Consistency of post-Newtonian waveforms with numerical relativity

General relativity predicts the gravitational wave signatures of coalescing binary black holes. Explicit waveform predictions for such systems, required for optimal analysis of observational data, have so far been achieved using the post-Newtonian (PN) approximation. The quality of this treatment is unclear, however, for the important late-inspiral portion. We derive late-inspiral waveforms via a complementary approach, direct numerical simulation of Einstein's equations. We compare waveform phasing from simulations of the last $\sim 14$ cycles of gravitational radiation from equal-mass, nonspinning black holes with the corresponding 2.5PN, 3PN, and 3.5PN orbital phasing. We find phasing agreement consistent with internal error estimates based on either approach, suggesting that PN waveforms for this system are effective until the last orbit prior to final merger.Comment: Replaced with published version -- one figure removed, text and other figures updated for clarity of discussio

Examining the measurement equivalence of the Conditional Reasoning Test for Aggression across U.S. and Croatian samples

The Conditional Reasoning Test for Aggression (CRT-A; James et al., 2005) is based on the ideas that aggressive individuals use motive-based cognitive biases to see their behavior as reasonable and that those biases can be measured with specially designed inductive reasoning tasks. The test has shown promising psychometric characteristics for U. S. samples but has not been validated in other cultural contexts. In our study, we examined whether the items from the CRT-A were invariant across culture by testing whether these items displayed differential item functioning (DIF) across Croatian (N=530) and U.S. (N=1479) samples. The Lord's Chi Square (Lord, 1980), the Raju UA index (Raju, 1988), the Mantel-Haenszel procedure (Mantel & Haenszel, 1959), and the logistic regression procedures (Swaminathan & Rogers, 1990) revealed that DIF was pervasive. Although an implicit measure of personality, the CRT-A seems susceptible to differential item functioning in another culture

Toward faithful templates for non-spinning binary black holes using the effective-one-body approach

We present an accurate approximation of the full gravitational radiation waveforms generated in the merger of non-eccentric systems of two non-spinning black holes. Utilizing information from recent numerical relativity simulations and the natural flexibility of the effective-one-body (EOB) model, we extend the latter so that it can successfully match the numerical relativity waveforms during the last stages of inspiral, merger and ringdown. By ``successfully'' here, we mean with phase differences < 8% of a gravitational-wave cycle accumulated by the end of the ringdown phase, maximizing only over time of arrival and initial phase. We obtain this result by simply adding a 4-post-Newtonian order correction in the EOB radial potential and determining the (constant) coefficient by imposing high-matching performances with numerical waveforms of mass ratios m1/m2 = 1, 3/2, 2 and 4, m1 and m2 being the individual black-hole masses. The final black-hole mass and spin predicted by the numerical simulations are used to determine the ringdown frequency and decay time of three quasi-normal-mode damped sinusoids that are attached to the EOB inspiral-(plunge) waveform at the EOB light-ring. The EOB waveforms might be tested and further improved in the future by comparison with extremely long and accurate inspiral numerical-relativity waveforms. They may already be employed for coherent searches and parameter estimation of gravitational waves emitted by non-spinning coalescing binary black holes with ground-based laser-interferometer detectors.Comment: 15 pages, 9 figure

Binary black hole late inspiral: Simulations for gravitational wave observations

Coalescing binary black hole mergers are expected to be the strongest gravitational wave sources for ground-based interferometers, such as the LIGO, VIRGO, and GEO600, as well as the space-based interferometer LISA. Until recently it has been impossible to reliably derive the predictions of General Relativity for the final merger stage, which takes place in the strong-field regime. Recent progress in numerical relativity simulations is, however, revolutionizing our understanding of these systems. We examine here the specific case of merging equal-mass Schwarzschild black holes in detail, presenting new simulations in which the black holes start in the late inspiral stage on orbits with very low eccentricity and evolve for ~1200M through ~7 orbits before merging. We study the accuracy and consistency of our simulations and the resulting gravitational waveforms, which encompass ~14 cycles before merger, and highlight the importance of using frequency (rather than time) to set the physical reference when comparing models. Matching our results to PN calculations for the earlier parts of the inspiral provides a combined waveform with less than half a cycle of accumulated phase error through the entire coalescence. Using this waveform, we calculate signal-to-noise ratios (SNRs) for iLIGO, adLIGO, and LISA, highlighting the contributions from the late-inspiral and merger-ringdown parts of the waveform which can now be simulated numerically. Contour plots of SNR as a function of z and M show that adLIGO can achieve SNR >~ 10 for some intermediate-mass binary black holes (IMBBHs) out to z ~ 1, and that LISA can see massive binary black holes (MBBHs) in the range 3x10^4 100 out to the earliest epochs of structure formation at z > 15.Comment: 17 pages, 20 figures. Final published versio

Micromanipulation of InP lasers with optoelectronic tweezers for integration on a photonic platform

The integration of light sources on a photonic platform is a key aspect of the fabrication of self-contained photonic circuits with a small footprint that does not have a definitive solution yet. Several approaches are being actively researched for this purpose. In this work we propose optoelectronic tweezers for the manipulation and integration of light sources on a photonic platform and report the positional and angular accuracy of the micromanipulation of standard Fabry-Pérot InP semiconductor laser die. These lasers are over three orders of magnitude bigger in volume than any previously assembled with optofluidic techniques and the fact that they are industry standard lasers makes them significantly more useful than previously assembled microdisk lasers. We measure the accuracy to be 2.5 ± 1.4 µm and 1.4 ± 0.4° and conclude that optoelectronic tweezers are a promising technique for the micromanipulation and integration of optoelectronic components in general and semiconductor lasers in particular

Modeling kicks from the merger of generic black-hole binaries

Recent numerical relativistic results demonstrate that the merger of comparable-mass spinning black holes has a maximum ``recoil kick'' of up to \sim 4000 \kms. However the scaling of these recoil velocities with mass ratio is poorly understood. We present new runs showing that the maximum possible kick perpendicular to the orbital plane does not scale as $\sim\eta^2$ (where $\eta$ is the symmetric mass ratio), as previously proposed, but is more consistent with $\sim\eta^3$, at least for systems with low orbital precession. We discuss the effect of this dependence on galactic ejection scenarios and retention of intermediate-mass black holes in globular clusters.Comment: 5 pages, 1 figure, 3 tables. Version published in Astrophys. J. Let

Medication adherence in patients with myotonic dystrophy and facioscapulohumeral muscular dystrophy

Myotonic dystrophy (DM) and facioscapulohumeral muscular dystrophy (FSHD) are the two most common adult muscular dystrophies and have progressive and often disabling manifestations. Higher levels of medication adherence lead to better health outcomes, especially important to patients with DM and FSHD because of their multisystem manifestations and complexity of care. However, medication adherence has not previously been studied in a large cohort of DM type 1 (DM1), DM type 2 (DM2), and FSHD patients. The purpose of our study was to survey medication adherence and disease manifestations in patients enrolled in the NIH-supported National DM and FSHD Registry. The study was completed by 110 DM1, 49 DM2, and 193 FSHD patients. Notable comorbidities were hypertension in FSHD (44 %) and DM2 (37 %), gastroesophageal reflux disease in DM1 (24 %) and DM2 (31 %) and arrhythmias (29 %) and thyroid disease (20 %) in DM1. Each group reported high levels of adherence based on regimen complexity, medication costs, health literacy, side effect profile, and their beliefs about treatment. Only dysphagia in DM1 was reported to significantly impact medication adherence. Approximately 35 % of study patients reported polypharmacy (taking 6 or more medications). Of the patients with polypharmacy, the DM1 cohort was significantly younger (mean 55.0 years) compared to DM2 (59.0 years) and FSHD (63.2 years), and had shorter disease duration (mean 26 years) compared to FSHD (26.8 years) and DM2 (34.8 years). Future research is needed to assess techniques to ease pill swallowing in DM1 and to monitor polypharmacy and potential drug interactions in DM and FSHD

Anatomy of the binary black hole recoil: A multipolar analysis

We present a multipolar analysis of the gravitational recoil computed in recent numerical simulations of binary black hole (BH) coalescence, for both unequal masses and non-zero, non-precessing spins. We show that multipole moments up to and including l=4 are sufficient to accurately reproduce the final recoil velocity (within ~2%) and that only a few dominant modes contribute significantly to it (within ~5%). We describe how the relative amplitudes, and more importantly, the relative phases, of these few modes control the way in which the recoil builds up throughout the inspiral, merger, and ringdown phases. We also find that the numerical results can be reproduced by an ``effective Newtonian'' formula for the multipole moments obtained by replacing the radial separation in the Newtonian formulae with an effective radius computed from the numerical data. Beyond the merger, the numerical results are reproduced by a superposition of three Kerr quasi-normal modes (QNMs). Analytic formulae, obtained by expressing the multipole moments in terms of the fundamental QNMs of a Kerr BH, are able to explain the onset and amount of ``anti-kick'' for each of the simulations. Lastly, we apply this multipolar analysis to help explain the remarkable difference between the amplitudes of planar and non-planar kicks for equal-mass spinning black holes.Comment: 28 pages, 20 figures, submitted to PRD; v2: minor revisions from referee repor