Order Consolidation for Batch Processing

We consider the batch processing of orders where either whole or part of a single order or a specific pair of different orders may be grouped in a batch with a fixed capacity. The problem can be modelled by a graph G = (V,E), where each node v V corresponds to an order, its weight w(v) corresponds to the amount of ordered quantity and a pair of orders, say u and v may be grouped in a batch if there exists the edge (u,v) E. The objective is to maximize the number of batches filled up to its capacity . In this paper, we prove that the problem is NP-hard and, moreover, that no PTAS exists unless P = NP. Then, an optimal algorithm is developed with running time O(|V|log |V|) for the special case when G is a tree.     

Design of Panel Studies for Disease Progression with Multiple Stages

A panel study consists of individuals who have data collected at periodic follow-up visits or pre-specified time points following entry into the study. The objective of this paper is to consider design issues in a panel study when the response variable is the stage of disease, and with focus on the transition intensities. Important design issues include the choice of the time interval between follow-up visits and sample size considerations. We study the effects of time intervals between follow-up visits on the precision of the transition intensities estimators. We also consider the power of statistical tests on the ratio of transition intensities. Discussion is extended to incorporate heterogeneity in the population in which frailty is introduced to describe subject-specific transition intensities.     

Neighborhood Selection and Residential Segregation

Residential segregation has long been a topic of investigation for urban scholars. In attempting to understand this phenomenon, most researchers have examined the characteristics of different residential neighborhoods (typically census tracts) and have often compared the composition of the population within the census tract over time. This study looks at the household characteristics of the mobile family, as well as the aggregate characteristics of the census tract into which the family moves. The findings reveal that households display a tendency to move to areas where the existing population has characteristics similar to their own. A multiple logit analysis reveals that the race/ethnicity of the household is generally the best predictor of the neighborhood where the household will move.     

Nonmetropolitan Residential Segregation Revisited

Abstract Nonmetropolitan (nonmetro) residential segregation in 1990 and change in the preceding decade have received insufficient attention. A set of empirical hypotheses are derived and assessed using nonmetro and metropolitan (metro) counties in Texas. Places in nonmetro counties were more segregated than places in metro counties in 1990 as in 1980. Substantial declines in segregation occurred in both nonmetro and metro places but were largest in growing places in nonmetro counties. An analysis controlling for other determinants of segregation supports the premise that population change was a major determinant of 1980–1990 change in segregation. Implications for nonmetro areas in the 1990s are discussed.     

Father-mother infant interaction in traditional and nontraditional Swedish families: A longtitudinal study

The effects of parental gender and caretaking role on parental attitudes, parent-infant interaction, infant-parent attachment, infants' sociability with strangers and their parental preferences were examined in a longitudinal study of fifty-one Swedish couples. Fathers who later spent more than a month out of the first nine as primary caretakers were considered involved or nontraditional. The parents were interviewed separately, prenatally, and five months postnatally. Parent-infant interaction was observed, security of attachment and sociability with strangers were assessed, and the infants' parental preferences were determined. Many parental attitudes were stable from the pre-to postnatal interview. Parenthood and work were more highly valued by nontraditional than traditional parents. Regardless of relative involvement in child care, infants directed more affiliative and attachment behaviors to their mothers than to their fathers. No relationship was found between relative parental involvement and the security of infant attachment. There was also no relationship between the security of infant-mother and infant-father attachments.     

ABOUT THE AUTHORS

Work satisfaction, self‐esteem, and alienation measures were obtained from white males in three service occupations (bartenders, barbers, and mailmen) at different levels of the occupational prestige hierarchy. While we found an overall positive relationship between work satisfaction and occupational prestige, this only held for variables where societal reference groups were forced upon the respondents. Such findings suggest that the relationship between work satisfaction and occupational prestige is less absolute than usually suggested by the literature. Hypotheses from the literature arguing for a direct relationship between occupational prestige and alienation were not supported by our data. We conclude that sociologists probably overestimate the salience of work and occupational prestige for the working class.     

Historical writing on migration into the commonwealth Caribbean: A bibliographical review of the period c.1838‐c.1938

For almost a century after slave emancipation in the Commonwealth Caribbean a steady stream of immigrants entered the colonies, from such diverse places as India, Africa, Europe, China, North America, Syria and Lebanon. Historical scholarship on these migrants has concentrated heavily on the Indians, while almost completely neglecting the Syrian/Lebanese. Moreover, the main emphasis has been on the economic roles of the migrants within the dominant plantation sector. Recently, however, increasing attention has been focused on the non‐plantation sectors, while interesting and scholarly work is also emerging on the socio‐cultural aspects of immigrant society. Much research still needs to be done on migrants into the smaller Caribbean islands. Although small in number by comparison with those migrating to Guyana and Trinidad, a knowledge of their roles in and adaptation to their host societies will help us to understand more fully the impact of post‐emancipation migration on the Commonwealth Caribbean.     

Living arrangements and level of care among clients discharged from a scattered-site housing-based independent living program

There is little recent research in the field of adolescent independent living that looks at the specific living arrangements of youth, who at the point of discharge from the child welfare system, had experienced living independently and had access to a choice of housing options. Administrative data and reviews of client records were used in this study to look at the choice of housing option and the change in level of care of 367 young adults who emancipated from the Lighthouse Youth Services Independent Living Program in Cincinnati, Ohio, during the five-year period 2001-2006. Given a range of housing options at the time of discharge, over half (55%) chose an independent living arrangement, including 41% who lived in their own place, either alone (28%) or with a roommate (13%). Only 21% decided to live in someone else's home, including just 7% with one or both birth parents, 10% with some other relative, and 4% with a non-relative. The remaining 24% of youth were discharged from independent living to a more restrictive living arrangement (a.k.a., higher “level of care”, including a residential treatment program, group home, foster care, or supervised independent living program) (11%) or whose whereabouts were unknown (13%). The outcomes of this study suggest that, when presented with a choice of housing options, most of this county's emancipating foster youth would prefer to live on their own, rather than to return to live with their families of origin. The study also suggests that many youth who participate in a scattered-site housing-based independent living program can succeed in leaving care with affordable housing in place and avoid immediate homelessness.