878 resultados para Education, Administration|Education, Elementary|Sociology, Social Structure and Development
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The main purpose of this paper is building a research model to integrate the socioeconomic concept of social capital within intentional models of new firm creation. Nevertheless, some researchers have found cultural differences between countries and regions to have an effect on economic development. Therefore, a second objective of this study is exploring whether those cultural differences affect entrepreneurial cognitions. Research design and methodology: Two samples of last year university students from Spain and Taiwan are studied through an Entrepreneurial Intention Questionnaire (EIQ). Structural equation models (Partial Least Squares) are used to test the hypotheses. The possible existence of differences between both sub-samples is also empirically explored through a multigroup analysis. Main outcomes and results: The proposed model explains 54.5% of the variance in entrepreneurial intention. Besides, there are some significant differences between both subsamples that could be attributed to cultural diversity. Conclusions: This paper has shown the relevance of cognitive social capital in shaping individuals’ entrepreneurial intentions across different countries. Furthermore, it suggests that national culture could be shaping entrepreneurial perceptions, but not cognitive social capital. Therefore, both cognitive social capital and culture (made up essentially of values and beliefs), may act together to reinforce the entrepreneurial intention.
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While much of the literature on cross section dependence has focused mainly on estimation of the regression coefficients in the underlying model, estimation and inferences on the magnitude and strength of spill-overs and interactions has been largely ignored. At the same time, such inferences are important in many applications, not least because they have structural interpretations and provide useful interpretation and structural explanation for the strength of any interactions. In this paper we propose GMM methods designed to uncover underlying (hidden) interactions in social networks and committees. Special attention is paid to the interval censored regression model. Our methods are applied to a study of committee decision making within the Bank of England’s monetary policy committee.
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We propose an elementary theory of wars fought by fully rational contenders. Two parties play a Markov game that combines stages of bargaining with stages where one side has the ability to impose surrender on the other. Under uncertainty and incomplete information, in the unique equilibrium of the game, long confrontations occur: war arises when reality disappoints initial (rational) optimism, and it persist longer when both agents are optimists but reality proves both wrong. Bargaining proposals that are rejected initially might eventually be accepted after several periods of confrontation. We provide an explicit computation of the equilibrium, evaluating the probability of war, and its expected losses as a function of i) the costs of confrontation, ii) the asymmetry of the split imposed under surrender, and iii) the strengths of contenders at attack and defense. Changes in these parameters display non-monotonic effects.
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Biological features and social preferences have been studied separately as factors influencing human strategic behaviour. We run two studies in order to explore the interplay between these two sets of factors. In the first study, we investigate to what extent social preferences may have some biological underpinnings. We use simple one-shot distribution experiments to attribute subjects one out of four types of social preferences: Self-interested (SI), Competitive (C), Inequality averse (IA) and Efficiency-seeking (ES). We then investigate whether these four groups display differences in their levels of facial Fluctuating Asymmetry (FA) and in proxies for exposure to testosterone during phoetal development and puberty. We observe that development-related biological features and social preferences are relatively independent. In the second study, we compare the relative weight of these two set of factors by studying how they affect subjects’ behaviour in the Ultimatum Game (UG). We find differences in offers made and rejection rates across the four social preference groups. The effect of social preferences is stronger than the effect of biological features even though the latter is significant. We also report a novel link between facial masculinity (a proxy for exposure to testosterone during puberty) and rejection rates in the UG. Our results suggest that biological features influence behaviour both directly and through their relation with the type of social preferences that individuals hold.
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We study the asymmetric and dynamic dependence between financial assets and demonstrate, from the perspective of risk management, the economic significance of dynamic copula models. First, we construct stock and currency portfolios sorted on different characteristics (ex ante beta, coskewness, cokurtosis and order flows), and find substantial evidence of dynamic evolution between the high beta (respectively, coskewness, cokurtosis and order flow) portfolios and the low beta (coskewness, cokurtosis and order flow) portfolios. Second, using three different dependence measures, we show the presence of asymmetric dependence between these characteristic-sorted portfolios. Third, we use a dynamic copula framework based on Creal et al. (2013) and Patton (2012) to forecast the portfolio Value-at-Risk of long-short (high minus low) equity and FX portfolios. We use several widely used univariate and multivariate VaR models for the purpose of comparison. Backtesting our methodology, we find that the asymmetric dynamic copula models provide more accurate forecasts, in general, and, in particular, perform much better during the recent financial crises, indicating the economic significance of incorporating dynamic and asymmetric dependence in risk management.
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We investigate the dynamic and asymmetric dependence structure between equity portfolios from the US and UK. We demonstrate the statistical significance of dynamic asymmetric copula models in modelling and forecasting market risk. First, we construct “high-minus-low" equity portfolios sorted on beta, coskewness, and cokurtosis. We find substantial evidence of dynamic and asymmetric dependence between characteristic-sorted portfolios. Second, we consider a dynamic asymmetric copula model by combining the generalized hyperbolic skewed t copula with the generalized autoregressive score (GAS) model to capture both the multivariate non-normality and the dynamic and asymmetric dependence between equity portfolios. We demonstrate its usefulness by evaluating the forecasting performance of Value-at-Risk and Expected Shortfall for the high-minus-low portfolios. From back-testing, e find consistent and robust evidence that our dynamic asymmetric copula model provides the most accurate forecasts, indicating the importance of incorporating the dynamic and asymmetric dependence structure in risk management.
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This article investigates the history of land and water transformations in Matadepera, a wealthy suburb of metropolitan Barcelona. Analysis is informed by theories of political ecology and methods of environmental history; although very relevant, these have received relatively little attention within ecological economics. Empirical material includes communications from the City Archives of Matadepera (1919-1979), 17 interviews with locals born between 1913 and 1958, and an exhaustive review of grey historical literature. Existing water histories of Barcelona and its outskirts portray a battle against natural water scarcity, hard won by heroic engineers and politicians acting for the good of the community. Our research in Matadepera tells a very different story. We reveal the production of a highly uneven landscape and waterscape through fierce political and power struggles. The evolution of Matadepera from a small rural village to an elite suburb was anything but spontaneous or peaceful. It was a socio-environmental project well intended by landowning elites and heavily fought by others. The struggle for the control of water went hand in hand with the land and political struggles that culminated – and were violently resolved - in the Spanish Civil War. The displacement of the economic and environmental costs of water use from few to many continues to this day and is constitutive of Matadepera’s uneven and unsustainable landscape. By unravelling the relations of power that are inscribed in the urbanization of nature (Swyngedouw, 2004), we question the perceived wisdoms of contemporary water policy debates, particularly the notion of a natural scarcity that merits a technical or economic response. We argue that the water question is fundamentally a political question of environmental justice; it is about negotiating alternative visions of the future and deciding whose visions will be produced.
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Insect odorant receptors (ORs) comprise an enormous protein family that translates environmental chemical signals into neuronal electrical activity. These heptahelical receptors are proposed to function as ligand-gated ion channels and/or to act metabotropically as G protein-coupled receptors (GPCRs). Resolving their signalling mechanism has been hampered by the lack of tertiary structural information and primary sequence similarity to other proteins. We use amino acid evolutionary covariation across these ORs to define restraints on structural proximity of residue pairs, which permit de novo generation of three-dimensional models. The validity of our analysis is supported by the location of functionally important residues in highly constrained regions of the protein. Importantly, insect OR models exhibit a distinct transmembrane domain packing arrangement to that of canonical GPCRs, establishing the structural unrelatedness of these receptor families. The evolutionary couplings and models predict odour binding and ion conduction domains, and provide a template for rationale structure-activity dissection.
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Eusociality is taxonomically rare, yet associated with great ecological success. Surprisingly, studies of environmental conditions favouring eusociality are often contradictory. Harsh conditions associated with increasing altitude and latitude seem to favour increased sociality in bumblebees and ants, but the reverse pattern is found in halictid bees and polistine wasps. Here, we compare the life histories and distributions of populations of 176 species of Hymenoptera from the Swiss Alps. We show that differences in altitudinal distributions and development times among social forms can explain these contrasting patterns: highly social taxa develop more quickly than intermediate social taxa, and are thus able to complete the reproductive cycle in shorter seasons at higher elevations. This dual impact of altitude and development time on sociality illustrates that ecological constraints can elicit dynamic shifts in behaviour, and helps explain the complex distribution of sociality across ecological gradients.
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Abstract: The increasingly high hygienic standards characterizing westernized societies correlate with an increasingly high prevalence of allergic disease. Initially based on these observations, the hygiene hypothesis postulates that reduced microbial stimulation during infancy impairs the immune system development and increases the risk of allergy. Moreover, there is increasing evidence that the crosstalk existing between the intestine and the resident microbiota is crucial for gut homeostasis. In particular, bacterial colonization of the gut affects the integrity of the gut barrier and stimulates the development of the gut associated immune tissue, both phenomena being essential for the immune system to mount a controlled response to food antigens. Therefore, alterations in the microbial colonization process, by compromising the barrier homeostasis, may increase the risk of food allergy. In this context, antibiotic treatment, frequently prescribed during infancy, affects gut colonization by bacteria. However, little is known about the impact of alterations in the colonization process on the maturation of the gut barrier and on the immunological response to oral antigens. The objective of this work was to determine the impact of a commercial antibiotic preparation employed in pediatric settings on the gut barrier status at the critical period of the suckling/weaning transition and to evaluate the physiological consequences of this treatment in terms of immune response to food antigens. We established an antibiotic-treated suckling rat model relevant to the pediatric population in terms of type, dose and route of administration of the antibiotic and of changes in the patterns of microbial colonization. Oral tolerance to a novel luminal antigen (ovalbumin) was impaired when the antigen was introduced during antibiotic treatment. These results paralleled to alterations in the intestinal permeability to macromolecules and reduced intestinal expression of genes coding for the major histocomptatibility complex II molecules, which suggest a reduced capacity of antigen handling and presentation in the intestine of the antibiotic-treated animals. In addition, low luminal IgA levels and reduced intestinal expression of genes coding for antimicrobial proteins suggest that protection against pathogens was reduced under antibiotic treatment. In conclusion, we observed in suckling rats that treatment with abroad-spectrum antibiotic commonly used in pediatric practices reduced the capacity of the immune system to develop tolerance. The impact of the antibiotic treatment on the immune response to the antigen-was likely mediated by the alterations of the gut microbiota, through impairment in the mechanisms of antigen handling and presentation. This work reinforces the body of data supporting a key role of the intestinal microbiota modulating the risk of allergy development and leads us to propose that the introduction of new food antigens should be avoided during antibiotic treatment in infants. Résumé: L'augmentation du niveau d'hygiène caractérisant les sociétés occidentales semble être fortement corrélée avec l'augmentation des cas d'allergie dans ces pays. De cette observation est née l'hypothèse qu'une diminution des stimuli microbiens pendant l'enfance modifie le développement du système immunitaire augmentant ainsi le risque d'allergie. En ce sens, un nombre croissant de données indiquent que les interactions existant entre l'intestin et les bactéries résidantes sont cruciales pour l'équilibre du système. En effet, la présence de bactéries dans l'intestin affecte l'intégrité de sa fonction de barrière et stimule le développement du système immunitaire intestinal. Ces deux paramètres étant essentiels à la mise en place d'une réponse contrôlée vis à vis d'un antigène reçu oralement, toute modification du processus naturel de colonisation compromettant l'équilibre intestinal pourrait augmenter le risque d'allergie. Les traitements aux antibiotiques, fréquemment prescrits en pédiatrie, modifient de façon conséquente le processus de colonisation bactérienne. Cependant peu de données existent concernant l'impact d'une altération du processus de colonisation sur la maturation de la barrière intestinale et de la réponse immunitaire dirigée contre un antigène. L'objectif de ce travail était de déterminer l'impact d'un antibiotique commercial et employé en pédiatrie sur l'état de la barrière intestinale au moment critique du sevrage et d'évaluer les conséquences physiologiques d'un tel traitement sur la réponse immune à un antigène alimentaire. Nous avons mis en place un modèle de rats allaités, traités à l'antibiotique, le plus proche possible des pratiques pédiatriques, en terme de nature, dose et voie d'administration de l'antibiotique. Nous avons constaté que l'établissement de la tolérance orale à un nouvel antigène (l'ovalbumine) est altéré quand celui-ci est donné pour la première fois au cours du traitement antibiotique. Ces résultats coïncident avec une diminution de la perméabilité intestinale aux macromolécules, ainsi qu'avec une diminution de l'expression des gènes codant pour les molécules du complexe majeur d'histocomptatibilité de classe II, suggérant une modification de l'apprêtement et de la présentation de l'antigène au niveau intestinal chez les rats traités à l'antibiotique. De plus, un faible taux d'IgA et une diminution de l'expression des gènes codant pour des protéines antimicrobiennes, observés après l'administration d'antibiotique, laissent à penser que la protection contre un pathogène est diminuée lors d'un traitement antibiotique. En conclusion, nous avons observé qu'un traitement antibiotique à large spectre d'activité, couramment utilisé en pédiatrie, réduit la capacité d'induction de la tolérance orale chez le rat allaité. L'impact du traitement antibiotique sur la réponse immune semble induite par l'altération de la flore intestinale via son effet sur les mécanismes d'apprêtement et de présentation de l'antigène. Ce travail renforce l'ensemble des données existantes qui accorde à la flore intestinale un rôle clef dans la modulation du risque de développement d'allergie et nous amène à recommander d'éviter l'introduction d'un nouvel aliment lorsqu'un enfant est traité aux antibiotiques.
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Objectives: Previous studies using subjective assessments have reported associations between sleep quantity and quality and cardiometabolic disorders, but little is known regarding the associ-ations with objective sleep characteristics. The purpose of this study was to evaluate the association between objective sleep measure sand metabolic syndrome (MS), hypertension, diabetes and obesity. Methods: 2162 subjects (51.2% women, mean age 58,11.1) from the general population were evaluated for hypertension,diabetes, overweight/obesity and MS, and underwent a full polysom-nography (PSG). PSG measured variables included: Total sleep time(TST), percentage and time spent in slow wave sleep (SWS) and in rapid eye movement (REM) sleep, sleep efficiency and arousal index(ArI) Results: In univariate analyses, MS was associated with decreased TST, SWS, REM sleep, sleep efficiency and increased ArI. After adjustment for age, gender, smoking, alcohol, physical activity, drugsthat affect sleep and depression, the ArI remained significantly higher, but the difference disappeared in subjects without significant sleep disordered breathing (SDB). Differences in sleep structure were also found according to the presence or absence of hypertension, diabetes and overweight/obesity in univariate analysis. However, these differences were attenuated after multivariate adjustment and after excluding subjects with significant SDB. Conclusions: In this population-based sample we found significant associations between sleep structure and MS, hypertension, diabetes and obesity. However, these associations were cancelled after multivariate adjustment. We conclude that normal variations in sleep contribute little if any to MS and associated disorders.
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(Résumé de l'ouvrage) This volume addresses research topics within the field of Bhakti literature, the devotional poetry and other compositions of devotional character in the earlier literature of the modern South Asian languages. Its papers range from the roots of the Bhakti tradition in the early history of Krsna to its modern adaptations in nineteenth- and twentieth-century culture. Geographically, they span Bengal to Sind, Panjab to Maharashtra. Contemporary study of the modern Indian languages has broadened the scope of scholarship to consider today's Hindu attitudes, and those of a mixed society, against the background of ancient culture. Here, materials in six modern Asian languages are discussed: Bengali, Gujarati, Hindi in its main literary forms, Marathi, Panjabi and Sindhi; with assessment also of material in Sanskrit, Arabic and Chinese. In addition to studies of literary (and orally transmitted) works in the Krsna or Rama traditions, and of Sufi compositions and their interpretation, there are papers on the early history of sacred sites, the emergence of the religion of Rama, later religious formulations throughout the subcontinent, and the interaction of the Islamic and the Hindu.
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The recent strides of democracy in Latin America have been associated to conflicting outcomes. The expectation that democracy would bring about peace and prosperity have been only partly satisfied. While political violence has been by and large eradicated from the sub-continent, poverty and social injustice still prevail and hold sway. Our study argues that democracy matters for inequality through the growing strength of center left and left parties and by making political leaders in general more responsive to the underprivileged. Furthermore, although the pension reforms recently enacted in the region generated overall regressive outcomes on income distribution, democratic countries still benefit from their political past: where democratic tradition was stronger, such outcomes have been milder. Democratic tradition and the specific ideological connotations of the parties in power, on the other hand, did not play an equally crucial role in securing lower levels of political violence: during the last wave of democratizations in Latin America, domestic peace was rather an outcome of political and social concessions to those in distress. In sum, together with other factors and especially economic ones, the reason why recent democratizations have provided domestic peace in most cases, but have been unable so far to solve the problem of poverty and inequality, is that democratic traditions in the subcontinent have been relatively weak and, more specifically, that this weakness has undermined the growth of left and progressive parties, acting as an obstacle to redistribution. Such weakness, on the other hand, has not prevented the drastic reduction of domestic political violence, since what mattered in this case was a combination of symbolic or material concessions and political agreements among powerful élites and counter-élites.