Attenuation, definition

If we now transfer our two interacting particles from the vacuum (whose dielectric constant is unity by definition) to a hypothetical continuous isotropic medium of dielectric constant e > 1, the electrostatic attractive forces will be attenuated because of the medium s capability of separating charge. Quantitative theories of this effect tend to be approximate, in part because the medium is not a structureless continuum and also because the bulk dielectric constant may be an inappropriate measure on the molecular scale. Eurther discussion of the influence of dielectric constant is given in Section 8.3. 

The vertical spring and mass is an example of a stable system and by definition this means that an arbitrary small external force does not cause the mass to depart far from the position of equilibrium. Correspondingly, the mass vibrates at small distances from the position of equilibrium. Stability of this system directly follows from Equation (3.102) as long as the mechanical sensitivity has a finite value, and it holds for any position of the mass. First, suppose that at the initial moment a small impulse of force is applied, delta function, then small vibrations arise and the mass returns to its original position due to attenuation. If the external force is small and constant then the mass after small oscillations occupies a new position of equilibrium, which only differs slightly from the original one. In both cases the elastic force of the spring is directed toward the equilibrium and this provides stability. Later we will discuss this subject in some detail. 

Typical sections through vent panels evaluated in the suppressive shields program are shown in Fig. 36, together with definitions of vent area ratios which were found to correlate with attenuation of transmitted blast waves. 

The International Union of Pure and Applied Chemistry recommends that the definition should now be based on the ratio of the radiant power of incident radiation (Pq) to the radiant power of transmitted radiation (P). Thus, A = log(Po/P) = log T. In solution, Pq would refer to the radiant power of light transmitted through the reference sample. T is referred to as the transmittance. If natural logarithms are used, the quantity, symbolized by P, is referred to as the Napierian absorbance. Thus, B = ln(Po/P). The definition assumes that light reflection and light scattering are negligible. If not, the appropriate term for log(Po/P) is attenuance. See Beer-Lambert Law Absorption Coefficient Absorption Spectroscopy... 

For most practical photopolymerizations there is appreciable attenuation of light intensity with penetration and the dependence of polymerization rate on monomer, photoinitiator, and light intensity is more complex (see Eqs. 3-54 and 3-55 for exact definitions). Equation 3-54 is especially useful for analyzing the practical aspects of a photopolymerization. When polymerizing any specific thickness of reaction system it is important to know Rp at various depths (e.g., front, middle, and rear surfaces) than to know only the total Rp for that system thickness. If the thickness is too large, the polymerization rate in the rear (deeper) layers will be too low, and those layers will be only partially polymerized—the result would be detrimental because the product s properties (especially the physical properties) would be... 

If an antidepressant is discontinued too early, rapid and serious relapse may result. This indicates that, whereas antidepressants may shorten or curb a depressive episode, they cannot definitely end and hence cure it. The attenuation of depressive symptoms is thus not a sufficient criterion for withdrawing drug therapy (Chapter 8). The decision as to when an antidepressant may be discontinued is often difficult and also dependent on the chronicitv of the patient s depression and the number of episodes of depression experienced. 

Western ethics may also involve an attenuation of the ego, but in general as means rather than as an end, and it never pursues this to the limit. The renunciating of one s attachments is a value in the West, but it exists as a means to help or serve others or God better (one distributes one s worldly goods to the poor ) not, as is the case in Buddhism, as a direct means to achieve the absence of suffering. The individual may also be devalued in comparison with the social class of which he is a member, but the Buddhist will retort that in fact such an individual does not exist, that he is merely an illusion. Humility, as when one says that the self is small when compared with God, is largely a way of increasing God s stature by relying upon a very resilient self for support. In fact, a Buddhist will reply, none of that exists, neither God nor self (or, more precisely, there is undoubtedly no God for the theravada Buddhist and there is definitely no self for all Buddhists). 

Figure 25.7 Nondimensional attenuation coefficient, a, and 10-1 specific phase shift, P, for sinusoidal input into a saturated groundwater system as a function 10 2 of the Peclet Number Pe. The numbers attributed to the different 1 q 3 lines give the nondimensional angular frequency 2. See text for definitions. 10-4...

For the definition of attenuation of intensity, the multiplier in front of the log is 20 rather than 10. 

The National Committee for Sugar Analysis, through the activities of its subcommittee on color evaluation, has recommended the above definitions of absorbancy and attenuancy. General adoption of these terms by the sugar industry would be a contribution to uniform reporting of their results. 

There are many potential mechanisms responsible for the occurrence of aspirin resistance or nonresponsiveness. Many of these studies reporting aspirin resistance have employed methods that did not isolate COX-1 inhibition and/or used treatment failure as their definition for aspirin resistance. Cigarette smoking, noncompliance, transient expression of COX-2 in newly formed platelets, and extra-platelet sources of PGG2/PGH2 (endothelial cells, monocytes/macrophages) may contribute to an attenuated clinical response to aspirin (63-66). Erythrocytes may attenuate the effect of aspirin by... 

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