3,924 research outputs found
Basal and hyperaemic myocardial blood flow in regionally denervated canine hearts: an in vivo study with positron emission tomography
No full textTotal eclipse of the heart: : the AM CVn Gaia14aae/ASSASN-14cn
No full textWe report the discovery and characterization of a deeply eclipsing AM CVn-system, Gaia14aae (=ASSASN-14cn). Gaia14aae was identified independently by the All-Sky Automated Survey for Supernovae (ASAS-SN; Shappee et al.) and by the Gaia Science Alerts project, during two separate outbursts. A third outburst is seen in archival Pan-STARRS-1 (PS1; Schlafly et al.; Tonry et al.; Magnier et al.) and ASAS-SN data. Spectroscopy reveals a hot, hydrogen-deficient spectrum with clear double-peaked emission lines, consistent with an accreting double-degenerate classification. We use follow-up photometry to constrain the orbital parameters of the system. We find an orbital period of 49.71 min, which places Gaia14aae at the long period extremum of the outbursting AM CVn period distribution. Gaia14aae is dominated by the light from its accreting white dwarf (WD). Assuming an orbital inclination of 90° for the binary system, the contact phases of the WD lead to lower limits of 0.78 and 0.015 M⊙ on the masses of the accretor and donor, respectively, and a lower limit on the mass ratio of 0.019. Gaia14aae is only the third eclipsing AM CVn star known, and the first in which the WD is totally eclipsed. Using a helium WD model, we estimate the accretor's effective temperature to be 12 900 ± 200 K. The three outburst events occurred within four months of each other, while no other outburst activity is seen in the previous 8 yr of Catalina Real-time Transient Survey (CRTS; Drake et al.), Pan-STARRS-1 and ASAS-SN data. This suggests that these events might be rebrightenings of the first outburst rather than individual events.Peer reviewe
1000 cataclysmic variables from the Catalina Real-time Transient Survey
No full textOver six years of operation, the Catalina Real-time Transient Survey (CRTS) has identified 1043 cataclysmic variable (CV) candidates - the largest sample of CVs from a single survey to date. Here, we provide spectroscopic identification of 85 systems fainter than g > 19, including three AM Canum Venaticorum binaries, one helium-enriched CV, one polar and one new eclipsing CV. We analyse the outburst properties of the full sample and show that it contains a large fraction of low-accretion-rate CVs with long outburst recurrence times. We argue that most of the high-accretion-rate dwarf novae in the survey footprint have already been found and that future CRTS discoveries will be mostly low-accretion-rate systems. We find that CVs with white-dwarf-dominated spectra have significantly fewer outbursts in their CRTS light curves compared to disc-dominated CVs, reflecting the difference in their accretion rates. Comparing the CRTS sample to other samples of CVs, we estimate the overall external completeness to be 23.6 per cent, but show that as much as 56 per cent of CVs have variability amplitudes that are too small to be selected using the transient selection criteria employed by current ground-based surveys. The full table of CRTS CVs, including their outburst and spectroscopic properties examined in this paper, is provided in the online materials
Nocturia Think Tank: Focus on Nocturnal Polyuria: Report from the ICI-RS 2011
No full textWeiss JP, Ruud Bosch JL, Drake M, Dmochowski RR, Hashim H, Hijaz A, Johnson TM, Juul K, Nørgaard JP, Norton P, Robinson D, Tikkinen KA, Van Kerrebroeck PE, Wein AJ. . Neurourol Urodyn 2012; 31:330-
On the AJ Conjecture for Knots
No full textWe confirm the AJ conjecture [Ga2] that relates the A-polynomial and the colored Jones polynomial for hyperbolic knots satisfying certain conditions. In particular, we show that the conjecture holds true for some classes of two-bridge knots and pretzel knots. This extends the result of the first author in [Le2], who established the AJ conjecture for a large class of two-bridge knots, including all twist knots. Along the way, we explicitly calculate the universal SL₂(C)-character ring of the knot group of the (−2, 3, 2n + 1)-pretzel knot, and show it is reduced for all integers n
Discovery of a single faint AGN in a large sample of z > 5 Lyman break galaxies
No full textAs part of a large spectroscopic survey of z > 5 Lyman break galaxies (LBGs), we have identified a single source which is clearly hosting an active galactic nucleus (AGN). Out of a sample of more than 50 spectroscopically confirmed R-band dropout galaxies at z∼ 5 and above, only J104048.6−115550.2 at z= 5.44 shows evidence for a high ionization potential emission line indicating the presence of a hard ionizing continuum from an AGN. Like most objects in our sample the rest-frame-UV spectrum shows the UV continuum breaking across a Lyα line. Uniquely within this sample of LBGs, emission from N V is also detected, a clear signature of AGN photoionization. The object is spatially resolved in Hubble Space Telescope (HST) imaging. This, and the comparatively high Lyα/N V flux ratio indicates that the majority of the Lyα (and the UV continuum longward of it) originates from stellar photoionization, a product of the ongoing starburst in the LBG. Even without the AGN emission, this object would have been photometrically selected and spectroscopically confirmed as a Lyman break in our survey. The measured optical flux (IAB= 26.1) is therefore an upper limit to that from the AGN and is of order 100 times fainter than the majority of known quasars at these redshifts. The detection of a single object in our survey volume is consistent with the best current models of high redshift AGN luminosity function, providing a substantial fraction of such AGN is found within luminous starbursting galaxies. We discuss the cosmological implications of this discovery
Programming of cardiovascular disease: an exploration of epigenetic mechanisms
No full textFetal exposure to excess glucocorticoid is associated with low birth weight and
increased cardiovascular disease risk in first generation offspring. Such phenotypes
can be produced experimentally through the administration of the synthetic
glucocorticoid dexamethasone (Dex) to pregnant rats during the last week of
gestation. These ‘programmed effects’ can be transmitted to a second generation
through both maternal and paternal lines. The overall hypothesis for this thesis was
that the transmission of programmed effects through the male line may result from
alterations in fetal germ cells, which form sperm in adulthood.
Epigenetic reprogramming of germ cells is characterised by the genome-wide erasure
and subsequent re-establishment of 5-methylcytosine (5mC), however this process
has not previously been described for the rat. Furthermore, the involvement of more
recently identified cytosine modifications; 5-hydroxymethylcytosine (5hmC), 5-
formylcytosine (5fC) and 5-carboxylcytosine (5caC), has not been characterised
during germ cell ontogeny. Using immunofluorescence to study DNA modifications
during late gestation I identified that 5hmC, 5fC and 5caC were present between
e14.5 and e16.5 but absent thereafter. In contrast, 5mC was absent during this time
but remethylation was noted from e19.5 onwards. Prenatal Dex exposure was
associated with the presence of significantly more 5mC-positive germ cells at e19.5
relative to controls. This difference did not persist at e20.5 suggesting that Dex
exposure promotes premature global remethylation. The mechanisms for this are
unclear since there were no differences between groups in the localisation of the
DNA methyltransferases DNMT3a and 3b, or in markers of normal testis maturation.
To enable the study of gene-specific changes in DNA methylation in the germline a
colony of Germ Cell Specific-Enhanced Green Fluorescent Protein (GCS-EGFP) rats
was established and characterised. GCS-EGFP rats had a transgenerational decrease
in pup weight with Dex exposure, as in Wistar rats. The expression of both
established and novel candidate genes was compared between strains. Multiple genes
across different pathways had altered expression, with some affected in both Wistar
and GCS-EGFP rats, whilst other differences were strain-specific. Enhanced
Reduced Representation Bisulfite Sequencing was performed on liver and fetal germ
cells from males exposed to Dex in utero to explore effects on DNA methylation.
These studies confirm that epigenetic reprogramming occurs in the rat and that this
process may be susceptible to modification by prenatal Dex exposure. GCS-EGFP
rats also exhibited a Dex programming phenotype, with decreased pup weight and
altered liver gene expression. The use of this unique strain of rats will permit
dissection of the mechanisms for the transmission of programmed phenotypes across
generations
The author, the text, and the (post)critic: notes on the encounter between postcritique and postcolonial criticism
No full textThe article confronts postcolonial criticism with postcritique, a proposal by Rita Felski for a hermeneutic strategy aiming to overcome the limits of critique. Because of its self-reflexivity, its liaison with poststructuralism, and the societal categories it mobilizes, postcritics often see postcolonial criticism as a quintessential example of critique. However, postcolonial authors share similar concerns as postcritics, particularly when warning against any hasty conflation between intellectual work and political commitment. This article argues that the postcritical understanding of critique eschews the connection between critique and the realm of culture, thereby running the risk of doing away with context altogether. In order to account for the frameworks or contexts in which cultural objects are produced, without falling into some of the pitfalls of critique that postcritique aims to counter, the article proposes to look at the figure of the author as a bridge between the individual and the collective, as Edward Said suggests. The article closes with an analysis of several (critical and postcritical) readings of J. M. Coetzee’s The Childhood of Jesus to provide an example of how authorship can enter the interpretive scene through the figure of ‘late style’
Exploring the roles, effectiveness and impact of health information professionals within evidence based practice
No full textThis is the thesis (critical appraisal) component of a PhD by Published Works. The overall submission was a portfolio of ten published papers supported by a critical appraisal focusing on two key areas: an exploration of the roles that Health Information Professionals (HIPs) can play within evidence based practice (EBP) and an exploration of the effectiveness and impact of the traditional supportive role played by HIPs within EBP. The published papers are listed and referenced within this document but not contained within it. The majority are available elsewhere within the University of Salford Institutional Repository.Drawing on a model developed from the library literature, the thesis highlights a wide range of supportive and active roles that HIPs can potentially play within EBP. This model is informed and illuminated by the studies within the portfolio that demonstrate how the author has fulfilled a wide range of these roles in practice, and identified a new role within systematic reviews in health and social care. This demonstrates that HIPs can transfer their skills outside their traditional library and information practice domain, thus extending theirrole and offering a range of professional opportunities.Using a varied range of research methodologies, the thesis also explores the effectiveness and impact of the contribution made by HIPs when using traditional skills to support EBP. Two models are used to illustrate the outcomes to which HIPs contribute. These include improving search skills and providing evidence which can, over the longer term, contribute to policy making and patient care. At present the weight of the evidence presented tosupport these links is weak. Methodological issues and future research that needs to be addressed to improve the strength of the evidence base are therefore highlighted and discussed
The XMM-Newton long look of NGC 1365: uncovering of the obscured X-ray source
No full textWe present an analysis of the extreme obscuration variability observed during an XMM–Newton 5-d continuous monitoring of the active galactic nuclei (AGN) in NGC 1365. The source was in a reflection-dominated state in the first ∼1.5 d, then a strong increase in the 7–10 keV emission was observed in ∼10 h, followed by a symmetric decrease. The spectral analysis of the different states clearly shows that this variation is due to an uncovering of the X-ray source. From this observation, we estimate a size of the X-ray source DS < 1013 cm, a distance of the obscuring clouds R∼ 1016 cm and a density n∼ 1011 cm−3. These values suggest that the X-ray absorption/reflection originates from the broad-line region clouds. This is also supported by the resolved width of the iron narrow Kα emission line, consistent with the width of the broad Hβ line
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