241 research outputs found
Dilaton Black Holes Near the Horizon
Generic 4-d black holes with unbroken supersymmetry are shown
to tend to a Robinson-Bertotti type geometry with a linear dilaton and doubling
of unbroken supersymmetries near the horizon. Purely magnetic dilatonic black
holes, which have unbroken supersymmetry, behave near the horizon as a
2-d linear dilaton vacuum . This geometry is invariant under 8
supersymmetries, i.e. half of the original supersymmetries are unbroken.
The supersymmetric positivity bound, which requires the mass of the 4-d dilaton
black holes to be greater than or equal to the central charge, corresponds to
positivity of mass for a class of stringy 2-d black holes.Comment: 10 pages, SU-ITP-92-2
Copyright and cultural work: an exploration
This article first discusses the contemporary debate on cultural âcreativityâ and the economy. Second, it considers the current state of UK copyright law and how it relates to cultural work. Third, based on empirical research on British dancers and musicians, an analysis of precarious cultural work is presented. A major focus is how those who follow their art by way of âportfolioâ work handle their rights in ways that diverge significantly from the current simplistic assumptions of law and cultural policy. Our conclusions underline the distance between present top-down conceptions of what drives production in the cultural field and the actual practice of dancers and musicians
Inter-rater reliability of the EPUAP pressure ulcer classification system using photographs
Background. Many classification systems for grading pressure ulcers are discussed in the literature. Correct identification and classification of a pressure ulcer is important for accurate reporting of the magnitude of the problem, and for timely prevention. The reliability of pressure ulcer classification systems has rarely been tested. Aims and objectives. The purpose of this paper is to examine the inter-rater reliability of classifying pressure ulcers according to the European Pressure Ulcer Advisory Panel classification system when using pressure ulcer photographs.Design. Survey was among pressure ulcer experts.Methods. Fifty-six photographs were presented to 44 pressure ulcer experts. The experts classified the lesions as normal skin, blanchable erythema, pressure ulcer (four grades) or incontinence lesion. Inter-rater reliability was calculated.Results. The multirater-Kappa for the entire group of experts was 0.80 (P < 0.001).Various groups of experts obtained comparable results. Differences in classifications are mainly limited to 1 degree of difference. Incontinence lesions are most often confused with grade 2 (blisters) and grade 3 pressure ulcers (superficial pressure ulcers).Conclusions. The inter-rater reliability of the European Pressure Ulcer Advisory Panel classification appears to be good for the assessment of photographs by experts. The difference between an incontinence lesion and a blister or a superficial pressure ulcer does not always seem clear.Relevance to clinical practice. The ability to determine correctly whether a lesion is a pressure ulcer lesion is important to assess the effectiveness of preventive measures. In addition, the ability to make a correct distinction between pressure ulcers and incontinence lesions is important as they require different preventive measures. A faulty classification leads to mistaken measures and negative results. Photographs can be used as a practice instrument to learn to discern pressure ulcers from incontinence lesions and to get to know the different grades of pressure ulcers. The Pressure Ulcer Classification software package has been developed to facilitate learning
'Tilting' the Universe with the Landscape Multiverse: The 'Dark' Flow
The theory for the selection of the initial state of the universe from the
landscape multiverse predicts superhorizon inhomogeneities induced by nonlocal
entanglement of our Hubble volume with modes and domains beyond the horizon.
Here we show these naturally give rise to a bulk flow with correlation length
of order horizon size. The modification to the gravitational potential has a
characteristic scale , and it originates from the
preinflationary remnants of the landscape. The 'tilt' in the potential induces
power to the lowest CMB multipoles, with the dominant contribution being the
dipole and next, the quadrupole. The induced multipoles are aligned
with an axis normal to their alignment plane being oriented along the preferred
frame determined by the dipole. The preferred direction is displayed by the
velocity field of the bulk flow relative to the expansion frame of the
universe. The parameters are tightly constrained thus the derived modifications
lead to robust predictions for testing our theory. The 'dark' flow was recently
discovered by Kashlinsky et al. to be about which seems in good
agreement with our predictions for the induced dipole of order .
Placed in this context, the discovery of the bulk flow by Kashlinsky et al.
becomes even more interesting as it may provide a probe of the preinflationary
physics and a window onto the landscape multiverse.Comment: 7 pgs, 2 fig
Late-time Entropy Production from Scalar Decay and Relic Neutrino Temperature
Entropy production from scalar decay in the era of low temperatures after
neutrino decoupling will change the ratio of the relic neutrino temperature to
the CMB temperature, and, hence, the value of N_eff, the effective number of
neutrino species. Such scalar decay is relevant to reheating after thermal
inflation, proposed to dilute massive particles, like the moduli and the
gravitino, featuring in supersymmetric and string theories. The effect of such
entropy production on the relic neutrino temperature ratio is calculated in a
semi-analytic manner, and a recent lower bound on this ratio, obtained from the
WMAP satellite and 2dF galaxy data, is used to set a lower bound of ~ 1.5 x
10^-23 Gev on the scalar decay constant, corresponding to a reheating
temperature of about 3.3 Mev.Comment: 13 pages, to appear in PR
The Three Families from SM-like Chiral Models
We give a detailed description of the model construction procedures about our
new approach to the family structure of the standard model. SM-like chiral
fermion spectra, largely "derivable" from the gauge anomaly constraints, are
formulated in a symmetry
framework as an extension of the SM symmetry. The case gives naturally
three families as a result, with nontrivially embedded into the
. Such a spectrum has extra vector-like quarks and
leptons. We illustrate how an acceptable symmetry breaking pattern can be
obtained through a relatively simple scalar sector which gives naturally
hierarchical quark mass matrices. Compatibility with various FCNC constraints
and some interesting aspects of the possible phenomenological features are
discussed, from a non-model specific perspective. The question of incorporating
supersymmetry without putting in the Higgses as extra supermultiplet is also
addressed.Comment: 43 pages RevTex, including 9 tables and 3 figure
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