4,579 research outputs found

    Exact vortex nucleation and cooperative vortex tunneling in dilute BECs

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    With the imminent advent of mesoscopic rotating BECs in the lowest Landau level (LLL) regime, we explore LLL vortex nucleation. An exact many-body analysis is presented in a weakly elliptical trap for up to 400 particles. Striking non-mean field features are exposed at filling factors >>1 . Eg near the critical rotation frequency pairs of energy levels approach each other with exponential accuracy. A physical interpretation is provided by requantising a mean field theory, where 1/N plays the role of Planck's constant, revealing two vortices cooperatively tunneling between classically degenerate energy minima. The tunnel splitting variation is described in terms of frequency, particle number and ellipticity.Comment: 4 pages,4 figure

    Implementation principles - turning intentions into outcomes

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    Companies sometimes fail to take effective action even when they know what they should do. Recent research shows that this surprising situation is more common than one would expect. How can the track record of companies in achieving the outcomes targeted by manufacturing strategy be improved? This article proposes a set of eight principles to improve the chances of taking effective action to turn intentions into outcomes. Rooted in the literature, the principles have also surfaced in case based research and commented on in the context of international consulting activities

    Anomalous hydrodynamics and "normal" fluids in rapidly rotating BECs

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    In rapidly rotating bose systems we show that there is a region of anomalous hydrodynamics whilst the system is still condensed, which coincides with the mean field quantum Hall regime. An immediate consequence is the absence of a normal fluid in any conventional sense. However, even the superfluid hydrodynamics is not described by conventional Bernoulli and continuity equations. We show there are kinematic constraints which connect spatial variations of density and phase, that the positions of vortices are not the simplest description of the dynamics of such a fluid (despite their utility in describing the instantaneous state of the condensate) and that the most compact description allows solution of some illuminating examples of motion. We demonstrate, inter alia, a very simple relation between vortices and surface waves. We show the surface waves can form a "normal fluid" which absorbs energy and angular momentum from vortex motion in the trap. The time scale of this process is sensitive to the initial configuration of the vortices, which can lead to long-lived vortex patches - perhaps related to those observed at JILA.Comment: 4 pages; 1 sentence and references modifie

    Keeping Confidence: Responsibility and public health

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    Keeping Confidence: HIV and the criminal law from service provider perspectives Duration: June 2012 - March 2013 The Monument Trust generously funded Sigma Research at London School of Hygiene and Tropical Medicine and Birkbeck College to undertake a qualitative study on perceptions of criminal prosecutions for HIV transmission among HIV service providers. Five short reports outlining the key findings of the study focus on the main themes arising from our analysis of the focus group discussions. The findings and associated policy and practice recommendations will be of interest to: those who provide HIV health and social care and their professional bodies (for instance NHIVNA, CHIVA, BHIVA, BASHH, SSHA, BPS), police and others who play a role in criminal investigations and trials, and people with diagnosed HIV

    Keeping Confidence: Understanding the Law

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    Keeping Confidence: HIV and the criminal law from service provider perspectives Duration: June 2012 - March 2013 The Monument Trust generously funded Sigma Research at London School of Hygiene and Tropical Medicine and Birkbeck College to undertake a qualitative study on perceptions of criminal prosecutions for HIV transmission among HIV service providers. Five short reports outlining the key findings of the study focus on the main themes arising from our analysis of the focus group discussions. The findings and associated policy and practice recommendations will be of interest to: those who provide HIV health and social care and their professional bodies (for instance NHIVNA, CHIVA, BHIVA, BASHH, SSHA, BPS), police and others who play a role in criminal investigations and trials, and people with diagnosed HIV

    Keeping Confidence: Practice and procedure

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    Keeping Confidence: HIV and the criminal law from service provider perspectives Duration: June 2012 - March 2013 The Monument Trust generously funded Sigma Research at London School of Hygiene and Tropical Medicine and Birkbeck College to undertake a qualitative study on perceptions of criminal prosecutions for HIV transmission among HIV service providers. Five short reports outlining the key findings of the study focus on the main themes arising from our analysis of the focus group discussions. The findings and associated policy and practice recommendations will be of interest to: those who provide HIV health and social care and their professional bodies (for instance NHIVNA, CHIVA, BHIVA, BASHH, SSHA, BPS), police and others who play a role in criminal investigations and trials, and people with diagnosed HIV

    Keeping Confidence: Identifying resources

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    Keeping Confidence: HIV and the criminal law from service provider perspectives Duration: June 2012 - March 2013 The Monument Trust generously funded Sigma Research at London School of Hygiene and Tropical Medicine and Birkbeck College to undertake a qualitative study on perceptions of criminal prosecutions for HIV transmission among HIV service providers. Five short reports outlining the key findings of the study focus on the main themes arising from our analysis of the focus group discussions. The findings and associated policy and practice recommendations will be of interest to: those who provide HIV health and social care and their professional bodies (for instance NHIVNA, CHIVA, BHIVA, BASHH, SSHA, BPS), police and others who play a role in criminal investigations and trials, and people with diagnosed HIV. Catherine Dodds, Matthew Weait, Adam Bourne, Siri Egede, Kathie Jessup and Peter Weatherburn

    Keeping Confidence: HIV and the criminal law from service provider perspectives. Executive Summary

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    Keeping Confidence is a qualitative research study that explores the perceptions of criminal prosecutions for HIV transmission among those providing support, health and social care services for people with HIV. The main findings of the study are described in detail in four focussed reports, listed in the box above. This executive summary gives information about the background and methods of the project, and provides an overview of key themes and findings, concluding with recommendations relevant to those planning and delivering services for people with diagnosed HIV. Catherine Dodds, Matthew Weait, Adam Bourne, Siri Egede, Kathie Jessup and Peter Weatherburn. Five short reports outlining the key findings of the study focus on the main themes arising from our analysis of the focus group discussions. The findings and associated policy and practice recommendations will be of interest to: those who provide HIV health and social care and their professional bodies (for instance NHIVNA, CHIVA, BHIVA, BASHH, SSHA, BPS), police and others who play a role in criminal investigations and trials, and people with diagnosed HIV

    Underestimated risks of recurrent long-range ash dispersal from northern Pacific Arc volcanoes

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    Widespread ash dispersal poses a significant natural hazard to society, particularly in relation to disruption to aviation. Assessing the extent of the threat of far-travelled ash clouds on flight paths is substantially hindered by an incomplete volcanic history and an underestimation of the potential reach of distant eruptive centres. The risk of extensive ash clouds to aviation is thus poorly quantified. New evidence is presented of explosive Late Pleistocene eruptions in the Pacific Arc, currently undocumented in the proximal geological record, which dispersed ash up to 8000?km from source. Twelve microscopic ash deposits or cryptotephra, invisible to the naked eye, discovered within Greenland ice-cores, and ranging in age between 11.1 and 83.7 ka b2k, are compositionally matched to northern Pacific Arc sources including Japan, Kamchatka, Cascades and Alaska. Only two cryptotephra deposits are correlated to known high-magnitude eruptions (Towada-H, Japan, ca 15 ka BP and Mount St Helens Set M, ca 28 ka BP). For the remaining 10 deposits, there is no evidence of age- and compositionally-equivalent eruptive events in regional volcanic stratigraphies. This highlights the inherent problem of under-reporting eruptions and the dangers of underestimating the long-term risk of widespread ash dispersal for trans-Pacific and trans-Atlantic flight route
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