201 research outputs found

    Observation of superconducting vortices carrying a temperature-dependent fraction of the flux quantum

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    The magnetic response is a state-defining property of superconductors. The magnetic flux penetrates type-II bulk superconductors by forming quantum vortices when the enclosed magnetic flux is equal to the magnetic flux quantum. The flux quantum is the universal quantity that depends only on the ratio of fundamental constants: the electron charge and the Planck constant. This work investigates the vortex state in the hole-overdoped Ba1x_{1-x}Kx_xFe2_2As2_2 by using scanning superconducting quantum interference device (SQUID) magnetometry. We observed quantum vortices that carry only a fraction of the flux quantum, which vary continuously with temperature. This finding establishes the phenomenon that superconductors support quantum vortices with non-universally quantized magnetic flux. Furthermore, the demonstrations of the mobility of the fractional vortices and the manipulability of their positions open up a route for future fluxonics applications.Comment: 19 pages, 9 figure

    Experience of non-vascular complications following endovascular aneurysm repair for abdominal aortic aneurysm

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    Endovascular aneurysm repair (EVAR) for the treatment of abdominal aortic aneurysm (AAA) is a widely used method, and its decreased invasiveness compared to traditional surgical repair has brought about reduced rates of morbidity and mortality. Several vascular complications related to the procedure have been reported, but non-vascular complications have rarely occurred. We report herein the case of a 78-year-old man who underwent EVAR for AAA and presented with active duodenal ulcer bleeding and acute acalculous cholecystitis as complications after the procedure. We must consider that a wide spectrum of complications may occur following EVAR, and therefore it is important to evaluate the risks of complication and to take the necessary measures to minimize them

    Ferrous Iron Binding Key to Mms6 Magnetite Biomineralisation: A Mechanistic Study to Understand Magnetite Formation Using pH Titration and NMR Spectroscopy

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    Formation of magnetite nanocrystals by magn eto-tactic bacteria is controlled by specificproteins whichregu-late the particles’ nucleation and growth.One such proteinis Mms6. This small, amphiph ilic protein can self-assembleand bind ferric ions to aid in magnetite formation. To under-stand the role of Mms6 duringinvitro iron oxide precipita-tion we have performed in situ pH titrations. We find Mms6has little effect duringferric salt precipitation, but exertsgreatest influence during the incorporation of ferrous ionsand conversion of this salt to mixed-valence iron mineral s,suggesting Mms6 has ahitherto unrecorded ferrous iron in-teracting property which promotes the formation of mag-netiteinferrous-rich solutions.Weshow ferrous binding tothe DEEVE motif within the C-term inal region of Mms6 byNMR spectroscopy,and model these binding events usingmolecular simulations. We conclude that Mms6 functions asamagnetite nucleating protein under cond itions where fer-rous ions predominate

    Chronic adiponectin deficiency leads to Alzheimer’s disease-like cognitive impairments and pathologies through AMPK inactivation and cerebral insulin resistance in aged mice

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    (a) Immunoblotting analysis of IRβ in the hippocampus and frontal cortex of 18-month old wildtype and APN-KO mice. (b) Densitometric analysis of the ratio of IRβ. Mean ± S.E.M.; ***p < 0.001, n.s. statistically not significant; Scale bar: 100 μm. (JPG 30 kb

    Combating social exclusion faced by disabled people in the wage labour market in Hong Kong

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    This article contributes to the search for suitable approaches to combat social exclusion faced by disabled people in capitalist wage labour markets. Referring to policy and service examples in Hong Kong, it reviews four social exclusion approaches – the Moral Underclass (MUD), Social Integrationist (SID), Redistributive (RED) and Collective Production (COP) approaches. These approaches are explored in relation to three key issues: (1) the diverse preferences of disabled people; (2) the myth of infeasibility regarding unconventional approaches and (3) the defects of the medical model of disability. The article argues that the MUD and SID approaches are more associated with the medical model of disability and emphasise individual changes. The RED and COP approaches contain more features of the social model of disability and are in favour of social and structural changes. The COP approach stresses the diverse preferences of disabled people and supports innovative services to combat social exclusion

    Perspective‐Taking and Depth of Theory‐of‐Mind Reasoning in Sequential‐Move Games

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    Theory‐of‐mind (ToM) involves modeling an individual’s mental states to plan one’s action and to anticipate others’ actions through recursive reasoning that may be myopic (with limited recursion) or predictive (with full recursion). ToM recursion was examined using a series of two‐player, sequential‐move matrix games with a maximum of three steps. Participants were assigned the role of Player I, controlling the initial and the last step, or of Player II, controlling the second step. Appropriate for the assigned role, participants either anticipated or planned Player II’s strategy at the second step, and then determined Player I’s optimal strategy at the first step. Participants more readily used predictive reasoning as Player II (i.e., planning one’s own move) than as Player I (i.e., anticipating an opponent’s move), although they did not differ when translating reasoning outcome about the second step to optimal action in the first step. Perspective‐taking influenced likelihood of predictive reasoning, but it did not affect the rate at which participants acquired it during the experimental block. We conclude that the depth of ToM recursion (related to perspective‐taking mechanisms) and rational application of belief–desire to action (instrumental rationality) constitute separate cognitive processes in ToM reasoning.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/91101/1/j.1551-6709.2012.01238.x.pd

    Optimal control of impulsive switched systems with minimum subsystem durations

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    This paper presents a new computational approach for solving optimal control problems governed by impulsive switched systems. Such systems consist of multiple subsystems operating in succession, with possible instantaneous state jumps occurring when the system switches from one subsystem to another. The control variables are the subsystem durations and a set of system parameters influencing the state jumps. In contrast with most other papers on the control of impulsive switched systems, we do not require every potential subsystem to be active during the time horizon (it may be optimal to delete certain subsystems, especially when the optimal number of switches is unknown). However, any active subsystem must be active for a minimum non-negligible duration of time. This restriction leads to a disjoint feasible region for the subsystem durations. The problem of choosing the subsystem durations and the system parameters to minimize a given cost function is a non-standard optimal control problem that cannot be solved using conventional techniques. By combining a time-scaling transformation and an exact penalty method, we develop a computational algorithm for solving this problem. We then demonstrate the effectiveness of this algorithm by considering a numerical example on the optimization of shrimp harvesting operations

    Aerosols in the E3SM Version 1: New Developments and Their Impacts on Radiative Forcing

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    The new Energy Exascale Earth System Model Version 1 (E3SMv1) developed for the U.S. Department of Energy has significant new treatments of aerosols and lightâ absorbing snow impurities as well as their interactions with clouds and radiation. This study describes seven sets of new aerosolâ related treatments (involving emissions, new particle formation, aerosol transport, wet scavenging and resuspension, and snow radiative transfer) and examines how they affect global aerosols and radiative forcing in E3SMv1. Altogether, they give a reduced total aerosol radiative forcing (â 1.6 W/m2) and sensitivity in cloud liquid water to aerosols, but an increased sensitivity in cloud droplet size to aerosols. A new approach for H2SO4 production and loss largely reduces a low bias in small particles concentrations and leads to substantial increases in cloud condensation nuclei concentrations and cloud radiative cooling. Emitting secondary organic aerosol precursor gases from elevated sources increases the column burden of secondary organic aerosol, contributing substantially to global clearâ sky aerosol radiative cooling (â 0.15 out of â 0.5 W/m2). A new treatment of aerosol resuspension from evaporating precipitation, developed to remedy two shortcomings of the original treatment, produces a modest reduction in aerosols and cloud droplets; its impact depends strongly on the model physics and is much stronger in E3SM Version 0. New treatments of the mixing state and optical properties of snow impurities and snow grains introduce a positive presentâ day shortwave radiative forcing (0.26 W/m2), but changes in aerosol transport and wet removal processes also affect the concentration and radiative forcing of lightâ absorbing impurities in snow/ice.Plain Language SummaryAerosol and aerosolâ cloud interactions continue to be a major uncertainty in Earth system models, impeding their ability to reproduce the observed historical warming and to project changes in global climate and water cycle. The U.S. DOE Energy Exascale Earth System Model version 1 (E3SMv1), a stateâ ofâ theâ science Earth system model, was developed to use exascale computing to address the grand challenge of actionable predictions of variability and change in the Earth system critical to the energy sector. It has been publicly released with new treatments in many aspects, including substantial modifications to the physical treatments of aerosols in the atmosphere and lightâ absorbing impurities in snow/ice, aimed at reducing some known biases or correcting model deficiencies in representing aerosols, their life cycle, and their impacts in various components of the Earth system. Compared to its predecessors (without the new treatments) and observations, E3SMv1 shows improvements in characterizing global distributions of aerosols and their radiative effects. We conduct sensitivity experiments to understand the impact of individual changes and provide guidance for future development of E3SM and other Earth system models.Key PointsA description and assessment of new aerosol treatments in the Energy Exascale Earth System Model Version 1 (E3SMv1) is providedContributions to the total aerosolâ related radiative forcing by individual new treatments and different processes are quantifiedSome of the new treatments are found to depend on model physics and require further improvement for E3SM or other Earth system modelsPeer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/153241/1/jame21034-sup-0001-Figure_SI-S01.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/153241/2/jame21034.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/153241/3/jame21034_am.pd

    The tropical rain belts with an annual cycle and a continent model intercomparison project: TRACMIP

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    This paper introduces the Tropical Rain belts with an Annual cycle and a Continent Model Intercomparison Project (TRACMIP). TRACMIP studies the dynamics of tropical rain belts and their response to past and future radiative forcings through simulations with 13 comprehensive and one simplified atmosphere models coupled to a slab ocean and driven by seasonally-varying insolation. Five idealised experiments, two with an aquaplanet setup and three with a setup with an idealized tropical continent, fill the space between prescribed-SST aquaplanet simulations and realistic simulations provided by CMIP5/6. The simulations reproduce key features of present-day climate and expected future climate change, including an annual-mean intertropical convergence zone (ITCZ) that is located north of the equator and Hadley cells and eddy-driven jets that are similar to present-day climate. Quadrupling CO2 leads to a northward ITCZ shift and preferential warming in Northern high-latitudes. The simulations show interesting CO2-induced changes in the seasonal excursion of the ITCZ and indicate a possible state-dependence of climate sensitivity. The inclusion of an idealized continent modulates both the control climate and the response to increased CO2; for example, it reduces the northward ITCZ shift associated with warming and, in some models, climate sensitivity. In response to eccentricity-driven orbital seasonal insolation changes, seasonal changes in oceanic rainfall are best characterized as a meridional dipole, while seasonal continental rainfall changes tend to be symmetric about the equator. This survey illustrates TRACMIP's potential to engender a deeper understanding of global and regional climate and to address questions on past and future climate
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