315 research outputs found

    Systematic Hydrogen‐Bond Manipulations To Establish Polysaccharide Structure–Property Correlations

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    A dense hydrogen‐bond network is responsible for the mechanical and structural properties of polysaccharides. Random derivatization alters the properties of the bulk material by disrupting the hydrogen bonds, but obstructs detailed structure–function correlations. We have prepared well‐defined unnatural oligosaccharides including methylated, deoxygenated, deoxyfluorinated, as well as carboxymethylated cellulose and chitin analogues with full control over the degree and pattern of substitution. Molecular dynamics simulations and crystallographic analysis show how distinct hydrogen‐bond modifications drastically affect the solubility, aggregation behavior, and crystallinity of carbohydrate materials. This systematic approach to establishing detailed structure–property correlations will guide the synthesis of novel, tailor‐made carbohydrate materials

    Systematic Hydrogen‐Bond Manipulations To Establish Polysaccharide Structure–Property Correlations

    Get PDF
    A dense hydrogen‐bond network is responsible for the mechanical and structural properties of polysaccharides. Random derivatization alters the properties of the bulk material by disrupting the hydrogen bonds, but obstructs detailed structure–function correlations. We have prepared well‐defined unnatural oligosaccharides including methylated, deoxygenated, deoxyfluorinated, as well as carboxymethylated cellulose and chitin analogues with full control over the degree and pattern of substitution. Molecular dynamics simulations and crystallographic analysis show how distinct hydrogen‐bond modifications drastically affect the solubility, aggregation behavior, and crystallinity of carbohydrate materials. This systematic approach to establishing detailed structure–property correlations will guide the synthesis of novel, tailor‐made carbohydrate materials

    Urban football narratives and the colonial process in Lourenço Marques

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    Support for Portuguese football teams, in Mozambique as well as in other former Portuguese colonies, could be interpreted either as a sign of the importance of a cultural colonial heritage in Africa or as a symbol of a perverse and neo-colonial acculturation. This article, focused on Maputo, the capital of Mozambique – formerly called Lourenc¸o Marques – argues that in order to understand contemporary social bonds, it is crucial to research the connection between the colonial process of urbanisation and the rise of urban popular cultures. Despite the existence of social discrimination in colonial Lourenc¸o Marques, deeply present in the spatial organisation of a city divided between a ‘concrete’ centre and the immense periphery, the consumption of football, as part of an emergent popular culture, crossed segregation lines. I argue that football narratives, locally appropriated, became the basis of daily social rituals and encounters, an element of urban sociability and the content of increasingly larger social networks. Therefore, the fact that a Portuguese narrative emerged as the dominant form of popular culture is deeply connected to the growth of an urban community

    Drones and digital adherence monitoring for community-based tuberculosis control in remote Madagascar: a cost-effectiveness analysis

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    Continuing tuberculosis control with current approaches is unlikely to reach the World Health Organization's objective to eliminate TB by 2035. Innovative interventions such as unmanned aerial vehicles (or drones) and digital adherence monitoring technologies have the potential to enhance patient-centric quality tuberculosis care and help challenged National Tuberculosis Programs leapfrog over the impediments of conventional Directly Observed Therapy (DOTS) implementation. A bundle of innovative interventions referred to for its delivery technology as the Drone Observed Therapy System (DrOTS) was implemented in remote Madagascar. Given the potentially increased cost these interventions represent for health systems, a cost-effectiveness analysis was indicated.; A decision analysis model was created to calculate the incremental cost-effectiveness of the DrOTS strategy compared to DOTS, the standard of care, in a study population of 200,000 inhabitants in rural Madagascar with tuberculosis disease prevalence of 250/100,000. A mixed top-down and bottom-up costing approach was used to identify costs associated with both models, and net costs were calculated accounting for resulting TB treatment costs. Net cost per disability-adjusted life years averted was calculated. Sensitivity analyses were performed for key input variables to identify main drivers of health and cost outcomes, and cost-effectiveness.; Net cost per TB patient identified within DOTS and DrOTS were, respectively, 282and282 and 1,172. The incremental cost per additional TB patient diagnosed in DrOTS was 2,631andtheincrementalcost−effectivenessratioofDrOTScomparedtoDOTSwas2,631 and the incremental cost-effectiveness ratio of DrOTS compared to DOTS was 177 per DALY averted. Analyses suggest that integrating drones with interventions ensuring highly sensitive laboratory testing and high treatment adherence optimizes cost-effectiveness.; Innovative technology packages including drones, digital adherence monitoring technologies, and molecular diagnostics for TB case finding and retention within the cascade of care can be cost effective. Their integration with other interventions within health systems may further lower costs and support access to universal health coverage

    Sperm selection by rheotaxis improves sperm quality and early embryo development

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    peer-reviewedThe objective of this work was to elucidate whether a sperm selection method that combines rheotaxis and microfluidics can improve the selection of spermatozoa over density gradient and swim-up. For this purpose human sperm selected by rheotaxis were compared against density gradient, swim-up and a control group of non-selected spermatozoa in split frozen-thawed (FT) and fresh (F) semen samples. Sperm quality was assessed in terms of motility, morphology, DNA fragmentation index (DFI), viability, acrosome integrity and membrane fluidity. Using a mouse model, we compared fertilisation and embryo development rates after performing ICSI with spermatozoa, sorted using rheotaxis or swim-up. Selection by rheotaxis yielded a sperm population with reduced DFI than the control (P < 0.05), improved normal morphology (P < 0.001) and higher total motility (TM; P < 0.001) than the other techniques studied in F and FT samples. Swim-up increased TM compared to density gradient and control in FT or F samples (P < 0.001), and yielded lower DFI than the control with F samples (P < 0.05). In FT samples, selection by rheotaxis yielded sperm with higher viability than control, density gradient and swim-up (P < 0.01) while acrosomal integrity and membrane fluidity were maintained. When mouse spermatozoa were selected for ICSI using rheotaxis compared to swim-up, there was an increase in fertilisation (P < 0.01), implantation (P < 0.001) and foetal development rates (P < 0.05). These results suggest that, in the absence of non-destructive DNA testing, the positive rheotaxis can be used to select a population of low DNA fragmentation spermatozoa with high motility, morphology and viability, leading to improved embryo developmental rates

    As assessment of the Competition Commission Report and subsequent outcomes

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    Following the Office of Fair Trading's review of the British deregulated bus market as a whole in 2009, the issues raised were referred to the Competition Commission. Its final report was published in December 2011. Subsequently, the House of Commons Transport Committee carried out an enquiry into the Commission's report, and reactions to it by the operating industry, user groups, and other bodies, which was published in September 2012. A number of major issues have been raised, including the extent to which price competition may be effective, the appropriate rate of return on capital that would be expected within the industry (and appropriate actions where this is excessive in practice), and industry structure. The importance of competition per se, as distinct from attributes of direct concern to users (such as reliability, frequency, and fares) has also been debated. This paper reviews the issues raised, and outcomes to date, in the light of further evidence on the industry's performance. It is demonstrated similar rates of return could be attained through very different operating strategies, which in turn have very different implications for changes in consumer surplus. The alternative uses made of such profits (for example through reinvestment) may also have markedly different impacts effects on users. Rather than focussing on the dangers of excessive rates of return on capital, the outcomes for service users should be the main issue

    Likelihood diagnostics and Bayesian analysis of a micro-economic disequilibrium model for retail services

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    In this paper we apply Maximum Likelihood and Bayesian methods to explain differences in floorspace productivity among retail establishments in the grocery trade. The model we develop is a switching model where sales are either supply-determined or demand-determined. Under excess supply the model allows for so-called ‘trading-down’, i.e., an increase in the share of selling area, and, thereby, a decrease in service level. To estimate our model we employ a cross-section of observations on individual shops. We present maximum likelihood results, and also study the shape of the likelihood surface by means of Monte Carlo numerical integration methods. With a uniform prior we obtain marginal posterior density functions both of the parameters of interest and of the average probability of the excess supply regime in the sample. The average probability of excess supply is 0.23, with a standard deviation of 0.06. This shows that, according to our estimates, excess demand is the rule and excess supply the exception in the sample that we analyse
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