The Final Merger of Black-Hole Binaries

Recent breakthroughs in the field of numerical relativity have led to dramatic progress in understanding the predictions of General Relativity for the dynamical interactions of two black holes in the regime of very strong gravitational fields. Such black-hole binaries are important astrophysical systems and are a key target of current and developing gravitational-wave detectors. The waveform signature of strong gravitational radiation emitted as the black holes fall together and merge provides a clear observable record of the process. After decades of slow progress, these mergers and the gravitational-wave signals they generate can now be routinely calculated using the methods of numerical relativity. We review recent advances in understanding the predicted physics of events and the consequent radiation, and discuss some of the impacts this new knowledge is having in various areas of astrophysics.Comment: 57 pages; 9 figures. Updated references & fixed typos. Published version is at http://www.annualreviews.org/doi/abs/10.1146/annurev.nucl.010909.08324

Black-hole binaries, gravitational waves, and numerical relativity

Understanding the predictions of general relativity for the dynamical interactions of two black holes has been a long-standing unsolved problem in theoretical physics. Black-hole mergers are monumental astrophysical events, releasing tremendous amounts of energy in the form of gravitational radiation, and are key sources for both ground- and space-based gravitational-wave detectors. The black-hole merger dynamics and the resulting gravitational waveforms can only be calculated through numerical simulations of Einstein's equations of general relativity. For many years, numerical relativists attempting to model these mergers encountered a host of problems, causing their codes to crash after just a fraction of a binary orbit could be simulated. Recently, however, a series of dramatic advances in numerical relativity has allowed stable, robust black-hole merger simulations. This remarkable progress in the rapidly maturing field of numerical relativity, and the new understanding of black-hole binary dynamics that is emerging is chronicled. Important applications of these fundamental physics results to astrophysics, to gravitational-wave astronomy, and in other areas are also discussed.Comment: 54 pages, 42 figures. Some typos corrected & references updated. Essentially final published versio

Spending All Your Money on Me: Influencer Marketing’s Impact on Engagement

Influencer marketing has been around for a few years and is rapidly approaching a $15 billion industry by 2022. In its nascency, the research is limited which investigates factors that substantiate the growth and popularity of advertising tools. In this study, we propose and explicate how two different types of influencers, namely mega- and macro-influencers, impact their audience\u27s engagement with sponsored posts. Utilizing secondary data from more than 650 Instagram posts, our results suggest mega-influencers are able to mitigate the negative effect of utilizing various post attributes, including meta-tags and product prominence

development of a new reference standard for microarray experiments

Often microarray studies require a reference to indirectly compare the samples under observation. References based on pooled RNA from different cell lines have already been described (here referred to as RNA-R), but they usually do not exhaustively represent the set of genes printed on a chip, thus requiring many adjustments during the analyses. A reference could also be generated in vitro transcribing the collection of cDNA clones printed on the microarray in use (here referred to as T3-R). Here we describe an alternative and simpler PCR-based methodology to construct a similar reference (Chip-R), and we extensively test and compare it to both RNA-R and T3-R. The use of both Chip-R and T3-R dramatically increases the number of signals on the slides and gives more reproducible results than RNA-R. Each reference preparation is also evaluated in a simple microarray experiment comparing two different RNA populations. Our results show that the introduction of a reference always interferes with the analysis. Indeed, the direct comparison is able to identify more up- or down-regulated genes than any reference-mediated analysis. However, if a reference has to be used, Chip-R and T3-R are able to guarantee more reliable results than RNA-R

General linear-optical quantum state generation scheme: Applications to maximally path-entangled states

We introduce schemes for linear-optical quantum state generation. A quantum state generator is a device that prepares a desired quantum state using product inputs from photon sources, linear-optical networks, and postselection using photon counters. We show that this device can be concisely described in terms of polynomial equations and unitary constraints. We illustrate the power of this language by applying the Grobner-basis technique along with the notion of vacuum extensions to solve the problem of how to construct a quantum state generator analytically for any desired state, and use methods of convex optimization to identify bounds to success probabilities. In particular, we disprove a conjecture concerning the preparation of the maximally path-entangled |n,0)+|0,n) (NOON) state by providing a counterexample using these methods, and we derive a new upper bound on the resources required for NOON-state generation.Comment: 5 pages, 2 figure

The Mare Reproductive Loss Syndrome and the Eastern Tent Caterpillar II: A Toxicokinetic/Clinical Evaluation and a Proposed Pathogenesis: Septic Penetrating Setae

Reviewing the mare reproductive loss syndrome (MRLS), it is proposed that the fundamental mechanism of this syndrome, which includes early fetal loss, late fetal loss, uveitis, pericarditis, and encephalitis, is tissue penetration by septic barbed setal fragments (septic penetrating setae) from Eastern tent caterpillars (Malacosoma americanum). Once ingested, these barbed setal fragments migrate through moving tissues, followed by rapid hematogenous spread of bacteria, bacterial emboli, and/or septic fragments of setae (septic penetrating setal emboli), collectively referred to as septic materials. Pathogenic bacteria, therefore, enter the horse as hitchhikers on or in the caterpillar setal fragments, and MRLS is caused by 1) the barbed setal fragments’ ability to penetrate moving tissues, including blood vessels, releasing septic materials, which rapidly distribute hematogenously; 2) the high sensitivity of the pregnant mare to bacteria from such septic materials introduced into the uterus, fetal membranes, or fetal fluids; 3) the unusually broad spectrum of bacterial pathogens carried on or in the setal fragments; and 4) the less effective antibacterial responses in certain susceptible extracellular fluids (e.g., fetal, ocular, pericardial, and cerebrospinal fluids). The driving force for MRLS pathology, including abortions, is septic material- induced bacterial proliferation, which provides a critical amplification step, enabling approximately 1-gram caterpillars to rapidly (32 hours) cause abortions in 680-kg (1,500- lb) mares. Calculations based on the unique eye data suggest that the actual number of distributing effective septic material quanta in field cases may be small—on the order of 10/horse/day—accounting for the lack of systemic clinical signs in affected horses. Therefore, it is proposed that MRLS starts with ingestion of Eastern tent caterpillars, followed by barbed setal fragments randomly penetrating intestinal tissues, including thinwalled venules and other blood vessels, with release of septic material that distributes hematogenously to all points in the body. Identification of abortigenic activity with the integument of the caterpillar and recent findings of large numbers of granulomatous lesions containing setal fragments in the intestines of pigs and rats directly supports the septic penetrating setal portion of the hypothesis. Analysis of the clinical syndromes and a toxicokinetic/ statistical analysis of MRLS suggest that setally-mediated introduction of septic material into blood vessels and other tissues may be key to understanding the very unusual toxicokinetics and pathogenesis of the unique group of syndromes that constitute MRLS. Like MRLS itself, this hypothesis is unique. The septic penetrating setal emboli portion is without precedent, is based on the unique clinical characteristics of MRLS, and appears well supported by ongoing experimental approaches

Gravitational Radiation Characteristics of Nonspinning Black-Hole Binaries

We present a detailed descriptive analysis of the gravitational radiation from binary mergers of non-spinning black holes, based on numerical relativity simulations of systems varying from equal-mass to a 6:1 mass ratio. Our analysis covers amplitude and phase characteristics of the radiation, suggesting a unified picture of the waveforms' dominant features in terms of an implicit rotating source, applying uniformly to the full wavetrain, from inspiral through ringdown. We construct a model of the late-stage frequency evolution that fits the l = m modes, and identify late-time relationships between waveform frequency and amplitude. These relationships allow us to construct a predictive model for the late-time waveforms, an alternative to the common practice of modelling by a sum of quasinormal mode overtones. We demonstrate an application of this in a new effective-one-body-based analytic waveform model

Accurate Waveforms for Non-spinning Binary Black Holes using the Effective-one-body Approach

Using numerical relativity as guidance 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 of non-spinning binary black holes during the last stages of inspiral, merger and ringdown. Here, by successfully, we mean with phase differences < or approx. 8% of a gravitational-wave cycle accumulated until the end of the ringdown 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 = 1,2/3,1/2 and = 1/4, 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 light-ring. The accurate EOB waveforms may be employed for coherent searches of gravitational waves emitted by non-spinning coalescing binary black holes with ground-based laser-interferometer detectors

Performance of the Spacecraft Propulsion Research Facility During Altitude Firing Tests of the Delta 3 Upper Stage

The Spacecraft Propulsion Research Facility at the NASA Lewis Research Center's Plum Brook Station was reactivated in order to conduct flight simulation ground tests of the Delta 3 cryogenic upper stage. The tests were a cooperative effort between The Boeing Company, Pratt and Whitney, and NASA. They included demonstration of tanking and detanking of liquid hydrogen, liquid oxygen and helium pressurant gas as well as 12 engine firings simulating first, second, and third burns at altitude conditions. A key to the success of these tests was the performance of the primary facility systems and their interfaces with the vehicle. These systems included the structural support of the vehicle, propellant supplies, data acquisition, facility control systems, and the altitude exhaust system. While the facility connections to the vehicle umbilical panel simulated the performance of the launch pad systems, additional purge and electrical connections were also required which were unique to ground testing of the vehicle. The altitude exhaust system permitted an approximate simulation of the boost-phase pressure profile by rapidly pumping the test chamber from 13 psia to 0.5 psia as well as maintaining altitude conditions during extended steady-state firings. The performance of the steam driven ejector exhaust system has been correlated with variations in cooling water temperature during these tests. This correlation and comparisons to limited data available from Centaur tests conducted in the facility from 1969-1971 provided insight into optimizing the operation of the exhaust system for future tests. Overall, the facility proved to be robust and flexible for vehicle space simulation engine firings and enabled all test objectives to be successfully completed within the planned schedule