Showing papers by "Coventry University published in 1997"

Secondary ferrimagnetic minerals in Welsh soils: a comparison of mineral magnetic detection methods and implications for mineral formation

Abstract: SUMMARY A range of low-temperature and isothermal magnetic measurements are used to identify the secondary ferrimagnetic mineral (SFM) grain sizes in 10 representative soil samples from Wales. A comparison of percentage frequency-dependent susceptibility (χFD percentage) and low-temperature remanence measurements shows that they are sensitive to different ranges of superparamagnetic (SP) grains. The relative distributions of SP grains and stable single domain (SSD) grains are similar in nine of the samples. Typical distributions for soils dominated by SFMs are ˜˜20-30 per cent SSD and 70–80 per cent SP. Multidomain (MD) grains were not detected in the samples studied. There is evidence that some soils contain significant numbers of ultrafine SP grains <0.010 μm that are not detected by low-temperature remanence measurements at 20 K and which will have the effect of depressing values of low-field susceptibility (χLF) and χFD percentage. A mixing model suggests that χFD percentage may be used semi-quantitatively to estimate the proportion of SP grains in a sample. The positively skewed grain-size distributions strongly suggest a mechanism of SFM formation that is driven by processes at the < 10-8 m scale, thus supporting weathering and fermentation as controlling processes, rather than the degradation of SSD bacterial magnetosomes and primary minerals.

A preliminary attempt to identify atmospherically-derived pollution particles in English topsoils from magnetic susceptibility measurements

Abstract: This study identifies topsoils in England having increased magnetic susceptibility (xlf) values attributable to the presence of anthropogenically produced pollution particles, such as fly-ash. The database consists of 1176 topsoils taken at 10 km intervals across the whole of England, and tested for magnetic susceptibility at low and high frequencies. Soils containing significant concentrations of pollution particles were identified using two criteria; xlf (values > 0.38 10−6m3kg−1) and xfd% (values < 3%). The ‘polluted’ topsoils are located in the south-east around London, the Midlands, the north around the conurbations of Manchester, Merseyside and West Yorkshire, and in the north-east around Newcastle and Teeside. The heavy metal concentration of the soils are elevated above background levels, and have strong positive relationships with magnetic susceptibility and other magnetic parameters.

Instabilities in a plane channel flow between compliant walls

Abstract: The stability of plane channel flow between compliant walls is investigated for disturbances which have the same symmetry, with respect to the channel centreline, as the Tollmien–Schlichting mode of instability. The interconnected behaviour of flow-induced surface waves and Tollmien–Schlichting waves is examined both by direct numerical solution of the Orr–Sommerfeld equation and by means of an analytic shear layer theory. We show that when the compliant wall properties are selected so as to give a significant stability effect on Tollmien–Schlichting waves, the onset of divergence instability can be severely disrupted. In addition, travelling wave flutter can interact with the Tollmien–Schlichting mode to generate a powerful instability which replaces the flutter instability identified in studies based on a potential mean-flow model. The behaviour found when the mean-flow shear layer is fully accounted for may be traced to singularities in the wave dispersion relation. These singularities can be attributed to solutions which represent Tollmien–Schlichting waves in rigid-walled channels. Such singularities will also be found in the dispersion relation for the case of Blasius flow. Thus, similar behaviour can be anticipated for Blasius flow, including the disruption of the onset of divergence instability. As a consequence, it seems likely that previous investigations for Blasius flow will have yielded very conservative estimates for the optimal stabilization that can be achieved for Tollmien–Schlichting waves for the purposes of laminar-flow control.

Numerical simulation of the evolution of Tollmien–Schlichting waves over finite compliant panels

Abstract: The evolution of two-dimensional Tollmien–Schlichting waves propagating along a wall shear layer as it passes over a compliant panel of finite length is investigated by means of numerical simulation. It is shown that the interaction of such waves with the edges of the panel can lead to complex patterns of behaviour. The behaviour of the Tollmien–Schlichting waves in this situation, particularly the effect on their growth rate, is pertinent to the practical application of compliant walls for the delay of laminar–turbulent transition. If compliant panels could be made sufficiently short whilst retaining the capability to stabilize Tollmien–Schlichting waves, there is a good prospect that multiple-panel compliant walls could be used to maintain laminar flow at indefinitely high Reynolds numbers.We consider a model problem whereby a section of a plane channel is replaced with a compliant panel. A growing Tollmien–Schlichting wave is then introduced into the plane, rigid-walled, channel flow upstream of the compliant panel. The results obtained are very encouraging from the viewpoint of laminar-flow control. They indicate that compliant panels as short as a single Tollmien–Schlichting wavelength can have a strong stabilizing effect. In some cases the passage of the Tollmien–Schlichting wave over the panel edges leads to the excitation of stable flow-induced surface waves. The presence of these additional waves does not appear to be associated with any adverse effect on the stability of the Tollmien–Schlichting waves. Except very near the panel edges the panel response and flow perturbation can be represented by a superposition of the Tollmien–Schlichting wave and two other eigenmodes of the coupled Orr–Sommerfeld/compliant-wall eigensystem.The numerical scheme employed for the simulations is derived from a novel vorticity–velocity formulation of the linearized Navier–Stokes equations and uses a mixed finite-difference/spectral spatial discretization. This approach facilitated the development of a highly efficient solution procedure. Problems with numerical stability were overcome by combining the inertias of the compliant wall and fluid when imposing the boundary conditions. This allowed the interactively coupled fluid and wall motions to be computed without any prior restriction on the form taken by the disturbances.

Sedimentary indicators of lake-level changes in the humid temperate zone: a critical review

Abstract: Evidence for lake-level changes derived from stratigraphic sequences in cores from littoral zones is reviewed in the context of lake sedimentation processes. These are illustrated with published case-studies which have used multiple-core data. Possible approaches for choosing optimum sites are examined. Sedimentation controls which may change over time are also considered; these include, wind strength and frequency, wind exposure, water depth and underwater slopes, sediment type and littoral vegetation. A final section discusses how lake-level studies can be optimised so that results can be used with confidence in paleoclimatic and paleohydrological reconstructions. Sedimentary data showing shifts in littoral vegetation along shallow underwater gradients in sheltered margins, and transitions between sediment compositions linked to specific hydrological conditions give the strongest lines of evidence.

The prevalence of Cryptosporidium parvum and C. muris in Mus domesticus, Apodemus sylvaticus and Clethrionomys glareolus in an agricultural system

Abstract: Wild mice and voles were tested for Cryptosporidium during a 2-year survey at an agricultural site in Warwickshire, United Kingdom. C. parvum and C. muris, the two cryptosporidial species known to infect mammals, were detected. Prevalence figures of 22%, 21% and 13% noted for C. parvum for Mus domesticus, Apodemus sylvaticus and Clethrionomys glareolus, respectively, were higher than those recorded for C. muris at 10%, 6% and 2%. C. parvum causes the sometimes severe diarrhoeal disease cryptosporidiosis in many hosts, but the wild rodents were asymptomatic. The discovery of C. muris in A. sylvaticus and C. glareolus confirms a wider distribution in wild rodents than has previously been reported. Rodents may represent a significant reservoir of Cryptosporidium with a high potential for infection of man and livestock due to cohabitation.

Dunefield Activity and Interactions with Climatic Variability in the Southwest Kalahari Desert

Abstract: An analysis is undertaken of the temporal variability of climatic parameters that influence dunefield aeolian activity. Data from seven meteorological stations in the southwestern Kalahari Desert are used, spanning the period 1960–1992. Erosivity is considered through analysis of wind data, and erodibility through analysis of precipitation and potential evapotranspiration, which together influence dune surface plant growth. The data are integrated using Lancaster's ‘mobility’ index which provides a measure of potential dune surface sand transport. This is renamed ‘potential dune surface activity index’, to reflect the actual characteristic that is measured. The subsequent analysis indicates that dunefield activity is episodic and temporally variable, that both erosivity and erodibility vary through time, and that present levels of activity cannot be characterized by a single simple state. © 1997 by John Wiley & Sons, Ltd.

The use of caesium-137 measurements to establish a sediment budget for the Start catchment, Devon, UK

Abstract: Caesium-137 (137Cs) measurements have been used to investigate the delivery of sediment from the hillslopes to a lake which marks the downstream limit of the small agricultural Start basin in Devon, UK. Total 137Cs inventories and 137Cs depth distributions in sediment cores were used to estimate that the eroded sediment stored within the fields and on the flood plain of the main river was equivalent to sediment yields of ca. 21 and 30 t km−2 year1, respectively. Based on published information on sediment accumulation in the lake, the minerogenic sediment yield from the basin was estimated to be ca. 29 t km−2 year−1. The erosion rate on the hillslopes in the basin, calculated as the sum of the sediment yield to the lake and the two storage components, is ca. 80 t km−2 year−1. Of the soil eroded from the slopes more than 60% is stored at intermediate locations and the sediment delivery to the lake is less than 40%. The calculated soil erosion rate for the Start basin is consistent with an estimate ...

Red‐light districts and Toleration Zones: geographies of female street prostitution in England and Wales

Abstract: Summary Although female street prostitution is widely acknowledged to occur in specific spaces, characteristically referred to as ‘red-light’ districts, geographers have been remarkably reticent in examining the nature and location of these spaces. Against a backdrop of mounting debate surrounding the legal status of prostitution in England and Wales, this paper considers the importance of such areas in the regulation and containment of street prostitution, and speculates as to how changing social and legal attitudes might result in very different geographies of prostitution.

Poster presentations and peer assessment: novel forms of evaluation and assessment

Abstract: A comparison of student achievement in different assessment exercises shows that diversity of assessment strategies is needed to assess students fairly and avoid discrimination Final-year Biology and Environmental Science students presented posters describing major ecosystem processes for a named ecosystem of their choice. Peer assessment and staff assessment are compared. Marks for poster presentations are also compared with marks for essays in the same subject area. Student assessors overmarked each other's work but ranked the posters in the same order as staff assessors. Students who gained high marks in the poster presentation tended to do poorly in the essay and vice versa. This suggests that diversity of assessment strategies is needed in order to assess students fairly. By only using one form of assessment, we may be discriminating against some students.

Mineral magnetic properties of mixtures of environmental and synthetic materials: linear additivity and interaction effects

Abstract: SUMMARY Mineral magnetic properties have been used recently to classify and to attempt to quantify the sources of sediments through environmental systems. Linear modelling techniques could be used with a wide range of concentration-dependent magnetic measurements to quantify the sources of sediments. To investigate wider application of linear modelling techniques using mineral magnetic properties, research has been conducted using laboratory mixtures of up to six source materials, including both natural environmental materials and synthetic compounds. While six sources may seem ambitious, this figure was used as an absolute upper limit rather than giving a real prospect of mathematically unmixing six sources. It has been found that even with the most magnetically differentiable materials, large errors are encountered when modelling the sources of the mixtures. This paper investigates the causes of ‘non-additivity’ of certain magnetic measurements and the failure of the linear modelling of the sources of the mixtures. Possible reasons for this failure include source homogeneity, calibration and linearity of equipment, magnetic viscosity of materials and/or the changing physical characteristics of the source materials once mixed together (interaction effects). In testing linear additivity, low-frequency susceptibility is the most reliable mineral magnetic measurement, while remanence measurements suffer from a systematic error in the expected results. Results have shown that in the best controlled conditions where the sources are identified and are artificially mixed together, the results of linear modelling are quite poor and at best four sources can be ‘unmixed’ with reasonable success. It is suggested that interaction within the mixtures, especially when containing highly ferrimagnetic burnt environmental materials, causes some of the non-additivity phenomena.

Cryptosporidium parvum in environmental samples in the Sligo area, Republic of Ireland: a preliminary report.

Abstract: To detect Cryptosporidium in environmental specimens in the Republic of Ireland, grab samples of river water were prepared by calcium carbonate flocculation, and marine mussel tissue homogenated prior to testing with a fluorescently labelled monoclonal antibody and fluorescence microscopy. The parasite was detected in both river waters and marine mussels (Mytilus edulis). Filter feeders such as Mytilus edulis may be of value as biological monitors for the presence of cryptosporidial oocysts in sea water. The presence of Cryptosporidium in river and marine waters and, in particular, contaminating mussels used for human consumption, has obvious health implications.

Environmental Monitoring of Estuaries; Estimating and Mapping Various Environmental Indicators in Breydon Water Estuary, U.K., Using Landsat TM Imagery

Abstract: The spatial and temporal distribution of suspended solids, turbidity, temperature, salinity, chlorophyll aand total phosphorus were estimated and mapped with various degrees of success in Breydon Water Estuary using satellite (Landsat Thematic Mapper) imagery All the indicators exhibit a similar spatial pattern within the estuary High values are found at both the saltwater and freshwater ends of the estuary, and low values are found in the mixing zone The pattern is thought to be due to the influence of suspended solids and turbidity on the optical characteristics of water in this environment The distribution of suspended solids and turbidity are influenced by the flood–ebb intervals, the sedimentation processes and the internal topography of the estuary All of the predicted values are consistent with those reported in the literature

Holocene relative sea-level changes on the margin of a glacio-isostatically uplifted area: an example from northern Caithness, Scotland:

Abstract: Evidence is presented for Holocene relative sea-level changes on the margin of a glacio-isostatically uplifted area: the lower Wick River valley, northern Caithness, Scotland. Lithostratigraphic, b...

The impact of weather patterns on historic and contemporary catchment sediment yields

Abstract: Lake sediment-based estimates of sediment yield have frequently been used to reconstruct changing patterns of sediment supply arising from environmental change. Such analyses have often emphasized the importance of anthropogenic factors and, in particular, changing land use of management practices over timescales beyond the scope of direct process monitoring. This paper examines several U.K. sediment yield chronologies within the context of mesoscale atmospheric circulation patterns. Changes in the frequency of the winter cyclonic Lamb weather type since 1861 were found to account for a significant proportion of the variation in sediment yields. The results also have implications for future sediment accumulation rates given the potential geomorphological consequences of global climate change. © 1997 by John Wiley & Sons, Ltd.

Validity, reliability and responsiveness in the assessment of pain

Abstract: This paper examines some methodological issues in the assessment of pain, with particular reference to validity, reliability and responsiveness These issues are illustrated with reference to vario

The utility of 4-aminobenzoic acid in promotion of hydrogen bonding in crystallization processes: the structures of the cocrystals with halo and nitro subsituted aromatic compounds, and the crystal structures of the adducts with 4-nitroaniline (1:1), 4-(4-nitrobenzyl)pyridine (1:2), and (4-nitrophenyl)acetic acid (1:1)

Abstract: A number of molecular adducts of 4-aminobenzoic acid (4-ABA) have been prepared and characterized using infrared spectroscopy and in three cases by X-ray diffration methods. These three compounds are with 4-nitroaniline [(4-ABA) (C6H6N2O2)], 4-(4-nitrobenzyl) pyridine, [(4-ABA)2(C12H10N2O2)4], and (4-nitrophenyl)acetic acid, [(4-ABA) (C8H7NO4)]. Other compounds described are with 4-chlorobenzoic acid, [(4-ABA) (C7H5ClO2)], 4-bromobenzoic acid, [(4-ABA) (C7H5BrO2)], 4-cyanobenzoic acid, [(4-ABA) (C7H6N2)], 2-nitrobenzoic acid, [(4-ABA) (C7H5NO4)], and 3-nitrobenzoic acid, [(4-ABA) (C7H5NO4)]. All compounds have 1:1 stoichiometry except that with 4-(4-nitrobenzyl)pyridine (1:2) which is unique in being retro-stoichiometric. A review of the systematics of the 4-aminobenzoic acid adducts is also made, particularly with respect to the infrared characterization of the cocrystalline materials and prediction of their NLO potential.

Survival of Xenorhabdus nematophilus and Photorhabdus luminescens in water and soil

Abstract: Strains of Xenorhabdus nematophilus and Photorhabdus luminescenswere genetically marked with kanamycin resistance and the xylE gene to aid theirdetection in water and soil. Following release in river water, cells declined to undetectable levelsin 6 d. In sterile river water, this decline was enhanced with cells detectable for only 2 d. In sterileMilli-Q purified water, the decline was slower than in either sterile or non-sterile river water.Survival in soil was also restricted with cells only detectable for 7 d. These experiments indicatedthat both X. nematophilus and P. luminescens have limited survival orcompetitive abilities in these environments. The faster decline of populations in sterile river waterwas unexpected, and the possible formation of specialized survival stages was investigated. Insterile water, a non-culturable but viable population of cells was detected, indicating that cellsmay survive longer than anticipated in the environment and remain undetectable using standardmicrobiological methods. The implications of this work to the use of these strains in biologicalcontrol and the release of genetically-modified micro-organisms is discussed.

Improving arthritis self-management among older adults: ‘Just what the doctor didn't order’

Abstract: Objective. Community-based health interventions have been shown to be effective in promoting arthritis self-management amongst people in North America. The aim of this study was to determine the effectiveness of such programmes among older people in the UK. Design. The study was a multiple baseline, pre-test–post-test design of 62 older people (> 55 years of age) attending Arthritis Self-Management Programmes (ASMP) delivered in community settings. Method. Data were collected by self-administered questionnaires at two points in time: prior to the intervention and after the intervention, four months from baseline. Results. The sample comprised 94 per cent women, with a mean age of 69 and mean disease duration of 26 years. Most participants had either osteoarthritis or rheumatoid arthritis. Results showed that after four months, participants demonstrated significant increases in arthritis self-efficacy (p < .0005), positive affect (p = .042), cognitive symptom management (p < .0005), communication with doctors (p =< .0005), exercise (p < .0005) and relaxation (p < .0005). In addition, significant decreases were found in terms of pain (p = .026), depression (p = .042) and visits to GPs (p = .013). Conclusion. This first evaluation of the ASMP delivered in community settings suggests that this form of health intervention is not only acceptable to older people in the UK, but can offer considerable benefits in terms of arthritis self-efficacy, increased use of self-management strategies such as exercise, a reduction in pain and improved psychological well-being.

Patient education leaflets for people with rheumatoid arthritis: A controlled study

Abstract: Despite the wide availability of disease-related leaflets, their impact on patients' wellbeing has rarely been evaluated. The purpose of this randomized, controlled study was to examine the effectiveness of leaflets amongst patients with rheumatoid arthritis (RA) in terms of change in knowledge, self-efficacy and psychological well-being. Patients were recruited and randomized to the intervention (N = 53), or control condition (N = 55), as they attended out-patient clinics. Data were collected by self-administered questionnaires at two points in time, 3 weeks apart. Following baseline assessment, the intervention group received a leaflet and were interviewed at the end of the study. After 3 weeks, the intervention group demonstrated an increase in knowledge (F = 21.24, p< 0.0001), a decrease in pain (F = 6.45, p = 0.013), and a decrease in depression (F = 3.64, p = 0.059). No changes were evident among the control group. Analysis of interview data revealed that patients found the leaflet reassuri...

Empirical study of the interdependencies of genetic algorithm parameters

Abstract: Although it is recognised that the performance of evolutionary systems such as genetic algorithms (GAs) is affected by the parameters that are employed to implement them, there is hardly any work known to us that has shed much light on the interdependencies and interactions between these parameters. Most studies on the effects of these parameters on the performance of GA-based systems have focused on a parameter at a time without considering the effect of other parameters on that parameter and vice versa. Consequently there is hardly any theory about the interactions and interdependencies of these parameters. This paper contributes towards correcting the situation mentioned above by examining empirically the relationship between two parameters of genetic algorithms (GAs): population size and replacement methods in the performance of GA-based systems. Results are presented that appear to show a link between replacement strategy and an appropriate population size when applying genetic algorithms to a particular problem. It is suggested that, in the domain of application considered in this paper one can infer that the more individuals that are replaced during reproduction the larger the population size that is needed for all optimum performance of GA-based systems. It is suggested that directing our efforts towards establishing the interdependencies and interactions between parameters of evolutionary systems will enhance the advancement of this new technology.

Middle Pleistocene deposits at Frog Hall Pit, Stretton‐on‐Dunsmore, Warwickshire, English Midlands, and their implications for the age of the type Wolstonian

Abstract: Organic sediment from Frog Hall Pit, near Coventry, has produced pollen, plant macrofossil, insect, ostracod and molluscan data indicative of the early part of a temperate episode in the Middle Pleistocene. The regional stratigraphy and clast lithological characteristics of the gravels underlying the temperate deposits show that the whole sequence at the site post-dates the major glaciation (the Wolstonian sensu Mitchell et al., 1973) of the Midlands. Amino-acid D/L ratios from molluscan shells give mean values of 0.24, which is consistent with an age in Oxygen Isotope Stage 9 and comparable with those from the Hoxnian Interglacial of East Anglia. This age-estimate for the Frog Hall organic deposit places a minimum age on the Wolstonian Glaciation of the Midlands in Oxygen Isotope Stage 10, and therefore close in time to the Anglian (Oxygen Isotope Stage 12) Cold Stage. © 1997 John Wiley & Sons, Ltd.

Some performance characteristics of a multi-axis touch trigger probe

Abstract: This paper examines the errors of a TP2-5W touch trigger probe using measurements performed with a three-axis co-ordinate measuring machine (CMM). Of the `user-selected properties' which can affect the accuracy of measurements, those examined are the direction of approach, the stylus length and diameter, the measuring speed, the approach distance, the location of the workpiece, the orientation of the workpiece and the mounting of the stylus stem.

The use of mineral magnetic measurements in polluted urban lakes and deposited dusts, Coventry, U.K.

Abstract: This paper presents findings from two linked studies which examine the relationship between heavy metals and mineral magnetic characteristics of sediments in a polluted urban lake and deposited dusts in Coventry, UK. The first study found no relationship between the two sets of properties in the urban lake sediments. The second shows that there is a relationship in