1,317 research outputs found
Polarization Light Curve Modeling of Corotating Interaction Regions in the Wind of the Wolf-Rayet Star WR 6
The intriguing WN4b star WR6 has been known to display epoch-dependent
spectroscopic, photometric and polarimetric variability for several decades. In
this paper, we set out to verify if a simplified analytical model in which
Corotating Interaction Regions (CIRs) threading an otherwise spherical wind is
able to reproduce the many broadband continuum light curves from the literature
with a reasonable set of parameters.
We modified the optically thin model we developed in Ignace, St-Louis &
Proulx-Giraldeau (2015) to approximately account for multiple scattering and
used it to fit 13 separate datasets of this star. By including two CIRs in the
wind, we obtained reasonable fits for all datasets with coherent values for the
inclination of the rotation axis () and for its orientation in
the plane of the sky, although in the latter case we obtained two equally
acceptable values ( and ) from the
polarimetry.
Additional line profile variation simulations using the Sobolev approximation
for the line transfer allowed us to eliminate the solution.
With the adopted configuration ( and ), we
were able to reproduce all datasets relatively well with two CIRs located near
the stellar equator and always separated by in longitude. The
epoch-dependency comes from the fact that these CIRs migrate along the surface
of the star. Density contrasts smaller than a factor of two and large opening
angles for the CIR () were found to best reproduce the
type of spectroscopic variability reported in the literature.Comment: 15 pages, 5 figures,5 table
On (Un)Truths of Photography : A Discussion with Photographer and Visual Artist Richard-Max Tremblay
"This contribution is an interview with Canadian award-winning photographer and painter, Richard-Max Tremblay. Through a series of questions and answers that draw from both Tremblay's personal philosophy and visual art practices, it approaches photographic untruth through the hands-on experience of a visual artist who has devoted a great part of his career to exploring the relationship between truth / untruth, seen / unseen, espression / suggestion." -- page 63
Developmental origins of chronic physical aggression: an international perspective on using singletons, twins and epigenetics
This chapter takes an international and historical perspective to discuss the present state of knowledge on the developmental origins of physical aggression and its implications for the prevention of chronic physical aggression. An increasing number of longitudinal studies of singleton and twins initiated at birth or during the first few years of life are showing that physical aggressions are more frequent in early childhood than at any other time during the life-span. Because chronic physical aggression generally starts in early childhood, preventive interventions during this period are much more likely to be effective and substantially decrease the costs of criminal behavior during adolescence and early adulthood. Unfortunately, most criminological studies on physical aggression development and prevention target the adolescent and adulthood periods and do not take into account gene-environment contributions. Early childhood studies are needed to identify early bio-psycho-social mechanisms that put individuals on a chronic trajectory of physical aggression from early childhood to adulthood. These studies can also help identify the preventive interventions that are most effective in preventing a life-course of crime and misery. Developmental criminology needs to take a bio-psycho-social intergenerational and life-span perspective as well as focus more systematically on females as the key target for intergenerational prevention of chronic physical aggression
Early Childhood Intervention. Rationale, Timing and Efficacy
This paper provides a brief review of the economic rationale for investing in early childhood. It discusses the optimal timing of intervention, with reference to recent work in developmental neuroscience, and asks how early is early? It motivates the need for early intervention by providing an overview of the impact of adverse factors during the antenatal and early childhood period on outcomes later in life. Early childhood interventions, even poorly designed ones, are costly to implement, therefore it is vital that interventions are well-designed if they are to yield high economic and social returns. The paper therefore presents a set of guiding principles for the effectiveness of early intervention. It concludes by presenting a case for a new study of the optimal timing of interventions.Early childhood intervention, brain development, optimal timing
Prévention de la délinquance : le rôle médiateur des pairs
The objective of this study was to test whether friends' characteristics mediated the link between early reduction of disruptive behavior and later reduction of delinquency (through a prevention program). The prevention program includes two components : social-cognitive-skills training for boys and parent-skills training at home. It was applied over a two-year period when the subjects were 8- and 9-year-old. Subjects were low SES boys rated as disruptive by their kindergarten teachers. They were randomly assigned to a prevention or a control condition. Their friends ' aggressiveness was rated by classmates over a three-year period following the end of the prevention program. Subjects reported on their delinquent behaviors when they were 13- and 14-year-old. Results indicate that friends' aggressiveness partially mediated the impact of the program on preventing delinquency. However, compared to the control boys, other mediating variables might also have played a role
Complexity : a potential paradigm for a health promotion discipline
Health promotion underpins a distancing from narrow, simplifying health approaches associated with the biomedical model. However, it has not yet succeeded in formally establishing its theoretical, epistemological and methodological foundations on a single paradigm. The complexity paradigm, which it has yet to broach head-on, might provide it with a disciplinary matrix in line with its implicit stances and basic values. This article seeks to establish complexity's relevance as a paradigm that can contribute to the development of a health promotion discipline. The relevance of complexity is justified primarily by its matching with several implicit epistemological and methodological/theoretical stances found in the cardinal concepts and principles of health promotion. The transcendence of ontological realism and determinism as well as receptiveness in respect of the reflexivity that complexity encompasses are congruent with the values of social justice, participation, empowerment and the concept of positive health that the field promotes. Moreover, from a methodological and theoretical standpoint, complexity assumes a holistic, contextual and transdisciplinary approach, toward which health promotion is tending through its emphasis on ecology and interdisciplinary action. In a quest to illustrate our position, developmental evaluation is presented as an example of practice stemming from a complexity paradigm that can be useful in the evaluation of health promotion initiatives. In short, we argue that it would be advantageous for health promotion to integrate this paradigm, which would provide it with a formal framework appropriate to its purposes and concerns
Fano Resonances in Mid-Infrared Spectra of Single-Walled Carbon Nanotubes
This work revisits the physics giving rise to the carbon nanotubes phonon
bands in the mid- infrared. Our measurements of doped and undoped samples of
single-walled carbon nanotubes in Fourier transform infrared spectroscopy show
that the phonon bands exhibit an asymmetric lineshape and that their effective
cross-section is enhanced upon doping. We relate these observations to
electron-phonon coupling or, more specifically, to a Fano resonance phenomenon.
We note that only the dopant-induced intraband continuum couples to the phonon
modes and that defects induced in the sidewall increase the resonance
probabilities.Comment: 5 pages, 4 figures and 1 Supplementary Information File (in pdf
- …