2,107 research outputs found

    A Mathematical Modelling Approach for Systems Where the Servers Are Almost Always Busy

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    The design and implementation of new configurations of mental health services to meet local needs is a challenging problem. In the UK, services for common mental health disorders such as anxiety and depression are an example of a system running near or at capacity, in that it is extremely rare for the queue size for any given mode of treatment to fall to zero. In this paper we describe a mathematical model that can be applied in such circumstances. The model provides a simple way of estimating the mean and variance of the number of patients that would be treated within a given period of time given a particular configuration of services as defined by the number of appointments allocated to different modes of treatment and the referral patterns to and between different modes of treatment. The model has been used by service planners to explore the impact of different options on throughput, clinical outcomes, queue sizes, and waiting times. We also discuss the potential for using the model in conjunction with optimisation techniques to inform service design and its applicability to other contexts

    Experimental alteration of DNA methylation affects the phenotypic plasticity of ecologically relevant traits in Arabidopsis thaliana

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    Heritable phenotypic variation in plants can be caused not only by underlying genetic differences, but also by variation in epigenetic modifications such as DNA methylation. However, we still know very little about how relevant such epigenetic variation is to the ecology and evolution of natural populations. We conducted a greenhouse experiment in which we treated a set of natural genotypes of Arabidopsis thaliana with the demethylating agent 5-azacytidine and examined the consequences of this treatment for plant traits and their phenotypic plasticity. Experimental demethylation strongly reduced the growth and fitness of plants and delayed their flowering, but the degree of this response varied significantly among genotypes. Differences in genotypes' responses to demethylation were only weakly related to their genetic relatedness, which is consistent with the idea that natural epigenetic variation is independent of genetic variation. Demethylation also altered patterns of phenotypic plasticity, as well as the amount of phenotypic variation observed among plant individuals and genotype means. We have demonstrated that epigenetic variation can have a dramatic impact on ecologically important plant traits and their variability, as well as on the fitness of plants and their ecological interactions. Epigenetic variation may thus be an overlooked factor in the evolutionary ecology of plant population

    Motivation for Physical Training in Army ROTC Cadets

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    The present study used Self-Determination Theory to study motivation for physical training (PT) in ARMY ROTC cadets (n=139). Results found that length of participation in ROTC lowered cadets’ intrinsic motivation, which then resulted in lower levels of enjoyment for PT. Application of results for future training is discussed

    Genome-Wide Patterns of Arabidopsis Gene Expression in Nature

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    Organisms in the wild are subject to multiple, fluctuating environmental factors, and it is in complex natural environments that genetic regulatory networks actually function and evolve. We assessed genome-wide gene expression patterns in the wild in two natural accessions of the model plant Arabidopsis thaliana and examined the nature of transcriptional variation throughout its life cycle and gene expression correlations with natural environmental fluctuations. We grew plants in a natural field environment and measured genome-wide time-series gene expression from the plant shoot every three days, spanning the seedling to reproductive stages. We find that 15,352 genes were expressed in the A. thaliana shoot in the field, and accession and flowering status (vegetative versus flowering) were strong components of transcriptional variation in this plant. We identified between ∼110 and 190 time-varying gene expression clusters in the field, many of which were significantly overrepresented by genes regulated by abiotic and biotic environmental stresses. The two main principal components of vegetative shoot gene expression (PCveg) correlate to temperature and precipitation occurrence in the field. The largest PCveg axes included thermoregulatory genes while the second major PCveg was associated with precipitation and contained drought-responsive genes. By exposing A. thaliana to natural environments in an open field, we provide a framework for further understanding the genetic networks that are deployed in natural environments, and we connect plant molecular genetics in the laboratory to plant organismal ecology in the wild

    Queen-produced volatiles change dynamically during reproductive swarming and are associated with changes in honey bee (Apis mellifera) worker behavior

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    International audienceAbstractDuring colony fission, honey bee workers are exquisitely sensitive to the presence of their queen in airborne swarms and bivouacs and will abandon swarming if she is absent. However, it is not known whether swarming queens produce a chemical bouquet that is distinct from non-swarming queens, containing either unique chemicals or altered proportions of chemicals. We found that queens emitted higher quantities and greater numbers of unique volatiles at liftoff than they did prior to swarming or in clustered bivouacs, and swarming workers tended to be attracted to these liftoff volatile blends. Pentadecane and heptadecane were collected most frequently and emitted in significantly higher quantities by queens at liftoff; these compounds have been described as pheromone components in other social insects, but not yet in honey bees. Our results suggest that volatile emission by queens is more dynamic than previously thought and that changes in their chemical signals may play a role in regulating the behavior of swarming workers

    The impact of therapy for childhood acute lymphoblastic leukaemia on intelligence quotients; results of the risk-stratified randomized central nervous system treatment trial MRC UKALL XI

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    <p>Background: The MRC UKALLXI trial tested the efficacy of different central nervous system (CNS) directed therapies in childhood acute lymphoblastic leukaemia (ALL). To evaluate morbidity 555/1826 randomised children underwent prospective psychological evaluations. Full Scale, verbal and performance IQs were measured at 5 months, 3 years and 5 years. Scores were compared in; (1) all patients (n = 555) versus related controls (n = 311), (2) low-risk children (presenting white cell count (WCC) < 50 × 109/l) randomised to intrathecal methotrexate (n = 197) versus intrathecal and high-dose intravenous methotrexate (HDM) (n = 202), and (3) high-risk children (WCC ≥ 50 × 109/l, age ≥ 2 years) randomised to HDM (n = 79) versus cranial irradiation (n = 77).</p> <p>Results: There were no significant differences in IQ scores between the treatment arms in either low- or high-risk groups. Despite similar scores at baseline, results at 3 and 5 years showed a significant reduction of between 3.6 and 7.3 points in all three IQ scores in all patient groups compared to controls (P < 0.002) with a higher proportion of children with IQs < 80 in the patient groups (13% vs. 5% at 3 years p = 0.003).</p> <p>Conclusion: Children with ALL are at risk of CNS morbidity, regardless of the mode of CNS-directed therapy. Further work needs to identify individuals at high-risk of adverse CNS outcomes.</p&gt