2,506 research outputs found

    The inter-generational persistence of child labor

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    The authors use the"Pesquisa Nacional por Amostragem a Domicilio"(PNAD) data for Brazil. Their paper asks two related questions. First, does the child labor status of parents impact the child labor incidence of their children? The authors find strong evidence that it does. Second, is this link only a function of permanent family income or is there a direct link between the child labor status of the parents, and their children? They find evidence that such a direct link exists. This complements their previous research (Emerson and Souza 2002) in which they went on to ask if a person works as a child, would this increase the probability of his, or her child working by more than what can be explained, by the fact that the person will be poor as an adult (by virtue of having been a child worker), and therefore compelled to send the child to work? The answer to this is also yes. Hence, the presence of social factors can cause the perpetuation of child labor through non-income channels. It is, for instance, possible that having been a child laborer oneself, affects one's social norms, and attitude to child labor (Basu 1999, Lopez-Calva 2002), such that one is more prone to send ones'own child to work.

    Nonstationarities in the occurrence rates of flood events in Portuguese watersheds

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    An exploratory analysis on the variability of flood occurrence rates in 10 Portuguese watersheds is made, to ascertain if that variability is concurrent with the principle of stationarity. A peaks-over-threshold (POT) sampling technique is applied to 10 long series of mean daily streamflows and to 4 long series of daily rainfall in order to sample the times of occurrence (POT time data) of the peak values of those series. The kernel occurrence rate estimator, coupled with a bootstrap approach, was applied to the POT time data to obtain the time dependent estimated occurrence rate curves, λ<span style="position: relative; margin-left: -0.45em; top: -0.3em;">ˆ</span>(<i>t</i>), of floods and extreme rainfall events. The results of the analysis show that the occurrence of those events constitutes an inhomogeneous Poisson process, hence the occurrence rates are nonstationary. An attempt was made to assess whether the North Atlantic Oscillation (NAO) casted any influence on the occurrence rate of floods in the study area. Although further research is warranted, it was found that years with a less-than-average occurrence of floods tend to occur when the winter NAO is in the positive phase, and years with a higher occurrence of floods (more than twice the average) tend to occur when the winter NAO is in the negative phase. Although the number of analyzed watersheds and their uneven spatial distribution hinders the generalization of the findings to the country scale, the authors conclude that the mathematical formulation of the flood frequency models relying on stationarity commonly employed in Portugal should be revised in order to account for possible nonstationarities in the occurrence rates of such events

    Extreme mechanical resilience of self-assembled nanolabyrinthine materials

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    Low-density materials with tailorable properties have attracted attention for decades, yet stiff materials that can resiliently tolerate extreme forces and deformation while being manufactured at large scales have remained a rare find. Designs inspired by nature, such as hierarchical composites and atomic lattice-mimicking architectures, have achieved optimal combinations of mechanical properties but suffer from limited mechanical tunability, limited long-term stability, and low-throughput volumes that stem from limitations in additive manufacturing techniques. Based on natural self-assembly of polymeric emulsions via spinodal decomposition, here we demonstrate a concept for the scalable fabrication of nonperiodic, shell-based ceramic materials with ultralow densities, possessing features on the order of tens of nanometers and sample volumes on the order of cubic centimeters. Guided by simulations of separation processes, we numerically show that the curvature of self-assembled shells can produce close to optimal stiffness scaling with density, and we experimentally demonstrate that a carefully chosen combination of topology, geometry, and base material results in superior mechanical resilience in the architected product. Our approach provides a pathway to harnessing self-assembly methods in the design and scalable fabrication of beyond-periodic and nonbeam-based nano-architected materials with simultaneous directional tunability, high stiffness, and unsurpassed recoverability with marginal deterioration

    The Role of the Family in Immigrants' Labor-Market Activity: Evidence from the United States

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    We use Census of Population microdata for 1980 and 1990 to examine the labor supply and wages of immigrant husbands and wives in the United States in a family context. Earlier research by Baker and Benjamin (1997) posits a family investment model in which, upon arrival, immigrant husbands invest in their human capital while immigrant wives work to provide the family with liquidity during this period. Consistent with this model, they find for Canada that immigrant wives work longer hours upon arrival than comparable natives, but, with time in Canada, they are eventually overtaken by native wives. In contrast, we find that, among immigrants to the United States, both husbands and wives work and earn less than comparable natives upon arrival, with similar shortfalls for men and women. Further, both immigrant husbands and wives have similar, positive assimilation profiles in wages and labor supply and eventually overtake both the wages and the labor supply of comparable natives.

    Stress Analysis on a “L” shape Truss Optimization

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    The metal construction market in Brazil has grown significantly over the past few years. The weight reductions and performance increase of mechanical pieces obtained by using optimization techniques are significant to the point that currently its use is critical to define that competitiveness of the metal-mechanical engineering industries, and its undeniable importance in reducing costs. The optimization applied in the mechanical part design consists of using computational methods for dimensions, shape or optimal topology of parts. This study aims to propose a study methodology to analyse the stress distribution thought the use of mathematical software and photoelasticity techniques, to propose a new structural profile, lighter and more efficient, which may be used as solution to overcome the current constructive limitations

    Transdisciplinarity in strategic decisions for oncological treatments

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    The current models for equity and access to new oncological treatments are under strain due to the economic and demographic crisis in Europe as well as the rising costs of innovative drugs. Cancer treatment needs a model of patient-centered care in which an interdisciplinary care plan, based on evidence-based practice is essential for patient wellbeing. Physicians should be focused in the doctor-patient relationship and informed consent is important, especially when new medicines are prescribed. Related with informed consent, there is therapeutic privilege. Moreover, utilitarianism and social justice have to be considered without compromising human dignity and the principle of economy cannot be ignored in the provision of public services. An interdisciplinary approach is essential for the new oncological drugs approval. Therefore, transdisciplinary decision between civil society, pharmaceuticals, healthcare professionals and policy makers is essential in order to assure quality, access to innovation and equity in oncological care.info:eu-repo/semantics/acceptedVersio
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