Free trade versus community: Social and environmental consequences of free trade in a world with capital mobility and overpopulated regions

Free trade based on comparative advantage is a widely accepted economic doctrine. The pure logic of comparative advantage, within the context of its assumptions, is unassailable. However, in a world characterized by demographic explosion, ecological stress, and free capital mobility, free trade does not serve the interests of wage-earners in countries with a relatively higher standard of living; it tends to undermine the national community that embraces both labor and capital.For a more extended discussion of some of the issues raised here, see Herman E. Daly and John B. Cobb, Jr. (1989).For the common good: redirecting the economy toward community, the environment, and A sustainable future. Boston: Beacon Press.     

A model for analyzing insect stage-frequency data when mortality varies with time

Summary A model is developed for the analysis of insect stage-frequency data which may be applied to populations with age-dependent mortality. The analysis of stage-frequency data is divided into two steps. In the first step, the number of different mortality rates and their values are estimated. The second step provides estimates of developmental rates and variances for each developmental stage and in addition provides estimates of the number of recruits to each stage. The model may be used both in analysis and prediction of insect stage frequencies. Hence, in addition to estimating developmental and mortality rates from stage-frequency data, it may also be used as a simulation model for an insect population. The model is applied to two populations ofHemileuca oliviae Cockerell, a lepidopterous pest of New Mexico grasslands. The model identifies, in the two populations, different mortality rates that are related to plant productivity.     

Land fragmentation under rapid urbanization: A cross-site analysis of Southwestern cities

Explosive population growth and increasing demand for rural homes and lifestyles fueled exurbanization and urbanization in the western USA over the past decades. Using National Land Cover Data we analyzed land fragmentation trends from 1992 to 2001 in five southwestern cities associated with Long Term Ecological Research (LTER) sites. We observed two general fragmentation trends: expansion of the urbanized area leading to fragmentation in the exurban and peri-urban regions and decreased fragmentation associated with infill in the previously developed urban areas. We identified three fragmentation patterns, riparian, polycentric, and monocentric, that reflect the recent western experience with growth and urbanization. From the literature and local expert opinion, we identified five relevant drivers ?C water provisioning, population dynamics, transportation, topography, and institutions ?C that shape land use decision-making and fragmentation in the southwest. In order to assess the relative importance of each driver on urbanization, we linked historical site-specific driver information obtained through literature reviews and archival analyses to the observed fragmentation patterns. Our work highlights the importance of understanding land use decision-making drivers in concert and throughout time, as historic decisions leave legacies on landscapes that continue to affect land form and function, a process often forgotten in a region and era of blinding change.     

Fugitives as fish: bounty hunting and exploitation of the commons

This note examines the property rights aspects of bounty hunting, and suggests that fugitives within the criminal justice system represent a common property resource. Economic theory might predict that this resource would be over exploited, perhaps resulting in industry profits being driven to zero. It is argued, however, that, in addition to regulation, recently developed concepts regarding uncertainty and heterogeneity of exploitation skills likely work to limit exploitation effort in bounty hunting. The anecdotal evidence and inference provided in this note make for a compelling pedagogical device for principles and intermediate economics students.     

生育与死亡转变对人口老龄化和老年抚养的影响

上海、北京和天津市在20世纪都经历了生育率急剧下降和预期寿命大幅度上升。生育率和死亡率的这些变化形成并将继续形成大量的老年人口。文章分析了这三大城市及中国的老年人口状况和未来的增长趋势,并就中国及这三个城市的人口趋势对老年抚养的影响进行讨论。     

Testing for Additivity at Select Mixture Groups of Interest Based on Statistical Equivalence Testing Methods

Several assumptions, defined and undefined, are used in the toxicity assessment of chemical mixtures. In scientific practice mixture components in the low-dose region, particularly subthreshold doses, are often assumed to behave additively (i.e., zero interaction) based on heuristic arguments. This assumption has important implications in the practice of risk assessment, but has not been experimentally tested. We have developed methodology to test for additivity in the sense of Berenbaum (Advances in Cancer Research, 1981), based on the statistical equivalence testing literature where the null hypothesis of interaction is rejected for the alternative hypothesis of additivity when data support the claim. The implication of this approach is that conclusions of additivity are made with a false positive rate controlled by the experimenter. The claim of additivity is based on prespecified additivity margins, which are chosen using expert biological judgment such that small deviations from additivity, which are not considered to be biologically important, are not statistically significant. This approach is in contrast to the usual hypothesis-testing framework that assumes additivity in the null hypothesis and rejects when there is significant evidence of interaction. In this scenario, failure to reject may be due to lack of statistical power making the claim of additivity problematic. The proposed method is illustrated in a mixture of five organophosphorus pesticides that were experimentally evaluated alone and at relevant mixing ratios. Motor activity was assessed in adult male rats following acute exposure. Four low-dose mixture groups were evaluated. Evidence of additivity is found in three of the four low-dose mixture groups. The proposed method tests for additivity of the whole mixture and does not take into account subset interactions (e.g., synergistic, antagonistic) that may have occurred and cancelled each other out.