1,358 research outputs found

    Determination of Asymptotic Waves in Maxwell Media by Double-Scale Method

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    In this paper, in a thermodynamical model of a rheological medium (Maxwell) with one internal variable, derived in the framework of classical irreversible thermodynamics, the asymptotic smooth waves, studied in (1) in a more classical way, are introduced from the point of view of double scale method (see (2)). We give a physical interpretation of the new (fast) variable, related to the surface across which the derivatives of the solution vary steeply. An one-dimensional application is carried out too

    Stochastic modelling of the spatial spread of influenza in Germany

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    In geographical epidemiology, disease counts are typically available in discrete spatial units and at discrete time-points. For example, surveillance data on infectious diseases usually consists of weekly counts of new infections in pre-defined geographical areas. Similarly, but on a different time-scale, cancer registries typically report yearly incidence or mortality counts in administrative regions. A major methodological challenge lies in building realistic models for space-time interactions on discrete irregular spatial graphs. In this paper, we will discuss an observation-driven approach, where past observed counts in neighbouring areas enter directly as explanatory variables, in contrast to the parameter-driven approach through latent Gaussian Markov random fields (Rue and Held, 2005) with spatio-temporal structure. The main focus will lie on the demonstration of the spread of influenza in Germany, obtained through the design and simulation of a spatial extension of the classical SIR model (Hufnagel et al., 2004)

    Flammability Tests on Hot Surface for Several Hydraulic Fluids

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    Industrial equipment using hydraulic fluids are design to accept higher load and speed, implicitly higher temperatures, including for fluids. Leakages from enclosures like gear boxes or hydraulic systems could increase the risk of fluid reaching hot surfaces, thus producing fires hard to be controlled and isolated. The designer have to evaluate the flammability of fluids and they should select several solutions for a particular application in order to estimate the costs of different solutions and to mitigate the risk of having accidental fires due to a specific fluid grade. The tests were done with the help of an original equipment allowing a dedicated soft assistance in order to protect the operator and to sustain reproducibility, according to the standard SR EN ISO 20823:2004 Petroleum and related products. The determination of the flammability characteristics of fluids in contact with hot surfaces - Manifold ignition test, There were tested the following grades of hydraulic oil HLP 68 X-Oil, HFC Prista, MHE 40 Prista (100% oil), a rapeseed oil (obtained after a dewaxing process) and an emulsion oil-in-water (5% vol. MHE 40 Prista). There were identified distinct behaviours of these fluids under the test condition

    Why we interact : on the functional role of the striatum in the subjective experience of social interaction

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    Acknowledgments We thank Neil Macrae and Axel Cleeremans for comments on earlier versions of this manuscript. Furthermore, we are grateful to Dorothé Krug and Barbara Elghahwagi for their assistance in data acquisition. This study was supported by a grant of the Köln Fortune Program of the Medical Faculty at the University of Cologne to L.S. and by a grant “Other Minds” of the German Ministry of Research and Education to K.V.Peer reviewedPreprin

    Second order perturbation theory for embedded eigenvalues

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    We study second order perturbation theory for embedded eigenvalues of an abstract class of self-adjoint operators. Using an extension of the Mourre theory, under assumptions on the regularity of bound states with respect to a conjugate operator, we prove upper semicontinuity of the point spectrum and establish the Fermi Golden Rule criterion. Our results apply to massless Pauli-Fierz Hamiltonians for arbitrary coupling.Comment: 30 pages, 2 figure

    On perturbations of Dirac operators with variable magnetic field of constant direction

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    We carry out the spectral analysis of matrix valued perturbations of 3-dimensional Dirac operators with variable magnetic field of constant direction. Under suitable assumptions on the magnetic field and on the pertubations, we obtain a limiting absorption principle, we prove the absence of singular continuous spectrum in certain intervals and state properties of the point spectrum. Various situations, for example when the magnetic field is constant, periodic or diverging at infinity, are covered. The importance of an internal-type operator (a 2-dimensional Dirac operator) is also revealed in our study. The proofs rely on commutator methods.Comment: 12 page

    Therapeutic Considerations Related to Finasteride Administration in Male Androgenic Alopecia and Benign Prostatic Hyperplasia

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    Finasteride has been used extensively until now as a relative efficient therapeutic option for male androgenic alopecia and benign prostatic hyperplasia. Unfortunately, over time several concerns appeared regarding the frequency and magnitude of adverse effects, which in some cases have been even irreversible. Herein we review the recent literature on this topic, trying to clarify the current safety profile of Finasteride for these two therapeutic indications. We concluded that Finasteride could be retained as a therapeutic approach for male androgenic alopecia, based on two important reasons. First, a synergistic action between a partial inhibitor of 5α-reductase (Finasteride) and another compound (like Minoxidil) are preferable to a complete suppression of 5α-reductase (see Dutasteride), in order to preserve the important physiological roles of dihydrotestosterone. Second, Finasteride side effects can currently be addressed in part prior to the onset of the therapy, by using information about the patient such as hand preference and sexual orientation to predict the risk of adverse effects

    Spectral theory for a mathematical model of the weak interaction: The decay of the intermediate vector bosons W+/-, II

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    We do the spectral analysis of the Hamiltonian for the weak leptonic decay of the gauge bosons W+/-. Using Mourre theory, it is shown that the spectrum between the unique ground state and the first threshold is purely absolutely continuous. Neither sharp neutrino high energy cutoff nor infrared regularization are assumed.Comment: To appear in Ann. Henri Poincar\'
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