The feasibility of testing whether Fasciola hepatica is associated with increased risk of verocytotoxin producing Escherichia coli O157 from an existing study protocol

The parasite Fasciola hepatica is a major cause of economic loss to the agricultural community worldwide as a result of morbidity and mortality in livestock, including cattle. Cattle are the principle reservoir of verocytotoxigenic Escherichia coli O157 (VTEC O157), an important cause of disease in humans. To date there has been little empirical research on the interaction between F. hepatica and VTEC O157. It is hypothesised that F. hepatica, which is known to suppress type 1 immune responses and induce an anti-inflammatory or regulatory immune environment in the host, may promote colonisation of the bovine intestine with VTEC O157. Here we assess whether it is statistically feasible to augment a prospective study to quantify the prevalence of VTEC O157 in cattle in Great Britain with a pilot study to test this hypothesis. We simulate data under the framework of a mixed-effects logistic regression model in order to calculate the power to detect an association effect size (odds ratio) of 2. In order to reduce the resources required for such a study, we exploit the fact that the test results for VTEC O157 will be known in advance of testing for F. hepatica by restricting analysis to farms with a VTEC O157 sample prevalence of >0% and <100%. From a total of 270 farms (mean 27 cows per farm) that will be tested for VTEC O157, power of 87% can be achieved, whereby testing of F. hepatica would only be necessary for an expected 50 farms, thus considerably reducing costs. Pre-study sample size calculations are an important part of any study design. The framework developed here is applicable to the study of other co-infections

A dimensional summation account of polymorphous category learning

This is the author accepted manuscript. The final version is available from Springer via the DOI in this record.Data and code availaibility: The data and code for all analyses for all experiments are available at the OSF addresses given in each Results section. The stimuli are available at the same locations.Polymorphous concepts are hard to learn, and this is perhaps surprising because they, like many natural concepts, have an overall similarity structure. However, the dimensional summation hypothesis (Milton & Wills, 2004) predicts this difficulty. It also makes a number of other predictions about polymorphous concept formation, which are tested here. In Experiment 1 we confirm the theory’s prediction that polymorphous concept formation should be facilitated by deterministic pretraining on the constituent features of the stimulus. This facilitation is relative to an equivalent amount of training on the polymorphous concept itself. In Experiments 2–4, the dimensional summation account of this single feature pretraining effect is contrasted with some other accounts, including a more general strategic account (Experiment 2), seriality of training and stimulus decomposition accounts (Experiment 3), and the role of errors (Experiment 4). The dimensional summation hypothesis provides the best account of these data. In Experiment 5, a further prediction is confirmed — the single feature pretraining effect is eliminated by a concurrent counting task. The current experiments suggest the hypothesis that natural concepts might be acquired by the deliberate serial summation of evidence. This idea has testable implications for classroom learning.Biotechnology and Biological Sciences Research Council (BBSRC

Genome-Wide Association Study of Lp-PLA2 Activity and Mass in the Framingham Heart Study

Lipoprotein-associated phospholipase A2 (Lp-PLA2) is an emerging risk factor and therapeutic target for cardiovascular disease. The activity and mass of this enzyme are heritable traits, but major genetic determinants have not been explored in a systematic, genome-wide fashion. We carried out a genome-wide association study of Lp-PLA2 activity and mass in 6,668 Caucasian subjects from the population-based Framingham Heart Study. Clinical data and genotypes from the Affymetrix 550K SNP array were obtained from the open-access Framingham SHARe project. Each polymorphism that passed quality control was tested for associations with Lp-PLA2 activity and mass using linear mixed models implemented in the R statistical package, accounting for familial correlations, and controlling for age, sex, smoking, lipid-lowering-medication use, and cohort. For Lp-PLA2 activity, polymorphisms at four independent loci reached genome-wide significance, including the APOE/APOC1 region on chromosome 19 (p = 6×10−24); CELSR2/PSRC1 on chromosome 1 (p = 3×10−15); SCARB1 on chromosome 12 (p = 1×10−8) and ZNF259/BUD13 in the APOA5/APOA1 gene region on chromosome 11 (p = 4×10−8). All of these remained significant after accounting for associations with LDL cholesterol, HDL cholesterol, or triglycerides. For Lp-PLA2 mass, 12 SNPs achieved genome-wide significance, all clustering in a region on chromosome 6p12.3 near the PLA2G7 gene. Our analyses demonstrate that genetic polymorphisms may contribute to inter-individual variation in Lp-PLA2 activity and mass

Long-term CO₂ injection and its impact on near-surface soil microbiology

Impacts of long-term CO₂ exposure on environmental processes and microbial populations of near-surface soils are poorly understood. This near-surface long-term CO₂ injection study demonstrated that soil microbiology and geochemistry is influenced more by seasonal parameters than elevated CO₂. Soil samples were taken during a 3-year field experiment including sampling campaigns before, during and after 24 months of continuous CO₂ injection. CO₂ concentrations within CO₂-injected plots increased up to 23% during the injection period. No CO₂ impacts on geochemistry were detected over time. In addition, CO₂ exposed samples did not show significant changes in microbial CO₂ and CH₄ turnover rates compared to reference samples. Likewise, no significant CO₂-induced variations were detected for the abundance of Bacteria, Archaea (16S rDNA) and gene copy numbers of the mcrA gene, Crenarchaeota and amoA gene. The majority (75%–95%) of the bacterial sequences were assigned to five phyla: Firmicutes, Proteobacteria, Actinobacteria, Acidobacteria and Bacteroidetes. The majority of the archaeal sequences (85%–100%) were assigned to the thaumarchaeotal cluster I.1b (soil group). Univariate and multivariate statistical as well as principal component analyses showed no significant CO₂-induced variation. Instead, seasonal impacts especially temperature and precipitation were detected

Turning the (virtual) world around: Patterns in saccade direction vary with picture orientation and shape in virtual reality

Research investigating gaze in natural scenes has identified a number of spatial biases in where people look, but it is unclear whether these are partly due to constrained testing environments (e.g., a participant with their head restrained and looking at a landscape image framed within a computer monitor). We examined the extent to which image shape (square vs. circle), image rotation, and image content (landscapes vs. fractal images) influence eye and head movements in virtual reality (VR). Both the eyes and head were tracked while observers looked at natural scenes in a virtual environment. In line with previous work, we found a bias for saccade directions parallel to the image horizon, regardless of image shape or content. We found that, when allowed to do so, observers move both their eyes and head to explore images. Head rotation, however, was idiosyncratic; some observers rotated a lot, whereas others did not. Interestingly, the head rotated in line with the rotation of landscape but not fractal images. That head rotation and gaze direction respond differently to image content suggests that they may be under different control systems. We discuss our findings in relation to current theories on head and eye movement control and how insights from VR might inform more traditional eye-tracking studies

Apolipoprotein E genotype does not moderate the associations of depressive symptoms, neuroticism and allostatic load with cognitive ability and cognitive aging in the Lothian Birth Cohort 1936

<div><p>Objectives</p><p>In this replication-and-extension study, we tested whether depressive symptoms, neuroticism, and allostatic load (multisystem physiological dysregulation) were related to lower baseline cognitive ability and greater subsequent cognitive decline in older adults, and whether these relationships were moderated by the E4 allele of the apolipoprotein E (<i>APOE</i>) gene. We also tested whether allostatic load mediated the relationships between neuroticism and cognitive outcomes.</p><p>Methods</p><p>We used data from the Lothian Birth Cohort 1936 (<i>n</i> at Waves 1–3: 1,028 [<i>M</i> age = 69.5 y]; 820 [<i>M</i> duration since Wave 1 = 2.98 y]; 659 [<i>M</i> duration since Wave 1 = 6.74 y]). We fitted latent growth curve models of general cognitive ability (modeled using five cognitive tests) with groups of <i>APOE</i> E4 non-carriers and carriers. In separate models, depressive symptoms, neuroticism, and allostatic load predicted baseline cognitive ability and subsequent cognitive decline. In addition, models tested whether allostatic load mediated relationships between neuroticism and cognitive outcomes.</p><p>Results</p><p>Baseline cognitive ability had small-to-moderate negative associations with depressive symptoms (<i>β</i> range = -0.20 to -0.17), neuroticism (<i>β</i> range = -0.27 to -0.23), and allostatic load (<i>β</i> range = -0.11 to 0.09). Greater cognitive decline was linked to baseline allostatic load (<i>β</i> range = -0.98 to -0.83) and depressive symptoms (<i>β</i> range = -1.00 to -0.88). However, <i>APOE</i> E4 allele possession did not moderate the relationships of depressive symptoms, neuroticism and allostatic load with cognitive ability and cognitive decline. Additionally, the associations of neuroticism with cognitive ability and cognitive decline were not mediated through allostatic load.</p><p>Conclusions</p><p>Our results suggest that <i>APOE</i> E4 status does not moderate the relationships of depressive symptoms, neuroticism, and allostatic load with cognitive ability and cognitive decline in healthy older adults. The most notable positive finding in the current research was the strong association between allostatic load and cognitive decline.</p></div

Mathematical graphics: technique and qpplications

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