283 research outputs found
Endothelin and increased contractility in adult rat ventricular myocytes. Role of intracellular alkalosis induced by activation of the protein kinase C-dependent Na(+)-H+ exchanger.
Secular Evolution and the Formation of Pseudobulges in Disk Galaxies
We review internal processes of secular evolution in galaxy disks,
concentrating on the buildup of dense central features that look like
classical, merger-built bulges but that were made slowly out of disk gas. We
call these pseudobulges. As an existence proof, we review how bars rearrange
disk gas into outer rings, inner rings, and gas dumped into the center. In
simulations, this gas reaches high densities that plausibly feed star
formation. In the observations, many SB and oval galaxies show central
concentrations of gas and star formation. Star formation rates imply plausible
pseudobulge growth times of a few billion years. If secular processes built
dense central components that masquerade as bulges, can we distinguish them
from merger-built bulges? Observations show that pseudobulges retain a memory
of their disky origin. They have one or more characteristics of disks: (1)
flatter shapes than those of classical bulges, (2) large ratios of ordered to
random velocities indicative of disk dynamics, (3) small velocity dispersions,
(4) spiral structure or nuclear bars in the bulge part of the light profile,
(5) nearly exponential brightness profiles, and (6) starbursts. These
structures occur preferentially in barred and oval galaxies in which secular
evolution should be rapid. So the cleanest examples of pseudobulges are
recognizable. Thus a large variety of observational and theoretical results
contribute to a new picture of galaxy evolution that complements hierarchical
clustering and merging.Comment: 92 pages, 21 figures in 30 Postscript files; to appear in Annual
Review of Astronomy and Astrophysics, Vol. 42, 2004, in press; for a version
with full resolution figures, see
http://chandra.as.utexas.edu/~kormendy/ar3ss.htm
Sensitivity and specificity of blood-fluid levels for oral anticoagulant-associated intracerebral haemorrhage
Intracerebral haemorrhage (ICH) is a life-threatening emergency, the incidence of which has increased in part due to an increase in the use of oral anticoagulants. A blood-fluid level within the haematoma, as revealed by computed tomography (CT), has been suggested as a marker for oral anticoagulant-associated ICH (OAC-ICH), but the diagnostic specificity and prognostic value of this finding remains unclear. In 855 patients with CT-confirmed acute ICH scanned within 48 h of symptom onset, we investigated the sensitivity and specificity of the presence of a CT-defined blood-fluid level (rated blinded to anticoagulant status) for identifying concomitant anticoagulant use. We also investigated the association of the presence of a blood-fluid level with six-month case fatality. Eighteen patients (2.1%) had a blood-fluid level identified on CT; of those with a blood-fluid level, 15 (83.3%) were taking anticoagulants. The specificity of blood-fluid level for OAC-ICH was 99.4%; the sensitivity was 4.2%. We could not detect an association between the presence of a blood-fluid level and an increased risk of death at six months (OR = 1.21, 95% CI 0.28–3.88, p = 0.769). The presence of a blood-fluid level should alert clinicians to the possibility of OAC-ICH, but absence of a blood-fluid level is not useful in excluding OAC-ICH
HIV-Specific T-Cells Accumulate in the Liver in HCV/HIV Co-Infection
BACKGROUND AND AIMS: Hepatitis C Virus (HCV)-related liver disease progresses more rapidly in individuals co-infected with Human Immunodeficiency Virus-1 (HIV), although the underlying immunologic mechanisms are unknown. We examined whether HIV-specific T-cells are identified in the liver of HCV/HIV co-infected individuals and promote liver inflammation through bystander immune responses. METHODS: Ex-vivo intra-hepatic lymphocytes from HCV mono-infected and HCV/HIV co-infected individuals were assessed for immune responses to HIV and HCV antigens by polychromatic flow cytometry. RESULTS: HCV/HIV liver biopsies had similar frequencies of lymphocytes but lower percentages of CD4+ T-cells compared to HCV biopsies. In co-infection, intra-hepatic HIV-specific CD8+ and CD4+ T-cells producing IFN-gamma and TNF-alpha were detected and were comparable in frequency to those that were HCV-specific. In co-infected individuals, viral-specific CD8+ T-cells produced more of the fibrogenic cytokine, TNF-alpha. In both mono- and co-infected individuals, intra-hepatic HCV-specific T-cells were poorly functional compared to HIV-specific T-cells. In co-infection, HAART was not associated with a reconstitution of intra-hepatic CD4+ T-cells and was associated with reduction in both HIV and HCV-specific intra-hepatic cytokine responses. CONCLUSION: The accumulation of functional HIV-specific T-cells in the liver during HCV/HIV co-infection may represent a bystander role for HIV in inducing faster progression of liver disease
A review of elliptical and disc galaxy structure, and modern scaling laws
A century ago, in 1911 and 1913, Plummer and then Reynolds introduced their
models to describe the radial distribution of stars in `nebulae'. This article
reviews the progress since then, providing both an historical perspective and a
contemporary review of the stellar structure of bulges, discs and elliptical
galaxies. The quantification of galaxy nuclei, such as central mass deficits
and excess nuclear light, plus the structure of dark matter halos and cD galaxy
envelopes, are discussed. Issues pertaining to spiral galaxies including dust,
bulge-to-disc ratios, bulgeless galaxies, bars and the identification of
pseudobulges are also reviewed. An array of modern scaling relations involving
sizes, luminosities, surface brightnesses and stellar concentrations are
presented, many of which are shown to be curved. These 'redshift zero'
relations not only quantify the behavior and nature of galaxies in the Universe
today, but are the modern benchmark for evolutionary studies of galaxies,
whether based on observations, N-body-simulations or semi-analytical modelling.
For example, it is shown that some of the recently discovered compact
elliptical galaxies at 1.5 < z < 2.5 may be the bulges of modern disc galaxies.Comment: Condensed version (due to Contract) of an invited review article to
appear in "Planets, Stars and Stellar
Systems"(www.springer.com/astronomy/book/978-90-481-8818-5). 500+ references
incl. many somewhat forgotten, pioneer papers. Original submission to
Springer: 07-June-201
Adenosine-stress cardiac magnetic resonance imaging in suspected coronary artery disease: a net cost analysis and reimbursement implications
The health and economic implications of new imaging technologies are increasingly relevant policy issues. Cardiac magnetic resonance imaging (CMR) is currently not or not sufficiently reimbursed in a number of countries including Germany, presumably because of a limited evidence base. It is unknown, however, whether it can be effectively used to facilitate medical decision-making and reduce costs by serving as a gatekeeper to invasive coronary angiography. We investigated whether the application of CMR in patients suspected of having coronary artery disease (CAD) reduces costs by averting referrals to cardiac catheterization. We used propensity score methods to match 218 patients from a CMR registry to a previously studied cohort in which CMR was demonstrated to reliably identify patients who were low-risk for major cardiac events. Covariates over which patients were matched included comorbidity profiles, demographics, CAD-related symptoms, and CAD risk as measured by Morise scores. We determined the proportion of patients for whom cardiac catheterization was deferred based upon CMR findings. We then calculated the economic effects of practice pattern changes using data on cardiac catheterization and CMR costs. CMR reduced the utilization of cardiac catheterization by 62.4%. Based on estimated catheterization costs of € 619, the utilization of CMR as a gatekeeper reduced per-patient costs by a mean of € 90. Savings were realized until CMR costs exceeded € 386. Cost savings were greatest for patients at low-risk for CAD, as measured by baseline Morise scores, but were present for all Morise subgroups with the exception of patients at the highest risk of CAD. CMR significantly reduces the utilization of cardiac catheterization in patients suspected of having CAD. Per-patient savings range from € 323 in patients at lowest risk of CAD to € 58 in patients at high-risk but not in the highest risk stratum. Because a negative CMR evaluation has high negative predictive value, its application as a gatekeeper to cardiac catheterization should be further explored as a treatment option
Limits on WWZ and WW\gamma couplings from p\bar{p}\to e\nu jj X events at \sqrt{s} = 1.8 TeV
We present limits on anomalous WWZ and WW-gamma couplings from a search for
WW and WZ production in p-bar p collisions at sqrt(s)=1.8 TeV. We use p-bar p
-> e-nu jjX events recorded with the D0 detector at the Fermilab Tevatron
Collider during the 1992-1995 run. The data sample corresponds to an integrated
luminosity of 96.0+-5.1 pb^(-1). Assuming identical WWZ and WW-gamma coupling
parameters, the 95% CL limits on the CP-conserving couplings are
-0.33<lambda<0.36 (Delta-kappa=0) and -0.43<Delta-kappa<0.59 (lambda=0), for a
form factor scale Lambda = 2.0 TeV. Limits based on other assumptions are also
presented.Comment: 11 pages, 2 figures, 2 table
The Dijet Mass Spectrum and a Search for Quark Compositeness in bar{p}p Collisions at sqrt{s} = 1.8 TeV
Using the DZero detector at the 1.8 TeV pbarp Fermilab Tevatron collider, we
have measured the inclusive dijet mass spectrum in the central pseudorapidity
region |eta_jet| < 1.0 for dijet masses greater than 200 Gev/c^2. We have also
measured the ratio of spectra sigma(|eta_jet| < 0.5)/sigma(0.5 < |eta_jet| <
1.0). The order alpha_s^3 QCD predictions are in good agreement with the data
and we rule out models of quark compositeness with a contact interaction scale
< 2.4 TeV at the 95% confidence level.Comment: 11 pages, 4 figures, 2 tables, submitted to Phys. Rev. Let
Search for High Mass Photon Pairs in p-pbar --> gamma-gamma-jet-jet Events at sqrt(s)=1.8 TeV
A search has been carried out for events in the channel p-barp --> gamma
gamma jet jet. Such a signature can characterize the production of a
non-standard Higgs boson together with a W or Z boson. We refer to this
non-standard Higgs, having standard model couplings to vector bosons but no
coupling to fermions, as a "bosonic Higgs." With the requirement of two high
transverse energy photons and two jets, the diphoton mass (m(gamma gamma))
distribution is consistent with expected background. A 90(95)% C.L. upper limit
on the cross section as a function of mass is calculated, ranging from
0.60(0.80) pb for m(gamma gamma) = 65 GeV/c^2 to 0.26(0.34) pb for m(gamma
gamma) = 150 GeV/c^2, corresponding to a 95% C.L. lower limit on the mass of a
bosonic Higgs of 78.5 GeV/c^2.Comment: 9 pages, 3 figures. Replacement has new H->gamma gamma branching
ratios and corresponding new mass limit
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