Population growth: U.S. and Latin American views

Abstract This article is an attempt at interpretation. As one who has worked professionally both in the United States and in Latin America, I would like to interpret how I see the United States and Latin America responding to the high Latin American population growth rate. This is a personal interpretation and as such, of course, is biassed. It is also a very broad subject to which a few pages of interpretation can hardly do justice. The very generalizations 'the United States' and 'Latin America' lend themselves to misunderstanding. These are not homogeneous areas but contain a variety of forces pulling in many directions. And yet, just because this is such a difficult subject as well as such an important one in the world of to-day, it is perhaps worth while to try to distil some common components which may help us gain a better understanding of the actions of others as well as our own.     

Male sterilization as a contraceptive method in Canada an empirical study

Abstract In 1851-61, the crude birth rate in Canada was 45. In 1972, it was approximately 16. Not only have birth rates decreased but the average family size has declined from five or six children per family at the turn of the century to two or three children in the 1970'S. In addition, women are completing their childbearing at an earlier age. 50 years ago, it was not uncommon for a woman to have a child in her late thirties or early forties. To-day, this is a relatively rare event. In fact, it is estimated that approximately 80% of all families have the number of children desired before the woman is 30 years of age. This new demographic pattern creates an important and crucial situation for Canadian couples. At age 30, with all the desired children and 15 more years of potential childbearing ahead of them, what can they do to prevent the occurrence of additional pregnancies?     

Tables for the analysis of selective predation experiments

Summary This paper discusses the analysis of selective predation experiments with two types of prey when the prey are not replaced after they have been removed by the predators. In an earlier paper (Manly et al., 1972) consideration was given to situations where the replication of experiments allows the estimation of standard errors from the experimental results; in the present paper a table of standard errors is given for a large range of experiments and replication is therefore no longer necessary. The standard errors were calculated on an electronic computer by solving the exact equations given in the earlier paper. The suggested method of analysis is illustrated using some data where the prey were red and yellow artificial ‘maggots’ and the predators were garden birds.     

Joint modified block replacement and production/inventory control policy for a failure-prone manufacturing cell

This paper considers a joint preventive maintenance (PM) and production/inventory control policy of an unreliable single machine, mono-product manufacturing cell with stochastic non-negligible corrective and preventive delays. The production/inventory control policy, which is based on the hedging point policy (HPP), consists in building and maintaining a safety stock of finished products in order to respond to demand and to avoid shortages during maintenance actions. Without considering the impact of preventive and corrective actions on the overall performance of the production system, most authors working in the reliability and maintainability domains confirm that the age-based preventive maintenance policy (ARP) outperforms the classical block-replacement policy (BRP). In order to reduce wastage incurred by the classical BRP, we consider a modified block replacement policy (MBRP), which consists in canceling a preventive maintenance action if the time elapsed since the last maintenance action exceeds a specified time threshold. The main objective of this paper is to determine the joint optimal policy that minimizes the overall cost, which is composed of corrective and preventive maintenance costs as well as inventory holding and backlog costs. A simulation model mimicking the dynamic and stochastic behavior of the manufacturing cell, based on more realistic considerations of the real behavior of industrial manufacturing cells, is proposed. Based on simulation results, the joint optimal MBRP/HPP parameters are obtained through a numerical approach that combines design of experiment, analysis of variance and response surface methodologies. The joint optimal MBRP/HPP policy is compared to classical joint ARP/HPP and BRP/HPP optimal policies, and the results show that the proposed MBRP/HPP outperforms the latter. Sensitivity analyses are also carried out in order to confirm the superiority of the proposed MBRP/HPP, and it is observed that for practitioners, the proposed joint MBRP/HPP offers not only cost savings, but is also easy to manage, as compared to the ARP/HPP policy.     

Race and the local politics of punishment in the new world of welfare

To illuminate how race affects the usage of punitive tools in policy implementation settings, we analyze sanctions imposed for noncompliant client behavior under welfare reform. Drawing on a model of racial classification and policy choice, we test four hypotheses regarding client race, local context, and sanctioning. Based on longitudinal and cross-sectional multilevel analyses of individual-level administrative data, we find that race plays a significant role in shaping sanction implementation. Its effects, however, are highly contingent on client characteristics, local political contexts, and the degree to which state governments devolve policy control to local officials.     

Neighborhood perceptions and parent outcomes in family based prevention programs for Thai adolescents: the role of program engagement

Due to concerns over Thai adolescent risky behaviors, effective prevention strategies are needed. Determining the role neighborhood context plays in program engagement and outcomes may inform these strategies. This study includes 170 mother-adolescent pairs (M = 13.44, SD = .52) in Bangkok, Thailand in a prevention program for adolescent substance use and sexual risk. Neighborhoods were related to engagement, which was critical to outcomes. Neighborhood disorganization was related to confidence in program effects and program completion. Completion was related to increased ATOD communication. Neighborhood cohesion was related to less program enjoyment, while neighborhood social control was related to more enjoyment. Enjoyment was related to increased ATOD communication and formation and monitoring of alcohol rules. Prevention strategies should focus on neighborhood contexts and enhancing engagement.     

The Short and Long-Run Labor Market Effects of Age Eligibility Rules: Evidence from Women’s Professional Tennis

Age is often used in law and public policy as a low-cost proxy for competency, maturity, and ability. Age is also used in numerous sport (and non-sport) labor markets to determine workplace eligibility. We exploit the enactment of the women’s professional tennis minimum age rule (AR) in 1995 to estimate the effects of ARs on short-run and long-run labor market outcomes. We find very limited evidence that the AR has had any systematic beneficial effect on players’ career longevity or success. Our results suggest that sport governing bodies should (re-)evaluate the efficacy and necessity of “one size fits all” age eligibility rules.