1,127 research outputs found
Gauged Dimension Bubbles
Some of the peculiar electrodynamical effects associated with gauged
``dimension bubbles'' are presented. Such bubbles, which effectively enclose a
region of 5d spacetime, can arise from a 5d theory with a compact extra
dimension. Bubbles with thin domain walls can be stabilized against total
collapse by the entrapment of light charged scalar bosons inside the bubble,
extending the idea of a neutral dimension bubble to accommodate the case of a
gauged U(1) symmetry. Using a dielectric approach to the 4d dilaton-Maxwell
theory, it is seen that the bubble wall is almost totally opaque to photons,
leading to a new stabilization mechanism due to trapped photons. Photon
dominated bubbles very slowly shrink, resulting in a temperature increase
inside the bubble. At some critical temperature, however, these bubbles
explode, with a release of radiation.Comment: 14 pages, no figures; to appear in Phys.Rev.
RESPOND – A patient-centred programme to prevent secondary falls in older people presenting to the emergency department with a fall: Protocol for a mixed methods programme evaluation.
Background Programme evaluations conducted alongside randomised controlled trials (RCTs) have potential to enhance understanding of trial outcomes. This paper describes a multi-level programme evaluation to be conducted alongside an RCT of a falls prevention programme (RESPOND). Objectives 1) To conduct a process evaluation in order to identify the degree of implementation fidelity and associated barriers and facilitators. 2) To evaluate the primary intended impact of the programme: participation in fall prevention strategies, and the factors influencing participation. 3) To identify the factors influencing RESPOND RCT outcomes: falls, fall injuries and ED re-presentations. Methods/ Design Five hundred and twenty eight community-dwelling adults aged 60–90 years presenting to two EDs with a fall will be recruited and randomly assigned to the intervention or standard care group. All RESPOND participants and RESPOND clinicians will be included in the evaluation. A mixed methods design will be used and a programme logic model will frame the evaluation. Data will be sourced from interviews, focus groups, questionnaires, clinician case notes, recruitment records, participant-completed calendars, hospital administrative datasets, and audio-recordings of intervention contacts. Quantitative data will be analysed via descriptive and inferential statistics and qualitative data will be interpreted using thematic analysis. Discussion The RESPOND programme evaluation will provide information about contextual and influencing factors related to the RCT outcomes. The results will assist researchers, clinicians, and policy makers to make decisions about future falls prevention interventions. Insights gained are likely to be transferable to preventive health programmes for a range of chronic conditions
Stability of Neutral Fermi Balls with Multi-Flavor Fermions
A Fermi ball is a kind of non-topological soliton, which is thought to arise
from the spontaneous breaking of an approximate symmetry and to
contribute to cold dark matter. We consider a simple model in which fermion
fields with multi-flavors are coupled to a scalar field through Yukawa
coupling, and examine how the number of the fermion flavors affects the
stability of the Fermi ball against the fragmentation. (1)We find that the
Fermi ball is stable against the fragmentation in most cases even in the lowest
order thin-wall approximation. (2)We then find that in the other specific
cases, the stability is marginal in the lowest order thin-wall approximation,
and the next-to-leading order correction determines the stable region of the
coupling constants; We examine the simplest case where the total fermion number
and the Yukawa coupling constant of each flavor are common to
the flavor, and find that the Fermi ball is stable in the limited region of the
parameters and has the broader region for the larger number of the flavors.Comment: 10 pages, 3 eps figures, ReVTeX
STRING v11: protein-protein association networks with increased coverage, supporting functional discovery in genome-wide experimental datasets
Proteins and their functional interactions form the backbone of the cellular machinery. Their connectivity network needs to be considered for the full understanding of biological phenomena, but the available information on protein-protein associations is incomplete and exhibits varying levels of annotation granularity and reliability. The STRING database aims to collect, score and integrate all publicly available sources of protein-protein interaction information, and to complement these with computational predictions. Its goal is to achieve a comprehensive and objective global network, including direct (physical) as well as indirect (functional) interactions. The latest version of STRING (11.0) more than doubles the number of organisms it covers, to 5090. The most important new feature is an option to upload entire, genome-wide datasets as input, allowing users to visualize subsets as interaction networks and to perform gene-set enrichment analysis on the entire input. For the enrichment analysis, STRING implements well-known classification systems such as Gene Ontology and KEGG, but also offers additional, new classification systems based on high-throughput text-mining as well as on a hierarchical clustering of the association network itself. The STRING resource is available online at https://string-db.org/
New Lump-like Structures in Scalar-field Models
In this work we investigate lump-like solutions in models described by a
single real scalar field. We start considering non-topological solutions with
the usual lump-like form, and then we study other models, where the bell-shape
profile may have varying amplitude and width, or develop a flat plateau at its
top, or even induce a lump on top of another lump. We suggest possible
applications where these exotic solutions might be used in several distinct
branches of physics.Comment: REvTex4, twocolumn, 10 pages, 9 figures; new reference added, to
appear in EPJ
On a class of stationary loops on SO(n) and the existence of multiple twisting solutions to a nonlinear elliptic system subject to a hard incompressibility constraint
For full abstract please refer to http://dx.doi.org/10.1186/s13661-018-1047-
Entrapment of a Network of Domain Walls
We explore the idea of a network of defects to live inside a domain wall in
models of three real scalar fields, engendering the Z_2 x Z_3 symmetry. The
field that governs the Z_2 symmetry generates a domain wall, and entraps the
hexagonal network formed by the three-junctions of the model of two scalar
fields that describes the remaining Z_3 symmetry. If the host domain wall bends
to the spherical form, in the thin wall approximation there may appear
non-topological structures hosting networks that accept diverse patterns. If
Z_3 is also broken, the model may generate a buckyball containing sixty
junctions, a fullerene-like structure. Applications to cosmology are outlined.Comment: Revtex, 4 pages, 2 ps figures; version to appear in Phys. Rev. D,
Rapid Communicatio
Diagnostic accuracy of consensus diagnostic criteria for frontotemporal dementia in a memory clinic population
Background/Aims: The goal of the present study was to evaluate the diagnostic accuracy of the core diagnostic criteria for frontotemporal dementia (FTD) [Neary D, et al: Neurology 1998;51:1546-1554] within a memory clinic population. Methods: The 5 core diagnostic criteria for FTD were operationalised in an informant-based written questionnaire. For a diagnosis of FTD the total clinical picture was weighted with findings on additional investigations and possible exclusion criteria, with follow-up of at least 1 year. Results: The operationalised core criteria for FTD had a sensitivity of 79% (95% CI = 57-92) and a specificity of 90% (95% CI = 85-94). Conclusion: The core diagnostic criteria for FTD applied in a caregiver questionnaire have good diagnostic accuracy among subjects without advanced dementia attending a memory clinic. This stresses the importance of the informant-based history in the differential diagnosis of dementia. Copyrigh
Star Formation and Dynamics in the Galactic Centre
The centre of our Galaxy is one of the most studied and yet enigmatic places
in the Universe. At a distance of about 8 kpc from our Sun, the Galactic centre
(GC) is the ideal environment to study the extreme processes that take place in
the vicinity of a supermassive black hole (SMBH). Despite the hostile
environment, several tens of early-type stars populate the central parsec of
our Galaxy. A fraction of them lie in a thin ring with mild eccentricity and
inner radius ~0.04 pc, while the S-stars, i.e. the ~30 stars closest to the
SMBH (<0.04 pc), have randomly oriented and highly eccentric orbits. The
formation of such early-type stars has been a puzzle for a long time: molecular
clouds should be tidally disrupted by the SMBH before they can fragment into
stars. We review the main scenarios proposed to explain the formation and the
dynamical evolution of the early-type stars in the GC. In particular, we
discuss the most popular in situ scenarios (accretion disc fragmentation and
molecular cloud disruption) and migration scenarios (star cluster inspiral and
Hills mechanism). We focus on the most pressing challenges that must be faced
to shed light on the process of star formation in the vicinity of a SMBH.Comment: 68 pages, 35 figures; invited review chapter, to be published in
expanded form in Haardt, F., Gorini, V., Moschella, U. and Treves, A.,
'Astrophysical Black Holes'. Lecture Notes in Physics. Springer 201
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