940 research outputs found

    Mutual Fund Theorem for continuous time markets with random coefficients

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    We study the optimal investment problem for a continuous time incomplete market model such that the risk-free rate, the appreciation rates and the volatility of the stocks are all random; they are assumed to be independent from the driving Brownian motion, and they are supposed to be currently observable. It is shown that some weakened version of Mutual Fund Theorem holds for this market for general class of utilities; more precisely, it is shown that the supremum of expected utilities can be achieved on a sequence of strategies with a certain distribution of risky assets that does not depend on risk preferences described by different utilities.Comment: 17 page

    Developing Students’ Skills of Identifying Reliable Scientific Sources: The Role of a Librarian

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    Purpose. The purpose of this paper is to provide modes of teaching Russian undergraduate students fundamental critical analysis of scientifc papers and ways of identifying misinformation and disinformation in “Academic Writing” discipline. design/methodology/approach. “Academic Writing” discipline was taught to frst-year undergraduate students by scientifc library experts. At a starting period students were asked to complete a questionnaire and perform a test, and then write an essay to identify how students were able to assess Web scientifc literature and verify their “tolerance” to inaccurate and fake scientifc information. Then contact hours on theory and practice of identifying and assessing information were introduced into the curriculum. At the end of the semester lists of works cited in original essays and fnal assays were compared.Findings. The fndings reveal that entirely all frst year undergraduate students lack the ability to differentiate between qualitative certain scientifc information and misinformation and disinformation, and they willingly borrow anything from the Web. However, students acquired necessary skills to assess information critically using socio-technical systems infrastructures.This was demonstrated with list of literature analysis in students’ essays and peer-checking. originality. It is headline news and social networks when it is necessary to distinguish from authentic and inaccurate information. However, skills of critical assessment of scientifc publications are of vital importance at a starting period of studies. In publications of that sort falsifcations, fabrications and other fake discoveries can lead to reputational and fnancial risks, and then trigger unethical demeanour of future researchers. It is qualifed librarians being experts in electronic resources and data based use who are able to get students to “digital hygiene”.Practical implications. The results of the paper can be used for teaching in university curriculum. Embedding information literacy and academic writing as well as involving information resources into students’ curriculum are aimed at the ability to identify misinformation and disinformation. Librarian-developed “Academic writing” discipline component might be introduced into curriculum as a self-contained short course or a composing element of any students’ academic discipline. All this mitigate the risks of applying low-equality, unverifed and openly fake information in educational and scientifc works

    Therapeutic complement targeting in ANCA-associated vasculitides and thrombotic microangiopathy

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    Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitides (AAVs) are a group of systemic autoimmune disorders characterized by necrotizing inflammation of medium-to-small vessels, a relative paucity of immune deposits, and an association with detectable circulating ANCAs. AAVs include granulomatosis with polyangiitis (renamed from Wegener's granulomatosis), microscopic polyangiitis, and eosinophilic granulomatosis with polyangiitis (Churg-Strauss syndrome). Until recently, AAVs have not been viewed as complement-mediated disorders. However, recent findings predominantly from animal studies demonstrated a crucial role of the complement system in the pathogenesis of AAVs. Complement activation or defects in its regulation have been described in an increasing number of acquired or genetically driven forms of thrombotic microangiopathy. Coinciding with this expanding spectrum of complement-mediated diseases, the question arises as to which AAV patients might benefit from a complement-targeted therapy. Therapies directed against the complement system point to the necessity of a genetic workup of genes of complement components and regulators in patients with AAV. Genetic testing together with pluripotent stem cells and bioinformatics tools may broaden our approach to the treatment of patients with aggressive forms of AAV

    Boundary Changes of Natural Plague Foci in the North-Western Pre-Caspian

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    Objective of the study is to specify present-day locations and sizes of natural plague foci in the North-Western Pre-Caspian.Materials and methods. Based on the results of field and office mapping of Pre-Caspian sandy and North-Western steppe plague foci, conducted in 2013–2014, designed have been electronic maps of the sectors, situated in the periphery of the foci.Results and conclusions. Detected has been marked reduction in sizes of natural foci owing to plowing of arid pastures. Over a significant distance, new natural focal boundaries are represented by linear elements of hydrography. Wherein such elements are absent, sector frames, in which evidence of enzooty remains, are accepted as formalized external boundaries. The process of deep and irreversible anthropogenic transformation of landscapes has resulted in the reduction of enzootic as regards plague territories: the steppe focus area has decreased by 22 %, being 51152 sq. km, the sandy one – by 13 %, amounting to 62510 sq. km. Farming on the extensive territories as a means of radical alterations of the landscapes has made the lands unsuitable for habitation of the little souslik, midday and tamarisk gerbils, which is an evidence of a complete loss of plague enzooty factors in the territory. The survey of actual position and sizes of natural plague foci within the rigid bonds, plotted on topographic maps and easily identifiable afield, provides for substantiated planning and complex prophylactic plague-control measures. Novel spatial parameters of the natural foci are suggested for the inclusion into official regulatory-methodological documents, guiding performance of epidemiological surveillance over plague

    MODIFICATIONS TO THE BOUNDARIES OF THE NATURAL PLAGUE FOCI IN THE VOLGA-URAL INTERFLUVE

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    Objective of the study is to locate the present-day sites and sizes of the natural plague foci in the Volga-Ural Interfluve. Materials and methods. According to the results of the field and office mapping, 2015 in the Volga-Ural steppe and sandy plague foci, designed have been electronic maps of the sectors situated in the periphery. Results and conclusions. During the past 3–4 decades significant decrease in plague enzooties in the territory of the Volga-Ural Interfluve has been observed. It occurs due to the plowing and melioration of the grazing lands. It is established that the southern and south-western outskirts of enzootic territories have natural boundaries represented with the linear elements of hydrography, and the eastern ones are the state border of the Russian Federation and the Republic of Kazakhstan. At sites where suitable linear elements of the landscape are absent (up north and west) the frames of the sectors, where evidence of enzooty is retained, are used as the formal external boundaries. Widespread plowing of semi-desert area made the territories in the eastern part of the Volgograd Region inadequate for small souslik habitation, which marks the loss of plague enzooty features. This fact in its turn led to the reduction of steppe focus acreage by 30 %, the coverage being currently 20873 km2 . Configuration of the sandy focus changed little, if at all, and amounts to 8625 km2 . Registering of the actual position and sizes of natural plague foci within the strictly set boundaries put on topographic maps provides for targeted planning and complex prophylactic anti-plague measures. New spatial indicators of natural plague foci are formalized in official normative-methodological documents regulating epidemiological surveillance over plague

    Limitations on the superposition principle: superselection rules in non-relativistic quantum mechanics

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    The superposition principle is a very basic ingredient of quantum theory. What may come as a surprise to many students, and even to many practitioners of the quantum craft, is tha superposition has limitations imposed by certain requirements of the theory. The discussion of such limitations arising from the so-called superselection rules is the main purpose of this paper. Some of their principal consequences are also discussed. The univalence, mass and particle number superselection rules of non-relativistic quantum mechanics are also derived using rather simple methods.Comment: 22 pages, no figure

    High frequency magnetic oscillations of the organic metal θ\theta-(ET)4_4ZnBr4_4(C6_6H4_4Cl2_2) in pulsed magnetic field of up to 81 T

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    De Haas-van Alphen oscillations of the organic metal θ\theta-(ET)4_4ZnBr4_4(C6_6H4_4Cl2_2) are studied in pulsed magnetic fields up to 81 T. The long decay time of the pulse allows determining reliable field-dependent amplitudes of Fourier components with frequencies up to several kiloteslas. The Fourier spectrum is in agreement with the model of a linear chain of coupled orbits. In this model, all the observed frequencies are linear combinations of the frequency linked to the basic orbit α\alpha and to the magnetic-breakdown orbit β\beta.Comment: 6 pages, 4 figure

    Level of Stress in Students with the Disturbance of Nasal Breathing and Comorbid Disorders

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    Background. The progressive increase of the number of schoolchildren with adaptation disorders and low level of health in recent years determines the need to assess the characteristics of the psychosomatic status in children and adolescents with various types of somatic pathology, including diseases of ENT organs, accompanied by nasal breathing disorders and hypoxia. It is also necessary to determine the severity of stress in children, for timely prevention and correction of these disorders.Aim: to assess the level of stress in schoolchildren with nasal breathing disorders against the background of nasal diseases and concomitant psychosomatic disorders.Materials and methods. 481 schoolchildren aged 12–17 (boys and girls) were examined. Nasal breathing disorders were assessed by a comprehensive ENT examination, including rhinoscopy, radiography of the sinuses, and olfactometry. The presence and severity of stress were determined by the questionnaire “Social factors and stress”.Results. We found that the high level of stress in children with nasal breathing disorders on the background of ENT pathology is more often associated with the high frequency and severity of psychosomatic symptoms: the presence of dorsalgia, asthenic syndrome, chronic headache and frequent episodes of abdominal pain. Moderately and significantly increased levels of stress associated with the presence of children with hypertension, asthenic syndrome, frequent abdominal pain, frequent pain in the cervical spine, panic disorders.Conclusions. Thus, the presence of certain psychosomatic complaints in children with nasal breathing disorders is directly related to the level of stress, which is important to take into account when planning preventive and corrective measures aimed at increasing the adaptive capacity and stress resistance of children. The studies illustrate the need to assess the psychosomatic status and the level of stress in schoolchildren with nasal breathing disorders taking into account their existing comorbid disorders of the psychosomatic spectrum
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