3,262 research outputs found

    A hierarchy of models for superconducting thin films

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    A hierarchy of models for type-II superconducting thin films is presented. Through appropriate asymptotic limits this hierarchy passes from the mesoscopic Ginzburg--Landau model to the London model with isolated vortices as ÎŽ\delta-function singularities to vortex-density models and finally to macroscopic critical-state models. At each stage it is found that a key nondimensional parameter is Λ=λ2/dL\Lambda = \lambda^2/d L, where λ\lambda is the penetration depth of the magnetic field, a material parameter, and d and L are a typical thickness and lateral dimension of the film,respectively. The models simplify greatly if this parameter is large or small

    Theory Of Spin Waves In Heisenberg Ferromagnetic And Antiferromagnetic Thin Films With Nonuniaxial Single-ion Anisotropy

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    This thesis describes the microscopic, quantum mechanical theory of exchange-dominated spin waves in Heisenberg ferromagnetic and antiferromagnetic thin films including the effects of nonuniaxial single-ion anisotropy. The results constitute a generalization of previous theoretical studies on spin waves in thin films with uniaxial anisotropy and in semi-infinite ferromagnets with nonuniaxial anisotropy.;A spin Hamiltonian containing nearest-neighbour exchange terms, Zeeman terms, and single-ion anisotropy terms is used. The films may be asymmetric with respect to surface exchange and anisotropy parameters which are also assured to be perturbed from the bulk values. The results apply both to cases in which the nonuniaxial anisotropy is an intrinsic aspect of the material and where it arises only at the surfaces as a consequence of lowered symmetry for those sites. Low temperatures are assumed where the linear spin-wave approximation is valid. The formalism is developed for arbitrary film thickness, arbitrary quantum spin number S, and perpendicular magnetization. Simple cubic (001) ferromagnetic systems and body-centered tetragonal (001) antiferromagnetic systems are specifically examined with extensions to other situations outlined.;A theoretical approach based on the equation-of-motion method is used to find Green functions which provide expressions for the dispersion relations for surface and quantized bulk spin waves, the associated spectral intensities, transverse spin correlation functions, and the dynamic response of the system in, for example, light scattering and spin wave resonance experiments. Representative numerical examples are provided for the dispersion relation results, some thermodynamic properties related to the mean-squared amplitude and ellipticity of spin precession, and the static magnetization. The use of the Green function results in calculating the light scattering cross-sections and absorption strength in spin wave resonance is outlined. Procedures developed to manage the increased mathematical complication associated with the nonuniaxial anisotropy are described

    Concussion assessment in cycling: a systematic review and call to action

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    Purpose:Concussion is a recognised risk in road cycling and can have serious health consequences1, especially when mismanaged. Epidemiological studies estimate that concussions account for 4-13% of all cycling injuries2-4and that the incidence of concussions is increasing5. The high-profile case of Toms Skujins in the 2017 Tour of California, who was initially allowed to continue riding despite demonstrating obvious ataxia following a crash, highlighted the lack of a concussion assessment protocol in road cycling. Aim: a systematic review of the literature on concussion assessmentin cycling.Methods:literature describing concussion assessment in cycling was identified by searching MEDLINE, EMBASE, PsycINFO & Web of Science. Two reviewers independently screened titles andabstracts for eligibility. Figure 1 demonstrates the flow diagram of reviewed and included studies. A qualitative analysis was undertaken of included studies.Results:From 94 studies identified, 2 were included for review. Gordon et al. 20136describe the presentation of a single case of paediatric concussion following a cycling crash and highlights the utility of evaluation using the Sport Concussion Assessment Tool7(SCAT5) as well as the importance of a stepwise return-to-play protocol. Greve & Modabber 20128discuss a number of traumatic brain injuries that occurred during the 2011 road cycling season and, as a minimum, calls for riders to be withdrawn from riding following loss of consciousness or amnesia. Discussion:Road cycling poses a unique challenge for the assessment of concussion and we have found there is little published evidence to advise effective means of in-race assessment. Following a potentially concussive impact, the decision to allow a rider to continue or not, must be made quickly and in sub-optimal conditions. Indeed it is not possible to temporarily withdraw a rider for a ‘sideline assessment’. Moreover medical personnel are often unable to observe the rider directly and rely on radio communication for assessment. The recent Berlin Consensus Statement on Concussion in Sport9states that “Adequate facilities should be provided for the appropriate medical assessment both on and off the field for all injured athletes. In some sports, this may require rule changes to allow an appropriate off-field medical assessment to occur without affecting the flow of the game or unduly penalising the injured player’s team.” Action must be taken to increase adherenceto the Berlin Consensus statement within cycling. Whilst the UCI Cycling Regulations10discuss multi-modal assessment in suspected concussion and the need for immediate withdrawal from competition/training if concussion is suspected, no internationally-agreed assessment protocol for concussion in road cycling has been published. The UCI regulations advise the use of SCAT5 for concussion assessment but this tool is impractical to use in-competition and would require modifications for use in road cycling, particularly for in-competition assessments. Abramson et al. of USA Cycling/MedicineofCycling.com have produced a concussions in cycling consensus statement11but with limited race-specific assessment instructions and the statement has not been published in a peer-reviewed journal.Conclusion:We would like to call on the UCI to hold a consensus meeting to establish an evidence-based concussion assessment protocol and return-to-riding protocol for road cycling. These protocols would need to be multi-lingual and should consider the role of both medical and non-medical personnel, e.g. neutral mechanics, who may be the first responder following a crash

    The timing of maternal depressive symptoms and child cognitive development: a longitudinal study.

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    Background: Maternal depression is known to be associated with impairments in child cognitive development, although the effect of timing of exposure to maternal depression is unclear. Methods: Data collected for the Avon Longitudinal Study of Parents and Children, a longitudinal study beginning in pregnancy, included self-report measures of maternal depression the Edinburgh Postnatal Depression Scale, completed on 6 occasions up to 3 years of age, and IQ of the index child (WISC) measured at aged 8 years. We used these data to assign women to 8 groups according to whether depression occurred in the antenatal, postnatal, preschool period, any combination of these times, or not at all. We compared a model comprising all patterns of depression (saturated model) with models nested within this to test whether there is a relationship between depression and child cognitive development and, if so, whether there is a sensitive period. We then investigated the relationship with child IQ for each model, following adjustment for confounders. Results: Six thousand seven hundred and thirty-five of 13,615 children from singleton births (49.5%, of eligible core sample) attended a research clinic at 8 years and completed a WISC with a score ≄ 70. A total of 5,029 mothers of these children had completed mood assessments over the 3 time periods. In unadjusted analyses, all three sensitive period models were as good as the saturated model, as was an accumulation model. Of the sensitive period models, only that for antenatal exposure was a consistently better fit than the accumulation model. After multiple imputation for missing data (to n = 6,735), there was no effect of postnatal depression on child IQ independent of depression at other times [-0.19 IQ points, 95% confidence interval (CI) -1.5 to 1.1 points]. There was an effect of antenatal depression (-3.19 IQ points, 95% CI: -4.33 to -2.06) which attenuated following adjustment (-0.64 IQ points, 95% CI: -1.68 to 0.40). Conclusions: The postnatal period is not a sensitive one for the effect of maternal depression on child cognitive development. © 2011 The Authors. Journal of Child Psychology and Psychiatry

    An Interview with John Heron: Exploring the Interface between Cooperative Inquiry and Transpersonal Studies

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    In this interview, John Heron—the founder of cooperative inquiry (CI; Heron, 1996, 1998)—discusses this experiential, participatory approach to research and learning with participatory research special issue guest editor Olga Sohmer. After presenting a summary of cooperative inquiry, Heron and Sohmer discuss CI in the context of transpersonal studies, including past and prospective future applications. Questioning the emphasis on “trans” in transpersonal, Heron unfolds the three dimensions of human spirituality that CI engages and offers a vision for transpersonal studies in light of CI ideals. Additional themes that are explored include cultivating authentic relationships in CI, the role of the nonhuman natural world in CI, practices based on CI principles that can be used in daily life, applying extended epistemology and radical assessment in education, self-generating culture, and the role of CI in human evolution

    The motion of superconducting vortices in thin films of varying thickness

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    The interaction of superconducting vortices with superconductor/vacuum interfaces is considered. A vortex is first shown to intersect such an interface normally. Various thin-film models are then formulated, corresponding to different parameter regimes. A local analysis of a vortex is performed, and a law of motion for each vortex deduced. This law of motion implies that the vortex will move to the locally thinnest part of the film, and is consistent with the vortex moving under the curvature induced by being forced to intersect the boundaries of the film normall

    Penentuan Indeks Kerentanan Pantai Akibat Kenaikan Muka Laut Di Pantai Bagian Barat Provinsi Banten

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    Shore is the area in side water and still have influence from tidal highest and lowest water. Shore vulnerability can decided with to look some factor which to influence, that is shoreline change, relative sea level, mean wave height, tidal range, coastal slope and geomorphology. Sixth factor\u27s above were factor\u27s which to influence shore vulnerability to sea level rise. This research aim was to know area vulnerability level in research location. Data\u27s which used in this research was Landsat TM 1997 and Landsat ETM+ 2009, Landuse map, SRTM (Shuttle Radar Topography Mission) Data, Tide, signifikan wave height, sea level rise relative, map batimetri. Metode which used in this research is with to analysis some data for to give result shore vulnerability index from aspect physical in research location with the data start from year 1997-2009. The result showed that based shore vulnerability index, area in the along shore part of west Banten which include to very high category is cikoneng village and which include to very low category is Pasauran, Carita, Caringin, and Margagiri Village.Key Words : Sea Level Rise, vulnerability, Shore, Province Bante

    Capital Misallocation and Economic Development in a Dynamic Open Economy

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    Some countries such as Canada, Italy, and Mexico have experienced a higher growth rate of capital per worker but a lower growth rate for GDP per worker when compared to the United States. This paper tries to reconcile this apparent contradiction in a dynamic open economy model. In the model, capital accumulation and exogenous technology adoption jointly generate output growth. In this environment, sectors with higher import participation have, ceteris paribus, a lower markup over production costs that in equilibrium implies a higher production level. Furthermore, when either sectoral import participation or sectoral productivity changes, capital allocation across sectors is affected, altering the actual rate of return on capital and triggering capital accumulation at a rate that differs from the long-run rate of technology adoption. We calibrate the model for the Mexican economy for 1995-2011. The results show that sectors with a reduction in TFP (total factor productivity) increased capital participation in the aggregate capital formation from 93.5% to 95.7% in the period. Furthermore, if the sectoral productivities had remained constant at the initial level in a counterfactual exercise, the aggregate output would be higher than its initial level, with capital accumulation increasing 74% and driving the rise in GDP
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