Gravitational waves from BH-NS binaries: Effective Fisher matrices and parameter estimation using higher harmonics

Inspiralling black hole-neutron star (BH-NS) binaries emit a complicated gravitational wave signature, produced by multiple harmonics sourced by their strong local gravitational field and further modulated by the orbital plane's precession. Some features of this complex signal are easily accessible to ground-based interferometers (e.g., the rate of change of frequency); others less so (e.g., the polarization content); and others unavailable (e.g., features of the signal out of band). For this reason, an ambiguity function (a diagnostic of dissimilarity) between two such signals varies on many parameter scales and ranges. In this paper, we present a method for computing an approximate, effective Fisher matrix from variations in the ambiguity function on physically pertinent scales which depend on the relevant signal to noise ratio. As a concrete example, we explore how higher harmonics improve parameter measurement accuracy. As previous studies suggest, for our fiducial BH-NS binaries and for plausible signal amplitudes, we see that higher harmonics at best marginally improve our ability to measure parameters. For non-precessing binaries, these Fisher matrices separate into intrinsic (mass, spin) and extrinsic (geometrical) parameters; higher harmonics principally improve our knowledge about the line of sight. For the precessing binaries, the extra information provided by higher harmonics is distributed across several parameters. We provide concrete estimates for measurement accuracy, using coordinates adapted to the precession cone in the detector's sensitive band.Comment: 19 pages, 11 figure

Somatic coliphage families as potential indicators of enteric viruses in water and methods for their detection

The potential use of specific somatic coliphage taxonomic groups as viral indicators on the basis of their persistence and prevalence in water was investigated. Representative type strains of the 4 major somatic coliphage taxonomic groups were seeded into environmental water and their survival was measured at temperatures of 23-25 and 4oC. Based on their greater persistence over time, the Myoviridae (type strain T4), the Microviridae (type strain PhiX174), and the Siphoviridae (type strain Lambda) were the preferred candidate somatic coliphages as candidate fecal indicator viruses in water. Also, a conventional, group-specific PCR method was developed to identify each of the 4 major taxonomic groups of somatic coliphages and used to classify individual somatic coliphage isolates from primary human sewage effluent to further document those detected and to describe their behavior in environmental waters. Over time, the taxonomic makeup of the somatic coliphage population in sewage changes, with the Microviridae family becoming the most prevalent taxonomic group in the sewage population after several weeks. Based on their persistence and prevalence in environmental waters, phages belonging to the Microviridae family could serve as indicators for sewage contamination and perhaps human enteric viruses in water. Rapid detection methods for reliable viral indicators that predict viral contamination in water are essential for timely protection of public health. Individual somatic coliphage families that are relatively persistent and abundant in environmental waters are possible reliable viral indicators. Rapid detection of the Microviridae family of somatic coliphages by real-time PCR method was developed and successfully applied to environmental water samples: primary sewage effluent of two different geographic regions, seawater, and groundwater. Also, as an antibody-based rapid detection method, CLAT (Culture, Latex Agglutination, and Typing), for the Siphoviridae family, N4-type viruses of the Podoviridae family, and T4-type viruses of Myoviridae, was developed and successfully applied to somatic coliphage isolates, although there is a need for improvement in method sensitivity and specificity. Developing new and rapid nucleic-based detection and antibody-based somatic coliphage detection and characterization methods will assist in future studies to evaluate individual somatic coliphage families as sewage and viral indicators for water quality assessment

End-to-End Differentiable Learning to HDR Image Synthesis for Multi-exposure Images

Recently, high dynamic range (HDR) image reconstruction based on the multiple exposure stack from a given single exposure utilizes a deep learning framework to generate high-quality HDR images. These conventional networks focus on the exposure transfer task to reconstruct the multi-exposure stack. Therefore, they often fail to fuse the multi-exposure stack into a perceptually pleasant HDR image as the inversion artifacts occur. We tackle the problem in stack reconstruction-based methods by proposing a novel framework with a fully differentiable high dynamic range imaging (HDRI) process. By explicitly using the loss, which compares the network's output with the ground truth HDR image, our framework enables a neural network that generates the multiple exposure stack for HDRI to train stably. In other words, our differentiable HDR synthesis layer helps the deep neural network to train to create multi-exposure stacks while reflecting the precise correlations between multi-exposure images in the HDRI process. In addition, our network uses the image decomposition and the recursive process to facilitate the exposure transfer task and to adaptively respond to recursion frequency. The experimental results show that the proposed network outperforms the state-of-the-art quantitative and qualitative results in terms of both the exposure transfer tasks and the whole HDRI process

Metnase Mediates Loading of Exonuclease 1 onto Single Strand Overhang DNA for End Resection at Stalled Replication Forks

Stalling at DNA replication forks generates stretches of single-stranded (ss) DNA on both strands that are exposed to nucleolytic degradation, potentially compromising genome stability. One enzyme crucial for DNA replication fork repair and restart of stalled forks in human is Metnase (also known as SETMAR), a chimeric fusion protein consisting of a su(var)3-9, enhancer-of-zeste and trithorax (SET) histone methylase and transposase nuclease domain. We previously showed that Metnase possesses a unique fork cleavage activity necessary for its function in replication restart and that its SET domain is essential for recovery from hydroxyurea-induced DNA damage. However, its exact role in replication restart is unclear. In this study, we show that Metnase associates with exonuclease 1 (Exo1), a 5'-exonuclease crucial for 5'-end resection to mediate DNA processing at stalled forks. Metnase DNA cleavage activity was not required for Exo1 5'-exonuclease activity on the lagging strand daughter DNA, but its DNA binding activity mediated loading of Exo1 onto ssDNA overhangs. Metnase-induced enhancement of Exo1-mediated DNA strand resection required the presence of these overhangs but did not require Metnase's DNA cleavage activity. These results suggest that Metnase enhances Exo1-mediated exonuclease activity on the lagging strand DNA by facilitating Exo1 loading onto a single strand gap at the stalled replication fork

Numerical modelling of scour around circular cylinder caused by jet flow and bed shear stress

A new scour numerical model composed of two modules is proposed here. The two modules are detailed Reynolds-average Navier-Stokes flow module and sediment transport and resultant scour module. The flow module uses horizontally regular grid at the bed but partial grid concept in the vertical direction. The sediment module operates entrainment, and deposition of suspended sediment. The entrainment of sediment is computed by a new empirical equation; the major independent variables of which are the jet flow velocity and the bed shear stress. The model is applied to a laboratory scour experiment around a circular cylinder at Kookmin University, and shows satisfactory agreement with measurements