Second harmonic electromagnetic emission of a turbulent magnetized plasma driven by a powerful electron beam

The power of second harmonic electromagnetic emission is calculated for the case when strong plasma turbulence is excited by a powerful electron beam in a magnetized plasma. It is shown that the simple analytical model of strong plasma turbulence with the assumption of a constant pump power is able to explain experimentally observed bursts of electromagnetic radiation as a consequence of separate collapse events. It is also found that the electromagnetic emission power calculated for three-wave interaction processes occurring in the long-wavelength part of turbulent spectrum is in order-of-magnitude agreement with experimental results

Homology class of a Lagrangian Klein bottle

It is shown that an embedded Lagrangian Klein bottle represents a non-trivial mod 2 homology class in a compact symplectic four-manifold $(X,\omega)$ with $c_1(X)\cdot[\omega]>0$. (In versions 1 and 2, the last assumption was missing. A counterexample to this general claim and the first proof of the corrected result have been found by Vsevolod Shevchishin.) As a corollary one obtains that the Klein bottle does not admit a Lagrangian embedding into the standard symplectic four-space.Comment: Version 3 - completely rewritten to correct a mistake; Version 4 - minor edits, added references; AMSLaTeX, 6 page

Strain-Hardening Stages and Structure Evolution in Pure Niobium and Vanadium upon High Pressure Torsion

High pressure torsion (HPT) is one of the ways to form nanostructured materials with high strength properties. However, HPT hardening mechanisms vary from material to material and are poorly understood for some BCC metals, particularly niobium and vanadium. This work aims to identify strain hardening stages for Nb and V metals during HPT. Two approaches have been used to identify the deformation stages during high pressure torsion. The approaches are based on the application of a "piecewise" model, taking into account the different deformation mechanisms that determine the type of the forming structure, and on the analysis of the hardness vs. true strain dependence according to the $H$$-$${e}^{0.5}$ law. We compared the identified stages with the results of the electron microscopic study of the structure. Both models describe well the structural changes observed microscopically in HPT-deformed niobium. However, we have shown that only the piecewise model gives an adequate description of the stages of structure development in vanadium. We have provided an explanation for the observed difference in the behavior of niobium and vanadium upon HPT.Comment: 21 pages, 9 figures, 1 tabl

Permian palaeomagnetism of East Kazakhstan and the amalgamation of Eurasia

Most of Kazakhstan belongs to the Ural–Mongol belt, the tectonic evolution of which is poorly understood as demonstrated by disparate tectonic models suggested thus far. We undertook a palaeomagnetic study of Upper Permian basalts and andesites from two localities in east Kazakhstan in order to evaluate the final stages of the evolution of this belt and Eurasian amalgamation. Thermal demagnetization revealed a single pre-tilting characteristic component of ubiquitously reversed polarity from all samples. The mean declination of this remanence from one locality agrees rather well with the Permian European palaeomeridian, whereas that from the other is clockwise rotated by 28°± 8° . The overall mean inclination of −49°± 4° differs by 9.7°± 4.2° from the reference inclination calculated, for our localities, from the Eurasian mean pole for the 245–260 Ma interval and is in agreement with 260–275 Ma data. We account for the observed pattern by either a slightly erroneous rock age (lithologies are somewhat older than indicated by geological data) or non-dipole (octopole) components of the geomagnetic field. Because significant relative motion of the study area with respect to Eurasia is not demonstrated, we conclude that welding of Kazakhstan, Europe and Siberia was essentially completed by Mid-Permian time.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73262/1/j.1365-246X.2003.01879.x.pd

Chaotic Interaction of Langmuir Solitons and Long Wavelength Radiation

In this work we analyze the interaction of isolated solitary structures and ion-acoustic radiation. If the radiation amplitude is small solitary structures persists, but when the amplitude grows energy transfer towards small spatial scales occurs. We show that transfer is particularly fast when a fixed point of a low dimensional model is destroyed.Comment: LaTex + 4 eps file

Flux-splitting schemes for parabolic problems

To solve numerically boundary value problems for parabolic equations with mixed derivatives, the construction of difference schemes with prescribed quality faces essential difficulties. In parabolic problems, some possibilities are associated with the transition to a new formulation of the problem, where the fluxes (derivatives with respect to a spatial direction) are treated as unknown quantities. In this case, the original problem is rewritten in the form of a boundary value problem for the system of equations in the fluxes. This work deals with studying schemes with weights for parabolic equations written in the flux coordinates. Unconditionally stable flux locally one-dimensional schemes of the first and second order of approximation in time are constructed for parabolic equations without mixed derivatives. A peculiarity of the system of equations written in flux variables for equations with mixed derivatives is that there do exist coupled terms with time derivatives

Estimated Inpatient Hospital Stay in Individual Wards: Guidelines on Radiation Safety after Radioiodine Therapy

Radionuclide therapy safety requirements are regulated by the Russian Radiation Safety Standards (RRSS), which state the maximum allowed radionuclide activity in the body and the equivalent dose rate (EDR) of gamma radiation. Therefore, it is necessary to estimate the time of an inpatient hospital stay in specially designed radionuclide therapy wards. The article presents the findings of individual 131I biokinetics studies in 64 patients admitted to radioiodine therapy of thyrotoxicosis and differentiated thyroid cancer. We developed a method to calculate the time interval to reach the EDR of 20μSv/h and the recommended EDR of 3 and 0.3μSv/h for adults and children, respectively. It is based on the measurement of the 131I excretion constant. Keywords: Radioiodine therapy, Radiation safety, Guidelin

СЛУЧАЙ УСПЕШНОГО ХИРУРГИЧЕСКОГО ЛЕЧЕНИЯ ПАЦИЕНТА С ПОЛНЫМ ТРАВМАТИЧЕСКИМ ОТРЫВОМ МОШОНКИ И КОЖНЫХ ПОКРОВОВ ПОЛОВОГО ЧЛЕНА В УСЛОВИЯХ ЦЕНТРАЛЬНОЙ РАЙОННОЙ БОЛЬНИЦЫ

The paper gives the experience with successful surgical treatment for scrotal traumatic avulsion and extensive penal scalping wound. A 28-year-old patient with an agricultural injury was taken to the central district hospital that performed three steps of Vitsin,s operation: primary surgical debridement, penile skin restoration, and scrotoplasty. This injury is extremely rare and the literature and media resources mainly report general information on the problem, the specific cases are sporadic; and this information has not been found in the Russian sources. Some reports deal with restoration of scrotal skin defect resulting from cancer treatment or Fournier ,s phlegmon, but these communications are few. Our case shows that stepwise treatment for such defects, stepwise scrotoplasty in particular, may be easily feasible at a general surgery hospital, even at a district hospital. В статье представлен опыт успешного хирургического лечения травматического отрыва мошонки и обширной скальпированной раны полового члена. Пациент 28 лет с сельскохозяйственной травмой доставлен в центральную районную больницу, где были выполнены 3 этапа операции по Б. А. Вицину: первичная хирургическая обработка раны, восстановление кожных покровов полового члена и скротопластика. Подобная травма крайне редка, и в литературе и медиаресурсах представлены главным образом общие сведения о проблеме, конкретные случаи единичны, а в отечественных источниках подобных сообщений мы не нашли вовсе. Некоторые сообщения посвящены восстановлению кожного дефекта мошонки, возникшего в результате лечения новообразований или в результате флегмоны Фурнье, но и эти сообщения немногочисленны. Наш случай показывает, что этапное лечение подобных дефектов, в частности этапная скротопластика, может быть легко выполнимо в условиях общехирургического стационара даже районной больницы