747 research outputs found

    On the Equivalence of Dual Theories

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    We discuss the equivalence of two dual scalar field theories in 2 dimensions. The models are derived though the elimination of different fields in the same Freedman--Townsend model. It is shown that tree SS-matrices of these models do not coincide. The 2-loop counterterms are calculated. It turns out that while one of these models is single-charged, the other theory is multi-charged. Thus the dual models considered are non-equivalent on classical and quantum levels. It indicates the possibility of the anomaly leading to non-equivalence of dual models.Comment: 14 pages, LaTeX; 2 figures, encapsulated PostScrip

    Investigation of the influence of technological conditions of microarc oxidation of magnesium alloys on their structural state and mechanical properties

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    Наведені дослідження структури і властивостей покриттів, отриманих при мікродуговій обробці на магнієвому сплаві. Обробка проводилася при анодно-катодному режимі в лужному електроліті з різними домішками. Показана можливість формування кристалічних оксидних покриттів різного фазового складу (MgO, MgAl₂O₄, Mg₂Sі₄, Mg₃(PO₄)₂) товщиною до 300 мкм, що мають високу адгезію з основою, гарні захисні властивості і високу твердість, яка досягає 6,6 ГПа

    The methodological problems of “human-sizedness” of modern cosmological theories

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    The article is picking up new methodological approaches to the study of the Cosmos and the understanding of the place of a human being in the Universe. The article has a methodological character and is presented in the form of the analysis and synthesis of various aspects of the study of this problem. The article considers theoretical and methodological aspects of cosmology, the analysis of modern scientific theories, the scope of their applicability. The obtained outputs can be used in cosmological modeling and in the studies of anthropological and existential aspects of cosmologyyesБелгородский госуниверсите

    Influence of the thermal factor on the composition of electron-beam high-entropy ALTiVCrNbMo coatings

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    This paper reports results of studying the element and phase compositions of electron-beam coatings based on the high-entropy alloy AlTiVCrNbMo, depending on the deposition temperature (in the range of 300...700 °С). The high-entropy alloys were melted in an arc furnace in an atmosphere of high-purity argon. Vacuum condensates of the high-entropy alloy (AlTiVCrNbMo) with a thickness of 3–5 µm were obtained in the vacuum setup UVN-2M-1 at a working vacuum of 5·10-5 mТоrr. The alloy evaporation was performed from the water-cooled ingot mold using an electron-beam gun with a power of 5 kW. Condensation of vapors of all the elements of the alloy was performed onto copper substrates at temperatures of 300, 500, 700 °C. Based on analysis of the element composition of materials of the target made of the high-entropy six-element alloy AlTiVCrNbMo and electron-beam coatings, based on it, we established the critical parameter (specific heat of vaporization of an element) that defined a selective change in the element composition. In accordance with a characteristic change in the composition of coatings of the multi-element high-entropy alloy, 3 groups of elements were distinguished: with a specific heat of evaporation of 280...350 kJ/mol (group 1), 420…460 kJ/mol (group 2), and 590…680 kJ/mol (group 3). It was shown that the formation of a single-phase coating of the high-entropy alloy (based on BCC of the crystalline lattice) occurs at the higher deposition temperature of 500...700 °C when the coating consists of not less than 5 elements. It was established that based on the conditions for an electron-beam process of materials formation, the results obtained can be divided into two types: those determined by the condition of evaporation of the target and those determined by the conditions of coating deposition. The density of flows of elements, evaporated from the target, is determined by their specific heat of evaporation. However, the ratio of atoms in the flow, derived in this way, may not be retained in the formed coating due to the secondary evaporation of elements from the growth surface. The obtained results allow us to substantiate principles for the selection of components for achieving the optimal element and phase compositions of high-entropy alloys.На основі аналізу елементного складу матеріалів мішені з високоентропійного шестиелементного сплаву AlTiVCrNbMo і електронно-променевих покриттів на його основі встановлено критичний параметр (питома теплота випаровування елемента), який визначає селективну зміну елементного складу. Показано, що формування однофазного покриття високоентропійного сплаву відбувається, коли до складу покриття входить не менше 5 елементів. Отримані результати дозволяють обґрунтувати принципи підбору компонент для досягнення оптимальних елементного та фазового складу високоентропійних сплавів

    The US ballistic missile defence policy in the Baltic and Nordic regions

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    This article examines the implications of the deployment of the US ballistic missile defense (BMD) system in the Baltic and Nordic regions. These implications are to be considered to ensure Russia's military security. Using the structural-functional method, the authors analyse the internal structure of the US BMD in Europe, stages of its implementation, and its influence on the military equilibrium in the region. Being similar to other regional missile defence systems of the Pentagon, BMD in Europe increases the offensive capabilities of the US armed forces and its allies and in doing so, it stops performing a purely defensive mission declared by Washington. It is stressed that the deployment of mobile sea- and land-based BMD elements in the Baltic Sea region and Nordic countries will inevitably destabilize the strategic situation and may lead to a new round of arms race in the region. The efficacy of BMD in Europe is evaluated from the perspective of military technology. The system’s potential threats to Russia's military security and its armed forces are assessed. The article considers measures to enhance national security that could be taken by Russia provided the US plans to deploy BMD in Europe are fully implemented

    Forecasting System Requirements to the Materials of the Shell of Fuel Elements of Innovative Fast Reactors

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    Innovative nuclear energy system (INSS) designed to ensure effective use of uranium 238 and thorium 232 to produce energy. Maintain the neutron balance of this process requires the development and use of new types of nuclear fuel and structural materials. This requires the development of models to predict changes in theirproperties under the action of fields of different radiation, temperature, stress and exposure to various chemical substances. It is important achievement is not the limiting parameters, and the optimal combination of the properties of materials and their working conditions. In this paper parameters such as the fluence of fast neutrons, the reaction rate in the fuel rod cladding and the change of nuclide composition, in particular, developments of hydrogen and helium, influencing the change of the strength properties of steels, are calculated

    Marked mitigation of transplant vascular sclerosis in FasL(gld) (CD95L) mutant recipients. I. The role of alloantibodies in the development of chronic rejection

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    Background. In the acute rejection of allografts, the interaction between Fas (CD95) and its ligand (FasL; CD95L) has been shown to be involved in mediating apoptotic cell death. The role, however, of these molecules in the pathogenesis of transplant vascular sclerosis is as yet undetermined. The present study was therefore designed to address this issue. Material. C3H/HEJ FasL(gld) (FasL-; H2(k)) spontaneously mutant mice were used either as donors or recipients of aortic allografts; wild-type C57BI/6 (B6; H2b) were used as corresponding recipients or donors (n=6/group), respectively. Controls included aortas transplanted across appropriate allogeneic and syngeneic strain combinations. For histopathological evaluations, the grafts were harvested at day 40 after transplantation, at which time, splenocytes and sera were also obtained for mixed leukocyte reaction and complement- mediated microcytotoxicity assays, respectively. Results. Similar to aortas obtained from allogeneic controls, allografts harvested from FasL-→B6 recipients had morphological evidence of chronic rejection characterized by circumferential intimal thickening with partial disruption of the elastic membranes. Correspondingly, heightened antidonor cellular reactivity was also witnessed in these recipients. On the contrary, B6 allografts harvested from the majority of C3H→FasL- recipients exhibited marked preservation of aortic morphology. Although these recipients had diminished antidonor cellular proliferation, the titers of alloantibodies were markedly elevated. Conclusion. The presence of FasL-expressing functional cytotoxic T cells is required for the pathogenesis of transplant vascular sclerosis. The significant reduction and/or absence of chronic rejection with the concomitant retention of antidonor humoral response in C3H FasL- recipients of B6 aortas prompt us to suggest that perhaps posttransplantation vasculopathy is initiated by cell-mediated cytotoxicity with its perpetuation facilitated by alloantibodies

    Improved surgical technique for the establishment of a murine model of aortic transplantation.

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    Aortic allotransplantation is a reliable procedure to study the evolvement of chronic rejection in mice. The progressive nature of this process in mice is characterized by diffuse and concentric myointimal proliferation which is inevitably associated with variable degrees of luminal constriction. These vascular changes are comparable to those that are witnessed in organ allografts undergoing chronic rejection in humans, underscoring its utility as a model of choice for the study of the development of this lesion. Whilst improved surgical technique has resulted in markedly enhanced graft survival, the results are far from being acceptable. Realizing this limitation, we embarked on developing a modified technique for aortic transplantation which would allow for improved graft survival in mice. A bypass conduit was created by end-to-side anastomosis of a segment of the donor's thoracic aorta into the infrarenal portion of the recipient's abdominal aorta. Using this technique, the graft survival was >98% with evidence in allotransplanted aorta of morphological changes pathognomonic of chronic rejection. On the contrary, no histopathological anomalies were discerned in aortic grafts transplanted across syngeneic animals. This modified surgical approach ameliorates the unacceptably high graft loss associated with earlier techniques, further extending the utility of this model as a tool to study the molecular and cellular mechanisms rudiment to the evolvement of chronic rejection
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