2,693 research outputs found
The Solar Neighborhood X: New Nearby Stars in the Southern Sky and Accurate Photometric Distance Estimates for Red Dwarfs
Photometric VRI and spectroscopic (6000-9500 A) observations of high proper
motion stars discovered during the first phase of the SuperCOSMOS RECONS (SCR)
search are used to estimate accurate distances to eight new nearby red dwarfs,
including probable 10 pc sample members SCR 1845-6357 (M8.5V at 4.6 pc), the
binary SCR 0630-7643AB (M6.0VJ at 7.0 pc), and SCR 1138-7721 (M5.0V at 9.4 pc).
Distance estimates are determined using a suite of new photometric color-Mk
relations defined using a robust set of nearby stars with accurate VRIJHK
photometry and trigonometric parallaxes.
These relations are utilized, with optical and infrared photometry, to
estimate distances on a uniform system (generally good to 15%) for two
additional samples of red nearby star candidates: several recently discovered
members of the solar neighborhood, and known faint stars with proper motions in
excess of 1.0"/yr south of DEC = -57.5. Of those without accurate trigonometric
parallax measurements, there are five stars in the first sample and three in
the second that are likely to be within 10 pc. The two nearest are SO 0253+1652
(M7.0V at 3.7 pc) and DEN 1048-3956 (M8.5V at 4.5 pc). When combined with SCR
1845-6357, these three stars together represent the largest increase in the 5
pc sample in several decades.
Red spectra are presented for the red dwarfs and types are given on the
RECONS standard spectral system. Red spectra are also given for two new nearby
white dwarfs for which we estimate distances from the photometry of less than
20 pc -- WD 0141-675 (LHS 145, 9.3 pc) and SCR 2012-5956 (17.4 pc). WD 0141-675
brings the total number of systems nearer than 10 pc discussed in this paper to
12.Comment: accepted to The Astronomical Journal (scheduled for November 2004
issue
The Bolocam Galactic Plane Survey: Survey Description and Data Reduction
We present the Bolocam Galactic Plane Survey (BGPS), a 1.1 mm continuum
survey at 33" effective resolution of 170 square degrees of the Galactic Plane
visible from the northern hemisphere. The survey is contiguous over the range
-10.5 < l < 90.5, |b| < 0.5 and encompasses 133 square degrees, including some
extended regions |b| < 1.5. In addition to the contiguous region, four targeted
regions in the outer Galaxy were observed: IC1396, a region towards the Perseus
Arm, W3/4/5, and Gem OB1. The BGPS has detected approximately 8400 clumps over
the entire area to a limiting non-uniform 1-sigma noise level in the range 11
to 53 mJy/beam in the inner Galaxy. The BGPS source catalog is presented in a
companion paper (Rosolowsky et al. 2010). This paper details the survey
observations and data reduction methods for the images. We discuss in detail
the determination of astrometric and flux density calibration uncertainties and
compare our results to the literature. Data processing algorithms that separate
astronomical signals from time-variable atmospheric fluctuations in the data
time-stream are presented. These algorithms reproduce the structure of the
astronomical sky over a limited range of angular scales and produce artifacts
in the vicinity of bright sources. Based on simulations, we find that extended
emission on scales larger than about 5.9' is nearly completely attenuated (>
90%) and the linear scale at which the attenuation reaches 50% is 3.8'.
Comparison with other millimeter-wave data sets implies a possible systematic
offset in flux calibration, for which no cause has been discovered. This
presentation serves as a companion and guide to the public data release through
NASA's Infrared Processing and Analysis Center (IPAC) Infrared Science Archive
(IRSA). New data releases will be provided through IPAC IRSA with any future
improvements in the reduction.Comment: Accepted for publication in Astrophysical Journal Supplemen
The Solar Neighborhood. XXII. Parallax Results from the CTIOPI 0.9m Program: Trigonometric Parallaxes of 64 Nearby Systems with 0\farcs5 1\farcs0 yr (SLOWMO sample)
We present trigonometric parallaxes of 64 stellar systems with proper motions
between 0\farcs5 yr and 1\farcs0 yr from the ongoing RECONS
(Research Consortium On Nearby Stars) parallax program at CTIO (the Cerro
Tololo Interamerican Observatory). All of the systems are south of DEC ,
and 58 had no previous trigonometric parallaxes. In addition to parallaxes for
the systems, we present proper motions, Johnson-Kron-Cousins photometry,
variability measurements, and spectral types. Nine of the systems are multiple;
we present results for their components, three of which are new astrometric
detections. Of the 64 systems, 56 are within 25 parsecs of the Sun and 52 of
those are in the southern hemisphere, comprising 5.7\% of the total number of
known southern 25 parsec systems.Comment: Figures not inline. Accepted by A
Coastal oceanography and sedimentology in New Zealand, 1967-91.
This paper reviews research that has taken place on physical oceanography and sedimentology on New Zealand's estuaries and the inner shelf since c. 1967. It includes estuarine sedimentation, tidal inlets, beach morphodynamics, nearshore and inner shelf sedimentation, tides and coastal currents, numerical modelling, short-period waves, tsunamis, and storm surges. An extensive reference list covering both published and unpublished material is included. Formal teaching and research programmes dealing with coastal landforms and the processes that shape them were only introduced to New Zealand universities in 1964; the history of the New Zealand Journal of Marine and Freshwater Research parallels and chronicles the development of physical coastal science in New Zealand, most of which has been accomplished in last 25 years
The Solar Neighborhood XXIII CCD Photometric Distance Estimates of SCR Targets -- 77 M Dwarf Systems within 25 Parsecs
We present CCD photometric distance estimates of 100 SCR (SuperCOSMOS RECONS)
systems with 0\farcs18/yr, 28 of which are new discoveries
previously unpublished in this series of papers. These distances are estimated
using a combination of new photometry acquired at CTIO and
magnitudes extracted from 2MASS. The estimates are improvements over those
determined using photographic plate magnitudes from SuperCOSMOS plus
, as presented in the original discovery papers. In total, 77 of the 100
systems investigated are predicted to be within 25 pc. If all 77 systems are
confirmed to have 40 milliarcseconds, this sample would
represent a 23% increase in M dwarf systems nearer than 25 pc in the southern
sky.Comment: 34 pages, 8 figure
A 'real puzzle': the views of patients with epilepsy about the organisation of care
BACKGROUND: Little is known about how individuals who have a diagnosis of epilepsy have experienced healthcare services or their views about how they should best be organised to meet their ongoing needs. METHODS: Focus group interviews. Individuals with epilepsy were identified in 5 practices in Wales: 90 were invited, 40 confirmed attendance and 19 individuals attended interviews in 5 groups of size 6, 5, 4, 3 and 1 (Table 2). Inclusion criteria: individuals with a confirmed diagnosis of epilepsy, aged between 18–65. The exclusion criteria were learning disability or an inability to travel to interview locations. RESULTS: The individuals in these group interviews were not 'epilepsy activists' yet they remained critical in extended discussions about the services encountered during their patient careers, wanting more information and advice about how to adapt to problems, particularly after initial diagnosis, more involvement in decision making, rapid access to expertise, preferably local, and improved communication between clinicians. A central concern was the tendency for concerns to be silenced, either overtly, or covertly by perceived haste, so that they felt marginalised, despite their own claims to own expert personal knowledge. CONCLUSIONS: Users of existing services for epilepsy are critical of current systems, especially the lack of attention given to providing information, psychosocial support and the wishes of patients to participate in decision making. Any reorganisation of services for individuals with epilepsy should take into account these perceived problems as well as try to reconcile the tension between the distant and difficult to access expertise of specialists and the local but unconfident support of generalists. The potential benefit of harnessing information technology to allow better liaison should be investigated
How does study quality affect the results of a diagnostic meta-analysis?
Background: The use of systematic literature review to inform evidence based practice in diagnostics is rapidly expanding. Although the primary diagnostic literature is extensive, studies are often of low methodological quality or poorly reported. There has been no rigorously evaluated, evidence based tool to assess the methodological quality of diagnostic studies. The primary objective of this study was to determine the extent to which variations in the quality of primary studies impact the results of a diagnostic meta-analysis and whether this differs with diagnostic test type. A secondary objective was to contribute to the evaluation of QUADAS, an evidence-based tool for the assessment of quality in diagnostic accuracy studies. Methods: This study was conducted as part of large systematic review of tests used in the diagnosis and further investigation of urinary tract infection (UTI) in children. All studies included in this review were assessed using QUADAS, an evidence-based tool for the assessment of quality in systematic reviews of diagnostic accuracy studies. The impact of individual components of QUADAS on a summary measure of diagnostic accuracy was investigated using regression analysis. The review divided the diagnosis and further investigation of UTI into the following three clinical stages: diagnosis of UTI, localisation of infection, and further investigation of the UTI. Each stage used different types of diagnostic test, which were considered to involve different quality concerns. Results: Many of the studies included in our review were poorly reported. The proportion of QUADAS items fulfilled was similar for studies in different sections of the review. However, as might be expected, the individual items fulfilled differed between the three clinical stages. Regression analysis found that different items showed a strong association with test performance for the different tests evaluated. These differences were observed both within and between the three clinical stages assessed by the review. The results of regression analyses were also affected by whether or not a weighting (by sample size) was applied. Our analysis was severely limited by the completeness of reporting and the differences between the index tests evaluated and the reference standards used to confirm diagnoses in the primary studies. Few tests were evaluated by sufficient studies to allow meaningful use of meta-analytic pooling and investigation of heterogeneity. This meant that further analysis to investigate heterogeneity could only be undertaken using a subset of studies, and that the findings are open to various interpretations. Conclusion: Further work is needed to investigate the influence of methodological quality on the results of diagnostic meta-analyses. Large data sets of well-reported primary studies are needed to address this question. Without significant improvements in the completeness of reporting of primary studies, progress in this area will be limited
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