Topological methods in social choice: an overview

 This paper gives an exposition of the topological framework for social choice theory developed by Chichilnisky, and reviews the mathematical concepts needed for understanding this framework. Within that context, this paper also discusses some classic results of Chichilnisky. Received: 30 December 1994/Accepted: 22 April 1996     

Further Results on Zellner's Minimum Expected Loss and Full Information Maximum Likelihood Estimators for Undersized Samples

The article presents a consistent set of conditions that a prior pdf for the reduced-form parameters must satisfy if Zellner's MELO estimators for the structural coefficients of a linear structural econometric model are to exist in all normal cases where the available sample is undersized. Also, the conditions under which the full information maximum likelihood estimators of structural coefficients exist are given. Finally, the article reports application of MELO estimation to Klein's Model I.     

A study of some ridge-type shrinkage estimators

In this paper,several ridge-type shrinkage estimators are studied with respect to their relative efficiency. Some interrelationships which exist among these estimators are pointed out. One of these estimators, T∞ based on the work of Mehta and Srinivasan (1971), is shown to be a flexible estimator, which has clear advantages over its competitors. A useful approximation for calculation of the relative efficiency of T∞ is also presented.     

Disability Among Native-born and Foreign-born Blacks in the United States

Using the 5% Public Use Micro Data Sample (PUMS) from the 2000 U.S. census, we examine differences in disability among eight black subgroups distinguished by place of birth and Hispanic ethnicity. We found that all foreign-born subgroups reported lower levels of physical activity limitations and personal care limitations than native-born blacks. Immigrants from Africa reported lowest levels of disability, followed by non-Hispanic immigrants from the Caribbean. Sociodemographic characteristics and timing of immigration explained the differences between these two groups. The foreign-born health advantage was most evident among the least-educated except among immigrants from Europe/Canada, who also reported the highest levels of disability among the foreign-born. Hispanic identification was associated with poorer health among both native-born and foreign-born blacks.     

An Eight-Step Guide to Creating and Sustaining a Mentoring Program

Mentoring is an extremely valuable activity for both individuals and organizations. Mentoring within organizations can develop and integrate employees into their corporate culture. Mentoring outside the mentees’ work groups or through professional development organizations can give broader perspective and support, especially in times of transition. But mentoring programs require tremendous effort to start, organize, and maintain. Few last more than two years. This article provides a structured approach to starting and sustaining a successful program. The steps include understanding an organization’s particular needs, learning from small pilot programs, following up with mentoring pairs during a committed formal mentoring period, and evaluating results from each program’s cycle to learn and grow the program. Supplementary materials for this article are available online.     

Assessing overweight, obesity, diet, and physical activity in college students

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) > or = 25 kg/m2 or BMI > or = 85th percentile and BMI > or = 30 kg/m2 or BMI > or = 95th percentile to estimate overweight and obesity in those aged < or = 19 years. To define overweight and obesity in those > or = 20 years, they used BMI > or = 25 kg/m2 and > or = 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.     

The hunt for a cure for Parkinson's disease

Several exciting new scientific advances have been made in the past decade toward both understanding the causes of and finding a cure for Parkinson's disease. Heartened by an acceleration in research findings in the past several years, the government has recently called for an infusion of funds from both the National Institutes of Health and private foundations into this burgeoning area of biomedical research. Most currently available conventional treatments for the disease only temporarily delay symptom presentation while doing nothing to halt disease progression. However, the rapidly accelerating pace of research in this field has left researchers hopeful that Parkinson's will be the first major age-related neurodegenerative disease for which we have a viable cure. In this article, advances in various areas of Parkinson's disease research are reviewed.     

Focal points in pure coordination games: An experimental investigation

This paper reports an experimental investigation of the hypothesis that in coordination games, players draw on shared concepts of salience to identify focal points on which they can coordinate. The experiment involves games in which equilibria can be distinguished from one another only in terms of the way strategies are labelled. The games are designed to test a number of specific hypotheses about the determinants of salience. These hypotheses are generally confirmed by the results of the experiment.