[Review of] Edith Blicksilver. The Ethnic American Woman; Problems, Protests, Lifestyle

Edith Blicksilver has compiled an extensive and varied series of articles, poems and narratives of personal experiences of the different female authors, covering the life spectrum of the Ethnic American Woman. They are presented in a logical and organized fashion, which provides structure but allows for flexibility in the themes. This adds to the enjoyment of the book and facilitates its reading

A Profit Efficiency Perspective on the Future Strategic Positioning of the Portuguese Banks

The Portuguese banking sector has been recently subjected to important structural changes. The diversification of the supply of financial services, the specialization phenomena and the growing importance of new technologies are changing the sector dramatically. A profit perspective is used to investigate the efficiency performance of the commercial banking sector in Portugal in the period 2000-2004 and infer some implications for the banks´ management strategic orientation. The Nerlovian and an alternative profit efficiency measures are used, illustrating the potentialities of the directional distance functions to the profit efficiency analysis. A decomposition of the alternative profit efficiency measure is also proposed.Banking; Nerlovian profit efficiency; alternative profit efficiency; directional distance functions

A stochastic production frontier model with a translog specification using the generalized maximum entropy estimator

In this paper, an empirical application of the generalized maximum entropy estimator in a stochastic production frontier model with a translog specification is discussed to investigate technical efficiency in a wine region of Portugal. The empirical results indicate technical progress over the time period of the sample and an increasing technical inefficiency over time. All production units are technically inefficient, although wine cooperatives are less inefficient than private firms.stochastic frontier analysis, generalized maximum entropy, technical efficiency, translog

AJAE Appendix: Dynamic Efficiency Measurement: Theory and Application

The material contained herein is supplementary to the article named in the title and published in the American Journal of Agricultural Economics, May 2007, Volume 89, Issue 2.Productivity Analysis,

Dynamic Efficiency Analysis using a Directional Distance Function

Input-based dynamic efficiency measures are derived from an adjustment-cost directional distance function approach. A dynamic input directional distance function can be generated from an adjustment-cost technology where the dynamics are explicitly incorporated in the form of the properties of the input requirement sets with respect to the quasi-fixed factors. The properties of the dynamic input directional distance function are inherited from the properties of the technology. The efficiency measures are then applied to a panel data set of Dutch horticulture firms over the period 1991-1995.Productivity Analysis,

Animals’ Health Control Efficiency in Northwest Portugal: A Two-stage DEA Approach

A two-stage approach is employed to analyze the efficiency of cooperatives responsible for ruminants’ disease control (OPP) at the farm level in Northwest Portugal. In the first stage, Data Envelopment Analysis (DEA) is used to estimate and decompose input-based overall inefficiency for each OPP. The input-based inefficiency measures are generated using the directional input distance function. In the second stage, the inefficiency estimates are regressed on environmental and organizational factors in order to explain efficiency differentials. Despite substantial environmental differences, the empirical results indicate that most cooperatives can reduce costs by improving scale efficiency and pure technical efficiency.input directional distance function, bootstrapping, economic efficiency, animal health services., Agricultural and Food Policy,

Contribution au pronostic de durée de vie des systèmes piles à combustible PEMFC

This thesis work aims to provide solutions for the limited lifetime of Proton Exchange Membrane Fuel Cell Systems (PEM-FCS) based on two complementary disciplines:A first approach consists in increasing the lifetime of the PEM-FCS by designing and implementing a Prognostics & Health Management (PHM) architecture. The PEM-FCS are essentially multi-physical systems (electrical, fluid, electrochemical, thermal, mechanical, etc.) and multi-scale (time and space), thus its behaviors are hardly understandable. The nonlinear nature of phenomena, the reversibility or not of degradations and the interactions between components makes it quite difficult to have a failure modeling stage. Moreover, the lack of homogeneity (actual) in the manufacturing process makes it difficult for statistical characterization of their behavior. The deployment of a PHM solution would indeed anticipate and avoid failures, assess the state of health, estimate the Remaining Useful Lifetime (RUL) of the system and finally consider control actions (control and/or maintenance) to ensure operation continuity.A second approach proposes to use a passive hybridization of the PEMFC with Ultra Capacitors (UC) to operate the fuel cell closer to its optimum operating conditions and thereby minimize the impact of aging. The UC appear as an additional source to the PEMFC due to their high power density, their capacity to charge/discharge rapidly, their reversibility and their long life. If we take the example of fuel cell hybrid electrical vehicles, the association between a PEMFC and UC can be performed using a hybrid of active or passive type system. The overall behavior of the system depends on both, the choice of the architecture and the positioning of these elements in connection with the electric charge. Today, research in this area focuses mainly on energy management between the sources and embedded storage and the definition and optimization of a power electronic interface designated to adjust the flow of energy between them. However, the presence of power converters increases the source of faults and failures (failure of the switches of the power converter and the impact of high frequency current oscillations on the aging of the PEMFC), and also increases the energy losses of the entire system (even if the performance of the power converter is high, it nevertheless degrades the overall system).Les travaux de cette thèse visent à apporter des éléments de solutions au problème de la durée de vie des systèmes pile à combustible (FCS – Fuel Cell System) de type à « membrane échangeuse de protons » (PEM – Proton Exchange Membrane) et se décline sur deux champs disciplinaires complémentaires :Une première approche vise à augmenter la durée de vie de celle-ci par la conception et la mise en œuvre d'une architecture de pronostic et de gestion de l'état de santé (PHM – Prognostics & Health Management). Les PEM-FCS, de par leur technologie, sont par essence des systèmes multi-physiques (électriques, fluidiques, électrochimiques, thermiques, mécaniques, etc.) et multi-échelles (de temps et d'espace) dont les comportements sont difficilement appréhendables. La nature non linéaire des phénomènes, le caractère réversible ou non des dégradations, et les interactions entre composants rendent effectivement difficile une étape de modélisation des défaillances. De plus, le manque d'homogénéité (actuel) dans le processus de fabrication rend difficile la caractérisation statistique de leur comportement. Le déploiement d'une solution PHM permettrait en effet d'anticiper et d'éviter les défaillances, d'évaluer l'état de santé, d'estimer le temps de vie résiduel du système, et finalement, d'envisager des actions de maîtrise (contrôle et/ou maintenance) pour assurer la continuité de fonctionnement. Une deuxième approche propose d'avoir recours à une hybridation passive de la PEMFC avec des super-condensateurs (UC – Ultra Capacitor) de façon à faire fonctionner la pile au plus proche de ses conditions opératoires optimales et ainsi, à minimiser l'impact du vieillissement. Les UCs apparaissent comme une source complémentaire à la PEMFC en raison de leur forte densité de puissance, de leur capacité de charge/décharge rapide, de leur réversibilité et de leur grande durée de vie. Si l'on prend l'exemple des véhicules à pile à combustible, l'association entre une PEMFC et des UCs peut être réalisée en utilisant un système hybride de type actif ou passif. Le comportement global du système dépend à la fois du choix de l'architecture et du positionnement de ces éléments en lien avec la charge électrique. Aujourd'hui, les recherches dans ce domaine se focalisent essentiellement sur la gestion d'énergie entre les sources et stockeurs embarqués ; et sur la définition et l'optimisation d'une interface électronique de puissance destinée à conditionner le flux d'énergie entre eux. Cependant, la présence de convertisseurs statiques augmente les sources de défaillances et pannes (défaillance des interrupteurs du convertisseur statique lui-même, impact des oscillations de courant haute fréquence sur le vieillissement de la pile), et augmente également les pertes énergétiques du système complet (même si le rendement du convertisseur statique est élevé, il dégrade néanmoins le bilan global)

An attempt to explain differences in economic growth: a stochastic frontier approach

Total factor productivity (TFP), factor accumulation, and growth are analysed for a panel of 40 countries in 2001–11. TFP growth and technical inefficiency are estimated using a stochastic frontier model. Environmental variables are found to have an important role in explaining differences in inefficiency across countries. Over 2001–11, the general improvement in technical efficiency of countries is almost outweighed by technological regress. Results indicate that differences in factor accumulation between OECD and emerging economies are more important than differences in TFP change to explain differences in economic growth. Results also indicate negative and significant random shocks for the OECD countries.info:eu-repo/semantics/acceptedVersio

Maximum entropy: a stochastic frontier approach for electricity distribution regulation

The literature on incentive-based regulation in the electricity sector indicates that the size of this sector in a country constrains the choice of frontier methods as well as the model specification itself to measure economic efficiency of regulated firms. The aim of this study is to propose a stochastic frontier approach with maximum entropy estimation, which is designed to extract information from limited and noisy data with minimal statements on the data generation process. Stochastic frontier analysis with generalized maximum entropy and data envelopment analysis – the latter one has been widely used by national regulators – are applied to a cross-section data on thirteen European electricity distribution companies. Technical efficiency scores and rankings of the distribution companies generated by both approaches are sensitive to model specification. Nevertheless, the stochastic frontier analysis with generalized maximum entropy results indicate that technical efficiency scores have similar distributional properties and these scores as well as the rankings of the companies are not very sensitive to the prior information. In general, the same electricity distribution companies are found to be in the highest and lowest efficient groups, reflecting weak sensitivity to the prior information considered in the estimation procedure.publishe

Becoming a teacher: The first year of work for teachers in Early Childhood Education

This article presents the results of the research about the most teaching problems for the graduates of Early Childhood Education of Universidad Pedagógica Nacional of Colombia, during their first year of work like teachers. It describes and analyzes the problems in the personal, didactic, institutional and social levels. Being the institutional trouble in which they feel the biggest problems by the pedagogical approaches confrontation of both public and private organizations; as well as, to the conflicts in the relation with the institution parents . The above leads to reflect on the need to accompany the beginning teachers in their first working year, because this will constitute many of its future ways of working and points of views of the same problems