Showing papers by "University of Portsmouth published in 1998"

Exponential potentials and cosmological scaling solutions

Abstract: We present a phase-plane analysis of cosmologies containing a baryotropic fluid with an equation of state ${p}_{\ensuremath{\gamma}}=(\ensuremath{\gamma}\ensuremath{-}1){\ensuremath{\rho}}_{\ensuremath{\gamma}},$ plus a scalar field $\ensuremath{\varphi}$ with an exponential potential $V\ensuremath{\propto}\mathrm{exp}(\ensuremath{-}\ensuremath{\lambda}\ensuremath{\kappa}\ensuremath{\varphi})$ where ${\ensuremath{\kappa}}^{2}=8\ensuremath{\pi}G$. In addition to the well-known inflationary solutions for ${\ensuremath{\lambda}}^{2}l2$, there exist scaling solutions when ${\ensuremath{\lambda}}^{2}g3\ensuremath{\gamma}$ in which the scalar field energy density tracks that of the baryotropic fluid (which for example might be radiation or dust). We show that the scaling solutions are the unique late-time attractors whenever they exist. The fluid-dominated solutions, where $V(\ensuremath{\varphi})/{\ensuremath{\rho}}_{\ensuremath{\gamma}}\ensuremath{\rightarrow}0$ at late times, are always unstable (except for the cosmological constant case $\ensuremath{\gamma}=0)$. The relative energy density of the fluid and scalar field depends on the steepness of the exponential potential, which is constrained by nucleosynthesis to ${\ensuremath{\lambda}}^{2}g20$. We show that standard inflation models are unable to solve this ``relic density'' problem.

Electrodes based on Magnéli phase titanium oxides: the properties and applications of Ebonex® materials

Abstract: Magneli phases are a range of substoichiometric oxides of titanium of the general formula TinO2n−1, (where n is between 4 and 10) produced from high temperature reduction of titania in a hydrogen atmosphere These blue/black ceramic materials exhibit a conductivity comparable to that of graphite and can be produced in a number of forms, such as tiles, rods, fibres, foams and powders While these materials have been studied for many years, they have only recently received interest for use as ceramic electrode materials, commercially termed ‘Ebonex®’, and are beginning to challenge precious metal coated anodes for some applications in aggressive electrolytes Other uses for these materials include electrowinning, electroplating, battery materials, impressed current cathodic protection anodes, electrochemical soil remediation, oxidation of organic wastes, flexible cable materials and electrophoresis The scope of this review considers the structure and properties of Magneli phase titanium oxide materials, together with their electrochemical behaviour and applications

DNA methylation models histone acetylation

Abstract: One of the main determinants of chromatin structure is histone acetylation1. Local chromosomal acetylation can be regulated dynamically, both through the involvement of transactivating factors with intrinsic histone acetylase activity, and through the recruitment of deacetylase complexes that repress gene expression2. Histone acetylation status is transiently modified from one state to another in response to physiological changes operating in the cell. It is not yet known, however, how the basic histone acetylation profiles on tissue-specific and housekeeping gene sequences are established during normal development. Here we show that DNA methylation takes part in this process by inducing decreased levels of chromatin acetylation.

Early Silurian sea-level changes

Abstract: Global sea-level fluctuated markedly during the early Silurian, probably as a result of the waxing and waning of ice-sheets in the South American portion of Gondwana. The highest sea-levels of the Silurian are recorded by the Telychian upper crispus–lower griestoniensis and spiralis–lower lapworthi biozones. Other highstands occurred in the early Aeronian, during the convolutus Zone (mid Aeronian), guerichi Zone and late turriculatus Zone (early Telychian), and early Sheinwoodian. Low sea-levels characterized much of the argenteus and sedgwickii zones (Aeronian), the utilis Subzone (late guerichi–early turriculatus zones, early Telychian), the late Telychian (commencing in the mid lapworthi Zone) and, after a period of apparently only small amplitude sea-level fluctuations in the late Sheinwoodian and earliest Homerian, the mid–late Homerian, in particular the early nassa Zone. Facies (and faunal) changes in the Lower Silurian do not support the P and S model of Jeppsson and others, but are consistent with the sea-level changes proposed herein. Mid Telychian marine red beds appear to have been deposited during a minor sea-level fall immediately after a period of very high sea-levels, rather than during a transgressive episode as previously suggested. Comparison of the sea-level curve presented herein with those constructed in the past is hampered by the lack of precision currently possible in the correlation of early Silurian deep water (graptolitic) and shallow water (shelly) sequences. Improving the precision of this correlation should be a priority for future research.

Police Officers' Perceptions of Eyewitness Performance in Forensic Investigations

Abstract: Few contemporary data support the assertion that eyewitnesses are important in police investigations. In the present study, 159 UK police officers were surveyed regarding their perceptions of eyewitnesses and eyewitness performance. The respondents indicated that eyewitnesses usually provide the central leads in criminal investigations; however, the police officers also believed that eyewitnesses rarely provide sufficient information, especially descriptive details as opposed to action details. Nevertheless, the officers believed that eyewitnesses are rarely incorrect. A sizable minority reported that witnesses rarely come forward to the police and that those who do are often reluctant to testify in court. Many officers indicated that they do not have enough time to conduct good eyewitness interviews.

Market Orientation and Performance: Do the Findings Established in Large Firms Hold in the Small Business Sector?

Abstract: This study examined whether the market orientation-performance link established in large firm studies hold in the small business sector and tested for the possible effects of market growth, competitive intensity, market and technological turbulence on any identified relationships. Specific performance measures used were new product success, sales growth and ROI. Based on constructs of the aforementioned variables, a research instrument was developed for the study and data were gathered through a self-administered mail survey among a U.K. sample of small firms. Our findings suggest that there is a positive impact of market orientation upon small business performance. In addition, evidence is provided on the mixed effects of the competitive environment on the market orientation-performance relationship. To conclude, we discuss implications of the findings for small business managers as well as study limitations and future research directions.

The theory-practice gap in nursing: from research-based practice to practitioner-based research.

Abstract: The aim of nursing research is generally agreed to be the generation of knowledge, and whilst this is a relevant aim in theory-based disciplines such as sociology, the primary concern of nursing is with practice. Using examples drawn mainly from the field of mental health, it will be argued in this paper that the application of generalizable, research-based knowledge to individual, unique, person-centred practice, the so-called 'research-based practice' advocated by the Department of Health, is one of the main causes of the theory-practice gap. It will be further suggested that nursing requires a paradigm of clinical research which focuses on the individual therapeutic encounter in order to complement the existing sociological paradigm of theoretical research which is best suited to the generation of generalizable knowledge and theory. The paper will conclude by suggesting that such a clinically based research paradigm must not only focus on the individual nurse-patient relationship, but that it must be carried out by the nurse herself. Clinical research, if it is to make a difference to practice, must therefore be practitioner-based research.

Cryopreservation of eukaryotic algae – a review of methodologies

Abstract: Since pioneering work in the early 1960s, there has been growing interest and numerous experimental investigations into the cryopreservation of algal material. Mostly, these studies relate to the requirement for long term preservation and storage of algal material contained in culture collections or used in the seaweed mariculture industry. The present review deals with techniques used in the cryopreservation of biological samples and their application to both micro- and macroalgae. Methods for the prevention of cell damage and freezing injury during the cooling and low-temperature storage of algal material are discussed with reference to the effect on viability of such variables as cooling rates, final temperatures attained, the use of various types and concentrations of cryoprotectants, thawing rates, and storage times and temperatures. Some consideration is also given to the various methods used for increasing cell viability, including the induction of freezing tolerance. Cryopreservation protocols employed by numerous workers in this field are detailed, and concluding remarks are made on those techniques and conditions providing optimum viability of cryopreserved algae.

The rotating cylinder electrode: its continued development and application

Abstract: The application of rotating cylinder electrodes (RCEs) in electrochemistry has been reviewed for the period 1982–1995. Among the applications highlighted are the novel design of cell geometries and reactors for a range of electrochemical processes, voltammetry and analysis, electrodeposition and corrosion. This range amply indicates the widespread acceptance of the RCE for studies in a number of interdisciplinary fields.

Determinants of Grain Production and Technical Efficiency in China

Abstract: A stochastic frontier production function is used to investigate the prospect to bring China's grain production and productivity to higher levels using a panel data set on 30 provinces from 1987–92. Given an irreversible trend of declining agricultural land, the only feasible way to raise total grain output is to increase land productivity if China does not want to rely on large-scale imports to feed her huge and still growing population. Considerable regional differences in grain yields suggest that there is still a vast potential for raising grain output. The short term solution is to use more land-augmenting inputs such as fertilisers and irrigation in the medium and low yield regions. However, the law of diminishing returns is in operation as more physical inputs are applied to shrinking land. Growth in grain output in the long term must rely on improvements in technical efficiency.

Market orientation and performance in the biotechnology industry: An exploratory empirical analysis

Abstract: The purpose ofthis study was to conduct an exploratory investigation into the link between market orientation and business performance in the biotechnology sector Based on the nature and character of the biotechnology industry, a multi-faceted scale of market orientation was derived from a preuiously tested and refined measure of the construct Data were generated from 62 biotechnolog firms and a variety of market orientation-performance relationships were investigated, alongside other potential effects on the different dimensions of business performance The findings indicate that market orientation is positively and signficanttly associated with three of the four performance measures examined Implications of our findings for biotechnology industry managers are discussed and limitations of the study as well as future research directions are addressed

Goal programming, compromise programming and reference point method formulations : linkages and utility interpretations

Abstract: This paper looks at connections between the multi-criteria techniques of goal programming, compromise programming, and the reference point method. The utility function structure of each method is examined and interpretation of the techniques in terms of pareto efficiency and the equilibrated nature of the solution is given. Means of ensuring pareto efficiency whilst maintaining as much as possible the equilibrated character are given for a certain class of model. Methods for ensuring conceptual correctness and computational accuracy by reducing reference point models to equivalent goal programmes are given. The findings are illustrated by means of an example.

Understanding Overseas Students’ Concerns and Problems

Abstract: A greater awareness of overseas students’ problems and a commitment to meeting their needs are critical for academic institutions to win the competition for overseas students. This study has empirically explored the perceptions of overseas students of the major problems encountered during their study. The interrelationships between each of the problems have also been examined. The data used for this study were drawn from the overseas students’ survey conducted at a university in the UK. The results yield some valuable insights for academic institutions in counselling and helping their overseas students and in improving the quality of services.

Audit market competition: auditor changes and the impact of tendering

Abstract: Increased competition within the external audit market and the recent phenomenon of audit tendering has renewed interest in the factors influencing auditor changes. In this paper, a questionnaire instrument is used to elicit perceptions of the factors which influence auditor–client realignments in this new environment and to indicate the relative influence of economic and behavioural factors. Positive, statistically significant associations were found between unsolicited approaches and the consideration of either a change in auditor or the conduct of a competitive tender. Fees are both the most frequently cited reason for considering auditor change and the most frequently cited factor influencing the selection of a new auditor. The chemistry of the relationship with senior audit firm personnel was ranked as more important than service issues in new auditor selection. Several significant associations between the reasons for change and both company size and type of change are identified. In particular, smaller companies, and companies changing from a non-Big Six firm, were more likely to change due to the need for a wider range of services and the influence of third parties. Findings indicated that 55% of auditor changes were effected by means of a tender, with the incumbent auditor having only an 18% chance of retaining the client. The various stages of the tender process appear to be dominated by the finance director, with audit committees having a restricted role. Tenders resulted in significant fee reductions in the year of change.

Introduced brown algae in the North East Atlantic, with particular respect toUndaria pinnatifida (Harvey) suringar

Abstract: The recent introduction of the macroalgaUndaria pinnatifida (Harvey) Suringar into the North Atlantic is the latest of a large number of introductions, which have occurred over many years. Some have been deliberate introductions for mariculture or research, while most have been accidental, via vectors such as shipping and shellfish imports. Not all newly recorded species are introductions; some are thought to be merely extensions of distribution, e.g.Laminaria ochroleuca, while others may have been overlooked previously, e.g.Scytosiphon dotyi. Subsequent to its accidental introduction into the waters around the Mediterranean French coast at Sete, most likely with imported oysters,Undaria was deliberately introduced into the North Atlantic, to Brittany, in 1983 by IFREMER for commercial exploitation.Undaria has since spread from the original sites in Brittany, and is now established at several sites on the south coast of England. This paper discusses the introduced brown algae in the North Atlantic and outlines the establishment ofUndaria in the UK.

From introduced species to invader: what determines variation in the success of Codium fragile ssp. tomentosoides (Chlorophyta) in the North Atlantic Ocean?

Abstract: The green algaCodium fragile ssp.tomentosoides (Chlorophyta) has been introduced accidentally and successfully from Japan to many shores of the northern and southern hemispheres, including those of the Northeast and Northwest Atlantic Ocean. On most European coasts,Codium occurs regularly but at low abundances in the intertidal zone and is absent from subtidal habitats. In contrast,Codium is extremely abundant in subtidal kelp beds in the Northwest Atlantic Ocean where it often reaches nuisance proportions. This differential success cannot be accounted for by either the properties of the invader or by physico-chemical differences between invaded coasts. A theoretical comparison between two regions on opposite sides of the Atlantic Ocean, i.e. Eastern Nova Scotia, Canada, and south central Britain, illustrates how the resident benthic community may determine the difference in relative abundance ofCodium in subtidal habitats between northeast America and Europe. In this review, low floral species diversity, biological disturbance and facilitation by a previous species invasion are suggested as potential factors for the establishment, success and abundance ofCodium in the Northwest Atlantic Ocean, but these require testing in field experiments.

Improvements in product quality in tandem cold rolling using robust multivariable control

Abstract: This paper considers the gauge control problem in tandem cold rolling. A robust multivariable solution is proposed via the H/sup /spl infin// loop shaping method of McFarlane and Glover (1990), which combined with a gain scheduling technique enables the control of the mill from thread speed to full speed. Improvement over a representative industrial controller is observed from nonlinear simulation results.

‘We have to put up with it — don’t we?’ The experience of being the registered nurse on duty, managing a violent incident involving an elderly patient: a phenomenological study

Abstract: The incidence of violence directed towards nurses is well known. However, despite guidelines and training aimed at preventing or minimizing these incidents, recent reports indicate an increase in their occurrence. This phenomenological study investigated the experiences of five registered nurses who had to manage a violent incident involving an elderly patient. The purpose of this was to discover what these nurses 'know' about the structure of such an experience and, through the use of Colaizzi's method of data analysis, present this knowledge in the form of an exhaustive description of the experience. Taped interviews were used to collect the data. The analytical process revealed that the experience is structured around five themes: professional competence, nursing identity, powerlessness and oppression, loss (neglected and deserted) and strategies for survival. The discussion analyses these themes and the relationships between them, highlighting the issues of nurse autonomy and exercising accountability. The implications for nursing practice, education and research include recognition of nurses as a professional group to enable autonomous practice, the ways in which nurses' perceptions of nursing knowledge may affect their educative role and the need to extend this study further to provide answers to the questions raised therein.

A Case Study for Comparing Two Service Quality Measurement Approaches in the Context of Teaching in Higher Education

Abstract: This study examines two alternative methods (SERVQUAL and SERVPREF), which are currently being used for measuring perceived service quality, with respect to their ability to explain variation in customers’ satisfaction. Following a theoretical discussion, a case study was conducted in the context of teaching in higher education. The statistical result shows that SERVPREF represents a better approach than SERVQUAL in explaining the variation of students’ satisfaction with overall quality of course delivery.

Suppression of fecundity of the root-knot nematode, Meloidogyne javanica, in monoxenic cultures of Arabidopsis thaliana treated with an alkaline extract of Ascophyllum nodosum

Abstract: Treatment of Arabidopsis thaliana plants with a commercially-available, alkaline extract of the marine brown alga, Ascophyllum nodosum, resulted in a significant decrease in the number of females of the root-knot nematode, Meloidogyne javanica, which developed in the roots compared to those of plants grown in a water control medium. Significant reductions in egg recovery were also achieved from plants treated with the seaweed extract. Similar effects were produced when betaine components of the seaweed extract (γ-aminobutyric acid betaine, δ-aminovaleric acid betaine and glycinebetaine) were used in quantities equivalent to those applied in the seaweed extract treatment. As the experiments were conducted under monoxenic conditions, it can be concluded that the results obtained with the application of either the seaweed extract or betaines are indicative of their effects on the plants and are not dependent on microorganisms associated with the rhizosphere.

Anisotropic stresses in inhomogeneous universes

Abstract: Anisotropic stress contributions to the gravitational field can arise from magnetic fields, collisionless relativistic particles, hydrodynamic shear viscosity, gravitational waves, skew axion fields in low-energy string cosmologies, or topological defects. We investigate the effects of such stresses on cosmological evolution, and in particular on the dissipation of shear anisotropy. We generalize some previous results that were given for homogeneous anisotropic universes, by including small inhomogeneity in the universe. This generalization is facilitated by a covariant approach. We find that anisotropic stress dominates the evolution of shear, slowing its decay. The effect is strongest in radiation-dominated universes, where there is slow logarithmic decay of shear. ©1998 The American Physical Society.