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Biomedical subjects

P R Holmes

Publications and source records attributed to P R Holmes.

11 recordsLinked to original sources

On risky ground: the water professional in politics.

Best practice in drainage basin management requires consultation and stakeholder engagement in the formulation and implementation of plans. The water management professional, engaging with the political world, is on risky ground, thanks to many stakeholders' accidental or chosen unwillingness to accept science-based advice. Technical specialists produce good advice, yet progress is inhibited because they do not connect effectively with politicians, administrators and managers. A series of short case studies from three countries in different but related fields provides evidence of the problems that are encountered. Professionals may be cut off from the political world within comfort zones defined by the cultural norms and behaviours of bureaucracy, their profession or their preferred communications style. The consequence of the professionals' lack of engagement in the political world can be that scarce money and effort is wasted on low priority issues, and the case for sound, sustainable environmental management is discredited. Stakeholder support is worth winning, because it can bring positive benefits in the effectiveness of environmental management programmes. Where outside help is needed to bring about this result, it should be provided by advisers who are sensitive to the culture, at the national, professional and organizational level, of the recipients.

Communication↗

Mechanism of pyrite dissolution in the presence of Thiobacillus ferrooxidans.

In spite of the environmental and commercial interests in the bacterial leaching of pyrite, two central questions have not been answered after more than 35 years of research: does Thiobacillus ferrooxidans enhance the rate of leaching above that achieved by ferric sulfate solutions under the same conditions, and if so, how do the bacteria affect such an enhancement? Experimental conditions of previous studies were such that the concentrations of ferric and ferrous ions changed substantially throughout the course of the experiments. This has made it difficult to interpret the data obtained from these previous works. The aim of this work was to answer these two questions by employing an experimental apparatus designed to maintain the concentrations in solution at a constant value. This was achieved by using the constant redox potential apparatus described previously (P. I. Harvey, and F. K. Crundwell, Appl. Environ. Microbiol. 63:2586-2592, 1997; T. A. Fowler, and F. K. Crundwell, Appl. Environ. Microbiol. 64:3570-3575, 1998). Experiments were conducted in both the presence and absence of T. ferrooxidans, maintaining the same conditions in solution. The rate of dissolution of pyrite with bacteria was higher than that without bacteria at the same concentrations of ferrous and ferric ions in solution. Analysis of the dependence of the rate of leaching on the concentration of ferric ions and on the pH, together with results obtained from electrochemical measurements, provided clear evidence that the higher rate of leaching with bacteria is due to the bacteria increasing the pH at the surface of the pyrite.

Electrochemistry↗

Light and suction trap catches of Culicoides midges in southern England.

1. The seasonal flight periods are given for eleven species or species groups of Culicoides midges at Pirbright, Surrey, U.K., from 1979 to 1981 and in 1983. 2. Most species were relatively uniformly distributed both within the study site and between years; only C.clintoni Boorman was limited in its spatial distribution and only C.segnis Campbell and Pelham-Clinton varied greatly in numbers between years. 3. Species fall into one of three patterns of seasonal abundance: spring emergers, summer emergers, or spring to autumn emergers. 4. Only the C.obsoletus group showed a pattern of emergence that could correspond to distinct generations, of one or more species in the group. Three distinct emergences were observed, and possible explanations for these discussed. 5. For all species except C.impunctatus Goetghebuer the catches from suction/light and suction only traps are poorly correlated whereas for C.impunctatus they are highly correlated. This may suggest that this species is not greatly attracted to light.

Animals↗

A study of population changes in adult Culex quinquefasciatus Say (Diptera: Culicidae) during a mosquito control programme in Dubai, United Arab Emirates.

The effectiveness of insecticidal control measures on adult Culex quinquefasciatus Say in Dubai, United Arab Emirates, was examined. Direct treatment of the study site with cypermethrin applied as a fog caused a temporary reduction both in total numbers (males and females) and in the proportion of older females. When cypermethrin was applied as an ultra low volume formulation at dusk and dawn numbers of males were greatly reduced, but numbers of females were not affected. It appears that the adulticiding operations had little overall effect on the total numbers or survival rate of females, or breeding success. The oviposition cycle duration was estimated to be two days, with the survival rate per oviposition cycle calculated as 30%. With these values it is thought unlikely that filariasis would be transmitted in Dubai.

Animals↗

The establishment of a laboratory colony of Ixodes holocyclus.

A laboratory colony capable of producing annually 3000 female Ixodes holocyclus was maintained for 3 years. Guinea-pigs were used for larval feeding and bandicoots for nymphs and adults. The methods and equipment employed are described in detail.

Animals↗