Model Shuttle Vehicle Developed To Support Vandenberg Hydrogen Disposal Investigation

Space Shuttle Main Engines (SSME) discharge a significant quantity of unburned hydrogen during normal start and shutdown operations. At Vandenberg Air Force Base (VAFB), a Flight Readiness Firing (FRF) or launch abort could introduce this unburned hydrogen into the enclosed SSME exhaust duct. This hydrogen in a closed duct creates a risk of detonation which could result in significant overpressure at the aft heat shield thereby causing damage to the Space Shuttle Vehicle (SSV). To mitigate the detonation hazard the Air Force (AF) initiated a Hydrogen Disposal System (HDS) program. Extensive analyses and feasibility testing were conducted on possible solutions. In December 1986 the AF Shuttle Test Group (STG) selected the Steam Inerting System (SIS) concept as the most technically feasible resolution to the unburned hydrogen issue. The following January, STG directed the Shuttle Processing Contractor (SPC) to complete the development and design of a SIS for the VAFB SSV launch pad (Refs. A & B)

Modeling and Assessment of Afterglow Decay Curves from Thermally Stimulated Luminescence of Complex Garnets

Post-print (lokagerð höfundar)Afterglow is an important phenomenon in luminescent materials and can be desired (e.g., persistent phosphors) or undesired (e.g., scintillators). Understanding and predicting afterglow is often based on analysis of thermally stimulated luminescence (TSL) glow curves, assuming the presence of one or more discrete trap states. Here we present a new approach for the description of the time-dependent afterglow from TSL glow curves using a model with a distribution of trap depths. The method is based on the deconvolution of the energy dependent density of occupied traps derived from TSL glow curves using Tikhonov regularization. To test the validity of this new approach, the procedure is applied to experimental TSL and afterglow data for Lu1Gd2Ga3Al2O12:Ce ceramics codoped with 40 ppm of Yb3+ or Eu3+ traps. The experimentally measured afterglow curves are compared with simulations based on models with and without the continuous trap depth distribution. The analysis clearly demonstrates the presence of a distribution of trap depths and shows that the new approach gives a more accurate description of the experimentally observed afterglow. The new method will be especially useful in understanding and reducing undesired afterglow in scintillators.I.I.V, R.G.P and I.A.S. acknowledge support support from the Projects 14.Y26.31.0015 and 3.8884.2017/8.9 of the Ministry of Education and Science of the Russian Federation and Horizon2020 RISE project CoExAN.Peer Reviewe

Diabetes self-management arrangements in Europe: a realist review to facilitate a project implemented in six countries

Background: Self-management of long term conditions can promote quality of life whilst delivering benefits to the financing of health care systems. However, rarely are the meso-level influences, likely to be of direct relevance to these desired outcomes, systematically explored. No specific international guidelines exist suggesting the features of the most appropriate structure and organisation of health care systems within which to situate self-management approaches and practices. This review aimed to identify the quantitative literature with regard to diabetes self-management arrangements currently in place within the health care systems of six countries (The United Kingdom, The Netherlands, Norway, Spain, Bulgaria, and Greece) and explore how these are integrated into the broader health care and welfare systems in each country. Methods: The methodology for a realist review was followed. Publications of interest dating from 2000 to 2013 were identified through appropriate MeSH terms by a systematic search in six bibliographic databases. A search diary was maintained and the studies were assessed for their quality and risk of bias. Results: Following the multi-step search strategy, 56 studies were included in the final review (the majority from the UK) reporting design methods and findings on 21 interventions and programmes for diabetes and chronic disease self-management. Most (11/21, 52%) of the interventions were designed to fit within the context of primary care. The majority (11/21, 52%) highlighted behavioural change as an important goal. Finally, some (5/21, 24%) referred explicitly to Internet-based tools. Conclusions: This review is based on results which are derived from a total of at least 5,500 individuals residing in the six participating countries. It indicates a policy shift towards patient-centred self-management of diabetes in a primary care context. The professional role of diabetes specialist nurses, the need for multidisciplinary approaches and a focus on patient education emerge as fundamental principles in the design of relevant programmes. Socio-economic circumstances are relevant to the capacity to self-manage and suggest that any gains and progress will be hard to maintain during economic austerity. This realist review should be interpreted within the wider context of a whole systems approach regarding self-care support and chronic illness management

Creative destruction in science

Drawing on the concept of a gale of creative destruction in a capitalistic economy, we argue that initiatives to assess the robustness of findings in the organizational literature should aim to simultaneously test competing ideas operating in the same theoretical space. In other words, replication efforts should seek not just to support or question the original findings, but also to replace them with revised, stronger theories with greater explanatory power. Achieving this will typically require adding new measures, conditions, and subject populations to research designs, in order to carry out conceptual tests of multiple theories in addition to directly replicating the original findings. To illustrate the value of the creative destruction approach for theory pruning in organizational scholarship, we describe recent replication initiatives re-examining culture and work morality, working parents\u2019 reasoning about day care options, and gender discrimination in hiring decisions. Significance statement It is becoming increasingly clear that many, if not most, published research findings across scientific fields are not readily replicable when the same method is repeated. Although extremely valuable, failed replications risk leaving a theoretical void\u2014 reducing confidence the original theoretical prediction is true, but not replacing it with positive evidence in favor of an alternative theory. We introduce the creative destruction approach to replication, which combines theory pruning methods from the field of management with emerging best practices from the open science movement, with the aim of making replications as generative as possible. In effect, we advocate for a Replication 2.0 movement in which the goal shifts from checking on the reliability of past findings to actively engaging in competitive theory testing and theory building. Scientific transparency statement The materials, code, and data for this article are posted publicly on the Open Science Framework, with links provided in the article

Modeling and Assessment of Afterglow Decay Curves from Thermally Stimulated Luminescence of Complex Garnets

Afterglow is an important phenomenon in luminescent materials and can be desired (e.g., persistent phosphors) or undesired (e.g., scintillators). Understanding and predicting afterglow is often based on analysis of thermally stimulated luminescence (TSL) glow curves, assuming the presence of one or more discrete trap states. Here we present a new approach for the description of the time-dependent afterglow from TSL glow curves using a model with a distribution of trap depths. The method is based on the deconvolution of the energy dependent density of occupied traps derived from TSL glow curves using Tikhonov regularization. To test the validity of this new approach, the procedure is applied to experimental TSL and afterglow data for Lu 1 Gd 2 Ga 3 Al 2 O 12 :Ce ceramics codoped with 40 ppm of Yb 3+ or Eu 3+ traps. The experimentally measured afterglow curves are compared with simulations based on models with and without the continuous trap depth distribution. The analysis clearly demonstrates the presence of a distribution of trap depths and shows that the new approach gives a more accurate description of the experimentally observed afterglow. The new method will be especially useful in understanding and reducing undesired afterglow in scintillators

Complex Garnets : Microscopic Parameters Characterizing Afterglow

Light yield, time response, afterglow, and thermoluminescence of Ce-doped garnet scintillators and persistent luminescent materials are controlled by a complex interplay between recombination and trapping/detrapping processes. Extensive research has contributed to a good qualitative understanding of how traps, impurities, and the presence of Ce4+ affect the materials properties. In this work we present a quantitative model that can explain the thermoluminescence and afterglow behavior of complex garnets. In particular, the model allows the determination of capture rates and effective capture radii for electrons by traps and recombination centers in Lu1Gd2Ga3Al2O12:Ce garnet ceramics. The model relies on solving a set of coupled rate equations describing charge carrier trapping and recombination in garnet ceramics doped with Ce and also codoped with a known concentration of an intentionally added electron trap, Yb3+. The model is supported by analysis of a complete set of experimental data on afterglow, rise-time kinetics, and X-ray excited luminescence which show that thermoluminescence/afterglow are governed by trapping/detrapping processes following interactive kinetics with dominant recombination channel. The underlying reason for dominant recombination is the presence of a small fraction of Ce4+ (≈2 ppm in the 0.2% Ce-doped sample) which have a very high capture cross section (≈2.7 Å effective radius) because of the Coulomb attractive nature of this recombination center. The quantitative insights on capture cross sections and concentrations of Ce4+ help to better understand the optical properties of Ce-doped garnet scintillators and persistent luminescent materials and serve in optimizing synthesis procedures by tuning the Ce3+/Ce4+ ratio by codoping with divalent cations and annealing in an oxygen-containing atmosphere

Complex Garnets : Microscopic Parameters Characterizing Afterglow

Light yield, time response, afterglow, and thermoluminescence of Ce-doped garnet scintillators and persistent luminescent materials are controlled by a complex interplay between recombination and trapping/detrapping processes. Extensive research has contributed to a good qualitative understanding of how traps, impurities, and the presence of Ce4+ affect the materials properties. In this work we present a quantitative model that can explain the thermoluminescence and afterglow behavior of complex garnets. In particular, the model allows the determination of capture rates and effective capture radii for electrons by traps and recombination centers in Lu1Gd2Ga3Al2O12:Ce garnet ceramics. The model relies on solving a set of coupled rate equations describing charge carrier trapping and recombination in garnet ceramics doped with Ce and also codoped with a known concentration of an intentionally added electron trap, Yb3+. The model is supported by analysis of a complete set of experimental data on afterglow, rise-time kinetics, and X-ray excited luminescence which show that thermoluminescence/afterglow are governed by trapping/detrapping processes following interactive kinetics with dominant recombination channel. The underlying reason for dominant recombination is the presence of a small fraction of Ce4+ (≈2 ppm in the 0.2% Ce-doped sample) which have a very high capture cross section (≈2.7 Å effective radius) because of the Coulomb attractive nature of this recombination center. The quantitative insights on capture cross sections and concentrations of Ce4+ help to better understand the optical properties of Ce-doped garnet scintillators and persistent luminescent materials and serve in optimizing synthesis procedures by tuning the Ce3+/Ce4+ ratio by codoping with divalent cations and annealing in an oxygen-containing atmosphere

A metasynthesis of qualitative studies regarding opinions and perceptions about barriers and determinants of health services’ accessibility in economic migrants

Background: Access to health services is an important health determinant. New research in health equity is required, especially amongst economic migrants from developing countries. Studies conducted on the use of health services by migrant populations highlight existing gaps in understanding which factors affect access to these services from a qualitative perspective. We aim to describe the views of the migrants regarding barriers and determinants of access to health services in the international literature (1997–2011). Methods: A systematic review was conducted for Qualitative research papers (English/Spanish) published in 13 electronic databases. A selection of articles that accomplished the inclusion criteria and a quality evaluation of the studies were carried out. The findings of the selected studies were synthesised by means of metasynthesis using different analysis categories according to Andersen’s conceptual framework of access and use of health services and by incorporating other emergent categories. Results: We located 3,025 titles, 36 studies achieved the inclusion criteria. After quality evaluation, 28 articles were definitively synthesised. 12 studies (46.2%) were carried out in the U.S and 11 studies (42.3%) dealt with primary care services. The participating population varied depending mainly on type of host country. Barriers were described, such as the lack of communication between health services providers and migrants, due to idiomatic difficulties and cultural differences. Other barriers were linked to the economic system, the health service characteristics and the legislation in each country. This situation has consequences for the lack of health control by migrants and their social vulnerability. Conclusions: Economic migrants faced individual and structural barriers to the health services in host countries, especially those with undocumented situation and those experimented idiomatic difficulties. Strategies to improve the structures of health systems and social policies are needed.Carolina Foundation (Spain), Mario Benedetti Foundation of the University of Alicante, Regional Ministry of Education (Generalitat Valenciana) (BEST/2009/003). Healthcare Research Fund of the Spanish Ministry of Health and Social Policy (PI 0790470)

Cognitive and psychiatric symptom trajectories 2–3 years after hospital admission for COVID-19: a longitudinal, prospective cohort study in the UK

Background: COVID-19 is known to be associated with increased risks of cognitive and psychiatric outcomes after the acute phase of disease. We aimed to assess whether these symptoms can emerge or persist more than 1 year after hospitalisation for COVID-19, to identify which early aspects of COVID-19 illness predict longer-term symptoms, and to establish how these symptoms relate to occupational functioning. Methods: The Post-hospitalisation COVID-19 study (PHOSP-COVID) is a prospective, longitudinal cohort study of adults (aged ≥18 years) who were hospitalised with a clinical diagnosis of COVID-19 at participating National Health Service hospitals across the UK. In the C-Fog study, a subset of PHOSP-COVID participants who consented to be recontacted for other research were invited to complete a computerised cognitive assessment and clinical scales between 2 years and 3 years after hospital admission. Participants completed eight cognitive tasks, covering eight cognitive domains, from the Cognitron battery, in addition to the 9-item Patient Health Questionnaire for depression, the Generalised Anxiety Disorder 7-item scale, the Functional Assessment of Chronic Illness Therapy Fatigue Scale, and the 20-item Cognitive Change Index (CCI-20) questionnaire to assess subjective cognitive decline. We evaluated how the absolute risks of symptoms evolved between follow-ups at 6 months, 12 months, and 2–3 years, and whether symptoms at 2–3 years were predicted by earlier aspects of COVID-19 illness. Participants completed an occupation change questionnaire to establish whether their occupation or working status had changed and, if so, why. We assessed which symptoms at 2–3 years were associated with occupation change. People with lived experience were involved in the study. Findings: 2469 PHOSP-COVID participants were invited to participate in the C-Fog study, and 475 participants (191 [40·2%] females and 284 [59·8%] males; mean age 58·26 [SD 11·13] years) who were discharged from one of 83 hospitals provided data at the 2–3-year follow-up. Participants had worse cognitive scores than would be expected on the basis of their sociodemographic characteristics across all cognitive domains tested (average score 0·71 SD below the mean [IQR 0·16–1·04]; p<0·0001). Most participants reported at least mild depression (263 [74·5%] of 353), anxiety (189 [53·5%] of 353), fatigue (220 [62·3%] of 353), or subjective cognitive decline (184 [52·1%] of 353), and more than a fifth reported severe depression (79 [22·4%] of 353), fatigue (87 [24·6%] of 353), or subjective cognitive decline (88 [24·9%] of 353). Depression, anxiety, and fatigue were worse at 2–3 years than at 6 months or 12 months, with evidence of both worsening of existing symptoms and emergence of new symptoms. Symptoms at 2–3 years were not predicted by the severity of acute COVID-19 illness, but were strongly predicted by the degree of recovery at 6 months (explaining 35·0–48·8% of the variance in anxiety, depression, fatigue, and subjective cognitive decline); by a biocognitive profile linking acutely raised D-dimer relative to C-reactive protein with subjective cognitive deficits at 6 months (explaining 7·0–17·2% of the variance in anxiety, depression, fatigue, and subjective cognitive decline); and by anxiety, depression, fatigue, and subjective cognitive deficit at 6 months. Objective cognitive deficits at 2–3 years were not predicted by any of the factors tested, except for cognitive deficits at 6 months, explaining 10·6% of their variance. 95 of 353 participants (26·9% [95% CI 22·6–31·8]) reported occupational change, with poor health being the most common reason for this change. Occupation change was strongly and specifically associated with objective cognitive deficits (odds ratio [OR] 1·51 [95% CI 1·04–2·22] for every SD decrease in overall cognitive score) and subjective cognitive decline (OR 1·54 [1·21–1·98] for every point increase in CCI-20). Interpretation: Psychiatric and cognitive symptoms appear to increase over the first 2–3 years post-hospitalisation due to both worsening of symptoms already present at 6 months and emergence of new symptoms. New symptoms occur mostly in people with other symptoms already present at 6 months. Early identification and management of symptoms might therefore be an effective strategy to prevent later onset of a complex syndrome. Occupation change is common and associated mainly with objective and subjective cognitive deficits. Interventions to promote cognitive recovery or to prevent cognitive decline are therefore needed to limit the functional and economic impacts of COVID-19. Funding: National Institute for Health and Care Research Oxford Health Biomedical Research Centre, Wolfson Foundation, MQ Mental Health Research, MRC-UK Research and Innovation, and National Institute for Health and Care Research.</p