83 research outputs found

    Interference between resonant and Auger mechanisms for charge-exchange processes near surfaces

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    In this work we solve the dynamics of the Newns-Anderson Hamiltonian supplemented with Auger termsand analyze the case of He1 scattered off an Al ~100! surface. The dynamical solution is compared with resultsof calculations based on much simpler approximations. We prove that resonant and Auger processes can betreated separately and independently in this case and that charge exchange between He and Al proceeds viaresonant and Auger exchange of electrons between the promoted molecular orbital of He and the conductionband states of Al.Fil: García, Evelina Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; ArgentinaFil: Wang, N.P.. Universidad Autónoma de Madrid; EspañaFil: Monreal, R.C.. Universidad Autónoma de Madrid; EspañaFil: Goldberg, Edith Catalina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; Argentin

    Network Flows Heuristics for Complementary Cell Suppression: An Empirical Evaluation and Extensions

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    Several network flows heuristics have been suggested in the past for the solution of the complementary suppression problem. However, a limited computational experience using them is reported in the literature, and, moreover, they were only appropriate for two-dimensional tables. The purpose of this paper is twofold. First, we perform an em-pirical comparison of two network flows heuristics. They are improved versions of already existing approaches. Second, we show that exten-sions of network flows methods (i.e., multicommodity network flows and network flows with side constraints) can model three-dimensional, hierarchical and linked tables. Exploiting this network structure can improve the performance of any solution method solely based on linear programming formulations

    The level of blood plasma mitochondrial DNA upon acute myocardium damage in experiment

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    The aim of the present investigation is to study the level of plasma mtDNA as a potential marker of cardiomyocyte damage in 2 and 4 h after subcutaneous injection of adrenaline and during the formed morphological alterations of the myocardium (3 days). Methods. Real time PCR. Male Wistar rats were used as the experimental animals. Results. It was shown that during the increase in the activity of cytolysis biomarkers, at the first hours after adrenaline injection, no reliable increase is observed in the level of free circulating blood mtDNA. A tendency of 2.5-fold increase in this parameter was established at the third day after adrenaline injection during the development of acute inflammatory process in the myocardium. On the whole, further researches are needed on the dynamics of mtDNA level upon acute damage of the myocardium in experimental and clinical investigations for unbiased estimation of the prospects of using the parameter in laboratory diagnostics. Keywords: mitochondrial DNA, cardiovascular diseases, adrenaline myocarditis, cytolysis biomarkers.Цель. Изучить уровень мтДНК плазмы крови как возможного маркера повреждений кардиомиоцитов через 2 и 4 ч после подкожной инъекции адреналина и на фоне сформированных морфологических изменений миокарда (3-и сут). Методы. Полимеразная цепная реакция в реальном времени. В экспериментах использовали самцов крыс линии Вистар. Результаты. Показано, что наряду с увеличением активности биомаркеров цитолиза в первые часы после введения адреналина значимого повышения уровня свободно циркулирующей мтДНК крови не происходит. Установлена тенденция к 2,5-кратному возрастанию данного показателя на 3-и сут после инъекции адреналина на фоне развития острого воспалительного процесса в миокарде. Выводы. В целом для объективной оценки перспектив этого показателя в лабораторной диагностике инфаркта миокарда необходимо дальнейшее изучение динамики уровня мтДНК при острых повреждениях миокарда в экспериментальных и клинических исследованиях. Ключевые слова: митохондриальная ДНК, сердечно-сосудистые заболевания, адреналиновый миокардит, биомаркеры цитолиза.Мета. Вивчити рівень мтДНК плазми крові як можливого маркера пошкоджень кардіоміоцитиів через 2 і 4 год після підшкірної ін’єкції адреналіну та на фоні сформованих морфологічних змін міокарда (3-тя доба). Методи. Полімеразна ланцюгова реакція у реальному часі. В експериментах використано самців щурів лінії Вістар. Результати. Показано, що поряд із збільшенням активності біомаркерів цитолізу в перші години після введення адреналіну суттєвого підвищення рівня вільно циркулюючої мтДНК крові не відбувається. Встановлено тенденцію до 2,5-разового зростання даного показника на 3-тю добу після ін’кції адреналіну на фоні розвитку гострого запального процесу в міокарді. Висновки. У цілому для об’єктивної оцінки перспектив цього показника у лабораторній діагностиці інфаркта міокарда необхідно подальше вивчення динаміки рівня мтДНК при гострих ураженнях міокарда в експериментальних і клінічних дослідженнях. Ключові слова: мітохондріальна ДНК, серцево-судинні захворювання, адреналіновий міокардит, біомаркери цитолізу

    Second order optimality conditions and their role in PDE control

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    If f : Rn R is twice continuously differentiable, f’(u) = 0 and f’’(u) is positive definite, then u is a local minimizer of f. This paper surveys the extension of this well known second order suffcient optimality condition to the case f : U R, where U is an infinite-dimensional linear normed space. The reader will be guided from the case of finite-dimensions via a brief discussion of the calculus of variations and the optimal control of ordinary differential equations to the control of nonlinear partial differential equations, where U is a function space. In particular, the following questions will be addressed: Is the extension to infinite dimensions straightforward or will unexpected difficulties occur? How second order sufficient optimality conditions must be modified, if simple inequality constraints are imposed on u? Why do we need second order conditions and how can they be applied? If they are important, are we able to check if they are fulfilled order sufficient optimality condition to the case f : U R, where U is an infinite-dimensional linear normed space. The reader will be guided from the case of finite-dimensions via a brief discussion of the calculus of variations and the optimal control of ordinary differential equations to the control of nonlinear partial differential equations, where U is a function space. In particular, the following questions will be addressed: Is the extension to infinite dimensions straightforward or will unexpected difficulties occur? How second order sufficient optimality conditions must be modified, if simple inequality constraints are imposed on u? Why do we need second order conditions and how can they be applied? If they are important, are we able to check if they are fulfilled? It turns out that infinite dimensions cause new difficulties that do not occur in finite dimensions. We will be faced with the surprising fact that the space, where f’’(u) exists can be useless to ensure positive definiteness of the quadratic form v f’’(u)v2. In this context, the famous two-norm discrepancy, its consequences, and techniques for overcoming this difficulty are explained. To keep the presentation simple, the theory is developed for problems in function spaces with simple box constraints of the form a = u = ß. The theory of second order conditions in the control of partial differential equations is presented exemplarily for the nonlinear heat equation. Different types of critical cones are introduced, where the positivity of f’’(u) must be required. Their form depends on whether a so-called Tikhonov regularization term is part of the functional f or not. In this context, the paper contains also new results that lead to quadratic growth conditions in the strong sense. As a first application of second-order sufficient conditions, the stability of optimal solutions with respect to perturbations of the data of the control problem is discussed. Second, their use in analyzing the discretization of control problems by finite elements is studied. A survey on further related topics, open questions, and relevant literature concludes the paper.The first author was partially supported by the Spanish Ministerio de Economía y Competitividad under project MTM2011-22711, the second author by DFG in the framework of the Collaborative Research Center SFB 910, project B6

    A Biased Random Key Genetic Algorithm Approach for Unit Commitment Problem

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    A Biased Random Key Genetic Algorithm (BRKGA) is proposed to find solutions for the unit commitment problem. In this problem, one wishes to schedule energy production on a given set of thermal generation units in order to meet energy demands at minimum cost, while satisfying a set of technological and spinning reserve constraints. In the BRKGA, solutions are encoded by using random keys, which are represented as vectors of real numbers in the interval [0, 1]. The GA proposed is a variant of the random key genetic algorithm, since bias is introduced in the parent selection procedure, as well as in the crossover strategy. Tests have been performed on benchmark large-scale power systems of up to 100 units for a 24 hours period. The results obtained have shown the proposed methodology to be an effective and efficient tool for finding solutions to large-scale unit commitment problems. Furthermore, from the comparisons made it can be concluded that the results produced improve upon some of the best known solutions
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