7,315 research outputs found

    Random telegraph signals in charge coupled devices

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    An investigation of fluctuating pixels resulting from proton irradiation of an E2V Technologies CCD47-20 device is presented. The device structure,experimental set up and irradiation methodology are described, followed by a detailed analysis of radiation induced random telegraph signals,RTS. The characteristics of the observed flickering pixels are discussed in detail and the proposed models explaining the mechanism behind the phenomena are viewed in light of the collected data

    Beyond supply and demand: addressing the complexities of workforce exclusion in Australia

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    Workforce exclusion is a complex and enduring problem in Australia, with some groups of job seekers more likely to be disadvantaged in the labour market than others. We identify a dominant unemployment narrative of ‘work first’ that surrounds unemployment interventions, and ignores the nature of disadvantage and its relationship to workforce exclusion, and reduces unemployment to a simple matter of labour market supply and demand. This approach privileges immediate economic productivity and exit from welfare payments over sustainable attachment to quality jobs. We examine fourteen programs for disadvantaged job seekers under one national provider network. Data was gathered from eleven semi-structured telephone interviews and eight evaluation reports and analysed using thematic analysis supported by NVivo. Our findings challenge the dominant narrative and argue that both ends of the supply and demand equation need to be examined, stressing the importance of a partnership-orientated and capacity building focus on the unemployed person, and the significance of quality employment with long term support. We identify the importance of acknowledging job seekers’ strengths, aspirations and preferences, and of job seekers having agency to determine their own pathways with support from service providers

    Proton induced leakage current in CCDs

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    The effect of different proton fluences on the performance of two E2V Technologies CCD47-20 devices was investigated with particular emphasis given to the analysis of 'random telegraph signal' (RTS) generation, bright pixel generation and induced changes in base dark current level. The results show that bright pixel frequency increases as the mean energy of the proton beam is increased, and that the base dark current level after irradiation scales with the level of ionization damage. For the RTS study, 500 pixels on one device were monitored over a twelve hour period. This data set revealed a number of distinct types of pixel change level fluctuation and a system of classification has been devised. Previously published RTS data is discussed and reviewed in light of the new data

    Low noise charge injection in the CCD22

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    The inclusion of a charge injection structure on a charge coupled device (CCD) allows for the mitigation of charge transfer loss which can be caused by radiation induced charge trapping defects. Any traps present in the pixels of the CCD are filled by the injected charge as it is swept through the device and consequently, the charge transfer efficiency is improved in subsequently acquired images. To date, a number of different types of CCD have been manufactured featuring a variety of charge injection techniques. The e2v Technologies CCD22, used in the EPIC MOS focal plane instruments of XMM-Newton, is one such device and is the subject of this paper. A detailed understanding of charge injection operation and the use of charge injection to mitigate charge transfer losses resulting from radiation damage to CCDs will benefit a number of space projects planned for the future, including the ESA GAIA and X-ray Evolving Universe Spectrometry (XEUS) missions.The charge injection structure and mode of operation of the CCD22 are presented, followed by a detailed analysis of the uniformity and repeatability of the charge injection amplitude across the columns of the device. The effects of proton irradiation on the charge injection characteristics are also presented, in particular the effect of radiation induced bright pixels on the injected charge level

    The impact of low energy proton damage on the operational characteristics of EPIC-MOS CCDs

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    The University of Tübingen 3.5 MeV Van de Graaf accelerator facility was used to investigate the effect of low energy protons on the performance of the European Photon Imaging Camera (EPIC), metal–oxide semiconductor (MOS), charge coupled devices (CCDs). Two CCDs were irradiated in different parts of their detecting areas using different proton spectra and dose rates. Iron-55 was the calibration source in all cases and was used to measure any increases in charge transfer inefficiency (CTI) and spectral resolution of the CCDs. Additional changes in the CCD bright pixel table and changes in the low X-ray energy response of the device were examined. The Monte Carlo code Stopping Range of Ions in Matter (SRIM) was used to model the effect of a 10 MeV equivalent fluence of protons interacting with the CCD. Since the non-ionising energy loss (NIEL) function could not be applied effectively at such low proton energies. From the 10 MeV values, the expected CTI degradation could be calculated and then compared to the measured CTI changes

    MOS CCDs for the wide field imager on the XEUS spacecraft

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    In recent years the XEUS mission concept has evolved and has been the subject of several industrial studies. The mission concept has now matured to the point that it could be proposed for a Phase A study and subsequent flight programme. The key feature of XEUS will be its X-ray optic with collecting area ~30-100x that of XMM. The mission is envisaged at an orbit around the L2 point in space, and is formed from two spacecraft; one for the mirrors, and the other for the focal plane detectors. With a focal length of 50m, the plate scale of the optic is 6.5x that of XMM, which using existing focal plane technology will reduce the effective field of view to a few arc minutes. Cryogenic instrumentation, with detector sizes of a few mm can only be used for narrow field studies of target objects, and a wide field instrument is under consideration using a DEPFET pixel array to image out to a diameter of 5 arcminutes, requiring an array of dimension 70mm. It is envisaged to extend this field of view possibly out to 15 arcminutes through the use of an outer detection ring comprised of MOS CCD

    Ontogenetic scaling patterns and functional anatomy of the pelvic limb musculature in emus (Dromaius novaehollandiae)

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    Emus (Dromaius novaehollandiae) are exclusively terrestrial, bipedal and cursorial ratites with some similar biomechanical characteristics to humans. Their growth rates are impressive, as their body mass increases eighty-fold from hatching to adulthood whilst maintaining the same mode of locomotion throughout life. These ontogenetic characteristics stimulate biomechanical questions about the strategies that allow emus to cope with their rapid growth and locomotion, which can be partly addressed via scaling (allometric) analysis of morphology. In this study we have collected pelvic limb anatomical data (muscle architecture, tendon length, tendon mass and bone lengths) and calculated muscle physiological cross sectional area (PCSA) and average tendon cross sectional area from emus across three ontogenetic stages (n = 17, body masses from 3.6 to 42 kg). The data were analysed by reduced major axis regression to determine how these biomechanically relevant aspects of morphology scaled with body mass. Muscle mass and PCSA showed a marked trend towards positive allometry (26 and 27 out of 34 muscles respectively) and fascicle length showed a more mixed scaling pattern. The long tendons of the main digital flexors scaled with positive allometry for all characteristics whilst other tendons demonstrated a less clear scaling pattern. Finally, the two longer bones of the limb (tibiotarsus and tarsometatarsus) also exhibited positive allometry for length, and two others (femur and first phalanx of digit III) had trends towards isometry. These results indicate that emus experience a relative increase in their muscle force-generating capacities, as well as potentially increasing the force-sustaining capacities of their tendons, as they grow. Furthermore, we have clarified anatomical descriptions and provided illustrations of the pelvic limb muscle–tendon units in emus

    Midway Consulting: Bridging the Gap between Producer and Consumer

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    A poster presented by Troy Hutchinson, Hannah Jones, Devan Neely and Anna Smith for the class Business, Accounting and Entrepreneurship: Proposed Business Plans.https://scholarworks.moreheadstate.edu/gsp_projects_2019/1004/thumbnail.jp

    Understanding the patient's perspective on rapid and routine HIV testing in an inner-city urgent care center

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    The purpose of this study was to explore patient perspectives of rapid and routine HIV-testing in an urgent care center at an urban public hospital. We conducted structured focus groups during a clinical trial comparing routinely offered rapid HIV-testing, routinely offered enzyme immunoassay (EIA) testing, and conventional EIA testing. Participants of the six focus groups were 89% African American, 60% uninsured, and had a low educational status. Four independent coders analyzed the data using iterative content analysis. Rapid testing was preferred to EIA testing because it reduced the need for a return visit and stress of waiting for test results, though there were concerns about accuracy. Participants supported routinely offering testing, but there were concerns about privacy and cost. Fear and stigma were common reasons for refusing testing and not returning for results. Distrust and misconceptions about HIV, particularly regarding the importance of testing, were very common
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