930 resultados para pattern-mixture model


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We suggest a time-dependent mean-field hydrodynamic model for a binary dipolar boson-fermion mixture to study the stability and collapse of fermions in the 164Dy-161Dy mixture. The condition of stability of the dipolar mixture is illustrated in terms of phase diagrams. A collapse is induced in a disk-shaped stable binary mixture by jumping the interspecies contact interaction from repulsive to attractive by the Feshbach resonance technique. The subsequent dynamics is studied by solving the time-dependent mean-field model including three-body loss due to molecule formation in boson-fermion and boson-boson channels. Collapse and fragmentation in the fermions after subsequent explosions are illustrated. The anisotropic dipolar interaction leads to anisotropic fermionic density distribution during collapse. This study is carried out in three-dimensional space using realistic values of dipolar and contact interactions. © 2013 American Physical Society.

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Pós-graduação em Agronomia (Energia na Agricultura) - FCA

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The adverse effects on Latin America and the Caribbean of the global economic and financial crisis, the worst since the 1930s, have been considerably less than was once feared. Although a run of growth was cut short in 2009 and regional output shrank by 1.9%, the impact of the crisis was limited by the application of countercyclical fiscal and monetary policies by many of the region’s governments. The recovery in the economies, particularly in South America, has gone hand-in-hand with the rapid resurgence of the emerging economies of Asia, with all the favourable consequences this has had for global trade. A similar pattern may be observed regarding the impact of the crisis on labour markets in Latin America and the Caribbean. Although millions of people lost their jobs or had to trade down to lower-quality work, levels of employment (including formal employment) fell by less than originally foreseen. At the same time, real wages rose slightly in a context of falling inflation. The labour market thus stabilized domestic demand, and this contributed to the recovery that began in many countries in late 2009. Improved international trade and financing conditions, and the pick-up in domestic demand driven by macroeconomic policies, have led different commentators to estimate growth in the region’s economy at some 6% in 2010. As detailed in the first part of this edition of the Bulletin, the upturn has been manifested at the regional level by the creation of formal employment, a rise in the employment rate, a decline in joblessness and a moderate increase in real wages. Specifically, it is estimatedthat the regional unemployment rate will have dropped by 0.6 percentage points, from 8.1% in 2009 to 7.5% in 2010. The performance of different countries and subregions has been very uneven, however. On the one hand, there is Brazil, where high economic growth has been accompanied by vigorous creation of formal jobs and the unemployment rate has dropped to levels not seen in a long time. Other countries in South America have benefited from strong demand for natural resources from the Asian countries. Combined with higher domestic demand, this has raised their economic growth rates and had a positive impact on employment indicators. On the other hand, the recovery is still very weak in certain countries and subregions, particularly in the Caribbean, with employment indicators continuing to worsen.Thus, the recovery in the region’s economy in 2010 may be characterized as dynamic but uneven. Growth estimates for 2011 are less favourable. The risks associated with the imbalances in the world economy and the withdrawal of countercyclical fiscal packages are likely to cause the region to grow more slowly in 2011. Accordingly, a small further reduction of between 0.2 and 0.4 percentage points in the unemployment rate is projected for 2011. However, these indicators of recovery do not guarantee growth with decent work in the long term. To bolster the improvement in labour market indicators and generate more productive employment and decent work, the region’s countries need to strengthen their macroeconomic policies, improve regional and global policy coordination, identify and remove bottlenecks in the labour market itself and enhance instruments designed to promote greater equality. Like the rest of the world, the Latin American and Caribbean region is also confronted with the challenge of transforming the way it produces so that its economies can develop along tracks that are sustainable in the long term. Climate change and the consequent challenge of developing and strengthening low-carbon production and consumption patterns will also affect the way people work. A great challenge ahead is to create green jobs that combine decent work with environmentally sustainable production patterns. From this perspective, the second part of this Bulletin discusses the green jobs approach, offering some information on the challenges and opportunities involved in moving towards a sustainable economy in the region and presenting a set of options for addressing environmental issues and the repercussions of climate change in the world of work. Although the debate about the green jobs concept is fairly new in the region, examples already exist and a number of countries have moved ahead with the application of policies and programmes in this area. Costa Rica has formulated a National Climate Change Strategy, for example, whose foremost achievements include professional training in natural-resource management. In Brazil, fuel production from biomass has increased and social housing with solar panelling is being built. A number of other countries in the region are making progress in areas such as ecotourism, sustainable agriculture and infrastructure for climate change adaptation, and in formalizing the work of people who recycle household waste. The shift towards a more environmentally sustainable economy may cause jobs to be destroyed in some economic sectors and created in others. The working world will inevitably undergo major changes. If the issue is approached by way of social dialogue and appropriate public policies, there is a chance to use this shift to create more decent jobs, thereby contributing to growth in the economy, the construction of higher levels of equality and protection for the environment.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Three Paracoccidioides brasiliensis antigens, namely a culture filtrate preparation, a somatic antigen and a mixture of equal parts of the two, were tested by two serological techniques against sera from patients with paracoccidioidomycosis, and in an in vivo delayed hypersensitivity model in mice. The antigen mixture was more sensitive than the two individual antigens for the evaluation of humoral and cellular immune response to P. brasiliensis, both in man and in experimental animals.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Although praised for their rationality, humans often make poor decisions, even in simple situations. In the repeated binary choice experiment, an individual has to choose repeatedly between the same two alternatives, where a reward is assigned to one of them with fixed probability. The optimal strategy is to perseverate with choosing the alternative with the best expected return. Whereas many species perseverate, humans tend to match the frequencies of their choices to the frequencies of the alternatives, a sub-optimal strategy known as probability matching. Our goal was to find the primary cognitive constraints under which a set of simple evolutionary rules can lead to such contrasting behaviors. We simulated the evolution of artificial populations, wherein the fitness of each animat (artificial animal) depended on its ability to predict the next element of a sequence made up of a repeating binary string of varying size. When the string was short relative to the animats' neural capacity, they could learn it and correctly predict the next element of the sequence. When it was long, they could not learn it, turning to the next best option: to perseverate. Animats from the last generation then performed the task of predicting the next element of a non-periodical binary sequence. We found that, whereas animats with smaller neural capacity kept perseverating with the best alternative as before, animats with larger neural capacity, which had previously been able to learn the pattern of repeating strings, adopted probability matching, being outperformed by the perseverating animats. Our results demonstrate how the ability to make predictions in an environment endowed with regular patterns may lead to probability matching under less structured conditions. They point to probability matching as a likely by-product of adaptive cognitive strategies that were crucial in human evolution, but may lead to sub-optimal performances in other environments.

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A Bayesian nonparametric model for Taguchi's on-line quality monitoring procedure for attributes is introduced. The proposed model may accommodate the original single shift setting to the more realistic situation of gradual quality deterioration and allows the incorporation of an expert's opinion on the production process. Based on the number of inspections to be carried out until a defective item is found, the Bayesian operation for the distribution function that represents the increasing sequence of defective fractions during a cycle considering a mixture of Dirichlet processes as prior distribution is performed. Bayes estimates for relevant quantities are also obtained. (C) 2012 Elsevier B.V. All rights reserved.

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We present for the first time a justification on the basis of central limit theorems for the family of life distributions generated from scale-mixture of normals. This family was proposed by Balakrishnan et al. (2009) and can be used to accommodate unexpected observations for the usual Birnbaum-Saunders distribution generated from the normal one. The class of scale-mixture of normals includes normal, slash, Student-t, logistic, double-exponential, exponential power and many other distributions. We present a model for the crack extensions where the limiting distribution of total crack extensions is in the class of scale-mixture of normals. (C) 2012 Elsevier B.V. All rights reserved.

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The availability of chemical elements for plants is mainly dependent on the nature of the soil and characteristics of each species. The transfer factors of lanthanides from the soil to the tree leaves of the Atlantic Forest, Brazil, were calculated for one fern species (Alsophila sternbergii-Pteridophyta division) and four magnoliophytes species (Bathysa australis, Euterpe edulis, Garcinia gardneriana and Guapira opposita-Magnoliophyta division) obtained in two areas of Serra do Mar State Park and collected in two different seasons. Samples were analyzed by instrumental neutron activation analysis (INAA). The soil-to-plant transfer factor (TF = C(plant):C(soil)) in magnoliophytes species was correlated to the mass fraction of lanthanides in the soil, described by a exponential model (TF = a.C (soil) (-b) ). Despite the tree fern Alsophila sternbergii presented a hyperaccumulation of lanthanides, this species did not have a significant relationship between TF and mass fraction in soil. Results indicated that plants of Magnoliophyta division selected the input of lanthanides from the soil, while the same was not observed in Alsophila sternbergii.