649 research outputs found

    I\u27ll Come Back to Dixieland, If You\u27ll Come Back to Me

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    https://digitalcommons.library.umaine.edu/mmb-vp/5546/thumbnail.jp

    Symmetry breaking in crossed magnetic and electric fields

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    We present the first observations of cylindrical symmetry breaking in highly excited diamagnetic hydrogen with a small crossed electric field, and we give a semiclassical interpretation of this effect. As the small perpendicular electric field is added, the recurrence strengths of closed orbits decrease smoothly to a minimum, and revive again. This phenomenon, caused by interference among the electron waves that return to the nucleus, can be computed from the azimuthal dependence of the classical closed orbits.Comment: 4 page REVTeX file including 5 postscript files (using psfig) Accepted for publication in Physical Review Letters. Difference from earlier preprint: we have discovered the cause of the earlier apparent discrepancy between experiment and theory and now achieve excellent agreemen

    The structure of Organizational Virtual Social Networks

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    Organizational virtual social networks (OVSN) reshape social structures due to their ability to strengthen social ties, to change power relations and to enable new forms of cooperation. Research in Information and Communication Technologies (ICT) has led to various approaches that analyze the impact of OVSN on organizations in terms of structure and behavior. Our study aims to analyze important features related to the structure of OVSN. It also aims to strengthen a network approach to analyze organizational phenomena such as working groups and connected individuals, as well as the impact of online networks in organizations. This study was based on the lines of approach described by Oinas-Kukkonen et al. (2010) and on the research carried out by Bobsin & Hoppen (2012) to understand the process of structuring OVSN. Our main results are an OVSN structure consisting of actors and roles, interactions, operating elements and articulating goals. We also analyzed some structural elements of networks which may contribute to the development of a network based approach to study organizational phenomena

    Pharmacodynamic modeling of bacillary elimination rates and detection of bacterial lipid bodies in sputum to predict and understand outcomes in treatment of pulmonary tuberculosis

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    This work was supported by a Wellcome Trust Clinical PhD Fellowship (086757/Z/08/A to D. J. S.), the Malawi Liverpool Wellcome Trust Core grant, and Medical Research Council (grant number G0300403 to M. R. B.).Background. Antibiotic-tolerant bacterial persistence prevents treatment shortening in drug-susceptible tuberculosis, and accumulation of intracellular lipid bodies has been proposed to identify a persister phenotype of Mycobacterium tuberculosis cells. In Malawi, we modeled bacillary elimination rates (BERs) from sputum cultures and calculated the percentage of lipid body-positive acid-fast bacilli (%LB + AFB) on sputum smears. We assessed whether these putative measurements of persistence predict unfavorable outcomes (treatment failure/relapse). Methods. Adults with pulmonary tuberculosis received standard 6-month therapy. Sputum samples were collected during the first 8 weeks for serial sputum colony counting (SSCC) on agar and time-to positivity (TTP) measurement in mycobacterial growth indicator tubes. BERs were extracted from nonlinear and linear mixed-effects models, respectively, fitted to these datasets. The %LB + AFB counts were assessed by fluorescence microscopy. Patients were followed until 1 year posttreatment. Individual BERs and %LB + AFB counts were related to final outcomes. Results. One hundred and thirty-three patients (56% HIV coinfected) participated, and 15 unfavorable outcomes were reported. These were inversely associated with faster sterilization phase bacillary elimination from the SSCC model (odds ratio [OR], 0.39; 95% confidence interval [CI], .22-.70) and a faster BER from the TTP model (OR, 0.71; 95% CI, .55-.94). Higher %LB + AFB counts on day 21-28 were recorded in patients who suffered unfavorable final outcomes compared with those who achieved stable cure (P = .008). Conclusions. Modeling BERs predicts final outcome, and high %LB + AFB counts 3-4 weeks into therapy may identify a persister bacterial phenotype. These methods deserve further evaluation as surrogate endpoints for clinical trials.Publisher PDFPeer reviewe

    Unresolved issues and new challenges in teaching English to young learners:the case of South Korea

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    The introduction of languages, especially English, into the primary curriculum around the world has been one of the major language-in-education policy developments in recent years. In countries where English has been compulsory for a number of years, the question arises as to what extent the numerous and well-documented challenges faced by the initial implementation of early language learning policies have been overcome and whether new challenges have arisen as policies have become consolidated. This article therefore focuses on South Korea, where English has been compulsory in primary school since 1997. The issues raised by the introduction of English into the primary curriculum are reviewed and the current situation in South Korea is investigated. The results of a mixed methods study using survey data from 125 Korean primary school teachers, together with data from a small-scale case study of one teacher are presented. The study shows that, while some of the initial problems caused by the introduction of early language learning appear to have been addressed, other challenges persist. Moreover, the data reveal the emergence of a number of new challenges faced by primary school teachers of English as they seek to implement government policy

    Ser649 and Ser650 Are the Major Determinants of Protein Kinase A-Mediated Activation of Human Hormone-Sensitive Lipase against Lipid Substrates

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    BACKGROUND: Hormone-sensitive lipase (HSL) is a key enzyme in the mobilization of fatty acids from stored triacylglycerols. Its activity is regulated by reversible protein phosphorylation. In rat HSL Ser563, Ser659 and Ser660 have been shown to be phosphorylated by protein kinase A (PKA) in vitro as well as in vivo. METHODOLOGY/PRINCIPAL FINDINGS: In this study we employed site-directed mutagenesis, in vitro phosphorylation and mass spectrometry to show that in vitro phosphorylation of human HSL by PKA occurs primarily on Ser649 and Ser650 (Ser659 and Ser660 in rat HSL). The wild type enzyme and four mutants were expressed in C-terminally His-tagged form in Sf9 insect cells and purified to homogeneity. HSL variants in which Ser552 and/or Ser554 were mutated to Ala or Glu retained both lipolytic and non-lipolytic activity and were phosphorylated by PKA and activated to a similar extent as the wild type enzyme. (32)P-labeling studies revealed that the bulk of the phosphorylation was on the Ser649/Ser650 site, with only a minor phosphorylation of Ser552 and Ser554. MS/MS analysis demonstrated that the peptide containing Ser649 and Ser650 was primarily phosphorylated on Ser650. The mutant lacking all four serines had severely reduced lipolytic activity, but a lesser reduction in non-lipolytic activity, had S(0.5) values for p-nitrophenol butyrate and triolein comparable to those of wild type HSL and was not phosphorylated by PKA. PKA phosphorylation of the wild type enzyme resulted in an increase in both the maximum turnover and S(0,5) using the TO substrate. CONCLUSIONS: Our results demonstrate that PKA activates human HSL against lipid substrates in vitro primarily through phosphorylation of Ser649 and Ser650. In addition the results suggest that Ser649 and Ser650 are located in the vicinity of a lipid binding region and that PKA phosphorylation controls the accessibility of this region

    Patterns in Greater Sage-grouse population dynamics correspond with public grazing records at broad scales

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    Human land use, such as livestock grazing, can have profound yet varied effects on wildlife interacting within common ecosystems, yet our understanding of land-use effects is often generalized from short-term, local studies that may not correspond with trends at broader scales. Here we used public land records to characterize livestock grazing across Wyoming, USA, and we used Greater Sage-grouse (Centrocercus urophasianus) as a model organism to evaluate responses to livestock management. With annual counts of male Sage-grouse from 743 leks (breeding display sites) during 2004-2014, we modeled population trends in response to grazing level (represented by a relative grazing index) and timing across a gradient in vegetation productivity as measured by the Normalized Vegetation Difference Index (NDVI). We found grazing can have both positive and negative effects on Sage-grouse populations depending on the timing and level of grazing. Sage-grouse populations responded positively to higher grazing levels after peak vegetation productivity, but populations declined when similar grazing levels occurred earlier, likely reflecting the sensitivity of cool-season grasses to grazing during peak growth periods. We also found support for the hypothesis that effects of grazing management vary with local vegetation productivity. These results illustrate the importance of broad-scale analyses by revealing patterns in Sage-grouse population trends that may not be inferred from studies at finer scales, and could inform sustainable grazing management in these ecosystems

    Statutory Assessment of the class? Supporting the additional needs of the learning context

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    This paper considers issues of funding of support for students facing difficulties in learning, and the role of assessment and labelling within this process. It explores the tensions within this process using a Foucauldian framework, and from the key perspectives of social justice and rights. Drawing on a range of literature it identifies the focus upon the individual within assessment processes around the world, and then considers in detail the strengths and weaknesses of the current form of Statutory Assessment of Special Educational Needs within England. The paper proposes an alternative funding system that resolves shortcomings within the individual approach and the English system. It suggests that a Class Funding Approach could build on a notion of justice for all, reduce the opportunities for wide variations in provision, and minimise the negative impact of current dividing practices

    Contemporary changes and civil society in Portugal and the Russian Federation

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    Portugal and the Russian Federation share some aspects of traditional culture and similar experiences in modern history, but they also exhibit significant differences that determine specific modes of civil society’s development. Results of a comparative and diachronic analysis show that the major differences between the two countries reside in civil society’s openness and composition. Organized civil society is not very distinct in relative size when comparing Portugal and the Russian Federation, but it is globally more autonomous, expressive, trusted and institutionalized in Portugal than in the Russian Federation and among the factors that contribute to this condition are an earlier and revolutionary transition to democracy, a larger middle class, a greater prevalence of the value of interdependence, and a regime that endorses bigger public social expenditure in Portugal, all this within the framework of the European Union that has a longer history of social demand and institutional incentives for civil society. Despite those unequal conditions, civil society faces similar current challenges in both countries, mainly with the outsourcing of the public provision of social services.info:eu-repo/semantics/acceptedVersio

    Native-English-Speaking Teachers:Disconnections Between Theory, Research, and Practice

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    Native-English-speaking teachers (NESTs) have long been in demand for perceived benefits of the skills they bring to the classroom. However, the notion that native speakers provide the best models of the target language and thus make the best teachers of the language has been criticised in the literature. This article reports on the disconnection between academic literature on NESTs and the realities they report. Drawing on data from an investigation into NEST schemes globally, the article suggests that lived classroom experiences of NESTs are complex, They are also often bilingual, experienced, and qualified, and regard local English teachers (LETs) they work with as experts and in control of how English is practised in the classroom. These characteristics contrast with much of the academic literature, which explores the concept of native speakerism, which tends to view NESTs negatively. The article proposes that one reason for the disconnection between theory and practice is the parallel lives of researchers and teachers, whether NESTs or LETs. Thus, each group’s realities and concerns are not always understood by the other. The article suggests that a substantial group of bilingual and bicultural NESTs consider the country where work home, so future theorisations of NESTs and native speakerism should take account of these teachers
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