San Francisco State University

About: San Francisco State University is a education organization based out in San Francisco, California, United States. It is known for research contribution in the topics: Population & Planet. The organization has 5669 authors who have published 11433 publications receiving 408075 citations. The organization is also known as: San Francisco State & San Francisco State Normal School.

The Brown Dwarf Desert at 75-1200 AU

Abstract: We present results of a comprehensive infrared coronagraphic search for substellar companions to nearby stars. The research consisted of (1) a 178-star survey at Steward and Lick observatories, with optical follow-up from Keck Observatory, capable of detecting companions with masses greater than 30 MJ, and semimajor axes between about 140 to 1200 AU; (2) a 102-star survey using the Keck Telescope, capable of detecting extrasolar brown dwarfs and planets typically more massive than 10 MJ, with semimajor axes between about 75 and 300 AU. Only one brown dwarf companion was detected, and no planets. The frequency of brown dwarf companions to G, K, and M stars orbiting between 75 and 300 AU is measured to be 1% ± 1%, the most precise measurement of this quantity to date. The frequency of massive (greater than 30 MJ) brown dwarf companions at 120–1200 AU is found to be f = 0.7% ± 0.7%. The frequency of giant planet companions with masses between 5 and 10 MJ orbiting between 75 and 300 AU is measured here for the first time to be no more than ~3%. Together with other surveys that encompass a wide range of orbital separations, these results imply that substellar objects with masses between 12 and 75 MJ form only rarely as companions to stars. Theories of star formation that could explain these data are only now beginning to emerge.

Hardiness training facilitates performance in college

Abstract: In 25 years of research and practice, hardiness has emerged as a pattern of attitudes and skills that is a pathway to resilience under stressful circumstances. As such, it is important to determine whether hardiness can be trained, and if such training improves performance and health. The few relevant studies available thus far have suggested this training effectiveness among working adults and students. Furthering this theme, the present study involves a large sample of undergraduate students, comparing those who experienced hardiness training as a regular credit course, with those who went through other courses taught by the same teachers. At the beginning of the courses, these two groups did not differ in demographics, hardiness levels, or grade-point-average (GPA). At the end of the courses, the Hardiness Training Group showed higher levels of hardiness, and GPA than did the Comparison Group. This improvement in GPA for the Hardiness Training Group persisted over the following 2-year period, even cont...

Mountain lion and human activity in California: Testing speculations

Abstract: We compiled and analyzed 24 years (1972-1995) of verified incidents of mountain lions killing domestic animals (n = 2,663) to examine trend, distribution, and types of conflicts in California. To model the relationships between mountain lion depredation and various human activity and habitat factors, we tested 2 predictive models. Domestic sheep depredation in counties was significantly (P< 0.05) related to amount of suitable mountain lion habitat. We hypothesize that increasing domestic sheep depredation may reflect regional increases in the distribution and abundance of mountain lions. A regression model of percent pet depredation indicated a significant (P < 0.05) association with average annual new house development (1979-1993). Counties with significant pet depredation are in the same regions where public safety problems have occurred and reflect a radiation of human activity into mountain lion habitat. Mountain lion depredation data may be a useful index of regional mountain lion activity. Livestock and pet depredation problems are increasing in different regions of the state for different reasons; pet depredations are increasing the most rapidly. Pet depredation may be a useful indicator of mountain lion proximity to humans.