Dose-Response and Risk Assessment of Airborne Hexavalent Chromium and Lung Cancer Mortality

This study evaluates the dose-response relationship for inhalation exposure to hexavalent chromium [Cr(VI)] and lung cancer mortality for workers of a chromate production facility, and provides estimates of the carcinogenic potency. The data were analyzed using relative risk and additive risk dose-response models implemented with both Poisson and Cox regression. Potential confounding by birth cohort and smoking prevalence were also assessed. Lifetime cumulative exposure and highest monthly exposure were the dose metrics evaluated. The estimated lifetime additional risk of lung cancer mortality associated with 45 years of occupational exposure to 1 microg/m3 Cr(VI) (occupational exposure unit risk) was 0.00205 (90%CI: 0.00134, 0.00291) for the relative risk model and 0.00216 (90%CI: 0.00143, 0.00302) for the additive risk model assuming a linear dose response for cumulative exposure with a five-year lag. Extrapolating these findings to a continuous (e.g., environmental) exposure scenario yielded an environmental unit risk of 0.00978 (90%CI: 0.00640, 0.0138) for the relative risk model [e.g., a cancer slope factor of 34 (mg/kg-day)-1] and 0.0125 (90%CI: 0.00833, 0.0175) for the additive risk model. The relative risk model is preferred because it is more consistent with the expected trend for lung cancer risk with age. Based on statistical tests for exposure-related trend, there was no statistically significant increased lung cancer risk below lifetime cumulative occupational exposures of 1.0 mg-yr/m3, and no excess risk for workers whose highest average monthly exposure did not exceed the current Permissible Exposure Limit (52 microg/m3). It is acknowledged that this study had limited power to detect increases at these low exposure levels. These cancer potency estimates are comparable to those developed by U.S. regulatory agencies and should be useful for assessing the potential cancer hazard associated with inhaled Cr(VI).     

Child‐Care Usage and Mother‐Infant “Quality Time”

Mothers' time‐use patterns were compared in families in which infants spent more than 30 hours per week in child care (In‐Care group; n= 143) versus 0 hours per week (At‐Home group; n= 183) from birth to 6 months of age. In‐Care group mothers spent about 12 fewer hours per week interacting with their infants, for about 32% less time; fathers of these infants were more involved in caregiving. The groups did not differ in the quality of mother‐infant interaction. In the In‐Care group, quantity of interaction was related to greater separation anxiety and concerns about effects of maternal employment. Time‐use data were not related to child outcomes at 15 months of age. Results suggest that the effect of extensive time spent apart on the quantity and quality of mother‐infant interaction may be smaller than anticipated.     

African American Children's Adjustment: The Roles of Maternal and Teacher Depressive Symptoms

This study examined the unique and interactive roles of mother and teacher depressive symptoms in child adjustment in 277 African American single mother‐headed families, as well as whether the associations differed depending on the age and gender of the child. Findings revealed a significant association between maternal depressive symptoms and child depressive symptoms in girls, but not boys. Moreover, the combination of higher levels of both mother and teacher depressive symptoms was associated with the highest level of child depressive symptoms and, for younger children, externalizing symptoms. The importance of considering the multiple social contexts in which children interact is discussed.     

Disabled by Design

This paper describes and analyses the author's attempts to engage in a user-led design/research process. This was undertaken during an MA in Design Research for Disability. The first section of the study delineates the background and context of the process of inquiry. This involves examination of the common features within design participation and emancipatory research. The second section of the study uses six principles of emancipatory research, defined by Emma Stone and Mark Priestley (1996), as a framework for analysis of the author's own process of inquiry.     

AN ALGORITHM FOR THE CONSTRUCTION OF OPTIMAL OR NEAR-OPTIMAL CHANGE-OVER DESIGNS

This paper presents an algorithm for the construction of optimal or near optimal change-over designs for arbitrary numbers of treatments, periods and units. Previous research on optimality has been either theoretical or has resulted in limited tabulations of small optimal designs. The algorithm consists of a number of steps:first find an optimal direct treatment effects design, ignoring residual effects, and then optimise this class of designs with respect to residual effects. Poor designs are avoided by judicious application of the (M, S)-optimality criterion, and modifications of it, to appropriate matrices. The performance of the algorithm is illustrated by examples.     

Increasing contraceptive use in Bangladesh: The role of demand and supply factors

This article analyzes the determinants of contraceptive use in Bangladesh, focusing on the roles of demand for additional children and of family planning service supply. Data from the Matlab Family Planning Health Services Project are used to examine the contributions of these factors to the difference in prevalence of modern contraceptive use between the project area and a control area served by the government family planning and health programs. Results of multivariate analysis deriving from the Easterlin synthesis framework show the importance of family planning supply factors in reducing psychic and resource costs of fertility regulation and in activating latent demand for contraception. Demand for birth limiting and for birth spacing emerge as important explanatory factors; demand for birth spacing is greater in the project area, and both demand measures exert a stronger effect on contraceptive behavior in that area.     

Communicating Global Activism

Many observers doubt the capacity of digital media to change the political game. The rise of a transnational activism that is aimed beyond states and directly at corporations, trade and development regimes offers a fruitful area for understanding how communication practices can help create a new politics. The Internet is implicated in the new global activism far beyond merely reducing the costs of communication, or transcending the geographical and temporal barriers associated with other communication media. Various uses of the Internet and digital media facilitate the loosely structured networks, the weak identity ties, and the patterns of issue and demonstration organizing that define a new global protest politics. Analysis of various cases shows how digital network configurations can facilitate: permanent campaigns; the growth of broad networks despite relatively weak social identity and ideology ties; transformation of individual member organizations and whole networks; and the capacity to communicate messages from desktops to television screens. The same qualities that make these communication-based politics durable also make them vulnerable to problems of control, decision-making and collective identity.     

‘I hereby come out’: What sort of speech act is coming out?

The process of coming out linguistically as a lesbian or as a gay man is occasionally referred to as a speech act (e.g. Harvey 1997: 72; Liang 1997: 293). This analogy is taken as a starting point to explore the extent to which coming out is a performative act, and what sort of speech act coming out may be. The discussion draws on the perspective of both the speaker and the hearer to consider how the acts involved in coming out are open to interpretation. Parallels are drawn between the act of coming out as a lesbian or a gay man and other instances of self–disclosure or of individuals' constructions of new facets of their identities.     

Complex belief-desire reasoning in children

Previous research concerned with children's belief-desire psychology has examined the capacity to predict or interpret action on the basis of the implicit proposition that ‘when an actor desires a particular end and believes that a particular action will achieve that end, he or she will undertake that action’. The limitations of this formulation for understanding acts of omission are outlined and an elaborated version of belief-desire psychology introduced. This version holds that ‘when an actor desires a particular end and believes that a particular action will achieve that end, and when it is believed that there are no co-occurring outcomes of that action whose avoidance is desired more highly than is the originally conceived end, then the actor will undertake the action which will satisfy the original desire’. An experiment is reported which examines 4-, 5, and 7-year-olds' ability to predict story characters' actions on the basis of either their true or false beliefs concerning undesirable outcomes associated with the pursuit of a desired end. Children of all age-groups provided evidence of understanding the elaborated version of belief-desire psychology. However, a significant improvement was noted between the ages of 4 and 7 years in the ability to understand circumstances involving false beliefs.