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Science and Nature Term Papers and Reports |
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History Of Cell Membrane
414 Words - 2 Pages.... cells are separated from their environment by a membrane possessing special characteristics, and in 1900 Overton performed some simple but classical experiments which proposed that cell membranes were composed of lipids (1). By measuring the permeability of various compounds across the membrane of a frog muscle, Overton found some interesting results. He observed that lipophilic molecules (molecules attracted to fat solvents) could easily cross this cell membrane, however larger lipid insoluble molecules could not. He also observed that small polar molecules could slowly cross the membrane. Other experiments with the likes of hen eggs suggested the presence of a lipid ....
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Autism 3
1709 Words - 7 Pages.... a lack of social relationship, a lack of communication abilities, persistent compulsive, rituals, and resistance to change” (Paluszny 1). For centuries, medical professionals have tried to understand autism and its origin. The above example shows only a few examples of autistic behavior.
The history of autism extends, as far back as the late sixteenth century; however, during that time it was not identified as this illness. Here is a statement from before the discovery of the illness:
In 1799, a boy about eleven years of age was found naked in the woods of
Averyron, France. He was dirty, covered with sores, mute, and behaved like
A wild animal. Jean Itard, the physici ....
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Copper And Molybdenum Deposits In The United States
2613 Words - 10 Pages.... and later became an important additive in
harder, more useful metals such as bronze (copper+tin; 2500 B.C.) and brass
(copper+zinc; 0 A.D.). The growth of copper production in the United States has
been a relatively recent occurrence. North American French explorers knew of
sources of native copper in the region of Lake Superior and the area natives had
copper jewelry and ornamentation. Earnest copper mining began in Simsbury,
Connecticut about 1709 and copper was actually exported to England after a
source was discovered in New Jersey around 1719. In later times domestic copper
resources did not satisfy national needs until the discovery of gold in
California shifted t ....
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Value Of Environmental Agencies
990 Words - 4 Pages.... agencies' must be valued.
By destroying the forest, we are creating an open-door policy for
disease. For example, the S.Amerindians have long adopted to endemic disease
and have prevented them, in large part, by their adaptation to conditions of
life over the 20,000 years they have inhabited the tropical forest. With the
lumber companies invading these towns and villages, their western germs are
exposing isolated, once-contained people. Kathlyn Gay, author of Rainforests of
the World, mentions, “Indigenous people in many countries have died because of
contact with outsiders-usually whites of northern European extraction-who have
brought contagious diseases, ran ....
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Australopithecus
306 Words - 2 Pages.... Ausralopithecus boisei roamed the earth
as early as 1.1 million years ago and was on earth at the sametime as homo
habilis and homo erectus. Most of the australopithecus fossils that have been
discovered have been found in eastern africa and have been dated between 4.5
million and 1.1 million years old. There has also been evidence that the
australopithecus "man" lived in australia where fossils have also been found.
The first discovery of an australopithecus fossil was made in 1924. The body of
the australopithecus is smaller than humans, but biffer than chimpanzees. Also,
The brain size of australopithecus is bigger than humans at about 475 cubic
centimeters. This is ....
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Environmental Crisis
1524 Words - 6 Pages.... problems have largely resulted from
population growth, which has lead to apathy and inaction with regard to the
wasteful consumption of resources. Examples are the desertification of the Sahel
in Africa, the one child policy in China and the mis-management of our oceans.
The Sahel is a strip of land that extends for more than 6000 kilometres across
the southern edge of the Sahara desert. It stretches from Senegal and
Mauritania in the west to Ethiopia and Somalia in the east. These nations are
among the world's poorest.
The area is one of social and biophysical crisis because of the way the
population are forced to live; they are destroying the productivity of ....
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How Toxic Waste Affects Canada’s Natural Environment
732 Words - 3 Pages.... that we produce every year, that 15% is enormous. The Environmental Protection Agency (EPA) estimates that we produce one ton of toxic wastes for every single person living in Canada every year. That means that the 15% represents about 4.2 million tons of toxic waste.
Toxic wastes, which are dumped in improper sites, can seep into underground water supplies and contaminate huge areas. If the land that is intoxicated supports plant life, most of the plants and trees will die off. If humans occupy the area, it could cause serious illness or death. For example, an area by Niagara Falls (US side) was used during the 1930s by a chemical company to dump its waste. Most of them ....
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Memory
1045 Words - 4 Pages.... called the
hippocampus (Loftus p. 392). Memory is acquired by a series of solidifying
events , but more research is still needed to discover and fully understand
(Loftus p. 392).
Memory is broken down into three systems or categories . These different
systems are sensory memory , short-term , and long-term memory. Sensory memory
is the shortest and less extensive of the others. It can hold memory for only an
instance (Memory p. 32). Suppose you see a tree , the image of the tree is
briefly held by the sensory memory and quickly disappears unless you transfer it
to your short-term memory (Rhodes p. 130). The next level is called short-term
memory. The image or fact can be h ....
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