247 research outputs found

    Identification of potential “Remedies” for Air Pollution (nitrogen) Impacts on Designated Sites (RAPIDS)

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    Atmospheric nitrogen (N) deposition is a significant threat to semi-natural habitats and species in the UK, resulting in on-going erosion of habitat quality and declines in many species of high conservation value. The project focused on impacts and remedies for designated conservation sites, especially Natura 2000 sites protected under the EU Habitats Directive. However, the approach and certainly the measures could be equally applied to other areas of high conservation value. Evidence was drawn together to develop a framework for identifying key N threats at individual sites as a basis to target mitigation options in the context of potential legislative, voluntary and financial instruments

    The Prevalence of Sex Trafficking of Children and Adolescents in the United States: A Scoping Review

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    Topic: This scoping review investigated research regarding the magnitude of minor sex trafficking (domestic minor sex trafficking and/or commercial sexual exploitation of children) in the United States, summarizing estimates, methodologies, and strengths and weaknesses of the studies. Method: Using Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, peer-reviewed articles and the gray literature were accessed via databases searches, reference harvesting, and expert advice. Articles were included if they provided a count or prevalence proportion estimate of trafficked or at-risk minors across or within a region of the United States. Six empirical studies, published from 1999 to 2017, were included in the review. Results: Included studies produced count estimates (n = 3) or prevalence proportion estimates (n = 3) for youth at risk of minor sex trafficking (n = 2) or reporting victimization (n = 5). Studies examined sex trafficking risk and victimization in different geographical areas, including across the United States (n = 2), in New York City (n = 1), and in Ohio (n = 1). Further, several studies focused on particular populations, such as street and shelter youths (n = 1) and adjudicated males (n = 1). Sampling methodologies of reviewed estimates included traditional random sampling (n = 1), nationally representative sampling (n = 2), convenience sampling (n = 1), respondent-driven sampling (n = 1), purposive sampling (n = 1), and use of census data (n = 2). Conclusion: Little research has estimated the prevalence of minor sex trafficking in the United States. The existing studies examine different areas and populations and use different categories to estimate the problem. The estimates reviewed here should be cited cautiously. Future research is needed on this important topic, including methodologies to produce more representative estimates of this hard-to-reach population

    Dynamical mean-field theory of spiking neuron ensembles: response to a single spike with independent noises

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    Dynamics of an ensemble of NN-unit FitzHugh-Nagumo (FN) neurons subject to white noises has been studied by using a semi-analytical dynamical mean-field (DMF) theory in which the original 2N2 N-dimensional {\it stochastic} differential equations are replaced by 8-dimensional {\it deterministic} differential equations expressed in terms of moments of local and global variables. Our DMF theory, which assumes weak noises and the Gaussian distribution of state variables, goes beyond weak couplings among constituent neurons. By using the expression for the firing probability due to an applied single spike, we have discussed effects of noises, synaptic couplings and the size of the ensemble on the spike timing precision, which is shown to be improved by increasing the size of the neuron ensemble, even when there are no couplings among neurons. When the coupling is introduced, neurons in ensembles respond to an input spike with a partial synchronization. DMF theory is extended to a large cluster which can be divided into multiple sub-clusters according to their functions. A model calculation has shown that when the noise intensity is moderate, the spike propagation with a fairly precise timing is possible among noisy sub-clusters with feed-forward couplings, as in the synfire chain. Results calculated by our DMF theory are nicely compared to those obtained by direct simulations. A comparison of DMF theory with the conventional moment method is also discussed.Comment: 29 pages, 2 figures; augmented the text and added Appendice

    Simulations of the Static Friction Due to Adsorbed Molecules

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    The static friction between crystalline surfaces separated by a molecularly thin layer of adsorbed molecules is calculated using molecular dynamics simulations. These molecules naturally lead to a finite static friction that is consistent with macroscopic friction laws. Crystalline alignment, sliding direction, and the number of adsorbed molecules are not controlled in most experiments and are shown to have little effect on the friction. Temperature, molecular geometry and interaction potentials can have larger effects on friction. The observed trends in friction can be understood in terms of a simple hard sphere model.Comment: 13 pages, 13 figure

    The evolution of language: a comparative review

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    For many years the evolution of language has been seen as a disreputable topic, mired in fanciful "just so stories" about language origins. However, in the last decade a new synthesis of modern linguistics, cognitive neuroscience and neo-Darwinian evolutionary theory has begun to make important contributions to our understanding of the biology and evolution of language. I review some of this recent progress, focusing on the value of the comparative method, which uses data from animal species to draw inferences about language evolution. Discussing speech first, I show how data concerning a wide variety of species, from monkeys to birds, can increase our understanding of the anatomical and neural mechanisms underlying human spoken language, and how bird and whale song provide insights into the ultimate evolutionary function of language. I discuss the ‘‘descended larynx’ ’ of humans, a peculiar adaptation for speech that has received much attention in the past, which despite earlier claims is not uniquely human. Then I will turn to the neural mechanisms underlying spoken language, pointing out the difficulties animals apparently experience in perceiving hierarchical structure in sounds, and stressing the importance of vocal imitation in the evolution of a spoken language. Turning to ultimate function, I suggest that communication among kin (especially between parents and offspring) played a crucial but neglected role in driving language evolution. Finally, I briefly discuss phylogeny, discussing hypotheses that offer plausible routes to human language from a non-linguistic chimp-like ancestor. I conclude that comparative data from living animals will be key to developing a richer, more interdisciplinary understanding of our most distinctively human trait: language
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