Photometry of two DQ white dwarfs - search for spots

Aims. The intensity profiles of the C_2 Swan bands in cool DQ white dwarfs cannot be adequately fitted with models that otherwise succesfully reproduce spectral features of the molecule CH in these stars. Initial modelling showed that a two-component atmosphere in the style of a spot might be able to solve the problem. Methods. We photometrically observed the two cool DQ white dwarfs GJ1117 and EGGR78 to search for variability caused by stellar spots. Results. We have not found any such variability, but we estimate the effects of hypothetical spots on lightcurves. We also estimate detection probabilities for spots in different configurations. Alternative explanations of the problem are needed and briefly discussed.Comment: 5 pages, 6 figures, published in A&

Spectropolarimetric observations of cool DQ white dwarfs

Following our recent discovery of a new magnetic DQ white dwarf (WD) with CH molecular features, we report the results for the rest of the DQ WDs from our survey. We use high signal-to-noise spectropolarimetric data to search for magnetic fields in a sample of 11 objects. One object in our sample, WD1235+422, shows the signs of continuum circular polarization that is similar to some peculiar DQs with unidentified molecular absorption bands, but the low S/N and spectral resolution of these data make more observations necessary to reveal the true nature of this object.Comment: 4 pages, 4 figures. Accepted for publication in Astronomy & Astrophysic

Сообщение о ретракции: «Иммунологические критерии прогнозирования замедленной консолидации костной ткани», журнал «Травматология и ортопедия России». 2009, № 2, С. 59–66

The article Immunologic criteria of prediction of bone delayed union published in Traumatology and Orthopedics of Russia (2009, N 2) by O.V. Berdyugina, K.A. Berdyugin is a duplicate of the article Immunological monitoring of slow down ostheogenesis published in Medical Immunology. 2009;(3-4):371-378. That was the reason for retraction. Revealed April 20, 2022 by the Editorial Board.Статья Иммунологические критерии прогнозирования замедленной консолидации костной ткани, опубликованная в журнале Травматология и ортопедия России (2009, № 2), авторами которой являются О.В. Бердюгина, К.А. Бердюгин, представляет собой дубликат статьи О.В. Бердюгиной Иммунологический мониторинг замедленного остеогенеза, опубликованной в журнале Медицинская иммунология. 2008, Т. 10, № 4-5, С. 371-378. В связи с этим указанная статья отозвана с публикации. Выявлено 20/04/22 редколлегией журнала

Fluidity Onset in Graphene

Viscous electron fluids have emerged recently as a new paradigm of strongly-correlated electron transport in solids. Here we report on a direct observation of the transition to this long-sought-for state of matter in a high-mobility electron system in graphene. Unexpectedly, the electron flow is found to be interaction-dominated but non-hydrodynamic (quasiballistic) in a wide temperature range, showing signatures of viscous flows only at relatively high temperatures. The transition between the two regimes is characterized by a sharp maximum of negative resistance, probed in proximity to the current injector. The resistance decreases as the system goes deeper into the hydrodynamic regime. In a perfect darkness-before-daybreak manner, the interaction-dominated negative response is strongest at the transition to the quasiballistic regime. Our work provides the first demonstration of how the viscous fluid behavior emerges in an interacting electron system.Comment: 8pgs, 4fg

Evidence for Extremely High Dust Polarization Efficiency in NGC 3184

Recent studies have found the Type II-plateau supernova (SN) 1999gi to be highly polarized (p_max = 5.8%, where p_max is the highest degree of polarization measured in the optical bandpass; Leonard & Filippenko 2001) and minimally reddened (E[B-V] = 0.21 +/- 0.09 mag; Leonard et al. 2002). From multiple lines of evidence, including the convincing fit of a ``Serkowski'' interstellar polarization (ISP) curve to the continuum polarization shape, we conclude that the bulk of the observed polarization is likely due to dust along the line of sight (l-o-s), and is not intrinsic to SN 1999gi. We present new spectropolarimetric observations of four distant Galactic stars close to the l-o-s to SN 1999gi (two are within 0.02 degrees), and find that all are null to within 0.2%, effectively eliminating Galactic dust as the cause of the high polarization. The high ISP coupled with the low reddening implies an extraordinarily high polarization efficiency for the dust along this l-o-s in NGC 3184: ISP / E(B-V) = 31^{+22}_{-9} % mag^{-1}. This is inconsistent with the empirical Galactic limit (ISP / E[B-V] < 9% mag^{-1}), and represents the highest polarization efficiency yet confirmed for a single sight line in either the Milky Way or an external galaxy.Comment: 27 pages, accepted for publication by the Astronomical Journa

High-precision broadband linear polarimetry of early-type binaries IV. Binary system of DH Cephei in the open cluster of NGC 7380

DH~Cephei is a well known massive O+O-type binary system on the northern sky, residing in the young open cluster NGC~7380. Our high-precision multi-band polarimetry has clearly revealed that variations of linear polarizations in this system are synchronous with the phase of the orbital period. We have used the observed variations of Stokes parameters $q$ and $u$ to derive the orbital inclination $i$, orientation $\Omega$, and the direction of rotation. In order to determine the contribution from interstellar polarization, we have carried out new observations of polarization of field stars with precisely measured parallaxes. The variations of Stokes parameters in all three $B$, $V$, and $R$ passbands clearly exhibit an unambiguous periodic signal at 1.055 d with the amplitude of variations $\sim$$0.2\%$ which corresponds to half of known orbital period of 2.11 d. This type of polarization variability is expected for a binary system with light scattering material distributed symmetrically with respect to the orbital plane. Even though most of the observed polarization ($\sim$2$\%$) is of interstellar origin, about one third of it is due to the intrinsic component. In addition to the regular polarization variability, there is a non-periodic component, strongest in the $B$ passband. We obtained in the $V$ passband our most reliable values for the orbital inclination $i = 46^{\circ}+11^{\circ}/-46^{\circ}$ and the orientation of the orbit on the sky $\Omega = 105^{\circ} \pm 55^{\circ}$, with 1$\sigma$ confidence intervals. The direction of the binary system rotation on the plane of the sky is clockwise