On the possible observational manifestation of supernova shock impact on the neutron star magnetosphere

Impact of supernova explosion on the neutron star magnetosphere in a massive binary system is considered. The supernova shock striking the NS magnetosphere filled with plasma can lead to the formation of a magnetospheric tail with significant magnetic energy. The magnetic field reconnection in the current sheet formed can convert the magnetic energy stored in the tail into kinetic energy of accelerated charged particles. Plasma instabilities excited by beams of relativistic particles can lead to the formation of a short pulse of coherent radio emission with parameters similar to those of the observed bright extragalactic millisecond radio burst (Lorimer et al. 2007).Comment: 8 pages, Astron. Lett. in pres

Multi-domain active sound control and noise shielding

This paper describes an active sound control methodology based on difference potentials. The main feature of this methodology is its ability to automatically preserve “wanted” sound within a domain while canceling “unwanted” noise from outside the domain. This method of preservation of the wanted sounds by active shielding control is demonstrated with various broadband and realistic sound sources such as human voice and music in multiple domains in a one-dimensional enclosure. Unlike many other conventional active control methods, the proposed approach does not require the explicit characterization of the wanted sound to be preserved. The controls are designed based on the measurements of the total field on the boundaries of the shielded domain only, which is allowed to be multiply connected. The method is tested in a variety of experimental cases. The typical attenuation of the unwanted noise is found to be about 20 dB over a large area of the shielded domain and the original wanted sound field is preserved with errors of around 1 dB and below through a broad frequency range up to 1 kHz. © 2011 Acoustical Society of Americ

Bounds on positive interior transmission eigenvalues

The paper contains lower bounds on the counting function of the positive eigenvalues of the interior transmission problem when the latter is elliptic. In particular, these bounds justify the existence of an infinite set of interior transmission eigenvalues and provide asymptotic estimates from above on the counting function for the large values of the wave number. They also lead to certain important upper estimates on the first few interior transmission eigenvalues. We consider the classical transmission problem as well as the case when the inhomogeneous medium contains an obstacle.Comment: We corrected inaccuracies cost by the wrong sign in the Green formula (17). In particular, the sign in the definition of \sigma was change

Work of dissertation councils of new system of scientific attestation

Статья посвящена рассмотрению вопроса о том, сохраняет ли свою целостность российская система научной аттестации. Устранение монополии Высшей аттестационной комиссии (ВАК) в вопросах контроля за деятельностью диссертационных советов и процедур защиты диссертаций сделало возможным рост многообразия правил и практик научной аттестации. Множество научных и образовательных организаций разработали собственные регламенты, регулирующие соответствующую деятельность. На уровне законодательства при самостоятельном присуждении ученых степеней было закреплено указание выставлять требования не ниже того, как они сформулированы в федеральных актах. Вопрос о том, как именно реализуется это указание, представляет исследовательский интерес. Кроме того, важно понять, действительно ли в разных частях современной системы соискатели могут получить равные права и возможности. В ходе исследования было выделено три фактически существующие подсистемы, образующие единую систему. Первая состоит из обычных и специальных диссертационных советов, регулируемых напрямую ВАК и Минобрнауки России. Вторая подсистема является совокупностью ведущих научных и образовательных организаций, самостоятельно присуждающих ученые степени. И, наконец, третья – духовные образовательные организации, наделенные правом присуждать богословские степени, которые на уровне федеральных государственных образовательных стандартов признаны аналогичными другим ученым степеням. Во всех трех подсистемах были рассмотрены варианты защиты диссертаций в постоянно действующих, разовых и объединенных диссертационных советах. Сравнительный анализ нормативных и правовых актов позволил выделить сходства и различия указанных подсистем, а также обозначить возможные варианты их развития.The paper is devoted to the consideration of the question of whether the Russian system of scientific attestation retains its integrity. The elimination of the monopoly of the Higher Attestation Commission (HAC) in matters of control over the activities of dissertation councils and procedures for defending dissertations made it possible to increase the variety of rules and practices of scientific attestation. Many scientific and educational organizations have developed their own regulations governing the corresponding activities. At the level of legislation, the instruction was fixed for the self-awarding of academic degrees to set requirements not lower than how they are formulated in federal acts. The question of how exactly this instruction is implemented is of research interest. In addition, it is important to understand whether applicants can receive equal rights and opportunities in different parts of the modern system. During the study, three existing subsystems were identified, together forming a single system. The first of them consists of ordinary and special dissertation councils, regulated directly by the Higher Attestation Commission and the Ministry of Science and Higher Education of Russia. The second subsystem is a collection of leading scientific and educational organizations that independently award academic degrees. Finally, the third subsystem consists of spiritual educational organizations, empowered to award theological degrees, which at the level of federal state educational standards are recognized as like other academic degrees. In all three subsystems, options for the defence of dissertations in permanent, one-time and joint dissertation councils were considered. Comparative analysis of regulatory and legal acts made it possible to highlight the similarities and differences of these subsystems, as well as to identify possible options for their development

Microbial carbonate build-ups at methane seeps near the upper boundary of the gas-hydrate stability zone in the Black Sea: results of EU project CRIMEA

Extensive dredging carried out in May-June 2004 in the deeper parts of the Dnepr paleo-delta area (NW Black Sea) yielded for the first time chimney-shaped carbonate microbial build-ups, which occur at methane seeps close to upper boundary of the gas-hydrate stability zone (~ 700 m). Carbonate samples taken with a benthic trawl represent fragments of the uppermost, middle and lowest parts of the build-up, which are similar to those found previously at the shallower and deeper methane seeps in the Black Sea. At the same time, the holed, plate-like carbonates in the lowest parts of the build-up provide first indications that gas channels are formed during the earliest growth phase of these microbial structures. Stable carbon isotope analyses of the carbonates from the uppermost fragments gave the d13C values ranging from -33.7 to -36.6 pro mil, while the d13C values of the lowermost fragments are significantly lighter, varying between -42.0 and -44.6 pro mil. Both these types of carbonates indicate that a major portion of the carbonate carbon originates from bacterial oxidation of the seeping methane. Oxygen isotopic values also show differences between the more irregular and porous samples from the uppermost part of the build-up, which are composed of a mixture of aragonite and Mg-calcite (d18O = 0.7 to 0.94 pro mil, and the only Mg-calcite cemented thin slabs of lowermost carbonates (d18O = 1.35 to 1.57 pro mil. The difference in d13C/d18O ratio found in the upper and lower parts of the build-up may reflect the changing of the water temperature and salinity during the chimney growth

Heat-kernel coefficients for oblique boundary conditions

We calculate the heat-kernel coefficients, up to $a_2$, for a U(1) bundle on the 4-Ball for boundary conditions which are such that the normal derivative of the field at the boundary is related to a first-order operator in boundary derivatives acting on the field. The results are used to place restrictions on the general forms of the coefficients. In the specific case considered, there can be a breakdown of ellipticity.Comment: 9 pages, JyTeX. One reference added and minor corrections mad

Magnetically stable zero-bias anomaly in Andreev contact to the magnetic Weyl semimetal Co3_3Sn2_2S2_2

Being encouraged by the interplay between topology, superconductivity and magnetism, we experimentally investigate charge transport through the interface between the Nb superconductor and the time-reversal symmetry breaking Weyl semimetal Co$_3$Sn$_2$S$_2$. In addition to the proximity induced superconducting gap, we observe several subgap features, among which the most interesting is the prominent subgap zero-bias anomaly, absolutely stable against external magnetic fields up to the critical field of Nb. As the promising scenario for the zero-bias anomaly to appear in transport characteristics, we consider the proximity induced zero-energy Andreev bound states interfaced with the half-metallic Co$_3$Sn$_2$S$_2$ and influenced by the strong spin-orbit coupling and large Zeeman splitting