Black Hole Formation in X-Ray Binaries: The Case of XTE J1118+480

In recent years, an increasing number of proper motions have been measured for Galactic X-ray binaries. When supplemented with accurate determinations of the component masses, orbital period, and donor luminosity and effective temperature, these kinematical constraints harbor a wealth of information on the systems' past evolution. The constraints on compact object progenitors and kicks derived from this are of immense value for understanding compact object formation and exposing common threads and fundamental differences between black hole and neutron star formation. Here, we present the results of such an analysis for the black hole X-ray binary XTE J1118+480. We present results from modeling the mass transfer phase, following the motion in the Galaxy back to the birth site of the black hole, and examining the dynamics of symmetric and asymmetric core-collapses of the black hole progenitor

Influence of raw material properties on the quality of solid biofuel and energy consumption in briquetting process

ArticleThe present paper is related to a pressing process research of raw materials with different density in order to investigate impact of biomass density on a formation of monolithic structure and the briquette’s strength. Another focus of the study is an influence of raw materials particles’ size on agglomeration process and quality of final product. Different biomass materials like two varieties of miscanthus, industrial hemp and apple wood were selected for experimental purposes of this research. Mechanical durability which represents one the main indicator of briquettes’ mechanical quality (strength) was determined. The research was conducted using hydraulic piston briquetting press. For assessment of briquetting efficiency during the whole process energy consumption was measured. One of the most important factors that can affect briquetting process is the temperature of pressing chamber which was registered as well. The main goal of the research was practical study of possibilities for increasing production efficiency and quality of briquettes on hydraulic piston briquetting press with respect to optimization of particles’ size of raw materials and use of raw materials the most appropriate density

Total Antioxidant Capacity and Polyphenol Content Correlation in Aqueous-Alcoholic Plant Extracts Used in Phytotherapy

The present investigation analyzes the antioxidant properties of aqueous-alcoholic extracts of Bulgarian plants used in phytotherapy in relation with their polyphenol content.  The total phenolic (TP) content and total antioxidant capacity (TAC) values of aqueous-alcoholic extract from Hypericum perforatum, Cydonia vulgaris, Arcostaphylos uva-ursi and Cotinus coggygria significantly exceeded the TP and TAC values of Ilex paraguariensis (mate), Aspalathus linearis (rooibos), Cyclopia intermedia (honeybush), and Camellia sinensis (black tea), famous for their antioxidants' content. The high degree of positive correlation (r=0,91) between TAC and TP values indicates the role of polyphenols for the plant antioxidant potential. Bulgarian medicinal plants are excellent sources of antioxidants established by their high TAC values as compared to the famous foreign plants honeybush, rooibos, mate and black tea and they prove to be a potential for the development of new pharmaceutical

EVIDENCE FOR FREE-RADICAL MEDIATED LIPID PEROXIDATION IN RATS AFTER COLD-IMMERSION STRESS

The role of cold immersion stress for the free-radical mediated lipid peroxidation in rat plasma and erythrocytes was studied. A model of cold-induced stress in rats was created. A significant increase of the level of thiobarbituric acid-reactive substances (TBARS) in plasma was found after chilling. Activated catabolic processes and xanthine-oxidase reactions during hypoxia could cause the increase measured in plasma levels of uric acid one hour after cold stress. A decrease in the antioxidant defence measured by uric acid consumption in rat blood plasma took also place already at the 3rd hour after chilling. These effects were not accompanied neither by elevated levels of TBARS, nor by a decrease in the reduced glutathione or elevated ratio of oxidized/ total glutathione in erythrocytes. The results indicated that lipid peroxidation was a component of the cold-induced stress in rats

Self-dual Yang-Mills fields in pseudoeuclidean spaces

The self-duality Yang-Mills equations in pseudoeuclidean spaces of dimensions $d\leq 8$ are investigated. New classes of solutions of the equations are found. Extended solutions to the D=10, N=1 supergravity and super Yang-Mills equations are constructed from these solutions.Comment: 9 pages, LaTeX, no figure

Understanding How Components of Organisations Contribute to Attacks

Attacks on organisations today explore many different layers, including buildings infrastructure, IT infrastructure, and human factor – the physical, virtual, and social layer. Identifying possible attacks, understanding their impact, and attributing their origin and contributing factors is difficult. Recently, system models have been used for automatically identifying possible attacks on the modelled organisation. The generated attacks consider all three layers, making the contribution of building infrastructure, computer infrastructure, and humans (insiders and outsiders) explicit. However, this contribution is only visible in the attack trees as part of the performed steps; it cannot be mapped back to the model directly since the actions usually involve several elements (attacker and targeted actor or asset). Especially for large attack trees, understanding the relations between several model components quickly results in a large quantity of interrelations, which are hard to grasp. In this work we present several approaches for visualising attributes of attacks such as likelihood of success, impact, and required time or skill level. The resulting visualisations provide a link between attacks on an organisations and the contribution of parts of an organisation to the attack and its impact

TEACHING IN A CONNECTED WORLD: NEW APPROACHES IN TEACHING BIOCHEMISTRY ADOPTED AT THE MEDICAL UNIVERSITY OF VARNA, BULGARIA

This paper aims at improving the content of the biochemistry curriculum and the methods by which it was delivered at the Medical University of Varna in terms of course content, examination standards and obtaining a feedback from the students. The paper presents two-year follow-up outcomes. A working collaboration was established with two Western European Universities, the University of Marburg, Germany and the University of Dundee, UK. The innovative teaching methodology developed and used in the Department of Biochemistry at the University of Dundee was adopted considering the particular circumstances in the Medical University of Varna. The content of the basic biochemistry course was revised and expanded emphasizing the molecular basis of metabolic variation between different organs and molecular events and clinical medicine. New clinically case-oriented studies of biochemically-based disorders were introduced for the first time in the basic biochemistry course in the form of tutorials and discussion sessions with the students. The laboratory classes in biochemistry were deleted and replaced by demonstrations and clinical laboratory tests, together with tutorial and group activity sessions. New interactive small group methods were adopted in our teaching with the aim to ensure better understanding and accessibility of the teaching material. One free elective discipline entitled "Molecular biology in medicine" has been introduced. A system for obtaining students' opinions about the courses and new teaching methods using feedback questionnaires was adopted

Effect of different compositions on anaerobic co-digestion of cattle manure and agro-industrial by-products

ArticleThe present research is dedicated to the study of anaerobic co-digestion process of different biomass materials. Anaerobic co-digestion of digested sludge, grass silage, haylage and cattle manure was evaluated in mesophilic tank reactors in the lab-scale experiment. Twelve laboratory scale tank reactors (1.5 L) were used during the incubation period of 45 days. First triplet of reactors was fed with pure digested sludge and the other three with different mixtures having the volumetric ratios of 30/35/25/10, 40/30/20/10 and 50/25/15/10 for digested sludge/corn silage/grass haylage/cattle manure. Methane production was analyzed for all labscale reactors individually. The resulting specific methane production of above-mentioned batches was 336.34, 238.1 and 233.23 LSTP[CH4] kg-1 [TVS], respectively. Other results such as cumulative biogas and methane yield, volumetric biogas and methane yield, volumetric biogas and methane yield per day were also assessed. These results had the highest meaning when complex substrate had no more than 30% of inoculum

Self-Duality in D <= 8-dimensional Euclidean Gravity

In the context of D-dimensional Euclidean gravity, we define the natural generalisation to D-dimensions of the self-dual Yang-Mills equations, as duality conditions on the curvature 2-form of a Riemannian manifold. Solutions to these self-duality equations are provided by manifolds of SU(2), SU(3), G_2 and Spin(7) holonomy. The equations in eight dimensions are a master set for those in lower dimensions. By considering gauge fields propagating on these self-dual manifolds and embedding the spin connection in the gauge connection, solutions to the D-dimensional equations for self-dual Yang-Mills fields are found. We show that the Yang-Mills action on such manifolds is topologically bounded from below, with the bound saturated precisely when the Yang-Mills field is self-dual. These results have a natural interpretation in supersymmetric string theory.Comment: 9 pages, Latex, factors in eqn. (6) corrected, acknowledgement and reference added, typos fixe