The VLA Low-frequency Sky Survey

The Very Large Array (VLA) Low-frequency Sky Survey (VLSS) has imaged 95% of the 3*pi sr of sky north of declination = -30 degrees at a frequency of 74 MHz (4 meter wavelength). The resolution is 80" (FWHM) throughout, and the typical RMS noise level is ~0.1 Jy/beam. The typical point-source detection limit is 0.7 Jy/beam and so far nearly 70,000 sources have been catalogued. This survey used the 74 MHz system added to the VLA in 1998. It required new imaging algorithms to remove the large ionospheric distortions at this very low frequency throughout the entire ~11.9 degree field of view. This paper describes the observation and data reduction methods used for the VLSS and presents the survey images and source catalog. All of the calibrated images and the source catalog are available online (http://lwa.nrl.navy.mil/VLSS) for use by the astronomical community.Comment: 53 pages, including 3 tables and 15 figures. Has been accepted for publication in the Astronomical Journa

Cognitive-behavioural therapy for deliberate self-harm

This thesis describes the outcomes of a randomized controlled trial of a Cognitive Behavioural Therapy (CBT) intervention for patients who engage in Deliberate Self-Harm (DSH). The CBT intervention was designed to supplement usual care following an episode of DSH. The study involved 90 people (95% females), aged 15–35 years, who were randomly assigned to CBT in addition to treatment as usual (TAU) or to treatment as usual only. The main study hypothesis, that CBT in addition to TAU would be more effective in reducing repetition of DSH than TAU only, was supported. Furthermore, those who received CBT in addition to TAU were shown to have significantly greater reductions in depression, anxiety and suicidal cognitions, and significantly greater improvements in self-esteem and problem solving ability. It is reasonable to assume that these positive findings are attributable to the effect of the CBT, given the random assignment as well as the absence of between group differences with respect to demographics, DSH, history of DSH, psychopathology and use of health care services. It is encouraging that these results are found for people with recurrent and chronic DSH, with high risk of repetition, and with high levels of psychiatric co-morbidity.LEI Universiteit LeidenSupport for the study was provided by The Netherlands Organisation for Health Research and Development (ZonMw) (contract grant number: 2100.0068).FSW - Self-regulation models for health behavior and Psychopathology - Ou

Four Extreme Relic Radio Sources in Clusters of Galaxies

(Abridged) We describe the results of the highest-resolution radio observations yet made of four relic radio sources in the Abell clusters A13, A85, A133 and A4038. Our VLA images at 1.4 GHz with 4" resolution show a remarkable variety of fine structure in the form of spectacular arcs, wisps, plumes and loops. Their integrated radio flux densities fall very rapidly with frequency, with power-law slopes between 2.1 and 4.4 near 1.4 GHz The relics possess linear polarization levels ranging between 2.3 % (A133) and 35 % (A85); the higher polarization fractions imply a highly ordered magnetic field in the fine structure and low differential Faraday rotation in the intervening cluster gas. The optical identification of host galaxies remains problematic. In A85, A133 and A4038 the travel times for the brightest cluster galaxies are significantly longer than the modeled ages of the relics and nearby bright ellipticals provide a better match. Excess X-ray emission in the 0.5 keV-to-2 keV band was found near the relics in A85 and A133. The surface brightness was too high to be attributed to the inverse-Compton mechanism alone. We found excellent fits to the broad-band radio spectra using the anisotropic (KGKP) model of spectral ageing, and we have extended the model to include diffusion of particles between regions of different field strength (the Murgia-JP, or MJP, model). The steep radio spectra imply ages for the relics of ~ 10^8 yr, at the start of which period their radio luminosities would have been ~ 10^25 W/Hz at 1.4 GHz.Comment: 43 pages, 13 figures, AJ, Sep 2001 (accepted

Childhood sexual abuse differentially predicts outcome of cognitive-behavioral therapy for deliberate self-harm.

De samenhang tussen somatische en psychische (dys)functie

Emotion regulation as mediator of treatment outcome in therapy for deliberate self-harm.

De samenhang tussen somatische en psychische (dys)functie

The 74MHz System on the Very Large Array

The Naval Research Laboratory and the National Radio Astronomy Observatory completed implementation of a low frequency capability on the VLA at 73.8 MHz in 1998. This frequency band offers unprecedented sensitivity (~25 mJy/beam) and resolution (~25 arcsec) for low-frequency observations. We review the hardware, the calibration and imaging strategies, comparing them to those at higher frequencies, including aspects of interference excision and wide-field imaging. Ionospheric phase fluctuations pose the major difficulty in calibrating the array. Over restricted fields of view or at times of extremely quiescent ionospheric ``weather'', an angle-invariant calibration strategy can be used. In this approach a single phase correction is devised for each antenna, typically via self-calibration. Over larger fields of view or at times of more normal ionospheric ``weather'' when the ionospheric isoplanatic patch size is smaller than the field of view, we adopt a field-based strategy in which the phase correction depends upon location within the field of view. This second calibration strategy was implemented by modeling the ionosphere above the array using Zernike polynomials. Images of 3C sources of moderate strength are provided as examples of routine, angle-invariant calibration and imaging. Flux density measurements indicate that the 74 MHz flux scale at the VLA is stable to a few percent, and tied to the Baars et al. value of Cygnus A at the 5 percent level. We also present an example of a wide-field image, devoid of bright objects and containing hundreds of weaker sources, constructed from the field-based calibration. We close with a summary of lessons the 74 MHz system offers as a model for new and developing low-frequency telescopes. (Abridged)Comment: 73 pages, 46 jpeg figures, to appear in ApJ

X-ray and Radio Interactions in the Cores of Cooling Flow Clusters

We present high resolution ROSAT x-ray and radio observations of three cooling flow clusters containing steep spectrum radio sources at their cores. All three systems exhibit strong signs of interaction between the radio plasma and the hot intracluster medium. Two clusters, A133 and A2626, show enhanced x-ray emission spatially coincident with the radio source whereas the third cluster, A2052, exhibits a large region of x-ray excess surrounding much of the radio source. Using 3-D numerical simulations, we show that a perturbed jet propagating through a cooling flow atmosphere can give rise to amorphous radio morphologies, particularly in the case where the jet was ``turned off'' and allowed to age passively. In addition, the simulated x-ray surface brightness produced both excesses and deficits as seen observationally.Comment: 25 pages, 10 figures, accepted for publication in A

A literature review of the training offered to qualified prescribers to use electronic prescribing systems: why is it so important?

Objectives A key element of the implementation and ongoing use of an electronic prescribing (ePrescribing) system is ensuring that users are, and remain, sufficiently trained to use the system. Studies have suggested that insufficient training is associated with suboptimal use. However, it is not clear from these studies how clinicians are trained to use ePrescribing systems or the effectiveness of different approaches. We sought to describe the various approaches used to train qualified prescribers on ePrescribing systems and to identify whether users were educated about the pitfalls and challenges of using these systems. Methods We performed a literature review, using a systematic approach across three large databases: Cumulative Index Nursing and Allied Health Literature, Embase and Medline were searched for relevant English language articles. Articles that explored the training of qualified prescribers on ePrescribing systems in a hospital setting were included. Key findings Our search of ‘all training’ approaches returned 1155 publications, of which seven were included. A separate search of ‘online’ training found three relevant publications. Training methods in the ‘all training’ category included clinical scenarios, demonstrations and assessments. Regarding ‘online’ training approaches; a team at the University of Victoria in Canada developed a portal containing simulated versions of electronic health records, where individuals could prescribe for fictitious patients. Educating prescribers about the challenges and pitfalls of electronic systems was rarely discussed. Conclusions A number of methods are used to train prescribers; however, the lack of papers retrieved suggests a need for additional studies to inform training methods