The structure of fluid trifluoromethane and methylfluoride

We present hard X-ray and neutron diffraction measurements on the polar fluorocarbons HCF3 and H3CF under supercritical conditions and for a range of molecular densities spanning about a factor of ten. The Levesque-Weiss-Reatto inversion scheme has been used to deduce the site-site potentials underlying the measured partial pair distribution functions. The orientational correlations between adjacent fluorocarbon molecules -- which are characterized by quite large dipole moments but no tendency to form hydrogen bonds -- are small compared to a highly polar system like fluid hydrogen chloride. In fact, the orientational correlations in HCF3 and H3CF are found to be nearly as small as those of fluid CF4, a fluorocarbon with no dipole moment.Comment: 11 pages, 9 figure

The Structure, Dynamics and Electronic Structure of Liquid Ag-Se Alloys Investigated by Ab Initio Simulation

Ab initio molecular-dynamics simulations have been used to investigate the structure, dynamics and electronic properties of the liquid alloy Ag(1-x)Se(x) at 1350 K and at the three compositions x=0.33, 0.42 and 0.65. The calculations are based on density-functional theory in the local density approximation and on the pseudopotential plane-wave method. The reliability of the simulations is confirmed by detailed comparisons with very recent neutron diffraction results for the partial structure factors and radial distribution functions (RDF) of the stoichiometric liquid Ag2Se. The simulations show a dramatic change of the Se-Se RDF with increasing Se content. This change is due to the formation of Se clusters bound by covalent bonds, the Se-Se bond length being almost the same as in pure c-Se and l-Se. The clusters are predominantly chain-like, but for higher x a large fraction of 3-fold coordinated Se atoms is also found. It is shown that the equilibrium fractions of Se present as isolated atoms and in clusters can be understood on a simple charge-balance model based on an ionic interpretation. The Ag and Se diffusion coefficients both increase with Se content, in spite of the Se clustering. An analysis of the Se-Se bond dynamics reveals surprisingly short bond lifetimes of less than 1 ps. The changes in the density of states with composition arise directly from the formation of Se-Se covalent bonds. Results for the electronic conductivity obtained using the Kubo-Greenwood approximation are in adequate agreement with experiment for l-Ag2Se, but not for the high Se contents. Possible reasons for this are discussed.Comment: 14 pages, Revtex, 14 Postscript figures embedded in the tex

The benefits of a 5-day dysphagia intensive placement

Finding practical dysphagia opportunities for students pre-qualification is challenging. Discussions with clinicians led to the development of a new placement model. The placement was just five days and had an accompanying workbook. The current study aimed to evaluate the benefits of the placement. Data were analysed from 40 students who attended an adult dysphagia placement and 13 who attended a paediatric dysphagia placement. Measures included a pre and post self-rating questionnaire, qualitative feedback from clinical educators and students and a pre and post measure of knowledge using concept maps. Student self-rating data indicated gains in experience, awareness, knowledge, clinical skills, competence, confidence and interest in dysphagia. Clinical educators and students also reported a range of benefits from this placement. Students who undertook a placement that focused on adult dysphagia significantly increased their knowledge of adult dysphagia, but this did not generalize to paediatric dysphagia. Despite reporting that they felt they had gained in knowledge of dysphagia, the students who did a paediatric dysphagia placement did not significantly increase their knowledge of dysphagia. The study raises a number of important considerations when designing placements including length, timing, intensity, how best to encourage generalization of knowledge, and how best to measure learning

Behavior of the thermopower in amorphous materials at the metal-insulator transition

Published versio

A comparison of specialist rehabilitation and care assistant support with specialist rehabilitation alone and usual care for people with Parkinson's living in the community: study protocol for a randomised controlled trial

<p>Abstract</p> <p>Background</p> <p>Parkinson's Disease is a degenerative neurological condition that causes movement problems and other distressing symptoms. People with Parkinson's disease gradually lose their independence and strain is placed on family members. A multidisciplinary approach to rehabilitation for people with Parkinson's is recommended but has not been widely researched. Studies are needed that investigate cost-effective community-based service delivery models to reduce disability and dependency and admission to long term care, and improve quality of life.</p> <p>Methods</p> <p>A pragmatic three parallel group randomised controlled trial involving people with Parkinson's Disease and live-in carers (family friends or paid carers), and comparing: management by a specialist multidisciplinary team for six weeks, according to a care plan agreed between the professionals and the patient and carer (Group A); multidisciplinary team management and additional support for four months from a trained care assistant (Group B); usual care, no coordinated team care planning or ongoing support (Group C). Follow up will be for six months to determine the impact and relative cost-effectiveness of the two interventions, compared to usual care. The primary outcomes are disability (patients) and strain (carers). Secondary outcomes include patient mobility, falls, speech, pain, self efficacy, health and social care use; carer general health; patient and carer social functioning, psychological wellbeing, health related quality of life. Semi structured interviews will be undertaken with providers (team members, care assistants), service commissioners, and patients and carers in groups A and B, to gain feedback about the acceptability of the interventions. A cost - effectiveness evaluation is embedded in the trial.</p> <p>Discussion</p> <p>The trial investigates components of recent national policy recommendations for people with long term conditions, and Parkinson's Disease in particular, and will provide guidance to inform local service planning and commissioning.</p> <p>Trial registration</p> <p>ISRCTN: <a href="http://www.controlled-trials.com/ISRCTN44577970">ISRCTN44577970</a></p

Utilising a systematic review-based approach to create a database of individual participant data for meta- and network meta-analyses: the RELEASE database of aphasia after stroke

Background: Collation of aphasia research data across settings, countries and study designs using big data principles will support analyses across different language modalities, levels of impairment, and therapy interventions in this heterogeneous population. Big data approaches in aphasia research may support vital analyses, which are unachievable within individual trial datasets. However, we lack insight into the requirements for a systematically created database, the feasibility and challenges and potential utility of the type of data collated. Aim: To report the development, preparation and establishment of an internationally agreed aphasia after stroke research database of individual participant data (IPD) to facilitate planned aphasia research analyses. Methods: Data were collated by systematically identifying existing, eligible studies in any language (≥10 IPD, data on time since stroke, and language performance) and included sourcing from relevant aphasia research networks. We invited electronic contributions and also extracted IPD from the public domain. Data were assessed for completeness, validity of value-ranges within variables, and described according to pre-defined categories of demographic data, therapy descriptions, and language domain measurements. We cleaned, clarified, imputed and standardised relevant data in collaboration with the original study investigators. We presented participant, language, stroke, and therapy data characteristics of the final database using summary statistics. Results: From 5256 screened records, 698 datasets were potentially eligible for inclusion; 174 datasets (5928 IPD) from 28 countries were included, 47/174 RCT datasets (1778 IPD) and 91/174 (2834 IPD) included a speech and language therapy (SLT) intervention. Participants’ median age was 63 years (interquartile range [53, 72]), 3407 (61.4%) were male and median recruitment time was 321 days (IQR 30, 1156) after stroke. IPD were available for aphasia severity or ability overall (n = 2699; 80 datasets), naming (n = 2886; 75 datasets), auditory comprehension (n = 2750; 71 datasets), functional communication (n = 1591; 29 datasets), reading (n = 770; 12 datasets) and writing (n = 724; 13 datasets). Information on SLT interventions were described by theoretical approach, therapy target, mode of delivery, setting and provider. Therapy regimen was described according to intensity (1882 IPD; 60 datasets), frequency (2057 IPD; 66 datasets), duration (1960 IPD; 64 datasets) and dosage (1978 IPD; 62 datasets). Discussion: Our international IPD archive demonstrates the application of big data principles in the context of aphasia research; our rigorous methodology for data acquisition and cleaning can serve as a template for the establishment of similar databases in other research areas

Predictors of Poststroke Aphasia Recovery A Systematic Review-Informed Individual Participant Data Meta-Analysis

Background and Purpose: The factors associated with recovery of language domains after stroke remain uncertain. We described recovery of overall-language-ability, auditory comprehension, naming, and functional-communication across participants’ age, sex, and aphasia chronicity in a large, multilingual, international aphasia dataset. / Methods: Individual participant data meta-analysis of systematically sourced aphasia datasets described overall-language ability using the Western Aphasia Battery Aphasia-Quotient; auditory comprehension by Aachen Aphasia Test (AAT) Token Test; naming by Boston Naming Test and functional-communication by AAT Spontaneous-Speech Communication subscale. Multivariable analyses regressed absolute score-changes from baseline across language domains onto covariates identified a priori in randomized controlled trials and all study types. Change-from-baseline scores were presented as estimates of means and 95% CIs. Heterogeneity was described using relative variance. Risk of bias was considered at dataset and meta-analysis level. / Results: Assessments at baseline (median=43.6 weeks poststroke; interquartile range [4–165.1]) and first-follow-up (median=10 weeks from baseline; interquartile range [3–26]) were available for n=943 on overall-language ability, n=1056 on auditory comprehension, n=791 on naming and n=974 on functional-communication. Younger age (<55 years, +15.4 Western Aphasia Battery Aphasia-Quotient points [CI, 10.0–20.9], +6.1 correct on AAT Token Test [CI, 3.2–8.9]; +9.3 Boston Naming Test points [CI, 4.7–13.9]; +0.8 AAT Spontaneous-Speech Communication subscale points [CI, 0.5–1.0]) and enrollment <1 month post-onset (+19.1 Western Aphasia Battery Aphasia-Quotient points [CI, 13.9–24.4]; +5.3 correct on AAT Token Test [CI, 1.7–8.8]; +11.1 Boston Naming Test points [CI, 5.7–16.5]; and +1.1 AAT Spontaneous-Speech Communication subscale point [CI, 0.7–1.4]) conferred the greatest absolute change-from-baseline across each language domain. Improvements in language scores from baseline diminished with increasing age and aphasia chronicity. Data exhibited no significant statistical heterogeneity. Risk-of-bias was low to moderate-low. / Conclusions: Earlier intervention for poststroke aphasia was crucial to maximize language recovery across a range of language domains, although recovery continued to be observed to a lesser extent beyond 6 months poststroke

Communicating simply, but not too simply: Reporting of participants and speech and language interventions for aphasia after stroke

Purpose: Speech and language pathology (SLP) for aphasia is a complex intervention delivered to a heterogeneous population within diverse settings. Simplistic descriptions of participants and interventions in research hinder replication, interpretation of results, guideline and research developments through secondary data analyses. This study aimed to describe the availability of participant and intervention descriptors in existing aphasia research datasets. Method: We systematically identified aphasia research datasets containing ≥10 participants with information on time since stroke and language ability. We extracted participant and SLP intervention descriptions and considered the availability of data compared to historical and current reporting standards. We developed an extension to the Template for Intervention Description and Replication checklist to support meaningful classification and synthesis of the SLP interventions to support secondary data analysis. Result: Of 11, 314 identified records we screened 1131 full texts and received 75 dataset contributions. We extracted data from 99 additional public domain datasets. Participant age (97.1%) and sex (90.8%) were commonly available. Prior stroke (25.8%), living context (12.1%) and socio-economic status (2.3%) were rarely available. Therapy impairment target, frequency and duration were most commonly available but predominately described at group level. Home practice (46.3%) and tailoring (functional relevance 46.3%) were inconsistently available. Conclusion : Gaps in the availability of participant and intervention details were significant, hampering clinical implementation of evidence into practice and development of our field of research. Improvements in the quality and consistency of participant and intervention data reported in aphasia research are required to maximise clinical implementation, replication in research and the generation of insights from secondary data analysis