A NOTE ON OPTIMAL PORTFOLIO SELECTION UNDER STABLE PARETIAN DISTRIBUTIONS*

Elton, Gruber, and Padberg's [2] [3] ranking procedure and Kwan's [6] nonranking procedure for optimal portfolio selection lead to the same solution. This is because of a particular functional property of the cutoff rate for security performance. In this note, the robustness of that functional property is demonstrated the normality of security returns assumed in the above studies is relaxed to encompass the general family of stable Paretian distributions. The proof here is an important step toward portfolio analysis using some multiindex models when securities cannot be ranked.     

Diversity and change in Cambodian households, 1998–2006

Extant ethnographic studies suggest that the nuclear family has been the predominant living arrangement in Cambodia, and the country’s rapid socioeconomic transformation since the early 1990s may have accentuated that dominance. To examine these claims, we analyse here household structure in Cambodia between 1998 and 2006, based on data from the 1998 Census, two nationally-representative surveys (2000 and 2005), and a continuing demographic surveillance system (from 2000 on). Our analysis confirms the large prevalence of nuclear families, but not an unequivocal trend toward their increasing prevalence. First, nuclear families are less prevalent in urban than in rural areas, and nationwide, they appear to have receded slightly between 2000 and 2005. We find that increases in the prevalence of extended households correspond to periods of faster economic growth, and interpret these contrasted trends as signs of tensions during this transitional period in Cambodia. While the nuclear family may still be the cultural norm, a high degree of pragmatism is also evident in the acceptance of other living arrangements, albeit temporary, as required by economic opportunities and housing shortage in urban areas.     

Barossa Night: cohesion in the British Army officer corps

Contrasting the classical explanation of military group cohesion as sustained by interpersonal bonds, recent scholars have highlighted the importance of ritualized communication, training and drills in explaining effective military performance in professional armies. While this has offered a welcome addition to the cohesion literature and a novel micro‐sociological method of examining cohesion, its primary evidential base has been combat groups. Indeed, despite their prominent role in directing operations over the past decade, the British Army's officer corps has received relatively little attention from sociologists during this period. No attempt has been made to explain cohesion in the officer corps. Using a similar method to recent cohesion scholars, this paper seeks to address this imbalance by undertaking a micro‐sociology of one ritual in particular: ‘Barossa Night’ in the Royal Irish Regiment. Firstly, it draws on the work of Durkheim to examine how cohesion amongst the officer corps is created and sustained through a dense array of practises during formal social rituals. It provides evidence that the use of rituals highlights that social solidarity is central to understanding officer cohesion. Secondly, following Hockey's work on how private soldiers negotiate order, the paper shows how this solidarity in the officer corps is based on a degree of negotiated order and the need to release organizational tensions inherent in a strictly hierarchical rank structure. It highlights how the awarding of gallantry medals can threaten this negotiated order and fuel deviancy. In examining this behaviour, the paper shows that even amongst an officer class traditionally viewed as the elite upholders of organizational discipline, the negotiation of rank and hierarchy can be fluid. How deviant behaviour is later accepted and normalized by senior officers indicates that negotiated order is as important to understanding cohesion in the British Army's officer corps as it is amongst private soldiers.     

Time preferences and consumer behavior

We investigate the predictive power of survey-elicited time preferences. The discount factor elicited from choice experiments using real payments predicts various health, energy, and financial outcomes, including overall self-reported health, smoking, installing energy-efficient lighting, and credit card balance. Allowing for time-inconsistent preferences, both the long-run and present-bias discount factors (δ and β) are also significantly associated in the expected direction with several outcomes. We consider several hypotheses regarding the strength of the association between discount factors and outcomes, such as salience of the outcome or liquidity constraints.     

One-Parent Families in Contemporary Cambodia

Nonmarital births and divorce are rare in Cambodia. Because of dramatic levels of adult mortality reached during the late 1970s, however, growing up with a single parent is not rare. Using nationally representative, cross-sectional data, we estimate that about 12% of children under age 18 co-reside with only one of their biological parents. Using longitudinal data representative of the Mekong River Valley, we found this proportion to be declining. Nearly half of these children live in nuclear families (single parent with or without a stepparent), even though they live in multigenerational families more frequently than children who live with both their parents, especially when young and not living with their mother. Finally, we consider differences in socioeconomic conditions and child educational outcomes by number of co-residing parents.     

Strategic Experimentation

This paper extends the classic two-armed bandit problem to a many-agent setting in which N players each face the same experimentation problem. The main change from the single-agent problem is that an agent can now learn from the current experimentation of other agents. Information is therefore a public good, and a free-rider problem in experimentation naturally arises. More interestingly, the prospect of future experimentation by others encourages agents to increase current experimentation, in order to bring forward the time at which the extra information generated by such experimentation becomes available. The paper provides an analysis of the set of stationary Markov equilibria in terms of the free-rider effect and the encouragement effect.     

Development and Validation of the Post-Dissolution Relational Communication Index

Relational dissolution is a distressing life event. Dissolution is further complicated when communication between ex-partners is inefficient, unpredictable, and strained. This examination uncovers the aspects of postdissolutional communication in a 2-part study. In Study 1, 271 participants experiencing a breakup completed surveys regarding their communication with an ex-romantic partner. The study empirically operationalizes these behaviors in the Post-Dissolution Relational Communication Index and reports on the factor structure, reliability, and convergent validity of the 2-factor solution produced. Both factors were significantly correlated with participants’ reports of communication satisfaction with a former relationship partner and the perceived seriousness of the relationship. In Study 2, self-reports from 151 participants who had experienced a divorce provided support for its use with divorced couples. A third factor was identified illustrating differences between nonmarital and marital ex-partners. Implications for postdissolution relationships and satisfaction with former partners are addressed. Furthermore, suggestions for practice are discussed.     

Substance misuse amongst young people in non‐school settings: challenges to practitioners and policy makers

Over the past two decades the levels of substance misuse amongst children and young people have increased at a global level generally and within the UK in particular. Some school aged young people are considered to be at an increased risk to substance misuse, particularly those outside mainstream school. However, the literature on substance use by these young people remains comparatively limited. This paper explores this issue through an investigation of cannabis use trends amongst the High Risk Booster Sample of the Belfast Youth Development Study, a longitudinal study of adolescent substance use. It focuses upon the cannabis use patterns of young people excluded from school and those attending Emotional and Behavioural Difficulty units from the age of 11–16 years, groups who are historically categorised as vulnerable to substance misuse. The experience of these young people provides evidence to highlight the contemporary challenges facing policy makers and practitioners when addressing substance use and misuse use amongst these young people. Copyright © 2009 John Wiley & Sons, Ltd.     

生态工程:可持续的环保理念

每年夏天,世界很多国家都会担心泥石流的问题.要如何才能走出这样的困境?"生态工程"正为我们提供了一条改变的线索.生态工程的具体实行,简单地说就是让水能循环,让土壤能呼吸,让动植物得以安全生长、繁衍.这些看来好像教科书里的教条,要如何实践干生活中呢?