735 research outputs found

    Thermal Conductivity and Specific Heat of the Spin-Ice Compound Dy2_2Ti2_2O7_7: Experimental Evidence for Monopole Heat Transport

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    Elementary excitations in the spin-ice compound Dy2_2Ti2_2O7_7 can be described as magnetic monopoles propagating independently within the pyrochlore lattice formed by magnetic Dy ions. We studied the magnetic-field dependence of the thermal conductivity {\kappa}(B) for B || [001] and observe clear evidence for magnetic heat transport originating from the monopole excitations. The magnetic contribution {\kappa}_{mag} is strongly field-dependent and correlates with the magnetization M(B). The diffusion coefficient obtained from the ratio of {\kappa}_{mag} and the magnetic specific heat is strongly enhanced below 1 K indicating a high mobility of the monopole excitations in the spin-ice state.Comment: 5 pages, 4 figure

    Combining support vector machines and segmentation algorithms for efficient anomaly detection: a petroleum industry application

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    Proceedings of: International Joint Conference SOCO’14-CISIS’14-ICEUTE’14, Bilbao, Spain, June 25th–27th, 2014, ProceedingsAnomaly detection is the problem of finding patterns in data that do not conform to expected behavior. Similarly, when patterns are numerically distant from the rest of sample, anomalies are indicated as outliers. Anomaly detection had recently attracted the attention of the research community for real-world applications. The petroleum industry is one of the application contexts where these problems are present. The correct detection of such types of unusual information empowers the decision maker with the capacity to act on the system in order to correctly avoid, correct, or react to the situations associated with them. In that sense, heavy extraction machines for pumping and generation operations like turbomachines are intensively monitored by hundreds of sensors each that send measurements with a high frequency for damage prevention. For dealing with this and with the lack of labeled data, in this paper we propose a combination of a fast and high quality segmentation algorithm with a one-class support vector machine approach for efficient anomaly detection in turbomachines. As result we perform empirical studies comparing our approach to other methods applied to benchmark problems and a real-life application related to oil platform turbomachinery anomaly detection.This work was partially funded by CNPq BJT Project 407851/2012-7 and CNPq PVE Project 314017/2013-

    Architecture of the yeast elongator complex

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    The highly conserved eukaryotic Elongator complex performs specific chemical modifications on wobble base uridines of tRNAs, which are essential for proteome stability and homeostasis. The complex is formed by six individual subunits (Elp1-6) that are all equally important for its tRNA modification activity. However, its overall architecture and the detailed reaction mechanism remain elusive. Here, we report the structures of the fully assembled yeast Elongator and the Elp123 sub-complex solved by an integrative structure determination approach showing that two copies of the Elp1, Elp2, and Elp3 subunits form a two-lobed scaffold, which binds Elp456 asymmetrically. Our topological models are consistent with previous studies on individual subunits and further validated by complementary biochemical analyses. Our study provides a structural framework on how the tRNA modification activity is carried out by Elongator

    Conceptualising social justice and sociocultural issues within physical education teacher education: international perspectives

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    Background: Physical education (PE) and physical education teacher education (PETE) have a substantial literature base that advocates for students to develop a critical consciousness, appreciate multiple perspectives, and engage in actions to enhance social justice (Tinning 2016). Analysing sociocultural issues, critically reflecting on beliefs, knowledge, biography and values, and developing a sense of agency to enact change, have been recognised as an integral part of the PETE knowledge base for some time (Fernández-Balboa 1997). However, there remain differences in how social justice itself is conceptualised and enacted. Social justice is aligned heavily with critical and ‘post’ theories where taking action for justice, democracy and power are central; but social justice is also found in humanist beliefs in student-centredness and equality and has been co-opted by neoliberal forces that promote individual responsibility. While a lack of consensus is not in itself a problem (Bialystok 2014), diverse definitions might contribute to confusion (Randall and Robinson 2016) and lead to uncertainty over what and how to teach for social justice. Purpose: In order to work towards greater certainty around concepts of social justice in the PETE community, this project sought to map variations in definition and conceptualisation of social justice and sociocultural issues among physical education teacher educators (PETEs) and physical education and sport pedagogy (PESP) educators, as part of a wider project on social justice and sociocultural perspectives and practices in PETE. Methods: PETE and PESP faculty (n=72) in North America, Europe, and Australasia engaged in an in-depth interview, during which they were asked how they define social justice and sociocultural issues. Additional information about participants’ social identity was collected. A constant comparative method of analysing participants’ definitions mapped a range of concepts building on the theoretical framework of neoliberal, humanist, critical and ‘post’ approaches to social justice. Findings: The data demonstrate that there are a range of understandings about sociocultural issues and social justice. Most commonly, some participants articulated a humanist approach to social justice by encouraging their pre-service teachers (PSTs) to have awareness of equality of opportunity in relation to gender, sexuality and/or racism. Less prevalent, but strongly stated by those who conceptualised social justice in these terms, was the importance to take action for democracy, empowerment or critical reflection. The terms diversity and equality, framed in neoliberal and humanist discourses, were most commonly used within the United States (US), while critical pedagogy and alignment with critical and ‘post’ theories were more prevalent in Australia and New Zealand. Conclusion: Differences exist in the ways social justice is conceptualised in PETE. While this can be attributed to the influence of local issues, it is also reflective of what intellectual tools, such as humanism or critical theory, are available for problematising social issues. The range of non-critical concepts found raises concern that PSTs are not getting the tools to enact social justice or tackle sociocultural issues.

    Preliminary genetic evidence of two different populations of Opisthorchis viverrini in Lao PDR

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    Opisthorchis viverrini is a major public health concern in Southeast Asia. Various reports have suggested that this parasite may represent a species complex, with genetic structure in the region perhaps being dictated by geographical factors and different species of intermediate hosts. We used four microsatellite loci to analyze O. viverrini adult worms originating from six species of cyprinid fish in Thailand and Lao PDR. Two distinct O. viverrini populations were observed. In Ban Phai, Thailand, only one subgroup occurred, hosted by two different fish species. Both subgroups occurred in fish from That Luang, Lao PDR, but were represented to very different degrees among the fish hosts there. Our data suggest that, although geographical separation is more important than fish host specificity in influencing genetic structure, it is possible that two species of Opisthorchis, with little interbreeding, are present near Vientiane in Lao PDR

    Human hippocampal neurogenesis drops sharply in children to undetectable levels in adults.

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    New neurons continue to be generated in the subgranular zone of the dentate gyrus of the adult mammalian hippocampus. This process has been linked to learning and memory, stress and exercise, and is thought to be altered in neurological disease. In humans, some studies have suggested that hundreds of new neurons are added to the adult dentate gyrus every day, whereas other studies find many fewer putative new neurons. Despite these discrepancies, it is generally believed that the adult human hippocampus continues to generate new neurons. Here we show that a defined population of progenitor cells does not coalesce in the subgranular zone during human fetal or postnatal development. We also find that the number of proliferating progenitors and young neurons in the dentate gyrus declines sharply during the first year of life and only a few isolated young neurons are observed by 7 and 13 years of age. In adult patients with epilepsy and healthy adults (18-77 years; n = 17 post-mortem samples from controls; n = 12 surgical resection samples from patients with epilepsy), young neurons were not detected in the dentate gyrus. In the monkey (Macaca mulatta) hippocampus, proliferation of neurons in the subgranular zone was found in early postnatal life, but this diminished during juvenile development as neurogenesis decreased. We conclude that recruitment of young neurons to the primate hippocampus decreases rapidly during the first years of life, and that neurogenesis in the dentate gyrus does not continue, or is extremely rare, in adult humans. The early decline in hippocampal neurogenesis raises questions about how the function of the dentate gyrus differs between humans and other species in which adult hippocampal neurogenesis is preserved
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