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Showing papers by "University of Leeds published in 1996"


Journal ArticleDOI
TL;DR: The Sydney System for the classification of gastritis emphasized the importance of combining topographical, morphological, and etiological information into a schema that would help to generate reproducible and clinically useful diagnoses as discussed by the authors.
Abstract: The Sydney System for the classification of gastritis emphasized the importance of combining topographical, morphological, and etiological information into a schema that would help to generate reproducible and clinically useful diagnoses. To reappraise the Sydney System 4 years after its introduction, a group of gastrointestinal pathologists from various parts of the world met in Houston, Texas, in September 1994. The aims of the workshop were (a) to establish an agreed terminology of gastritis; (b) to identify, define, and attempt to resolve some of the problems associated with the Sydney System. This article introduces the Sydney System as it was revised at the Houston Gastritis Workshop and represents the consensus of the participants. Overall, the principles and grading of the Sydney System were only slightly modified, the grading being aided by the provision of a visual analogue scale. The terminology of the final classification has been improved to emphasize the distinction between the atrophic and nonatrophic stomach; the names used for each entity were selected because they are generally acceptable to both pathologists and gastroenterologists. In addition to the main categories and atrophic and nonatrophic gastritis, the special or distinctive forms are described and their respective diagnostic criteria are provided. The article includes practical guidelines for optimal biopsy sampling of the stomach, for the use of the visual analogue scales for grading the histopathologic features, and for the formulation of a comprehensive standardized diagnosis. A glossary of gastritis-related terms as used in this article is provided.

4,511 citations


Journal ArticleDOI
01 Oct 1996-Talanta
TL;DR: A new suite of 10 programs concerned with equilibrium constants and solution equilibria is described, which includes data preparation programs, pretreatment programs, equilibrium constant refinement and post-run analysis.

2,779 citations


Journal ArticleDOI
24 May 1996-Science
TL;DR: Data on rocks from Spitsbergen and the equatorial sections of Italy and Slovenia indicate that the world's oceans became anoxic at both low and high paleolatitudes in the Late Permian, which may have been responsible for the mass extinction at this time.
Abstract: Data on rocks from Spitsbergen and the equatorial sections of Italy and Slovenia indicate that the world's oceans became anoxic at both low and high paleolatitudes in the Late Permian. Such conditions may have been responsible for the mass extinction at this time. This event affected a wide range of shelf depths and extended into shallow water well above the storm wave base.

966 citations


Journal ArticleDOI
16 Aug 1996-Science
TL;DR: The cloned AUX1 gene can restore the auxin-responsiveness of transgenic aux1 roots and suggest thatAUX1 mediates the transport of an amino acid-like signaling molecule that regulates root gravitropic curvature.
Abstract: The plant hormone auxin regulates various developmental processes including root formation, vascular development, and gravitropism. Mutations within the AUX1 gene confer an auxin-resistant root growth phenotype and abolish root gravitropic curvature. Polypeptide sequence similarity to amino acid permeases suggests that AUX1 mediates the transport of an amino acid-like signaling molecule. Indole-3-acetic acid, the major form of auxin in higher plants, is structurally similar to tryptophan and is a likely substrate for the AUX1 gene product. The cloned AUX1 gene can restore the auxin-responsiveness of transgenic aux1 roots. Spatially, AUX1 is expressed in root apical tissues that regulate root gravitropic curvature.

901 citations


Journal ArticleDOI
TL;DR: The Cognitive Style Index (CSI) as discussed by the authors is a psychome-trically sound instrument suitable for application in large-scale organizational studies, and through its development, to confirm empirically the generic intuition-analysis dimension of cognitive style.
Abstract: Almost 1000 adults participated in the development of the Cognitive Style Index (CSI), a new measure designed specifically for use with managerial and professional groups. the objectives of the study were, first, to produce a psychome-trically sound instrument suitable for application in large-scale organizational studies, and second, through its development, to confirm empirically the generic intuition-analysis dimension of cognitive style. Findings suggest that each objective was largely fulfilled. At a time when there is a burgeoning interest in intuition as a basis for decision making and problem solving in organizations, the CSI would appear to be a notable addition to the small collection of measures appropriate for survey research.

852 citations


Journal ArticleDOI
TL;DR: A hybrid method of short-term traffic forecasting is introduced; the KARIMA method, which uses a Kohonen self-organizing map as an initial classifier; each class has an individually tuned ARIMA model associated with it.
Abstract: A hybrid method of short-term traffic forecasting is introduced; the KARIMA method. The technique uses a Kohonen self-organizing map as an initial classifier; each class has an individually tuned ARIMA model associated with it. Using a Kohonen map which is hexagonal in layout eases the problem of defining the classes. The explicit separation of the tasks of classification and functional approximation greatly improves forecasting performance compared to either a single ARIMA model or a backpropagation neural network. The model is demonstrated by producing forecasts of traffic flow, at horizons of half an hour and an hour, for a French motorway. Performance is similar to that exhibited by other layered models, but the number of classes needed is much smaller (typically between two and four). Because the number of classes is small, it is concluded that the algorithm could be easily retrained in order to track long-term changes in traffic flow and should also prove to be readily transferrable.

700 citations


Journal ArticleDOI
TL;DR: A software package is described that operates on small molecules observed in the PDB collection of protein structures that converts three-dimensional coordinates of small molecules to molecular descriptor strings that encode them uniquely in order to enable small-molecule recognition, despite high variability in atom and molecule nomenclature.
Abstract: A software package is described that operates on small molecules observed in the PDB collection of protein structures. Molecular topology files for many molecular modeling programs can be generated automatically. The three-dimensional coordinates of small molecules can be converted to molecular descriptor strings that encode them uniquely in order to enable small-molecule recognition, despite high variability in atom and molecule nomenclature. From this descriptor a plausible 3D structure can be regenerated using energy minimisation. Alternatively, an ensemble of structures can be generated using a distance-geometry-based algorithm.

607 citations


Journal ArticleDOI
TL;DR: In this paper, the reduced kinetic, C1, scheme of Mauss and Peters is employed for a range of equivalence ratios under atmospheric conditions, with flame propagation at constant pressure.

580 citations


Journal ArticleDOI
TL;DR: Root growth is enhanced under nitrogen and phosphorus deficiencies, but not under deficiencies of nutrients of low mobility in the phloem, such as calcium and boron, as demonstrated in impaired export under magnesium, potassium, or zinc deficiencies.
Abstract: Mineral nutrients taken up by the roots are, as a rule, transported in the xylem to the shoot, and photoassimilates transported in the phloem to the roots. According to the Thornley model of photosynthate partitioning, nutrient deficiencies should favour photosynthate partitioning to the roots. Examples are cited to show that this preferential partitioning is dependent on phloem mobility and hence on nutrient cycling from shoot to roots. Thus, root growth is enhanced under nitrogen and phosphorus deficiencies, but not under deficiencies of nutrients of low mobility in the phloem, such as calcium and boron. Enhanced root growth under nutrient deficiency relies on the import of both photosynthates and mineral nutrients. Cycling of mineral nutrients serves a number of other functions. These include the root supply of nutrients assimilated in the shoot (nitrate and sulphate reduction), maintenance of cation-anion balance in the shoot, providing an additional driving force for solute volume flow in the phloem and xylem, and acting as a shoot signal to convey nutrient demand to the root. Cycling of certain mineral nutrients through source leaves has a considerable impact on photosynthate export as demonstrated in impaired export under magnesium, potassium, or zinc deficiencies. Mineral nutrient deficiency can, therefore, affect photosynthate partitioning either directly via phloem loading and transport or indirectly by depressing sink demand.

573 citations


Journal ArticleDOI
TL;DR: In this paper, the slow pyrolysis of biomass in the form of pine wood was investigated in a static batch reactor at pyrolysisation temperatures from 300 to 720°C and heating rates from 5 to 80 K min−1.

549 citations


Journal ArticleDOI
J.G. Cabrera1
TL;DR: In this article, the effects of corrosion rate on cracking and bond strength loss were investigated using laboratory data to investigate the influence of fly ash on the rate of reinforcement corrosion, and the laboratory data was used to develop numerical models to predict: 1. (a) rate of corrosion from the width and intensity of cracking 2. (b) bond stress from corrosion rate, and 3. (c) serviceability loss from corrosion rates.
Abstract: Steel corrosion in concrete leads to cracking, reduction of bond strength, reduction of steel cross section and loss of serviceability. Reinforced concrete undergoing corrosion does not only give the appearance of poor performance, but can in extreme cases, lose its structural integrity. Numerical relations to assess the loss of serviceability due to steel reinforcement corrosion are scanty, thus data to relate the rate of corrosion to cracking and loss of bond strength are necessary. This paper uses laboratory data to investigate the effects of corrosion rate on cracking and bond strength loss. It also examines the influence of fly ash on the rate of reinforcement corrosion. The laboratory data is used to develop numerical models to predict: 1. (a) rate of corrosion from the width and intensity of cracking 2. (b) bond stress from corrosion rate, and 3. (c) serviceability loss from corrosion rate.

Journal ArticleDOI
TL;DR: A photochemical trajectory model is used to describe the ozone production from the oxidation of methane and 95 other hydrocarbons in the presence of sunlight and NOx in air parcels advected across north west Europe towards the British Isles.

Journal ArticleDOI
TL;DR: Ghemawat et al., 1986; Glaister and Buckley, 1994; Hergert and Morris, 1988 as discussed by the authors have shown that firms in developed market economies are increasingly willing to participate in cooperative ventures often with their direct competitors, and that firms themselves have voluntarily adopted alliances as a strategic option in response to changing market conditions rather than in compliance to exogenously enforced rules.
Abstract: Over the past two decades the incidence of strategic alliance formation has accelerated (Ghemawat et al., 1986; Glaister and Buckley, 1994; Hergert and Morris, 1988). Traditionally strategic alliances were used by multinational companies as a vehicle to enter the markets of developing countries that enforced restrictive conditions on foreign investment (Hood and Young, 1979). More recently firms in developed market economies have been increasingly willing to participate in cooperative ventures often with their direct competitors. The momentum for this has come from the firms themselves, which have voluntarily adopted alliances as a strategic option in response to changing market conditions rather than in compliance to exogenously enforced rules (Harrigan, 1988; Vonortas, 1990).

Journal ArticleDOI
01 Jul 1996-Fuel
TL;DR: In this article, a mixture of mixed wood waste was pyrolysed in a fluidized bed reactor at 400, 450, 500 and 550°C, and the results showed that only low quantities of hydrocarbons were present and the oxygenated and polar fractions were dominant.

Journal ArticleDOI
TL;DR: Six principles of emancipatory research are identified and an attempt made to balance the twin requirements of political action and academic rigour are made.
Abstract: Important methodological questions are raised by the act of researching disablement. Disability research has attracted much methodological criticism from disabled people who argue that it has taken place within an oppressive theoretical paradigm and within an oppressive set of social relations. These issues are of heightened significance for non-disabled researchers and bear many similarities to those faced by researchers investigating barriers to the social inclusion of women, Black and ‘Third World’ peoples. Such challenges have led to the development of an ‘emancipatory’ research paradigm. Six principles of emancipatory research are identified and the authors’ own research projects are critically examined within this framework. A number of contradictions are identified and an attempt made to balance the twin requirements of political action and academic rigour.

Journal ArticleDOI
26 Sep 1996-Nature
TL;DR: In this paper, the authors reported two dramatic outbursts of TeV photons from the active galaxy Markarian 421 (Mrk421) in which the flux increased above the relatively quiescent value by more than a factor of 50, briefly making Mrk421 the brightest TeV source in the sky.
Abstract: DISCRETE astronomical sources of photons in the TeV energy range are believed to be associated with regions in the relativistic outflow of particles and radiation from compact objects, such as neutron stars and black holes. The flux from such sources, together with the timescales on which they vary, can provide strong constraints on the emission mechanisms. Here we report the observation of two dramatic outbursts of TeV photons from the active galaxy Markarian 421 (Mrk421). In the first outburst, which had a doubling time of about one hour, the flux increased above the relatively quiescent value by more than a factor of 50, briefly making Mrk421 the brightest TeV source in the sky. In the second outburst, which lasted approximately 30 minutes, the flux increased by a factor of 20–25. These data suggest that the emission region is extremely small—perhaps even smaller than our Solar System. This could prove challenging for current theoretical models of such emissions.

Journal ArticleDOI
20 Dec 1996-Science
TL;DR: The crystal structure of an unmodified hammerhead RNA in the absence of divalentMetal ions has been solved, and it was shown that this ribozyme can cleave itself in the crystal when divalent metal ions are added.
Abstract: The crystal structure of an unmodified hammerhead RNA in the absence of divalent metal ions has been solved, and it was shown that this ribozyme can cleave itself in the crystal when divalent metal ions are added. This biologically active RNA fold is the same as that found previously for two modified hammerhead ribozymes. Addition of divalent cations at low pH makes it possible to capture the uncleaved RNA in metal-bound form. A conformational intermediate, having an additional Mg(II) bound to the cleavage-site phosphate, was captured by freeze-trapping the RNA at an active pH prior to cleavage. The most significant conformational changes were limited to the active site of the ribozyme, and the changed conformation requires only small additional movements to reach a proposed transition-state.

Book ChapterDOI
01 Jan 1996
TL;DR: Hemadsorption is a fast and convenient method of detecting orthomyxoviruses and non respiratory syncytial virus paramyxovirus in cell cultures in which the cytopathic effect vary from obvious to minimal.
Abstract: Publisher Summary This chapter outlines the two most commonly used methods of virus isolation—namely, tissue cultures and embryonated eggs. The chapter describes the methodology involved for the predominant virus groups that cover the majority of viruses encountered in the clinical situation. The chapter also describes selected methods of virus assay and the calculation of virus titers. Nasal swabs are the easiest specimens to collect for respiratory viruses and are also the best specimens for the majority of the respiratory viruses described in the chapter. Hemadsorption is a fast and convenient method of detecting orthomyxoviruses and non respiratory syncytial virus paramyxoviruses in cell cultures in which the cytopathic effect vary from obvious to minimal.

Journal ArticleDOI
TL;DR: The detection of gamma rays of energy greater than 300 GeV from the BL Lacertae object Mrk 501 demonstrates that extragalactic TeV emission is not unique to Mrk 421.
Abstract: The detection of gamma rays of energy greater than 300 GeV from the BL Lacertae object Mrk 501 demonstrates that extragalactic TeV emission is not unique to Mrk 421. During 66 hr of observations between 1995 March and July we measured an average flux of 8.1 ± 1.4 × 10-12 cm-2 s-1 above 300 GeV, a flux that is only 20% of the average Mrk 421 flux. The new gamma-ray source has not been reported by the Compton Gamma Ray Observatory as an emitter of gamma rays at lower energies. There is evidence for variability on timescales of days.

Journal ArticleDOI
01 Jun 1996
TL;DR: Different mechanistic models for plant-specific inactivation mechanisms and their relationship with repeat-specific silencing phenomena in other species are discussed.
Abstract: Homology-dependent gene silencing phenomena in plants have received considerable attention, especially when it was discovered that the presence of homologous sequences not only affected the stability of transgene expression, but that the activity of endogenous genes could be altered after insertion of homologous transgenes into the genome. Homology-mediated inactivation most likely comprises at least two different molecular mechanisms that induce gene silencing at the transcriptional or posttranscriptional level, respectively. In this review we discuss different mechanistic models for plant-specific inactivation mechanisms and their relationship with repeat-specific silencing phenomena in other species.

Journal ArticleDOI
TL;DR: The results suggest that the short version of the Inventory of Interpersonal Problems sacrifices little compared to the original 127-item version in terms of its psychometric properties while being considerably more convenient for routine clinical practice.
Abstract: Three related studies are presented focusing on the development of a short 32-item version of the Inventory of Interpersonal Problems (IIP). Study 1 presents the procedures for item selection on the IIP short version; Study 2 presents a confirmatory analysis of the IIP short version on an independent sample; and Study 3 provides preliminary normative (general population and out-patient) data and additional evidence of the psychometric properties of the IIP short form. The results suggest that the short version sacrifices little compared to the original 127-item version in terms of its psychometric properties while being considerably more convenient for routine clinical practice.

Journal ArticleDOI
H Forster1, J Fisher1
01 Jun 1996
TL;DR: Following the re-application of load, after short periods of load removal, friction was also found to drop sharply, and synovial fluid significantly reduced friction compared to Ringer's solution, which was not as effective for the cartilage-metal contacts.
Abstract: Friction of cartilage on metal, metal on cartilage and cartilage on cartilage contact configurations, within a mixed lubrication regime, was measured using synovial fluid, Ringer's solution or with no lubricant present. The main test variable was the period of stationary loading which ranged from 5 s to 45 min, prior to sliding and consequently measuring friction. The coefficient of friction rose gradually with increasing stationary loading time, up to a value of approximately 0.3 at 45 min for all the contact configurations. Following the re-application of load, after short periods of load removal, friction was also found to drop sharply. The flow of liquid in the biphasic cartilage and load carriage by the fluid phase was highlighted as being an important factor in reducing friction within the mixed or boundary lubrication regime. Movement of the contact zone over the cartilage counterface ensured very low friction as the slider moved over fully hydrated cartilage. For the cartilage--cartilage contacts synovial fluid significantly reduced friction compared to Ringer's solution. This was attributed to an effective boundary lubrication action, which was not as effective for the cartilage--metal contacts.

Journal ArticleDOI
TL;DR: Analysis of the cell killing curves and results suggest that cationic photosensitizers may have a broader application in the photoinactivation of bacterial cells than the anionic or neutral photosensitiveers commonly used in photodynamic therapy.
Abstract: The photosensitization of microorganisms is potentially useful for sterilization and for the treatment of certain bacterial diseases. Until now, any broad spectrum approach has been inhibited because, although Gram-positive bacteria can be photoinactivated by a range of photosensitizers, Gram-negative bacteria have not usually been susceptible to photosensitized destruction. In the present work, it has been shown that the Gram-negative bacteria Escherichia coli and Pseudomonas aeruginosa, as well as the Gram-positive bacterium Enterococcus seriolicida, can be photoinactivated when illuminated in the presence of a cationic water-soluble zinc pyridinium phthalocyanine (PPC). The degree of photoinactivation is dependent on both the concentration of PPC and the illumination time. In contrast, the three bacteria are not photoinactivated by illumination in the presence of a neutral tetra-diethanolamine phthalocyanine (TDEPC) or negatively charged tetra-sulphonated phthalocyanine (TSPC). Uptake studies have revealed that the lack of activity of TSPC is due to the fact that it has very little affinity for any of the organisms. However, the issue appears to be more complex than simply the gross levels of cellular uptake, since TDEPC and PPC are both taken up by the organisms but only PPC shows activity. This indicates that the localization and subcellular distribution of the phthalocyanines may be a crucial factor in determining their cell killing potential. Further analysis of the uptake data has revealed a cell-bound photosensitizer fraction, which remains tightly associated after several washings, and another weakly bound fraction, which is removed by successive washings. Analysis of the cell killing curves, carried out after successive washings of E. coli exposed to PPC, has revealed that it is the tightly associated fraction that is involved in the photosensitization. Taken together with other data, these results suggest that cationic photosensitizers may have a broader application in the photoinactivation of bacterial cells than the anionic or neutral photosensitizers commonly used in photodynamic therapy.

Proceedings ArticleDOI
14 Oct 1996
TL;DR: A 3D deformable Point Distribution Model of the human hand is constructed, capturing training data semi-automatically from volume images via a physically-based model and how to improve on a weighted least-squares pose parameter approximation at little computational cost is shown.
Abstract: In this paper we first describe how we have constructed a 3D deformable Point Distribution Model of the human hand, capturing training data semi-automatically from volume images via a physically-based model. We then show how we have attempted to use this model in tracking an unmarked hand moving with 6 degrees of freedom (plus deformation) in real time using a single video camera. In the course of this we show how to improve on a weighted least-squares pose parameter approximation at little computational cost. We note the successes and shortcomings of our system and discuss how it might be improved.

Journal ArticleDOI
TL;DR: In this article, it was shown that although technical trading rules examined do have predictive ability in terms of UK data, their use would not allow investors to make excess returns in the presence of costly trading.
Abstract: Brock et al. (1992) found technical trading rules to have predictive ability with regards to the Dow Jones Index. The current paper considers whether this result can be replicated on UK data. The paper also considers whether investors could earn excess returns from technical analysis in a costly trading environment. The paper concludes that although the technical trading rules examined do have predictive ability in terms of UK data, their use would not allow investors to make excess returns in the presence of costly trading.

Journal ArticleDOI
TL;DR: High-grade dysplasia in columnar-lined oesophagus can be eradicated by endoscopic photodynamic therapy with endogenously generated PpIX, and remaining non-dysplastic Barrett's epithelium will require surveillance, but overall the technique has interrupted or delayed the worsening of the Dysplasia through to carcinoma.

Journal ArticleDOI
TL;DR: The findings indicate that antioxidant defenses could be considerably compromised in these very sick patients and the potential of these species to damage DNA and lipid membranes could be increased and compromise recovery.

Journal ArticleDOI
TL;DR: This article examined the effect of matching and mismatching learning style and learning activity on learning achievement and the possibility of creating a match by promoting learner adaptability or modifying the trainer's training style.
Abstract: This review paper examines the effect of matching and mismatching learning style and learning activity and matching and mismatching trainer and trainee learning style on learning achievement. It also explores the possibility of creating a match by promoting learner adaptability or modifying the trainer's training style. The implications of this discussion for training and development are considered.

Journal ArticleDOI
TL;DR: Interestingly, the most effective inhibitor of the binding of the monoclonal antibodies MAC207, JIM4 and JIM13 to exudate gum antigens was an acidic trisaccharide, isolated from a partial acid hydrolysate of gum karaya which has the structure: GlcA beta(1-->3) GalA alpha(1)--Rha, determined by a combination of FAB-MS, GC-MS and NMR spectroscopy.
Abstract: Arabinogalactan-proteins (AGPs) are a diverse class of plant cell surface proteoglycans implicated in a range of fundamental processes associated with plant cell development. Anti-AGP monoclonal antibodies have been used extensively for the investigation of the developmental regulation of AGPs although virtually nothing is known about the structure of the carbohydrate epitopes recognised by these antibodies. In this report, a series of methyl glycosides of monosaccharides and a range of oligosaccharides that are elements of the carbohydrate component of AGPs have been investigated for recognition by previously derived anti-AGP monoclonal antibodies. No clear evidence was obtained for the involvement of terminal arabinofuranosides, nor of the galactan backbone, in the recognition of the glycan structure of AGPs by any of the antibodies used in this study. Interestingly, the most effective inhibitor of the binding of the monoclonal antibodies MAC207, JIM4 and JIM13 to exudate gum antigens was an acidic trisaccharide, isolated from a partial acid hydrolysate of gum karaya which has the structure: GlcA beta(1-->3) GalA alpha(1-->2)Rha, determined by a combination of FAB-MS, GC-MS and NMR spectroscopy.

Journal ArticleDOI
TL;DR: In this paper, a model for homogeneous-heterogeneous reactions in boundary-layer flow is presented in which the homogeneous reaction is represented by cubic autocatalysis and the heterogeneous reaction by a first-order process.