Conductivity, weak ferromagnetism and charge instability in α−MnS\alpha-MnS single crystal

The temperature dependence of resistivity, magnetization and electron-spin resonance of the $\alpha- MnS$ single crystal were measured in temperature range of $5 K < T < 550 K$. Magnetization hysteresis in applied magnetic field up to 0.7 T at $T=5 K, 77 K, 300 K$, irreversible temperature behavior of magnetization and resistivity were found . The obtained data were explained in terms of degenerate tight binding model using random phase approximation. The contribution of holes in $t_{2g}$ and $e_g$ bands of manganese ions to the conductivity, optical absorbtion spectra and charge instability in $\alpha -MnS$ were studied. Charge susceptibility maxima resulted from the competition of the on-site Coulomb interaction between the holes in different orbitals and small hybridization of sub-bands were calculated at $T=160 K, 250 K, 475 K$.Comment: 6 pages, 12 figure

Pattern of changes in morpho-densitometric parameters of magnocellular neurons of the hypothalamic paraventricular nucleus under restraint stress of different duration

The aim of the work was to define the nature of changes in morpho-densitometric parameters of magnocellular neurons of the hypothalamic paraventricular nucleus in rats at 6, 15 and 21 weeks of restricted living space. Materials and methods. A total of 55 male Wistar rats aged 6-10 months were used and divided into 4 groups (1 – intact control, 10 rats; 2, 3 and 4 – experimental groups of 15 rats each, which were in conditions of restricted environmental space for 6, 15 and 21 weeks, respectively). Morpho-densitometric analysis of 5-μm-thick rat brain sections was performed after preliminary standard histological processing and 48 hours of halocyanine-chrome staining by Einarson using an AxioImager-M2 microscope (Carl Zeiss, Germany). Images of magnocellular neurons of the hypothalamic paraventricular nuclei (PVN), which were topographically identified according to the stereotaxic atlas of the rat brain, were captured using a highly sensitive AxioCam-ERc 5s video camera (Carl Zeiss, Germany) and recorded as a computer file using AxioVision 40 V 4.8.2.0 software (license number 3005339). Quantitative data on the area of neurons, their nuclei and nucleoli, the content of heterogeneous DNA and RNA in the cell cytoplasm, nuclei and nucleoli were obtained in a semi-automatic mode using the open source software ImageJ (National Institutes of Health, USA). Results. Chronic stress condition modelled in rats for 6, 15, and 21 weeks (limited living space, inactivity, and complicated communications) resulted in a decrease in the area of cytoplasm and nuclei of magnocellular neurons of the hypothalamic PVN. The decrease was directly proportional to restrain stress duration: cytoplasm and nuclei by 18 % and 9 % at week 6 and by 40 % and 25 % at week 21, respectively, and only cytoplasm by 23 % at 15 weeks. On the contrary, the area of neuronal nuclei was increased by 31 % at 6 weeks of stress and 33 % at 15 weeks, and by 15 % at 21 weeks of stress compared to the control. The content of nucleic acids in the cytoplasm of magnocellular neurons of the hypothalamic PVN in the group of rats with 6-week restriction was 39 % less than in the control group, 34 % less than that in the group with 15-week restriction, and 42 % less than that in the group of 21-week restrain stress. In the nuclei of cells after 6 and 15 weeks of restriction, the content was decreased approximately equally by 37 % and 35 %, respectively, and long-term restriction (21 weeks) contributed to a 41 % decrease. In the neuron nucleoli, the content of nucleic acids was changed similarly: in the group of 6 weeks, a decrease of 40 % was characteristic, after 15 weeks – by 39 %, and after 21 weeks – by 43 %. Conclusions. Changes in the morphometric parameters of magnocellular neurons of the hypothalamic PVN in rats with long-term limitation of living space are characterized by time dependence and multidirectionality, which is related to the functional features of the neuron structural components (cytoplasm, nucleus and nucleoli). There is a progressive decrease in the cytoplasmic area of PVN neurons and their nuclei, while the nucleolar area increases with increasing length of living space limitation. The content of nucleic acids in the studied structures of the hypothalamic PVN magnocellular neurons after prolonged stress at each time point (6, 15, 21 weeks) becomes less than the control values by more than a third. Comparison of nucleic acid content in the neuron cytoplasm, nuclei, and nucleoli shows a narrow range of variations in the parameters of the experimental group rats between different periods

Pathogenetic characteristics of the hormonal profile in rats subjected to restraint stress of different duration

The aim of the work is to ascertain the character of changes in the hormonal profile (concentrations of corticosterone, insulin, and adrenocorticotropic hormone) in conjunction with metabolic alterations and elevated blood pressure, which are induced in rats by restraint stress at 6th, 15th and 21st weeks of environmental space restriction. Materials and methods. A total of 55 normotensive male Wistar rats, aged 6–10 months, were assigned into 4 experimental groups (1 – intact control (10 rats); 2, 3 and 4 (15 rats each exposed to restricted space allowance)). All the animals were subjected to blood pressure (BP), blood glucose level and body weight measurements twice: at the stage of forming groups and at the 6th, 15th and 21st weeks. Plasma hormone concentrations (insulin, corticosterone, and ACTH) were examined by the immunoenzymatic method using commercial kits (Monobind, USA). Results. The body weight of the animals was significantly reduced by 20.72 % after 6 weeks of space allowance restriction, it was restored to baselines by the 15th week and exceeded control values by 26.1 % at the 21st week. BP levels showed an increasing trend, a dynamic increase in systolic pressure by 7 %, 17 % and 26 % was detected, respectively, as well as diastolic from the 15th week to the 21st week by 21.4 % and 37.0 %, respectively. Glucose concentration was within the euglycemic range. Changes in the hormonal profile showed an increase in the concentration of ACTH by more than 50 % and a decrease in insulin – by 34 % at the 6th week with a subsequent twofold decrease in the insulin concentration (at week 15) and a further more than twofold increase in ACTH at the 21st week. As for changes in the concentration of corticosterone, a peak increase of 3.77 times was noticed at the 15th week, followed by a decrease and restoration to the normative values by the 21st week. Conclusions. Even minor and unremarkable continuously acting stressors, which cannot be coped, become important triggers for hormonal profile and carbohydrate metabolism alterations as well as for a persistent increase in blood pressure, which manifest first by hypoinsulinemia, an increase in the level of ACTH, and a constant concentration of corticosterone. Long-term stress exposure contributes to a transient “peak” increase in the corticosterone level, a significant increase in insulin and a sustained increase in ACTH. Multidirectional changes in the levels of the studied hormones occur amidst a gradual increase in blood pressure and a stable increase in the level of glycemia

Long-term restraint stress as a predictor of insulin resistance development in experimental rats

The aim of the work was to define the pattern of changes and pathogenetic mechanisms of glycemic curve shape during a glucose tolerance test in rats at 6, 15, and 21 weeks of environmental space restriction. Materials and methods. A total of 55 male Wistar rats aged 6–10 months were used and divided into 4 groups (1 – intact control, 10 rats; 2, 3 and 4 of 15 rats each, which were in conditions of restricted environmental space for 6, 15 and 21 weeks, respectively). Fasting plasma levels of glucose (test strips Test Strip II on a Glucocard glucometer (ARKRAY Inc., Japan)), insulin and corticosterone (by an immunoenzymatic method using commercial kits for rats from Monobind, USA) were measured, glucose tolerance tests (GTT) were performed, the HOMA index and the insulin/corticosterone ratio were calculated. Results. The 6-week environmental space restriction, immobility and complex communication relations resulted in a hypoinsulinemic-hypoglycemic type of the glycemic curve with high tissue glucose sensitivity in animals which were in the conditions described (the HOMA index was significantly decreased to 0.21 versus 0.55 in the control), the characteristic delayed hyperglycemic peak at the 30th min of the test slowly returned to the euglycemic level by only the 90th min against the 30th min in the controls. The 15-week restriction caused a hypoinsulinemic curve with preserved tissue glucose sensitivity (the HOMA index 0.33 versus 0.55 in the controls). Alterations in postprandial glucose absorption were manifested by the highest glucose concentration at the 15th min of the test, a very slow decrease in the glucose level in the post-absorption period not being restored to baseline values by the 90th min. The 21-week restriction shaped a diabetic type of the glycemic curve, impaired tissue glucose sensitivity (a substantial and significant increase in the calculated HOMA index from 0.55 in the controls to 0.95) and resulted in the development of insulin resistance. Conclusions. The environmental space restriction, immobility and complex communication relations gradually induce a range of disorders in animals and change the glycemic response shape to glucose load, impair prandial insulin secretion, augment hyperglycemic effects of counterinsular hormones (corticosterone), and realize dysfunctional manifestations of prandial/postprandial glycemia. 6 weeks of restrictions and challenges shape the hypoinsulinemic-hypoglycemic type of the glycemic curve with high tissue glucose sensitivity, while 15 weeks result in the hypoinsulinemic curve with preserved tissue glucose sensitivity. 21 weeks show the diabetic type of the glycemic curve with impaired tissue glucose sensitivity and the development of insulin resistance

Spherical Bondi accretion onto a magnetic dipole

Quasi-spherical supersonic (Bondi-type) accretion to a star with a dipole magnetic field is investigated using resistive magnetohydrodynamic simulations. A systematic study is made of accretion to a non-rotating star, while sample results for a rotating star are also presented. A new stationary subsonic accretion flow is found with a steady rate of accretion to the magnetized star smaller than the Bondi accretion rate. Dependences of the accretion rate and the flow pattern on the magnetic momentum of the star and the magnetic diffusivity are presented. For slow star's rotation the accretion flow is similar to that in non-rotating case, but in the case of fast rotation the structure of the subsonic accretion flow is fundamentally different and includes a region of ``propeller'' outflow. The methods and results described here are of general interest and can be applied to systems where matter accretes with low angular momentum.Comment: 15 pages, 15 figures, used emulapj.st

Accretion, Outflows, and Winds of Magnetized Stars

Many types of stars have strong magnetic fields that can dynamically influence the flow of circumstellar matter. In stars with accretion disks, the stellar magnetic field can truncate the inner disk and determine the paths that matter can take to flow onto the star. These paths are different in stars with different magnetospheres and periods of rotation. External field lines of the magnetosphere may inflate and produce favorable conditions for outflows from the disk-magnetosphere boundary. Outflows can be particularly strong in the propeller regime, wherein a star rotates more rapidly than the inner disk. Outflows may also form at the disk-magnetosphere boundary of slowly rotating stars, if the magnetosphere is compressed by the accreting matter. In isolated, strongly magnetized stars, the magnetic field can influence formation and/or propagation of stellar wind outflows. Winds from low-mass, solar-type stars may be either thermally or magnetically driven, while winds from massive, luminous O and B type stars are radiatively driven. In all of these cases, the magnetic field influences matter flow from the stars and determines many observational properties. In this chapter we review recent studies of accretion, outflows, and winds of magnetized stars with a focus on three main topics: (1) accretion onto magnetized stars; (2) outflows from the disk-magnetosphere boundary; and (3) winds from isolated massive magnetized stars. We show results obtained from global magnetohydrodynamic simulations and, in a number of cases compare global simulations with observations.Comment: 60 pages, 44 figure

Клиническая симптоматика поражения суставов при синдроме Лефгрена

Objective: to investigate joint damage and laboratory and instrumental features in Löfgren's syndrome (LS) in patients referred to the Rheumatology Center.Patients and methods. The five-year investigation enrolled 142 patients of both sexes (31 men and 111 women; mean age, 39.3±11.1 years) with erythema nodosum (EN) accompanied by polyarthralgias or arthritis. All the patients underwent comprehensive clinical, laboratory and instrumental examinations, including joint ultrasound and chest computed tomography.Results and discussion. Disseminated EN that was correlated with the level of CRP was detected in 96% of cases (p=0.006; r=0.38). The signs of joint damage with predominantly periarticular changes in the ankle joints were observed in 124 (87%) patients. There was a relationship of the duration of the articular syndrome to that of inflammatory changes in subcutaneous tissue and to the number of nodules (p=0.02; r=0.45). The level of CRP had a significant direct correlation with the number of nodules (p=0.008; r=0.29) and the severity of the articular syndrome (p=0.003; r=0.29). Elevated levels of angiotensin-converting enzyme were found in 97 (78%) patients. Joint damage was significantly more frequently combined with X-ray Stage I sarcoidosis (Sr) (p=0.03). The Stage II Sr showed a male preponderance (p=0.04) and a 4.8-fold increase in the merging of subcutaneous nodes into conglomerates (p=0.002).Conclusion. Joint damage may be one of the first signs of LS, which requires that physicians of various specialties should coordinate their actions to timely diagnose, assess activity, and choose an adequate therapeutic approach.Цель исследования – изучение поражения суставов и лабораторно-инструментальных особенностей при синдроме Лефгрена (СЛ) у больных, направленных в ревматологический центр.Пациенты и методы. В исследование продолжительностью 5 лет включено 142 пациента обоего пола (31 мужчина и 111 женщин, средний возраст 39,3±11,1 года) с узловатой эритемой (УЭ), сопровождавшейся полиартралгиями или артритом. Всем пациентам проводили комплексное клиническое, лабораторное и инструментальное обследование, включая УЗИ суставов и компьютерную томографию органов грудной клетки.Результаты и обсуждение. В 96% случаев выявлена распространенная УЭ, которая коррелировала с уровнем СРБ (р=0,006; r=0,38). У 124 (87%) пациентов наблюдались признаки поражения суставов с преимущественно периартикулярными изменениями в области голеностопных суставов. Отмечена взаимосвязь длительности суставного синдрома с длительностью воспалительных изменений подкожной клетчатки и количеством узлов (р=0,02; r=0,45). Уровень СРБ имел значимую прямую корреляцию с количеством узлов (р=0,008; r=0,29) и выраженностью суставного синдрома (р=0,003; r=0,29). Повышенный уровень ангиотензинпревращающего фермента выявлен у 97 (78%) пациентов. Поражение суставов значимо чаще сочеталось с I рентгенологической стадией саркоидоза (Ср; р=0,03). В группе со II стадией Ср преобладали мужчины (р=0,04) и в 4,8 раза чаще встречалось слияние подкожных узлов в конгломераты (p=0,002).Заключение. Поражение суставов может быть одним из первых признаков СЛ, что требует координации действий врачей различных специальностей с целью своевременной диагностики, оценки активности и выбора адекватного терапевтического подхода