Chandra X-ray spectroscopy of the focused wind in the Cygnus X-1 system III. Dipping in the low/hard state

We present an analysis of three Chandra High Energy Transmission Gratings observations of the black hole binary Cyg X-1/HDE 226868 at different orbital phases. The stellar wind that is powering the accretion in this system is characterized by temperature and density inhomogeneities including structures, or "clumps", of colder, more dense material embedded in the photoionized gas. As these clumps pass our line of sight, absorption dips appear in the light curve. We characterize the properties of the clumps through spectral changes during various dip stages. Comparing the silicon and sulfur absorption line regions (1.6-2.7 keV $\equiv$ 7.7-4.6 {\AA}) in four levels of varying column depth reveals the presence of lower ionization stages, i.e., colder or denser material, in the deeper dip phases. The Doppler velocities of the lines are roughly consistent within each observation, varying with the respective orbital phase. This is consistent with the picture of a structure that consists of differently ionized material, in which shells of material facing the black hole shield the inner and back shells from the ionizing radiation. The variation of the Doppler velocities compared to a toy model of the stellar wind, however, does not allow us to pin down an exact location of the clump region in the system. This result, as well as the asymmetric shape of the observed lines, point at a picture of a complex wind structure.Comment: 19 pages, 15 figures, accepted for publication in A&

NICER/NuSTAR Characterization of 4U 1957+11: A Near Maximally Spinning Black Hole Potentially in the Mass Gap

© 2023. The Author(s). Published by the American Astronomical Society. This is an open access article distributed under the Creative Commons Attribution License, to view a copy of the license, see: https://creativecommons.org/licenses/by/4.0/4U 1957+11 is a black hole candidate system that has been in a soft X-ray spectral state since its discovery. We present analyses of recent joint NICER and NuSTAR spectra, which are extremely well described by a highly inclined disk accreting into a near maximally spinning black hole. Owing to the broad X-ray coverage of NuSTAR, the fitted spin and inclination are strongly constrained for our hypothesized disk models. The faintest spectra are observed out to 20 keV, even though their hard tail components are almost absent when described with a simple corona. The hard tail increases with luminosity, but shows clear two-track behavior with one track having appreciably stronger tails. The disk spectrum color-correction factor is anticorrelated with the strength of the hard tail (e.g., as measured by the Compton y parameter). Although the spin and inclination parameters are strongly constrained for our chosen model, the mass and distance are degenerate parameters. We use our spectral fits, along with a theoretical prior on color-correction, an observational prior on likely fractional Eddington luminosity, and an observational prior on distance obtained from Gaia studies, to present mass and distance contours for this system. The most likely parameters, given our presumed disk model, suggest a 4.6 M ⊙ black hole at 7.8 kpc observed at luminosities ranging from ≈1.7% to 9% of Eddington. This would place 4U 1957+11 as one of the few actively accreting sources within the mass gap of ≈2–5 M ⊙ where there are few known massive neutron stars or low-mass black holes. Higher mass and distance, however, remain viable.Peer reviewe

High-resolution X-ray spectroscopy of supergiant HMXB 4U 1700−37 during the compact object eclipse

We present an analysis of the first observation of the iconic high-mass X-ray binary 4U 1700−37 with the Chandra High-Energy Transmission Gratings (HETGs) during an X-ray eclipse. The goal of the observation was to study the structure/physical conditions in the clumpy stellar wind through high-resolution spectroscopy. We find the following: (a) Emission-line brightness from K-shell transitions, corresponding to near-neutral species, directly correlates with continuum illumination. However, these lines do not greatly diminish during eclipse. This is readily explained if fluorescence K α emission comes from the bulk of the wind. (b) The highly ionized Fe xxv and Fe xxvi Ly α diminish during eclipse. Thus, they must be produced in the vicinity of the compact object where log ξ > 3. (c) To describe the emission-line spectrum, the sum of two self-consistent photoionization models with low ionization (log ξ ∼ −1) and high ionization (log ξ ∼ 2.4) is required. From their emission measures, the clump-to-interclump density ratio can be estimated to be nc/ni ∼ 300. To fit the complex He-like Si xiii profile, the plasma requires a broadening with vbulk ∼ 840 km s−1. Reproducing the observed r ≈ f line fluxes requires the addition of a third collisionally ionized plasma. (d) Emission-line widths appear unresolved at the HETG resolution with the exception of silicon. There is no clear radial segregation between (quasi-)neutral and ionized species, consistent with cold wind clumps interspersed in a hot rarefied interclump medium.This research has been funded under the project ESP2017-85691-P. The research leading to these results has received funding from the European Union’s Horizon 2020 Programme under the Activities for the High-Energy Astrophysiscs Domain (AHEAD) project (grant agreement no. 654215). Victoria Grinberg (VG) was supported through the Margarete von Wrangell fellowship by the ESF and the Ministry of Science, Research and the Arts of Baden-Württemberg. Work at LLNL was performed under the auspices of the U.S. Department of Energy under contract no. DE-AC52-07NA27344 and supported through National Aeronautics and Space Administration (NASA) grants to Lawrence Livermore National Laboratory (LLNL). Lida M. Oskinova acknowledges Deutsches Zentrum für Luft und Raumfahrt (DLR) grant FKZ 50 OR 1508 and partial support by the Russian Government Program of Competitive Growth of Kazan Federal University

SOCIAL RECEPTION AND INCLUSION OF REFUGEES FROM UKRAINE

Our research aimed to study the ongoing phenomena of cross-border displacement of the Ukrainian population resulting from the Russian aggression that started on the 24th of February 2022. In the first stage of this research, we managed to get the opinions of over 500 refugees with a focus on their needs, concerns, plans, and expectations. Collected data also allowed a reconstruction of social-demographic profiles of fleeing Ukrainian refugees. The preliminary outcomes are presented in the report

Confidence of UK Ophthalmology Registrars in Managing Posterior Capsular Rupture: Results from a National Trainee Survey

Introduction: To establish the level of confidence amongst UK ophthalmology specialist registrars (residents) in managing posterior capsule rupture (PCR) during cataract surgery. / Methods: An online nine-item questionnaire was distributed to all registrars, recruited nationwide via regional representatives. Data collected included stage of training, number of completed cataract operations, cumulative PCR rate, number of PCRs independently managed, understanding of vitrectomy settings and fluidic parameters and access to simulation. Respondents self-evaluated their confidence in managing PCR with vitreous loss. / Results: Complete responses were obtained from 248 registrars (35% response rate). Mean number of phacoemulsification procedures performed was 386. For senior registrars (OST 6–7), 35 out of 70 (50%) felt confident to manage PCR independently and 55 out of 70 (78.6%) were either quite confident or very confident at deciding when to implant an intraocular lens during PCR management. Lower confidence levels were noted for junior trainees (OST 1–2). Over 65% of survey respondents had access to relevant simulation. / Conclusions: Our results represent the largest UK survey analysing the confidence of PCR management amongst registrars. Confidence improves with duration of training and increased exposure to management of PCR. However, 50% of senior registrars still lacked confidence to independently manage PCR and vitreous loss. A specific competency-based framework, potentially using a simulator or simulating a PCR event, incorporated into the curriculum may be desirable

X-ray spectral and flux variability of the microquasar GRS 1758-258 on timescales from weeks to years

We present the spectral and timing evolution of the persistent black hole X-ray binary GRS 1758-258 based on almost 12 years of observations using the Rossi X-ray Timing Explorer Proportional Counter Array. While the source was predominantly found in the hard state during this time, it entered the thermally dominated soft state seven times. In the soft state GRS 1758-258 shows a strong decline in flux above 3 keV rather than the pivoting flux around 10 keV more commonly shown by black hole transients. In its 3-20 keV hardness intensity diagram, GRS 1758-258 shows a hysteresis of hard and soft state fluxes typical for transient sources in outburst. The RXTE-PCA and RXTE-ASM long-term light curves do not show any orbital modulations in the range of 2 to 30 d. However, in the dynamic power spectra significant peaks drift between 18.47d and 18.04d for the PCA data, while less significant signatures between 19d and 20d are seen for the ASM data as well as for the Swift/BAT data. We discuss different models for the hysteresis behavior during state transitions as well as possibilities for the origin of the long term variation in the context of a warped accretion disk.Comment: 12 pages, 13 figures, accepted by Astronomy & Astrophysic

An integrated clinical program and crowdsourcing strategy for genomic sequencing and Mendelian disease gene discovery.

Despite major progress in defining the genetic basis of Mendelian disorders, the molecular etiology of many cases remains unknown. Patients with these undiagnosed disorders often have complex presentations and require treatment by multiple health care specialists. Here, we describe an integrated clinical diagnostic and research program using whole-exome and whole-genome sequencing (WES/WGS) for Mendelian disease gene discovery. This program employs specific case ascertainment parameters, a WES/WGS computational analysis pipeline that is optimized for Mendelian disease gene discovery with variant callers tuned to specific inheritance modes, an interdisciplinary crowdsourcing strategy for genomic sequence analysis, matchmaking for additional cases, and integration of the findings regarding gene causality with the clinical management plan. The interdisciplinary gene discovery team includes clinical, computational, and experimental biomedical specialists who interact to identify the genetic etiology of the disease, and when so warranted, to devise improved or novel treatments for affected patients. This program effectively integrates the clinical and research missions of an academic medical center and affords both diagnostic and therapeutic options for patients suffering from genetic disease. It may therefore be germane to other academic medical institutions engaged in implementing genomic medicine programs

A Hard X-Ray Power-Law Spectral Cutoff in Centaurus X-4

The low-mass X-ray binary Cen X-4 is the brightest and closest (<1.2 kpc) quiescent neutron star transient. Previous 0.5-10 keV X-ray observations of Cen X-4 in quiescence identified two spectral components: soft thermal emission from the neutron star atmosphere and a hard power-law tail of unknown origin. We report here on a simultaneous observation of Cen X-4 with NuSTAR (3-79 keV) and XMM-Newton (0.3-10 keV) in 2013 January, providing the first sensitive hard X-ray spectrum of a quiescent neutron star transient. The 0.3-79 keV luminosity was 1.1 x 10^(33) erg/s (for D=1kpc), with around 60 percent in the thermal component. We clearly detect a cutoff of the hard spectral tail above 10 keV, the first time such a feature has been detected in this source class. We show that thermal Comptonization and synchrotron shock origins for the hard X-ray emission are ruled out on physical grounds. However, the hard X-ray spectrum is well fit by a thermal bremsstrahlung model with an 18 keV electron temperature, which can be understood as arising either in a hot layer above the neutron star atmosphere or in a radiatively-inefficient accretion flow (RIAF). The power-law cutoff energy may be set by the degree of Compton cooling of the bremsstrahlung electrons by thermal seed photons from the neutron star surface. Lower thermal luminosities should lead to higher (possibly undetectable) cutoff energies. We compare Cen~X-4's behavior with PSR J1023+0038, IGR J18245-2452, and XSS J12270-4859, which have shown transitions between LMXB and radio pulsar modes at a similar X-ray luminosity.Comment: 16 pages, 8 figures. Accepted for publication in ApJ. Sections 4 and 5 substantially revise

Whole brain radiotherapy (WBRT) after local treatment of brain metastases in melanoma patients: Statistical Analysis Plan

Background: The WBRTMel trial is a multinational, open-label, phase III randomised controlled trial comparing whole brain radiotherapy (WBRT) to observation following local treatment of one to three melanoma brain metastases with surgery and/or stereotactic irradiation. The primary trial endpoint was to determine the effect of adding WBRT to local treatment on distant intracranial control, and the secondary endpoints were neurocognitive function, quality of life (QoL), performance status, overall survival, death from intracranial causes, death from melanoma and cost-effectiveness. Objective: The objective of this update is to outline and publish the pre-determined statistical analysis plan (SAP) before the database lock and the start of analysis. Methods: The SAP describes basic analysis principles, methods for dealing with a range of commonly encountered data analysis issues and the specific statistical procedures for analysing efficacy and safety outcomes. The SAP was approved after closure of recruitment and before completion of patient follow-up. It outlines the planned primary analyses and a range of subgroup and sensitivity analyses regarding the clinical and QoL outcomes. Health economic outcomes are not included in this plan but will be analysed separately. The SAP will be adhered to for the final data analysis of this trial to avoid analysis bias arising from knowledge of the data. Results: The resulting SAP is consistent with best practice and will allow open and transparent reporting. Conclusion: We have developed a SAP for the WBRTMel trial which will be followed to ensure high-quality standards of internal validity to minimise analysis bias

Rescue of skeletal muscle α-actin–null mice by cardiac (fetal) α-actin

Skeletal muscle α-actin (ACTA1) is the major actin in postnatal skeletal muscle. Mutations of ACTA1 cause mostly fatal congenital myopathies. Cardiac α-actin (ACTC) is the major striated actin in adult heart and fetal skeletal muscle. It is unknown why ACTC and ACTA1 expression switch during development. We investigated whether ACTC can replace ACTA1 in postnatal skeletal muscle. Two ACTC transgenic mouse lines were crossed with Acta1 knockout mice (which all die by 9 d after birth). Offspring resulting from the cross with the high expressing line survive to old age, and their skeletal muscles show no gross pathological features. The mice are not impaired on grip strength, rotarod, or locomotor activity. These findings indicate that ACTC is sufficiently similar to ACTA1 to produce adequate function in postnatal skeletal muscle. This raises the prospect that ACTC reactivation might provide a therapy for ACTA1 diseases. In addition, the mouse model will allow analysis of the precise functional differences between ACTA1 and ACTC