2,852 research outputs found

    Robust self-trapping of vortex beams in a saturable optical medium

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    We report the first observation of robust self-trapping of vortex beams propagating in a uniform condensed medium featuring local saturable self-focusing nonlinearity. Optical vortices with topological charge m=1, that remain self-trapped over ~ 5 Rayleigh lengths, are excited in carbon disulfide using a helical light beam at 532 nm and intensities from 8 to 10 GW/cm^2. At larger intensities, the vortex beams lose their stability, spontaneously breaking into two fragments. Numerical simulations based on the nonlinear Schr\"odinger equation including the three-photon absorption and nonpolynomial saturation of the refractive nonlinearity demonstrate close agreement with the experimental findings.Comment: 27 pages, 7 figures,to be published in Phys. Rev. A (2016

    Enabling Future Sustainability Transitions: An Urban Metabolism Approach to Los Angeles Pincetl et al. Enabling Future Sustainability Transitions

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    Summary: This synthesis article presents an overview of an urban metabolism (UM) approach using mixed methods and multiple sources of data for Los Angeles, California. We examine electric energy use in buildings and greenhouse gas emissions from electricity, and calculate embedded infrastructure life cycle effects, water use and solid waste streams in an attempt to better understand the urban flows and sinks in the Los Angeles region (city and county). This quantification is being conducted to help policy-makers better target energy conservation and efficiency programs, pinpoint best locations for distributed solar generation, and support the development of policies for greater environmental sustainability. It provides a framework to which many more UM flows can be added to create greater understanding of the study area's resource dependencies. Going forward, together with policy analysis, UM can help untangle the complex intertwined resource dependencies that cities must address as they attempt to increase their environmental sustainability

    Dispersión de juveniles de Cigüeña Blanca (Ciconia ciconia) en Córdoba (S de España)

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    D'un total de 91 cigonyes blanques marcades amb anelles de PVC a la província de Córdova entre 1990-1993 sis van ser localitzades com a nidificants a la mateixa àrea entre 1991 i 1994. Altres tres exemplars es van trobar a les províncies veïnes de Sevilla, Huelva i Ciutat Reial. La distància mitjana des del lloc de naixement al de nidificació fou 80,7 km (s.d.=81,8, n=13, distància màxima= 250 km, mínima= 0). Aquests resultats suggereixen que l'augment detectat en les poblacions nidificants de cigonya blanca de Córdova i altres llocs d'Espanya podria estar relacionat amb una baixa mortalitat dels juvenils que retornen a criar prop de les seves àrees de naixement

    Brain activation covaries with reported criminal behaviors when making risky choices: A fuzzy-trace theory approach

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    This is the author accepted manuscript. The final version is available from the American Psychological Association via the DOI in this record.Criminal behavior has been associated with abnormal neural activity when people experience risks and rewards or exercise inhibition. However, neural substrates of mental representations that underlie criminal and noncriminal risk-taking in adulthood have received scant attention. We take a new approach, applying fuzzy-trace theory, to examine neural substrates of risk preferences and criminality. We extend ideas about gist (simple meaning) and verbatim (precise risk-reward tradeoffs) representations used to explain adolescent risk-taking to uncover neural correlates of developmentally inappropriate adult risk-taking. We tested predictions using a risky-choice framing task completed in the MRI scanner, and examined neural covariation with self-reported criminal and noncriminal risk-taking. As predicted, risk-taking was correlated with a behavioral pattern of risk preferences called “reverse framing” (preferring sure losses over a risky option and a risky option over sure gains, the opposite of typical framing biases) that has been linked to risky behavior in adolescents and is rarely observed in nondisordered adults. Experimental manipulations confirmed processing interpretations of typical framing (gist-based) and reverse-framing (verbatim-based) risk preferences. In the brain, covariation with criminal and noncriminal risk-taking was observed predominantly when subjects made reverse-framing choices. Noncriminal risk-taking behavior was associated with emotional reactivity (amygdala) and reward motivation (striatal) areas, whereas criminal behavior was associated with greater activation in temporal and parietal cortices, their junction, and insula. When subjects made more developmentally typical framing choices, reflecting non-preferred gist processing, activation in dorsolateral prefrontal cortex covaried with criminal risk-taking, which may reflect cognitive effort to process gist while inhibiting preferred verbatim processin

    Human bony labyrinth is an indicator of population history and dispersal from Africa.

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    The dispersal of modern humans from Africa is now well documented with genetic data that track population history, as well as gene flow between populations. Phenetic skeletal data, such as cranial and pelvic morphologies, also exhibit a dispersal-from-Africa signal, which, however, tends to be blurred by the effects of local adaptation and in vivo phenotypic plasticity, and that is often deteriorated by postmortem damage to skeletal remains. These complexities raise the question of which skeletal structures most effectively track neutral population history. The cavity system of the inner ear (the so-called bony labyrinth) is a good candidate structure for such analyses. It is already fully formed by birth, which minimizes postnatal phenotypic plasticity, and it is generally well preserved in archaeological samples. Here we use morphometric data of the bony labyrinth to show that it is a surprisingly good marker of the global dispersal of modern humans from Africa. Labyrinthine morphology tracks genetic distances and geography in accordance with an isolation-by-distance model with dispersal from Africa. Our data further indicate that the neutral-like pattern of variation is compatible with stabilizing selection on labyrinth morphology. Given the increasingly important role of the petrous bone for ancient DNA recovery from archaeological specimens, we encourage researchers to acquire 3D morphological data of the inner ear structures before any invasive sampling. Such data will constitute an important archive of phenotypic variation in present and past populations, and will permit individual-based genotype-phenotype comparisons

    Situación y perspectivas de la truficultura en España

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    En este trabajo se presenta un panorama de la situación de la truficultura en España, desde sus comienzos en los años 50 a la actualidad, y sus perspectivas de futuro. Se destacan la actividad científica y técnica, desarrolladas en Centros de Investigación y Universidades españolas, en aspectos diversos: micorrización en vivero, certificación de planta micorrizada, ecología de la trufa, recuperación de truferas naturales, cultivo y seguimiento de plantaciones truferas, taxonomía química, control de las especies de trufa, reforestación y selvicultura trufera. Se aprecia un aumento en el apoyo que se le da al sector desde las Administraciones Públicas, tanto desde la perspectiva forestal, la agraria o la, ya indicada, de la investigación. Se aportan datos de produccion, precios, áreas de recogida, mercados, investigación, plantaciones truferas. Se da un breve resumen de las perspectivas del sector trufero en España. SUMMARY The objective of this work is to provide a overview of truffle cultivation in Spain from its beginnings in the 1950s to the present, and its prospects for the future. At the moment, truffle cultivation in Spain is a reality. There is a great deal of activity on the part of farmers as well as on the part of scientific researchers in universities and specialised centres who are investigating a wide range of aspects on the subject: mycorrhization in nurseries, mycorrhized plant certification, ecology, recuperation of wild truffle stands, monitoring of truffle plantations, chemical taxonomy, control of truffle species, and reforestation and truffle cultivation. A growing support for the truffle sector from the Public Administration can be observed, as much from the agrarian and forestry perspective as from the mentioned research perspective. Data on production, prices, collection areas, markets, publications, truffle plantations and research are given. Finally, we give a brief summary of future prospects for the truffle sector in Spain

    Diagnostic criterion for crystallized beams

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    Small ion crystals in a Paul trap are stable even in the absence of laser cooling. Based on this theoretically and experimentally well-established fact we propose the following diagnostic criterion for establishing the presence of a crystallized beam: Absence of heating following the shut-down of all cooling devices. The validity of the criterion is checked with the help of detailed numerical simulations.Comment: REVTeX, 11 pages, 4 figures; submitted to PR

    Exploration Medical System Demonstration Project

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    A near-Earth Asteroid (NEA) mission will present significant new challenges including hazards to crew health created by exploring a beyond low earth orbit destination, traversing the terrain of asteroid surfaces, and the effects of variable gravity environments. Limited communications with ground-based personnel for diagnosis and consultation of medical events require increased crew autonomy when diagnosing conditions, creating treatment plans, and executing procedures. Scope: The Exploration Medical System Demonstration (EMSD) project will be a test bed on the International Space Station (ISS) to show an end-to-end medical system assisting the Crew Medical Officers (CMO) in optimizing medical care delivery and medical data management during a mission. NEA medical care challenges include resource and resupply constraints limiting the extent to which medical conditions can be treated, inability to evacuate to Earth during many mission phases, and rendering of medical care by a non-clinician. The system demonstrates the integration of medical technologies and medical informatics tools for managing evidence and decision making. Project Objectives: The objectives of the EMSD project are to: a) Reduce and possibly eliminate the time required for a crewmember and ground personnel to manage medical data from one application to another. b) Demonstrate crewmember's ability to access medical data/information via a software solution to assist/aid in the treatment of a medical condition. c) Develop a common data management architecture that can be ubiquitously used to automate repetitive data collection, management, and communications tasks for all crew health and life sciences activities. d) Develop a common data management architecture that allows for scalability, extensibility, and interoperability of data sources and data users. e) Lower total cost of ownership for development and sustainment of peripheral hardware and software that use EMSD for data management f) Provide better crew health via the reduction in crew errors, crew time, and ground time
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