137 research outputs found
Constraining the near-core rotation of the gamma Doradus star 43 Cygni using BRITE-Constellation data
Photometric time series of the Dor star 43 Cyg obtained with the
BRITE-Constellation nano-satellites allow us to study its pulsational
properties in detail and to constrain its interior structure. We aim to find a
g-mode period spacing pattern that allows us to determine the near-core
rotation rate of 43 Cyg and redetermine the star's fundamental atmospheric
parameters and chemical composition. We conducted a frequency analysis using
the 156-days long data set obtained with the BRITE-Toronto satellite and
employed a suite of MESA/GYRE models to derive the mode identification,
asymptotic period spacing and near-core rotation rate. We also used
high-resolution, high signal-to-noise ratio spectroscopic data obtained at the
1.2m Mercator telescope with the HERMES spectrograph to redetermine the
fundamental atmospheric parameters and chemical composition of 43 Cyg using the
software Spectroscopy Made Easy (SME). We detected 43 intrinsic pulsation
frequencies and identified 18 of them to be part of a period spacing pattern
consisting of prograde dipole modes with an asymptotic period spacing of . The near-core rotation rate was
determined to be . The
atmosphere of 43 Cyg shows solar chemical composition at an effective
temperature of 7150 150 K, a log g of 4.2 0.6 dex and a projected
rotational velocity, , of 44 4 kms. The morphology
of the observed period spacing patterns shows indications of the presence of a
significant chemical gradient in the stellar interior.Comment: 9 pages, 8 figures, accepted by A&
BRITE-Constellation: Data processing and photometry
The BRITE mission is a pioneering space project aimed at the long-term
photometric monitoring of the brightest stars in the sky by means of a
constellation of nano-satellites. Its main advantage is high photometric
accuracy and time coverage inaccessible from the ground. The main aim of this
paper is the presentation of procedures used to obtain high-precision
photometry from a series of images acquired by the BRITE satellites in two
modes of observing, stare and chopping. We developed two pipelines
corresponding to the two modes of observing. The assessment of the performance
of both pipelines is presented. It is based on two comparisons, which use data
from six runs of the UniBRITE satellite: (i) comparison of photometry obtained
by both pipelines on the same data, which were partly affected by charge
transfer inefficiency (CTI), (ii) comparison of real scatter with theoretical
expectations. It is shown that for CTI-affected observations, the chopping
pipeline provides much better photometry than the other pipeline. For other
observations, the results are comparable only for data obtained shortly after
switching to chopping mode. Starting from about 2.5 years in orbit, the
chopping mode of observing provides significantly better photometry for
UniBRITE data than the stare mode. This paper shows that high-precision space
photometry with low-cost nano-satellites is achievable. The proposed meth- ods,
used to obtain photometry from images affected by high impulsive noise, can be
applied to data from other space missions or even to data acquired from
ground-based observations
Restricting calcium currents is required for correct fiber type specification in skeletal muscle
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Gene expression profiling for molecular distinction and characterization of laser captured primary lung cancers
<p>Abstract</p> <p>Methods</p> <p>We examined gene expression profiles of tumor cells from 29 untreated patients with lung cancer (10 adenocarcinomas (AC), 10 squamous cell carcinomas (SCC), and 9 small cell lung cancer (SCLC)) in comparison to 5 samples of normal lung tissue (NT). The European and American methodological quality guidelines for microarray experiments were followed, including the stipulated use of laser capture microdissection for separation and purification of the lung cancer tumor cells from surrounding tissue.</p> <p>Results</p> <p>Based on differentially expressed genes, different lung cancer samples could be distinguished from each other and from normal lung tissue using hierarchical clustering. Comparing AC, SCC and SCLC with NT, we found 205, 335 and 404 genes, respectively, that were at least 2-fold differentially expressed (estimated false discovery rate: < 2.6%). Different lung cancer subtypes had distinct molecular phenotypes, which also reflected their biological characteristics. Differentially expressed genes in human lung tumors which may be of relevance in the respective lung cancer subtypes were corroborated by quantitative real-time PCR.</p> <p>Genetic programming (GP) was performed to construct a classifier for distinguishing between AC, SCC, SCLC, and NT. Forty genes, that could be used to correctly classify the tumor or NT samples, have been identified. In addition, all samples from an independent test set of 13 further tumors (AC or SCC) were also correctly classified.</p> <p>Conclusion</p> <p>The data from this research identified potential candidate genes which could be used as the basis for the development of diagnostic tools and lung tumor type-specific targeted therapies.</p
Macroscopic quantum resonators (MAQRO)
Quantum physics challenges our understanding of the nature of physical
reality and of space-time and suggests the necessity of radical revisions of
their underlying concepts. Experimental tests of quantum phenomena involving
massive macroscopic objects would provide novel insights into these fundamental
questions. Making use of the unique environment provided by space, MAQRO aims
at investigating this largely unexplored realm of macroscopic quantum physics.
MAQRO has originally been proposed as a medium-sized fundamental-science space
mission for the 2010 call of Cosmic Vision. MAQRO unites two experiments:
DECIDE (DECoherence In Double-Slit Experiments) and CASE (Comparative
Acceleration Sensing Experiment). The main scientific objective of MAQRO, which
is addressed by the experiment DECIDE, is to test the predictions of quantum
theory for quantum superpositions of macroscopic objects containing more than
10e8 atoms. Under these conditions, deviations due to various suggested
alternative models to quantum theory would become visible. These models have
been suggested to harmonize the paradoxical quantum phenomena both with the
classical macroscopic world and with our notion of Minkowski space-time. The
second scientific objective of MAQRO, which is addressed by the experiment
CASE, is to demonstrate the performance of a novel type of inertial sensor
based on optically trapped microspheres. CASE is a technology demonstrator that
shows how the modular design of DECIDE allows to easily incorporate it with
other missions that have compatible requirements in terms of spacecraft and
orbit. CASE can, at the same time, serve as a test bench for the weak
equivalence principle, i.e., the universality of free fall with test-masses
differing in their mass by 7 orders of magnitude.Comment: Proposal for a medium-sized space mission, 28 pages, 9 figures - in
v2, we corrected some minor mistakes and replaced fig. 9 with a
higher-resolution version; Experimental Astronomy, March 2012, Online, Open
Acces
Genome Sequencing of SHH Medulloblastoma Predicts Genotype-Related Response to Smoothened Inhibition
SummarySmoothened (SMO) inhibitors recently entered clinical trials for sonic-hedgehog-driven medulloblastoma (SHH-MB). Clinical response is highly variable. To understand the mechanism(s) of primary resistance and identify pathways cooperating with aberrant SHH signaling, we sequenced and profiled a large cohort of SHH-MBs (n = 133). SHH pathway mutations involved PTCH1 (across all age groups), SUFU (infants, including germline), and SMO (adults). Children >3 years old harbored an excess of downstream MYCN and GLI2 amplifications and frequent TP53 mutations, often in the germline, all of which were rare in infants and adults. Functional assays in different SHH-MB xenograft models demonstrated that SHH-MBs harboring a PTCH1 mutation were responsive to SMO inhibition, whereas tumors harboring an SUFU mutation or MYCN amplification were primarily resistant
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