194 research outputs found

    Extremely red radio galaxies

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    At least half the radio galaxies at z>1 in the 7C Redshift Survey have extremely red colours (R-K>5), consistent with stellar populations which formed at high redshift (z>5). We discuss the implications of this for the evolution of massive galaxies in general and for the fraction of near-IR-selected EROs which host AGN, a result which is now being tested by deep, hard X-ray surveys. The conclusion is that many massive galaxies undergo at least two active phases: one at z~5 when the black hole and stellar bulge formed and another at z~1-2 when activity is triggered by an event such as an interaction or merger.Comment: 6 pages, 2 figures, to appear in the proceedings of the workshop on "QSO hosts and their environments", IAA, Granada, 10-12 Jan 2001, Ed. I. Marque

    The highly rearranged mitochondrial genomes of the crabs Maja crispata and Maja squinado (Majidae) and gene order evolution in Brachyura

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    Abstract We sequenced the mitochondrial genomes of the spider crabs Maja crispata and Maja squinado (Majidae, Brachyura). Both genomes contain the whole set of 37 genes characteristic of Bilaterian genomes, encoded on both \u3b1- and \u3b2-strands. Both species exhibit the same gene order, which is unique among known animal genomes. In particular, all the genes located on the \u3b2-strand form a single block. This gene order was analysed together with the other nine gene orders known for the Brachyura. Our study confirms that the most widespread gene order (BraGO) represents the plesiomorphic condition for Brachyura and was established at the onset of this clade. All other gene orders are the result of transformational pathways originating from BraGO. The different gene orders exhibit variable levels of genes rearrangements, which involve only tRNAs or all types of genes. Local homoplastic arrangements were identified, while complete gene orders remain unique and represent signatures that can have a diagnostic value. Brachyura appear to be a hot-spot of gene order diversity within the phylum Arthropoda. Our analysis, allowed to track, for the first time, the fully evolutionary pathways producing the Brachyuran gene orders. This goal was achieved by coupling sophisticated bioinformatic tools with phylogenetic analysis

    Structural Analysis of Papain-Like NlpC/P60 Superfamily Enzymes with a Circularly Permuted Topology Reveals Potential Lipid Binding Sites

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    NlpC/P60 superfamily papain-like enzymes play important roles in all kingdoms of life. Two members of this superfamily, LRAT-like and YaeF/YiiX-like families, were predicted to contain a catalytic domain that is circularly permuted such that the catalytic cysteine is located near the C-terminus, instead of at the N-terminus. These permuted enzymes are widespread in virus, pathogenic bacteria, and eukaryotes. We determined the crystal structure of a member of the YaeF/YiiX-like family from Bacillus cereus in complex with lysine. The structure, which adopts a ligand-induced, “closed” conformation, confirms the circular permutation of catalytic residues. A comparative analysis of other related protein structures within the NlpC/P60 superfamily is presented. Permutated NlpC/P60 enzymes contain a similar conserved core and arrangement of catalytic residues, including a Cys/His-containing triad and an additional conserved tyrosine. More surprisingly, permuted enzymes have a hydrophobic S1 binding pocket that is distinct from previously characterized enzymes in the family, indicative of novel substrate specificity. Further analysis of a structural homolog, YiiX (PDB 2if6) identified a fatty acid in the conserved hydrophobic pocket, thus providing additional insights into possible function of these novel enzymes

    Cognitive ability and physical health:A Mendelian randomization study

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    Causes of the association between cognitive ability and health remain unknown, but may reflect a shared genetic aetiology. This study examines the causal genetic associations between cognitive ability and physical health. We carried out two-sample Mendelian randomization analyses using the inverse-variance weighted method to test for causality between later life cognitive ability, educational attainment (as a proxy for cognitive ability in youth), BMI, height, systolic blood pressure, coronary artery disease, and type 2 diabetes using data from six independent GWAS consortia and the UK Biobank sample (N = 112 151). BMI, systolic blood pressure, coronary artery disease and type 2 diabetes showed negative associations with cognitive ability; height was positively associated with cognitive ability. The analyses provided no evidence for casual associations from health to cognitive ability. In the other direction, higher educational attainment predicted lower BMI, systolic blood pressure, coronary artery disease, type 2 diabetes, and taller stature. The analyses indicated no causal association from educational attainment to physical health. The lack of evidence for causal associations between cognitive ability, educational attainment, and physical health could be explained by weak instrumental variables, poorly measured outcomes, or the small number of disease cases

    Structural and Sequence Analysis of Imelysin-Like Proteins Implicated in Bacterial Iron Uptake

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    Imelysin-like proteins define a superfamily of bacterial proteins that are likely involved in iron uptake. Members of this superfamily were previously thought to be peptidases and were included in the MEROPS family M75. We determined the first crystal structures of two remotely related, imelysin-like proteins. The Psychrobacter arcticus structure was determined at 2.15 Å resolution and contains the canonical imelysin fold, while higher resolution structures from the gut bacteria Bacteroides ovatus, in two crystal forms (at 1.25 Å and 1.44 Å resolution), have a circularly permuted topology. Both structures are highly similar to each other despite low sequence similarity and circular permutation. The all-helical structure can be divided into two similar four-helix bundle domains. The overall structure and the GxHxxE motif region differ from known HxxE metallopeptidases, suggesting that imelysin-like proteins are not peptidases. A putative functional site is located at the domain interface. We have now organized the known homologous proteins into a superfamily, which can be separated into four families. These families share a similar functional site, but each has family-specific structural and sequence features. These results indicate that imelysin-like proteins have evolved from a common ancestor, and likely have a conserved function

    Foundations of Black Hole Accretion Disk Theory

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    This review covers the main aspects of black hole accretion disk theory. We begin with the view that one of the main goals of the theory is to better understand the nature of black holes themselves. In this light we discuss how accretion disks might reveal some of the unique signatures of strong gravity: the event horizon, the innermost stable circular orbit, and the ergosphere. We then review, from a first-principles perspective, the physical processes at play in accretion disks. This leads us to the four primary accretion disk models that we review: Polish doughnuts (thick disks), Shakura-Sunyaev (thin) disks, slim disks, and advection-dominated accretion flows (ADAFs). After presenting the models we discuss issues of stability, oscillations, and jets. Following our review of the analytic work, we take a parallel approach in reviewing numerical studies of black hole accretion disks. We finish with a few select applications that highlight particular astrophysical applications: measurements of black hole mass and spin, black hole vs. neutron star accretion disks, black hole accretion disk spectral states, and quasi-periodic oscillations (QPOs).Comment: 91 pages, 23 figures, final published version available at http://www.livingreviews.org/lrr-2013-

    A web-based intervention to promote physical activity in adolescents and young adults with cystic fibrosis: protocol for a randomized controlled trial

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    BACKGROUND Regular participation in physical activity by people with cystic fibrosis (CF) promotes positive clinical and health outcomes including reduced rate of decline in lung function, fewer hospitalizations and greater wellbeing. However adherence to exercise and activity programs is low, in part due to the substantial daily therapy burden for young people with CF. Strict infection control requirements limit the role of group exercise programs that are commonly used in other clinical groups. Investigation of methods to promote physical activity in this group has been limited. The Active Online Physical Activity in Cystic fibrosis Trial (ActionPACT) is an assessor-blinded, multi-centre, randomized controlled trial designed to compare the efficacy of a novel web-based program (ActivOnline) compared to usual care in promoting physical activity participation in adolescents and young adults with CF. METHODS Adolescents and young adults with CF will be recruited on discharge from hospital for a respiratory exacerbation. Participants randomized to the intervention group will have access to a web-based physical activity platform for the 12-week intervention period. ActivOnline allows users to track their physical activity, set goals, and self-monitor progress. All participants in both groups will be provided with standardised information regarding general physical activity recommendations for adolescents and young adults. Outcomes will be assessed by a blinded assessor at baseline, after completion of the intervention, and at 3-months followup. Healthcare utilization will be assessed at 12 months from intervention completion. The primary outcome is change in moderate-to-vigorous physical activity participation measured objectively by accelerometry. Secondary outcomes include aerobic fitness, health-related quality of life, anxiety and depression and sleep quality. DISCUSSION This trial will establish whether a web-based application can improve physical activity participation more effectively than usual care in the period following hospitalization for a respiratory exacerbation. The web-based application under investigation can be made readily and widely available to all individuals with CF, to support physical activity and exercise participation at a time and location of the user’s choosing, regardless of microbiological status. TRIAL REGISTRATION Clinical trial registered on July 13, 2017 with the Australian and New Zealand Clinical Trials Register at (ACTRN12617001009303)

    Web-based physical activity promotion in young people with CF: a randomised controlled trial

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    This is the author accepted manuscript. The final version is available from BMJ Publishing Group via the DOI in this recordData availability statement: Data are available on reasonable request. Data requests should, in the first instance, be addressed to Professor Anne Holland ([email protected]). Access to data will be subject to approval by the coordinating principal investigator and relevant Human Research Ethics Committee.Background Physical activity levels are known to decline following hospitalisation for people with cystic fibrosis (pwCF). However, optimal physical activity promotion strategies are unclear. This study investigated the effect of a web-based application (ActivOnline) in promoting physical activity in young pwCF. Methods Multicentre randomised controlled trial with assessor blinding and qualitative evaluation. People with CF (12–35 years) admitted to hospital for a respiratory cause were eligible and randomised to the 12-week ActivOnline intervention (AO) or usual care (UC). The primary outcome was change in device-based time spent in moderate-to-vigorous physical activity (MVPA) from baseline to post-intervention. Follow-up was at 6 months from hospital discharge when qualitative evaluation was undertaken. Results 107 participants were randomised to AO (n=52) or UC (n=55). Sixty-three participants (59%) contributed to the intention-to-treat analysis. Mean (SD) age was 21 (6) years (n=46, <18 years). At baseline, physical activity levels were high in both groups (AO 102 (52) vs UC 127 (73) min/day). There was no statistically significant difference in MVPA between groups at either timepoint (post-intervention mean difference (95% CI) −14 mins (−45 to 16)). Uptake of the intervention was low with only 40% (n=21) of participants accessing the web application. Conclusion A web-based application, including individualised goal setting, real-time feedback and motivation for behavioural change, was no better than usual care at promoting physical activity in young pwCF following hospital discharge. High levels of baseline physical activity levels in both groups, and limited engagement with the intervention, suggest alternative strategies may be necessary to identify and support young pwCF who would benefit from enhanced physical activity. Trial registration number ACTRN12617001009303, 13 July 13 2017.Cystic Fibrosis Trus

    Clinical, laboratory and pathological findings in dogs experimentally infected with Angiostrongylus vasorum

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    The aim of this comparative study was to investigate the development of clinical signs and accompanying haematological, coproscopic and pathological findings as a basis for the monitoring of health condition of Angiostrongylus vasorum infected dogs. Six beagles were orally inoculated with 50 (n = 3) or 500 (n = 3) A. vasorum third stage larvae (L3) obtained from experimentally infected Biomphalaria glabrata snails. Two dogs were treated with moxidectin/imidacloprid spot-on solution and two further dogs with an oral experimental compound 92 days post infection (dpi), and were necropsied 166 dpi. Two untreated control dogs were necropsied 97 dpi. Prepatency was 47-49 days. Dogs inoculated with 500 L3 exhibited earlier (from 42 dpi) and more severe respiratory signs. Clinical signs resolved 12 days after treatment and larval excretion stopped within 20 days in all four treated dogs. Upon necropsy, 10 and 170 adult worms were recovered from the untreated dogs inoculated with 50 and 500 L3, respectively. Adult worms were also found in two treated dogs, in the absence of L1 or eggs. Despite heavy A. vasorum infection load and severe pulmonary changes including vascular thrombosis, only mild haematological changes were observed. Eosinophilia was absent but the presence of plasma cells was observed. Neutrophilic leucocytes showed a transient increase but only after treatment. Signs for coagulopathies were slight; nevertheless coagulation parameters were inoculation dose dependent. Ten weeks after treatment pulmonary fibrosis was still present. Infections starting from 50 L3 of A. vasorum had a massive impact on lung tissues and therefore on the health of affected dogs, particularly after prepatency, although only mild haematological abnormalities were evident

    A web-based intervention to promote physical activity in adolescents and young adults with cystic fibrosis: protocol for a randomized controlled trial.

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    This is the final version. Available from BMC via the DOI in this record. BACKGROUND: Regular participation in physical activity by people with cystic fibrosis (CF) promotes positive clinical and health outcomes including reduced rate of decline in lung function, fewer hospitalizations and greater wellbeing. However adherence to exercise and activity programs is low, in part due to the substantial daily therapy burden for young people with CF. Strict infection control requirements limit the role of group exercise programs that are commonly used in other clinical groups. Investigation of methods to promote physical activity in this group has been limited. The Active Online Physical Activity in Cystic fibrosis Trial (ActionPACT) is an assessor-blinded, multi-centre, randomized controlled trial designed to compare the efficacy of a novel web-based program (ActivOnline) compared to usual care in promoting physical activity participation in adolescents and young adults with CF. METHODS: Adolescents and young adults with CF will be recruited on discharge from hospital for a respiratory exacerbation. Participants randomized to the intervention group will have access to a web-based physical activity platform for the 12-week intervention period. ActivOnline allows users to track their physical activity, set goals, and self-monitor progress. All participants in both groups will be provided with standardised information regarding general physical activity recommendations for adolescents and young adults. Outcomes will be assessed by a blinded assessor at baseline, after completion of the intervention, and at 3-months followup. Healthcare utilization will be assessed at 12 months from intervention completion. The primary outcome is change in moderate-to-vigorous physical activity participation measured objectively by accelerometry. Secondary outcomes include aerobic fitness, health-related quality of life, anxiety and depression and sleep quality. DISCUSSION: This trial will establish whether a web-based application can improve physical activity participation more effectively than usual care in the period following hospitalization for a respiratory exacerbation. The web-based application under investigation can be made readily and widely available to all individuals with CF, to support physical activity and exercise participation at a time and location of the user's choosing, regardless of microbiological status. TRIAL REGISTRATION: Clinical trial registered on July 13, 2017 with the Australian and New Zealand Clinical Trials Register at (ACTRN12617001009303).Cystic Fibrosis Trus
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