Phase Separation and the Dual Nature of the Electronic Structure in Cuprates

The dual nature of the electronic structure of stripes in $La_{2-x}Sr_xCuO_4$ was characterized by experimental observations, mainly by ARPES, of nodal spectral weight together with the straight segments near antinodal regions. We present here an attempt to understand this dual behavior in terms of the competition of order and disorder, by applying the phase separation theory of Cahn-Hilliard (CH) to the high pseudogap temperature, which is very large in the far underdoping region and vanishs near the doping level p=0.2. The spinodal phase separation predictions together with the Bogoliubov-deGennes (BdG) superconducting theory provides several interesting insights. For instance, we find that the disorder enhances the local superconducting gap which scales with the leading edge shift and that, upon doping, the size of the hole-rich stripes increases, yielding to the system their metallic properties.Comment: revised version, 4 pages and 3 fig

Prevalence and intensity of black-spot disease in fish community from a subtropical stream (Santa Lucía river basin, Uruguay)

The objective of the present study was to identify fish species susceptible to black spot disease, the temporal variation in intensity prevalence and abundance of black spot, and its correlation with environmental and host parameters. In order to do so, several sampling campaigns were conducted bimonthly during one year, along the main course of an agricultural watershed. A total of twenty-seven fish species were collected, out of which only two, Astyanax aff. fasciatus ("mojarra") and Oligosarcus jenynsii ("dientudo") presented black spot disease. In A. aff. fasciatus, 63% of black spot prevalence was registered and did not show significant seasonal changes during the sampling period, nor did the abundance and intensity. Regarding possible relations between the disease and environmental and host parameters, a higher intensity of black spot infection was observed in the ventral region of the fish and allometric coefficient (WT − LS, relationship) values did not differ significantly between parasitized and non-parasitized fish groups.El objetivo del presente estudio fue identificar las especies susceptibles a la enfermedad del punto negro, la variación temporal de su intensidad, prevalencia y abundancia; así como su relación con parámetros ambientales y del hospedador. Para ello, se realizaron muestreos bimensualmente durante un año, en el curso principal de una cuenca agrícola suburbana. Fueron colectadas un total de veintisiete especies, de las cuales en solo dos, Astyanax aff. fasciatus ("mojarra") y Oligosarcus jenynsii ("dientudo"), se observó la enfermedad del punto negro. En A. aff. fasciatus se registró una prevalencia de puntos negros del 63% y la misma no presentó diferencias significativas durante el período de muestreo, al igual que su abundancia e intensidad. En cuanto a las posibles relaciones de la enfermedad con parámetros ambientales y del hospedador, se observó una mayor intensidad de la infección en la región ventral de los peces y no se encontraron diferencias significativas en los valores del coeficiente alométrico (relación WT − LS) entre los peces parasitados y no parasitados

The Welfare Cost of Macroeconomic Uncertainty in the Post-War Period

Lucas (1987) has shown the surprising result that the welfare cost of business cycles is quite small. Using standard assumptions on preferences and a fully-fledged econometric model we computed the welfare costs of macroeconomic uncertainty for the post-WWII era using the multivariate Beveridge-Nelson decomposition for trends and cycles, which considers not only business-cycle uncertainty but also uncertainty from the stochastic trend in consumption. The post-WWII period is relatively quiet, with the welfare costs of uncertainty being about 0.9% of per-capita consumption. Although changing the decomposition method changed substantially initial results, the welfare cost of uncertainty is qualitatively small in the post-WWII era - about $175.00 a year per-capita in the U.S. We also computed the marginal welfare cost of macroeconomic uncertainty using this same technique. It is about twice as large as the welfare cost -$350.00 a year per-capita.welfare costs of business cycles, Beveridge-Nelson decomposition

On the Welfare Costs of Business-Cycle Fluctuations and Economic-Growth Variation in the 20th Century

Lucas (1987) has shown a surprising result in business-cycle research: the welfare cost ofbusiness cycles are very small. Our paper has several original contributions. First, in computingwelfare costs, we propose a novel setup that separates the effects of uncertainty stemming frombusiness-cycle fluctuations and economic-growth variation. Second, we extend the sample from which to compute the moments of consumption: the whole of the literature chose primarily to work with post-WWII data. For this period, actual consumption is already a result of counter-cyclical policies, and is potentially smoother than what it otherwise have been in their absence. So, we employ also pre-WWII data. Third, we take an econometric approach and compute explicitly the asymptotic standard deviation of welfare costs using the Delta Method. Estimates of welfare costs show major differences for the pre-WWII and the post-WWII era. They can reach up to 15 times for reasonable parameter values -β=0.985, and ∅=5. For example, in the pre-WWII period (1901-1941), welfare cost estimates are 0.31% of consumption if we consider only permanent shocks and 0.61% of consumption if we consider only transitory shocks. In comparison, the post-WWII era is much quieter: welfare costs of economic growth are 0.11% and welfare costs of business cycles are 0.037% - the latter being very close to the estimate in Lucas (0.040%). Estimates of marginal welfare costs are roughly twice the size of the total welfare costs. For the pre-WWII era, marginal welfare costs of economic-growth and business- cycle fluctuations are respectively 0.63% and 1.17% of per-capita consumption. The same figures for the post-WWII era are, respectively, 0.21% and 0.07% of per-capita consumption.

A construção social do conhecimento pela criança em idade escolar

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AS CONTRIBUIÇÕES DA GESTÃO DO CONHECIMENTO NO DESENVOLVIMENTO GERENCIAL: UM ESTUDO COM GESTORES DE PESSOAS DA REDE FEDERAL DE EDUCAÇÃO PROFISSIONAL, CIENTÍFICA E TECNOLÓGICA

Os modelos de administração pública influenciam a sociedade, assim como definem os avanços ou limitações dessa. A Rede federal de educação profissional, científica e tecnológica - RFEPT, como parte da administração pública, teve um crescimento considerável num Brasil recente e a gestão do conhecimento tornou-se mais relevante para se atingir a necessária efetividade dos serviços prestados à sociedade aliada a boas práticas de gestão. Investigar gestores de pessoas da RFEPT sobre o modelo de gestão por competências é o propósito deste estudo a partir de uma metodologia qualitativa com uso de software e análise de conteúdos. Fica evidente que o excesso de trabalho e carência de servidores são desafios freqüentes dos gestores. Seus entendimentos sobre gestão por competências são vagos se comparados à literatura pertinente. Suas competências mais evidenciadas são: comunicação, liderança e gestão de conflitos, e as desejadas por eles são: organização do tempo, comunicação, motivação e liderança. É essencial conceber o gerenciamento de pessoas como área estratégica das instituições, o que implica na gestão do conhecimento que contribua para o desenvolvimento desses gestores

A INFLUÊNCIA DO APEGO NA RECOMENDAÇÃO DE UMA IES NA ÓTICA DE ALUNOS DE UMA UNIVERSIDADE PÚBLICA FEDERAL NO BRASIL

Apego emocional e a recomendação da marca são dois assuntos explorados no marketing, entretanto, poucos trabalhos buscaram medir esta relação, em especial no contexto educacional. Buscando suprir esta carência, o presente artigo buscou analisar a influência do apego por uma instituição de ensino superior pública na recomendação dela por parte dos alunos. Para tanto, realizou-se uma survey descritiva e quantitativa com a participação de 87 alunos de um curso superior de uma universidade pública do sul do Brasil entre janeiro e abril de 2014. Os dados foram tabulados e tratados via equação estrutural, sendo que o resultado da modelagem, revelou haver uma forte influência do apego emocional na recomendação. Neste caso, conclui-se que o apego emocional é um forte componente para gerar a recomendação, mesmo em IES públicas federais

Numerical Study of the Cahn-Hilliard Equation in One, Two and Three Dimensions

The Cahn-Hilliard equation is related with a number of interesting physical phenomena like the spinodal decomposition, phase separation and phase ordering dynamics. On the other hand this equation is very stiff an the difficulty to solve it numerically increases with the dimensionality and therefore, there are several published numerical studies in one dimension (1D), dealing with different approaches, and much fewer in two dimensions (2D). In three dimensions (3D) there are very few publications, usually concentrate in some specific result without the details of the used numerical scheme. We present here a stable and fast conservative finite difference scheme to solve the Cahn-Hilliard with two improvements: a splitting potential into a implicit and explicit in time part and a the use of free boundary conditions. We show that gradient stability is achieved in one, two and three dimensions with large time marching steps than normal methods.Comment: 20 pages with 12 figs. Accepted in the Physica