64 research outputs found

    Efficient numerical description of the dynamics of interacting multispecies quantum gases

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    We present a highly efficient method for the numerical solution of coupled Gross-Pitaevskii equations describing the evolution dynamics of a multi-species mixture of Bose-Einstein condensates in time-dependent potentials. This method, based on a moving and expanding reference frame, compares favorably to a more standard but much more computationally expensive solution based on a frozen frame. It allows an accurate description of the long-time behavior of interacting, multi-species quantum mixtures including the challenging problem of long free expansions relevant to microgravity and space experiments. We demonstrate a successful comparison to experimental measurements of a binary Rb-K mixture recently performed with the payload of a sounding rocket experiment

    Quantum Gas Mixtures and Dual-Species Atom Interferometry in Space

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    The capability to reach ultracold atomic temperatures in compact instruments has recently been extended into space. Ultracold temperatures amplify quantum effects, while free-fall allows further cooling and longer interactions time with gravity - the final force without a quantum description. On Earth, these devices have produced macroscopic quantum phenomena such as Bose-Einstein condensation (BECs), superfluidity, and strongly interacting quantum gases. Quantum sensors interfering the superposition of two ultracold atomic isotopes have tested the Universality of Free Fall (UFF), a core tenet of Einstein's classical gravitational theory, at the 101210^{-12} level. In space, cooling the elements needed to explore the rich physics of strong interactions and preparing the multiple species required for quantum tests of the UFF has remained elusive. Here, utilizing upgraded capabilities of the multi-user Cold Atom Lab (CAL) instrument within the International Space Station (ISS), we report the first simultaneous production of a dual species Bose-Einstein condensate in space (formed from 87^{87}Rb and 41^{41}K), observation of interspecies interactions, as well as the production of 39^{39}K ultracold gases. We have further achieved the first space-borne demonstration of simultaneous atom interferometry with two atomic species (87^{87}Rb and 41^{41}K). These results are an important step towards quantum tests of UFF in space, and will allow scientists to investigate aspects of few-body physics, quantum chemistry, and fundamental physics in novel regimes without the perturbing asymmetry of gravity

    Economic benefits of methylmercury exposure control in Europe : monetary value of neurotoxicity prevention

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    © 2013 Bellanger et al.; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.Background: Due to global mercury pollution and the adverse health effects of prenatal exposure to methylmercury (MeHg), an assessment of the economic benefits of prevented developmental neurotoxicity is necessary for any cost-benefit analysis. Methods: Distributions of hair-Hg concentrations among women of reproductive age were obtained from the DEMOCOPHES project (1,875 subjects in 17 countries) and literature data (6,820 subjects from 8 countries). The exposures were assumed to comply with log-normal distributions. Neurotoxicity effects were estimated from a linear dose-response function with a slope of 0.465 Intelligence Quotient (IQ) point reduction per μg/g increase in the maternal hair-Hg concentration during pregnancy, assuming no deficits below a hair-Hg limit of 0.58 μg/g thought to be safe. A logarithmic IQ response was used in sensitivity analyses. The estimated IQ benefit cost was based on lifetime income, adjusted for purchasing power parity. Results: The hair-mercury concentrations were the highest in Southern Europe and lowest in Eastern Europe. The results suggest that, within the EU, more than 1.8 million children are born every year with MeHg exposures above the limit of 0.58 μg/g, and about 200,000 births exceed a higher limit of 2.5 μg/g proposed by the World Health Organization (WHO). The total annual benefits of exposure prevention within the EU were estimated at more than 600,000 IQ points per year, corresponding to a total economic benefit between €8,000 million and €9,000 million per year. About four-fold higher values were obtained when using the logarithmic response function, while adjustment for productivity resulted in slightly lower total benefits. These calculations do not include the less tangible advantages of protecting brain development against neurotoxicity or any other adverse effects. Conclusions: These estimates document that efforts to combat mercury pollution and to reduce MeHg exposures will have very substantial economic benefits in Europe, mainly in southern countries. Some data may not be entirely representative, some countries were not covered, and anticipated changes in mercury pollution all suggest a need for extended biomonitoring of human MeHg exposure.Exposure data were contributed from the DEMOCOPHES project (LIFE09 ENV/BE/000410) carried out thanks to joint financing of 50% from the European Commission programme LIFE + along with 50% from each participating country (see the national implementation websites accessible via http://www.eu-hbm.info/democophes/project-partners). Special thanks go to the national implementation teams. The COPHES project that provided the operational and scientific framework was funded by the European Community's Seventh Framework Programme - DG Research (Grant Agreement Number 244237). Additional exposure data were supported by the PHIME project (FOOD-CT-2006-016253) and ArcRisk (GA 226534). We are grateful to Yue Gao and colleagues for sharing Flanders exposure data from the Flemish Center of Expertise on Environment and Health, financed and steered by the Ministry of the Flemish Community. National exposure data from the 2006–2007 French national survey on nutrition and health (Etude Nationale Nutrition Santé) were made available by Nadine Fréry, French Institute for Public Health Surveillance. Data from the Norwegian Mother and Child Cohort Study (a validation sample) were kindly provided by Anne Lise Brantsæter, National Institute of Public Health, Oslo. The UK mercury data were obtained from the ALSPAC pregnancy blood analyses carried out at the Centers for Disease Control and Prevention with funding from NOAA (the US National Oceanographic and Atmospheric Administration). The studies in the Faroe Islands were supported by the US National Institutes of Health (ES009797 and ES012199). The contents of this paper are solely the responsibility of the authors and do not necessarily represent the official views of the funding agencies

    Childhood lead exposure in France: benefit estimation and partial cost-benefit analysis of lead hazard control

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    <p>Abstract</p> <p>Background</p> <p>Lead exposure remains a public health concern due to its serious adverse effects, such as cognitive and behavioral impairment: children younger than six years of age being the most vulnerable population. In Europe, the lead-related economic impacts have not been examined in detail. We estimate the annual costs in France due to childhood exposure and, through a cost benefit analysis (CBA), aim to assess the expected social and economic benefits of exposure abatement.</p> <p>Methods</p> <p>Monetary benefits were assessed in terms of avoided national costs. We used results from a 2008 survey on blood-lead (B-Pb) concentrations in French children aged one to six years old. Given the absence of a threshold concentration being established, we performed a sensitivity analysis assuming different hypothetical threshold values for toxicity above 15 μg/L, 24 μg/L and 100 μg/L. Adverse health outcomes of lead exposure were translated into social burden and economic costs based on literature data from literature. Direct health benefits, social benefits and intangible avoided costs were included. Costs of pollutant exposure control were partially estimated in regard to homes lead-based paint decontamination, investments aiming at reducing industrial lead emissions and removal of all lead drinking water pipes.</p> <p>Results</p> <p>The following overall annual benefits for the three hypothetical thresholds values in 2008 are: €22.72 billion, €10.72 billion and €0.44 billion, respectively. Costs from abatement ranged from €0.9 billion to 2.95 billion/year. Finally, from a partial CBA of lead control in soils and dust the estimates of total net benefits were € 3.78 billion, € 1.88 billion and €0.25 billion respectively for the three hypothesized B-Pb effect values.</p> <p>Conclusions</p> <p>Prevention of childhood lead exposure has a high social benefit, due to reduction of B-Pb concentrations to levels below 15 μg/L or 24 μg/L, respectively. Reducing only exposures above 100 μg/L B-Pb has little economic impact due to the small number of children who now exhibit such high exposure levels. Prudent public policies would help avoiding future medical interventions, limit the need for special education and increase future productivity, and hence lifetime income for children exposed to lead.</p

    Les vins effervescents au Royaume-Uni

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    National audienc

    Méthodes récursives

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    PUF, Pari
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