761 research outputs found

    Quantifying Permafrost Extent, Condition, and Degradation Rates at Department of Defense Installations in the Arctic

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    The DoD is planning over $500M in military construction on Eielson Air Force Base (AFB) within the next three years. This construction program will expand the footprint of facilities and change parts of the storm water management scheme, which may have second order effects on the underlying permafrost layer. These changes in permafrost will drive engineering decision making at local and regional levels, and help shape the overall strategy for military readiness in the Arctic. Little site-specific knowledge exists on the human caused effects to permafrost at this location. In 2016, the permafrost degradation rates at Eielson AFB were modeled using the Geophysical Institute Permafrost Laboratory (GIPL) 2.1 model and limited available geotechnical and climate data. Model results indicated a degradation of the discontinuous permafrost layer at Eielson AFB of at least 7 meters in depth over the next century. To further refine an understanding of the geophysics at Eielson AFB and help engineers and commanders make more informed decisions on engineering and operations in the arctic, this project established two long term permafrost monitoring stations near the future construction sites. The data set generated by these stations are the first of their kind at Eielson AFB and represent the first modern systematic effort in the DoD to quantify permafrost condition before, during, and after construction activities. In addition to better understanding the effects of construction activity, we hope to provide awareness and better stewardship for permafrost as a fragile and important natural resource present on many federally owned installations

    How Do Children Become Workers? Making Sense of Conflicting Accounts of Cultural Transmission in Anthropology and Psychology

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    This article uses children’s work as a lens to examine methodological concerns in the study of cultural transmission and children’s learning of useful domestic and subsistence skills. We begin by providing a review of the relevant literature concerning cultural transmission in the context of the ethnographic record, as well as more recent studies originating largely from psychology. We then offer an ethnographic case study concerning Asabano (PNG [Papua New Guinea]) childhood to make an important methodological contribution in the interdisciplinary study of cultural transmission. The case study centers on the paradox that Asabano parents, in interviews, claim that their children learn almost exclusively via parental teaching. Field observation and the parent’s and children’s spontaneous remarks suggest that this, in fact, does not happen and that children are expected to learn largely on their own with little parental intervention. To account for this paradox, we illustrate the limits of asking in particular cultural contexts like that of the Asabano, as well as the influence of institutions such as schools and churches, which have provided new and influential models of teaching that interlocutors are able to refer to in the context of interviews without necessarily changing their actual practices

    Exploring the flavour structure of the MSSM with rare K decays

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    We present an extensive analysis of rare K decays, in particular of the two neutrino modes K+->pi+ nu nu-bar and KL->pi0 nu nu-bar, in the Minimal Supersymmetric extension of the Standard Model. We analyse the expectations for the branching ratios of these modes, both within the restrictive framework of the minimal flavour violation hypothesis and within a more general framework with new sources of flavour-symmetry breaking. In both scenarios, the information that can be extracted from precise measurements of the two neutrino modes turn out to be very useful in restricting the parameter space of the model, even after taking into account the possible information on the mass spectrum derived from high-energy colliders, and the constraints from B-physics experiments. In the presence of new sources of flavour-symmetry breaking, additional significant constraints on the model can be derived also from the two KL->pi0 l+l- modes.Comment: 22 pages, 10 figures (high quality figures available on request

    Agentschappen en de verzelfstandigingsparadox

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    Verzelfstandiging van overheidsorganisaties leidt tot een paradox. Enerzijds krijgen de organisaties meer zelfstandi

    Motivation in physical education across the primary-secondary school transition

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    The purpose of this study was to examine the temporal patterns of approach-avoidance achievement goals, implicit theories of ability and perceived competence in physical education across the transition from primary to secondary school. We also evaluated the predictive utility of implicit theories and perceived competence with regard to achievement goal adoption, and determined the moderating influence of gender on temporal patterns and antecedent–goal relationships. One hundred and forty pupils (mean age at start of study = 11.37 years, SD =.28) completed measures of entity and incremental beliefs, perceived competence and goals on four occasions during a 12-month period. Mastery-approach, performance-approach and perform-ance-avoidance goals, as well as entity and incremental beliefs, exhibited a linear decline over time. Mastery-avoidance goals showed no significant change. Girls exhibited a linear decline in perceived competence, whereas for boys the trajectory was curvilinear. Competence perceptions predicted initial scores, but not rate of change, on mastery-approach and both types of performance goals. Incrementa

    Lignans and breast cancer risk in pre- and post-menopausal women: meta-analyses of observational studies

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    Phyto-oestrogens are plant compounds structurally similar to oestradiol, which have been proposed to have protective effects against breast cancer. The main class of phyto-oestrogens in the Western diet is lignans. Literature reports on the effect of lignans in breast cancer risk have been conflicting. We performed three separate meta-analyses to examine the relationships between (i) plant lignan intake, (ii) enterolignan exposure and (iii) blood enterolactone levels and breast cancer risk. Medline, BIOSIS and EMBASE databases were searched for publications up to 30 September 2008, and 23 studies were included in the random effects meta-analyses. Overall, there was little association between high plant lignan intake and breast cancer risk (11 studies, combined odds ratio (OR): 0.93, 95% confidence interval (95% CI): 0.83-1.03, P = 0.15), but this association was subjected to marked heterogeneity (I-2 = 44%). Restricting the analysis to post-menopausal women, high levels of plant lignan intake were associated with reduced breast cancer risk (7 studies, combined OR: 0.85, 95% CI: 0.78, 0.93, P < 0.001) and heterogeneity was markedly reduced (I-2 = 0%). High enterolignan exposure was also associated with breast cancer (5 studies, combined OR: 0.73, 95% CI: 0.57, 0.92, P = 0.009) but, again, there was marked heterogeneity (I-2 = 63%). No association was found with blood enterolactone levels (combined OR: 0.82, 95% CI: 0.59-1.14, P = 0.24). In conclusion, plant lignans may be associated with a small reduction in post-menopausal breast cancer risk, but further studies are required to confirm these results

    Comparative efficacy of two Ivermectin Pour-on anthelmintics in beef steers in a commercial feedyard

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    Generic products generally have a cost advantage for beef producers over brand-name products. Recently, many beef producers have debated whether to utilize generic anthelmintics in cow/calf herds and feeder cattle. If generics are to be justified, the products must be proven to have efficacy similar to the brand-name product. Previous studies have indicated that generic macrocyclic lactones are less effective in controlling gastrointestinal parasites of cattle than the original brand-name products. The objective of this study was to compare the efficacy of Vetrimec (Norbrook Laboratories Limited, Newry, Co. Down, Northern Ireland) pour-on and Ivomec (Merial Animal Health, Duluth, GA) pour-on by utilizing the fecal egg reduction test in newly arrived feedlot steers

    Synthesis of pentacene nanotubes by melt-assisted template wetting

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    peer-reviewedno abstract availablePUBLISHEDpeer-reviewe

    Schwinger-Keldysh Propagators from AdS/CFT Correspondence

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    We demonstrate how to compute real-time Green's functions for a class of finite temperature field theories from their AdS gravity duals. In particular, we reproduce the two-by-two Schwinger-Keldysh matrix propagator from a gravity calculation. Our methods should work also for computing higher point Lorentzian signature correlators. We elucidate the boundary condition subtleties which hampered previous efforts to build a Lorentzian-signature AdS/CFT correspondence. For two-point correlators, our construction is automatically equivalent to the previously formulated prescription for the retarded propagator.Comment: 16 pages, 1 figure, references added; to appear in JHE

    Universal Extra Dimensions and Kaluza Klein Bound States

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    We study the bound states of the Kaluza-Klein (KK) excitations of quarks in certain models of Universal Extra Dimensions. Such bound states may be detected at future lepton colliders in the cross section for the pair production of KK-quarks near threshold. For typical values of model parameters, we find that "KK-quarkonia" have widths in the 10 - 100 MeV range, and production cross sections of order a few picobarns for the lightest resonances. Two body decays of the constituent KK-quarks lead to distinctive experimental signatures. We point out that such KK resonances may be discovered before any of the higher KK modes.Comment: 21 pages LaTeX, 9 eps figure
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