... hemisphere to within a fraction of a degree, going back to AD 1400. The study places in a new context long-standing controversy over the relative roles of human and natural changes in the climate of past centuries, according to Mann. Scientists were particularly interested in natural "forcings" -- factors that can affect the climate significantly but which are not part of the climate system itself. Based on statistical comparisons of reconstructed northern hemisphere temperatures, the best estimates indicate that natural changes in the brightness of the sun and volcanic emissions both played an important role i ...

... formation of identical twins, triplets, and so on. Identical siblings constitute a clone. The growth of a tumor in the body of an individual is, in effect, the formation of a clone of malignant cells. Humans have learned from nature and started their cloning saga also. In one method of artificial cloning used in plant breeding, cells are cut from a plant and placed in a flask with a nutrient medium. The cells grow and divide, forming embryonic tissues that are transferred to soil, where they produce complete plants. Grafting is another method of cloning used in Horticulture. Matching cuts are made in the stems of ...

... the normal brain to the Alzheimer's brain. There was a loss of nerve cells from the Cerebral Cortex in the Alzheimer's victim. Approximately ten percent of the neurons in this region were lost. But a ten percent loss is relatively minor, and cannot account for the severe impairment suffered by Alzheimer's victims. Neurofibrillary Tangles are also found in the brains of Alzheimer's victims. They are found within the cell bodies of nerve cells in the cerebral cortex, and take on the structure of a paired helix. Other diseases that have "paired helixes" include Parkinson's disease, Down's syndrome, and Dementia Pugilis ...

... at the equator because of the inter tropical convergence zone and rises to the poles. There the air is cooled and it floats back down to the equator where the process is repeated. Another major contributing factor to the circulation of the air is due to the subtropical highs. These highs like the ITCZ migrate during the different seasons. The idealized belt model is a great representation of the general circulation of the atmosphere. The equatorial belt of variable winds and calms ranges from 5 degrees north to 5 degrees south. This wind belt is characterized by weak winds and lo ...

... on the market. Terrorist, organized crime and countries with nuclear ambition, are high bid contenders for the material. The United States is also becoming involved for the safety of preventing a nuclear disaster. The U.S. has just begun their large task and with Russia's worsening economy, smuggling of nuclear material will continue. During the Cold War the security of Soviet nuclear weapons and missile materials was based on a highly centralized military system and operating within a strong political authority. The workers back then where well disciplined and each individual new his/her role. The worke ...

... of dogs, cats, apes, monkeys, horses, ponies, calves, sheep, goats, pigs, and a couple million rabbits, hamsters, guinea pigs, birds, rats and mice (Curtis 658). These animals are subjected to experiments that often cause pain and even death. According to Cutis, about 25 cosmetic companies including Avon and Revlon, have cooperated in conducting animal tests to see if there product are irritating (664). These experiments were tested on rabbits only because they have no tear glands to wipe away any foreign objects on the eye. The animal would be strapped down and the "product" would be dropped into the ey ...

... use it to make food. This is called photosynthesis. During this process oxygen is released which is then breathed in by humans and animals. This procedure is repeated over and over and a natural balance is obtained. However this natural balance is disrupted by human activity. People of the world are putting more than 5.5 billion tons of CO2 into the atmosphere every year. 75% of this is caused from the burning of fossil fuels. These fuels are burnt all the time to run factories, power plants and vehicles. The main sources of CO2 emissions are electric utilities, residential buildings, industry and transport ...

... However, fossil fuels such as coal, require greater quantities to produce the equivalent amount of electricity produced from Uranium. The use of nuclear power opposed to burning fossil fuels has reduced carbon dioxide emissions by 2 billion tonnes per year, minimising the global warming effect on the atmosphere. Carbon dioxide is responsible for half of man made gases contributing to the Greenhouse Effect, and has sparked action from the UN Intergovernment Panel on Climate Change. Their consensus is a concern for the environment in the next century if fossil fuels continue to be used, even at present global lev ...

... considered as a definite possibility for an alternative power source for space program, but the cost and size of the stacks were tremendous. By 1983, Geoff Ballard and a small team of physicists were able to develop the Proton Exchange Membrane (PEM) to produce nearly ten times as much energy, while being only a fraction of the size. How the PEM Works: A is an electrochemical device that produces electricity silently, without combustion. Hydrogen fuel, which is one of the most abundant chemicals in the universe, and oxygen from the air are electrochemically combined in the to produce electricity. Heat and pure ...

... but do you realize what an important role these beetles play all around the world. I remember several days when I was young that I would just go for a walk in my grandfather's pasture. I would enjoy the quiet walks, and sometimes try to scare the cows, but more often than not, I would end up stopping to watch dung beetles frantically work on a big cow pat. I remember how disgusting it appeared, but I was just fascinated at the concept of cow poop being rolled into balls and taken away by bugs. To realize why dung beetles are so important, you must first know a few facts about them. Dung beetles are named after ...