Projected implications of climate change for road safety in Greater Vancouver, Canada

The elevated risk of collision while driving during precipitation has been well documented by the road safety community, with heavy rainfall events of particular concern. As the climate warms in the coming century, altered precipitation patterns are likely. The current study builds on the extensive literature on weather-related driving risks and draws on the climate change impact literature in order to explore the implications of climate change for road safety. It presents both an approach for conducting such analyses, as well as empirical estimates of the direction and magnitude of change in road safety for the highly urbanized Greater Vancouver metropolitan region on Canada’s west coast. The signal that emerges from the analysis is that projections of greater rainfall frequency are expected to translate into higher collision counts by the mid 2050s. The greatest adverse safety impact is likely to be concentrated on moderate to heavy rainfall days (≥ 10 mm), which are associated with more highly elevated risks today. This suggests that particular attention should be paid to future changes in the frequency and intensity of extreme rainfall events.     

Use of a sensitive analytical method and the silt-clay (< 53 μm) fraction of stream sediments in exploration for gold in northern Thailand

Heavy mineral concentrates (SG 3.3) from the Huai Hin Laep, a tributary of the Huai Kho Lo River in northern Thailand, contain strongly anomalous concentrations of gold. In contrast, the gold content of the associated < 149 μm and <53 μm fractions of the sediment is generally less than the 5 ppb detection limit obtained by a conventional fire assay-atomic absorption spectrometry method. To test for the presence of a gold anomaly at concentrations < 5 ppb, we have used an aqua-regia digestion followed by an Amberlite XAD-8 column preconcentration technique that, when used with a spectrometer that enables full display of the analytical spectrum to optimize baseline analysis, gives a detection limit of 0.1 ppb Au.Gold content of the < 53 μm sediment fraction ranges from 1.0 to 3.1 ppb compared to concentrations that typically range from 1000 to more than 100,000 ppb in the heavy mineral concentrates. However, despite gold concentrations in the sediment being several orders of magnitude lower than those in the heavy mineral concentrates, the downstream dispersion patterns are similar, with gold concentrations increasing at high energy sites and downstream away from the assumed source. These results identify the presence of a greatly diluted gold anomaly in the < 53 μm fraction of the sediments and suggest that transport and deposition of this fine grained gold is controlled by the same sedimentological factors that control the behavior of gold in the sand-size range, between 53 μm and 425 μm. Most important from an exploration standpoint, is that by using a sufficiently sensitive analytical method, meaningful gold dispersion patterns can be recognized at concentrations below 5 ppb.     

AsteroFLAG: First results from hare‐and‐hounds Exercise #1

We report on initial results from the first phase of Exercise #1 of the asteroFLAG hare and hounds. The asteroFLAG group is helping to prepare for the asteroseismology component of NASA's Kepler mission, and the first phase of Exercise #1 is concerned with testing extraction of estimates of the large and small frequency spacings of the low‐degree p modes from Kepler‐like artificial data. These seismic frequency spacings will provide key input for complementing the exoplanet search data. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)