Weak lensing surveys and the intrinsic correlation of galaxy ellipticities

We explore the possibility that an intrinsic correlation between galaxy ellipticities arising during the galaxy formation process may account for part of the shear signal recently reported by several groups engaged in weak lensing surveys. Using high resolution N-body simulations we measure the projected ellipticities of dark matter halos and their correlations as a function of pair separation. With this simplifying, but not necessarily realistic assumption (halo shapes as a proxy for galaxy shapes), we find a positive detection of correlations up to scales of at least 20 h^-1mpc (limited by the box size). The signal is not strongly affected by variations in the halo finding technique, or by the resolution of the simulations. We translate our 3d results into angular measurements of ellipticity correlation functions and shear variance which can be directly compared to observations. We also measure similar results from simulated angular surveys made by projecting our simulation boxes onto the plane of the sky and applying a radial selection function. Interestingly, the shear variance we measure is a small, but not entirely negligible fraction (from ~10-20 %) of that seen by the observational groups, and the ellipticity correlation functions approximately mimic the functional form expected to be caused by weak lensing. The amplitude depends on the width in redshift of the galaxy distribution. If photometric redshifts are used to pick out a screen of background galaxies with a small width, then the intrinsic correlation may become comparable to the weak lensing signal. Although we are dealing with simulated dark matter halos, whether there is a signal from real galaxies could be checked with a nearby sample with known redshifts.Comment: 12 pages, 11 ps figures, emulateapj.sty, submitted to Ap

Discrepant perceptions of communication, teamwork and situation awareness among surgical team members

Objective To assess surgical team members’ differences in perception of non-technical skills. Design Questionnaire design. Setting Operating theatres (OTs) at one university hospital, three teaching hospitals and one general hospital in the Netherlands. Participants Sixty-six surgeons, 97 OT nurses, 18 anaesthetists and 40 nurse anaesthetists. Methods All surgical team members, of five hospitals, were asked to complete a questionnaire and state their opinion on the current state of communication, teamwork and situation awareness at the OT. Results Ratings for ‘communication’ were significantly different, particularly between surgeons and all other team members (P ? 0.001). The ratings for ‘teamwork’ differed significantly between all team members (P ? 0.005). Within ‘situation awareness’ significant differences were mainly observed for ‘gathering information’ between surgeons and other team members (P < 0.001). Finally, 72–90% of anaesthetists, OT nurses and nurse anaesthetists rated routine team briefings and debriefings as inadequate. Conclusions This study shows discrepancies on many aspects in perception between surgeons and other surgical team members concerning communication, teamwork and situation awareness. Future research needs to ascertain whether these discrepancies are linked to greater risk of adverse events or to process as well as systems failures. Establishing this link would support implementation and use of complex team interventions that intervene at multiple levels of the healthcare systemIndustrial Design Engineerin

Merging Galaxies in the SDSS EDR

We present a new catalog of merging galaxies obtained through an automated systematic search routine. The 1479 new pairs of merging galaxies were found in approximately 462 sq deg of the Sloan Digital Sky Survey Early Data Release (SDSS EDR; Stoughton et al. 2002) photometric data, and the pair catalog is complete for galaxies in the magnitude range 16.0 <= g* <= 20. The selection algorithm, implementing a variation on the original Karachentsev (1972) criteria, proved to be very efficient and fast. Merging galaxies were selected such that the inter-galaxy separations were less than the sum of the component galaxies' radii. We discuss the characteristics of the sample in terms of completeness, pair separation, and the Holmberg effect. We also present an online atlas of images for the SDSS EDR pairs obtained using the corrected frames from the SDSS EDR database. The atlas images also include the relevant data for each pair member. This catalog will be useful for conducting studies of the general characteristics of merging galaxies, their environments, and their component galaxies. The redshifts for a subset of the interacting and merging galaxies and the distribution of angular sizes for these systems indicate the SDSS provides a much deeper sample than almost any other wide-area catalog to date.Comment: 58 pages, which includes 15 figures and 6 tables. Figures 2, 8, 9, 10, 11, 13, and 14 are provided as JPEG files. For online atlas, see http://home.fnal.gov/~sallam/MergePair/ . Accepted for publication in A

Orientation of Galaxies in the Local Supercluster: A Review

The progress of the studies on the orientation of galaxies in the Local Supercluster (LSC) is reviewed and a summary of recent results is given. Following a brief introduction of the LSC, we describe the results of early studies based on two-dimensional analysis, which were mostly not conclusive. We describe next the three-dimensional analysis, which is used widely today. Difficulties and systematic effects are explained and the importance of selection effects is described. Then, results based on the new method and modern databases are given, which are summarized as follows. When the LSC is seen as a whole, galaxy planes tend to align perpendicular to the LSC plane with lenticulars showing the most pronounced tendency. Projections onto the LSC plane of the spin vectors of Virgo cluster member galaxies, and to some extent, those of the total LSC galaxies, tend to point to the Virgo cluster center. This tendency is more pronounced for lenticulars than for spirals. It is suggested that 'field' galaxies, i.e., those which do not belong to groups with more than three members, may be better objects than other galaxies to probe the information at the early epoch of the LSC formation through the analysis of galaxy orientations. Field lenticulars show a pronounced anisotropic distribution of spin vectors in the sense that they lay their spin vectors parallel to the LSC plane while field spirals show an isotropic spin-vector distribution.Comment: 21 pages, 10 figures; Accepted for publication in Astrophysics and Space Scienc

Span of control in supervision of rail track work

The supervision of engineering work on the railways has received relatively little examination despite being both safety-critical in its own right and having wider implications for the successful running of the railways. The present paper is concerned with understanding the factors that make different engineering works perceived as easier or harder to manage. We describe an approach building on notions of ‘span of control’, through which we developed the TOECAP inventory (Team, Organisation, Environment, Communication, Activity and Personal). This tool was validated through both interviews and questionnaires. As well as identifying the physical factors involved, the work also emphasised the importance of collaborative and attitudinal factors. We conclude by discussing limitations of the present work and future directions for development

A longitudinal study of adolescents’ judgments of the attractiveness of facial symmetry, averageness and sexual dimorphism

Adolescents have been found to differ by age in their attraction to facial symmetry, averageness, and sexual dimorphism. However, it has not been demonstrated that attraction to these facial characters changes over time as a consequence of age-linked development. We aimed to extend previous cross-sectional findings by examining whether facial attractiveness judgments change over time during adolescence as a consequence of increasing age, in a within-subjects study of two cohorts of adolescents aged 11–16. Consistent with previous findings, we find that adolescents (often particularly females) judged faces with increased averageness, symmetry and femininity to be more attractive than original, asymmetric and masculine faces, respectively. However, we do not find longitudinal changes in face preference judgments across the course of a year, leading us to question the extent to which some of the previously reported differences in facial attractiveness judgments between younger and older adolescents were due to age-linked changes

Identifying work ability promoting factors for home care aides and assistant nurses

<p>Abstract</p> <p>Background</p> <p>In workplace health promotion, all potential resources needs to be taken into consideration, not only factors relating to the absence of injury and the physical health of the workers, but also psychological aspects. A dynamic balance between the resources of the individual employees and the demands of work is an important prerequisite. In the home care services, there is a noticeable trend towards increased psychosocial strain on employees at work. There are a high frequency of work-related musculoskeletal disorders and injuries, and a low prevalence of sustainable work ability. The aim of this research was to identify factors promoting work ability and self-efficacy in care aides and assistant nurses within home care services.</p> <p>Methods</p> <p>This study is based on cross-sectional data collected in a municipality in northern Sweden. Care aides (n = 58) and assistant nurses (n = 79) replied to a self-administered questionnaire (response rate 46%). Hierarchical multiple regression analyses were performed to assess the influence of several independent variables on self-efficacy (model 1) and work ability (model 2) for care aides and assistant nurses separately.</p> <p>Results</p> <p>Perceptions of personal safety, self-efficacy and musculoskeletal wellbeing contributed to work ability for assistant nurses (R²adj of 0.36, <it>p </it>< 0.001), while for care aides, the safety climate, seniority and age contributed to work ability (R²adj of 0.29, <it>p </it>= 0.001). Self-efficacy was associated with the safety climate and the physical demands of the job in both professions (R²adj of 0.24, <it>p </it>= 0.003 for care aides), and also by sex and age for the assistant nurses (R²adj of 0.31, <it>p </it>< 0.001).</p> <p>Conclusions</p> <p>The intermediate factors contributed differently to work ability in the two professions. Self-efficacy, personal safety and musculoskeletal wellbeing were important for the assistant nurses, while the work ability of the care aides was associated with the safety climate, but also with the non-changeable factors age and seniority. All these factors are important to acknowledge in practice and in further research. Proactive workplace interventions need to focus on potentially modifiable factors such as self-efficacy, safety climate, physical job demands and musculoskeletal wellbeing.</p

Correlations between psychometric schizotypy, scan path length, fixations on the eyes and face recognition.

Psychometric schizotypy in the general population correlates negatively with face recognition accuracy, potentially due to deficits in inhibition, social withdrawal, or eye-movement abnormalities. We report an eye-tracking face recognition study in which participants were required to match one of two faces (target and distractor) to a cue face presented immediately before. All faces could be presented with or without paraphernalia (e.g., hats, glasses, facial hair). Results showed that paraphernalia distracted participants, and that the most distracting condition was when the cue and the distractor face had paraphernalia but the target face did not, while there was no correlation between distractibility and participants' scores on the Schizotypal Personality Questionnaire (SPQ). Schizotypy was negatively correlated with proportion of time fixating on the eyes and positively correlated with not fixating on a feature. It was negatively correlated with scan path length and this variable correlated with face recognition accuracy. These results are interpreted as schizotypal traits being associated with a restricted scan path leading to face recognition deficits