Confidence intervals for finite difference solutions

Although applications of Bayesian analysis for numerical quadrature problems have been considered before, it is only very recently that statisticians have focused on the connections between statistics and numerical analysis of differential equations. In line with this very recent trend, we show how certain commonly used finite difference schemes for numerical solutions of ordinary and partial differential equations can be considered in a regression setting. Focusing on this regression framework, we apply a simple Bayesian strategy to obtain confidence intervals for the finite difference solutions. We apply this framework on several examples to show how the confidence intervals are related to truncation error and illustrate the utility of the confidence intervals for the examples considered.     

冒险成就的电信巨头

从任何一个角度看,全球无线手机通讯行业都在快速逼近危机的边缘。全世界已经有50多个国家的手机用户数量超过其实际人口数量。即使是在工业化国家中手机人均拥有率较低的美国,在用的手机数量也超过了2.7亿部（市场渗透率接近于90％）。今天,随着无线通讯市场的日益萎缩,     

Towards an integrated model of leadership and self regulation

Most organizations strive to recruit employees who can accommodate unpredictable changes, demonstrate adaptability, and interact effectively with a diversity of individuals. Nevertheless, recent advances in self regulation imply that leaders can instead cultivate such qualities in employees rather than merely attract individuals with these capacities. This paper delineates some of the leadership characteristics and behaviors that could diminish the fragility of employees to foster these qualities. First, a framework is developed that integrates four theories of self regulation—self discrepancy theory, personality systems interaction theory, optimal self esteem, and self salience. Second, this framework is applied to demonstrate how fragility undermines adaptive performance. Finally, this framework is used to show how many leadership constructs, such as self sacrificing, moral management, and transformational behavior, can curb this fragility and thus improve adaptive performance.     

Time as a limited resource: Communication strategy in mobile phone networks

We used a large database of 9 billion calls from 20 million mobile users to examine the relationships between aggregated time spent on the phone, personal network size, tie strength and the way in which users distributed their limited time across their network (disparity). Compared to those with smaller networks, those with large networks did not devote proportionally more time to communication and had on average weaker ties (as measured by time spent communicating). Further, there were not substantially different levels of disparity between individuals, in that mobile users tend to distribute their time very unevenly across their network, with a large proportion of calls going to a small number of individuals. Together, these results suggest that there are time constraints which limit tie strength in large personal networks, and that even high levels of mobile communication do not fundamentally alter the disparity of time allocation across networks.     

Extrapolative simulation of neighborhood networks based on population spatial distribution: Do they predict crime?

Objectives

Previous criminological scholarship has posited that network ties among neighborhood residents may impact crime rates, but has done little to consider the specific ways in which network structure may enhance or inhibit criminal activity. A lack of data on social ties has arguably led to this state of affairs. We propose to avoid this limitation by demonstrating a novel approach of extrapolatively simulating network ties and constructing structural network measures to assess their effect on neighborhood crime rates.

Methods

We first spatially locate the households of a city into their constituent blocks. Then, we employ spatial interaction functions based on prior empirical work and simulate a network of social ties among these residents. From this simulated network, we compute network statistics that more appropriately capture the notions of cohesion and information diffusion that underlie theories of networks and crime.

Results

We show that these network statistics are robust predictors of the levels of crime in five separate cities (above standard controls) at the very micro geographic level of blocks and block groups.

Conclusions

We conclude by considering extensions of the approach that account for homophily in the formation of network ties.     

Comparisons of Gambling and Alcohol Use Among College Students and Noncollege Young People in the United States

Abstract

Objective: Gambling and alcohol use were compared for college and noncollege young adults in the US population. Participants: Participants were 1,000 respondents aged 18 to 21. Methods: Data were analyzed from a representative household sample of US young people aged 14 to 21 years old. Telephone interviews were conducted between August 2005 and January 2007. Results: After taking into account gender, age, race/ethnicity, and socioeconomic status, college student status did not predict gambling, frequent gambling, or problem gambling. In contrast, being a college student was associated with higher levels of alcohol use and problem drinking. Being male was the strongest predictor of both problem gambling and problem drinking. Blacks were less likely than whites to drink heavily; yet they were more likely than whites to gamble heavily. Conclusion: Young males should be targeted for prevention and intervention efforts for both problem gambling and problem drinking regardless of college student status.     

Flourishing: Exploring Predictors of Mental Health Within the College Environment

Abstract

Objective: To explore the predictive factors of student mental health within the college environment. Participants: Students enrolled at 7 unique universities during years 2008 (n = 1,161) and 2009 (n = 1,459). Methods: Participants completed survey measures of mental health, consequences of alcohol use, and engagement in the college environment. Results: In addition to replicating previous findings related to Keyes’ Mental Health Continuum, multiple regression analysis revealed several predictors of college student mental health, including supportive college environments, students’ sense of belonging, professional confidence, and civic engagement. However, multiple measures of engaged learning were not found to predict mental health. Conclusions: Results suggest that supportive college environments foster student flourishing. Implications for promoting mental health across campus are discussed. Future research should build on exploratory findings and test confirmatory models to better understand relationships between the college environment and student flourishing.     

Environmental Health and Safety Philosophy

Abstract

Objective: This study examines ethnic identity and body image in black and white college females. Participants: Researchers surveyed 118 students at 2 universities, 1 traditionally white and 1 historically black. Methods: Correlations and multivariate analysis of variance (MANOVA) were used to investigate the relationship between race, ethnic identity, and body dissatisfaction. Results: There was no relationship between a woman's ethnic identity and her body dissatisfaction. Although white women scored higher on body dissatisfaction measures, women in both groups who had higher body dissatisfaction scores also choose smaller ideal body types. Results suggest that identification with an ethnic group may not shield women from being dissatisfied with their bodies. Conclusion: Colleges and universities should be aware that many women could experience body dissatisfaction and develop diverse programs that target women from different ethnic groups.     

Echoic and Self-Echoic Responses in Children

Eleven typically developing children were assessed on the accuracy of prompted self-echoic responses following a 5-s delay from their initial echoic response, replicating procedures in Esch, Esch, McCart, and Petursdottir (2010) that compared discrepancies between echoic and self-echoic scores of autistic and typically developing children following a 2-s delay. We compared the two studies in terms of age, level tested, and echoic/self-echoic discrepancy scores. Age and test level differences were found to be statistically significant. Results are discussed in terms of discrepant self-echoic performance and self-echoic rehearsal as it relates to participant age, test level, motivating variables, and the development of complex behavior.