Showing papers by "University of Reading published in 2002"

Approximate Bayesian computation in population genetics.

Abstract: We propose a new method for approximate Bayesian statistical inference on the basis of summary statistics. The method is suited to complex problems that arise in population genetics, extending ideas developed in this setting by earlier authors. Properties of the posterior distribution of a parameter, such as its mean or density curve, are approximated without explicit likelihood calculations. This is achieved by fitting a local-linear regression of simulated parameter values on simulated summary statistics, and then substituting the observed summary statistics into the regression equation. The method combines many of the advantages of Bayesian statistical inference with the computational efficiency of methods based on summary statistics. A key advantage of the method is that the nuisance parameters are automatically integrated out in the simulation step, so that the large numbers of nuisance parameters that arise in population genetics problems can be handled without difficulty. Simulation results indicate computational and statistical efficiency that compares favorably with those of alternative methods previously proposed in the literature. We also compare the relative efficiency of inferences obtained using methods based on summary statistics with those obtained directly from the data using MCMC.

Acrylamide is formed in the Maillard reaction

Abstract: Reports of the presence of acrylamide in a range of fried and oven-cooked foods have caused worldwide concern because this compound has been classified as probably carcinogenic in humans. Here we show how acrylamide can be generated from food components during heat treatment as a result of the Maillard reaction between amino acids and reducing sugars. We find that asparagine, a major amino acid in potatoes and cereals, is a crucial participant in the production of acrylamide by this pathway.

The CloudSat mission and the A-train: a new dimension of space-based observations of clouds and precipitation

Abstract: CloudSat is a satellite experiment designed to measure the vertical structure of clouds from space. The expected launch of CloudSat is planned for 2004, and once launched, CloudSat will orbit in formation as part of a constellation of satellites (the A-Train) that includes NASA's Aqua and Aura satellites, a NASA–CNES lidar satellite (CALIPSO), and a CNES satellite carrying a polarimeter (PARASOL). A unique feature that CloudSat brings to this constellation is the ability to fly a precise orbit enabling the fields of view of the CloudSat radar to be overlapped with the CALIPSO lidar footprint and the other measurements of the constellation. The precision and near simultaneity of this overlap creates a unique multisatellite observing system for studying the atmospheric processes essential to the hydrological cycle. The vertical profiles of cloud properties provided by CloudSat on the global scale fill a critical gap in the investigation of feedback mechanisms linking clouds to climate. Measuring these profi...

Introductory Econometrics for Finance

Abstract: A complete resource for finance students, this textbook presents the most common empirical approaches in finance in a comprehensive and well-illustrated manner that shows how econometrics is used in practice, and includes detailed case studies to explain how the techniques are used in relevant financial contexts. Maintaining the accessible prose and clear examples of previous editions, the new edition of this best-selling textbook provides support for the main industry-standard software packages, expands the coverage of introductory mathematical and statistical techniques into two chapters for students without prior econometrics knowledge, and includes a new chapter on advanced methods. Learning outcomes, key concepts and end-of-chapter review questions (with full solutions online) highlight the main chapter takeaways and allow students to self-assess their understanding. Online resources include extensive teacher and student support materials, including EViews, Stata, R, and Python software guides.

Role of soil microorganisms in improving P nutrition of plants

Abstract: Phosphorus (P) is one of the major plant growth-limiting nutrients although it is abundant in soils in both inorganic and organic forms. Phosphate solubilizing micro-organisms (PSMs) are ubiquitous in soils and could play an important role in supplying P to plants in a more environmentally friendly and sustainable manner. Although solubilization of P compounds by microbes is very common under laboratory conditions, results in the field have been highly variable. This variability has hampered the large-scale use of PSMs in agriculture. Many reasons have been suggested for this variability, but none of them have been extensively investigated. In spite of the importance of PSMs in agriculture, the detailed biochemical and molecular mechanisms of P solubilization are not known. Recent work in our laboratory has shown that the conditions employed to isolate PSMs do not reflect soil conditions and that PSMs capable of effectively releasing P from soil are not so highly abundant as was suggested in earlier studies. These studies have also indicated that the mineral phosphate solubilizing (mps) ability of microbes could be linked to specific genes, and that these genes are present even in non P solubilizing bacteria. Understanding the genetic basis of P solubilization could help in transforming more rhizosphere-competent bacteria into PSMs. Further research should also focus on the microbial solubilization of iron (Fe) and aluminum (Al) phosphates, as well as mobilization of the organic phosphate reserves present in the soils.

On the Nature of the Project as a Temporary Organization

Abstract: The nature of the project as a temporary organization is analysed from the perspective of organizational theory. This leads to a reassessment of the definition of a project. It is suggested that classical definitions of projects are not wrong, just incomplete. The project as a temporary organization is viewed here as a production function, as an agency for assigning resources to the management of change within the functional organization, and as an agency for managing uncertainty. The role of the project manager is also considered. The project manager is chief executive of the temporary organization, and thus their roles in objective setting and motivating team members are emphasized over their role in planning and executing work. Second, as manager of the agency, they are the agent of the owner (principal) and so a second hierarchy of management and control must be put in place to monitor their performance. These agency costs add to the cost of the project, but may also explain why professional recognition is so important to project managers.

New perspectives on the Northern Hemisphere winter storm tracks

Abstract: The aim of this paper is to explore the use of both an Eulerian and system-centered method of storm track diagnosis applied to a wide range of meteorological fields at multiple levels to provide a range of perspectives on the Northern Hemisphere winter transient motions and to give new insight into the storm track organization and behavior. The data used are primarily from the European Centre for Medium-Range Weather Forecasts reanalyses project extended with operational analyses to the period 1979–2000. This is supplemented by data from the National Centers for Environmental Prediction and Goddard Earth Observing System 1 reanalyses. The range of fields explored include the usual mean sea level pressure and the lower- and upper-tropospheric height, meridional wind, vorticity, and temperature, as well as the potential vorticity (PV) on a 330-K isentropic surface (PV330) and potential temperature on a PV = 2 PVU surface (θPV2). As well as reporting the primary analysis based on feature tracking, t...

Endocannabinoid levels in rat limbic forebrain and hypothalamus in relation to fasting, feeding and satiation: stimulation of eating by 2-arachidonoyl glycerol

Abstract: Endocannabinoids are implicated in appetite and body weight regulation. In rodents, anandamide stimulates eating by actions at central CB1 receptors, and hypothalamic endocannabinoids may be under the negative control of leptin. However, changes to brain endocannabinoid levels in direct relation to feeding or changing nutritional status have not been investigated. We measured anandamide and 2-arachidonoyl glycerol (2-AG) levels in feeding-associated brain regions of rats, during fasting, feeding of a palatable food, or after satiation. Endocannabinoid levels were compared to those in rats fed ad libitum, at a point in their daily cycle when motivation to eat was absent. Fasting increased levels of anandamide and 2-AG in the limbic forebrain and, to a lesser extent, of 2-AG in the hypothalamus. By contrast, hypothalamic 2-AG declined as animals ate. No changes were detected in satiated rats. Endocannabinoid levels in the cerebellum, a control region not directly involved in the control of food intake, were unaffected by any manipulation. As 2-AG was most sensitive to variation during feeding, and to leptin regulation in a previous study, we examined the behavioural effects of 2-AG when injected into the nucleus accumbens shell, a limbic forebrain area strongly linked to eating motivation. 2-AG potently, and dose-dependently, stimulated feeding. This effect was attenuated by the CB1 receptor antagonist SR141716. These findings provide the first direct evidence of altered brain levels of endocannabinoids, and of 2-AG in particular, during fasting and feeding. The nature of these effects supports a role for endocannabinoids in the control of appetitive motivation.

The Monopolization Hypothesis and the dispersal–gene flow paradox in aquatic organisms

Abstract: Many aquatic organisms rely on passive transport of resting stages for their dispersal. In this review, we provide evidence pointing to the high dispersal capacity of both animals (cladocerans, rotifers and bryozoans) and aquatic macrophytes inhabiting lentic habitats. This evidence includes direct observation of dispersal by vectors such as wind and waterfowl and the rapid colonization of new habitats. Such high dispersal capacity contrasts with the abundant evidence of pronounced genetic differentiation among neighbouring populations in many pond-dwelling organisms. We provide an overview of the potential mechanisms causing a discrepancy between high dispersal rates and reduced levels of gene flow. We argue that founder events combined with rapid local adaptation may underlie the striking patterns of genetic differentiation for neutral markers in many aquatic organisms. Rapid population growth and local adaptation upon colonization of a new habitat result in the effective monopolization of resources, yielding a strong priority effect. Once a population is locally adapted, the presence of a large resting propagule bank provides a powerful buffer against newly invading genotypes, so enhancing priority effects. Under this Monopolization Hypothesis, high genetic differentiation among nearby populations largely reflects founder events. Phylogeographic data support a scenario of low effective dispersal among populations and persistent effects of historical colonization in cyclical parthenogens. A comparison of patterns of gene flow in taxa with different life cycles suggests an important role of local adaptation in reducing gene flow among populations. We argue that patterns of regional genetic differentiation may often reflect historical colonization of new habitats rather than contemporary gene flow.

Consumer perception of organic food production and farm animal welfare

Abstract: This paper is derived from a larger scale project investigating consumer attitudes towards organic food in the UK. Presents focus group results on consumer perceptions, attitudes and behaviour in relation to two key interrelated food trends: organic food and animal welfare. The results indicate that consumers often confuse organic and free‐range products because they believe that “organic” is equivalent to “free‐range” food. Focus group discussions were conducted to identify the main beliefs and attitudes towards organic food of both organic and non‐organic food buyers. Results indicate that, although health and food safety concerns are the main motives for organic food purchases, ethical concerns, specifically in relation to standards of animal welfare, play a significant influencing role in the decision to purchase organic food. The results are consistent with parallel research into consumer concerns about animal welfare, which showed that consumers are primarily concerned about food safety issues. Furthermore, the research illustrates the central outcome that animal welfare is used by consumers as an indicator of other, more important product attributes, such as safety and the impact on health. Indeed, ethical considerations seem to motivate the purchase of organic food and free‐range products and, therefore, may be viewed as interrelated. However, such ethical frameworks are closely related, if not contingent upon, the quality of the product, which includes perceptions of higher standards of safety and healthiness. Based on the qualitative data, suggests that the organic market could take advantage of research on consumer motivation to buy free‐range products, by embodying ethical concerns as an indicator of product quality.

Aziridines: epoxides’ ugly cousins?

Abstract: Aziridines, the nitrogenous analogues of epoxides, have until recently excited far less interest amongst synthetic organic chemists than their oxygenated counterparts, with some justification. A range of reviews concerned with the physical properties, synthesis (asymmetric and otherwise), reactions and utility of aziridines exists; this review briefly summarizes the similarities and differences between oxiranes and their nitrogenated analogues, concentrating on the underlying properties of aziridines and recent developments in their chemistry. In addition to descriptions of the physical nature of aziridines, especially those features which underpin their utility as synthetic intermediates, the sections beneath describe reactions involving alkylative ring-opening and synthesis of aziridines.

Gastrointestinal Microflora Studies in Late-Onset Autism

Abstract: Some cases of late-onset (regressive) autism may involve abnormal flora because oral vancomycin, which is poorly absorbed, may lead to significant improvement in these children. Fecal flora of children with regressive autism was compared with that of control children, and clostridial counts were higher. The number of clostridial species found in the stools of children with autism was greater than in the stools of control children. Children with autism had 9 species of Clostridium not found in controls, whereas controls yielded only 3 species not found in children with autism. In all, there were 25 different clostridial species found. In gastric and duodenal specimens, the most striking finding was total absence of non-spore-forming anaerobes and microaerophilic bacteria from control children and significant numbers of such bacteria from children with autism. These studies demonstrate significant alterations in the upper and lower intestinal flora of children with late-onset autism and may provide insights into the nature of this disorder.

Atmospheric GCM Response to Extratropical SST Anomalies: Synthesis and Evaluation*

Abstract: The advances in our understanding of extratropical atmosphere‐ocean interaction over the past decade and a half are examined, focusing on the atmospheric response to sea surface temperature anomalies. The main goal of the paper is to assess what was learned from general circulation model (GCM) experiments over the recent two decades or so. Observational evidence regarding the nature of the interaction and dynamical theory of atmospheric anomalies forced by surface thermal anomalies is reviewed. Three types of GCM experiments used to address this problem are then examined: models with fixed climatological conditions and idealized, stationary SST anomalies; models with seasonally evolving climatology forced with realistic, time-varying SST anomalies; and models coupled to an interactive ocean. From representative recent studies, it is argued that the extratropical atmosphere does respond to changes in underlying SST although the response is small compared to internal (unforced) variability. Two types of interactions govern the response. One is an eddy-mediated process, in which a baroclinic response to thermal forcing induces and combines with changes in the position or strength of the storm tracks. This process can lead to an equivalent barotropic response that feeds back positively on the ocean mixed layer temperature. The other is a linear, thermodynamic interaction in which an equivalent-barotropic low-frequency atmospheric anomaly forces a change in SST and then experiences reduced surface thermal damping due to the SST adjustment. Both processes contribute to an increase in variance and persistence of low-frequency atmospheric anomalies and, in fact, may act together in the natural system.

Phenotypic Plasticity: Beyond Nature and Nurture

Abstract: The concept of phenotypic plasticity has been popular in evolutionary biology over the last two decades or so. It really provides something for the theoreticians to get their teeth into, lying, as it does, at the interface of physiology, morphology, behaviour and genetics, probably contributing significantly to the level of phenotypic variation noted in wild populations and influencing rates of evolution. As is so often the case in evolutionary biology, this is a field in which empiricists have struggled to keep up with the pace of theoretical development. Phenotypic plasticity research has produced controversy; how do the genes affecting the plastic response operate, indeed do genes for plasticity really exist, how should plasticity be described and quantified, and so on? This has provided the stuff for some fascinating conflicts in the scientific press and the development of a number of phenotypic plasticity ‘camps’. The appearance of Phenotypic Plasticity: Beyond Nature and Nurture by Massimo Pigliucci is timely. The study of phenotypic plasticity is probably due for new input and it is possible that this publication could provide the necessary stimulus. A comparison of this book with an earlier text by CD Schlichting and M Pigliucci (Phenotypic Evolution: A Reaction Norm Perspective, Sinauer, 1998) is inevitable. As expected, there is a fair amount of overlap in the material covered by the two books. However, Phenotypic Plasticity: Beyond Nature and Nurture gets my vote. I found it considerably easier to read and to digest the information provided. In fact, I would expect Phenotypic Plasticity to appeal to students at all levels of development and sophistication. The text is nicely laid out (although the reproduction of many of the figures is quite poor) and well written. After three chapters introducing phenotypic plasticity, Pigliucci presents separate chapters on genetics, molecular biology, developmental biology, ecology, behaviour, evolution and theoretical biology. One of the great strengths of the book is that Pigliucci is making real efforts to ensure that the subject moves forward by discussing lines of research that still need to be addressed. It is difficult to see how any student of phenotypic plasticity will be able to get by without a copy of this book on their shelf. In fact, I highly recommend Phenotypic Plasticity to anybody interested in evolution. It is a fascinating read and will not fail to stimulate new insight into this most important topic.

From DNA to Diversity: Molecular Genetics and the Evolution of Animal Design

Abstract: Bring home now the book enPDFd from dna to diversity molecular genetics and the evolution of animal design to be your sources when going to read. It can be your new collection to not only display in your racks but also be the one that can help you fining the best sources. As in common, book is the window to get in the world and you can open the world easily. These wise words are really familiar with you, isn't it?

Cosmic rays, clouds and climate

Abstract: Galactic cosmic rays could influence Earth's cloudiness by creating aerosol particles that prompt cloud formation. That possible effect looks to be smaller than thought, but the story won't end there.

The standard Gaussian model for block copolymer melts

Abstract: As a result of important advances over the last decade, block copolymer melts have become an excellent model system for studying fundamental phenomena associated with molecular self-assembly. During this time, good quantitative agreement has been achieved between theory and experiment in regards to equilibrium phase behaviour, and with it has emerged a thorough understanding in terms of simple intuitive explanations. The theoretical contributions to this effort are largely attributed to mean-field calculations on a standard Gaussian model. Here, we review this present understanding of block copolymer phase behaviour, the model and its underlying assumptions, the mean-field approximation and its limitations, and the attempts to incorporate fluctuation corrections. Rather than following the traditional rigorous derivations, we present slightly more intuitive and transparent ones in such a way to stress the close connection between the related calculations. In this way, we hope to provide a valuable introduction to block copolymer theory.

On metrics for comparing nondominated sets

Abstract: Evolutionary multiobjective optimization (EMO) boasts a proliferation of algorithms and benchmark problems. We need principled ways to compare the performance of different EMO algorithms, but this is complicated by the fact that the result of an EMO run is not a single scalar value, but a collection of vectors forming a nondominated set. Various metrics for nondominated sets have been suggested. We compare several, using the framework of 'outperformance relations' (Hansen and Jaszkiewicz, 1998). This enables us to criticize and contrast a variety of published metrics, leading to some recommendations on which seem most useful in practice.

Probiotics as modulators of the gut flora.

Abstract: Probiotic ingestion can be recommended as a preventative approach to maintaining the balance of the intestinal microflora and thereby enhance 'well-being'. Research into the use of probiotic intervention in specific illnesses and disorders has identified certain patient populations that may benefit from the approach. Undoubtedly, probiotics will vary in their efficacy and it may not be the case that the same results occur with all species. Those that prove most efficient will likely be strains that are robust enough to survive the harsh physico-chemical conditions present in the gastrointestinal tract. This includes gastric acid, bile secretions and competition with the resident microflora. A survey of the literature indicates positive results in over fifty human trials, with prevention/treatment of infections the most frequently reported output. In theory, increased levels of probiotics may induce a 'barrier' influence against common pathogens. Mechanisms of effect are likely to include the excretion of acids (lactate, acetate), competition for nutrients and gut receptor sites, immunomodulation and the formation of specific antimicrobial agents. As such, persons susceptible to diarrhoeal infections may benefit greatly from probiotic intake. On a more chronic basis, it has been suggested that some probiotics can help maintain remission in the inflammatory conditions, ulcerative colitis and pouchitis. They have also been suggested to repress enzymes responsible for genotoxin formation. Moreover, studies have suggested that probiotics are as effective as anti-spasmodic drugs in the alleviation of irritable bowel syndrome. The approach of modulating the gut flora for improved health has much relevance for the management of those with acute and chronic gut disorders. Other target groups could include those susceptible to nosocomial infections, as well as the elderly, who have an altered microflora, with a decreased number of beneficial microbial species. For the future, it is imperative that mechanistic interactions involved in probiotic supplementation be identified. Moreover, the survival issues associated with their establishment in the competitive gut ecosystem should be addressed. Here, the use of prebiotics in association with useful probiotics may be a worthwhile approach. A prebiotic is a dietary carbohydrate selectively metabolised by probiotics. Combinations of probiotics and prebiotics are known as synbiotics.

Population growth rate and its determinants: an overview.

Abstract: We argue that population growth rate is the key unifying variable linking the various facets of population ecology. The importance of population growth rate lies partly in its central role in forecasting future population trends; indeed if the form of density dependence were constant and known, then the future population dynamics could to some degree be predicted. We argue that population growth rate is also central to our understanding of environmental stress: environmental stressors should be defined as factors which when first applied to a population reduce population growth rate. The joint action of such stressors determines an organism's ecological niche, which should be defined as the set of environmental conditions where population growth rate is greater than zero (where population growth rate = r = log(e)(N(t+1)/N(t))). While environmental stressors have negative effects on population growth rate, the same is true of population density, the case of negative linear effects corresponding to the well-known logistic equation. Following Sinclair, we recognize population regulation as occurring when population growth rate is negatively density dependent. Surprisingly, given its fundamental importance in population ecology, only 25 studies were discovered in the literature in which population growth rate has been plotted against population density. In 12 of these the effects of density were linear; in all but two of the remainder the relationship was concave viewed from above. Alternative approaches to establishing the determinants of population growth rate are reviewed, paying special attention to the demographic and mechanistic approaches. The effects of population density on population growth rate may act through their effects on food availability and associated effects on somatic growth, fecundity and survival, according to a 'numerical response', the evidence for which is briefly reviewed. Alternatively, there may be effects on population growth rate of population density in addition to those that arise through the partitioning of food between competitors; this is 'interference competition'. The distinction is illustrated using a replicated laboratory experiment on a marine copepod, Tisbe battagliae. Application of these approaches in conservation biology, ecotoxicology and human demography is briefly considered. We conclude that population regulation, density dependence, resource and interference competition, the effects of environmental stress and the form of the ecological niche, are all best defined and analysed in terms of population growth rate.

Cholesterol assimilation by lactic acid bacteria and bifidobacteria isolated from the human gut.

Abstract: The objective of this study was to evaluate the effect of human gut-derived lactic acid bacteria and bifidobacteria on cholesterol levels in vitro. Continuous cultures inoculated with fecal material from healthy human volunteers with media supplemented with cholesterol and bile acids were used to enrich for potential cholesterol assimilators among the indigenous bacterial populations. Seven potential probiotics were found: Lactobacillus fermentum strains F53 and KC5b, Bifidobacterium infantis ATCC 15697, Streptococcus bovis ATCC 43143, Enterococcus durans DSM 20633, Enterococcus gallinarum, and Enterococcus faecalis. A comparative evaluation regarding the in vitro cholesterol reduction abilities of these strains along with commercial probiotics was undertaken. The degree of acid and bile tolerance of strains was also evaluated. The human isolate L. fermentum KC5b was able to maintain viability for 2 h at pH 2 and to grow in a medium with 4,000 mg of bile acids per liter. This strain was also able to remove a maximum of 14.8 mg of cholesterol per g (dry weight) of cells from the culture medium and therefore was regarded as a candidate probiotic.

Effects of consumption of probiotics and prebiotics on serum lipid levels in humans.

Abstract: The objective of this article is to review existing studies concerning the effects of probiotics and prebiotics on serum cholesterol concentrations, with particular attention on the possible mechanisms of their action. Although not without exception, results from animal and human studies suggest a moderate cholesterol-lowering action of dairy products fermented with appropriate strain(s) of lactic acid bacteria and bifidobacteria. Mechanistically, probiotic bacteria ferment food-derived indigestible carbohydrates to produce short-chain fatty acids in the gut, which can then cause a decrease in the systemic levels of blood lipids by inhibiting hepatic cholesterol synthesis and/or redistributing cholesterol from plasma to the liver. Furthermore, some bacteria may interfere with cholesterol absorption from the gut by deconjugating bile salts and therefore affecting the metabolism of cholesterol, or by directly assimilating cholesterol. For prebiotic substances, the majority of studies have been done with the fructooligosaccharides inulin and oligofructose, and although convincing lipid-lowering effects have been observed in animals, high dose levels had to be used. Reports in humans are few in number. In studies conducted in normal-lipidemic subjects, two reported no effect of inulin or oligofructose on serum lipids, whereas two others reported a significant reduction in serum triglycerides (19 and 27%, respectively) with more modest changes in serum total and LDL cholesterol. At present, data suggest that in hyperlipidemic subjects, any effects that do occur result primarily in reductions in cholesterol, whereas in normal lipidemic subjects, effects on serum triglycerides are the dominant feature.

What motivates consumers to buy organic food in the UK?: Results from a qualitative study

Abstract: The aim of the overall project is to understand in depth the behavioural process of parents with respect to organic food. Its main objectives are to identify: beliefs, with respect to organic food, of parents who buy and do not buy organic food; the positive as well as negative attitudes towards organic food of those who buy and do not buy organic food; the impact of those attitudes on food choice for parents who buy and do not buy organic food; and to model the food choice behaviour of parents with respect to organic food. Employs both qualitative and quantitative methods. Reports the results of the second qualitative phase of the project which involved 40 laddering interviews, which were conducted in Reading, UK. The means‐end chain approach was used. The key idea is that product attributes are a means for consumers to obtain desired ends. Participants were parents with children aged 4‐12 years old, who were responsible for food purchases in their families and belonged to ABC1 class. The life values which were revealed mainly fall into three main broad categories. Consumers’ human, animal and environment centred values form the key motivating factors for organic food purchase. Both laddering and focus group interviews have generated certain hypotheses that are tested through the quantitative phase of the project, which uses a sample survey.

Enhancing the Learning of Sport Skills Through External-Focus Feedback

Abstract: The authors examined how the effectiveness of feedback for the learning of complex motor skills is affected by the focus of attention it induces. The feedback referred specifically either to body movements (internal focus) or to movement effects (external focus). In Experiment 1, groups of novices and advanced volleyball players (N = 48) practiced “tennis” serves under internal-focus or external-focus feedback conditions in a 2 (expertise) × 2 (feedback type) design. Type of feedback did not differentially affect movement quality, but external-focus feedback resulted in greater accuracy of the serves than internal-focus feedback during both practice and retention, independent of the level of expertise. In Experiment 2, the effects of relative feedback frequency as a function of attentional focus were examined. A 2 (feedback frequency: 100% vs. 33%) × 2 (feedback type) design was used. Experienced soccer players (N = 52) were required to shoot lofted passes at a target. External-focus feedback res...

Cultural differences in the online behavior of consumers

Abstract: Understanding how different cultures use the Net---as well as perceive the same Web sites---can translate to truly global e-commerce.

Prebiotic effects of inulin and oligofructose

Abstract: Prebiotics are non-digestible food ingredients that target certain components within the microbiota of the human large intestine. Efficient prebiotics need to have a specific fermentation therein and thereby have the ability to alter the faecal microflora composition towards a more 'beneficial' community structure. This should occur by the stimulation of benign or potentially health promoting genera but not the harmful groups. Because of their positive attributes bifidobacteria and lactobacilli are the most frequent target organisms. Both inulin and oligofructose have been demonstrated to be effective prebiotics. This has been shown through both in vitro and in vivo assessments in different laboratories. Because of their recognised prebiotic properties, principally the selective stimulation of colonic bifidobacteria, both inulin and oligofructose are increasingly used in new food product developments. Examples include drinks, yoghurts, biscuits and table spreads. Because of the recognised inhibitory effects that bifidobacteria can exert against gut pathogens, one of the most important aspects of prebiotic ingestion is fortification of the gut flora to resist acute infections.

Testing for genetic evidence of population expansion and contraction: an empirical analysis of microsatellite DNA variation using a hierarchical Bayesian model.

Abstract: The role of past climatic change in shaping the distributions of tropical rain forest vertebrates is central to long-standing hypotheses about the legacy of the Quaternary ice ages. One approach to testing such hypotheses is to use genetic data to infer the demographic history of codistributed species. Population genetic theory that relates the structure of allelic genealogies to historical changes in effective population size can be used to detect a past history of demographic expansion or contraction. The fruit bats Cynopterus sphinx and C. brachyotis (Chiroptera: Pteropodidae) exhibit markedly different distribution patterns across the Indomalayan region and therefore represent an exemplary species pair to use for such tests. The purpose of this study was to test alternative hypotheses about historical patterns of demographic expansion and contraction in C. sphinx and C. brachyotis using a coalescent-based analysis of microsatellite variation. Specifically, we used a hierarchical Bayesian model based on Markov chain Monte Carlo simulations to estimate the posterior distribution of genealogical and demographic parameters. The results revealed strong evidence for population contraction in both species. Evidence for a population contraction in C. brachyotis was expected on the basis of biogeographic considerations. However, similar evidence for population contraction in C. sphinx does not support the hypothesis that this species underwent a pronounced range expansion during the late Quaternary. Genetic evidence for population decline may reflect the consequences of habitat destruction on a more recent time scale.

Becoming Roman: The Origins of Provincial Civilization in Gaul. By G. Woolf. Cambridge University Press, Cambridge1998/2000. Pp. xv + 296, figs 20. Price: £40.00 (bound); £15.95 (paper). ISBN 0 521 414456 (bound); 0 521 789826 (paper).

Abstract: 1. On Romanization 2. Roman power and the Gauls 3. The civilising ethos 4. Mapping cultural change 5. Urbanising the Gauls 6. The culture of the countryside 7. Consuming Rome 8. Keeping faith? 9. Being Roman in Gaul.