Effects of a torsion field on Big Bang nucleosynthesis

In this paper it is investigated whether torsion, which arises naturally in most theories of quantum gravity, has observable implications for the Big Bang nucleosynthesis. Torsion can lead to spin flips amongst neutrinos thus turning them into sterile neutrinos. In the early Universe they can alter the helium abundance which is tightly constrained by observations. Here I calculate to what extent torsion of the string theory type leads to a disagreement with the Big Bang nucleosynthesis predictions.Comment: accepted by General Relativity and Gravitatio

Effect of delayed acquisition times on Gadolinium-enhanced MRI of the presumably normal canine brain

A delay in imaging following intravenous contrast medium administration has been recommended to reduce misdiagnoses. However, the normal variation of contrast enhancement in dogs following a delay has not been characterized. Contrast enhanced MR imaging of 22 dogs was assessed, in terms of identification of normal anatomic structures, to investigate the variation associated with 10 minute delay between contrast medium administration and imaging. All dogs had a normal brain MR imaging study and unremarkable CSF. Specific ROIs were assessed both objectively, using computer software, and subjectively using three observers. Mean contrast enhancement greater than 10% was seen in the pituitary gland, choroid plexus, meninges, temporal muscle, trigeminal nerve and the trigeminal nerve root. Structures with an active blood-brain-barrier had minimal contrast enhancement (<6%). Enhancing structures had significantly more contrast enhancement at t=1min versus t=10min, except in temporal muscle, the trigeminal nerve and the trigeminal nerve root. Inter-observer agreement was moderate to good in favor of the initial post contrast T1w sequence. The observers found either no difference or poor agreement in identification of the non-vascular structures. Intra-observer agreement was very good with all vascular structures and most non-vascular structures. A degree of meningeal enhancement was a consistent finding. The initial acquisition had higher enhancement characteristics and observer agreement for some structures; however, contrast-to-noise was comparable in the delayed phase or not significantly different. We provide baseline references and suggest that the initial T1w post contrast sequence is preferable but not essential should a delayed post contrast T1w sequence be performed

Association between low 25(OH) vitamin D levels, antiretroviral therapy and metabolic profile in a cohort of treated ahd therapy naive HIV positive patients in Western Australia

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Students with specific learning disabilities experiences of pre-registration physiotherapy education: a qualitative study.

Background Attainment gaps for students with disabilities have been noted in pre-registration physiotherapy courses in the UK. Previous research suggests disclosure, lack of staff knowledge and poor communication between University and placement sites may be relevant, but these are limited to small case studies with students with visual or physical disabilities. The purpose of this study was to explore disabled physiotherapy students’ experiences of their education in order to elucidate factors that may influence success. Methods Qualitative study drawing on phenomenological traditions. Four focus groups including 15 students with disabilities were conducted. Transcripts were analysed thematically. Procedures for transparency and rigour such as member checking and peer debriefing were implemented. Results Three major themes were derived from data. “It was quite a relief” explores the personal and social implications of diagnosis. “They’re not natural” focuses on academic assessment and the specifics of adjustments made and not made within that context. “My dyslexia doesn’t switch off” explores the inaccessibility of the learning environment and dissects the contrast between the 24-h nature of having a specific learning condition and the somewhat piecemeal nature of adjustments during their education. Conclusions This study indicates that having a specific learning disability or anxiety creates a number of hurdles to success in physiotherapy education. Most were within the University setting and were perceived to result from staff ignorance or piecemeal approaches to inclusion. A lack of consistency alongside facilitated dialogue and acknowledgement of enhancements results in frustration, ambiguity towards disclosure and reinforcement of a deficit model. Such an approach belies the intention of the profession and the NHS and does not maximise the potential of widening participation

Working hard to belong: a qualitative study exploring students from black, Asian and minority ethnic backgrounds experiences of pre-registration physiotherapy education

Background Previous research has demonstrated that attainment inequalities exist for students from Black Asian and Minority Ethnic (BAME) groups in pre-registration physiotherapy education. While previous research has explored students from BAME backgrounds experience of university, the context of physiotherapy is unique and is under researched. Therefore the purpose of this study was to explore BAME student experiences during their physiotherapy training. Methods Using a phenomenological approach pre-registration BSc and MSc students from BAME backgrounds from two universities who had completed both academic and clinical modules were invited to participate. Focus groups followed a topic guide developed from the literature and were facilitated by physiotherapy educators from outside the host institution. They were digitally recorded, transcribed verbatim and analysed thematically. Analytical triangulation was adopted throughout the research process as a mechanism to enhance rigour. Results Seventeen students participated from a range of self-identified BAME backgrounds that were also representative of age, gender and course. Themes derived from the data included: feeling an outsider in reflections of belonging, behaviours by others that marginalise BAME and personal strategies to integrate in physiotherapy despite the lack of power and influence. Collectively these themes demonstrate a range of challenges which students from BAME backgrounds face within both an academic and practice learning environment. Conclusions While this may not be surprising based on other disciplines, this study demonstrates that studying physiotherapy as a student from BAME background requires persistence to overcome a series of many implicit challenges. Understanding the experiences of students from BAME backgrounds presents unique opportunities to educate the profession and co-create opportunities for a more diverse profession with practitioners and educators as role models. There is a need for greater training for educators to listen to these students’ voices and their stories, and understand where institutional structures and practices could be modified to enable BAME student inclusion in physiotherapy education and practice

Superconducting niobium thin film slow-wave structures

A superconducting comb structure as a slow-wave element in a traveling-wave maser will significantly improve maser noise temperature and gain by reducing the insertion loss. The results of the insertion loss measurements of superconducting niobium slow-wave structures subjected to maser operating conditions at X-Band frequencies are presented

Fermion Helicity Flip Induced by Torsion Field

We show that in theories of gravitation with torsion the helicity of fermion particles is not conserved and we calculate the probability of spin flip, which is related to the anti-symmetric part of affine connection. Some cosmological consequences are discussed.Comment: 6 pages, to appear in Europhysics Letter

Pressure-induced diamond to beta-tin transition in bulk silicon: a near-exact quantum Monte Carlo study

The pressure-induced structural phase transition from diamond to beta-tin in silicon is an excellent test for theoretical total energy methods. The transition pressure provides a sensitive measure of small relative energy changes between the two phases (one a semiconductor and the other a semimetal). Experimentally, the transition pressure is well characterized. Density-functional results have been unsatisfactory. Even the generally much more accurate diffusion Monte Carlo method has shown a noticeable fixed-node error. We use the recently developed phaseless auxiliary-field quantum Monte Carlo (AFQMC) method to calculate the relative energy differences in the two phases. In this method, all but the error due to the phaseless constraint can be controlled systematically and driven to zero. In both structural phases we were able to benchmark the error of the phaseless constraint by carrying out exact unconstrained AFQMC calculations for small supercells. Comparison between the two shows that the systematic error in the absolute total energies due to the phaseless constraint is well within 0.5 mHa/atom. Consistent with these internal benchmarks, the transition pressure obtained by the phaseless AFQMC from large supercells is in very good agreement with experiment.Comment: 9 pages, 5 figure