Showing papers by "University of Nottingham published in 1993"

Exploratory Factor Analysis: A Users’Guide

Abstract: In 1978, Comrey wrote a guide to factor analysis in the Journal of Consulting and Clinical Psychology. This paper provides an update of the information given by Comrey in relation to exploratory factor analysis (EFA) for work and organizational psychologists, and particularly those involved with test development, interpretation and validation. In doing so, it offers a user's guide to contemporary methods and available techniques and introduces heuristics for dealing with problems of skew and kurtosis, social desirability response set, and factor naming.

A spatial model of interaction in large virtual environments

Abstract: We present a spatial model of group interaction in virtual environments. The model aims to provide flexible and natural support for managing conversations among large groups gathered in virtual space. However, it can also be used to control more general interactions among other kinds of objects inhabiting such spaces. The model defines the key abstractions of object aura, nimbus, focus and adapters to control mutual levels of awareness. Furthermore, these are defined in a sufficiently general way so as to apply to any CSCW system where a spatial metric can be identified - i.e. a way of measuring position and direction. Several examples are discussed, including virtual reality and text conferencing applications. Finally, the paper provides a more formal computational architecture for the spatial model by relating it to the object oriented modelling approach for distributed systems.

Influence of oral creatine supplementation of muscle torque during repeated bouts- of maximal voluntary exercise in man

Abstract: 1. The present experiment was undertaken to investigate the influence of oral creatine supplementation, shown previously to increase the total creatine content of human skeletal muscle (Harris RC, Soderlund K, Hultman E. Clin Sci 1992; 83: 367–74), on skeletal muscle isokinetic torque and the accumulation of plasma ammonia and blood lactate during five bouts of maximal exercise. 2. Twelve subjects undertook five bouts of 30 maximal voluntary isokinetic contractions, interspersed with 1 min recovery periods, before and after 5 days of placebo (4 × 6 g of glucose/day, n = 6) or creatine (4 × 5 g of creatine plus 1 g of glucose/day, n = 6) oral supplementation. Muscle torque production and plasma ammonia and blood lactate accumulation were measured during and after exercise on each treatment 3. No difference was seen when comparing muscle peak torque production during exercise before and after placebo ingestion. After creatine ingestion, muscle peak torque production was greater in all subjects during the final 10 contractions of exercise bout 1 ( P <0.05), throughout the whole of exercise bouts 2 ( P <0.01), 3 ( P <0.05) and 4 ( P = 0.057) and during contractions 11–20 of the final exercise bout ( P <0.05), when compared with the corresponding measurements made before creatine ingestion. Plasma ammonia accumulation was lower during and after exercise after creatine ingestion. No differences were found when comparing blood lactate levels. 4. There is evidence to suggest that the decrease in the degree of muscle torque loss after dietary creatine supplementation may be a consequence of a creatine-induced acceleration of skeletal muscle phosphocreatine resynthesis. It is postulated that an increased availability of phosphocreatine would maintain better the required rate of ATP demand during contraction. This is supported by the observed lower accumulation of plasma ammonia during exercise after creatine ingestion.

Reflection: a necessary but not sufficient condition for professional development

Abstract: Few discussions on professional development occur without some reference to the central role that reflection plays in the learning life of the teacher. It is the sine qua non of the ‘teacher‐researcher’, ‘action research’ and ‘reflective practitioner’ movements. During the last 20 years there has been a growing body of literature and practices which has sought to identify different levels of reflection in which involvement is essential, it is claimed, for the maximising of teacher growth. Yet much of this has failed to consider the need for reflection to be accompanied by confrontation if development is to occur, and alongside this, the negative and positive roles that organisational culture may play in the provision for different kinds and levels of reflection and confrontation. Two key issues are addressed in this paper. The first relates to our understanding and use of reflection—an essential part of the learning process; and the second, to the need for partnerships and coalitions within colla...

Sex Discrimination: How Do We Tell the Difference between Male and Female Faces?:

Abstract: People are remarkably accurate (approaching ceiling) at deciding whether faces are male or female, even when cues from hair style, makeup, and facial hair are minimised. Experiments designed to explore the perceptual basis of our ability to categorise the sex of faces are reported. Subjects were considerably less accurate when asked to judge the sex of three-dimensional (3-D) representations of faces obtained by laser-scanning, compared with a condition where photographs were taken with hair concealed and eyes closed. This suggests that cues from features such as eyebrows, and skin texture, play an important role in decision-making. Performance with the laser-scanned heads remained quite high with 3/4-view faces, where the 3-D shape of the face should be easiest to see, suggesting that the 3-D structure of the face is a further source of information contributing to the classification of its sex. Performance at judging the sex from photographs (with hair concealed) was disrupted if the photographs were inverted, which implies that the superficial cues contributing to the decision are not processed in a purely 'local' way. Performance was also disrupted if the faces were shown in photographic negatives, which is consistent with the use of 3-D information, since negation probably operates by disrupting the computation of shape from shading. In 3-D, the 'average' male face differs from the 'average' female face by having a more protuberant nose/brow and more prominent chin/jaw. The effects of manipulating the shapes of the noses and chins of the laser-scanned heads were assessed and significant effects of such manipulations on the apparent masculinity or femininity of the heads were revealed. It appears that our ability to make this most basic of facial categorisations may be multiply determined by a combination of 2-D, 3-D, and textural cues and their interrelationships.

Identification and genetic analysis of normal and mutant phytoene synthase genes of tomato by sequencing, complementation and co-suppression

Abstract: A tomato phytoene synthase gene, Psyl, has recently been isolated as the clone GTOM5 [20] and shown by sequence identity to be the gene from which the major fruit-ripening cDNA clone TOM5 [19] was derived. Sequence analysis of transcripts from two allelic yellow-fruited tomato mutants, mapped to chromosome 3, has shown the lack of carotenoids in fruit of these mutants to be due to the production of aberrant TOM5 transcripts which are unlikely to encode a functional phytoene synthase enzyme. In one mutant (yellow flesh) the aberrant transcript contained a sequence that, by its strong hybridization to a wide size range of genomic fragments, appeared to be repeated many times within the genome. Southern and PCR analysis of the phytoene synthase genes in the mutant revealed restriction fragment length polymorphisms, suggesting that the production of altered mRNAs was associated with specific genomic rearrangements. Constitutive over-expression of a TOM5 cDNA clone in transgenic mutant plants restored synthesis of the carotenoid lycopene in ripening fruit and also led to unscheduled pigment production in other cell types. In some mutant plants transformed with the TOM5 cDNA construct, inhibition of carotenoid production in immature green fruit, leaves and flowers was observed, due to the phenomenon of co-suppression, indicating that different insertion events with the same gene construct can lead to overexpression or co-suppression in transgenic plants. Green organs of these plants were susceptible to photobleaching, due to the lack of carotenoids. These results suggest the existence of separate Psy genes for carotenoid synthesis in green organs.

Importance of placement of intra-articular steroid injections.

Abstract: had asthma or exercise induced bronchoconstriction.' The figures agreed with those of Weiler et al, who found self reported asthma in 12% of football players; basketball players had a low asthma prevalence.29 In a study from Portugal Gomes et al found normal bronchial responsiveness in elite runners.?0 In another study swimmers had a higher prevalence of asthma and bronchial hyperresponsiveness than other athletes and the authors postulated a relation with ambient swimming pool conditions.3' To our knowledge there are no other studies of skiers or other athletes performing exercise at low temperatures. From the few reports available there is no evidence that strenuous training by itself increases the risk of asthma. Strenuous training at low temperatures, however, seems to be pathogenetic for asthma, possibly due to the repeated breathing of large amounts of cold air.

The preparation and characterization of poly(lactide-co-glycolide) microparticles. II: The entrapment of a model protein using a (water-in-oil)-in-water emulsion solvent evaporation technique

Abstract: Poly(lactide-co-glycolide) (PLG) microparticles with entrapped antigens have recently been investigated as controlled-release vaccines. This paper describes the preparation of PLG microparticles with an entrapped model antigen, ovalbumin (OVA), using a (water-in-oil)-in-water emulsion solvent evaporation technique. In a series of experiments, the effects of process parameters on particle size and OVA entrapment were investigated. It was found that smooth, spherical microparticles 1–2 µm in diameter containing up to 10% (w/w) OVA could be produced using a small volume of external aqueous phase containing a high concentration of emulsion stabilizer and a 1:5 antigen:polymer ratio. PAGE analysis, isoelectric focusing, and Western blotting of OVA released from the microparticles in vitro confirmed that the molecular weight and antigenicity of the protein remained largely unaltered by the entrapment procedure.

What's the Difference between Men and Women? Evidence from Facial Measurement:

Abstract: Human subjects are able to identify the sex of faces with very high accuracy. Using photographs of adults in which hair was concealed by a swimming cap, subjects performed with 96% accuracy. Previous work has identified a number of dimensions on which the faces of men and women differ. An attempt to combine these dimensions into a single function to classify male and female faces reliably is described. Photographs were taken of 91 male and 88 female faces in full face and profile. These were measured in several ways: (i) simple distances between key points in the pictures; (ii) ratios and angles formed between key points in the pictures; (iii) three-dimensional (3-D) distances derived by combination of full-face and profile photographs. Discriminant function analysis showed that the best discriminators were derived from simple distance measurements in the full face (85% accuracy with 12 variables) and 3-D distances (85% accuracy with 6 variables). Combining measures taken from the picture plane with those derived in 3-D produced a discriminator approaching human performance (94% accuracy with 16 variables). Performance of the discriminant function was compared with that of human perceivers and found to be correlated, but far from perfectly. The difficulty of deriving a reliable function to distinguish between the sexes is discussed with reference to the development of automatic face-processing programs in machine vision. It is argued that such systems will need to incorporate an understanding of the stimuli if they are to be effective.

Addressing the gap in scheduling research: a review of optimization and heuristic methods in production scheduling

Abstract: This paper considers the gap between scheduling theory and scheduling practice. The development and the main results of classical scheduling theory are reviewed and presented in an easily accessible way. Recent trends in scheduling research which attempt to make it more relevant and applicable are described. The nature of the gap between theory and practice is discussed. The failure of classical scheduling theory to address the total environment within which the scheduling function operates is noted. However, scheduling research in operations management and manufacturing systems tends to ignore the rich vein of methods, techniques and results in the classical theory. The need for an integrated scheduling research effort, containing elements of both approaches, is stressed.

Normal values for handgrip strength in 920 men and women aged over 65 years, and longitudinal changes over 4 years in 620 survivors

Abstract: 1. The maximal grip strength of the hand has been measured in a random sample of 359 men and 561 women aged over 65 years living in their own homes. The response rate was 80% from a representative demographic area of the U.K. Measurements were made of body mass, skeletal size (demispan) and grip strength. Grip strength was measured using a custom-built strain-gauged dynamometer. The best of three attempts was taken as definitive. A structured questionnaire was used to obtain information about customary activity, use of handgrip muscles, health and psychological well-being. This was repeated with 620 survivors 4 years later. 2. The results for strength were normally distributed. The right hand was 10% stronger than the left and men had twice the strength of women. Strength was significantly related to skeletal size and in men to body mass. The gender difference was only partly accounted for by skeletal size and women were substantially disadvantaged in terms of their strength/body mass ratio. 3. There was a significant decline in strength with age of 2%/year for men and women. Strength was also significantly related to customary activity, reported use of the hands and psychological and physical health. 4. After 4 years 620 survivors were re-measured. Grip strength had declined by 12% in men and 19% in women and these losses were significantly related to age. A significant decline was also found in reported use, customary activity and health scores, and in women in body mass and psychological health.(ABSTRACT TRUNCATED AT 250 WORDS)

Altered fruit ripening and leaf senescence in tomatoes expressing an antisense ethylene‐forming enzyme transgene

Abstract: Summary Tomato plants in which the synthesis of ethylene-forming enzyme (EFE) had been inhibited by an anti-sense gene were used to study the role of ethylene in fruit ripening at the biochemical and molecular level. A reduction in total lycopene accumulation was observed in EFE-antisense fruit ripened both on and off the plant. The rate of over-ripening and fruit spoilage was also reduced in the EFE-antisense fruit. The degree of inhibition of ripening was shown to be dependent upon the stage of development at which the fruit were detached from the plant. The effects on ripening in EFE-antisense fruit were much more pronounced when fruit were detached from the vine before the onset of colour change, and were associated with changes in the level of accumulation of mRNAs homologous to a number of previously characterized ripening-related cDNAs. The retarded ripening of detached EFE-antisense fruit could be partially restored by ethylene treatment. In addition to changes observed in ripening fruit, a temporal delay in the onset of foliar senescence was observed in EFE-antisense plants, indicating that the physiological effects of the EFE-antisense gene, and the associated reduction in ethylene evolution, are not confined specifically to fruit ripening.

Signalling in Territorial Systems: A Context for Individual Identification, Ranging and Eavesdropping

Abstract: Territorial systems are characterized by the relative longevity and stability of interactions between neighbouring individuals. Two abilities of signal receivers that can be seen as adaptations increasing the efficiency of territory defence will be discussed: identifying neighbouring individuals and ranging (i.e. determining the distance to) signallers. The costs involved in such discriminations will also be outlined. Although signalling has been traditionally considered as occurring between two individuals (signaller and receiver), long-range signals will be received by many individuals. In territorial systems a group of neighbours could be considered as a communication network: consisting as its simplest of a signaller and a number of receivers. The scope for low cost, low-risk information gathering in such networks by eavesdropping will be discussed with particular reference to territorial songbirds and electric fish.

Temperature and the Pollinating Activity of Social Bees

Abstract: . 1Thermal constraints on flight acivity limit the pollinating effectiveness of bees. Each species of social bee has a microclimatic ‘window’ within which foraging flight can be sustained. 2To predict whether a given species of social bee is worth testing as a pollinator in a given climate, it is useful to know at least the lower limits of that microclimatic ‘window’. We consider how information from a series of bee counts through a day can be used to characterize a bee species in terms of activity/microclimate relations as a basis for predicting the diel pattern of foraging activity of a bee introduced into a new climate as a pollinator. 3We discuss the relative merits of bee counts at a foraging patch and counts based on hive traffic as indices of the proportion of bees active. 4We suggest that the activity/microclimate relations of a species be expressed in terms of the lower threshold black globe temperature for flight activity. Black globe temperature, Tg, is easily measured with inexpensive equipment, and can substitute for measurements of ambient temperature and radiation as a predictor of diel patterns of bee activity. 5We use examples of field data to explore the relationship between microclimate and activity for the honeybee Apis mellifera and several species of bumblebee, Bombus. Regression analysis is used to relate activity to Tg and to identify the lower temperature threshold for activity from field bee counts. 6In field studies analysed here, the bumblebees Bombus terrestrisllucorum, B.pascuorum and B.hortorum began foraging at lower temperatures than honey-bees or B.lapidarius.

Effect of aspirin and non-steroidal anti-inflammatory drugs on colorectal adenomas: case-control study of subjects participating in the Nottingham faecal occult blood screening programme.

Abstract: OBJECTIVE--To examine the relation between the use of aspirin and non-steroidal anti-inflammatory drugs and the presence of asymptomatic colorectal adenomas. DESIGN--Case-control study of subjects participating in a randomised controlled trial of faecal occult blood screening for colorectal cancer. Data on analgesics and other drugs were obtained from a questionnaire which was mainly concerned with diet and was administered by an interviewer. SETTING--Nottingham. SUBJECTS--147 patients with positive results in faecal occult blood tests who were found to have colorectal adenomas (cases), 153 age and sex matched control subjects with negative results in such tests (negative controls), and 176 control subjects with positive results in the tests who were found not to have colorectal adenomas (positive controls). MAIN OUTCOME MEASURES--Relative risk of developing colorectal adenomas according to frequency and duration of use of analgesics. RESULTS--Cases reported taking less aspirin and non-steroidal anti-inflammatory drugs than the negative controls, with the estimated relative risk for any use being 0.49 (95% confidence interval 0.3 to 0.8). The inverse association was less strong when cases were compared with the positive controls (0.66 (0.4 to 1.1)). The association was specific for aspirin and non-steroidal anti-inflammatory drugs there being no association with paracetamol or other drugs. Prescribed use of non-steroidal anti-inflammatory drugs for longer than five years was associated with the lowest risk (0.21 (0.1 to 0.8)), although the numbers reporting prolonged prescribed use were small. CONCLUSIONS--These findings support the hypothesis that aspirin and non-steroidal anti-inflammatory drug use protects against the development of colorectal neoplasia.

Radiographic patterns and associations of osteoarthritis of the knee in patients referred to hospital.

Abstract: OBJECTIVES--To investigate differing patterns and associations of osteoarthritis of the knee in patients referred to hospital. METHODS--Two hundred and fifty two consecutive patients (161 women, 91 men; mean age 70 years, range 34-91 years) referred to hospital with osteoarthritis of the knee underwent clinical, radiographic, and synovial fluid screening. RESULTS--Radiographic changes of osteoarthritis of the knee (definite narrowing with or without osteoarthritic features) were bilateral in 85% of patients. Of 470 knees affected, 277 (59%) were affected in two compartments and 28 (6%) in three compartments. Unilateral and isolated medial tibiofemoral osteoarthritis were more common in men. Calcium pyrophosphate crystal deposition was common (synovial fluid identification in 132 (28%) knees; knee chondrocalcinosis in 76 (30%) patients) and associated with disability, bilateral, multicompartmental and severe radiographic osteoarthritis, marked osteophytosis, attrition, and cysts. Multiple clinical nodes (58 (23%) patients) and radiographic polyarticular interphalangeal osteoarthritis (66 (26%) patients) were associated with a higher frequency of inactivity pain, disability, multicompartmental and severe radiographic change. Forestier's disease predominated in men but showed no other associations. CONCLUSIONS--In a group of patients referred to hospital osteoarthritis of the knee is usually bilateral and affects more than one compartment. Severe and multicompartmental radiographic changes are associated with calcium pyrophosphate crystal deposition, nodal change, and polyarticular interphalangeal osteoarthritis.

Effect of synchronizing the rate of dietary energy and nitrogen release on rumen fermentation and microbial protein synthesis in sheep

Abstract: The effects of two diets formulated to be either synchronous or asynchronous with respect to the hourly supply of energy and nitrogen on rumen fermentation and microbial protein synthesis were studied in sheep.In Expt 1, the in situ degradation characteristics of nitrogen (N), organic matter (OM) and carbohydrate (CHO) fractions were determined in winter wheat straw, winter barley, malt distillers dark grains rapeseed meal and fishmeal. The feeds exhibited a large range in degradability characteristics of the nitrogen and energy-yielding fractions.A computer program was developed based upon the raw material degradation characteristics obtained from the above studies. The program was used to formulate two diets with similar metabolizable energy (9·5 MJ/kg DM) and rumen degradable protein contents (96 g/kg DM) but to be either synchronous (diet A) or asynchronous (diet B) with respect to the hourly rate of release of N and energy. The program was used to predict the hourly release of N, OM and CHO and the molar production of volatile fatty acids (VFA).In Expt 2, the two diets were fed to four cannulated sheep at the rate of 1 kg/day in four equal portions, in two periods, using a change-over design. Rumen ammonia concentrations followed the predicted rate of N degradation. A maximum concentration of 10·5 and 7 mM for diets A and B respectively was achieved within the first hour of feeding which then fell to 7 and 3 mM respectively. Rumen VFA proportions were more stable for the synchronous diet (A) than the asynchronous diet (B) and were more stable than predicted for both diets. True ruminal degradation of OM and CHO was similar for both diets and close to that predicted, although fibre degradability in diet A was 30% lower than predicted due to a reduction in both cellulose and hemicellulose digested. Microbial protein production was estimated simultaneously with L-[4,5–3H]leucine and a technique based on cytosine. Estimates varied with marker but mean values indicated a 27% greater production of microbial N (g N/kg DM I) with the synchronous diet (A) and an average improvement in microbial protein efficiency (g N/kg OM truly degraded or CHO apparently degraded) of 13%, although neither difference was significant. There was evidence of a greater recycling of N in the animals and a significantly lower content of rumen degradable protein when the sheep were fed the asynchronous diet (B).The results are consistent with the view that synchronizing the rate of supply of N and energyyielding substrates to the rumen micro-organisms based upon ingredient in situ degradation data can improve microbial protein flow at the duodenum and the efficiency of microbial protein synthesis.

The transition state of the f + h2 reaction.

Abstract: The transition state region of the F + H(2) reaction has been studied by photoelectron spectroscopy of FH(2)(-). New para and normal FH(2)(-)photoelectron spectra have been measured in refined experiments and are compared here with exact three-dimensional quantum reactive scattering simulations that use an accurate new ab initio potential energy surface for F + H(2). The detailed agreement that is obtained between this fully ab initio theory and experiment is unprecedented for the F + H(2) reaction and suggests that the transition state region of the F + H(2) potential energy surface has finally been understood quantitatively.

The production of antifungal volatiles by Bacillus subtilis

Abstract: A strain of Bacillus subtilis which produces an antibiotic metabolite was also found to produce a volatile compound(s) which was antifungal to Rhizoctonia solani and Pythium ultimum. Growth of the fungi was severely impaired in the presence of the volatiles and physiological abnormalities of the hyphae were observed, including hyphal distortion and vacuolation. A range of media were tested for volatile production and potato dextrose agar (PDA) was found to be the most active. Temperature had a considerable effect on antifungal volatile activity with the greatest inhibition occurring at 30 degrees C. Addition of iron (III) chloride to Sabouraud's glucose agar (SGA) also enhanced the antifungal effect. The volatiles were found to be water soluble and remained active when trapped in SGA.

Removing colour from dyehouse waste waters — a critical review of technology available

Abstract: Strict controls are being introduced on coloured effluents from UK dyehouses discharged to sewer. Failure to comply with these new regulations could result in prosecution. Yet in certain cases the technology to treat dyehouse waste waters adequately is either not available or prohibitively costly. This paper (originally given at a conference at the Manchester Conference Centre entitled ‘Waste water management for industry’) reviews the treatment technologies that can currently be used by the textile processor and discusses those newer techniques that may emerge in the near future.

Bayesian Inference for Generalized Linear and Proportional Hazards Models Via Gibbs Sampling

Abstract: It is shown that Gibbs sampling, making systematic use of an adaptive rejection algorithm proposed by Gilks and Wild, provides a straightforward computational procedure for Bayesian inferences in a wide class of generalized linear and proportional hazards models