4,327 research outputs found

    XMM-Newton view of the N 206 superbubble in the Large Magellanic Cloud

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    We perform an analysis of the X-ray superbubble in the N 206 HII region in the Large Magellanic Cloud using current generation facilities to gain a better understanding of the physical processes at work in the superbubble and to improve our knowledge of superbubble evolution. We used XMM-Newton observations of the N 206 region to produce images and extract spectra of the superbubble diffuse emission. Morphological comparisons with Halpha images from the Magellanic Cloud Emission Line Survey were performed, and spectral analysis of the diffuse X-ray emission was carried out. We derived the physical properties of the hot gas in the superbubble based on the results of the spectral analysis. We also determined the total energy stored in the superbubble and compared this to the expected energy input from the stellar population to assess the superbubble growth rate discrepancy for N 206. We find that the brightest region of diffuse X-ray emission is confined by a Halpha shell, consistent with the superbubble model. In addition, faint emission extending beyond the Halpha shell was found, which we attribute to a blowout region. The spectral analysis of both emission regions points to a hot shocked gas as the likely origin of the emission. We determine the total energy stored in the bubble and the expected energy input by the stellar population. However, due to limited data on the stellar population, the input energy is poorly constrained and, consequently, no definitive indication of a growth rate discrepancy is seen. Using the high-sensitivity X-ray data from XMM-Newton and optical data from the Magellanic Cloud Emission Line Survey has allowed us to better understand the physical properties of the N 206 superbubble and address some key questions of superbubble evolution.Comment: 12 pages, 7 figures. Accepted for publication in A&

    Visuospatial tasks suppress craving for cigarettes.

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    The Elaborated Intrusion (EI) theory of desire posits that visual imagery plays a key role in craving. We report a series of experiments testing this hypothesis in a drug addiction context. Experiment 1 showed that a mental visual imagery task with neutral content reduced cigarette craving in abstaining smokers, but that an equivalent auditory task did not. The effect of visual imagery was replicated in Experiment 2, which also showed comparable effects of non-imagery visual working memory interference. Experiment 3 showed that the benefit of visual over auditory interference was not dependent upon imagery being used to induce craving. Experiment 4 compared a visuomotor task, making shapes from modeling clay, with a verbal task (counting back from 100), and again showed a benefit of the visual over the non-visual task. We conclude that visual imagery supports craving for cigarettes. Competing imagery or visual working memory tasks may help tackle craving in smokers trying to quit

    Emotional and behavioral reaction to intrusive thoughts.

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    A self-report measure of the emotional and behavioral reactions to intrusive thoughts was developed. The article presents data that confirm the stability, reliability, and validity of the new seven-item measure. Emotional and behavioral reactions to intrusions emerged as separate factors on the Emotional and Behavioral Reactions to Intrusions Questionnaire (EBRIQ), a finding confirmed by an independent stress study. Test-retest reliability over 30 to 70 days was good. Expected relationships with other constructs were significant. Stronger negative responses to intrusions were associated with lower mindfulness scores and higher ratings of experiential avoidance, thought suppression, and intensity and frequency of craving. The EBRIQ will help explore differences in reactions to intrusive thoughts in clinical and nonclinical populations, and across different emotional and behavioral states. It will also be useful in assessing the effects of therapeutic approaches such as mindfulness

    Imaging and spectroscopy of laser-produced colliding plasmas

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    Laser-produced plasmas are formed when short pulse, high power lasers are focused onto a surface Applications range from VUV / X-ray sources for lithography, microscopy and radiography to X-ray lasers, thin him deposition, analytical spectroscopy and electron / ion beam generation A battery of particle and optical techniques are currently being used to fully characterise the properties of laserproduced plasmas. Over the past forty years much experimental and theoretical / computational work has focussed on the generation and expansion of LPP’s in vacuum Recently however, the dynamics of LPP’s expanding into background gasses has received increased interest This has been driven by the need to control the growth conditions of thin films produced using pulsed laser deposition The dynamics of LPP’s expanding into background gasses are very different from that of the vacuum case and leads to plume splitting and sharpening effects. Although much is known about the properties of laser-produced plasmas expanding in vacuum and into background gasses, very little is known about the expansion and interaction of a LPP into another LPP The aim of this project is the study of this system, colliding laser-produced plasmas Colliding plasma experiments may be cast as a model system for atmospheric and/or astrophysical colliding systems, for example when tracer elements are injected into supersonic winds at high altitude or collisionless plasma interaction in young supernova remnants Colliding plasmas have also been considered as a possible solution to the problem of particulate deposition in PLD. In order to study colliding plasmas m this work we have used, primarily, three diagnostic techniques VUV photoabsorption imaging was used in order to track the evolution of dark plume matter, or non-emitting plasma species residing m ground and metastable states We have also performed combined conventional gated CCD imaging and imaging spectroscopy to study excited species in the interaction region

    Towards the Development of an Interactive 3D Coach Training Serious Game

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    The twilight world of British business politics: the Spring Sunningdale conferences since the 1960s

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    This article explores a previously unknown form of interaction, known as Spring Sunningdale, between the British business elite and its civil servant equivalent in Whitehall. These began in 1963 and were still continuing only a few years ago. The continuity and stability of these meetings stands in contrast to wider changes in the nature of business–government relations in Britain during this period, particularly since the election of the Thatcher government in 1979. The article analyses why there was such continuity and what the senior civil servants and the captains of industry who attended these annual meetings gained from them

    Fully automated segmentation and tracking of the intima media thickness in ultrasound video sequences of the common carotid artery

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    Abstract—The robust identification and measurement of the intima media thickness (IMT) has a high clinical relevance because it represents one of the most precise predictors used in the assessment of potential future cardiovascular events. To facilitate the analysis of arterial wall thickening in serial clinical investigations, in this paper we have developed a novel fully automatic algorithm for the segmentation, measurement, and tracking of the intima media complex (IMC) in B-mode ultrasound video sequences. The proposed algorithm entails a two-stage image analysis process that initially addresses the segmentation of the IMC in the first frame of the ultrasound video sequence using a model-based approach; in the second step, a novel customized tracking procedure is applied to robustly detect the IMC in the subsequent frames. For the video tracking procedure, we introduce a spatially coherent algorithm called adaptive normalized correlation that prevents the tracking process from converging to wrong arterial interfaces. This represents the main contribution of this paper and was developed to deal with inconsistencies in the appearance of the IMC over the cardiac cycle. The quantitative evaluation has been carried out on 40 ultrasound video sequences of the common carotid artery (CCA) by comparing the results returned by the developed algorithm with respect to ground truth data that has been manually annotated by clinical experts. The measured IMTmean ± standard deviation recorded by the proposed algorithm is 0.60 mm ± 0.10, with a mean coefficient of variation (CV) of 2.05%, whereas the corresponding result obtained for the manually annotated ground truth data is 0.60 mm ± 0.11 with a mean CV equal to 5.60%. The numerical results reported in this paper indicate that the proposed algorithm is able to correctly segment and track the IMC in ultrasound CCA video sequences, and we were encouraged by the stability of our technique when applied to data captured under different imaging conditions. Future clinical studies will focus on the evaluation of patients that are affected by advanced cardiovascular conditions such as focal thickening and arterial plaques

    A Unique Multi-Messenger Signal of QCD Axion Dark Matter

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    We propose a multi-messenger probe of QCD axion Dark Matter based on observations of black hole-neutron star binary inspirals. It is suggested that a dense Dark Matter spike may grow around intermediate mass black holes (103105M10^{3}-10^{5} \mathrm{\,M_{\odot}}). The presence of such a spike produces two unique effects: a distinct phase shift in the gravitational wave strain during the inspiral and an enhancement of the radio emission due to the resonant axion-photon conversion occurring in the neutron star magnetosphere throughout the inspiral and merger. Remarkably, the observation of the gravitational wave signal can be used to infer the Dark Matter density and, consequently, to predict the radio emission. We study the projected reach of the LISA interferometer and next-generation radio telescopes such as the Square Kilometre Array. Given a sufficiently nearby system, such observations will potentially allow for the detection of QCD axion Dark Matter in the mass range 107eV10^{-7}\,\mathrm{eV} to 105eV10^{-5}\,\mathrm{eV}.Comment: 5 pages, 3 figures. Appendix added with additional figures. Updated to published versio
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