1,019 research outputs found

    Origin of gamma-ray emission in the shell of Cassiopeia A

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    Non-thermal X-ray emission from the shell of Cassiopeia A (Cas A) has been an interesting subject of study, as it provides information about relativistic electrons and their acceleration mechanisms in the shocks. Chandra X-ray observatory revealed the detailed spectral and spatial structure of this SNR in X-rays. The spectral analysis of Chandra X-ray data of Cas A shows unequal flux levels for different regions of the shell, which can be attributed to different magnetic fields in those regions. Additionally, the GeV gamma-ray emission observed by Large Area Telescope on board Fermi Gamma Ray Space Telescope showed that the hadronic processes are dominating in Cas A, a clear signature of acceleration of protons. In this paper we aim to explain the GeV-TeV gamma-ray data in the context of both leptonic and hadronic scenario. We modeled the multi-wavelength spectrum of Cas A. We use synchrotron emission process to explain the observed non-thermal X-ray fluxes from different regions of the shell. These result in estimation of the model parameters, which are then used to explain TeV gamma-ray emission spectrum. We also use hadronic scenario to explain both GeV and TeV fluxes simultaneously. We show that a leptonic model alone cannot explain the GeV-TeV data. Therefore, we need to invoke a hadronic model to explain the observed GeV-TeV fluxes. We found that although pure hadronic model is able to explain the GeV-TeV data, a lepto-hadronic model provides the best fit to the data.Comment: Accepted in A&

    Beyond E11

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    We study the non-linear realisation of E11 originally proposed by West with particular emphasis on the issue of linearised gauge invariance. Our analysis shows even at low levels that the conjectured equations can only be invariant under local gauge transformations if a certain section condition that has appeared in a different context in the E11 literature is satisfied. This section condition also generalises the one known from exceptional field theory. Even with the section condition, the E11 duality equation for gravity is known to miss the trace component of the spin connection. We propose an extended scheme based on an infinite-dimensional Lie superalgebra, called the tensor hierarchy algebra, that incorporates the section condition and resolves the above issue. The tensor hierarchy algebra defines a generalised differential complex, which provides a systematic description of gauge invariance and Bianchi identities. It furthermore provides an E11 representation for the field strengths, for which we define a twisted first order self-duality equation underlying the dynamics.Comment: 97 pages. v2: Minor changes, references added. Published versio

    Definition of the Ethical Values and Ethics Codes for Turkish Midwifery: A Focused Group Study in Kocaeli

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    Background: The independent roles of midwives have not been properly defined, and midwifery ethical values and moral codes proper to Turkish culture have not been developed. The absence of legal regulations concerning midwifery has negatively affected midwifery in the process of professionalization. Objectives: The purpose of this study was to identify the professional values of midwifery in Turkey. Materials and Methods: A focus group was created with the participation of nine midwives working at two state hospitals and a university hospital that provide birth service for women in Kocaeli, which is the most important industrial city in Turkey. The opinions of the midwives on the characteristics that a good midwife should possess and the professional values that a good midwife should observe were collected via in-depth interviews. The interviews were recorded. A total of three meetings were held with the participants. Finally, the notes taken by the reporter during these interviews were rearranged, and the recordings were transcribed by the researchers. Results: The characteristics suggested by the participants were classified into three categories: professional, personal, and interpersonal. Professional competence, capacity to properly inform interested parties, trustworthiness, respect for individuals and human dignity, and empathy were the most commonly named characteristics. As for the professional values of midwifery, professional competence, trustworthiness, responsibility, maximum benefit, and protection of privacy were the most often identified. Midwives also reported that most of the difficulties they faced in the exercise of daily tasks concerned protecting the privacy of their patients as well as the integrity and prestige of the profession, achieving the maximum benefit and least harm for patients, and providing a just and equal service. Conclusions: The professional values were mentioned by participant midwives were similar to the values proposed by international professional organizations. But there were some differences perhaps due to cultural differences

    Acute brucella melitensis M16 infection model in mice treated with tumor necrosis factor-alpha inhibitors

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    Introduction: There is limited data in the literature about brucellosis related to an intracellular pathogen and anti-tumor necrosis factor alpha (anti-TNFα) medication. The aim of this study was to evaluate acute Brucella infections in mice receiving anti-TNFα drug treatment. Methodology: Anti-TNFα drugs were injected in mice on the first and fifth days of the study, after which the mice were infected with B. melitensis M16 strain. Mice were sacrificed on the fourteenth day after infection. Bacterial loads in the liver and spleen were defined, and histopathological changes were evaluated. Results: Neither the liver nor the spleen showed an increased bacterial load in all anti-TNFα drug groups when compared to a non-treated, infected group. The most significant histopathological findings were neutrophil infiltrations in the red pulp of the spleen and apoptotic cells with hepatocellular pleomorphism in the liver. There was no significant difference among the groups in terms of previously reported histopathological findings, such as extramedullary hematopoiesis and granuloma formation. Conclusions: There were no differences in hepatic and splenic bacterial load and granuloma formation, which indicate worsening of the acute Brucella infection in mice; in other words, anti-TNFα treatment did not exacerbate the acute Brucella spp. infection in mice. © 2015 Kutlu et al

    Witten-Nester Energy in Topologically Massive Gravity

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    We formulate topologically massive supergravity with cosmological constant in the first order formalism, and construct the Noether supercurrent and superpotential associated with its local supersymmetry. Using these results, we construct in ordinary topologically massive gravity the Witten-Nester integral for conserved charges containing spinors which satisfy a generalized version of Witten equation on the initial value surface. We show that the Witten-Nester charge, represented as an integral over the boundary of the initial value surface produces the Abbott-Deser-Tekin energy for asymptotically anti de Sitter spacetimes. We consider all values of the Chern-Simons coupling constant, including the critical value known as the chiral point, and study the cases of standard Brown-Henneaux boundary conditions, as well as their weaker version that allow a slower fall-off. Studying the Witten-Nester energy as a bulk integral over the initial value surface instead, we find a bound on the energy, and through it the sufficient condition for the positivity of the energy. In particular, we find that spacetimes of Petrov type N that admit globally well defined solutions of the generalized Witten equation have positive energy.Comment: 43 page

    Kundt spacetimes as solutions of topologically massive gravity

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    We obtain new solutions of topologically massive gravity. We find the general Kundt solutions, which in three dimensions are spacetimes admitting an expansion-free null geodesic congruence. The solutions are generically of algebraic type II, but special cases are types III, N or D. Those of type D are the known spacelike-squashed AdS_3 solutions, and of type N are the known AdS pp-waves or new solutions. Those of types II and III are the first known solutions of these algebraic types. We present explicitly the Kundt solutions that are CSI spacetimes, for which all scalar polynomial curvature invariants are constant, whereas for the general case we reduce the field equations to a series of ordinary differential equations. The CSI solutions of types II and III are deformations of spacelike-squashed AdS_3 and the round AdS_3, respectively.Comment: 30 pages. This material has come from splitting v1 of arXiv:0906.3559 into 2 separate papers. v2: minor changes

    Supersymmetric Higher Spin Theories

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    We revisit the higher spin extensions of the anti de Sitter algebra in four dimensions that incorporate internal symmetries and admit representations that contain fermions, classified long ago by Konstein and Vasiliev. We construct the dS4dS_4, Euclidean and Kleinian version of these algebras, as well as the corresponding fully nonlinear Vasiliev type higher spin theories, in which the reality conditions we impose on the master fields play a crucial role. The N=2{\cal N}=2 supersymmetric higher spin theory in dS4dS_4, on which we elaborate further, is included in this class of models. A subset of Konstein-Vasiliev algebras are the higher spin extensions of the AdS4AdS_4 superalgebras osp(4N)osp(4|{\cal N}) for N=1,2,4{\cal N}=1,2,4 mod 4 and can be realized using fermionic oscillators. We tensor the higher superalgebras of the latter kind with appropriate internal symmetry groups and show that the N=3{\cal N}=3 mod 4 higher spin algebras are isomorphic to those with N=4{\cal N}=4 mod 4. We describe the fully nonlinear higher spin theories based on these algebras as well, and we elaborate further on the N=6{\cal N}=6 supersymmetric theory, providing two equivalent descriptions one of which exhibits manifestly its relation to the N=8{\cal N}=8 supersymmetric higher spin theory.Comment: 30 pages. Contribution to J. Phys. A special volume on "Higher Spin Theories and AdS/CFT" edited by M. R. Gaberdiel and M. Vasilie

    More on Massive 3D Supergravity

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    Completing earlier work on three dimensional (3D) N=1 supergravity with curvature-squared terms, we construct the general supergravity extension of cosmological massive gravity theories. We expand about supersymmetric anti-de Sitter vacua, finding the conditions for bulk unitarity and the critical points in parameter space at which the spectrum changes. We discuss implications for the dual conformal field theory.Comment: v1 : 53 pages, 1 figure; v2 : significantly shortened, 42 p., version published in Class. Quant. Gra
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