Showing papers by "University of Exeter published in 2000"

Music in Everyday Life

Abstract: The power of music to influence mood, create scenes, routines and occasions is widely recognised and this is reflected in a strand of social theory from Plato to Adorno that portrays music as an influence on character, social structure and action. There have, however, been few attempts to specify this power empirically and to provide theoretically grounded accounts of music's structuring properties in everyday experience. Music in Everyday Life uses a series of ethnographic studies - an aerobics class, karaoke evenings, music therapy sessions and the use of background music in the retail sector - as well as in-depth interviews to show how music is a constitutive feature of human agency. Drawing together concepts from psychology, sociology and socio-linguistics it develops a theory of music's active role in the construction of personal and social life and highlights the aesthetic dimension of social order and organisation in late modern societies.

Plant L‐ascorbic acid: chemistry, function, metabolism, bioavailability and effects of processing

Abstract: Humans are unable to synthesise L-ascorbic acid (L-AA, ascorbate, vitamin C), and are thus entirely dependent upon dietary sources to meet needs. In both plant and animal metabolism, the biological functions of L-ascorbic acid are centred around the antioxidant properties of this molecule. Considerable evidence has been accruing in the last two decades of the importance of L-AA in protecting not only the plant from oxidative stress, but also mammals from various chronic diseases that have their origins in oxidative stress. Evidence suggests that the plasma levels of L-AA in large sections of the population are sub-optimal for the health protective effects of this vitamin. Until quite recently, little focus has been given to improving the L-AA content of plant foods, either in terms of the amounts present in commercial crop varieties, or in minimising losses prior to ingestion. Further, while L-AA biosynthesis in animals was elucidated in the 1960s, 1 it is only very recently that a distinct biosynthetic route for plants has been proposed. 2 The characterisation of this new pathway will undoubtedly provide the necessary focus and impetus to enable fundamental questions on plant L-AA metabolism to be resolved. This review focuses on the role of L-AA in metabolism and the latest studies regarding its bio- synthesis, tissue compartmentalisation, turnover and catabolism. These inter-relationships are considered in relation to the potential to improve the L-AA content of crops. Methodology for the reliable analysis of L-AA in plant foods is briefly reviewed. The concentrations found in common food sources and the effects of processing, or storage prior to consumption are discussed. Finally the factors that determine the bioavailability of L-AA and how it may be improved are considered, as well as the most important future research needs. # 2000 Society of Chemical Industry

The public release of performance data: what do we expect to gain? A review of the evidence.

Abstract: ContextInformation about the performance of hospitals, health professionals, and health care organizations has been made public in the United States for more than a decade. The expected gains of public disclosure have not been made clear, and both the benefits and potential risks have received minimal empirical investigation.ObjectiveTo summarize the empirical evidence concerning public disclosure of performance data, relate the results to the potential gains, and identify areas requiring further research.Data SourcesA literature search was conducted on MEDLINE and EMBASE databases for articles published between January 1986 and October 1999 in peer-reviewed journals. Review of citations, public documents, and expert advice was conducted to identify studies not found in the electronic databases.Study SelectionDescriptive, observational, or experimental evaluations of US reporting systems were selected for inclusion.Data ExtractionIncluded studies were organized based on use of public data by consumers, purchasers, physicians, and hospitals; impact on quality of care outcomes; and costs.Data SynthesisSeven US reporting systems have been the subject of published empirical evaluations. Descriptive and observational methods predominate. Consumers and purchasers rarely search out the information and do not understand or trust it; it has a small, although increasing, impact on their decision making. Physicians are skeptical about such data and only a small proportion makes use of it. Hospitals appear to be most responsive to the data. In a limited number of studies, the publication of performance data has been associated with an improvement in health outcomes.ConclusionsThere are several potential gains from the public disclosure of performance data, but use of the information by provider organizations for quality improvement may be the most productive area for further research.

Ascorbic acid in plants: biosynthesis and function.

Abstract: Ascorbic acid (vitamin C) is an abundant component of plants. It reaches a concentration of over 20 mM in chloroplasts and occurs in all cell compartments, including the cell wall. It has proposed functions in photosynthesis as an enzyme cofactor (including synthesis of ethylene, gibberellins and anthocyanins) and in control of cell growth. A biosynthetic pathway via GDP-mannose, GDP-L-galactose, L-galactose, and L-galactono-1,4-lactone has been proposed only recently and is supported by molecular genetic evidence from the ascorbate-deficient vtc 1 mutant of Arabidopsis thaliana. Other pathways via uronic acids could provide minor sources of ascorbate. Ascorbate, at least in some species, is a precursor of tartrate and oxalate. It has a major role in photosynthesis, acting in the Mehler peroxidase reaction with ascorbate peroxidase to regulate the redox state of photosynthetic electron carriers and as a cofactor for violaxanthin de-epoxidase, an enzyme involved in xanthophyll cycle-mediated photoprotection. The hypersensitivity of some of the vtc mutants to ozone and UV-B radiation, the rapid response of ascorbate peroxidase expression to (photo)-oxidative stress, and the properties of transgenic plants with altered ascorbate peroxidase activity all support an important antioxidative role for ascorbate. In relation to cell growth, ascorbate is a cofactor for prolyl hydroxylase that posttranslationally hydroxylates proline residues in cell wall hydroxyproline-rich glycoproteins required for cell division and expansion. Additionally, high ascorbate oxidase activity in the cell wall is correlated with areas of rapid cell expansion. It remains to be determined if this is a causal relationship and, if so, what is the mechanism. Identification of the biosynthetic pathway now opens the way to manipulating ascorbate biosynthesis in plants, and, along with the vtc mutants, this should contribute to a deeper understanding of the proposed functions of this multifaceted molecule.

Auxetic behavior from rotating squares

Abstract: Auxetic materials exhibit the very unusual properties of becoming wider when stretched and narrower when squashed [1], that is they have negative Poisson’s ratios. Apart from the pure scientific interest of having materials showing such an unconventional property, a negative Poisson’s ratio gives a material several other beneficial effects such as an increased shear stiffness, an increased plane strain fracture toughness and an increased indentation resistance. These properties make auxetics superior to conventional materials for many practical applications [1, 2]. In recent years several auxetics have been fabricated by modifying the microstructure of existing materials, including foams [2] and microporous polymers [3]. A number of molecular auxetics have also been proposed [4–9] one example being α-cristobalite [7]. The auxetic behavior in these materials can be explained in terms of their geometry and deformation mechanism. Thus, the hunt for new auxetic materials is frequently approached through searching for geometric features which may give such behavior [9, 10]. In this letter we present a new mechanism to achieve a negative Poisson’s ratio. This is based on an arrangement involving rigid squares connected together at their vertices by hinges as illustrated in Fig. 1. This may be viewed as a two dimensional arrangement of squares or as a projection of a particular plane of a three dimensional structure. This latter type of geometry is commonly found in inorganic crystalline materials [8, 9, 11]. Referring to Fig. 1, for squares of side length “l” at an angle θ to each other, the dimensions of the unit cell in the Oxi directions are given by:

Prevalence of use of complementary/alternative medicine: a systematic review.

Abstract: Reported are the results of a systematic review of the prevalence of use of complementary/alternative medicine. Computerized literature searches were carried out in four databases. Twelve surveys thus found were selected because they dealt with the utilization of complementary/alternative medicine in random or representative samples of the general population. Data were extracted in a predefined, standardized way. Prevalence of use of complementary/alternative medicine ranged from 9% to 65%. Even for a given form of treatment such as chiropractic, as used in the USA, considerable discrepancies emerged. The data suggest that complementary/alternative therapies are used frequently and increasingly. Prevalence of use seemed to depend critically on factors that were poorly controlled in surveys of complementary/alternative medicine. The true prevalence of use of complementary/alternative medicine in the general population remains uncertain.

Thinking with Bourdieu Against Bourdieu: A ‘Practical’ Critique of the Habitus

Abstract: There are two strands in Bourdieu's sociological writings. On the one hand, Bourdieu argues for a theoretical position one might term his “practical theory” which emphasizes virtuosic interactions between individuals. On the other hand, and most frequently, Bourdieu appeals to the concept of the habitus according to which society consists of objective structures and determined—and isolated—individuals. Although Bourdieu believes that the habitus is compatible with his practical theory and overcomes the impasse of objectivism and subjectivism in social theory, neither claim is the case; the habitus is incompatible with his practical theory, and it retreats quickly into objectivism. However, Bourdieu's practical theory does offer a way out of the impasse of objectivism and subjectivism by focussing on the intersubjective interactions between individuals.

Ecological gradients, subdivisions and terminology of north‐west European mires

Abstract: Summary 1 The historical development of mire ecology and terminology is reviewed in relation to evolving concepts and perceptions, and the diverse schools and traditions of vegetation and habitat description and research. 2 Most ecological and floristic variation within north-west European mire vegetation is accounted for by three ecological gradients: the acid base-poor vs. neutral, base- and bicarbonate-rich gradient; the gradient in fertility related to availability of the limiting nutrient elements N and P; and the water level gradient. EAects of salinity and the spring‐flush‐fen gradients are of more local significance, usually easily recognized. Land use is an important additional factor. 3 The mineral-soil-water limit between ombrotrophic and minerotrophically influenced sites is not sharp, and cannot be related to consistent diAerences in either vegetation or water chemistry. It should be abandoned as a general main division within mires. 4 The most important natural division is between ‘bog’, with pH generally 6.0, high Ca 2a and HCO3 ‐ , vegetation rich in dicotyledonous herbs and ‘brown mosses’. This division is reflected in a bimodal distribution of pH. 5 The terms oligotrophic, mesotrophic and eutrophic should refer only to nutrient richness (fertility, mainly N and P), not to base richness (metallic cations and pH). 6 It is recommended that ‘mire’ should embrace both wetlands on peat and related communities on mineral soils, that ‘bog’ (unqualified) should encompass both ombrotrophic and weakly minerotrophic mires, including ‘bog woodland’, and that ‘fen’ should be restricted to base-rich mires but include both herbaceous and wooded vegetation (‘fen carr’). 7 Definitions are given for a range of broadly defined categories that should cover most vegetation types commonly encountered. The relation of these to British national vegetation classification types and to major units in European phytosociology is outlined.

MAP kinase and protein kinase A-dependent mobilization of triacylglycerol and glycogen during appressorium turgor generation by Magnaporthe grisea.

Abstract: Magnaporthe grisea produces an infection structure called an appressorium, which is used to breach the plant cuticle by mechanical force. Appressoria generate hydrostatic turgor by accumulating molar concentrations of glycerol. To investigate the genetic control and biochemical mechanism for turgor generation, we assayed glycerol biosynthetic enzymes during appressorium development, and the movement of storage reserves was monitored in developmental mutants. Enzymatic activities for glycerol generation from carbohydrate sources were present in appressoria but did not increase during development. In contrast, triacylglycerol lipase activity increased during appressorium maturation. Rapid glycogen degradation occurred during conidial germination, followed by accumulation in incipient appressoria and dissolution before turgor generation. Lipid droplets also moved to the incipient appressorium and coalesced into a central vacuole before degrading at the onset of turgor generation. Glycogen and lipid mobilization did not occur in a Δpmk1 mutant, which lacked the mitogen-activated protein kinase (MAPK) required for appressorium differentiation, and was retarded markedly in a ΔcpkA mutant, which lacks the catalytic subunit of cAMP-dependent protein kinase A (PKA). Glycogen and lipid degradation were very rapid in a Δmac1 sum1-99 mutant, which carries a mutation in the regulatory subunit of PKA, occurring before appressorium morphogenesis was complete. Mass transfer of storage carbohydrate and lipid reserves to the appressorium therefore occurs under control of the PMK1 MAPK pathway. Turgor generation then proceeds by compartmentalization and rapid degradation of lipid and glycogen reserves under control of the CPKA/SUM1-encoded PKA holoenzyme.

Efficacy of ginger for nausea and vomiting: a systematic review of randomized clinical trials.

Abstract: Ginger (Zingiber officinale) is often advocated as beneficial for nausea and vomiting. Whether the herb is truly efficacious for this condition is, however, still a matter of debate. We have performed a systematic review of the evidence from randomized controlled trials for or against the efficacy of ginger for nausea and vomiting. Six studies met all inclusion criteria and were reviewed. Three on postoperative nausea and vomiting were identified and two of these suggested that ginger was superior to placebo and equally effective as metoclopramide. The pooled absolute risk reduction for the incidence of postoperative nausea, however, indicated a non-significant difference between the ginger and placebo groups for ginger 1 g taken before operation (absolute risk reduction 0.052 (95% confidence interval -0.082 to 0.186)). One study was found for each of the following conditions: seasickness, morning sickness and chemotherapy-induced nausea. These studies collectively favoured ginger over placebo.

Time-integrated sampling of fluvial suspended sediment: a simple methodology for small catchments

Abstract: Fine-grained (<62·5 µm) suspended sediment transport is a key component of the geochemical flux in most fluvial systems. The highly episodic nature of suspended sediment transport imposes a significant constraint on the design of sampling strategies aimed at characterizing the biogeochemical properties of such sediment. A simple sediment sampler, utilizing ambient flow to induce sedimentation by settling, is described. The sampler can be deployed unattended in small streams to collect time-integrated suspended sediment samples. In laboratory tests involving chemically dispersed sediment, the sampler collected a maximum of 71% of the input sample mass. However, under natural conditions, the existence of composite particles or flocs can be expected to increase significantly the trapping efficiency. Field trials confirmed that the particle size composition and total carbon content of the sediment collected by the sampler were representative statistically of the ambient suspended sediment. Copyright © 2000 John Wiley & Sons, Ltd.

Structural colour: Colour mixing in wing scales of a butterfly

Abstract: Green coloration in the animal kingdom, as seen in birds' feathers and reptile integument, is often an additive mixture of structurally effected blue and pigmentary yellow1. Here we investigate the origin of the bright green coloration of the wing scales of the Indonesian male Papilio palinurus butterfly, the microstructure of which generates an extraordinary combination of both yellow and blue iridescence. The dual colour arises from a modulation imposed on the multilayer, producing the blue component as a result of a previously undiscovered retro-reflection process.

Learning Careers: Continuity and change in young people's dispositions to learning

Abstract: Despite an extensive literature on the subject of learning, very little has been written about the ways in which young people's dispositions to learning transform over time. This article draws upon a longitudinal research project which focused on such transformations. The article centres on the case of Amanda Ball and considers the implications which her story holds for our understanding of learning. It is shown that dispositions can transform in a short period of time and that such transformations are often linked, in complex ways, to wider social, economic and cultural contexts.

Ascorbate biosynthesis and function in photoprotection

Abstract: Ascorbate (vitamin C) can reach very high concentrations in chloroplasts (20-300 mM). The pool size in leaves and chloroplasts increases during acclimation to high light intensity and the highest concentrations recorded are in high alpine plants. Multiple functions for ascorbate in photosynthesis have been proposed, including scavenging of active oxygen species generated by oxygen photoreduction and photorespiration, regeneration of alpha-tocopherol from alpha-tocopheryl radicals, cofactor for violaxanthin de-epoxidase and donation of electrons to photosystem II. Hydrogen peroxide scavenging is catalysed by ascorbate peroxidase (Mehler peroxidase reaction) and the subsequent regeneration of ascorbate by reductant derived from photosystem I allows electron flow in addition to that used for CO2 assimilation. Ascorbate is synthesized from guanosine diphosphate-mannose via L-galactose and L-galactono-1,4-lactone. The last step, catalysed by L-galactono-1,4-lactone dehydrogenase, is located on the inner mitochondrial membrane and uses cytochrome c as electron acceptor. L-galactono-1,4-lactone oxidation to ascorbate by intact leaves is faster in high-light acclimated leaves and is also enhanced by high light, suggesting that this step contributes to the control of pool size by light. Ascorbate-deficient Arabidopsis thaliana vtc mutants are hypersensitive to a number of oxidative stresses including ozone and ultraviolet B radiation. Further investigation of these mutants shows that they have reduced zeaxanthin-dependent non-photochemical quenching, confirming that ascorbate is the cofactor for violaxanthin de-epoxidase and that availability of thylakoid lumen ascorbate could limit this reaction. The vtc mutants are also more sensitive to photo-oxidation imposed by combined high light and salt treatments.

A stable non-classical metallofullerene family

Abstract: In the evolving field of fullerenes, nanotubes and endohedral metallofullerenes, the isolated-pentagon rule (IPR)1 is sacrosanct — exceptions have been predicted2,3, but no bare carbon cages with adjacent pentagons have been characterized. Small organic molecules with metal-stabilized fused five-membered rings (pentalenes) have been created4, however, and here we describe a family of non-classical endohedral metallofullerenes with the general structure AxSc3−xN@C68 (where x = 0–2, A is a rare-earth metal, Sc is scandium and N is nitrogen) that has a non-IPR cage of only 68 carbon atoms containing annelated five-membered rings. This internal ring network is metal-stabilized and is accessible for external organic reaction chemistry.

Garlic for treating hypercholesterolemia. A meta-analysis of randomized clinical trials.

Abstract: The available data suggest that garlic is superior to placebo in reducing total cholesterol levels. However, the size of the effect is modest, and its robustness is debatable. The use of garlic for...

Aromatherapy: A systematic review

Abstract: Aromatherapy is becoming increasingly popular; however there are few clear indications for its use. To systematically review the literature on aromatherapy in order to discover whether any clinical indication may be recommended for its use, computerised literature searches were performed to retrieve all randomised controlled trials of aromatherapy from the following databases: MEDLINE, EMBASE, British Nursing Index, CISCOM, and AMED. The methodological quality of the trials was assessed using the Jadad score. All trials were evaluated independently by both authors and data were extracted in a pre-defined, standardised fashion. Twelve trials were located: six of them had no independent replication; six related to the relaxing effects of aromatherapy combined with massage. These studies suggest that aromatherapy massage has a mild, transient anxiolytic effect. Based on a critical assessment of the six studies relating to relaxation, the effects of aromatherapy are probably not strong enough for it to be considered for the treatment of anxiety. The hypothesis that it is effective for any other indication is not supported by the findings of rigorous clinical trials.

Peer-led and adult-led school health education: a critical review of available comparative research

Abstract: Peer-led health education in school is widely used. Advocates suggest it is an effective method based on the belief that information, particularly sensitive information, is more easily shared between people of a similar age. Critics suggest that this is a method not based on sound theory or evidence of effectiveness. This review evaluates school-based health education programmes which have set out to compare the effects of peers or adults delivering the same material. The identified studies indicated that peer leaders were at least as, or more, effective than adults. Although this suggests that peerled programmes can be effective, methodological difficulties and analytical problems indicate that this is not an easy area to investigate, and research so far has not provided a definitive answer.

Electronic conductivity of solid-state, mixed-valent, monolayer-protected Au clusters

Abstract: Electronic conductivity, σEL, in solid-state films of alkanethiolate monolayer protected Au clusters (Au MPCs) occurs by a bimolecular, electron self-exchange reaction, whose rate constant is controlled by (a) the core-to-core tunneling of electronic charge along alkanethiolate chains and (b) the mixed valency of the MPC cores (e.g., a mixture of cores with different electronic charges). The tunneling mechanism is demonstrated by an exponential relation between the electronic conductivity of Au309(Cn)92 MPCs (average composition) and n, the alkanethiolate chainlength, which varies from 4 to 16. The electron tunneling coefficient βn = 1.2/CH2 or, after accounting for alkanethiolate chain interdigitation, βdis = 0.8 A-1. Quantized electrochemical double layer charging of low polydispersity Au140(C6)53 MPCs was used to prepare solutions containing well-defined mixtures of MPC core electronic charges (such as MPC0 mixed with MPC1+). Electronic conductivities of mixed-valent, solid-state Au140(C6)53 MPC films ...

Förster energy transfer in an optical microcavity.

Abstract: By studying the transfer of excitation energy between dye molecules confined within an optical microcavity, we demonstrate experimentally that Forster energy transfer is influenced by the local photonic mode density. Locating donor and acceptor molecules at well-defined positions allows the transfer rate to be determined as a function of both mutual separation and cavity length. The results show that the Forster transfer rate depends linearly on the donor emission rate and hence photonic mode density, providing the potential to control energy transfer by modification of the optical environment.

LDA Calculations Using a Basis of Gaussian Orbitals

Abstract: In this paper we will consider some of the methods involved in carrying out density functional calculations within the framework of localised basis sets, specifically those of Gaussian type orbitals. Particular emphasis is placed on the methods used in the AIMPRO (Ab Initio Modelling PROgram) code, but mention is made of a number of developments and strategies used in other programs.

Do Zeolites Have Negative Poisson's Ratios?

Abstract: Consequently, the size of the resulting nanoparticles matches the dimension of the nanometer-sized cavities inside these swollen domains. The possibility of controlling the growth of the metal nanoclusters by changing the morphological features of the support represents a unique feature of resin supports, in which the metal nanoparticles are generated inside the swollen polymer network and not simply at its surface. It can be inferred that functional resins characterized by a narrower distribution of nanoporous domains will make it possible to control even more precisely the size and size distribution of the metal nanoclusters generated inside them, a task that we are going to turn to in the near future.

The role of complementary and alternative medicine

Abstract: Based on a presentation from the Millennium Festival of Medicine Complementary and alternative medicine is defined as “diagnosis, treatment and/or prevention which complements mainstream medicine by contributing to a common whole, by satisfying a demand not met by orthodoxy or by diversifying the conceptual frameworks of medicine.”1 It comprises a confusingly large and heterogeneous array of techniques, with both therapeutic and diagnostic approaches (table 1). #### Summary points The one year prevalence for use of complementary and alternative medicine is around 20% and is predicted to rise Some of the reasons for this popularity amount to a biting criticism of conventional medicine At present much complementary and alternative medicine is still opinion based View this table: Table 1 Examples of techniques used in complementary and alternative medicine A recent telephone survey on the use of complementary and alternative medicine in the United Kingdom yielded a one year prevalence of 20%.14 Herbalism, aromatherapy, homoeopathy, acupuncture, massage, and reflexology were among the most popular. This level of use may seem impressive but, compared with other countries, it is low (figure). National differences are difficult to interpret. To some they indicate that in the United Kingdom complementary and alternative medicine will grow to match its popularity in Germany or France, where, contrary to the United Kingdom, it is mostly practised by medically trained doctors. One year prevalence of complementary and alternative medicine in various countries. Data based on surveys of random or representative samples of population The exact reasons for the popularity of complementary and alternative medicine are complex; they change with time and space, they may vary from therapy to therapy, and they are different from one individual to another—for example, a patient with AIDS will have other motives than someone who is “worried well.” Reporting on complementary and alternative medicine in the British daily press is …