200 research outputs found
Radial Velocity Observations and Light Curve Noise Modeling Confirm That Kepler-91b is a Giant Planet Orbiting a Giant Star
Kepler-91b is a rare example of a transiting hot Jupiter around a red giant
star, providing the possibility to study the formation and composition of hot
Jupiters under different conditions compared to main-sequence stars. However,
the planetary nature of Kepler-91b, which was confirmed using phase-curve
variations by Lillo-Box et al., was recently called into question based on a
re-analysis of Kepler data. We have obtained ground-based radial velocity
observations from the Hobby-Eberly Telescope and unambiguously confirm the
planetary nature of Kepler-91b by simultaneously modeling the Kepler and radial
velocity data. The star exhibits temporally correlated noise due to stellar
granulation which we model as a Gaussian Process. We hypothesize that it is
this noise component that led previous studies to suspect Kepler-91b to be a
false positive. Our work confirms the conclusions presented by Lillo-Box et al.
that Kepler-91b is a 0.73+/-0.13 Mjup planet orbiting a red giant star.Comment: Published in Ap
Coherent optical phase transfer over a 32-km fiber with 1-s instability at
The phase coherence of an ultrastable optical frequency reference is fully
maintained over actively stabilized fiber networks of lengths exceeding 30 km.
For a 7-km link installed in an urban environment, the transfer instability is
at 1-s. The excess phase noise of 0.15 rad, integrated from
8 mHz to 25 MHz, yields a total timing jitter of 0.085 fs. A 32-km link
achieves similar performance. Using frequency combs at each end of the
coherent-transfer fiber link, a heterodyne beat between two independent
ultrastable lasers, separated by 3.5 km and 163 THz, achieves a 1-Hz linewidth.Comment: 4 pages, 4 figure
Identifying and troubleshooting low-frequency artifacts mimicking atrial flutter caused by deep brain stimulator
Electromagnetic interference from deep brain stimulators (DBS) is known to cause high-frequency artifact on some forms of cardiac telemetry.1 Here, we (1) present a unique case in which a DBS caused a low-frequency artifact mimicking typical atrial flutter leading to referral to electrophysiology; (2) demonstrate a method to confirm this; and (3) provide recommendations of how to minimize artifact and work around this interaction in future rhythm monitoring attempts
Terminal spreading depolarization and electrical silence in death of human cerebral cortex
Objective: Restoring the circulation is the primary goal in emergency
treatment of cerebral ischemia. However, better understanding of how the brain
responds to energy depletion could help predict the time available for
resuscitation until irreversible damage and advance development of
interventions that prolong this span. Experimentally, injury to central
neurons begins only with anoxic depolarization. This potentially reversible,
spreading wave typically starts 2 to 5 minutes after the onset of severe
ischemia, marking the onset of a toxic intraneuronal change that eventually
results in irreversible injury. Methods: To investigate this in the human
brain, we performed recordings with either subdural electrode strips (n = 4)
or intraparenchymal electrode arrays (n = 5) in patients with devastating
brain injury that resulted in activation of a Do Not Resuscitate–Comfort Care
order followed by terminal extubation. Results: Withdrawal of life‐sustaining
therapies produced a decline in brain tissue partial pressure of oxygen
(ptiO2) and circulatory arrest. Silencing of spontaneous electrical activity
developed simultaneously across regional electrode arrays in 8 patients. This
silencing, termed “nonspreading depression,” developed during the steep
falling phase of ptiO2 (intraparenchymal sensor, n = 6) at 11 (interquartile
range [IQR] = 7–14) mmHg. Terminal spreading depolarizations started to
propagate between electrodes 3.9 (IQR = 2.6–6.3) minutes after onset of the
final drop in perfusion and 13 to 266 seconds after nonspreading depression.
In 1 patient, terminal spreading depolarization induced the initial
electrocerebral silence in a spreading depression pattern; circulatory arrest
developed thereafter. Interpretation: These results provide fundamental
insight into the neurobiology of dying and have important implications for
survivable cerebral ischemic insults. Ann Neurol 2018;83:295–31
The SPLASH Survey: Kinematics of Andromeda's Inner Spheroid
The combination of large size, high stellar density, high metallicity, and
Sersic surface brightness profile of the spheroidal component of the Andromeda
galaxy (M31) within R_proj ~ 20 kpc suggest that it is unlike any subcomponent
of the Milky Way. In this work we capitalize on our proximity to and external
view of M31 to probe the kinematical properties of this "inner spheroid." We
employ a Markov chain Monte Carlo (MCMC) analysis of resolved stellar
kinematics from Keck/DEIMOS spectra of 5651 red giant branch stars to
disentangle M31's inner spheroid from its stellar disk. We measure the mean
velocity and dispersion of the spheroid in each of five spatial bins after
accounting for a locally cold stellar disk as well as the Giant Southern Stream
and associated tidal debris. For the first time, we detect significant spheroid
rotation (v_rot ~ 50 km/s) beyond R_proj ~ 5 kpc. The velocity dispersion
decreases from about 140 km/s at R_proj = 7 kpc to 120 km/s at R_proj = 14 kpc,
consistent to 2 sigma with existing measurements and models. We calculate the
probability that a given star is a member of the spheroid and find that the
spheroid has a significant presence throughout the spatial extent of our
sample. Lastly, we show that the flattening of the spheroid is due to velocity
anisotropy in addition to rotation. Though this suggests that the inner
spheroid of M31 more closely resembles an elliptical galaxy than a typical
spiral galaxy bulge, it should be cautioned that our measurements are much
farther out (2 - 14 r_eff) than for the comparison samples.Comment: Accepted for publication in Ap
Prenatal exome sequencing in anomalous fetuses: new opportunities and challenges
We investigated the diagnostic and clinical performance of exome sequencing (ES) in fetuses with sonographic abnormalities with normal karyotype, microarray and, in some cases, normal gene specific sequencing
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