Reinforcing Processes

Dependence is a somatic state which develops after chronic administration of certain dtugs. This condition is characterized by the necessity to continue administration of the drug to avoid the appearance of withdrawal symptoms. Withdrawal symptoms are relieved by the administration of the drug upon which the body was dependent . Psychological dependence is due to (e.g., social) reinforcement processes in the maintenance of drug-seeking behavior. 

Both amphetamine and cocaine have also been reported to support intracranial self-administration in the mesolimbic/mesocortical dopaminergic system. Rats will self-administer cocaine into the medial prefrontal cortex (Goeders and Smith 1983). while amphetamine is self-administered into the orbitofrontal cortex of rhesus monkeys (Phillips and Rolls 1981) and the nucleus accumbens of rats (Hoebel et al. 1983 Monaco et al. 1981). These data indicate that the mesolimbic/mesocortical dopaminergic system is involved in the initiation of stimulant reinforcement processes, and this work suggests that the region of the nucleus accumbens, more specifically the mesolimbic dopamine system, may be an important substrate for reinforcing properties of several psychomotor stimulant drugs. 

Huston, J. P., Wagner, U. and Hasenohrl, R. U. The tuber-omammillary nucleus projections in the control of learning, memory and reinforcement processes evidence for an inhibitory role. Behav. Brain Res. 83 97-105,1997. 

In the last part of the paper, filler-elastomer chemical interactions which are able to take place through surface functional groups or surface reactive hydrogens are studied. The effect exerted by the created filler-elastomer bonds in the reinforcement process is then discussed. 

It was shown, on the one hand, that gum-filler interactions are associated with the immobilization of a certain amount of rubber on the surface or inside the carbon black aggregates, and, on the other hand, that the corresponding bound or occluded rubbers play important roles in the reinforcement process due either to a restriction of elastomer chain mobility in the vicinity of the filler or to an increase of the effective volume of the latter. What are now the effects exerted by a filler on the stress-strain behavior and the modulus of cured rubbers ... 

The filler-elastomer chemical interactions take place through its surface functional groups and hydrogen atoms. Coupling agents improve polymer-filler adhesion. From the point of view of dynamic-mechanical properties for low strains, the filler-elastomer bonds have a positive effect in the reinforcement process. 

Role of the Orbitofrontal Cortex in Reinforcement Processing and Inhibitory Control Evidence from Functional Magnetic Resonance Imaging Studies in Healthy Human Subjects Rebecca Elliott and Bill Deakin... 

Shippenberg TS, Bals-Kubik R, Herz A (1987) Motivational properties of opioids evidence that an activation of 8-receptors mediate reinforcement processes. Brain Res 436 234-239... 

Schipanski A (2007) Reinforcement processing in larval Drosophila melanogaster. Diploma Thesis, University of Wurzburg... 

There are certain facts which should not be overlooked in any discussion of filled elastomers, consideration of which eliminates much unnecessary conjecture about the nature of the reinforcement process. These may be summarized as follows ... 

Recycling of Polypropylene. At its Knapsack site, Hoechst has erected a recycling plant for polypropylene with a capacity of 5 000 t/a of PP recyclate (Fig. 120). Recycling makes it possible to start with pure PP fractions from used parts (such as those from automobiles) and modify them into typeware. The material must be collected, ground, and sorted on a decentralized basis. The ground recycled parts are mixed with virgin PP powder, additives, and reinforcements, processed in an extruder, and thus converted to products that meet the required specifications [253]. 

Reinforcement Processing Fiber Tensile Young s Flexural Impact content strength modulus strength strength (%) (MPa) (GPa) (MPa) (KJ/m ) ... 

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