6,350 research outputs found

    Localization to delocalization transition in a driven nonlinear cavity array

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    We study nonlinear cavity arrays where the particle relaxation rate in each cavity increases with the excitation number. We show that coherent parametric inputs can drive such arrays into states with commensurate filling that form non-equilibrium analogs of Mott insulating states. We explore the boundaries of the Mott insulating phase and the transition to a delocalized phase with spontaneous first order coherence. While sharing many similarities with the Mott insulator to superfluid transition in equilibrium, the phase-diagrams we find also show marked differences. Particularly the off diagonal order does not become long range since the influence of dephasing processes increases with increasing tunneling rates.Comment: 7 pages, 8 figure

    Safeguarding Adults and Mass Marketing Fraud - perspectives from the Police, Trading Standards and the Voluntary Sector

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    Despite the growing awareness of Mass Marketing Fraud (MMF) in the financial abuse of vulnerable older people, little empirical research has been undertaken in this area. This paper is one of the first to consider the perspectives of a range of professionals who work with victims of mass marketing fraud and financial crime. MMF is a growing threat in the financial abuse of older people, and is increasingly recognised as a concern for professionals involved in supporting and safeguarding vulnerable older people. This paper considers the themes emerging from a small exploratory qualitative study into the perspectives of professionals working to safeguard those at risk of MMF and considers some of the complexities involved in tackling MMF. This involves consideration of the techniques used to groom and lure victims in plausible looking frauds, and the factors which serve to reinforce their sustained involvement in such activity

    “Winning and losing”: Vulnerability to Mass Marketing Fraud

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    Purpose – The purpose of this paper is to report the findings from a small qualitative study of victims of mass marketing fraud (MMF), exploring how they become involved in such activity and then sustain their involvement. The article concludes with recommendations for practitioners involved in supporting vulnerable older people. Design/methodology/approach – The paper considers a small exploratory qualitative study into the vulnerability of older people (n=3) to MMF from the perspectives of the ‘victims’ of such fraud, and four professionals from different agencies who work with cases of MMF (n=4). This paper reports specifically on the interviews with older people (n=3). Findings - This paper highlights a range of predisposing risk factors to MMF which emerged as key themes including the psycho-social background of the victim, emotional vulnerability, the need for meaningful activity, and opportunities engagement in meaningful social activity. Research limitations/implications - The small scale of this exploratory study is a limitation, but as there is currently a dearth of research in this area it makes a valuable contribution to the developing knowledge base. Practical implications - Professionals need to develop increased understanding of the complexities of sustained involvement in MMF, and the ways in which fraudsters manipulate potential victims by ‘grooming’ and luring through plausible schemes which appear genuine to the victim. Social implications - MMF is a growing threat in the financial abuse of older people, and is increasingly recognised as a concern for professionals involved in supporting and safeguarding vulnerable older people. Originality – Despite the growing awareness of MMF in the financial abuse of vulnerable older people, this paper is one of the first to consider the perspectives of victims of MMF

    The Hanbury Brown and Twiss Experiment with Fermions

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    We realized an equivalent Hanbury Brown and Twiss experiment for a beam of electrons in a two dimensional electron gas in the quantum Hall regime. A metallic split gate serves as a tunable beam splitter which is used to partition the incident beam into transmitted and reflected partial beams. The current fluctuations in the reflected and transmitted beam are fully anticorrelated demonstrating that fermions tend to exclude each other (anti-bunching). If the occupation probability of the incident beam is lowered by an additional gate, the anticorrelation is reduced and disappears in the classical limit of a highly diluted beam

    Assessing Dysplasia of a Bronchial Biopsy with FTIR Spectroscopic Imaging

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    An FTIR image of an 8 ”m section of de-paraffinised bronchial biopsy that shows a histological transition from normal to severe dysplasia/squamous cell carcinoma (SCC) insitu was obtained in transmission by stitching together images of 256 x 256 ”m recorded using a 96 x 96 element FPA detector. Each pixel spectrum was calculated from 128 co-added interferograms at 4 cm−1 resolution. In order to improve the signal to noise ratio, blocks of 4x4 adjacent pixels were subsequently averaged. Analyses of this spectral image, after conversion of the spectra to their second derivatives, show that the epithelium and the lamina propria tissue types can be distinguished using the area of troughs at either 1591, 1334, 1275 or 1215 cm−1 or, more effectively, by separation into two groups by hierarchical clustering (HCA) of the 1614-1465 region. Due to an insufficient signal to noise ratio, disease stages within the image could not be distinguished with this extent of pixel averaging. However, after separation of the cell types, disease stages within either the epithelium or the lamina propria could be distinguished if spectra were averaged from larger, manually selected areas of the tissue. Both cell types reveal spectral differences that follow a transition from normal to cancerous histology. For example, spectral changes that occurred in the epithelium over the transition from normal to carcinoma insitu could be seen in the 1200-1000 cm−1 region, particularly as a decrease in the second derivative troughs at 1074 and 1036 cm−1 , consistent with changes in some form of carbohydrate. Spectral differences that indicate a disease transition from normal to carcinoma in the lamina propria could be seen in the 1350-1175 cm−1 and 1125-1030 cm−1 regions. Thus demonstrating that a progression from healthy to severe dysplasia/squamous cell carcinoma (SCC) insitu can be seen using FTIR spectroscopic imaging and multivariate analysis

    Tile size selection for low-power tile-based architectures

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    In this paper, we investigate the power implications of tile size selection for tile-based processors. We refer to this investigation as a tile granularity study. This is accomplished by distilling the architectural cost of tiles with different computational widths into a system metric we call the Granularity Indicator (GI). The GI is then compared against the communications exposed when algorithms are partitioned across multiple tiles. Through this comparison, the tile granularity that best fits a given set of algorithms can be determined, reducing the system power for that set of algorithms. When the GI analysis is applied to the Synchroscalar tile architecture[1], we find that Synchroscalar\u27s already low power consumption can be further reduced by 14% when customized for execution of the 802.11a receiver. In addition, the GI can also be a used to evaluate tile size when considering multiple applications simultaneously, providing a convenient platform for hardware-software co-design

    Structure of the southern Keweenawan rift from COCORP surveys across the Midcontinent Geophysical Anomaly in northeastern Kansas

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    This is the published version. Copyright 1984 American Geophysical Union. All Rights Reserved.COCORP profiling across the midcontinent geophysical anomaly in northeastern Kansas reveals structural basins and other features of the Precambrian Keweenawan rift buried beneath the Phanerozoic cover. The 40-km-wide main basin is asymmetric, with a maximum depth of 3 km on the east and 8 km on the west. The basin fill is characterized by a lower layered sequence of strong continuous west dipping reflectors which may be correlated with Middle Keweenawan interbedded volcanic and clastic rocks exposed along the MGA in the Lake Superior region. Overlying this layered sequence is a zone of weak, discontinuous reflectors correlated here with the predominantly clastic rocks characteristic of the Upper Keweenawan sequence near Lake Superior. A second tilted but shallower basin lies to the east of the main basin and appears to be filled predominantly with clastic sedimentary rocks. The character of the seismic data, the seismic velocity distribution, and gravity modeling suggest that mafic intrusions lie beneath the main rift basin. Normal faults associated with the rift dip at moderate angles to the east. Palinspastic reconstruction indicates that the rift basin formed by the rotation of fault bounded blocks during crustal extension. Although reactivation of preexisting structures appears to have occurred in many other rifts profiled by COCORP, the evidence is inconclusive on this point in the case of the Kansas data. The structures mapped by COCORP surveys in Kansas and elsewhere suggest that asymmetric sequences of layered reflectors are characteristic, and perhaps diagnostic, of rift basin deposits in general

    The seasonal cycle of carbonate system processes in Ryder Bay, West Antarctic Peninsula

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    The carbon cycle in seasonally sea-ice covered waters remains poorly understood due to both a lack of observational data and the complexity of the system. Here we present three consecutive seasonal cycles of upper ocean dissolved inorganic carbon (DIC) and total alkalinity measurements from Ryder Bay on the West Antarctic Peninsula. We attribute the observed changes in DIC to four processes: mixing of water masses, air–sea CO2 flux, calcium carbonate precipitation/dissolution and photosynthesis/respiration. This approach enables us to resolve the main drivers of the seasonal DIC cycle and also investigate the mechanisms behind interannual variability in the carbonate system. We observe a strong, asymmetric seasonal cycle in the carbonate system, driven by physical processes and primary production. In summer, melting glacial ice and sea ice and a reduction in mixing with deeper water reduce the concentration of DIC in surface waters. The dominant process affecting the carbonate system is net photosynthesis which reduces DIC and the fugacity of CO2, making the ocean a net sink of atmospheric CO2. In winter, mixing with deeper, carbon-rich water and net heterotrophy increase surface DIC concentrations, resulting in pH as low as 7.95 and aragonite saturation states close to 1. We observe no clear seasonal cycle of calcium carbonate precipitation/dissolution but some short-lived features of the carbonate time series strongly suggest that significant precipitation of calcium carbonate does occur in the Bay. The variability observed in this study demonstrates that changes in mixing and sea-ice cover significantly affect carbon cycling in this dynamic environment. Maintaining this unique time series will allow the carbonate system in seasonally sea-ice covered waters to be better understood

    Effect of four weeks detraining on strength, power, and sensorimotor ability of adolescent surfers

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    Background: Surfing is a high skill sport that requires a considerable amount of time in a variety of ocean conditions to help develop the fundamental techniques. Objective: The purpose of this study was to investigate the effect of four weeks of detraining on strength, power, and sensorimotor ability in adolescent surfers. Methods: Nineteen adolescent surfers (13.8 A 1.7 y, 53.6 A 10.8 kg and 165.1 A 8.9 cm) participated in four weeks of detraining (surfing participation maintained but resistance training ceased) following seven weeks of periodized resistance training. Maximal isometric strength, power, and sensorimotor ability pre-test results were determined from the conclusion (post-test) of the first seven-week training block while post-test results were measured at the start (pre-test) of a second seven-week training block. Results: Four weeks of detraining significantly decreased the following variables: Vertical jump height by -5.26%, (p=0.037, d= 0.40), vertical jump peak velocity by -3.73% (p=0.001, d= 0.51), isometric strength by -5.5%, (p=0.012, d= 0.22), and relative isometric strength by -7.27% (p=0.003, d= 0.47). Furthermore, sensorimotor ability worsened, with a significant increase of 61.36% (p=0.004, d= 1.01), indicating that athletes took longer to stabilize from a dynamic landing task. Conclusions: This demonstrates that surfing, in the absence of resistance training, is not a sufficient training stimulus to maintain physical characteristics. Adolescent surfers with a relatively low training age should avoid cessation of resistance training and strive to maintain consistent resistance training in conjunction with surf training in order to avoid negative decrements in physical characteristics that are associated with surfing performance

    Coulomb induced positive current-current correlations in normal conductors

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    In the white-noise limit current correlations measured at different contacts of a mesoscopic conductor are negative due to the antisymmetry of the wave function (Pauli principle). We show that current fluctuations at capacitive contacts induced via the long range Coulomb interaction as consequence of charge fluctuations in the mesoscopic sample can be {\it positively} correlated. The positive correlations are a consequence of the extension of the wave-functions into areas near both contacts. As an example we investigate in detail a quantum point contact in a high magnetic field under conditions in which transport is along an edge state.Comment: Revtex, 4 pages includes 2 figure
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