A holonomy characterisation of Fefferman spaces

We prove that Fefferman spaces, associated to non--degenerate CR structures of hypersurface type, are characterised, up to local conformal isometry, by the existence of a parallel orthogonal complex structure on the standard tractor bundle. This condition can be equivalently expressed in terms of conformal holonomy. Extracting from this picture the essential consequences at the level of tensor bundles yields an improved, conformally invariant analogue of Sparling's characterisation of Fefferman spaces.Comment: AMSLaTeX, 15 page

Multivariate analysis of biologging data reveals the environmental determinants of diving behaviour in a marine reptile

Diving behaviour of ‘surfacers' such as sea snakes, cetaceans and turtles is complex and multi-dimensional, thus may be better captured by multi-sensor biologging data. However, analysing these large multi-faceted datasets remains challenging, though a high priority. We used high-resolution multi-sensor biologging data to provide the first detailed description of the environmental influences on flatback turtle (Natator depressus) diving behaviour, during its foraging life-history stage. We developed an analytical method to investigate seasonal, diel and tidal effects on diving behaviour for 24 adult flatback turtles tagged with biologgers. We extracted 16 dive variables associated with three-dimensional and kinematic characteristics for 4128 dives. K-means and hierarchical cluster analyses failed to identify distinct dive types. Instead, principal component analysis objectively condensed the dive variables, removing collinearity and highlighting the main features of diving behaviour. Generalized additive mixed models of the main principal components identified significant seasonal, diel and tidal effects on flatback turtle diving behaviour. Flatback turtles altered their diving behaviour in response to extreme tidal and water temperature ranges, displaying thermoregulation and predator avoidance strategies while likely optimizing foraging in this challenging environment. This study demonstrates an alternative statistical technique for objectively interpreting diving behaviour from multivariate collinear data derived from biologgers

Coping styles associated with depression, health anxiety and health-related quality of life in pulmonary hypertension : cross-sectional analysis

Objectives Pulmonary hypertension (PH) is a life-shortening disease associated with early mortality and high morbidity. With advancements in medical treatment, people are living longer with the disease, and research is now needed to explore variables that help to enhance patient-reported outcomes. This study investigated the coping strategies of individuals with PH and examined the relationship between coping, depression, health anxiety and health-related quality of life (HRQoL). Design A cross-sectional survey design was used. Participants Participants (n=121) were recruited from membership of Pulmonary Hypertension Association (PHA) UK. Outcome measures Participants completed a series of questionnaires assessing depression (Patient Health Questionnaire-9), health anxiety (Short Health Anxiety Inventory), HRQoL (emPHasis-10) and coping (Brief COPE). A principal component analysis was used to identify participants’ coping profile. A series of correlational, linear and moderated multiple regression analyses were performed to examine the relationship between coping and health-related outcomes. Results Overall, 43% participants met criteria for potential clinical depression. Depression and health anxiety were strongly associated with HRQoL, explaining 37% and 30% of variance respectively (p<0.001). A principal component analysis identified a four-component model of coping. Dimensions were named based on construct items: ‘cognitive and affirmation coping’ (seven items), ‘passive coping’ (four items), ‘external coping’ (seven items) and ‘substance use coping’ (two items). Cognitive and affirmation and external coping moderated the relationship between depression and HRQoL, with high use of these coping strategies reducing the impact of depression on HRQoL. External coping also moderated the effect of health anxiety on HRQoL. Conclusions The results uniquely highlight the importance of coping styles and psychological distress in predicting HRQoL in PH. Our findings indicate the importance to assess for psychological distress in this population and suggest the need to offer psychological interventions that take into account coping resources and strategies

The International development of PROQOL-HCV: An instrument to assess the health-related quality of life of patients treated for Hepatitis C virus

Background Hepatitis C virus (HCV) compromises Health-related Quality of Life (HRQL) with detriments to Physical, Mental and Social health domains. Treatment with interferon and ribavirin is associated with side effects which further impair HRQL. New treatments appear potent, effective and tolerable. However, Patient Reported Outcomes instruments that capture the impact on HRQL for people with hepatitis C are largely non-specific and will be needed in the new treatment era. Therefore, we developed a conceptually valid multidimensional model of HCV-specific quality of life and pilot survey instrument, the Patient Reported Outcome Quality of Life survey for HCV (PROQOL-HCV). Methods HCV patients from France (n = 30), Brazil (n = 20) and Australia (n  = 20) were interviewed to investigate HCV-HRQL issues raised in the scientific literature and by treatment specialists. Interviews were recorded, transcribed and translated into English and French. Results Fifteen content dimensions were derived from the qualitative analysis, refined and fitted to four domains: (1) Physical Health included: fatigue, pain, sleep, sexual impairment and physical activity; (2) Mental Health: psychological distress, psychosocial impact, and cognition; (3) Social Health: support, stigma, social activity, substance use; (4) Treatment: management, side effects, and fear of treatment failure. The impact of some dimensions extended beyond their primary domain including: physical activity, cognition, sleep, sexual impairment, and the three treatment dimensions. A bank of 300 items was constructed to reflect patient reports and, following expert review, reduced to a 72-item pilot questionnaire. Conclusion We present a conceptually valid multidimensional model of HCV-specific quality of life and the pilot survey instrument, PROQOL-HCV. The model is widely inclusive of the experience of hepatitis C and the first to include the treatment dimension

Smooth metric measure spaces, quasi-Einstein metrics, and tractors

We introduce the tractor formalism from conformal geometry to the study of smooth metric measure spaces. In particular, this gives rise to a correspondence between quasi-Einstein metrics and parallel sections of certain tractor bundles. We use this formulation to give a sharp upper bound on the dimension of the vector space of quasi-Einstein metrics, providing a different perspective on some recent results of He, Petersen and Wylie.Comment: 33 pages; final versio

Strange quark matter in a chiral SU(3) quark mean field model

We apply the chiral SU(3) quark mean field model to investigate strange quark matter. The stability of strange quark matter with different strangeness fraction is studied. The interaction between quarks and vector mesons destabilizes the strange quark matter. If the strength of the vector coupling is the same as in hadronic matter, strangelets can not be formed. For the case of beta equilibrium, there is no strange quark matter which can be stable against hadron emission even without vector meson interactions.Comment: 19 pages, 8 figure

Adults’ experiences of living with pulmonary hypertension: a thematic synthesis of qualitative studies

Objectives Pulmonary hypertension is a life-shortening disease that has a considerable impact on quality of life. Improving our understanding of how individuals are affected and cope with the disease will help to improve services and outcomes. This review synthesises the published qualitative research that has listened to adults discuss their experiences of living with the disease. Design A comprehensive systematic search of four databases was conducted in May 2020: Web of Science, PubMed, PsycINFO and Cochrane Library. Suitable studies were evaluated using the Critical Appraisal Skills programme. Findings from the studies were extracted and subjected to a thematic synthesis. Results Nineteen articles were identified reflecting the experiences of over 1900 individuals impacted by pulmonary hypertension from Europe, North and South America and Asia. Ten studies did not report participant’s WHO functional class of pulmonary hypertension, which resulted in comparing experiences between different severity difficult. All studies met the majority of the quality assessment items. Six descriptive themes emerged discussing participant’s experiences of diagnosis, treatment, prognosis, healthcare professionals, impact and coping with pulmonary hypertension. Four higher order analytical themes were developed from the descriptive themes, reflecting: (i) uncertainties and anxiety that participants encountered related to pulmonary hypertension; (ii) lack of recognition of the impact of the condition; (iii) frustration at the paucity of awareness of pulmonary hypertension in society and healthcare settings and (iv) participant’s accounts of transitioning through different stages of living with the disease. Conclusions These findings form the first synthesis of experiences of life in individuals impacted by pulmonary hypertension and illustrate the multifaceted impact of the condition. The voices of numerous groups are missing from the literature highlighting the need for additional research. The results have implications for clinical practice emphasising the role of educational and psychological therapies to support those with the disease

The influence of individual cognitive style on performance in management education

This paper reports the outcomes of an empirical study undertaken to explore the possibility that cognitive style may be an important factor influencing performance on certain types of task in management education. Four hundred and twelve final-year undergraduate degree students studying management and business administration were tested using the Allinson-Hayes Cognitive Style Index. Their cognitive styles were then compared with assessment grades achieved for academic modules, the task categories of which were deemed to be consonant with either the wholist/intuitive or the analytic style of working. Overall ability defined by final degree grades was also tested against individuals’ cognitive styles. As expected, students whose dominant cognitive styles were analytic attained higher grades for long term solitary tasks involving careful planning and analysis of information. However, contrary to expectations, performance on tasks believed to be more suited to the wholist/intuitive style was also higher for analytic individuals, as was overall ability defined by final degree grades. The results were discussed in terms of the nature of the tasks and the need for methods of performance assessment that are independent of an orientation bias. Without this, it is argued, employment selection criteria may favour the wrong type of candidate in some circumstances

Initial experience of an investigational 3T MR scanner designed for use on neonatal wards

OBJECTIVES: MR imaging of neonates is difficult for many reasons and a major factor is safe transport to the MR facilities. In this article we describe the use of a small, investigational 3-T MR customised for brain imaging and sited on a neonatal unit of a tertiary centre in the UK, which is in contrast to a 300-m journey to the whole-body MR scanner used at present for clinical cases. METHODS: We describe our methods for preparing babies for safe transport and scanning on an investigational 3-T MR scanner on a neonatal unit and the development of appropriate MR sequences. The MR scanner does not have CE marking at present so this early development work was undertaken on normal neonates whose parents consented to a research examination. RESULTS: Fifty-two babies were scanned and there were no serious adverse events. The MR examinations were considered to be diagnostically evaluable in all 52 cases and in 90% the imaging was considered to be at least as good as the quality obtained on the 1.5-T scanner currently used for clinical cases. CONCLUSION: We have shown that this investigational 3-T MR scanner can be used safely on a neonatal unit and we have refined the MR sequences to a point that they are clinically usable. KEY POINTS: • Access to neonatal MR imaging is limited. • We describe an investigational 3-T MR scanner site on a neonatal unit. • The scanner produces images suitable for clinical practice