Chord diagrams and BPHZ subtractions

The combinatorics of the BPHZ subtraction scheme for a class of ladder graphs for the three point vertex in $\phi^3$ theory is transcribed into certain connectivity relations for marked chord diagrams (knots with transversal intersections). The resolution of the singular crossings using the equivalence relations in these examples provides confirmation of a proposed fundamental relationship between knot theory and renormalization in perturbative quantum field theory.Comment: 12 pages, 5 Postscript figures, LaTex 2

After uniqueness: the evolution of forensic science opinions

Big changes are occurring in forensic science, particularly among experts who compare the patterns found in fingerprints, footwear impressions, toolmarks, handwriting, and the like. Forensic examiners are reaching conclusions in new ways and changing the language they use in reports and testimony. This article explains these changes and the challenges they pose for lawyers and judges

Catchment survey in the Karonga District: a landscape-scale analysis of provisioning and core reduction strategies during the Middle Stone Age of northern Malawi

The landscape of northern Malawi is defined by several river catchments that drain from the highlands in the west into Lake Malawi in the east. Many thousands of Middle Stone Age (MSA) artefacts are present on the surface, in particular, in areas where sedimentary units assigned to the Chitimwe Beds are exposed. The unique configuration of the region and its exposures makes it possible to address landscape-scale questions about MSA behaviour that augment information derived from excavated assemblages. In this study, data are derived from initial results of surveys conducted in 2012 which focussed on how lithic raw materials (in the form of cobbles) and core technology (in the form of mapped and analysed cores) are distributed across the landscape relative to different landforms, geologies and one another. These data are used to examine if differences in core reduction technology occur in different catchment areas with different raw material quantities and qualities, and to test hypotheses about lithic provisioning scenarios. This allows for examination of core reduction technologies in relation to raw material sources via surface finds, on a larger regional scale than is usually possible from excavations. Different catchments show differences in the type and quality of the raw material, with higher-quality quartzites occurring in the North Rukuru catchment and declining to the south. This is reflected in the types of materials that MSA people chose to use for the production of stone tools. However, differences in raw material selection and distance from cobbles did not influence preferred core reduction strategies, and most cores cluster together near cobble sources. This suggests that throughout the MSA in the study area, core reduction strategies were highly conserved even while raw material use remained flexible, and cores were not regularly transported as part of a provisioning strategy

Unifying Approaches to Chiral Bosons

Chiral bosons, or self-dual p-form fields, are ubiquitous in string theoretic contexts but are challenging to treat. Lagrangian constructions invariably introduce a complexity be it auxiliary fields or sacrificing Lorentz invariance. In this note we show how to pass between such different approaches to chiral bosons starting from a Chern Simons point of view to recover formulations of Pasti, Sorokin and Tonin and of Mkrtchyan. This leads to a novel generalisation of the latter to include non-Abelian chiral bosons in 2-dimensions, and generalisations to include twisted self-duality which are relevant in T-duality symmetric approaches to string theory. Our approach also shows how global affine symmetries of two- and higher-dimensional chiral bosons emerge from broken Chern-Simons gauge transformations on the boundary.Comment: 22 page

Leucocyte telomere length and risk of cardiovascular disease: systematic review and meta-analysis.

OBJECTIVE: To assess the association between leucocyte telomere length and risk of cardiovascular disease. DESIGN: Systematic review and meta-analysis. DATA SOURCES: Studies published up to March 2014 identified through searches of Medline, Web of Science, and Embase. ELIGIBILITY CRITERIA: Prospective and retrospective studies that reported on associations between leucocyte telomere length and coronary heart disease (defined as non-fatal myocardial infarction, coronary heart disease death, or coronary revascularisation) or cerebrovascular disease (defined as non-fatal stroke or death from cerebrovascular disease) and were broadly representative of general populations--that is, they did not select cohort or control participants on the basis of pre-existing cardiovascular disease or diabetes. RESULTS: Twenty four studies involving 43,725 participants and 8400 patients with cardiovascular disease (5566 with coronary heart disease and 2834 with cerebrovascular disease) were found to be eligible. In a comparison of the shortest versus longest third of leucocyte telomere length, the pooled relative risk for coronary heart disease was 1.54 (95% confidence interval 1.30 to 1.83) in all studies, 1.40 (1.15 to 1.70) in prospective studies, and 1.80 (1.32 to 2.44) in retrospective studies. Heterogeneity between studies was moderate (I(2) = 64%, 41% to 77%, Phet<0.001) and was not significantly explained by mean age of participants (P = 0.23), the proportion of male participants (P = 0.45), or distinction between retrospective versus prospective studies (P = 0.32). Findings for coronary heart disease were similar in meta-analyses restricted to studies that adjusted for conventional vascular risk factors (relative risk 1.42, 95% confidence interval 1.17 to 1.73); studies with ≥ 200 cases (1.44, 1.20 to 1.74); studies with a high quality score (1.53, 1.22 to 1.92); and in analyses that corrected for publication bias (1.34, 1.12 to 1.60). The pooled relative risk for cerebrovascular disease was 1.42 (1.11 to 1.81), with no significant heterogeneity between studies (I(2) = 41%, 0% to 72%, Phet = 0.08). Shorter telomeres were not significantly associated with cerebrovascular disease risk in prospective studies (1.14, 0.85 to 1.54) or in studies with a high quality score (1.21, 0.83 to 1.76). CONCLUSION: Available observational data show an inverse association between leucocyte telomere length and risk of coronary heart disease independent of conventional vascular risk factors. The association with cerebrovascular disease is less certain

Technique for the calibration of hydrophones in the frequency range 10 to 600 kHz using a heterodyne interferometer and an acoustically compliant membrane

A technique for the calibration of hydrophones using an optical method is presented. In the method, a measurement is made of the acoustic particle velocity in the field of a transducer by use of a thin plastic pellicle that is used to reflect the optical beam of a laser vibrometer, the pellicle being acoustically transparent at the frequency of interest. The hydrophone under test is then substituted for the pellicle, and the hydrophone response to the known acoustic field is measured. A commercially available laser vibrometer is used to undertake the calibrations, and results are presented over a frequency range from 10 to 600 kHz. A comparison is made with the method of three-transducer spherical-wave reciprocity, with agreement of better than 0.5 dB over the majority of the frequency range. The pellicle used is in the form of a narrow strip of thin Mylar©, and a discussion is given of the effect of the properties of the pellicle on the measurement results. The initial results presented here show that the method has the potential to form the basis of a primary standard method, with the calibration traceable to standards of length measurement through the wavelength of the laser light

No evidence for changes in GABA concentration, functional connectivity, or working memory following continuous theta burst stimulation over dorsolateral prefrontal cortex

Continuous theta burst stimulation (cTBS) is thought to reduce cortical excitability and modulate functional connectivity, possibly by altering cortical inhibition at the site of stimulation. However, most evidence comes from the motor cortex and it remains unclear whether similar effects occur following stimulation over other brain regions. We assessed whether cTBS over left dorsolateral prefrontal cortex altered gamma aminobutyric acid (GABA) concentration, functional connectivity and brain dynamics at rest, and brain activation and memory performance during a working memory task. Seventeen healthy individuals participated in a randomised, sham-controlled, cross-over experiment. Before and after either real or sham cTBS, magnetic resonance spectroscopy was obtained at rest to measure GABA concentrations. Functional magnetic resonance imaging (fMRI) was also recorded at rest and during an n-back working memory task to measure functional connectivity, regional brain activity (low-frequency fluctuations), and task-related patterns of brain activity. We could not find evidence for changes in GABA concentration (P = 0.66, Bayes factor [BF10] = 0.07), resting-state functional connectivity (P(FWE) > 0.05), resting-state low-frequency fluctuations (P = 0.88, BF10 = 0.04), blood-oxygen level dependent activity during the n-back task (P(FWE) > 0.05), or working memory performance (P = 0.13, BF10 = 0.05) following real or sham cTBS. Our findings add to a growing body of literature suggesting the effects of cTBS are highly variable between individuals and question the notion that cTBS is a universal ‘inhibitory’ paradigm

Rotating Convection in an Anisotropic System

We study the stability of patterns arising in rotating convection in weakly anisotropic systems using a modified Swift-Hohenberg equation. The anisotropy, either an endogenous characteristic of the system or induced by external forcing, can stabilize periodic rolls in the K\"uppers-Lortz chaotic regime. For the particular case of rotating convection with time-modulated rotation where recently, in experiment, chiral patterns have been observed in otherwise K\"uppers-Lortz-unstable regimes, we show how the underlying base-flow breaks the isotropy, thereby affecting the linear growth-rate of convection rolls in such a way as to stabilize spirals and targets. Throughout we compare analytical results to numerical simulations of the Swift-Hohenberg equation