Convergence properties of the expected improvement algorithm with fixed mean and covariance functions

This paper deals with the convergence of the expected improvement algorithm, a popular global optimization algorithm based on a Gaussian process model of the function to be optimized. The first result is that under some mild hypotheses on the covariance function k of the Gaussian process, the expected improvement algorithm produces a dense sequence of evaluation points in the search domain, when the function to be optimized is in the reproducing kernel Hilbert space generated by k  . The second result states that the density property also holds for P-almost$\mathsf{P}\text{-almost}$ all continuous functions, where P is the (prior) probability distribution induced by the Gaussian process.     

Inferring multiple graphical structures

Gaussian Graphical Models provide a convenient framework for representing dependencies between variables. Recently, this tool has received a high interest for the discovery of biological networks. The literature focuses on the case where a single network is inferred from a set of measurements. But, as wetlab data is typically scarce, several assays, where the experimental conditions affect interactions, are usually merged to infer a single network. In this paper, we propose two approaches for estimating multiple related graphs, by rendering the closeness assumption into an empirical prior or group penalties. We provide quantitative results demonstrating the benefits of the proposed approaches. The methods presented in this paper are embeded in the R package simone from version 1.0-0 and later.     

Sequential design of computer experiments for the estimation of a probability of failure

This paper deals with the problem of estimating the volume of the excursion set of a function f:ℝ ^d →ℝ above a given threshold, under a probability measure on ℝ ^d that is assumed to be known. In the industrial world, this corresponds to the problem of estimating a probability of failure of a system. When only an expensive-to-simulate model of the system is available, the budget for simulations is usually severely limited and therefore classical Monte Carlo methods ought to be avoided. One of the main contributions of this article is to derive SUR (stepwise uncertainty reduction) strategies from a Bayesian formulation of the problem of estimating a probability of failure. These sequential strategies use a Gaussian process model of f and aim at performing evaluations of f as efficiently as possible to infer the value of the probability of failure. We compare these strategies to other strategies also based on a Gaussian process model for estimating a probability of failure.     

Piecewise deterministic Markov processes applied to fatigue crack growth modelling

In this paper, we use a particular piecewise deterministic Markov process (PDMP) to model the evolution of a degradation mechanism that may arise in various structural components, namely, the fatigue crack growth. We first derive some probability results on the stochastic dynamics with the help of Markov renewal theory: a closed-form solution for the transition function of the PDMP is given. Then, we investigate some methods to estimate the parameters of the dynamical system, involving Bogolyubov's averaging principle and maximum likelihood estimation for the infinitesimal generator of the underlying jump Markov process. Numerical applications on a real crack data set are given.     

The relation between children’s task‐specific competence and mothers’ controlling practices

In the guided learning domain of socialization, studies examining the antecedents of controlling parenting suggest that children’s lack of competence in a task could trigger controlling practices in that task. However, a stringent test of this relation remains to be conducted. This study examined this relation using a sample of 101 children (M_age = 10.21 years) and their mothers, a standardized measure of children’s competence in a task that was unfamiliar to the participants, and multi‐informant observational measures of maternal controlling practices during a mother–child interaction involving that task (rated by an independent coder and the children). Path analyses showed that children’s initial lack of competence in a task was related to higher levels of coded maternal controlling practices during a subsequent mother–child interaction involving that task, which in turn were positively linked to children’s perceptions of their mothers’ practices as controlling. A bootstrap analysis also confirmed that the indirect link from children’s competence to perceived maternal controlling practices through coded maternal controlling practices was significant. These effects were observed while controlling for mothers’ self‐reported controlling parenting style and perceptions of their children’s academic skills. Implications of these findings for the promotion of optimal parenting and future research directions are discussed.     

Frantz Fanon,poet: pleasure of the text,power of the text

ABSTRACT

Frantz Fanon’s writing represents a productive embrace of the political and the poetic. His ideas have had such a long afterlife, they live on in us, I submit, precisely because the language of their articulation, image-filled and rhythmic, is compelling. This article examines three elements of Fanonian poetics in Black Skin, White Masks: the use of metaphor and, in “By Way of Conclusion,” an ambiguous/multiple “I” as persona, and, finally, what Brent Edwards has called “anaphoric poetics,” the repetition of the same word or words at the beginning of successive phrases.     

An ecological systems approach to understanding social support in foster family resilience

Families who care for children in the foster care system often experience challenges related to the system, accessing services and supports, and managing relationships. Despite these challenges, many families thrive because of unique attributes and strengths that contribute to experiences of resilience. Using an ecological framework, this study examined social support among resilient foster families to better understand how foster caregivers experienced positive reciprocal transactions across systems. As part of a larger study, in‐depth narrative interviews were conducted to examine the process of resilience for families who foster. Findings revealed that families accessed and benefited from social support on micro‐level, meso‐level and macro‐level. Understanding how families cultivated social support across multiple levels offers implications for practice and policy when considering how best to retain and support families who care for vulnerable children.     

Can urban consolidation limit local biodiversity erosion? Responses from carabid beetle and spider assemblages in Western France

During the last decades, urban consolidation has been developed to minimize spatial expansion of cities, yet very few studies investigated whether it would actually reduce some negative effects of urbanization on biodiversity. In this study, we compared the invertebrate assemblages associated with two distinct urban forms (compact vs. conventional), focusing on two arthropod taxa often used as bioindicators, and dominant in urban habitats: spiders and carabid beetles. The following parameters were estimated: assemblage composition, species richness, activity-density total, per species (excluding seldom-recorded species) and per size class. The field collection was performed in 2009 using pitfall traps randomly set in hedgerows within 6 sites (representing 251 traps). A total of 4,413 spiders belonging to 117 species and 2,077 adult carabid beetles belonging to 39 species were collected. We found few significant differences in carabid beetle and spider assemblages between the two urban forms. The species richness of both groups was independent from the neighborhood design. Only four species of carabid beetles and ten of spiders significantly reacted to the neighborhood design, and no difference was found among the two designs for all other species. Large carabid beetles were more abundant and small spiders less abundant in the new neighborhood design compared to the conventional one. For both carabid beetles and spiders, no difference in assemblage composition was found between neighborhood designs. We therefore conclude that urban consolidation, by permitting a higher human density with similar arthropod assemblages, could contribute to reduce biodiversity loss in cities.     

Entre « passion » et incertitude : la socialisation au métier de footballeur professionnel

On the basis of a socioethnographic survey conducted in a professional soccer training center in France, the means of occupational socialization are analyzed in this demanding, captivating institution. Light is shed on how trainees appropriate this professional world and its requirements. As they enter this social universe, they encounter a key tension. On the one hand, training calls for a heavy investment that trainers and trainees experience as a “passion” and understand as being separate from the world of “ordinary” work. On the other hand, it is also a major source of uncertainty as to trainees’ prospects, given its intense selectivity and the few outlets in the labor market. It requires of trainees a strong commitment in time, body and spirit with prospects so uncertain that the course of training is seldom free from periods of soul-searching.     

Black Interactionist Thought and the Lived-Experience Approach to Symbolic Interactionism

Du Bois is often regarded as an important scholar for his contributions to the development of sociology. However, less is known about his work in developing interactionist thought. This essay is an introduction to this special issue, and a small attempt to acknowledge the work of scholars of color within the interactionist tradition. The Du Bosian approach to sociology has for too long been dismissed out of hand. Scholars pursuing new areas of inquiry, topics outside the bounds of “mainstream sociology,” are often met with fierce resistance—even today. Instead of building these scholars up, through mentorship and aid, so-called “accomplished” scholars see fit to tear down the work of those not like them. The Du Bosian perspective celebrates the plurality of voices, advocates for mentorship, and sees sociological inquiry as rooted in the real needs and concerns of those so marginalized. As this collection of articles illustrates, even when conforming to scientific standards work in this tradition has a political dimension as it lays bare the inequities in society—even, at times, drawing government interference with their work. This issue also calls upon professional sociologists to reflect on the ways they reproduce these patterns within the discipline and higher education.