Parameter estimation in high dimensional Gaussian distributions

In order to compute the log-likelihood for high dimensional Gaussian models, it is necessary to compute the determinant of the large, sparse, symmetric positive definite precision matrix. Traditional methods for evaluating the log-likelihood, which are typically based on Cholesky factorisations, are not feasible for very large models due to the massive memory requirements. We present a novel approach for evaluating such likelihoods that only requires the computation of matrix-vector products. In this approach we utilise matrix functions, Krylov subspaces, and probing vectors to construct an iterative numerical method for computing the log-likelihood.     

Best Nonparametric Bounds on Demand Responses

This paper uses revealed preference inequalities to provide the tightest possible (best) nonparametric bounds on predicted consumer responses to price changes using consumer‐level data over a finite set of relative price changes. These responses are allowed to vary nonparametrically across the income distribution. This is achieved by combining the theory of revealed preference with the semiparametric estimation of consumer expansion paths (Engel curves). We label these expansion path based bounds on demand responses as E‐bounds. Deviations from revealed preference restrictions are measured by preference perturbations which are shown to usefully characterize taste change and to provide a stochastic environment within which violations of revealed preference inequalities can be assessed.     

Assessing Overweight,Obesity, Diet,and Physical Activity in College Students

Abstract

The authors surveyed 738 college students aged 18 to 27 years to assess overweight, obesity, dietary habits, and physical activity. They used BMI (body mass index) > 25 kg/m² or BMI > 85th percentile and BMI > 30 kg/m¹ or BMI > 95th percentile to estimate overweight and obesity in those aged < 19 years. To define overweight and obesity in those > 20 years, they used BMI > 25 kg/m² and > 30 kg/m². They found overweight rates of 21.6% using BMI directly and 16.2% using BMI percentile and obesity rates of 4.9% using BMI directly and 4.2% using BMI percentile. More than 69% of the participants reported < 5 servings of fruits and vegetables per day and more than 67% reported < 20 g of fiber per day; participants reported physical activity on fewer than 3 d/wk. Most college students are not meeting dietary and physical activity guidelines, suggesting the need for prevention interventions and increased understanding of overweight in college students.     

Postdivorce Relationships in Families and Children's Psychosocial Adjustment

Divorced mothers and their school-aged children in 50 single-mother families and 37 stepfather families reported on mothers' ex-partner relationships, children's relationships with both parents, and children's well-being. A 2 (family structure) × 2 (gender) multivariate analysis of variance revealed a main effect of gender: Mothers with sons report higher levels of ex-partner relationship satisfaction. An interaction effect was also found: Boys in single-mother families report more acceptance and fewer conflicts than boys in stepfather families. Multiple regression analysis revealed that mother–ex-partner relationships are associated with children's problem behavior, whereas child–nonresidential father relationships are associated with positive aspects of children's well-being. The results indicate that family structure itself is not associated with child adjustment. What matters most is the quality of family relationships.     

Exploring the Role of Being Out on a Queer Person's Self-Compassion

Recent changes in societal attitudes toward lesbian, gay, and bisexual identities have resulted in more people openly identifying with sexual minority status. Due to research on the effects of denying one's sexual orientation and the negative effects of this, many have advocated for more openness in queer sexual orientation. Compassion means connecting to the suffering of others not by avoiding their pain but instead by identifying it so that the feeling of kindness may emerge. Self-compassion, therefore, involves being touched by and open to one's own suffering, not avoiding or disconnecting from it, generating the desire to alleviate one's suffering and to heal oneself with kindness. The purpose of the research is to understand the impact that being out has on a queer person's self-compassion. The Self-Compassion Scale (SCS) is a 26-item, 5-point Likert measure, where a higher score equated to higher self-compassion and looked at how a person showed loving kindness to one's self through the six dimensions of self-compassion. The six dimensions of self-compassion are mindfulness, over-identification, self-kindness, self-judgment, common humanity, and isolation. Results showed that those who are totally out have a higher sense of self-compassion. Implications for practitioners working with the queer population are also discussed.     

Negotiating Ethnic Identity in the College Korean Language Classes

This article examines the ways in which second-generation Korean-American students form and transform their senses of ethnicity through their participation in Korean language classes at the University of Illinois, Urbana-Champaign. These classes were largely populated by second-generation Korean-Americans. Called the "New Second Generation," these Korean-American students, who have "successfully" proceeded through the American educational system, show that adaptation to the host society does not necessarily lead to assimilated American identity, and that learning Korean (a "heritage" language) does not necessarily lead to homogeneous ethnic identity formation. Although "heritage" (or "ethnic") language has often been taken up as a symbol for group maintenance, my study shows that actual interaction with the language is complexly and heterogeneously experienced among the group members, especially in relation to the ethnic identity formation process. Korean classes (as a transnational social field) contain complicated and contradictory characteristics, resulting from their complex mixture of class participants, their institutional location, and their national and transnational situation. Korean-American language learners negotiate their sense of ethnic identity by interacting with social meanings initiated from words, passages, illustrations, and texts. Furthermore, Korean-American student's language performance and cultural tastes, which are perceived and evaluated by themselves and others, differently locate these students on a continuum of "Koreanness" and "Americanness," reflecting different relationships to Korea and different senses of being Korean.     

Galvão among the cannibals: The emotional constitution of colonial power

Colonial domination was not a simple act of violence. Rather, it was written into the bodies and the hearts of the people—"white,” “black,” or whatever other combination might be held to exist. Using the example of the Portuguese African colonies in mid‐twentieth century, this paper aims at illuminating the emotional constitution of colonial power by exploring the uses of the trope cannibalism. In order to do that, recourse is taken to a reading of the non‐fictional writings of Henrique Galvão—one of the most active Portuguese intellectuals and Africanist politicians of the period. Subaltern persons were attributed terrible and mysterious tendencies that escaped simple rationality (they were zombified). In this way, a phantasmagoria of subalternity was constituted that, through fear, transformed domination into a structure of emotions. Thus, the repressive attitudes of colonial power were made to appear natural and unavoidable.     

The influence of dual‐identity development on the psychosocial functioning of African‐American gay and bisexual men

To examine the influence of racial‐ethnic and sexual identity development on the psychosocial functioning of African‐American gay and bisexual men (AAGBM), 174 AAGBM completed questionnaire packets designed to assess their levels of racial‐ethnic and sexual identity development, self‐esteem, social support, male gender role stress, HIV prevention self‐efficacy, psychological distress, and life satisfaction. The results indicate that AAGBM who possess more positive (i.e., integrated) seif‐identification as being African American and gay reported higher levels of self‐esteem, HIV prevention self‐efficacy, stronger social support networks, greater levels of life satisfaction, and lower levels of male gender role and psychological distress than their counterparts who reported less positive (i.e., less well integrated) African‐American and gay identity development. Although higher levels of racial‐ethnic identity development were associated with greater levels of life satisfaction, sexual identity development was not.     

Comparing Ourselves to Others: International Knowledge and Attitudes

The authors focus on the collaboration between a university methods professor and two classroom teachers in teaching social studies methods as a way of bridging the gap between university preparation for teaching social studies and putting that preparation into practice in elementary classrooms. The teachers offer recommendations from their own teaching experiences for how preservice teachers can find time for powerful social studies teaching despite pressures to meet the requirements of No Child Left Behind in literacy and mathematics. They integrate social studies with literacy and math, use "teachable moments" and transitions between subjects, and incorporate social studies research with computer and media skills. In addition, they employ class meetings to practice the democratic processes of collectively setting and revising class rules, accepting responsibility for those rules, and working together to solve classroom problems. Informal feedback from the preservice teachers reflects their appreciation of advice from classroom teachers with current experience in addressing the challenge of making time for powerful social studies teaching.     

Becoming a Social Worker: Chris' Account

Chris Murray, a young African-American male, admitted on a scholarship to a social work masters program, reflexively explores his negotiation of difference in dialogue with an Australian female social work educator twice his age. Standpoint theory and the concept of intersectionality are used to frame Chris' experiences at a private northeast US university after achieving an undergraduate degree in his southern home state. His initial access to university came through military service. Chris was interviewed by the author as part of her international study project examining social work students' experience of diversity in the classroom. The open-ended interview was designed to allow self-identity of difference. Chris ethnographically recounts to a stranger a subjectivity statement of who he is in relation to studying social work. Chris' story works the hyphen between the binary of subjectivity and objectivity through the particulars of his personal history and world-view and his expectation that I as a social work educator share his seeking of social justice. His detailing of what moved him to become a social worker and contextual complexities negotiated along the way connect to wider discourses on how agency and structure play out in lived experience in seeking social justice.