847 research outputs found
The latest casualty: Phillip Knightley and media failure
He covers the coverage of wars and the fine borderline that journalists might cross to become propaganda merchants: World War II, Vietnam, The Gulf, Kosovo, to name a few, and now the âWar on Terrorâ. And the performance so far of the news media in this latest one has left Phillip Knightley, author of The First Casualty, underwhelmed: civil rights down the drain, public debate and dissent stifled, the news media hardly batting an eyelid. âWell, the press in Britain, Australia, and probably New Zealand, did a better job than their American counterparts,â he sighs, âbut thatâs not saying much.
The synthesis and potential applications of asymmetric silacycles
Although the use of silicon-based reagents has undergone rapid development during the last twenty years, the application of organosilicon chemistry to asymmetric synthesis has been somewhat slower to develop. The many problems associated with the use of 'Si-centred' chiral organosilicon compounds has led to the application of 'C-centred' chiral organosilicon compounds. This work has been aimed at the synthesis and application of cyclic silicon species. Routes towards the synthesis of medium-sized rings have been investigated as a potential application of enantiomerically pure silacycles. This work has led to the discovery of an unusual tandem cycloaddition-bond fragmentation reaction of 3-(dienylacyloxy)cycloalk-2- en-l-ones, which affords a-tetralone as the principal product. Most work has been directed at the synthesis of asymmetric silacycles. Two routes have been explored. Firstly, the double asymmetric hydrosilylation of dienes, catalysts based on many transition metals were used but little evidence of hydrosilylation was observed. The second route is that of the double asymmetric hydroboration of divinylsilanes. Asymmetric stoichiometric hydroboration led to products of moderate to high enantiomeric excess, whilst rhodium-catalysed hydroboration led to high yields of the achiral syn isomer. The diastereoselectivity has been found to vary according to the length of the tether between two phosphine ligands, with maximum diastereoselectivity being observed for butanodiphosphines. NMR studies have investigated the possibility that this is related to the stability of a divinylsilane-diphosphine rhodium complex. Finally, the formation of a variety of silacycles has been attempted. Boron- redistribution of the product of hydroboration with (-)-diisopinocampheylborane has been shown to occur with retention of stereochemistry and subsequent carbonylation led to the formation of asymmetric silacyclohexanones. Oxidation of the hydroboration product led to the formation of a silyldiol species. Reactions of this silyldiol have provided the basis for encouraging preliminary attempts at the formation of other heterosilacycles
The Lived Experience of Myocardial Infarction
This item is only available electronically.Cardiovascular diseases (CVDs) are a major cause of death and disability worldwide and
include diseases of the heart, vascular diseases of the brain and diseases of the blood vessels.
Coronary artery disease (CAD), a specific type of CVD, is a chronic disease which
encompasses stable and unstable periods. During unstable periods, vascular wall
inflammation and other manifestations of atherosclerosis may cause individuals to develop a
myocardial infarction (MI). MI may go undetected, be a minor event in a lifelong chronic
disease, or be a major catastrophic event leading to severe cardiac deterioration or sudden
cardiac death. Experiencing MI frequently alters an individualâs mental representation of self
and is often accompanied by mental health concerns including fear, anxiety, worry,
depression, grief and loss. Likewise, individuals who experience MI frequently endorse
concerns about the social and interpersonal impacts of the condition. Initial research has also
identified important variances in how men and women experience MI, with significant
implications for future prevention, treatment and rehabilitation. This review aims to identify,
analyse and synthesise existing knowledge about individualsâ experiences of MI and
comment on the gender differences highlighted within the literature.Thesis (M.Psych(Clinical)) -- University of Adelaide, School of Psychology, 201
Proton-proton collisions at the Large Hadron Collider's ALICE Experiment: diffraction and high multiplicity
Diffraction in pp collisions contributes approximately 30 % of the inelastic cross section. Its influence on the pseudorapidity density is not well constrained at high energy. A method to estimate the contributing fractions of diffractive events to the inelastic cross section has been developed, and the fractions are measured in the ALICE detector at 900 GeV (7 TeV) to be f=0.2780.055 (f=0.280.054) respectively. These results are compatible with recent ATLAS and ALICE measurements. Bjorkenâs energy density relation suggests that, in high multiplicity pp collisions at the LHC, an environment comparable to A-A collisions at RHIC could be produced. Such events are of great interest to the ALICE Collaboration. Constraints on the running conditions have been established for obtaining a high multiplicity pp data sample using the ALICE detectorâs multiplicity trigger. A model independent method to separate a multiplicity distribution from âpile-upâ contributions has been developed, and used in connection with other findings to establish a suitable threshold for a multiplicity trigger. It has been demonstrated data obtained under these conditions for 3 months can be used to conduct early strangeness analyses with multiplicities of over 5 times the mean. These findings have resulted in over 16 million high multiplicity events being obtained to date
Complex responses to movement-based disease control: when livestock trading helps
Livestock disease controls are often linked to movements between farms, for example, via quarantine and pre- or post-movement testing. Designing effective controls, therefore, benefits from accurate assessment of herd-to-herd transmission. Household models of human infections make use of R*, the number of groups infected by an initial infected group, which is a metapopulation level analogue of the basic reproduction number R0 that provides a better characterization of disease spread in a metapopulation. However, existing approaches to calculate R* do not account for individual movements between locations which means we lack suitable tools for livestock systems. We address this gap using next-generation matrix approaches to capture movements explicitly and introduce novel tools to calculate R* in any populations coupled by individual movements. We show that depletion of infectives in the source group, which hastens its recovery, is a phenomenon with important implications for design and efficacy of movement-based controls. Underpinning our results is the observation that R* peaks at intermediate livestock movement rates. Consequently, under movement-based controls, infection could be controlled at high movement rates but persist at intermediate rates. Thus, once control schemes are present in a livestock system, a reduction in movements can counterintuitively lead to increased disease prevalence. We illustrate our results using four important livestock diseases (bovine viral diarrhoea, bovine herpes virus, Johne's disease and Escherichia coli O157) that each persist across different movement rate ranges with the consequence that a change in livestock movements could help control one disease, but exacerbate another
The transfer of IgA from mucus to plasma and the implications for diagnosis and control of nematode infections
Immunoglobulin A (IgA) activity has been associated with reduced growth and fecundity of Teladorsagia circumcincta. IgA is active at the site of infection in the abomasal mucus. However, while IgA activity in abomasal mucus is not easily measured in live animals without invasive methods, IgA activity can be readily detected in the plasma, making it a potentially valuable tool in diagnosis and control. We used a Bayesian statistical analysis to quantify the relationship between mucosal and plasma IgA in sheep deliberately infected with T. circumcincta. The transfer of IgA depends on mucosal IgA activity as well as its interaction with worm number and size; together these account for over 80% of the variation in plasma IgA activity. By quantifying the impact of mucosal IgA and worm number and size on plasma IgA, we provide a tool that can allow more meaningful interpretation of plasma IgA measurements and aid the development of efficient control programmes
A Bayesian generalized random regression model for estimating heritability using overdispersed count data
Background:
Faecal egg counts are a common indicator of nematode infection and since it is a heritable trait, it provides a marker for selective breeding. However, since resistance to disease changes as the adaptive immune system develops, quantifying temporal changes in heritability could help improve selective breeding programs. Faecal egg counts can be extremely skewed and difficult to handle statistically. Therefore, previous heritability analyses have log transformed faecal egg counts to estimate heritability on a latent scale. However, such transformations may not always be appropriate. In addition, analyses of faecal egg counts have typically used univariate rather than multivariate analyses such as random regression that are appropriate when traits are correlated. We present a method for estimating the heritability of untransformed faecal egg counts over the grazing season using random regression.
Results:
Replicating standard univariate analyses, we showed the dependence of heritability estimates on choice of transformation. Then, using a multitrait model, we exposed temporal correlations, highlighting the need for a random regression approach. Since random regression can sometimes involve the estimation of more parameters than observations or result in computationally intractable problems, we chose to investigate reduced rank random regression. Using standard software (WOMBAT), we discuss the estimation of variance components for log transformed data using both full and reduced rank analyses. Then, we modelled the untransformed data assuming it to be negative binomially distributed and used Metropolis Hastings to fit a generalized reduced rank random regression model with an additive genetic, permanent environmental and maternal effect. These three variance components explained more than 80 % of the total phenotypic variation, whereas the variance components for the log transformed data accounted for considerably less. The heritability, on a link scale, increased from around 0.25 at the beginning of the grazing season to around 0.4 at the end.
Conclusions:
Random regressions are a useful tool for quantifying sources of variation across time. Our MCMC (Markov chain Monte Carlo) algorithm provides a flexible approach to fitting random regression models to non-normal data. Here we applied the algorithm to negative binomially distributed faecal egg count data, but this method is readily applicable to other types of overdispersed data
Estimating the potential impact of canine distemper virus on the Amur tiger population (Panthera tigris altaica) in Russia
Lethal infections with canine distemper virus (CDV) have recently been diagnosed in Amur tigers (Panthera tigris altaica), but long-term implications for the population are unknown. This study evaluates the potential impact of CDV on a key tiger population in Sikhote-Alin Biosphere Zapovednik (SABZ), and assesses how CDV might influence the extinction potential of other tiger populations of varying sizes. An individual-based stochastic, SIRD (susceptible-infected-recovered/dead) model was used to simulate infection through predation of infected domestic dogs, and/or wild carnivores, and direct tiger-to-tiger transmission. CDV prevalence and effective contact based on published and observed data was used to define plausible low- and high-risk infection scenarios. CDV infection increased the 50-year extinction probability of tigers in SABZ by 6.3% to 55.8% compared to a control population, depending on risk scenario. The most significant factors influencing model outcome were virus prevalence in the reservoir population(s) and its effective contact rate with tigers. Adjustment of the mortality rate had a proportional impact, while inclusion of epizootic infection waves had negligible additional impact. Small populations were found to be disproportionately vulnerable to extinction through CDV infection. The 50-year extinction risk in populations consisting of 25 individuals was 1.65 times greater when CDV was present than that of control populations. The effects of density dependence do not protect an endangered population from the impacts of a multi-host pathogen, such as CDV, where they coexist with an abundant reservoir presenting a persistent threat. Awareness of CDV is a critical component of a successful tiger conservation management policy
Multistrain models predict sequential multidrug treatment strategies to result in less antimicrobial resistance than combination treatment
Background
Combination treatment is increasingly used to fight infections caused by bacteria resistant to two or more antimicrobials. While multiple studies have evaluated treatment strategies to minimize the emergence of resistant strains for single antimicrobial treatment, fewer studies have considered combination treatments. The current study modeled bacterial growth in the intestine of pigs after intramuscular combination treatment (i.e. using two antibiotics simultaneously) and sequential treatments (i.e. alternating between two antibiotics) in order to identify the factors that favor the sensitive fraction of the commensal flora.
Growth parameters for competing bacterial strains were estimated from the combined in vitro pharmacodynamic effect of two antimicrobials using the relationship between concentration and net bacterial growth rate. Predictions of in vivo bacterial growth were generated by a mathematical model of the competitive growth of multiple strains of Escherichia coli.
Results
Simulation studies showed that sequential use of tetracycline and ampicillin reduced the level of double resistance, when compared to the combination treatment. The effect of the cycling frequency (how frequently antibiotics are alternated in a sequential treatment) of the two drugs was dependent upon the order in which the two drugs were used.
Conclusion
Sequential treatment was more effective in preventing the growth of resistant strains when compared to the combination treatment. The cycling frequency did not play a role in suppressing the growth of resistant strains, but the specific order of the two antimicrobials did. Predictions made from the study could be used to redesign multidrug treatment strategies not only for intramuscular treatment in pigs, but also for other dosing routes
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