859 resultados para Social and spatial dynamics


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The knowledge on Atlantic Forest scarab beetle fauna is quite limited. This biome is strongly degraded and these insects can be used as bioindicators since they are sensitive to forest destruction and show distinct organizational patterns in forest fragments or in areas that have been deteriorated by human activity. Thus, a study of the Scarabaeidae (sensu stricto) dung beetles fauna that inhabit Serra do Japi, São Paulo, Brazil (23º12'-23º22' S and 46º53'-47º03'W) was carried out; the monthly species richness was analyzed in six areas during one year and the vegetation's structural physiognomy was described. The areas included a conserved and a degraded valley, a northward and a southward hillside, a hilltop, and an area of secondary forest growing under eucalyptus trees. The specimens were collected using four pitfall traps baited with human feces, which remained at each spot during 48 hours. Between September, 1997 and August, 1998, 3524 individuals of 39 species were collected; the most abundant were: Canthidium trinodosum, Eurysternus cyanescens, Uroxys kratochvili, Scybalocanthon nigriceps, Uroxys lata, Canthonella sp., Dichotomius assifer, Deltochilum furcatum, Canthidium sp.2, Canthon latipes, Deltochilum rubripenne, Eurysternus sp., and Dichotomius sp.1. The number of individuals and species was greater in the hot, rainy season, when there was a correlation between the number of species and the mean annual temperature [r²= 0.69; p<0.01]. The lower winter richness was most pronounced in the conserved valley, while richness remained relatively constant in the degraded valley; abundance was much higher in the degraded valley. The cluster analysis showed that the valleys and hillsides are the most similar in relation to species composition and abundance, yet different from the secondary forest with eucalypts and the hilltop.

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We analyze the impact of a minimum price variation (tick) and timepriority on the dynamics of quotes and the trading costs when competitionfor the order flow is dynamic. We find that convergence to competitiveoutcomes can take time and that the speed of convergence is influencedby the tick size, the priority rule and the characteristics of the orderarrival process. We show also that a zero minimum price variation is neveroptimal when competition for the order flow is dynamic. We compare thetrading outcomes with and without time priority. Time priority is shownto guarantee that uncompetitive spreads cannot be sustained over time.However it can sometimes result in higher trading costs. Empiricalimplications are proposed. In particular, we relate the size of thetrading costs to the frequency of new offers and the dynamics of theinside spread to the state of the book.

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In analyzing the distinctive contribution of foreign subsidiaries anddomestic firms to productivity growth in aggregate Belgian manufacturing,this paper shows that foreign ownership is an important source of firmheterogeneity affecting productivity dynamics. Foreign firms havecontributed disproportionately large to aggregate productivity growth,but more importantly reallocation processes differ significantly betweenthe groups of foreign subsidiaries and domestic firms.

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We model firm-owned capital in a stochastic dynamic New-Keynesian generalequilibrium model à la Calvo. We find that this structure impliesequilibrium dynamics which are quantitatively di¤erent from the onesassociated with a benchmark case where households accumulate capital andrent it to firms. Our findings therefore stress the importance ofmodeling an investment decision at the firm level in addition to ameaningful price setting decision. Along the way we argue that the problemof modeling firm-owned capital with Calvo price-setting has not been solvedin a correct way in the previous literature.

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Objectifs - Identifier les facteurs de vulnérabilité sociaux et médicaux associés au recours multiple aux consultations des urgences. - Déterminer si les patients à recours multiple sont plus à même de combiner ces facteurs dans un système d'assurance universelle. Méthode Il s'agit d'une étude cas-contrôle rétrospective basée sur l'étude de dossiers médico-administratifs comparant des échantillons randomisés de patients à recours multiple à des patients n'appartenant pas à cette catégorie, au sein des urgences du Centre Hospitalier Universitaire Vaudois et de la Policlinique Médicale Universitaire de Lausanne. Les auteurs ont défini les patients à recours multiple comme comptabilisant au moins quatre consultations aux urgences durant les douze mois précédents. Les patients adultes (>18 ans) ayant consulté les urgences entre avril 2008 et mars 2009 (période d'étude) étaient inclus ; ceux quittant les urgences sans décharge médicale étaient exclus. Pour chaque patient, le premier dossier d'urgence informatisé inclus dans la période d'étude était sélectionné pour l'extraction des données. Outre les variables démographiques de base, les variables d'intérêt comprennent des caractéristiques sociales (emploi, type de résidence) et médicales (diagnostic principal aux urgences). Les facteurs sociaux et médicaux significatifs ont été utilisés dans la construction d'un modèle de régression logistique, afin de déterminer les facteurs associés avec le recours multiple aux urgences. De plus, la combinaison des facteurs sociaux et médicaux a été étudiée. Résultats Au total, 359/Γ591 patients à recours multiple et 360/34'263 contrôles ont été sélectionnés. Les patients à recours multiple représentaient moins d'un vingtième de tous les patients des urgences (4.4%), mais engendraient 12.1% de toutes les consultations (5'813/48'117), avec un record de 73 consultations. Aucune différence en termes d'âge ou de genre n'est apparue, mais davantage de patients à recours multiples étaient d'une nationalité autre que suisse ou européenne (n=117 [32.6%] vs n=83 [23.1%], p=0.003). L'analyse multivariée a montré que les facteurs de vulnérabilité sociaux et médicaux les plus fortement associés au recours multiple aux urgences étaient : être sous tutelle (Odds ratio [OR] ajusté = 15.8; intervalle de confiance [IC] à 95% = 1.7 à 147.3), habiter plus proche des urgences (OR ajusté = 4.6; IC95% = 2.8 à 7.6), être non assuré (OR ajusté = 2.5; IC95% = 1.1 à 5.8), être sans emploi ou dépendant de l'aide sociale (OR ajusté = 2.1; IC95% = 1.3 à 3.4), le nombre d'hospitalisations psychiatriques (OR ajusté = 4.6; IC95% = 1.5 à 14.1), ainsi que le recours à au moins cinq départements cliniques différents durant une période de douze mois (OR ajusté = 4.5; IC95% = 2.5 à 8.1). Le fait de comptabiliser deux sur quatre facteurs sociaux augmente la vraisemblance du recours multiple aux urgences (OR ajusté = 5.4; IC95% = 2.9 à 9.9) ; des résultats similaires ont été trouvés pour les facteurs médicaux (OR ajusté = 7.9; IC95% = 4.6 à 13.4). La combinaison de facteurs sociaux et médicaux est fortement associée au recours multiple aux urgences, puisque les patients à recours multiple étaient dix fois plus à même d'en comptabiliser trois d'entre eux (sur un total de huit facteurs, IC95% = 5.1 à 19.6). Conclusion Les patients à recours multiple aux urgences représentent une proportion modérée des consultations aux urgences du Centre Hospitalier Universitaire Vaudois et de la Policlinique Médicale Universitaire de Lausanne. Les facteurs de vulnérabilité sociaux et médicaux sont associés au recours multiple aux urgences. En outre, les patients à recours multiple sont plus à même de combiner les vulnérabilités sociale et médicale que les autres. Des stratégies basées sur le case management pourraient améliorer la prise en charge des patients à recours multiple avec leurs vulnérabilités afin de prévenir les inégalités dans le système de soins ainsi que les coûts relatifs.

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Gesneriaceae are represented in the New World (NW) by a major clade (c. 1000 species) currently recognized as subfamily Gesnerioideae. Radiation of this group occurred in all biomes of tropical America and was accompanied by extensive phenotypic and ecological diversification. Here we performed phylogenetic analyses using DNA sequences from three plastid loci to reconstruct the evolutionary history of Gesnerioideae and to investigate its relationship with other lineages of Gesneriaceae and Lamiales. Our molecular data confirm the inclusion of the South Pacific Coronanthereae and the Old World (OW) monotypic genus Titanotrichum in Gesnerioideae and the sister-group relationship of this subfamily to the rest of the OW Gesneriaceae. Calceolariaceae and the NW genera Peltanthera and Sanango appeared successively sister to Gesneriaceae, whereas Cubitanthus, which has been previously assigned to Gesneriaceae, is shown to be related to Linderniaceae. Based on molecular dating and biogeographical reconstruction analyses, we suggest that ancestors of Gesneriaceae originated in South America during the Late Cretaceous. Distribution of Gesneriaceae in the Palaeotropics and Australasia was inferred as resulting from two independent long-distance dispersals during the Eocene and Oligocene, respectively. In a short time span starting at 34 Mya, ancestors of Gesnerioideae colonized several Neotropical regions including the tropical Andes, Brazilian Atlantic forest, cerrado, Central America and the West Indies. Subsequent diversification within these areas occurred largely in situ and was particularly extensive in the mountainous systems of the Andes, Central America and the Brazilian Atlantic forest. Only two radiations account for 90% of the diversity of Gesneriaceae in the Brazilian Atlantic forest, whereas half of the species richness in the northern Andes and Central America originated during the last 10 Myr from a single radiation.

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The right of a person to be protected from natural hazards is a characteristic of the social and economical development of the society. This paper is a contribution to the reflection about the role of Civil Protection organizations in a modern society. The paper is based in the inaugural conference made by the authors on the 9th Plinius Conference on Mediterranean Storms. Two major issues are considered. The first one is sociological; the Civil Protection organizations and the responsible administration of the land use planning should be perceived as reliable as possible, in order to get consensus on the restrictions they pose, temporary or definitely, on the individual free use of the territory as well as in the entire warning system. The second one is technological: in order to be reliable they have to issue timely alert and warning to the population at large, but such alarms should be as "true" as possible. With this aim, the paper summarizes the historical evolution of the risk assessment, starting from the original concept of "hazard", introducing the concepts of "scenario of event" and "scenario of risk" and ending with a discussion about the uncertainties and limits of the most advanced and efficient tools to predict, to forecast and to observe the ground effects affecting people and their properties. The discussion is centred in the case of heavy rains and flood events in the North-West of Mediterranean Region.

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The new techniques proposed for agriculture in the Amazon region include rotational fallow systems enriched with leguminous trees and the replacement of biomass burning by mulching. Decomposition and nutrient release from mulch were studied using fine-mesh litterbags with five different leguminous species and the natural fallow vegetation as control. Samples from each treatment were analyzed for total C, N, P, K, Ca, Mg, lignin, cellulose content and soluble polyphenol at different sampling times over the course of one year. The decomposition rate constant varied with species and time. Weight loss from the decomposed litter bag material after 96 days was 30.1 % for Acacia angustissima, 32.7 % for Sclerolobium paniculatum, 33.9 % for Iinga edulis and the Fallow vegetation, 45.2 % for Acacia mangium and 63.6 % for Clitoria racemosa. Immobilization of N and P was observed in all studied treatments. Nitrogen mineralization was negatively correlated with phenol, C-to-N ratio, lignin + phenol/N ratio, and phenol/phosphorus ratios and with N content in the litterbag material. After 362 days of field incubation, an average (of all treatments), 3.3 % K, 32.2 % Ca and 22.4 % Mg remained in the mulch. Results confirm that low quality and high amount of organic C as mulch application are limiting for the quantity of energy available for microorganisms and increase the nutrient immobilization for biomass decomposition, which results in competition for nutrients with the crop plants.

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One of the limitations of cross-country health expenditure analysis refers to the fact that the financing, the internal organization and political restraints of health care decision-making are country-specific and heterogeneous. Yet, a potential solution is to examine the influence of such effects in those countries that have undertaken decentralization processes. In such a setting, it is possible to examine potential expenditure spillovers across the geography of a country as well as the influence of the political ideology of regional incumbents on public health expenditure. This paper examines the determinants of public health expenditure within Spanish region-states (Autonomous Communities, ACs), most of them subject to similar financing structures although exhibiting significant heterogeneity as a result of the increasing decentralization, region-specific political factors along with different use of health care inputs, economic dimension and spatial interactions

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The loss of biodiversity has become a matter of urgent concern and a better understanding of local drivers is crucial for conservation. Although environmental heterogeneity is recognized as an important determinant of biodiversity, this has rarely been tested using field data at management scale. We propose and provide evidence for the simple hypothesis that local species diversity is related to spatial environmental heterogeneity. Species partition the environment into habitats. Biodiversity is therefore expected to be influenced by two aspects of spatial heterogeneity: 1) the variability of environmental conditions, which will affect the number of types of habitat, and 2) the spatial configuration of habitats, which will affect the rates of ecological processes, such as dispersal or competition. Earlier, simulation experiments predicted that both aspects of heterogeneity will influence plant species richness at a particular site. For the first time, these predictions were tested for plant communities using field data, which we collected in a wooded pasture in the Swiss Jura mountains using a four-level hierarchical sampling design. Richness generally increased with increasing environmental variability and "roughness" (i.e. decreasing spatial aggregation). Effects occurred at all scales, but the nature of the effect changed with scale, suggesting a change in the underlying mechanisms, which will need to be taken into account if scaling up to larger landscapes. Although we found significant effects of environmental heterogeneity, other factors such as history could also be important determinants. If a relationship between environmental heterogeneity and species richness can be shown to be general, recently available high-resolution environmental data can be used to complement the assessment of patterns of local richness and improve the prediction of the effects of land use change based on mean site conditions or land use history.

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One of the limitations of cross-country health expenditure analysis refers to the fact that the financing, the internal organization and political restraints of health care decision-making are country-specific and heterogeneous. Yet, a potential solution is to examine the influence of such effects in those countries that have undertaken decentralization processes. In such a setting, it is possible to examine potential expenditure spillovers across the geography of a country as well as the influence of the political ideology of regional incumbents on public health expenditure. This paper examines the determinants of public health expenditure within Spanish region-states (Autonomous Communities, ACs), most of them subject to similar financing structures although exhibiting significant heterogeneity as a result of the increasing decentralization, region-specific political factors along with different use of health care inputs, economic dimension and spatial interactions

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We present a study of the evaporation dynamics of a substance undergoing a coarsening process. The system is modeled by the Cahn-Hilliard equation with absorbing boundaries. We have found that the dynamics, although of a diffusive nature, is much slower than the usual one without coarsening. Analytical and simulation results are in reasonable agreement.