541 research outputs found
The Electron-Phonon Interaction of Low-Dimensional and Multi-Dimensional Materials from He Atom Scattering
Atom scattering is becoming recognized as a sensitive probe of the
electron-phonon interaction parameter at metal and metal-overlayer
surfaces. Here, the theory is developed linking to the thermal
attenuation of atom scattering spectra (in particular, the Debye-Waller
factor), to conducting materials of different dimensions, from quasi-one
dimensional systems such as W(110):H(11) and Bi(114), to quasi-two
dimensional layered chalcogenides and high-dimensional surfaces such as
quasicrystalline 2ML-Ba(0001)/Cu(001) and d-AlNiCo(00001). Values of
obtained using He atoms compare favorably with known values for the bulk
materials. The corresponding analysis indicates in addition the number of
layers contributing to the electron-phonon interaction that is measured in an
atom surface collision.Comment: 23 pages, 5 figures, 1 tabl
Mixing of fermion fields of opposite parities and baryon resonances
We consider a loop mixing of two fermion fields of opposite parities whereas
the parity is conserved in a Lagrangian. Such kind of mixing is specific for
fermions and has no analogy in boson case. Possible applications of this effect
may be related with physics of baryon resonances. The obtained matrix
propagator defines a pair of unitary partial amplitudes which describe the
production of resonances of spin and different parity or
. The use of our amplitudes for joint description of
partial waves and shows that the discussed effect is clearly
seen in these partial waves as the specific form of interference between
resonance and background. Another interesting application of this effect may be
a pair of partial waves and where the picture is more
complicated due to presence of several resonance states.Comment: 22 pages, 6 figures, more detailed comparison with \pi N PW
Meromorphic Approximants to Complex Cauchy Transforms with Polar Singularities
We study AAK-type meromorphic approximants to functions , where is a
sum of a rational function and a Cauchy transform of a complex measure
with compact regular support included in , whose argument has
bounded variation on the support. The approximation is understood in -norm
of the unit circle, . We obtain that the counting measures of poles of
the approximants converge to the Green equilibrium distribution on the support
of relative to the unit disk, that the approximants themselves
converge in capacity to , and that the poles of attract at least as many
poles of the approximants as their multiplicity and not much more.Comment: 39 pages, 4 figure
Fractional Kinetics for Relaxation and Superdiffusion in Magnetic Field
We propose fractional Fokker-Planck equation for the kinetic description of
relaxation and superdiffusion processes in constant magnetic and random
electric fields. We assume that the random electric field acting on a test
charged particle is isotropic and possesses non-Gaussian Levy stable
statistics. These assumptions provide us with a straightforward possibility to
consider formation of anomalous stationary states and superdiffusion processes,
both properties are inherent to strongly non-equilibrium plasmas of solar
systems and thermonuclear devices. We solve fractional kinetic equations, study
the properties of the solution, and compare analytical results with those of
numerical simulation based on the solution of the Langevin equations with the
noise source having Levy stable probability density. We found, in particular,
that the stationary states are essentially non-Maxwellian ones and, at the
diffusion stage of relaxation, the characteristic displacement of a particle
grows superdiffusively with time and is inversely proportional to the magnetic
field.Comment: 15 pages, LaTeX, 5 figures PostScrip
Understanding Anomalous Transport in Intermittent Maps: From Continuous Time Random Walks to Fractals
We show that the generalized diffusion coefficient of a subdiffusive
intermittent map is a fractal function of control parameters. A modified
continuous time random walk theory yields its coarse functional form and
correctly describes a dynamical phase transition from normal to anomalous
diffusion marked by strong suppression of diffusion. Similarly, the probability
density of moving particles is governed by a time-fractional diffusion equation
on coarse scales while exhibiting a specific fine structure. Approximations
beyond stochastic theory are derived from a generalized Taylor-Green-Kubo
formula.Comment: 4 pages, 3 eps figure
HEART RATE VARIABILITY IN HEMODIALYSIS PATIENTS
There are a small number of works that have studied heart rhythm variability parameters in patients treated with hemodialysis.
Aim. To investigate the peculiarities of heart rhythm variability parameters in patients treated with hemodialysis.
Methods. The observational controlled study included 55 patients treated with hemodialysis, aged 24 to 75 years, including 29 men and 26 women. The control group consisted of 20 healthy individuals of comparable age and sex. Heart rhythm variability parameters were investigated in all patients.
Results. In the study of heart rhythm variability in patients treated with hemodialysis comparatively with the control group time parameters and most of frequency indexes were decreased.
Conclusions. Our study found the diminishment of the total power of neurohumoral regulation in patients treated hemodialysis, as evidenced by the low values SDNN, rNN50, CV
RATING EVALUATION OFSPECIALIZED MEDICAL CARE BYTHEPATIENTSNEPHROLOGIC PROFILE OFTHE UKRAINEPROVINSE
The aim of the work was to conduct a comparative analysis of indicators of the performance of nephrological services in the regions of Ukraine by using the method of complex statistical coefficients.
Materials and methods. Evaluation of the performance of the system of provision of nephrological services in the regions of Ukraine was made by studying the indicators that characterize the structure, use of health care resources, quality and efficiency of its provision submitted to National Register ofpatients with chronic kidney disease and patients with acute kidney injury (2015).
Results. By using rating evaluation methodology, it was identified place of relevant region by each indicator, by each area and by all areas of provision of nephrological services in the region as a whole.
Conclusions. As a result of a comprehensive study of the condition of the system of providing nephrological service in the regions, there were identified ranking places of the administrative territories
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