Showing papers by "University of Bedfordshire published in 1999"

Astronomical calibration of Oligocene-Miocene time

Abstract: Lithological cyclicity was observed aboard the JOIDES RESOLUTION in sediment sequences recovered from the Ceara Rise during ODP Leg 154. Shipboard work led to the conclusion that the Oligocene was probably characterized by ca . 41 ka cycles. Weedon and others were able to confirm this, and created a provisional time–scale for the Oligocene by assuming that the cyclicity is a response to orbital obliquity variation, and by using spectral analysis to estimate the mean wavelength and hence the sedimentation rate of successive intervals of core. We have extended this work by intercorrelating almost all the 9.5 m sediment cores from each of the four sites that recovered Oligocene sediment. We have successfully correlated all the material covering a time–interval of ca . 10 Ma from 18 Ma to 28 Ma, as well as most of the sediment from the 14 to 18 Ma and 28 to 34 Ma intervals. Although variability is dominated by the 41 ka cycle there is sufficient variability at the precession period (amplitude–modulated by eccentricity) to permit an absolute placement of this section with reference to the calculated orbital history. Further work is needed to establish precisely the implications of this calibration for the geological time–scale but it appears that the true ages of events close to the Oligocene–Miocene boundary are ca . 0.9 Ma younger than they appear on recently published time–scales. The sedimentary record preserves information concerning the amplitude modulation of the obliquity signal that is of astronomical as well as geological significance.

Spectral sensitivity of the domestic fowl (Gallus g. domesticus).

Abstract: 1. The spectral sensitivity of 7 broiler fowl was determined in a behavioural test. 2. Initially the birds were trained to receive a food reward by pecking at a clear, Perspex panel behind which was a light stimulus (circular, diameter=9 mm), originating from a tungsten-halogen lamp. Subsequently , they were trained to choose between 2 panels only 1 of which was lit; the assignation of light and dark on each panel was randomly ascribed between trials. The colour of the lit panel was determined by the wavelength of the light transmitted through one of 13 closely defined narrow bandwidth filters between 326

The market viability of European mass tourist destinations. A post‐stagnation life‐cycle analysis

Abstract: First generation European mass tourist resorts, defined as those that developed in the north of the continent up to and including the first half of this century, have shown a variety of responses to impending decline within the post-stagnation phase of their life-cycle, much as predicted in the tourist area life-cycle (TALC) model. There have been winners and losers, as some destinations have diversified their local economies and others have accepted gradual contraction, whereas a select few have maintained a competitive edge through product investment and reorientation to new markets. For the second generation of European mass tourist resorts, those high density tourist areas that emerged in the Mediterranean in the 1960s, the evolutionary life-cycle has, to date, been of a much shorter duration. The period from exploration to stagnation has lasted a mere 30 years, sometimes less. The nature of these resorts, whereby rapid development has created a tourism monoculture, means that the onset of decline has far more dramatic implications to local economies when compared with first generation resorts. Unfortunately, although strategic planning initiatives are now (belatedly) being practised, it is likely that rejuvenation will only be short-lived due in most cases to the inherent structural weaknesses of these resorts. Their legacy is one of overdevelopment and environmental scarring, they rely too heavily on price as a marketing tool in an increasingly quality conscious market, and the powers of promotion and distribution remain largely in the hands of northern European mass consolidators (tour operators), with little commerical incentive for customer loyalty. This paper thus predicts a pessimistic post-stagnation scenario for most second generation Mediterranean mass market resorts. Copyright © 1999 John Wiley & Sons, Ltd.

Survival of Low-pH Stress by Escherichia coli O157:H7: Correlation between Alterations in the Cell Envelope and Increased Acid Tolerance

Abstract: Survival of a nontoxigenic isolate of Escherichia coli O157:H7 at low pH (pH 3.0) was examined over prolonged time periods for each of three population types: exponential-phase cells, stationary-phase cells, and acid-adapted exponential-phase cells. In each population, approximately 5 x 10(4) CFU ml-1 were detected after a 24-h incubation at pH 3.0. Even after 3 days at pH 3.0, significant numbers of survivors from each of the three populations could be detected. The high level of acid tolerance exhibited by these survivors was found to be quickly lost once they were transferred to conditions which permitted growth to resume, indicating that they were not mutants. Proton flux measurements on the three populations of cells revealed that the initial rates of viability loss at pH 3.0 correlated well with net proton accumulation. Cells showing a high initial rate of viability loss (exponential-phase cells) accumulated protons at the highest rate, whereas resistant populations (adapted or stationary-phase cells) accumulated protons only slowly. Differences in the protein composition of the cell envelope between the three populations were studied by two-dimensional polyacrylamide gel electrophoresis. Complex differences in the pattern of proteins expressed by each population were uncovered. The implications of these findings are discussed in the context of a possible model accounting for acid tolerance in this important food-borne pathogen.

Astronomical calibration of the Jurassic time-scale from cyclostratigraphy in British mudrock formations

Abstract: Three British Jurassic mudrock formations have been investigated, via timeseries analysis, for evidence of sedimentary cyclicity related to orbitalclimatic (Milankovitch) cyclicity: the Blue Lias, ...

Local lymph node assay responses to paraphenylenediamine: Intra- and inter-laboratory evaluations

Abstract: The murine local lymph node assay (LLNA) is a method for the prospective identification of skin sensitizing chemicals. Proliferative responses induced in lymph nodes draining the site of topical application of the test chemical are measured and those chemicals that induce a stimulation index of three or more compared with concurrent vehicle-treated controls are considered to have the potential to cause skin sensitization. Dose-response data from the LLNA may be used to derive an estimate of relative skin sensitizing potency, based upon derivation of the concentration of chemical required to cause a stimulation index of 3 (EC3 value) as calculated by linear interpolation. The purpose of the present investigations was to examine the stability of LLNA responses and the consistency of derived EC3 values induced by the contact allergen paraphenylenediamine (PPD). Analyses were conducted once a month over a 4-month period in each of two independent laboratories. In all assays, and in both laboratories, PPD elicited a positive response. Although some minor differences in responses between and within laboratories were observed, the derived EC3 values were generally very consistent. In Laboratory 1, EC3 values varied between 0.06 and 0.09% PPD, whereas in Laboratory 2 the range was 0.09-0.20%. These EC3 values are consistent with clinical experience of this material insofar as it is a common and relatively potent cause of allergic contact dermatitis in humans. Taken together, these data confirm the stability of LLNA responses both with time and between laboratories and provide additional support for the use of derived EC3 values in the assessment of relative skin sensitizing potency.

Use of multi-staining flow cytometry to characterise the physiological state of Escherichia coli W3110 in high cell density fed-batch cultures.

Abstract: High cell density fed-batch fermentations of Escherichia coli W3110 have been carried out at specific growth rates of less than 0.3 h ˛1 , to investigate the effect of glucose limitation on the physiological state of indi- vidual cells. After an initial exponential batch phase, the feed rate was held constant and a final dry cell weight of approximately 50 g per litre was achieved. The fermen- tations were monitored by mass spectrometry whilst measurements of pH, DOC, CFU/mL, TCN, OD500nm and residual glucose concentrations were made. Satisfactory and reproducible results were obtained. Flow cytometric analysis of cells in broth samples, based on either of two multi-staining protocols, revealed a progressive change in cell physiological state throughout the course of the fermentations. From these measurements it was con- cluded that the loss in reproductive viability towards the end of the fed-batch process is due to cell death and not due to the formation of a "viable but nonculturable state" as had previously been reported. Since the pres- ence of a high proportion of dead or dying cells at any time during a fermentation has a detrimental effect on the synthesis of any desired product it is proposed that an on-line flow cytometric analysis and control strategy could be used as a means of increasing overall process efficiency. © 1999 John Wiley & Sons, Inc. Biotechnol Bioeng 63: 705-711, 1999.

Skin sensitization risk assessment: a comparative evaluation of 3 isothiazolinone biocides

Abstract: Many of the chemicals in common use possess, to some degree, a capacity to cause skin sensitization. Consequently, it is important to conduct a thorough and accurate risk assessment when it can be anticipated that such chemicals are likely to come into contact with human skin. Such risk assessments must consider the nature and extent of dermal exposure together with the sensitizing potency of the chemical. Whilst the exposure elements of the risk assessment process are often well understood, or can at least be reasonably predicted on the basis of the proposed usage of the chemical, the determination of skin sensitizing potency may be problematic. In this paper, we describe an approach to the determination of relative potency of 3 isothiazolinone biocides. Initially, the local lymph node assay (LLNA) provides an estimate of relative sensitizing potency. Where appropriate, this can be followed by confirmatory testing in the human repeat insult patch test (HRIPT). The data generated reveal that (chloro)methyl isothiazolinone (CMI) is a significantly stronger sensitizer than either methyl trimethylene isothiazolinone (MTI) or benzisothiazolinone (BIT). Furthermore, both the LLNA and the HRIPT data show consistently that BIT is a somewhat weaker skin sensitizer than MTI. As an important additional component of the safety evaluation, the ability of these sensitizing isothiazolinones to cross-react has been considered; the data indicate that the more weakly sensitizing isothiazolinones do not elicit allergic reactions in subjects sensitized to MCI. The implications for use of these biocides in various product types are discussed.

The effect of an inhibitor of matrix metalloproteinases on colonic inflammation in a trinitrobenzenesulphonic acid rat model of inflammatory bowel disease.

Abstract: Background : Recent publications have reported that matrix metalloproteinases (MMPs) are expressed in colonic tissue taken from ulcerative colitis and Crohn’s disease patients. Aim : To evaluate the effects of a matrix metalloproteinase inhibitor, marimastat, on colonic inflammation in experimental colitis induced by trinitrobenzenesulphonic acid (TNBS)-ethanol in the rat. Methods : Rats were dosed (by mouth) for 7 days (b.d.) with either sulphasalazine (50 mg/kg), marimastat (40 mg/kg) or vehicle. TNBS-ethanol was administered rectally on the 4th day of dosing. On the last day of dosing, colons were removed and assessed for inflammation using myeloperoxidase activity, production of soluble TNFα (tumour necrosis factor α), clinical score and histological assessment. In addition, the bioavailability and effect of marimastat on a range of MMPs were assessed in-vitro. Results : In this study we have confirmed that marimastat is a broad spectrum MMPI with a bioavailability of 5%. TNBS rats dosed with sulphasalazine had a significantly lower (P < 0.05) myeloperoxidase activity, TNFα production and a markedly lower clinical score. Similarly, rats dosed with marimastat had a significantly lower (P < 0.05) myeloperoxidase activity and clinical score, but the TNFα production was not significantly reduced. Conclusions : Dosing rats with TNBS-induced colitis using sulphasalazine or marimastat produced a significant reduction in tissue injury and inflammation.

Cyclostratigraphy and the Early Jurassic timescale: Data from the Belemnite Marls, Dorset, southern England

Abstract: Time series based on determinations (wt%) of calcium carbonate and total organic carbon have been generated for the entire Lower Jurassic hemipelagic Belemnite Marls, Dorset, southern Britain. This formation was deposited during early Pliensbachian time, at a paleolatitude of about 35°N, in an epicontinental sea that was largely enclosed by the supercontinent of Pangea. The sequence contains compositionally diverse light and dark marl bedding couplets, the thicknesses of which are notably reduced in the upper third of the section. The regularity of the couplets in segments of the sequence, combined with a regular amplitude modulation, indicates an origin that is related to the orbital-precession cycle (i.e., one of the Milankovitch parameters). A timescale is developed by assigning a duration of 20 k.y. per couplet, and this suggests that the entire formation represents at least 1.78 m.y. Using the new timescale, bundles of bedding couplets are shown to have periods consistent with the 123 k.y. component of the orbital-eccentricity variations. The amplitude of the couplets varies at the same frequencies as the bundle cycles, in accordance with the interpretation that the couplets record precession and the bundles record eccentricity. However, despite having the same frequency of variation, there is no consistent relationship (coherence) between the variations in amplitude of the couplet cycle and the bundle cycles as would be predicted by the eccentricity-precession relationship. This mismatch can be explained in terms of nonlinear behavior of a climatic system characterized by a varying response time or nonlinear response of the sedimentary system itself. The data contain no evidence for orbital-obliquity cycles. Because the obliquity cycle affects insolation principally at high latitudes, the climatic factors that indirectly controlled the sedimentary cyclicity must have arisen at relatively low latitudes. The Belemnite Marls timescale indicates highly variable minimum durations for ammonite zones and subzones. True durations cannot be determined because it is possible that the succession is incomplete as a result of undetected erosion and/or nondeposition. A combination of the new results with cyclostratigraphic data from Yorkshire, northeast England, and the Southern Alps, Switzerland, indicates, based on cycle counts, that the Pliensbachian Stage lasted at least 4.82 m.y. Marine Sr-isotope ratios appear to have decreased linearly from the start of Jurassic time until the end of Pliensbachian time. The rate of decrease in 87 Sr/ 86 Sr established using the Belemnite Marls timescale was 0.000042/m.y. (or less if the main part of the formation is incomplete). Using this rate, with the observed changes in Sr-isotope ratios, gives minimum durations of 2.86 m.y. for Hettangian time, 7.62 m.y. for Sinemurian time, and 6.67 m.y. for Pliensbachian time.

Book towns as tourism developments in peripheral areas.

Abstract: This paper examines a research and development programme into one of the most novel forms of tourism development in peripheral areas of Europe, the book town, which started in Hay-on-Wye in Wales in 1961 and by the 1990s had spread to Belgium, France, The Netherlands, Norway and Finland. In 1996 the Scottish Tourism Research Unit at the University of Strathclyde, in partnership with Scotland's national development agency, Scottish Enterprise, undertook a programme of research aimed at evaluating the tourism potential of a book town development in Scotland. The results led to the development of a book town in Wigtown, a rural town in the extreme south west of Scotland, which was launched in May 1998. Copyright © 1999 John Wiley & Sons, Ltd.

Variable frequency microwave heating of food.

Abstract: Industrial microwave food processing is universally based on single frequency microwave sources. With the emergence of variable frequency microwave ovens, it is possible to exploit the frequency dependence of a food’s permittivity and/or choice of heating frequency, for example as a new route to achieving targeted heating. Variable frequency heating procedures are developed to overcome the geometry of a roughly spherical foodstuff dominating the heating pattern when heated in fi xed frequency applicators. Target mean temperatures of 55, 75 and 90°C within 2 minutes and without physical damage were set; means of 54.5 ± 4.1, 75.1 ± 4.7 and 87.6 ± 3.5°C respectively were achieved within the time constraint and with no major physical damage, based on combining 8 discrete frequencies between 2.4 and 6.2 GHz.

Computer-Assisted Assessment: Impact on Higher Education Institutions

Abstract: As an increasing number of higher education institutions (HEI's) look to computers to solve some of the problems associated with the burden of expanded student numbers, advances in technology are increasingly impacting the way in which the curriculum is delivered and assessed (Hartley et al, 1999). More contentious than using computers to deliver content and support student learning is computer-assisted assessment (CAA). CAA can include a range of activities such as, the collation, analysis and transmission of examination grades across networks and, most desirably, the use of computer-based assessment, where students complete assessments at workstations and their answers are automatically marked. CAA is, in comparison to computer-aided learning, a relatively new development and is often pioneered by enthusiastic individual academics (Stephens et al, 1998). The successful implementation of CAA is often hindered or abandoned due to time and funding restrictions, or reliance on an individual academic.

Learning to teach in the secondary school : a companion to school experience

Abstract: Part 1. Becoming a Teacher 1.1 What Do Teachers Do? 1.2 The Student Teacher's Role and Responsibilities 1.3 Managing your Time and Preventing Stress 1.4 Teaching and Learning with ICT: An introduction Part 2. Beginning to Teach 2.1 Reading Classrooms 2.2 Schemes of Work and Lesson Planning 2.3 Taking Responsibility for Whole Lessons Part 3. Classroom Interactions and Managing Pupils 3.1 Communicating with Pupils 3.2 Motivating Pupils 3.3 Behaviour for Learning Part 4. Pupil Differences 4.1 Differentiation, Progression and Pupil Grouping 4.2 Growth, Development and Diet 4.3 Cognitive Development 4.4 Responding to Diversity 4.5 Moral Development and Values 4.6 Introduction to Inclusion Part 5. Helping Pupils 5.1 Ways Pupils Learn 5.2 Active Learning 5.3 Teaching Styles and Individualised Learning 5.4 Improving your Teaching Part 6. Assessing and Recording Pupils' Work 6.1 Assessment: Principles and practice 6.2 External Examinations and Assessment Part 7. The School, Curriculum and Society 7.1 Aims of Education 7.2 The School Curriculum 7.3 The National Curriculum 7.4 The Broader Curriculum 7.5 Scottish Curriculum and Assessment Part 8. Your Professional Development 8.1 Getting your First Post 8.2 Developing Further as a Teacher: Managing your Induction Year 8.3 Accountability, Contractual and Statutory Duties Part 9. And Finally

Influence of application vehicle on skin sensitization to methylchloroisothiazolinone/methylisothiazolinone: an analysis using the local lymph node assay

Abstract: The murine local lymph node assay (LLNA) is a method for the identification of skin sensitizing chemicals in which activity is measured as a function of proliferative responses induced in draining lymph nodes following topical exposure of mice to the test material. More recently, the LLNA has also been used for the determination of relative skin sensitizing potency based upon the mathematical derivation of an EC3 value, this being the estimated concentration of test chemical necessary to provoke a 3-fold increase in lymph-node cell-proliferative activity compared with concurrent vehicle-treated controls. Here we describe the use of the LLNA to determine the influence of vehicle on the skin-sensitizing potency of methylchloroisothiazolinone/methylisothiazolinone (MCI/MI), the active ingredient of preservatives such as Kathon CG. To this end, LLNA responses to MCI/ MI were measured using the vehicles 4:1 acetone:olive oil (AOO), methyl ethyl ketone, dimethylsulfoxide, dimethylformamide, propylene glycol (PG) and acetone. It was found that the vehicle in which MCI/MI was applied had a substantial impact on activity, with derived EC3 values varying from 0.0049% with AOO to 0.048% with PG. With the other vehicles, EC3 values ranged from 0.0068 to 0.0076%. The skin sensitizing potency of MCI/MI as judged from LLNA responses is consistent with what is known of the requirements for sensitization in humans. It is proposed that the LLNA not only provides a method for determination of relative skin sensitizing potency, but is also appropriate for assessing the influence of vehicle matrix on sensitizing activity.

Diffusion of Aqueous Sugar Solutions as Affected by Locust Bean Gum Studied by NMR

Abstract: Time domain proton NMR was used to study translational diffusion and molecular mobility of sugar and water molecules in simple aqueous solutions to determine how the addition of hydrocolloid stabilizers affect their mobility. Results showed that addition of Locust Bean Gum (LBG) did not affect the diffusion or mobility of either the sugar or water molecules over distances up to 10μm in unfrozen solutions. The diffusion properties of the sugar and water molecules were not affected by either biopolymer cryogelation or the presence of ice. We hypothesized that retardation of the ice crystal growth rates in aqueous sugar solutions caused by the presence of LBG was not a bulk property of the solution. The most likely cause is a modification of the local interfacial region between the ice crystal surface and the surrounding unfrozen solution.

A kinetic study of the effect of hydrogen peroxide and peracetic acid against Staphylococcus aureus and Pseudomonas aeruginosa using the bioscreen disinfection method.

Abstract: Hydrogen peroxide and peracetic acid at pH 4 were examined against Staphylococcus aureus and Pseudomonas aeruginosa using the published 'Bioscreen' technique of biocide analysis. The data were examined using either classical Chick-Watson (CW) log-linear disinfection kinetics or the empirical, non-linear time Hom model. In some cases, modelling the data with the classical CW method gave good linear correlations, in others, however, deviations from this model were observed. In such cases the Hom model proved an adequate descriptor of the data. The Bioscreen technique therefore gives data which can be analysed using the normal mechanistic and empirical models currently available.

Microwave phase control heating

Abstract: Summary Food processors are increasingly looking towards new microwave-based technologies to deliver competitive advantage in the market place, reduce operational costs, allow greater product innovation and increase flexibility without the need for large capital investments. The technical barriers to the widespread exploitation of microwave heating, and opportunities for microwave heating in food processing, are discussed in the context of the need to understand the microwave field/material/process interaction. It is shown how a new application of interference techniques, called phase control microwave heating, may offer opportunities for enhanced heat transfer in food processing, especially for direct control of the spatial power deposition within a foodstuff. Simulations of phase control heating using a 3D FETD microwave model, validation of experimental findings and examples in other applications are presented.

Assisted bibliotherapy: effective, efficient treatment for moderate anxiety problems.

Abstract: Specific psychological treatments of proven effectiveness for moderate anxiety disorders are not often easily accessible in general practice. In this study, selected patients were supported in learning skills to manage their symptoms. This approach was efficient, acceptable, and led to clinically significant symptom reduction for a high proportion of patients. This improvement was well sustained at three-month follow-up.

Integrating species and habitat data for nature conservation in Great Britain: data sources and methods

Abstract: Summary 1.Britain is unusual in the quantity and quality of species and habitat data available, at both national and regional scales. This paper reviews the sources, coverage and quality of these data. 2.Habitat and species data are used by conservation agencies in England, Scotland and Wales for site selection and for monitoring habitat quality. The paper argues, however, that neither habitat data nor species distribution data on their own are sufficient to locate and monitor habitats for nature conservation purposes effectively. 3.Differences in sampling methodologies between habitat and species surveys present methodological difficulties for the development of an integrated monitoring system that uses both types of data. These problems need to be overcome if habitat and species data are to be used more effectively for nature conservation in the wider countryside. 4.A more integrated system based on the concept of biotope occupancy is proposed and discussed. The implementation of the system would assist with understanding those factors that explain observed patterns in species distribution and diversity, thereby helping to improve the effectiveness of policies for nature conservation.