Binary populations and stellar dynamics in young clusters

We first summarize work that has been done on the effects of binaries on theoretical population synthesis of stars and stellar phenomena. Next, we highlight the influence of stellar dynamics in young clusters by discussing a few candidate UFOs (unconventionally formed objects) like intermediate mass black holes, Eta Carinae, Zeta Puppis, Gamma Velorum and WR 140.Comment: Contributed paper IAU 250: Massive Stars as Cosmic Engine

The formation and evolution of very massive stars in dense stellar systems

The early evolution of dense stellar systems is governed by massive single star and binary evolution. Core collapse of dense massive star clusters can lead to the formation of very massive objects through stellar collisions ($M\geq$ 1000 \msun). Stellar wind mass loss determines the evolution and final fate of these objects, and decides upon whether they form black holes (with stellar or intermediate mass) or explode as pair instability supernovae, leaving no remnant. We present a computationaly inexpensive evolutionary scheme for very massive stars that can readily be implemented in an N-body code. Using our new N-body code 'Youngbody' which includes a detailed treatment of massive stars as well as this new scheme for very massive stars, we discuss the formation of intermediate mass and stellar mass black holes in young starburst regions. A more detailed account of these results can be found in Belkus et al. 2007.Comment: 2 pages, 2 figures. To appear in conference proceedings for IAUS246, 200

The evolution of very massive stars

Publisher's version/PDFCore collapse of dense massive star clusters is unavoidable, and this leads to the formation of massive objects, with masses of up to 1000 M[circled dot] and even larger. When these objects become stars, stellar wind mass loss determines their evolution and final fate, and decides on whether they form black holes (with normal mass or with intermediate mass) or explode as a pair-instability supernova. In this paper we discuss the evolution of very massive stars and present a convenient evolution recipe that can be implemented in a gravitational N-body code to study the dynamics of dense massive clusters

Patients with anorectal malformation and upper limb anomalies:genetic evaluation is warranted

Abstract The objective of this study was to compare the prevalence of genetic disorders in anorectal malformation (ARM) patients with upper limb anomalies to that in ARM patients with other associated anomalies. A retrospective case study was performed in two pediatric surgery centers. All patients born between 1990 and 2012 were included. VACTERL (vertebral defects (V), anal atresia (A), cardiac malformations (C), tracheoesophageal fistula with esophageal atresia (TE), renal dysplasia (R), and limb anomalies (L)) was defined as at least three components present. We included 700 ARM patients: 219 patients (31 %) had isolated ARM, 43 patients (6 %) had a major upper limb anomaly, and 438 patients (63 %) had other associated anomalies. The most prevalent upper limb anomalies were radial dysplasia (n=12) and hypoplastic thumb (n= 11). Ten of the 43 patients (23 %) with an upper limb anomaly were diagnosed with a genetic disorder—nine also met the V

The WR population predicted by massive single star and by massive binary evolution

We discuss differences between massive single star and massive close binary population number synthesis predictions of WR stars. We show that the WC/WN number ratio as function of metallicity depends significantly on whether or not binaries are included. Furthermore, the observed WC(+OB)/WN(+OB) number ratio in the Solar neighborhood seems to indicate that the WR mass loss rates are lower by another factor two compared to recently proposed clumping corrected formalisms. We then demonstrate that the observed lower luminosity distribution of single WN stars can be explained in a satisfactory way by massive single star evolutionary computations where the red supergiant phase is calculated using a stellar wind mass loss rate formalism that is based on recent observations.Comment: 13 pages, 4 figures; comments and criticisms on this preprint are very welcom

Patients with anorectal malformation and upper limb anomalies: genetic evaluation is warranted

The objective of this study was to compare the prevalence of genetic disorders in anorectal malformation (ARM) patients with upper limb anomalies to that in ARM patients with other associated anomalies. A retrospective case study was performed in two pediatric surgery centers. All patients born between 1990 and 2012 were included. VACTERL (vertebral defects (V), anal atresia (A), cardiac malformations (C), tracheoesophageal fistula with esophageal atresia (TE), renal dysplasia (R), and limb anomalies (L)) was defined as at least three components present. We included 700 ARM patients: 219 patients (31 %) had isolated ARM, 43 patients (6 %) had a major upper limb anomaly, and 438 patients (63 %) had other associated anomalies. The most prevalent upper limb anomalies were radial dysplasia (n = 12) and hypoplastic thumb (n = 11). Ten of the 43 patients (23 %) with an upper limb anomaly were diagnosed with a genetic disorder—nine also met the VACTERL criteria—vs. 9 % of ARM patients with other anomalies (p = 0.004, chi-squared test). Conclusion: Genetic disorders are twice as frequently diagnosed in ARM patients with upper limb anomalies than in those with other anomalies. As they also frequently meet the VACTERL criteria, it is important to consider VACTERL as a diagnosis per exclusionem. Genetic counseling is certainly warranted in these patients.What is Known:• Anorectal malformations (ARMs) often co-occur with other congenital anomalies, including upper limb anomalies, mainly of pre-axial origin.• Co-occurrence of ARMs and upper limb anomalies is seen in disorders such as Townes-Brocks syndrome, Fanconi anemia, and VACTERL association.What is New:• ARM patients with a major upper limb anomaly—with or without other congenital anomalies—have a twofold greater chance of a genetic disorder than have non-isolated ARM patients without upper limb anomalies.• Not all upper limb anomalies in ARM patients are part of the VACTERL association; a workup for genetic evaluation is proposed

Clinical relevance of rapid FOXF1-targeted sequencing in patients suspected of alveolar capillary dysplasia with misalignment of pulmonary veins

Alveolar capillary dysplasia with misalignment of pulmonary Veins (ACDMPV) is a lethal congenital lung disorder that presents shortly after birth with respiratory failure and therapy-resistant pulmonary hypertension. It is associated with heterozygous point mutations and genomic deletions that involve the FOXF1 gene or its upstream regulatory region. Patients are unresponsive to the intensive treatment regiments and suffer unnecessarily, because ACDMPV is not always timely recognized and histological diagnosis is invasive and time-consuming. Here, we demonstrate the usefulness of a non-invasive, fast genetic test for FOXF1 variants that we previously developed to rapidly diagnose ACDMPV and reduce the time of hospitalization.</p