interneurons that act as a postman and deliver the decision to the motor functio ...
