698 research outputs found
Barriers in the p-spin interacting spin-glass model. The dynamical approach
We investigate the barriers separating metastable states in the spherical
p-spin glass model using the instanton method. We show that the problem of
finding the barrier heights can be reduced to the causal two-real-replica
dynamics. We find the probability for the system to escape one of the highest
energy metastable states and the energy barrier corresponding to this process.Comment: 4 pages, 1 figur
Instantons in the Langevin dynamics: an application to spin glasses
We develop a general technique to calculate the probability of transitions
over the barriers in spin-glasses in the framework of the dynamical theory. We
use Lagrangian formulation of the instanton dynamics in which the transitions
are represented by instantons. We derive the full set of the equations that
determine the instantons but instead of solving them directly we prove that an
instanton process can be mapped into a usual process going back in time which
simplifies the problem significantly. We apply this general considerations to a
simple example of the spherical Sherrington-Kirkpatrick model and we find the
probability of the transition between the metastable states which is in
agreement with physical expectations.Comment: 18 pages, 2 figure
Thermal transport in granular metals
We study the electron thermal transport in granular metals at large tunnel
conductance between the grains, and not too low a temperature , where is the mean energy level spacing for a single grain.
Taking into account the electron-electron interaction effects we calculate the
thermal conductivity and show that the Wiedemann-Franz law is violated for
granular metals. We find that interaction effects suppress the thermal
conductivity less than the electrical conductivity.Comment: Replaced with published versio
Oxygen-conducting Composites Based on Me2(WO4)3 (Me = Sm, Al)
Composites Sm2(WO4)3-WO3 and Al2(WO4)3-WO3 were prepared by the solid-state method and a systematic study of their electrotransport properties has been carried out. A sharp increase in the oxygen-ion conductivity is observed in composites Sm2(WO4)3–WO3 at small WO3 values (about 10 mol.%). This effect is probably caused by formation of the non-autonomous interface phase covering grain boundaries of Sm2(WO4)3. These composite O2− – electrolytes are perspective materials for high temperature fuel cells. Тhe composite effect is absent in the Al2(WO4)3–WO3 system. This is probably due to the negative thermal expansion coefficient of Al2(WO4)3, which prevents the formation of a continuous high-conducting microphase film.
Keywords: composites, ionic conductivity, heterogeneous doping, microphas
Statistically Optimized Inversion Algorithm for Enhanced Retrieval of Aerosol Properties from Spectral Multi-Angle Polarimetric Satellite Observations
The proposed development is an attempt to enhance aerosol retrieval by emphasizing statistical optimization in inversion of advanced satellite observations. This optimization concept improves retrieval accuracy relying on the knowledge of measurement error distribution. Efficient application of such optimization requires pronounced data redundancy (excess of the measurements number over number of unknowns) that is not common in satellite observations. The POLDER imager on board the PARASOL microsatellite registers spectral polarimetric characteristics of the reflected atmospheric radiation at up to 16 viewing directions over each observed pixel. The completeness of such observations is notably higher than for most currently operating passive satellite aerosol sensors. This provides an opportunity for profound utilization of statistical optimization principles in satellite data inversion. The proposed retrieval scheme is designed as statistically optimized multi-variable fitting of all available angular observations obtained by the POLDER sensor in the window spectral channels where absorption by gas is minimal. The total number of such observations by PARASOL always exceeds a hundred over each pixel and the statistical optimization concept promises to be efficient even if the algorithm retrieves several tens of aerosol parameters. Based on this idea, the proposed algorithm uses a large number of unknowns and is aimed at retrieval of extended set of parameters affecting measured radiation
Hall Effect in a Quasi-One-Dimensional System
We consider the Hall effect in a system of weakly coupled one-dimensional
chains with Luttinger interaction within each chain. We construct a
perturbation theory in the inter-chain hopping term and find that there is a
power law dependence of the Hall conductivity on the magnetic field with an
exponent depending on the interaction constant. We show that this perturbation
theory becomes valid if the magnetic field is sufficiently large.Comment: 20 page
On Lagrangian formulations for arbitrary bosonic HS fields on Minkowski backgrounds
We review the details of unconstrained Lagrangian formulations for Bose
particles propagated on an arbitrary dimensional flat space-time and described
by the unitary irreducible integer higher-spin representations of the Poincare
group subject to Young tableaux with rows. The procedure
is based on the construction of Verma modules and finding auxiliary oscillator
realizations for the symplectic algebra which encodes the second-class
operator constraints subsystem in the HS symmetry algebra. Application of an
universal BRST approach reproduces gauge-invariant Lagrangians with reducible
gauge symmetries describing the free dynamics of both massless and massive
bosonic fields of any spin with appropriate number of auxiliary fields.Comment: 8 pages, no figures, extended Contribution to the Proceedings of the
International Workshop "Supersymmetry and Quantum Symmetries" (SQS'2011, July
18- July 23, 2011, Dubna, Russia), v.2: 9 pages, 2 references with comments
in Introduction adde
Superconducting-coil--resistor circuit with electric field quadratic in the current
It is shown for the first time that the observed [Phys. Lett. A 162 (1992)
105] potential difference Phi_t between the resistor and the screen surrounding
the circuit is caused by polarization of the resistor because of the kinetic
energy of the electrons of the superconducting coil. The proportionality of
Phi_t to the square of the current and to the length of the superconducting
wire is explained. It is pointed out that measuring Phi_t makes it possible to
determine the Fermi quasimomentum of the electrons of a metal resistor.Comment: 2 pages, 1 figur
Superconductivity, phase fluctuations and the c-axis conductivity of bilayer high temperature superconductors
We present a theory of the interplane conductivity of bilayer high
temperature superconductors, focusing on the effect of quantal and thermal
fluctuations on the oscillator strengths of the superfluid stiffness and the
bilayer plasmon. We find that the opening of the superconducting gap and
establishment of superconducting phase coherence each lead to redistribution of
spectral weight over wide energy scales. The factor-of-two relation between the
superfluid stiffness and the change below in the oscillator strength of
the absorptive part of the conductivity previously derived for single-layer
systems, is found to be substantially modified in bilayer systems.Comment: 11 pages, 14 figure
Заместительная терапия препаратами антитромбина в комплексном лечении сепсиса
Purpose — to assess the efficacy of supplementation therapy for antithrombin deficiency in the combined treatment of sepsis.Materials and methods. A prospective-retrospective study of the efficacy of supplementation therapy for antithrombin deficiency during sepsis was carried out; 90 patients were examined. The patients were split into two groups whether antithrombin deficiency correction was or was not undertaken. The composite outcome — the incidence of cardiovascular complications as of day 28 from the therapy commencement — was chosen as the primary endpoint of the study. The secondary endpoints of the study were prevalence of adverse events as of day 28 from the therapy commencement and 180-day mortality.Results. There was no difference between the groups either in respect of 28-day mortality or composite outcome. Analysis of secondary endpoints revealed that in the group of patients who received antithrombin supplementation therapy, the risk of development of an acute renal injury was significantly lower on day 28 and 180 from therapy commencement: OR 3.5 [95% CI 1.05–11.66] at P=0.04 and OR 2.92 [95% CI 1.02–8.31] at P=0.045, respectively.Conclusion. Correction of antithrombin level to activity level ‘over 61%’ is associated with decreased incidence degree III acute kidney failure (KDIGO).Цель работы — оценить эффективность применения заместительной терапии недостаточности антитромбина при комплексном лечении сепсиса.Материал и методы. Провели проспективно — ретроспективное исследования эффективности заместительной терапии недостаточности антитромбина при сепсисе; обследованы 90 пациентов. В зависимости от того, проводили ли коррекцию недостаточности антитромбина, пациентов разделили на две группы. Первичной точкой исследования выбрали композитный исход — частоту развития осложнений со стороны сердечно-сосудистой системы через 28 дней после начала лечения. Вторичные точки исследования — частота развития неблагоприятных событий на 28 день от начала лечения и 180 дневная летальность.Результаты. Группы не различались между собой ни по 28-дневной летальности, ни по композитному исходу. При анализе вторичных точек выявили, что в группе пациентов получавших заместительную терапию антитромбином, риск развития острого почечного повреждения был существенно ниже на 28 и 180 сутки от начала лечения: OR 3,5 [95% CI 1,05–11,66] при р=0,04 и OR 2,92 [95% CI 1,02–8,31] при р=0,045, соответственно.Заключение. Коррекция уровня антитромбина до уровня активности «более 61%» ассоциирована со снижением частоты развития острой почечной недостаточности III cт. (KDIGO)
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