On the kinematic evolution of young local associations and the Sco-Cen complex

Context: Over the last decade, several groups of young (mainly low-mass) stars have been discovered in the solar neighbourhood (closer than ~100 pc), thanks to cross-correlation between X-ray, optical spectroscopy and kinematic data. These young local associations -- including an important fraction whose members are Hipparcos stars -- offer insights into the star formation process in low-density environments, shed light on the substellar domain, and could have played an important role in the recent history of the local interstellar medium. Aims: To study the kinematic evolution of young local associations and their relation to other young stellar groups and structures in the local interstellar medium, thus casting new light on recent star formation processes in the solar neighbourhood. Methods: We compiled the data published in the literature for young local associations. Using a realistic Galactic potential we integrated the orbits for these associations and the Sco-Cen complex back in time. Results: Combining these data with the spatial structure of the Local Bubble and the spiral structure of the Galaxy, we propose a recent history of star formation in the solar neighbourhood. We suggest that both the Sco-Cen complex and young local associations originated as a result of the impact of the inner spiral arm shock wave against a giant molecular cloud. The core of the giant molecular cloud formed the Sco-Cen complex, and some small cloudlets in a halo around the giant molecular cloud formed young local associations several million years later. We also propose a supernova in young local associations a few million years ago as the most likely candidate to have reheated the Local Bubble to its present temperature.Comment: 27 pages, 13 figures, 14 tables. Accepted for publication in Astronomy & Astrophysic

Constructing and contextualizing a multi-dimensional burnout profile of high school music teachers

Thesis (D.M.A.)--Boston UniversityTeaching music, like other human service professions, can be stressful. For some teachers, excessive stress in the work environment can lead to burnout, a syndrome of Emotional Exhaustion (EE), Depersonalization (Dp), and reduced Personal Accomplishment (PA; Maslach, Jackson, & Leiter, 1996). Well- established negative consequences have been associated with burnout including serious health disorders, workplace withdrawal, and destabilized learning environments. Thus, I undertook this investigation in an effort to add to the literature a more comprehensive understanding of public high school music teachers' burnout by way of developing a multidimensional profile of music teachers' burnout and by comparing music teachers' burnout with burnout of other subject area teachers. A non-random sample of music (n =52), English (n=67), mathematics (n=67), science (n=67), and social studies (n = 38) teachers completed a web-based version of the Maslach Burnout Inventory-Educators Survey (MBI-ES). Music teachers' mean EE was categorized as high and was higher than established norms. Music teachers' mean Dp was categorized as moderate, similar to established norms. Mean PA for music teachers was lower than that reported for the normative sample, indicating a higher than normal sense of personal accomplishment among music teachers who participated in the study. In general, findings in regards to demographic variables were consistent with findings for music teachers overall. However, mean EE was higher for non-itinerant music teachers (n=28) than for itinerant music teachers (n=24), and higher among males (n=35) than among females (n=17). When considered collectively, no difference in categorical burnout was noted between non-music teachers (n=239) and music teachers. Considered discretely, categorized means evidenced greater emotional exhaustion for the music teacher group than for the math and social studies teacher groups. The psychometric properties of the MBI are discussed and further factor validity studies are recommended. In addition, I recommend that researchers focus on teacher stress rather than burnout at the local level. Finally, I recommend that researchers work toward developing practical instruments that can be can used for the assessment of teacher stress and coping resources at the school or district level