395 research outputs found
An Extreme X-ray Disk Wind in the Black Hole Candidate IGR J17091-3624
{\it Chandra} spectroscopy of transient stellar-mass black holes in outburst
has clearly revealed accretion disk winds in soft, disk--dominated states, in
apparent anti-correlation with relativistic jets in low/hard states. These disk
winds are observed to be highly ionized, dense, and to have typical velocities
of 1000 km/s or less projected along our line of sight. Here, we present
an analysis of two {\it Chandra} High Energy Transmission Grating spectra of
the Galactic black hole candidate IGR J170913624 and contemporaneous EVLA
radio observations, obtained in 2011. The second {\it Chandra} observation
reveals an absorption line at 6.910.01 keV; associating this line with
He-like Fe XXV requires a blue-shift of km/s (0.03, or
the escape velocity at 1000 R). This projected outflow velocity is an
order of magnitude higher than has previously been observed in stellar-mass
black holes, and is broadly consistent with some of the fastest winds detected
in active galactic nuclei. A potential feature at 7.32 keV, if due to Fe XXVI,
would imply a velocity of km/s (0.05), but this putative
feature is marginal. Photoionization modeling suggests that the accretion disk
wind in IGR J170913624 may originate within 43,300 Schwarzschild radii of
the black hole, and may be expelling more gas than accretes. The
contemporaneous EVLA observations strongly indicate that jet activity was
indeed quenched at the time of our {\it Chandra} observations. We discuss the
results in the context of disk winds, jets, and basic accretion disk physics in
accreting black hole systems.Comment: 6 pages, 2 figures, Accepted to ApJLetter
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A randomised controlled trial of cognitive behavioural treatment for obsessive compulsive disorder in children and adolescents
Cognitive behaviour therapy (CBT) for young people with obsessive compulsive disorder (OCD) has become the treatment of first choice. However, the literature is largely based on studies emphasising exposure and response prevention. In this study, we report on a randomised controlled trial of CBT for young people carried out in typical outpatient clinic conditions which focused on cognitions. A randomised controlled trial compares 10 sessions of manualised cognitive behavioural treatment with a 12-week waiting list for adolescents and children with OCD. Assessors were blind to treatment allocation. 21 consecutive patients with OCD aged between 9 and 18 years were recruited. The group who received treatment improved more than a comparison group who waited for 3 months. The second group was treated subsequently using the same protocol and made similar gains. In conclusion, CBT can be delivered effectively to young people with OCD in typical outpatient settings
Using venous blood gas analysis in the assessment of COPD exacerbations: a prospective cohort study
Introduction: Identifying acute hypercapnic respiratory failure is crucial in the initial management of acute exacerbations of COPD. Guidelines recommend obtaining arterial blood samples but these are more difficult to obtain than venous. We assessed whether blood gas values derived from venous blood could replace arterial at initial assessment.
Methods: Patients requiring hospital treatment for an exacerbation of COPD had paired arterial and venous samples taken. Bland–Altman analyses were performed to assess agreement between arterial and venous pH, CO2 and . The relationship between SpO2 and SaO2 was assessed. The number of attempts and pain scores for each sample were measured.
Results: 234 patients were studied. There was good agreement between arterial and venous measures of pH and (mean difference 0.03 and −0.04, limits of agreement −0.05 to 0.11 and −2.90 to 2.82, respectively), and between SaO2 and SpO2 (in patients with an SpO2 of >80%). Arterial sampling required more attempts and was more painful than venous (mean pain score 4 (IQR 2–5) and 1 (IQR 0–2), respectively, p<0.001).
Conclusions: Arterial sampling is more difficult and more painful than venous sampling. There is good agreement between pH and values derived from venous and arterial blood, and between pulse oximetry and arterial blood gas oxygen saturations. These agreements could allow the initial assessment of COPD exacerbations to be based on venous blood gas analysis and pulse oximetry, simplifying the care pathway and improving the patient experience
The Brief Solastalgia Scale: A Psychometric Evaluation and Revision
Witnessing degradation and loss to one’s home environment can cause the negative emotional experience of solastalgia. We review the psychometric properties of the 9-item Solastalgia subscale from the Environmental Distress Scale (Higginbotham et al. (EcoHealth 3:245–254, 2006)). Using data collected from three large, independent, adult samples (N = 4229), who were surveyed soon after the 2019/20 Australian bushfires, factor analyses confirmed the scale’s unidimensionality, while analyses derived from Item Response Theory highlighted the poor psychometric performance and redundant content of specific items. Consequently, we recommend a short-form scale consisting of five items. This Brief Solastalgia Scale (BSS) yielded excellent model fit and internal consistency in both the initial and cross-validation samples. The BSS and its parent version provide very similar patterns of associations with demographic, health, life satisfaction, climate emotion, and nature connectedness variables. Finally, multi-group confirmatory factor analysis demonstrated comparable construct architecture (i.e. configural, metric, and scalar invariance) across validation samples, gender categories, and age. As individuals and communities increasingly confront and cope with climate change and its consequences, understanding related emotional impacts is crucial. The BSS promises to aid researchers, decision makers, and practitioners to understand and support those affected by negative environmental change
Persistent symptoms after COVID-19 are not associated with differential SARS-CoV-2 antibody or T cell immunity
Among the unknowns in decoding the pathogenesis of SARS-CoV-2 persistent symptoms in Long Covid is whether there is a contributory role of abnormal immunity during acute infection. It has been proposed that Long Covid is a consequence of either an excessive or inadequate initial immune response. Here, we analyze SARS-CoV-2 humoral and cellular immunity in 86 healthcare workers with laboratory confirmed mild or asymptomatic SARS-CoV-2 infection during the first wave. Symptom questionnaires allow stratification into those with persistent symptoms and those without for comparison. During the period up to 18-weeks post-infection, we observe no difference in antibody responses to spike RBD or nucleoprotein, virus neutralization, or T cell responses. Also, there is no difference in the profile of antibody waning. Analysis at 1-year, after two vaccine doses, comparing those with persistent symptoms to those without, again shows similar SARS-CoV-2 immunity. Thus, quantitative differences in these measured parameters of SARS-CoV-2 adaptive immunity following mild or asymptomatic acute infection are unlikely to have contributed to Long Covid causality. ClinicalTrials.gov (NCT04318314)
Environment Orientation : a structured simulation approach for agent-based complex systems
Complex systems are collections of independent agents interacting with each other and with their environment to produce emergent behaviour. Agent-based computer simulation is one of the main ways of studying complex systems. A naive approach to such simulation can fare poorly, due to large communication overhead, and due to the scope for deadlock between the interacting agents sharing a computational platform. Agent interaction can instead be considered entirely from the point of view of the environment(s) within which the agents interact. Structuring a simulation using such Environment Orientation leads to a simulation that reduces communication overhead, that is effectively deadlock-free, and yet still behaves in the manner required. Additionally the Environment Orientation architecture eases the development of more sophisticated large-scale simulations, with multiple kinds of complex agents, situated in and interacting with multiple kinds of environments. We describe the Environment Orientation simulation architecture. We report on a number of experiments that demonstrate the effectiveness of the Environment Orientation approach: a simple flocking system, a flocking system with multiple sensory environments, and a flocking system in an external environment
Induced pseudoscalar coupling of the proton weak interaction
The induced pseudoscalar coupling is the least well known of the weak
coupling constants of the proton's charged--current interaction. Its size is
dictated by chiral symmetry arguments, and its measurement represents an
important test of quantum chromodynamics at low energies. During the past
decade a large body of new data relevant to the coupling has been
accumulated. This data includes measurements of radiative and non radiative
muon capture on targets ranging from hydrogen and few--nucleon systems to
complex nuclei. Herein the authors review the theoretical underpinnings of
, the experimental studies of , and the procedures and uncertainties
in extracting the coupling from data. Current puzzles are highlighted and
future opportunities are discussed.Comment: 58 pages, Latex, Revtex4, prepared for Reviews of Modern Physic
Neural Network Mechanisms Underlying Stimulus Driven Variability Reduction
It is well established that the variability of the neural activity across trials, as measured by the Fano factor, is elevated. This fact poses limits on information encoding by the neural activity. However, a series of recent neurophysiological experiments have changed this traditional view. Single cell recordings across a variety of species, brain areas, brain states and stimulus conditions demonstrate a remarkable reduction of the neural variability when an external stimulation is applied and when attention is allocated towards a stimulus within a neuron's receptive field, suggesting an enhancement of information encoding. Using an heterogeneously connected neural network model whose dynamics exhibits multiple attractors, we demonstrate here how this variability reduction can arise from a network effect. In the spontaneous state, we show that the high degree of neural variability is mainly due to fluctuation-driven excursions from attractor to attractor. This occurs when, in the parameter space, the network working point is around the bifurcation allowing multistable attractors. The application of an external excitatory drive by stimulation or attention stabilizes one specific attractor, eliminating in this way the transitions between the different attractors and resulting in a net decrease in neural variability over trials. Importantly, non-responsive neurons also exhibit a reduction of variability. Finally, this reduced variability is found to arise from an increased regularity of the neural spike trains. In conclusion, these results suggest that the variability reduction under stimulation and attention is a property of neural circuits
Molecular responses of European flounder (Platichthys flesus) chronically exposed to contaminated estuarine sediments
Molecular responses to acute toxicant exposure can be effective biomarkers, however responses to chronic exposure are less well characterised. The aim of this study was to determine chronic molecular responses to environmental mixtures in a controlled laboratory setting, free from the additional variability encountered with environmental sampling of wild organisms. Flounder fish were exposed in mesocosms for seven months to a contaminated estuarine sediment made by mixing material from the Forth (high organics) and Tyne (high metals and tributyltin) estuaries (FT) or a reference sediment from the Ythan estuary (Y). Chemical analyses demonstrated that FT sediment contained significantly higher concentrations of key environmental pollutants (including polycyclic aromatic hydrocarbons (PAHs), chlorinated biphenyls and heavy metals) than Y sediment, but that chronically exposed flounder showed a lack of differential accumulation of contaminants, including heavy metals. Biliary 1-hydroxypyrene concentration and erythrocyte DNA damage increased in FT-exposed fish. Transcriptomic and 1H NMR metabolomic analyses of liver tissues detected small but statistically significant alterations between fish exposed to different sediments. These highlighted perturbance of immune response and apoptotic pathways, but there was a lack of response from traditional biomarker genes. Gene-chemical association annotation enrichment analyses suggested that polycyclic aromatic hydrocarbons were a major class of toxicants affecting the molecular responses of the exposed fish. This demonstrated that molecular responses of sentinel organisms can be detected after chronic mixed toxicant exposure and that these can be informative of key components of the mixture
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Identifying causes of Western Pacific ITCZ drift in ECMWF System 4 hindcasts
The development of systematic biases in climate models used in operational seasonal forecasting adversely affects the quality of forecasts they produce. In this study, we examine the initial evolution of systematic biases in the ECMWF System 4 forecast model, and isolate aspects of the model simulations that lead to the development of these biases. We focus on the tendency of the simulated intertropical convergence zone in the western equatorial Pacific to drift northwards by between 0.5° and 3° of latitude depending on season. Comparing observations with both fully coupled atmosphere–ocean hindcasts and atmosphere-only hindcasts (driven by observed sea-surface temperatures), we show that the northward drift is caused by a cooling of the sea-surface temperature on the Equator. The cooling is associated with anomalous easterly wind stress and excessive evaporation during the first twenty days of hindcast, both of which occur whether air-sea interactions are permitted or not. The easterly wind bias develops immediately after initialisation throughout the lower troposphere; a westerly bias develops in the upper troposphere after about ten days of hindcast. At this point, the baroclinic structure of the wind bias suggests coupling with errors in convective heating, although the initial wind bias is barotropic in structure and appears to have an alternative origin
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