3,441 research outputs found

    Atmospheric neutrons

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    Contributions to fast neutron measurements in the atmosphere are outlined. The results of a calculation to determine the production, distribution and final disappearance of atmospheric neutrons over the entire spectrum are presented. An attempt is made to answer questions that relate to processes such as neutron escape from the atmosphere and C-14 production. In addition, since variations of secondary neutrons can be related to variations in the primary radiation, comment on the modulation of both radiation components is made

    Reproducing Kernels of Generalized Sobolev Spaces via a Green Function Approach with Distributional Operators

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    In this paper we introduce a generalized Sobolev space by defining a semi-inner product formulated in terms of a vector distributional operator P\mathbf{P} consisting of finitely or countably many distributional operators PnP_n, which are defined on the dual space of the Schwartz space. The types of operators we consider include not only differential operators, but also more general distributional operators such as pseudo-differential operators. We deduce that a certain appropriate full-space Green function GG with respect to L:=PTPL:=\mathbf{P}^{\ast T}\mathbf{P} now becomes a conditionally positive definite function. In order to support this claim we ensure that the distributional adjoint operator P\mathbf{P}^{\ast} of P\mathbf{P} is well-defined in the distributional sense. Under sufficient conditions, the native space (reproducing-kernel Hilbert space) associated with the Green function GG can be isometrically embedded into or even be isometrically equivalent to a generalized Sobolev space. As an application, we take linear combinations of translates of the Green function with possibly added polynomial terms and construct a multivariate minimum-norm interpolant sf,Xs_{f,X} to data values sampled from an unknown generalized Sobolev function ff at data sites located in some set XRdX \subset \mathbb{R}^d. We provide several examples, such as Mat\'ern kernels or Gaussian kernels, that illustrate how many reproducing-kernel Hilbert spaces of well-known reproducing kernels are isometrically equivalent to a generalized Sobolev space. These examples further illustrate how we can rescale the Sobolev spaces by the vector distributional operator P\mathbf{P}. Introducing the notion of scale as part of the definition of a generalized Sobolev space may help us to choose the "best" kernel function for kernel-based approximation methods.Comment: Update version of the publish at Num. Math. closed to Qi Ye's Ph.D. thesis (\url{http://mypages.iit.edu/~qye3/PhdThesis-2012-AMS-QiYe-IIT.pdf}

    Magnetic-Field-Induced Antiferromagnetism in Two-Dimensional Hubbard Model: Analysis of CeRhIn5_5

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    We propose the mechanism for the magnetic-field-induced antiferromagnetic (AFM) state in a two-dimensional Hubbard model in the vicinity of the AFM quantum critical point (QCP), using the fluctuation-exchange (FLEX) approximation by taking the Zeeman energy due to the magnetic field BB into account. In the vicinity of the QCP, we find that the AFM correlation perpendicular to BB is enhanced, whereas that parallel to BB is reduced. This fact means that the finite magnetic field increases TNT_N, with the AFM order perpendicular to BB. The increment in TNT_N can be understood in terms of the reduction of both quantum and thermal fluctuations due to the magnetic field, which is caused by the self-energy effect within the FLEX approximation. The present study naturally explains the increment in TNT_N in CeRhIn_5 under the magnetic field found recently.Comment: 5 page

    The integrated academic information system support for education 3.0 in higher education institution: lecturer perspective

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    Education 3.0 has been implemented in many higher education institutions (HEIs). Education 3.0 has been directed the institution toward better educational experience. But on the other hands, the implementation of Education 3.0 also caused some problems. Previous research has found administrative problem experienced by the lecturer. This research explores deeper from the lecturer and suggested the solution from lecturer perspective, combined with information technology capabilities owned by the HEIs. The research used a case study as the method and conducted a qualitative research with a semi-structured interview. The interview analysis has found that the increase of the administrative processes is caused by online and offline administrative activities. The online activities are from e-learning and the offline activities are from traditional learning (face-to-face). The administrative processes also involved the academic information system (AIS). Simplified all of the administrative processes are more preferred. To overcome the problems, integrating the AIS and e-learning become necessary. This research suggests transforming the existing AIS into an integrated AIS and hopes the solution can simplify the administration process

    The reform of the English National Health Service: professional dominance, countervailing powers and the buyers’ revolt

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    The 2012 English Health and Social Care Act marked a fundamental reform of statutory healthcare in England in ways which elevated the interests of the government over the interests of patients or the professions, and which undermined traditional alliances between professions and patients. Drawing on a countervailing powers framework we present a thematic analysis of parliamentary papers, press releases and other publicly available materials produced across the reform process by four key actors in the healthcare field—the government, medical profession, patients and ‘for profit’ providers. This analysis explores how the pursuit of sectional interests by these actors may have acted to constrain potential alliances and ultimately contributed to the enactment of the legislation by default. This conclusion has relevance for other Beveridge model healthcare systems undergoing health and social care reform under the auspices of austerity

    Evanescent light-matter Interactions in Atomic Cladding Wave Guides

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    Alkali vapors, and in particular rubidium, are being used extensively in several important fields of research such as slow and stored light non-linear optics3 and quantum computation. Additionally, the technology of alkali vapors plays a major role in realizing myriad industrial applications including for example atomic clocks magentometers8 and optical frequency stabilization. Lately, there is a growing effort towards miniaturizing traditional centimeter-size alkali vapor cells. Owing to the significant reduction in device dimensions, light matter interactions are greatly enhanced, enabling new functionalities due to the low power threshold needed for non-linear interactions. Here, taking advantage of the mature Complimentary Metal-Oxide-Semiconductor (CMOS) compatible platform of silicon photonics, we construct an efficient and flexible platform for tailored light vapor interactions on a chip. Specifically, we demonstrate light matter interactions in an atomic cladding wave guide (ACWG), consisting of CMOS compatible silicon nitride nano wave-guide core with a Rubidium (Rb) vapor cladding. We observe the highly efficient interaction of the electromagnetic guided mode with the thermal Rb cladding. The nature of such interactions is explained by a model which predicts the transmission spectrum of the system taking into account Doppler and transit time broadening. We show, that due to the high confinement of the optical mode (with a mode area of 0.3{\lambda}2), the Rb absorption saturates at powers in the nW regime.Comment: 10 Pages 4 Figures. 1 Supplementar

    Scarring Effects on Tunneling in Chaotic Double-Well Potentials

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    The connection between scarring and tunneling in chaotic double-well potentials is studied in detail through the distribution of level splittings. The mean level splitting is found to have oscillations as a function of energy, as expected if scarring plays a role in determining the size of the splittings, and the spacing between peaks is observed to be periodic of period {2π2\pi\hbar} in action. Moreover, the size of the oscillations is directly correlated with the strength of scarring. These results are interpreted within the theoretical framework of Creagh and Whelan. The semiclassical limit and finite-{\hbar} effects are discussed, and connections are made with reaction rates and resonance widths in metastable wells.Comment: 22 pages, including 11 figure

    A Chinese Model for Labour in Europe?

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    Based on long-term fieldwork in multiple locations, our article questions the approach that posits a Chinese model of work and employment relations as increasingly exporting its form of labour management and dominating worldwide. It does so by focusing on Europe and discussing two labour regimes considered as typically Chinese: the Chinese fashion workshops in the Italian fashion industry, and the Foxconn electronics plants in the Czech Republic. Our findings bring new insights to bear on issues for which research is still thin on the ground and challenge the hypothesis of a \u2018Chinesisation\u2019 of work and employment practices in Chinese small firms and MNCs operating in Europe. We move the focus away from the simple analysis of firm management prevailing in the literature and suggest that, in order to understand the firm\u2019s behaviours, the role of the state, the unions, the migrant workers and the role of temporary work agencies should all be taken into consideration
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