General-relativistic precession in a black-hole binary.

The general-relativistic phenomenon of spin-induced orbital precession has not yet been observed in strong-field gravity. Gravitational-wave observations of binary black holes (BBHs) are prime candidates, as we expect the astrophysical binary population to contain precessing binaries1,2. Imprints of precession have been investigated in several signals3-5, but no definitive identification of orbital precession has been reported in any of the 84 BBH observations so far5-7 by the Advanced LIGO and Virgo detectors8,9. Here we report the measurement of strong-field precession in the LIGO-Virgo-Kagra gravitational-wave signal GW200129. The binary's orbit precesses at a rate ten orders of magnitude faster than previous weak-field measurements from binary pulsars10-13. We also find that the primary black hole is probably highly spinning. According to current binary population estimates, a GW200129-like signal is extremely unlikely, and therefore presents a direct challenge to many current binary-formation models.

Bekenstein-Hod Universal Bound on Information Emission Rate Is Obeyed by LIGO-Virgo Binary Black Hole Remnants.

Causality and the generalized laws of black hole thermodynamics imply a bound, known as the Bekenstein-Hod universal bound, on the information emission rate of a perturbed system. Using a time-domain ringdown analysis, we investigate whether remnant black holes produced by the coalescences observed by Advanced LIGO and Advanced Virgo obey this bound. We find that the bound is verified by the astrophysical black hole population with 94% probability, providing a first confirmation of the Bekenstein-Hod bound from black hole systems.

Measuring Intermediate-Mass Black-Hole Binaries with Advanced Gravitational Wave Detectors.

We perform a systematic study to explore the accuracy with which the parameters of intermediate-mass black-hole binary systems can be measured from their gravitational wave (GW) signatures using second-generation GW detectors. We make use of the most recent reduced-order models containing inspiral, merger, and ringdown signals of aligned-spin effective-one-body waveforms to significantly speed up the calculations. We explore the phenomenology of the measurement accuracies for binaries with total masses between 50M(⊙) and 500M(⊙) and mass ratios between 0.1 and 1. We find that (i) at total masses below ∼200M(⊙), where the signal-to-noise ratio is dominated by the inspiral portion of the signal, the chirp mass parameter can be accurately measured; (ii) at higher masses, the information content is dominated by the ringdown, and total mass is measured more accurately; (iii) the mass of the lower-mass companion is poorly estimated, especially at high total mass and more extreme mass ratios; and (iv) spin cannot be accurately measured for our injection set with nonspinning components. Most importantly, we find that for binaries with nonspinning components at all values of the mass ratio in the considered range and at a network signal-to-noise ratio of 15, analyzed with spin-aligned templates, the presence of an intermediate-mass black hole with mass >100M(⊙) can be confirmed with 95% confidence in any binary that includes a component with a mass of 130M(⊙) or greater.

Gravitational waves: search results, data analysis and parameter estimation: Amaldi 10 Parallel session C2.

The Amaldi 10 Parallel Session C2 on gravitational wave (GW) search results, data analysis and parameter estimation included three lively sessions of lectures by 13 presenters, and 34 posters. The talks and posters covered a huge range of material, including results and analysis techniques for ground-based GW detectors, targeting anticipated signals from different astrophysical sources: compact binary inspiral, merger and ringdown; GW bursts from intermediate mass binary black hole mergers, cosmic string cusps, core-collapse supernovae, and other unmodeled sources; continuous waves from spinning neutron stars; and a stochastic GW background. There was considerable emphasis on Bayesian techniques for estimating the parameters of coalescing compact binary systems from the gravitational waveforms extracted from the data from the advanced detector network. This included methods to distinguish deviations of the signals from what is expected in the context of General Relativity.

Factors affecting eGFR 5-year post-deceased donor renal transplant: analysis and predictive model.

AIM: Long-term survival of renal allografts has improved over the last 20 years. However, less is known about current expectations for long-term allograft function as determined by estimated glomerular filtration rate (eGFR). The aim of this study was to investigate factors which affect graft function at 5 years' post-renal transplantation. The statistically significant factors were then used to construct a predictive model for expected eGFR at five years' post-transplant. METHODS: We retrospectively reviewed all adult patients who received a renal transplant in the Republic of Ireland between 1990 and 2004. Data collected included era of transplantation (1990-1994, 1995-1999, 2000-2004), donor and recipient age and gender, number of human leucocyte antigen mismatches, cold ischemia time (CIT), number of prior renal transplants, immunosuppressive regimen used and acute rejection episodes. Estimated GFR was calculated at 5 years after transplantation from patient data using the Modified Diet in Renal Disease (MDRD) equation. Consecutive sampling was used to divide the study population into two equal unbiased groups of 489 patients. The first group (derivation cohort) was used to construct a predictive model for eGFR five years' post-transplantation, the second (validation cohort) to test this model. RESULTS: Nine hundred and seventy eight patients were analyzed. The median age at transplantation was 43 years (range 18-78) and 620 (63.4%) were male. One hundred and seventy five patients (17.9%) had received a prior renal transplant. Improved eGFR at five years' post-transplantation was associated with tacrolimus-based combination immunosuppression, younger donor age, male recipient, absence of cytomegalovirus disease and absence of acute rejection episodes as independently significant factors (p < 0.05). The predictive model developed using these factors showed good correlation between predicted and actual median eGFR at five years. The model explained 20% of eGFR variability. The validation model findings were consistent with the derivation model (21% variability of eGFR explained by model using same covariates on new data). CONCLUSION: The predictive model we have developed shows good correlation between predicted and actual median eGFR at five years' post-transplant. Applications of this model include comparison of current and future therapy options such as new immunosuppressive regimens.

Measuring the spin of black holes in binary systems using gravitational waves.

Compact binary coalescences are the most promising sources of gravitational waves (GWs) for ground-based detectors. Binary systems containing one or two spinning black holes are particularly interesting due to spin-orbit (and eventual spin-spin) interactions and the opportunity of measuring spins directly through GW observations. In this Letter, we analyze simulated signals emitted by spinning binaries with several values of masses, spins, orientations, and signal-to-noise ratios, as detected by an advanced LIGO-Virgo network. We find that for moderate or high signal-to-noise ratio the spin magnitudes can be estimated with errors of a few percent (5%-30%) for neutron star-black hole (black hole-black hole) systems. Spins' tilt angle can be estimated with errors of 0.04 rad in the best cases, but typical values will be above 0.1 rad. Errors will be larger for signals barely above the threshold for detection. The difference in the azimuth angles of the spins, which may be used to check if spins are locked into resonant configurations, cannot be constrained. We observe that the best performances are obtained when the line of sight is perpendicular to the system's total angular momentum and that a sudden change of behavior occurs when a system is observed from angles such that the plane of the orbit can be seen both from above and below during the time the signal is in band. This study suggests that direct measurement of black hole spin by means of GWs can be as precise as what can be obtained from x-ray binaries.

Assessment of rotational instability with disruption of the accessory collateral ligament of the thumb MCP joint: a biomechanical study.

OBJECTIVES: The objective of this paper was to biomechanically investigate rotational stability of the thumb after ulnar collateral ligament (UCL) and accessory collateral ligament (ACL) disruption and repair at the metacarpal joint of the thumb. METHODS: Twelve fresh frozen adult cadaveric thumbs were used. The torsion test was performed under constant rotation of 1/s through 30 arc of metacarpal phalangeal (MCP) joint. The torsional resistance was determined for four categories: first no intervention of the UCL structures (control), next with the proper UCL cut at the distal insertion, then with the additional ACL ligament cut, and lastly with the repair of only the proper UCL. The decrease on the amount of torsional rigidity for each of the last three categories was determined and compared. Each thumb was used as its own control. Significance of the differences in each test categories was statistically determined. RESULTS: After the proper UCL was cut, the torsional rigidity of the MCP joint was reduced 35.18 +/- 17.56% (p < 0.001). When, additionally, the ACL was cut, the torsional rigidity of the MCP joint was further reduced to 49.34 +/- 16.82% (P < 0.001). After repair of only the proper UCL, the torsional rigidity of the MCP joint improved, but still showed a considerable reduction from controls. The amount of reduction was not consistent among specimens and was 13.52 +/- 16.40%. CONCLUSIONS: The ACL ligament is a contributor of rotary stability as well as a provider of lateral stability. Leaving the ruptured ACL unrepaired causes some residual rotating instability and that may lead to future rotational instability of the MCP joint.

Two potential causes of EPL rupture after distal radius volar plate fixation.

Rupture of the extensor pollicis longus tendon can occur after volar plate fixation of dorsally comminuted distal radius fractures. We attempted to identify the etiology of extensor pollicis longus tendon injury after volar plate fixation of the distal radius and potential solutions to this problem. After describing two case reports, we examine six cadaveric specimens and retrospectively review 10 selected patients to evaluate possible technique refinements to minimize damage to the extensor pollicis longus tendon during volar plating of the distal radius. We identify specific screw holes in three commercially available volar distal radius plates that direct the drill bit or prominent screw tips into the third extensor compartment. In addition, after reduction and plate fixation, bone fragments or dorsal gapping may predispose the extensor pollicis longus tendon to injury. We recommend either using shorter screw lengths or leaving the implicated plate holes unfilled. In addition, we suggest consideration of an open assessment of the third extensor compartment, if indicated, as performed through a small dorsal incision ulnar to Lister's tubercle.