35 research outputs found

    Asymptotic Methods in the Statics and Dynamics of Perforated Plates and Shells with Periodic Structures

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    Homogenization Method in the Theory of Corrugated Plates

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    Gene-Environment Interaction Research and Transgenic Mouse Models of Alzheimer's Disease

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    The etiology of the sporadic form of Alzheimer's disease (AD) remains largely unknown. Recent evidence has suggested that gene-environment interactions (GxE) may play a crucial role in its development and progression. Whereas various susceptibility loci have been identified, like the apolipoprotein E4 allele, these cannot fully explain the increasing prevalence of AD observed with aging. In addition to such genetic risk factors, various environmental factors have been proposed to alter the risk of developing AD as well as to affect the rate of cognitive decline in AD patients. Nevertheless, aside from the independent effects of genetic and environmental risk factors, their synergistic participation in increasing the risk of developing AD has been sparsely investigated, even though evidence points towards such a direction. Advances in the genetic manipulation of mice, modeling various aspects of the AD pathology, have provided an excellent tool to dissect the effects of genes, environment, and their interactions. In this paper we present several environmental factors implicated in the etiology of AD that have been tested in transgenic animal models of the disease. The focus lies on the concept of GxE and its importance in a multifactorial disease like AD. Additionally, possible mediating mechanisms and future challenges are discussed

    Silicon and Germanium Nanostructures for Photovoltaic Applications: Ab-Initio Results

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    Actually, most of the electric energy is being produced by fossil fuels and great is the search for viable alternatives. The most appealing and promising technology is photovoltaics. It will become truly mainstream when its cost will be comparable to other energy sources. One way is to significantly enhance device efficiencies, for example by increasing the number of band gaps in multijunction solar cells or by favoring charge separation in the devices. This can be done by using cells based on nanostructured semiconductors. In this paper, we will present ab-initio results of the structural, electronic and optical properties of (1) silicon and germanium nanoparticles embedded in wide band gap materials and (2) mixed silicon-germanium nanowires. We show that theory can help in understanding the microscopic processes important for devices performances. In particular, we calculated for embedded Si and Ge nanoparticles the dependence of the absorption threshold on size and oxidation, the role of crystallinity and, in some cases, the recombination rates, and we demonstrated that in the case of mixed nanowires, those with a clear interface between Si and Ge show not only a reduced quantum confinement effect but display also a natural geometrical separation between electron and hole

    Methodology of Application of Modern Educational Technologies for Training Specialists

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    This paper discusses the methodology of applying modern educational technologies for training specialists in the field of metallurgical production based on the CDIO initiative. In order to expand the possibilities of the practice-orientedness of specialists, practical training is used to solve real problems and conditions of enterprise activity with the help of applied and specialized software products and the project method. The organizational and structural principles of the project method implementation are shown.В данной работе рассмотрена методология применения современных образовательных технологий для подготовки специалистов в сфере металлургического производства на основе инициативы CDIO. С целью расширения возможностей практико-ориентированности специалистов применяется практическая подготовка для решения реальных проблем и условий деятельности предприятий с помощью прикладных и специализированных программных продуктов и метода проектов. Показаны организационный и структурный принципы реализации метода проектов

    Ultramafic vegetation and soils in the circumboreal region of the Northern Hemisphere

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    The paper summarizes literature on climate, soil chemistry, vegetation and metal accumulation by plants found on ultramafic substrata in the circumboreal zone (sensu Takhtajan, Floristic regions of the world, 1986) of the Northern Hemisphere. We present a list of 50 endemic species and 18 ecotypes obligate to ultramafic soils from the circumboreal region of Holarctic, as well as 30 and 2 species of Ni and Zn hyperaccumulators, respectively. The number of both endemics and hyperaccumulators are markedly lower compared to that of the Mediterranean and tropical regions. The diversity of plant communities on ultramafics soils of the circumboral region is also described. The underlying causes for the differences of ultramafic flora between arctic, cold, cool temperate and Mediterranean and tropical regions are also discussed. © 2018, The Ecological Society of Japan
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