The uptake and utilisation of amino acids by mammals

Imperial Users onl

How non-linear scaling relations unify dwarf and giant elliptical galaxies

Dwarf elliptical galaxies are frequently excluded from bright galaxy samples because they do not follow the same linear relations in diagrams involving effective half light radii R_e or mean effective surface brightnesses _e. However, using two linear relations which unite dwarf and bright elliptical galaxies we explain how these lead to curved relations when one introduces either the half light radius or the associated surface brightness. In particular, the curved _e - R_e relation is derived here. This and other previously misunderstood curved relations, once heralded as evidence for a discontinuity between faint and bright elliptical galaxies at M_B ~ -18 mag, actually support the unification of such galaxies as a single population whose structure (i.e. stellar concentration) varies continuously with stellar luminosity and mass.Comment: 4 pages including 2 figures, to appear in "A Universe of dwarf galaxies", Conf. Proc. (Lyon, June 14-18, 2010

Predictions of leachate generation from minerals processing waste deposits

The minerals processing industry in South Africa produces significant tonnages of waste material which are disposed of commonly in dedicated waste depositories. These deposits pose a potential to pollute the environment if leachate is generated within the deposit and released to the surroundings. Leachate generation is generally investigated using laboratory columnar experiments which attempt to mimic the physical and chemical processes which occur in the deposit. These experiments, termed lysimeter experiments, are time consuming in that they typically last for at least a few months and can last for up to three years. Lysimeter experiments are also costly to conduct. Because of restrictions such as these, relatively few deposits have been characterised to determine the leachate which they generate and thus the risk which they pose to the environment. There is an urgent need to be able to estimate the environmental risks associated with existing waste deposits. The first step towards assessing this risk would be an ability to predict leachate generation within a specific deposit. Such an ability could be used to identify which of the existing deposits produce significant leachate and thus pose a potential hazard to the environment. Equally, if leachate generation from new deposits could be estimated as a function of waste material and characteristics of the waste deposit, this information could be used to improve the engineering design of waste deposits. The work presented in this thesis involved identifying suitable modelling strategies which could be used to determine leachate generation within waste deposits which contain waste material typical of that produced by the minerals processing industry. Two modelling strategies have been investigated. The first modelling strategy involved a macroscopic model in which all effects such as intrinsic chemical kinetics, intra-particle diffusion, external mass transfer and hydrodynamic considerations are lumped into a single parameter. The result of this approach is an effective reaction rate for the release of hazardous constituents from a volume element of the waste deposit. The effective reaction rate is determined by fitting the model to experimental data based on lysimeter tests. The main advantage of this model is that it eliminates the need for a detailed understanding of the individual factors which contribute to leachate generation. This model was investigated both for its inherent simplicity and for use in cases where insufficient information with respect to the intrinsic chemical reaction rates, intra-particle diffusion, external mass transfer or hydrodynamic aspects exist. The main disadvantage of this model is that it has a limited predictive ability in that the individual significance of any one factor which contributes to leachate generation cannot be determined. For this reason a second, more detailed model, termed the heterogenous columnar model, has also been investigated. The heterogenous columnar model describes the release of hazardous constituents at the single particle level and relates this information to the overall leachate generation within the deposit. This is achieved by calculating the release of hazardous constituents from the size distribution of particles to the bulk fluid between these particles. The release of hazardous constituents from individual particles is determined by making use of a particle-scale chemical reaction 'model. This particle-scale model is sufficiently detailed to be able to determine the relative contribution to the overall release of hazardous constituents from the particles of intrinsic chemical kinetics of the reactions to the effects of diffusion of the fluid reagent into each particle. The heterogenous columnar model can also be used to determine whether the effective rate of release of hazardous constituents from the particles (which include intrinsic kinetic and diffusional contributions) or the flow of fluid reagent through the deposit limits the release of hazardous constituents from the deposit. This information can be used to determine the main factors which affect the release of hazardous constituents from waste deposits and can thus be used to improve the design of waste deposits. Probably the most important attribute of the heterogenous columnar model is that methods have been investigated to determine the model parameters from a simple continuously stirred tank reactor (CSTR) type experiment. The ability of the heterogenous columnar. model to predict leaching behaviour has been investigated using data on precious metal leaching found in the literature. The results are encouraging in that the model can accurately predict the leaching behaviour of precious metals. A preliminary investigation into determining suitable particle-scale model parameters for a sample of waste from a CSTR experiment has been conducted. This too has yielded encouraging results. However, the application of using the heterogenous columnar model using these parameters to describe leachate generation within waste deposits or lysimeter experiments still needs to be demonstrated. Once the heterogenous columnar model has been verified against data pertaining to leachate generation from a waste deposit it may start to provide the minerals processing industry with the information which it so desperately requires in order to dispose of wastes in a manner which minimises the impact on the environment

The Don and Helen New Zealand election 2005: A media a-gender?

The media uses the technique of framing to process and package information in order to make sense of the material and present a news ‘story’ which is accessible to the audience. International research reports demonstrate a consistent ‘gendered’ framing of media coverage. ‘Gendering’ refers to the highlighting of a person’s gender, when this is not particularly relevant to the context. Usually gendering involves seeing the male as the norm, and the female as the remarkable. In terms of the media and politics, this gendering includes the under-representation of women politicians, an emphasis on their appearance, marital and maternal status, and personality rather than the policies and issues of debate. More recently, however, there is evidence that in some contexts the media is becoming less overtly biased in its representation of women politicians. While there are still many ways in which women are presented differently from their male counterparts, there is also some evidence that an emphasis on gender is initiated by the party campaigns rather than being a result of media agenda-setting

Guidelines for the management of the foot health problems associated with rheumatoid arthritis

Background. Rheumatoid arthritis (RA) as a chronic systemic disease, commonly affects the feet, impacting negatively on patients' quality of life. Specialist podiatrists have a prime role to play in the assessment and management of foot and ankle problems within this patient group. However, it has been identified that in many areas there is no specialist podiatry service, with many patients being managed by non‐specialist podiatrists. Therefore, the North West Clinical Effectiveness Group for the Foot in Rheumatic Diseases (NWCEG) identified the need to develop ‘practitioner facing’ guidelines for the management of specific foot health problems associated with RA. Methods. Members of a guideline development group from the NWCEG each reviewed the evidence for specific aspects of the assessment and management of foot problems. Where evidence was lacking, ‘expert opinion’ was obtained from the members of the NWCEG and added as a consensus on current and best practice. An iterative approach was employed, with the results being reviewed and revised by all members of the group and external reviewers before the final guideline document was produced. Results. The management of specific foot problems (callus, nail pathology, ulceration) and the use of specific interventions (foot orthoses, footwear, patient education, steroid injection therapy) are detailed and standards in relation to each are provided. A diagrammatic screening pathway is presented, with the aim of guiding nonspecialist podiatrists through the complexity of assessing and managing those patients with problems requiring input from a specialist podiatrist and other members of the rheumatology multidisciplinary team. Conclusion. This pragmatic approach ensured that the guidelines were relevant and applicable to current practice as ‘best practice’, based on the available evidence from the literature and consensus expert opinion. These guidelines provide both specialist and non‐specialist podiatrists with the essential and ‘gold standard’ aspects of managing people with RA‐related foot problems

Miscarriage, stillbirth and congenital malformation in the offspring of UK veterans of the first Gulf war.

OBJECTIVES: To assess whether the offspring of UK veterans of the first Gulf war are at increased risk of fetal death or congenital malformation. METHOD: This was a retrospective reproductive cohort study of UK Gulf war veterans and a demographically similar comparison group who were in service at the time but were not deployed to the Gulf. Reproductive history was collected by means of a validated postal questionnaire between 1998 and 2001. RESULTS: In all, 27 959 pregnancies reported by men and 861 pregnancies reported by women were conceived after the first Gulf war and before November 1997. The risk of reported miscarriage was higher among pregnancies fathered by Gulf war veterans than by non-Gulf war veterans (OR = 1.4, 95% CI: 1.3, 1.5). Stillbirth risk was similar in both groups. Male Gulf war veterans reported a higher proportion of offspring with any type of malformation than the comparison cohort (OR = 1.5, 95% CI: 1.3, 1.7). Examination by type of malformation revealed some evidence for increased risk of malformations of the genital system, urinary system (renal and urinary tract), and 'other' defects of the digestive system, musculo-skeletal system, and non-chromosomal (non-syndrome) anomalies. These associations were weakened when analyses were restricted to clinically confirmed conditions. There was little or no evidence of increased risk for other structural malformations, specific syndromes, and chromosomal anomalies. Among female veterans, no effect of Gulf war service was found on the risk of miscarriage. The numbers of stillbirths and malformations reported by women were too small to allow meaningful analyses. CONCLUSION: We found no evidence for a link between paternal deployment to the Gulf war and increased risk of stillbirth, chromosomal malformations, or congenital syndromes. Associations were found between fathers' service in the Gulf war and increased risk of miscarriage and less well-defined malformations, but these findings need to be interpreted with caution as such outcomes are susceptible to recall bias. The finding of a possible relationship with renal anomalies requires further investigation. There was no evidence of an association between risk of miscarriage and mothers' service in the gulf

Treatment Outcomes of Treatment-Naïve Hepatitis C Patients co-infected with HIV: a systematic review and meta-analysis of observational cohorts

Co-infection with Hepatitis C (HCV) and HIV is common and HIV accelerates hepatic disease progression due to HCV. However, access to HCV treatment is limited and success rates are generally poor