31,701 research outputs found

    A Rotating Charged Black Hole Solution in f(R) Gravity

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    In the context of f(R) theories of gravity, we address the problem of finding a rotating charged black hole solution in the case of constant curvature. The new metric is obtained by solving the field equations and we show that the behavior of it is typical of a rotating charged source. In addition, we analyze the thermodynamics of the new black hole. The results ensures that the thermodynamical properties in f(R) gravities are qualitatively similar to those of standard General Relativity.Comment: 9 pages, no figure

    Contraceptive knowledge and practice among HIV-positive women receiving antiretroviral therapy at a district hospital in KwaZulu-Natal

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    Objectives: To determine the knowledge and use of contraceptives by HIV-positive women attending an ART clinic.Design: Observational descriptive cross-sectional study.Setting and subjects: Many human immunodeficiency virus (HIV)-positive South African women fall pregnant each year while receiving antiretroviral therapy (ART). In 2010, 2 056 women of childbearing age attended the ART clinic at a district hospital south of Durban. Between October 2010 and June 2011, data were collected using a validated questionnaire from400 women on their contraceptive knowledge and use. Women over 18 years of age who consented to participate, and who had been receiving ART for more than a month, were eligible for participation in the study.Outcome measures: Contraceptive knowledge and use.Results: All participants had received counselling on male condom use. The majority of HIV-positive women receiving ART preferred the male condom as their contraception of choice. Knowledge of male condoms was excellent, but only 66% of the study group used condoms, and just over 50% used a dual method of contraception (male condoms plus anothercontraceptive method). While 97% of participants were knowledgeable about injectable contraception, only 40% used the latter as a form of contraception. Ninety-two per cent of the participants reported recent sexual activity, 14% had fallen pregnant while receiving ART, and 64% planned on having a child in the future.Conclusion: The low use of dual contraception was a cause for concern. Recommendations include the integration of family planning services into HIV care at all ART sites. This should promote proper fertility management for women receiving ART. Keywords: contraceptive knowledge, practice, HIV-positive women, antiretroviral therap

    Cloning of mouse integrin alphaV cDNA and role of the alphaV-related matrix receptors in metanephric development.

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    Metanephrogenesis has been a long-standing model to study cell-matrix interactions. A number of adhesion molecules, including matrix receptors (i.e., integrins), are believed to be involved in such interactions. The integrins contain alpha and beta s ubunits and are present in various tissues in different heterodimeric forms. In this study, one of the members of the integrin superfamily, alphaV, was characterized, and its relevance in murine nephrogenesis was investigated. Mouse embryonic renal cDNA libraries were prepared and screened for alphaV, and multiple clones were isolated and sequenced. The deduced amino acid sequence of the alpha-v cDNA clones and hydropathic analysis revealed that it has a typical signal sequence and extracellular, transmembrane, and cytoplasmic domains, with multiple Ca2+ binding sites. No A(U)nA mRNA instability motifs were present. Conformational analysis revealed no rigid long-range-ordered structure in murine alphaV. The alphaV was expressed in the embryonic kidney at day 13 of the gestation, with a transcript size of approximately 7 kb. Its expression increased progressively during the later gestational stages and in the neonatal period. It was distributed in the epithelial elements of developing nephrons and was absent in the uninduced mesenchyme. In mature metanephroi, the expression was relatively high in the glomeruli and blood vessels, as compared to the tubules. Various heterodimeric associations of alphaV, i.e., with beta1, beta3, beta5, and beta6, were observed in metanephric tissues. Inclusion of alphaV-antisense-oligodeoxynucleotide or -antibody in metanephric culture induced dysmorphogenesis of the kidney with reduced population of the nephrons, disorganization of the ureteric bud branches, and reduction of mRNA and protein expressions of alphaV. The expressions of integrin beta3, beta5, and beta6 were unaltered. These findings suggest that the integrin alphaV is developmentally regulated, has a distinct spatio-temporal expression, and is relevant in the mammalian organogenesis

    Design and Fabrication of Electrolyte-Supported Tubular SOFC Combined with Supercritical Water Oxidation on Biomass Gas

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    Solid oxide fuel cells (SOFCs) are relatively simple and environmental friendly devices for the production of electricity from hydrocarbons. The use of a high pressure supercritical water (SCW) reactor containing a SOFC has the potential for using a multitude of logistical liquid fuels that would otherwise not be possible in a regular SOFC system. A SOFC-SCW system was designed to allow the anode to be exposed to the pressure and chemical milieu of the supercritical water oxidation reactor. The effects of the amount of water/fuel and oxygen fed into the reactor under SCW conditions at 400 degrees C were studied. The effects on electrochemical performance as well as preliminary results on a number of feed stocks, for example pectin, are also described.open1111Nsciescopu

    Robust Multi-Image HDR Reconstruction for the Modulo Camera

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    Photographing scenes with high dynamic range (HDR) poses great challenges to consumer cameras with their limited sensor bit depth. To address this, Zhao et al. recently proposed a novel sensor concept - the modulo camera - which captures the least significant bits of the recorded scene instead of going into saturation. Similar to conventional pipelines, HDR images can be reconstructed from multiple exposures, but significantly fewer images are needed than with a typical saturating sensor. While the concept is appealing, we show that the original reconstruction approach assumes noise-free measurements and quickly breaks down otherwise. To address this, we propose a novel reconstruction algorithm that is robust to image noise and produces significantly fewer artifacts. We theoretically analyze correctness as well as limitations, and show that our approach significantly outperforms the baseline on real data.Comment: to appear at the 39th German Conference on Pattern Recognition (GCPR) 201

    unreinforced masonry buildings

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    A recent earthquake of M=4.9 occurred on 29 October 2007 in C, ameli, Denizli, which is located in a seismically active region at southwest Anatolia, Turkey. It has caused extensive damages at unreinforced masonry buildings like many other cases observed in Turkey during other previous earthquakes. Most of the damaged structures were non-engineered, seismically deficient, unreinforced masonry buildings. This paper presents a site survey of these damaged buildings. In addition to typical masonry damages, some infrequent, event-specific damages were also observed. Reasons for the relatively wide spread damages considering the magnitude of the event are discussed in the paper

    On the Hierarchy of Block Deterministic Languages

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    A regular language is kk-lookahead deterministic (resp. kk-block deterministic) if it is specified by a kk-lookahead deterministic (resp. kk-block deterministic) regular expression. These two subclasses of regular languages have been respectively introduced by Han and Wood (kk-lookahead determinism) and by Giammarresi et al. (kk-block determinism) as a possible extension of one-unambiguous languages defined and characterized by Br\"uggemann-Klein and Wood. In this paper, we study the hierarchy and the inclusion links of these families. We first show that each kk-block deterministic language is the alphabetic image of some one-unambiguous language. Moreover, we show that the conversion from a minimal DFA of a kk-block deterministic regular language to a kk-block deterministic automaton not only requires state elimination, and that the proof given by Han and Wood of a proper hierarchy in kk-block deterministic languages based on this result is erroneous. Despite these results, we show by giving a parameterized family that there is a proper hierarchy in kk-block deterministic regular languages. We also prove that there is a proper hierarchy in kk-lookahead deterministic regular languages by studying particular properties of unary regular expressions. Finally, using our valid results, we confirm that the family of kk-block deterministic regular languages is strictly included into the one of kk-lookahead deterministic regular languages by showing that any kk-block deterministic unary language is one-unambiguous

    Stability of Spatial Optical Solitons

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    We present a brief overview of the basic concepts of the soliton stability theory and discuss some characteristic examples of the instability-induced soliton dynamics, in application to spatial optical solitons described by the NLS-type nonlinear models and their generalizations. In particular, we demonstrate that the soliton internal modes are responsible for the appearance of the soliton instability, and outline an analytical approach based on a multi-scale asymptotic technique that allows to analyze the soliton dynamics near the marginal stability point. We also discuss some results of the rigorous linear stability analysis of fundamental solitary waves and nonlinear impurity modes. Finally, we demonstrate that multi-hump vector solitary waves may become stable in some nonlinear models, and discuss the examples of stable (1+1)-dimensional composite solitons and (2+1)-dimensional dipole-mode solitons in a model of two incoherently interacting optical beams.Comment: 34 pages, 9 figures; to be published in: "Spatial Optical Solitons", Eds. W. Torruellas and S. Trillo (Springer, New York
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