Showing papers by "Edinburgh Napier University published in 1998"
TL;DR: In this paper, a sequence of events following pulmonary deposition of ultrafine particles can be hypothesised, based on studies to date, which can be seen as an important factor in stimulating inflammation and interstitial transfer.
779 citations
376 citations
TL;DR: In this article, a series of interdisciplinary field studies was conducted on the Canary Island archipelago, which straddles the transition between the coastal upwelling regime and the warmer, oligotrophic waters of the open ocean.
373 citations
TL;DR: The present review seeks to put the apparently conflicting findings of cancer incidence in quartz-exposed industries into a unifying thesis, based on mechanistic studies, and suggests that quartz cannot be death with as a single hazard entity, as is the case with most other chemicals.
Abstract: An IARC Working Group recently classified crystalline silica (quartz) into IARC's Group 1, i.e. a carcinogen. This classification is based on evidence of carcinogenicity in experimental animals and in humans. However, the evaluation stated that in making the overall evaluation, the Working Group noted that carcinogenicity to humans was not detected in all industrial circumstances studied and that carcinogenicity may be dependent on inherent characteristics of the crystalline silica or on external factors affecting its biological activity. The present review seeks to put the apparently conflicting findings of cancer incidence in quartz-exposed industries into a unifying thesis, based on mechanistic studies. These mechanistic studies have enabled the events leading from deposition of quartz to silicosis and cancer to be partially elucidated and have demonstrated that the biological effects of quartz can be understood in terms of surface reactivity. We particularly emphasise the ability of quartz to generate free radicals and cause oxidative stress and the fact that this could be modified by a range of substances that affect the quartz surface; some of these modifying substances could originate from other minerals. We therefore propose that the hazard posed by quartz is not a constant entity, but one that may vary dramatically depending on the origin of the silica sample or its contact with other chemicals/minerals within its complex constitution. The mechanistic data described here could assist in the interpretation of epidemiological studies and pose further hypotheses that could be tested in order to help resolve the quartz carcinogenesis anomaly. The data suggest that quartz cannot be death with as a single hazard entity, as is the case with most other chemicals.
239 citations
TL;DR: In this article, the authors investigated the relationship between company characteristics including size, age, location and industry group, and profitability and growth in a sample of 38 small manufacturing firms located in Tayside Region.
Abstract: Using accounts data for a sample of 38 small manufacturing firms located in Tayside Region, this paper investigates the relationship between company characteristics including size, age, location and industry group, and profitability and growth. The trade‐off between the possibly conflicting objectives of profit and growth is considered primarily from the entrepreneurial rather than the managerial standpoint which previous econometric studies of small firm performance have concentrated on. Motivations for undertaking entrepreneurial activity and their possible relationships with profitability and growth are discussed and a number of hypotheses developed. From this perspective it is argued that a firm size measure based on employment is more appropriate than one based on sales or assets which previous studies have used. Firm characteristics are found to be of limited value in explaining profitability. However, larger firms are found to grow faster than smaller, and younger firms are found to grow faster than older. This is also some evidence that growth is stronger in urban than in suburban or rural locations. It is possible that entrepreneurial motivations are an important factor in this regard and it is suggested that future econometric studies of small firm performance take these into account.
231 citations
TL;DR: Biosurfactants may find applications in the near future in the environmental remediation industries, where the requirement for purified molecules is of less importance and the cost of production is considerably higher than for synthetic surfactants.
Abstract: Like other hydrocarbon-oxidising bacteria, rhodococci respond to the presence of alkanes by producing biosurfactant molecules to improve their ability to utilise these hydrophobic compounds as growth substrates. In the rhodococci these surfactants are predominantly glycolipids, the majority of which remain cell-bound during unrestricted growth. Most work has been done on the trehalose mycolates formed by Rhodococcus erythropolis, but nitrogen- limited conditions lead to the production of anionic trehalose tetraesters also.
228 citations
TL;DR: It is suggested that uf CB induces a greater oxidative stress than fine CB, and that this may play a role in the toxicological effects of this ultrafine particle.
224 citations
TL;DR: The many isoforms of splicing of at least 10 of the 20 CD44 exons during mRNA CD44 potentially endow cells with a set of functions, which processing introduces additional sequences at a single operate both in adult and fetal life.
Abstract: oresis (SDS–PAGE gels) of 80–95 000. This difference is the CD44 has many guises: a differentiation antigen during lymresult of extensive glycosylation of the extracellular domain, phopoiesis, an adhesion molecule for lymphocyte–endothelial which contains many sites for both Nand O-linked carbocell interactions, a glycoprotein with the ability to remodel the hydrates. Most of the potential N-linked sites are located in extracellular matrix during embryonic development, and a the membrane distal region, while the membrane proximal potential marker of malignancy and metastasis. This versatility domain has many O-linked sites.3–6 There are also four in function results from the expression of a large group of consensus sequences for attachment of chondroitin sulphate CD44 glycoproteins, where isoforms differ both in amino acid in the membrane proximal region. Not much is known about sequence and carbohydrate composition. Heterogeneity generthe structures of oligosaccharides present at any of these sites, ated by alternative splicing of a large number of additional which is a pity, because cell type-dependent glycosylation has exons, in a region of mRNA corresponding to the extracellular a major effect on CD44 function. domain of CD44, is enhanced by differential glycosylation of Polypeptide isoforms of CD44 are produced by alternative the resulting polypeptide isoforms. The many isoforms of splicing of at least 10 of the 20 CD44 exons during mRNA CD44 potentially endow cells with a set of functions, which processing. This introduces additional sequences at a single operate both in adult and fetal life, in normal and malignant site between amino acids 202 and 203 in the membrane cells, in the immune system and other tissues. proximal extracellular domain of CD44s.3,6–10 Potentially,
205 citations
TL;DR: The European Commission Water Framework Directive (ECWDF) as mentioned in this paper has been proposed for catchment management throughout Europe and could have major impacts on the conservation and restoration of aquatic ecosystems, and the proposed mechanisms for determining water quality status under the Directive are described.
Abstract: 1. The forthcoming European Commission Water Framework Directive will introduce catchment management throughout Europe, and could have major impacts on the conservation and restoration of aquatic ecosystems. The Directive is outlined, and the proposed mechanisms for determining water quality status under the Directive are described.
2. The Directive is assessed using the developing ideas of ecosystem health. These combine scientific validity with an open acknowledgement of the value judgements inherent in all assessments of ecological quality, and emphasize the importance of public involvement.
3. Permitted derogations and exemptions are identified and their likely consequences discussed. These include substantial reductions in the potential of the Directive to improve water status in some cases. Existing bioassessment methods relevant to the proposed scheme are reviewed, and the sampling and statistical implications of the Directive are explored. Much work is needed on the development of ecological classification and referencing systems if the requirements of the Directive are to be met.
4. The emphasis of the Directive on biological (and not just chemical) quality goals, and the introduction of a consideration of ecological functioning (as well as structure) is welcomed. Although the Directive requires the assessment of hydromorphological and chemical, in addition to biological, variables, in most cases biological assessment is given priority. We advocate inclusion of all three elements in quality assessments.
5. The Directive gives little advice on policy integration for catchment management at European and national levels, and fails to provide for public involvement in the process of ecosystem management. These omissions will limit the ability of the Directive to deliver ecosystem health, and need to be addressed if the goals of the Directive are to be achieved. © 1998 John Wiley & Sons, Ltd.
118 citations
TL;DR: An efficient algorithm for determining the stochastic user equilibrium solution for logit-based loading, based on the Davidon-Fletcher-Powell function minimisation method, which is found to give the fastest rate of convergence for all but the smallest network.
Abstract: The paper proposes an efficient algorithm for determining the stochastic user equilibrium solution for logit-based loading. The commonly used Method of Successive Averages typically has a very slow convergence rate. The new algorithm described here uses Williams’ result [ Williams, (1977) On the formation of travel demand models and economic evaluation measures of user benefit. Environment and Planning 9A(3), 285–344] which enables the expected value of the perceived travel costs Srs to be readily calculated for any flow vector x. This enables the value of the Sheffi and Powell, 1982 objective function [Sheffi, Y. and Powell, W. B. (1982) An algorithm for the equilibrium assignment problem with random link times. Networks 12(2), 191–207], and its gradient in any specified search direction, to be calculated. It is then shown how, at each iteration, an optimal step length along the search direction can be easily estimated, rather than using the pre-set step lengths, thus giving much faster convergence. The basic algorithm uses the standard search direction (towards the auxiliary solution). In addition the performance of two further versions of the algorithm are investigated, both of which use an optimal step length but alternative search directions, based on the Davidon–Fletcher–Powell function minimisation method. The first is an unconstrained and the second a constrained version. Comparisons are made of all three versions of the algorithm, using a number of test networks ranging from a simple three-link network to one with almost 3000 links. It is found that for all but the smallest network the version using the standard search direction gives the fastest rate of convergence. Extensions to allow for multiple user classes and elastic demand are also possible.
108 citations
TL;DR: The need for separate, DBT- and BTH-specific desulphurisation routes is rationalised in terms of the chemical differences between the two compounds.
Abstract: Desulphurising enzymes remove the sulphur moiety from an organosulphur molecule leaving the carbon skeleton intact. Two kinds of desulphurisation reaction are recognised. The dibenzothiophene (DBT)-specific pathway desulphurises DBT to inorganic sulphite and 2- hydroxybiphenyl (HBP), and the benzothiophene (BTH)-specific pathway desulphurises BTH to 2-(2′-hydroxyphenyl)ethan 1-al (HPEal) and probably inorganic sulphite. The DBT-desulphurisation pathway was originally identified in Rhodococcus erythropolis strain IGTS8 (ATCC 53968), and the BTH-desulphurisation pathway in Gordonia sp. strain 213E (NCIMB 40816). These organisms do not further metabolise the organic product of desulphurisation. In this article current knowledge of the biochemistry and genetics of the desulphurisation enzymes is reviewed. The need for separate, DBT- and BTH-specific desulphurisation routes is rationalised in terms of the chemical differences between the two compounds. The desulphurisation pathway is compared with other microbial DBT- degrading enzyme systems. Finally some comments are made concerning the application of desulphurisation enzymes for fuel desulphurisation and on the relevance of these enzymes to the ecology of the mycolata (sensu Chun et al, 1996).
TL;DR: In this article, the authors describe the original research and development of an electronic load governor which is microprocessor-based and incorporates three-phase balancing, and the results of the implementation of the advanced algorithm in the control of micro hydroelectric power generation are presented and compared with the original algorithm.
Abstract: This paper describes the original research and development of an electronic load governor which is microprocessor-based and incorporates three-phase balancing. The combined study and testing of the transient behaviour of the governor indicated the need for an improved control algorithm. The results of the implementation of the advanced algorithm in the control of micro hydroelectric power generation are presented and compared with the original algorithm.
TL;DR: Experimental results on the constant current stressing and forming of hydrogenated amorphous silicon (a-Si) Cr/p+-V thin film devices are presented in this article, where an irreversible change of the initial higher resistance state into a permanent ''formed' state of lower resistance is described.
Abstract: Experimental results on the constant current stressing and forming of hydrogenated amorphous silicon (a-Si) Cr/p+-V thin film devices are presented. In the initial stage of electro-forming by constant current stressing, with increasing injection of charge via either increasing bias or time, the current=f(v) properties of devices exhibit an instability, as shown by a decrease in the reverse current. Eventually, with further increase in the current bias, the local current density reaches a critical value IF, and a rapid `runaway' processes occurs, which results in an irreversible change of the initial higher resistance state into a permanent `formed' state of lower resistance.
TL;DR: In this paper, the embodied energy of the four main materials used in the construction of an inert gas filled, double-glazed window, of a given size, was quantified.
TL;DR: In this paper, the authors examined the nature of entrepreneurial dynamics in small business service firms and found that entrepreneurs revise their motivations, objectives and strategies over time as a result of changes in market conditions or their own expectations.
Abstract: This paper examines the nature of entrepreneurial dynamics in small business service firms. The past decade has seen a rapid growth in the number of small business service firms, with a corresponding increase in their importance in terms of employment and income generation. Despite the growing body of research on the impact that the entrepreneur has on the performance of small firms, very little of this research has focused on small business service firms. This paper reports findings from a study of the entrepreneurship process in a sample of 20 small business service firms based in the west of Scotland. Using a qualitative research design, evidence is found that entrepreneurs revise their motivations, objectives and strategies over time as a result of changes in market conditions or their own expectations. The most prevalent new objective is found to be business growth which was pursued as a means of increasing profitability, which in turn satisfies both pecuniary and non‐pecuniary intrinsic motivations.
TL;DR: Members of the genus, particularly R. ruber, were shown to produce low toxicity surfactants effective in removing oil from surfaces, and crude surfactant complexes enhanced the degradation of crude oil, in the short term, when added to contaminated agricultural soil during bioremediation studies utilizing biopiling technology.
Abstract: Rhodococcus strains from the culture collection at the Institute of Ecology and Genetics of Microorganisms, Perm, Russia were examined for biosurfactant production during growth on n-alkanes and the ability to remove oil associated with contaminated sands and oil shale cuttings. Members of the genus, particularly R. ruber, were shown to produce low toxicity surfactants effective in removing oil from surfaces. The extent of desorption was inversely related to the concentration of high molecular weight hydrocarbons, namely asphaltenes and resins. In addition, crude surfactant complexes enhanced the degradation of crude oil, in the short term, when added to contaminated agricultural soil during bioremediation studies utilizing biopiling technology.
TL;DR: The association withAmyloid plaques may indicate that HSPG is involved in amyloid plaque formation and/or persistence but involvement with early diffuse forms of PrP suggests a more fundamental role in scrapie pathogenesis.
TL;DR: In this article, two models, MRM (meteorological radiation model) and CRM (cloud-cover radiation model), are presented, and a brief comparison of the two models is presented.
27 Sep 1998
TL;DR: Extensions to an evolutionary algorithm that timetables classes for an entire University are described and methods are described that allow timetables to be produced which have minimal changes compared to a full or partial reference timetable.
Abstract: This paper describes extensions to an evolutionary algorithm that timetables classes for an entire University. A new method of dealing with multi-objectives is described along with a user interface designed for it. New results are given concerning repair of poor recombination choices during local search. New methods are described and evaluated that allow timetables to be produced which have minimal changes compared to a full or partial reference timetable. The paper concludes with a discussion of scale-up issues, and gives some initial results that are very encouraging.
23 Sep 1998
TL;DR: A new chromosome representation for evolving digital circuits based on the chip architecture of the Xilinx 6216 FPGA is presented and it is noteworthy that the presence of elitism significantly improves the Genetic Algorithm performance.
Abstract: In this paper we present a new chromosome representation for evolving digital circuits. The representation is based very closely on the chip architecture of the Xilinx 6216 FPGA. We examine the effectiveness of evolving circuit functionality by using randomly chosen examples taken from the truth table. We consider the merits of a cell architecture in which functional cells alternate with routing cells and compare this with an architecture in which any cell can implement a function or be merely used for routing signals. It is noteworthy that the presence of elitism significantly improves the Genetic Algorithm performance.
TL;DR: Exposure to hyperoxia resulted in a time-dependent increase in GSH levels and γ-GCS activity, and dexamethasone exposure produced a significant time- dependent decrease in the levels of GSH andγ- GCS activity at 24-96 h.
Abstract: We studied the regulation of GSH and the enzymes involved in GSH regulation, γ-glutamylcysteine synthetase (γ-GCS) and γ-glutamyl transpeptidase (γ-GT), in response to the oxidants menadione, xanth...
TL;DR: Generalized linear modelling was used to develop regression estimates of expected junction accidents (both in total and disaggregated by severity, road surface condition and lighting condition) which allow for the possibility of accident risk varying over time.
TL;DR: IR thermography was used to identify the major sites of heat loss from a female barn owl and suggested that barn owls lose considerable amounts of heat during prolonged periods of flight, hypothesised that by being active in cool nocturnal conditions, barn Owls may exploit waste metabolic heat for thermoregulation.
TL;DR: In this article, a simple and precise meteorological radiation model (MRM) is presented, which enables computation of horizontal beam and diffuse solar radiation to be accomplished, given four basic meteorological parameters (hourly dry-and wet-bulb temperatures, atmospheric pressure and bright sunshine duration).
27 Sep 1998
TL;DR: It is shown that the amount of routing and functional resource have a marked effect on the success of the evolutionary process of combinational logic designs on a field-programmable gate array.
Abstract: This paper describes experiments to determine how the architecture vis-a-vis routing and functional resources affect the ease with which combinational logic designs may be evolved on a field-programmable gate array (FPGA). We compare two chromosome representations with differing levels of connectivity, and show that the amount of routing and functional resource have a marked effect on the success of the evolutionary process.
TL;DR: In this article, qualitative and quantitative data from first-year students from three contrasting academic courses were collected as part of an ongoing longitudinal study, which supported the widely held belief that assessment has an effect on student learning.
Abstract: Qualitative and quantitative data from first‐year students from three contrasting academic courses were collected as part of an ongoing longitudinal study. The findings support the widely held belief that assessment has an effect on student learning. These findings are echoed in data from a parallel study of second and third‐year students on the same courses. Interview data provided a snapshot of student experiences of learning and assessment. A number of important issues emerged relating both to organisational and personal factors. In addition, student preferences for particular types of assessment provided insights into their approaches to studying. Interview data were related to approaches to studying profiles and stress measures. Mismatches were identified and discussed, and some year and area differences were explored. Implications for both teachers and learners were considered.
TL;DR: The traditional car-following model is modified by adding a new nonlinear term to take account of the driver attempting to achieve a certain desired intervehicle separation distance as well as the traditional aim of matching the velocity of the vehicle ahead.
Abstract: The mathematical models used to describe the dynamical behavior of a group of road vehicles traveling in a single lane without overtaking are known as car-following models. These models are widely used in many commercially available microscopic traffic simulation software packages. They attempt to mimic the interactions between individual vehicles that are traveling sufficiently close together for the behavior of each vehicle to be dependent upon the motion of the vehicle immediately in front. In this paper we modify the traditional car-following model by adding a new nonlinear term to take account of the driver attempting to achieve a certain desired intervehicle separation distance as well as the traditional aim of matching the velocity of the vehicle ahead. Numerical solution of the resulting coupled system of nonlinear differential equations is used to analyze the stability of the equilibrium solution to a periodic perturbation. For certain parameter values chaotic oscillations are generated, consisting of a broad spectrum of frequency components. Such chaotic motion produces extremely complicated dynamical behavior that has an inherent lack of predictability associated with it. The results of simulating over a range of parameter values are presented and, where it is present, the degree of chaos is estimated.
01 Jan 1998
TL;DR: This paper describes work which attempts to evolve circuit solutions for combinational logic systems directly onto Xilinx 6000 FPGA parts, using a network list (netlist) chromosome and genes which represent circuit module function.
Abstract: This paper describes work which attempts to evolve circuit solutions for combinational logic systems directly onto Xilinx 6000 FPGA parts. The reason for attempting to evolve designs direct onto the device is twofold: (i) every circuit has a known functionality and (ii) every circuit must be able to be placed on the chip and then routed. Using evolutionary techniques allows us to consider these two important aspects of design and implementation as a single problem. The paper describes the basic method adopted, using a network list (netlist) chromosome and genes which represent circuit module function, and then discusses some of the results achieved, plus difficulties encountered, and some of the additional problems which still require to be solved in this new and exciting area of research.
TL;DR: In the case of Cramond Beach, Edinburgh, a two-fold increase in litter was found between April and October 1994 as discussed by the authors, although the proportion of items found in some categories had decreased (containers, confectionery and crisp wrappers, clothing, fishing line, fishing net, shotgun cartridges, metal, cardboard and paper).
TL;DR: The authors examines the roots of these dualistic approaches and subjects their claims to critical scrutiny, arguing that apparently fundamental differences may be better understood as differences of degree and emphasis rather than principle.
Abstract: A constant theme running through much of the literature on nationalism is the dualistic attempt to make clear and sharp distinctions between two kinds of nationalism, one progressive and benign, the other reactionary and malign. Examples include attempts to distinguish between Western and Eastern, political and cultural, civic and ethnic, liberal and illiberal types. This article examines the roots of these dualistic approaches and subjects their claims to critical scrutiny, arguing that apparently fundamental differences may be better understood as differences of degree and emphasis rather than principle. It suggests that all forms of nationalism have to confront and may be vitiated by the fundamental difficulty of what to do about the other, in relation to which the nation has to be both defined and constructed.