Showing papers by "University of Exeter published in 2002"

The genome sequence of Schizosaccharomyces pombe

Abstract: We have sequenced and annotated the genome of fission yeast (Schizosaccharomyces pombe), which contains the smallest number of protein-coding genes yet recorded for a eukaryote: 4,824. The centromeres are between 35 and 110 kilobases (kb) and contain related repeats including a highly conserved 1.8-kb element. Regions upstream of genes are longer than in budding yeast (Saccharomyces cerevisiae), possibly reflecting more-extended control regions. Some 43% of the genes contain introns, of which there are 4,730. Fifty genes have significant similarity with human disease genes; half of these are cancer related. We identify highly conserved genes important for eukaryotic cell organization including those required for the cytoskeleton, compartmentation, cell-cycle control, proteolysis, protein phosphorylation and RNA splicing. These genes may have originated with the appearance of eukaryotic life. Few similarly conserved genes that are important for multicellular organization were identified, suggesting that the transition from prokaryotes to eukaryotes required more new genes than did the transition from unicellular to multicellular organization.

Culture, corporate governance and disclosure in Malaysian corporations

Abstract: Evidence from research conducted on corporate accounting indicates that the interaction of environmental factors influences disclosure practices The purpose of this study is to examine the importance of various corporate governance and cultural (race and education) characteristics, in addition to firm-specific factors, as possible determinants of voluntary (non-mandatory accounting and non-accounting information) disclosures in the annual reports of Malaysian listed corporations The results of the regression analysis indicate significant associations (at the 5 per cent level) between two corporate governance variables ( viz chair who is a non-executive director and domination of family members on boards) and the extent of voluntary disclosure This finding has implications for corporate governance policy formulation by the Malaysian Institute of Corporate Governance (MISG) One cultural factor (proportion of Malay directors on the board) is significantly associated (at the 5 per cent level) with the extent of voluntary disclosure suggesting that governmental focus on culture may solicit a response to secrecy from those who feel threatened

Representation of the Gender of Human Faces by Infants: A Preference for Female

Abstract: Six experiments based on visual preference procedures were conducted to examine gender categorization of female versus male faces by infants aged 3 to 4 months. In experiment 1, infants familiarized with male faces preferred a female face over a novel male face, but infants familiarized with female faces divided their attention between a male face and a novel female face. Experiment 2 demonstrated that these asymmetrical categorization results were likely due to a spontaneous preference for females. Experiments 3 and 4 showed that the preference for females was based on processing of the internal facial features in their upright orientation, and not the result of external hair cues or higher-contrast internal facial features. While experiments 1 through 4 were conducted with infants reared with female primary caregivers, experiment 5 provided evidence that infants reared with male primary caregivers tend to show a spontaneous preference for males. Experiment 6 showed that infants reared with female primary caregivers displayed recognition memory for individual females, but not males. These results suggest that representation of information about human faces by young infants may be influenced by the gender of the primary caregiver.

Altered Sexual Maturation and Gamete Production in Wild Roach (Rutilus rutilus) Living in Rivers That Receive Treated Sewage Effluents

Abstract: Disruption in gonadal development of wild roach living in U.K. rivers receiving large volumes of treated sewage effluent is manifest in a variety of ways, ranging from malformation of the germ cells and/or reproductive ducts to altered gamete production. Intersex fish were also found to have an altered endocrine status and an elevated concentration of plasma vitellogenin. Gonadal growth was inhibited only in severely intersex fish, whereas progression of spermatogenesis was delayed in a large proportion of all intersex and exposed male fish. In contrast to the effects observed in the intersex and exposed male fish, the maturation of ovaries in female fish inhabiting effluent-contaminated rivers appeared to be less obviously affected, although a higher incidence of oocyte atresia was found in the effluent-exposed fish compared with the reference fish. A positive correlation was found between the proportion of female tissue in the gonads of intersex fish and their plasma vitellogenin concentration, suggesting that vitellogenin can be an indicator for the level of gonadal disruption in intersex roach. The estradiol-17β concentration in intersex fish was intermediate between the concentration found in males and females, and the plasma testosterone was between 2- and 3-fold higher in intersex fish compared with male fish. These data suggest a link between altered endocrine status in intersex and female fish and gonadal disruption. Spermiation was also affected in roach living in effluent-impacted rivers: a lower proportion of fish were found releasing sperm, and in those intersex fish that were spermiating, a reduced milt volume and a reduced sperm density were found. All intersex fish had malformations of the reproductive duct(s), and in severely affected fish, the ducts were occluded, thus preventing release of gametes. In view of the widespread occurrence of intersexuality in wild fish populations in rivers throughout the United Kingdom, assessment of the reproductive capabilities of these intersex roach is clearly needed to understand the impact of this phenomenon on roach fertility.

Wild Intersex Roach (Rutilus rutilus) Have Reduced Fertility

Abstract: Endocrine-disrupting chemicals, known to be present in the environment, have great potential for interfering with reproductive health in wildlife and humans. There is, however, little direct evidence that endocrine disruption has adversely affected fertility in any organism. In freshwater and estuarine fish species, for example, although a widespread incidence of intersex has been reported, it is not yet known if intersexuality influences reproductive success. The purpose of this study was, therefore, to determine gamete quality in wild intersex roach (Rutilus rutilus) by assessing sperm characteristics, fertilization success, and ability to produce viable offspring. The results clearly demonstrate that gamete production is reduced in intersex roach. A significantly lower proportion of moderately or severely feminized fish (17.4% and 33.3%, respectively) were able to release milt compared with normal male fish from contaminated rivers (in which 97.6% of the males were able to release milt), reference male fish (97.7%), or less severely feminized intersex fish (experiment 1: 85.8%, experiment 2: 97%). Intersex fish that did produce milt produced up to 50% less (in terms of volume per gram of testis weight) than did histologically normal male fish. Moreover, sperm motility (percentage of motile sperm and curvilinear velocity) and the ability of sperm to successfully fertilize eggs and produce viable offspring were all reduced in intersex fish compared with normal male fish. Male gamete quality (assessed using sperm motility, sperm density, and fertilization success) was negatively correlated with the degree of feminization in intersex fish (r = -0.603; P < 0.001) and was markedly reduced in severely feminized intersex fish by as much as 50% in terms of motility and 75% in terms of fertilization success when compared with either less severely feminized intersex fish or unaffected male fish. This is the first evidence documenting a relationship between the morphological effects (e.g., intersex) of endocrine disruption and the reproductive capabilities of any wild vertebrate. The results suggest that mixtures of endocrine-disrupting substances discharged into the aquatic environment could pose a threat to male reproductive health.

The risk-benefit profile of commonly used herbal therapies : Ginkgo, St. John's Wort, Ginseng, Echinacea, Saw Palmetto, and Kava

Abstract: Because use of herbal remedies is increasing, a risk-benefit profile of commonly used herbs is needed. This article provides a clinically oriented overview of the efficacy and safety of ginkgo, St. John's wort, ginseng, echinacea, saw palmetto, and kava. Wherever possible, assessments are based on systematic reviews of randomized clinical trials. Encouraging data support the efficacy of some of these popular herbal medicinal products, and the potential for doing good seems greater than that for doing harm. The published evidence suggests that ginkgo is of questionable use for memory loss and tinnitus but has some effect on dementia and intermittent claudication. St. John's wort is efficacious for mild to moderate depression, but serious concerns exist about its interactions with several conventional drugs. Well-conducted clinical trials do not support the efficacy of ginseng to treat any condition. Echinacea may be helpful in the treatment or prevention of upper respiratory tract infections, but trial data are not fully convincing. Saw palmetto has been shown in short-term trials to be efficacious in reducing the symptoms of benign prostatic hyperplasia. Kava is an efficacious short-term treatment for anxiety. None of these herbal medicines is free of adverse effects. Because the evidence is incomplete, risk-benefit assessments are not completely reliable, and much knowledge is still lacking.

High-Flavonol Tomatoes Resulting from the Heterologous Expression of the Maize Transcription Factor Genes LC and C1

Abstract: Flavonoids are a group of polyphenolic plant secondary metabolites important for plant biology and human nutrition. In particular flavonols are potent antioxidants, and their dietary intake is correlated with a reduced risk of cardiovascular diseases. Tomato fruit contain only in their peel small amounts of flavonoids, mainly naringenin chalcone and the flavonol rutin, a quercetin glycoside. To increase flavonoid levels in tomato, we expressed the maize transcription factor genes LC and C1 in the fruit of genetically modified tomato plants. Expression of both genes was required and sufficient to upregulate the flavonoid pathway in tomato fruit flesh, a tissue that normally does not produce any flavonoids. These fruit accumulated high levels of the flavonol kaempferol and, to a lesser extent, the flavanone naringenin in their flesh. All flavonoids detected were present as glycosides. Anthocyanins, previously reported to accumulate upon LC expression in several plant species, were present in LC/C1 tomato leaves but could not be detected in ripe LC/C1 fruit. RNA expression analysis of ripening fruit revealed that, with the exception of chalcone isomerase, all of the structural genes required for the production of kaempferol-type flavonols and pelargonidin-type anthocyanins were induced strongly by the LC/C1 transcription factors. Expression of the genes encoding flavanone-3'-hydroxylase and flavanone-3'5'-hydroxylase, which are required for the modification of B-ring hydroxylation patterns, was not affected by LC/C1. Comparison of flavonoid profiles and gene expression data between tomato leaves and fruit indicates that the absence of anthocyanins in LC/C1 fruit is attributable primarily to an insufficient expression of the gene encoding flavanone-3'5'-hydroxylase, in combination with a strong preference of the tomato dihydroflavonol reductase enzyme to use the flavanone-3'5'-hydroxylase reaction product dihydromyricetin as a substrate.

Whither Europeanization? Concept Stretching and Substantive Change

Abstract: This paper discusses the concept of Europeanization in the light of recent research on the impact of the European Union politics and policy. Conceptual analysis is preliminary to empirical analysis. Accordingly, I examine the risk of "concept stretching", discuss extension and intension of Europeanization, and propose a taxonomy to "unpack" the concept and organize empirical research. The explanation of Europeanization is based on mechanisms and variables that need further exploration, but some preliminary results are presented here. Further research should concentrate on the policy level (and its interaction with macro-structures) and seek cross-fertilization with theoretical policy analysis and international relations, thus avoiding the risk of intellectual segregation.

Quantitative assessment of skin layers absorption and skin reflectance spectra simulation in the visible and near-infrared spectral regions.

Abstract: We have simulated diffuse reflectance spectra of skin by assuming a wavelength-independent scattering coefficient for the different skin tissues and using the known wavelength dependence of the absorption coefficient of oxy- and deoxyhaemoglobin and water. A stochastic Monte Carlo method is used to convert the wavelength-dependent absorption coefficient and wavelength-independent scattering coefficient into reflected intensity. The absorption properties of skin tissues in the visible and near-infrared spectral regions are estimated by taking into account the spatial distribution of blood vessels, water and melanin content within distinct anatomical layers. The geometrical peculiarities of skin histological structure, degree of blood oxygenation and the haematocrit index are also taken into account. We demonstrate that when the model is supplied with reasonable physical and structural parameters of skin, the results of the simulation agree reasonably well with the results of in vivo measurements of skin spectra.

Conceptualizing agriculture: a critique of post-productivism as the new orthodoxy:

Abstract: It has become fashionable to conceptualize recent shifts in agrarian priorities as a ‘postproductivist’ transition from a previously ‘productivist’ agriculture. This notion became more popular throughout the 1990s as a way to capture in one convenient package the complex changes experienced by both the agricultural sector specifically and within rural areas more generally. However, the widespread and uncritical use of such an all-encompassing term is rather surprising given debates elsewhere in human geography on the rejection of dualistic thinking. Yet, in agricultural and rural studies, the active creation and reinforcement of a productivist/ post-productivist dualism has emerged as a means of explaining the uneven development of rural areas. This paper develops a critique of post-productivism to demonstrate its invalidity, presenting empirical evidence to refute five supposed characteristics relating to quality food, pluriactivity, sustainability, production dispersion and regulation. It is argued that future progress in agricultural research will only be made if post-productivism is abandoned. Effort should be refocused upon understanding deeper processes underpinning agricultural change using existing theoretical perspectives developed in human geography but which lack application in the agricultural context. Ecological modernization is provided as a brief exemplar of how such progress may be achieved.

The formation mechanism of brown dwarfs

Abstract: We present results from the first hydrodynamical star formation calculation to demonstrate that brown dwarfs are a natural and frequent product of the collapse and fragmentation of a turbulent molecular cloud. The brown dwarfs form via the fragmentation of dense molecular gas in unstable multiple systems and are ejected from the dense gas before they have been able to accrete to stellar masses. Thus, they can be viewed as 'failed stars'. Approximately three-quarters of the brown dwarfs form in gravitationally unstable circumstellar discs while the remainder form in collapsing filaments of molecular gas. These formation mechanisms are very efficient, producing roughly the same number of brown dwarfs as stars, in agreement with recent observations. However, because close dynamical interactions are involved in their formation, we find a very low frequency of binary brown dwarf systems (≤5 per cent) and that those binary brown dwarf systems that do exist must be close, ≤ 10 au. Similarly, we find that young brown dwarfs with large circumstellar discs (radii ≥ 10 au) are rare ( 5 per cent).

Does Federalism Lead to Excessively High Taxes

Abstract: The relative strengths of vertical and horizontal tax externalities turn on the balance between the interest responsiveness of the supply of savings and demand for capital, the extent to which immobile factors are taxed by the states, and the strength of preferences between federal and state expenditures. The vertical externality will dominate if the aggregate tax base of the federation is responsible to the state tax instrument. Tax interactions in federations are more complex than has often been supposed.

Interlocking Interactions, the Diffusion of Innovations in Health Care

Abstract: This article aims to provide a reassessment of the processes of diffusion of innovations into organizations, based on new empirical data. The focus of the article is the latter stages of the diffusion process. The article draws on the results of two studies, which examined the diffusion of innovations in health care in the UK. These projects were a matched pair of qualitative studies, using purposeful selections of comparative case studies. The results demonstrate the ambiguous, contested nature of new scientific knowledge. The highly interactive nature of diffusion, with active adopters is illustrated. There is no evidence of a single adoption decision. The science is socially mediated. The features of context and of actors interlock to influence diffusion.

Poikilohydry and homoihydry: antithesis or spectrum of possibilities?

Abstract: Summary Plants have followed two principal (and contrasting) strategies of adaptation to the irregular supply of water on land, which are closely bound up with scale. Vascular plants evolved internal transport from the soil to the leafy canopy (but their ‘homoihydry’ is far from absolute, and some are desiccation tolerant (DT)). Bryophytes depended on desiccation tolerance, suspending metabolism when water was not available; their cells are generally either fully turgid or desiccated. Desiccation tolerance requires preservation intact through drying–re-wetting cycles of essential cell components and their functional relationships, and controlled cessation and restarting of metabolism. In many bryophytes and some vascular plants tolerance is essentially constitutive. In other vascular plants (particularly poikilochlorophyllous species) and some bryophytes tolerance is induced by water stress. Desiccation tolerance is adaptively optimal on hard substrates impenetrable to roots, and on poor dry soils in seasonally dry climates. DT vascular plants are commonest in warm semiarid climates; DT mosses and lichens occur from tropical to polar regions. DT plants vary widely in their inertia to changing water content. Some mosses and lichens dry out and recover within an hour or less; vascular species typically respond on a time scale of one to a few days.

The Desktop Guide to Complementary and Alternative Medicine

Abstract: If you, like me, have ever puzzled over the Feldenkrais method, or wondered what is Qi gong then help is at hand. What the authors have done here is to bring together into a desk-top manual, with an accompanying CD-ROM, an account of the commoner types of complementary and alternative medicine (CAM) together with their own and others work, derived from systematic reviews, to examine its evidence base. By doing so they have provided a quick, accessible, guide for the practising clinician which should make it easier to discuss the issues with individuals seeking their advice or help in spotting when there might be, say, an interaction between a prescribed medicine and something obtained from a nonconventional source. With so many people resorting to nonprescribed preparations, if nothing else, their table of interactions between herbal remedies and anticoagulants is worth the price of the book. The section on herbal remedies will provide a quick answer to many of the commoner questions posed to pharmacologists and pharmacists. There are references throughout not only to the data backing up their conclusions but also giving entry points to references on most of the commoner forms of CAM. Whether it would be possible to quickly access some of these papers is debatable as a goodly number are in journals not stocked by most conventional medical libraries. What this book also does is to indicate where there is acceptable evidence for CAM, other areas where there remains doubt, and some where it can be rejected outright. The authors are not alone in this approach but they have made their conclusions readily accessible in the book and provided a CD where this information can be referred to rapidly. Plainly it is not possible to detail every modality of CAM in a book of this sort but the authors have been successful in producing a comprehensive and worthwhile guide that can be recommended to all clinicians, and to anybody else, who may want a readily accessible guide to the pitfalls and benefits of using complementary medicine – and medicines.

Shape recovery algorithms using level sets in 2-D/3-D medical imagery: a state-of-the-art review

Abstract: The class of geometric deformable models, also known as level sets, has brought tremendous impact to medical imagery due to its capability of topology preservation and fast shape recovery. In an effort to facilitate a clear and full understanding of these powerful state-of-the-art applied mathematical tools, the paper is an attempt to explore these geometric methods, their implementations and integration of regularizers to improve the robustness of these topologically independent propagating curves/surfaces. The paper first presents the origination of level sets, followed by the taxonomy of level sets. We then derive the fundamental equation of curve/surface evolution and zero-level curves/surfaces. The paper then focuses on the first core class of level sets, known as "level sets without regularizers." This class presents five prototypes: gradient, edge, area-minimization, curvature-dependent and application driven. The next section is devoted to second core class of level sets, known as "level sets with regularizers." In this class, we present four kinds: clustering-based, Bayesian bidirectional classifier-based, shape-based and coupled constrained-based. An entire section is dedicated to optimization and quantification techniques for shape recovery when used in the level set framework. Finally, the paper concludes with 22 general merits and four demerits on level sets and the future of level sets in medical image segmentation. We present applications of level sets to complex shapes like the human cortex acquired via MRI for neurological image analysis.

'French is the Language of Love and Stuff': Student perceptions of issues related to motivation in learning a foreign language

Abstract: This article reports on an investigation into the motivation of secondary school students in the South-west of England to learn foreign languages. A questionnaire was constructed based on a model derived from the motivation literature to examine students' responses on 16 constructs related to motivation. This was administered to 228 students in years 7, 8 and 9. The analysis revealed a decrease in motivation with age, and higher level of motivation among girls than boys. It also revealed a strikingly higher motivation to learn German than French, which was even more marked when the boys only were considered. These findings were further investigated using interviews. Both girls and boys were able to provide clear explanations for differences between the genders, as well as for the language differences. These included such aspects as French being considered feminine, it not being 'cool' for boys to be seen to make an effort at French, and the tendency for boys not to try at anything that appears to be tedious.

Subcritical solvothermal synthesis of condensed inorganic materials.

Abstract: The solvothermal method has recently been extended from zeolite synthesis to the formation of condensed inorganic solids, which find uses in diverse areas due to properties such as ionic-conductivity, solid-state magnetism, giant magnetoresistance, low thermal expansion and ferroelectricity. This offers specific advantages over the traditional ceramic synthetic routes to inorganic solids and these are highlighted with examples from the recent literature, and the efforts focussed on determining the formation mechanism of solids from the heterogeneous mixtures used in solvothermal procedures are discussed.

Panax ginseng: a systematic review of adverse effects and drug interactions.

Abstract: Panax ginseng C. A. Meyer is a perennial herb native to Korea and China and has been used as an herbal remedy in eastern Asia for thousands of years. Modern therapeutic claims refer to vitality, immune function, cancer, cardiovascular diseases, improvement of cognitive and physical performance and sexual function. A recent systematic review of randomised controlled trials found that the efficacy of ginseng root extract could not be established beyond doubt for any of these indications. In order to obtain a balanced assessment of the therapeutic value of P. ginseng it is also necessary to consider the safety profile. In view of the extremely widespread use of P. ginseng it seems important to ask whether this herbal medicine involves health risks for the consumer. This review was conducted as a systematic attempt to document and evaluate all the available safety data on P. ginseng root extracts. Systematic searches were performed in five electronic databases and the reference lists of all papers located were checked for further relevant publications. All articles containing original data on adverse events and drug interactions with P. ginseng were included. Information was also requested from 12 manufacturers of ginseng preparations, the spontaneous reporting schemes of the WHO and national drug safety bodies. No language restrictions were imposed. Data from clinical trials suggest that the incidence of adverse events with ginseng monopreparations is similar to that with placebo. The most commonly experienced adverse events are headache, sleep and gastrointestinal disorders. The possibility of more serious adverse events is indicated in isolated case reports and data from spontaneous reporting schemes; however, causality is often difficult to determine from the evidence provided. Combination products containing ginseng as one of several constituents have been associated with serious adverse events and even fatalities. Interpretation of these cases is difficult as ingredients other than P. ginseng may have caused the problems. Possible drug interactions have been reported between P. ginseng and warfarin, phenelzine and alcohol. Collectively, these data suggest that P. ginseng monopreparations are rarely associated with adverse events or drug interactions. The ones that are documented are usually mild and transient. Combined preparations are more often associated with such events but causal attribution is usually not possible.

A systematic review of systematic reviews of homeopathy

Abstract: Homeopathy remains one of the most controversial subjects in therapeutics. This article is an attempt to clarify its effectiveness based on recent systematic reviews. Electronic databases were searched for systematic reviews/meta-analysis on the subject. Seventeen articles fulfilled the inclusion/exclusion criteria. Six of them related to re-analyses of one landmark meta-analysis. Collectively they implied that the overall positive result of this meta-analysis is not supported by a critical analysis of the data. Eleven independent systematic reviews were located. Collectively they failed to provide strong evidence in favour of homeopathy. In particular, there was no condition which responds convincingly better to homeopathic treatment than to placebo or other control interventions. Similarly, there was no homeopathic remedy that was demonstrated to yield clinical effects that are convincingly different from placebo. It is concluded that the best clinical evidence for homeopathy available to date does not warrant positive recommendations for its use in clinical practice.

The formation of close binary systems by dynamical interactions and orbital decay

Abstract: We present results from the first hydrodynamical star formation calculation to demonstrate that close binary stellar systems (separations 10 au) need not be formed directly by fragmentation. Instead, a high frequency of close binaries can be produced through a combination of dynamical interactions in unstable multiple systems and the orbital decay of initially wider binaries. Orbital decay may occur as a result of gas accretion and/or the interaction of a binary with its circumbinary disc. These three mechanisms avoid the problems associated with the fragmentation of optically thick gas to form close systems directly. They also result in a preference for close binaries to have roughly equal-mass components because dynamical exchange interactions and the accretion of gas with high specific angular momentum drive mass ratios towards unity. Furthermore, because of the importance of dynamical interactions, we find that stars with greater masses ought to have a higher frequency of close companions, and that many close binaries ought to have wide companions. These properties are in good agreement with the results of observational surveys.

Validating a new non-penetrating sham acupuncture device: two randomised controlled trials

Abstract: For clinical trials of acupuncture, it would be desirable to have a sham procedure that is indistinguishable from the real treatment, yet inactive. A sham needle has been designed which telescopes instead of penetrating the skin. The Park Sham Device involves an improved method of supporting the sham needle and requires validation. The objective of these studies was to test whether the sham procedure using the new device was 1) indistinguishable from the same procedure using real needles in acupuncture naive subjects, and 2) inactive, where the specific needle sensation (de qi) is taken as a surrogate measure of activity. The studies were designed as subject and assessor blind, randomised controlled trials. Study 1) included 58 patients enrolled in a clinical trial of acupuncture for acute stroke. Study 2) included 63 healthy, acupuncture naive, adult volunteers. The interventions used were real or sham acupuncture using the Park Sham Device. Study 1) was set in a district general hospital, and study 2) in a university laboratory. The outcome measure in study 1) was the form of treatment that patients believed they had received. In study 2) the outcome measure was experience of de qi, as judged by three acupuncture experts. No patient in either group(study 1) believed he or she had been treated with the sham needle. In 40 volunteers (study 2) for whom experts achieved consensus, the relative risk of experiencing de qi with real acupuncture to that with sham acupuncture was 15.38 (95% CI 2.26 to 104.86). The inter-rater reliability of all 13 experts (study 2), calculated from their judgements on 10 subjects selected by randomisation, was 0.52 (95% CI 0.19 to 0.61). In conclusion, the results suggest that the procedure using the new device is indistinguishable from the same procedure using real needles in acupuncture naive subjects, and is inactive, where the specific needle sensation (de qi) is taken as a surrogate measure of activity. It is therefore a valid control for acupuncture trials. The findings also lend support to the existence of de qi, a major concept underlying traditional Chinese acupuncture.

An Analysis of Disclosure in the Annual Reports of U.K. and Dutch Companies

Abstract: This study adopts a comparative approach to assess the comprehensive‐ness of disclosure in the 1996 annual reports of United Kingdom (U.K.) and Dutch corporations. Although the two countries exhibit some similarities, there are important differences in legal systems, capital markets, and corporate governance mechanisms. The disclosure model developed is based on the main headings specified in the Fourth and Seventh European Union Directives. Based on this model, disclosure by U.K. companies is more comprehensive than by Dutch corporations and the difference is significant (5 percent level with two‐tailed test). Most of the key areas of disclosure are found to be more comprehensive in the U.K. than in The Netherlands. This is due to more stringent regulation in the U.K. than in The Netherlands where the approach is more flexible. The model is used to establish whether disclosure is related to a number of firm‐specific characteristics using regression analysis. The impact of size is the same for both countr...

Adulteration of Chinese herbal medicines with synthetic drugs: a systematic review

Abstract: The popularity of Chinese herbal medicines (CHMs) demands a critical analysis of safety issues. The aim of this systematic review is to summarize data regarding adulterations of CHMs with conventional drugs. Literature searches were carried out in six databases. Articles containing original data on adulterations were considered without language restrictions. Eighteen case reports, two case series and four analytical investigations were identified. The list of adulterants contains drugs associated with serious adverse effects like corticosteroids. In several instances, patients were seriously harmed. One report from Taiwan suggests that 24% of all samples were contaminated with at least one conventional pharmacological compound. It is concluded that adulteration of CHMs with synthetic drugs is a potentially serious problem which needs to be addressed by adequate regulatory measures.

The magnetic field and wind confinement of θ1 Orionis C

Abstract: We report the detection, through spectropolarimetric observations, of a strong dipolar magnetic field of presumably fossil origin at the surface of the very young O star theta (1) Ori C. The Stokes V signatures we detect are variable with time, the variations being consistent with rotational modulation. A detailed modelling of our observations indicates that this dipole field has an intensity of 1.1+/-0.1 kG and is inclined at 42degrees+/-6degrees with respect to the rotation axis (assumed to be inclined at 45degrees to the line of sight). We find, in particular, that the positive magnetic pole comes closest to the observer when the variable Halpha emission component observed on this star reaches maximum strength. This discovery represents the first definite detection of a magnetic field in an O star, as well as the first detection of a fossil field in a very young star.We also investigate in this paper the magnetic confinement of the radiatively driven wind of theta (1) Ori C in the context of the magnetically confined wind-shock model of Babel & Montmerle. In the case of theta (1) Ori C, this model predicts the formation of a large magnetosphere (extending as far as 2-3R *), consisting of a very hot post-shock region (with temperatures in excess of 10 MK and densities of about 10(10) -10(11) cm(-3) ) generated by the strong collision of the wind streams from both stellar magnetic hemispheres, as well as a dense cooling disc forming in the magnetospheric equator. We find that this model includes most of the physics required to obtain a satisfactory level of agreement with the extensive data sets available for theta (1) Ori C in the literature (and, in particular, with the recent X-ray data and the phase-resolved spectroscopic observations of ultraviolet and optical wind lines) provided that the mass-loss rate of theta (1) Ori C is at least 5 times smaller than that predicted by radiatively driven wind models. We finally show how new observations with the XMM or Chandra spacecraft could help us constrain this model much more tightly and thus obtain a clear picture of how magnetic fields can influence the winds of hot stars.

Reactive sulfur species: an emerging concept in oxidative stress.

Abstract: The ingredients of oxidative stress include a variety of reactive species such as reactive oxygen and reactive nitrogen species (ROS, RNS). While sulfur is usually considered as part of cellular antioxidant systems there is mounting evidence that reactive sulfur species (RSS) with stressor properties similar to the ones found in ROS are formed under conditions of oxidative stress. Thiols as well as disulfides are easily oxidised to sulfur species with sulfur in higher oxidation states. Such agents include thiyl radicals, disulfides, sulfenic acids and disulfide-S-oxides. They rapidly oxidise and subsequently inhibit thiol-proteins and enzymes and can be considered as a separate class of oxidative stressors providing new antioxidant drug targets.