The low or retrograde spin of the first extragalactic microquasar: implications for Blandford-Znajek powering of jets

Transitions to high mass accretion rates in black hole X-ray binaries are associated with the ejection of powerful, relativistically moving jets. The mechanism that powers such events is thought to be linked to tapping of the angular momentum (spin) of the black hole, the rate of accretion through the disc or some combination of the two. We can attempt to discriminate between these different possibilities by comparing proxies for jet power with spin estimates. Because of the small number of sources that reach Eddington mass accretion rates and have therefore been suggested to act as ‘standard candles’, there has been much recent debate as to whether a significant correlation exists between jet power and black hole spin. We perform continuum fitting to the high-quality, disc-dominated XMM–Newton spectra of the extragalactic microquasar discovered in M31. Assuming prograde spin, we find that for sensible constraints the spin is always very low (a* ≤ 0.15 at 3s).When combined with a proxy for jet power derived from the maximum 5 GHz radio luminosity during a bright flaring event, we find that the source sits well above the previously reported, rising correlation that would indicate that spin tapping is the dominant mechanism for powering the jets, i.e. it is too ‘radio loud’ for such a low spin. The notable exceptions require the inclination to be improbably small or the jet to be very fast. We investigate whether this could be a byproduct of selecting prograde-only spin, finding that the data statistically favour a substantially retrograde spin for the same constraints (a* ≤-0.17 at 3s). Although theoretically improbable, this remarkable finding could be confirmation that retrograde spin can power such jets via spin-tapping, as has been suggested for certain radio quasars. In either case this work demonstrates the value of studying local extragalactic microquasars as a means to better understand the physics of jet launching

Aging of a Polymer Core Composite Conductor Under Combined Ozone and Temperature Conditions

The next generation High Temperature Low Sag Polymer Core Composite Conductors (HTLS PCCC) can experience harsh in-service environments including high temperature and highly concentrated ozone. In some extreme cases, it is possible that the conductors will experience temperatures of up to 180°C and ozone concentrations as high as 1% (10,000 ppm). Therefore, the primary goal of this research was to determine the most damaging aging conditions which could negatively affect the in-service life of the conductors. This included characterizing the aging in ozone and at high temperature of the HTLS PCCC hybrid composite rods and neat resin. It was found that exposure to 1% ozone for up to three months at room temperature did not negatively affect the flexural performance of either the neat resin epoxy, or the hybrid composite rods. When aged up to a year at 140°C no detrimental effect on flexural performance of the composite was observed, as opposed to aging at 180°C, which had a very negative effect on the properties. The aging of the epoxy at 140°C was driven almost entirely by temperature and the effect of 1% ozone, even at that temperature, was insignificant for aging times up to ninety days. A finite element model was developed and showed the residual stresses developed after aging at 140°C for a year were minimal, but for temperatures higher than 160°C were substantial. From this it was determined that the aging was thermally driven, and atmospheric high temperatures were the most damaging conditions for the PCCC conductors

Right care, right time, right place: improving outcomes for people with spinal cord injury through early access to intervention and improved access to specialised care: study protocol

Background: Traumatic spinal cord injury is a devastating condition impacting adversely on the health and wellbeing, functioning and independence, social participation and quality of life of the injured person. In Australia, there are approximately 15 new cases per million population per year; economic burden estimates suggest 2 billion dollars annually. For optimal patient outcomes expert consensus recommends expeditious transfer (“24 hours) in a Spinal Cord Injury Unit. Examining current health service and clinical intervention pathways in this Australian population-based sample, in relation to their outcomes, will provide an understanding of factors associated with patient flow, resource utilisation and cost, and patient and family quality of life. Barriers to streamlined effective early-care pathways and facilitators of optimal treatment for these patients will be identified

Global Three-Dimensional Radiation Magnetohydrodynamic Simulations of Accretion onto a Stellar Mass Black Hole at Sub- and Near-critical Accretion Rates

We present global 3D radiation magnetohydrodynamical simulations of accretion onto a 6.62 solar mass black hole with quasi-steady state accretion rates reaching 0.016 to 0.9 times the critical accretion rate, which is defined as the accretion rate to power the Eddington luminosity assuming a 10% radiative efficiency, in different runs. The simulations show no sign of thermal instability over hundreds of thermal timescales at 10 $r_{\rm g}$. The energy dissipation happens close to the mid-plane in the near-critical runs and near the disk surface in the low accretion rate run. The total radiative luminosity inside $\sim$20 $r_{\rm g}$ is about 1% to 30% the Eddington limit, with a radiative efficiency of about 6% and 3%, respectively, in the sub- and near-critical accretion regimes. In both cases, self-consistent turbulence generated by the magnetorotational instability (MRI) leads to angular momentum transfer, and the disk is supported by magnetic pressure. Outflows from the central low-density funnel with a terminal velocity of $\sim$0.1$c$ are seen only in the near-critical runs. We conclude that these magnetic pressure dominated disks are thermally stable and thicker than the $\alpha$ disk, and the effective temperature profiles are much flatter than that in the $\alpha$ disks. The magnetic pressure of these disks are comparable within an order of magnitude with the previous analytical magnetic pressure dominated disk model.Comment: 17 pages, 13 figures, 3 tables, accepted for publication in Ap

The effects of skull flattening on suchian jaw muscle evolution

Jaw muscles are key features of the vertebrate feeding apparatus. The jaw musculature is housed in the skull whose morphology reflects a compromise between multiple functions, including feeding, housing sensory structures, and defense, and the skull constrains jaw muscle geometry. Thus, jaw muscle anatomy may be suboptimally oriented for the production of bite force. Crocodylians are a group of vertebrates that generate the highest bite forces ever measured with a flat skull suited to their aquatic ambush predatory style. However, basal members of the crocodylian line (e.g., Prestosuchus) were terrestrial predators with plesiomorphically tall skulls, and thus the origin of modern crocodylians involved a substantial reorganization of the feeding apparatus and its jaw muscles. Here, we reconstruct jaw muscles across a phylogenetic range of crocodylians and fossil suchians to investigate the impact of skull flattening on muscle anatomy. We used imaging data to create 3D models of extant and fossil suchians that demonstrate the evolution of the crocodylian skull, using osteological correlates to reconstruct muscle attachment sites. We found that jaw muscle anatomy in early fossil suchians reflected the ancestral archosaur condition but experienced progressive shifts in the lineage leading to Metasuchia. In early fossil suchians, musculus adductor mandibulae posterior and musculus pterygoideus (mPT) were of comparable size, but by Metasuchia, the jaw musculature is dominated by mPT. As predicted, we found that taxa with flatter skulls have less efficient muscle orientations for the production of high bite force. This study highlights the diversity and evolution of jaw muscles in one of the great transformations in vertebrate evolution.Fil: Sellers, Kaleb C.. University of Missouri; Estados UnidosFil: Nieto, Mauro Nicolas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Centro de Investigaciones en Ciencias de la Tierra. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Centro de Investigaciones en Ciencias de la Tierra; ArgentinaFil: Degrange, Federico Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Centro de Investigaciones en Ciencias de la Tierra. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Centro de Investigaciones en Ciencias de la Tierra; ArgentinaFil: Pol, Diego. Museo Paleontológico Egidio Feruglio; ArgentinaFil: Clark, James M.. The George Washington University. Columbian College Of Arts And Sciences. Department Of Biological Sciences.; Estados UnidosFil: Middleton, Kevin M.. University of Missouri; Estados UnidosFil: Holliday, Casey M.. University of Missouri; Estados Unido

Genomic variant sharing: a position statement.

Sharing de-identified genetic variant data is essential for the practice of genomic medicine and is demonstrably beneficial to patients. Robust genetic diagnoses that inform medical management cannot be made accurately without reference to genetic test results from other patients, as well as population controls. Errors in this process can result in delayed, missed or erroneous diagnoses, leading to inappropriate or missed medical interventions for the patient and their family. The benefits of sharing individual genetic variants, and the harms of not sharing them, are numerous and well-established. Databases and mechanisms already exist to facilitate deposition and sharing of pseudonomised genetic variants, but clarity and transparency around best practice is needed to encourage widespread use, prevent inconsistencies between different communities, maximise individual privacy and ensure public trust. We therefore recommend that widespread sharing of a small number of individual genetic variants associated with limited clinical information should become standard practice in genomic medicine. Information robustly linking genetic variants with specific conditions is fundamental biological knowledge, not personal information, and therefore should not require consent to share. For additional case-level detail about individual patients or more extensive genomic information, which is often essential for clinical interpretation, it may be more appropriate to use a controlled-access model for data sharing, with the ultimate aim of making as much information as open and de-identified as possible with appropriate consent

Hysteresis and hierarchies: dynamics of disorder-driven first-order phase transformations

We use the zero-temperature random-field Ising model to study hysteretic behavior at first-order phase transitions. Sweeping the external field through zero, the model exhibits hysteresis, the return-point memory effect, and avalanche fluctuations. There is a critical value of disorder at which a jump in the magnetization (corresponding to an infinite avalanche) first occurs. We study the universal behavior at this critical point using mean-field theory, and also present preliminary results of numerical simulations in three dimensions.Comment: 12 pages plus 2 appended figures, plain TeX, CU-MSC-747

Ethical and methodological issues in engaging young people living in poverty with participatory research methods

This paper discusses the methodological and ethical issues arising from a project that focused on conducting a qualitative study using participatory techniques with children and young people living in disadvantage. The main aim of the study was to explore the impact of poverty on children and young people's access to public and private services. The paper is based on the author's perspective of the first stage of the fieldwork from the project. It discusses the ethical implications of involving children and young people in the research process, in particular issues relating to access and recruitment, the role of young people's advisory groups, use of visual data and collection of data in young people's homes. The paper also identifies some strategies for addressing the difficulties encountered in relation to each of these aspects and it considers the benefits of adopting participatory methods when conducting research with children and young people

Enhancing our conceptual understanding of state and trait self-efficacy by correlational analysis of four self-efficacy scales in people with spinal cord injury

BACKGROUND: Self-efficacy is an important determinant of adjustment following spinal cord injury. Self-efficacy is defined as the belief that one can successfully execute behavior required to produce the desired outcomes. In its original conceptualization, self-efficacy refers to the confidence that people have in their ability to accomplish specific tasks and behaviors within a specific context. Over the years these situation specific aspects have been unconfined and multiple constructs of self-efficacy have been proposed. The most common is a division in trait and state self-efficacy. Another used division that is utilized is between general, domain-specific and task-specific self-efficacy. The scientific support for these constructs is to date still unclear. The objective of this study was to enhance the understanding of the self-efficacy construct by comparing four self-efficacy scales designed to measure three aspects of self-efficacy (general versus domain-specific versus task-specific) in people with spinal cord injury. METHODS: Dutch and Australian adults with spinal cord injury (N = 140) completed four frequently used self-efficacy scales; the Moorong Self-efficacy Scale, General Self-efficacy Scale, University of Washington Self-efficacy Scale and a Self-care Self-efficacy Scale approximately 6 months after their inpatient rehabilitation. Pearson correlations examined inter-relationships between the scales. RESULTS: Hypothesized strong correlations between scales measuring similar aspects of self-efficacy were found (correlations 0.50-0.65). However, the hypothesized weak to moderate correlations between scales measuring diverging aspects of self-efficacy were only partly found (correlations 0.31-0.74), with 7 out of 12 correlations being strong instead of moderate. CONCLUSIONS: The expected distinctions between the three aspects of self-efficacy was not demonstrated. All four scales measure a common latent construct, most likely general self-efficacy aspects. Further research is necessary to find ways to improve the measurement of domain-specific and task-specific aspects of SE, so that they are sensitive enough to capture change over time, and thus enhance clinical outcomes of people with SCI as they adjust to their disability