6,736 research outputs found
Women’s empowerment and violent death among women and men in Europe: An ecological study
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
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
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
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 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 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-Wallach solution together with a compactifying pp-wave. The
SU(2) theory admits a black string, whose near horizon limit is . We also obtain the Yang-Mills analogue of the Salam-Sezgin solution of
the U(1) theory, namely , where the 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
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British research in accounting and finance (2001–2007): the 2008 research assessment exercise
No abstract available
Quantum coherence and carriers mobility in organic semiconductors
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
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
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 C-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-: identification of the individual galaxies responsible for the 80-290m cosmic infrared background
We propose a new method of pushing to its faintest detection
limits using universal trends in the redshift evolution of the far infrared
over 24m 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
sources to the cosmic infrared background (CIRB) by a factor 5 close to its
peak at 250m and more than 3 in the 350m and 500m bands. We
produce realistic mock images of the deep PACS and SPIRE images of
the GOODS-North field from the GOODS- 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 24m prior positions.
The clean index (CI), previously defined but validated here with simulations,
which measures the presence of bright 24m neighbours and the photometric
accuracy index (PAI) directly extracted from the mock images. After
correction for completeness, thanks to our mock 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 100m and 2.2 mJy at 160m and 55, 33, and 13% of
the CIRB in the SPIRE bands down to 2.5, 5, and 9 mJy at 250m, 350m,
and 500m, respectively. The latter depths improve the detection limits of
by factors of 5 at 250m, and 3 at 350m and 500m as
compared to the standard confusion limit. Interestingly, the dominant
contributors to the CIRB in all bands appear to be distant siblings
of the Milky Way (0.96 for 300m) with a stellar mass
of 910M.Comment: 22 pages, 16 figures. Accepted for publication by Astronomy and
Astrophysic
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