956 research outputs found
Corrigendum to `Orbit closures in the enhanced nilpotent cone', published in Adv. Math. 219 (2008)
In this note, we point out an error in the proof of Theorem 4.7 of [P. Achar
and A.~Henderson, `Orbit closures in the enhanced nilpotent cone', Adv. Math.
219 (2008), 27-62], a statement about the existence of affine pavings for
fibres of a certain resolution of singularities of an enhanced nilpotent orbit
closure. We also give independent proofs of later results that depend on that
statement, so all other results of that paper remain valid.Comment: 4 pages. The original paper, in a version almost the same as the
published version, is arXiv:0712.107
Offspring of parents with recurrent depression: which features of parent depression index risk for offspring psychopathology?
Background: Parental depression is associated with an increased risk of psychiatric disorder in offspring, although outcomes vary. At present relatively little is known about how differences in episode timing, severity, and course of recurrentdepression relate to risk in children. The aim of this study was to consider the offspring of parents with recurrentdepression and examine whether a recent episode of parental depressionindexesrisk for offspringpsychopathology over and above these other parental depressionfeatures.
<p/>Methods: Three hundred and thirty seven recurrently depressed parents and their offspring (aged 9â17) were interviewed as part of an ongoing study, the âEarly Prediction of Adolescent Depression Studyâ. The Child and Adolescent Psychiatric Assessment was used to assess two child outcomes; presence of a DSM-IV psychiatric disorder and number of DSM-IV child-rated depression symptoms.
<p/>Results: Children whose parents had experienced a recent episode of depression reported significantly more depression symptoms, and odds of child psychiatric disorder were doubled relative to children whose parents had not experienced a recent episode of depression. Past severity of parental depression was also significantly associated with child depression symptoms.
<p/>Limitations: Statistical analyses preclude causal conclusions pertaining to parental depression influences on offspringpsychopathology; several features of parental depression were recalled retrospectively.
<p/>Conclusions: This study suggests that particular features of parental depression, specifically past depression severity and presence of a recent episode, may be important indicators of risk for child psychiatric disorder and depressive symptoms
Identifying Clinical applications of Spectroscopic x-ray imaging
Spectroscopic x-ray detectors, such as Medipix, are opening the door to the widespread use of energy
selective biomedical x-ray imaging. With dual energy computed tomography quickly becoming the clinical standard,
spectroscopic imaging is a likely next step. However to confirm the utility of spectroscopic x-ray detectors there needs
to be a clearer indication of the clinical benefits of the technology
Classification of Static Charged Black Holes in Higher Dimensions
The uniqueness theorem for static charged higher dimensional black hole
containing an asymptotically flat spacelike hypersurface with compact interior
and with both degenerate and non-degenerate components of event horizon is
proposed. By studies of the near-horizon geometry of degenerate horizons one
was able to eliminate the previous restriction concerning the inequality
fulfilled by the charges of the adequate components of the aforementioned
horizons.Comment: 9 pages, RevTex, to be published in Phys.Rev. D1
Inhomogeneous imperfect fluid spherical models without Big-Bang singularity
So far all known singularity-free cosmological models are cylindrically
symmetric. Here we present a new family of spherically symmetric non-singular
models filled with imperfect fluid and radial heat flow, and satisfying the
weak and strong energy conditions. For large anisotropy in pressure and
heat flux tend to vanish leading to a perfect fluid. There is a free function
of time in the model, which can be suitably chosen for non-singular behaviour
and there exist multiplicity of such choices.Comment: 8 pages, LaTeX versio
On the Papapetrou field in vacuum
In this paper we study the electromagnetic fields generated by a Killing
vector field in vacuum space-times (Papapetrou fields). The motivation of this
work is to provide new tools for the resolution of Maxwell's equations as well
as for the search, characterization, and study of exact solutions of Einstein's
equations. The first part of this paper is devoted to an algebraic study in
which we give an explicit and covariant procedure to construct the principal
null directions of a Papapetrou field. In the second part, we focus on the main
differential properties of the principal directions, studying when they are
geodesic, and in that case we compute their associated optical scalars. With
this information we get the conditions that a principal direction of the
Papapetrou field must satisfy in order to be aligned with a multiple principal
direction of the Weyl tensor in the case of algebraically special vacuum
space-times. Finally, we illustrate this study using the Kerr, Kasner and pp
waves space-times.Comment: 24 pages, LaTeX2e, IOP style. To appear in Classical and Quantum
Gravit
On global models for isolated rotating axisymmetric charged bodies; uniqueness of the exterior field
A relatively recent study by Mars and Senovilla provided us with a uniqueness
result for the exterior vacuum gravitational field generated by an isolated
distribution of matter in axial rotation in equilibrium in General Relativity.
The generalisation to exterior electrovacuum gravitational fields, to include
charged rotating objects, is presented here.Comment: LaTeX, 21 pages, uses iopart styl
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