95 research outputs found

    Ion Heating and Current and Momentum profile Relaxation During Sawtooth Crashes in the MST Reversed Field Pinch.

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    Very robust and global phenomena associated with sawtooth crashes are studied in a reversed field pinch plasma. These phenomena are: anomalous ion heating, current profile relaxation, and plasma momentum profile relaxation. We have implemented new sophisticated diagnostics to characterize these processes with good spatial and temporal resolution. The majority ion temperature is measured with the Rutherford scattering diagnostic and the minority ion temperature is measured with charge exchange recombination spectroscopy. At the sawtooth crash the ion temperature almost doubles and a significant fraction of the equilibrium magnetic field energy is transferred into the ion thermal energy. The profile of the parallel current (inferred via laser polarimetry) flattens after the sawtooth crash which provides the most complete evidence of plasma relaxation toward a Taylor state. At the sawtooth crash we observe transport and relaxation both of the plasma toroidal and parallel momentum. The flattening of the parallel plasma momentum profile is in a good agreement with the theoretical predictions of two-fluid MHD

    Measuring the tail of the dog that doesn't bark in the night: the case of the national evaluation of Choose Life (the national strategy and action plan to prevent suicide in Scotland)

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    <p><b>Background:</b> Learning about the impact of public health policy presents significant challenges for evaluators. These include the nebulous and organic nature of interventions ensuing from policy directives, the tension between long-term goals and short-term interventions, the appropriateness of establishing control groups, and the problems of providing an economic perspective. An example of contemporary policy that has recently been subject to evaluation is the first phase of the innovative Scottish strategy for suicide prevention (Choose Life).</p> <p><b>Discussion and summary:</b> This paper discusses how challenges, such as those above, were made manifest within this programme. After a brief summary of the overarching approach taken to evaluating the first phase of Choose Life, this paper then offers a set of recommendations for policymakers and evaluators on how learning from a second phase might be augmented. These recommendations are likely to have general resonance across a range of policy evaluations as they move from early planning and implementation to more mature phases. </p&gt

    "We're not short of people telling us what the problems are. We're short of people telling us what to do": An appraisal of public policy and mental health

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    Background: There is sustained interest in public health circles in assessing the effects of policies on health and health inequalities. We report on the theory, methods and findings of a project which involved an appraisal of current Scottish policy with respect to its potential impacts on mental health and wellbeing. Methods: We developed a method of assessing the degree of alignment between Government policies and the 'evidence base', involving: reviewing theoretical frameworks; analysis of policy documents, and nineteen in-depth interviews with policymakers which explored influences on, and barriers to cross-cutting policymaking and the use of research evidence in decisionmaking. Results: Most policy documents did not refer to mental health; however most referred indirectly to the determinants of mental health and well-being. Unsurprisingly research evidence was rarely cited; this was more common in health policy documents. The interviews highlighted the barriers to intersectoral policy making, and pointed to the relative value of qualitative and quantitative research, as well as to the imbalance of evidence between "what is known" and "what is to be done". Conclusion: Healthy public policy depends on effective intersectoral working between government departments, along with better use of research evidence to identify policy impacts. This study identified barriers to both these. We also demonstrated an approach to rapidly appraising the mental health effects of mainly non-health sector policies, drawing on theoretical understandings of mental health and its determinants, research evidence and policy documents. In the case of the social determinants of health, we conclude that an evidence-based approach to policymaking and to policy appraisal requires drawing strongly upon existing theoretical frameworks, as well as upon research evidence, but that there are significant practical barriers and disincentives

    Transport studies of the itinerant metamagnet Sr₃Ru₂O₇ near its quantum critical point

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    Strongly correlated metals are known to give rise to a variety of exotic states. In particular, if a system is tuned towards a quantum critical point, new ordered phases may arise. Sr₃Ru₂O₇ is a quasi-two dimensional metal in which field-tuned quantum criticality has been observed. In very pure single crystals of this material, a phase with unusual transport properties forms in the vicinity of its quantum critical point. Upon the application of a small in-plane field, electrical resistivity becomes anisotropic, a phenomenon which has led to the naming of this phase as an `electron nematic'. The subject of this thesis is a study of the electrical transport in high purity crystals of Sr₃Ru₂O₇. We modified an adiabatic demagnetisation refrigerator to create the conditions by which the entire temperature-field phase diagram can be explored. In particular, this allowed us to access the crossover between the low-temperature Fermi liquid and the quantum critical region. We also installed a triple axis `vector magnet' with which the applied magnetic field vector can be continuously rotated within the anisotropic phase. We conclude that the low- and high-field Fermi liquid properties have a complex dependence on magnetic field and temperature, but that a simple multiple band model can account for some of these effects, and reconcile the measured specific heat, dHvA quasiparticle masses and transport co-efficients. At high temperatures, we observe similarities between the apparent resistive scattering rate at critical tuning and those observed in other quantum critical systems and in elemental metals. Finally, the anisotropic phase measurements confirm previous reports and demonstrate behaviour consistent with an Ising-nematic, with the anisotropy aligned along either of the principal crystal axes. Our observations are consistent with the presence of a large number of domains within the anisotropic phase, and conclude that scattering from domain walls is likely to contribute strongly to the large measured anisotropy

    Overview of the Instrumentation for the Dark Energy Spectroscopic Instrument

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    Full list of authors: Abareshi, B.; Aguilar, J.; Ahlen, S.; Alam, Shadab; Alexander, David M.; Alfarsy, R.; Allen, L.; Allende Prieto, C.; Alves, O.; Ameel, J.; Armengaud, E.; Asorey, J.; Aviles, Alejandro; Bailey, S.; Balaguera-Antolinez, A.; Ballester, O.; Baltay, C.; Bault, A.; Beltran, S. F.; Benavides, B.; BenZvi, S.; Berti, A.; Besuner, R.; Beutler, Florian; Bianchi, D.; Blake, C.; Blanc, P.; Blum, R.; Bolton, A.; Bose, S.; Bramall, D.; Brieden, S.; Brodzeller, A.; Brooks, D.; Brownewell, C.; Buckley-Geer, E.; Cahn, R. N.; Cai, Z.; Canning, R.; Capasso, R.; Carnero Rosell, A.; Carton, P.; Casas, R.; Castander, F. J.; Cervantes-Cota, J. L.; Chabanier, S.; Chaussidon, E.; Chuang, C.; Circosta, C.; Cole, S.; Cooper, A. P.; da Costa, L.; Cousinou, M-C; Cuceu, A.; Davis, T. M.; Dawson, K.; De la Cruz-Noriega, R.; de la Macorra, A.; de Mattia, A.; Della Costa, J.; Demmer, P.; Derwent, M.; Dey, A.; Dey, B.; Dhungana, G.; Ding, Z.; Dobson, C.; Doel, P.; Donald-McCann, J.; Donaldson, J.; Douglass, K.; Duan, Y.; Dunlop, P.; Edelstein, J.; Eftekharzadeh, S.; Eisenstein, D. J.; Enriquez-Vargas, M.; Escoffier, S.; Evatt, M.; Fagrelius, P.; Fan, X.; Fanning, K.; Fawcett, V. A.; Ferraro, S.; Ereza, J.; Flaugher, B.; Font-Ribera, A.; Forero-Romero, J. E.; Frenk, C. S.; Fromenteau, S.; Gansicke, B. T.; Garcia-Quintero, C.; Garrison, L.; Gaztanaga, E.; Gerardi, F.; Gil-Marin, H.; Gontcho, S. Gontcho A.; Gonzalez-Morales, Alma X.; Gonzalez-de-Rivera, G.; Gonzalez-Perez, V; Gordon, C.; Graur, O.; Green, D.; Grove, C.; Gruen, D.; Gutierrez, G.; Guy, J.; Hahn, C.; Harris, S.; Herrera, D.; Herrera-Alcantar, Hiram K.; Honscheid, K.; Howlett, C.; Huterer, D.; Irsic, V; Ishak, M.; Jelinsky, P.; Jiang, L.; Jimenez, J.; Jing, Y. P.; Joyce, R.; Jullo, E.; Juneau, S.; Karacayli, N. G.; Karamanis, M.; Karcher, A.; Karim, T.; Kehoe, R.; Kent, S.; Kirkby, D.; Kisner, T.; Kitaura, F.; Koposov, S. E.; Kovacs, A.; Kremin, A.; Krolewski, Alex; L'Huillier, B.; Lahav, O.; Lambert, A.; Lamman, C.; Lan, Ting-Wen; Landriau, M.; Lane, S.; Lang, D.; Lange, J. U.; Lasker, J.; Le Guillou, L.; Leauthaud, A.; Suu, A. Le Van; Levi, Michael E.; Li, T. S.; Magneville, C.; Manera, M.; Manser, Christopher J.; Marshall, B.; Martini, Paul; McCollam, W.; McDonald, P.; Meisner, Aaron M.; Mena-Fernandez, J.; Meneses-Rizo, J.; Mezcua, M.; Miller, T.; Miquel, R.; Montero-Camacho, P.; Moon, J.; Moustakas, J.; Mueller, E.; Munoz-Gutierrez, Andrea; Myers, Adam D.; Nadathur, S.; Najita, J.; Napolitano, L.; Neilsen, E.; Newman, Jeffrey A.; Nie, J. D.; Ning, Y.; Niz, G.; Norberg, P.; Noriega, Hernan E.; O'Brien, T.; Obuljen, A.; Palanque-Delabrouille, N.; Palmese, A.; Zhiwei, P.; Pappalardo, D.; Peng, X.; Percival, W. J.; Perruchot, S.; Pogge, R.; Poppett, C.; Porredon, A.; Prada, F.; Prochaska, J.; Pucha, R.; Perez-Fernandez, A.; Perez-Rafols, I; Rabinowitz, D.; Raichoor, A.; Ramirez-Solano, S.; Ramirez-Perez, Cesar; Ravoux, C.; Reil, K.; Rezaie, M.; Rocher, A.; Rockosi, C.; Roe, N. A.; Roodman, A.; Ross, A. J.; Rossi, G.; Ruggeri, R.; Ruhlmann-Kleider, V; Sabiu, C. G.; Safonova, S.; Said, K.; Saintonge, A.; Catonga, Javier Salas; Samushia, L.; Sanchez, E.; Saulder, C.; Schaan, E.; Schlafly, E.; Schlegel, D.; Schmoll, J.; Scholte, D.; Schubnell, M.; Secroun, A.; Seo, H.; Serrano, S.; Sharples, Ray M.; Sholl, Michael J.; Silber, Joseph Harry; Silva, D. R.; Sirk, M.; Siudek, M.; Smith, A.; Sprayberry, D.; Staten, R.; Stupak, B.; Tan, T.; Tarle, Gregory; Tie, Suk Sien; Tojeiro, R.; Urena-Lopez, L. A.; Valdes, F.; Valenzuela, O.; Valluri, M.; Vargas-Magana, M.; Verde, L.; Walther, M.; Wang, B.; Wang, M. S.; Weaver, B. A.; Weaverdyck, C.; Wechsler, R.; Wilson, Michael J.; Yang, J.; Yu, Y.; Yuan, S.; Yeche, Christophe; Zhang, H.; Zhang, K.; Zhao, Cheng; Zhou, Rongpu; Zhou, Zhimin; Zou, H.; Zou, J.; Zou, S.; Zu, Y.; DESI Collaboration.--This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited.The Dark Energy Spectroscopic Instrument (DESI) embarked on an ambitious 5 yr survey in 2021 May to explore the nature of dark energy with spectroscopic measurements of 40 million galaxies and quasars. DESI will determine precise redshifts and employ the baryon acoustic oscillation method to measure distances from the nearby universe to beyond redshift z > 3.5, and employ redshift space distortions to measure the growth of structure and probe potential modifications to general relativity. We describe the significant instrumentation we developed to conduct the DESI survey. This includes: a wide-field, 3fdg2 diameter prime-focus corrector; a focal plane system with 5020 fiber positioners on the 0.812 m diameter, aspheric focal surface; 10 continuous, high-efficiency fiber cable bundles that connect the focal plane to the spectrographs; and 10 identical spectrographs. Each spectrograph employs a pair of dichroics to split the light into three channels that together record the light from 360–980 nm with a spectral resolution that ranges from 2000–5000. We describe the science requirements, their connection to the technical requirements, the management of the project, and interfaces between subsystems. DESI was installed at the 4 m Mayall Telescope at Kitt Peak National Observatory and has achieved all of its performance goals. Some performance highlights include an rms positioner accuracy of better than 0farcs1 and a median signal-to-noise ratio of 7 of the [O ii] doublet at 8 × 10−17 erg s−1 cm−2 in 1000 s for galaxies at z = 1.4–1.6. We conclude with additional highlights from the on-sky validation and commissioning, key successes, and lessons learned. © 2022. The Author(s). Published by the American Astronomical Society.This research is supported by the Director, Office of Science, Office of High Energy Physics of the U.S. Department of Energy under contract No. DE-AC02-05CH11231, and by the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility under the same contract. Additional support for DESI is provided by the U.S. National Science Foundation, Division of Astronomical Sciences under contract No. AST-0950945 to the NSF's National Optical-Infrared Astronomy Research Laboratory; the Science and Technologies Facilities Council of the United Kingdom; the Gordon and Betty Moore Foundation; the Heising–Simons Foundation; the French Alternative Energies and Atomic Energy Commission (CEA); the National Council of Science and Technology of Mexico (CONACYT); the Ministry of Science and Innovation of Spain, and by the DESI Member Institutions: Aix-Marseille University; Argonne National Laboratory; Barcelona-Madrid Regional Participation Group; Brookhaven National Laboratory; Boston University; Brazil Regional Participation Group; Carnegie Mellon University; CEA-IRFU, Saclay; China Participation Group; Cornell University; Durham University; École Polytechnique Fédérale de Lausanne; Eidgenössische Technische Hochschule, Zürich; Fermi National Accelerator Laboratory; Granada-Madrid-Tenerife Regional Participation Group; Harvard University; Kansas State University; Korea Astronomy and Space Science Institute; Korea Institute for Advanced Study; Lawrence Berkeley National Laboratory; Laboratoire de Physique Nucléaire et de Hautes Energies; Ludwig Maximilians University; Max Planck Institute; Mexico Regional Participation Group; New York University; NSF's National Optical-Infrared Astronomy Research Laboratory; Ohio University; Perimeter Institute; Shanghai Jiao Tong University; Siena College; SLAC National Accelerator Laboratory; Southern Methodist University; Swinburne University; The Ohio State University; Universidad de los Andes; University of Arizona; University of Barcelona; University of California, Berkeley; University of California, Irvine; University of California, Santa Cruz; University College London; University of Florida; University of Michigan at Ann Arbor; University of Pennsylvania; University of Pittsburgh; University of Portsmouth; University of Queensland; University of Rochester; University of Toronto; University of Utah; University of Waterloo; University of Wyoming; University of Zurich; UK Regional Participation Group; and Yale University. This work has made use of data from the European Space Agency (ESA) mission Gaia (https://www.cosmos.esa.int/gaia), processed by the Gaia Data Processing and Analysis Consortium (DPAC; https://www.cosmos.esa.int/web/gaia/dpac/consortium). Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement.With funding from the Spanish government through the Severo Ochoa Centre of Excellence accreditation SEV-2017-0709.Peer reviewe

    The Warwick-Edinburgh Mental Well-being Scale (WEMWBS) : development and UK validation

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    Background There is increasing international interest in the concept of mental well-being and its contribution to all aspects of human life. Demand for instruments to monitor mental well-being at a population level and evaluate mental health promotion initiatives is growing. This article describes the development and validation of a new scale, comprised only of positively worded items relating to different aspects of positive mental health: the Warwick-Edinburgh Mental Well-Being Scale (WEMWBS). Methods WEMWBS was developed by an expert panel drawing on current academic literature, qualitative research with focus groups, and psychometric testing of an existing scale. It was validated on a student and representative population sample. Content validity was assessed by reviewing the frequency of complete responses and the distribution of responses to each item. Confirmatory factor analysis was used to test the hypothesis that the scale measured a single construct. Internal consistency was assessed using Cronbach's alpha. Criterion validity was explored in terms of correlations between WEMWBS and other scales and by testing whether the scale discriminated between population groups in line with pre-specified hypotheses. Test-retest reliability was assessed at one week using intra-class correlation coefficients. Susceptibility to bias was measured using the Balanced Inventory of Desired Responding. Results WEMWBS showed good content validity. Confirmatory factor analysis supported the single factor hypothesis. A Cronbach's alpha score of 0.89 (student sample) and 0.91 (population sample) suggests some item redundancy in the scale. WEMWBS showed high correlations with other mental health and well-being scales and lower correlations with scales measuring overall health. Its distribution was near normal and the scale did not show ceiling effects in a population sample. It discriminated between population groups in a way that is largely consistent with the results of other population surveys. Test-retest reliability at one week was high (0.83). Social desirability bias was lower or similar to that of other comparable scales. Conclusion WEMWBS is a measure of mental well-being focusing entirely on positive aspects of mental health. As a short and psychometrically robust scale, with no ceiling effects in a population sample, it offers promise as a tool for monitoring mental well-being at a population level. Whilst WEMWBS should appeal to those evaluating mental health promotion initiatives, it is important that the scale's sensitivity to change is established before it is recommended in this context
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