Use of an in situ artificial substrate for biological accumulation and monitoring of aqueous trace metals a preliminary field investigation

A preliminary field study was undertaken to investigate the use of attached periphyton on an artificial substrate as a water column composite sampler for trace metals. Spatial and temporal trends are presented of trace metal biological accumulation terms of the substrate placement in the vicinity of a synthetic fiber chemical manufacturing plant. Seasonal distribution and biological accumulation of antimony, chromium, copper, mercury and zinc is discussed. Statistical analysis of metal accumulated as a function of substrate placement, showed significantly higher levels of chromium for the discharge station compared to the reference stations. In contrast sediment analysis of the discharge station showed only slightly higher levels of zinc and no significant chromium accumulation when compared to a upriver reference station.     

Model-Based Verification of a Security Protocol for Conditional Access to Services

We use the formal language LOTOS to specify and verify the robustness of the Equicrypt protocol under design in the European OKAPI project for conditional access to multimedia services. We state some desired security properties and formalize them. We describe a generic intruder process and its modelling, and show that some properties are falsified in the presence of this intruder. The diagnostic sequences can be used almost directly to exhibit the scenarios of possible attacks on the protocol. Finally, we propose an improvement of the protocol which satisfies our properties.