6,736 research outputs found

    Women’s empowerment and violent death among women and men in Europe: An ecological study

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    Background This study examined the association between mortality due to injury and poisoning among men and women in Europe and nine indicators of women's empowerment (i.e. women's challenging of existing power structures that subordinate women). Methods A cross-sectional ecological design was used, with 24 countries from the European Union plus two countries within the European Economic Area and Switzerland. Results Most of the nine indicators of women's empowerment were unrelated to men's, as well as women's, death rates from injury and poisoning. However, multiple linear regression models showed that a few indicators of women's empowerment were significantly associated with mortality due to injury and poisoning for both women and men. When three Baltic States with considerably higher mortality rates (Latvia, Lithuania and Estonia) were excluded from the analysis, however, only one indicator (female economic activity as a percentage of male economic activity) remained a significant predictor of men's death rates. Conclusion These data suggest that some indicators of women's empowerment may be associated with mortality due to injury and poisoning for men, although the association was dependent on which countries were included in the analysis. This highlights the importance of examining in greater detail the influence of changing gender roles on the health behaviours of women and men

    Universal Model of Finite-Reynolds Number Turbulent Flow in Channels and Pipes

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    In this Letter we suggest a simple and physically transparent analytical model of the pressure driven turbulent wall-bounded flows at high but finite Reynolds numbers Re. The model gives accurate qualitative description of the profiles of the mean-velocity and Reynolds-stresses (second order correlations of velocity fluctuations) throughout the entire channel or pipe in the wide range of Re, using only three Re-independent parameters. The model sheds light on the long-standing controversy between supporters of the century-old log-law theory of von-K\`arm\`an and Prandtl and proposers of a newer theory promoting power laws to describe the intermediate region of the mean velocity profile.Comment: 4 pages, 6 figs, re-submitted PRL according to referees comment

    Analytical Model of the Time Developing Turbulent Boundary Layer

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    We present an analytical model for the time-developing turbulent boundary layer (TD-TBL) over a flat plate. The model provides explicit formulae for the temporal behavior of the wall-shear stress and both the temporal and spatial distributions of the mean streamwise velocity, the turbulence kinetic energy and Reynolds shear stress. The resulting profiles are in good agreement with the DNS results of spatially-developing turbulent boundary layers at momentum thickness Reynolds number equal to 1430 and 2900. Our analytical model is, to the best of our knowledge, the first of its kind for TD-TBL.Comment: 5pages, 9 figs, JETP Letters, submitte

    The general form of supersymmetric solutions of N=(1,0) U(1) and SU(2) gauged supergravities in six dimensions

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    We obtain necessary and sufficient conditions for a supersymmetric field configuration in the N=(1,0) U(1) or SU(2) gauged supergravities in six dimensions, and impose the field equations on this general ansatz. It is found that any supersymmetric solution is associated to an SU(2)⋉R4SU(2)\ltimes \mathbb{R}^4 structure. The structure is characterized by a null Killing vector which induces a natural 2+4 split of the six dimensional spacetime. A suitable combination of the field equations implies that the scalar curvature of the four dimensional Riemannian part, referred to as the base, obeys a second order differential equation. Bosonic fluxes introduce torsion terms that deform the SU(2)⋉R4SU(2)\ltimes\mathbb{R}^4 structure away from a covariantly constant one. The most general structure can be classified in terms of its intrinsic torsion. For a large class of solutions the gauge field strengths admit a simple geometrical interpretation: in the U(1) theory the base is K\"{a}hler, and the gauge field strength is the Ricci form; in the SU(2) theory, the gauge field strengths are identified with the curvatures of the left hand spin bundle of the base. We employ our general ansatz to construct new supersymmetric solutions; we show that the U(1) theory admits a symmetric Cahen-Wallach4×S2_4\times S^2 solution together with a compactifying pp-wave. The SU(2) theory admits a black string, whose near horizon limit is AdS3×S3AdS_3\times S_3. We also obtain the Yang-Mills analogue of the Salam-Sezgin solution of the U(1) theory, namely R1,2×S3R^{1,2}\times S^3, where the S3S^3 is supported by a sphaleron. Finally we obtain the additional constraints implied by enhanced supersymmetry, and discuss Penrose limits in the theories.Comment: 1+29 pages, late

    Quantum coherence and carriers mobility in organic semiconductors

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    We present a model of charge transport in organic molecular semiconductors based on the effects of lattice fluctuations on the quantum coherence of the electronic state of the charge carrier. Thermal intermolecular phonons and librations tend to localize pure coherent states and to assist the motion of less coherent ones. Decoherence is thus the primary mechanism by which conduction occurs. It is driven by the coupling of the carrier to the molecular lattice through polarization and transfer integral fluctuations as described by the hamiltonian of Gosar and Choi. Localization effects in the quantum coherent regime are modeled via the Anderson hamiltonian with correlated diagonal and non-diagonal disorder leading to the determination of the carrier localization length. This length defines the coherent extension of the ground state and determines, in turn, the diffusion range in the incoherent regime and thus the mobility. The transfer integral disorder of Troisi and Orlandi can also be incorporated. This model, based on the idea of decoherence, allowed us to predict the value and temperature dependence of the carrier mobility in prototypical organic semiconductors that are in qualitative accord with experiments

    Bitwise Bell inequality violations for an entangled state involving 2N ions

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    Following on from previous work [J. A. Larsson, Phys. Rev. A 67, 022108 (2003)], Bell inequalities based on correlations between binary digits are considered for a particular entangled state involving 2N trapped ions. These inequalities involve applying displacement operations to half of the ions and then measuring correlations between pairs of corresponding bits in the binary representations of the number of centre-of-mass phonons of N particular ions. It is shown that the state violates the inequalities and thus displays nonclassical correlations. It is also demonstrated that it violates a Bell inequality when the displacements are replaced by squeezing operations.Comment: 12 pages, 5 figures, accepted for publication in Phys. Rev.

    Morphology Effectively Controls Singlet-Triplet Exciton Relaxation and Charge Transport in Organic Semiconductors

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    We present a comparative study of ultrafast photo-conversion dynamics in tetracene (Tc) and pentacene (Pc) single crystals and Pc films using optical pump-probe spectroscopy. Photo-induced absorption in Tc and Pc crystals is activated and temperature-independent respectively, demonstrating dominant singlet-triplet exciton fission. In Pc films (as well as C60_{60}-doped films) this decay channel is suppressed by electron trapping. These results demonstrate the central role of crystallinity and purity in photogeneration processes and will constrain the design of future photovoltaic devices.Comment:

    GOODS-HerschelHerschel: identification of the individual galaxies responsible for the 80-290μ\mum cosmic infrared background

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    We propose a new method of pushing HerschelHerschel to its faintest detection limits using universal trends in the redshift evolution of the far infrared over 24μ\mum colours in the well-sampled GOODS-North field. An extension to other fields with less multi-wavelength information is presented. This method is applied here to raise the contribution of individually detected HerschelHerschel sources to the cosmic infrared background (CIRB) by a factor 5 close to its peak at 250μ\mum and more than 3 in the 350μ\mum and 500μ\mum bands. We produce realistic mock HerschelHerschel images of the deep PACS and SPIRE images of the GOODS-North field from the GOODS-HerschelHerschel Key Program and use them to quantify the confusion noise at the position of individual sources, i.e., estimate a "local confusion noise". Two methods are used to identify sources with reliable photometric accuracy extracted using 24μ\mum prior positions. The clean index (CI), previously defined but validated here with simulations, which measures the presence of bright 24μ\mum neighbours and the photometric accuracy index (PAI) directly extracted from the mock HerschelHerschel images. After correction for completeness, thanks to our mock HerschelHerschel images, individually detected sources make up as much as 54% and 60% of the CIRB in the PACS bands down to 1.1 mJy at 100μ\mum and 2.2 mJy at 160μ\mum and 55, 33, and 13% of the CIRB in the SPIRE bands down to 2.5, 5, and 9 mJy at 250μ\mum, 350μ\mum, and 500μ\mum, respectively. The latter depths improve the detection limits of HerschelHerschel by factors of 5 at 250μ\mum, and 3 at 350μ\mum and 500μ\mum as compared to the standard confusion limit. Interestingly, the dominant contributors to the CIRB in all HerschelHerschel bands appear to be distant siblings of the Milky Way (zz∼\sim0.96 for λ\lambda<<300μ\mum) with a stellar mass of M⋆M_{\star}∼\sim9×\times1010^{10}M⊙_{\odot}.Comment: 22 pages, 16 figures. Accepted for publication by Astronomy and Astrophysic
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