719 research outputs found
Shutters and slats for the integral sunshade of an optical reception antenna
Optical reception antennas used at a small Sun-Earth-probe angle (small solar elongation E) require sunshading to prevent intolerable scattering of light from the surface of the primary mirror. An integral sunshade consisting of hexagonal tubes aligned with the segmentation of a large mirror was proposed for use down to E = 12 degrees. For smaller angles, asterisk-shaped vanes inserted into the length of the hexagonal tubes would allow operation down to about 6 degrees with a fixed obscuration of 3.6 percent. Two alternative methods are investigated to extend the usefulness of the integral sunshade to smaller angles by adding either variable-area shutters to block the tube corners that admit off-axis sunlight or by inserting slats (partial vanes) down the full length of some tubes. Slats are effective for most operations down to 6 degrees, and obscure only 1.2 percent. For E between 10.75 and 12 degrees, shutters cause even less obscuration
Discovery of the Transiting Planet Kepler-5B
We present 44 days of high duty cycle, ultra precise photometry of the 13th magnitude star Kepler-5 (KIC 8191672, T(eff) = 6300 K, log g = 4.1), which exhibits periodic transits with a depth of 0.7%. Detailed modeling of the transit is consistent with a planetary companion with an orbital period of 3.548460 +/- 0.000032 days and a radius of 1.431(-0.052)(+0.041) R(J). Follow-up radial velocity measurements with the Keck HIRES spectrograph on nine separate nights demonstrate that the planet is more than twice as massive as Jupiter with a mass of 2.114(-0.059)(+0.056) M(J) and a mean density of 0.894 +/- 0.079 g cm(-3).NASA's Science Mission DirectorateAstronom
Sex Differences in the Management and Outcomes of Heart Failure with Preserved Ejection Fraction in Patients Presenting to the Emergency Department with Acute Heart Failure
Background
Heart failure (HF) with preserved ejection fraction (HFpEF) is more common in women than in men; data characterizing sex differences in the management and outcomes of HFpEF patients presenting to the emergency department (ED) are limited.
Methods and Results
Using Acute Decompensated Heart Failure National Registry Emergency Module data linked to Medicare claims, we conducted a retrospective analysis of acute HF patients in the ED, identifying HFpEF (ejection fraction [EF] ≥40%) patients and stratifying by sex to compare baseline characteristics, ED therapies, hospital length of stay (LOS), in-hospital mortality, and post-discharge outcomes. Of 4161 HFpEF patients, 2808 (67%) were women, who were more likely to be older and hypertensive, but less likely to be diabetic or smokers (all P 140 mm Hg (62.5% vs 56.4%; P = .0001) and higher EF. There were no sex differences in ED therapies, adjusted 30- and 180-day all-cause mortality, in-hospital mortality, or 30- and 180-day readmissions. After adjustment, women had longer LOS (0.40 days, 95% confidence interval [CI] 0.10–0.70; P = .008).
Conclusions
Women with HFpEF presenting to the ED were more likely to have elevated systolic blood pressure, but overall ED management strategies were similar to those in men. We observed adjusted differences in hospital LOS, but no differences in 30- and 180-day outcomes
Relativistic separable dual-space Gaussian Pseudopotentials from H to Rn
We generalize the concept of separable dual-space Gaussian pseudopotentials
to the relativistic case. This allows us to construct this type of
pseudopotential for the whole periodic table and we present a complete table of
pseudopotential parameters for all the elements from H to Rn. The relativistic
version of this pseudopotential retains all the advantages of its
nonrelativistic version. It is separable by construction, it is optimal for
integration on a real space grid, it is highly accurate and due to its analytic
form it can be specified by a very small number of parameters. The accuracy of
the pseudopotential is illustrated by an extensive series of molecular
calculations
Structure and Dynamics of the Sun's Open Magnetic Field
The solar magnetic field is the primary agent that drives solar activity and
couples the Sun to the Heliosphere. Although the details of this coupling
depend on the quantitative properties of the field, many important aspects of
the corona - solar wind connection can be understood by considering only the
general topological properties of those regions on the Sun where the field
extends from the photosphere out to interplanetary space, the so-called open
field regions that are usually observed as coronal holes. From the simple
assumptions that underlie the standard quasi-steady corona-wind theoretical
models, and that are likely to hold for the Sun, as well, we derive two
conjectures on the possible structure and dynamics of coronal holes: (1)
Coronal holes are unique in that every unipolar region on the photosphere can
contain at most one coronal hole. (2) Coronal holes of nested polarity regions
must themselves be nested. Magnetic reconnection plays the central role in
enforcing these constraints on the field topology. From these conjectures we
derive additional properties for the topology of open field regions, and
propose several observational predictions for both the slowly varying and
transient corona/solar wind.Comment: 26 pages, 6 figure
ISS Space Plasma Laboratory: An ISS instrument package for investigating the opening/closing of solar and heliospheric magnetic fields
Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/140428/1/6.2014-1422.pd
Hospitalizations in patients with atrial fibrillation:an analysis from ROCKET AF
AIMS: The high costs associated with treatment for atrial fibrillation (AF) are primarily due to hospital care, but there are limited data to understand the reasons for and predictors of hospitalization in patients with AF. METHODS AND RESULTS: The ROCKET AF trial compared rivaroxaban with warfarin for stroke prophylaxis in AF. We described the frequency of and reasons for hospitalization during study follow-up and utilized Cox proportional hazards models to assess for baseline characteristics associated with all-cause hospitalization. Of 14 171 patients, 14% were hospitalized at least once. Of 2614 total hospitalizations, 41% were cardiovascular including 4% for AF; of the remaining, 12% were for bleeding. Compared with patients not hospitalized, hospitalized patients were older (74 vs. 72 years), and more frequently had diabetes (46 vs. 39%), prior MI (23 vs. 16%), and paroxysmal AF (19 vs. 17%), but less frequently had prior transient ischaemic attack/stroke (49 vs. 56%). After multivariable adjustment, lung disease [hazard ratio (HR) 1.46, 95% confidence interval (CI) 1.29–1.66], diabetes [1.22, (1.11–1.34)], prior MI [1.27, (1.13–1.42)], and renal dysfunction [HR 1.07 per 5 unit GFR < 65 mL/min, (1.04–1.10)] were associated with increased hospitalization risk. Treatment assignment was not associated with differential rates of hospitalization. CONCLUSION: Nearly 1 in 7 of the moderate-to-high-risk patients with AF enrolled in this trial was hospitalized within 2 years, and both AF and bleeding were rare causes of hospitalization. Further research is needed to determine whether care pathways directed at comorbid conditions among AF patients could reduce the need for and costs associated with hospitalization
Kepler-22b: A 2.4 Earth-radius Planet in the Habitable Zone of a Sun-like Star
A search of the time-series photometry from NASA's Kepler spacecraft reveals
a transiting planet candidate orbiting the 11th magnitude G5 dwarf KIC 10593626
with a period of 290 days. The characteristics of the host star are well
constrained by high-resolution spectroscopy combined with an asteroseismic
analysis of the Kepler photometry, leading to an estimated mass and radius of
0.970 +/- 0.060 MSun and 0.979 +/- 0.020 RSun. The depth of 492 +/- 10ppm for
the three observed transits yields a radius of 2.38 +/- 0.13 REarth for the
planet. The system passes a battery of tests for false positives, including
reconnaissance spectroscopy, high-resolution imaging, and centroid motion. A
full BLENDER analysis provides further validation of the planet interpretation
by showing that contamination of the target by an eclipsing system would rarely
mimic the observed shape of the transits. The final validation of the planet is
provided by 16 radial velocities obtained with HIRES on Keck 1 over a one year
span. Although the velocities do not lead to a reliable orbit and mass
determination, they are able to constrain the mass to a 3{\sigma} upper limit
of 124 MEarth, safely in the regime of planetary masses, thus earning the
designation Kepler-22b. The radiative equilibrium temperature is 262K for a
planet in Kepler-22b's orbit. Although there is no evidence that Kepler-22b is
a rocky planet, it is the first confirmed planet with a measured radius to
orbit in the Habitable Zone of any star other than the Sun.Comment: Accepted to Ap
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