A biological survey of the Rappahannock River, Virginia

Also part of series: Special report from the Virginia Fisheries Laboratory ; no.6.Also referred to as the Rappahannock River Survey

The Metallicity-Luminosity Relation, Effective Yields, and Metal Loss in Spiral and Irregular Galaxies

I present results on the correlation between galaxy mass, luminosity, and metallicity for a sample of spiral and irregular galaxies having well-measured abundance profiles, distances, and rotation speeds. Additional data for low surface brightness galaxies from the literature are also included for comparison. These data are combined to study the metallicity-luminosity and metallicity-rotation speed correlations for spiral and irregular galaxies. The metallicity luminosity correlation shows its familiar form for these galaxies, a roughly uniform change in the average present-day O/H abundance of about a factor 100 over 11 magnitudes in B luminosity. However, the O/H - V(rot) relation shows a change in slope at a rotation speed of about 125 km/sec. At faster V(rot), there appears to be no relation between average metallicity and rotation speed. At lower V(rot), the metallicity correlates with rotation speed. This change in behavior could be the result of increasing loss of metals from the smaller galaxies in supernova-driven winds. This idea is tested by looking at the variation in effective yield, derived from observed abundances and gas fractions assuming closed box chemical evolution. The effective yields derived for spiral and irregular galaxies increase by a factor of 10-20 from V(rot) approximately 5 km/sec to V(rot) approximately 300 km/sec, asympotically increasing to approximately constant y(eff) for V(rot) > 150 km/sec. The trend suggests that galaxies with V(rot) < 100-150 km/sec may lose a large fraction of their SN ejecta, while galaxies above this value tend to retain metals.Comment: 40 pages total, including 7 encapsulated postscript figures. Accepted for publication in 20 Dec 2002 Ap

Number of Borderline Personality Disorder Criteria and Depression Predict Poor Functioning and Quality of Life in Outpatient Youth.

This study aimed to investigate which factors contribute to poor functioning and poor quality of life in youth (aged 15-25 years) with borderline personality disorder (BPD), and whether the number of BPD criteria might be an independent predictor of these outcomes. A sample of 499 help-seeking outpatient youth, aged 15-25 years, was assessed. Stepwise multiple regression analyses showed that the number of BPD criteria was the best predictor of poor functioning, followed by number of mental health visits in the past month, female sex, and a current diagnosis of depression. Current depression was the best predictor of Assessment of Quality of Life utility score, followed by the number of BPD criteria. These findings underscore the clinical significance of DSM-IV BPD features (even when subthreshold for a categorical diagnosis) in youth and their effects upon social and occupational functioning and quality of life early in the course of BPD

The clinical significance of subthreshold borderline personality disorder features in outpatient youth

Studies among adult patients have found that subthreshold borderline personality disorder (BPD) features are associated with elevated psychosocial morbidity compared with patients with no BPD features. However, the clinical significance of subthreshold features of BPD has not been investigated among real-world patients during the clinical emergence of the disorder, which is usually between puberty and emerging adulthood. This study aimed to replicate and extend previous research by comparing outpatient youth aged 15-25 years with subthreshold BPD features with youth with no BPD features. The sample included 499 potential participants, of whom 111 had no DSM-IV BPD features at all, and 155 had between one and four features. Results indicated that the group with subthreshold BPD features had more severe mental illness and poorer social and occupational functioning. These findings suggest that subthreshold BPD features are clinically important and should be a focus of clinical intervention to reduce continuing disability and improve outcome