733 research outputs found

    Massive Dirac particles on the background of charged de-Sitter black hole manifolds

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    We consider the behavior of massive Dirac fields on the background of a charged de-Sitter black hole. All black hole geometries are taken into account, including the Reissner-Nordstr\"{o}m-de-Sitter one, the Nariai case and the ultracold case. Our focus is at first on the existence of bound quantum mechanical states for the Dirac Hamiltonian on the given backgrounds. In this respect, we show that in all cases no bound state is allowed, which amounts also to the non-existence of normalizable time-periodic solutions of the Dirac equation. This quantum result is in contrast to classical physics, and it is shown to hold true even for extremal cases. Furthermore, we shift our attention on the very interesting problem of the quantum discharge of the black holes. Following Damour-Deruelle-Ruffini approach, we show that the existence of level-crossing between positive and negative continuous energy states is a signal of the quantum instability leading to the discharge of the black hole, and in the cases of the Nariai geometry and of the ultracold geometries we also calculate in WKB approximation the transmission coefficient related to the discharge process.Comment: 19 pages, 11 figures. Macro package: Revtex4. Changes concern mainly the introduction and the final discussion in section VI; moreover, Appendix D on the evaluation of the Nariai transmission integral has been added. References adde

    Inverse Eigenvalue Problems for Perturbed Spherical Schroedinger Operators

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    We investigate the eigenvalues of perturbed spherical Schr\"odinger operators under the assumption that the perturbation q(x)q(x) satisfies xq(x)L1(0,1)x q(x) \in L^1(0,1). We show that the square roots of eigenvalues are given by the square roots of the unperturbed eigenvalues up to an decaying error depending on the behavior of q(x)q(x) near x=0x=0. Furthermore, we provide sets of spectral data which uniquely determine q(x)q(x).Comment: 14 page

    Green's function for a Schroedinger operator and some related summation formulas

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    Summation formulas are obtained for products of associated Lagurre polynomials by means of the Green's function K for the Hamiltonian H = -{d^2\over dx^2} + x^2 + Ax^{-2}, A > 0. K is constructed by an application of a Mercer type theorem that arises in connection with integral equations. The new approach introduced in this paper may be useful for the construction of wider classes of generating function.Comment: 14 page

    Absence of Normalizable Time-periodic Solutions for The Dirac Equation in Kerr-Newman-dS Black Hole Background

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    We consider the Dirac equation on the background of a Kerr-Newman-de Sitter black hole. By performing variable separation, we show that there exists no time-periodic and normalizable solution of the Dirac equation. This conclusion holds true even in the extremal case. With respect to previously considered cases, the novelty is represented by the presence, together with a black hole event horizon, of a cosmological (non degenerate) event horizon, which is at the root of the possibility to draw a conclusion on the aforementioned topic in a straightforward way even in the extremal case.Comment: 12 pages. AMS styl

    Quantitative analysis of particles, genomes and infectious particles in supernatants of haemorrhagic fever virus cell cultures

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    Information on the replication of viral haemorrhagic fever viruses is not readily available and has never been analysed in a comparative approach. Here, we compared the cell culture growth characteristics of haemorrhagic fever viruses (HFV), of the Arenaviridae, Filoviridae, Bunyaviridae, and Flavivridae virus families by performing quantitative analysis of cell culture supernatants by (i) electron microscopy for the quantification of virus particles, (ii) quantitative real time PCR for the quantification of genomes, and (iii) determination of focus forming units by coating fluorescent antibodies to infected cell monolayers for the quantification of virus infectivity

    Multiparticle equations for interacting Dirac fermions in magnetically confined graphene quantum dots

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    We study the energy of quasi-particles in graphene within the Hartree-Fock approximation. The quasi-particles are confined via an inhomogeneous magnetic field and interact via the Coulomb potential. We show that the associated functional has a minimizer and determines the stability conditions for the N-particle problem in such a graphene quantum dot

    Effects of an educational intervention to strengthen humanistic practice on haemodialysis nurses' caring attitudes and behaviours and quality of working life: a cluster randomised controlled trial.

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    Nurses are trained to establish a trusting relationship with patients to create an environment promoting patients' quality of life. However, in tech-heavy care settings, such as haemodialysis units, dehumanising practices may emerge and take root for various reasons to the potential detriment of both patients and nurses. For patients, this may lead to a deterioration of quality of life and, ultimately, of health status. For nurses, it may cause a deterioration of the work environment and, in turn, of quality of working life. Based on Watson's Theory of Human Caring, we developed a brief educational intervention for haemodialysis nurses to strengthen their humanistic practice in the aim of improving the nurse-patient relationship and nurse quality of working life.. The intervention was tested by way of an experimental design. One hundred and one haemodialysis nurses, recruited in ten hospitals in French-speaking Switzerland, were randomised into an experimental group that received the intervention and a control group. The nurse-patient relationship was measured with the Caring Nurse-Patient Interaction Scale (EIIP-70) and nurse quality of life at work was measured with the Quality of Work Life Questionnaire at four time points: pre-intervention, intervention completion, and six-month and one-year follow-ups. Random intercept regression analysis was used to evaluate change over time in the two variables under study. The intervention appeared to reinforce nurse attitudes and behaviours geared to a more humanistic practice. The effect seemed to fade over time but, 1 year post-intervention, six dimensions of the nurse-patient relationship (hope, sensibility, helping relationship, expression of emotions, problem solving, teaching) scored above baseline. Nurse quality of working life, too, seemed positively impacted. The cultural dimension of nurse quality of working life, that is, the degree to which everyday work activities attune with personal and cultural values, seemed positively impacted, as well, with improvement stable throughout the year following the intervention. Results support a positive effect of the intervention over both the short term and the medium-to-long term. A brief intervention of the sort may constitute an effective means to improve the nurse-patient relationship by preventing or reducing dehumanising practices. NCT03283891

    Quantum Effects for the Dirac Field in Reissner-Nordstrom-AdS Black Hole Background

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    The behavior of a charged massive Dirac field on a Reissner-Nordstrom-AdS black hole background is investigated. The essential self-adjointness of the Dirac Hamiltonian is studied. Then, an analysis of the discharge problem is carried out in analogy with the standard Reissner-Nordstrom black hole case.Comment: 18 pages, 5 figures, Iop styl

    Comparison of Chlamydia antigen and AD-like pathology in the brains of BALB/c mice following intranasal infection with Chlamydia muridarum or Chlamydia pneumoniae

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    Previous research indicates BALB/c mice inoculated with Chlamydia pneumoniae (Cpn) demonstrated AD-like pathology which suggests that this mouse model is valid for studying the pathogenesis implicated in Alzheimer’s disease (AD). Studies have demonstrated that Chlamydia trachomatis (Ctr) can disseminate from its primary site of infection and plays a major role in the induction of reactive arthritis. The objectives of this lab are: (1) to identify and localize Chlamydia antigens in the brains of BALB/c mice infected with C. muridarum and (2) to determine if infection with C. muridarum induces AD-like pathology comparable to Cpn. Using mouse adapted respiratory isolates of C. muridarum, we investigated whether C. muridarum disseminated from the respiratory tract to the brain. Mice were intranasally infected with plaqued C small Weiss (CSW) or plaqued mouse pneumonitis Weiss (MoPn Weiss). Brain tissue was isolated at 2 months post-infection. Serial sections from brains infected mice were analyzed for amyloid or Chlamydia antigens. Preliminary analysis of brain tissue demonstrated no detectable difference in C. muridarum antigen between mice receiving 1 x105 IFU and mice receiving 1 x101 IFU, whereas a small but detectable difference was identified in amyloid-specific labeling between these two experimental groups. In contrast, prominent Chlamydia-specific labeling was identified in the brains of Cpn-infected mice as well as substantial amyloid deposition at 2 months p.i.. These data suggest that, relative to Cpn AR-39 infection, C. muridarum infection is a weaker stimulus for inflammation, resulting in decreased amyloid deposition in the brains of BALB/c mice
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