Turbulent convection in protoplanetary discs and its role in angular momentum transfer

We present a model for the transport of anisotropic turbulence in an accretion disc. The model uses the Reynolds stress tensor approach in the mean field approximation. To study the role of convection in a protoplanetary disc, we combine the turbulence model with a radiative transfer calculation, and also include convection using the mixing length approximation. We find that the turbulence generated by convection causes the angular momentum of the accretion disc to be directed outwards. We also confirm the conclusions of other authors that turbulent convection is unable to provide the observed disc accretion rates as well as a heat source sufficient for the convection to be self-sustaining. The reasons for the latter are the strong anisotropy of the turbulence together with the low efficiency of the energy transfer from the background velocity shear to the turbulent stress tensor.Comment: MNRAS accepted | 15 pages, 8 figure

Constrained minimization in the C# # environment

Abstract On the basis of the ideas, proposed by one of the authors (I.N. Silin), a suitable software has been developed for constrained data "tting. Constraints may be of arbitrary type; i.e. equalities and inequalities. The simplest possible way has been used. The widely known program FUMILI was re-written in the C# # language. Constraints in the form of inequalities ( )5a were taken into account by changing them into equalities ( )"t and simple inequalities of type t5a. The equalities were taken into account by means of quadratic penalty functions. The suitable software was tested on the model data for the ANKE setup (COSY accelerator, Forschungszentrum JuK lich, Germany)

Pathogenetic factors of disorders in spermatogenesis and antioxidative activity of an ejaculate in young men with post pubertal visceral obesity and normal andrological anamnesis

BACKGROUND: Considering the negative influence of a visceral obesity on spermatogenesis, it is important to investigate its pathogenetic factors. AIMS: To reveal the pathogenetic factors of disorders in spermatogenesis and antioxidative activity of an ejaculate in young men with post pubertal visceral obesity and normal andrological anamnesis. MATERIALS AND METHODS: 47 men under 30 years with post pubertal and nutritional visceral obesity have been included into one-stage research. The length of circle of waist, lipid blood spectrum, blood levels of glucose and insulin, antioxidant activity and electronic-microscopic analysis of an ejaculate have been examined. Differences were considered statistically significant with p <0,05. RESULTS: The LDL and triglyceride levels in patients with disorders in spermatogenesis were significantly higher than considered in men with normozoospermia. Correlations between antioxidative activity of ejaculate and levels of LDL (n=47, r=-0,310; p=0,033), triglyceride (n=47, r=-0,366; p=0,011) and the number of normal spermatozoons in ejaculate (n=47, r=0,343;p=0,017) have been revealed. CONCLUSIONS: The dyslipidemia in young men with post pubertal visceral obesity and normal andrological anamnesis can be considered as pathogenetic factors of disorders in spermatogenesis. Nevertheless the dyslipidemia can influence spermatogenesis through oxidative stress

Stimulation of spermatogenesis by combined therapy with follicle-stimulating hormone and chorionic gonadotropin for azoospermia and infertility in cases of previous ineffective monotherapy with chorionic gonadotropin and antiestrogen

Often there is a need of application of the methods of treatment, directed on increase in quantity of spermatozoa in an ejaculate. In the research efficiency of the combined therapy by preparation follicle-stimulating hormone was estimated and a chorionic gonadotrophin in cases of the previous inefficiency monotherapy a chorionic gonadotrophin and an anti-estrogen. The efficiency of treatment concerning an oligoteratozoospermiya made 65 %. Positive changes of morphology of spermatozoa included improvement of condensation of a chromatin and decrease of the degrading forms. At the same time this treatment was safe and didn»t lead to development of side effects

The infarct-limiting efficacy of deltorphin-II in old rats with diet-induced metabolic syndrome

Background. The discovery of new pharmacological agents for myocardial protection during reperfusion injury is an urgent goal of modern physiology and pharmacology.The aim of the study. To identify the potential for protecting the myocardium from reperfusion injury by administering the delta-2 opioid receptor agonist deltorphin-II prior to reperfusion in old rats with diet-induced metabolic syndrome.Materials and methods. The study was performed on Wistar rats aged 60 days (young rats) and 450 days (old rats) before the onset of a study. Metabolic syndrome (MetS) was modeled for 84 days with a high-carbohydrate high-fat diet (16 % protein, 21 % fat, 46 % carbohydrate) with the replacement of drinking water with 20 % fructose solution. Myocardial infarction was performed by 45-min coronary occlusion followed by 120-min reperfusion; the size of the area of the necrotic myocardium was determined relative to the size of the hypoperfusion zone. The delta-2 opioid receptor agonist deltorphin-II was administered once intravenously 5 minutes before the end of ischemia.Results. It was found that coronary occlusion and subsequent reperfusion both in groups of young and old rats led to the formation of myocardial infarction (necrosis), the size of which was 45 % of the size of the risk zone. Administration of deltorphin-II in old rats led to a limitation of infarct size to 30 % of the size of the risk zone, i. e. 1.7-fold. The use of deltorphin-II in old rats with MetS contributed to a decrease in infarct size to 27 % of the size of the risk zone (1.5 times). The obtained results demonstrate the cardioprotective efficacy of the delta-2 opioid receptor agonist deltorphin-II in aging and metabolic syndrome in rats.Conclusions. These data may serve as a basis for conducting preclinical studies of deltorphin-II as a drug for treatment of acute myocardial infarction

A 12,000 Year Record of Explosive Volcanism in the Siple Dome Ice Core, West Antarctica

Air mass trajectories in the Southern Hemisphere provide a mechanism for transport to and deposition of volcanic products on the Antarctic ice sheet from local volcanoes and from tropical and subtropical volcanic centers. This study extends the detailed record of Antarctic, South American, and equatorial volcanism over the last 12,000 years using continuous glaciochemical series developed from the Siple Dome A (SDMA) ice core, West Antarctica. The largest volcanic sulfate spike ( 280 mu g/L) occurs at 5881 B. C. E. Other large signals with unknown sources are observed around 325 B. C. E. ( 270 mu g/L) and 2818 B. C. E. ( 191 mu g/L). Ages of several large equatorial or Southern Hemisphere volcanic eruptions are synchronous with many sulfate peaks detected in the SDMA volcanic ice chemistry record. The microprobe fingerprinting\u27\u27 of glass shards in the SDMA core points to the following Antarctic volcanic centers as sources of tephra found in the SDMA core: Balenny Island, Pleiades, Mount Berlin, Mount Takahe, and Mount Melbourne as well as Mount Hudson and possibly Mount Burney volcanoes of South America. Identified volcanic sources provide an insight into the poorly resolved transport history of volcanic products from source volcanoes to the West Antarctic ice sheet

Research in the area of preparing activated alumina. Part 4. new technological approaches for synthesis of ultrafine α-Al₂O₃

Results of new integrated technological approaches to synthesis of ultrafine -alumina using commercially available metallurgical alumina as a raw material are presente

Volcanic glass from the 1.8 ka Taupō eruption (New Zealand) detected in Antarctic ice at ~ 230 CE.

Chemical anomalies in polar ice core records are frequently linked to volcanism; however, without the presence of (crypto)tephra particles, links to specific eruptions remain speculative. Correlating tephras yields estimates of eruption timing and potential source volcano, offers refinement of ice core chronologies, and provides insights into volcanic impacts. Here, we report on sparse rhyolitic glass shards detected in the Roosevelt Island Climate Evolution (RICE) ice core (West Antarctica), attributed to the 1.8 ka Taupō eruption (New Zealand)-one of the largest and most energetic Holocene eruptions globally. Six shards of a distinctive geochemical composition, identical within analytical uncertainties to proximal Taupō glass, are accompanied by a single shard indistinguishable from glass of the ~25.5 ka Ōruanui supereruption, also from Taupō volcano. This double fingerprint uniquely identifies the source volcano and helps link the shards to the climactic phase of the Taupō eruption. The englacial Taupō-derived glass shards coincide with a particle spike and conductivity anomaly at 278.84 m core depth, along with trachytic glass from a local Antarctic eruption of Mt. Melbourne. The assessed age of the sampled ice is 230 ± 19 CE (95% confidence), confirming that the published radiocarbon wiggle-match date of 232 ± 10 CE (2 SD) for the Taupō eruption is robust