13,240 research outputs found

    Cleaning up the catalogue

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    The London School of Economics wanted to remove cataloguing inconsistencies but the scale of the task was huge, and outsourcing to a specialist bibliographic services company proved only a partial solution. Helen Williams explains why manual and automated processes were needed

    Phylogenetic analysis accounting for age-dependent death and sampling with applications to epidemics

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    The reconstruction of phylogenetic trees based on viral genetic sequence data sequentially sampled from an epidemic provides estimates of the past transmission dynamics, by fitting epidemiological models to these trees. To our knowledge, none of the epidemiological models currently used in phylogenetics can account for recovery rates and sampling rates dependent on the time elapsed since transmission. Here we introduce an epidemiological model where infectives leave the epidemic, either by recovery or sampling, after some random time which may follow an arbitrary distribution. We derive an expression for the likelihood of the phylogenetic tree of sampled infectives under our general epidemiological model. The analytic concept developed in this paper will facilitate inference of past epidemiological dynamics and provide an analytical framework for performing very efficient simulations of phylogenetic trees under our model. The main idea of our analytic study is that the non-Markovian epidemiological model giving rise to phylogenetic trees growing vertically as time goes by, can be represented by a Markovian "coalescent point process" growing horizontally by the sequential addition of pairs of coalescence and sampling times. As examples, we discuss two special cases of our general model, namely an application to influenza and an application to HIV. Though phrased in epidemiological terms, our framework can also be used for instance to fit macroevolutionary models to phylogenies of extant and extinct species, accounting for general species lifetime distributions.Comment: 30 pages, 2 figure

    Catching crabs: a case study in local-scale English conservation

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    Wells-next-the-Sea and Cromer in Norfolk (England) both rely upon their local crab populations, since crabbing (gillying) is a major part of their tourist industry. Compared to a control site with no crabbing, crabs from Wells harbour and Cromer pier were found to have nearly six times the amount of limb damage. Crabs caught by the general public had more injuries than crabs caught in controlled conditions, suggesting the buckets in which the crabs were kept were to blame. Since there is much evidence that such injuries have negative impacts on the survival and reproductive success of the shore crab, this is taken as evidence of non-lethal injury from humans having a population-level effect on these animals. Questionnaire data demonstrated a public lack of awareness and want for information, which was then used to obtain funding to produce a leaflet campaign informing the public of how to crab responsibly. All data collected is available online at http://dx.doi.org/10.6084/m9.figshare.979288

    Consumers’ Desire for GM Labels: Is the Devil in the Details?

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    Consumer/Household Economics, Food Consumption/Nutrition/Food Safety,

    Social Assistance Programs and Outcomes: Food Assistance in the Context of Welfare Reform

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    Food assistance programs play an important role in meeting the basic needs of low-income households. We consider the complex interactions among food stamps, labor force participation, and food insecurity status of low-income households under different program designs and economic conditions. The analysis uses data from the Survey of Program Dynamics to jointly estimate the role of participation in the Food Stamp Program (FSP), labor market participation and well-being, measured as food security, through the use of a simultaneous equation model. The results of our research suggest that food insecurity has a positive effect on FSP participation while labor force participation reduces FSP participation. Furthermore, FSP participation is more responsive to changes in the program benefits than to changes in nonlabor income. The linkages among food program participation, labor force participation, and well-being, measured in terms of food insecurity, are complex. The structural approach provides evidence that, among low-income households, program parameters affect FSP participation but no evidence that the food assistance reduces food insecurity.
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