Use of Acute Toxicity to Estimate Carcinogenic Risk

Data on the effects of human exposure to carcinogens are limited, so that estimation of the risks of carcinogens must be obtained indirectly. Current risk estimates are generally based on lifetime animal bioassays which are expensive and which take more than two years to complete. We here show how data on acute toxicity can be used to make a preliminary estimate of carcinogenic risk and give an idea of the uncertainty in that risk estimate. The estimates obtained are biased upwards, and so are useful for setting interim standards and determining whether further study is worthwhile. A general scheme which incorporates the use of such estimates is outlined, and it is shown by example how adoption of the procedures suggested could have prevented regulatory hiatus in the past.     

Revolutionary Mexico and the world economy

Conclusion Obregón and Calles encountered intense but disunited resistance at home and abroad. They responded with land and labor reforms to coopt campesinos and urban workers, thereby undercutting popular opposition and enlisting the masses in the campaign against regionalist bosses, Porfirian oligarchs, and foreign investors. These populist alliances helped the Sonoran diarchy build more loyal and professional military and civilian bureaucracies, which in turn helped regulate local and metropolitan firms, increase and stabilize tax revenues, and develop the economy's infrastructure. Following Obregón assasination in 1928, Calles forestalled collapse by integrating many military and civilian bosses into a central party organization. Yet the state remained only partially consolidated. At the end of the Calles administration, regionalist cliques retained considerable political autonomy, and a major campesino rebellion challenged federal authority. Furthermore, dependence on foreign petroleum and mining companies limited government revenue and spending. In mid-1927, Calles inaugurated several years of conservative domestic policies and open collaboration with North Americans. But Calles did not purge all progressive elements from the state machinery. His quest for political stability led him to enroll in the official party many elites who depended on mass followings and who opposed the rightward shift of government policy. During the Great Depression, these elites formed a coalition with intellectuals, small business, and the lower classes that after electing Lázaro Cardenas president, ended Callista hegemony and undertook far-reaching reforms. Thus the Cardenistas completed what Obregón and Calles had begun: the Mexican state's transformation from the poorly centralized oligarchic structure of the Porfiriato to the highly centralized, mass-inclusionary structure of the postrevolutionary era. In the next decade, Mexico joined the ranks of the world's intermediate, semiperipheral economies thanks to import-substitution and metropolitan capital. Since then, Mexican governments have maintained political stability and spurred industrialization by steering a pragmatic course between reformism and conservatism, nationalism and collaborationism.In regard to future research, this essay suggests that we consider not only Mexico's relationship to North Atlantic powers in the 1920s but also its standing vis-à-vis the states and classes of other late-industrializing countries. One possibility is to study the interplay of metropolitan actions to control the raw materials and markets of the periphery with the politics of resistance and accommodation throughout the Caribbean basin: How did international and local conflicts affect the distribution of United States and Western European investments in the Caribbean basin? What impact did metropolitan investments have on the region's struggles over state power and pattern of economic change? How did the state-building struggles and economic changes of the 1920s influence the region's nationalist break-throughs and defeats during the Great Depression and World War II? What were the consequences of nationalist successes and failures for the subsequent paths of state making and economic development in the Caribbean basin, as well as for North Atlantic investors and governments after World War II?     

论嗜杀物种

包括黑猩猩在内的很多物种的动物都经常杀害同类。这些事实再次引起了关于进化过程中形成的生物特性是否影响着以及如何影响着人类好战的倾向等问题的讨论。要讨论这方面的问题,需要区分动物的两类暴力行为,即“猎杀”与“斗杀”。猎杀是猎食者对无助的动物的攻击。小群的黑猩猩或游动性的狩猎—采集者有时会杀死邻近社群的竞争对手。现有的资料表明,由这种群间攻击导致的死亡在总的死亡率中所占的比例与人类与黑猩猩这两个物种大致相同。这方面行为的普遍性说明这两个物种都存在进化过程中形成的致命的暴力行为,其认知能力也适应了成功地进行杀戮的需要。     

Self‐consistent estimation of mean response functions and their derivatives

Many methods have been developed for the nonparametric estimation of a mean response function, but most of these methods do not lend themselves to simultaneous estimation of the mean response function and its derivatives. Recovering derivatives is important for analyzing human growth data, studying physical systems described by differential equations, and characterizing nanoparticles from scattering data. In this article the authors propose a new compound estimator that synthesizes information from numerous pointwise estimators indexed by a discrete set. Unlike spline and kernel smooths, the compound estimator is infinitely differentiable; unlike local regression smooths, the compound estimator is self‐consistent in that its derivatives estimate the derivatives of the mean response function. The authors show that the compound estimator and its derivatives can attain essentially optimal convergence rates in consistency. The authors also provide a filtration and extrapolation enhancement for finite samples, and the authors assess the empirical performance of the compound estimator and its derivatives via a simulation study and an application to real data. The Canadian Journal of Statistics 39: 280–299; 2011 © 2011 Statistical Society of Canada     

Sensitivity Analysis Revisted and Extended

The tolerance approach to sensitivity analysis in linear programming provides a framework for dealing with simultaneous and independent variations of the coefficients and terms. Specifically, the approach yields a maximum tolerance percentage which in turn characterizes a region of variability for the coefficients or terms. This paper shows how to expand this region of variability yielding ordinary sensitivity analysis as a special case of the tolerance approach.     

INDUSTRY STUDIES AND AMERICAN INDUSTRIAL PERFORMANCE

A nationwide research program on the performance of American industry, sponsored by the Alfred P. Sloan Foundation, now involves scores of faculty researchers and more than 100 graduate students at several American universities. Ten research centers have been established, and each one is dedicated to the study of a particular industry. An eleventh center is carrying out research on problems that cut across these industries. It is expected that the Sloan Industry Studies program will make useful contributions to the performance of the industries themselves, to policymaking at all levels of government, and to the development of interdisciplinary research communities within the universities.     

Configurations of informal social support among older lesbians

Limited research has been conducted on the needs and concerns of older lesbians in the American population. The purpose of this paper is to present findings from a qualitative study of older (aged 55 and older) lesbians' experiences of and perspectives on aging, with a focus on their discussions of social support. Through an in-depth qualitative study with 25 older lesbians, we found that aging lesbians may be less likely to access formal social services due to perceptions of bias within the services and a potential lack of connection with those who do use services. However, participants were creative at formulating informal networks of support. Four heuristic categories (empowered, secure, independent, and precarious) of informal social support were developed to characterize the various ways in which participants configured their support systems. Social support within each category was conceptualized both in terms of intentionality and degree of connectedness. Being partnered did not necessarily equate with a strong sense of social support. Further research needs to be conducted on older lesbians in order to better characterize and respond to their needs as they age.