1,022 research outputs found

    La información, los servicios y el «complejo electrónico»: una visión panorámica de la tercera revolución industrial

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    Federico Alberto Cuello C. (biografía): Economista dominicano. Estudió en el Instituto Tecnológico de Santo Domingo e hizo un doctorado en economía del desarrollo en la Universidad de Illinois, centro en el que también realizó un M. A. en teoría económica y econometría. Laboró en el Departamento de Deuda Externa del Banco Central y participó en la Comisión Nacional del GATT. De una larga trayectoria diplomática, fue embajador del país ante el Reino de Bélgica, la Unión Europea la República Checa y Polonia. Luego representó el país ante las Naciones Unidas. Y desde julio de 2011 es embajador de la República Dominicana ante el Reino Unido. Entre sus múltiples artículos y trabajos leídos en centros de estudios superiores, se encuentran los libros: Nuevos aires en las relaciones dominico-europeas, una ronda de negociaciones multilaterales para el desarrollo, Hacia el libre comercio: intereses, opciones y negociaciones y Negociaciones agrícolas: estado de situación en la OMC.Correspondiente a la segunda mitad de la década de los 80, este texto plantea las principales características de lo que ya se conocía como "tercera revolución industrial", esto es, la multiplicación y el entrelazamiento cada vez mayor de los servicios con el sistema de producción de bienes, la visibilidad y aumento del conocimiento como fuente de crecimiento económico y poder, y su tratamiento y transmisión a través del complejo electrónico de comunicación que hoy se conoce como tecnologías de la información y la comunicación (las TIC). De un lado, la mayor complejidad e incidencia de los servicios en el aparato productivo de bienes ya hacía, en aquella época, que las empresas tendieran cada vez más a la "terciarización" o externalización de muchas de sus tareas internas. De otro lado, el reconocimiento de que el conocimiento es una entidad inmaterial que se genera socialmente impulsaba, de algún modo, el deseo y la necesidad de su mayor difusión a través de los medios electrónicos. Entre las grandes consecuencias de todo este movimiento histórico mundial se encuentran la nueva configuración de la división internacional del trabajo y la alteración estructural de la producción a escala planetaria (sobre todo con la flexibilización de los procesos productivos, la transnacionalización de la producción y la descentralización de la toma de decisiones). Asimismo, dicha revolución ha puesto en entredicho el papel del Estado-nación en la definición de la política económica y ha servido para cuestionar el planteamiento epistemológico tradicional según el cual habría un conocimiento objetivo y no ideológico, cuestionamiento que ha afectado de manera esencial a las ciencias sociales, y entre ellas, a la economía

    Probing phase coexistence and stabilization of the spin-ordered ferrimagnetic state by Calcium addition in the YBa_{1-x}Ca_{x}Co_{2}O_{5.5} layered cobaltites using neutron diffraction

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    In this article we study the effects of a partial substitution of Ba with the smaller cation Ca in the layered cobaltites YBaCo_2O_{5+\delta} for \delta \approx 0.5. Neutron thermodiffractograms are reported for the compounds YBa_{0.95}Ca_{0.05}Co_2O_{5.5} (x_{Ca}=0.05) and YBa_{0.90}Ca_{0.10}Co_2O_{5.5} (x_{Ca}=0.10) in the temperature range 20 K \leq T \leq 300 K, as well as high resolution neutron diffraction experiments at selected temperatures for the samples x_{Ca}=0.05, x_{Ca}=0.10 and the parent compound x_{Ca}=0. We have found the magnetic properties to be strongly affected by the cationic substitution. Although the "122" perovskite structure seems unaffected by Ca addition, the magnetic arrangements of Co ions are drastically modified: the antiferromagnetic (AFM) long-range order is destroyed, and a ferrimagnetic phase with spin state order is stabilized below T \sim 290 K. For the sample with x_{Ca}=0.05 a fraction of AFM phase coexists with the ferrimagnetic one below T \sim 190 K, whereas for x_{Ca}=0.10 the AFM order is completely lost. The systematic refinement of the whole series has allowed for a better understanding of the observed low-temperature diffraction patterns of the parent compound, YBaCo_2O_{5.5}, which had not yet been clarified. A two-phase scenario is proposed for the x_{Ca}=0 compound which is compatible with the phase coexistence observed in the x_{Ca}=0.05 sample

    Adjuvants : an essential component of neisseria vaccines

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    Adjuvants may be classified into delivery systems and immune potentiator or modulator molecules based on their mechanism of action. Neisseria vaccines containing traditional adjuvants such as aluminium salts have existed for long time, but meningitis caused by Neisseria meningitidis serogroups, particularly serogroup B, continues to be a global health problem. Novel strategies have applied in silico and recombinant technologies to develop "universal" antigens (e.g. proteins, peptides and plasmid DNA) for vaccines, but these antigens have been shown to be poorly immunogenic even when alum adjuvanted, implying a need for better vaccine design. In this work we review the use of natural, detoxified, or synthetic molecules in combination with antigens to activate the innate immune system and to modulate the adaptive immune responses. In the main, antigenic and imune potentiator signals are delivered using nano-, micro-particles, alum, or emulsions. The importance of interaction between adjuvants and antigens to activate and target dendritic cells, the bridge between the innate and adaptive immune systems, will be discussed. In addition, nasal vaccine strategies based on the development of mucosal adjuvants and Neisseria derivatives to eliminate the pathogen at the site of infection provide promising adjuvants effective not only against respiratory pathogens, but also against pathogens responsible for enteric and sexually transmitted diseases

    Conformal polishing approach: Tool footprint analysis

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    Polishing process is one of the most critical manufacturing processes during a metal part production because it determines the final quality of the product. Free-form surface polishing is a handmade process with lots of rejected parts, scrap generation and time and energy consumption. Two different research lines are being developed: prediction models of the final surface quality parameters and an analysis of the amount of material removed depending on the polishing parameters to predict the tool footprint during the polishing task. This research lays the foundations for a future automatic conformal polishing system. It is based on rotational and translational tool with dry abrasive in the front mounted at the end of a robot. A tool to part concept is used, useful for large or heavy workpieces. Results are applied on different curved parts typically used in tooling industry, aeronautics or automotive. A mathematical model has been developed to predict the amount of material removed in function of polishing parameters. Model has been fitted for different abrasives and raw materials. Results have shown deviations under 20% that implies a reliable and controllable process. Smaller amount of material can be removed in controlled areas of a three-dimensional workpiece

    Bibliografía de los peces de agua dulce de la Argentina Suplemento 1996-2002.

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    Between 1981 and 1995, we published five bibliographic lists (López et al., 1981, 1982,1987, 1989 y 1995) that included the publications referred to Argentine freshwater fishes and related general information published since Ringuelet et al. (1967). We included Uruguayan papers until 1989, when it became apparent that our access to those materials was not complete. Other bibliographic collections were published on several subjects (López et al., 1991, 1993, y Ferriz et al., 1998). In the foreword to the 1995 list, López stated that it was difficult to assess the actual usefulness of the lists, since they were seldom quoted in research papers. This consideration, along with the wide success of electronic databases, caused us to discontinue the series, since its only goal had been to increase the knowledge and access to local research papers and foreign publications of interest to local researchers. Regrettably, our experience indicates that access to scientific literature is still, if not difficult, somewhat arbitrary. Apart from that, the continuous work on diverse research lines at División Zoología Vertebrados of Museo de La Plata leads to the accumulation of a multiplicity of information which may be sorted out for the use of others without much difficulty. At present, electronically-supported databases appear as the simplest way to do this. The future will show if this method is more efficient than the preceding one. In this issue we have included papers published between 1996 and 2002; and it is our purpose to update the list on a yearly basis. Papers included cover Argentine fish fauna and some related subjects of more general interest. Naturally, it is hardly surprising that some involuntary omissions will occur when addressing this subject. Any corrections and/or additions will be incorporated in following versions; and all information is most welcome

    Engagement of the PFC in consolidation and recall of recent spatial memory

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    The standard model of system consolidation proposes that memories are initially hippocampus dependent and become hippocampus independent over time. Previous studies have demonstrated the involvement of the medial prefrontal cortex (mPFC) in the retrieval of remote memories. The transformations required to make a memory undergo system's consolidation are thought to require synaptic plasticity. In this study, we investigated the participation of the mitogen-activated protein kinase (MAPK)/ERK pathway in acquisition, memory consolidation, and recent memory recall of the Morris water maze (MWM) task using a 1-d training protocol. To this end, bilateral injections of the MEK inhibitor U0126 into the rat mPFC were performed. The injection of the MEK inhibitor in the mPFC did not affect the acquisition of the MWM. However, MEK inhibitor resulted in impairments on recent memory retrieval either when applied at the end of the learning phase (memory consolidation) or prior to the retention test. The results strongly support the concept that recently acquired and consolidated spatial memories require the mPFC, and that local activation of the MAPK/ERK pathway in the mPFC is necessary for the consolidation and recall of recent memories.Fil: Leon, Wanda C.. McGill University; CanadáFil: Bruno, Martin. McGill University; Canadá. Universidad Nacional de Cuyo; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan; ArgentinaFil: Allard, Simon. McGill University; CanadáFil: Nader, Karim. McGill University; CanadáFil: Cuello, A. Claudio. McGill University; Canad

    Comparison of short-range-order in liquid- and rotator-phase states of a simple molecular liquid: A reverse Monte Carlo and molecular dynamics analysis of neutron diffraction data

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    6 págs.; 6 figs.; 1 tab. ; PACS number s : 61.25.Em, 61.20. p, 61.43. j, 61.12. qThe short-range order (SRO) correlations in liquid- and rotator-phase states of carbon tetrachloride are revisited here. The correlation of some angular magnitudes is used to evaluate the positional and orientational correlations in the liquid as well as in the rotator phase. The results show significant similitudes in the relative position of the molecules surrounding a central one but striking differences in their relative orientations, which could explain the changes in SRO between the two phases and the puzzling behavior of the local density in the liquid and rotator phases. © 2007 The American Physical Society.We would also like to acknowledge “Generalitat de Catalunya” Project No. 2005SGR- 00535 and MEC Project No. FIS2005-00975 for partial support of this work.Peer Reviewe
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