Abundances determined using Si II and Si III in B-type stars: evidence for stratification

It is becoming clear that determination of the abundance of Si using lines of Si II and Si III can lead to quite discordant results in mid to late B-type stars. The difference between the Si abundances derived from the two ion states can exceed one dex in some cases. We have carried out a study intended to clarify which kinds of B stars exhibit this discrepancy, to try to identify regularities in the phenomenon, and to explore possible explanations such as abundance stratification by comparing models to observed spectra. We used spectra from the ESPaDOnS spectropolarimeter and FEROS spectrograph, supplemented with spectra from the ESO and ELODIE archives, of magnetic Bp, HgMn, and normal B-type stars ranging in effective temperature from about 10500 to 15000 K. Using these spectra, we derived abundances using the spectrum synthesis program ZEEMAN which can take into account the influence of magnetic fields. For each star, accurate abundances of Si II, Si III, Ti, Cr, and Fe were derived. All magnetic Bp stars in our sample show a discordance between the derived abundances of the first and second ions of silicon, with the latter being between 0.6 - 1.7 dex higher. The same behaviour is observed in the non-magnetic stars but to a much smaller extent: Si III is enhanced by between 0.3 - 0.8 dex compared to Si II.We do not detect the discrepancy in three stars, HD 22136 (normal), HD 57608 (HgMn) and HD 27295 (HgMn); these are the only stars in our sample for which the microturbulence parameter is significantly different from zero, and which therefore probably have convection occurring in their atmospheres. We find that vertical stratification of silicon in the atmospheres of B-type stars may provide an explanation of this phenomenon, but our detailed stratification models do not completely explain the discrepancies, which may, in part, be due to non-LTE effects.Comment: 9 pages, 2 figures, accepted for publication in A&

Cognitive, Ideological, and Goal-Pursuit Barriers to Ethical Decision Making

This paper brings together diverse research findings to suggest that there are several cognitive, ideological, and goal-pursuit barriers that often get in the way of ethical decision-making. The barriers lead managers to give little or no conscious attention to the ethical implications of their actions. The barriers that I categorize and describe are overconfidence, cognitively “filling-in” of missing information, social norm beliefs, ethical fixed mindsets, metaphors in-use, fairness and justice ideology, behavioral scripts, goal-fever (teleopathy), and goal framing. I describe the processes and mechanisms that underlie these barriers to increase awareness of them so that the willing manager may be better equipped to prevent unwanted effects. Most managers desire to do good work and behave ethically. Sometimes they make decisions and behave in ways that are unintentionally unethical. This paper helps to address that problem. Often, decisions involving more routine and less effortful consideration end up getting made without concern for the ethical implications. Throughout this paper the barriers are described and explained, business examples are provided, and suggestions for remedial steps are offered

The atmospheric chemistry of magnetic Bp stars

The chemically peculiar magnetic A- and B-type (Ap/Bp) stars are characterised by large overabundances, of the order of 10^2 and 10^4 times the Sun, of Fe-peak and rare earth elements, respectively. Further, they possess strong, ordered magnetic fields (of order 1 kG) that are roughly dipolar in nature. We present in-depth investigations of magnetic Ap/Bp stars, ranging from detailed analyses of specific stars to larger surveys aimed at studying stratification and atmospheric abundance evolution. For HD 133880 and HD 147010, we offer complete investigations of their magnetic fields and chemical abundance distributions. For each star, a simple magnetic field model is derived, from both line-of-sight and surface magnetic field measurements, that consists of dipole, quadrupole and octupole components. Abundance analysis is then performed using ZEEMAN, a spectrum synthesis program that takes into account the effects of the magnetic field. Discrepant results between abundances derived from Si II and Si III in B-type stars has been documented in the literature. We report on the first comprehensive study of this phenomenon in various classes of B-type stars (including the non-magnetic HgMn and normal stars and magnetic Bp stars) ranging in effective temperature from about 11000 to 15000 K. We interpret the results in the context of vertical stratification in the atmospheres of these stars. The abundance anomalies that exist in magnetic Ap/Bp stars are known to be produced by diffusion processes, when the gravitational settling of ions competes with radiative levitation. However, nothing is known about how these abundance anomalies may evolve during the main sequence lifetime of these stars. We present an extensive study of the atmospheric abundances for several elements of magnetic Ap/Bp stars, that are members of open clusters or associations (and therefore have well-determined ages), and attempt to interpret the results in the context of diffusion

A Program Evaluation of a Local School District’s Bullying Prevention Program

This research study provides a complete program evaluation on a school district in Texas to determine the overall success of their bullying prevention program. The research focuses on qualitative and quantitative data that included principal interviews, district and campus discipline data and results from a quality survey used by the district over several years. This case study also focuses on preventive measures and disciplinary consequences used by the district and campuses in order to reduce the number of bullying incidents and provide a safer school environment for students and staff. Based on the program evaluation, the district showed success in several areas of the program, especially around reduction in incidents of bullying behavior that result in disciplinary consequences. The district studied also exhibited positive safety results as assessed through a quality survey used across most campuses and levels. Implications for leadership, bullying intervention strategies, and future studies are discussed in closing

Molecular Systematics of Red Algae.

Phylogenetic analyses of nucleotide sequences for the nuclear-encoded small subunit ribosomal RNA (SSU) gene were used to test current hypotheses of relationships within the Corallinales and among the florideophycidaean orders of red algae. Analyses of SSU gene sequences indicate that the order Corallinales includes four major lineages. The Sporolithaceae is resolved as the earliest-diverging lineage within the order and forms the sister group to a monophyletic Corallinaceae. The molecular data also support the monophyly of the subfamilies Melobesioideae and Corallinoideae. The latter subfamily is inferred as sister to a fourth lineage including non-geniculate and geniculate species classified in the subfamilies Mastophoroideae, Metagoniolithoideae, Lithophylloideae, and Amphiroideae. Genicula are inferred to have arisen independently in three separate lineages and are not homologous structures. These results indicate that the common taxonomic practice of separating corallines on the basis of the presence or absence of genicula does not accurately reflect the evolutionary history of the group. Cladistic analysis of SSU gene sequences indicates that the Florideophycidae is a monophyletic taxon comprised, roughly, of two large sister clades. One clade includes all orders possessing pit plugs with two cap layers. Within this assemblage, the orders Corallinales and Rhodogorgonales are inferred to be closely related. The second florideophycidaean clade includes, with the exception of the Gelidiales, those orders in which pit plugs are characterized by the absence of cap layers and the presence of a cap membrane. These results support Pueschel\u27s (1994) contention that: (1) naked pit plugs are the plesiomorphic type in the Rhodophyta, (2) all orders possessing pit plugs with two cap layers are derived from a common ancestor, (3) outer cap layers are homologous structures, and (4) domed outer caps and cap membranes are derived features within the two cap layer lineage. Results also indicate that although the inner cap layers found in the Bangiales, Hildenbrandiales, and the two-cap-layer lineage may be homologous, inner caps in the Gelidiales are independently derived

An Ecological Study of the Cumberland Plateau Salamander, Plethodon kentucki Mittleman, in West Virginia

A study was conducted to determine various aspects of the ecology of Plethodon kentucki in West Virginia. Results of studies on range and distribution revealed that P. kentucki is limited to southwestern counties in West Virginia. A population of P. kentucki at Beech Fork State Park was extremely seasonal with regard to activity. Seasonal activity was not significantly correlated with air temperature, soil temperature, air relative humidity, or soil pH. Seasonal activity was significantly correlated with soil moisture. Critical Thermal Maxima and dehydration values were not significantly different between f· kentucki and its congener, P. glutinosus, thus each is equally well adapted to temperature and moisture conditions in West Virginia. Environmental conditions (temperature and moisture) do not explain the absence of f kentucki in northern counties where P. glutinosus is abundant. Plethodon kentucki was most active between 9:00 and 10:00PM EST. Linear movements were measured at 1.32 m for a juvenile, and 1.81 m for an adult female. Rocks (47.9%) were utilized as cover objects more frequently than leaves (20.8%) and logs (4.2%). Crevices beneath exposed roots of living trees were important microhabitats for P. kentucki (27.1%). Individuals of P. kentucki were found more frequently on west-facing slopes (44.8%) than on southwest- (31.0%) and northwest-facing slopes (14.6%). Based on results of laboratory studies, competition occurs between f. kentucki and f. glutinosus in West Virginia. Plethodon glutinosus was more territorial in nature, and was considered the dominant competitor. Competition apparently plays a key role in limiting the range and distribution of P. kentucki in West Virginia. The stomachs of 70 P. kentucki and 79 f· glutionsus were analyzed for food contents. Prey selection was significantly correlated, thus indicating a high degree of similarity in feeding habits for the two species. Hymenopterans were found in stomachs of both species more frequently than any other prey type (f. · 71.4% ; f. g. 54.4%), followed by coleopterans (f. k. 40.0% ; f· g. 32.9%) and gastropods (f. · 30.0% ; f· g. 30.4%). Food appears to be a resource for which these two species compete. Head width was not significantly different for the two species. Prey size probably does not partition feeding habits, and thus probably increases the intensity of competition for food between P. kentucki and P. glutinosus