311 research outputs found
Variability survey in the CoRoT SRa01 field: Implications of eclipsing binary distribution on cluster formation in NGC 2264
Time-series photometry of the CoRoT field SRa01 was carried out with the
Berlin Exoplanet Search Telescope II (BEST II) in 2008/2009. A total of 1,161
variable stars were detected, of which 241 were previously known and 920 are
newly found. Several new, variable young stellar objects have been discovered.
The study of the spatial distribution of eclipsing binaries revealed the higher
relative frequency of Algols toward the center of the young open cluster NGC
2264. In general Algol frequency obeys an isotropic distribution of their
angular momentum vectors, except inside the cluster, where a specific
orientation of the inclinations is the case. We suggest that we see the orbital
plane of the binaries almost edge-on.Comment: 18 pages, 8 figures, accepted for publication in Ap
The Berlin Exoplanet Search Telescope II. Catalog of Variable Stars. I. Characterization of Three Southern Target Fields
A photometric survey of three Southern target fields with BEST II yielded the
detection of 2,406 previously unknown variable stars and an additional 617
stars with suspected variability. This study presents a catalog including their
coordinates, magnitudes, light curves, ephemerides, amplitudes, and type of
variability. In addition, the variability of 17 known objects is confirmed,
thus validating the results. The catalog contains a number of known and new
variables that are of interest for further astrophysical investigations, in
order to, e.g., search for additional bodies in eclipsing binary systems, or to
test stellar interior models.
Altogether, 209,070 stars were monitored with BEST II during a total of 128
nights in 2009/2010. The overall variability fraction of 1.2-1.5% in these
target fields is well comparable to similar ground-based photometric surveys.
Within the main magnitude range of , we identify
0.67(3)% of all stars to be eclipsing binaries, which indicates a completeness
of about one third for this particular type in comparison to space surveys.Comment: accepted to A
Recommended from our members
X-ray Fluorescence Particle Size and Scattering Angle Considerations Preparatory Experiments for the Calibration and Interpretation of C1XS Data
ISRO’s Chandrayaan-1 mission to the Moon is due to be launched in April 2008. Part of its payload is C1XS, a compact X-ray fluorescence (XRF) spectrometer which will provide high quality elemental mapping of the lunar surface [1]. In flight, the input source (solar X-ray spectrum) will be measured by the accompanying XSM payload [2]. An ‘in-house’ IDL XRF modelling code (referred to as the ‘C1XS XRF code’ [3]), which is based on the methods of [4], will be used to convert the C1XS data from X-ray fluxes into elemental ratios and abundances. This study outlines a plan of testing the accuracy and robustness of the code, using XRF spectral data from well characterised geological samples. We aim to quantify how XRF intensity varies with changing particle size and phase angle (θ in Fig. 1) geometry, in order to simulate changes in the solar aspect angle (angle between the Sun, the lunar surface and the detectors), as well as surface topography. These issues have previously been studied within a materials science context e.g. [5 – 9], but rarely but rarely for heterogeneous, geological samples [10 – 12]
Neurocognitive Outcome and Compensating Possibilities in Children and Adolescents Treated for Acute Lymphoblastic Leukemia With Chemotherapy Only
Aim: To examine the neurocognitive outcomes in children and adolescents with acute lymphoblastic leukemia (ALL) in remission who were treated with systemic chemotherapy only (CTO). Methods: Neurocognitive performances in 36 children and adolescents, aged 8.4–15.3 years, in long-term remission from ALL 4.3–12.4 years post diagnosis, without relapse, and with no pre-diagnosis history of neurodevelopmental disorder were compared with 36 healthy controls matched for gender, age, and parents’ socio-economic status. The former patients and the healthy controls completed an extensive battery of standardized neuropsychological tests. Results: Survivors who were treated by CTO obtained significantly lower scores than did healthy controls on the domains of Copy and drawing (p = 0.001; Cohen’s d 0.85; after controlling for Type 1 errors q = 0.006), Arithmetic (p = 0.001; Cohen’s d 0.80; after controlling for Type 1 errors, q = 0.006), and Tactile sensory functions (p = 0.008; Cohen’s d 0.65; after controlling for Type 1 errors, q = 0.03). Fifty percent of the ALL group were more than 1 SD below the control groups mean on Copy and drawing. There was an interaction between age and group (ALL vs. Control, p = 0.042) on Copy and drawing, indicating that the youngest ALL patients exhibited the worst performance. The oldest ALL patients performed equal to or better than the controls. A tendency in the same direction was seen for Arithmetic and Tactile sensory functions. The ALL survivors exhibited a steeper rising learning slope on repeated tests, with lower scores on a tactile problem-solving task, tactile sensory tests, verbal memory, and visual attention, but they performed as well as the controls when stimuli were repeated. Conclusion: The results indicate that neurocognitive long-term sequelae in ALL survivors are limited to specific domains – particularly complex drawing, arithmetic, and tactile processing, and novelty processing. Cognitive deficits are shown among the youngest ALL patients. Intervention programs and school programs should account for difficulties with processing new information and taking advantage of repetitions as a strength, which may prevent survivors from falling behind their peers.publishedVersio
Lunar chemistry from Chandrayaan-1, C1XS results from Southern nearside highlands of the Moon
This article does not have an abstract
A Mercury Lander Mission Concept Study for the Next Decadal Survey
Mariner 10 provided our first closeup reconnaissance of Mercury during its three flybys in 1974 and 1975. MESSENGERs 20112015 orbital investigation enabled numerous discoveries, several of which led to substantial or complete changes in our fundamental understanding of the planet. Among these were the unanticipated, widespread presence of volatile elements (e.g., Na, K, S); a surface with extremely low Fe abundance whose darkening agent is likely C; a previously unknown landformhollows that may form by volatile sublimation from within rocks exposed to the harsh conditions on the surface; a history of expansive effusive and explosive volcanism; substantial radial contraction of the planet from interior cooling; offset of the dipole moment of the internal magnetic field northward from the geographic equator by ~20% of the planets radius; crustal magnetization, attributed at least in part to an ancient field; unexpected seasonal variability and relationships among exospheric species and processes; and the presence in permanently shadowed polar terrain of water ice and other volatile materials, likely to include complex organic compounds. Mercurys highly chemically reduced and unexpectedly volatile-rich composition is unique among the terrestrial planets and was not predicted by earlier hypotheses for the planets origin. As an end-member of terrestrial planet formation, Mercury holds unique clues about the original distribution of elements in the earliest stages of the Solar System and how planets (and exoplanets) form and evolve in close proximity to their host stars. The BepiColombo mission promises to expand our knowledge of this planet and to shed light on some of the mysteries revealed by the MESSENGER mission. However, several fundamental science questions raised by MESSENGERs pioneering exploration of Mercury can only be answered with in situ measurements from the planets surface
Neurocognitive Outcome and Compensating Possibilities in Children and Adolescents Treated for Acute Lymphoblastic Leukemia With Chemotherapy Only
Aim: To examine the neurocognitive outcomes in children and adolescents with acute lymphoblastic leukemia (ALL) in remission who were treated with systemic chemotherapy only (CTO).Methods: Neurocognitive performances in 36 children and adolescents, aged 8.4–15.3 years, in long-term remission from ALL 4.3–12.4 years post diagnosis, without relapse, and with no pre-diagnosis history of neurodevelopmental disorder were compared with 36 healthy controls matched for gender, age, and parents’ socio-economic status. The former patients and the healthy controls completed an extensive battery of standardized neuropsychological tests.Results: Survivors who were treated by CTO obtained significantly lower scores than did healthy controls on the domains of Copy and drawing (p = 0.001; Cohen’s d 0.85; after controlling for Type 1 errors q = 0.006), Arithmetic (p = 0.001; Cohen’s d 0.80; after controlling for Type 1 errors, q = 0.006), and Tactile sensory functions (p = 0.008; Cohen’s d 0.65; after controlling for Type 1 errors, q = 0.03). Fifty percent of the ALL group were more than 1 SD below the control groups mean on Copy and drawing. There was an interaction between age and group (ALL vs. Control, p = 0.042) on Copy and drawing, indicating that the youngest ALL patients exhibited the worst performance. The oldest ALL patients performed equal to or better than the controls. A tendency in the same direction was seen for Arithmetic and Tactile sensory functions. The ALL survivors exhibited a steeper rising learning slope on repeated tests, with lower scores on a tactile problem-solving task, tactile sensory tests, verbal memory, and visual attention, but they performed as well as the controls when stimuli were repeated.Conclusion: The results indicate that neurocognitive long-term sequelae in ALL survivors are limited to specific domains – particularly complex drawing, arithmetic, and tactile processing, and novelty processing. Cognitive deficits are shown among the youngest ALL patients. Intervention programs and school programs should account for difficulties with processing new information and taking advantage of repetitions as a strength, which may prevent survivors from falling behind their peers
Improved Variable Star Search in Large Photometric Data Sets -- New Variables in CoRoT Field LRa02 Detected by BEST II
The CoRoT field LRa02 has been observed with the Berlin Exoplanet Search
Telescope II (BEST II) during the southern summer 2007/2008. A first analysis
of stellar variability led to the publication of 345 newly discovered variable
stars. Now, a deeper analysis of this data set was used to optimize the
variability search procedure. Several methods and parameters have been tested
in order to improve the selection process compared to the widely used J index
for variability ranking. This paper describes an empirical approach to treat
systematic trends in photometric data based upon the analysis of variance
statistics that can significantly decrease the rate of false detections.
Finally, the process of reanalysis and method improvement has virtually
doubled the number of variable stars compared to the first analysis by Kabath
et al. A supplementary catalog of 272 previously unknown periodic variables
plus 52 stars with suspected variability is presented. Improved ephemerides are
given for 19 known variables in the field. In addition, the BEST II results are
compared with CoRoT data and its automatic variability classification.Comment: 16 pages, 15 figures; figure set, machine-readable and VO tables
available in the electronic edition of the Astronomical Journa
A Yeast Model of FUS/TLS-Dependent Cytotoxicity
FUS/TLS is a nucleic acid binding protein that, when mutated, can cause a subset of familial amyotrophic lateral sclerosis (fALS). Although FUS/TLS is normally located predominantly in the nucleus, the pathogenic mutant forms of FUS/TLS traffic to, and form inclusions in, the cytoplasm of affected spinal motor neurons or glia. Here we report a yeast model of human FUS/TLS expression that recapitulates multiple salient features of the pathology of the disease-causing mutant proteins, including nuclear to cytoplasmic translocation, inclusion formation, and cytotoxicity. Protein domain analysis indicates that the carboxyl-terminus of FUS/TLS, where most of the ALS-associated mutations are clustered, is required but not sufficient for the toxicity of the protein. A genome-wide genetic screen using a yeast over-expression library identified five yeast DNA/RNA binding proteins, encoded by the yeast genes ECM32, NAM8, SBP1, SKO1, and VHR1, that rescue the toxicity of human FUS/TLS without changing its expression level, cytoplasmic translocation, or inclusion formation. Furthermore, hUPF1, a human homologue of ECM32, also rescues the toxicity of FUS/TLS in this model, validating the yeast model and implicating a possible insufficiency in RNA processing or the RNA quality control machinery in the mechanism of FUS/TLS mediated toxicity. Examination of the effect of FUS/TLS expression on the decay of selected mRNAs in yeast indicates that the nonsense-mediated decay pathway is probably not the major determinant of either toxicity or suppression.Fidelity Biosciences (Firm)Fidelity Biosciences (Firm) (Research Inititative)ALS Therapy AllianceNational Institutes of Health (U.S.) (NIH 1RC1NS06839)National Institutes of Health (U.S.) (NIH U01NS05225-03)National Institutes of Health (U.S.) (NIH R01NS050557-05)National Institutes of Health (U.S.) (NIH 1RC2NS070342-01)Pierre L. de Bourgknecht ALS Research FoundationNational Science Foundation (U.S.) (NS614192
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