246 research outputs found
Critical sound attenuation in a diluted Ising system
The field-theoretic description of dynamical critical effects of the
influence of disorder on acoustic anomalies near the temperature of the
second-order phase transition is considered for three-dimensional Ising-like
systems. Calculations of the sound attenuation in pure and dilute Ising-like
systems near the critical point are presented. The dynamical scaling function
for the critical attenuation coefficient is calculated. The influence of
quenched disorder on the asymptotic behaviour of the critical ultrasonic
anomalies is discussed.Comment: 12 RevTeX pages, 4 figure
Practice of using the magnetic treatment devices to intensify the processes of primary oil treating
During the primary treatment of oil, gas and water, complications arise associated with the presence of hard water-oil emulsions, which cause an increase in fluid pressure in the gathering systems, pipeline damage, as well as difficulties in gas separation and preliminary water discharge at the preliminary discharge unit (PRU). Additional problems arise during transportation of highly paraffinic oils associated with the crystallization of paraffin in the flow path of the oilfield equipment and on the inner surface of pipes, leading to a drop in the productivity of pipelines.
Article discusses the technology of magnetic-reagent treatment of water-oil media, which allows intensifying the processes of primary oil treatment at the facilities of its production. Bench and pilot tests have shown the ability of the magnetic field to accelerate oil demulsification processes, increasing the percentage of separated water during subsequent settling, and to reduce asphalt-resin-paraffin deposits (ARPD) on the inner surface of oil and gas field equipment.
Mechanism of the magnetic field effect on water-oil media is described. Effect of treatment on the integrity of the armour shells of oil-water emulsions was studied. Various modes of magnetic treatment have been investigated with evaluation of its effectiveness. It is shown that the best effect is achieved with the combined use of reagents and a magnetic field. Synergistic effect is observed, which consists in increasing their effectiveness. This made it possible to conclude that this method can be applied to reduce the consumption of reagents used in oil production while maintaining the treatment efficiency
Eigenvalue estimates for non-selfadjoint Dirac operators on the real line
We show that the non-embedded eigenvalues of the Dirac operator on the real
line with non-Hermitian potential lie in the disjoint union of two disks in
the right and left half plane, respectively, provided that the of
is bounded from above by the speed of light times the reduced Planck
constant. An analogous result for the Schr\"odinger operator, originally proved
by Abramov, Aslanyan and Davies, emerges in the nonrelativistic limit. For
massless Dirac operators, the condition on implies the absence of nonreal
eigenvalues. Our results are further generalized to potentials with slower
decay at infinity. As an application, we determine bounds on resonances and
embedded eigenvalues of Dirac operators with Hermitian dilation-analytic
potentials
Eigenvalue bounds for Schr\"odinger operators with a homogeneous magnetic field
We prove Lieb-Thirring inequalities for Schr\"odinger operators with a
homogeneous magnetic field in two and three space dimensions. The inequalities
bound sums of eigenvalues by a semi-classical approximation which depends on
the strength of the magnetic field, and hence quantifies the diamagnetic
behavior of the system. For a harmonic oscillator in a homogenous magnetic
field, we obtain the sharp constants in the inequalities.Comment: 12 page
Upper and lower limits on the number of bound states in a central potential
In a recent paper new upper and lower limits were given, in the context of
the Schr\"{o}dinger or Klein-Gordon equations, for the number of S-wave
bound states possessed by a monotonically nondecreasing central potential
vanishing at infinity. In this paper these results are extended to the number
of bound states for the -th partial wave, and results are also
obtained for potentials that are not monotonic and even somewhere positive. New
results are also obtained for the case treated previously, including the
remarkably neat \textit{lower} limit with (valid in the Schr\"{o}dinger case, for a class of potentials
that includes the monotonically nondecreasing ones), entailing the following
\textit{lower} limit for the total number of bound states possessed by a
monotonically nondecreasing central potential vanishing at infinity: N\geq
\{\{(\sigma+1)/2\}\} {(\sigma+3)/2\} \}/2 (here the double braces denote of
course the integer part).Comment: 44 pages, 5 figure
Lieb-Thirring inequalities for geometrically induced bound states
We prove new inequalities of the Lieb-Thirring type on the eigenvalues of
Schr\"odinger operators in wave guides with local perturbations. The estimates
are optimal in the weak-coupling case. To illustrate their applications, we
consider, in particular, a straight strip and a straight circular tube with
either mixed boundary conditions or boundary deformations.Comment: LaTeX2e, 14 page
Experimental study of direct photon emission in K- --> pi- pi0 gamma decay using ISTRA+ detector
The branching ratio in the charged-pion kinetic energy region of 55 to 90 MeV
for the direct photon emission in the K- --> pi- pi0 gamma decay has been
measured using in-flight decays detected with the ISTRA+ setup operating in the
25 GeV/c negative secondary beam of the U-70 PS. The value
Br(DE)=[0.37+-0.39(stat)+-0.10(syst)]*10^(-5) obtained from the analysis of 930
completely reconstructed events is consistent with the average value of two
stopped-kaon experiments, but it differs by 2.5 standard deviations from the
average value of three in-flight-kaon experiments. The result is also compared
with recent theoretical predictions.Comment: 13 pages, 8 figure
Remote monitoring of adolescents with type 1 diabetes mellitus using a mobile application
Background: The prevalence of type 1 diabetes mellitus (T1DM) in childhood is increasing every year. Adolescence is the most challenging age for achieving optimal metabolic control of T1DM. Telemedicine has already been shown to be effective in children with the condition, but there are not enough studies in adolescents. The use of mobile apps may be associated with better glycemic control in patients with type 1 diabetes.Aims: To assess the effectiveness and safety of a model of medical care for adolescents with type 1 diabetes using remote counseling and a mobile application.Materials and methods: Were included adolescents aged ≥14 and 18 years with a T1DM duration> 3 months, a glycated hemoglobin level (HbA1c)> 7%. The duration of the study was 26 weeks. There were 3 face-to-face and at least 4 remote visits using a mobile application. All patients underwent standard examination and anthropometry, study of HbA1c, registration and analysis of indicators, assessment and correction of the treatment. The quality of life of adolescents was assessed at baseline and at the end of the study. Adolescents and physicians were interviewed about program evaluation.Results: 56 patients were included, 7 adolescents withdrew. HbA1c significantly decreased by the 12th week of the study (–0.3%; p = 0.005), by the end of the study the change in HbA1c was –0.5% (p <0.001). There was an increase in the percentage of glucose measurements in the target range (+5.3 pp; p = 0.016) and a decrease in blood glucose variability (-3.1 pp; p = 0.015). There was a significant improvement in both the total assessment of the quality of life by patients (+2.9 points; p = 0.008) and individual components of its indicators: attitude to diabetes (+3.0 points; p = 0.049), attitude to treatment (+4.6 points; p = 0.010) and communication with others (+4.5 points; p = 0.015). The majority of doctors and patients assessed their participation in the study positively. The incidence of adverse events did not change significantly during the study from baseline.Conclusion: Remote counseling using a mobile app is a safe and effective approach for adolescents with T1DM in terms of glycemic control and quality of life, and provides convenience and speed of interaction
Complex zeros of real ergodic eigenfunctions
We determine the limit distribution (as ) of complex
zeros for holomorphic continuations \phi_{\lambda}^{\C} to Grauert tubes of
real eigenfunctions of the Laplacian on a real analytic compact Riemannian
manifold with ergodic geodesic flow. If is an
ergodic sequence of eigenfunctions, we prove the weak limit formula
\frac{1}{\lambda_j} [Z_{\phi_{j_k}^{\C}}] \to \frac{i}{\pi} \bar{\partial}
{\partial} |\xi|_g, where [Z_{\phi_{j_k}^{\C}}] is the current of
integration over the complex zeros and where is with respect
to the adapted complex structure of Lempert-Sz\"oke and Guillemin-Stenzel.Comment: Added some examples and references. Also added a new Corollary, and
corrected some typo
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