Open Access. Powered by Scholars. Published by Universities.®

Digital Commons Network™

Open Access. Powered by Scholars. Published by Universities.®

University of Plymouth

Discipline
Keyword
Publication Year
Publication
Publication Type
File Type

Articles 6451 - 6480 of 6786

Full-Text Articles in Entire DC Network

Evolutionary Decomposition Of Complex Design Spaces, Christopher Richard Bonham Jan 2000

Evolutionary Decomposition Of Complex Design Spaces, Christopher Richard Bonham

School of Engineering, Computing and Mathematics Theses

This dissertation investigates the support of conceptual engineering design through the decomposition of multi-dimensional search spaces into regions of high performance. Such decomposition helps the designer identify optimal design directions by the elimination of infeasible or undesirable regions within the search space. Moreover, high levels of interaction between the designer and the model increases overall domain knowledge and significantly reduces uncertainty relating to the design task at hand. The aim of the research is to develop the archetypal Cluster Oriented Genetic Algorithm (COGA) which achieves search space decomposition by using variable mutation (vmCOGA) to promote diverse search and an Adaptive …

Go to article

Exploring And Exploiting Models Of The Fitness Landscape: A Case Against Evolutionary Optimization, Jonathan Paul Moore Jan 2000

Exploring And Exploiting Models Of The Fitness Landscape: A Case Against Evolutionary Optimization, Jonathan Paul Moore

School of Engineering, Computing and Mathematics Theses

In recent years, the theories of natural selection and biological evolution have proved popular metaphors for understanding and solving optimization problems in engineering design. This thesis identifies some fundamental problems associated with this use of such metaphors. Key objections are the failure of evolutionary optimization techniques to represent explicitly the goal of the optimization process, and poor use of knowledge developed during the process. It is also suggested that convergent behaviour of an optimization algorithm is an undesirable quality if the algorithm is to be applied to multimodal problems. An alternative approach to optimization is suggested, based on the explicit …

Go to article

Scallop Dredging Has Profound, Long-Term Impacts On Maerl Habitats, J. M. Hall-Spencer, P. G. Moore Jan 2000

Scallop Dredging Has Profound, Long-Term Impacts On Maerl Habitats, J. M. Hall-Spencer, P. G. Moore

School of Biological and Marine Sciences

No abstract provided.

Go to article

Limaria Hians (Mollusca: Limacea): A Neglected Reef-Forming Keystone Species, J. M. Hall-Spencer, P. G. Moore Jan 2000

Limaria Hians (Mollusca: Limacea): A Neglected Reef-Forming Keystone Species, J. M. Hall-Spencer, P. G. Moore

School of Biological and Marine Sciences

1. The case is made for recognition of the marine bivalve Limaria hians as a reef-forming species, which plays a key architectural role in certain benthic communities around the United Kingdom and Ireland. 2. This species uses byssal threads to construct nests that can coalesce to form reefs that cover hectares of seabed, contain multiple conspecifies and bind sediment. In so doing, L. hians modifies physical, chemical and biological processes at the sediment-water interface. 3. Such nests support a high diversity of associated organisms in coarse-grade sediments (19 species of algae and 265 species of invertebrates from six discrete nests …

Go to article

Transport Of Fine Sediment With Mesoscale Currents In The Shelf-Slope Zone Of The Sea, Gi Shapiro, Tm Akivis, Nv Pykhov, Sm Antsyferov Jan 2000

Transport Of Fine Sediment With Mesoscale Currents In The Shelf-Slope Zone Of The Sea, Gi Shapiro, Tm Akivis, Nv Pykhov, Sm Antsyferov

School of Biological and Marine Sciences

No abstract provided.

Go to article

Ecological Risk Assessment Of Endocrine Disruptors, Th Hutchinson, R Brown, Ke Brugger, Pm Campbell, M Holt, R Länge, P Mccahon, Lj Tattersfield, Egmond R Van Jan 2000

Ecological Risk Assessment Of Endocrine Disruptors, Th Hutchinson, R Brown, Ke Brugger, Pm Campbell, M Holt, R Länge, P Mccahon, Lj Tattersfield, Egmond R Van

School of Geography, Earth and Environmental Sciences

No abstract provided.

Go to article

An Evaluation Of The Use Of Spectral Properties In Monitoring Stress In Marine Macroalgae, Sarah Jane May Jan 2000

An Evaluation Of The Use Of Spectral Properties In Monitoring Stress In Marine Macroalgae, Sarah Jane May

School of Biological and Marine Sciences Theses

The overall aim of this thesis was to assess the potential of developing specific quantifiable assays of pollutant damage based on changes on the in vivo optical properties of macroalgae, applicable to laboratory and remote systems. The green macroalgae, E.intestinalis, was exposed to selected trace metals (copper and zinc), triazine herbicides (Irgarol 1051 and atrazine) and a series of alcohols (n = 1 - 9). The algal in vivo spectral properties, measured using a spectrophotometer fitted with an integrating sphere, determined changes due to exposure, and results were compared with established methods, including growth and fluorescence, to assess algal health …

Go to article

Models Of Oxidative Stress Induced By Disease Or Pollution In Invertebrates And Vertebrates, Heather Clare Meigh Jan 2000

Models Of Oxidative Stress Induced By Disease Or Pollution In Invertebrates And Vertebrates, Heather Clare Meigh

School of Biological and Marine Sciences Theses

Glutathione and its related enzymes have a central role in the antioxidant mechanisms of both invertebrates and vertebrates. Evidence suggests that changes in antioxidant defence mechanisms are associated with the late complications of diabetes. In addition, invertebrates show changes in antioxidant mechanisms in response to contamination; these changes have the potential to be utilised in the environmental monitoring of pollution. The present study investigated the role of glutathione and its related enzymes with regard to complications of diabetes and toxicity exposure using the crab, Carcinus maenas. A preliminary investigation showed that glutathione peroxidase and glutathione reductase activities are unaltered in …

Go to article

Qualitative Analysis Of Indigo Precursors From Woad By Hplc And Hplc‐Ms, Kg Gilbert (Nee Stoker), Dj Hill, C Crespo, A Mas, Et Al Jan 2000

Qualitative Analysis Of Indigo Precursors From Woad By Hplc And Hplc‐Ms, Kg Gilbert (Nee Stoker), Dj Hill, C Crespo, A Mas, Et Al

Peninsula Medical School

A qualitative method has been devised to analyse the indigo precursors in leaf extracts of woad (Isatis spp.) using HPLC coupled to an evaporative light scattering detector and confirmed using HPLC coupled, on line, to a particle beam mass spectrometer. Using this technique, indican has been positively identified in shoot extracts of European (I. tinctoria) and Chinese (I. indigotica) woad. Greater amounts of indican were found in the Chinese compared with the European woad. Copyright © 2000 John Wiley & Sons, Ltd.

Go to article

Qualitative Analysis Of Indigo Precursors From Woad By Hplc And Hplc-Ms, Kg Gilbert, Dj Hill, C Crespo, A Mas, M Lewis, B Rudolph, Dt Cooke Jan 2000

Qualitative Analysis Of Indigo Precursors From Woad By Hplc And Hplc-Ms, Kg Gilbert, Dj Hill, C Crespo, A Mas, M Lewis, B Rudolph, Dt Cooke

Peninsula Medical School

No abstract provided.

Go to article

Maerl-Forming Coralline Algae And Associated Phytobenthos From The Maltese Islands, E Lanfranco, M Rizzo, J Hall-Spencer, Ja Borg, Pj Schembri Jun 1999

Maerl-Forming Coralline Algae And Associated Phytobenthos From The Maltese Islands, E Lanfranco, M Rizzo, J Hall-Spencer, Ja Borg, Pj Schembri

School of Biological and Marine Sciences

Maerl grounds consist mainly of unattached non-geniculate coralline algae, known as rhodoliths, and their algal debris. The recent discovery of such grounds around the Maltese Islands led to the present study of rhodolith-forming species. Gross morphology of the rhodoliths was highly variable so identifications were based on microscopic examination of fertile material. Investigations using optical and scanning electro microscopy confirmed that five main species of rhodolith-forming coralline algae were present: Lithophyllum racemus, Lithothamnion corallioides, Lithothamnion minervae, Mesophyllum alternans and Phymatolithon calcareum. Two other heavily calcified species, tentatively identified as Peyssonnelia rosa-marina and Neogoniolithon brassica-florida on the basis of gross morphology, …

Go to article

Intelligent Control Strategies For An Autonomous Underwater Vehicle, Paul Jason Craven Jan 1999

Intelligent Control Strategies For An Autonomous Underwater Vehicle, Paul Jason Craven

School of Engineering, Computing and Mathematics Theses

The dynamic characteristics of autonomous underwater vehicles (AUVs) present a control problem that classical methods cannot often accommodate easily. Fundamentally, AUV dynamics are highly non-linear, and the relative similarity between the linear and angular velocities about each degree of freedom means that control schemes employed within other flight vehicles are not always applicable. In such instances, intelligent control strategies offer a more sophisticated approach to the design of the control algorithm. Neurofuzzy control is one such technique, which fuses the beneficial properties of neural networks and fuzzy logic in a hybrid control architecture. Such an approach is highly suited to …

Go to article

Morphology And Electrophysiology Of Retinal Photoreceptor Terminations In The Octopus (Eledone Cirrosa) Optic Lobe, Dominic Anthony Hussey Jan 1999

Morphology And Electrophysiology Of Retinal Photoreceptor Terminations In The Octopus (Eledone Cirrosa) Optic Lobe, Dominic Anthony Hussey

School of Biological and Marine Sciences Theses

Cephalopods possess a well-developed visual system encompassing a pair of camera-type eyes attached to specific visual processing regions of the central nervous system known as the optic lobes. The retina contains a single type of photoreceptive cell, which send axons via a dorso-ventral chiasma to the optic lobes. Although electrophysiological recordings have been routinely obtained from the retina there are few recordings from the optic lobe. This study investigated the morphology and electrophysiology of the first synapse in the Octopus (Eledone cirrosa) visual system. The morphology and innervation patterns of individual optic nerves onto the optic lobe were revealed using …

Go to article

Diesel Engine Exhaust Emission Fractions: Clastogenic Effects In Vitro, Rachael Ann Whittington Jan 1999

Diesel Engine Exhaust Emission Fractions: Clastogenic Effects In Vitro, Rachael Ann Whittington

School of Biological and Marine Sciences Theses

Despite being hailed as a green fuel, emissions from diesel engines including particulate matter (PM10 and PM 2.5) have been implicated in a range of adverse human health effects from lung and bladder cancers to premature mortality. In this study diesel engine exhaust emissions were collected from a light duty direct injection diesel engine on a standard test bed. Engine conditions of speed and load were altered to provide a set of total emission samples from over the engine's operating range. Diesel emission samples collected were fractionated on a silica column into aliphatic, aromatic, and polar groups of compounds, which …

Go to article

Assessment Of The Effects Of Uv-B In Marine Macroalgae: Potential Biomarkers Of Exposure And Effect, Britt Cordi Jan 1999

Assessment Of The Effects Of Uv-B In Marine Macroalgae: Potential Biomarkers Of Exposure And Effect, Britt Cordi

School of Biological and Marine Sciences Theses

Studies were undertaken to investigate the suitability of several molecular and physiological responses as biomarkers of UV-B exposure in several marine macroalgal species. Investigations into the sensitivity of mature plants and the reproductive unicells were also carried out. Furthermore, experiments were conducted to determine the interaction between UV-B radiation and the antifouling compound Irgarol 1051 in both a fouling alga and two non-target algal species. Chlorophyll fluorescence, in vivo thallus absorptance and ion leakage were investigated for their suitability as physiological biomarkers of UV -B exposure in the intertidal alga Enteromorpha intestinalis and the subtidal alga Palmaria palmata. DNA damage …

Go to article

Dietary Interactions Influencing Feed Intake, Nutrient Utilisation And Appetite Regulation In The Rainbow Trout, Oncorhynchus Mykiss, Ahmet Adem Tekinay Jan 1999

Dietary Interactions Influencing Feed Intake, Nutrient Utilisation And Appetite Regulation In The Rainbow Trout, Oncorhynchus Mykiss, Ahmet Adem Tekinay

School of Biological and Marine Sciences Theses

Dietary factors are one of the most significant considerations in the regulation of appetite in fish since dietary nutrient and energy concentration modulate feed intake in the short and longer term. These interactions may also be important from a commercial aspect, since the objective of aquaculture is to obtain maximum growth, feed efficiency and consumer acceptance of the product. This thesis addresses the major dietary components which are likely to influence appetite in rainbow trout. These include dietary lipid level, carbohydrate content and degree of complexity as well as energy density and protein/energy ratio. Experimental data is presented which examines …

Go to article

Trauma Stress Severity And Road Traffic Accidents: A Prospective Pilot Study Into 11 Causal Factors, Louise Horner-Baggs Jan 1999

Trauma Stress Severity And Road Traffic Accidents: A Prospective Pilot Study Into 11 Causal Factors, Louise Horner-Baggs

School of Psychology Theses

Factors associated with the development of post traumatic stress symptomatology have frequently been reported in the literature over the last decade. However, of the empirical studies examining these factors, few have used appropriate methodological designs and most have examined one factor in isolation. This pilot study used a cross-lagged panel analysis design to investigate 11 factors previously identified in the literature as being causally related to the development of post traumatic stress symptomatology. The 11 factors investigated were: perceived controllability, perceived predictability, perceived threat, shattering and confirmation of core assumptions, causal attributions, supportive and unsupportive behaviour, peritraumatic dissociation and the …

Go to article

A Submersible Battery-Powered Flow Injection (Fi) Sensor For The Determination Of Nitrate In Estuarine And Coastal Waters, Arj David, T Mccormack, Pj Worsfold Jan 1999

A Submersible Battery-Powered Flow Injection (Fi) Sensor For The Determination Of Nitrate In Estuarine And Coastal Waters, Arj David, T Mccormack, Pj Worsfold

School of Geography, Earth and Environmental Sciences

The design, construction and performance of a remotely deployed submersible flow injection-based nutrient (total oxidized nitrogen) sensor are described. The sensor featured a custom-built microcomputer and a solid-state, flow-through spectrophotometric detector, and the derivatization chemistry was based on in-line coppercadmium reduction of nitrate to nitrite, and diazotization with N1NED and sulphanilamide. The limit of detection was 0.0014 mg l-1 NO3-N and the linear range was 0.0014- 0.77 mg l-1 with a 260 μl sample volume and a 20 mm path length flow cell. Results from submersed deployments in the Tamar estuary and North Sea are also reported.

Go to article

Atmospheric Trace Metal Biogeochemistry And Fluxes To Shelf Seas, Christina Louise Wells Jan 1999

Atmospheric Trace Metal Biogeochemistry And Fluxes To Shelf Seas, Christina Louise Wells

School of Geography, Earth and Environmental Sciences Theses

The total concentrations of particulate trace metals (Al. Cd, Co, Cu, Fe. Mn, Na. Ni. Pb, Zn) with analytical quality assurance, have been determined in atmospheric aerosols at two coastal sites, and during cruises in the Celtic Sea. Sampling at a site on the western English Channel covered 19 months and represents one of the most comprehensive time series of trace metals in atmospheric aerosols. Aerosol concentrations of Cd. Cu, Pb and Zn for the English Channel were lower than previously reported and Al. Co and Mn concentrations were similar to literature values. The elements were grouped according to behaviour …

Go to article

Monitoring Of Trace Metal Behaviour In Natural Waters, David John Whttworth Jan 1999

Monitoring Of Trace Metal Behaviour In Natural Waters, David John Whttworth

School of Geography, Earth and Environmental Sciences Theses

An automated voltammetric dissolved trace metal monitor was developed and validated for in situ analysis of estuarine waters. The system was successfully applied to the determination of Ni concentrations during two studies in the Tamar Estuary. The automated system used Adsorptive Cathodic Stripping Voltammetry (AdCSV) for trace metal analysis with a continuous flow sampling procedure and an on line LTV digestion system to ensure complete breakdown of interfering and metal complexing organic ligands. Its application to the measurement of total dissolved Ni in the Tamar Estuary showed a high measuring frequency of up to 6 fully calibrated samples per hour …

Go to article

The Distribution And Reactivity Of Organochlorines In Estuaries, Andrew O. Tyler Jan 1999

The Distribution And Reactivity Of Organochlorines In Estuaries, Andrew O. Tyler

School of Geography, Earth and Environmental Sciences Theses

In February 1997, the Governing Council of the United Nations Environment Programme initiated a protocol to reduce the risks to human health and the environment arising from persistent organic pollutants. The initial list of 12 families of organochlorine pollutants included polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) selected for their persistence, bioaccumulation capacity and toxicity. The aim of this work was to further understanding of the behaviour of these organochlorines (OCs) in estuarine systems. Field surveys were conducted at UK estuarine (Humber, Clyde and Dee) and coastal locations. Sediments were analysed for OCs and a range of …

Go to article

Antimony Speciation By Chromatographic Sample Introduction To Plasma Spectroscopy, Alen Bruce Guy Jan 1999

Antimony Speciation By Chromatographic Sample Introduction To Plasma Spectroscopy, Alen Bruce Guy

School of Geography, Earth and Environmental Sciences Theses

Antimony (Sb), an element in Group V of the Periodic Table, has an ancient and varied chemistry with many applications in industry and medicine. However, although sensitive analytical methods exist for the determination of Sb very tittle is known about the speciation of the element. It is widely known that the toxicity of Sb is not only dependent upon its oxidation state but also its molecular form. Thus this study has utilised chromatographic sample introduction directly coupled to plasma spectroscopic instruments to facilitate separations of Sb based upon molecular form coupled with sensitive detection methods. Fundamental studies, using NMR to …

Go to article

Automated Flow Injection Instrumentation For Monitoring Nitrogen Species In Natural Waters, Simon Philip Coles Jan 1999

Automated Flow Injection Instrumentation For Monitoring Nitrogen Species In Natural Waters, Simon Philip Coles

School of Geography, Earth and Environmental Sciences Theses

The provision of high quality analytical data is an essential prerequisite for understanding the biogeochemical cycling of nutrients in the aquatic environment. Due to the instability of samples collected for nutrient determinations however, in situ analysis is preferred. This approach also allows for high temporal and spatial resolution of the data and alteration of the sampling frequency to meet local environmental needs. Chapter One describes the role of nitrogen species, particularly ammonia and nitrate, in the aquatic environment, their sources, and possible environmental effects and summarises analytical techniques for their determination. Solid state miniaturised detectors and their suitability for in …

Go to article

Structural Characterisation And The Diagenetic Pathways Of C25 Highly Branched Isoprenoid Hydrocarbons, Lesley Anne Johns Jan 1999

Structural Characterisation And The Diagenetic Pathways Of C25 Highly Branched Isoprenoid Hydrocarbons, Lesley Anne Johns

School of Geography, Earth and Environmental Sciences Theses

Highly branched isoprenoid (HBI) hydrocarbons have been widely reported in recent sediments. It is known that two species of diatomaceous algae, the diatoms Haslea ostrearia and Rhizosolenia setigera are able to biosynthesise C25 HBI alkenes. Large scale cultures of H. ostrearia studied previously, allowed isolation and characterisation of five HBI polyenes. The stereochemistry of the chiral centres was not reported however. The concentrations of HBIs often decrease with depth in sediment cores but the reasons for this are unknown.

Go to article

Analytical Applications Of The Peroxyoxalate Chemiluminescence Reaction, Matthew Graham Sanders Jan 1999

Analytical Applications Of The Peroxyoxalate Chemiluminescence Reaction, Matthew Graham Sanders

School of Geography, Earth and Environmental Sciences Theses

The overall objectives of this thesis were to investigate the potential of the peroxyoxalate chemiluminescence (POOL) reaction for the quantitative detection of target analytes in non-aqueous matrices and to compare quantitative performance with fluorescence detection. The target analytes investigated were polycyclic aromatic hydrocarbons (PAHs) and aliphatic amines. These were selected as an important class of compounds in engine exhaust emissions and a detergent additive in diesel fuel respectively. Chapter one outlines the challenges of analysing petroleum products and engine exhaust emissions and discusses the potential of luminescence techniques, particularly chemiluminescence (CL), for the quantification of trace components. The chapter also …

Go to article

Mercury Species In Natural Gas Condensate, Azman Bin Shafawi Jan 1999

Mercury Species In Natural Gas Condensate, Azman Bin Shafawi

School of Geography, Earth and Environmental Sciences Theses

The presence of ultra-trace levels of mercury in industrial gas and condensate streams is a cause of both environmental and production concern. The toxic nature of the element, in all forms, together with its ability to shut-down large processing plants dictates a need for its accurate and precise measurement. The study which investigated the recovery of various mercury species, spiked into synthetic and real condensate samples using conventional and new digestion and/or extraction techniques showed recovery was dependent upon the speciation. Using the most efficient technique, L

Go to article

The Origins And Occurrence Of Estrogenic A-Ring Aromatic Steroids In U.K. Sewage Treatment Works Effluents, Stewart James Niven Jan 1999

The Origins And Occurrence Of Estrogenic A-Ring Aromatic Steroids In U.K. Sewage Treatment Works Effluents, Stewart James Niven

School of Geography, Earth and Environmental Sciences Theses

There is worldwide concern over the possible estrogenic effects of organic chemicals on a variety of wildlife and indeed on humankind. In the U.K., estrogenic compounds in sewage treatment works (STW) effluents have been implicated in causing the increases in egg yolk protein production observed in caged male trout and other fish species. At the initiation of the present study, few of the estrogenic compounds in STW effiuents had been recognised, although circumstantial evidence suggested that steroidal hormones were primary candidates. Cholesterol is abundant in STW effluents and is the precursor of all steroidal hormones biosynthesised in mammalian systems. Thus, …

Go to article

Responses Of Recent Benthic Foraminifera To Metal Pollution In South West England Estuaries: A Study Of Impact And Change, Sheila Joan Stubbles Jan 1999

Responses Of Recent Benthic Foraminifera To Metal Pollution In South West England Estuaries: A Study Of Impact And Change, Sheila Joan Stubbles

School of Geography, Earth and Environmental Sciences Theses

There was a major discharge into Restronguet Creek, south-west Cornwall in January 1992 of metalled acidic mine water drainage from the recently closed Wheal Jane tin mine. Shortly after this discharge a post-impact study using the responses of Recent benthic foraminifera as indicators of metal pollution was carried out on this Creek which had not been investigated previously. Because of a lack of pre-discharge foraminiferal data from Restronguet Creek, other estuaries, which previously drained metal mining regions, have been sampled in order to determine the background levels in foraminiferal populations. These estuaries, Fowey (Cornwall), Avon and Erme (south-west Devon) have …

Go to article

The Hydrology Of A Major Valley Wetland At Goss Moor, Cornwall, Carl Alexander Lugemalila Ishemo Jan 1999

The Hydrology Of A Major Valley Wetland At Goss Moor, Cornwall, Carl Alexander Lugemalila Ishemo

School of Geography, Earth and Environmental Sciences Theses

This thesis aims to fiimish an understanding of the water fluxes and storages occurring at the subcatchment scale in Goss Moor, a large lowland wetland in Cornwall, UK. Goss Moor constitutes approximately 5 km^ of poor fen and similar wetland areas sited on clayey alluvial and periglacial deposits in the base of a broad/shallow headwater valley. The bedrock is kaolinised granite and pelite. The hydrological characterisation was achieved using variables measured directly on site, using spectrally derived stream flow components and using flows output from a caUbrated numerical model of transient groundwater flow beneath the wetland. The study demonstrated the …

Go to article

The Autecology Of The Meadow Thistle (Cirsium Dissectum L. Hill) On Devon Rhos Pastures, With Particular Reference To The Effect Of Major Environmental Variables On The Population Dynamics, John Ross Jan 1999

The Autecology Of The Meadow Thistle (Cirsium Dissectum L. Hill) On Devon Rhos Pastures, With Particular Reference To The Effect Of Major Environmental Variables On The Population Dynamics, John Ross

School of Geography, Earth and Environmental Sciences Theses

Semi-natural wet grassland communities are rapidly disappearing from the farmed landscape. Protection of remaining areas and restoration of degraded areas has become a priority with organisations concerned with the conservation of biodiversity in the U.K. The research described in this thesis provides an insight into the community dynamics of one particularly rare plant community, the Cirsio-Molinietum fen meadow (NVC M24). This was achieved by examining the autecology of Cirsium dissectum, one of the key indicator species of this community. The habitat environment where C. dissectum is present was characterised at eight Devon M24 locations and ten non-M24 locations. This revealed …

Go to article

First Prev Next Last