3,428 research outputs found
The Solar-Type Contact Binary BX Pegasi Revisited
We present the results of new CCD photometry for the contact binary BX Peg,
made during three successive months beginning on September 2008. As do
historical light curves, our observations display an O'Connell effect and the
November data by themselves indicate clear evidence for very short-time
brightness disturbance. For these variations, model spots are applied
separately to the two data set of Group I (Sep.--Oct.) and Group II (Nov.). The
former is described by a single cool spot on the secondary photosphere and the
latter by a two-spot model with a cool spot on the cool star and a hot one on
either star. These are generalized manifestations of the magnetic activity of
the binary system. Twenty light-curve timings calculated from Wilson-Devinney
code were used for a period study, together with all other minimum epochs. The
complex period changes of BX Peg can be sorted into a secular period decrease
caused dominantly by angular momentum loss due to magnetic stellar wind
braking, a light-travel-time (LTT) effect due to the orbit of a low-mass third
companion, and a previously unknown short-term oscillation. This last period
modulation could be produced either by a second LTT orbit with a period of
about 16 yr due to the existence of a fourth body or by the effect of magnetic
activity with a cycle length of about 12 yr.Comment: 23 pages, including 6 figures and 8 tables, accepted for publication
in PAS
Physical Properties of the Transiting Planetary System TrES-3
We present four new transits of the planetary system TrES-3 observed between
2009 May and 2010 June. Among these, the third transit by itself indicates
possible evidence for brightness disturbance, which might be the result of the
planet blocking a cool starspot on the stellar surface. A total of 109 transit
times, including our measurements, were used to determine the improved
ephemeris with a transit epoch of 2454185.9109440.000072 HJED and an
orbital period of 1.306187000.00000015 d. We analyzed the transit light
curves using the JKTEBOP code and adopting the quadratic limb-darkening law. In
order to derive the physical properties of the TrES-3 system, the transit
parameters are combined with the empirical relations from eclipsing binary
stars and stellar evolutionary models. The stellar mass and radius obtained
from a calibration using , log and [Fe/H] are consistent
with those from the isochrone analysis. We found that the exoplanet TrES-3b has
a mass of 1.930.07 M, a radius of 1.300.04 R,
a surface gravity of log =3.450.02, a density of 0.820.06
, and an equilibrium temperature of 164123 K. The results
are in good agreement with theoretical models for gas giant planets.Comment: 15 pages, including 4 figures and 4 tables, accepted for publication
in PAS
Analyzing Herd Behavior in Global Stock Markets: An Intercontinental Comparison
Herd behavior is an important economic phenomenon, especially in the context
of the recent financial crises. In this paper, herd behavior in global stock
markets is investigated with a focus on intercontinental comparison. Since most
existing herd behavior indices do not provide a comparative method, we propose
a new herd behavior index and demonstrate its desirable properties through
simple theoretical models. As for empirical analysis, we use global stock
market data from Morgan Stanley Capital International to study herd behavior
especially during periods of financial crises in detail
Deep Learning-based Synthetic High-Resolution In-Depth Imaging Using an Attachable Dual-element Endoscopic Ultrasound Probe
Endoscopic ultrasound (EUS) imaging has a trade-off between resolution and
penetration depth. By considering the in-vivo characteristics of human organs,
it is necessary to provide clinicians with appropriate hardware specifications
for precise diagnosis. Recently, super-resolution (SR) ultrasound imaging
studies, including the SR task in deep learning fields, have been reported for
enhancing ultrasound images. However, most of those studies did not consider
ultrasound imaging natures, but rather they were conventional SR techniques
based on downsampling of ultrasound images. In this study, we propose a novel
deep learning-based high-resolution in-depth imaging probe capable of offering
low- and high-frequency ultrasound image pairs. We developed an attachable
dual-element EUS probe with customized low- and high-frequency ultrasound
transducers under small hardware constraints. We also designed a special geared
structure to enable the same image plane. The proposed system was evaluated
with a wire phantom and a tissue-mimicking phantom. After the evaluation, 442
ultrasound image pairs from the tissue-mimicking phantom were acquired. We then
applied several deep learning models to obtain synthetic high-resolution
in-depth images, thus demonstrating the feasibility of our approach for
clinical unmet needs. Furthermore, we quantitatively and qualitatively analyzed
the results to find a suitable deep-learning model for our task. The obtained
results demonstrate that our proposed dual-element EUS probe with an
image-to-image translation network has the potential to provide synthetic
high-frequency ultrasound images deep inside tissues.Comment: 10 pages, 9 figure
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