Gravitational waves from eccentric intermediate mass binary black hole mergers

Owing to the difficulty of direct observation, mergers of intermediate-mass black hole binaries are relatively less understood compared to stellar-mass binaries; however, the gravitational waves from their last few orbits and ringdown fall in the band of ground-based detectors. Because the typical source is expected to circularize prior to entering LIGO or VIRGO's range, inspiral searches concentrate on circularized binaries. It is possible that events will be missed if there are sources with residual eccentricity. We study the variation of the signal to noise present in the dominant mode of the eccentric evolutions as a function of mass and eccentricity and also the relative contribution of the signal in the various spherical harmonic modes. The energy radiated in gravitational waves increases with eccentricity until the eccentricity becomes too high, leading to plunging trajectories, at which point the energy radiated decreases. This enhancement of the energy for initial eccentricities near the transition value translates into larger signal-to-noise ratios. Consequently despite the anticipated loss in the signal-to-noise ratio due to the use of quasi-circular detection templates, some eccentric signals potentially may be seen farther out than others

Electromagnetic Simulation and Design of a Novel Waveguide RF Wien Filter for Electric Dipole Moment Measurements of Protons and Deuterons

The conventional Wien filter is a device with orthogonal static magnetic and electric fields, often used for velocity separation of charged particles. Here we describe the electromagnetic design calculations for a novel waveguide RF Wien filter that will be employed to solely manipulate the spins of protons or deuterons at frequencies of about 0.1 to 2 MHz at the COoler SYnchrotron COSY at J\"ulich. The device will be used in a future experiment that aims at measuring the proton and deuteron electric dipole moments, which are expected to be very small. Their determination, however, would have a huge impact on our understanding of the universe.Comment: 10 pages, 10 figures, 4 table

Binary Black Hole Encounters, Gravitational Bursts and Maximum Final Spin

The spin of the final black hole in the coalescence of nonspinning black holes is determined by the ``residual'' orbital angular momentum of the binary. This residual momentum consists of the orbital angular momentum that the binary is not able to shed in the process of merging. We study the angular momentum radiated, the spin of the final black hole and the gravitational bursts in a series of orbits ranging from almost direct infall to numerous orbits before infall that exhibit multiple bursts of radiation in the merger process. We show that the final black hole gets a maximum spin parameter $a/M_h \le 0.78$, and this maximum occurs for initial orbital angular momentum $L \approx M^2_h$.Comment: Replaced with version to appear in PR

Thoracic endovascular aortic repair: impact of urgency on outcome and quality of life

Objectives: Endovascular repair of the descending thoracic aorta is a very promising technique in elective and, particularly, emergency situations. This study assessed the impact of urgency of the procedure on outcome and mid-term quality of life in surviving patients. Methods: Post hoc analysis of prospectively collected data of 58 consecutive patients (January 2001-December 2005) with surgical pathologies of the descending thoracic aorta treated by endovascular means. Six patients were excluded due to recent operations on the ascending aorta before thoracic endovascular repair. The remaining patients (n=52) were 69±10 years old, and 43 were men (83%). Twenty-seven had been treated electively, and 25 for emergency indications. Reasons for emergency were acute type B aortic dissections with or without malperfusion syndrome in 14, and aortic ruptures in 11 cases. Follow-up was 29±16 months. Endpoints were perioperative and late morbidity and mortality rates and long-term quality of life as assessed by the short form health survey (SF-36) and Hospital Anxiety and Depression Scale questionnaires. Results: Cohorts were comparable regarding age, sex, cardiovascular risk factors, and comorbidities. Perioperative mortality was somewhat higher in emergency cases (12% vs 4%, p=0.34). Paraplegia occurred in one patient in each cohort (4%). Overall quality of life after two and a half years was similar in both treatment cohorts: 72 (58-124) after emergency, and 85 (61-105) after elective endovascular aortic repair (p=0.98). Normal scores range from 85 to 115. Anxiety and depression scores were in the normal range and comparable. Conclusions: Thoracic endovascular aortic repair is an excellent and safe treatment option for the diseased descending aorta, particularly in emergency situations. Early morbidity and mortality rates can be kept very low. Mid-term quality of life was not affected by the urgency of the procedure. Similarly, mid-term anxiety and depression scores were not increased after emergency situation

Unequal Mass Binary Black Hole Plunges and Gravitational Recoil

We present results from fully nonlinear simulations of unequal mass binary black holes plunging from close separations well inside the innermost stable circular orbit with mass ratios q = M_1/M_2 = {1,0.85,0.78,0.55,0.32}, or equivalently, with reduced mass parameters $\eta=M_1M_2/(M_1+M_2)^2 = {0.25, 0.248, 0.246, 0.229, 0.183}$. For each case, the initial binary orbital parameters are chosen from the Cook-Baumgarte equal-mass ISCO configuration. We show waveforms of the dominant l=2,3 modes and compute estimates of energy and angular momentum radiated. For the plunges from the close separations considered, we measure kick velocities from gravitational radiation recoil in the range 25-82 km/s. Due to the initial close separations our kick velocity estimates should be understood as a lower bound. The close configurations considered are also likely to contain significant eccentricities influencing the recoil velocity.Comment: 12 pages, 5 figures, to appear in "New Frontiers" special issue of CQ

Gravitational perturbations of Schwarzschild spacetime at null infinity and the hyperboloidal initial value problem

We study gravitational perturbations of Schwarzschild spacetime by solving a hyperboloidal initial value problem for the Bardeen-Press equation. Compactification along hyperboloidal surfaces in a scri-fixing gauge allows us to have access to the gravitational waveform at null infinity in a general setup. We argue that this hyperboloidal approach leads to a more accurate and efficient calculation of the radiation signal than the common approach where a timelike outer boundary is introduced. The method can be generalized to study perturbations of Kerr spacetime using the Teukolsky equation.Comment: 14 pages, 9 figure

High dietary fat consumption impairs axonal mitochondrial function in vivo

Peripheral neuropathy (PN) is the most common complication of prediabetes and diabetes. PN causes severe morbidity for Type 2 diabetes (T2D) and prediabetes patients, including limb pain followed by numbness resulting from peripheral nerve damage. PN in T2D and prediabetes is associated with dyslipidemia and elevated circulating lipids; however, the molecular mechanisms underlying PN development in prediabetes and T2D are unknown. Peripheral nerve sensory neurons rely on axonal mitochondria to provide energy for nerve impulse conduction under homeostatic conditions. Models of dyslipidemia in vitro demonstrate mitochondrial dysfunction in sensory neurons exposed to elevated levels of exogenous fatty acids. Herein, we evaluated the effect of dyslipidemia on mitochondrial function and dynamics in sensory axons of the saphenous nerve of a male high-fat diet (HFD)-fed murine model of prediabetes to identify mitochondrial alterations that correlate with PN pathogenesis in vivo. We found that the HFD decreased mitochondrial membrane potential (MMP) in axonal mitochondria and reduced the ability of sensory neurons to conduct at physiological frequencies. Unlike mitochondria in control axons, which dissipated their MMP in response to increased impulse frequency (from 1 to 50 Hz), HFD mitochondria dissipated less MMP in response to axonal energy demand, suggesting a lack of reserve capacity. The HFD also decreased sensory axonal Ca^{2+} levels and increased mitochondrial lengthening and expression of PGC1α, a master regulator of mitochondrial biogenesis. Together, these results suggest that mitochondrial dysfunction underlies an imbalance of axonal energy and Ca^{2+} levels and impairs impulse conduction within the saphenous nerve in prediabetic PN

Implementation of higher-order absorbing boundary conditions for the Einstein equations

We present an implementation of absorbing boundary conditions for the Einstein equations based on the recent work of Buchman and Sarbach. In this paper, we assume that spacetime may be linearized about Minkowski space close to the outer boundary, which is taken to be a coordinate sphere. We reformulate the boundary conditions as conditions on the gauge-invariant Regge-Wheeler-Zerilli scalars. Higher-order radial derivatives are eliminated by rewriting the boundary conditions as a system of ODEs for a set of auxiliary variables intrinsic to the boundary. From these we construct boundary data for a set of well-posed constraint-preserving boundary conditions for the Einstein equations in a first-order generalized harmonic formulation. This construction has direct applications to outer boundary conditions in simulations of isolated systems (e.g., binary black holes) as well as to the problem of Cauchy-perturbative matching. As a test problem for our numerical implementation, we consider linearized multipolar gravitational waves in TT gauge, with angular momentum numbers l=2 (Teukolsky waves), 3 and 4. We demonstrate that the perfectly absorbing boundary condition B_L of order L=l yields no spurious reflections to linear order in perturbation theory. This is in contrast to the lower-order absorbing boundary conditions B_L with L<l, which include the widely used freezing-Psi_0 boundary condition that imposes the vanishing of the Newman-Penrose scalar Psi_0.Comment: 25 pages, 9 figures. Minor clarifications. Final version to appear in Class. Quantum Grav

Food supply depends on seagrass meadows in the coral triangle

The tropical seascape provides food and livelihoods to hundreds of millions of people, but the support of key habitats to this supply remains ill appreciated. For fisheries and conservation management actions to help promote resilient ecosystems, sustainable livelihoods, and food supply, knowledge is required about the habitats that help support fisheries productivity and the consequences of this for food security. This paper provides an interdisciplinary case study from the coral triangle of how seagrass meadows provide support for fisheries and local food security. We apply a triangulated approach that utilizes ecological, fisheries and market data combined with over 250 household interviews. Our research demonstrates that seagrass associated fauna in a coral triangle marine protected area support local food supply contributing at least 50% of the fish based food. This formed between 54% and 99% of daily protein intake in the area. Fishery catch was found to significantly vary with respect to village (p < 0.01) with habitat configuration a probable driver. Juvenile fish comprised 26% of the fishery catch and gear type significantly influenced this proportion (<0.05). Limited sustainability of fishery practices (high juvenile catch and a 51% decline in CPUE for the biggest fishery) and poor habitat management mean the security of this food supply has the potential to be undermined in the long-term. Findings of this study have implications for the management and assessment of fisheries throughout the tropical seascape. Our study provides an exemplar for why natural resource management should move beyond biodiversity and consider how conservation and local food security are interlinked processes that are not mutually exclusive. Seagrass meadows are under sustained threat worldwide, this study provides evidence of the need to conserve these not just to protect biodiversity but to protect food security

AMR, stability and higher accuracy

Efforts to achieve better accuracy in numerical relativity have so far focused either on implementing second order accurate adaptive mesh refinement or on defining higher order accurate differences and update schemes. Here, we argue for the combination, that is a higher order accurate adaptive scheme. This combines the power that adaptive gridding techniques provide to resolve fine scales (in addition to a more efficient use of resources) together with the higher accuracy furnished by higher order schemes when the solution is adequately resolved. To define a convenient higher order adaptive mesh refinement scheme, we discuss a few different modifications of the standard, second order accurate approach of Berger and Oliger. Applying each of these methods to a simple model problem, we find these options have unstable modes. However, a novel approach to dealing with the grid boundaries introduced by the adaptivity appears stable and quite promising for the use of high order operators within an adaptive framework