1,450 research outputs found
Augmentation of the IUE Ultraviolet Spectral Atlas
Observations of normal stars in order to fulfill the following goals (1) to provide a stellar library to support astronomical research by the scientific community; and (2) to obtain a sufficient sample of stars to guard against variability and peculiarity, and to allow a finite range of temperature, gravity, and metallicity in a given spectral type-luminosity class combination, are reported
Probing gravitational non-minimal coupling with dark energy surveys
We investigate observational constraints on a specific one-parameter
extension to the minimal quintessence model, where the quintessence field
acquires a quadratic coupling to the scalar curvature through a coupling
constant . The value of is highly suppressed in typical tracker
models if the late-time cosmic acceleration is driven at some field values near
the Planck scale. We test in a second class of models in which the field
value today becomes a free model parameter. We use the combined data from
type-Ia supernovae, cosmic microwave background, baryon acoustic oscillations
and matter power spectrum, to weak lensing measurements and find a best-fit
value where is excluded outside the 95 per cent
confidence region. The effective gravitational constant subject
to the hint of a non-zero is constrained to at the same confidence level on cosmological scales, and can be narrowed
down to when combining with Solar
System tests.Comment: Context extended, figures and references added, title changed to
match with accepted version for publicatio
"Teleparallel" Dark Energy
Using the "teleparallel" equivalent of General Relativity as the
gravitational sector, which is based on torsion instead of curvature, we add a
canonical scalar field, allowing for a nonminimal coupling with gravity.
Although the minimal case is completely equivalent to standard quintessence,
the nonminimal scenario has a richer structure, exhibiting quintessence-like or
phantom-like behavior, or experiencing the phantom-divide crossing. The richer
structure is manifested in the absence of a conformal transformation to an
equivalent minimally-coupled model.Comment: 5 pages, 1 figure, Version published in PLB704 (2011) 384-38
Deferoxamine retinopathy: spectral domain-optical coherence tomography findings
Al-Djamiʿ li Ibn al-BaïtharNumérisation effectuée à partir d'un document de substitution
Shape restricted regression with random Bernstein polynomials
Shape restricted regressions, including isotonic regression and concave
regression as special cases, are studied using priors on Bernstein polynomials
and Markov chain Monte Carlo methods. These priors have large supports, select
only smooth functions, can easily incorporate geometric information into the
prior, and can be generated without computational difficulty. Algorithms
generating priors and posteriors are proposed, and simulation studies are
conducted to illustrate the performance of this approach. Comparisons with the
density-regression method of Dette et al. (2006) are included.Comment: Published at http://dx.doi.org/10.1214/074921707000000157 in the IMS
Lecture Notes Monograph Series
(http://www.imstat.org/publications/lecnotes.htm) by the Institute of
Mathematical Statistics (http://www.imstat.org
Deferoxamine retinopathy: spectral domain-optical coherence tomography findings
BACKGROUND: To describe the spectral domain optical coherence tomography (SD-OCT) findings of a patient who developed pigmentary retinopathy following high-dose deferoxamine administration. CASE PRESENTATION: A 34-year-old man with thalassemia major complained of nyctalopia and decreased vision following high-dose intravenous deferoxamine to treat systemic iron overload. Fundus examination revealed multiple discrete hypo-pigmented lesions at the posterior pole and mid-peripheral retina. Recovery was partial following cessation of desferrioxamine six weeks later. A follow-up SD-OCT showed multiple accumulated hyper-reflective deposits primarily in the choroid, retina pigment epithelium (RPE), and inner segment and outer segment (IS/OS) junction. CONCLUSION: Deferoxamine retinopathy primarily targets the RPE–Bruch membrane–photoreceptor complex, extending from the peri-fovea to the peripheral retina with foveola sparing. An SD-OCT examination can serve as a simple, noninvasive tool for early detection and long-term follow-up
Development of the NTP Pool Project in Taiwan
Among the standard time reporting systems, the Network Time Protocol (NTP) provides an easy and accurate way for the accessing the Universal time. The NTP is taking the benefit of the pervasiveness of the computer network during
the recent information-oriented modern world. The NTP Pool Project is the project to provide a distributed framework of the NTP servers. As the ever-increasing amounts of the requests of the standard time, the number of the NTP servers provided by the NTP Pool Project will be extended correspondingly. This paper will provide the detailed introduction on the framework of the NTP Pool Project, the development of the NTP Pool Project in Taiwan at the present time, and the followed by the suggestions of the implementation of the NTP pool project
Profiling time course expression of virus genes---an illustration of Bayesian inference under shape restrictions
There have been several studies of the genome-wide temporal transcriptional
program of viruses, based on microarray experiments, which are generally useful
in the construction of gene regulation network. It seems that biological
interpretations in these studies are directly based on the normalized data and
some crude statistics, which provide rough estimates of limited features of the
profile and may incur biases. This paper introduces a hierarchical Bayesian
shape restricted regression method for making inference on the time course
expression of virus genes. Estimates of many salient features of the expression
profile like onset time, inflection point, maximum value, time to maximum
value, area under curve, etc. can be obtained immediately by this method.
Applying this method to a baculovirus microarray time course expression data
set, we indicate that many biological questions can be formulated
quantitatively and we are able to offer insights into the baculovirus biology.Comment: Published in at http://dx.doi.org/10.1214/09-AOAS258 the Annals of
Applied Statistics (http://www.imstat.org/aoas/) by the Institute of
Mathematical Statistics (http://www.imstat.org
In vitro propagation and analysis of secondary metabolites in Glossogyne tenuifolia (Hsiang-Ju) - a medicinal plant native to Taiwan
Far-Ultraviolet Absorption Lines in the Remnant of SN 1006
We have obtained a far-ultraviolet spectrum (1150-1600 Å) of a hot subdwarf star behind the remnant of supernova 1006 with the Faint Object Spectrograph (FOS) on the Hubble Space Telescope. The high-quality spectrum is used to test previous identifications of the strong absorption features discovered with the International Ultraviolet Explorer. These features have FWHM = 4000 (±300) km s-1 and are not at the rest wavelengths of known interstellar lines, as opposed to the broader (~8000 km s-1 FWHM) Fe II lines from the remnant centered at 0 km s-1 in near-UV FOS spectra. We confirm that the broad absorption features are principally due to redshifted Si II, Si III, and Si IV lines, which are centered at a radial velocity of 5100 (±200) km s-1.
The Si II λ1260.4 profile is asymmetric, with a nearly flat core and sharp red wing, unlike the Si II λ1526.7 and Si IV λλ1393.8, 1402.8 profiles. One possible explanation is additional absorption from another species. Previous work has suggested that S II λλ1250.6, 1253.8, 1259.5 at a radial velocity of ~6000 km s-1 is responsible, but this would require a sulfur-to-silicon abundance ratio that is at least a factor of 10 higher than expected. Another possible explanation is that the Si II and Si IV profiles are intrinsically different, but this does not explain the symmetric (albeit weaker) Si II λ1526.7 profile
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