Finding diamonds in the rough: Targeted Sub-threshold Search for Strongly-lensed Gravitational-wave Events

Strong gravitational lensing of gravitational waves can produce duplicate signals separated in time with different amplitudes. We consider the case in which strong lensing produces identifiable gravitational-wave events and weaker sub-threshold signals hidden in the noise background. We present a search method for the sub-threshold signals using reduced template banks targeting specific confirmed gravitational-wave events. We apply the method to all events from Advanced LIGO's first and second observing run O1/O2. Using GW150914 as an example, we show that the method effectively reduces the noise background and raises the significance of (near-) sub-threshold triggers. In the case of GW150914, we can improve the sensitive distance by $2.0\% - 14.8\%$. Finally, we present the top $5$ possible lensed candidates for O1/O2 gravitational-wave events that passed our nominal significance threshold of False-Alarm-Rate $\leq 1/30$ days

Rapid generation of fully relativistic extreme-mass-ratio-inspiral waveform templates for LISA data analysis

The future space mission LISA will observe a wealth of gravitational-wave sources at millihertz frequencies. Of these, the extreme-mass-ratio inspirals of compact objects into massive black holes are the only sources that combine the challenges of strong-field complexity with that of long-lived signals. Such signals are found and characterized by comparing them against a large number of accurate waveform templates during data analysis, but the rapid generation of such templates is hindered by computing the $\sim10^3$-$10^5$ harmonic modes in a fully relativistic waveform. We use order-reduction and deep-learning techniques to derive a global fit for these modes, and implement it in a complete waveform framework with hardware acceleration. Our high-fidelity waveforms can be generated in under $1\,\mathrm{s}$, and achieve a mismatch of $\lesssim 5\times 10^{-4}$ against reference waveforms that take $\gtrsim 10^4$ times longer. This marks the first time that analysis-length waveforms with full harmonic content can be produced on timescales useful for direct implementation in LISA analysis algorithms.Comment: 6 pages, 3 figure

Assessing the data-analysis impact of LISA orbit approximations using a GPU-accelerated response model

The analysis of gravitational wave (GW) datasets is based on the comparison of measured time series with theoretical templates of the detector's response to a variety of source parameters. For LISA, the main scientific observables will be the so-called time-delay interferometry (TDI) combinations, which suppress the otherwise overwhelming laser noise. Computing the TDI response to GW involves projecting the GW polarizations onto the LISA constellation arms, and then combining projections delayed by a multiple of the light propagation time along the arms. Both computations are difficult to perform efficiently for generic LISA orbits and GW signals. Various approximations are currently used in practice, e.g., assuming constant and equal armlengths, which yields analytical TDI expressions. In this article, we present 'fastlisaresponse', a new efficient GPU-accelerated code that implements the generic TDI response to GWs in the time domain. We use it to characterize the parameter-estimation bias incurred by analyzing loud Galactic-binary signals using the equal-armlength approximation. We conclude that equal-armlength parameter-estimation codes should be upgraded to the generic response if they are to achieve optimal accuracy for high (but reasonable) SNR sources within the actual LISA data.Comment: 15 pages, 7 figures, 2 table

A new photogrammetric method for quantifying corneal topography

Attempts to describe normal corneal shape and to represent corneal topography by an array of discrete points have limited usefulness. A quantitative photogrammetric method that produces indices to describe corneal shape was developed. Four indices depict the departure of keratographic rings from circularity, and two indices express the trends and consistencies of all the rings from one keratograph. This photogrammetric index method (PIM) was evaluated against established measurement techniques. Values for the six indices were computed for groups (10 corneas each) of symmetrical, regularly astigmatic, and keratoconic corneas that had been defined by keratometry and clinical criteria. Predictions of the differences among groups were formulated for each index based on group descriptions and anticipated manual tracing and/or digitization error. Parametric and nonparametric tests of significance supported most predictions. The asymmetry of irregularly astigmatic keratoconic corneas, the variability of their orthogonal principal meridians, and an increasing symmetry toward their peripheries were documented clearly. The circularity of symmetrical group rings and the ellipticity of regularly astigmatic group rings were also evident. Preliminary norms are offered to illustrate the usefulness of the PIM in defining groups of corneas with the same histories and in classifying individual corneas

Effect of tissue fit on corneal shape after transplantation

Postkeratoplasty astigmatism is now a major problem preventing visual recovery. Certain postopertive topographic characteristics are felt to be dictated by the fit of the donor corneal button in its recipient bed. Deficient tissue at the wound is predicted to contribute to the location of the steep meridian and excess tissue to the location of the flat meridian. In an eight-cat sample using our Fit Assessment Method and Photogrammetric Index Method, the authors tested the relationship between button fit in recipient bed and resulting corneal curvature at approximately 42, 161, and 289 postoperative days. Corneal symmetry improved between the first and second postoperative periods. Deficient tissue led to steepened curvature and ample tissue to flattened curvature in the first measurement period. When buttons fit poorly, deficient tissue led to steepness in the first postoperative period, but led to flattened curvature 90 deg away from the deficient tissue meridian in the second and third periods. The relationship between ample tissue and flattest postoperative curvature did not depend on the magnitude of button-bed disparity in any period. Corneal elasticity appeared to influence the way tissue disparity affected postoperative topography. Our findings support Troutman's balloon mode. When there was a large amount of uncompensated tissue disparity, the tissue deficiency exerted a force that shortened the translimbal chord. This produced both steepened curvature parallel to this chord soon after surgery and flattened curvature at 90 deg to the chord in the stable postoperative cornea

SALINAS - An implicit finite element structural dynamics code developed for massively parallel platforms

As computational needs for structural finite element analysis increase, a robust implicit structural dynamics code is needed which can handle millions of degrees of freedom in the model and produce results with quick turn around time. A parallel code is needed to avoid limitations of serial platforms. Salinas is an implicit structural dynamics code specifically designed for massively parallel platforms. It computes the structural response of very large complex structures and provides solutions faster than any existing serial machine. This paper gives a current status of Salinas and uses demonstration problems to show Salinas' performance

When grassroots innovation movements encounter mainstream institutions: implications for models of inclusive innovation

Grassroots innovation movements (GIMs) can be regarded as initiators or advocates of alternative pathways of innovation. Sometimes these movements engage with more established science, technology and innovation (STI) institutions and development agencies in pursuit of their goals. In this paper, we argue that an important aspect to encounters between GIMs and mainstream STI institutions is the negotiation of different framings of grassroots innovation and development of policy models for inclusive innovation. These encounters can result in two different modes of engagement by GIMs; what we call insertion and mobilization. We illustrate and discuss these interrelated notions of framings and modes of engagement by drawing on three case studies of GIMs: the Social Technologies Network in Brazil, and the Honey Bee Network and People's Science Movements in India. The cases highlight that inclusion in the context of GIMs is not an unproblematic, smooth endeavour, and involves diverse interpretations and framings, which shape what and who gets included or excluded. Within the context of increasing policy interest, the analysis of encounters between GIMs and STI institutions can offer important lessons for the design of models of inclusive innovation and development

Pengaruh Konsistensi Fly Ash Terhadap Sifat - Sifat Mortar Hvfa

Fly ash merupakan hasil dari pembakaran batubara banyak digunakan sebagai bahan pengganti semen. Keuntungan penggunaan fly ash pada beton segar ialah kehalusan dan bentuk partikel fly ash yang bulat dapat meningkatkan workability, serta mengurangi terjadinya bleeding dan segregasi. Permasalahan yang sering dihadapi dalam penggunaan fly ash ini adalah kemampuan untuk mengontrol mutu fly ash yang dihasilkan.Fly ash berwarna abu-abu hingga kehitaman warna kehitaman karena adanya karbon, hal ini disebabkan pembakaran yang tidak sempurna. Juga dari penelitian lain disebutkan bahwa kandungan dari fly ash dipengaruhi dari asal batu bara, teknik pembakaran batu bara, kandungan mineral, metode pengumpulan, lama waktu penyimpanan, dan periode pengambilan sampel.Oleh karena itu dapat disimpulkan bahwa, perbedaan waktu pengambilan fly ash memungkinkan terjadinya perbedaan antara masing-masing fly ash. Dalam penelitian ini kami ingin melihat konsistensi dari setiap fly ash yang kami ambil dengan waktu yang berbeda-beda. Kandungan mineral yang terdapat dalam fly ash bervariasi, dan variasi ini tentu bisa menyebabkan perbedaan pada kualitas dan mutu beton yang dihasilkan. Variasi fly ash yang ada dapat dilihat dari kandungan kimia yang ada, kehalusan, dan loss on ignition (LOI). Kualitas dari fly ash dapat dengan mudah ditentukan melalui pengukuran nilai pH fly ash.Dalam penelitian ini menggunakan campuran mortar high volume fly ash (HVFA) dimana menggunakan penggantian semen hingga 50%