Dependence mechanism

The radiation and temperature dependent mechanical properties of viscoelastic materials (modulus and loss) are of great interest throughout the plastics, polymer, and rubber from initial design to routine production. There are a number of laboratory research instruments are available to determine these properties. All these hardness tests conducted on polymeric materials involve the penetration of the sample under consideration by loaded spheres or other geometric shapes [1]. Most of these tests are to some extent arbitrary because the penetration of an indenter into viscoelastic material increases with time. For example, standard durometer test (the "Shore A") is widely used to measure the static "hardness" or resistance to indentation. However, it does not measure basic material properties, and its results depend on the specimen geometry (it is difficult to make available the identity of the initial position of the devices on cylinder or spherical surfaces while measuring) and test conditions, and some arbitrary time must be selected to compare different materials. 

The development of devices that provide a direct measure of stress or particle velocity led to observations of new rate-dependent mechanical responses and showed the power of such time-resolved measurements. The quartz gauge was the first of these devices with nanosecond time resolution, but its upper operating limit of 4 GPa limited its application. The development of the VISAR has had the most substantial impact on capabilities. VISAR systems, with time-resolution approaching 1 ns and the ability to work to pressures of 100 GPa, provide capabilities that have substantially altered the scientific descriptions of shock-compressed matter. 

Studies of the electrical and mechanical responses of ferroelectric solids under shock compression show this technical problem to be the most complex of any investigated. The combination of rate-dependent mechanical and electrical processes along with strong electromechanical coupling has clouded physical interpretation of the numerous investigations. 

The WLF approach is a general extension of the VTF treatment to characterize relaxation processes in amorphous systems. Any temperature-dependent mechanical relaxation process, R, can be expressed in terms of a universal scaling law ... 

Another example is a recently discovered second mode of action by which nuclear receptors modulate transcription. In contrast to DNA-binding-dependent mechanisms, cross talk refers here to gene regulation by protein-protein-interaction of nuclear receptors with other transcription factors, such as AP-1 or NF-kB. Consequently, the nuclear receptor acts as a corepressor or coactivator of transcription. 

The nuclear pore complex, located in the nuclear envelope, contains more than 50 proteins. It allows diffusion of small proteins between cytoplasm and nucleoplasm. Larger molecules (>50kD) are selectively transported by an energy-dependent mechanism. 

In eukaryotes there is also evidence that Met(O) is actively transported. It has been reported that Met(O) is transported into purified rabbit intestinal and renal brush border membrane vesicles by a Met-dependent mechanism and accumulates inside the vesicles against a concentration gradient102. In both types of vesicles the rate of transport is increased with increasing concentrations of Na+ in the incubation medium. The effect of the Na+ is to increase the affinity of Met(O) for the carrier. Similar to that found in the bacterial system, the presence of Met and other amino acids in the incubation medium decreased the transport of Met(O). These results suggest that Met(O) is not transported by a unique carrier. 

Other reports on the morphology and mechanical behavior of organosiloxane containing copolymeric systems include polyurethanes 201 202), aliphatic 185, 86) and aromatic117,195> polyesters, polycarbonates 233 236>, polyhydroxyethers69,311, siloxane zwitterionomers 294 295) and epoxy networks 115>. All of these systems display two phase morphologies and composition dependent mechanical properties, as expected. 

Wikler A Opioid Dependence Mechanisms and Treatment. New York, Plenum, 1980 Williams JT, Christie MJ, Manzoni O Cellular and synaptic adaptations mediating opioid dependence. Physiol Rev 81 299—343, 2001 Woody GE, O Brien CR, Rickels K Depression and anxiety in heroin addicts a placebo-controlled study of doxepin in combination with methadone. Am J Psychiatry 132 447--i50, 1975... 

Mast cells express high-affinity IgE Fc receptors (FceRI) on their surface, contain cytoplasmic granules which are major sources of histamine and other inflammatory mediators, and are activated to release and generate these mediators by IgE-dependent and non-IgE-dependent mechanisms [1]. Disturbances either in the release of mast cell mediators or in mast cell proliferation are associated with clonal mast cell disorders including monoclonal mast cell activation syndrome (MMAS) and mastocytosis respectively, which are in turn associated with some cases of anaphylaxis [2], Molecular mechanisms have been identified which may link increased releasability of mast cell mediators and conditions leading to increased mast cell numbers [3]. Patients with mastocytosis have an increased risk to develop anaphylaxis [4, 5] and those with anaphylaxis may suffer from unrecognized mastocytosis or may display incomplete features of the disease [6-8]. 

A more recently recognized mechanism of dmg resistance is that of efflux in which the antibiotic is rapidly extmded horn the cell by an energy-dependent mechanism. This affects antibiotics such as the tetracyclines and macrolides. 

These observations were rationaUzed by invoking two parallel, [L]-dependent mechanisms for the catalysis, one via monomeric platinum species (Scheme 5-5)... 

Rowley, D.A. and HaUiwell, B. (1983a). Formation of hydroxyl radicals from hydrogen peroxide and iron salts by superoxide-and ascorbate-dependent mechanisms relevance to the pathology of rheumatoid disease. Clin. Sci. 64, 649-654. 

Domin J, Harper L, Aubyn D, et al. The class II phosphoinositide 3-kinase PI3K-C2beta regulates cell migration by a PtdIns(3)P dependent mechanism. J Cell Physiol 2005 205(3) 452 162. 

Khandaker MH, Xu L, Rahimpour R, et al. CXCR1 and CXCR2 are rapidly down-modulated by bacterial endotoxin through a unique agonist-independent, tyrosine kinase-dependent mechanism. J Immunol 1998 161 1930-1938. 

Fulkerson PC, Zhu H, Williams DA, Zimmermann N, Rothenberg ME. CXCL9 inhibits eosinophil responses by a CCR3- and Rac2-dependent mechanism. Blood 2005 106 436-443. 

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