Application of the method of collective coordinates the the quantisation of the two-dimensional higgs model

A comprehensive analysis of the application of the method of collective coordinates to the two dimensional Higgs model is given. First the instanton solution is derived, and the geometry of configuration space, and the construction of Schrodinger wave functionals are discussed. It is then explicitly verified that the Goldstone mode is the projection of the vacuum state onto the generator of the broken symmetry. The elimination of this Goldstone mode by means of the unitary gauge condition is demonstrated to the the crucial point in the construction of a consistent perturbation procedure. The parameter of the broken symmetry group is then used as the collective coordinate for field configurations around a minimum of the interaction. Throughout, the discussion is sufficiently detailed in order to facilitate the application of the method to other fields.     

On the predictability of the positions of the convergence zones in the ocean

The disagreement between the experimental and calculated positions of the first convergence zone are known from many publications. The most probable cause for such a disagreement, namely, the incorrect specification of the input data for the calculations, is considered. The lack of simultaneity between the hydrological surveys of the region and the acoustic experiments is emphasized. The experimental data obtained by the author in five ocean regions are presented. These data characterize the diurnal variability of the distance from the source to the nearest boundary of the convergence zone. The relations proposed by different researchers for calculating the sound speed from the temperature, salinity, and hydrostatic pressure are analyzed. It is shown that these relations lead to a substantial difference in the estimated depth dependence of the hydrostatic gradient of the sound speed. The position of the first convergence zone is calculated for the propagation conditions determined by vertical temperature and salinity profiles with the subsequent recalculation of these profiles into sound speed profiles by using eight different formulas known from the literature. It is shown that different formulas lead to different values of the distance to the first zone; this difference is substantially greater than that between the calculations and experiment. The necessity of improving the recalculation relations in view of the experimental data on sound propagation in natural oceanic waveguides, including the data on the actual positions of the convergence zones, is emphasized.     

Effect of the architecture of the left ventricle on the speed of the excitation wave in muscle fibers

It is known that preferential paths for the propagation of an electrical excitation wave in the human ventricular myocardium are associated with muscle fibers in tissue. The speed of the excitation wave along a fiber is several times higher than that across the direction of the fiber. To estimate the effect of the architecture and anisotropy of the myocardium of the left ventricle on the process of its electrical activation, we have studied the relation between the speed of the electrical excitation wave in a one-dimensional isolated myocardial fiber consisting of sequentially coupled cardiomyocytes and in an identical fiber located in the wall of a threedimensional anatomical model of the left ventricle. It has been shown that the speed of a wavefront along the fiber in the three-dimensional myocardial tissue is much higher than that in the one-dimensional fiber. The acceleration of the signal is due to the rotation of directions of fibers in the wall and to the position of the excitation wavefront with respect to the direction of this fiber. The observed phenomenon is caused by the approach of the excitable tissue with rotational anisotropy in its properties to a pseudoisotropic tissue.     

Influence of the random dynamic parameters of the human body on the dynamic characteristics of the coupled system of structure-crowd

The presence of human occupants may change the dynamic behaviour of structures considerably. While this effect is considered in mechanical engineering (e.g. interaction between driver seat and driver) and biomechanics (potentially damaging effects of vibrations) by using equivalent mass-spring-damper systems for the human body, the design practice in civil engineering still often clings to the so-called mass-only model, i.e. the occupants are considered only as additional masses when analysing the dynamic behaviour of floor slabs and stand structures. Recent research efforts aim to improve this situation by recommending averaged models for the human body. This approach seems to be reasonable for large crowds; however, for smaller groups, the question arises whether the random scatter in the dynamic characteristics of the human body leads to random scatter in the effective natural frequency and the effective damping of the coupled structure-crowd system. Based on a probabilistic model for the dynamic characteristics of the human body, an extensive study is presented in this paper. The key variables are the natural frequency of the bare structure, the ratio of the crowd’s mass to the structure mass and the group size. The scatter in the effective dynamic characteristics of the coupled system is revealed by the 90%-confidence interval. Furthermore, the maximum span of the respective bounds is used to identify cases where the averaged model fails to predict the real behaviour of the coupled system.     

Calculation of the vacuum condensates of the trace of the energy-momentum tensor

It is shown that a modification of the effective potential proposed by A.A. Migdal and Shifman makes it possble to calculate the vacuum condensates of the trace of the energy-momentum tensor in massless theories in various spacetime dimensions.     

Set the controls for the heart of the Sun

In this paper we describe experiments conducted with high-power lasers that are attempting to replicate, for a very short time and in miniature, conditions found in the Sun. Experiments to date have reached conditions in the outer part of the Sun. To reach the Sun's centre requires compression of material to very much greater than solid density and heating to over ten million degrees. To achieve this, a new class of experiments and a new generation of high-power lasers are required.     

Influence of the thickness of the liquid layer on the ratio of the dimensions of a convection cell

A theory is developed for a new type of transition — a change in the ratio of the longitudinal and transverse dimensions of a convection cell as the thickness of a liquid layer is varied. A sudden change in the ratio of the cell dimensions takes place because of a change in the predominant mechanism for excitation of convection. The governing influence of buoyancy forces gives way to one of thermocapillary forces, and they in turn give way to the influence of thermoelectric forces for yet thinner layers. As the layer thickness is reduced gradually at a fixed external heating, the ratio of the dimensions will take on the values 0.7, 0.65, and 1, respectively. Zh. Tekh. Fiz. 68, 7–11 (November 1998)     

Numerical modeling in the problem of the mechanisms of SAR imaging of the ocean

Based on numerical modeling, we demonstrate the validity of the conclusion, drawn on the basis of theoretical analysis in [1], that the mechanism of fluctuations of the effective density of scatterers, which is commonly accepted at present as the physical basis for the space-borne SAR diagnostics of the ocean surface, actually works only in the case of a sufficiently flat swell in the absence of wind roughness. In all other cases, the dominant role is played by another mechanism, namely, fluctuations of the number of surface elements whose images are randomly shifted and superimposed due to orbital velocities. The special consideration is devoted to the case of mixed roughness comprising both wind roughness and swell. It is shown that, in contrast to long-wavelength narrow-band swell in the absence of large wind waves, the same swell in the mixed roughness is revealed in the linear manner in an SAR image.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 47, No. 9, pp. 753–760, September, 2004.     

On the problem of the distribution of impurity ions in the F-region of the ionosphere

One-dimensional nonisothermal diffusion in ionospheric plasma (the F-region) is considered in the stationary case. The analysis is carried out for two species of positive ions with allowance for the ionization and recombination processes and the effect of gravity. A system of two coupled equations is derived for the concentrations of the electrons and ions. A transition is made to the case when the ions which determine dissociative recombination are impurity ions. For this case criteria are presented whose fulfilment causes the distribution that has been found to coincide with that obtained by Mange [9] without allowance for photochemical processes.     

The role of the pion cloud in the interpretation of the valence light-cone wavefunction of the nucleon

The pion cloud renormalises the light-cone wavefunction of the nucleon which is measured in hard, exclusive photon-nucleon reactions. We discuss the leading twist contributions to high-energy exclusive reactions taking into account both the pion cloud and perturbative QCD physics. The nucleon’s electromagnetic form-factor at high Q² is proportional to the bare nucleon probability Z and the cross-sections for hard (real at large angle or deeply virtual) Compton scattering are proportional to Z². Our present knowledge of the pion-nucleon system is consistent with Z = 0.7 ± 0.2. If we apply just perturbative QCD to extract a light-cone wavefunction directly from these hard exclusive cross-sections, then the light-cone wavefunction that we extract measures the three valence quarks partially screened by the pion cloud of the nucleon. We discuss how this pion cloud renormalisation effect might be understood at the quark level in terms of the (in-)stability of the perturbative Dirac vacuum in low energy QCD.     

Dielectric investigation of the temperature dependence of the nonexponentiality of the dynamics of polymer melts

Using broad band dielectric spectroscopy (10(-5)-10(9) Hz), combining time domain and frequency domain techniques, we study the temperature dependence of the non-Debye character of the alpha relaxation of polymer melts in the glass transition temperature T(g) range. The alpha relaxation process is described in terms of the Kohlrausch-Williams-Watts relaxation function which has a single parameter beta to characterize the nonexponentiality of the relaxation. At high temperatures, beta remains nearly insensitive to temperature changes, whereas in the vicinity of T(g) a nearly linear increasing of beta with temperature is found. The temperature range where the change of the beta(T) behavior occurs is located for all the polymers investigated around 1.2T(g). Moreover, our results indicate a common value of beta approximately equal to 1/3 at the temperature where the relaxation time diverges. The beta(T) behavior near T(g) is discussed in terms of a "rugged landscape" phase space which allows us to rationalize both the beta(T) behavior observed as well as the similarities of our findings near T(g) with the results reported in simulations on Ising spin glasses and other model systems.     

On the role of the amplitude of the fricative noise in the perception of place of articulation in voiceless fricative consonants

The current study explores the role of the amplitude of the fricative noise in the perception of place of articulation in voiceless fricative consonants. The amplitude of the fricative noise in naturally produced fricative-vowel utterances was varied relative to the vowel and potential changes in perceptual responses were investigated. The amplitude of the fricative noise for [s] and [s] was reduced such that the amplitude of the noise relative to the vowel was similar to [f] and [O], and, conversely, the amplitude of the fricative noise of [f] and [O] was increased such that the amplitude of the noise relative to the vowel was similar to [s] and [s]. The fricative noise was presented to listeners in both its vowel context and in isolation. Results indicated that, when the spectral properties of the fricative noise and formant transitions are compatible, the perceptual effects of the amplitude manipulation of the amplitude of the noise had a small effect on the overall identification of place of articulation, and when effects emerged, they varied across the different fricative stimuli. Moreover, although decreasing the amplitude of [s] and [s] resulted in an increase in [f] and [O] responses, increasing the amplitude of [f] and [O] did not result in an increase in [s] and [s] responses. Implications of these findings for phonetic feature theories are considered.     

The ageing of the blood supply and the lymphatic drainage of the skin

The anatomy and functions of the blood and lymph vessels of human skin are described. Variation in these due to site, ageing and events during life consequent to exposure to a threatening environment are emphasised. Gradual atrophy and greater heterogeneity are features of ageing. Responses to injury and repair are complex and the interaction of mechanical signals distorting skin cells with numerous chemical signals are referred to. The lymphatics are part of an immunosurveillance system to monitor skin barrier penetration. The review attempts to draw attention to key recent advances in our understanding of the cytokine and growth factor production of the skin in the context of previous mainly physiological reviews especially influenced by 50 years of clinical practice as a dermatologist with an eye on both the skin and the fields of microcirculation and lymphology.     

An Attempt at the Identification of the Dynamic Properties of the Isomerization Column on the Basis of the Results of Radioisotope Measurements

The present paper makes an attempt of the interpretation of the tracer measurements by means of transfer function. Obtained data of residence time of catalyst in xylene isomerization column inserted in previous paper [1] were used to the identification of dynamic properties of individual sections of the column.     

Determination of the exact solutions to the inhomogeneous burgers equation with the use of the darboux transformation

A method of determining the exact solutions to the Burgers equation on the basis of the Darboux transformation is described. It is shown that a single application of the Darboux transformation to the homogeneous Burgers equation transforms the latter into the inhomogeneous equation describing acoustic wave propagation against transonic flow in the de Laval nozzle. In this case, the contraction ratio of the nozzle is fixed and determined by the viscosity coefficient of the medium. Based on the exact solution of the homogeneous Burgers equation, for the aforementioned problem of the flow in the nozzle, all the possible regular steady-state solutions are presented and the evolution of nonstationary solutions is investigated. The algorithm of a multiple Darboux transformation, which allows an increase in the strength of inhomogeneity, i.e., in the contraction ratio of the nozzle, is determined. This approach leads to a discrete set of possible contraction ratios at which exact solutions can be obtained. The Crum’s theorem is used to derive a formula that allows determination of the exact solutions to the inhomogeneous Burgers equation from the solutions to the homogeneous heat transfer equation. It is noted that, in fact, the proposed algorithm of the multiple Darboux transformation makes it possible to decrease the viscosity coefficient of the medium in a discrete way.     

On the problem of the consistency of the high-temperature precipitation model with the classical nucleation theory

The adequacy of the model of high-temperature precipitation in dislocation-free silicon single crystals to the classical theory of nucleation and growth of second-phase particles in solids has been considered. It has been shown that the introduction and consideration of thermal conditions of crystal growth in the initial equations of the classical nucleation theory make it possible to explain the precipitation processes occurring in the high-temperature range and thus extend the theoretical basis of the application of the classical nucleation theory. According to the model of high-temperature precipitation, the smallest critical radius of oxygen and carbon precipitates is observed in the vicinity of the crystallization front. Cooling of the crystal is accompanied by the growth and coalescence of precipitates. During heat treatments, the nucleation of precipitates starts at low temperatures, whereas the growth and coalescence of precipitates occur with an increase in the temperature. It has been assumed that the high-temperature precipitation of impurities can determine the overall kinetics of defect formation in other dislocation-free single crystals of semiconductors and metals.     

On the Locality of the No Hair Conjecture and the Measure of the Universe

We reanalize the recently proposed proof by Jensen and Stein-Schabes [1] of the No Hair Theorem for inhomogeneous spacetimes, putting a special emphasis on the asymptotic behaviour of the shear and curvature. We conclude that the theorem only holds locally and estimate the minimum size a region should be in order for it to inflate. We discuss in some detail the assumptions used in the theorem. In the last section we speculate about the possible measure of the set of spacetimes that would undergo inflation.     

Determination of the temperature of the onset of ion transport from the temperature dependence of the relative change in the ultrasound velocity in the lithium ceramic Li-Si-Ge-As-S-O

An ultrasonic method is used to study the onset of ion transport inlithium oxides in a ceramic of the Li-Si-Ge-As-S-O system. The onset temperature for ion transport estimated from the temperature dependence of the relative change in the propagation speed of ultrasound is the same as that obtained by other methods, which indicates that the ultrasonic method is applicable to studies of the onset of ion conductivity inlithium oxide semiconductors. Zh. Tekh. Fiz. 69, 137–138 (May 1999)