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Recent developments in nanotechnology, especially in the area of nanoclay composites, are improving the technical performance of biobased polymers and moving them toward technical and economic competitiveness with petroleum‐based polymers and conventional composites. We assess whether these developments also improve the environmental sustainability of biopolymers, by using a life cycle approach. We estimate energy use and emissions from the nanoclay production process and compare these with prior life cycle data for biopolymers as well as other fibers, and we find that nanoclay production results in lower energy use and greenhouse gas emissions than production of many common biopolymers and glass fibers. Nanoclay composites hence can improve the life cycle environmental performance of several common biopolymers. However, for some biopolymers the relative performance depends on the functional unit.  相似文献   

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This paper exploits three rounds of panel data provided by the Peruvian dataset of the Young Lives study to investigate the relationship between child cognition and obesity status among the poor. Child weight status is measured by a full distribution of child weight, from severely thin to obese, using data from a z-score for body mass index and cognition is measured by the Spanish version of the Picture Peabody Vocabulary Test (PPVT). This relationship is studied at age five and age eight (school age), and disaggregated across socioeconomic factors of gender, urban/rural setting and indigenous/nonindigenous status. The initial results suggests that obese children have higher cognitive scores and that this result is driven by those who are female, non-indigenous and live in an urban region. However, after correcting for possible bias due to unobservable heterogeneity, there is little evidence of this relationship. The one exception is for a weakly significant relationship between obese female children and higher cognition, a relationship which tends to weaken between the ages of five and eight. On the other end of the weight distribution, indigenous children who are severely thin or thin have significantly lower cognitive scores, a relationship that holds after correcting for possible bias and appears to strengthen between ages of five and eight. This paper contributes to a very small set of literature on child cognition and obesity, points to the importance of controlling for unobserved heterogeneity in estimation, and is the first of its kind to study this relationship in a developing country.  相似文献   

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BACKGROUND TO THE DEBATE: In many countries, the number of patients waiting for a kidney transplant is increasing. But there is a widespread and serious shortage of kidneys for transplantation, a shortage that can lead to suffering and death. One approach to tackling the shortage is for a patient with renal disease to buy a kidney from a living donor, who is often in a developing country, a sale that could--in theory at least--help to lift the donor out of poverty. Such kidney sales are almost universally illegal. Proponents of kidney sales argue that since the practice is widespread, it would be safer to formally regulate it, and that society should respect people's autonomous control over their bodies. Critics express concern about the potential for exploitation and coercion of the poor, and about the psychological and physical after-effects on the donors of this illegal kidney trade.  相似文献   

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Contrary to conventional wisdom, NHANES data indicate that the poor have never had a statistically significant higher prevalence of overweight status at any time in the last 35 years. Despite this empirical evidence, the view that the poor are less healthy in terms of excess accumulation of fat persists. This paper provides evidence that conventional wisdom is reflecting important differences in the relationship between income and the body mass index. The first finding is based on distribution-sensitive measures of overweight which indicates that the severity of overweight has been higher for the poor than the nonpoor throughout the last 35 years. The second finding is from a newly introduced estimator, unconditional quantile regression (UQR), which provides a measure of the income-gradient in BMI at different points on the unconditional BMI distribution. The UQR estimator indicates that the strongest relationship between income and BMI is observed at the tails of the distribution. There is a statistically significant negative income gradient in BMI at the obesity threshold and some evidence of a positive gradient at the underweight threshold. Both of these UQR estimates imply that for those at the tails of the BMI distribution, increases in income are correlated with healthier BMI values.  相似文献   

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Anthropologists and demographers have devoted considerable attention to testing the fertility-polygyny hypothesis, which posits that polygynously married women have lower fertility than their monogamously married counterparts. Much less attention has been paid to the potential impact of polygynous marriages on the health and well-being of children. The objective of this paper was to assess whether polygynous marital status is a risk factor for poor nutritional status and growth performance among a cohort of young Tanzanian children. Using data collected from both wet and dry season periods, we tested for an association from both cross-sectional and longitudinal perspectives. Despite relatively high nutritional status compared to other agropastoralists and horticultural populations, as well as the presence of various socioecological factors that were expected to mitigate any "costs" to polygynous marriage, we found that among our target population, polygynous marital status is a risk factor for poor growth performance. This association is most pronounced in the wet season, and maintains even after allowing for the potential influences of child age and sex, and household characteristics. These results counter our original expectation, and suggest that polygyny is costly to children in this population; this does not appear to be the result of difference in early child environment or household wealth.  相似文献   

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This commentary articulates three perspectives on race in America: economic determinism, institutionalism and a field-theoretic approach. It argues that William Julius Wilson's masterwork, The Declining Significance of Race, was informed by the first and anticipated the latter two. Wilson's most profound and enduring legacy is his unwavering concern for the dispossessed.  相似文献   

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It is tempting to use standard protonation states for the analysis of protein-ligand interactions. Two different pK(a) calculation methods, PROPKA (protein pK(a)) and MCCE (multi conformation continuum electrostatics), were applied to challenge this convenient behavior. As data basis, we selected five recently approved drugs for which structural information of the protein-drug complex is available. We analyzed the pK(a) calculations in terms of a measure termed BIPS (binary protonation states) recently introduced by us. Both methods agree in detecting the majority of the sites with atypical BIPS values. However, when using only one method, some of the atypcial BIPS value would have been missed. Therefore, we recommend using both methods to set such an interpretation on a solid basis.  相似文献   

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'Statins' are 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors - oral cholesterol-lowering drugs that are used to treat hypercholesterolaemia. It is widely accepted that statins have anti-inflammatory effects that are independent of their ability to lower cholesterol. Animal studies and observational clinical studies have indicated that statins might also be effective in treating certain neurological diseases - in particular, multiple sclerosis, Alzheimer's disease and ischaemic stroke. At present, however, results from ongoing prospective, randomized clinical trials are not available.  相似文献   

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In this essay, I defend a bi-constructivist approach to ethology—a constructivist ethology assuming that each animal adopts constructivist strategies. I put it in opposition to what I call a realist-Cartesian approach, which is currently the dominant approach to ethology and comparative psychology. The starting point of the bi-constructivist approach can be formulated as a shift from the classical Aristotelian question “What is an animal?” to the Spinozean question, which is much less classical but which seems to me to be much stronger: “What are the capacities of the animal?”. Is it possible to conceptualize an ethology which insists on interpretation and therefore on invention, innovation and creativity, rather than on causality, the monotony of behavioural routines, and/or genetic or environmental determination? Such an ethology would be based not on the fiction of an absent observer but on fully recognizing the necessity of an observer, who is effectively present in order to get an observation. A pluralistic ethology does not dissociate itself from the marginal epistemologies of practitioners like animal trainers, hunters, stockbreeders etc., or, moreover, non-western experts. An ethology of this kind is not clamped within the boundaries of purely academic epistemology, obsessed by demarcation lines between the human and the animal. My work on the bi-constructivist approach represents a contribution towards the elaboration of an authentically biosemiotic ethology, one which is significantly different from the mechanical ethology of today.  相似文献   

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This paper examines whether low income is a barrier to contraceptive use in Pakistan, a country in which economic conditions are deteriorating at a time when the private sector is becoming a more important supplier of contraception. Multivariate regression analysis performed using the Pakistan Contraceptive Demand Survey suggests that low income is a deterrent to modern contraceptive use in Pakistan. This is particularly the case for contraceptive methods supplied through the private sector. It is concluded that, if the aim of family planning programmes is to reach low-income people, the prices of contraceptives supplied through the private sector should be kept as low as possible.  相似文献   

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Malnutrition, poor health, hunger, and even starvation are still the world's greatest challenges. Malnutrition is defined as deficiency of nutrition due to not ingesting the proper amounts of nutrients by simply not eating enough food and/or by consuming nutrient-poor food in respect to the daily nutritional requirements. Moreover, malnutrition and disease are closely associated and incidences of such diet-related diseases increase particularly in low- and middle-income states. While foods of animal origin are often unaffordable to low-income families, various neglected crops can offer an alternative source of micronutrients, vitamins, as well as health-promoting secondary plant metabolites. Therefore, agricultural and horticultural research should develop strategies not only to produce more food, but also to improve access to more nutritious food. In this context, one promising approach is to promote biodiversity in the dietary pattern of low-income people by getting access to nutritional as well as affordable food and providing recommendations for food selection and preparation. Worldwide, a multitude of various plant species are assigned to be consumed as grains, vegetables, and fruits, but only a limited number of these species are used as commercial cash crops. Consequently, numerous neglected and underutilized species offer the potential to diversify not only the human diet, but also increase food production levels, and, thus, enable more sustainable and resilient agro- and horti-food systems. To exploit the potential of neglected plant (NP) species, coordinated approaches on the local, regional, and international level have to be integrated that consequently demand the involvement of numerous multi-stakeholders. Thus, the objective of the present review is to evaluate whether NP species are important as “Future Food” for improving the nutritional status of humans as well as increasing resilience of agro- and horti-food systems.  相似文献   

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Over the last two decades, macroecology – the analysis of large‐scale, multi‐species ecological patterns and processes – has established itself as a major line of biological research. Analyses of statistical links between environmental variables and biotic responses have long and successfully been employed as a main approach, but new developments are due to be utilized. Scanning the horizon of macroecology, we identified four challenges that will probably play a major role in the future. We support our claims by examples and bibliographic analyses. 1) Integrating the past into macroecological analyses, e.g. by using paleontological or phylogenetic information or by applying methods from historical biogeography, will sharpen our understanding of the underlying reasons for contemporary patterns. 2) Explicit consideration of the local processes that lead to the observed larger‐scale patterns is necessary to understand the fine‐grain variability found in nature, and will enable better prediction of future patterns (e.g. under environmental change conditions). 3) Macroecology is dependent on large‐scale, high quality data from a broad spectrum of taxa and regions. More available data sources need to be tapped and new, small‐grain large‐extent data need to be collected. 4) Although macroecology already lead to mainstreaming cutting‐edge statistical analysis techniques, we find that more sophisticated methods are needed to account for the biases inherent to sampling at large scale. Bayesian methods may be particularly suitable to address these challenges. To continue the vigorous development of the macroecological research agenda, it is time to address these challenges and to avoid becoming too complacent with current achievements.  相似文献   

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