916 resultados para over-generalization and under-generalization problems


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Differences in physico-chemical characteristics of bone grafts to fill bone defects have been demonstrated to influence in vitro bacterial biofilm formation. Aim of the study was to investigate in vivo staphylococcal biofilm formation on different calcium phosphate bone substitutes. A foreign-body guinea-pig infection model was used. Teflon cages prefilled with β-tricalcium phosphate, calcium-deficient hydroxyapatite, or dicalcium phosphate (DCP) scaffold were implanted subcutaneously. Scaffolds were infected with 2 × 10(3) colony-forming unit of Staphylococcus aureus (two strains) or S. epidermidis and explanted after 3, 24 or 72 h of biofilm formation. Quantitative and qualitative biofilm analysis was performed by sonication followed by viable counts, and microcalorimetry, respectively. Independently of the material, S. aureus formed increasing amounts of biofilm on the surface of all scaffolds over time as determined by both methods. For S. epidermidis, the biofilm amount decreased over time, and no biofilm was detected by microcalorimetry on the DCP scaffolds after 72 h of infection. However, when using a higher S. epidermidis inoculum, increasing amounts of biofilm were formed on all scaffolds as determined by microcalorimetry. No significant variation in staphylococcal in vivo biofilm formation was observed between the different materials tested. This study highlights the importance of in vivo studies, in addition to in vitro studies, when investigating biofilm formation of bone grafts.

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In experiments with two-person sequential games we analyzewhether responses to favorable and unfavorable actions dependon the elicitation procedure. In our hot treatment thesecond player responds to the first player s observed actionwhile in our cold treatment we follow the strategy method and have the second player decide on a contingent action foreach and every possible first player move, without firstobserving this move. Our analysis centers on the degree towhich subjects deviate from the maximization of their pecuniaryrewards, as a response to others actions. Our results show nodifference in behavior between the two treatments. We also findevidence of the stability of subjects preferences with respectto their behavior over time and to the consistency of theirchoices as first and second mover.

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This paper addresses three questions: (1) why does the share of skilledworkers in regional population tend to be higher in wealthier regions? (2)what determines changes in this share over time? and (3) why is it that internalmigration tends to raise average skill levels of the receiving regions relativeto that of the sending regions? I construct a two--region dynamic model withagglomeration and congestion to answer these questions. It is shown that,under certain relationship between wages and demand for land, unskilledworkers are discouraged more strongly from living in a wealthier region andare less mobile than skilled workers.

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By introducing physical outcomes in coalitional games we note that coalitional games and social choice problems are equivalent (implying that so are the theory of implementation and the Nash program). This facilitates the understanding of the role of invariance and randomness in the Nash program. Also, the extent to which mechanisms in the Nash program perform ``real implementation'' is examined.

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This paper estimates a translog stochastic frontier production function in the analysis of all 48 contiguous U.S. states in the period 1970-1983, to attempt to measure and explain changes in technical efficiency. The model allows technical inefficiency to vary over time, and inefficiency effects to be a function of a set of explanatory variables in which the level and composition of public capital plays an important role. Results indicated that U.S. state inefficiency levels were significantly and positively correlated with the ratio of public capital to private capital. The proportion of public capital devoted to highways is negatively correlated with technical inefficiency, suggesting that not only the level but also the composition of public capital influenced state efficiency.

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An important policy issue in recent years concerns the number of people claimingdisability benefits for reasons of incapacity for work. We distinguish between workdisability , which may have its roots in economic and social circumstances, and healthdisability which arises from clear diagnosed medical conditions. Although there is a linkbetween work and health disability, economic conditions, and in particular the businesscycle and variations in the risk of unemployment over time and across localities, mayplay an important part in explaining both the stock of disability benefit claimants andinflows to and outflow from that stock. We employ a variety of cross?country andcountry?specific household panel data sets, as well as administrative data, to testwhether disability benefit claims rise when unemployment is higher, and also toinvestigate the impact of unemployment rates on flows on and off the benefit rolls. Wefind strong evidence that local variations in unemployment have an importantexplanatory role for disability benefit receipt, with higher total enrolments, loweroutflows from rolls and, often, higher inflows into disability rolls in regions and periodsof above?average unemployment. Although general subjective measures of selfreporteddisability and longstanding illness are also positively associated withunemployment rates, inclusion of self?reported health measures does not eliminate thestatistical relationship between unemployment rates and disability benefit receipt;indeed including general measures of health often strengthens that underlyingrelationship. Intriguingly, we also find some evidence from the United Kingdom and theUnited States that the prevalence of self?reported objective specific indicators ofdisability are often pro?cyclical that is, the incidence of specific forms of disability arepro?cyclical whereas claims for disability benefits given specific health conditions arecounter?cyclical. Overall, the analysis suggests that, for a range of countries and datasets, levels of claims for disability benefits are not simply related to changes in theincidence of health disability in the population and are strongly influenced by prevailingeconomic conditions. We discuss the policy implications of these various findings.

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This chapter highlights the problems that structural methods and SVAR approaches have when estimating DSGE models and examining their ability to capture important features of the data. We show that structural methods are subject to severe identification problems due, in large part, to the nature of DSGE models. The problems can be patched up in a number of ways but solved only if DSGEs are completely reparametrized or respecified. The potential misspecification of the structural relationships give Bayesian methods an hedge over classical ones in structural estimation. SVAR approaches may face invertibility problems but simple diagnostics can help to detect and remedy these problems. A pragmatic empirical approach ought to use the flexibility of SVARs against potential misspecificationof the structural relationships but must firmly tie SVARs to the class of DSGE models which could have have generated the data.

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Aging is a multidimensional process of physical, psychological, and social changes. Understanding how we sleep and how this dynamic process evolves across life span will help to identify normal developmental aspects of sleep over time and to create strategies to increase awareness of sleep disturbances and their early management. In normal sleepers from HypnoLaus cohort, we evaluated the effects of age and gender on both subjective and objective sleep measurements. Our results indicate that normal aging is not accompanied by sleep complaints, and when they exist suggest the presence of underlying comorbidities. Polysomnographic data revealed that slow wave sleep was more affected with age in men, and age affected differently NREM and REM spectral power densities. Both sleep structure and spectral analysis profiles may constitute standards to delineate pathological changes in sleep, both for aging women and men. Another important aspect in the management of sleep and its disorders is a detailed characterization of sleep-inducing medications. Gamma-hydroxybutyrate (GHB) is an inhibitory neurotransmitter derivative of GABA, but its mode of action and the range of effects are not well understood. Several properties, as growth hormone stimulation in humans and the development of weight loss in treated patients suggest an unexplored metabolic effect. In different experiments we assessed the effects of acute, short term and chronic GHB administration on central (cerebral cortex) and peripheral (liver) biochemical processes involved in the metabolism of the drug, as well as the effects of the drug on metabolism in C57BL/6J, GABAB knock-out and obese (ob/ob) mice. We showed that GHB treatment affects weight gain in C57BL/6J and GABAB knock-out mice. Metabolomic analysis indicated large central and peripheral metabolic changes induced by GHB with important relevance to its therapeutic use. -- Le vieillissement est un processus multidimensionnel accompagné par de multiples changements dans les domaines physique, psychologique et social. Comprendre comment nous dormons et comment ce processus dynamique évolue sur la durée de vie nous aidera à identifier les aspects normaux du développement du sommeil au fil du temps, et à créer des stratégies pour accroître la connaissance et compréhension des troubles du sommeil et leur prise en charge précoce. Chez les sujets normaux de la cohorte HypnoLaus nous avons évalué les effets de l'âge et du sexe sur les mesures subjectives et objectives du sommeil. Nos résultats indiquent que le vieillissement normal ne s'accompagne pas de troubles du sommeil, et quand ils existent ceux-ci suggèrent la présence de comorbidités sous-jacentes. Les données polysomnographiques ont révélé que le sommeil profond était plus affecté avec l'âge chez les hommes. De plus, nous avons montré comment l'âge modifie la composition spectrale du sommeil lent et paradoxal. La structure du sommeil et les profils d'analyse spectrale peuvent donc constituer des standards permettant de définir les changements pathologiques du sommeil chez les personnes âgées. Parmi les aspects importants de la gestion du sommeil et de ses troubles, la caractérisation détaillée des médicaments hypnotiques utilisés est essentielle. L'acide gamma-hydroxybutyrique (GHB) est un acide gras à courte chaîne dérivé du GABA, principal neurotransmetteur inhibiteur du cerveau, mais son mode d'action et tous ses effets sont toujours largement méconnus. Plusieurs propriétés, comme la stimulation de la sécrétion de l'hormone de croissance chez l'homme et le développement d'une perte de poids chez les patients traités suggèrent un effet métabolique inexploré. Dans différentes expériences, nous avons évalué les effets d'une exposition aiguë, à court terme et chronique de GHB sur les processus biochimiques centraux (cortex cérébral) et périphériques (foie) impliqués dans le métabolisme du médicament. Nous avons aussi évalué les effets du médicament sur le métabolisme des souris C57BL/6J, GABAB KO et obèses (ob/ob). Nos résultats ont montré que le GHB diminue le gain de poids chez les souris C57BL/6J et GABAB KO. L'analyse métabolomique a indiqué des changements importants induits par GHB au niveau central et périphérique, et ces effets sont importants pour son utilisation thérapeutique.

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In this study, drosophilids that bred in fruits of three common plant species of the Brazilian Savanna were investigated: Emmotum nitens, Hancornia speciosa and Anacardium humile, along with the temporal and spatial distribution of these insects among fruits obtained from six individuals of E. nitens. Fallen fruits were collected in natural environments, placed on moist sand in individual containers and all drosophilids that emerged from these resources during 15 days were collected, counted and identified. From 3,651 fruits collected (3,435 of E. nitens, 179 of A. humile and 37 of H. speciosa) 4,541 flies emerged and were classified into 19 species of Drosophilidae. Their distribution was unequal among the three resources, also over time, and among the six individuals of E. nitens. Such fluctuations probably reflect the availability of resources in time and space and probably the action of selective factors such as larval competition.

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Cape Verde is considered part of Sahelian Africa, where drought and desertification are common occurrences. The main activity of the rural population is rain-fed agriculture, which over time has been increasingly challenged by high temporal and spatial rainfall variability, lack of inputs, limited land area, fragmentation of land, steep slopes, pests, lack of mechanization and loss of top soil by water erosion. Human activities, largely through poor farming practices and deforestation (Gomez, 1989) have accelerated natural erosion processes, shifting the balance between soil erosion and soil formation (Norton, 1987). According to previous studies, vegetation cover is one of the most important factors in controlling soil loss (Cyr et al., 1995; Hupy, 2004; Zhang et al., 2004; Zhou et al., 2006). For this reason, reforestation is a touchstone of the Cape Verdean policy to combat desertification. After Independence in 1975, the Cape Verde government had pressing and closely entangled environmental and socio-economic issues to address, as long-term desertification had resulted in a lack of soil cover, severe soil erosion and a scarcity of water resources and fuel wood. Across the archipelago, desertification was resulting from a variety of processes including poor farming practices, soil erosion by water and wind, soil and water salinity in coastal areas due to over pumping and seawater intrusion, drought and unplanned urbanization (DGA-MAAP, 2004). All these issues directly affected socio-economic vulnerability in rural areas, where about 70% of people depended directly or indirectly on agriculture in 1975. By becoming part of the Inter- State Committee for the Fight against Drought in the Sahel in 1975, the government of Cape Verde gained structured support to address these issues more efficiently. Presentday policies and strategies were defined on the basis of rational use of resources and human efforts and were incorporated into three subsequent national plans: the National Action Plan for Development (NDP) (1982–1986), the NDP (1986–1990) and the NDP (1991–1995) (Carvalho

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This paper explains why trade liberalizations occur in developing countries,and why they are often reversed. It does so by focusing on the use oflobbying for protection by import competing firms as a means to postponecostly product quality upgrades to keep up with foreign competitors. Giventhe availability of a political market for import tariffs, domestic firmswill lobby for a sequence of tariffs that insulate domestic profits from awidening quality gap, thereby allowing adjustment to be postponed. But asthe contributions required by the government grow with the size of thequality gap, it will be optimal to adjust quality and to decrease thelobbying effort at some time, leading to liberalization and technologicalcatch-up. But then the equilibrium tariff will again be small and "cheap",and it will pay to start lobbying anew, until the next quality adjustment.Therefore, cycles in protection will occur as a result of the use oflobbying as a substitute for innovation. The model thus sheds new light onthe impact of the costs of protection on the effectiveness of the lobbyingeffort over time, and on their implications for the timing and the timehorizon of trade reforms in developing countries.

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The kidney is a key organ in the maintenance of ion and fluid homeostasis and specific transport systems localized along the nephron guarantee this function. Due to its large functional heterogeneity, experiments on the whole organ level cannot be easily performed, and thus more refined tools are needed, like for example the development of specific recombination systems to gain knowledge on the physiological role of single proteins implicated in ion transport. This review introduces the transgenic technology developed over the past decades, and then focuses on recent strategies for generating kidney-specific gene targeting, over-expression, and gene ablation in mice, that will help to understand the physiological role of proteins implicated in salt and water balance in the kidney.

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The traditionally coercive and state-controlled governance of protected areas for nature conservation in developing countries has in many cases undergone change in the context of widespread decentralization and liberalization. This article examines an emerging "mixed" (coercive, community- and market-oriented) conservation approach in managed-resource protected areas and its effects on state power through a case study on forest protection in the central Indian state of Madhya Pradesh. The findings suggest that imperfect decentralization and partial liberalization resulted in changed forms, rather than uniform loss, of state power. A forest co-management program paradoxically strengthened local capacity and influence of the Forest Department, which generally maintained its territorial and knowledge-based control over forests and timber management. Furthermore, deregulation and reregulation enabled the state to withdraw from uneconomic activities but also implied reduced place-based control of non-timber forest products. Generally, the new policies and programs contributed to the separation of livelihoods and forests in Madhya Pradesh. The article concludes that regulatory, community- and market-based initiatives would need to be better coordinated to lead to more effective nature conservation and positive livelihood outcomes.

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OBJECTIVE: To assess the public health consequences of the rise in multiple births with respect to congenital anomalies. DESIGN: Descriptive epidemiological analysis of data from population-based congenital anomaly registries. SETTING: Fourteen European countries. POPULATION: A total of 5.4 million births 1984-2007, of which 3% were multiple births. METHODS: Cases of congenital anomaly included live births, fetal deaths from 20 weeks of gestation and terminations of pregnancy for fetal anomaly. MAIN OUTCOME MEASURES: Prevalence rates per 10,000 births and relative risk of congenital anomaly in multiple versus singleton births (1984-2007); proportion prenatally diagnosed, proportion by pregnancy outcome (2000-07). Proportion of pairs where both co-twins were cases. RESULTS: Prevalence of congenital anomalies from multiple births increased from 5.9 (1984-87) to 10.7 per 10,000 births (2004-07). Relative risk of nonchromosomal anomaly in multiple births was 1.35 (95% CI 1.31-1.39), increasing over time, and of chromosomal anomalies was 0.72 (95% CI 0.65-0.80), decreasing over time. In 11.4% of affected twin pairs both babies had congenital anomalies (2000-07). The prenatal diagnosis rate was similar for multiple and singleton pregnancies. Cases from multiple pregnancies were less likely to be terminations of pregnancy for fetal anomaly, odds ratio 0.41 (95% CI 0.35-0.48) and more likely to be stillbirths and neonatal deaths. CONCLUSIONS: The increase in babies who are both from a multiple pregnancy and affected by a congenital anomaly has implications for prenatal and postnatal service provision. The contribution of assisted reproductive technologies to the increase in risk needs further research. The deficit of chromosomal anomalies among multiple births has relevance for prenatal risk counselling.

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Este relatório se enquadra na cadeira de Simulação – Jogos de Marketing, do curso de licenciatura em Marketing, Gestão Comercial e Empreendedorismo ministrado pelo Instituto Superior de Ciências Económicas e Empresariais em Cabo Verde. Se trata de um relatório final de tudo aquilo que foi desenvolvido com o uso do simulador do Marketplace6, onde foi aplicado todos os conhecimentos apreendidos até hoje no curso, através da simulação da gestão de uma empresa de microcomputadores, a XY-TECH. Apresenta a evolução financeira da empresa ao longo dos dois anos da sua actividade, as estratégias de marketing desenvolvidas para que fosse possível garantir a sua sustentabilidade no mercado, o seu desempenho ao longo dos tempos e sua visão para o futuro. A experiência do uso deste simulador permitiu saber concretamente aquilo que se passa dentro das empresas em termos de gestão e tomada de decisão, bem como o trabalho em equipa, onde se pode aplicar todos os conhecimentos adquiridos nas outras cadeiras do curso. Traz como resultados competências em saber fazer na prática e habilidade em saber trabalhar em grupo.This report falls under the Simulation Chair - Marketing Games, degree course in Marketing, Business Management and Entrepreneurship taught by the School of Economics and Management in Cape Verde. It is a final report of all that has been developed using the Marketplace6 simulator, where it was applied all the knowledge acquired to date on the course, through the simulation of running a microcomputer company, XY-TECH. Presents the financial performance of the company over the two years of its activity, marketing strategies developed to make it possible to ensure their sustainability in the market, its performance over time and its vision for the future. The experience of using this simulator allowed to know precisely what is happening inside the company in terms of management and decision making, as well as team work, where you can apply all the knowledge acquired in other ongoing chairs. Brings results as skills in knowing how to do in practice and ability to know how to work in groups.