... (1991); and Rolls (1991). The behaviourist theories proposed that a reward or aversive object/event will motivate a rat to move towards or away from the location along a reward gradient, and this has been shown to be the case with rats in a maze situation (O'Keefe, 1983). Indeed, this situation does not require the rat to have a concept of absolute space; it may depend on associations between cues and responses which are provided by the maze structure itself. However, O'Keefe & Nadel (1978) identified spatial behaviours which they argued would require the existence of an allocentric map: detection of changes within the environment; navigation to the goal from ...
... he received a doctorate in canon law from the University of Ferrara. Copernicus lived with his uncle in his bishopric palace. While he stayed there he published his first book which was a translation of letters written by the 7th century writer, Theophylactus of Simocatta. After that he wrote an astronomical discourse that laid the foundation of his heliocentric theory; the theory that the sun is the center of our solar system. However, it was 400 years before it was published. After leaving his uncle, he wrote a treatise on money, and began the work for which he is most famous, On the Revolution of the Celestial Spheres, which took him almost 15 years to writ ...
... First of all, and most importantly, automobiles are harmful to our environment. Automobiles run on gasoline, which is a mixture derived from petroleum. Gasoline contains hundreds of different hydrocarbons, or compounds containing the chemical elements carbon and hydrogen(Gasoline). When the gas is burned in the engine of the car, several byproducts result. These exhausts include hydrocarbons and oxides of three elements: Carbon, nitrogen, and sulfur(Emissions). Tiny amounts of poisonous trace elements such as lead, cadmium, and nickel also are present. Everything contained in the exhaust affects the environment intensely. Auto engine exhaust contributes ab ...
... aspiration, guided by ultrasound. At the same time, semen samples from the husband (or donor) are obtained. The most active and healthy sperm are selected by forcing them to swim through a culture medium. - The egg and sperm are placed together in a suitable medium for fertilisation to occur in a culture dish. If fertilisation does not occur after 72 hours, the oocytes (incompletely developed eggs) and sperm are disposed of. The resulting embryos are observed for the next few days. - A small plastic tube is inserted through cervix to place embryos into the uterus. The patient is able to go home a few hours later with minimal discomfort. During the firs ...
... such pollutants as nitric acid and sulfuric acid, both dissolving easily in water. This results in acidic water droplets that can be carried by prevailing winds, returning to Earth as acid rain, snow, or fog. This effects the lakes by changing the pH balance. As the water pH approaches 6, crustaceans, insects, and plankton begin to disappear. When the pH is slightly above 5, major changes start to happen, less desirable species of mosses and plankton may begin to flourish, whereas others will lessen in numbers and die off. Below pH of 5, the water is to acidic for many fish, the bottom is covered with undecayed material, and the shores may be dominated by mosse ...
... remaining in use. This is because it provided an obvious way of keeping the constant connection necessary for voice traffic. The invention of the transistor and the concept of pulse code modulation (PCM) allowed digital communications to be developed in the late 1960's. The interconnection of computer systems over telecommunication networks soon became a requirement. Modems were used at first to generate analogue signals compatible with the PSTNs from the digital computer data to allow such interconnections. The already wide spread use of the PSTNs was an advantage of this scheme, however it was soon recognized as not being an optimum solution for data transfer. ...
... Neurotransmitters transmit messages from one neuron to another. Two of these neurotransmitters are not produced in sufficient quantities in a depressed person’s brain. Because of this lack, too few messages get transmitted between neurons and the symptoms of depression occur. In Clinical depression the chemicals in the brain are out-of-balance. New technology allows researchers to take pictures of the brain that show activity levels in the brain. These imaging techniques such as f-MRI and PET scan actually create images of how active different parts of the brain are. Some studies with these kinds of techniques have suggested that the patterns of activ ...
... probably find plant structure interesting. If microscopic organisms appeal to you, you should look into microbiology, phycology, or mycology. If you are artistic, ornamental horticulture and landscape design might be right up your alley. If you worry about feeding the hungry, you should study plant pathology or plant breeding. At some larger universities, you can even study specific types of , each with its own department. These departments include argonomy (field crops), microbiology (microbes like bacteria and fungi), horticulture (fruits, ornamentals, and veggies), and plant pathology (diseases pertaining to plants). If you are a people person, you mig ...
... species would start to increase. 3. It is seldom possible to count all the individuals in a given space. Explain one method by which biologists can study population densities without obtaining such data. Scientist barely ever count the amount of individuals in a certain area because it would take too much time. Instead of actually counting the number of individuals in an area they would compare it with other areas where they know the population of individuals. In this way they can roughly estimate the number of individuals in a certain area. 4. What might happen to a rabbit population in an area where there are no predators? If there were a few rabbits in an ar ...
... triclinic and hexagonal system. Crystals may form when a solution of a substance evaporates. Crystals may also form when a vapor or molten substance solidifies. Allotropes are different forms of the same element. For Example, oxygen has two allotropes, normal oxygen and ozone. Pure carbon also has two allotropes, diamond and graphite. A crystal of diamond is in fact a single giant molecule in which every carbon atom is linked to four other, by four equal, strong bonds. These bonds are arranged tetrahedrally round each atom and there are no planes along which the giant molecule can easily be split. This quality is what gives diamond its tremendous hardness. ...
