Physical mechanism

The physical mechanisms of gravitational lenses are well known since the foundation of General Relativity. Any mass concentration is going to deflect photons that are passing by with a fraction angle per unit length, 56/5s, given 

In practice, the total deflection angle is at most about an arcmin. This is the case for the most massive galaxy clusters. It implies that in the subsequent calculations it is possible to ignore the bending of the trajectories and calculate the lens effects as if the trajectories were straight lines. This is the Bom 

Eventually, one can do another approximation by noting that in general the deflection takes place along a very small fraction of the trajectory between the sources and the observer. One can then assume that the lens effect is instantaneous and is produced through the crossing of a plane, the lens plane. This is 

The direct consequence of this bending is a displacement of the apparent position of the background objects. This apparent displacement depends on the distance of the source plane, Dos, and on the distance between the lens plane and the source plane Drs- More precisely we have (see Fig. 13.1), 

1 We will see in section 13.3 what is its meaning in a cosmological context. 

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From standpoint of aims of the technical diagnostics (TD) it is necessary to select two probable states of the NDT objects (NDTO). The first, when defect in the material already has been formed might characterize as defective state of material (DSM). And second - when defect is not yet formed, but exist so changes in the spatial (volume) distribution (SD) of the physical-mechanical features (PMF) of the material, of its tense-deformed state (TDS), which under certain conditions will initiate defect origination. This is predefective state of material (PDSM). 

There are two approaches to explain physical mechanism of the phenomenon. The first model is based on the existence of the difference between the saturated vapor pressures above two menisci in dead-end capillary. It results in the evaporation of a liquid from the meniscus of smaller curvature ( classical capillary imbibition) and the condensation of its vapor upon the meniscus of larger curvature originally existed due to capillary condensation. 

Thus it is necessary to find alternative approach to describe the physical mechanism of two-side filling of conical capillaries with hquids. Theoretical model of film flow in conical dead-end capillary is based on the concept of disjoining pressure II in thin liquid film [13]... 

One more experimental result, which is important for PT is as follows. Only polar liquids fill conical capillaries from both sides. We used various penetrants to fill conical defects Pion , LZh-6A , LZhT , LUM-9 etc. It was established that only the penetrants containing polar liquid as the basic liquid component (various alcohols, water and others) manifest two-side filling phenomenon. This result gives one more confirmation of the physical mechanism of the phenomenon, based on liquid film flow, because the disjoining pressure strongly depends just on the polarity of a liquid. 

Physical mechanism of two-side filling of dead-end capillaries with liquids, based on liquid film flow along the wall, is proposed for the first time. Theoretical model correlates with experimental data. 

We begm tliis section by looking at the Solomon equations, which are the simplest fomuilation of the essential aspects of relaxation as studied by NMR spectroscopy of today. A more general Redfield theory is introduced in the next section, followed by the discussion of the coimections between the relaxation and molecular motions and of physical mechanisms behind the nuclear relaxation. 

Abstract. A model of the conformational transitions of the nucleic acid molecule during the water adsorption-desorption cycle is proposed. The nucleic acid-water system is considered as an open system. The model describes the transitions between three main conformations of wet nucleic acid samples A-, B- and unordered forms. The analysis of kinetic equations shows the non-trivial bifurcation behaviour of the system which leads to the multistability. This fact allows one to explain the hysteresis phenomena observed experimentally in the nucleic acid-water system. The problem of self-organization in the nucleic acid-water system is of great importance for revealing physical mechanisms of the functioning of nucleic acids and for many specific practical fields. 

Analytical separations may be classified in three ways by the physical state of the mobile phase and stationary phase by the method of contact between the mobile phase and stationary phase or by the chemical or physical mechanism responsible for separating the sample s constituents. The mobile phase is usually a liquid or a gas, and the stationary phase, when present, is a solid or a liquid film coated on a solid surface. Chromatographic techniques are often named by listing the type of mobile phase, followed by the type of stationary phase. Thus, in gas-liquid chromatography the mobile phase is a gas and the stationary phase is a liquid. If only one phase is indicated, as in gas chromatography, it is assumed to be the mobile phase. 

Mechanisms of Leukocyte Adsorption. The exact mechanism of leukocyte adhesion to filter media is not yet fuUy understood. Multiple mechanisms simultaneously contribute to the adhesion of cells to biomaterials, however, physical and biological mechanisms have been distinguished. Physical mechanisms include barrier phenomenon, surface tension, and electrostatic charge biological mechanisms include cell activation and cell to cell binding. 

This article focuses primarily on the properties of the most extensively studied III—V and II—VI compound semiconductors and is presented in five sections (/) a brief summary of the physical (mechanical and electrical) properties of the 2incblende cubic semiconductors (2) a description of the metal organic chemical vapor deposition (MOCVD) process. MOCVD is the preferred technology for the commercial growth of most heteroepitaxial semiconductor material (J) the physics and (4) apphcations of electronic and photonic devices and (5) the fabrication process technology in use to create both electronic and photonic devices and circuits. 

Physical, mechanical, and thermal constants of tin are shown in Table 1. 

Syndiotactic polybutadiene was fkst made by Natta in 1955 (28) with a melting point of 154°C. Syndiotactic polybutadiene [31567-90-5] can be prepared with various melting points depending on its vinyl content and degree of crystallinity. The physical, mechanical, and rheological properties of the polymer are gready affected by these parameters. 

Another chapter deals with the physical mechanisms of deformation on a microscopic scale and the development of micromechanical theories to describe the continuum response of shocked materials. These methods have been an important part of the theoretical tools of shock compression for the past 25 years. Although it is extremely difficult to correlate atomistic behaviors to continuum response, considerable progress has been made in this area. The chapter on micromechanical deformation lays out the basic approaches of micromechanical theories and provides examples for several important problems. 

The surface preparation must enable and promote the formation of bonds across the adherend/primer-adhesive interface. These bonds may be chemical (covalent, acid-base, van der Waals, hydrogen, etc.), physical (mechanical interlocking), diffusional (not likely with adhesive bonding to metals), or some combination of these (Chapters 7-9). 

Modifications of the wood surface can be performed by various physical, mechanical and chemical treatments. Chemical treatments especially are performed in order to enhance the dimensional stability, but also for amelioration of physical and mechanical properties or a higher resistance against physical, chemical and biological degradation. 

The benign shock paradigm is clearly an approximation, but one that has proven very effective. The catastrophic shock paradigm corresponds to the known physical, mechanical, and chemical processes, but its characteristics have proven difficult to quantify. 

It is of interest to compare the observations with different physical mechanisms as shown in Fig. 5.19. Typically, the polarization values for polymers are weak and do not overlap those of piezoelectrics. What is observed is that there is over a 6 order-of-magnitude range in polarizations from the weakest signals (Teflon) to the strongest (PZT 95-5). The polarization signals from ionic crystals are stronger than those in polymers and overlap those of piezoelectrics, albeit at larger strains. 

D. C. Guell, H. Brenner. Physical mechanism of membrane osmotic phenomena. Ind Eng Chem Res 55 3004, 1996. 

There is arbitr iriness in describing phenomena as either physical or chemical, but in some sense the nuclear relaxation mechanisms we have discussed to this point are physical mechanisms, based as they are on rotational motions of molecules, magnetic dipole-dipole interactions, quadrupolar interactions, and so on. Now we discuss a nuclear relaxation mechanism that is chemical in origin. 

Annual Book of ASTM Standards Metals-Physical, Mechanical and Corrosion Testing... 

Despite the technical study and examination of this subject, it is important to recognize that because of the variety of factors noted earlier, the designer should not expect precise resulls and should allow considerable flexibility in the physical/mechanical design in order to adjust the system to achieve the required results. 

The effective use of metals as materials of construction must be based on an understanding of their physical, mechanical and chemical properties. These last, as pointed out earlier, cannot be divorced from the environmental conditions prevailing. Any fundamental approach to the phenomena of corrosion must therefore involve consideration of the structural features of the metal, the nature of the environment and the reactions that occur at the metal/environment interface. The more important factors involved may be summarised as follows ... 

The choice of alloy for any particular application is determined by the desired physical, mechanical and metallurgical properties. Within these limits, however, a range of materials is usually available. It is essential that at the very earliest stage the choice of materials and the details of design of the installation should be considered from the point of view of corrosion, if the best performance is to be obtained in service. This is particularly true of copper alloys, where protective measures are not normally applied. 

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