221 research outputs found
Effect of public education aimed at early diagnosis of malignant melanoma: cohort comparison study
No abstract available
Observational study of type of surgical training and outcome of definitive surgery for primary malignant melanoma
No abstract available
The Jang equation reduction of the spacetime positive energy theorem in dimensions less than eight
We extend the Jang equation proof of the positive energy theorem due to R.
Schoen and S.-T. Yau from dimension to dimensions . This
requires us to address several technical difficulties that are not present when
. The regularity and decay assumptions for the initial data sets to which
our argument applies are weaker than those of R. Schoen and S.-T. Yau. In
recent joint work with L.-H. Huang, D. Lee, and R. Schoen we have given a
different proof of the full positive mass theorem in dimensions .
We pointed out that this theorem can alternatively be derived from our density
argument and the positive energy theorem of the present paper.Comment: All comments welcome! Final version to appear in Comm. Math. Phy
Damped finite-time-singularity driven by noise
We consider the combined influence of linear damping and noise on a dynamical
finite-time-singularity model for a single degree of freedom. We find that the
noise effectively resolves the finite-time-singularity and replaces it by a
first-passage-time or absorbing state distribution with a peak at the
singularity and a long time tail. The damping introduces a characteristic
cross-over time. In the early time regime the probability distribution and
first-passage-time distribution show a power law behavior with scaling exponent
depending on the ratio of the non linear coupling strength to the noise
strength. In the late time regime the behavior is controlled by the damping.
The study might be of relevance in the context of hydrodynamics on a nanometer
scale, in material physics, and in biophysics.Comment: 9 pages, 4 eps-figures, revtex4 fil
Power laws and stretched exponentials in a noisy finite-time-singularity model
We discuss the influence of white noise on a generic dynamical
finite-time-singularity model for a single degree of freedom. We find that the
noise effectively resolves the finite-time-singularity and replaces it by a
first-passage-time or absorbing state distribution with a peak at the
singularity and a long time tail exhibiting power law or stretched exponential
behavior. The study might be of relevance in the context of hydrodynamics on a
nanometer scale, in material physics, and in biophysics.Comment: 10 pages revtex file, including 4 postscript-figures. References
added and a few typos correcte
Dynamical Horizons and their Properties
A detailed description of how black holes grow in full, non-linear general
relativity is presented. The starting point is the notion of dynamical
horizons. Expressions of fluxes of energy and angular momentum carried by
gravitational waves across these horizons are obtained. Fluxes are local and
the energy flux is positive. Change in the horizon area is related to these
fluxes. A notion of angular momentum and energy is associated with
cross-sections of the horizon and balance equations, analogous to those
obtained by Bondi and Sachs at null infinity, are derived. These in turn lead
to generalizations of the first and second laws of black hole mechanics. The
relation between dynamical horizons and their asymptotic states --the isolated
horizons-- is discussed briefly. The framework has potential applications to
numerical, mathematical, astrophysical and quantum general relativity.Comment: 44 pages, 2 figures, RevTeX4. Minor typos corrected. Final PRD
versio
A proof of the Geroch-Horowitz-Penrose formulation of the strong cosmic censor conjecture motivated by computability theory
In this paper we present a proof of a mathematical version of the strong
cosmic censor conjecture attributed to Geroch-Horowitz and Penrose but
formulated explicitly by Wald. The proof is based on the existence of
future-inextendible causal curves in causal pasts of events on the future
Cauchy horizon in a non-globally hyperbolic space-time. By examining explicit
non-globally hyperbolic space-times we find that in case of several physically
relevant solutions these future-inextendible curves have in fact infinite
length. This way we recognize a close relationship between asymptotically flat
or anti-de Sitter, physically relevant extendible space-times and the so-called
Malament-Hogarth space-times which play a central role in recent investigations
in the theory of "gravitational computers". This motivates us to exhibit a more
sharp, more geometric formulation of the strong cosmic censor conjecture,
namely "all physically relevant, asymptotically flat or anti-de Sitter but
non-globally hyperbolic space-times are Malament-Hogarth ones".
Our observations may indicate a natural but hidden connection between the
strong cosmic censorship scenario and the Church-Turing thesis revealing an
unexpected conceptual depth beneath both conjectures.Comment: 16pp, LaTeX, no figures. Final published versio
The Impact of the Implementation of the Dutch Combined Meeting Centres Support Programme for Family Caregivers of People with Dementia in Italy, Poland and UK
Objectives: The MEETINGDEM research project aimed to implement the combined Dutch Meeting Centre Support Programme (MCSP) for community-dwelling people with dementia and caregivers within Italy, Poland and UK and to assess whether comparable benefits were found in these countries as in the Netherlands.
Method: Nine pilot Meeting Centres (MCs) participated (Italy-5, Poland-2, UK-2). Effectiveness of MCSP was compared to usual care (UC) on caregiver outcomes measuring competence (SSCQ), mental health (GHQ-12), emotional distress (NPI-Q) and loneliness (UCLA) analysed by ANCOVAs in a 6-month pre-test/post-test controlled trial. Interviews using standardised measures were completed with caregivers.
Results: Pre/post data were collected for 93 caregivers receiving MCSP and 74 receiving UC. No statistically significant differences on the outcome measures were found overall. At a country level MC caregivers in Italy showed significant better general mental health (p=0.04, d=0.55) and less caregiver distress (p=0.02, d=0.62) at post-test than the UC group. Caregiver satisfaction was rated on a sample at 3 months (n=81) and 6 months (n=84). The majority of caregivers reported feeling less burdened and more supported by participating in MCSP.
Conclusion: The moderate positive effect on sense of competence and the greater mental health benefit for lonely caregivers using the MCSP compared to UC as found in the original Dutch studies were not replicated. However, subject to study limitations, caregivers in Italy using MCSP benefitted more regarding their mental health and emotional distress than caregivers using UC. Further evaluation of the benefits of MCSP within these countries in larger study samples is recommended
Level Set Method for the Evolution of Defect and Brane Networks
A theory for studying the dynamic scaling properties of branes and
relativistic topological defect networks is presented. The theory, based on a
relativistic version of the level set method, well-known in other contexts,
possesses self-similar ``scaling'' solutions, for which one can calculate many
quantities of interest. Here, the length and area densities of cosmic strings
and domain walls are calculated in Minkowski space, and radiation, matter, and
curvature-dominated FRW cosmologies with 2 and 3 space dimensions. The scaling
exponents agree the naive ones based on dimensional analysis, except for cosmic
strings in 3-dimensional Minkowski space, which are predicted to have a
logarithmic correction to the naive scaling form. The scaling amplitudes of the
length and area densities are a factor of approximately 2 lower than results
from numerical simulations of classical field theories. An expression for the
length density of strings in the condensed matter literature is corrected.Comment: 46pp LaTeX, revtex4(preprint), 1 eps figure, revised for publication.
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