1,660 research outputs found

    Acoustic vibration test detects intermittent electrical discontinuities

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    Nondestructive test method detects faulty electrical connections in inaccessible or hidden portions of electronic harness assemblies and connectors. Method employs readily available commercial equipment

    Psychological impacts of challenging behaviour and motivational orientation in staff supporting individuals with autistic spectrum conditions

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    Despite increased risk of experiencing challenging behaviour, psychological impacts on community and residential staff supporting adults with autistic spectrum conditions are under-explored. Studies examining related roles indicate protective psychological factors may help maintain staff well-being. This study investigated relationships between motivational orientation (eudaimonic or hedonic), challenging behaviour frequency and type (physical, verbal or self-injurious), and psychological impacts (anxiety, depression and life satisfaction). Participants (N=99) were recruited from six organisations providing autism-specific adult services within Scotland. A series of binary logistic regressions demonstrated weekly challenging behaviour exposure (compared to monthly or daily) significantly increased the likelihood of anxiety caseness. Increased eudaimonic motivation significantly reduced the likelihood of anxiety caseness while also predicting higher life satisfaction. Further, having high levels of eudaimonic motivation appeared to moderate the impact of weekly challenging behaviour exposure on anxiety. No motivational orientation or challenging behaviour factor significantly predicted depression. This sample also demonstrated higher anxiety, lower depression, and equivalent life satisfaction levels compared to general population norms. The results highlight the need for considering staff’s motivational orientations, their frequency of exposure to challenging behaviour, and both positive and negative psychological outcomes, if seeking to accurately quantify or improve well-being in this staff population

    How long is a hillslope?

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    Hillslope length is a fundamental attribute of landscapes, intrinsically linked to drainage density, landslide hazard, biogeochemical cycling and hillslope sediment transport. Existing methods to estimate catchment average hillslope lengths include inversion of drainage density or identification of a break in slope–area scaling, where the hillslope domain transitions into the fluvial domain. Here we implement a technique which models flow from point sources on hilltops across pixels in a digital elevation model (DEM), based on flow directions calculated using pixel aspect, until reaching the channel network, defined using recently developed channel extraction algorithms. Through comparisons between these measurement techniques, we show that estimating hillslope length from plots of topographic slope versus drainage area, or by inverting measures of drainage density, systematically underestimates hillslope length. In addition, hillslope lengths estimated by slope–area scaling breaks show large variations between catchments of similar morphology and area. We then use hillslope length–relief structure of landscapes to explore nature of sediment flux operating on a landscape. Distinct topographic forms are predicted for end-member sediment flux laws which constrain sediment transport on hillslopes as being linearly or nonlinearly dependent on hillslope gradient. Because our method extracts hillslope profiles originating from every ridgetop pixel in a DEM, we show that the resulting population of hillslope length–relief measurements can be used to differentiate between linear and nonlinear sediment transport laws in soil mantled landscapes. We find that across a broad range of sites across the continental United States, topography is consistent with a sediment flux law in which transport is nonlinearly proportional to topographic gradient

    Radio Planetary Nebulae in the Large Magellanic Cloud

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    We present 21 new radio-continuum detections at catalogued planetary nebula (PN) positions in the Large Magellanic Cloud (LMC) using all presently available data from the Australia Telescope Online Archive at 3, 6, 13 and 20 cm. Additionally, 11 previously detected LMC radio PNe are re-examined with 7 7 detections confirmed and reported here. An additional three PNe from our previous surveys are also studied. The last of the 11 previous detections is now classified as a compact \HII\ region which makes for a total sample of 31 radio PNe in the LMC. The radio-surface brightness to diameter (Σ\Sigma-D) relation is parametrised as ΣDβ\Sigma \propto {D^{ - \beta }}. With the available 6~cm Σ\Sigma-DD data we construct Σ\Sigma-DD samples from 28 LMC PNe and 9 Small Magellanic Cloud (SMC) radio detected PNe. The results of our sampled PNe in the Magellanic Clouds (MCs) are comparable to previous measurements of the Galactic PNe. We obtain β=2.9±0.4\beta=2.9\pm0.4 for the MC PNe compared to β=3.1±0.4\beta = 3.1\pm0.4 for the Galaxy. For a better insight into sample completeness and evolutionary features we reconstruct the Σ\Sigma-DD data probability density function (PDF). The PDF analysis implies that PNe are not likely to follow linear evolutionary paths. To estimate the significance of sensitivity selection effects we perform a Monte Carlo sensitivity simulation on the Σ\Sigma-DD data. The results suggest that selection effects are significant for values larger than β2.6\beta \sim 2.6 and that a measured slope of β=2.9\beta=2.9 should correspond to a sensitivity-free value of 3.4\sim 3.4.Comment: 19 pages, 9 figures, 6 table

    Constraining the Temperature of Impact Melt from the Mistastin Lake Impact Structure Using Zircon Crystal Structures

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    Impact melt is a product of hyper-velocity impact events formed by the instantaneous melting of near-surface target rocks. Constraining the temperature of impact melt is vital to understanding its prograde heating and cooling history, which can have implications for inferring the environment of early Earth ~4.0 billion years ago when microbial life potentially arose. To date, only one datum on the initial impact melt temperature has been derived by Timms et al. These authors studied zirconia microstructures and crystallographic orientations that revealed the former presence of cubic zirconia, found in a black impact glass at the Mistastin Lake impact structure, Canada. The presence of cubic zirconia indicates a minimum temperature for the impact melt of >2370C from the dissociation temperature of zircon to cubic zirconia and liquid SiO2. With only one temperature datum, it is still difficult to constrain the entire temperature range experienced during the impact melting process; from its instantaneous formation to thermal equilibrium with the cold clasts collected along the crater floor and walls. In addition, obtaining a temperature value from only one type of impactite limits the inferred temperature range, because each impactite experiences a different cooling history. In this study, we present a preliminary investigation of 61 zircon crystals, 14 of which are similar to those studied by Timms et al., from the Mistastin Lake impact structure. To acquire a more accurate temperature profile representative of impact melt, zircon crystals were collected from different types of impactites containing impact melt, including additional samples of the black impact glass studied by Timms et al

    Radio Planetary Nebulae in the Small Magellanic Cloud

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    We present ten new radio continuum (RC) detections at catalogued planetary nebula (PN) positions in the Small Magellanic Cloud (SMC): SMPS6, LIN 41, LIN 142, SMP S13, SMP S14, SMP S16, J18, SMP S18, SMP S19 and SMP S22. Additionally, six SMC radio PNe previously detected, LIN 45, SMP S11, SMPS17, LIN321, LIN339 and SMPS24 are also investigated (re-observed) here making up a population of 16 radio detections of catalogued PNe in the SMC. These 16 radio detections represent ~15 % of the total catalogued PN population in the SMC. We show that six of these objects have characteristics that suggest that they are PN mimics: LIN 41, LIN 45, SMP S11, LIN 142, LIN 321 and LIN 339. We also present our results for the surface brightness - PN radius relation ({\Sigma}-D) of the SMC radio PN population. These are consistent with previous SMC and LMC PN measurements of the ({\Sigma}-D) relation.Comment: Accepted for publication in Astrophysics and Space Scienc

    LMC X-1: A New Spectral Analysis of the O-star in the binary and surrounding nebula

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    We provide new observations of the LMC X-1 O star and its extended nebula structure using spectroscopic data from VLT/UVES as well as Hα\alpha imaging from the Wide Field Imager on the Max Planck Gesellschaft / European Southern Observatory 2.2m telescope and ATCA imaging of the 2.1 GHz radio continuum. This nebula is one of the few known to be energized by an X-ray binary. We use a new spectrum extraction technique that is superior to other methods to obtain both radial velocities and fluxes. This provides an updated spatial velocity of 21.0 ± 4.8\simeq 21.0~\pm~4.8 km s1^{-1} for the O star. The slit encompasses both the photo-ionized and shock-ionized regions of the nebula. The imaging shows a clear arc-like structure reminiscent of a wind bow shock in between the ionization cone and shock-ionized nebula. The observed structure can be fit well by the parabolic shape of a wind bow shock. If an interpretation of a wind bow shock system is valid, we investigate the N159-O1 star cluster as a potential parent of the system, suggesting a progenitor mass of 60\sim 60 M_{\odot} for the black hole. We further note that the radio emission could be non-thermal emission from the wind bow shock, or synchrotron emission associated with the jet inflated nebula. For both wind and jet-powered origins, this would represent one of the first radio detections of such a structure.Comment: 7 Figures, 4 Table

    An analysis of neonates with surgical diagnoses admitted to the neonatal intensive care unit at Charlotte Maxeke Johannesburg Academic Hospital, South Africa

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    Background. The burden of neonatal surgical conditions is not well documented in low- to middle-income countries (LMICs). These conditions are thought to be relatively common, with a considerable proportion of neonates admitted to the neonatal intensive care unit (NICU) requiring surgical intervention.Objectives. To review neonates with surgical conditions admitted to the NICU in our hospital setting.Methods. This was a retrospective, descriptive study of neonates with surgical conditions admitted to the NICU at Charlotte Maxeke Johannesburg Academic Hospital (CMJAH), South Africa, between 1 January 2013 and 31 December 2015. The characteristics and survival of these neonates were described using univariate analysis. The NICU at CMJAH is combined with a paediatric intensive care unit, to a total of 15 beds, and serves as a referral unit.Results. Of 923 neonates admitted to the NICU, 319 (34.6%) had primarily surgical conditions. Of these 319 neonates, 205 survived (64.3%). There were 125/319 neonates (39.2%) with necrotising enterocolitis (NEC), 55 of whom survived (55/125; 44.0%), making the presence of NEC significantly associated with poor outcome (p<0.001). Other significant predictors of poor outcome were the patient being outborn (p=0.029); the presence of late-onset sepsis (p<0.001), with Gram-negative organisms (p=0.005); and lesser gestational age (p=0.001) and lower birth weight (p<0.001). Major birth defects were present in 166/319 neonates (52.0%). The abdomen was the most prevalent site of surgery, with 216/258 procedures (83.7%) being abdominal, resulting in a mortality rate of 76/216 (35.2%).Conclusions. Neonates with major surgical conditions accounted for one-third of NICU admissions in the present study. The study highlights the considerable burden placed on paediatric surgical services at a large referral hospital in SA. Paediatric surgical services, with early referral and improvement of neonatal transport systems, must be a priority in planned healthcare interventions to reduce neonatal mortality in LMICs
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