Spectroscopic confirmation of a white dwarf companion to the B star 16 Dra

Using an Extreme Ultraviolet Explorer (EUVE) spectrum, we confirm the identification of a white dwarf companion to the B9.5V star 16 Dra (HD150100), and constrain its surface temperature to lie between 29,000K and 35,000K. This is the third B star + white dwarf non-interacting Sirius-type binary to be confirmed, after y Pup (HR2875, HD59635) and theta Hya (HR3665, HD79469). 16 Dra and its white dwarf companion are members of a larger resolved proper motion system including the B9V star 17 Dra A (HD150117). The white dwarf must have evolved from a progenitor more massive than this star, i.e. ~3.7 solar masses. White dwarf companions to B stars are important since they set an observational limit on the maximum mass for white dwarf progenitors, and can potentially be used to investigate the high mass ends of the initial-final mass relation and the white dwarf mass-radius relation.Comment: Accepted for publication in A&A, 22nd May 200

Theta Hya: Spectroscopic identification of a second B star + white dwarf binary

We report the identification, in an Extreme Ultraviolet Explorer (EUVE) spectrum, of a hot white dwarf companion to the 3rd magnitude late-B star Theta Hya (HR3665, HD79469). This is the second B star + white dwarf binary to be conclusively identified; Vennes, Berghofer and Christian (1997), and Burleigh and Barstow (1998) had previously reported the spectroscopic discovery of a hot white dwarf companion to the B5V star y Pup (HR2875). Since these two degenerate stars must have evolved from main sequence progenitors more massive than their B star companions, they can be used to place observational lower limits on the maximum mass for white dwarf progenitors, and to investigate the upper end of the initial-final mass relation. Assuming a pure hydrogen composition, we constrain the temperature of the white dwarf companion to Theta Hya to lie between 25,000K and 31,000K. We also predict that a third bright B star, 16 Dra (B9.5V), might also be hiding an unresolved hot white dwarf companion.Comment: 4 pages, 1 figure. Accepted for publication in Astronomy and Astrophysic

Inferring Species Trees from Incongruent Multi-Copy Gene Trees Using the Robinson-Foulds Distance

We present a new method for inferring species trees from multi-copy gene trees. Our method is based on a generalization of the Robinson-Foulds (RF) distance to multi-labeled trees (mul-trees), i.e., gene trees in which multiple leaves can have the same label. Unlike most previous phylogenetic methods using gene trees, this method does not assume that gene tree incongruence is caused by a single, specific biological process, such as gene duplication and loss, deep coalescence, or lateral gene transfer. We prove that it is NP-hard to compute the RF distance between two mul-trees, but it is easy to calculate the generalized RF distance between a mul-tree and a singly-labeled tree. Motivated by this observation, we formulate the RF supertree problem for mul-trees (MulRF), which takes a collection of mul-trees and constructs a species tree that minimizes the total RF distance from the input mul-trees. We present a fast heuristic algorithm for the MulRF supertree problem. Simulation experiments demonstrate that the MulRF method produces more accurate species trees than gene tree parsimony methods when incongruence is caused by gene tree error, duplications and losses, and/or lateral gene transfer. Furthermore, the MulRF heuristic runs quickly on data sets containing hundreds of trees with up to a hundred taxa.Comment: 16 pages, 11 figure

A Survey for Photometric Variability in Isolated Magnetic White Dwarfs—Measuring their Spin Periods

We present the initial findings of a photometric survey of isolated magnetic white dwarfs (MWDs) carried out with the 1.0m Jacobus Kapteyn Telescope. Of our sample of 30 MWDs, we have observed variability in 17 (57%) over our observed timescales (minutes to years), with a further 11 requiring more data, and two that are non-variable at the 1% level. In total we have discovered possible variability in 15 targets that has not been reported before in the literature, and we have measured the spin period of five objects in our sample to within a few percent. We find no correlation between spin period, mass or temperature, but there may be a weak negative correlation between period and field strength for the short-period targets. We have identified 14 MWDs with low field strengths and low temperatures, which are candidates for having star spots on their surfaces and should be followed up with polarimetry. We have also found that three low-field, high temperature MWDs are unexpectedly variable, with no obvious mechanism to cause this

A search for hidden white dwarfs in the ROSAT EUV survey II: Discovery of a distant DA+F6/7V binary system in a direction of low density neutral hydrogen

We report the results of our final search for hot white dwarfs in unresolved, Sirius-type, binary systems with IUE. One new system, RE J0500-364 (DA+F6/7V), has been identified. This star appears to lie at a distance of between 500-1000pc, making it one of the most distant white dwarfs, if not the most distant, to be detected in the EUV surveys. The very low line-of-sight neutral hydrogen volume density to this object could place a lower limit on the length of the Beta CMa interstellar tunnel of diffuse gas, which stretches away from the Local Bubble in a similar direction to RE J0500-364.Comment: 1 LaTex file plus 15 figures; accepted for publication in Monthly Notices of the Royal Astronomical Societ

A Gift For My Favorite Man

Too often, choosing a gift for your favorite man can become a panic instead of a pleasure. Should I even get him a present?-How much should I spend?-What would he like? There\u27s no better way to find the answers than to ask the source of your dilemma-the· men themselves. That\u27s just what the Homemaker staff did, and their quizzing of a cross-section of Iowa State men turned up the following gift-buying guides

Education Leaders’ Perceptions of Faculty Ethical Decision-Making: Awareness, Learning, and Change

Conversations about ethical decision-making exist in a climate of misinformation within social and political forums. The issue of ethical decision-making in the context of educational leadership within a school environment has not been recently investigated. The purpose of this qualitative exploratory case study was to examine the perceptions of education leaders who observed the processes faculty employed when ethical decision-making commenced throughout the school day. Data was collected during interviews with education leaders who answered semi-structured, open-ended questions. The findings led the leaders to self-reflect, redefining their roles as authentic leaders and a gaining a deeper understanding of school culture, thus helping create systemic change

Understanding Roles and Relationships: Teachers’ Work in a Northern Ontario Remote First Nations Community

This article explores how teachers negotiate their roles and relationships in a Northern Ontario First Nations community. Through a case study approach, utilizing interviews and focus groups with 15 participants, I constructed four categories: (1) pedestal people, (2) educational transitioners, (3) relationship builders, and (4) community integrators, for the purpose of explaining the ways in which teachers navigate their roles and relationships in the community and the implications for their work as teachers. I argue that community integrators embody an understanding of Indigenous approaches, centralized in relational knowing and being, and model a practice most efficacious for Indigenous student success. Keywords: Indigenous education, relationships, teachers’ workCet article explore la manière dont les enseignants négocient leurs rôles et leurs relations dans une communauté des Premières Nations du nord de l’Ontario. En utilisant une approche basée sur des études de cas, par le moyen d’entretiens individuels et de groupes de discussion composés de 15 participants, je distingue quatre catégories : (a) les personnes sur un piédestal, (b) les éducateurs en transition, (c) les bâtisseurs de relations, et (d) les intégrateurs de communauté, pour expliquer les façons dont les enseignants gèrent leurs rôles et leurs relations dans la communauté, et les implications pour leur travail en tant qu’enseignants. Je soutiens que les intégrateurs de communauté incarnent une compréhension des approches autochtones centralisée sur la relation de l’être et du savoir, et modélisent une pratique plus efficace pour la réussite des étudiants autochtones.Mots-clés : éducation autochtone, relations, travail des enseignant

Addressing the Educational Needs of Occupational Therapists Regarding Sexuality in an Acute Care Setting

Despite the knowledge that sexuality is an important factor of well-being for individuals with disabilities, occupational therapists (OTs) continue to under-address this topic with clients (McGrath & Sakellariou, 2016). Additional education on sexuality may help OTs improve their knowledge and confidence in discussing and addressing sexuality with clients during intervention. The purpose of this study is to determine the educational needs of occupational therapists working in acute care who are alumnus of Elizabethtown College to promote the discussion of sexuality in practice. The research questions of the project are: 1) Do OTs in acute care educate clients on sexuality? 2) What methods do they typically use to provide this education? 3) What are the educational needs and preferences of acute care therapists? Participants completed an anonymous online survey with questions related to their knowledge levels regarding sexuality, current comfort level addressing and educating needs and preferences related to sexuality. Survey questions were developed using principles of Adult Learning Theory, which states adult learners are self-directed, experienced, and motivated to learn (Rothwell, 2008). Survey responses were analyzed and reviewed for common trends, which included a perceived lack of education, difficulty initiating discussion, an openness to learn more information, and a perceived lack of time in the acute care setting. This information was utilized to create an educational resource for therapists to be distributed by the researcher