564 research outputs found

    Experimental observation of high-order quantum accelerator modes.

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    Using a freely falling cloud of cold cesium atoms periodically kicked by pulses from a vertical standing wave of laser light, we present the first experimental observation of high-order quantum accelerator modes. This confirms the recent prediction by Fishman, Guarneri, and Rebuzzini [Phys. Rev. Lett.10.1103/PhysRevLett.89.084101 89, 084101 (2002)]. We also show how these accelerator modes can be identified with the stable regions of phase space in a classical-like chaotic system, despite their intrinsically quantum origin

    Do Assistive Devices, Training, and Workload Affect Injury Incidence? Prevention Efforts by Nursing Homes and Back Injuries among Nursing Assistants

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    This paper is a report of a study of association between workplace injuries experienced by nursing assistants in nursing homes in the United States and four factors that may affect injury rates: initial nursing assistant training, training at the current facility, lifting devices, and time to execute daily duties

    UK sustainable drainage systems: past, present and future

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    Urban drainage has developed from an engineering discipline, concerned principally with public health and safety outcomes, into a multifaceted vision linking drainage with environmental and wider social and economic imperatives to deliver multifunctional outcomes. UK attention is too often focused on surface water as ‘a problem’, despite international progress and initiatives showing that an ‘opportunity-centred’ approach needs to be taken. Sustainable drainage systems, or ‘Suds’, can, when they are part of an integrated approach to water management, cost-effectively provide many benefits beyond management of water quality and quantity. New tools are available that can design Suds for maximum value to society but this requires greater collaboration across disciplines to seize all of the opportunities available. This paper introduces those tools and a roadmap for their use, including guidance, design objectives and criteria for maximising benefits. These new supporting tools and guidance can help to provide a business case for greater use of Suds in future

    Comorbidity and repeat admission to hospital for adverse drug reactions in older adults: retrospective cohort study

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    Objectives To identify factors that predict repeat admission to hospital for adverse drug reactions (ADRs) in older adults

    Paleo-denudation rates suggest variations in runoff drove aggradation during last glacial cycle, Crete, Greece

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    Fluvial aggradation and incision are often linked to Quaternary climate cycles, but it usually remains unclear whether variations in runoff or sediment supply or both drive channel response to climate variability. Here we quantify sediment supply with paleo-denudation rates and provide geochronological constraints on aggradation and incision from the Sfakia and Elafonisi alluvial-fan sequences in Crete, Greece. We report seven optically stimulated luminescence (OSL)and ten radiocarbon ages, eight 10Be,and eight 36Cl denudation rates from modern channeland terrace sediments. For five samples, 10Be and 36Cl were measured on the same sample by measuring 10Be on chert and 36Cl on calcite. Results indicate relatively steady denudation rates throughout the past 80kyr, but the aggradation and incision history indicates a link with climate shifts. At the Elafonisi fan, we identify four periods of aggradation coinciding with Marine Isotope Stages (MIS) 2, 4, 5a/b, and likely 6, and three periods of incision coinciding with MIS 1, 3, and likely 5e. At the Sfakia fan, rapid aggradation occurred during MIS 2 and 4,followed by incision during MIS 1. Nearby climate and vegetation records show that MIS 2, 4, and 6 stadials were characterized by cold and dry climates with sparse vegetation, whereas forest cover and more humid conditions prevailed during MIS 1, 3, and 5. Our data thus suggest that past changes in climate had little effect on landscape-wide denudation rates but exerted a strong control on the aggradation-incision behaviour of alluvial channels on Crete. During glacial stages, we attribute aggradation to hillslope sediment release promoted by reduced vegetation cover and decreased runoff; conversely, incision occurred during relatively warm and wet stages due to increased runoff. In this landscape, past hydroclimate variations outcompeted changes in sediment supply as the primary driver of alluvial deposition and incision

    Observation of an unexpected third receptor molecule in the crystal structure of human interferon-γ receptor complex

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    AbstractBackground: Molecular interactions among cytokines and cytokine receptors form the basis of many cell-signaling pathways relevant to immune function. Interferon-γ (IFN-γ) signals through a multimeric receptor complex consisting of two different but structurally related transmembrane chains: the high-affinity receptor-binding subunit (IFN-γRα) and a species-specific accessory factor (AF-1 or IFN-γRβ). In the signaling complex, the two receptors probably interact with one another through their extracellular domains. Understanding the atomic interactions of signaling complexes enhances the ability to control and alter cell signaling and also provides a greater understanding of basic biochemical processes.Results: The crystal structure of the complex of human IFN-γ with the soluble, glycosylated extracellular part of IFN-γRα has been determined at 2.9 Å resolution using multiwavelength anomalous diffraction methods. In addition to the expected 2:1 complex, the crystal structure reveals the presence of a third receptor molecule not directly associated with the IFN-γ dimer. Two distinct intermolecular contacts, involving the edge strands of the C-terminal domains, are observed between this extra receptor and the 2:1 receptor–ligand complex thereby forming a 3:1 complex.Conclusions: The observed interactions in the 2:1 complex of the high-affinity cell-surface receptor with the IFN-γ cytokine are similar to those seen in a previously reported structure where the receptor chains were not glycosylated. The formation of β-sheet packing interactions between pairs of IFN-γRα receptors in these crystals suggests a possible model for receptor oligomerization of Rα and the structurally homologous Rβ receptors in the fully active IFN-γ signaling complex

    Theoretical analysis of quantum dynamics in 1D lattices: Wannier-Stark description

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    This papers presents a formalism describing the dynamics of a quantum particle in a one-dimensional tilted time-dependent lattice. The description uses the Wannier-Stark states, which are localized in each site of the lattice and provides a simple framework leading to fully-analytical developments. Particular attention is devoted to the case of a time-dependent potential, which results in a rich variety of quantum coherent dynamics is found.Comment: 8 pages, 6 figures, submitted to PR

    White Matter fMRI Activation Cannot Be Treated as a Nuisance Regressor: Overcoming a Historical Blind Spot

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    Despite past controversies, increasing evidence has led to acceptance that white matter activity is detectable using functional magnetic resonance imaging (fMRI). In spite of this, advanced analytic methods continue to be published that reinforce a historic bias against white matter activation by using it as a nuisance regressor. It is important that contemporary analyses overcome this blind spot in whole brain functional imaging, both to ensure that newly developed noise regression techniques are accurate, and to ensure that white matter, a vital and understudied part of the brain, is not ignored in functional neuroimaging studies

    Mental Health of Parents and Life Satisfaction of Children: A Within-Family Analysis of Intergenerational Transmission of Well-Being

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    This paper addresses the extent to which there is an intergenerational transmission of mental health and subjective well-being within families. Specifically it asks whether parents’ own mental distress influences their child’s life satisfaction, and vice versa. Whilst the evidence on daily contagion of stress and strain between members of the same family is substantial, the evidence on the transmission between parental distress and children’s well-being over a longer period of time is sparse. We tested this idea by examining the within-family transmission of mental distress from parent to child’s life satisfaction, and vice versa, using rich longitudinal data on 1,175 British youths. Results show that parental distress at year t-1 is an important determinant of child’s life satisfaction in the current year. This is true for boys and girls, although boys do not appear to be affected by maternal distress levels. The results also indicated that the child’s own life satisfaction is related with their father’s distress levels in the following year, regardless of the gender of the child. Finally, we examined whether the underlying transmission correlation is due to shared social environment, empathic reactions, or transmission via parent-child interaction
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