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Search Results: 1 - 10 of 299217 matches for " Beverley J. Henning "
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Accretion and Jet Power
Beverley J. Wills
Physics , 1996, DOI: 10.1007/BFb0102608
Abstract: In the first of a series of three lectures we discuss ways of measuring the power available to feed the jets in powerful FR II radio sources. For unobscured radio-loud QSOs we present evidence that this power is directly related to the UV-optical luminosity, or probably more accurately, to the power radiated through processes of accretion in a strong gravitational potential. It has been suggested on theoretical grounds that powerful radio jets are a necessary component of the central engine. It then follows, from the similarity of the optical-UV power output, spectral energy distribution, and emission-line spectra of radio-loud and radio-quiet QSOs, that radio-quiet QSOs have the same power available to feed jets as do radio-loud QSOs. This then leaves us with the puzzle of why we do not see the powerful jets in radio-quiet QSOs.
An Interpretation of Radio-loud -- Radio-quiet QSO Differences
Beverley J. Wills
Physics , 1996, DOI: 10.1007/BFb0102610
Abstract: Here we speculate on what observations are telling us about the difference between radio-loud and radio-quiet QSOs. The observations are (i) the relation between ultraviolet-optical luminosity and `jet power', (ii) the dependences of emission and absorption line spectra, and the spectral energy distribution, on radio core-dominance, assumed to be an indicator of orientation, (iii) the spectral differences between radio-loud and radio-quiet QSOs, and (iv) the inverse relation between the strength of broad, blended Fe\,II multiplets and [O\,III]\,$\lambda$5007, and the apparently-related association between Fe\,II strength, reddening, broad absorption lines, and scattering polarization. We present and discuss a picture in which there are two main variables: (i) the inclination of the plane of the host galaxy to the axis of the inner jet (the central engine's rotation axis), and (ii) the angle of the line-of-sight to this rotation axis. The radio-loud QSOs are those with jets aiming away from the plane of the host galaxy.
Introduction to Unified Schemes
Beverley J. Wills
Physics , 1999,
Abstract: The differences among apparently diverse classes of AGN are mainly the result of viewing the central engine at different orientations, because dust, which absorbs and scatters the light, partially covers the central source, and because synchrotron emission is highly beamed along the relativistic jet. Also important are factors independent of orientation: the total power output, the unknown mover behind the eigenvector 1 relationships, and the radio-loudness. These other factors may not be independent of the parameters of Unified models, such as intrinsic jet physics, AGN dust content, and torus thickness. We outline the basic evidence for orientation Unified Schemes, and briefly discuss their importance for understanding the mechanisms of the central engine and its relation to the surrounding host galaxy and beyond.
MicroRNA-1 Downregulation Increases Connexin 43 Displacement and Induces Ventricular Tachyarrhythmias in Rodent Hypertrophic Hearts
Antonio Curcio, Daniele Torella, Claudio Iaconetti, Eugenia Pasceri, Jolanda Sabatino, Sabato Sorrentino, Salvatore Giampà, Mariella Micieli, Alberto Polimeni, Beverley J. Henning, Angelo Leone, Daniele Catalucci, Georgina M. Ellison, Gianluigi Condorelli, Ciro Indolfi
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0070158
Abstract: Downregulation of the muscle-specific microRNA-1 (miR-1) mediates the induction of pathologic cardiac hypertrophy. Dysfunction of the gap junction protein connexin 43 (Cx43), an established miR-1 target, during cardiac hypertrophy leads to ventricular tachyarrhythmias (VT). However, it is still unknown whether miR-1 and Cx43 are interconnected in the pro-arrhythmic context of hypertrophy. Thus, in this study we investigated whether a reduction in the extent of cardiac hypertrophy could limit the pathological electrical remodeling of Cx43 and the onset of VT by modulating miR-1 levels. Wistar male rats underwent mechanical constriction of the ascending aorta to induce pathologic left ventricular hypertrophy (LVH) and afterwards were randomly assigned to receive 10mg/kg valsartan, VAL (LVH+VAL) delivered in the drinking water or placebo (LVH) for 12 weeks. Sham surgery was performed for control groups. Programmed ventricular stimulation reproducibly induced VT in LVH compared to LVH+VAL group. When compared to sham controls, rats from LVH group showed a significant decrease of miR-1 and an increase of Cx43 expression and its ERK1/2-dependent phosphorylation, which displaces Cx43 from the gap junction. Interestingly, VAL administration to rats with aortic banding significantly reduced cardiac hypertrophy and prevented miR-1 down-regulation and Cx43 up-regulation and phosphorylation. Gain- and loss-of-function experiments in neonatal cardiomyocytes (NCMs) in vitro confirmed that Cx43 is a direct target of miR-1. Accordingly, in vitro angiotensin II stimulation reduced miR-1 levels and increased Cx43 expression and phosphorylation compared to un-stimulated NCMs. Finally, in vivo miR-1 cardiac overexpression by an adenoviral vector intra-myocardial injection reduced Cx43 expression and phosphorylation in mice with isoproterenol-induced LVH. In conclusion, miR-1 regulates Cx43 expression and activity in hypertrophic cardiomyocytes in vitro and in vivo. Treatment of pressure overload-induced myocyte hypertrophy reduces the risk of life-threatening VT by normalizing miR-1 expression levels with the consequent stabilization of Cx43 expression and activity within the gap junction.
Does Every Quasar Harbor A Blazar?
Feng Ma,Beverley J. Wills
Physics , 1998, DOI: 10.1086/311573
Abstract: Assuming there is a blazar type continuum in every radio-loud quasar, we find that the free-free heating due to the beamed infrared continuum can greatly enhance collisionally excited lines, and thus explain the stronger CIV $\lambda$1549 line emission observed in radio loud quasars. We further predict that the CIV line should show variability {\it not} associated with observed continuum or Ly$\alpha$ variability.
Optical Polarization of 52 Radio-Loud QSOs and BL Lac Objects
Natarajan Visvanathan,Beverley J. Wills,.
Physics , 1998, DOI: 10.1086/300610
Abstract: Polarization measurements are presented for 52 radio-loud QSOs and BL Lac objects. For 9 highly polarized (p >3%) AGN, these are the first published polarization measurements. Of these 9, 7 are highly-polarized QSOs (HPQs), one is a BL Lac object and another is a likely BL Lac object. Polarization variability is confirmed for some of these new and previously known highly-polarized AGN. While 6 of the HPQs have flat radio spectra are almost certainly blazars, PKS 1452-217 is probably a new member of the rare class of radio-loud QSOs that show high polarization by scattering, and is therefore important for testing orientation Unified Schemes. In competition for the highest redshift HPQ are the well-observed QSO PKS 0438-43 at z = 2.85, with maximum p = 4.7%, and PKS 0046-315 at z = 2.72, for which we find p = 13%.
Indicators of Black Hole Mass and Eddington Accretion Ratio from QSO X-ray and UV Spectra
Beverley J. Wills,Zhaohui Shang
Physics , 2003,
Abstract: The evolution of luminous QSOs is linked to the evolution of massive galaxies. We know this because the relic black-holes found locally have masses dependent on the properties of the host galaxy's bulge. An important way to explore this evolution would be to measure dependences of black hole masses and Eddington accretion ratios over a range of redshifts, i.e., with cosmological age. For low redshift QSOs (and their lower luminosity Seyfert galaxy counterparts) it has been possible to infer black hole masses from the luminosities and velocity dispersions of their host-galaxy bulges. These masses agree with those virial black hole masses calculated from the Doppler widths of the broad Hbeta emission lines. The latter method can then be extended to more distant and luminous QSOs, up to redshifts of 0.6 with ground-based optical observations. We discuss ways to extend these explorations to higher redshifts -- up to about 3 using the widths of QSOs' broad UV emission lines, and in principle, and to redshifts near 4 from ground-based infrared observations of rest-frame Hbeta at 2.5 micron. We discuss the possibility of investigating the accretion history of the higher redshift QSOs using measures of Eddington accretion ratio -- the soft X-ray spectral index and the eigenvectors of Principal Components Analyses of QSOs' UV emission-line spectra.
Discovery of Hidden Blazars
Feng Ma,Beverley J. Wills
Physics , 2001, DOI: 10.1126/science.1060412
Abstract: A blazar is believed to exist in every radio-loud quasar. This is expected in a unified scheme where the differences in both optical and radio observations of radio-loud quasars are the result of different viewing angles. We have predicted that blazars may be detected using emission line ratio variations caused by variable illumination of gas clouds in the broad emission line region. In a spectroscopic search of 62 quasars at a redshift of about 2, we have discovered large (>20%) variations of the emission line ratios, CIV/CIII] or CIV/Ly$\alpha$, when compared with historical data taken over 10 years ago. This result is consistent with our prediction, and thus supports the unification scheme for radio-loud quasars.
The desperate need for good-quality clinical trials to evaluate the optimal source and dose of fibrinogen in managing bleeding
Simon J Stanworth, Beverley J Hunt
Critical Care , 2011, DOI: 10.1186/cc10510
Abstract: In the previous issue of Critical Care, Kozek-Langenecker and colleagues [1] report the findings, as described in their title, of a 'systematic review' in which the clinical effectiveness of fresh frozen plasma (FFP) is compared with that of fibrinogen concentrate. In their conclusions, the authors indicate a 'consistent message of benefit of fibrinogen concentrate over both FFP and crystalloids/colloids on a number of outcome measures, including reduction of blood loss and allogeneic transfusions'. The key question for a reader is whether the results in this review provide confidence in these statements.We argue for extreme caution in the interpretation of the review. The main blood component as an alternative specific source of (concentrated) fibrinogen is cryoprecipitate, not FFP. It is likely that, in many studies, the FFP was given for other reasons such as to raise levels of procoagulant factors in non-bleeding patients. The criteria for inclusion of studies are very broad: the studies included were defined as taking place in the field of perioperative and 'massive' trauma, the latter of which was undefined. Many of the perioperative studies included cardiovascular surgery, and others were studies in infants. Is it appropriate to pull together studies com-paring different formulations of plasma (for example, pathogen inactivation) with studies of fibrinogen concentrate in cystectomy? Crucially, the studies cover a whole range of designs, from randomized controlled trials (RCTs) to retrospective non-comparator studies and case reports. Many studies were uncontrolled, making comparative assessments impossible.One key component of a systematic review process is methodological quality, which forms part of the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines [2] used to assess the under-taking and reporting of systematic reviews, but it is unclear how this has been undertaken in this review. Comparable standards - the Consolida
Introduction to Principal Components Analysis
Paul J. Francis,Beverley J. Wills
Physics , 1999,
Abstract: Understanding the inverse equivalent width - luminosity relationship (Baldwin Effect), the topic of this meeting, requires extracting information on continuum and emission line parameters from samples of AGN. We wish to discover whether, and how, different subsets of measured parameters may correlate with each other. This general problem is the domain of Principal Components Analysis (PCA). We discuss the purpose, principles, and the interpretation of PCA, using some examples from QSO spectroscopy. The hope is that identification of relationships among subsets of correlated variables may lead to new physical insight.
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