An experimental study of how hydraulic transients cause mobilisation of material within drinking water distribution systems.

This paper provides new insight into how the hydraulic transients that occur within drinking water distribution networks can mobilise material adhered to the pipe wall and hence cause unacceptable water quality and customer dissatisfaction. Results are reported from extensive, representative, physical experiments covering a wide range of repeatable rapidly accelerating and decelerating hydraulic conditions. Novel time synchronous analysis shows that mobilisation always occurs in the first dynamic surge of the transient; however, differences in the physical processes that govern mobilisation were observed between the two groups of transient type studied. A function to estimate the mobilising force is proposed and applied to the physical experiments performed. The research provides important insights for identifying and understanding the mechanisms and forces induced during transients, vital for ensuring the supply of safe drinking water in operational distribution systems.

Biodiversity effects on yield and unsown species invasion in a temperate forage ecosystem.

BACKGROUND AND AIMS: Current agricultural practices are based on growing monocultures or binary mixtures over large areas, with a resultant impoverishing effect on biodiversity at several trophic levels. The effects of increasing the biodiversity of a sward mixture on dry matter yield and unsown species invasion were studied. METHODS: A field experiment involving four grassland species [two grasses--perennial ryegrass (Lolium perenne) and cocksfoot (Dactylis glomerata)--and two legumes--red clover (Trifolium pratense) and white clover (Trifolium repens)], grown in monocultures and mixtures in accordance with a simplex design, was carried out. The legumes were included either as single varieties or as one of two broad genetic-base composites. The experiment was harvested three times a year over three years; dry matter yield and yield of unsown species were determined at each harvest. Yields of individual species and interactions between all species present were estimated through a statistical modelling approach. KEY RESULTS: Species diversity produced a strong positive yield effect that resulted in transgressive over-yielding in the second and third years. Using broad genetic-base composites of the legumes had a small impact on yield and species interactions. Invasion by unsown species was strongly reduced by species diversity, but species identity was also important. Cocksfoot and white clover (with the exception of one broad genetic-base composite) reduced invasion, while red clover was the most invaded species. CONCLUSIONS: The results show that it is possible to increase, and stabilize, the yield of a grassland crop and reduce invasion by unsown species by increasing its species diversity.

The association of E. coli and soil particles in overland flow.

The removal of E. coli from overland flow under saturation-excess runoff conditions was investigated in experimental field plots that were 1 m wide and 5 m long. Variation in the attenuation of bacteria and distance transported was quantified under contrasting flow conditions. In addition, the impact of soil tillage upon microbial attenuation was examined by comparing results derived from grassed plots (intact) with those subject to tillage with the soil left bare (cultivated). For intact plots subjected to a flow of 2 L/min, 27% of the E. coli in the flow was removed after 5 m with removal following a logarithmic function with respect to distance. For the higher flow rates of 6 L/min and 20 L/min, no attenuation trend was observed over this distance. E. coli removal during flow across the cultivated plots was significantly greater compared to the intact plots. This was attributed to a greater infiltration rate in the cultivated plots (due to the tillage) which promoted a greater volume of flow to pass through the soil matrix, providing the opportunity for filtration and adsorption of microbes. Logarithmic trends with respect to distance were observed for all flow rates tested on the cultivated plots (2, 6 and 20 L/min). Total removal after 5 m at a flow rate of 2 L/min was 41% and again removal efficiency decreased as the flow rate increased. Analysis of the transported state of the E. coli revealed that the bacteria were being transported predominantly in particles less than 20 microm in diameter and were not attached to large (dense) soil particles. The limited removal (< 50%) of bacteria from overland flow under saturation-excess runoff conditions in these experiments appeared, therefore, to be primarily due to a lack of settling or deposition. Instead, most bacteria remained entrained within the overland flow down the length of the plots.

Development of a process for the production of the anticancer lead compound pleurotin by fermentation of Hohenbuehelia atrocaerulea.

Pleurotin is a naphthoquinone antibiotic originally isolated from Pleurotus griseus. Two pleurotin producing strains of Hohenbuehelia atrocaerulea have been identified, which, on solid substrate fermentation for 2 months yield 1-2 mg/l of the antibiotic. Described here is the lengthy developmental process which resulted in a production protocol being developed which reliably yields pleurotin from liquid fermentation at >300 mg/l. Critical to obtaining this increase in titer was inclusion in the media of an aqueous extract of alder wood.

Numbers and transported state of Escherichia coli in runoff direct from fresh cowpats under simulated rainfall.

AIMS: To investigate the number of Escherichia coli in runoff derived directly from fresh cowpats and to determine if the E. coli are attached to dense particles, in flocs or as individual cells. METHODS AND RESULTS: Three cowpats were collected monthly from the same farm for 13 months and the number of E. coli in them estimated. A rainfall simulator was used to generate runoff from the individual cowpats, which was fractioned to determine the transported state of any E. coli present. The number of E. coli in the cowpat runoff was highly variable and was strongly correlated with the number of E. coli in the cowpat. Only a small percentage (approx. 8%) of the E. coli in runoff were attached to dense (>1.3 g ml(-1)) particles and there was no evidence of flocculation of the cells. CONCLUSIONS: Escherichia coli in runoff from cowpats are transported predominantly as individual cells. SIGNIFICANCE AND IMPACT OF THE STUDY: Mitigation strategies to reduce the number of faecal bacteria in overland flow from agricultural land need to be designed to trap single bacterial cells.

Morphological compatibility of white clover and perennial ryegrass cultivars grown under two nitrate levels in flowing solution culture.

The effects of nitrate (NO3-) supply on shoot morphology, vertical distribution of shoot and root biomass and total nitrogen (N) acquisition by two perennial ryegrass (Lolium perenne L.) cultivars (AberElan and Preference) and two white clover (Trifolium repens L.) cultivars (Grasslands Huia and AberHerald) were studied in flowing nutrient culture. Cultivars were grown from seed as monocultures and the clovers inoculated with Rhizobium. The 6-week measurement period began on day 34 (grasses) and day 56 (clovers) when the NO3- supply was adjusted to either 2 mmol m-3 (low nitrogen, LN) or 50 mmol m-3 (high nitrogen, HN). These treatments were subsequently maintained automatically. Plants were harvested at intervals to measure their morphology and N content. Cultivars of both species differed significantly in several aspects of their response to NO3- supply. In the grasses, the LN treatment increased the root : shoot ratio of AberElan but did not affect the distribution of root length in the root profile. In contrast, this treatment changed the root distribution of Preference compared with HN, resulting in a larger proportion of root length being distributed further down the root profile. The morphology of white clover Grasslands Huia was for the most part unaffected by the level of NO3- supply. In contrast, AberHerald exhibited different growth strategies, with LN plants increasing their stolon weight per unit length at the expense of leaf production, leaf area and stolon length, whereas HN plants showed reduced stolon thickness, greater leaf area production and stolon length per plant. Cultivars with different morphological/physiological strategies in response to NO3- supply may be of value in the construction of 'compatible mixtures' aimed at reducing oscillations in sward clover content by extending the range of conditions that allow balanced coexistence of species to occur.

Predicting the effect of atmospheric pollution on soil and surface water acidification in the Middle Hills of Nepal.

Rapid population growth and the expansion of South East Asian economies have lead to recent concerns regarding the effects of anthropogenic pollution on the environment. The RAINS-ASIA source-receptor, atmospheric transport model, is used to produce scenarios of future anthropogenic sulphur deposition. This is used as an input to the MAGIC model for prediction of future changes in the hydrochemistry of two catchments of the Likhu Khola watershed in the Middle Hills region of Nepal. Since much of this region is under intense cultivation and the application of mineral fertilisers may be contributing to soil and surface water acidification and loss of soil fertility, a best- and worse-case scenario for fertiliser application are incorporated to assess the overall anthropogenic influence upon soil and surface water acidification. The results indicate a decrease of soil base saturation and streamwater ANC, especially under the worst-case scenario of increased acidic deposition and increased fertiliser use. However, the pH status of soils and surface water are predicted to decrease only marginally as a result of the abundant supply of base cations from the highly weathered bedrock and deep soil. The problem of increased acidification of soils and water at a regional scale, however, should be addressed.

Appraisal, coping, and social support as mediators of well-being in black and white family caregivers of patients with Alzheimer's disease.

Family caregivers of patients with Alzheimer's disease (AD) commonly have high levels of psychological distress. Black caregivers often report less depression than White caregivers, but the process underlying this difference is poorly understood. With the use of a stress process model, 123 White and 74 Black family caregivers of patients with AD and other progressive dementias were studied. Black caregivers appraised patient problems as less stressful and reported higher self-efficacy in managing caregiving problems and less depression than did White caregivers. White and Black caregivers also differed significantly in coping responses but not in social supports. Structural equation analyses indicated that the correlational structure of the stress process was similar in White and Black caregivers. Caregiving stressors and race did not affect well-being through direct paths, but they were mediated by effects for appraisal, social support and activity, and coping. Possible cultural mechanisms explaining the better adjustment among Black caregivers are discussed.

Individual patterns of immediate skin reactivity to mold extracts.

One hundred atopic patients were skin tested intradermally over a 2-year period with 30 different mold extracts. Subjects were monitored for immediate reactions. Data suggest that to evaluate mold sensitivity in atopic patients one must use multiple mold extracts.

Involvement of the outer wall layer of Cladosporium cladosporioides in an IgG-mediated hypersensitivity.

The serum of an individual hypersensitive to the fungus Cladosporium cladosporioides reacted with the outer wall layer of germinating spores, immature hyphae, and, to a lesser extent, mature mycelium, as detected by the indirect immunofluorescence assay when goat anti-human IgG, but not goat anti-human IgE, was employed. The outer wall layer of ungerminated spores, however, did not react with the patient's serum and the anti-human IgG probe. When ungerminated spores were vortexed in physiological saline for 1 min, approximately 8 pg of protein/spore was released; this rapid release of protein may have been the cause of the loss of antigenic activity from the outer wall layer of ungerminated spores during the immunoassay process. Immunoblotting revealed the presence of a high molecular weight antigen in all the extracts of the fungus at various stages of the life cycle, including ungerminated and germinating spores, hyphae in the logarithmic phase, mature mycelium, and a culture filtrate of C. cladosporioides.

The significance of the spores of the Basidiomycetes (mushrooms and their allies) in bronchial asthma and allergic rhinitis.

The role of Basidiospores in the allergic diathesis is poorly understood. Dialyzed extracts of Agaricus campestris, Coprinus micaceus, Fuligo septica, Lycoperdon perlatum, Scleroderma lycoperdoides, Ustilago maydis, and sooty mold were prepared from fresh spores. The study group consisted of 100 patients with asthma and 100 patients with allergic rhinitis. These 200 patients had symptoms occurring during October and November. All were intradermally skin tested with the seven extracts at concentrations of 1 microgram/mL or 10 micrograms/mL. No scratch or pressure puncture tests were performed. Skin tests were recorded at 15 minutes (pos = 5-mm wheal with 10-mm erythema or greater) and at six or 24 hours (pos = 6 mm or greater of induration and erythema). A total of 436 immediate reactions were observed in the asthmatic group (4.4/patient) compared with 129 in the rhinitic group (1.3/patient). The late phase reactions were just the opposite. The asthmatic group had 66 late phase reactions or 0.7/patient compared with 382 or 3.8/patient in the rhinitic group. This study demonstrates that patients with bronchial asthma have a higher incidence of immediate skin sensitivity by intradermal testing, whereas patients with allergic rhinitis have late phase sensitivity to these fungal spores. This study was performed in the eastern United States only; therefore, the clinical significance of the results will become more apparent once this study is repeated in other parts of the country by other investigators.