Showing papers by "Edinburgh Napier University published in 1996"

Adverse health effects of PM10 particles: involvement of iron in generation of hydroxyl radical.

Abstract: OBJECTIVES: Environmental particles < 10 microns average aerodynamic diameter (PM10) are associated with mortality, exacerbation of airways diseases, and decrement in lung function. It is hypothesised that PM10 particles, along with other pathogenic particles, generate free radicals at their surface in reactions involving iron, and that this is a factor in the pathogenicity of PM10 particles. Identification of free radical activity in PM10 and examination of the content and role of iron in this process was undertaken. METHODS: Free radical activity was detected with a supercoiled plasmid, phi X174 RF1 DNA, and measured as scission of the supercoiled DNA (mediated by free radicals) by scanning laser densitometry. The role of the hydroxyl radical was confirmed by the use of the specific scavenger mannitol, and the role of iron investigated with the iron chelator desferrioxamine-B (DSF-B). Iron released from PM10 particles at pH 7.2 and pH 4.6 (to mimic conditions on the lung surface and in macrophage phagolysosomes, respectively) was assessed spectrophotometrically with the Fe++ chelator ferrozine and the Fe+ + + chelator DSF-B. RESULTS: PM10 particles showed significant free radical activity by their ability to degrade supercoiled DNA. A substantial part of this activity was due to the generation of hydroxyl radicals, as shown by partial protection with mannitol. Similarly, DSF-B also conferred protection against the damage caused to plasmid DNA indicating the role of iron in generation of hydroxyl radicals. Negligible Fe++ was released at either pH 7.2 or pH 4.6 by contrast with Fe+ + +, which was released in substantial quantities at both pHs, although twice as much was released at pH 4.6. CONCLUSIONS: PM10 particles generate the hydroxyl radical, a highly deleterious free radical, in aqueous solution. This occurs by an iron dependent process and hydroxyl radicals could play a part in the pathogenicity of PM10 particles. Iron release was greatest at the pH of the lysosome (pH 4.6) indicating that iron may be mobilised inside macrophages after phagocytosis, leading to oxidative stress in the macrophages.

Theory of room temperature quantized resistance effects in metal-a-Si:H-metal thin film structures

Abstract: A theoretical model of room temperature quantized resistance steps is described in terms of movement of a free electron Fermi surface into a quantized k -space (associated with electron confinement in real space) under the influence of applied electric field. The model is in good accordance with experimental observations such as the non-periodicity in quanta and voltage space and gives very realistic values for the parameters of electron lifetime, Fermi wavevector and geometry. Room temperature quantization is observed when the value of free electron lifetime (∼ 10 −14 s) is matched with a small size for electron confinement (∼ 7 nm or less).

Capacitance anomaly near the metal—non-metal transition in Cr—hydrogenated amorphous Si—V thin-film devices

Abstract: We present experimental results that show a metal—non-metal (MNM) transition occurring in hydrogenated amorphous Si (a-Si: H) analogue memory devices as a function of temperature. The dc resistance of the devices undergoes a continuous change in the range 65–100 K from semiconductor-like behaviour to metallic behaviour, as the temperature increases. The ac conductivity, measured over the frequency range 1–3·1 × 107 Hz, shows an anomalous change as the temperature is varied over the MNM transition. Ac characteristics were modelled using multicomponent RC and RL equivalent circuits below and above the MNM transition region respectively. It is found that the capacitance increases markedly when the temperature approaches the MNM transition from the semiconductor side. Near the transition temperature this capacitance disappears, and the equivalent circuit now requires an inductive component together with a resistance which has a positive temperature coefficient of resistance equivalent to that of the ...

A Two-stage Housing Choice Forecasting Model:

Abstract: A new housing choice forecasting model is developed here to answer a practical question: how to forecast housing demand at a disaggregate level. Being different from the previous housing choice mod...

Binding of Aspergillus fumigatus spores to lung epithelial cells and basement membrane proteins: relevance to the asthmatic lung.

Abstract: BACKGROUND: Aspergillus fumigatus is an opportunistic pathogen to which asthmatic subjects are particularly susceptible. The ability of spores of A fumigatus to bind to pulmonary cells and basement membrane proteins was investigated to determine the mechanisms involved in this susceptibility. METHODS: Cells of the A549 pulmonary epithelial cell line or purified basement membrane proteins were immobilised on the wells of microtitre plates. They were then exposed to spores of A fumigatus in suspension, with or without various pretreatments of the spores, cells, and proteins. Adherent spores were counted by light microscopy. RESULTS: Spores of A fumigatus bound in a concentration dependent manner to A549 epithelial cells and pretreatment of cells with interferon gamma (2500 units/ml) caused a significant doubling of spore binding. Binding of spores to A549 cells was inhibited by about a third by pre-incubation of the spores with fibrinogen (100 micrograms/ml). Spores bound specifically to extracellular matrix (ECM) components laid down by A549 cells, and pretreatment of the ECM components with hydrogen peroxide (25-80 microM) enhanced spore binding by approximately one third. They also bound specifically and in a saturable manner to purified fibrinogen, fibronectin, laminin, type I collagen, and type IV collagen. Pre-incubation of spores with Arg-Gly-Asp tripeptide (RGD; 50-200 micrograms/ ml) inhibited binding to fibronectin and type I collagen by 50%. CONCLUSIONS: This study suggests that the presence of activated epithelial cells and the exposure of basement membrane that occurs in asthma, together with oxidant stress, may facilitate the colonisation of the asthmatic lung by A fumigatus. The RGD sequence may be involved in spore binding to some ECM proteins. Free fibrinogen may protect against binding of A fumigatus spores to the pulmonary epithelium.

Dissolved Oxygen and Nitrification in the Upper Forth Estuary During Summer (1982–92): Patterns and Trends

Abstract: River discharge, wastewater inputs and water quality data from summer surveys in the upper Forth estuary have been reviewed for the period 1982–92. Particular attention has been given to dissolved oxygen and its possible links to the processes involved in the cycling of dissolved inorganic nitrogen species. Average dissolved oxygen (DO) concentrations for a particular year are linked with river flow; DO concentrations were lowest in years when river flow was low. Average DO concentrations in the upper Forth estuary have increased since 1959 when records began; however, the inter-annual variability in river flowprecludes the detection of any significant trend over the present study period. An important process contributing to the development of the oxygen minimum in the upper estuary is nitrification. A comparison has been made between total oxidized nitrogen (TON) concentrations (i.e. nitrate+nitrite) observed in river water, and those predicted by extrapolating down estuary TON/salinity relationships to zero. The latter are always larger than the former with the greatest discrepancies observed under low river flows. It is suggested that under low flow conditions, the longer water residence times in the upper estuary enable nitrification to proceed to a greater extent. Ample particulate organic nitrogen (PON) required for nitrification is demonstrated to exist in the turbidity maximum. This can originate from the river and/or the estuary and may be of natural or anthropogenic origin. Evidence is presented to show that the magnitude of the internally generated TON source has increased over the period under study. Maximum ammonia and nitrite concentrations in the estuary tend to be associated with years in which river flow is low. The mid-estuarine concentration maxima for nitrite are indicative of a benthic source, their locations are downstream of the nitrification-produced nitrate maximum. Their distributions are consistent with processes breaking down PON in reducing sediments (e.g. denitrification). Therefore, lower DO concentrations in the water column may be taken as indicative of more reducing conditions close to the surface sediments. An oxygen budget is constructed for the upper estuary. While gas exchange is identified as the major source of oxygen overall, DO from river water is likely to dominate at low salinity. The main sinks for oxygen in the estuary are nitrification, inputs of BOD and sediment oxygen demand. The link between high river flows and improved water quality is attributed not only to the oxygen contained in river water, but also to the associated shift of the turbidity maximum further downstream where the volume of the estuary is greater. A complex picture emerges of chemical and physical processes tending to act in concert towards low DO concentrations under low river flow conditions.

A comparison of methods of determining and predicting the pathogenicity of mineral fibers

Abstract: Most authors consider that long-term inhalation studies represent the most reliable method of obtaining data on the pathogenicity of mineral fibers. However, because of the length of time required and the great cost of inhalation work, other methods of examining the biological effects of mineral fibers have been used. The program of work described here was designed to compare a wide range of techniques, including inhalation, for determining the biological effects of a selection of man-made mineral fibers. Silicon carbide whiskers were examined as a very durable material and also a less durable glass microfiber (code 100/475) as a relatively soluble man-made vitreous fiber. Amosite asbestos was used as a positive control. long-term inhalation studies with full-life-span follow-up demonstrated that amosite and silicon carbide were both fibrogenic and carcinogenic in rats, while glass microfiber produced very little fibrosis and a few benign pulmonary tumors in numbers similar to those found in contr...

Implementing cultural change through human resources: the elusive organization alchemy?

Abstract: Examines approaches taken by two UK hotels for survival in the current complex environment in which greater competition, market changes and technological advances are affecting the manner in which the hospitality industry is operating. Examines strategies which have been implemented in an attempt to ensure long‐term success. Analyses the manner in which these organizations have undertaken the process of culture change in order to achieve and maintain a competitive advantage. Focuses on the role of human resource management within this process.

An advanced electronic load governor for control of micro hydroelectric generation

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.

A matter of chaos ‐ some issues for hospitality businesses

Abstract: With reference to the concepts of chaos theory, proposes that long‐term strategic planning is of little benefit to businesses (especially small businesses) operating in the hospitality industry, and that managerial focus should emphasize innovative and creative practices in order to sustain competitive advantage. To achieve this, organizations need to have a clear vision of where they want to be and attempt to achieve this aim by adapting to situations as they arise. Today’s hospitality organizations should not try and overcome their environment by predicting future outcomes but instead should change and adapt with the environment.

Inhibition of the transcription factors NF-kappa B and AP-1 underlies loss of cytokine gene expression in rat alveolar macrophages treated with a diffusible product from the spores of Aspergillus fumigatus.

Abstract: The spores of Aspergillus fumigatus have a survival advantage over other respirable fungal spores in the lung, leading to a number of lung diseases associated with this fungus. We have hypothesized that a component on the spore surface can inhibit the activation of alveolar macrophages, known to play an essential role in immune regulation in the lung. A diffusible product from the spores of A. fumigatus (AfD) inhibited the production of tumor necrosis factor alpha (TNF alpha) protein by alveolar macrophages in an enzyme-linked immunosorbent assay. Using a semiquantitative reverse transcription-polymerase chain reaction, we also demonstrated a potent inhibitory effect of AfD on the production of proinflammatory cytokine transcripts in rat alveolar macrophages. The inhibition occurred at the level of transcription, with AfD inhibiting the synthesis of TNF alpha-and interleukin 6 (IL-6)-specific mRNA transcripts. No effect was seen on the synthesis of interleukin 1 beta (IL-1 beta) cytokine transcripts or on...

The literature search: a library‐based model for information skills instruction

Abstract: It is expected that instruction in information skills (formerly known as bibliographic instruction) will be an important function of libraries in the “information society”. Describes a model for teaching the core informational skill of library‐based literature searching (information retrieval). It centres on a flow chart of the main stages in a systematic search: create set of search terms; formulate logical search statement; estimate parameters of search; search information sources; and record and evaluate references. The flow chart is flanked by two columns. One contains conceptual frameworks which illuminate aspects of the search process, such as the information chain and QRAQ (quantity, relevance, authority and quality), a simple schema for evaluating bibliographic references. The other column identifies library tools and services which can assist the end‐user at various stages of a search, such as search analysis and bibliographic instruction. The model was developed primarily in an academic, health sciences environment, but operates at a sufficiently high level of generality to be of wide applicability in information skills programmes.

Some mysteries relating to the prudence principle in the Fourth Directive and in German and British law

Abstract: Article 31 of the Fourth Directive, which specifies the general valuation principles to be applied in the preparation of financial statements, shows a difference in emphasis between the different language versions. Except for the English version of the Directive, all others emphasize prudence, as opposed to the other valuation principles required by the article. The earlier drafts of the Directive are examined in an attempt to trace the development of this difference between the English and the other language versions. It seems that the particular wording of Article 31 with its relatively greater weight on prudence probably results from UK influence, more specifically from SSAP 2. A possible solution is then suggested as to why this particular emphasis on prudence was not retained in the English version of the Directive. Further, it is noted that German law did not explicitly make prudence an overriding concept before the Fourth Directive and nor does the German implementation of Article 31.

The impact of information technology on corporate financial reporting: a contingency perspective

Abstract: Previous studies investigating IT impact on accounting suffer from a lack of theoretical guidance. An examination of the nature of information technology (IT), financial information and corporate financial reporting (CFR) indicates that the evaluation of IT impact on CFR requires a general, flexible and adaptive framework. Analogous to the contingency theory of organizations (CTO), this paper proposes such a framework. Its general assumptions are that the impact of IT on different aspects of CFR varies and the degree and pattern are contingent upon environmental, organizational, and managerial characteristics. Hypotheses have been developed to expand the framework. An evaluation of the framework against criticisms of CTO shows that it avoids several much criticized problems although care must be taken to ameliorate other pitfalls.

Identification of Rhodococcus equi using the polymerase chain reaction.

Abstract: K.S. BELL, J.C. PHILP, N. CHRISTOFI AND D.W.J. AW. 1996. Two regions in the gene coding for 16S rRNA in Rhodococcus equi were selected as species-specific primer sequences for the polymerase chain reaction (PCR). PCR using these primers was tested against 10 strains of R. equi (including the type strain) and gave positive results for all but was negative for all other tested species of Rhodococcus; representatives of the most closely related genera and a number of other bacterial species. This method could therefore be used to identify this species which can infect the lungs or other organs of horses, pigs, humans and other animals.

A note on the origins of the 'information society':

Abstract: The origins of the 'information society' are not well under stood. This paper assembles and evaluates the available data with a view to providing clarification of the provenance of a now widely-used and influential concept. Two main accounts have appeared. The first features Machlup's 1962 monograph The Production and Distribution of Knowledge in the United States. The second claims Japanese proven ance, citing articles in the broadcasting journal Hoso Asahi. Various equivocations and confusions are discussed, such as the tendency in both accounts to conflate the 'information society' with the concept of an 'information industry'. The second account quickly emerges as the stronger. However, it is argued (perhaps controversially) that ultimate credit for the invention of the 'information society' belongs not to the authors of the articles published in Hoso Asahi, but to that journal's editorial staff. While the paper is primarily inter pretative, some additional research data are cited.

In vitro function and durability assessment of a novel polyurethane heart valve prosthesis

Abstract: While flexible-leaflet, central-flow prosthetic heart valves promise relief from anticoagulation therapy, they continue to be restricted by inadequate durability In consequence, a novel trileaflet valve, made entirely from polyurethane, has been developed A batch of 6 consecutively manufactured polyurethane valves was subjected to hydrodynamic function and accelerated fatigue testing Computerized data acquisition and control systems have been introduced to improve valve testing methodologies In terms of hydrodynamic function, the polyurethane valve demonstrates transvalvular pressure gradients similar to those for a bioprosthetic valve (Carpentier-Edwards) and levels of retrograde flow significantly less than those for either the bioprosthetic valve or a bileaflet mechanical valve (St Jude Medical) The equivalent of 10 years of cycling without failure has been exceeded by all 6 polyurethane valves in accelerated fatigue tests with 2 valves remaining intact after 674 million cycles (equivalent to approximately 17 years) in continuing tests Highspeed photography revealed considerable differences in leaflet motion between valves cycled at accelerated and physiological rates

Fast Evolutionary Learning of Minimal Radial Basis Function Neural Networks Using a Genetic Algorithm

Abstract: A hybrid algorithm for determining Radial Basis Function (RBF) networks is proposed. Evolutionary learning is applied to the non-linear problem of determining RBF network architecture (number of hidden layer nodes, basis function centres and widths) in conjunction with supervised gradient-based learning for tuning connection weights. A direct encoding of RBF hidden layer node basis function centres and widths is employed. The genetic operators utilised are adapted from those used in recent work on evolution of fuzzy inference systems. A parsimonious allocation of training sets and training epochs to evaluation of candidate networks during evolution is proposed in order to accelerate the learning process.

Tabular techniques for generating Kronecker expansions

Abstract: Tabular techniques and algorithms for generating Kronecker expansions are presented. The Kronecker expansions, a subclass of mixed-polarity Reed-Muller expansions, can be generated from Boolean functions Kronecker expansions of different polarity. The techniques can be used for completely and incompletely specified Boolean functions. The algorithms were implemented in Pascal and fully tested. Examples are given to illustrate the procedures.

A new 2D FEM analysis of a disc machine with offset rotor

Abstract: The paper presents a new 2-D finite element method (2D FEM) analysis of a double-sided axial field, permanent magnet excited brushless DC motor. The rotor of the machine is free to move in a direction perpendicular to the axis of the shaft. Computed 2D results are compared with 3D FEM analysis and the new analysis method is shown to give close agreement.