2,013 research outputs found

    Active current sheets and hot flow anomalies in Mercury's bow shock

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    Hot flow anomalies (HFAs) represent a subset of solar wind discontinuities interacting with collisionless bow shocks. They are typically formed when the normal component of motional (convective) electric field points toward the embedded current sheet on at least one of its sides. The core region of an HFA contains hot and highly deflected ion flows and rather low and turbulent magnetic field. In this paper, we report first observations of HFA-like events at Mercury identified over a course of two planetary years. Using data from the orbital phase of the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) mission, we identify a representative ensemble of active current sheets magnetically connected to Mercury's bow shock. We show that some of these events exhibit unambiguous magnetic and particle signatures of HFAs similar to those observed earlier at other planets, and present their key physical characteristics. Our analysis suggests that Mercury's bow shock does not only mediate the flow of supersonic solar wind plasma but also provides conditions for local particle acceleration and heating as predicted by previous numerical simulations. Together with earlier observations of HFA activity at Earth, Venus and Saturn, our results confirm that hot flow anomalies are a common property of planetary bow shocks, and show that the characteristic size of these events is of the order of one planetary radius.Comment: 39 pages, 15 figures, 2 table

    The occupational role of the lay health trainer in England: a review of practice

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    Health Trainers constitute an emergent occupational group in the Public Health system in England with the key purpose to reduce health inequalities by helping or ‘nudging’ people in local communities to adopt healthier lifestyles. Whilst primarily supplying health-related information and support regarding smoking cessation, diet, alcohol, physical activity and mental wellbeing issues, the role also requires awareness of, and sensitivity toward the specific needs of local communities. This literature review charts current research on the occupational context of the Health Trainer role since its implementation in the English Public Health system. It provides a critical examination of current literature whilst highlighting the theoretical basis of Health Trainers’ roles, the potential boundary-crossing nature of their work, along with professional development issues

    Twisting type-N vacuum fields with a group H2H_2

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    We derive the equations corresponding to twisting type-N vacuum gravitational fields with one Killing vector and one homothetic Killing vector by using the same approach as that developed by one of us in order to treat the case with two non-commuting Killing vectors. We study the case when the homothetic parameter ϕ\phi takes the value -1, which is shown to admit a reduction to a third-order real ordinary differential equation for this problem, similar to that previously obtained by one of us when two Killing vectors are present.Comment: LaTeX, 11 pages. To be published in Classical and Quantum Gravit

    The interaction between systemic inflammation and psychosocial stress in the association with cardiac troponin elevation: A new approach to risk assessment and disease prevention.

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    We have previously shown that there is a complex and dynamic biological interaction between acute mental stress and acute release of inflammatory factors into the blood stream in relation to heart disease. We now hypothesize that the presence of chronic psychosocial stress may modify the weight of single test results for inflammation as a predictor of heart disease. Using a cross-sectional design, 500 participants free from heart disease drawn from the Whitehall II study in UK in 2006-2008 were tested for plasma fibrinogen as an inflammatory factor, financial strain as a marker of chronic psychosocial stress, coronary calcification measured using computed tomography, and for plasma high-sensitivity cardiac troponin T (HS-CTnT) as a marker of cardiac risk. Fibrinogen concentration levels above the average were associated with a 5-fold increase in the odds of HS-CTnT positivity only among individuals with financial strain (N=208, OR=4.73, 95%CI=1.67 to 13.40, P=0.003). Fibrinogen was in fact not associated with HS-CTnT positivity in people without financial strain despite the larger size of that subsample (n=292, OR=0.84, 95%CI=0.42 to 1.67, P=0.622). A test for interaction on the full sample (N=500) showed a P value of 0.010 after adjusting for a range of demographics, health behaviours, traditional cardiovascular risk factors, psychosocial stressors, inflammatory cytokines, and coronary calcification. In conclusion, elevated fibrinogen seems to be cardio-toxic only when is combined with financial strain. Chronic psychosocial stress may modify the meaning that we should give to single test results for inflammation. Further research is needed to confirm our results

    Greening the transport sector by mainstreaming biodiversity

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    In late 2022, the UN CBD (Convention on Biological Diversity) will meet to adopt a post2020 global biodiversity framework which will detail how the private sector should mainstream biodiversity into its business strategies, investments, and production systems. The mainstreaming of biodiversity has lagged behind the carbon agenda, as evidenced in the Green Transport Strategy for South Africa. However, both voluntary and legislated corporate disclosures on biodiversity impact are increasing. The National Biodiversity and Business Network (NBBN) of South Africa assists corporates in understanding their dependencies and impacts on nature. We discuss the main impacts of transport on African biodiversity and present the results of the third, annual corporate biodiversity performance assessment of the Biodiversity Disclosure Project. For 2020, 327 JSE-listed companies and 27 State-Owned Enterprises (SOEs) were involved. The results showed that the private sector, including transport, is illequipped to achieve science-based targets and invest in biodiversity. We briefly outline emerging measurement standards for the transport sector to become greener, not only in energy, but biodiversity. This includes setting targets which are based on footprint accounting, thereby contributing to the Sustainable Development Goals.Papers presented at the 40th International Southern African Transport Conference on 04 -08 July 202

    'Working out’ identity: distance runners and the management of disrupted identity

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    This article contributes fresh perspectives to the empirical literature on the sociology of the body, and of leisure and identity, by analysing the impact of long-term injury on the identities of two amateur but serious middle/long-distance runners. Employing a symbolic interactionist framework,and utilising data derived from a collaborative autoethnographic project, it explores the role of ‘identity work’ in providing continuity of identity during the liminality of long-term injury and rehabilitation, which poses a fundamental challenge to athletic identity. Specifically, the analysis applies Snow and Anderson’s (1995) and Perinbanayagam’s (2000) theoretical conceptualisations in order to examine the various forms of identity work undertaken by the injured participants, along the dimensions of materialistic, associative and vocabularic identifications. Such identity work was found to be crucial in sustaining a credible sporting identity in the face of disruption to the running self, and in generating momentum towards the goal of restitution to full running fitness and reengagement with a cherished form of leisure. KEYWORDS: identity work, symbolic interactionism, distance running, disrupted identit

    The Embedding of Schwarzschild in Braneworld

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    The braneworlds models were inspired partly by Kaluza-Klein's theory, where both the gravitational and the gauge fields are obtained from the geometry of a higher dimensional space. The positive aspects of these models consist in perspectives of modifications it could bring in to particle physics, such as: unification in a TeV scale, quantum gravity in this scale and deviation of Newton's law for small distances. One of the principles of these models is to suppose that all space-times can be embedded in a bulk of higher dimension. The main result in these notes is a theorem showing a mathematical inconsistency of the Randall-Sundrum braneworld model, namely that the Schwarzschild space-time cannot be embedded locally and isometrically in a five dimensional bulk with constant curvature,(for example AdS-5). From the point of view of semi-Riemannian geometry this last result represents a serious restriction to the Randall-Sundrum's braneworld model.Comment: Published in the Int. J. Theor. Phys, 200

    Spacelike Ricci Inheritance Vectors in a Model of String Cloud and String Fluid Stress Tensor

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    We study the consequences of the existence of spacelike Ricci inheritance vectors (SpRIVs) parallel to xax^a for model of string cloud and string fluid stress tensor in the context of general relativity. Necessary and sufficient conditions are derived for a spacetime with a model of string cloud and string fluid stress tensor to admit a SpRIV and a SpRIV which is also a spacelike conformal Killing vector (SpCKV). Also, some results are obtained.Comment: 11 page

    New first integral for twisting type-N vacuum gravitational fields with two non-commuting Killing vectors

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    A new first integral for the equations corresponding to twisting type-N vacuum gravitational fields with two non-commuting Killing vectors is introduced. A new reduction of the problem to a complex second-order ordinary differential equation is given. Alternatively, the mentioned first integral can be used in order to provide a first integral of the second-order complex equation introduced in a previous treatment of the problem.Comment: 7 pages, LaTeX, uses ioplppt.sty and iopl12.sty; to be published in Class. Quantum Gra

    Feminist phenomenology and the woman in the running body

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    Modern phenomenology, with its roots in Husserlian philosophy, has been taken up and utilised in a myriad of ways within different disciplines, but until recently has remained relatively under-used within sports studies. A corpus of sociological-phenomenological work is now beginning to develop in this domain, alongside a longer standing literature in feminist phenomenology. These specific social-phenomenological forms explore the situatedness of lived-body experience within a particular social structure. After providing a brief overview of key strands of phenomenology, this article considers some of the ways in which sociological, and particularly feminist phenomenology, might be used to analyse female sporting embodiment. For illustrative purposes, data from an autophenomenographic project on female distance running are also included, in order briefly to demonstrate the application of phenomenology within sociology, as both theoretical framework and methodological approach
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