25,756 research outputs found
Prognostic variables and scores identifying the last year of life in COPD: a systematic review protocol
Introduction People living with advanced chronic obstructive pulmonary disease (COPD) suffer from significant morbidity, reduced quality of life and high mortality, and are likely to benefit from many aspects of a palliative care approach. Prognostic estimates are a meaningful part of decision-making and better evidence for such estimates would facilitate advance care planning. We aim to provide quality evidence on known prognostic variables and scores which predict a prognosis in COPD of <12 months for use in the community. Methods and analysis We will conduct a systematic review of randomised or quasi-randomised controlled trials, prospective and retrospective longitudinal cohort and case–control studies on prognostic variables, multivariate scores or models for COPD. The search will cover the period up to April 2016. Study selection will follow the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, with data extraction using fields from the Critical Appraisal and Data Extraction for Systematic Reviews of Prediction Modelling Studies (CHARMS) checklist for multivariate models, and study quality will be assessed using a modified version of the Quality In Prognosis Studies (QUIPS) tool. Ethics and dissemination The results will be disseminated through peer-reviewed publications and national and international conference presentations
Minimum Particle Size for Cyclone Dust Separator
Perkins technology wish to separate small soot particles from exhaust gases, and the question posed to the study group was to determine the feasibility of using a cyclone separator to remove these particles. Soot is mostly composed of polycyclicaromatic compounds and results from the incomplete combustion of the diesel fuel in the engine. The average size of the particles formed in the engine is in the range 3 to 10 nm in diameter, but this is known to increase within the exhaust system.
In the first part of this report we determine the minimum particle size that can be removed by centrifugal separation.
The second part discusses the mechanisms for particle growth within the exhaust system in order to estimate the particle growth rate.
In section two we estimate the minimum particle diameter that can be removed by a cyclone separator is around one micron. This estimate is consistent with current applications of hydrocyclones. The particle size measurements by Perkins Technology together with our estimates from section three, suggest that the soot particles are an order of magnitude smaller than this. Although it may be possible to remove some particles less than one micron in diameter with a well designed high-speed cyclone, we do not think it will be possible to remove a substantial proportion of 100 nm or smaller particles.
The growth rate of the particles increases if the particles volume fraction or the polydispersity is increased. Therefore aggregation could be enhanced by the addition of larger particles (d > 1 µm) or water droplets (provided the water does not all vapourise) to the exhaust gas
Hydrodynamical simulations of the decay of high-speed molecular turbulence. I. Dense molecular regions
We present the results from three dimensional hydrodynamical simulations of
decaying high-speed turbulence in dense molecular clouds. We compare our
results, which include a detailed cooling function, molecular hydrogen
chemistry and a limited C and O chemistry, to those previously obtained for
decaying isothermal turbulence.
After an initial phase of shock formation, power-law decay regimes are
uncovered, as in the isothermal case. We find that the turbulence decays faster
than in the isothermal case because the average Mach number remains higher, due
to the radiative cooling. The total thermal energy, initially raised by the
introduction of turbulence, decays only a little slower than the kinetic
energy.
We discover that molecule reformation, as the fast turbulence decays, is
several times faster than that predicted for a non-turbulent medium. This is
caused by moderate speed shocks which sweep through a large fraction of the
volume, compressing the gas and dust. Through reformation, the molecular
density and molecular column appear as complex patterns of filaments, clumps
and some diffuse structure. In contrast, the molecular fraction has a wider
distribution of highly distorted clumps and copious diffuse structure, so that
density and molecular density are almost identically distributed during the
reformation phase. We conclude that molecules form in swept-up clumps but
effectively mix throughout via subsequent expansions and compressions.Comment: 12 pages, 12 figures; For a version of the article with higher
resolution figures, see http://star.arm.ac.uk/preprints/381.p
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Strength, Weakness, Opportunity, Threat (SWOT) Analysis of the Adaptations to Anatomical Education in the United Kingdom and Republic of Ireland in Response to the Covid‐19 Pandemic
The Covid-19 pandemic has driven the fastest changes to higher education across the globe, necessitated by social distancing measures preventing any face to face teaching. This has led to an almost immediate switch to distance learning by higher education institutions. Anatomy faces some unique challenges. Intrinsically, anatomy is a three-dimensional subject that requires a sound understanding of the relationships between structures, often achieved by the study of human cadaveric material, models and virtual resources. This study sought to identify the approaches taken in the United Kingdom and Republic of Ireland to deliver anatomical education through online means. Data were collected from 14 different universities in the United Kingdom and Republic of Ireland and compared adopting a thematic analysis approach. Once themes were generated, they were collectively brought together using a strength, weakness, opportunity, threat (SWOT) analysis. Key themes included the opportunity to develop new online resources and the chance to engage in new academic collaborations. Academics frequently mentioned the challenge that time constrains could place on the quality and effectiveness of these resources; especially as in many cases the aim of these resources is to compensate for a lack of exposure to cadaveric exposure. Comparisons of the actions taken by multiple higher education institutions reveals the ways that academics have tried to balance this demand. Discussions will facilitate decisions being made by higher education institutions regarding adapting the curriculum and assessment methods in anatomy
Narrative, identity and mental health: How men with serious mental illness re-story their lives through sport and exercise
Objectives: It has been suggested that mental illness threatens identity and sense of self when one's personal story is displaced by dominant illness narratives focussing on deficit and dysfunction. One role of therapy, therefore, is to allow individuals to re-story their life in a more positive way which facilitates the reconstruction of a meaningful identity and sense of self. This research explores the ways in which involvement in sport and exercise may play a part in this process. Design: Qualitative analysis of narrative. Method: We used an interpretive approach which included semi-structured interviews and participant observation with 11 men with serious mental illness to gather stories of participants' sport and exercise experiences. We conducted an analysis of narrative to explore the more general narrative types which were evident in participants' accounts. Findings: We identified three narrative types underlying participants' talk about sport and exercise: (a) an action narrative about "going places and doing stuff"; (b) an achievement narrative about accomplishment through effort, skill or courage; (c) a relationship narrative of shared experiences to talk about combined with opportunities to talk about those experiences. We note that these narrative types differ significantly from-and may be considered alternatives to-dominant illness narratives. Conclusion: This study provides an alternative perspective on how sport and exercise can help men with serious mental illness by providing the narrative resources which enabled participants to re-story aspects of their lives through creating and sharing personal stories through which they rebuilt or maintained a positive sense of self and identity. © 2007 Elsevier Ltd. All rights reserved
The Wardle Instability in Interstellar Shocks: I. Nonlinear Dynamical Evolution
The nonlinear evolution of unstable C-type shocks in weakly ionized plasmas
is studied by means of time-dependent magnetohydrodynamical simulations. This
study is limited to shocks in magnetically dominated plasmas (in which the
Alfven speed in the neutrals greatly exceeds the sound speed), and
microphysical processes such as ionization and recombination are not followed.
Both two-dimensional simulations of planar perpendicular and oblique C-type
shocks, and fully three-dimensional simulation of a perpendicular shock are
presented.Comment: 20 pages, 7 Postscript figures, LaTeX, accepted by Ap.
Psychoeducational interventions in adolescent depression: A systematic review
Background:
Adolescent depression is common and leads to distress and impairment for individuals/families. Treatment/prevention guidelines stress the need for good information and evidence-based psychosocial interventions. There has been growing interest in psychoeducational interventions (PIs), which broadly deliver accurate information about health issues and self-management.
Objective, methods:
Systematic search of targeted PIs as part of prevention/management approaches for adolescent depression. Searches were undertaken independently in PubMed, PsycINFO, EMBASE, guidelines, reviews (including Cochrane), and reference lists. Key authors were contacted. No restrictions regarding publishing dates.
Results:
Fifteen studies were included: seven targeted adolescents with depression/depressive symptoms, eight targeted adolescents ‘at risk' e.g. with a family history of depression. Most involved family/group programmes; others included individual, school-based and online approaches. PIs may affect understanding of depression, identification of symptoms, communication, engagement, and mental health outcomes.
Conclusion, practice implications:
PIs can have a role in preventing/managing adolescent depression, as a first-line or adjunctive approach. The limited number of studies, heterogeneity in formats and evaluation, and inconsistent approach to defining PI, make it difficult to compare programmes and measure overall effectiveness. Further work needs to establish an agreed definition of PI, develop/evaluate PIs in line with frameworks for complex interventions, and analyse their active components
Optically tailored access to metastable electronic states
On irradiating a molecular system with a laser beam of ultraviolet or visible frequency, photon absorption occurs when an electronic state is at a suitable energy level relative to an initial state. Despite meeting this criterion, interesting metastable states can remain inaccessible because of symmetry constraints. In this Letter a mechanism, based on the input of an off-resonant beam, is shown to enable the population of such states. This is achievable because the laser-modified process involves different selection rules compared to conventional photon absorption. The effects of applying the stimulus beam to either a one- or two-photon process are examined
Experimental analysis of dynamic charge acceptance test conditions for lead-acid cells
© 2016 IEEE.This paper presents the results of a series of tests to determine the Dynamic Charge Acceptance (DCA) performance of small form-factor 2 V, 6 Ah, carbon-enhanced VRLA cells designed for Hybrid Electric Vehicle (HEV) applications. A test procedure has been written for a battery test system, based on a modified DCA Short Test profile. Results have been obtained for a batch of cells, tested at various temperatures, rest periods and states of charge. These conditions have been chosen to mimic a range of real-life scenarios which could potentially be encountered during HEV operation. The resulting analysis demonstrates clear variations and trends in DCA performance which may be used to inform conditions for future testing regimes. The same test procedure is then applied to standard lead-acid cells and the results compared
A non-metric perfectly normal hereditarily indecomposable continuum
AbstractWe construct an example of a non-metric perfectly normal hereditarily indecomposable continuum. The example is constructed as an inverse limit of non-metric analogues of solenoids. Theorems needed to insure perfect normality are stated and proven. It is shown that the example cannot be embedded in a countable product of Hausdorff arcs
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