Sampling Strategies for Toxic Air Contaminants

Annual concentrations of toxic air contaminants are of primary concern from the perspective of chronic human exposure assessment and risk analysis. Despite recent advances in air quality monitoring technology, resource and technical constraints often impose limitations on the availability of a sufficient number of ambient concentration measurements for performing environmental risk analysis. Therefore, sample size limitations, representativeness of data, and uncertainties in the estimated annual mean concentration must be examined before performing quantitative risk analysis. In this paper, we discuss several factors that need to be considered in designing field-sampling programs for toxic air contaminants and in verifying compliance with environmental regulations. Specifically, we examine the behavior of SO2, TSP, and CO data as surrogates for toxic air contaminants and as examples of point source, area source, and line source-dominated pollutants, respectively, from the standpoint of sampling design. We demonstrate the use of bootstrap resampling method and normal theory in estimating the annual mean concentration and its 95% confidence bounds from limited sampling data, and illustrate the application of operating characteristic (OC) curves to determine optimum sample size and other sampling strategies. We also outline a statistical procedure, based on a one-sided t-test, that utilizes the sampled concentration data for evaluating whether a sampling site is compliance with relevant ambient guideline concentrations for toxic air contaminants.     

Smoothed bootstrap bandwidth selection for nonparametric hazard rate estimation

A smoothed bootstrap method is presented for the purpose of bandwidth selection in nonparametric hazard rate estimation for iid data. In this context, two new bootstrap bandwidth selectors are established based on the exact expression of the bootstrap version of the mean integrated squared error of some approximations of the kernel hazard rate estimator. This is very useful since Monte Carlo approximation is no longer needed for the implementation of the two bootstrap selectors. A simulation study is carried out in order to show the empirical performance of the new bootstrap bandwidths and to compare them with other existing selectors. The methods are illustrated by applying them to a diabetes data set.     

Legitimating the Philippines as a language learning space: Transnational Korean youth's experiences and evaluations

This paper examines how a peripheral English‐speaking country is constructed as a legitimate language learning space in the global English language teaching (ELT) industry by investigating South Koreans’ recent engagement in Philippine English education. It focuses on a short‐term English study abroad program, in which the Philippines serves as a transit place prior to students’ moving to a Western English‐speaking country. Drawing data from ethnographic research on South Korean youth studying English abroad, the article analyzes why Korean students seek Philippine English education in spite of their apparent pursuit of authentic English, and how they evaluate their learning experience in the Philippines. This paper finds that the Philippines holds a niche market in the global ELT industry by separating a space for English learning from other public and everyday spaces of English use and offering pedagogically intensive but emotionally supportive environments to English learners.     

Quantifying the synergistic effects of impervious surface and drought on radial tree growth

Urban Ecosystems - The global trend of increasing urbanization is generating isolated patches of vegetation that could be strongly influenced by the surrounding landscape. Simultaneously, many of...     

The Role of Family Behaviors in Determining Income Distribution: The Case of South Korea

In this article, we examined what has contributed to the worsening income inequality and poverty between 1996 and 2011 in South Korea. We used a rank-preserving exchange method and a conditional reweighting method to assess the roles of family behaviors—including female labor force participation and family structure—characteristics of household heads, and men’s earnings. The results showed that the change in men’s earnings was a dominant factor in accounting for the increasing income inequality and poverty. The change in age and education among household heads also contributed significantly to the worsening income distribution. The change in family structure mainly affected the income disparity among lower-income families and increased poverty. The rise in women’s labor force participation improved the income distribution but not considerably. The distributional roles of family have not worked to prevent or reverse the worsening income distribution in the past few decades in South Korea.     

Plant-mycorrhizal fungi associations along an urbanization gradient: implications for tree seedling survival

Mycorrhizal fungi symbioses can be critical determining if established seedlings survive or not. Currently, in remnant forests, plants and their fungal symbionts are exposed to varied anthropomorphic effects related to urbanization, however, little is known about their impact on this association. We investigated the relationship between mycorrhizal fungi and tree seedling survival along an urbanization gradient. We planted three species of temperate tree seedlings (Acer rubrum, Carya ovata, and Quercus rubra) in three landscapes: urban, suburban, and rural. We measured the percent of root length colonized by mycorrhizal fungi and monitored survival during their first growing season. We analyzed mycorrhizal colonization as a function of landscape type (urban-rural) and additional variables known to contribute to mycorrhizal colonization (phosphorus, nitrogen, initial plant height). We then analyzed seedling survival as a function of the degree of mycorrhizal fungi colonization associated with the landscape gradient and of additional environmental factors (light and soil moisture). Within a species we found no changes in the levels of mycorrhizal fungi colonization across the urbanization gradient. Each species, however, had markedly different levels of colonization. Survival of A. rubrum was independent of mycorrhizal colonization, while C. ovata and Q. rubra had a significant positive response to increased mycorrhizal fungi. These findings highlight the resilience of mycorrhizal communities across the rural-urban gradient typical of this region, but they also underscore the potential sensitivity of some tree species to lower levels of mycorrhizal fungi colonization.     

Objective Bayesian analysis based on upper record values from two-parameter Rayleigh distribution with partial information

In the life test, predicting higher failure times than the largest failure time of the observed is an important issue. Although the Rayleigh distribution is a suitable model for analyzing the lifetime of components that age rapidly over time because its failure rate function is an increasing linear function of time, the inference for a two-parameter Rayleigh distribution based on upper record values has not been addressed from the Bayesian perspective. This paper provides Bayesian analysis methods by proposing a noninformative prior distribution to analyze survival data, using a two-parameter Rayleigh distribution based on record values. In addition, we provide a pivotal quantity and an algorithm based on the pivotal quantity to predict the behavior of future survival records. We show that the proposed method is superior to the frequentist counterpart in terms of the mean-squared error and bias through Monte carlo simulations. For illustrative purposes, survival data on lung cancer patients are analyzed, and it is proved that the proposed model can be a good alternative when prior information is not given.     

Multistate projections by level of education for Portugal, 2011–2031

Educational attainment is an attribute that leads to a great distinction between the members of a population, including when considering their health and well-being, which are features to pursue within an aging society. The aim of this work was to produce demographic projections for the Portuguese population by sex, age group and level of educational attainment, for the period 2011–2031. Considering fertility, mortality and migration differentials by level of education, the population was projected using the multistate cohort-component method with a block Leslie matrix. Two scenarios were considered, one where educational attainment before 2011 remains constant and another in which educational attainment will follow the trend observed over the last decade, being the trend in the state proportion modelled using continuation ratio models. The results show an increase in the proportion of individuals who complete higher educational levels in almost all age groups of both sexes. Among women, only 13.6 % had completed some level of higher education in 2011, a figure that will rise to approximately 23.4 % in 2031, whereas among men this value was only 9.7 % and will also rise by 2031, reaching 15.5 %. We can expect the proportion of people with higher educational levels to continue to rise as the education of younger cohorts seems to evolve positively. This work will be particularly useful to study how the aging population and the rising levels of education can contribute to the planning and monitoring of public policies, although these findings can also be used in other research contexts.     

马克思主义"和谐"理念中的政治和谐追求

实现政治和谐是空想社会主义者向往的政治理想,他们著书立说,对政治和谐及其建立进行充分的论证,并设计方案、展开实验;马克思和恩格斯第一次把政治和谐提到理论高度,列宁则将社会主义政治和谐的建设付诸实践;毛泽东、邓小平、江泽民、胡锦涛在不同的历史阶段从不同的方面继承、丰富和发展了马克思主义的和谐观,探索着马克思主义中国化和中国特色社会主义的政治和谐之路。研究马克思主义＂和谐＂观及所蕴含的政治和谐思想对当今构建社会主义和谐社会具有重大的理论价值和实践意义。