998 resultados para Previous cesarean section
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Patients affected with intra-thoracic recurrences of primary or secondary lung malignancies after a first course of definitive radiotherapy have limited therapeutic options, and they are often treated with a palliative intent. Re-irradiation with stereotactic ablative radiotherapy (SABR) represents an appealing approach, due to the optimized dose distribution that allows for high-dose delivery with better sparing of organs at risk. This strategy has the goal of long-term control and even cure. Aim of this review is to report and discuss published data on re-irradiation with SABR in terms of efficacy and toxicity. Results indicate that thoracic re-irradiation may offer satisfactory disease control, however the data on outcome and toxicity are derived from low quality retrospective studies, and results should be cautiously interpreted. As SABR may be associated with serious toxicity, attention should be paid for an accurate patients' selection.
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We provide robust and compelling evidence of the marked impact of tertiary education on the economic growth of less developed countries and of its the relatively smaller impact on the growth of developed ones. Our results argue in favor of the accumulation of high skill levels especially in technologically under-developed countries and, contrary to common wisdom, independently of the fact that these economies might initially produce lower-technology goods or perform technology imitation. Our results are robust to the different measures used in proxying human capital and to the adjustments made for cross-country differences in the quality of education. Country-specific institutional quality, as well as other indicators including legal origin, religious fractionalization and openness to trade have been used to control for the robustness of the results. These factors are also shown to speed up technology convergence thereby confirming previous empirical studies. Our estimates tackle problems of endogeneity by adopting a variety of techniques, including instrumental variables -for both panel and cross-section analyses- and the two-step efficient dynamics system GMM.
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This dissertation is based on four articles dealing with modeling of ozonation. The literature part of this considers some models for hydrodynamics in bubble column simulation. A literature review of methods for obtaining mass transfer coefficients is presented. The methods presented to obtain mass transfer are general models and can be applied to any gas-liquid system. Ozonation reaction models and methods for obtaining stoichiometric coefficients and reaction rate coefficients for ozonation reactions are discussed in the final section of the literature part. In the first article, ozone gas-liquid mass transfer into water in a bubble column was investigated for different pH values. A more general method for estimation of mass transfer and Henry’s coefficient was developed from the Beltrán method. The ozone volumetric mass transfer coefficient and the Henry’s coefficient were determined simultaneously by parameter estimation using a nonlinear optimization method. A minor dependence of the Henry’s law constant on pH was detected at the pH range 4 - 9. In the second article, a new method using the axial dispersion model for estimation of ozone self-decomposition kinetics in a semi-batch bubble column reactor was developed. The reaction rate coefficients for literature equations of ozone decomposition and the gas phase dispersion coefficient were estimated and compared with the literature data. The reaction order in the pH range 7-10 with respect to ozone 1.12 and 0.51 the hydroxyl ion were obtained, which is in good agreement with literature. The model parameters were determined by parameter estimation using a nonlinear optimization method. Sensitivity analysis was conducted using object function method to obtain information about the reliability and identifiability of the estimated parameters. In the third article, the reaction rate coefficients and the stoichiometric coefficients in the reaction of ozone with the model component p-nitrophenol were estimated at low pH of water using nonlinear optimization. A novel method for estimation of multireaction model parameters in ozonation was developed. In this method the concentration of unknown intermediate compounds is presented as a residual COD (chemical oxygen demand) calculated from the measured COD and the theoretical COD for the known species. The decomposition rate of p-nitrophenol on the pathway producing hydroquinone was found to be about two times faster than the p-nitrophenol decomposition rate on the pathway producing 4- nitrocatechol. In the fourth article, the reaction kinetics of p-nitrophenol ozonation was studied in a bubble column at pH 2. Using the new reaction kinetic model presented in the previous article, the reaction kinetic parameters, rate coefficients, and stoichiometric coefficients as well as the mass transfer coefficient were estimated with nonlinear estimation. The decomposition rate of pnitrophenol was found to be equal both on the pathway producing hydroquinone and on the path way producing 4-nitrocathecol. Comparison of the rate coefficients with the case at initial pH 5 indicates that the p-nitrophenol degradation producing 4- nitrocathecol is more selective towards molecular ozone than the reaction producing hydroquinone. The identifiability and reliability of the estimated parameters were analyzed with the Marcov chain Monte Carlo (MCMC) method. @All rights reserved. No part of the publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior permission of the author.
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Statistics show that the expanding service sector accounts already for three quarters of GDP in the developed economies. Moreover, there is abundant evidence on high variation in productive performance across the service industries. This suggests divergent technological and institutional trajectories within the tertiary sector. While conceptual knowledge on services and their performance has accumulated substantially, the overall landscape on productivity and competitiveness is still inconclusive. As noted by number of authors the research on service productivity is still in its infancy. The purpose of this paper is to develop further the analytical framework of service productivity. The approach is based on the notion that service definitions, classifications and performance measurement are strongly interdependent. Given the ongoing restructuring of businesses activities with higher information content, it is argued that the dichotomy between manufacturing and services should not be taken too far. Industrial evolution also suggests that the official industry classifications are increasingly outdated and new taxonomies for empirical research are therefore needed. Based on the previous analyses and new insights the paper clarifies the debated concept of service productivity and identifies the critical dimensions by which the service industries cluster. It is also demonstrated that the dimensions enable to construct new service taxonomies which bear essentially on productivity opportunities at the business level. Needles to say the key determinant explaining the development and potential of productivity growth is innovation activity. As an extensive topic of research, however, service innovation is tackled here only in a cursory way. The paper is constructed as follows: the first section focuses on the conceptual issues and evolving nature of service activities. A workable definition of service should capture the diversity of service activities, as well as the aspects of service processes, comprehensively. The distinctions and similarities between services and manufacturing are discussed, too. Section 2 deals with the service productivity, a persistent and controversial issue in academic literature and policy. With the assessments of strengths and weaknesses of the main schools new insights based on value creation will be brought in. Industry classifications and taxonomies are discussed in Section 3. It begins with a short analysis of the official classifications and their evaluation from the perspective of empirical research. Using well-known examples it is shown that the taxonomies on the manufacturing industries have a clear analogy with the business services. As there is a growing interest to regroup services too, the work to date, has been less systematic and inherently qualitative. Based on the earlier contributions threedimensional service taxonomy is constructed which highlight the key dimensions of productive performance. The main findings and implications are summed up in Section 4.
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1826 (T5).
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1824 (T2).
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Variante(s) de titre : Bulletin universel des sciences et de l'industrie. 4e section, Sciences agricoles et économiques
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1826 (T6).
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1825 (T3).
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1825 (T4).
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1827 (T7).
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1827 (T8).
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1824 (T1).
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1926/12 (N2).
