Dürer polyhedra: the dark side of Melancholia

Dürer's engraving Melencolia I famously includes a perspective view of a solid polyhedral block of which the visible portion is an 8-circuit bounding a pentagon-triple+triangle patch. The polyhedron is usually taken to be a cube truncated on antipodal corners, but an infinity of others are compatible with the visible patch. Construction of all cubic polyhedra compatible with the visible portion (i.e., Dürer Polyhedra) is discussed, explicit graphs and symmetries are listed for small cases ( ≤ 18 vertices) and total counts are given for 10 ≤ vertices ≤ 26

Lists and learners : the importance of university rankings in international graduate student choice

This thesis examines the relationship between two rapidly increasing aspects of the world’s higher education landscape: international student mobility and League Tables and Ranking Systems (LTRS) which evaluate higher education institutions (HEIs). This study utilized results from two recent large-scale student surveys which included over 5000 domestic and international graduate students at 82 HEIs in 19 European Union/European Free Trade Area (EU/EFTA) countries. Two primary areas of differences among respondents were analyzed: 1. Comparisons of the differing levels of importance domestic and international graduate students placed on rankings and other factors in their choice of a HEI. 2. Differences in the importance of rankings among different international graduate student demographic groups (age, country of study, discipline, gender, level of degree program, nationality, region of origin, home country income level). In order to put the quantitative findings from this thesis into context, three background areas are presented. The first provides a conceptual background to international student mobility, by introducing relevant aspects of globalization and internationalization, rationales behind cross-border education, and the scope of student mobility worldwide and in the EU/EFTA region. The second area examines the rise of national and global LTRS. Lastly, prominent theoretical models created to understand domestic and international student decision-making, as well as the results from a comprehensive review of previous student choice studies are discussed. Among the major findings is that in 31 of 36 comparisons, international and domestic graduate students varied significantly in the importance placed on the included choice factors. In regards to LTRS, master and doctoral students from outside the EU/EFTA rated rankings as significantly more important than domestic students in both surveys. International students from the EU/EFTA only rated rankings higher than domestic students in the 2009 survey. The 2007 survey included biology, chemistry, math, and physics graduate students. Degree level and country of study were significant factors associated with the importance placed on rankings among both international students from the EU/EFTA region, and those from outside the region. Students from outside the region also placed significantly greater importance on rankings than the EU/EFTA international students. Comparisons combining those two groups showed significant differences based on nationality, region of origin, and home country income level. Age, gender and discipline did not play a significant role within either group. In the 2009 survey, including economics, political science, and psychology, few significant differences were found in the importance of rankings between or among international students from the EU/EFTA region and those from other countries. While country of study was a significant factor within both groups, discipline was a significant factor only for EU/EFTA students. There was also a small negative correlation with age and the importance placed on rankings by international EU/EFTA doctoral students. Home country income level was a significant factor among the combined group of international students. However, degree level, gender, nationality, and region of origin were not significant for either international group. Multivariate analyses conducted using binary logistic regression were generally consistent with the bivariate analyses presented above for the 2007 and 2009 samples. The major exceptions were that home country income level and country of study were no longer significant predictors of the importance placed on rankings for international students in 2009. Keywords: International Students, University Rankings, Graduate Students, Student Mobility, Student Choic

Service Learning: A Valuable Experience

In this paper, we describe how our department recently incorporated a major service learning component into the curriculum. Specifically, we employed participation in the IRS’s Volunteer Income Tax Assistance (VITA) program as an effective means of experiential and service learning for the past two years for Masters of Accountancy students. We designed a course devoted entirely to serving in a VITA program operated on a local Air Force base. Our experience confirms that service learning can be a powerful tool in teaching. It has enhanced our students’ academic and professional development. It has given significance to our mission and it has strengthened community relationships. However, recent developments have made it difficult for us to maintain this service learning project in its present form. It appears that we, like many other programs, must consider again how to implement service learning as part of our curriculum, but we will do so now with a greater appreciation and enthusiasm for its unique contributions to learning

New methods of testing Lorentz violation in electrodynamics

We investigate experiments that are sensitive to the scalar and parity-odd coefficients for Lorentz violation in the photon sector of the Standard Model Extension (SME). We show that of the classic tests of special relativity, Ives-Stilwell (IS) experiments are sensitive to the scalar coefficient, but at only parts in 10^5 for the state-of-the-art experiment. We then propose asymmetric Mach-Zehnder interferometers with different electromagnetic properties in the two arms, including recycling techniques based on travelling wave resonators to improve the sensitivity. With present technology we estimate that the scalar and parity odd coefficients may be measured at sensitivity better than parts in 10^11 and 10^15 respectively.Comment: Accepted for publication in Phys. Rev.

Watchful Waiting vs. Immediate Transurethral Prostatectomy for Symptomatic Prostatism

The rate of resection for benign prostatic hypertrophy shows considerable variability among small geographic areas. To help inform the decision to recommend prostatectomy to men with prostatism without signs of chronic retention, we performed a decision analysis to compare the expected outcomes with immediate transurethral resection and watchful waiting. Data used in the model originated from the medical literature, Medicare claims data, and patient interview studies. In our base-case for 70-year-old men, immediate surgery resulted in the loss of 1.01 months of life expectancy, but when adjustments were made for quality of life, immediate surgery was favored with a net utility benefit of 2.94 quality-adjusted life-months. However, the analysis was particularly sensitive to the degree of disutility attributed to the index symptoms of prostatism. We conclude that patient preferences should be the dominant factor in the decision whether to recommend prostatectomy

Combinations of idelalisib with rituximab and/or bendamustine in patients with recurrent indolent non-Hodgkin lymphoma

Key Points Combining phosphatidylinositol-3-kinase δ inhibition with rituximab, bendamustine, or both is feasible and active in relapsed iNHL. The safety of novel combinations should be proven in phase 3 trials before adoption in clinical practice.</jats:p

Grazing reduces bee abundance and diversity in saltmarshes by suppressing flowering of key plant species

Global declines in pollinator populations and associated services make it imperative to identify and sensitively manage valuable habitats. Coastal habitats such as saltmarshes can support extensive flowering meadows, but their importance for pollinators, and how this varies with land-use intensity, is poorly understood. We hypothesised that saltmarshes provide important bee foraging habitat, and that livestock grazing either suppresses or enhances its value by reducing the abundance - or increasing the diversity - of flowering plants. To test these hypotheses, we surveyed 11 saltmarshes in Wales (UK) under varying grazing management (long-term ungrazed, extensively grazed, intensively grazed) over three summers and investigated causal pathways linking grazing intensity with bee abundance and diversity using a series of linear mixed models. We also compared observed bee abundances to 11 common terrestrial habitats using national survey data. Grazing reduced bee abundance and richness via reductions in the flower cover of the two key food plants: sea aster Tripolium pannonicum and sea lavender Limonium spp. Grazing also increased flowering plant richness, but the positive effects of flower richness did not compensate for the negative effects of reduced flower cover on bees. Bee abundances were approximately halved in extensively grazed marshes (relative to ungrazed) and halved again in intensively grazed marshes. Saltmarsh flowers were primarily visited by honeybees Apis mellifera and bumblebees Bombus spp. in mid and late summer. Compared to other broad habitat types in Wales, ungrazed saltmarshes ranked highly for honeybees and bumblebees in July-August, but were relatively unimportant for solitary bees. Intensively grazed saltmarshes were amongst the least valuable habitats for all bee types. Under appropriate grazing management, saltmarshes provide a valuable and previously overlooked foraging habitat for bees. The strong effects of livestock grazing identified here are likely to extend geographically given that both livestock grazing and key grazing-sensitive plants are widespread in European saltmarshes. We recommend that long-term ungrazed saltmarshes are protected from grazing, and that grazing is maintained at extensive levels on grazed marshes. In this way, saltmarshes can provide forage for wild and managed bee populations and support ecosystem services

Within-Session Analysis of Amphetamine-Elicited Rotation Behavior Reveals Differences between Young Adult and Middle-Aged F344/BN Rats with Partial Unilateral Striatal Dopamine Depletion

Preclinical modeling of Parkinson's disease using 6-hydroxydopamine (6-OHDA) has been valuable in developing and testing therapeutic strategies. Recent efforts have focused on modeling early stages of disease by infusing 6-OHDA into the striatum. The partial DA depletion that follows intrastriatal 6-OHDA is more variable than the near complete depletion following medial forebrain bundle infusion, and behavioral screening assays are not as well characterized in the partial lesion model. We compared relationships between amphetamine-elicited rotation behavior and DA depletion following intrastriatal 6-OHDA (12.5 μg) in 6 month vs. 18 month F344/BN rats, at 2-weeks and 6-weeks post-lesion. We compared the total number of rotations with within-session (bin-by-bin) parameters of rotation behavior as indicators of DA depletion. Striatal DA depletion was greater in the young adult than in the middle-aged rats at 2 weeks but not at 6 weeks post-lesion. The total number of rotations for the whole session and striatal DA depletion did not differ between the two age groups. Regression analysis revealed a greater relationship between within-session parameters of rotation behavior and DA depletion in the middle-aged group than in the young adult group. These results have implications for estimating DA depletion in preclinical studies using rats of different ages