Chemical composition of B-type supergiants in the OB8, OB10, OB48, OB78 associations of M31

Absolute and differential chemical abundances are presented for the largest group of massive stars in M31 studied to date. These results were derived from intermediate resolution spectra of seven B-type supergiants, lying within four OB associations covering a galactocentric distance of 5 - 12 kpc. The results are mainly based on an LTE analysis, and we additionally present a full non-LTE, unified model atmosphere analysis of one star (OB78-277) to demonstrate the reliability of the differential LTE technique. A comparison of the stellar oxygen abundance with that of previous nebular results shows that there is an offset of between ~0.15 - 0.4 dex between the two methods which is critically dependent on the empirical calibration adopted for the R23 parameter with [O/H]. However within the typical errors of the stellar and nebular analyses (and given the strength of dependence of the nebular results on the calibration used) the oxygen abundances determined in each method are fairly consistent. We determine the radial oxygen abundance gradient from these stars, and do not detect any systematic gradient across this galactocentric range. We find that the inner regions of M31 are not, as previously thought, very 'metal rich'. Our abundances of C, N, O, Mg, Si, Al, S and Fe in the M31 supergiants are very similar to those of massive stars in the solar neighbourhood.Comment: 15 pages, 9 figures and 9 tables. Submitted to A&A April 200

Perceptions of the effects of professional

The purpose of this study was to describe teacher perceptions of the effects of Professional Learning Communities (PLCs), as designed by common planning of core subjects among high school teachers, on teacher efficacy in the public schools of North Georgia. The study sought to answer the following research questions: (1) Is there a difference in teacher selfefficacy as measured by the Teacher's Sense of Efficacy Scale (TSES) between high school teachers who participate in Professional Learning Communities linked with the organizational structure of common core planning and those who do not? and (2) What differences exist among teachers' description of the effects of common core planning on their teaching practices and on their self-efficacy? The first question was answered using the TSES. The second research question was answered through interviews with a purposefully selected sample of teachers. This research used mixed methods. Survey and interview data exploring teacher's educational experience in Professional Learning Communities designed with and without common core planning were collected. Survey results provide evidence of a positive relationship between classroom related components of teacher efficacy and Professional Learning Communities linked with the organizational strategy of common core planning among the unit of analysis--the teachers. This study added to the existing body of knowledge about the use of Professional Learning Communities in high schools. Implications for researchers, policy analysis, and practitioners were identified. (Published By University of Alabama Libraries