Abundances of PNe in the Outer Disk of M31

We present spectroscopic observations and chemical abundances of 16 planetary nebulae (PNe) in the outer disk of M31. The [O III] 4363 line is detected in all objects, allowing a direct measurement of the nebular temperature essential for accurate abundance determinations. Our results show that the abundances in these M31 PNe display the same correlations and general behaviors as Type II PNe in the Milky Way Galaxy. We also calculate photoionization models to derive estimates of central star properties. From these we infer that our sample PNe, all near the peak of the Planetary Nebula Luminosity Function, originated from stars near 2 M_sun. Finally, under the assumption that these PNe are located in M31's disk, we plot the oxygen abundance gradient, which appears shallower than the gradient in the Milky Way.Comment: 48 pages, including 12 figures and 8 tables, accepted by Astrophysical Journa

Positive experiences of UNF students: A mixed-method model.

Positive psychology is becoming of increasing interest in recent years and topics such as happiness, subjective well-being, life satisfaction are being examined in many areas of psychology (Quick et al, 2007; Simmons& Nelson, 2006). Many large scale studies are being conducted by survey researchers globally to understand these constructs. In addition there is also a lot of interest in examining positive dispositional variables such as Flow, Vigor and Engagement. In this study we looked at the positive experiences students have at UNF and the positive emotions associated with these experiences. We used an online survey on Qualtrics and studied the specific conditions that promote a positive climate for student learning. We also looked at how the perceptions of these positive experiences as well as positive emotions. We also examine how these are related to some dispositional variables such as Flow, Vigor and Engagement. Both qualitative and quantitative methods were used to collect the data. The first method attempted to identify specific incidents that made students experience positive stress. The second uses structured questionnaires to collect data on their dispositions. The results were analyzed both qualitatively and quantitatively

Crc Is Involved in Catabolite Repression Control of the bkd Operons of Pseudomonas putida and Pseudomonas aeruginosa

Crc (catabolite repression control) protein of Pseudomonas aeruginosa has shown to be involved in carbon regulation of several pathways. In this study, the role of Crc in catabolite repression control has been studied in Pseudomonas putida. The bkd operons of P. putida and P. aeruginosa encode the inducible multienzyme complex branched-chain keto acid dehydrogenase, which is regulated in both species by catabolite repression. We report here that this effect is mediated in both species by Crc. A 13-kb cloned DNA fragment containing the P. putida crc gene region was sequenced. Crc regulates the expression of branched-chain keto acid dehydrogenase, glucose-6-phosphate dehydrogenase, and amidase in both species but not urocanase, although the carbon sources responsible for catabolite repression in the two species differ. Transposon mutants affected in their expression of BkdR, the transcriptional activator of the bkd operon, were isolated and identified as crc and vacB (rnr) mutants. These mutants suggested that catabolite repression in pseudomonads might, in part, involve control of BkdR levels. Originally published Journal of Bacteriology, Vol. 182, No. 4, Feb 200