2,823 research outputs found

    Spatial opinion dynamics and the effects of two types of mixing

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    Spatially situated opinions that can be held with different degrees of conviction lead to spatiotemporal patterns such as clustering (homophily), polarization, and deadlock. Our goal is to understand how sensitive these patterns are to changes in the local nature of interactions. We introduce two different mixing mechanisms, spatial relocation and nonlocal interaction (“telephoning”), to an earlier fully spatial model (no mixing). Interestingly, the mechanisms that create deadlock in the fully spatial model have the opposite effect when there is a sufficient amount of mixing. With telephoning, not only is polarization and deadlock broken up, but consensus is hastened. The effects of mixing by relocation are even more pronounced. Further insight into these dynamics is obtained for selected parameter regimes via comparison to the mean-field differential equations

    First record of Nemertodermatida from Belgian marine waters

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    Acoelomorpha; Nemertodermatida; new records; Belgium</td

    OPTIMAL MOVEMENT FOR LOWER EXTREMITY INJURY PREVENTION; HOW TO CREATE AN OPTIMAL LEARNING ENVIRONMENT FOR YOUTH SOCCER GIRLS

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    For lower extremity injury prevention, it is crucial to decrease external loads to the joints in sport-specific situations. The purpose of this study was to examine how landing kinetics and psychological factors (i.e., motivation) change during a four-week laboratory training program. Ten talented soccer girls practiced three sport-specific tasks and received expert video instruction. Increased fun and competence in week 3 compared to week 1 was observed. No significant changes of effort and joint load (a discrete number to describe combined external frontal and transverse plane knee and ankle moments) were found. Results are promising and innovative as this is the first study testing the entire OPTIMAL model including retention and linking biomechanics with perceived motivation. More research is planned on additional instructions and feedback that may enhance the motor learning curve

    Robust Bayes-Like Estimation: Rho-Bayes estimation

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    We consider the problem of estimating the joint distribution PP of nn independent random variables within the Bayes paradigm from a non-asymptotic point of view. Assuming that PP admits some density ss with respect to a given reference measure, we consider a density model S‾\overline S for ss that we endow with a prior distribution π\pi (with support S‾\overline S) and we build a robust alternative to the classical Bayes posterior distribution which possesses similar concentration properties around ss whenever it belongs to the model S‾\overline S. Furthermore, in density estimation, the Hellinger distance between the classical and the robust posterior distributions tends to 0, as the number of observations tends to infinity, under suitable assumptions on the model and the prior, provided that the model S‾\overline S contains the true density ss. However, unlike what happens with the classical Bayes posterior distribution, we show that the concentration properties of this new posterior distribution are still preserved in the case of a misspecification of the model, that is when ss does not belong to S‾\overline S but is close enough to it with respect to the Hellinger distance.Comment: 68 page

    AFLP TM technique used for genetic characterization of rat inbred strains

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    The AFLP TM technique is a novel DNA technology which generates AFLP markers. The technique is based on the combined use of restriction fragments and selective PCR primers Because both the restriction fragments and the selective primers can be varied, many new genetic markers will become available. We have used four enzyme/primer combinations for the genetic characterization of 12 rat inbred strains. All these strains could be provided with their own unique genetic profile using these four combinations. No variation was found within the individuals of the same strain. This indicates that AFLP markers are stable and useful for genetic monitoring of strains and for linkage analysis

    Reopening schools during the COVID-19 pandemic: Overview and rapid systematic review of guidelines and recommendations on preventive measures and the management of cases

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    Given the limited evidence of school closure effectiveness in containing the pandemic and the consequences for young people, reopening schools with appropriate measures is essential. This overview aimed to describe the main measures planned for the 2020&ndash;2021 academic year within the WHO European Region. A rapid systematic review of scientific databases was also performed. The websites of the government, Ministry of Health, and Ministry of Education of European Region countries were searched through 1 October for official documents about the prevention and management of suspected cases/confirmed cases in primary and secondary schools. To find further suggestions, a rapid systematic review was conducted through 20 October searching Pubmed, Scopus, and Embase. There were 23 official documents. France, Luxembourg, Malta, Ireland, Italy, Portugal, the UK, Spain, and San Marino were considered. Performing the rapid review, 855 records were identified and 7 papers were finally selected. The recommendations mostly agreed. However, there was no consensus on the criteria for the return to school of students that tested positive, and the flexibility between attendance at school and remote education for high-risk children often varied. School closure was commonly considered as the very last resort for COVID-19 control. Studies are required to evaluate the impact of different recommendations during this autumn term

    Palatini versus metric formulation in higher curvature gravity

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    We compare the metric and the Palatini formalism to obtain the Einstein equations in the presence of higher-order curvature corrections that consist of contractions of the Riemann tensor, but not of its derivatives. We find that there is a class of theories for which the two formalisms are equivalent. This class contains the Palatini version of Lovelock theory, but also more Lagrangians that are not Lovelock, but respect certain symmetries. For the general case, we find that imposing the Levi-Civita connection as an Ansatz, the Palatini formalism is contained within the metric formalism, in the sense that any solution of the former also appears as a solution of the latter, but not necessarily the other way around. Finally we give the conditions the solutions of the metric equations should satisfy in order to solve the Palatini equations.Comment: 13 pages, latex. V2: reference added, major changes in section 3, conclusions partially correcte

    Psoas abscess: report of a series and review of the literature

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    We describe a series of twelve patients with a psoas abscess seen in a three-year period in a university hospital and a large teaching hospital in the Netherlands. In our series, five of the 12 patients had a primary psoas abscess. The predisposing conditions were intravenous drug use, diabetes mellitus, prostate carcinoma and haematoma in the psoas muscle in a patient with haemophilia A. Seven of the 12 patients had a secondary psoas abscess. Five cases were due to vertebral osteomyelitis including two cases of tuberculosis. In the other two cases it was due to colitis and urinary tract infection. It is remarkable that in our series there was only one patient with a psoas abscess secondary to a disease of the digestive tract, while this is the most common cause of a secondary psoas abscess in the literature. There were two cases of tuberculosis which is an emerging disease again
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