Induced magnetic field in accretion disks around neutron stars

There are X-ray pulsating sources that are explained by accretion from disks around neutron stars. Such disks deserve a detailed analysis. In particular, the dipole magnetic field of the central star may penetrate the disk, giving rise to an induced magnetic field inside the disk due to the frozen-in condition. The growth of the induced field can be limited by the turbulent diffusion. In the present work, I calculate the induced field in this case. The problem is reduced to the induction equation to which I have found an analytical solution describing radial and vertical structures of the induced field. The radial structure is close to the earlier predicted dependence on the difference in angular velocities between the magnetosphere and disk, $b \propto \Omega_{\rm s} - \Omega_{\rm k}$, while the vertical structure of an induced field is close to the linear dependence on the altitude above the equator, $b \propto z$. The possibility of the existence of non-stationary quasi-periodic components of the induced field is discussed.Comment: 8 pages, 3 figures, accepted to Astronomy Letters, proceedings of Physics of Neutron Stars conference (10-14 July 2023, Saint Petersburg, Russia), translation by the autho

Effective lining of tunnel kiln cars made of aluminosilicate ceramoconcrete

Aluminosilicate ceramoconcrete lining for cars used in ceramic plant firing kilns was developed and introduced. The first cars with this lining have already operated for more than 50 cyclesyesBelgorod State Universit

X-ray studies of enzymes that interact with penicillins.

The technique of X-ray diffraction has been successfully applied to enzymes associated with peptidoglycan biosynthesis. The technique has taught us a great deal about the structures and catalytic mechanisms of penicillin-binding proteins and beta-lactamases. An insight into the structural basis for antibiotic resistance is given

Off-limb EUV observations of the solar corona and transients with the CORONAS-F/SPIRIT telescope-coronagraph

The SPIRIT telescope aboard the CORONAS-F satellite (in orbit from 26 July 2001 to 5 December 2005), observed the off-limb solar corona in the 175 Å (Fe IX, X and XI lines) and 304 Å (He II and Si XI lines) bands. In the coronagraphic mode the mirror was tilted to image the corona at the distance of 1.1...5 <I>R</I><sub>sun</sub> from the solar center, the outer occulter blocked the disk radiation and the detector sensitivity was enhanced. This intermediate region between the fields of view of ordinary extreme-ultraviolet (EUV) telescopes and most of the white-light (WL) coronagraphs is responsible for forming the streamer belt, acceleration of ejected matter and emergence of slow and fast solar wind. We present here the results of continuous coronagraphic EUV observations of the solar corona carried out during two weeks in June and December 2002. The images showed a "diffuse" (unresolved) component of the corona seen in both bands, and non-radial, ray-like structures seen only in the 175 Å band, which can be associated with a streamer base. The correlations between latitudinal distributions of the EUV brightness in the corona and at the limb were found to be high in 304 Å at all distances and in 175 Å only below 1.5 <I>R</I><sub>sun</sub>. The temporal correlation of the coronal brightness along the west radial line, with the brightness at the underlying limb region was significant in both bands, independent of the distance. On 2 February 2003 SPIRIT observed an expansion of a transient associated with a prominence eruption seen only in the 304 Å band. The SPIRIT data have been compared with the corresponding data of the SOHO LASCO, EIT and UVCS instruments

Nonlinear evolution of short-wavelength torsional Alfvén waves

We analyze nonlinear evolution of torsional Alfvén waves in a straight magnetic flux tube filled in with a low-β plasma, and surrounded with a plasma of lower density. Such magnetic tubes model, in particular, a segment of a coronal loop or a polar plume. The wavelength is taken comparable to the tube radius. We perform a numerical simulation of the wave propagation using ideal magnetohydrodynamics. We find that a torsional wave nonlinearly induces three kinds of compressive flows: the parallel flow at the Alfvén speed, which constitutes a bulk plasma motion along the magnetic field, the tube wave, and also transverse flows in the radial direction, associated with sausage fast magnetoacoustic modes. In addition, the nonlinear torsional wave steepens and its propagation speed increases. The latter effect leads to the progressive distortion of the torsional wave front, i.e., nonlinear phase mixing. Because of the intrinsic non-uniformity of the torsional wave amplitude across the tube radius, the nonlinear effects are more pronounced in regions with higher wave amplitudes. They are always absent at the axes of the flux tube. In the case of a linear radial profile of the wave amplitude, the nonlinear effects are localized in an annulus region near the tube boundary. Thus, the parallel compressive flows driven by torsional Alfvén waves in the solar and stellar coronae, are essentially non-uniform in the perpendicular direction. The presence of additional sinks for the wave energy reduces the efficiency of the nonlinear parallel cascade in torsional Alfvén waves

Поражение суставов и позвоночника у б ольных с воспалительными заболеваниями кишечника

The paper reviews literature on locomotor apparatus injury in inflammatory bowel disease (IBD). It describes the types of joint and spinal column involvement in ulcerative colitis (UC) and Crohn’s disease (CD). The ratio of onset to the activity of IBD and articular syndrome is estimated. The most common type of articular syndrome is peripheral arthritis that involves mainly the knee and ankle joints and that is associated with IBD activity in most cases. Unlike peripheral arthritis, the course of axial spondyloarthritis manifesting as isolated sacroiliitis and ankylosing spondylitis (AS) is unrelated to IBD activity. There is evidence on isolated sacroiliitis that is rather common asymptomatic, that is diagnosed late, and that is a finding in a number of patients during examination. The paper provides the clinical and instrumental characteristics of AS in IBDand points to the similarity of their clinical manifestations and radiographic changes with those in idiopathic AS. It also describes the picture of enthesitis with emphasis on the systemic extra-articular manifestations of IBD, which are associated with articular syndrome (erythema nodosum and uveitis) in a number of cases. Radiographic changes in peripheral joints and spinal column are characterized in different types of locomotor apparatus injury in patients with IBD. There are data available in the literature on the treatment of articular syndrome in patients with UC and CD. It is noted that there is a need for a differentiated approach to treating peripheral arthritis and axial skeleton involvement; the role of nonsteroidal anti-inflammatory drugs, sulfasalazine, and biological agents in the treatment of articular syndrome in IBD is assessed. It is indicated that IBD patients having rheumatic manifestations should be followed up jointly by a gastroenterologist and a rheumatologist.Представлен обзор литературы, посвященной поражению опорно-двигательного аппарата при воспалительных заболеваниях кишечника (ВЗК). Описаны варианты поражения суставов и позвоночника при язвенном колите (ЯК) и болезни Крона (БК). Дана оценка соотношения дебюта и активности ВЗК и суставного синдрома. Наиболее частым вариантом суставного синдрома оказался периферический артрит, протекавший с вовлечением преимущественно коленных и голеностопных суставов, в большинстве случаев связанный с активностью ВЗК. В отличие от периферического артрита течение аксиального спондилоартрита, представленного изолированным сакроилиитом и анкилозирующим спондилитом (АС), не зависело от активности ВЗК. Приведены данные об изолированном сакроилиите, который нередко протекает бессимптомно, поздно диагностируется и у ряда больных является находкой при обследовании. Дана клинико-инструментальная характеристика АС при ВЗК, отмечена схожесть клинических проявлений и рентгенологических изменений с таковыми при идиопатическом АС. Описана картина энтезита, уделено внимание системным внесуставным проявлениям ВЗК, в ряде случаев ассоциированным с суставным синдромом (узловатая эритема и увеит). Охарактеризованы рентгенологические изменения периферических суставов и позвоночника при различных вариантах поражения опорно-двигательного аппарата у больных с ВЗК. Приведены данные литературы, касающиеся лечения суставного синдрома у больных ЯК и БК. Отмечена необходимость дифференцированного подхода к лечению периферического артрита и поражения аксиального скелета, оценена роль нестероидных противовоспалительных препаратов, сульфасалазина, генно-инженерных биологических препаратов в лечении суставного синдрома при ВЗК. Указано, что пациентов с ВЗК, имеющих ревматологические проявления, должны наблюдать совместно гастроэнтеролог и ревматолог

Xenobiotic-induced activation of human aryl hydrocarbon receptor target genes in Drosophila is mediated by the epigenetic chromatin modifiers

Aryl hydrocarbon receptor (AHR) is the key transcription factor that controls animal development and various adaptive processes. The AHR\u27s target genes are involved in biodegradation of endogenous and exogenous toxins, regulation of immune response, organogenesis, and neurogenesis. Ligand binding is important for the activation of the AHR signaling pathway. Invertebrate AHR homologs are activated by endogenous ligands whereas vertebrate AHR can be activated by both endogenous and exogenous ligands (xenobiotics). Several studies using mammalian cultured cells have demonstrated that transcription of the AHR target genes can be activated by exogenous AHR ligands, but little is known about the effects of AHR in a living organism. Here, we examined the effects of human AHR and its ligands using transgenic Drosophila lines with an inducible human AhR gene. We found that exogenous AHR ligands can increase as well as decrease the transcription levels of the AHR target genes, including genes that control proliferation, motility, polarization, and programmed cell death. This suggests that AHR activation may affect the expression of gene networks that could be critical for cancer progression and metastasis. Importantly, we found that AHR target genes are also controlled by the enzymes that modify chromatin structure, in particular components of the epigenetic Polycomb Repressive complexes 1 and 2. Since exogenous AHR ligands (alternatively - xenobiotics) and small molecule inhibitors of epigenetic modifiers are often used as pharmaceutical anticancer drugs, our findings may have significant implications in designing new combinations of therapeutic treatments for oncological diseases. © Akishina et al