An investigation of thresholds in air pollution-mortality effects

In this paper we introduce and implement new techniques to investigate threshold effects in air pollution-mortality relationships. Our key interest is in measuring the dose-response relationship above and below a given threshold level where we allow for a large number of potential explanatory variables to trigger the threshold effect. This is in contrast to existing approaches that usually focus on a single threshold trigger. We allow for a myriad of threshold effects within a Bayesian statistical framework that accounts for model uncertainty (i.e. uncertainty about which threshold trigger and explanatory variables are appropriate). We apply these techniques in an empirical exercise using daily data from Toronto for 1992-1997. We investigate the existence and nature of threshold effects in the relationship between mortality and ozone (O3), total particulate matter (PM) and an index of other conventionally occurring air pollutants. In general, we find the effects of the pollutants we consider on mortality to be statistically indistinguishable from zero with no evidence of thresholds. The one exception is ozone, for which results present an ambiguous picture. Ozone has no significant effect on mortality when we exclude threshold effects from the analysis. Allowing for thresholds we find a positive and significant effect for this pollutant when the threshold trigger is the average change in ozone two days ago. However, this significant effect is not observed after controlling for PM

A better proof of the Goldman-Parker conjecture

The Goldman-Parker Conjecture classifies the complex hyperbolic C-reflection ideal triangle groups up to discreteness. We proved the Goldman-Parker Conjecture in [Ann. of Math. 153 (2001) 533--598] using a rigorous computer-assisted proof. In this paper we give a new and improved proof of the Goldman-Parker Conjecture. While the proof relies on the computer for extensive guidance, the proof itself is traditional.Comment: Published by Geometry and Topology at http://www.maths.warwick.ac.uk/gt/GTVol9/paper35.abs.htm

Modular circle quotients and PL limit sets

We say that a collection Gamma of geodesics in the hyperbolic plane H^2 is a modular pattern if Gamma is invariant under the modular group PSL_2(Z), if there are only finitely many PSL_2(Z)-equivalence classes of geodesics in Gamma, and if each geodesic in Gamma is stabilized by an infinite order subgroup of PSL_2(Z). For instance, any finite union of closed geodesics on the modular orbifold H^2/PSL_2(Z) lifts to a modular pattern. Let S^1 be the ideal boundary of H^2. Given two points p,q in S^1 we write pq if p and q are the endpoints of a geodesic in Gamma. (In particular pp.) We show that is an equivalence relation. We let Q_Gamma=S^1/ be the quotient space. We call Q_Gamma a modular circle quotient. In this paper we will give a sense of what modular circle quotients `look like' by realizing them as limit sets of piecewise-linear group actionsComment: Published by Geometry and Topology at http://www.maths.warwick.ac.uk/gt/GTVol8/paper1.abs.htm

Values Following a Major Terrorist Incident: Finnish Adolescent and Student Values Before and After September 11, 2001

The horrific terrorist attacks on the United States on September 11, 2001, left an indelible mark on perceptions of security and threat across the world. This paper uses Schwartz’s (1992) value circumplex model to examine value change across matched high school and university student samples in Finland, questioned before and after the World Trade Center (WTC) and associated attacks. In Study 1 (N5419), security values of adolescents were higher the day following the WTC attacks than before, but fell back toward pre-attack levels in the subsequent two samples. In contrast, levels of stimulation were lower following the terrorist incidents. In Study 2 (N5222), security levels of students were also higher following the WTC attacks, but again were closer to pre-attack levels in a subsequent cohort

Eleutherodactylus glandulifer

Number of Pages: 1Integrative BiologyGeological Science

Eleutherodactylus abbotti

Number of Pages: 2Integrative BiologyGeological Science