84 research outputs found
Modelling a high-mass red giant observed by CoRoT
The G6 giant HR\,2582 (HD\,50890) was observed by CoRoT for approximately 55
days. Mode frequencies are extracted from the observed Fourier spectrum of the
light curve. Numerical stellar models are then computed to determine the
characteristics of the star (mass, age, etc...) from the comparison with
observational constraints. We provide evidence for the presence of solar-like
oscillations at low frequency, between 10 and 20\,Hz, with a regular
spacing of Hz between consecutive radial orders. Only radial
modes are clearly visible. From the models compatible with the observational
constraints used here, We find that HR\,2582 (HD\,50890) is a massive star with
a mass in the range (3--\,5\,), clearly above the red clump. It
oscillates with rather low radial order ( = 5\,--\,12) modes. Its
evolutionary stage cannot be determined with precision: the star could be on
the ascending red giant branch (hydrogen shell burning) with an age of
approximately 155 Myr or in a later phase (helium burning). In order to obtain
a reasonable helium amount, the metallicity of the star must be quite subsolar.
Our best models are obtained with a mixing length significantly smaller than
that obtained for the Sun with the same physical description (except
overshoot). The amount of core overshoot during the main-sequence phase is
found to be mild, of the order of 0.1\,.Comment: Accepted in A&
Personalized recurrence risk assessment following the birth of a child with a pathogenic de novo mutation
Following the diagnosis of a paediatric disorder caused by an apparently de novo mutation, a recurrence risk of 1–2% is frequently quoted due to the possibility of parental germline mosaicism; but for any specific couple, this figure is usually incorrect. We present a systematic approach to providing individualized recurrence risk. By combining locus-specific sequencing of multiple tissues to detect occult mosaicism with long-read sequencing to determine the parent-of-origin of the mutation, we show that we can stratify the majority of couples into one of seven discrete categories associated with substantially different risks to future offspring. Among 58 families with a single affected offspring (representing 59 de novo mutations in 49 genes), the recurrence risk for 35 (59%) was decreased below 0.1%, but increased owing to parental mixed mosaicism for 5 (9%)—that could be quantified in semen for paternal cases (recurrence risks of 5.6–12.1%). Implementation of this strategy offers the prospect of driving a major transformation in the practice of genetic counselling
Personalized recurrence risk assessment following the birth of a child with a pathogenic de novo mutation
Following the diagnosis of a paediatric disorder caused by an apparently de novo mutation, a recurrence risk of 1-2% is frequently quoted due to the possibility of parental germline mosaicism; but for any specific couple, this figure is usually incorrect. We present a systematic approach to providing individualized recurrence risk. By combining locus-specific sequencing of multiple tissues to detect occult mosaicism with long-read sequencing to determine the parent-of-origin of the mutation, we show that we can stratify the majority of couples into one of seven discrete categories associated with substantially different risks to future offspring. Among 58 families with a single affected offspring (representing 59 de novo mutations in 49 genes), the recurrence risk for 35 (59%) was decreased below 0.1%, but increased owing to parental mixed mosaicism for 5 (9%)-that could be quantified in semen for paternal cases (recurrence risks of 5.6-12.1%). Implementation of this strategy offers the prospect of driving a major transformation in the practice of genetic counselling
Stellar Structure and Evolution: Deductions from Hipparcos
During the last decade, the understanding of fine features of the structure
and evolution of stars has become possible as a result of enormous progress
made in the acquisition of high-quality observational and experimental data and
of new developments and refinements in the theoretical description of stellar
plasmas. The confrontation of high-quality observations with sophisticated
stellar models has allowed many aspects of the theory to be validated, and
several characteristics of stars relevant to Galactic evolution and cosmology
to be inferred. This paper is a review of the results of recent studies
undertaken in the context of the Hipparcos mission, taking benefit of the
high-quality astrometric data it has provided. Successes are discussed, as well
as the problems that have arisen and suggestions proposed to solve them. Future
observational and theoretical developments expected and required in the field
are also presented.Comment: 56 pages, including 9 figures, Ann. Rev. Astron. Astrophys. Vol. 38,
September 2000 (in press
Multimodal analysis of cell-free DNA whole-genome sequencing for pediatric cancers with low mutational burden
Sequencing of cell-free DNA in the blood of cancer patients (liquid biopsy) provides attractive opportunities for early diagnosis, assessment of treatment response, and minimally invasive disease monitoring. To unlock liquid biopsy analysis for pediatric tumors with few genetic aberrations, we introduce an integrated genetic/epigenetic analysis method and demonstrate its utility on 241 deep whole-genome sequencing profiles of 95 patients with Ewing sarcoma and 31 patients with other pediatric sarcomas. Our method achieves sensitive detection and classification of circulating tumor DNA in peripheral blood independent of any genetic alterations. Moreover, we benchmark different metrics for cell-free DNA fragmentation analysis, and we introduce the LIQUORICE algorithm for detecting circulating tumor DNA based on cancer-specific chromatin signatures. Finally, we combine several fragmentation-based metrics into an integrated machine learning classifier for liquid biopsy analysis that exploits widespread epigenetic deregulation and is tailored to cancers with low mutation rates. Clinical associations highlight the potential value of cfDNA fragmentation patterns as prognostic biomarkers in Ewing sarcoma. In summary, our study provides a comprehensive analysis of circulating tumor DNA beyond recurrent genetic aberrations, and it renders the benefits of liquid biopsy more readily accessible for childhood cancers
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