851 research outputs found

    Thermocurrents and their Role in high Q Cavity Performance

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    Over the past years it became evident that the quality factor of a superconducting cavity is not only determined by its surface preparation procedure, but is also influenced by the way the cavity is cooled down. Moreover, different data sets exists, some of them indicate that a slow cool-down through the critical temperature is favourable while other data states the exact opposite. Even so there where speculations and some models about the role of thermo-currents and flux-pinning, the difference in behaviour remained a mystery. In this paper we will for the first time present a consistent theoretical model which we confirmed by data that describes the role of thermo-currents, driven by temperature gradients and material transitions. We will clearly show how they impact the quality factor of a cavity, discuss our findings, relate it to findings at other labs and develop mitigation strategies which especially addresses the issue of achieving high quality factors of so-called nitrogen doped cavities in horizontal test

    Between overt and covert research: concealment and disclosure in an ethnographic study of commercial hospitality

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    This article examines the ways in which problems of concealment emerged in an ethnographic study of a suburban bar and considers how disclosure of the research aims, the recruitment of informants, and elicitation of information was negotiated throughout the fieldwork. The case study demonstrates how the social context and the relationships with specific informants determined overtness or covertness in the research. It is argued that the existing literature on covert research and covert methods provides an inappropriate frame of reference with which to understand concealment in fieldwork. The article illustrates why concealment is sometimes necessary, and often unavoidable, and concludes that the criticisms leveled against covert methods should not stop the fieldworker from engaging in research that involves covertness

    Nuclei, Superheavy Nuclei and Hypermatter in a chiral SU(3)-Modell

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    A model based on chiral SU(3)-symmetry in nonlinear realisation is used for the investigation of nuclei, superheavy nuclei, hypernuclei and multistrange nuclear objects (so called MEMOs). The model works very well in the case of nuclei and hypernuclei with one Lambda-particle and rules out MEMOs. Basic observables which are known for nuclei and hypernuclei are reproduced satisfactorily. The model predicts Z=120 and N=172, 184 and 198 as the next shell closures in the region of superheavy nuclei. The calculations have been performed in self-consistent relativistic mean field approximation assuming spherical symmetry. The parameters were adapted to known nuclei.Comment: 19 pages, 11 figure

    A Study of Cosmic Ray Composition in the Knee Region using Multiple Muon Events in the Soudan 2 Detector

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    Deep underground muon events recorded by the Soudan 2 detector, located at a depth of 2100 meters of water equivalent, have been used to infer the nuclear composition of cosmic rays in the "knee" region of the cosmic ray energy spectrum. The observed muon multiplicity distribution favors a composition model with a substantial proton content in the energy region 800,000 - 13,000,000 GeV/nucleus.Comment: 38 pages including 11 figures, Latex, submitted to Physical Review

    The impacts of environmental warming on Odonata: a review

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    Climate change brings with it unprecedented rates of increase in environmental temperature, which will have major consequences for the earth's flora and fauna. The Odonata represent a taxon that has many strong links to this abiotic factor due to its tropical evolutionary history and adaptations to temperate climates. Temperature is known to affect odonate physiology including life-history traits such as developmental rate, phenology and seasonal regulation as well as immune function and the production of pigment for thermoregulation. A range of behaviours are likely to be affected which will, in turn, influence other parts of the aquatic ecosystem, primarily through trophic interactions. Temperature may influence changes in geographical distributions, through a shifting of species' fundamental niches, changes in the distribution of suitable habitat and variation in the dispersal ability of species. Finally, such a rapid change in the environment results in a strong selective pressure towards adaptation to cope and the inevitable loss of some populations and, potentially, species. Where data are lacking for odonates, studies on other invertebrate groups will be considered. Finally, directions for research are suggested, particularly laboratory studies that investigate underlying causes of climate-driven macroecological patterns

    Early and Middle Holocene Hunter-Gatherer Occupations in Western Amazonia: The Hidden Shell Middens

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    We report on previously unknown early archaeological sites in the Bolivian lowlands, demonstrating for the first time early and middle Holocene human presence in western Amazonia. Multidisciplinary research in forest islands situated in seasonally-inundated savannahs has revealed stratified shell middens produced by human foragers as early as 10,000 years ago, making them the oldest archaeological sites in the region. The absence of stone resources and partial burial by recent alluvial sediments has meant that these kinds of deposits have, until now, remained unidentified. We conducted core sampling, archaeological excavations and an interdisciplinary study of the stratigraphy and recovered materials from three shell midden mounds. Based on multiple lines of evidence, including radiocarbon dating, sedimentary proxies (elements, steroids and black carbon), micromorphology and faunal analysis, we demonstrate the anthropogenic origin and antiquity of these sites. In a tropical and geomorphologically active landscape often considered challenging both for early human occupation and for the preservation of hunter-gatherer sites, the newly discovered shell middens provide evidence for early to middle Holocene occupation and illustrate the potential for identifying and interpreting early open-air archaeological sites in western Amazonia. The existence of early hunter-gatherer sites in the Bolivian lowlands sheds new light on the region's past and offers a new context within which the late Holocene "Earthmovers" of the Llanos de Moxos could have emerged. © 2013 Lombardo et al

    Tools to overcome potential barriers to chlamydia screening in general practice: Qualitative evaluation of the implementation of a complex intervention

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    Background: Chlamydia trachomatis remains a significant public health problem. We used a complex intervention, with general practice staff, consisting of practice based workshops, posters, computer prompts and testing feedback and feedback to increase routine chlamydia screening tests in under 25 year olds in South West England. We aimed to evaluate how intervention components were received by staff and to understand what determined their implementation into ongoing practice. Methods: We used face-to-face and telephone individual interviews with 29 general practice staff analysed thematically within a Normalisation Process Theory Framework which explores: 1. Coherence (if participants understand the purpose of the intervention); 2. Cognitive participation (engagement with and implementation of the intervention); 3. Collective action (work actually undertaken that drives the intervention forwards); 4. Reflexive monitoring (assessment of the impact of the intervention). Results: Our results showed coherence as all staff including receptionists understood the purpose of the training was to make them aware of the value of chlamydia screening tests and how to increase this in their general practice. The training was described by nearly all staff as being of high quality and responsible for creating a shared understanding between staff of how to undertake routine chlamydia screening. Cognitive participation in many general practice staff teams was demonstrated through their engagement by meeting after the training to discuss implementation, which confirmed the role of each staff member and the use of materials. However several participants still felt unable to discuss chlamydia in many consultations or described sexual health as low priority among colleagues. National targets were considered so high for some general practice staff that they didn’t engage with the screening intervention. Collective action work undertaken to drive the intervention included use of computer prompts which helped staff remember to make the offer, testing rate feedback and having a designated lead. Ensuring patients collected samples when still in the general practice was not attained in most general practices. Reflexive monitoring showed positive feedback from patients and other staff about the value of screening, and feedback about the general practices testing rates helped sustain activity. Conclusions: A complex intervention including interactive workshops, materials to help implementation and feedback can help chlamydia screening testing increase in general practices

    Facilitators and “deal breakers”: a mixed methods study investigating implementation of the goal setting and action planning (G-AP) framework in community rehabilitation teams

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    Background: High quality goal setting in stroke rehabilitation is vital, but challenging to deliver. The G-AP framework (including staff training and a stroke survivor held G-AP record) guides patient centred goal setting with stroke survivors in community rehabilitation teams. We found G-AP was acceptable, feasible to deliver and clinically useful in one team. The aim of this study was to conduct a mixed methods investigation of G-AP implementation in diverse community teams prior to a large-scale evaluation. Methods: We approached Scottish community rehabilitation teams to take part. Following training, G-AP was delivered to stroke survivors within participating teams for 6 months. We investigated staff experiences of G-AP training and its implementation using focus groups and a training questionnaire. We investigated fidelity of G-AP delivery through case note review. Focus group data were analysed using a Framework approach; identified themes were mapped into Normalisation Process Theory constructs. Questionnaire and case note data were analysed descriptively. Results: We recruited three teams comprising 55 rehabilitation staff. Almost all staff (93%, 51/55) participated in G-AP training; of those, 80% (n = 41/51) completed the training questionnaire. Training was rated as ‘good’ or ‘very good’ by almost all staff (92%, n = 37/41). G-AP was broadly implemented as intended in two teams. Implementation facilitators included - G-AP ‘made sense’; repetitive use of G-AP in practice; flexible G-AP delivery and positive staff appraisals of G-AP impact. G-AP failed to gain traction in the third team. Implementation barriers included - delays between G-AP training and implementation; limited leadership engagement; a poor ‘fit’ between G-AP and the team organisational structure and simultaneous delivery of other goal setting methods. Staff recommended (i) development of training to include implementation planning; (ii) ongoing local implementation review and tailoring, and (iii) development of electronic and aphasia friendly G-AP records. Conclusions: The interaction between G-AP and the practice setting is critical to implementation success or failure. Whilst facilitators support implementation success, barriers can collectively act as implementation “deal breakers”. Local G-AP implementation efforts should be planned, monitored and tailored. These insights can inform implementation of other complex interventions in community rehabilitation settings
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