1,733 research outputs found

    Thermodynamic analysis of topological black holes in Gauss-Bonnet gravity with nonlinear source

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    Employing two classes of nonlinear electrodynamics, we obtain topological black hole solutions of Gauss-Bonnet gravity. We investigate geometric properties of the solutions and find that there is an intrinsic singularity at the origin. We investigate the thermodynamic properties of the asymptotically flat black holes and also asymptotically adS solutions. Using suitable local transformation, we generalize static horizon-flat solutions to rotating ones. We discuss their conserved and thermodynamic quantities as well as the first law of thermodynamics. Finally, we calculate the heat capacity of the solutions to obtain a constraint on the horizon radius of stable solutions.Comment: accepted in Eur. Phys. J. C (DOI: 10.1140/epjc/s10052-014-3079-9

    One-loop quantum corrections to cosmological scalar field potentials

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    We study the loop corrections to potentials of complex or coupled real scalar fields used in cosmology to account for dark energy, dark matter or dark fluid. We show that the SUGRA quintessence and dark matter scalar field potentials are stable against the quantum fluctuations, and we propose solutions to the instability of the potentials of coupled quintessence and dark fluid scalar fields. We also find that a coupling to fermions is very restricted, unless this coupling has a structure which already exists in the scalar field potential or which can be compensated by higher order corrections. Finally, we study the influence of the curvature and kinetic term corrections.Comment: 11 pages, 1 figure, accepted for publication in Phys. Rev.

    HARNESSING DAYLIGHTING AND SOLAR GAINS AS SUSTAINABLE ARCHITECTURAL DESIGNMETHODSIN MIXED-USE DEVELOPMENTS IN LAGOS, NIGERIA.

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    Thebuilt environment contributes around 40% of the world’s total carbon footprint,resulting in high building energy costs and pollution, as well as detrimental effects on the environment through the use of engines. Energy consumption can be very high in buildings, especially in mixed-us facilities. This paper seeks to analyse and contribute to the existing knowledge on daylighting and solar gain measures, resulting to a sustainable method of achieving energy efficiency in buildings. The methodology adopted for this study involves the use of case studies of two nationalandone international buildings of mixed-use typology which were appraised by evaluatingand criticizing. Criticalanalyses of physical and daylighting measures of existing developments were evaluated, pointing out merits and demerits of existing strategies as adopted in the cases.Findings from this study evince thattheneed for office and residentialspaces despite the unavailability of land in Lagosresulted in the concept of mixed-use developments. Also, some daylighting and solar gainsstrategies have been adopted but not fully maximized in Nigeria, especially the use of light shelves to enhance day lighting. Thispaper recommends that the techniques to be used to enhancedaylightingand solar gains, materials and designs;theplacements and orientations,should be determinedright from conceptualization,through to the architecture process (design and construction)

    Nanoparticles-cell association predicted by protein corona fingerprints

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    In a physiological environment (e.g., blood and interstitial fluids) nanoparticles (NPs) will bind proteins shaping a "protein corona" layer. The long-lived protein layer tightly bound to the NP surface is referred to as the hard corona (HC) and encodes information that controls NP bioactivity (e.g. cellular association, cellular signaling pathways, biodistribution, and toxicity). Decrypting this complex code has become a priority to predict the NP biological outcomes. Here, we use a library of 16 lipid NPs of varying size (Ø ≈ 100-250 nm) and surface chemistry (unmodified and PEGylated) to investigate the relationships between NP physicochemical properties (nanoparticle size, aggregation state and surface charge), protein corona fingerprints (PCFs), and NP-cell association. We found out that none of the NPs' physicochemical properties alone was exclusively able to account for association with human cervical cancer cell line (HeLa). For the entire library of NPs, a total of 436 distinct serum proteins were detected. We developed a predictive-validation modeling that provides a means of assessing the relative significance of the identified corona proteins. Interestingly, a minor fraction of the HC, which consists of only 8 PCFs were identified as main promoters of NP association with HeLa cells. Remarkably, identified PCFs have several receptors with high level of expression on the plasma membrane of HeLa cells

    Nanoparticles-cell association predicted by protein corona fingerprints

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    In a physiological environment (e.g., blood and interstitial fluids) nanoparticles (NPs) will bind proteins shaping a "protein corona" layer. The long-lived protein layer tightly bound to the NP surface is referred to as the hard corona (HC) and encodes information that controls NP bioactivity (e.g. cellular association, cellular signaling pathways, biodistribution, and toxicity). Decrypting this complex code has become a priority to predict the NP biological outcomes. Here, we use a library of 16 lipid NPs of varying size (Ø ≈ 100-250 nm) and surface chemistry (unmodified and PEGylated) to investigate the relationships between NP physicochemical properties (nanoparticle size, aggregation state and surface charge), protein corona fingerprints (PCFs), and NP-cell association. We found out that none of the NPs' physicochemical properties alone was exclusively able to account for association with human cervical cancer cell line (HeLa). For the entire library of NPs, a total of 436 distinct serum proteins were detected. We developed a predictive-validation modeling that provides a means of assessing the relative significance of the identified corona proteins. Interestingly, a minor fraction of the HC, which consists of only 8 PCFs were identified as main promoters of NP association with HeLa cells. Remarkably, identified PCFs have several receptors with high level of expression on the plasma membrane of HeLa cells

    An admissible estimator for the rth power of a bounded scale parameter in a subclass of the exponential family under entropy loss function

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    We consider an admissible estimator for the rth power of a scale parameter that is lower or upper bounded in a subclass of the scale-parameter exponential family under the entropy loss function. An admissible estimator for a bounded parameter in the family of transformed chi-square distributions is also given.Розглянуто допустиму оцiнку для r-го степеня параметра масштабу, обмеженого зверху або знизу у пiдкласi експоненцiальної сiм’ї параметрiв масштабу з ентропiйною функцiєю втрат. Наведено також допустиму оцiнку обмеженого параметра у сiм’ї трансформованих розподiлiв хi-квадрат

    Network inference using asynchronously updated kinetic Ising Model

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    Network structures are reconstructed from dynamical data by respectively naive mean field (nMF) and Thouless-Anderson-Palmer (TAP) approximations. For TAP approximation, we use two methods to reconstruct the network: a) iteration method; b) casting the inference formula to a set of cubic equations and solving it directly. We investigate inference of the asymmetric Sherrington- Kirkpatrick (S-K) model using asynchronous update. The solutions of the sets cubic equation depend of temperature T in the S-K model, and a critical temperature Tc is found around 2.1. For T < Tc, the solutions of the cubic equation sets are composed of 1 real root and two conjugate complex roots while for T > Tc there are three real roots. The iteration method is convergent only if the cubic equations have three real solutions. The two methods give same results when the iteration method is convergent. Compared to nMF, TAP is somewhat better at low temperatures, but approaches the same performance as temperature increase. Both methods behave better for longer data length, but for improvement arises, TAP is well pronounced.Comment: 6 pages, 4 figure

    Group velocity control in the ultraviolet domain via interacting dark-state resonances

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    The propagation of a weak probe field in a laser-driven four-level atomic system is investigated. We choose mercury as our model system, where the probe transition is in the ultraviolet region. A high-resolution peak appears in the optical spectra due to the presence of interacting dark resonances. We show that this narrow peak leads to superluminal light propagation with strong absorption, and thus by itself is only of limited interest. But if in addition a weak incoherent pump field is applied to the probe transition, then the peak structure can be changed such that both sub- and superluminal light propagation or a negative group velocity can be achieved without absorption, controlled by the incoherent pumping strength

    An admissible estimator for the rth power of a bounded scale parameter in a subclass of the exponential family under entropy loss function

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    We consider an admissible estimator for the rth power of a scale parameter that is lower or upper bounded in a subclass of the scale-parameter exponential family under the entropy loss function. An admissible estimator for a bounded parameter in the family of transformed chi-square distributions is also given.Розглянуто допустиму оцiнку для r-го степеня параметра масштабу, обмеженого зверху або знизу у пiдкласi експоненцiальної сiм’ї параметрiв масштабу з ентропiйною функцiєю втрат. Наведено також допустиму оцiнку обмеженого параметра у сiм’ї трансформованих розподiлiв хi-квадрат

    Performance evaluation of damper control settings for operation of multiple-zone variable air volume reheat system in different building applications and climate types

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    Choosing the right control strategies is an important task for effective operation of variable air volume reheat (VAVR) system in commercial buildings. In this design, dampers’ position inside air terminal units (ATUs) are modulated to adjust the amount of air supply volume based on thermal zones’ cooling or heating demand. A minimum air flow fraction (MAFF) is set for damper settings of ATUs to avoid under-ventilation problem in thermal zones. This study investigated the impact of MAFF value on various performance aspects of multiple-zone VAVR design in different building applications and climate types. A five-storey commercial building for three applications of school, office and retail in four climate types of tropical monsoon, hot desert, Mediterranean and humid continental have been simulated in EnergyPlus building simulation software. The results of simulations have shown that lowering MAFF value in ATUs would reduce the required reheat coil energy to maintain precise air supply temperature at part load cooling scenarios. Nonetheless, this reduction could have some implications on thermal comfort and indoor air quality level of thermal zones in a multiple-zone arrangement. It was concluded that in general it is an energy efficient control strategy to keep MAFF value to as low as 0.1 for high ventilation rate spaces like classrooms in school buildings (except for hot desert climate). On the other hand, it is advisable to not reduce MAFF value below 0.3 for low ventilation rate spaces like office areas to avoid any air quality issues in thermal zones
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