2,173 research outputs found
Demonstration of nanoimprinted hyperlens array for high-throughput sub-diffraction imaging
11124Nsciescopu
Optical observations of NEA 162173 (1999 JU3) during the 2011-2012 apparition
Near-Earth asteroid 162173 (1999 JU3) is a potential target of two asteroid
sample return missions, not only because of its accessibility but also because
of the first C-type asteroid for exploration missions. The lightcurve-related
physical properties of this object were investigated during the 2011-2012
apparition. We aim to confirm the physical parameters useful for JAXA's
Hayabusa 2 mission, such as rotational period, absolute magnitude, and phase
function. Our data complement previous studies that did not cover low phase
angles. With optical imagers and 1-2 m class telescopes, we acquired the
photometric data at different phase angles. We independently derived the
rotational lightcurve and the phase curve of the asteroid. We have analyzed the
lightcurve of 162173 (1999 JU3), and derived a synodic rotational period of
7.625 +/- 0.003 h, the axis ratio a/b = 1.12. The absolute magnitude H_R =
18.69 +/- 0.07 mag and the phase slope of G = -0.09 +/- 0.03 were also obtained
based on the observations made during the 2011-2012 apparition.Comment: 4 pages, 3 figure
The Taiwanese-American Occultation Survey: The Multi-Telescope Robotic Observatory
The Taiwanese-American Occultation Survey (TAOS) operates four fully
automatic telescopes to search for occultations of stars by Kuiper Belt
Objects. It is a versatile facility that is also useful for the study of
initial optical GRB afterglows. This paper provides a detailed description of
the TAOS multi-telescope system, control software, and high-speed imaging.Comment: 11 pages, 11 figure
The TAOS Project: Statistical Analysis of Multi-Telescope Time Series Data
The Taiwanese-American Occultation Survey (TAOS) monitors fields of up to
~1000 stars at 5 Hz simultaneously with four small telescopes to detect
occultation events from small (~1 km) Kuiper Belt Objects (KBOs). The survey
presents a number of challenges, in particular the fact that the occultation
events we are searching for are extremely rare and are typically manifested as
slight flux drops for only one or two consecutive time series measurements. We
have developed a statistical analysis technique to search the multi-telescope
data set for simultaneous flux drops which provides a robust false positive
rejection and calculation of event significance. In this paper, we describe in
detail this statistical technique and its application to the TAOS data set.Comment: 15 pages, 14 figures. Submitted to PAS
On the L_p-solvability of higher order parabolic and elliptic systems with BMO coefficients
We prove the solvability in Sobolev spaces for both divergence and
non-divergence form higher order parabolic and elliptic systems in the whole
space, on a half space, and on a bounded domain. The leading coefficients are
assumed to be merely measurable in the time variable and have small mean
oscillations with respect to the spatial variables in small balls or cylinders.
For the proof, we develop a set of new techniques to produce mean oscillation
estimates for systems on a half space.Comment: 44 pages, introduction revised, references expanded. To appear in
Arch. Rational Mech. Ana
Occupational noise exposure is associated with hypertension in China: Results from project ELEFANT
OBJECTIVES:
We investigated the association between occupational noise exposure and the risk of elevated blood pressure and hypertension by stage in young adults.
METHODS:
We utilized 124,286 young adults (18-40 years) from the Project ELEFANT study. We categorized occupational noise exposure as high (75 dBA noise exposure for more than 4 hours per day) or low, and measured blood pressure (mmHg) and categorized participants by hypertension stage (normal, elevated, Stage 1, Stage 2). We applied adjusted logistic regression models to identify associations with hypertension risk, and we further examined the noise-BMI, noise-gender, and noise-residence interactions on hypertension risk in separate models.
RESULTS:
High occupational noise exposure was associated with increases in blood pressure among participants with elevated blood pressure (Estimate = 0.23, 95% CI: 1.09, 1.46, p = 0.0009), in Stage 1 hypertension (Estimate = 0.15, 95% CI: 1.06, 1.25, p = 0.0008), and in Stage 2 hypertension (Estimate = 0.41 95% CI: 1.31, 1.73, p<0.0001). Likewise, noise exposure-BMI interaction was consistently positively associated with increases in blood pressure in participants with elevated blood pressure (Estimate = 0.71, 95% CI: 1.55, 2.69, p<0.0001), in Stage 1 hypertension (Estimate = 0.78, 95% CI: 1.82, 2.61, p<0.0001), and in Stage 2 hypertension (Estimate = 2.06, 95% CI: 5.64, 10.81, p<0.0001). The noise exposure-male interaction showed higher risk for hypertension compared to the noise exposure-female interaction in participants with elevated blood pressure (Estimate = 1.24, 95% CI: 2.56, 4.71, p<0.0001), Stage 1 (Estimate = 1.67, 95% CI: 4.34, 6.42, p<0.0001) and Stage 2 hypertension (Estimate = 1.70, 95% CI: 3.86, 7.77, p<0.0001). Finally, we found that noise exposure-urban interaction was consistently associated with an increase in blood pressure in elevated blood pressure (Estimate = 0.32, 95% CI: 1.19, 1.62, p<0.0001) and in Stage 2 hypertension (Estimate = 0.44, 95% CI: 1.31, 1.80, p<0.0001)
The Taiwanese-American Occultation Survey Project Stellar Variability. II. Detection of 15 Variable Stars
The Taiwanese-American Occultation Survey (TAOS) project has collected more than a billion photometric measurements since 2005 January. These sky survey data—covering timescales from a fraction of a second to a few hundred days—are a useful source to study stellar variability. A total of 167 star fields, mostly along the ecliptic plane, have been selected for photometric monitoring with the TAOS telescopes. This paper presents our initial analysis of a search for periodic variable stars from the time-series TAOS data on one particular TAOS field, No. 151 (R.A. = 17^(h)30^(m)6^(s).7, decl. = 27°17'30", J2000), which had been observed over 47 epochs in 2005. A total of 81 candidate variables are identified in the 3 deg^2 field, with magnitudes in the range 8 < R < 16. On the basis of the periodicity and shape of the light curves, 29 variables, 15 of which were previously unknown, are classified as RR Lyrae, Cepheid, δ Scuti, SX Phonencis, semi-regular, and eclipsing binaries
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