95 research outputs found

    An Aberrant Microbiota is not Strongly Associated with Incidental Colonic Diverticulosis

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    Colonic diverticula are protrusions of the mucosa through weak areas of the colonic musculature. The etiology of diverticulosis is poorly understood, but could be related to gut bacteria. Using mucosal biopsies from the sigmoid colon of 226 subjects with and 309 subjects without diverticula during first-time screening colonoscopy, we assessed whether individuals with incidental colonic diverticulosis have alternations in the adherent bacterial communities in the sigmoid colon. We found little evidence of substantial associations between the microbial community and diverticulosis among cases and controls. Comparisons of bacterial abundances across all taxonomic levels showed differences for phylum Proteobacteria (p = 0.038) and family Comamonadaceae (p = 0.035). The r-squared values measuring the strength of these associations were very weak, however, with values ~2%. There was a similarly small association between the abundance of each taxa and total diverticula counts. Cases with proximal only diverticula and distal only diverticula likewise showed little difference in overall microbiota profiles. This large study suggests little association between diverticula and the mucosal microbiota overall, or by diverticula number and location. We conclude that the mucosal adherent microbiota community composition is unlikely to play a substantial role in development of diverticulosis

    Electric current circuits in astrophysics

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    Cosmic magnetic structures have in common that they are anchored in a dynamo, that an external driver converts kinetic energy into internal magnetic energy, that this magnetic energy is transported as Poynting fl ux across the magnetically dominated structure, and that the magnetic energy is released in the form of particle acceleration, heating, bulk motion, MHD waves, and radiation. The investigation of the electric current system is particularly illuminating as to the course of events and the physics involved. We demonstrate this for the radio pulsar wind, the solar flare, and terrestrial magnetic storms

    Wind anisotropies and GRB progenitors

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    We study the effect of wind anisotropies on the stellar evolution leading to collapsars. Rotating models of a 60 M⊙_\odot star with Ω/Ωcrit=0.75\Omega/\Omega_{\rm crit}=0.75 on the ZAMS, accounting for shellular rotation and a magnetic field, with and without wind anisotropies, are computed at ZZ=0.002 until the end of the core He-burning phase. Only the models accounting for the effects of the wind anisotropies retain enough angular momentum in their core to produce a Gamma Ray Burst (GRB). The chemical composition is such that a type Ic supernova event occurs. Wind anisotropies appear to be a key physical ingredient in the scenario leading to long GRBs.Comment: 5 pages, 4 figures, accepted for publication in A&A Lette

    An integrated whole genome analysis of Mycobacterium tuberculosis reveals insights into relationship between its genome, transcriptome and methylome.

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    Human tuberculosis disease (TB), caused by Mycobacterium tuberculosis (Mtb), is a complex disease, with a spectrum of outcomes. Genomic, transcriptomic and methylation studies have revealed differences between Mtb lineages, likely to impact on transmission, virulence and drug resistance. However, so far no studies have integrated sequence-based genomic, transcriptomic and methylation characterisation across a common set of samples, which is critical to understand how DNA sequence and methylation affect RNA expression and, ultimately, Mtb pathogenesis. Here we perform such an integrated analysis across 22 M. tuberculosis clinical isolates, representing ancient (lineage 1) and modern (lineages 2 and 4) strains. The results confirm the presence of lineage-specific differential gene expression, linked to specific SNP-based expression quantitative trait loci: with 10 eQTLs involving SNPs in promoter regions or transcriptional start sites; and 12 involving potential functional impairment of transcriptional regulators. Methylation status was also found to have a role in transcription, with evidence of differential expression in 50 genes across lineage 4 samples. Lack of methylation was associated with three novel variants in mamA, likely to cause loss of function of this enzyme. Overall, our work shows the relationship of DNA sequence and methylation to RNA expression, and differences between ancient and modern lineages. Further studies are needed to verify the functional consequences of the identified mechanisms of gene expression regulation

    The Earth: Plasma Sources, Losses, and Transport Processes

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    This paper reviews the state of knowledge concerning the source of magnetospheric plasma at Earth. Source of plasma, its acceleration and transport throughout the system, its consequences on system dynamics, and its loss are all discussed. Both observational and modeling advances since the last time this subject was covered in detail (Hultqvist et al., Magnetospheric Plasma Sources and Losses, 1999) are addressed

    Sources of potential bias when combining routine data linkage and a national survey of secondary school-aged children: a record linkage study

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    Background Linking survey data to administrative records requires informed participant consent. When linkage includes child data, this includes parental and child consent. Little is known of the potential impacts of introducing consent to data linkage on response rates and biases in school-based surveys. This paper assessed: i) the impact on overall parental consent rates and sample representativeness when consent for linkage was introduced and ii) the quality of identifiable data provided to facilitate linkage. Methods Including an option for data linkage was piloted in a sub-sample of schools participating in the Student Health and Wellbeing survey, a national survey of adolescents in Wales, UK. Schools agreeing to participate were randomized 2:1 to receive versus not receive the data linkage question. Survey responses from consenting students were anonymised and linked to routine datasets (e.g. general practice, inpatient, and outpatient records). Parental withdrawal rates were calculated for linkage and non-linkage samples. Multilevel logistic regression models were used to compare characteristics between: i) consenters and non-consenters; ii) successfully and unsuccessfully linked students; and iii) the linked cohort and peers within the general population, with additional comparisons of mental health diagnoses and health service contacts. Results The sub-sample comprised 64 eligible schools (out of 193), with data linkage piloted in 39. Parental consent was comparable across linkage and non-linkage schools. 48.7% (n = 9232) of students consented to data linkage. Modelling showed these students were more likely to be younger, more affluent, have higher positive mental wellbeing, and report fewer risk-related behaviours compared to non-consenters. Overall, 69.8% of consenting students were successfully linked, with higher rates of success among younger students. The linked cohort had lower rates of mental health diagnoses (5.8% vs. 8.8%) and specialist contacts (5.2% vs. 7.7%) than general population peers. Conclusions Introducing data linkage within a national survey of adolescents had no impact on study completion rates. However, students consenting to data linkage, and those successfully linked, differed from non-consenting students on several key characteristics, raising questions concerning the representativeness of linked cohorts. Further research is needed to better understand decision-making processes around providing consent to data linkage in adolescent populations
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