3,516 research outputs found
PHASES Differential Astrometry and the Mutual Inclination of the V819 Herculis Triple Star System
V819 Herculis is a well-studied triple star system consisting of a ``wide''
pair with 5.5 year period, one component of which is a 2.2-day period eclipsing
single-line spectroscopic binary. Differential astrometry measurements from the
Palomar High-precision Astrometric Search for Exoplanet Systems (PHASES) are
presented and used to determine a relative inclination between the short- and
long-period orbits of 23.6 +- 4.9 degrees. This represents only the sixth
unambiguous determination of the mutual inclination of orbits in a hierarchical
triple system. This result is combined with those for the other five systems
for analysis of the observed distribution of mutual inclinations in nearby
triple systems. It is found that this distribution is different than that which
one would expect from random orientations with statistical significance at the
94% level; implications for studying the spatial distribution of angular
momentum in star forming regions is discussed.Comment: Accepted for publication in Astronomy and Astrophysics; changed
direction of axis for figure 2
Tomographic reconstruction of quantum states in N spatial dimensions
Most quantum tomographic methods can only be used for one-dimensional
problems. We show how to infer the quantum state of a non-relativistic
N-dimensional harmonic oscillator system by simple inverse Radon transforms.
The procedure is equally applicable to finding the joint quantum state of
several distinguishable particles in different harmonic oscillator potentials.
A requirement of the procedure is that the angular frequencies of the N
harmonic potentials are incommensurable. We discuss what kind of information
can be found if the requirement of incommensurability is not fulfilled and also
under what conditions the state can be reconstructed from finite time
measurements. As a further example of quantum state reconstruction in N
dimensions we consider the two related cases of an N-dimensional free particle
with periodic boundary conditions and a particle in an N-dimensional box, where
we find a similar condition of incommensurability and finite recurrence time
for the one-dimensional system.Comment: 8 pages, 1 figur
Full characterization of Gaussian bipartite entangled states by a single homodyne detector
We present the full experimental reconstruction of Gaussian entangled states
generated by a type--II optical parametric oscillator (OPO) below threshold.
Our scheme provides the entire covariance matrix using a single homodyne
detector and allows for the complete characterization of bipartite Gaussian
states, including the evaluation of purity, entanglement and nonclassical
photon correlations, without a priori assumptions on the state under
investigation. Our results show that single homodyne schemes are convenient and
robust setups for the full characterization of OPO signals and represent a tool
for quantum technology based on continuous variable entanglement.Comment: 4 pages, 3 figures, slightly longer version of published PR
Radial Structure in the TW Hya Circumstellar Disk
We present new near-infrared interferometric data from the CHARA array and the Keck Interferometer on the circumstellar disk of the young star, TW Hya, a proposed "transition disk." We use these data, as well as previously published, spatially resolved data at 10 μm and 7 mm, to constrain disk models based on a standard flared disk structure. We find that we can match the interferometry data sets and the overall spectral energy distribution with a three-component model, which combines elements at spatial scales proposed by previous studies: optically thin, emission nearest the star, an inner optically thick ring of emission at roughly 0.5 AU followed by an opacity gap and, finally, an outer optically thick disk starting at ~4 AU. The model demonstrates that the constraints imposed by the spatially resolved data can be met with a physically plausible disk but this requires a disk containing not only an inner gap in the optically thick disk as previously suggested, but also a gap between the inner and outer optically thick disks. Our model is consistent with the suggestion by Calvet et al. of a planet with an orbital radius of a few AU. We discuss the implications of an opacity gap within the optically thick disk
Protein Delivery of an Artificial Transcription Factor Restores Widespread Ube3a Expression in an Angelman Syndrome Mouse Brain.
Angelman syndrome (AS) is a neurological genetic disorder caused by loss of expression of the maternal copy of UBE3A in the brain. Due to brain-specific genetic imprinting at this locus, the paternal UBE3A is silenced by a long antisense transcript. Inhibition of the antisense transcript could lead to unsilencing of paternal UBE3A, thus providing a therapeutic approach for AS. However, widespread delivery of gene regulators to the brain remains challenging. Here, we report an engineered zinc finger-based artificial transcription factor (ATF) that, when injected i.p. or s.c., crossed the blood-brain barrier and increased Ube3a expression in the brain of an adult mouse model of AS. The factor displayed widespread distribution throughout the brain. Immunohistochemistry of both the hippocampus and cerebellum revealed an increase in Ube3a upon treatment. An ATF containing an alternative DNA-binding domain did not activate Ube3a. We believe this to be the first report of an injectable engineered zinc finger protein that can cause widespread activation of an endogenous gene in the brain. These observations have important implications for the study and treatment of AS and other neurological disorders
First visual orbit for the prototypical colliding-wind binary WR 140
Wolf-Rayet stars represent one of the final stages of massive stellar
evolution. Relatively little is known about this short-lived phase and we
currently lack reliable mass, distance, and binarity determinations for a
representative sample. Here we report the first visual orbit for WR
140(=HD193793), a WC7+O5 binary system known for its periodic dust production
episodes triggered by intense colliding winds near periastron passage. The IOTA
and CHARA interferometers resolved the pair of stars in each year from
2003--2009, covering most of the highly-eccentric, 7.9 year orbit. Combining
our results with the recent improved double-line spectroscopic orbit of Fahed
et al. (2011), we find the WR 140 system is located at a distance of 1.67 +/-
0.03 kpc, composed of a WR star with M_WR = 14.9 +/- 0.5 Msun and an O star
with M_O = 35.9 +/- 1.3 Msun. Our precision orbit yields key parameters with
uncertainties times 6 smaller than previous work and paves the way for detailed
modeling of the system. Our newly measured flux ratios at the near-infrared H
and Ks bands allow an SED decomposition and analysis of the component
evolutionary states.Comment: Complete OIFITS dataset included via Data Conservancy Projec
Fad Diets: Professional Development Needs Among Nutrition Agents in Select Southern States
Because FCS agents teach communities about dietary guidelines, it is important that they are aware of the latest nutrition research. This study assessed FCS agents’ knowledge of popular fad diets (low-carbohydrate, intermittent fasting, detoxes and cleanses) and their potential adverse effects, and its relationship among location, certifications, years of experience, professional association memberships, and education. Agents in Louisiana, Texas, Arkansas, and Mississippi were emailed a survey. RDN, DTR, and CHES certifications had significant associations (p = 0.03) with knowledge of adverse effects of fad diets. Agents who hold these credentials may have more knowledge about adverse effects of fad diets
Imaging the Algol Triple System in H Band with the CHARA Interferometer
Algol (Beta Per) is an extensively studied hierarchical triple system whose
inner pair is a prototype semi-detached binary with mass transfer occurring
from the sub-giant secondary to the main-sequence primary. We present here the
results of our Algol observations made between 2006 and 2010 at the CHARA
interferometer with the Michigan Infrared Combiner in the H band. The use of
four telescopes with long baselines allows us to achieve better than 0.5 mas
resolution and to unambiguously resolve the three stars. The inner and outer
orbital elements, as well as the angular sizes and mass ratios for the three
components are determined independently from previous studies. We report a
significantly improved orbit for the inner stellar pair with the consequence of
a 15% change in the primary mass compared to previous studies. We also
determine the mutual inclination of the orbits to be much closer to
perpendicularity than previously established. State-of-the-art image
reconstruction algorithms are used to image the full triple system. In
particular an image sequence of 55 distinct phases of the inner pair orbit is
reconstructed, clearly showing the Roche-lobe-filling secondary revolving
around the primary, with several epochs corresponding to the primary and
secondary eclipses
On Alternative Supermatrix Reduction
We consider a nonstandard odd reduction of supermatrices (as compared with
the standard even one) which arises in connection with possible extension of
manifold structure group reductions. The study was initiated by consideration
of the generalized noninvertible superconformal-like transformations. The
features of even- and odd-reduced supermatrices are investigated on a par. They
can be unified into some kind of "sandwich" semigroups. Also we define a
special module over even- and odd-reduced supermatrix sets, and the generalized
Cayley-Hamilton theorem is proved for them. It is shown that the odd-reduced
supermatrices represent semigroup bands and Rees matrix semigroups over a unit
group.Comment: 22 pages, Standard LaTeX with AmS font
CHARA/MIRC observations of two M supergiants in Perseus OB1: temperature, Bayesian modeling, and compressed sensing imaging
Two red supergiants of the Per OB1 association, RS Per and T Per, have been
observed in H band using the MIRC instrument at the CHARA array. The data show
clear evidence of departure from circular symmetry. We present here new
techniques specially developed to analyze such cases, based on state-of-the-art
statistical frameworks. The stellar surfaces are first modeled as limb-darkened
discs based on SATLAS models that fit both MIRC interferometric data and
publicly available spectrophotometric data. Bayesian model selection is then
used to determine the most probable number of spots. The effective surface
temperatures are also determined and give further support to the recently
derived hotter temperature scales of red su- pergiants. The stellar surfaces
are reconstructed by our model-independent imaging code SQUEEZE, making use of
its novel regularizer based on Compressed Sensing theory. We find excellent
agreement between the model-selection results and the reconstructions. Our
results provide evidence for the presence of near-infrared spots representing
about 3-5% of the stellar flux
- …