Computing A-optimal and E-optimal designs for regression models via semidefinite programming

In semidefinite programming (SDP), we minimize a linear objective function subject to a linear matrix being positive semidefinite. A powerful program, SeDuMi, has been developed in MATLAB to solve SDP problems. In this article, we show in detail how to formulate A-optimal and E-optimal design problems as SDP problems and solve them by SeDuMi. This technique can be used to construct approximate A-optimal and E-optimal designs for all linear and nonlinear regression models with discrete design spaces. In addition, the results on discrete design spaces provide useful guidance for finding optimal designs on any continuous design space, and a convergence result is derived. Moreover, restrictions in the designs can be easily incorporated in the SDP problems and solved by SeDuMi. Several representative examples and one MATLAB program are given.     

Public Sociology on Twitter: a Space for Public Pedagogy?

Research has examined various elements of Twitter; however, no scholarship has explored how sociologists currently use the platform. This empirically driven paper explores how individuals that self-identify as sociologists on Twitter use the popular micro-blogging social media site. A total of 152,977 tweets from Twitter profiles of 130 sociologists were collected and examined using qualitative media analysis. The potential use of Twitter allows the sociologist to become both the generator and interlocutor of dialogue with publics. We frame our data analysis and discussion around the core theme of expertise - namely, the role that expertise plays in the use of Twitter by sociologists. Our findings indicate that when sociologists used Twitter as sociologists (i.e., drawing upon their stated research expertise) little direct engagement with publics occurred. Thus, while sociologists appear to be using Twitter as a space for public sociology, the use of this interactive platform is mostly limited to the generation of content, a finding consistent with Burawoy’s traditional form of public sociology. Suggestions for future research are noted.     

Fathers' Investments of Money and Time Across Residential Contexts

Fathers' roles in family life have changed dramatically over the past 50 years. In addition to ongoing breadwinning responsibilities, many fathers are now involved in direct caregiving and engagement with children. Yet there is considerable variation in what fathers do, especially depending on whether they live with or away from their child. In this article, the authors use data from the Fragile Families and Child Wellbeing Study (N = 3,869) to describe how fathers' economic capacities (money) and direct involvement with children (time) are associated over child ages 1 to 9 for resident versus nonresident fathers, net of confounding factors. They found suggestive evidence that money and time investments operate differently across residential contexts: Resident fathers experience a trade‐off between market work and time involved with children. In contrast, nonresident fathers' higher economic capacities are associated with more time involvement, underscoring the greater challenge for such fathers to remain actively involved.     

Grandparents' Education and Infant Health: Pathways Across Generations

Using data from the Fragile Families and Child Wellbeing survey linked to respondents' medical records (N = 2,870), this study examines the association between grandparents' education and birth outcomes and explores potential pathways underlying this relationship. Results show that having a grandfather with less than a high school education was associated with a 93 gram reduction in birth weight, a 59% increase in the odds of low birth weight, and a 136% increase in the odds of a neonatal health condition when compared with having a grandfather with a high school education or more. These associations were partially accounted for by mother's educational attainment and marital status as well as by prenatal history of depression, hypertension, and prenatal health behaviors, depending on the specific outcome. The findings from this study call for heightened attention to the multigenerational influences of educational attainment for infant health.     

“I Feel Like More of a Man”: A Mixed Methods Study of Masculinity,Sexual Performance,and Circumcision for HIV Prevention

Ethnographic studies from numerous societies have documented the central role of male circumcision in conferring masculinity and preparing boys for adult male sexuality. Despite this link between masculinity, sexuality, and circumcision, there has been little research on these dynamics among men who have been circumcised for HIV prevention. We employed a mixed methods approach with data collected from recently circumcised men in the Dominican Republic (DR) to explore this link. We analyzed survey data collected six to 12 months post-circumcision (N = 293) as well as in-depth interviews conducted with a subsample of those men (n = 30). We found that 42% of men felt more masculine post-circumcision. In multivariate analysis, feeling more masculine was associated with greater concern about being perceived as masculine (OR = 1.70, 95% CI: 1.25–2.32), feeling more potent erections post-circumcision (OR = 2.25, 95% CI: 1.26–4.03), and reporting increased ability to satisfy their partners post-circumcision (OR = 2.30, 95% CI: 1.11–4.77). In qualitative interviews, these factors were all related to masculine norms of sexually satisfying one’s partner, and men’s experiences of circumcision were shaped by social norms of masculinity. This study highlights that circumcision is not simply a biomedical intervention and that circumcision programs need to incorporate considerations of masculine norms and male sexuality into their programming.     

Sexually Experienced Adolescents’ Thoughts About Sexual Pleasure

Little research on adolescents has examined developmentally normative facets of sexuality that are not obviously linked to physical health. The purpose of this secondary data analysis was to qualitatively analyze adolescents’ thoughts about and experiences with sexual pleasure. The study sample consisted of 56 sexually experienced, ethnically diverse, predominantly female adolescents who were participating in a Web-based intervention to promote healthy sexual decision making. Comments on one message board, “Sexual Pleasure: Does It Matter to You?,” provided an opportunity to examine adolescents’ thoughts about and experiences with sexual pleasure, as well as their communication with partners about that topic. Adolescents’ comments demonstrated that they experience difficulties with pleasure in their sexual relationships. Adolescents generally believed that men are more likely than women to feel pleasure due to differences that include biology, understanding of one’s body, and control over partnered sexual behavior. Adolescents defined inequality of received pleasure differently and discussed contexts in which inequality may be acceptable. Adolescents expressed motivation to communicate with partners about sexual pleasure. However, their statements suggested they often lack the skills to do so. Future prevention and intervention programs should equip adolescents with skills to communicate with partners about sexual pleasure.     

“Men never cry”: Teaching Mormon Manhood in the Church of Jesus Christ of Latter-day Saints

We examine the ways Mormon leaders establish “what it means to be a man” for their followers. Based on content analysis of over 40 years of archival material, we analyze how Mormon leaders represent manhood as the ability to signify control over self and others as well as an inability to be controlled. Specifically, we demonstrate how these representations stress controlling the self, emotional and sexual expression, and others while emphasizing the development of self-reliance and independence from others’ control. We draw out implications for understanding (1) how religious leaders create ideal notions of manhood, (2) what the religious interpretations of secular constructions of manhood are, and (3) how these relate to the reproduction of gender inequalities.     

Family Economy,Rural School Choice,and Flexischooling Children with Disabilities

Most homeschooled students would be more accurately described as “flexischooled,” partly homeschooled and partly enrolled in school. The popularity of these two alternatives to public or private school enrollment has increased over the past several decades to the extent that, by 2012 over 2 million students, 4 percent of the population, were either flexischooled or homeschooled in the United States. To understand why parents have pursued these options over enrollment, we employed a family economy perspective, arguing that family, child, and locational considerations shaped parents' motivations for homeschooling or flexischooling over enrollment. For example, parents' decisions were partially shaped by the interaction between children's disability status and rural location. Using data from the National Household Education Survey 2012, this article first describes the prevalence of flexischooling and full‐time homeschooling. Then, it demonstrates how various family, child, and locational factors shape the odds of flexischooling and homeschooling, and then examines the interaction between location and children's disability status in detail. We discuss the implications of our findings for family economy theoretical perspectives, flexischooling, and rural education research.     

Familial Patterning and Prevalence of Male Androphilia in Samoa

Previous research established that male androphilia (i.e., sexual arousal and attraction to adult males) clusters in families. Some studies find that male androphilia clusters in both the paternal and maternal lines, while others find that it clusters only in the latter. Most of the research investigating the familial nature of male androphilia has taken place in Western cultural contexts that are problematic for such research because they are characterized by low fertility. To address this, our previous work has examined familial patterning of male androphilia in Samoa, a high-fertility population in which androphilic males are readily identified due to their public status as fa’afafine (a third gender category). Building on this work, the present study replicated the familial nature of male androphilia in Samoa using a sample size that was ~122% larger than the one we previously employed (N = 382, M ±SD age: 29.72 years ±10.16). Samoan fa’afafine had significantly more fa’afafine relatives in their maternal and paternal lines compared to Samoan gynephilic males (p < .001). The prevalence of male androphilia was equivalent across both the paternal and maternal lines (all p > .15). The revised prevalence estimate of male androphilia in Samoa falls between 0.61% and 3.51%.     

Marriage Delay,Time to Play? Marital Horizons and Hooking Up in College

Previous research suggests that an increasing age at first marriage has contributed to the prevalence of sexual hookups on U.S. college campuses. In this article, we use life course and marital horizons theories to analyze the influence of ideal age at first marriage on hooking up among unmarried heterosexual college students. Analyses of the Online College Social Life Survey (N = 17,981) show a positive association between ideal age at first marriage and hookups for most students, but not for students whose mothers have no post‐secondary education, Asian men, Asian women, and Latina women. Variation in ideal marriage timing does not account for gender, racial/ethnic, and class gaps in hookup participation. Results are discussed with reference to the role of sexuality in processes of stratification throughout young adulthood.