185 research outputs found

    Control of the self-assembly of alkanethiol-coated gold nanoparticles in the solid state

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    Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2008.Includes bibliographical references (leaf 24).A study of the behavior of nanoparticles in the presence of solvent vapors is presented. Millimeter-scale films of gold nanoparticles, one nanometer thick, are treated with solvent vapors at various temperatures and the behavior of the nanoparticles is tracked over time using transmission electron microscopy. The ultimate goal of this processing is to repair defects such as grains, dislocations, and vacancies in the original superlattice. Additionally, Langmuir-Schaeffer films of gold nanoparticles on water surfaces are subjected to thermal and ultrasonic treatment in an attempt to correct defects in the films, which are then transferred to solid substrates for observation. Unfortunately, none of these approaches is able to reduce the defect concentration in a lattice, although thermal treatment and sonication of Langmuir-Schaeffer nanoparticle films are found to provide a controllable approach to depositing exact double layers of nanoparticles.by Vladimir Tarasov.S.B

    Groebner Bases in Perturbative Calculations

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    In this paper we outline the most general and universal algorithmic approach to reduction of loop integrals to basic integrals. The approach is based on computation of Groebner bases for recurrence relations derived from the integration by parts method. In doing so we consider generic recurrence relations when propagators have arbitrary integer powers treated as symbolic variables (indices) for the relations.Comment: 5 page

    Current Concept of Revascularization in STEMI Patients with Multivessel Coronary Artery Disease: Evidence Base and Our Own Randomized Trial Results

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    The use of personalized approach for the optimal revascularization strategy in patients with ST‐segment elevation myocardial infarction (STEMI) and multivessel coronary artery disease (MVCAD) is based on complete revascularization by using latest generation drug‐eluting stents, with the choice between multivessel primary stenting and staged stenting strategy. The chapter includes theoretical rationale, original single‐center study, an original calculator for choosing optimal revascularization strategy, and a clinical case example

    The role of physical culture and sport activities in migrant integration

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    The relevance of the research topic consists in solving the scientific and practical problem of integrating migrants into the host community. The purpose of the research is to identify the role of physical culture and sports in the social integration of migrants. The methodology of the research is presented by the theories of assimilation of migrants with the local population; multiculturalism as the idea of the existence of a multinational state; transnationalism implemented in the conditions of globalization, informatization and digitalization of the society. The research methods used are content analysis of documents; analysis of statistical data, secondary analysis of sociological data, comparative analysis. The novelty of the research issue lies in the critical understanding of the advantages and limitations of physical training and sports as tools for integrating migrants into host communities in foreign countries. The results of the research have been defined: the role of physical training and sports activities in the process of migrants’ integration based on the domestic and foreign research; the main approaches to the implementation of migration policy measures in world practice (assimilation, multiculturalism and transnationalism) as well as the assessment of its success, by using the Migrant Integration Index. The study allows us to draw a conclusion about the dual nature of the integration potential of physical culture and sports in the implementation of migration policy: on the one hand, it is a way of revealing socio-cultural capital, searching for additional opportunities for self-realization in a new socio-cultural environment, overcoming social isolation, eliminating barriers of social exclusion; on the other hand, it is a deterrent effect of migrants’ age, gender, ethnicity, religion, level of education, attitude to various sports and physical activity in the countries of entry and exit on the integration process

    Social values of sports movement and prevention of migrantophobia

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    The modern world and Russia in particular is characterized by intensive migration processes. Ethnic, socio-cultural, religious conflicts and migrant-phobia are spreading in the countries that receive migrants. This requires a search for new means and mechanisms for the adaptation and integration of migrants, as well as the prevention of migrant phobia among the local population. The aim of the study is to give a sociological description of migrantophobia in Russia and substantiate the potential of the social values of the sports movement in its prevention. The content of the research is based on: 1) the analysis of bibliographic sources on the topic of the article; 2) a secondary analysis of sociological research on the perception of migrants and migrant phobia. Sociological studies demonstrate a downward trend in the level of migrantophobia in the Russian society, however, there is a need for new ways of preventing it. It has been concluded that sport as a social institution and such social values of sport as activity, self-realization, communication, respect, friendship, tolerance can play a significant role in the adaptation and integration of migrants, as well as in prevention of migrant phobia among the local population. Interpretations of the social functions of sports in relation to migrants have been given. The macro-, meso- and micro factors of the involvement of migrants in sports have been indicated

    Solving Recurrence Relations for Multi-Loop Feynman Integrals

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    We study the problem of solving integration-by-parts recurrence relations for a given class of Feynman integrals which is characterized by an arbitrary polynomial in the numerator and arbitrary integer powers of propagators, {\it i.e.}, the problem of expressing any Feynman integral from this class as a linear combination of master integrals. We show how the parametric representation invented by Baikov can be used to characterize the master integrals and to construct an algorithm for evaluating the corresponding coefficient functions. To illustrate this procedure we use simple one-loop examples as well as the class of diagrams appearing in the calculation of the two-loop heavy quark potential.Comment: 24 pages, 5 ps figures, references added, minor modifications, published versio

    Extracorporeal Membrane Oxygenation Support for Complex Percutaneous Coronary Interventions in Patients without Cardiogenic Shock

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    It has been shown that extracorporeal membrane oxygenation (ECMO) may provide cardiopulmonary support during percutaneous coronary interventions (PCI) in patients with refractory cardiogenic shock. Current guidelines consider ECMO and implantable left ventricular assist devices in selected non-ST-segment elevation acute coronary syndrome (NSTE-ACS) patients. High-risk PCI remains a viable revascularization strategy for those patients who are not suitable for surgery or those refusing it. However, such a subset of patients is considered to be at an extremely high risk of PCI complications as there is a risk of hemodynamic collapse during balloon inflations or complex procedures, particularly, if coronary dissection with vessel closure or no reflow occurs. This chapter is devoted to the use of ECMO support for high-risk complex PCI in NSTE-ACS patients without cardiogenic shock based on the theoretical rationale, observational retrospective single-center studies and clinical case examples
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