Forming short-period Wolf-Rayet X-ray binaries and double black holes through stable mass transfer

We show that black-hole High-Mass X-ray Binaries (HMXBs) with O- or B-type donor stars and relatively short orbital periods, of order one week to several months may survive spiral in, to then form Wolf-Rayet (WR) X-ray binaries with orbital periods of order a day to a few days; while in systems where the compact star is a neutron star, HMXBs with these orbital periods never survive spiral-in. We therefore predict that WR X-ray binaries can only harbor black holes. The reason why black-hole HMXBs with these orbital periods may survive spiral in is: the combination of a radiative envelope of the donor star, and a high mass of the compact star. In this case, when the donor begins to overflow its Roche lobe, the systems are able to spiral in slowly with stable Roche-lobe overflow, as is shown by the system SS433. In this case the transferred mass is ejected from the vicinity of the compact star (so-called "isotropic re-emission" mass loss mode, or "SS433-like mass loss"), leading to gradual spiral-in. If the mass ratio of donor and black hole is $>3.5$, these systems will go into CE evolution and are less likely to survive. If they survive, they produce WR X-ray binaries with orbital periods of a few hours to one day. Several of the well-known WR+O binaries in our Galaxy and the Magellanic Clouds, with orbital periods in the range between a week and several months, are expected to evolve into close WR-Black-Hole binaries,which may later produce close double black holes. The galactic formation rate of double black holes resulting from such systems is still uncertain, as it depends on several poorly known factors in this evolutionary picture. It might possibly be as high as $\sim 10^{-5}$ per year.Comment: MNRAS in pres

Strange stars in low-mass binary pulsar systems

Based on observational facts and a variety of theoretical arguments we discuss in this work the possibility that pulsars in Low-Mass Binary Pulsar systems could be strange stars rather than neutron stars. It is shown that, although subject to reasonable uncertainties, the consideration of the physics of the SQM core and thin normal crusts leads to the prediction of several observed features of the magnetic field history of these systems whitin this working hypothesis.Comment: 6 pages, no figures, PlainTex file submitted to IJMP

Expected Coalescence Rate of Double Neutron Stars for Ground Based Interferometers

In this paper we present new estimates of the coalescence rate of neutron star binaries in the local universe and we discuss its consequences for the first generations of ground based interferometers. Our approach based on both evolutionary and statistical methods gives a galactic merging rate of 1.7 10$^{-5}$ yr$^{-1}$, in the range of previous estimates 10$^{-6}$ - 10$^{-4}$ yr$^{-1}$. The local rate which includes the contribution of elliptical galaxies is two times higher, in the order of 3.4 10$^{-5}$ yr$^{-1}$. We predict one detection every 148 and 125 years with initial VIRGO and LIGO, and up to 6 events per year with their advanced configuration. Our recent detection rate estimates from investigations on VIRGO future improvements are quoted.Comment: talk given at the GWDAW9 (Annecy, 2004) to be published in CQ

Type Ia Supernovae: An Examination of Potential Progenitors and the Redshift Distribution

We examine the possibility that supernovae type Ia (SN Ia) are produced by white dwarfs accreting from Roche-lobe filling evolved companions, under the assumption that a strong optically thick stellar wind from accretor is able to stabilize the mass transfer. We show that if a mass transfer phase on a thermal timescale precedes a nuclear burning driven phase, then such systems (of which the supersoft X-ray sources are a subgroup) can account for about 10% of the inferred SN Ia rate. In addition, we examine the cosmic history of the supernova rate, and we show that the ratio of the rate of SN Ia to the rate of supernovae produced by massive stars (supernovae of types II, Ib, Ic) should increase from about z = 1 towards lower redshifts.Comment: 29 pages, Latex, 6 figures, aasms4.sty, psfig.sty, to appear in The Astrophysical Journa

Midwives' work-related fear and anxiety and its impact on their wellbeing and performance. A qualitative study of perceived anxiety in community midwives

INTRODUCTION: Working with acute situations is usually part of midwifery practice. In the Netherlands the community midwives work in a context where they are mostly the sole decision-makers and policymakers and often do not have the support of a multidisciplinary team during a birth. How Dutch community midwives maintain their emotional hygiene is not known. This study aims to explore how Dutch midwives perceive fear and its influence on their performance.METHODS: This is a qualitative study with semi-structured interviews of 19 Dutch community midwives between October 2018 and January 2019.RESULTS: Four themes were identified: 1) midwives' perceptions of fear and anxiety, 2) how years of experience affect fear and anxiety, 3) influence of the work content; and 4) implications for performance. Midwives perceived fear in acute situations where maternal and/or fetal complications were imminent. Participants perceived anxiety either as helpful or a hindrance. Awareness of these feelings helps them to regulate whether or not to give in to these feelings.CONCLUSIONS: Our findings suggest similar perspectives on fear in Dutch community midwives compared to previous outcomes. In the Netherlands, midwives seem reluctant to talk about fear and anxiety in the profession. The awareness of these emotions occurring while working is essential for the wellbeing of midwives, as well as the importance of knowing how to act on fear and anxiety.</p

The heterogeneity of the biliary tree

[Image: see text

GRAIL, an omni-directional gravitational wave detector

A cryogenic spherical and omni-directional resonant-mass detector proposed by the GRAIL collaboration is described.Comment: 5 pages, 4 figs., contribution to proceedings GW Data Analysis Workshop, Paris, nov. 199

Evidence for Recipient-Derived Cells in Peribiliary Glands and Biliary Epithelium of the Large Donor Bile Ducts After Liver Transplantation

Introduction Chimerism after orthotopic liver transplantation (OLT) has largely been investigated in intrahepatic cellular constituents. However, little is known about chimerism in the extrahepatic and large intrahepatic bile ducts. Our aim was to evaluate the presence and extent of chimerism after OLT in the peribiliary glands (PBG) and the luminal epithelium of the large donor bile ducts. Methods For this study, we examined six extrahepatic and large intrahepatic bile ducts from livers that were re-transplanted. In all cases there was a sex-mismatch between donor and recipient (female donor organ and male recipient), which allowed to discriminate between donor- and recipient-derived cells. Specimens from female to female transplants were used as negative controls and male to male transplants as positive controls. Fluorescencein situhybridization (FISH) for Y and X chromosomes was performed and the percentage of XY positive cells was determined among biliary epithelial cells. Immunohistochemistry was used to correlate chimerism with histological features. Results Cholangiocellular chimerism in all studied specimens ranged from 14 to 52%. The degree of chimerism was not associated with biliary damage. Marked chimerism was present at 5 days post-OLT. Ki-67-positivity was detected in 1-8% of the epithelial cells at the time of liver re-transplantation, and this correlated inversely with the degree of chimerism. Conclusion Recipient-derived cholangiocytes are present in the large bile ducts of the donor liver after OLT. The presence of chimerism in the large bile ducts suggests that recipient-derived cells may play a role in biliary regeneration following ischemia-induced injury during OLT

Generative models of the human connectome

The human connectome represents a network map of the brain's wiring diagram and the pattern into which its connections are organized is thought to play an important role in cognitive function. The generative rules that shape the topology of the human connectome remain incompletely understood. Earlier work in model organisms has suggested that wiring rules based on geometric relationships (distance) can account for many but likely not all topological features. Here we systematically explore a family of generative models of the human connectome that yield synthetic networks designed according to different wiring rules combining geometric and a broad range of topological factors. We find that a combination of geometric constraints with a homophilic attachment mechanism can create synthetic networks that closely match many topological characteristics of individual human connectomes, including features that were not included in the optimization of the generative model itself. We use these models to investigate a lifespan dataset and show that, with age, the model parameters undergo progressive changes, suggesting a rebalancing of the generative factors underlying the connectome across the lifespan.Comment: 38 pages, 5 figures + 19 supplemental figures, 1 tabl

Tracking Infant Development With a Smartphone:A Practical Guide to the Experience Sampling Method

The COVID-19 pandemic has forced developmental researchers to rethink their traditional research practices. The growing need to study infant development at a distance has shifted our research paradigm to online and digital monitoring of infants and families, using electronic devices, such as smartphones. In this practical guide, we introduce the Experience Sampling Method (ESM) – a research method to collect data, in the moment, on multiple occasions over time – for examining infant development at a distance. ESM is highly suited for assessing dynamic processes of infant development and family dynamics, such as parent-infant interactions and parenting practices. It can also be used to track highly fluctuating family dynamics (e.g., infant and parental mood or behavior) and routines (e.g., activity levels and feeding practices). The aim of the current paper was to provide an overview by explaining what ESM is and for what types of research ESM is best suited. Next, we provide a brief step-by-step guide on how to start and run an ESM study, including preregistration, development of a questionnaire, using wearables and other hardware, planning and design considerations, and examples of possible analysis techniques. Finally, we discuss common pitfalls of ESM research and how to avoid them