988 resultados para Los Alamos Scientific Laboratory. Theoretical Division.
Resumo:
OBJECTIVE: Fibrotic changes are initiated early in acute respiratory distress syndrome. This may involve overproliferation of alveolar type II cells. In an animal model of acute respiratory distress syndrome, we have shown that the administration of an adenoviral vector overexpressing the 70-kd heat shock protein (AdHSP) limited pathophysiological changes. We hypothesized that this improvement may be modulated, in part, by an early AdHSP-induced attenuation of alveolar type II cell proliferation. DESIGN: Laboratory investigation. SETTING: Hadassah-Hebrew University and University of Pennsylvania animal laboratories. SUBJECTS: Sprague-Dawley Rats (250 g). INTERVENTIONS: Lung injury was induced in male Sprague-Dawley rats via cecal ligation and double puncture. At the time of cecal ligation and double puncture, we injected phosphate-buffered saline, AdHSP, or AdGFP (an adenoviral vector expressing the marker green fluorescent protein) into the trachea. Rats then received subcutaneous bromodeoxyuridine. In separate experiments, A549 cells were incubated with medium, AdHSP, or AdGFP. Some cells were also stimulated with tumor necrosis factor-alpha. After 48 hrs, cytosolic and nuclear proteins from rat lungs or cell cultures were isolated. These were subjected to immunoblotting, immunoprecipitation, electrophoretic mobility shift assay, fluorescent immunohistochemistry, and Northern blot analysis. MEASUREMENTS AND MAIN RESULTS: Alveolar type I cells were lost within 48 hrs of inducing acute respiratory distress syndrome. This was accompanied by alveolar type II cell proliferation. Treatment with AdHSP preserved alveolar type I cells and limited alveolar type II cell proliferation. Heat shock protein 70 prevented overexuberant cell division, in part, by inhibiting hyperphosphorylation of the regulatory retinoblastoma protein. This prevented retinoblastoma protein ubiquitination and degradation and, thus, stabilized the interaction of retinoblastoma protein with E2F1, a key cell division transcription factor. CONCLUSIONS: : Heat shock protein 70-induced attenuation of cell proliferation may be a useful strategy for limiting lung injury when treating acute respiratory distress syndrome if consistent in later time points.
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Durante los últimos cinco años hemos visto cómo las bibliotecas universitarias y también las de investigación han aumentado el número de revistas electrónicas en su fondo bibliográfico, ya sea como complemento a las impresas o bien para reemplazarlas. Por su naturaleza, las publicaciones electrónicas representan retos para los sistemas existentes: tanto las editoriales como las bibliotecas se ven condicionadas por los procedimientos y procesos que reinaban en el entorno del papel impreso. Por ejemplo, las primeras siguen editando títulos según el patrón tradicional de recopilaciones de artículos, y las bibliotecas se esfuerzan para adaptar sus presupuestos y operaciones para la integración de suscripciones electrónicas.
Resumo:
Resumen: El artículo analiza los problemas de accesibilidad que actualmente presentan los artículos científicos en soporte digital. El estudio se centra en los aspectos de facilidad de uso del contenido de los documentos digitales según la forma en que se publiquen, sin entrar en el estudio de los distintos sistemas de recuperación. Se analizan los dos formatos más utilizados para la publicación de artículos científicos en soporte digital: HTML y PDF, estudiando el desempeño lector en relación a la presencia de sumarios o de tablas internas o vinculadas. El estudio se ha realizado con dos colectivos: 30 sujetos ciegos, usuarios de Jaws, contactados gracias a la mediación de la Fundación ONCE, y 30 sujetos no ciegos, profesores del Departamento de Biblioteconomía y Documentación de la Universidad de Barcelona. El estudio muestra que la localización de los datos contenidos en tablas se ve facilitada en documentos HTML por la inclusión de un sumario que vincule con la tabla, así como la inclusión de tablas completas en el cuerpo del documento HTML facilita la actividad lectora por parte de los usuarios ciegos. A nivel metodológico la presente investigación aporta dos novedades relevantes respecto a la literatura existente en los estudios de usabilidad con ciegos: estudia la usabilidad del formato PDF y es un test de usabilidad cuantitativo; este último hecho dificulta su comparación con la mayoría de artículos publicados. Abstract: This paper analyses the problems of accessibility posed by scientific articles published in digital format, focusing on the ease of use of their content with respect to the form in which they are published (irrespective of the recovery system). The two most widely used formats for the publication of scientific articles in digital format, HTML and PDF, are analysed, examining reader performance in relation to the presence of contents lists or internal or linked tables. The study involved two groups: 30 blind subjects, all JAWS users, contacted through the ONCE Foundation, and 30 sighted subjects, lecturers in the Department of Librarianship and Documentation of the University of Barcelona. The results shows the location of data in tables is easier in HTML documents through the inclusion of a contents list linked to these tables. Further, the inclusion of complete tables in the body of HTML document facilitates the reading activity of blind users. At the methodological level, this work reports two novelties with respect to the existing literature on usability by blind people: it examines the usability of the PDF format, and discusses a quantitative usability test. The latter hinders comparison with the majority of published articles.
Resumo:
Information and communication technologies enabled cultural and scientific patrimony -and information in general- to be presented in digital format, as well as in traditional analogical formats. The response was immediate and since the decade of the 1990s different projects have been designed to guarantee permanent access to the digital production -retrieval, storage, handling, preservation and dissemination. This article presents an international overview of existing models of national digital repositories, a name given to these projects that are normally generated by national libraries with a common objective: ensuring that web pages are always accessible.
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En el presente trabajo se describe el método de la determinación de la dureza efectuando las mediciones a escala microscópica. Se establece la relación entre la escala de dureza de Mohs y las unidades Vickers de dureza (VHN). Se describen también los cuatro tipos de aparatos microscópicos que pueden ser utilizados en dicho método.
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This paper analyses the representations of the body present in contemporary science-fiction literature and film. Using theoretical concepts by Althusser, Foucault and Haraway, the text establishes first a typology of cybernetic organisms in contemporary culture and reviews its presence and ideological implications in films like Robocop (1987), Johny Mnemonic (1995) or Matrix (1999). The paper argues for a self-conscience as political and historical subjects in order to avoid falling into a fallacious cyberandroginy that reinforces phallogocentric power structures.
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De acuerdo con la teoría de las áreas monetàrias óptimas,los shocks asimétricos tienen un papel fundamental en la determinación de los beneficios y los costes derivados del establecimiento de una área monetaria. En este sentido, diferentes estudios recientes señalan una importante reducción del grado de asimetría de los shocks en términos reales a lo largo de los últimos años entre los países europeos como consecuencia de la mayor coordinación de las políticas económicas y de la aproximación de las estructuras productivas. De todas maneras, una de las cuestiones clave en el nuevo entorno económico, y que no ha sido demasiado considerada a la literatura reciente, es el posible papel desestabilitzador de la política monetaria común como consecuencia de las diferencias en los mecanismos de transmisión de la política monetaria en los distintos países y regiones de la Zona Euro. En este trabajo se considera la mencionada cuestión desde un punto de vista teórico y se analiza empíricamente la existencia de diferencias regionales en los efectos de la política monetaria llevada a término en España a lo largo de los últimos años con la finalidad d identificar los principales determinantes de esta asimetría en el ámbito europeo
Resumo:
De acuerdo con la teoría de las áreas monetàrias óptimas,los shocks asimétricos tienen un papel fundamental en la determinación de los beneficios y los costes derivados del establecimiento de una área monetaria. En este sentido, diferentes estudios recientes señalan una importante reducción del grado de asimetría de los shocks en términos reales a lo largo de los últimos años entre los países europeos como consecuencia de la mayor coordinación de las políticas económicas y de la aproximación de las estructuras productivas. De todas maneras, una de las cuestiones clave en el nuevo entorno económico, y que no ha sido demasiado considerada a la literatura reciente, es el posible papel desestabilitzador de la política monetaria común como consecuencia de las diferencias en los mecanismos de transmisión de la política monetaria en los distintos países y regiones de la Zona Euro. En este trabajo se considera la mencionada cuestión desde un punto de vista teórico y se analiza empíricamente la existencia de diferencias regionales en los efectos de la política monetaria llevada a término en España a lo largo de los últimos años con la finalidad d identificar los principales determinantes de esta asimetría en el ámbito europeo
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This report summarizes research conducted at Iowa State University on behalf of the Iowa Department of Transportation, focusing on the volumetric state of hot-mix asphalt (HMA) mixtures as they transition from stable to unstable configurations. This has raditionally been addressed during mix design by meeting a minimum voids in the mineral aggregate (VMA) requirement, based solely upon the nominal maximum aggregate size without regard to other significant aggregate-related properties. The goal was to expand the current specification to include additional aggregate properties, e.g., fineness modulus, percent crushed fine and coarse aggregate, and their interactions. The work was accomplished in three phases: a literature review, extensive laboratory testing, and statistical analysis of test results. The literature review focused on the history and development of the current specification, laboratory methods of identifying critical mixtures, and the effects of other aggregate-related factors on critical mixtures. The laboratory testing involved three maximum aggregate sizes (19.0, 12.5, and 9.5 millimeters), three gradations (coarse, fine, and dense), and combinations of natural and manufactured coarse and fine aggregates. Specimens were compacted using the Superpave Gyratory Compactor (SGC), conventionally tested for bulk and maximum theoretical specific gravities and physically tested using the Nottingham Asphalt Tester (NAT) under a repeated load confined configuration to identify the transition state from sound to unsound. The statistical analysis involved using ANOVA and linear regression to examine the effects of identified aggregate factors on critical state transitions in asphalt paving mixtures and to develop predictive equations. The results clearly demonstrate that the volumetric conditions of an HMA mixture at the stable unstable threshold are influenced by a composite measure of the maximum aggregate size and gradation and by aggregate shape and texture. The currently defined VMA criterion, while significant, is seen to be insufficient by itself to correctly differentiate sound from unsound mixtures. Under current specifications, many otherwise sound mixtures are subject to rejection solely on the basis of failing to meet the VMA requirement. Based on the laboratory data and statistical analysis, a new paradigm to volumetric mix design is proposed that explicitly accounts for aggregate factors (gradation, shape, and texture).
Resumo:
Division of labor is a complex phenomenon observed throughout nature. Theoretical studies have focused either on its emergence through self-organization mechanisms or on its adaptive consequences. We suggest that the interaction of self-organization, which undoubtedly characterizes division of labor in social insects, and evolution should be further explored. We review the factors empirically shown to influence task choice. In light of these factors, we review the most important self-organization and evolutionary models for division of labor and outline their advantages and limitations. We describe ways to unify evolution and self-organization in the theoretical study of division of labor and recent results in this area. Finally, we discuss some benchmarks and primary challenges of this approach.
Resumo:
The present study explores the statistical properties of a randomization test based on the random assignment of the intervention point in a two-phase (AB) single-case design. The focus is on randomization distributions constructed with the values of the test statistic for all possible random assignments and used to obtain p-values. The shape of those distributions is investigated for each specific data division defined by the moment in which the intervention is introduced. Another aim of the study consisted in testing the detection of inexistent effects (i.e., production of false alarms) in autocorrelated data series, in which the assumption of exchangeability between observations may be untenable. In this way, it was possible to compare nominal and empirical Type I error rates in order to obtain evidence on the statistical validity of the randomization test for each individual data division. The results suggest that when either of the two phases has considerably less measurement times, Type I errors may be too probable and, hence, the decision making process to be carried out by applied researchers may be jeopardized.
Resumo:
Resumen: El artículo analiza los problemas de accesibilidad que actualmente presentan los artículos científicos en soporte digital. El estudio se centra en los aspectos de facilidad de uso del contenido de los documentos digitales según la forma en que se publiquen, sin entrar en el estudio de los distintos sistemas de recuperación. Se analizan los dos formatos más utilizados para la publicación de artículos científicos en soporte digital: HTML y PDF, estudiando el desempeño lector en relación a la presencia de sumarios o de tablas internas o vinculadas. El estudio se ha realizado con dos colectivos: 30 sujetos ciegos, usuarios de Jaws, contactados gracias a la mediación de la Fundación ONCE, y 30 sujetos no ciegos, profesores del Departamento de Biblioteconomía y Documentación de la Universidad de Barcelona. El estudio muestra que la localización de los datos contenidos en tablas se ve facilitada en documentos HTML por la inclusión de un sumario que vincule con la tabla, así como la inclusión de tablas completas en el cuerpo del documento HTML facilita la actividad lectora por parte de los usuarios ciegos. A nivel metodológico la presente investigación aporta dos novedades relevantes respecto a la literatura existente en los estudios de usabilidad con ciegos: estudia la usabilidad del formato PDF y es un test de usabilidad cuantitativo; este último hecho dificulta su comparación con la mayoría de artículos publicados. Abstract: This paper analyses the problems of accessibility posed by scientific articles published in digital format, focusing on the ease of use of their content with respect to the form in which they are published (irrespective of the recovery system). The two most widely used formats for the publication of scientific articles in digital format, HTML and PDF, are analysed, examining reader performance in relation to the presence of contents lists or internal or linked tables. The study involved two groups: 30 blind subjects, all JAWS users, contacted through the ONCE Foundation, and 30 sighted subjects, lecturers in the Department of Librarianship and Documentation of the University of Barcelona. The results shows the location of data in tables is easier in HTML documents through the inclusion of a contents list linked to these tables. Further, the inclusion of complete tables in the body of HTML document facilitates the reading activity of blind users. At the methodological level, this work reports two novelties with respect to the existing literature on usability by blind people: it examines the usability of the PDF format, and discusses a quantitative usability test. The latter hinders comparison with the majority of published articles.
Resumo:
This paper analyses the representations of the body present in contemporary science-fiction literature and film. Using theoretical concepts by Althusser, Foucault and Haraway, the text establishes first a typology of cybernetic organisms in contemporary culture and reviews its presence and ideological implications in films like Robocop (1987), Johny Mnemonic (1995) or Matrix (1999). The paper argues for a self-conscience as political and historical subjects in order to avoid falling into a fallacious cyberandroginy that reinforces phallogocentric power structures.