327 research outputs found

    Lucha contra la pobreza en América Latina: ¿Selectividad y universalismo?

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    La ineficacia de las estrategias del bienestar en América Latina basadas exclusivamente en la extensión de los derechos contributivos ha auspiciado nuevas discusiones sobre la selectividad y el universalismo en la provisión de políticas sociales. La puesta en vigor de programas de lucha contra la pobreza mediante comprobación de recursos de los beneficiarios (programas de transferencias de rentas condicionadas) es objeto de examen y valoración en la ponencia. Se discute si tal selectividad favorece un universalismo básico, y si los programas de comprobación de recursos pueden ser transformados eventualmente en políticas de prestaciones universales

    Поиск фрагмента изображения с использованием нейронной сети Кохонена

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    This paper considers the ability to sample on a series of images using Kohonen neural network, analyzing the distribution of basic colors. Objective is to improve the quality and speed of search for fragments of the image by creating software that performs clustering colors images

    Разработка рекомендаций по предупреждению осложнений при бурении скважин в различных геолого-технических условиях

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    Объектом исследования являются методы предупреждения осложнений при бурении скважин в различных горно-геологических условиях. Цель работы разработка рекомендаций по предупреждению осложнений. В процессе работы был проведен анализ и систематизация накопленного в данной области опыта, разработок и исследований. В результате работы была разработана классификация технических, технологических и организационных мер предупреждения осложнений при бурении.The object of the study is the methods of preventing complications when drilling wells in various mining and geological conditions. The purpose of the work is to develop recommendations for the prevention of complications. In the course of the work, the analysis and systematization of the accumulated experience, developments and research in this area was carried out. As a result of the work, a classification of technical, technological and organizational measures to prevent complications during drilling was developed

    Inequality restricted and pre-test estimation in a mis-specified econometric model

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    This thesis is concerned with the finite sample properties of some estimators of the unknown parameters in a linear model which is (possibly) mis-specified through the exclusion of relevant regressors. We assume that in addition to sample information, prior information regarding the unknown parameters is available in the form of a linear inequality constraint imposed on the regression coefficients. The combination of this type of prior information and sample information in specifying the corresponding statistical model leads to what has been identified in the literature as the inequality restricted estimator. If the statistical significance of the inequality constraint is tested prior to the estimation process, then the estimator thereby generated is called the inequality pre-test estimator. The properties of these estimators of the coefficient vector in a properly specified model have been examined rather thoroughly in the literature. In this thesis, we extend the results reported in the literature to the case where the underlying regression model is underfitted. We also investigate the sampling performance of the corresponding estimators for the model's disturbance variance, as well as the choice of an optimal size for the pre-test. The general background and motivation for this study are given in Chapter 1. Much of the earlier research on inequality restricted and pre-test estimation are built on results from studies that assume that the prior information is in the form of linear equality restrictions. We survey the relevant literature in this area in Chapter 2. Chapter 3 reviews the literature on inequality restricted and pre-test estimation. We focus on this problem in the context of the standard linear model with a single linear inequality constraint on the coefficient vector, as this is directly related to the theme of this thesis. In Chapter 4, we derive and evaluate the risk, under quadratic loss, of the inequality restricted and pre-test estimators for the regression prediction vector in an underfitted model. This analysis takes the established literature further by allowing for mis-specification in the regressor matrix. We consider the risk of the prediction vector, rather than the coefficient vector itself, so that our results are data independent. The risk functions of the corresponding estimators for the regression disturbance variance in the properly specified and underfitted models are derived in Chapters 6 and 7 respectively. As in the case where the prior information exists as linear equality restrictions, our results show that when the model is underfitted, the use of valid prior information does not necessarily guarantee a reduction in risk. This result holds for the estimation of both the prediction vector and the scale parameter. When one is estimating the regression disturbance variance, with an appropriate choice of test size, the inequality pre-test estimator can uniformly dominate the estimator that uses sample information only. We also find that the risk functions of the estimators of the error variance are affected more by mis-specification than are the corresponding predictive risks. In the case where no strictly dominating estimator exists, the question of the choice of an optimal critical value of the pre-test remains. Chapters 5 and 8 explore this issue when one is estimating the prediction vector and scale parameter respectively. We find that most of our results concur qualitatively with those reported in the literature when the prior information exists as exact equality restrictions. Chapter 9 contains some concluding remarks and a summary of the major results obtained in earlier chapters. We also outline some possible future research topics in this general area

    Equipment and methods for measuring reflectance of concentrating solar reflector materials

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    The proper optical characterization of solar reflector materials is a challenging task. Although several commercial instruments exist to measure reflectance, they have been developed for other applications and often do not meet all the specific requirements demanded by the solar thermal industry. In particular, the characterization of solar reflectors involve the complete solar spectral wavelength range, an incidence angle range from near normal to 70° and most importantly a very narrow acceptance angle range from near specular to 20 mrad. The accurate measurement of reflectance as a function of all the previously mentioned parameters has not been commercially implemented. This paper reviews the different alternatives to measure reflector materials, describes reflectance models used to approximate the missing information and presents current research work on prototype reflectometers to fill the gap

    Equipment and methods for measuring reflectance of concentrating solar reflector materials

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    The proper optical characterization of solar reflector materials is a challenging task. Although several commercial instruments exist to measure reflectance, they have been developed for other applications and often do not meet all the specific requirements demanded by the solar thermal industry. In particular, the characterization of solar reflectors involve the complete solar spectral wavelength range, an incidence angle range from near normal to 70° and most importantly a very narrow acceptance angle range from near specular to 20 mrad. The accurate measurement of reflectance as a function of all the previously mentioned parameters has not been commercially implemented. This paper reviews the different alternatives to measure reflector materials, describes reflectance models used to approximate the missing information and presents current research work on prototype reflectometers to fill the gap

    Immune-profiling of innate and adaptive immunity following three vaccinations of the MERS vaccine candidate MVA-MERS-S

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    Middle East Respiratory Syndrome (MERS) is a respiratory disease caused by MERS coronavirus (MERS-CoV). In follow-up to a phase 1 trial, we performed a longitudinal analysis of immune responses following immunization with the Modified Vaccinia virus Ankara (MVA)-based vaccine MVA-MERS-S encoding MERS-CoV-spike protein. Three homologous intramuscular immunizations were administered on days 0 and 28 with a late booster vaccination at 12±4 months. Vaccination with MVA-MERS-S revealed a benign safety profile. No serious or severe adverse events were reported. Here, we analyzed innate and adaptive immune responses to the MVA-MERS-S in ten vaccinees. For this approach, blood samples were collected frequently for a period of about three years. Serum, plasma and PBMCs were analyzed at multiple time points using different techniques, which allowed an in-depth characterization of immune responses elicited by MVA-MERS-S. Please click Download on the upper right corner to see the full abstract

    Myo/Nog cell regulation of bone morphogenetic protein signaling in the blastocyst is essential for normal morphogenesis and striated muscle lineage specification

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    AbstractCells that express MyoD mRNA, the G8 antigen and the bone morphogenetic protein (BMP) inhibitor noggin (Nog) are present in the epiblast before gastrulation. Ablation of “Myo/Nog” cells in the blastocyst results in an expansion of canonical BMP signaling and prevents the expression of noggin and follistatin before and after the onset of gastrulation. Once eliminated in the epiblast, they are neither replaced nor compensated for as development progresses. Older embryos lacking Myo/Nog cells exhibit severe axial malformations. Although Wnts and Sonic hedgehog are expressed in ablated embryos, skeletal muscle progenitors expressing Pax3 are missing in the somites. Pax3+ cells do emerge adjacent to Wnt3a+ cells in vitro; however, few undergo skeletal myogenesis. Ablation of Myo/Nog cells also results in ectopically placed cardiac progenitors and cardiomyocytes in the somites. Reintroduction of Myo/Nog cells into the epiblast of ablated embryos restores normal patterns of BMP signaling, morphogenesis and skeletal myogenesis, and inhibits the expression of cardiac markers in the somites. This study demonstrates that Myo/Nog cells are essential regulators of BMP signaling in the early epiblast and are indispensable for normal morphogenesis and striated muscle lineage specification

    Identification of a Spike-Specific CD8<sup>+</sup> T-Cell Epitope Following Vaccination Against the Middle East Respiratory Syndrome Coronavirus in Humans

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    Licensed vaccines against the Middle East respiratory syndrome coronavirus (MERS-CoV), an emerging pathogen of concern, are lacking. The modified vaccinia virus Ankara vector-based vaccine MVA-MERS-S, expressing the MERS-CoV-spike glycoprotein (MERS-S), is one of 3 candidate vaccines in clinical development and elicits robust humoral and cellular immunity. Here, we identified for the first time a MERS-S-specific CD8+ T-cell epitope in an HLA-A∗03:01/HLA-B∗35:01-positive vaccinee using a screening assay, intracellular cytokine staining, and in silico epitope prediction. As evidence from MERS-CoV infection suggests a protective role of long-lasting CD8+ T-cell responses, the identification of epitopes will facilitate longitudinal analyses of vaccine-induced T-cell immunity.</p
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