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Finite groups of untwisted outer automorphisms of RAAGs
Get PDFFor any right-angled Artin group A_Γ , Charney-Stambaugh-Vogtmann showed that the subgroup U^0(A_Γ) of Out(A_Γ) generated by Whitehead automorphisms and inversions acts properly and cocompactly on a contractible space K_Γ . In the present paper we show that any finite subgroup of U^0(A_Γ) fixes a point of K_Γ . This generalizes the fact that any finite subgroup of Out(F_n) fixes a point of Outer Space, and implies that there are only finitely many conjugacy classes of finite subgroups in U^0(A_Γ)
Experimental process characterisation for high-volume compression moulding of hybrid-architecture composites
Get PDFCompression moulding of woven fabric prepreg and sheet moulding compound (SMC) in a single-shot process combines the superior mechanical properties of continuous fibre composites and the high design flexibility of discontinuous fibre composites. This experimental study presents insights into the moulding characteristics of prepreg and SMC and explores the interaction between these two materials during manufacturing of hybrid-architecture composites. All tests were performed under typical compression moulding conditions using a squeeze flow testing rig. The response of each material was interpreted through proposed material models applied to the data acquired from single architecture tests. Critical interaction mechanisms were identified from hybrid architecture tests, alongside some additional deformation mechanisms, such as high level of in-plane fibre tow deformation not observed in single-architecture tests. Novel experimental methods were also introduced to quantify the change in meso-scale fibre architecture in the prepreg induced by the flow of SMC. The outcomes of this study not only shed light on the essential interaction mechanisms of hybrid-architecture composites but also provide valuable insights into deformation mechanisms not apparent in isolated material studies. Ultimately, these findings will facilitate the future development of a numerical simulation model for hybrid moulding processes
Talking in primary care (TIP) : protocol for a cluster-randomised controlled trial in UK primary care to assess clinical and cost-effectiveness of communication skills e-learning for practitioners on patients’ musculoskeletal pain and enablement
Get PDFIntroduction: Effective communication can help optimise healthcare interactions and patient outcomes. However, few interventions have been tested clinically, subjected to cost-effectiveness analysis or are sufficiently brief and well-described for implementation in primary care. This paper presents the protocol for determining the effectiveness and cost-effectiveness of a rigorously developed brief eLearning tool, EMPathicO, among patients with and without musculoskeletal pain. Methods and analysis: A cluster randomised controlled trial in general practitioner (GP) surgeries in England and Wales serving patients from diverse geographic, socioeconomic and ethnic backgrounds. GP surgeries are randomised (1:1) to receive EMPathicO e-learning immediately, or at trial end. Eligible practitioners (eg, GPs, physiotherapists and nurse practitioners) are involved in managing primary care patients with musculoskeletal pain. Patient recruitment is managed by practice staff and researchers. Target recruitment is 840 adults with and 840 without musculoskeletal pain consulting face-to-face, by telephone or video. Patients complete web-based questionnaires at preconsultation baseline, 1 week and 1, 3 and 6 months later. There are two patient-reported primary outcomes: pain intensity and patient enablement. Cost-effectiveness is considered from the National Health Service and societal perspectives. Secondary and process measures include practitioner patterns of use of EMPathicO, practitioner-reported self-efficacy and intentions, patient-reported symptom severity, quality of life, satisfaction, perceptions of practitioner empathy and optimism, treatment expectancies, anxiety, depression and continuity of care. Purposive subsamples of patients, practitioners and practice staff take part in up to two qualitative, semistructured interviews. Ethics approval and dissemination: Approved by the South Central Hampshire B Research Ethics Committee on 1 July 2022 and the Health Research Authority and Health and Care Research Wales on 6 July 2022 (REC reference 22/SC/0145; IRAS project ID 312208). Results will be disseminated via peer-reviewed academic publications, conference presentations and patient and practitioner outlets. If successful, EMPathicO could quickly be made available at a low cost to primary care practices across the country. Trial registration number: ISRCTN18010240
Emergency medical dispatchers’ experiences of using the Medical Priority Dispatch System telephone triage to identify maternity emergencies : a qualitative focus group study
Get PDFObjectives: The ambulance service plays a pivotal role in the provision of care in out-of-hospital maternity emergencies. Telephone triage of this patient group is complex and must be sensitive to an emergency situation to prevent unnecessary delays in treatment. This study aimed to explore emergency medical dispatchers’ (EMDs) perceptions of the structured protocol they use. Design: Voluntary participation in semistructured phenomenological focus groups. The participants were asked to discuss their experiences of using Medical Priority Dispatch System Protocol 24 (pregnancy, childbirth and miscarriage). Thematic analysis was applied to code and group topics. Discussion between the EMDs is presented for each theme and their experiences, including quotes, are presented to offer an overview of the maternity protocol and its use. Setting: A large urban UK ambulance service. Participants: 23 control room staff. Results: Perceptions of maternity emergencies, challenges with key questions, the need for sensitivity surrounding miscarriage, using prearrival instructions and postdispatch instructions to help patients and ideas for additional ProQA functionality emerged as the five overarching themes. Protocol 24 was considered to reflect many of the clinical factors EMDs associate with maternity emergencies although further factors, including some non-clinical, were suggested for inclusion. Miscarriage and termination-related calls were thought to be challenging as the language of the protocol is designed for pregnancy. However, instructions were generally considered well written and user-friendly, although some were thought to be unnecessary. EMDs were largely positive regarding the ProQA software, but felt backward navigation was difficult if a situation changed. Conclusions: Maternity calls were considered rewarding but complex by EMDs. We suggest changes including the use of more sensitive language in response to miscarriage and termination and make recommendations for the omission and inclusion of specific instructions, as well as enhancements to key questions and functionality. Further research is needed to ensure focus group findings are generalisable to other services, particularly in other countries
Solvated inverse vulcanisation by photopolymerisation
Get PDFInverse Vulcanisation (IV) under neat reaction conditions (without solvent) has enabled the research and development of the fundamental chemistry as well as the generation of unique sulfur-rich polymers with unprecedented properties. However, such bulk polymerisation can be problematic, especially with high molecular weight. The energetics of the thermal polymerisation process, combined with poor heat control of solvent-free polymerisation, cause risks of dangerous auto-acceleration if the process is scaled up. The required high temperatures (>160 °C or 135 °C even with catalysts), exceed the boiling point of most commonplace organic solvents, preventing implementation of solvents for IV under thermal conditions. We report here a photo-induced IV polymerisation in solvent at room temperature. The reactions proceed smoothly and efficiently with excellent yields, despite the potential negative factors of reflection, refraction, and low absorption intensity of light by these organic solvents, opening an attractive avenue for the preparation of functional sulfur-rich polymers as well as their potential applications. The extension of crosslinkers to the value-added C5 fraction of industrial byproduct and β-carotene showcase the benefit of this low temperature protocol. Mechanistic study reveals that the moisture in both substrates and solvents might play a key role for the generation of toxic H2S by-product in IV reaction under thermal conditions, with photopolymerisation remaining un-affected. This protocol not only extensively expands the scope of crosslinkers for the IV reaction together with resultant polymers, but also provides a potential scale-up route for industrial application by avoiding the generation of toxic H2S by-product and possible explosion risk with high temperature
Acoustic field visualisation using local absorption of ultrasound and thermochromic liquid crystals
Get PDFAcoustic field and vibration visualisation is important in a wide range of applications. Laser vibrometry is often used for such visualisation, however, the equipment has a high cost and requires significant user expertise, and the method can be slow, as it requires scanning point by point. Here we suggest a different approach to visualisation of acoustic fields in the kHz – MHz range, using paint-on or removable film sensors, which produce a direct visual map of ultrasound displacement. The sensors are based on a film containing thermochromic liquid crystals (TLC), along with a backing/underlay layer which improves absorption of ultrasound. The absorption generates heat, which can be seen by a change in colour of the TLC film. A removable sensor is used to visualise the resonant modes of an air-coupled flexural transducer operated from 410 kHz to 7.23 MHz, and to visualise 40 kHz standing waves in a Perspex plate. The thermal basis of the visualisation is confirmed using thermal imaging. The speed and cost of visualisation makes the new sensor attractive for use in condition monitoring, for fast assessment of transducer quality, or for analysis of acoustic field distribution in power ultrasonic systems
Synthesis of lipid-linked precursors of the bacterial cell wall is governed by a feedback control mechanism in Pseudomonas aeruginosa
Get PDFMany bacterial surface glycans such as the peptidoglycan (PG) cell wall are built from monomeric units linked to a polyprenyl lipid carrier. How this limiting carrier is distributed among competing pathways has remained unclear. Here we describe the isolation of hyperactive variants of Pseudomonas aeruginosa MraY, the enzyme that forms the first lipid-linked PG precursor. These variants result in the elevated production of the final PG precursor lipid II in cells and are hyperactive in vitro. The activated MraY variants have substitutions that map to a cavity on the extracellular side of the dimer interface, far from the active site. Our structural and molecular dynamics results suggest that this cavity is a binding site for externalized lipid II. Overall, our results support a model in which excess externalized lipid II allosterically inhibits MraY, providing a feedback mechanism that prevents the sequestration of lipid carrier in the PG biogenesis pathway