University of Exeter

About: University of Exeter is a education organization based out in Exeter, United Kingdom. It is known for research contribution in the topics: Population & Context (language use). The organization has 15820 authors who have published 50650 publications receiving 1793046 citations. The organization is also known as: Exeter University & University of the South West of England.

Structural deformation of bacterial biofilms caused by short‐term fluctuations in fluid shear: An in situ investigation of biofilm rheology

Abstract: The physical properties (rheology) of biofilms will determine the shape and mechanical stability of the biofilm structure and consequently affect both mass transfer and detachment processes Biofilm viscoelasticity is also thought to increase fluid energy losses in pipelines Yet there is very little information on the rheology of intact biofilms This is due in part to the difficulty in using conventional testing techniques The size and nature of biofilms makes them difficult to handle, while removal from a surface destroys the integrity of the sample We have developed a method which allowed us to conduct simple stress-strain and creep experiments on mixed and pure culture biofilms in situ by observing the structural deformations caused by changes in hydrodynamic shear stress (tau(w)) The biofilms were grown under turbulent pipe flow (flow velocity (u) = 1 m/s, Reynolds number (Re) = 3600, tau(w) = 5 09 N/m(2)) for between 12 and 23 days The resulting biofilms were heterogeneous and consisted of filamentous streamers that were readily deformed by changes in tau(w) At tau(w) of 1011 N/m(2) the streamers were flattened so that the thickness was reduced by 25% We estimated that the shear modulus (G) of the mixed culture biofilm was 27 N/m(2) and the apparent elastic modulus (E(app)) of both biofilms was in the range of 17 to 40 N/m(2) The biofilms behaved like elastic and viscoelastic solids below the tau(w) at which they were grown but behaved like viscoelastic fluids at elevated tau(w) The implications of these results for fluid energy losses and the processes of mass transfer and detachment are discussed

Genomic analyses identify hundreds of variants associated with age at menarche and support a role for puberty timing in cancer risk

Abstract: The timing of puberty is a highly polygenic childhood trait that is epidemiologically associated with various adult diseases. Using 1000 Genomes Project-imputed genotype data in up to ∼370,000 women, we identify 389 independent signals (P < 5 × 10-8) for age at menarche, a milestone in female pubertal development. In Icelandic data, these signals explain ∼7.4% of the population variance in age at menarche, corresponding to ∼25% of the estimated heritability. We implicate ∼250 genes via coding variation or associated expression, demonstrating significant enrichment in neural tissues. Rare variants near the imprinted genes MKRN3 and DLK1 were identified, exhibiting large effects when paternally inherited. Mendelian randomization analyses suggest causal inverse associations, independent of body mass index (BMI), between puberty timing and risks for breast and endometrial cancers in women and prostate cancer in men. In aggregate, our findings highlight the complexity of the genetic regulation of puberty timing and support causal links with cancer susceptibility.

Myosin domain evolution and the primary divergence of eukaryotes

Abstract: Eukaryotic cells have two contrasting cytoskeletal and ciliary organizations. The simplest involves a single cilium-bearing centriole, nucleating a cone of individual microtubules (probably ancestral for unikonts: animals, fungi, Choanozoa and Amoebozoa). In contrast, bikonts (plants, chromists and all other protozoa) were ancestrally biciliate with a younger anterior cilium, converted every cell cycle into a dissimilar posterior cilium and multiple ciliary roots of microtubule bands. Here we show by comparative genomic analysis that this fundamental cellular dichotomy also involves different myosin molecular motors. We found 37 different protein domain combinations, often lineage-specific, and many previously unidentified. The sequence phylogeny and taxonomic distribution of myosin domain combinations identified five innovations that strongly support unikont monophyly and the primary bikont/unikont bifurcation. We conclude that the eukaryotic cenancestor (last common ancestor) had a cilium, mitochondria, pseudopodia, and myosins with three contrasting domain combinations and putative functions.

Weak localization in graphene flakes.

Abstract: We show that the manifestation of quantum interference in graphene is very different from that in conventional two-dimensional systems. Because of the chiral nature of charge carriers, it is not only sensitive to inelastic, phase-breaking scattering, but also to a number of elastic scattering processes. We study weak localization in different samples and at different carrier densities, including the Dirac region, and find the characteristic rates that determine it. We show how the shape and quality of graphene flakes affect the values of the elastic and inelastic rates and discuss their physical origin.

Adverse events following acupuncture: prospective survey of 32 000 consultations with doctors and physiotherapists.

Abstract: Acupuncture is increasingly popular, but it is not free from risk for the patient.1 Safety is best established with prospective surveys. Our aim was to ascertain the incidence of adverse events related to acupuncture treatment, as currently practised in Britain by doctors and physiotherapists. Volunteer acupuncture practitioners were recruited through journals circulated to members of the British Medical Acupuncture Society and the Acupuncture Association of Chartered Physiotherapists (approximately 2750 members).2 A prospective survey was undertaken using forms for intensive event monitoring that had been piloted previously.3 Minor adverse events were defined as “any ill-effect, no matter how small, that is unintended and non-therapeutic, even if not unexpected.” These events were reported every month, along with the total number of consultations. Minor or serious events that were considered to be “significant”—“unusual, novel, dangerous, significantly inconvenient, or requiring further information”—were reported on separate forms when they occurred. Anonymous reporting was accepted. A sample size of …