136 research outputs found

    Three-Fold Diffraction Symmetry in Epitaxial Graphene and the SiC Substrate

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    The crystallographic symmetries and spatial distribution of stacking domains in graphene films on SiC have been studied by low energy electron diffraction (LEED) and dark field imaging in a low energy electron microscope (LEEM). We find that the graphene diffraction spots from 2 and 3 atomic layers of graphene have 3-fold symmetry consistent with AB (Bernal) stacking of the layers. On the contrary, graphene diffraction spots from the buffer layer and monolayer graphene have apparent 6-fold symmetry, although the 3-fold nature of the satellite spots indicates a more complex periodicity in the graphene sheets.Comment: An addendum has been added for the arXiv version only, including one figure with five panels. Published paper can be found at http://link.aps.org/doi/10.1103/PhysRevB.80.24140

    Theoretical and methodological approaches to the determination of the "capital of enterprise" economic essence

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    Розглянуто основні підходи до обґрунтування сутності поняття "капітал підприємства". Сформовано власне визначення категорії "капітал" підприємства як матеріальні, грошові та нематеріальні ресурси, що авансовано у формування активів підприємства, необхідних для здійснення його господарської діяльності в довгостроковій перспективі, з метою отримання доходу та прибутку. Визначено склад взаємопов'язаних і взаємообумовлених внутрішніх і зовнішніх факторів, що впливають на структуру капіталу підприємства та визначають можливості управління ним.The main approaches to substantiating the essence of the concept of "capital of an enterprise" are considered. The actual definition of the category of "capital" of the enterprise as material, monetary and intangible resources, which was advanced in forming the assets of an enterprise necessary for its economic activity in the long run, was formed for the purpose of obtaining income and profits. The composition of interconnected and mutually determined internal and external factors influencing the structure of the enterprise capital and determine the possibilities of management of it are determined. The internal factors determining the peculiarities of the formation and composition of the capital of enterprises are: the organizational and legal form of the enterprise's activity, the existing capital structure, the level of profitability of the operating acti vity, the size of the enterprise and the stage of its life cycle, the degree of financial stability, the priorities of owners and management in choosing a method of financial provision, etc. External factors are the following: the state of the legislative process, the level of administrative influence on the economy of enterprises, the stability of the commodity market, the financial market situation, the tax burden on the enterprise, the ratio of creditors and investors to a particular enterprise, the degree of credit risk and the level of potential of the banking system, tendencies of development of other branches of economy

    IP-10-Mediated T Cell Homing Promotes Cerebral Inflammation over Splenic Immunity to Malaria Infection

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    Plasmodium falciparum malaria causes 660 million clinical cases with over 2 million deaths each year. Acquired host immunity limits the clinical impact of malaria infection and provides protection against parasite replication. Experimental evidence indicates that cell-mediated immune responses also result in detrimental inflammation and contribute to severe disease induction. In both humans and mice, the spleen is a crucial organ involved in blood stage malaria clearance, while organ-specific disease appears to be associated with sequestration of parasitized erythrocytes in vascular beds and subsequent recruitment of inflammatory leukocytes. Using a rodent model of cerebral malaria, we have previously found that the majority of T lymphocytes in intravascular infiltrates of cerebral malaria-affected mice express the chemokine receptor CXCR3. Here we investigated the effect of IP-10 blockade in the development of experimental cerebral malaria and the induction of splenic anti-parasite immunity. We found that specific neutralization of IP-10 over the course of infection and genetic deletion of this chemokine in knockout mice reduces cerebral intravascular inflammation and is sufficient to protect P. berghei ANKA-infected mice from fatality. Furthermore, our results demonstrate that lack of IP-10 during infection significantly reduces peripheral parasitemia. The increased resistance to infection observed in the absence of IP-10-mediated cell trafficking was associated with retention and subsequent expansion of parasite-specific T cells in spleens of infected animals, which appears to be advantageous for the control of parasite burden. Thus, our results demonstrate that modulating homing of cellular immune responses to malaria is critical for reaching a balance between protective immunity and immunopathogenesis

    Mathematical concepts for the micromechanical modelling of dislocation dynamics with a phase-field approach

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    International audienceThis contribution reviews mathematical concepts of micro-mechanical modeling in the phase-field approach applied to dislocation dynamics. The intention is twofold: On the one hand, modelling of dislocation dynamics is a very recent field of development in phase-field theory, in comparison to the simulation of diffusional phase transformation and related micro-structure evolution problems in materials science. The reason is that modelling dislocation dynamics poses several challenges for phase-field concepts which go beyond purely diffusional problems in materials science as, e.g., dendritic solidification, as we point out in Sect.3. On the other hand, the modelling of dislocations has triggered further wide-ranging developments of phase-field based models for deformation problems. This is an important development, since a comprehensive model for deformation problems should include displacive as well as diffusional degrees of freedom from the atomic scale to the microscale. This is something phase-field theory is capable of, as dicussed in this review article. We aim to give an overview on relevant mathematical concepts, and to stimulate further steps in this direction

    Cure of Chronic Viral Infection and Virus-Induced Type 1 Diabetes by Neutralizing Antibodies

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    The use of neutralizing antibodies is one of the most successful methods to interfere with receptor–ligand interactions in vivo. In particular blockade of soluble inflammatory mediators or their corresponding cellular receptors was proven an effective way to regulate inflammation and/or prevent its negative consequences. However, one problem that comes along with an effective neutralization of inflammatory mediators is the general systemic immunomodulatory effect. It is, therefore, important to design a treatment regimen in a way to strike at the right place and at the right time in order to achieve maximal effects with minimal duration of immunosuppression or hyperactivation. In this review, we reflect on two examples of how short time administration of such neutralizing antibodies can block two distinct inflammatory consequences of viral infection. First, we review recent findings that blockade of IL-10/IL-10R interaction can resolve chronic viral infection and second, we reflect on how neutralization of the chemokine CXCL10 can abrogate virus-induced type 1 diabetes

    Modeling morphological instabilities in lipid membranes with anchored amphiphilic polymers

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    Anchoring molecules, like amphiphilic polymers, are able to dynamically regulate membrane morphology. Such molecules insert their hydrophobic groups into the bilayer, generating a local membrane curvature. In order to minimize the elastic energy penalty, a dynamic shape instability may occur, as in the case of the curvature-driven pearling instability or the polymer-induced tubulation of lipid vesicles. We review recent works on modeling of such instabilities by means of a mesoscopic dynamic model of the phase-field kind, which take into account the bending energy of lipid bilayers
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