18,260 research outputs found

    Multi-band spectroscopy of inhomogeneous Mott-insulator states of ultracold bosons

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    In this work, we use inelastic scattering of light to study the response of inhomogeneous Mott-insulator gases to external excitations. The experimental setup and procedure to probe the atomic Mott states are presented in detail. We discuss the link between the energy absorbed by the gases and accessible experimental parameters as well as the linearity of the response to the scattering of light. We investigate the excitations of the system in multiple energy bands and a band-mapping technique allows us to identify band and momentum of the excited atoms. In addition the momentum distribution in the Mott states which is spread over the entire first Brillouin zone enables us to reconstruct the dispersion relation in the high energy bands using a single Bragg excitation with a fixed momentum transfer.Comment: 19 pages, 7 figure

    Management of Humeral Shaft Fractures; Non-Operative Versus Operative

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    Context: Functional humeral bracing remains the gold standard for treatment of humeral shaft fractures. There is an increasing trend in the literature to perform operative fixation of these fractures. Evidence Acquisition: The aim of this systematic review was to compare the level one evidence for the outcome of non-operative with operative management of humeral shaft fractures in adults. A comprehensive electronic literature search of Medline and PubMed was performed with specific inclusion criteria to identify randomized controlled trials. Results: In total, seventeen different studies were identified from the search terms and combinations used. Only one study met the inclusion criteria; however, this was a published study protocol of an ongoing trial currently being conducted. One additional published protocol for an ongoing trial was also identified, but this was for a prospective comparative observational study. Although this latter study may not be level one evidence, it would offer great insight into the functional outcome of humeral shaft fractures and economic implications of operative management, which is currently not addressed in the literature. Two retrospective comparative studies were also identified, one of which demonstrated a significantly lower rate of nonunion and malunion in those patients undergoing operative management. Conclusions: This systematic review demonstrated a deficiency in the current literature of level one evidence available for the management of humeral shaft fractures. The current ongoing randomized control trail would offer a greater insight into the management of humeral shaft fractures and help confirm or refute the current literature. If this randomized control trial affirms the reduction in the rate of nonunion with operative fixation, a cost economic analysis is essential. As it would seem to offer operative management to all patients may be over treatment and not to offer this at all would undertreat

    Long lasting instabilities in granular mixtures

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    We have performed experiments of axial segregation in the Oyama's drum. We have tested binary granular mixtures during very long times. The segregation patterns have been captured by a CCD camera and spatio-temporal graphs are created. We report the occurence of instabilities which can last several hours. We stress that those instabilities originate from the competition between axial and radial segregations. We put into evidence the occurence of giant fluctuations in the fraction of grain species along the surface during the unstable periods.Comment: 10 pages, 10 figures, (2002

    Getting into Uni in England and Australia: who you know, what you know or knowing the ropes?

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    Both England and Australia have displayed strong social democratic traditions in their approaches to higher education expansion in the second half of the twentieth century, but are now continuing that expansion as part of a ‘neo-liberal’ reform agenda. This paper traces how the rhetoric of widening participation and equitable access to higher education has remained a key feature of policy discourse in both contexts, albeit with different inflections and effects over time and indeed between the two countries. It also shows how the longstanding relationship between higher education and social and cultural reproduction has endured despite a series of ‘social democratic’ and ‘neo-liberal’ policy initiatives that have ostensibly sought to weaken that link. It concludes that more needs to be done if the rhetoric of equity and social justice is to impact upon the reality of contemporary higher education in these two countries

    RR Lyrae mode switching in globular cluster M 68 (NGC 4590)

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    D.M.B. acknowledges NPRP grant # X-019-1-006 from the Qatar National Research Fund (a member of Qatar Foundation). A.A.F. acknowledges the support of DGAPA-UNAM through project IN106615-17.We build on our detailed analysis of time-series observations of the globular cluster M 68 to investigate the irregular pulsational behaviour of four of the RR Lyrae stars in this cluster. M 68 is one of only two globular clusters in which mode switching of RR Lyrae stars has previously been reported. We discuss one additional case, as well as a case of irregular behaviour, and we briefly revisit the two previously reported cases with a homogeneous analysis. We find that in 2013, V45 was pulsating in the first-overtone mode alone, despite being previously reported as a double-mode (fundamental and first overtone) pulsator in 1994, and that the amplitude of the fundamental mode in V7 is increasing with time. We also suggest that V21 might not have switched pulsation modes as previously reported, although the first overtone seems to be becoming less dominant. Finally, our analysis of available archival data confirms that V33 lost a pulsation mode between 1950 and 1986.Publisher PDFPeer reviewe

    X-ray diffraction from bone employing annular and semi-annular beams

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    This is the final version of the article. Available from the publisher via the DOI in this record.There is a compelling need for accurate, low cost diagnostics to identify osteo-tissues that are associated with a high risk of fracture within an individual. To satisfy this requirement the quantification of bone characteristics such as 'bone quality' need to exceed that provided currently by densitometry. Bone mineral chemistry and microstructure can be determined from coherent x-ray scatter signatures of bone specimens. Therefore, if these signatures can be measured, in vivo, to an appropriate accuracy it should be possible by extending terms within a fracture risk model to improve fracture risk prediction.In this preliminary study we present an examination of a new x-ray diffraction technique that employs hollow annular and semi-annular beams to measure aspects of 'bone quality'. We present diffractograms obtained with our approach from ex vivo bone specimens at Mo Kα and W Kα energies. Primary data is parameterized to provide estimates of bone characteristics and to indicate the precision with which these can be determined.We acknowledge gratefully the funding provided by the UK Engineering and Physical Sciences Research Council (EPSRC) grant number EP/K020196/

    Improving water productivity, reducing poverty and enhancing equity in mixed crop-livestock systems in the Indo-Gangetic Basin: CPWF project report 68

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    Farming systems / Mixed farming / Water productivity / Feed production / Livestock / Energy consumption / Gender / Poverty / River basins / Case studies / India / Indo-Gangetic Basin / West Bengal / Haryana / Uttar Pradesh

    Rural migration in sub-Saharan Africa: Patterns, drivers and relation to structural transformation

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    Sub-Saharan Africa has a long history of internal and international migratory movements. Migration patterns and dynamics from, to and between rural areas are profoundly differentiated across regions, and flows have considerably evolved over time. Yet, more recently, rural migration takes place in the unique situation of a major rural and urban demographic increase, which results in critical socio-economic and environmental challenges. In this context, intertwined migration drivers emerge and call for a better understanding of on-going dynamics. This working paper draws on a combination of literature review and data analysis, building on the results of the Atlas "Rural Africa in motion. Dynamics and drivers of migration South of the Sahara". This mixed approach is used to propose a conceptual framework based on past, current and future drivers of migration, then to examine observed patterns of rural migration and finally to discuss drivers' characteristics and dynamics from case studies and existing datasets
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