Springer correspondences for dihedral groups

Recent work by a number of people has shown that complex reflection groups give rise to many representation-theoretic structures (e.g., generic degrees and families of characters), as though they were Weyl groups of algebraic groups. Conjecturally, these structures are actually describing the representation theory of as-yet undescribed objects called ''spetses'', of which reductive algebraic groups ought to be a special case. In this paper, we carry out the Lusztig--Shoji algorithm for calculating Green functions for the dihedral groups. With a suitable set-up, the output of this algorithm turns out to satisfy all the integrality and positivity conditions that hold in the Weyl group case, so we may think of it as describing the geometry of the ''unipotent variety'' associated to a spets. From this, we determine the possible ''Springer correspondences'', and we show that, as is true for algebraic groups, each special piece is rationally smooth, as is the full unipotent variety.Comment: 21 page

A bijection between Littlewood-Richardson tableaux and rigged configurations

A bijection is defined from Littlewood-Richardson tableaux to rigged configurations. It is shown that this map preserves the appropriate statistics, thereby proving a quasi-particle expression for the generalized Kostka polynomials, which are q-analogues of multiplicities in tensor products of irreducible general linear group modules indexed by rectangular partitions.Comment: 66 pages, AMS-LaTeX, requires xy.sty and related file

Turning Point Scotland's Housing First Project Evaluation: Final Report

GIS maps are one kind of complex display in which people search for targets. Recent studies have shown that the choice of colour-scales when displaying these maps has important implications for people's strategies in searching these displays (Donnelly, Cave, Welland & Menneer, 2006). The current study follows up on this research. Observers searched for multiple targets in each display. Two targets were red and two were blue, and targets were not very salient. Observers searched until all targets were found. This often took several seconds and many fixations. The order in hich observers found targets suggested that they were more reliant on search for particular colours under some color-scales than under others. What will be presented here is a number of oculomotor measures used to explore how search was guided in the displays: the degree to which fixations clustered around targets, the image characteristics of regions of the display that were fixated, and goodness of fit to fixation distributions of Itti & Koch saliency maps, where the features used to compute saliency were varied. The goal was to see which measures would best pick up on differences in what guided search through complex display

The Implications of Flexible Staffing Arrangements for Job Stability

In this paper, we examine the job stability of workers in a wide range of flexible staffing arrangements: agency temporary, direct-hire temporary, on-call, contract company, independent contractor, and regular part-time work. We draw upon two data sources in our analysis. The first is a nationwide survey of employers on their use of flexible staffing arrangements conducted by the Upjohn Institute for Employment Research. This survey provides evidence on why employers use various types of flexible staffing arrangements and the extent to which employers move workers in these positions into regular arrangements within their organization. The second data source is the Supplement to the February 1995 Current Population Survey on Contingent and Alternative Work Arrangements. Exploiting the longitudinal component of the CPS, we compare the subsequent labor market status of individuals in flexible work arrangements and those in regular full-time positions in February 1995. We find that, except for independent contractors, workers in flexible staffing arrangements have less job stability than those in regular full-time arrangements in the sense that they are more likely to switch employers, become unemployed, or involuntarily drop out of the labor force within a year. However, the degree of job stability varies considerably across arrangements. We also show that the recent growth in certain types of flexible staffing arrangements could have translated into small declines in aggregate job stability and can account for a substantial share of the modest increase in job switching observed over the last decade.flexible, staffing, job, stability, Houseman, Polivka

Stellar Clusters in NGC 1313: Evidence for Infant Mortality

We present evidence that infant mortality of stellar clusters is likely to be a major and very efficient process for the dissolution of young clusters in the spiral galaxy NGC 1313. Performing stellar PSF photometry on archival HST/ACS images of the galaxy, we find that a large fraction of early B-type stars are seen outside of star clusters and well spread within the galactic disk, consistent with the scenario of infant mortality. We also calculate the UV flux produced by the stars in and out the clusters and find that 75 to 90% of the UV flux in NGC 1313 is produced by stars outside the clusters. These results suggest that the infant mortality of star clusters is probably the underlying cause of the diffuse UV emission in starburst galaxies. Infant mortality would also explain the numerous B-type stars observed in the background field of our Galaxy as well. We exclude the possibility that unresolved low-mass star clusters and scaled OB associations might be the main source for the diffuse UV emission.Comment: 5 pages, 3 figures, accepted for publication in the Astrophysical Journal Letter

Evolution and relationships of the conifer seed cone telemachus: Evidence from the triassic of antarctica

The seed cone Telemachus is known from several Triassic localities in Gondwana. New specimens from two localities in Antarctica provide additional information about the type species, Telemachus elongatus, based on details of morphology and anatomy revealed by using a modified transfer technique on the compressed plants. Seed cones of T. elongatus are up to 6.0 cm long and characterized by conspicuous, elongate bracts. A second Antarctic species, described here as Telemachus antarcticus, is segregated, based on a shorter bract and differences in cone size. Newly recognized features of the genus include the shape, size, and disposition of the ovules; vascularization of the ovuliferous complex; and scale and bract histology. As a result of this new information, it is now possible to compare Telemachus with the permineralized Middle Triassic conifer seed cone Parasciadopitys from the Central Transantarctic Mountains. The similarities between the two genera make it possible to relate organs in different preservational modes and to develop a more complete concept for this widely distributed Gondwana conifer. Placing the Telemachus plant within a phylogenetic context makes it possible to evaluate the relationship with other so-called transitional conifers, an informal group that has been interpreted as intermediate between Paleozoic and modern conifers.Fil: Escapa, Ignacio Hernán. University of Kansas; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Decombeix, Anne-Laure. University of Kansas; Estados UnidosFil: Taylor, Edith L.. University of Kansas; Estados UnidosFil: Taylor, Thomas N.. University of Kansas; Estados Unido

Decreasing Medical Complications for Total Knee Arthroplasty: Effect of Critical Pathways on Outcomes

BACKGROUND: Studies on critical pathway use have demonstrated decreased length of stay and cost without compromise in quality of care. However, pathway effectiveness is difficult to determine given methodological flaws, such as small or single center cohorts. We studied the effect of critical pathways on total knee replacement outcomes in a large population-based study. METHODS: We identified hospitals in four US states that performed total knee replacements. We sent a questionnaire to surgical administrators in these hospitals including items about critical pathway use and hospital characteristics potentially related to outcomes. Patient data were obtained from Medicare claims, including demographics, comorbidities, 90-day postoperative complications and length of hospital stay. The principal outcome measure was the risk of having one or more postoperative complications. RESULTS: Two hundred ninety five hospitals (73%) responded to the questionnaire, with 201 reporting the use of critical pathways. 9,157 Medicare beneficiaries underwent TKR in these hospitals with a mean age of 74 years (± 5.8). After adjusting for both patient and hospital related variables, patients in hospitals with pathways were 32% less likely to have a postoperative complication compared to patients in hospitals without pathways (OR 0.68, 95% CI 0.50-0.92). Patients managed on a critical pathway had an average length of stay 0.5 days (95% CI 0.3-0.6) shorter than patients not managed on a pathway. CONCLUSION: Medicare patients undergoing total knee replacement surgery in hospitals that used critical pathways had fewer postoperative complications than patients in hospitals without pathways, even after adjusting for patient and hospital related factors. This study has helped to establish that critical pathway use is associated with lower rates of postoperative mortality and complications following total knee replacement after adjusting for measured variables