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

Teledermatology by Videoconference : Experience of a Pilot Project

Background: There is a shortage of medical specialists within the provincial departments of health in South Africa. Telemedicine is a potential way of providing specialist services, at a distance, to rural areas. This study assesses patient and staff satisfaction and issues, technological and operational, associated with the establishment of a videoconference-based teledermatology service. Methods: An ISDN-based videoconference link was established between Port Shepstone Hospital and the Nelson R Mandela School of Medicine in Durban. Patients with a dermatological problem that would have necessitated transfer to the academic hospital for diagnosis and/or management were entered into a prospective study which evaluated the ability to make a diagnosis and prescribe a management plan by videoconference and the patients\' and doctors\' satisfaction with the consultations. Results: A total of 69 patients were seen during 12 videoconferenced consultation sessions. Seventeen patients (24.6%) were subsequently referred to the academic hospital: nine patients were sent because a definitive diagnosis could not be made; and eight patients were transferred for specialist management based on the diagnosis made. The patients\' and referring doctors\' satisfaction with the consultation was 80.3% and 82.1% respectively, while the dermatologist was satisfied 67.6% of the time. The dermatologist was dissatisfied with ten (14.7%) of the consultations and this was related to difficulties in making a definitive diagnosis. The referring doctors found 59 (85.9%) of the consultations to be of educational value. No problems were noted in diagnosing lesions in dark-skinned patients. Conclusion: Videoconferenced teledermatology between district hospitals and regional hospitals is possible and can improve services to rural areas. Further studies on widespread implementation and sustainability are warranted. South African Family Practice Vol. 50 (3) 2008: pp. 70-70

First and Second Order Perturbations of Hypersurfaces

In this paper we find the first and second order perturbations of the induced metric and the extrinsic curvature of a non-degenerate hypersurface $\Sigma$ in a spacetime $(M,g)$, when the metric $g$ is perturbed arbitrarily to second order and the hypersurface itself is allowed to change perturbatively (i.e. to move within spacetime) also to second order. The results are fully general and hold in arbitrary dimensions and signature. An application of these results for the perturbed matching theory between spacetimes is presented.Comment: 31 pages, no figures. To be published in Classical and Quantum Gravit

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 9–17) were interviewed as part of an ongoing study, the ‘Early Prediction of Adolescent Depression Study’. 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

Dynamical Collapse of Charged Scalar Field in Phantom Gravity

We investigated the problem of the dynamical collapse of a self-gravitating complex charged scalar field in Einstein-Maxwell-dilaton theory with a phantom copuling for the adequate fields in the system under consideration. We also considered two simplifications of it, i.e., the separate collapses of phantom Maxwell and phantom scalar fields under the influence of Einstein gravity. One starts with the regular spacetime and leads the evolution through the formation of the horizons and the final singularity. We discuss the structures of spacetimes emerging in the process of the dynamical collapse and comment on the role of the considered fields in its course.Comment: 15 pages, RevTex, 18 figures, to be published in Phys.Rev.D1

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

Experiment selection for the discrimination of semi-quantitative models of dynamical systems

AbstractModeling an experimental system often results in a number of alternative models that are all justified by the available experimental data. To discriminate among these models, additional experiments are needed. Existing methods for the selection of discriminatory experiments in statistics and in artificial intelligence are often based on an entropy criterion, the so-called information increment. A limitation of these methods is that they are not well-adapted to discriminating models of dynamical systems under conditions of limited measurability. Moreover, there are no generic procedures for computing the information increment of an experiment when the models are qualitative or semi-quantitative. This has motivated the development of a method for the selection of experiments to discriminate among semi-quantitative models of dynamical systems. The method has been implemented on top of existing implementations of the qualitative and semi-quantitative simulation techniques QSIM, Q2, and Q3. The applicability of the method to real-world problems is illustrated by means of an example in population biology: the discrimination of four competing models of the growth of phytoplankton in a bioreactor. The models have traditionally been considered equivalent for all practical purposes. Using our model discrimination approach and experimental data we show, however, that two of them are superior for describing phytoplankton growth under a wide range of experimental conditions

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 $t$ 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