44 research outputs found
Measuring the Hubble constant with Type Ia supernovae as near-infrared standard candles
The most precise local measurements of rely on observations of Type Ia
supernovae (SNe Ia) coupled with Cepheid distances to SN Ia host galaxies.
Recent results have shown tension comparing to the value inferred from
CMB observations assuming CDM, making it important to check for
potential systematic uncertainties in either approach. To date, precise local
measurements have used SN Ia distances based on optical photometry, with
corrections for light curve shape and colour. Here, we analyse SNe Ia as
standard candles in the near-infrared (NIR), where intrinsic variations in the
supernovae and extinction by dust are both reduced relative to the optical.
From a combined fit to 9 nearby calibrator SNe with host Cepheid distances from
Riess et al. (2016) and 27 SNe in the Hubble flow, we estimate the absolute
peak magnitude mag and
(statistical) 2.7 (systematic) km s Mpc. The 2.2
statistical uncertainty demonstrates that the NIR provides a compelling avenue
to measuring SN Ia distances, and for our sample the intrinsic (unmodeled) peak
magnitude scatter is just 0.10 mag, even without light curve shape or
colour corrections. Our results do not vary significantly with different sample
selection criteria, though photometric calibration in the NIR may be a dominant
systematic uncertainty. Our findings suggest that tension in the competing
distance ladders is likely not a result of supernova systematics that
could be expected to vary between optical and NIR wavelengths, like dust
extinction. We anticipate further improvements in with a larger
calibrator sample of SNe Ia with Cepheid distances, more Hubble flow SNe Ia
with NIR light curves, and better use of the full NIR photometric data set
beyond simply the peak -band magnitude.Comment: 13 pages, replaced to match published version in A&A, code available
at https://github.com/sdhawan21/irh
CHANGES IN OXIDATIVE STRESS AND VASCULAR FUNCTION AS DETERMINANTS OF PROGRESSION OF ATHEROSCLEROSIS
TCT-22 Combination of High Wall Shear Stress, Plaque Burden, and Plaque Phenotype has Incremental Value for Prediction of Increased Plaque Vulnerability in Patients with Coronary Artery Disease
Fracture Risk in Men With Congestive Heart Failure Risk Reduction With Spironolactone
ObjectivesThe purpose of this study was to determine whether spironolactone use is associated with fractures in men with congestive heart failure (CHF).BackgroundIn rats with aldosteronism, spironolactone preserves skeletal strength. However, in humans, the relationship of spironolactone to fractures is not known.MethodsThe medical records of all male patients with CHF from 1999 to 2005 treated at the Veterans Affairs Medical Center, Memphis, Tennessee, were reviewed (n = 4,735). Odds ratios with 95% confidence intervals of having a fracture associated with spironolactone use were estimated using conditional logistic regression.ResultsWe identified 167 cases with a single-incident fracture and matched these by age and race to 668 control subjects without fractures. After adjustment for covariates, spironolactone use was inversely associated with total fracture (odds ratio: 0.575; 95% confidence interval: 0.346 to 0.955, p = 0.0324).ConclusionsThe use of spironolactone is inversely associated with fractures in men with CHF