158 research outputs found

    Sub-Doppler laser cooling of 40K with Raman gray molasses on the D2 line

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    Gray molasses is a powerful tool for sub-Doppler laser cooling of atoms to low temperatures. For alkaline atoms, this technique is commonly implemented with cooling lasers which are blue-detuned from either the D1 or D2 line. Here we show that efficient gray molasses can be implemented on the D2 line of 40K with red-detuned lasers. We obtained temperatures of 48(2)µK, which enables direct loading of 9.2(3)x106 atoms from a magneto-optical trap into an optical dipole trap. We support our findings by a one-dimensional model and three-dimensional numerical simulations of the optical Bloch equations which qualitatively reproduce the experimentally observed cooling effects.PreprintPublisher PDFPeer reviewe

    Informe lito-bioestratigráfico de la cuenca sedimentaria occidental del sur del Perú entre 13° S y 15°S: avances preliminares

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    El presente informe, se realizó en el marco del estudio de investigación del proyecto GR40B: Geología de la cuenca sedimentaria occidental del centro del Perú en Chincheros, hojas 28o2, 28o3 y Conayca, hojas 26m1, 26m4 a escala 1: 50,000, llevado a cabo el año 2016 por el Instituto Geológico Minero y Metalúrgico (INGEMMET), mediante la Dirección de Geología Regional. Este corresponde a una parte del estudio de investigación geológica de la cuenca sedimentaria occidental del sur del Perú, comprendido entre los paralelos 13°S y 15°S que se dio inicio el año 2015. El proyecto comprende estudios litogeoquímicos, bioestratigráficos, además de estudios de procedencia sedimentaria. Uno de los productos para el año 2016 fue el cartografiado a escala 1: 50,000 del cuadrángulo de Chincheros, hojas 28o2 y 28o3, ubicado en el departamento de Ayacucho y el cartografiado del cuadrángulo Conayca, hojas 26m1 y 26m4 ubicado en el departamento de Huancavelica. El informe que a continuación se presenta, corresponde a un avance de la información bio-estratigráfica y lito-estratigráfica colectada durante los trabajos de campo realizados dentro del proyecto de investigación geológica desarrollado el año 2016. El levantamiento de columnas estratigráficas ha permitido caracterizar las unidades Mesozoicas de las zonas trabajadas y sirven como base para estudios complementarios estratigráficos, sedimentológicos y paleontológicos. En la franja correspondiente a la Cordillera Occidental, entre los departamentos de Ayacucho por el sur y el departamento de Huancavelica en la zona central del Perú, se tienen estudios regionales y locales que indican similitudes entre las rocas del intervalo Triásico-Jurásico-Cretáceo. Sin embargo, hasta la fecha, existen diferencias en nomenclatura estratigráfica, lo cual constituye un tema de análisis. La investigación que se viene realizando, comprende estudios sedimentológicos, estratigráficos, paleontológicos y tectónicos representativos de la cuenca sedimentaria occidental. Esta investigación pretende redefinir la génesis, ambientes y los límites de la cuenca mesozoica del centro del Perú. En particular en el presente informe se exponen los avances referentes a litoestratigrafía y bioestratigrafía de las zonas trabajadas el año 2016. Para tal efecto, se han levantado columnas estratigráficas y se ha realizado el muestreo de rocas y fósiles. Como parte del avance del estudio, se hace un breve recuento de las columnas levantadas donde se incluyen los estudios de petrografía y estudios paleontológicos

    Peer-based behavioral health program for drug users in China: a pilot study

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    <p>Abstract</p> <p>Background</p> <p>Many injection drug users (IDUs) in China have high risk sexual behaviors that contribute to the spread of HIV infection. Although many IDUs in China move through drug rehabilitation centers, this opportunity for sexual health education has largely been overlooked.</p> <p>Methods</p> <p>A convenience sample of 667 drug users from two rehabilitation centers in South China was recruited in the study. Two hundred and forty seven drug users from a single Guangdong Province rehabilitation center received the peer-based education intervention, while 420 drug users from another rehabilitation center received routine HIV/STI education and was used as the control. One hundred and eighty nine (22.1%) individuals refused to participate in the study. HIV/STI behavioral and knowledge domains were assessed at 3 months in rehabilitation centers after the intervention (first follow-up) and at 2-23 months in the community after release (second follow-up).</p> <p>Results</p> <p>Drug users who completed the intervention reported more frequent condom use with casual sex partners (60.0% vs. 12.5% condom use every time, p = 0.011) and less frequent injection (56.7% vs. 26.4% no injection per day, p = 0.008) at the second follow-up compared to those in the routine education group. Loss to follow up was substantial in both control and intervention groups, and was associated with living far from the detention center and having poor HIV knowledge at baseline.</p> <p>Conclusions</p> <p>This study shows that rehabilitation centers may be a useful location for providing behavioral HIV/STI prevention services and referral of individuals to community-based programs upon release. More research is needed on behalf of detained drug users in China who have complex social, medical, and legal needs.</p

    Peer-based behavioral health program for drug users in China: a pilot study

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    <p>Abstract</p> <p>Background</p> <p>Many injection drug users (IDUs) in China have high risk sexual behaviors that contribute to the spread of HIV infection. Although many IDUs in China move through drug rehabilitation centers, this opportunity for sexual health education has largely been overlooked.</p> <p>Methods</p> <p>A convenience sample of 667 drug users from two rehabilitation centers in South China was recruited in the study. Two hundred and forty seven drug users from a single Guangdong Province rehabilitation center received the peer-based education intervention, while 420 drug users from another rehabilitation center received routine HIV/STI education and was used as the control. One hundred and eighty nine (22.1%) individuals refused to participate in the study. HIV/STI behavioral and knowledge domains were assessed at 3 months in rehabilitation centers after the intervention (first follow-up) and at 2-23 months in the community after release (second follow-up).</p> <p>Results</p> <p>Drug users who completed the intervention reported more frequent condom use with casual sex partners (60.0% vs. 12.5% condom use every time, p = 0.011) and less frequent injection (56.7% vs. 26.4% no injection per day, p = 0.008) at the second follow-up compared to those in the routine education group. Loss to follow up was substantial in both control and intervention groups, and was associated with living far from the detention center and having poor HIV knowledge at baseline.</p> <p>Conclusions</p> <p>This study shows that rehabilitation centers may be a useful location for providing behavioral HIV/STI prevention services and referral of individuals to community-based programs upon release. More research is needed on behalf of detained drug users in China who have complex social, medical, and legal needs.</p

    Monocytes induce STAT3 activation in human mesenchymal stem cells to promote osteoblast formation

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    A major therapeutic challenge is how to replace bone once it is lost. Bone loss is a characteristic of chronic inflammatory and degenerative diseases such as rheumatoid arthritis and osteoporosis. Cells and cytokines of the immune system are known to regulate bone turnover by controlling the differentiation and activity of osteoclasts, the bone resorbing cells. However, less is known about the regulation of osteoblasts (OB), the bone forming cells. This study aimed to investigate whether immune cells also regulate OB differentiation. Using in vitro cell cultures of human bone marrow-derived mesenchymal stem cells (MSC), it was shown that monocytes/macrophages potently induced MSC differentiation into OBs. This was evident by increased alkaline phosphatase (ALP) after 7 days and the formation of mineralised bone nodules at 21 days. This monocyte-induced osteogenic effect was mediated by cell contact with MSCs leading to the production of soluble factor(s) by the monocytes. As a consequence of these interactions we observed a rapid activation of STAT3 in the MSCs. Gene profiling of STAT3 constitutively active (STAT3C) infected MSCs using Illumina whole human genome arrays showed that Runx2 and ALP were up-regulated whilst DKK1 was down-regulated in response to STAT3 signalling. STAT3C also led to the up-regulation of the oncostatin M (OSM) and LIF receptors. In the co-cultures, OSM that was produced by monocytes activated STAT3 in MSCs, and neutralising antibodies to OSM reduced ALP by 50%. These data indicate that OSM, in conjunction with other mediators, can drive MSC differentiation into OB. This study establishes a role for monocyte/macrophages as critical regulators of osteogenic differentiation via OSM production and the induction of STAT3 signalling in MSCs. Inducing the local activation of STAT3 in bone cells may be a valuable tool to increase bone formation in osteoporosis and arthritis, and in localised bone remodelling during fracture repair

    A comprehensive fracture prevention strategy in older adults: The European union geriatric medicine society (EUGMS) statement

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    Prevention of fragility fractures in older people has become a public health priority, although the most appropriate and cost-effective strategy remains unclear. In the present statement, the Interest group on falls and fracture prevention of the European union geriatric medicine society (EUGMS), in collaboration with the International association of gerontology and geriatrics for the European region (IAGG-ER), the European union of medical specialists (EUMS), the Fragility fracture network (FFN), the International osteoporosis foundation (IOF) – European society for clinical and economic aspects of osteoporosis and osteoarthritis (ECCEO), outlines its views on the main points in the current debate in relation to the primary and secondary prevention of falls, the diagnosis and treatment of bone fragility, and the place of combined falls and fracture liaison services for fracture prevention in older people

    Variational Foundations and Generalized Unified Theory of RVE-Based Multiscale Models

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    A unified variational theory is proposed for a general class of multiscale models based on the concept of Representative Volume Element. The entire theory lies on three fundamental principles: (1) kinematical admissibility, whereby the macro- and micro-scale kinematics are defined and linked in a physically meaningful way; (2) duality, through which the natures of the force- and stress-like quantities are uniquely identified as the duals (power-conjugates) of the adopted kinematical variables; and (3) the Principle of Multiscale Virtual Power, a generalization of the well-known Hill-Mandel Principle of Macrohomogeneity, from which equilibrium equations and homogenization relations for the force- and stress-like quantities are unequivocally obtained by straightforward variational arguments. The proposed theory provides a clear, logically-structured framework within which existing formulations can be rationally justified and new, more general multiscale models can be rigorously derived in well-defined steps. Its generality allows the treatment of problems involving phenomena as diverse as dynamics, higher order strain effects, material failure with kinematical discontinuities, fluid mechanics and coupled multi-physics. This is illustrated in a number of examples where a range of models is systematically derived by following the same steps. Due to the variational basis of the theory, the format in which derived models are presented is naturally well suited for discretization by finite element-based or related methods of numerical approximation. Numerical examples illustrate the use of resulting models, including a non-conventional failure-oriented model with discontinuous kinematics, in practical computations
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