Predictive validity of the HCR-20 for inpatient aggression:the effect of intellectual disability on accuracy

BackgroundPeople with intellectual disability (ID) account for a large proportion of aggressive incidents in secure and forensic psychiatric services. Although the Historical, Clinical, Risk Management 20 (HCR-20) has good predictive validity in inpatient settings, it does not perform equally in all groups and there is little evidence for its efficacy in those with ID.MethodA pseudo-prospective cohort study of the predictive efficacy of the HCR-20 for those with ID (n = 109) was conducted in a UK secure mental health setting using routinely collected risk data. Performance of the HCR-20 in the ID group was compared with a comparison group of adult inpatients without an ID (n = 504). Analysis controlled for potential covariates including security level, length of stay, gender and diagnosis.ResultsThe HCR-20 total score was a significant predictor of any aggression and of physical aggression for both groups, although the area under the curve values did not reach the threshold for a large effect size. The clinical subscale performed significantly better in those without an ID compared with those with. The ID group had a greater number of relevant historical and risk management items. The clinicians' summary judgment significantly predicted both types of aggressive outcomes in the ID group, but did not predict either in those without an ID.ConclusionsThis study demonstrates that, after controlling for a range of potential covariates, the HCR-20 is a significant predictor of inpatient aggression in people with an ID and performs as well as for a comparison group of mentally disordered individuals without ID. The potency of HCR-20 subscales and items varied between the ID and comparison groups suggesting important target areas for improved prediction and risk management interventions in those with ID

Studying dark energy with galaxy cluster surveys

Galaxy cluster surveys provide a powerful means of studying the density and nature of the dark energy. The redshift distribution of detected clusters in a deep, large solid angle SZE or X-ray survey is highly sensitive to the dark energy equation of state. Accurate constraints at the 5% level on the dark energy equation of state require that systematic biases in the mass estimators must be controlled at better than the similar to10% level. Observed regularity in the cluster population and the availability of multiple, independent mass estimators suggests these precise measurements are possible. Using hydrodynamical simulations that include preheating, we show that the level of preheating required to explain local galaxy cluster structure has a dramatic effect on X-ray cluster surveys, but only a mild effect on SZE surveys. This suggests that SZE surveys may be optimal for cosmology while X-ray surveys are well suited for studies of the thermal history of the intracluster medium.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/60610/1/Mohr2002Studying.pd

Depth of interaction and bias voltage depenence of the spectral response in a pixellated CdTe detector operating in time-over-threshold mode subjected to monochromatic X-rays

High stopping power is one of the most important figures of merit for X-ray detectors. CdTe is a promising material but suffers from: material defects, non-ideal charge transport and long range X-ray fluorescence. Those factors reduce the image quality and deteriorate spectral information. In this project we used a monochromatic pencil beam collimated through a 20μm pinhole to measure the detector spectral response in dependance on the depth of interaction. The sensor was a 1mm thick CdTe detector with a pixel pitch of 110μm, bump bonded to a Timepix readout chip operating in Time-Over-Threshold mode. The measurements were carried out at the Extreme Conditions beamline I15 of the Diamond Light Source. The beam was entering the sensor at an angle of \texttildelow20 degrees to the surface and then passed through \texttildelow25 pixels before leaving through the bottom of the sensor. The photon energy was tuned to 77keV giving a variation in the beam intensity of about three orders of magnitude along the beam path. Spectra in Time-over-Threshold (ToT) mode were recorded showing each individual interaction. The bias voltage was varied between -30V and -300V to investigate how the electric field affected the spectral information. For this setup it is worth noticing the large impact of fluorescence. At -300V the photo peak and escape peak are of similar height. For high bias voltages the spectra remains clear throughout the whole depth but for lower voltages as -50V, only the bottom part of the sensor carries spectral information. This is an effect of the low hole mobility and the longer range the electrons have to travel in a low field

Ballistic-electron-emission spectroscopy of Al<SUB>x</SUB>Ga<SUB>1-x</SUB>As/GaAs heterostructures: conduction-band offsets, transport mechanisms, and band-structure effects

We report an extensive investigation of semiconductor band-structure effects in single-barrier AlxGa1-xAs/GaAs heterostructures using ballistic-electron-emission spectroscopy (BEES). The transport mechanisms in these single-barrier structures were studied systematically as a function of temperature and Al composition over the full compositional range (0&#8804;x&#8804;1). The initial (&#915;) BEES thresholds for AlxGa1-xAs single barriers with 0&#8804;x&#8804;0.42 were extracted using a model which includes the complete transmission probability of the metal-semiconductor interface and the semiconductor heterostructure. Band offsets measured by BEES are in good agreement with previous measurements by other techniques which demonstrates the accuracy of this technique. BEES measurements at 77 K give the same band-offset values as at room temperature. When a reverse bias is applied to the heterostructures, the BEES thresholds shift to lower voltages in good agreement with the expected bias-induced band-bending. In the indirect band-gap regime (x&gt;0.45), spectra show a weak ballistic-electron-emission microscopy current contribution due to intervalley scattering through AlxGa1-xAs X valley states. Low-temperature spectra show a marked reduction in this intervalley current component, indicating that intervalley phonon scattering at the GaAs/AlxGa1-xAs interface produces a significant fraction of this X valley current. A comparison of the BEES thresholds with the expected composition dependence of the AlxGa1-xAs &#915;, L, and X points yields good agreement over the entire composition range

Bayesian Analysis of Solar Oscillations

A Bayesian probability based approach is applied to the problem of detecting and parameterizing oscillations in the upper solar atmosphere for the first time. Due to its statistical origin, this method provides a mechanism for determining the number of oscillations present, gives precise estimates of the oscillation parameters with a self-consistent statistical error analysis, and allows the oscillatory model signals to be reconstructed within these errors. A highly desirable feature of the Bayesian approach is the ability to resolve oscillations with extremely small frequency separations. The code is applied to SOHO/CDS (Solar and Heliospheric Observatory/Coronal Diagnostic Spectrometer) O V 629A observations and resolves four distinct P4, P5, P6 and P7 p-modes within the same sunspot transition region. This suggests that a spectrum of photospheric p-modes is able to propagate into the upper atmosphere of the Sun and Sun-like stars, and places precise observational constraints on models of umbral eigen modes.Comment: Accepted for publication in The Astrophysical Journal. It is scheduled for the ApJ July 20, 2008, v682n 1 issu

An experimental evaluation of the benefits and costs of providing fertility information to adolescents and emerging adults

STUDY QUESTION Does the provision of fertility (compared to control) information affect fertility-related knowledge, perceived threat of infertility, anxiety, physical stress and fertility plans in adolescents and emerging adults? SUMMARY ANSWER The provision of fertility information was associated with increased fertility knowledge (emerging adults) and greater infertility threat (adolescents and emerging adults). WHAT IS KNOWN ALREADY According to fertility education research, adolescents and emerging adults know less than they should know about fertility topics. Fertility knowledge can be improved through the provision of information in older adults. STUDY DESIGN, SIZE, DURATION Experimental design. Secondary and university students completed pre-information questionnaires, were randomly assigned via computer to an experimental group, read either fertility (FertiEduc group) or healthy pregnancy information (Control group), and completed post-information questionnaires. Data were collected in group sessions via an online portal. PARTICIPANTS/MATERIALS, SETTING, METHODS Eligible participants were aged 16–18 (adolescents) or 21–24 years (emerging adults), childless, not currently pregnant (for men, partner not pregnant) or trying to conceive, presumed fertile and intending to have a child in the future. Of the 255 invited, 208 (n = 93 adolescents, n = 115 emerging adults) participated. The FertiEduc group received ‘A Guide to Fertility’, four online pages of information about fertility topics (e.g. ‘When are men and women most fertile?’) and the Control group received four online pages from the National Health Service (NHS) pregnancy booklet ‘Baby Bump and Beyond’. Participants completed a questionnaire (fertility knowledge, perceived threat of infertility, anxiety, physical stress and fertility plans, moderators) prior to and after the provision of information. Mixed factorial analysis of variance was used to examine the effects of information provision and hierarchical multiple regression to assess potential moderators of knowledge. MAIN RESULTS AND THE ROLE OF CHANCE The FertiEduc and Control groups were equivalent on age, gender, disability, relationship status and orientation at baseline. Results showed that fertility information significantly increased fertility knowledge for emerging adults only (P < 0.001) and threat of infertility for emerging adults and adolescents (P = 0.05). The moderators were not significant. Participation in the study was associated with an increase in feelings of anxiety but a decrease in physical stress reactions. Adolescents had more optimal fertility plans compared to emerging adults due to being younger. LIMITATIONS, REASONS FOR CAUTION This was an experimental study on a self-selected sample of men and women from selected educational institutions and only short term effects of information were studied. WIDER IMPLICATIONS OF THE FINDINGS Provision of fertility information can have benefits (increased fertility knowledge) but also costs (increase potential threat of infertility). Adolescents find fertility information positive but do not learn from it. Fertility education should be tailored according to age groups and created to minimise negative effects. Longitudinal examination of the effects of fertility information in multi-centre studies is warranted and should include measures of perceived threat of infertility

The Properties of X-ray Cold Fronts in a Statistical Sample of Simulated Galaxy Clusters

We examine the incidence of cold fronts in a large sample of galaxy clusters extracted from a (512h^-1 Mpc) hydrodynamic/N-body cosmological simulation with adiabatic gas physics computed with the Enzo adaptive mesh refinement code. This simulation contains a sample of roughly 4000 galaxy clusters with M > 10^14 M_sun at z=0. For each simulated galaxy cluster, we have created mock 0.3-8.0 keV X-ray observations and spectroscopic-like temperature maps. We have searched these maps with a new automated algorithm to identify the presence of cold fronts in projection. Using a threshold of a minimum of 10 cold front pixels in our images, corresponding to a total comoving length L_cf > 156h^-1 kpc, we find that roughly 10-12% of all projections in a mass-limited sample would be classified as cold front clusters. Interestingly, the fraction of clusters with extended cold front features in our synthetic maps of a mass-limited sample trends only weakly with redshift out to z=1.0. However, when using different selection functions, including a simulated flux limit, the trending with redshift changes significantly. The likelihood of finding cold fronts in the simulated clusters in our sample is a strong function of cluster mass. In clusters with M>7.5x10^14 M_sun the cold front fraction is 40-50%. We also show that the presence of cold fronts is strongly correlated with disturbed morphology as measured by quantitative structure measures. Finally, we find that the incidence of cold fronts in the simulated cluster images is strongly dependent on baryonic physics.Comment: 16 pages, 21 figures, Accepted to Ap

On the statistical detection of propagating waves in polar coronal holes

Waves are important for the heating of the solar corona and the acceleration of the solar wind. We have examined a long spectral time series of a northern coronal hole observed on the 20th October 1996, with the SUMER spectrometer onboard SoHO. The observations were obtained in a transition region N IV 765 A line and in a low coronal Ne VIII 770 A line. Our observations indicate the presence of compressional waves with periods of ~25 min. Using Fourier techniques, we measured the phase delays between intensity as well as velocity oscillations in the two chosen lines. From this we are able to measure the travel time of the propagating oscillations and, hence, the propagation speeds of the waves producing the oscillations. We found that there is a difference in the nature of the propagation in bright ('network') and dark ('internetwork') regions with the latter sometimes showing evidence for downwardly propagating waves that is not seen in the former. As, in all cases, the measured propagation speeds are subsonic, we concluded that the detected waves are slow magnetoacoustic in nature.Comment: 7 pages, 7 figure