519 research outputs found

    Ultrafast phase-change logic device driven by melting processes.

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    The ultrahigh demand for faster computers is currently tackled by traditional methods such as size scaling (for increasing the number of devices), but this is rapidly becoming almost impossible, due to physical and lithographic limitations. To boost the speed of computers without increasing the number of logic devices, one of the most feasible solutions is to increase the number of operations performed by a device, which is largely impossible to achieve using current silicon-based logic devices. Multiple operations in phase-change-based logic devices have been achieved using crystallization; however, they can achieve mostly speeds of several hundreds of nanoseconds. A difficulty also arises from the trade-off between the speed of crystallization and long-term stability of the amorphous phase. We here instead control the process of melting through premelting disordering effects, while maintaining the superior advantage of phase-change-based logic devices over silicon-based logic devices. A melting speed of just 900 ps was achieved to perform multiple Boolean algebraic operations (e.g., NOR and NOT). Ab initio molecular-dynamics simulations and in situ electrical characterization revealed the origin (i.e., bond buckling of atoms) and kinetics (e.g., discontinuouslike behavior) of melting through premelting disordering, which were key to increasing the melting speeds. By a subtle investigation of the well-characterized phase-transition behavior, this simple method provides an elegant solution to boost significantly the speed of phase-change-based in-memory logic devices, thus paving the way for achieving computers that can perform computations approaching terahertz processing rates.This is the author's accepted manuscript. The final version is published by PNAS here: http://www.pnas.org/content/early/2014/08/27/1407633111.full.pdf+html?with-ds=yes

    Corpo-oralidades y territorio en la dramaturgia de Felipe Vergara, de la experiencia del conflicto al correlato artístico

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    Dissertação apresentada ao Programa de Pós- Graduação em Literatura Comparada da Universidade Federal da Integração Latino- Americana, como requisito parcial à obtenção do título de Mestre em Literatura Comparada. Orientador: Andrea Ciacchi (Pós-Doutor Universidade Estadual de Campinas , Doutor em Iberistica, Università di Bologn , a Mestro em Letras, Universidade Federal da Paraíba , Graduação em Antropologia, Università di Roma)Propongo una lectura de la poética teatral de Felipe Vergara desde el estudio de tres piezas: Kilele, una epopeya artesanal; Arimbato, el camino del árbol; y Coragyps Sapiens, partiendo por considerar el teatro como un encuentro vital entre los artistas y su público, que instala escrituras permeadas por el tiempo, la historia y el contexto de su surgimiento. En ese sentido planteo que la dramaturgia Vergara funciona como un correlato que revive el rastro de la experiencia de guerra de las comunidades del Pacífico colombiano, a la vez que toma una posición autónoma de resistencia artística, social y cultural, y que porta en su discurso las versiones silenciadas históricamente, las versiones subterráneas. Para el análisis abordo: la relación indisoluble de las comunidades con su territorio, manifiesta en las obras; las representaciones de cuerpo y su fragmentación tanto a nivel individual como colectivo; y su reconstrucción a través de los duelos que se encarnan en transmisiones rituales, corporales y orales, en actos de memoria viva. Presento así un recorrido por la propuesta artística de Felipe Vergara y un acercamiento a algunas propuestas teatrales las comunidades del Pacífico colombiano, en las que curiosamente, Vergara trabajó de la mano de Inge Kleutgens, Catalina Medina y otros colaboradores. Retomaremos tres obras de Vergara, así como tres de las creaciones colectivas de las comunidades con las que , rastreando en ellas los procesos y procedimientos para la reconstrucción de una porción de los relatos alternativos de la historia social de las vivencias del conflicto social y armado colombiano, traducidas en las relaciones entre los imaginarios y las representaciones simbólicas de las obras, que asocian las gamas de sentido del texto y de la puesta en escena, con el cauce efectivo que propicia su escritura.Proponho uma leitura da poesia teatral de Felipe Vergara a partir do estudo de três obras: Kilele, una epopeya artesanal; Arimbato, el camino del árbol; y Coragyps Sapiens, começando por considerar o teatro como um encontro vital entre os artistas e seu público, que instala escritos permeados pelo tempo, pela história e pelo contexto de seu surgimento. Nesse sentido, proponho que a dramaturgia de Vergara funcione como um correlato que revive o traço da experiência de guerra das comunidades do Pacífico colombiano, ao mesmo tempo em que assume uma posição autônoma de resistência artística, social e cultural, e que carrega em seu discurso as versões silenciadas historicamente, as versões subterrâneas. Pela análise a bordo: a relação indissolúvel das comunidades com seu território, manifestada nos trabalhos; representações corporais e sua fragmentação individual e coletiva; e sua reconstrução através dos duelos que se encarnam em transmissões rituais, corporais e orais, em atos de memória viva. Apresento um encontro com a proposta artística de Felipe Vergara, propostas teatrais das comunidades do Pacífico colombiano, nas quais curiosamente, Vergara trabalhou com Inge Kleutgens, Catalina Medina e outros colaboradores. Retornaremos a três obras de Vergara, bem como a três das criações coletivas das comunidades com as quais traçamos os processos e procedimentos para a reconstrução de uma parte dos relatos alternativos da história social das experiências do conflito social e armado colombiano , traduzido nas relações entre o imaginário e as representações simbólicas das obras, que associam as faixas de significado do texto e da encenação, ao canal efetivo que propicia sua escrit

    Synergistic Inhibition of Endothelial Cell Proliferation, Tube Formation, and Sprouting by Cyclosporin A and Itraconazole

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    Pathological angiogenesis contributes to a number of diseases including cancer and macular degeneration. Although angiogenesis inhibitors are available in the clinic, their efficacy against most cancers is modest due in part to the existence of alternative and compensatory signaling pathways. Given that angiogenesis is dependent on multiple growth factors and a broad signaling network in vivo, we sought to explore the potential of multidrug cocktails for angiogenesis inhibition. We have screened 741 clinical drug combinations for the synergistic inhibition of endothelial cell proliferation. We focused specifically on existing clinical drugs since the re-purposing of clinical drugs allows for a more rapid and cost effective transition to clinical studies when compared to new drug entities. Our screen identified cyclosporin A (CsA), an immunosuppressant, and itraconazole, an antifungal drug, as a synergistic pair of inhibitors of endothelial cell proliferation. In combination, the IC50 dose of each drug is reduced by 3 to 9 fold. We also tested the ability of the combination to inhibit endothelial cell tube formation and sprouting, which are dependent on two essential processes in angiogenesis, endothelial cell migration and differentiation. We found that CsA and itraconazole synergistically inhibit tube network size and sprout formation. Lastly, we tested the combination on human foreskin fibroblast viability as well as Jurkat T cell and HeLa cell proliferation, and found that endothelial cells are selectively targeted. Thus, it is possible to combine existing clinical drugs to synergistically inhibit in vitro models of angiogenesis. This strategy may be useful in pursuing the next generation of antiangiogenesis therapy

    Revisiting the Local Structure in Ge-Sb-Te based Chalcogenide Superlattices.

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    The technological success of phase-change materials in the field of data storage and functional systems stems from their distinctive electronic and structural peculiarities on the nanoscale. Recently, superlattice structures have been demonstrated to dramatically improve the optical and electrical performances of these chalcogenide based phase-change materials. In this perspective, unravelling the atomistic structure that originates the improvements in switching time and switching energy is paramount in order to design nanoscale structures with even enhanced functional properties. This study reveals a high- resolution atomistic insight of the [GeTe/Sb2Te3] interfacial structure by means of Extended X-Ray Absorption Fine Structure spectroscopy and Transmission Electron Microscopy. Based on our results we propose a consistent novel structure for this kind of chalcogenide superlattices

    Risk factors for severe hand foot mouth disease in Singapore: a case control study

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    BACKGROUND: Hand foot mouth disease (HFMD) is a common childhood infection that can potentially lead to serious complications. The aim of this study is to identify risk factors of acquiring severe HFMD in our population. METHODS: We performed a case control study using patients admitted to our hospital from August 2004 to July 2014. Cases were patients with severe HFMD disease while controls were age-matched patients obtained from the same year, in a 2:1 ratio. Data comprising demographic characteristics, clinical symptoms and signs, and lab findings were collected. Conditional univariable logistic regression was performed to determine risk factors for severe disease. RESULTS: A total of 24 cases of severe HFMD were identified and matched with 48 controls. Seventeen (70.8 %) cases had central nervous system complications. Seven (29.2 %) had cardiovascular complications without evidence of myocarditis. One patient died of encephalitis. The overall mortality of severe disease is 4 %. Evidence of hypoperfusion, seizure, altered mentation, meningeal irritation, tachycardia, tachypnea, raised absolute neutrophil count and EV-A71 (Enterovirus A71) positivity were significantly associated with a severe course of HFMD. CONCLUSION: In managing children with HFMD, physicians should consider these factors to help identify patients at risk for severe disease

    Erythropoietin Improves the Survival of Fat Tissue after Its Transplantation in Nude Mice

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    Background: Autologous transplanted fat has a high resorption rate, providing a clinical challenge for the means to reduce it. Erythropoietin (EPO) has non-hematopoietic targets, and we hypothesized that EPO may improve long-term fat graft survival because it has both pro-angiogenic and anti-apoptotic properties. We aimed to determine the effect of EPO on the survival of human fat tissue after its transplantation in nude mice. Methodology/Principal Findings: Human fat tissue was injected subcutaneously into immunologically-compromised nude mice, and the grafts were then treated with either 20 IU or 100 IU EPO. At the end of the 15-week study period, the extent of angiogenesis, apoptosis, and histology were assessed in the fat grafts. The results were compared to vascular endothelial growth factor (VEGF)-treated and phosphate-buffered saline (PBS)-treated fat grafts. The weight and volume of the EPOtreated grafts were higher than those of the PBS-treated grafts, whose weights and volumes were not different from those of the VEGF-treated grafts. EPO treatment also increased the expression of angiogenic factors and microvascular density, and reduced inflammation and apoptosis in a dose-dependent manner in the fat grafts. Conclusions/Significance: Our data suggest that stimulation of angiogenesis by a cluster of angiogenic factors and decreased fat cell apoptosis account for potential mechanisms that underlie the improved long-term survival of fa

    In vivo clearance of surfactant lipids during acute pulmonary inflammation.

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    BACKGROUND: A decrease in pulmonary surfactant has been suggested to contribute to the lung dysfunction associated with pulmonary inflammation. A number of studies have implicated surfactant clearance as a possible mechanism for altered pool sizes. The objective of the current study was to specifically investigate the mechanisms of surfactant clearance in a rodent model of acute pulmonary inflammation. METHODS: Inflammation was induced by intrapulmonary instillation of lipopolysaccharide (LPS: 100 μg/kg). Lipid clearance was assessed at 18 and 72 hours post-LPS instillation by intratracheal administration of radiolabel surfactant-like liposomes 2 hours prior to isolation and analysis of inflammatory cells and type II cells. RESULTS: At both 18 and 72 hours after LPS instillation there was significantly less radioactivity recovered in the lavage fluid compared to respective control groups (p < 0.05). At both time points, the number of cells recovered by lavage and their associated radioactivity was greater compared to control groups (p < 0.01). There was no difference in recovery of radioactivity by isolated type II cells or other cells obtained from enzymatic digestion of lung tissue. CONCLUSION: These results show that increased clearance of surfactant lipids in our model of acute pulmonary inflammation is primarily due to the inflammatory cells recruited to the airspace and not increased uptake by alveolar type II cells
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