Immigration cohorts and residential overcrowding in southern California

To what degree do immigrants reduce their high rates of residential overcrowding with increasing length of residence in the United States? This question is addressed through the application of a “double cohort” method that nests birth cohorts within immigration cohorts. This method enables duration of immigration effects to be separated from aging effects as cohorts pass through life course phases, when family sizes may be growing or shrinking. The analysis finds that cohort trends differ sharply from the cross-sectional pattern observed at a single point in time. Cohorts’ growth in income is found to contribute substantially to the decline in overcrowding over time. Cohort trends among Hispanic immigrants, however, diverge from those among others, indicating much less decrease in overcrowding and even increases over certain age spans.     

Asian American Elderly:

Many existing public assumptions held by social workers about Asian American elderly are misleading. These socially and economically disadvantaged pebple are systefitically excluded from having access to the professional social service, both culturally and structurally. This article studies their negative historical experiences, structural difficulties and cultural barriers in acquiring the necessary social services.     

Price vs. revenue stabilization through a buffer stock: Which is more financially feasible for LDCs?

Optimal control theory is used to analyze the implications of the adoption of price and LDC export revenue stabilization objectives by an international buffer stock for cocoa. The results obtained for the period 1956–76 suggest that the stabilization of either price or revenue at systematic trend would reduce the instability of both variables from that during the sample period. Although the stabilization of revenues at systematic trend decreases their average level, the stabilization of price has the opposite effect. Because of this, it may be financially feasible for the LDCs to provide the necessary resources for a price-stabilizing buffer stock.     

TIME ALLOCATION IN AN EXCHANGE-PRODUCTION PARADIGM

The three uses of one's time — leisure, nonmarket work, and market work — are affected by the availability of others' time for sale in the market. The paper integrates the supply of time and the demand for others' time by means of geometric models of exchange and production. Possible patterns of market work behavior are enriched by the incorporation of proportional and lump-sum transaction costs. The diversity of the results argues against indiscriminate reliance on institutional restrictions in explaining work decisions.     

Men's perceptions and knowledge of human papillomavirus (HPV) infection and cervical cancer

The authors assessed young men's knowledge and perceptions of genital human papillomavirus (HPV) infection to identify factors that predict intention to make positive behavioral changes. Male university students aged 18 to 25 years completed a self-report instrument to assess knowledge and perceptions of genital HPV infection. If diagnosed with HPV, most men (95%) reported that they would use condoms with new partners. The intention to reduce number of sex partners was associated with an understanding that HPV may have severe consequences for women, whereas intention to encourage female sex partners to undergo Pap smear screening was associated with increased general knowledge of HPV infection. The authors concluded that it is important to include men in HPV education and prevention efforts, especially within the context that HPV may lead to cervical cancer in female partners.     

Gambling Screens: Does Shortening the Time Frame Affect their Psychometric Properties?

Gambling screening tools such as the South Oaks Gambling Screen (SOGS) and a DSM-IV Screen for Gambling Problems (NODS) developed by the National Opinion Research Council have psychometrically validated lifetime and past-year versions. As research questions often dictate shorter time intervals, researchers have adapted the time frames of these instruments to their specific purposes without examining whether changing the time frame affects the psychometric properties. In this study, 3-month versions of SOGS and NODS were administered to a sample of 80 pathological gamblers (59 men, 21 women, mean age 44) seeking treatment at a state-funded facility. The 3-months versions had good internal consistency, good convergent validity with each other, with gambling behaviors assessed via the timeline followback method, and with measures of impulsivity. The 3-month versions also showed good discriminant validity with demographic variables and a measure of verbal IQ. Together the data indicate that shortening the time frame to 3 months does not seem to have adverse effects on the psychometric properties of SOGS and NODS. Thus these adapted versions could profitably be used for shorter time intervals, including as pre/post-treatment and follow-up measures in treatment outcome studies.     

Two Variations of the Minimum Steiner Problem

Given a set S of starting vertices and a set T of terminating vertices in a graph G = (V,E) with non-negative weights on edges, the minimum Steiner network problem is to find a subgraph of G with the minimum total edge weight. In such a subgraph, we require that for each vertex s S and t T, there is a path from s to a terminating vertex as well as a path from a starting vertex to t. This problem can easily be proven NP-hard. For solving the minimum Steiner network problem, we first present an algorithm that runs in time and space that both are polynomial in n with constant degrees, but exponential in |S|+|T|, where n is the number of vertices in G. Then we present an algorithm that uses space that is quadratic in n and runs in time that is polynomial in n with a degree O(max {max {|S|,|T|}–2,min {|S|,|T|}–1}). In spite of this degree, we prove that the number of Steiner vertices in our solution can be as large as |S|+|T|–2. Our algorithm can enumerate all possible optimal solutions. The input graph G can either be undirected or directed acyclic. We also give a linear time algorithm for the special case when min {|S|,|T|} = 1 and max {|S|,|T|} = 2.The minimum union paths problem is similar to the minimum Steiner network problem except that we are given a set H of hitting vertices in G in addition to the sets of starting and terminating vertices. We want to find a subgraph of G with the minimum total edge weight such that the conditions required by the minimum Steiner network problem are satisfied as well as the condition that every hitting vertex is on a path from a starting vertex to a terminating vertex. Furthermore, G must be directed acyclic. For solving the minimum union paths problem, we also present algorithms that have a time and space tradeoff similar to algorithms for the minimum Steiner network problem. We also give a linear time algorithm for the special case when |S| = 1, |T| = 1 and |H| = 2.An extended abstract of part of this paper appears in Hsu et al. (1996).Supported in part by the National Science Foundation under Grants CCR-9309743 and INT-9207212, and by the Office of Naval Research under Grant No. N00014-93-1-0272.Supported in part by the National Science Council, Taiwan, ROC, under Grant No. NSC-83-0408-E-001-021.     

The Expectation-Threshold model of reproductive decision making

It is proposed that as expectations about parenting become increasingly high, couples have an increasing tendency to decide to have a(or another) child. Similarly, as parenting expectations become increasingly low, couples have an increasing tendency to decide on sterilization. Couples without extremely high or low expectations continue to use contraceptives. Expectations are defined as Subjective Expected Utilities (SEUs) for having or not having a child. Preliminary results support the model and suggest that the threshold for making these decisions is not at neutral, but is conservative so that couples must have fairly high or low expectations before making such binding decisions are parenting or sterilization. The fact that data reveal that this exists supports the Expectancy-Threshold model, but it also requires a change in SEU Theory's maximization rule for some kinds of decisions.The authors wish to thank Carole Baker, former executive Director of the National Alliance for Optional Parenthood, and the board members of that organization for their cooperation, and Dr. Barbara Beach who helped with the data analysis. Funding was provided, in part, by The Center for Studies in Demography and Ecology, University of Washington, through a grant, No. 5 P30 HDO 9397, from the National Institute for Child Health and Human Development