Application of the Bootstrap Approach to the Choice of Dimension and the α Parameter in the SIRα Method

To reduce the dimensionality of regression problems, sliced inverse regression approaches make it possible to determine linear combinations of a set of explanatory variables X related to the response variable Y in general semiparametric regression context. From a practical point of view, the determination of a suitable dimension (number of the linear combination of X) is important. In the literature, statistical tests based on the nullity of some eigenvalues have been proposed. Another approach is to consider the quality of the estimation of the effective dimension reduction (EDR) space. The square trace correlation between the true EDR space and its estimate can be used as goodness of estimation. In this article, we focus on the SIR_α method and propose a naïve bootstrap estimation of the square trace correlation criterion. Moreover, this criterion could also select the α parameter in the SIR_α method. We indicate how it can be used in practice. A simulation study is performed to illustrate the behavior of this approach.     

Asymptotic Results for Spatial ARMA Models

Causal quadrantal-type spatial ARMA(p, q) models with independent and identically distributed innovations are considered. In order to select the orders (p, q) of these models and estimate their autoregressive parameters, estimators of the autoregressive coefficients, derived from the extended Yule–Walker equations are defined. Consistency and asymptotic normality are obtained for these estimators. Then, spatial ARMA model identification is considered and simulation study is given.     

Sexual Health Services for Homeless Youth: A Qualitative Analysis of their Experiences

The sexual health problems experienced by homeless youth bring into question their use of available sexual health services. Using a qualitative typological analysis, this study aims to identify sexual health services utilization profiles for homeless youth, and to understand the role of the homeless experience on the utilization of sexual health services. Individual interviews were conducted with 33 homeless youth (17 men, 16 women) between 18 and 25?years of age. Typological analysis identified four profiles: (1) a targeted use of sexual health services to determine one’s serological status following a relational change during the homeless experience; (2) a limited use of sexual health services to manage sexual emergencies that arise during the homeless experience; (3) a regular use of sexual health services to avoid the risks associated with the homeless experience; (4) a frequent use of sexual health services to obtain support when engaging in prostitution during the homeless experience. This study shows that the precarious and unstable conditions within the homeless experience incite youth to utilize sexual health services in different ways. These findings point to the importance of rethinking sexual health services to better adapt them to the different utilization profiles of homeless youth.     

Participatory Art as a Social Practice of Commoning to Reinvent the Right to the City

The right to the city is a concept that helps rethink spatial–social dynamics, which has recently reinvigorated the field of organization studies. Following Lefebvre and considering the failure of both the market and the state, other scholars pinpoint the need to rethink social–spatial and geographical–historical relations. They do so by theorizing the city as a host for urban commons. Collective and non-commodified, these spatial–social experiences need to be constantly reproduced and preserved through commoning practices in the struggle against spatial injustice. A case study shows that a civil society organization (CSO) uses participatory art to (re)produce urban commons at the level of a local community and to redress partially spatial injustice. We theorize participatory art-making as a social practice of commoning, i.e., a process of organizing for the commons—collective art-based activities to serve a community—and of the common—to (re)produce a community while performing them. Such commoning practices are not only about sharing urban resources but also about using and experiencing differently urban spaces. By making participatory artworks in public spaces and co-designing street furniture with residents of poor areas, TDA helps to better cope with the tensions between residents and local authorities and between amateurs and professional artists. By negotiating the long-term implementation of these creative artworks in the public space with public authorities, TDA has fostered the empowerment of inhabitants as they have experienced citizens’ reappropriation of some public spaces in Marseille.     

Fisher's Information for Discretely Sampled Lévy Processes

This paper studies the asymptotic behavior of Fisher's information for a Lévy process discretely sampled at an increasing frequency. As a result, we derive the optimal rates of convergence of efficient estimators of the different parameters of the process and show that the rates are often nonstandard and differ across parameters. We also show that it is possible to distinguish the continuous part of the process from its jumps part, and even different types of jumps from one another.     

Assessment of the Effectiveness of Radon Screening Programs in Reducing Lung Cancer Mortality

The present study was aimed at assessing the health consequences of the presence of radon in Quebec homes and the possible impact of various screening programs on lung cancer mortality. Lung cancer risk due to this radioactive gas was estimated according to the cancer risk model developed by the Sixth Committee on Biological Effects of Ionizing Radiations. Objective data on residential radon exposure, population mobility, and tobacco use in the study population were integrated into a Monte‐Carlo‐type model. Participation rates to radon screening programs were estimated from published data. According to the model used, approximately 10% of deaths due to lung cancer are attributable to residential radon exposure on a yearly basis in Quebec. In the long term, the promotion of a universal screening program would prevent less than one death/year on a province‐wide scale (0.8 case; IC 99%: –3.6 to 5.2 cases/year), for an overall reduction of 0.19% in radon‐related mortality. Reductions in mortality due to radon by (1) the implementation of a targeted screening program in the region with the highest concentrations, (2) the promotion of screening on a local basis with financial support, or (3) the realization of systematic investigations in primary and secondary schools would increase to 1%, 14%, and 16.4%, respectively, in the each of the populations targeted by these scenarios. Other than the battle against tobacco use, radon screening in public buildings thus currently appears as the most promising screening policy for reducing radon‐related lung cancer.     

The ‘good mother’ struggles: Obstacles to the attainment of motherhood ideals among adult women formerly placed in residential care

We analysed narratives of motherhood produced by 13 women who were involved with the welfare system or the justice system during adolescence. The original contribution of our study was its focus on mothers who were turning age 30, so they were not in that period of generalized instability that characterizes the transition from care and into adulthood. This qualitative study was part of a larger study on French‐Canadian adolescents with a history of residential care. Semi‐directed interviews were conducted with 13 women, more than 15 years after their admission to residential care. Our data highlights that motherhood can contribute to the vulnerability of women who were involved with the welfare or the justice system as adolescents. Our results suggest that in order to shed a perceived deviant label and to compensate for the adverse events they experienced, they pursue internalized ideals of “good motherhood” that translate into restrictions and strain. Furthermore, they tend to refrain from allowing people into their lives and asking for help for fear of being judged. Yet, as their children are getting older and exhibiting problem behaviors of their own, the questioning of their parental practices and skills only becomes more intense.