Impact of echocardiographic left ventricular geometry on clinical prognosis

Abnormal left ventricular (LV) geometry, including LV hypertrophy (LVH), is associated with increased risk of major cardiovascular (CV) events and all-cause mortality and may be an independent predictor of morbid CV events. Patients with LVH have increased risk of congestive heart failure, coronary heart disease, sudden cardiac death and stroke. We review the risk factors for LVH and its consequences, as well as the risk imposed by concentric remodeling (CR). We also examine evidence supporting the benefits of LVH regression, as well as evidence regarding the risk of CR progressing to LVH, as opposed to normalization of CR. We also briefly review the association of abnormal LV geometry with left atrial enlargement and the combined effects of these structural cardiac abnormalities

Kepler Mission Stellar and Instrument Noise Properties

Kepler Mission results are rapidly contributing to fundamentally new discoveries in both the exoplanet and asteroseismology fields. The data returned from Kepler are unique in terms of the number of stars observed, precision of photometry for time series observations, and the temporal extent of high duty cycle observations. As the first mission to provide extensive time series measurements on thousands of stars over months to years at a level hitherto possible only for the Sun, the results from Kepler will vastly increase our knowledge of stellar variability for quiet solar-type stars. Here we report on the stellar noise inferred on the timescale of a few hours of most interest for detection of exoplanets via transits. By design the data from moderately bright Kepler stars are expected to have roughly comparable levels of noise intrinsic to the stars and arising from a combination of fundamental limitations such as Poisson statistics and any instrument noise. The noise levels attained by Kepler on-orbit exceed by some 50% the target levels for solar-type, quiet stars. We provide a decomposition of observed noise for an ensemble of 12th magnitude stars arising from fundamental terms (Poisson and readout noise), added noise due to the instrument and that intrinsic to the stars. The largest factor in the modestly higher than anticipated noise follows from intrinsic stellar noise. We show that using stellar parameters from galactic stellar synthesis models, and projections to stellar rotation, activity and hence noise levels reproduces the primary intrinsic stellar noise features.Comment: Accepted by ApJ; 26 pages, 20 figure

Prognostic implications of left ventricular hypertrophy

Left ventricular hypertrophy (LVH) was one of the earliest studied echocardiographic characteristics of the left ventricle. As the myriad of measurable metrics has multiplied over recent years, this reliable and relevant variable can often be overlooked. In this paper, we discuss appropriate techniques for accurate analysis, underlying pathophysiology, and the contributions from various risk factors. The prognostic implications of LVH on stroke, serious arrhythmias, and sudden cardiac death are reviewed. Finally, we examine the effect of therapy to reduce LVH and the resultant clinical outcomes. (C) 2018 Elsevier Inc. All rights reserved

Kepler-93b: A Terrestrial World Measured to within 120 km, and a Test Case for a New Spitzer Observing Mode

We present the characterization of the Kepler-93 exoplanetary system, based on three years of photometry gathered by the Kepler spacecraft. The duration and cadence of the Kepler observations, in tandem with the brightness of the star, enable unusually precise constraints on both the planet and its host. We conduct an asteroseismic analysis of the Kepler photometry and conclude that the star has an average density of 1.652+/-0.006 g/cm^3. Its mass of 0.911+/-0.033 M_Sun renders it one of the lowest-mass subjects of asteroseismic study. An analysis of the transit signature produced by the planet Kepler-93b, which appears with a period of 4.72673978+/-9.7x10^-7 days, returns a consistent but less precise measurement of the stellar density, 1.72+0.02-0.28 g/cm^3. The agreement of these two values lends credence to the planetary interpretation of the transit signal. The achromatic transit depth, as compared between Kepler and the Spitzer Space Telescope, supports the same conclusion. We observed seven transits of Kepler-93b with Spitzer, three of which we conducted in a new observing mode. The pointing strategy we employed to gather this subset of observations halved our uncertainty on the transit radius ratio R_p/R_star. We find, after folding together the stellar radius measurement of 0.919+/-0.011 R_Sun with the transit depth, a best-fit value for the planetary radius of 1.481+/-0.019 R_Earth. The uncertainty of 120 km on our measurement of the planet's size currently renders it one of the most precisely measured planetary radii outside of the Solar System. Together with the radius, the planetary mass of 3.8+/-1.5 M_Earth corresponds to a rocky density of 6.3+/-2.6 g/cm^3. After applying a prior on the plausible maximum densities of similarly-sized worlds between 1--1.5 R_Earth, we find that Kepler-93b possesses an average density within this group.Comment: 20 pages, 9 figures, accepted for publication in Ap

An asteroseismic membership study of the red giants in three open clusters observed by Kepler: NGC6791, NGC6819, and NGC6811

Studying star clusters offers significant advances in stellar astrophysics due to the combined power of having many stars with essentially the same distance, age, and initial composition. This makes clusters excellent test benches for verification of stellar evolution theory. To fully exploit this potential, it is vital that the star sample is uncontaminated by stars that are not members of the cluster. Techniques for determining cluster membership therefore play a key role in the investigation of clusters. We present results on three clusters in the Kepler field of view based on a newly established technique that uses asteroseismology to identify fore- or background stars in the field, which demonstrates advantages over classical methods such as kinematic and photometry measurements. Four previously identified seismic non-members in NGC6819 are confirmed in this study, and three additional non-members are found -- two in NGC6819 and one in NGC6791. We further highlight which stars are, or might be, affected by blending, which needs to be taken into account when analysing these Kepler data.Comment: 12 pages, 9 figures, 5 tables, accepted by Ap

Current perspectives on left ventricular geometry in systemic hypertension

Hypertension (HTN) is a global health problem and a leading risk factor for cardiovascular disease (CVD) morbidity and mortality. The hemodynamic overload from HTN causes left ventricular (LV) remodeling, which usually manifests as distinct alterations in LV geometry, such as concentric remodeling or concentric and eccentric LV hypertrophy (LVH). In addition to being a common target organ response to HTN, LV geometric abnormalities are well-known independent risk factors for CVD. Because of their prognostic implications and quantifiable nature, changes in LV geometric parameters have commonly been included as an outcome in anti-HTN drug trials. The purpose of this paper is to review the relationship between HTN and LV geometric changes with a focus on (1) diagnostic approach, (2) epidemiology, (3) pathophysiology, (4) prognostic effect and (5) LV response to anti-HTN therapy and its impact on CVD risk reduction

Kepler-68: Three Planets, One With a Density Between That of Earth and Ice Giants

NASA's Kepler Mission has revealed two transiting planets orbiting Kepler-68. Follow-up Doppler measurements have established the mass of the innermost planet and revealed a third jovian-mass planet orbiting beyond the two transiting planets. Kepler-68b, in a 5.4 day orbit has mass 8.3 +/- 2.3 Earth, radius 2.31 +/- 0.07 Earth radii, and a density of 3.32 +/- 0.92 (cgs), giving Kepler-68b a density intermediate between that of the ice giants and Earth. Kepler-68c is Earth-sized with a radius of 0.953 Earth and transits on a 9.6 day orbit; validation of Kepler-68c posed unique challenges. Kepler-68d has an orbital period of 580 +/- 15 days and minimum mass of Msin(i) = 0.947 Jupiter. Power spectra of the Kepler photometry at 1-minute cadence exhibit a rich and strong set of asteroseismic pulsation modes enabling detailed analysis of the stellar interior. Spectroscopy of the star coupled with asteroseismic modeling of the multiple pulsation modes yield precise measurements of stellar properties, notably Teff = 5793 +/- 74 K, M = 1.079 +/- 0.051 Msun, R = 1.243 +/- 0.019 Rsun, and density 0.7903 +/- 0.0054 (cgs), all measured with fractional uncertainties of only a few percent. Models of Kepler-68b suggest it is likely composed of rock and water, or has a H and He envelope to yield its density of about 3 (cgs).Comment: 32 pages, 13 figures, Accepted to Ap

Fundamental Properties of Kepler Planet-Candidate Host Stars using Asteroseismology

We have used asteroseismology to determine fundamental properties for 66 Kepler planet-candidate host stars, with typical uncertainties of 3% and 7% in radius and mass, respectively. The results include new asteroseismic solutions for four host stars with confirmed planets (Kepler-4, Kepler-14, Kepler-23 and Kepler-25) and increase the total number of Kepler host stars with asteroseismic solutions to 77. A comparison with stellar properties in the planet-candidate catalog by Batalha et al. shows that radii for subgiants and giants obtained from spectroscopic follow-up are systematically too low by up to a factor of 1.5, while the properties for unevolved stars are in good agreement. We furthermore apply asteroseismology to confirm that a large majority of cool main-sequence hosts are indeed dwarfs and not misclassified giants. Using the revised stellar properties, we recalculate the radii for 107 planet candidates in our sample, and comment on candidates for which the radii change from a previously giant-planet/brown-dwarf/stellar regime to a sub-Jupiter size, or vice versa. A comparison of stellar densities from asteroseismology with densities derived from transit models in Batalha et al. assuming circular orbits shows significant disagreement for more than half of the sample due to systematics in the modeled impact parameters, or due to planet candidates which may be in eccentric orbits. Finally, we investigate tentative correlations between host-star masses and planet candidate radii, orbital periods, and multiplicity, but caution that these results may be influenced by the small sample size and detection biases.Comment: 19 pages, 10 figures, 4 tables; accepted for publication in ApJ; machine-readable versions of tables 1-3 are available as ancillary files or in the source code; v2: minor changes to match published versio

Stellar Spin-Orbit Misalignment in a Multiplanet System

Stars hosting hot Jupiters are often observed to have high obliquities, whereas stars with multiple co-planar planets have been seen to have low obliquities. This has been interpreted as evidence that hot-Jupiter formation is linked to dynamical disruption, as opposed to planet migration through a protoplanetary disk. We used asteroseismology to measure a large obliquity for Kepler-56, a red giant star hosting two transiting co-planar planets. These observations show that spin-orbit misalignments are not confined to hot-Jupiter systems. Misalignments in a broader class of systems had been predicted as a consequence of torques from wide-orbiting companions, and indeed radial-velocity measurements revealed a third companion in a wide orbit in the Kepler-56 system.Comment: Accepted for publication in Science, published online on October 17 2013; PDF includes main article and supplementary materials (65 pages, 27 figures, 7 tables); v2: small correction to author lis