1,848 research outputs found

    The variability processing and analysis of the Gaia mission

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    We present the variability processing and analysis that is foreseen for the Gaia mission within Coordination Unit 7 (CU7) of the Gaia Data Processing and Analysis Consortium (DPAC). A top level description of the tasks is given.Comment: 4 pages, 1 figure. To be published in the proceedings of the GREAT-ITN conference "The Milky Way Unravelled by Gaia: GREAT Science from the Gaia Data Releases", 1-5 December 2014, University of Barcelona, Spain, EAS Publications Series, eds Nicholas Walton, Francesca Figueras, and Caroline Soubira

    Blackboard Rules for Coordinating Context-aware Applications in Mobile Ad Hoc Networks

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    Thanks to improvements in wireless communication technologies and increasing computing power in hand-held devices, mobile ad hoc networks are becoming an ever-more present reality. Coordination languages are expected to become important means in supporting this type of interaction. To this extent we argue the interest of the Bach coordination language as a middleware that can handle and react to context changes as well as cope with unpredictable physical interruptions that occur in opportunistic network connections. More concretely, our proposal is based on blackboard rules that model declaratively the actions to be taken once the blackboard content reaches a predefined state, but also that manage the engagement and disengagement of hosts and transient sharing of blackboards. The idea of reactiveness has already been introduced in previous work, but as will be appreciated by the reader, this article presents a new perspective, more focused on a declarative setting.Comment: In Proceedings FOCLASA 2012, arXiv:1208.432

    Concentration and purification by magnetic separation of the erythrocytic stages of all human Plasmodium species

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    International audienceBackground : Parasite concentration methods facilitate molecular, biochemical and immunologicalresearch on the erythrocytic stages of Plasmodium. In this paper, an adaptation of magnetic MACS®columns for the purification of human Plasmodium species is presented. This method was useful forthe concentration/purification of either schizonts or gametocytes.Results and conclusions : The magnetic removal of non-parasitized red blood cells (in vivo andin vitro) using magnetic columns (MACS) was evaluated. This easy-to-use technique enrichedschizonts and gametocytes from Plasmodium falciparum in vitro cultures with a very high degree ofpurity. In addition, all haemozoin-containing stages (schizonts and/or gametocytes) from theperipheral blood of infected patients could be concentrated using this method. This method isparticularly useful for the concentration of non-falciparum species, which do not grow in cultureand are otherwise difficult to obtain in large amounts

    Pulsating star research and the Gaia revolution

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    In this article we present an overview of the ESA Gaia mission and of the unprecedented impact that Gaia will have on the field of variable star research. We summarise the contents and impact of the first Gaia data release on the description of variability phenomena, with particular emphasis on pulsating star research. The Tycho-Gaia astrometric solution, although limited to 2.1 million stars, has been used in many studies related to pulsating stars. Furthermore a set of 3,194 Cepheids and RR Lyrae stars with their times series have been released. Finally we present the plans for the ongoing study of variable phenomena with Gaia and highlight some of the possible impacts of the second data release on variable, and specifically, pulsating stars.Comment: 12 pages, 4 figures, proceedings for the 22nd Los Alamos Stellar Pulsation Conference Series Meeting "Wide field variability surveys: a 21st-century perspective", held in San Pedro de Atacama, Chile, Nov. 28 - Dec. 2, 201

    A comparative study of four significance measures for periodicity detection in astronomical surveys

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    We study the problem of periodicity detection in massive data sets of photometric or radial velocity time series, as presented by ESA's Gaia mission. Periodicity detection hinges on the estimation of the false alarm probability of the extremum of the periodogram of the time series. We consider the problem of its estimation with two main issues in mind. First, for a given number of observations and signal-to-noise ratio, the rate of correct periodicity detections should be constant for all realized cadences of observations regardless of the observational time patterns, in order to avoid sky biases that are difficult to assess. Secondly, the computational loads should be kept feasible even for millions of time series. Using the Gaia case, we compare the FM method of Paltani and Schwarzenberg-Czerny, the Baluev method and the GEV method of Süveges, as well as a method for the direct estimation of a threshold. Three methods involve some unknown parameters, which are obtained by fitting a regression-type predictive model using easily obtainable covariates derived from observational time series. We conclude that the GEV and the Baluev methods both provide good solutions to the issues posed by a large-scale processing. The first of these yields the best scientific quality at the price of some moderately costly pre-processing. When this pre-processing is impossible for some reason (e.g. the computational costs are prohibitive or good regression models cannot be constructed), the Baluev method provides a computationally inexpensive alternative with slight biases in regions where time samplings exhibit strong aliase

    Molecular monitoring of plasmodium falciparum drug susceptibility at the time of the introduction of artemisinin-based combination therapy in Yaoundé, Cameroon: Implications for the future

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    <p>Abstract</p> <p>Background</p> <p>Regular monitoring of the levels of anti-malarial resistance of <it>Plasmodium falciparum </it>is an essential policy to adapt therapy and improve malaria control. This monitoring can be facilitated by using molecular tools, which are easier to implement than the classical determination of the resistance phenotype. In Cameroon, chloroquine (CQ), previously the first-line therapy for uncomplicated malaria was officially withdrawn in 2002 and replaced initially by amodiaquine (AQ) monotherapy. Then, artemisinin-based combination therapy (ACT), notably artesunate-amodiaquine (AS-AQ) or artemether-lumefantrine (AL), was gradually introduced in 2004. This situation raised the question of the evolution of <it>P. falciparum </it>resistance molecular markers in Yaoundé, a highly urbanized Cameroonian city.</p> <p>Methods</p> <p>The genotype of <it>pfcrt </it>72 and 76 and <it>pfmdr1 </it>86 alleles and <it>pfmdr1 </it>copy number were determined using real-time PCR in 447 <it>P. falciparum </it>samples collected between 2005 and 2009.</p> <p>Results</p> <p>This study showed a high prevalence of parasites with mutant <it>pfcrt </it>76 (83%) and <it>pfmdr1 </it>86 (93%) codons. On the contrary, no mutations in the <it>pfcrt </it>72 codon and no samples with duplication of the <it>pfmdr1 </it>gene were observed.</p> <p>Conclusion</p> <p>The high prevalence of mutant <it>pfcrt </it>76T and <it>pfmdr1 </it>86Y alleles might be due to the choice of alternative drugs (AQ and AS-AQ) known to select such genotypes. Mutant <it>pfcrt </it>72 codon was not detected despite the prolonged use of AQ either as monotherapy or combined with artesunate. The absence of <it>pfmdr1 </it>multicopies suggests that AL would still remain efficient. The limited use of mefloquine or the predominance of mutant <it>pfmdr1 </it>86Y codon could explain the lack of <it>pfmdr1 </it>amplification. Indeed, this mutant codon is rarely associated with duplication of <it>pfmdr1 </it>gene. In Cameroon, the changes of therapeutic strategies and the simultaneous use of several formulations of ACT or other anti-malarials that are not officially recommended result in a complex selective pressure, rendering the prediction of the evolution of <it>P. falciparum </it>resistance difficult. This public health problem should lead to increased vigilance and regular monitoring.</p

    Implementing pelvic floor muscle training for women with pelvic organ prolapse: a realist evaluation of different delivery models.

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    Background Pelvic Floor Muscle Training (PFMT) has been shown to be effective for pelvic organ prolapse in women, but its implementation in routine practice is challenging due to lack of adequate specialist staff. It is important to know if PFMT can be delivered by different staff skill mixes, what barriers and facilitators operate in different contexts, what strategies enable successful implementation and what are the underlying mechanisms of their action. PROPEL intervention was designed to maximise the delivery of effective PFMT in the UK NHS using different staff skill mixes. We conducted a realist evaluation (RE) of this implementation to understand what works, for whom, in what circumstances and why. Methods Informed by the Realist and RE-AIM frameworks, the study used a longitudinal, qualitative, multiple case study design. The study took place in five, purposively selected, diverse NHS sites across the UK and proceeded in three phases to identify, test and refine a theory of change. Data collection took place at 4 time points over an 18 month implementation period using focus groups and semi-structured interviews with a range of stakeholders including service leads/managers, senior practitioners, newly trained staff and women receiving care in the new service models. Data were analysed using thematic framework approach adapted to identify Context, Mechanism and Outcome (CMO) configurations of the RE. Results A heightened awareness of the service need among staff and management was a mechanism for change, particularly in areas where there was a shortage of skilled staff. In contrast, the most established specialist physiotherapist-delivered PFMT service activated feelings of role protection and compromised quality, which restricted the reach of PFMT through alternative models. Staff with some level of prior knowledge in women’s health and adequate organisational support were more comfortable and confident in new role. Implementation was seamless when PFMT delivery was incorporated in newly trained staff’s role and core work. Conclusion Roll-out of PFMT delivery through different staff skill mixes is possible when it is undertaken by clinicians with an interest in women’s health, and carefully implemented ensuring adequate levels of training and ongoing support from specialists, multi-disciplinary teams and management
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