Nonmesonic weak decay of Λ-hypernuclei within independent-particle shell-model

After a short introduction to the nonmesonic weak decay (NMWD) ΛN→nN of Λ-hypernuclei we discuss the long-standing puzzle on the ratio Γn/Γp, and some recent experimental evidences that signalized towards its final solution. Two versions of the Independent-Particle-Shell-Model (IPSM) are employed to account for the nuclear structure of the final residual nuclei. They are: (a) IPSM-a, where no correlation, except for the Pauli principle, is taken into account, and (b) IPSM-b, where the highly excited hole states are considered to be quasi-stationary and are described by Breit-Wigner distributions, whose widths are estimated from the experimental data. We evaluate the coincidence spectra in Λ 4He, Λ 5He, Λ 12C, Λ 16O, and Λ 28Si, as a function of the sum of kinetic energies EnN=En+EN for N=n, p. The recent Brookhaven National Laboratory experiment E788 on Λ 4He, is interpreted within the IPSM. We found that the shapes of all the spectra are basically tailored by the kinematics of the corresponding phase space, depending very weakly on the dynamics, which is gauged here by the one-meson-exchange- potential. In spite of the straightforwardness of the approach a good agreement with data is achieved. This might be an indication that the final-state- interactions and the two-nucleon induced processes are not very important in the decay of this hypernucleus. We have also found that the π+K exchange potential with soft vertex-form-factor cutoffs (Λπ≈0. 7GeV, ΛK≈0.9GeV), is able to account simultaneously for the available experimental data related to Γp and Γn for Λ 4H, and Λ 5He. © 2010 American Institute of Physics.

Science and technology policies in open economies: the case of Latin America and the Caribbean

Includes bibliography

Theory and practice of industrial policy: evidence from the Latin American experience

Includes bibliography

Geometric modeling from the medical images in the CAD system to support prosthesis design

This paper presents an individual designing prosthesis for surgical use and proposes a methodology for such design through mathematical extrapolation of data from digital images obtained via tomography of individual patient's bones. Individually tailored prosthesis designed to fit particular patient requirements as accurately as possible should result in more successful reconstruction, enable better planning before surgery and consequently fewer complications during surgery. Fast and accurate design and manufacture of personalized prosthesis for surgical use in bone replacement or reconstruction is potentially feasible through the application and integration of several different existing technologies, which are each at different stages of maturity. Initial case study experiments have been undertaken to validate the research concepts by making dimensional comparisons between a bone and a virtual model produced using the proposed methodology and a future research directions are discussed.

Interventions to promote the wearing of hearing protection

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Simple green approach to reinforce natural rubber with bacterial cellulose nanofibers

Natural rubber (NR) is a renewable polymer with a wide range of applications, which is constantly tailored, further increasing its utilizations. The tensile strength is one of its most important properties susceptible of being enhanced by the simple incorporation of nanofibers. The preparation and characterization of natural-rubber based nanocomposites reinforced with bacterial cellulose (BC) and bacterial cellulose coated with polystyrene (BCPS), yielded high performance materials. The nanocomposites were prepared by a simple and green process, and characterized by tensile tests, dynamical mechanical analysis (DMA), scanning electron microscopy (SEM), and swelling experiments. The effect of the nanofiber content on morphology, static, and dynamic mechanical properties was also investigated. The results showed an increase in the mechanical properties, such as Young's modulus and tensile strength, even with modest nanofiber loadings. © 2013 American Chemical Society.

The physiological demands of table tennis: A review

Although table tennis has a tradition lasting more than 100 years, relatively little is known about players' physiological requirements - especially during competition. In this review we discuss research studies that have led to our current understanding of how the body functions during table tennis training and competition and how this is altered by training. Match and practice analysis of the table tennis game indicates that during intense practice and competition it is predominantly the anaerobic alactic system that is called into play, while the endurance system is relied on to recovery the anaerobic stores used during such effort. It is thus important for coaches to keep in mind that, while the anaerobic alactic system is the most energetic system used during periods of exertion in a table tennis game, a strong capacity for endurance is what helps a player recover quicker for the following match and the next day of competition. This paper provides a review of specific studies that relate to competitive table tennis, and highlights the need for training and research programs tailored to table tennis. © Journal of Sports Science and Medicine.

A coordenação bimanual em função do foco atencional

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Metodologia para adaptação e expansão de conteúdos de programas educativos da TV analógica para a TV digital: estudo de caso: o programa infantil De onde vem?

Pós-graduação em Televisão Digital: Informação e Conhecimento - FAAC

An assessment of green export opportunities for Barbados

Includes bibliography.

The employment situation in Latin America and the Caribbean: Labour productivity and distribution issues

Although the economies of Latin America and the Caribbean grew more slowly in 2011 than in 2010, there were some improvements on the employment front. Workers benefited from the region’s satisfactory economic performance in an increasingly complex international setting. The unemployment rate fell from 7.3% in 2010 to 6.7% in 2011 thanks to a halfpercentage- point gain in the urban employment rate. Both rates are at levels that have not been seen for a long time. The proportion of formal jobs with social benefits rose as well, and underemployment declined. The average wage and the minimum wage both increased in real terms, albeit only moderately. Economic performance and the employment situation varied widely among the subregions. The unemployment rate dropped by 0.6 percentage points in South America but 0.4 percentage points in the countries of the northern part of Latin America. In the countries of the Caribbean, the employment rate was up by 0.2 percentage points. The data show that substantial labour market gaps and serious labour-market insertion issues remain. This is especially the case for women and young people, for whom unemployment rates and other labour indicators are still unfavourable. The second part of this report looks at whether the fruits of economic growth and rising productivity have been distributed equitably between workers and companies. Between 2002 and 2008 (the most recent expansionary economic cycle), wages as a percentage of GDP fell in 13 of the 21 countries of the region for which data are available and rose in just 8. This points to redistribution that is unfavourable to workers, which is worrying in a region which already has the most unequal distribution of income in the world. Underlying this trend is the fact that, worldwide, wages have grown less than productivity. Beyond the ethical dimension of this issue, it jeopardizes the social and economic sustainability of growth. For example, one of the root causes of the recent financial crisis was that households in the United States responded to declining wage income by borrowing more to pay for consumption and housing. This turned out to be unsustainable in the long run. Over time, it undermines the labour market’s contribution to the efficient allocation of resources and its distributive function, too, with negative consequences for democratic governance. Among the triggers of this distributive worsening most often cited in the global debate are market deregulation and its impact on financial globalization, technological change that favours capital over labour, and the weakening of labour institutions. What is needed here is a public policy effort to help keep wage increases from lagging behind increases in productivity. Some countries of the region, especially in South America, saw promising developments during the second half of the 2000s in the form of a positive trend reversal in wages as a percentage of GDP. One example is Brazil, where a minimum wage policy tailored to the dynamics of the domestic market is considered to be one of the factors behind an upturn in the wage share of GDP. The region needs to grow more and better. Productivity must grow at a steady pace, to serve as the basis for sustained improvements in the well-being of the populace and to narrow the gap between the economies of Latin America and the Caribbean and the more advanced economies. And inequality must be decreased; this could be achieved by closing the productivity gap between upgraded companies and the many firms whose productivity is low. As set out in this report, the region made some progress between 2002 and 2010, with labour productivity rising at the rate of 1.5% a year. But this progress falls short of that seen in other regions such as Sub-Saharan Africa (2.1%) and, above all, East Asia (8.3%, not counting Japan and the Republic of Korea). Moreover, in many of the countries of the region these gains have not been distributed equitably. Therein lies a dual challenge that must be addressed: continue to increase productivity while enhancing the mechanisms for distributing gains in a way that will encourage investment and boost worker and household income. The Economic Commission for Latin America and the Caribbean (ECLAC) and the International Labour Organization (ILO) estimate that the pace of economic growth in the region will be slightly slower in 2012 than in 2011, in a global economic scenario marked by the cooling of several of the main economic engines and a high degree of uncertainty concerning, above all, prospects for the euro zone. The region is expected to continue to hold up well to this worsening scenario, thanks to policies that leveraged more favourable conditions in the past. This will be felt in the labour markets, as well, so expectations are that unemployment will edge down by as much as two tenths of a decimal point.

The Caribbean and the post-2015 development agenda

This paper will contend that the post-2015 development agenda presents a major opportunity for Caribbean countries to reverse decades of lagging economic performance and make the transition to balanced, holistic, and people-centred growth and development. The MDGs, while valuable in promoting gains in poverty reduction, health, education, nutrition, and maternal well-being were not tailored to the growth and development needs of the region. This can now be changed by a post-2015 development agenda which goes beyond improving the welfare of citizens by meeting basic needs and enhancing access to primary services. The necessary scaling-up of the MDG framework will require that the sustainable development goals, which will anchor the post- 2015 development agenda, are capable of promoting structural change, competitiveness and output gains while advancing social development and meeting environmental concerns. They must also address the unfinished business of the millennium development goals, primarily in the area of human development.

Migração (2,5-D) com amplitudes verdadeiras em meios com gradiente constante de velocidade

A migração com amplitudes verdadeiras de dados de reflexão sísmica, em profundidade ou em tempo, possibilita que seja obtida uma medida dos coeficientes de reflexão dos chamados eventos de reflexão primária. Estes eventos são constituídos, por exemplo, pelas reflexões de ondas longitudinais P-P em refletores de curvaturas arbitrárias e suaves. Um dos métodos mais conhecido é o chamado migração de Kirchhoff, através do qual a imagem sísmica é produzida pela integração do campo de ondas sísmicas, utilizando-se superfícies de difrações, denominadas de Superfícies de Huygens. A fim de se obter uma estimativa dos coeficientes de reflexão durante a migração, isto é a correção do efeito do espalhamento geométrico, utiliza-se uma função peso no operador integral de migração. A obtenção desta função peso é feita pela solução assintótica da integral em pontos estacionários. Tanto no cálculo dos tempos de trânsito como na determinação da função peso, necessita-se do traçamento de raios, o que torna a migração em situações de forte heterogeneidade da propriedade física um processo com alto custo computacional. Neste trabalho é apresentado um algoritmo de migração em profundidade com amplitudes verdadeiras, para o caso em que se tem uma fonte sísmica pontual, sendo o modelo de velocidades em subsuperfície representado por uma função que varia em duas dimensões, e constante na terceira dimensão. Esta situação, conhecida como modelo dois-e-meio dimensional (2,5-D), possui características típicas de muitas situações de interesse na exploração do petróleo, como é o caso da aquisição de dados sísmicos 2-D com receptores ao longo de uma linha sísmica e fonte sísmica 3-D. Em particular, é dada ênfase ao caso em que a velocidade de propagação da onda sísmica varia linearmente com a profundidade. Outro tópico de grande importância abordado nesse trabalho diz respeito ao método de inversão sísmica denominado empilhamento duplo de difrações. Através do quociente de dois empilhamentos com pesos apropriados, pode-se determinar propriedades físicas e parâmetros geométricos relacionados com a trajetória do raio refletido, os quais podem ser utilizados a posteriori no processamento dos dados sísmicos, visando por exemplo, a análise de amplitudes.

Migração com amplitude verdadeira em meios com gradiente constante de velocidade

Este trabalho tem por objetivo a aplicação de um método de migração com amplitudes verdadeiras, considerando-se um meio acústico onde a velocidade de propagação varia linearmente com a profundidade. O método de migração é baseado na teoria dos raios e na integral de migração de Kirchhoff, procurando posicionar de forma correta os refletores e recuperar os respetivos coeficientes de reflexão. No processo de recuperação dos coeficientes de reflexão, busca-se corrigir o fator de espalhamento geométrico de reflexões sísmicas primárias, sem o conhecimento a priori dos refletores procurados. Ao considerar-se configurações fonte-receptor arbitrárias, as reflexões primárias podem ser imageadas no tempo ou profundidade, sendo as amplitudes do campo de ondas migrado uma medida dos coeficientes de reflexão (função do ângulo de incidência). Anteriormente têm sido propostos alguns algoritmos baseados na aproximação de Born ou Kirchhoff. Todos são dados em forma de um operador integral de empilhamento de difrações, que são aplicados à entrada dos dados sísmicos. O resultado é uma seção sísmica migrada, onde cada ponto de reflexão é imageado com uma amplitude proporcional ao coeficiente de reflexão no ponto. No presente caso, o processo de migração faz uso de um modelo com velocidade que apresenta uma distribuição que varia linearmente com a profundidade, conhecido também como gradiente constante de velocidade. O esquema de migração corresponde a uma versão modificada da migração de empilhamento por difração e faz uso explícito da teoria do raio, por exemplo, na descrição de tempos de trânsito e amplitudes das reflexões primárias, com as quais a operação de empilhamento e suas propriedades podem ser entendidas geometricamente. Efeitos como o espalhamento geométrico devido à trajetória do raio levam a distorção das amplitudes. Estes efeitos têm que ser corregidos durante o processamento dos dados sísmicos. Baseados na integral de migração de Kirchhoff e na teoria paraxial dos raios, foi derivada a função peso e o operador da integral por empilhamento de difrações para um modelo sísmico 2,5-D, e aplicado a uma serie de dados sintéticos em ambientes com ruído e livre de ruído. O resultado mostra a precisão e estabilidade do método de migração em um meio 2,5-D como ferramenta para obter informação sobre as propriedades de refletividade da subsuperfície da terra. Neste método não são levados em consideração a existência de caústicas nem a atenuação devido a fricção interna.

Toxicidade e efeitos subletais de toxinas Cry de Bacillus thuringiensis Berliner em diferentes populações de Plutella xylostella (L.) (Lepidoptera: Plutellidae) em laboratório

Pós-graduação em Agronomia (Entomologia Agrícola) - FCAV