625 research outputs found
Effects of Turbulent Mixing on the Critical Behavior
Effects of strongly anisotropic turbulent mixing on the critical behavior are
studied by means of the renormalization group. Two models are considered: the
equilibrium model A, which describes purely relaxational dynamics of a
nonconserved scalar order parameter, and the Gribov model, which describes the
nonequilibrium phase transition between the absorbing and fluctuating states in
a reaction-diffusion system. The velocity is modelled by the d-dimensional
generalization of the random shear flow introduced by Avellaneda and Majda
within the context of passive scalar advection. Existence of new nonequilibrium
types of critical regimes (universality classes) is established.Comment: Talk given in the International Bogolyubov Conference "Problems of
Theoretical and Mathematical Physics" (Moscow-Dubna, 21-27 August 2009
Salt sensitivity and timed drug therapy in arterial hypertension. Enhancing antihypertensive drug efficacy: a controlled randomised trial
Background. An elevated or inadequate sensitivity to salt intake is an important mechanism for maintaining high blood pressure in patients with arterial hypertension. Chronopharmacotherapy comprises an important approach to control arterial hypertension through personalised correction of blood pressure but requires a further proof of efficacy in salt-sensitive hypertensive patients.Objectives. An assessment of six-month dynamics of diurnal and nocturnal peripheral and central blood pressure in salt-sensitive patients with arterial hypertension under chronopharmacotherapy.Methods. A controlled randomised trial included 86 salt-sensitive patients with arterial hypertension. Salt sensitivity was estimated with a Kharchenko’s test. All patients had circadian monitoring of the peripheral and central blood pressure and glomerular filtration rate at baseline and in a six-month follow-up. The patients were randomised into 3 cohorts. Cohort A united patients received perindopril and amlodipine in morning, cohort B — perindopril in morning, amlodipine in evening, cohort C — perindopril in evening, amlodipine in morning. Statistica 12 (StatSoftInc, USA) was used for nonparametric statistical analyses.Results. In six months of chronopharmacotherapy a target arterial pressure was registered in 87.5% patients in cohort A, 96.4 and 96.2% patients in cohorts B and C, respectively. All cohorts exhibited a declining peripheral and central blood pressure over therapy. Cohort A had a greater decline in daytime, and cohorts B and C — both diurnally and nocturnally. Cohorts B and C had more patients with an adequate nocturnal blood pressure decline. Glomerular filtration rate also elevated with perindopril or amlodipine intake before bedtime.Conclusion. The perindopril or amlodipine intake before bedtime in a combined therapy for arterial hypertension provided for a target blood pressure in the overall majority of patients, effectively reduced peripheral and central blood pressure at all time intervals, contributed to optimising the circadian blood pressure profile and increased the glomerular filtration rate
Two-dimensional magnetoexcitons in the presence of spin-orbit coupling
We study theoretically the effect of spin-orbit coupling on quantum well
excitons in a strong magnetic field. We show that, in the presence of an
in-plane field component, the excitonic absorption spectrum develops a
double-peak structure due to hybridization of bright and dark magnetoexcitons.
If the Rashba and Dresselhaus spin-orbit constants are comparable, the
magnitude of splitting can be tuned in a wide interval by varying the azimuthal
angle of the in-plane field. We also show that the interplay between spin-orbit
and Coulomb interactions leads to an anisotropy of exciton energy dispersion in
the momentum plane. The results suggest a way for direct optical measurements
of spin-orbit parameters.Comment: 9 pages, 6 figure
Non-Linear Algebra and Bogolubov's Recursion
Numerous examples are given of application of Bogolubov's forest formula to
iterative solutions of various non-linear equations: one and the same formula
describes everything, from ordinary quadratic equation to renormalization in
quantum field theory.Comment: LaTex, 21 page
Sequential superradiant scattering from atomic Bose-Einstein condensates
We theoretically discuss several aspects of sequential superradiant
scattering from atomic Bose-Einstein condensates. Our treatment is based on the
semiclassical description of the process in terms of the Maxwell-Schroedinger
equations for the coupled matter-wave and optical fields. First, we investigate
sequential scattering in the weak-pulse regime and work out the essential
mechanisms responsible for bringing about the characteristic fan-shaped
side-mode distribution patterns. Second, we discuss the transition between the
Kapitza-Dirac and Bragg regimes of sequential scattering in the strong-pulse
regime. Finally, we consider the situation where superradiance is initiated by
coherently populating an atomic side mode through Bragg diffraction, as in
studies of matter-wave amplification, and describe the effect on the sequential
scattering process.Comment: 9 pages, 4 figures. Submitted to Proceedings of LPHYS'06 worksho
Anomalous exponents in the rapid-change model of the passive scalar advection in the order
Field theoretic renormalization group is applied to the Kraichnan model of a
passive scalar advected by the Gaussian velocity field with the covariance
. Inertial-range
anomalous exponents, related to the scaling dimensions of tensor composite
operators built of the scalar gradients, are calculated to the order
of the expansion. The nature and the convergence of
the expansion in the models of turbulence is are briefly discussed.Comment: 4 pages; REVTeX source with 3 postscript figure
Study of the , , Decays with an SND Detector on a VEPP-2M Collider
The process was studied in the energy range
MeV with an SND detector on a VEPP-2M collider. The
decay branching ratios , , and
were measured.Comment: 5 pages, 4 figure
The Minimum Stellar Mass in Early Galaxies
The conditions for the fragmentation of the baryonic component during merging
of dark matter halos in the early Universe are studied. We assume that the
baryonic component undergoes a shock compression. The characteristic masses of
protostellar molecular clouds and the minimum masses of protostars formed in
these clouds decrease with increasing halo mass. This may indicate that the
initial stellar mass function in more massive galaxies was shifted towards
lower masses during the initial stages of their formation. This would result in
an increase of the number of stars per unit halo mass, i.e., the efficiency of
star formation.Comment: 18 pages, 7 figure
Сальважная лимфаденэктомия у пациентов с рецидивом рака предстательной жедезы после радикальной простатэктомии
A separate group of patients who underwent radical prostatectomy, make patients with isolated recurrence of cancer in the lymph nodes, limited by regional and / or retroperitoneal lymph nodes. Alternatively, treatment of this patient group can be used open or laparoscopic lymphadenectomy (robot-assisted). The analysis of literature indicate an increase in disease-free survival of these patients during lymphadenectomy. Imaging techniques such as multiparametric magnetic resonance imaging and positron emission tomography, allow more accurately identify lymph nodes in patients with biochemical recurrence of prostate cancer after radical prostatectomy. Отдельную группу больных, перенесших радикальную простатэктомию, составляют пациенты с изолированным рецидивом рака в лимфатических узлах, ограниченных регионарными и / или забрюшинными лимфатическими узлами. В качестве одного из вариантов лечения данной группы пациентов может быть применена лимфаденэктомия открытым или лапароскопическим (робот-ассистированным) доступами. Проведенный анализ литературных источников указывает на увеличение общей выживаемости данной группы пациентов при проведении лимфаденэктомии. Доступные методы визуализации, такие как мультипараметрическая магнитно-резонансная томография и позитронно-эмиссионная томография, позволяют более точно идентифицировать поражение лимфатических узлов у пациентов с биохимическим рецидивом рака простаты после радикальной простатэктомии.
Magnetic Resonance of the Intrinsic Defects of the Spin-Peierls Magnet CuGeO3
ESR of the pure monocrystals of CuGeO3 is studied in the frequency range 9-75
GHz and in the temperature interval 1.2-25 K. The splitting of the ESR line
into several spectral components is observed below 5 K, in the temperature
range where the magnetic susceptibility is suppressed by the spin-Peierls
dimerization. The analysis of the magnetic resonance signals allows one to
separate the signals of the S=1/2- and S=1 defects of the spin-Peierls phase.
The value of g-factor of these signals is close to that of the Cu-ion. The
additional line of the magnetic resonance is characterized by an anomalous
value of the g-factor and by the threshold-like increase of the microwave
susceptibility when the microwave power is increasing. The ESR signals are
supposingly attributed to two types of the planar magnetic defects, arising at
the boundaries of the domains of the spin-Peierls state with the different
values of the phase of the dimerization.Comment: LATEX-text, 12 PS-figures, typos corrected, LATEX-style change
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