1,330 research outputs found
Improved predictions of the standard model and the detection of new physics in neutron beta decay
We improve the current predictions of the standard model for neutron beta
decay observables and compare them with the currently available ones. Next we
study their implications in the possible detection of new physics. We discuss
where the limitations are and where further efforts should be directed.Comment: 8 pages, 3 figures, to appear in Physics Letters
Emission Spectrum of Fundamental Strings: An Algebraic Approach
We formulate a linear difference equation which yields averaged
semi-inclusive decay rates for arbitrary, not necessarily large, values of the
masses. We show that the rates for decays M \to m+\M' of typical heavy open
strings are independent of the masses and , and compute the ``mass
deffect''. For closed strings we find decay rates proportional to , where is the reduced mass of the decy products. Our
method yields exact interaction rates valid for all mass ranges and may provide
a fully microscopic basis, not limited to the long string approximation, for
the interactions in the Boltzmann equation approach to hot string gases.Comment: 35 pages, 3 figure
Sun exposure behaviour, seasonal vitamin D deficiency, and relationship to bone health in adolescents
YesContext: Vitamin D is essential for bone health in adolescence, where there is rapid bone mineral
content accrual. As cutaneous sun-exposure provides vitamin D, there is no recommended oral intake
for UK adolescents.
Objective: Assess seasonal vitamin D status and its contributors in white Caucasian adolescents, and
examine bone health in those found deficient.
Design: Prospective cohort study.
Setting: Six schools in Greater Manchester, UK.
Participants: 131 adolescents, 12–15 years.
Intervention(s): Seasonal assessment of circulating 25-hydroxyvitamin D (25OHD), personal sunexposure
and dietary vitamin D. Adolescents deficient (25OHD <10 ng/mL/25 nmol/L) in ≥one
season underwent dual-energy X-ray absorptiometry (lumbar spine, femoral neck), with bone mineral
apparent density (BMAD) correction for size, and peripheral quantitative computed tomography
(distal radius) for volumetric (v)BMD.
Main Outcome Measure: Serum 25OHD; BMD.
Results: Mean 25OHD was highest in September: 24.1 (SD 6.9) ng/mL and lowest in January: 15.5
(5.9) ng/mL. Over the year, 16% were deficient in ≥one season and 79% insufficient (25OHD <20
ng/mL/50 nmol/L) including 28% in September. Dietary vitamin D was low year-round while
personal sun-exposure was seasonal and predominantly across the school week. Holidays accounted
for 17% variation in peak 25OHD (p<0.001). Nineteen adolescents underwent bone assessment,
which showed low femoral neck BMAD versus matched reference data (p=0.0002), 3 with Z≤ -2.0
distal radius trabecular vBMD.
Conclusions: Sun-exposure levels failed to provide adequate vitamin D, ~one-quarter adolescents
insufficient even at summer-peak. Seasonal vitamin D deficiency was prevalent and those affected
had low BMD. Recommendations on vitamin D acquisition are indicated in this age-group.The Bupa Foundation (Grant number TBF-M10-017)
Diffusion of electrons in random magnetic fields,
Diffusion of electrons in a two-dimensional system in static random magnetic
fields is studied by solving the time-dependent Schr\"{o}dinger equation
numerically. The asymptotic behaviors of the second moment of the wave packets
and the temporal auto-correlation function in such systems are investigated. It
is shown that, in the region away from the band edge, the growth of the
variance of the wave packets turns out to be diffusive, whereas the exponents
for the power-law decay of the temporal auto- correlation function suggest a
kind of fractal structure in the energy spectrum and in the wave functions. The
present results are consistent with the interpretation that the states away
from the band edge region are critical.Comment: 22 pages (8 figures will be mailed if requested), LaTeX, to appear in
Phys. Rev.
Nuclear structure of Ac-231
The low-energy structure of 231Ac has been investigated by means of gamma ray
spectroscopy following the beta-decay of 231Ra. Multipolarities of 28
transitions have been established by measuring conversion electrons with a
mini-orange electron spectrometer. The decay scheme of 231Ra --> 231Ac has been
constructed for the first time. The Advanced Time Delayed beta-gamma-gamma(t)
method has been used to measure the half-lives of five levels. The moderately
fast B(E1) transition rates derived suggest that the octupole effects, albeit
weak, are still present in this exotic nucleus
Comparison of risk scoring systems for patients presenting with upper gastrointestinal bleeding: international multicentre prospective study
Objective: To compare the predictive accuracy and clinical utility of five risk scoring systems in the assessment of patients with upper gastrointestinal bleeding.
Design: International multicentre prospective study.
Setting: Six large hospitals in Europe, North America, Asia, and Oceania.
Participants: 3012 consecutive patients presenting over 12 months with upper gastrointestinal bleeding.
Main outcome measures: Comparison of pre-endoscopy scores (admission Rockall, AIMS65, and Glasgow Blatchford) and post-endoscopy scores (full Rockall and PNED) for their ability to predict predefined clinical endpoints: a composite endpoint (transfusion, endoscopic treatment, interventional radiology, surgery, or 30 day mortality), endoscopic treatment, 30 day mortality, rebleeding, and length of hospital stay. Optimum score thresholds to identify low risk and high risk patients were determined.
Results: The Glasgow Blatchford score was best (area under the receiver operating characteristic curve (AUROC) 0.86) at predicting intervention or death compared with the full Rockall score (0.70), PNED score (0.69), admission Rockall score (0.66, and AIMS65 score (0.68) (all P<0.001). A Glasgow Blatchford score of ≤1 was the optimum threshold to predict survival without intervention (sensitivity 98.6%, specificity 34.6%). The Glasgow Blatchford score was better at predicting endoscopic treatment (AUROC 0.75) than the AIMS65 (0.62) and admission Rockall scores (0.61) (both P<0.001). A Glasgow Blatchford score of ≥7 was the optimum threshold to predict endoscopic treatment (sensitivity 80%, specificity 57%). The PNED (AUROC 0.77) and AIMS65 scores (0.77) were best at predicting mortality, with both superior to admission Rockall score (0.72) and Glasgow Blatchford score (0.64; P<0.001). Score thresholds of ≥4 for PNED, ≥2 for AIMS65, ≥4 for admission Rockall, and ≥5 for full Rockall were optimal at predicting death, with sensitivities of 65.8-78.6% and specificities of 65.0-65.3%. No score was helpful at predicting rebleeding or length of stay.
Conclusions: The Glasgow Blatchford score has high accuracy at predicting need for hospital based intervention or death. Scores of ≤1 appear the optimum threshold for directing patients to outpatient management. AUROCs of scores for the other endpoints are less than 0.80, therefore their clinical utility for these outcomes seems to be limited.
Trial registration: Current Controlled Trials ISRCTN16235737
Atl1 Regulates Choice between Global Genome and Transcription-Coupled Repair of O6-Alkylguanines
Nucleotide excision repair (NER) has long been known to remove DNA lesions induced by chemical carcinogens, and the molecular mechanism has been partially elucidated. Here we demonstrate that in Schizosaccharomyces pombe a DNA recognition protein, alkyltransferase-like 1 (Atl1), can play a pivotal role in selecting a specific NER pathway, depending on the nature of the DNA modification. The relative ease of dissociation of Atl1 from DNA containing small O6-alkylguanines allows accurate completion of global genome repair (GGR), whereas strong Atl1 binding to bulky O6-alkylguanines blocks GGR, stalls the transcription machinery, and diverts the damage to transcription-coupled repair. Our findings redraw the initial stages of the NER process in those organisms that express an alkyltransferase-like gene and raise the question of whether or not O6-alkylguanine lesions that are poor substrates for the alkyltransferase proteins in higher eukaryotes might, by analogy, signal such lesions for repair by NER
Fracture in the Elderly Multidisciplinary Rehabilitation (FEMuR):study protocol for a phase II randomised feasibility study of a multidisciplinary rehabilitation package following hip fracture [ ISRCTN22464643 ]
Background
Proximal femoral fracture is a common, major health problem in old age resulting in loss of functional independence and a high-cost burden on society, with estimated health and social care costs of £2.3 billion per year in the UK. Rehabilitation has the potential to maximise functional recovery and maintain independent living, but evidence of effectiveness is lacking. Usual rehabilitation care is delivered by a multi-disciplinary team in the hospital and in the community. An ‘enhanced rehabilitation’ intervention has been developed consisting of a workbook, goal-setting diary and extra therapy sessions, designed to improve self-efficacy and increase the amount and quality of the practice of physical exercise and activities of daily living.
Methods/design
This paper describes the design of a phase II study comprising an anonymous cohort of all proximal femoral fracture patients admitted to the three acute hospitals in Betsi Cadwaladr University Health Board over a 6-month period with a randomised feasibility study comparing the enhanced rehabilitation intervention with usual care. These will assess the feasibility of a future definitive randomised controlled trial and concurrent economic evaluation in terms of recruitment, retention, outcome measure completion, compliance with the intervention and fidelity of delivery, health service use data, willingness to be randomised and effect size for a future sample size calculation. Focus groups will provide qualitative data to contribute to the assessment of the acceptability of the intervention amongst patients, carers and rehabilitation professionals and the feasibility of delivering the planned intervention. The primary outcome measure is function assessed by the Barthel Index. Secondary outcomes measure the ability to perform activities of daily living, anxiety and depression, potential mediators of outcomes such as hip pain, self-efficacy and fear of falling, health utility, health service use, objectively assessed physical function and adverse events. Participants’ preference for rehabilitation services will be assessed in a discrete choice experiment.
Discussion
Phase II studies are an opportunity to not only assess the feasibility of trial methods but also to compare different methods of outcome measurement and novel methods of obtaining health service use data from routinely collected patient information.
Trial registration
Current Controlled Trials ISRCTN22464643, UKCRN16677
Fluctuation Relations for Diffusion Processes
The paper presents a unified approach to different fluctuation relations for
classical nonequilibrium dynamics described by diffusion processes. Such
relations compare the statistics of fluctuations of the entropy production or
work in the original process to the similar statistics in the time-reversed
process. The origin of a variety of fluctuation relations is traced to the use
of different time reversals. It is also shown how the application of the
presented approach to the tangent process describing the joint evolution of
infinitesimally close trajectories of the original process leads to a
multiplicative extension of the fluctuation relations.Comment: 38 page
Discovery of Calcium, Indium, Tin, and Platinum Isotopes
Currently, twenty-four calcium, thirty-eight indium, thirty-eight tin and
thirty-nine platinum isotopes have been observed and the discovery of these
isotopes is discussed here. For each isotope a brief synopsis of the first
refereed publication, including the production and identification method, is
presented.Comment: to be published in At. Data Nuclear Data Tables, This updated paper
combines manuscripts: 1004.4934 (Calcium), 1004.5266 (Indium), 1003.5127
(Tin), and 1006.4033 (Platinum
- …