Attentional Processes in Children\u27s Overt and Relational Aggression

This study examined attention and memory processes assumed by the social information–processing model to be biased in aggressive children. We also explored whether similar biases were associated with overt and relational ag-gression. A total of 96 fourth through sixth graders saw videos of overtly and relationally aggressive child actors and afterward recalled video content. Par-ticipants\u27 reaction times were also measured as they shifted attention from video content to neutral stimuli. Hierarchical regression analyses showed that, after controlling for processing of nonaggressive stimuli, peer-nominated relational aggression was significantly related to attention shifting and free recall for re-lationally aggressive videos; results were significant after controlling for overt aggression. Peer-nominated overt aggression was related to attention for overtly aggressive videos, but not when relational aggression was controlled. IQ and general attention problems did not explain results. The results suggest that rela- tionally aggressive children are particularly fixated on relationally aggressive events, perhaps because of the socially nuanced nature of relational aggression

L’absentéisme hospitalier au Québec : aspects culturels et socio-démographiques

Cet article porte sur certains aspects de l'absentéisme en milieu hospitalier au Québec. L'intérêt principal ici réside dans la remise en question de certaines pratiques analytiques.Research on sociodemographical and cultural determinants of work absenteeism has been plagued with empirically inconsistent results. It has been suggested that the failure to analyze the data beyond a simple linear bivariate approach, as well as insufficient levels of aggregation (eg: individual without organizational units) is possibly responsible for the inconsistencies.This study was designed to demonstrate these deficiencies. Although the study is limited in scope, an attempt has been made to compare and contrast the different results that could be obtained when a linear, as opposed to interactive, approach is used. And further, it raises many questions concerning the adequacy of published research which attributes absenteeism to sociodemographical characteristics without delving into the real complexity of this phenomenon.Four hundred seven (407) subjects employed in six Québec hospitals, representing a wide variety of occupations, participated in this study. Personal and sociodemographical characteristics were obtained from questionnaires administered in the course of another research project carried out by the authors.The results show a significant difference in absenteeism depending on the level and type of the analysis performed. For example, it is found that the mean absence rate for the ' 'Francophone hospitals" was significantly higher than that of the "Anglophone hospitals". Cultural reasons are advanced to explain these differences.At the individual level of analysis, several findings emerge. First, it is shown that sex is an important determinant of absence behavior. Such finding is consistent with other published results, which point out that women have significantly higher rates of absence than men. Yet, when further analysis is undertaken, the concomitant effects of other related sociodemographic variables are more clearly revealed. For example, married women are absent more often than single women while the opposite tendency is found for men. The combined effect of sex and marital status may point to an explanation of absenteeism in terms of "family social responsibility". This explanation differs from that which might be advanced based on the simple analysis of each of these variables treated independently. Further, bivariate analysis of absence by the level of education, shows an inverse relationship between these two variables. However, when the same analysis is repeated, adjusting for sex, it is found that women have systematically higher rates of absence in each category of education. Other relationships found for income, age and absenteeism are also discussed in the text.The implications of the results are discussed in terms of a research strategy for the conduct of a sociodemographical and cultural study of absenteeism

A geometrical setting for the classification of multilayers

We elaborate on the consequences of the factorization of the transfer matrix of any lossless multilayer in terms of three basic matrices of simple interpretation. By considering the bilinear transformation that this transfer matrix induces in the complex plane, we introduce the concept of multilayer transfer function and study its properties in the unit disk. In this geometrical setting, our factorization translates into three actions that can be viewed as the basic pieces for understanding the multilayer behavior. Additionally, we introduce a simple trace criterion that allows us to classify multilayers in three types with properties closely related to one (and only one) of these three basic matrices. We apply this approach to analyze some practical examples that are representative of these types of matrices.Comment: 8 pages, 5 figures. To be published in J. Opt. Soc. Am.

An improved method for statistical studies of the internal kinematics of HII regions: the case of M 83

We present the integrated Halpha emission line profile for 157 HII regions in the central 3.4' x 3.4' of the galaxy M 83 (NGC 5236). Using the Fabry-Perot interferometer GHaFaS, on the 4.2 m William Herschel on La Palma, we show the importance of a good characterization of the instrumental response function for the study of line profile shapes. The luminosity-velocity dispersion relation is also studied, and in the log(L)-log(sigma) plane we do not find a linear relation, but an upper envelope with equation log(L)=0.9 *log(sigma)+38.1. For the adopted distance of 4.5 Mpc, the upper envelope appears at the luminosity L=10^38.5 ergs, in full agreement with previous studies of other galaxies, reinforcing the idea of using HII regions as standard candles.Comment: 13 pages, 9 figures, accepted for publication in MNRA

Adaptive Optics for Astronomy

Adaptive Optics is a prime example of how progress in observational astronomy can be driven by technological developments. At many observatories it is now considered to be part of a standard instrumentation suite, enabling ground-based telescopes to reach the diffraction limit and thus providing spatial resolution superior to that achievable from space with current or planned satellites. In this review we consider adaptive optics from the astrophysical perspective. We show that adaptive optics has led to important advances in our understanding of a multitude of astrophysical processes, and describe how the requirements from science applications are now driving the development of the next generation of novel adaptive optics techniques.Comment: to appear in ARA&A vol 50, 201

Ground-based astrometry with wide field imagers. V. Application to near-infrared detectors: HAWK-I@VLT/ESO

High-precision astrometry requires accurate point-spread function modeling and accurate geometric-distortion corrections. This paper demonstrates that it is possible to achieve both requirements with data collected at the high acuity wide-field K-band imager (HAWK-I), a wide-field imager installed at the Nasmyth focus of UT4/VLT ESO 8m telescope. Our final astrometric precision reaches ~3 mas per coordinate for a well-exposed star in a single image with a systematic error less than 0.1 mas. We constructed calibrated astro-photometric catalogs and atlases of seven fields: the Baade's Window, NGC 6656, NGC 6121, NGC 6822, NGC 6388, NGC 104, and the James Webb Space Telescope calibration field in the Large Magellanic Cloud. We make these catalogs and images electronically available to the community. Furthermore, as a demonstration of the efficacy of our approach, we combined archival material taken with the optical wide-field imager at the MPI/ESO 2.2m with HAWK-I observations. We showed that we are able to achieve an excellent separation between cluster members and field objects for NGC 6656 and NGC 6121 with a time base-line of about 8 years. Using both HST and HAWK-I data, we also study the radial distribution of the SGB populations in NGC 6656 and conclude that the radial trend is flat within our uncertainty. We also provide membership probabilities for most of the stars in NGC 6656 and NGC 6121 catalogs and estimate membership for the published variable stars in these two fields.Comment: 36 pages (included appendix), 13 tables, 35 figures (26 in low resolution), accepted for publication in Astronomy and Astrophysics. Online materials will be soon available on CDS. Meanwhile, online materials can be requested directly to the first autho

The Disks of Galaxies with Seyfert and Starburst Nuclei: II. Near-Infrared Structural Properties

We have derived the near-infrared structural components of a sample of Seyfert and starburst (SBN) host galaxies by fitting the images of Hunt et al. (1997,ApJS,108,229) with a new two-dimensional decomposition algorithm. An analysis of the fitted parameters shows that Seyfert 1 and SBN bulges resemble normal early-type bulges in structure and color, with (J-K)^c_b about 0.1 mag redder than disk (J-K)^c_d. Seyfert 2 bulges, instead, are bluer than normal with (J-K)^c_b ~ (J-K)^c_d. Seyfert disks (especially Type 1), but not those of SBNs, are abnormally bright (in surface brightness), significantly more so than even the brightest normal disks. Seyfert disks are also compact, but similar to those in normal early-type spirals. For a given mass, Seyferts and especially SBNs are abnormally rich in neutral hydrogen, and there is strong, albeit indirect, evidence for lower mass-to-light (M/L) ratios in Seyfert and SBN disks, but for normal M/Ls in their bulges. In Seyferts and SBNs, HI mass fractions and M/L ratios are anticorrelated, and we attribute the high gas mass fractions and low M/Ls in SBNs and several Seyferts to ongoing star formation. Such abundant gas in Seyferts would be expected to inhibit bar formation, which may explain why active galaxies are not always barred.Comment: 25 pgs (two-column, single-spaced) including 8 incorporated figures and 2 tables (aas2pp4, amssym, epsfig). Accepted for publication in Ap

The Potential-Density Phase Shift Method for Determining the Corotation Radii in Spiral and Barred Galaxies

We have developed a new method for determining the corotation radii of density waves in disk galaxies, which makes use of the radial distribution of an azimuthal phase shift between the potential and density wave patterns. The approach originated from improved theoretical understandings of the relation between the morphology and kinematics of galaxies, and on the dynamical interaction between density waves and the basic-state disk stars which results in the secular evolution of disk galaxies. In this paper, we present the rationales behind the method, and the first application of it to several representative barred and grand-design spiral galaxies, using near-infrared images to trace the mass distributions, as well as to calculate the potential distributions used in the phase shift calculations. We compare our results with those from other existing methods for locating the corotations, and show that the new method both confirms the previously-established trends of bar-length dependence on galaxy morphological types, as well as provides new insights into the possible extent of bars in disk galaxies. Application of the method to a larger sample and the preliminary analysis of which show that the phase shift method is likely to be a generally-applicable, accurate, and essentially model-independent method for determining the pattern speeds and corotation radii of single or nested density wave patterns in galaxies. Other implications of this work are: most of the nearby bright disk galaxies appear to possess quasi-stationary spiral modes; that these density wave modes and the associated basic state of the galactic disk slowly transform over time; and that self-consistent N-particle systems contain physics not revealed by the passive orbit analysis approaches.Comment: 48 pages, 16 figures. Accepted for publication in the Astronomical Journa