Rapid bacterial detection and viability measurements have been greatly enhanced by recent advances in the use of fluorescent stains in cytometry. It has previously been shown that four physiological states can be distinguished : reproductively viable, metabolically active, intact and permeabilized. Previous sorting experiments have shown that not all intact cells readily grow, but some intact cells can grow even when they fail to show metabolic activity, as determined by esterase turnover. To circumvent the limitations imposed by active dye extrusion or cell dormancy on viability measurements used to date (e.g. enzyme activity or cell polarization), a fast triple fluorochrome staining procedure has been developed that takes account of these problems. This allows further cellular characterization of intact cells by : active exclusion of ethidium bromide (EB) (metabolically active cells), uptake of EB but exclusion of bis‐oxonol (BOX) (de‐energized but with a polarized cell membrane) and uptake of both dyes (depolarized). Permeabilized cells were identified by propidium iodide (PI) uptake. The method was validated using an electronically programmable single cell sorter (EPICS Elite®) and aged Salmonella typhimurium cells. Reproductive viability was determined by sorting single cells to their staining pattern directly onto agar plates. Most polarized cells could be recovered as well as a significant fraction of the depolarized cells, demonstrating that depolarization is a sensitive measure of cell damage but a poor indicator of cell death.

A new geological map and a partly revised lithostratigraphy are presented for the Kilbride Peninsula and the area immediately to the north in County Mayo in the west of Ireland. Volcanic arc rocks of the Lough Nafooey Group are unconformably overlain by late Floian mudrocks that were deposited after the cessation of volcanic activity and which did not receive any detritus from the Lough Nafooey arc. The unconformably overlying Darriwillian Rosroe Formation is similar in character to areas immediately to the west and north-east and shows a coarsening upward pattern. A south dipping Silurian succession everywhere masks the contact between the Lough Nafooey Group and the metamorphic rocks of Connemara. The Silurian succession shows progressive deepening from terrestrial sediments at the base to deep-water turbidites in the youngest strata seen. There are also important provenance changes throughout the Silurian succession. A widespread alkaline lava near the base is the only thick volcanic horizon seen in the succession. The structural geometry suggests that two large fault features (the Doon Rock and Clonbur faults) acted as a linked system during sedimentation and may have produced a point source for a clastic sediment fan of latest Ordovician or early Silurian age. This feature, termed the Derryveeny fan, contains coarse-grained metamorphic detritus from erosion of Connemara further to the south. A marked strike swing of the Silurian strata is attributed to post-Wenlock SSE directed contraction with reverse reactivation of the Derry Bay and Lettereeneen faults and associated deformation of their respective footwalls.

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