5,944 research outputs found

    Triaxial digital fluxgate magnetometer for NASA applications explorer mission: Results of tests of critical elements

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    Tests performed to prove the critical elements of the triaxial digital fluxgate magnetometer design were described. A method for improving the linearity of the analog to digital converter portion of the instrument was studied in detail. A sawtooth waveform was added to the signal being measured before the A/D conversion, and averaging the digital readings over one cycle of the sawtooth. It was intended to reduce bit error nonlinearities present in the A/D converter which could be expected to be as much as 16 gamma if not reduced. No such nonlinearities were detected in the output of the instrument which included the feature designed to reduce these nonlinearities. However, a small scale nonlinearity of plus or minus 2 gamma with a 64 gamma repetition rate was observed in the unit tested. A design improvement intended to eliminate this small scale nonlinearity was examined

    The host galaxies of luminous radio-quiet quasars

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    We present the results of a deep K-band imaging study which reveals the host galaxies around a sample of luminous radio-quiet quasars. The K-band images, obtained at UKIRT, are of sufficient quality to allow accurate modelling of the underlying host galaxy. Initially, the basic structure of the hosts is revealed using a modified Clean deconvolution routine optimised for this analysis. 2 of the 14 quasars are shown to have host galaxies with violently disturbed morphologies which cannot be modelled by smooth elliptical profiles. For the remainder of our sample, 2D models of the host and nuclear component are fitted to the images using the chi-squared statistic to determine goodness of fit. Host galaxies are detected around all of the quasars. The reliability of the modelling is extensively tested, and we find the host luminosity to be well constrained for 9 quasars. The derived average K-band absolute K-corrected host galaxy magnitude for these luminous radio-quiet quasars is =-25.15+/-0.04, slightly more luminous than an L* galaxy. The spread of derived host galaxy luminosities is small, although the spread of nuclear-to-host ratios is not. These host luminosities are shown to be comparable to those derived from samples of quasars of lower total luminosity and we conclude that there is no correlation between host and nuclear luminosity for these quasars. Nuclear-to-host ratios break the lower limit previously suggested from studies of lower nuclear luminosity quasars and Seyfert galaxies. Morphologies are less certain but, on the scales probed by these images, some hosts appear to be dominated by spheroids but others appear to have disk-dominated profiles.Comment: 16 pages, 8 figures, revised version to be published in MNRA

    NICMOS Observations of Low-Redshift Quasar Host Galaxies

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    We have obtained Near-Infrared Camera and Multi-Object Spectrometer images of 16 radio quiet quasars observed as part of a project to investigate the ``luminosity/host-mass limit.'' The limit results were presented in McLeod, Rieke, & Storrie-Lombardi (1999). In this paper, we present the images themselves, along with 1- and 2-dimensional analyses of the host galaxy properties. We find that our model-independent 1D technique is reliable for use on ground-based data at low redshifts; that many radio-quiet quasars live in deVaucouleurs-law hosts, although some of the techniques used to determine host type are questionable; that complex structure is found in many of the hosts, but that there are some hosts that are very smooth and symmetric; and that the nuclei radiate at ~2-20% of the Eddington rate based on the assumption that all galaxies have central black holes with a constant mass fraction of 0.6%. Despite targeting hard-to-resolve hosts, we have failed to find any that imply super-Eddington accretion rates.Comment: To appear in ApJ, 28 pages including degraded figures. Download the paper with full-resolutio figures from http://www.astro.wellesley.edu/kmcleod/mm.p

    An exploration into the client at the heart of therapy : a qualitative perspective

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    Over 50 years ago Eysenck challenged the existing base of research into psychotherapy. Since that time, a large number of investigations have been conducted to verify the efficacy of therapy. Recently however, an increasing number of studies have cast new doubts on this research base. Instead of therapy being a function of the therapist, it is now becoming ever more apparent that the client plays a prime role in the therapeutic process. The qualitative studies presented in this paper provide some examples of research that demonstrates that clients are actively involved in their therapy, even making counselling work despite their counsellor. These studies suggest that clients may not experience therapy as beneficially as traditional outcome studies indicate. This raises a new challenge to researchers to more fully explore the client's experience of therapy, a challenge to which qualitative methods of inquiry would appear well suited

    A feasibility study: Forest Fire Advanced System Technology (FFAST)

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    The National Aeronautics and Space Administration/Jet Propulsion Laboratory and the United States Department of Agriculture Forest Service completed a feasibility study that examined the potential uses of advanced technology in forest fires mapping and detection. The current and future (1990's) information needs in forest fire management were determined through interviews. Analysis shows that integrated information gathering and processing is needed. The emerging technologies that were surveyed and identified as possible candidates for use in an end to end system include ""push broom'' sensor arrays, automatic georeferencing, satellite communication links, near real or real time image processing, and data integration. Matching the user requirements and the technologies yielded a ""strawman'' system configuration. The feasibility study recommends and outlines the implementation of the next phase for this project, a two year, conceptual design phase to define a system that warrants continued development

    Quasars and Ultraluminous Infrared Galaxies: At the Limit?

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    We have detected the host galaxies of 16 nearby, radio-quiet quasars using images obtained with the Near-Infrared Camera and Multi-Object Spectrometer (NICMOS). We confirm that these luminous quasars tend to live in luminous, early-type host galaxies, and we use the host-galaxy magnitudes to refine the luminosity/host-mass limit inferred from ground-based studies. If quasars obey the relation Mblackhole/Mspheroid∼0.006M_{black hole}/M_{spheroid}\sim0.006 found for massive dark objects in nonactive galaxies, then our analysis implies that they radiate at up to ∼20\sim20% of the Eddington rate. An analogous analysis for ultraluminous infrared galaxies shows them to accrete at up to similar Eddington fractions, consistent with the hypothesis that some of them are powered by embedded quasars.Comment: 9 pages, includes 2 eps figs, accepted to ApJLet

    The development of the forms of responding to self-critical thoughts Scale (FoReST)

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    Background: Self-critical thoughts are a feature of many mental health problems. Adopting a psychologically flexible response to thoughts has been highlighted as a key determinant of wellbeing. But, the measurement of psychological flexibility (PF) in relation to self-critical thoughts is under-developed. This paper reports on the development of the Forms of Responding to Self-Critical Thoughts Scale (FoReST). Method: Study One involved the development and exploratory factor analysis of the FoReST in a convenience sample of 253 non-clinical adults. Study Two was a confirmatory factor analysis study of the FoReST in a sample of 110 University students. Study 3 explored the convergent and concurrent validity of the FoReST by examining associations with measures of similar constructs (PF, self-compassion, self-criticism) and relevant mental health measures (anxiety, depression, distress). Study 3 also explored the FoReST’s incremental validity for predicting depression and anxiety levels beyond an established measure of self-critical thinking. Results: In Study One, exploratory factor analysis produced a 9-item/2-factor solution (unworkable action and mindful acceptance). The measure demonstrated good internal consistency. In Study 2, the confirmatory factor analysis also indicated a 2-factor model (unworkable action and mindful acceptance) and overall internal consistency that was excellent. In Study Three, the FoReST demonstrated high convergent validity with similar measures, and good concurrent validity with mental health outcomes. Analyses also indicated good incremental validity for the FoReST for predicting HADS depression and anxiety scores. Conclusions: The FoReST appears to be a psychometrically sound measure suitable for measuring change processes in third wave therapies such as Acceptance and Commitment Therapy, Mindfulness-based Interventions and Compassion Focused therapy

    Migration and multiple sclerosis in immigrants to Australia from United Kingdom and Ireland: a reassessment. I. Risk of MS by age at immigration

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    A previous study of the prevalence of multiple sclerosis (MS) in 1981 among immigrants from the United Kingdom and Ireland to Australia found that the prevalence for those with age at immigration (AAI) under 15 years of age did not differ from the older immigrants. We have reanalysed the original materials as well as census data for 1901–1981 for UKI and other high MS risk country immigrants. There was a highly significant trend in the prevalence rates of all Australians from New South Wales (NSW) to South Australia (SA) to Western Australia (WA) to Queensland (QLD). Rates by state among the Australian-born were almost identical to these, but there was no prevalence gradient for the UKI-born. The denominator population at risk of MS by AAI was calculated from special census tables of length of residence in Australia by age 0–79 in 1981 for UKI immigrants 1947–1981. The numerator was limited to the subset of 258 MS (Group II) also immigrating in 1947 and later, and age 0–79 in 1981. The absolute risk of MS for these migrants to the four states entering at age 0–14 was 22/100,000, significantly less than for all older age groups; age 15–39 immigrants had a risk of 54/100,000. Similar risk ratios for 0–14 versus 15–39 by state were 31 versus 61 (NSW), 29 versus 44 (QLD), 11 versus 50 (SA), 15 versus 51 (WA)
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