Enhancing the significance of gravitational wave bursts through signal classification

The quest to observe gravitational waves challenges our ability to discriminate signals from detector noise. This issue is especially relevant for transient gravitational waves searches with a robust eyes wide open approach, the so called all- sky burst searches. Here we show how signal classification methods inspired by broad astrophysical characteristics can be implemented in all-sky burst searches preserving their generality. In our case study, we apply a multivariate analyses based on artificial neural networks to classify waves emitted in compact binary coalescences. We enhance by orders of magnitude the significance of signals belonging to this broad astrophysical class against the noise background. Alternatively, at a given level of mis-classification of noise events, we can detect about 1/4 more of the total signal population. We also show that a more general strategy of signal classification can actually be performed, by testing the ability of artificial neural networks in discriminating different signal classes. The possible impact on future observations by the LIGO-Virgo network of detectors is discussed by analysing recoloured noise from previous LIGO-Virgo data with coherent WaveBurst, one of the flagship pipelines dedicated to all-sky searches for transient gravitational waves

Prospects for intermediate mass black hole binary searches with advanced gravitational-wave detectors

We estimated the sensitivity of the upcoming advanced, ground-based gravitational-wave observatories (the upgraded LIGO and Virgo and the KAGRA interferometers) to coalescing intermediate mass black hole binaries (IMBHB). We added waveforms modeling the gravitational radiation emitted by IMBHBs to detectors' simulated data and searched for the injected signals with the coherent WaveBurst algorithm. The tested binary's parameter space covers non-spinning IMBHBs with source-frame total masses between 50 and 1050 $\text{M}_{\odot}$ and mass ratios between $1/6$ and 1$\,$. We found that advanced detectors could be sensitive to these systems up to a range of a few Gpc. A theoretical model was adopted to estimate the expected observation rates, yielding up to a few tens of events per year. Thus, our results indicate that advanced detectors will have a reasonable chance to collect the first direct evidence for intermediate mass black holes and open a new, intriguing channel for probing the Universe over cosmological scales.Comment: 9 pages, 4 figures, corrected the name of one author (previously misspelled

Feedback cooling of the normal modes of a massive electromechanical system to submillikelvin temperature

We apply a feedback cooling technique to simultaneously cool the three electromechanical normal modes of the ton-scale resonant-bar gravitational wave detector AURIGA. The measuring system is based on a dc Superconducting Quantum Interference Device (SQUID) amplifier, and the feedback cooling is applied electronically to the input circuit of the SQUID. Starting from a bath temperature of 4.2 K, we achieve a minimum temperature of 0.17 mK for the coolest normal mode. The same technique, implemented in a dedicated experiment at subkelvin bath temperature and with a quantum limited SQUID, could allow to approach the quantum ground state of a kilogram-scale mechanical resonator.Comment: 4 pages, 4 figure

Mental health problems in adolescents: how to identify them?

Universidade Federal de São Paulo (UNIFESP)Universidade Presbiteriana MackenzieUNIFESPSciEL

A burst search for gravitational waves from binary black holes

Compact binary coalescence (CBC) is one of the most promising sources of gravitational waves. These sources are usually searched for with matched filters which require accurate calculation of the GW waveforms and generation of large template banks. We present a complementary search technique based on algorithms used in un-modeled searches. Initially designed for detection of un-modeled bursts, which can span a very large set of waveform morphologies, the search algorithm presented here is constrained for targeted detection of the smaller subset of CBC signals. The constraint is based on the assumption of elliptical polarisation for signals received at the detector. We expect that the algorithm is sensitive to CBC signals in a wide range of masses, mass ratios, and spin parameters. In preparation for the analysis of data from the fifth LIGO-Virgo science run (S5), we performed preliminary studies of the algorithm on test data. We present the sensitivity of the search to different types of simulated CBC waveforms. Also, we discuss how to extend the results of the test run into a search over all of the current LIGO-Virgo data set.Comment: 12 pages, 4 figures, 2 tables, submitted for publication in CQG in the special issue for the conference proceedings of GWDAW13; corrected some typos, addressed some minor reviewer comments one section restructured and references updated and correcte

Networks of gravitational wave detectors and three figures of merit

This paper develops a general framework for studying the effectiveness of networks of interferometric gravitational wave detectors and then uses it to show that enlarging the existing LIGO-VIRGO network with one or more planned or proposed detectors in Japan (LCGT), Australia, and India brings major benefits, including much larger detection rate increases than previously thought... I show that there is a universal probability distribution function (pdf) for detected SNR values, which implies that the most likely SNR value of the first detected event will be 1.26 times the search threshold. For binary systems, I also derive the universal pdf for detected values of the orbital inclination, taking into account the Malmquist bias; this implies that the number of gamma-ray bursts associated with detected binary coalescences should be 3.4 times larger than expected from just the beaming fraction of the gamma burst. Using network antenna patterns, I propose three figures of merit that characterize the relative performance of different networks... Adding {\em any} new site to the planned LIGO-VIRGO network can dramatically increase, by factors of 2 to 4, the detected event rate by allowing coherent data analysis to reduce the spurious instrumental coincident background. Moving one of the LIGO detectors to Australia additionally improves direction-finding by a factor of 4 or more. Adding LCGT to the original LIGO-VIRGO network not only improves direction-finding but will further increase the detection rate over the extra-site gain by factors of almost 2, partly by improving the network duty cycle... Enlarged advanced networks could look forward to detecting three to four hundred neutron star binary coalescences per year.Comment: 38 pages, 7 figures, 2 tables. Accepted for publication in Classical and Quantum Gravit

Search for binary black hole mergers in the third observing run of Advanced LIGO-Virgo using coherent WaveBurst enhanced with machine learning

In this work, we use the coherent WaveBurst (cWB) pipeline enhanced with machine learning (ML) to search for binary black hole (BBH) mergers in the Advanced LIGO-Virgo strain data from the third observing run. We detect, with equivalent or higher significance, all gravitational-wave (GW) events previously reported by the standard cWB search for BBH mergers in the third GW Transient Catalog. The ML-enhanced cWB search identifies five additional GW candidate events from the catalog that were previously missed by the standard cWB search. Moreover, we identify three marginal candidate events not listed in third GW Transient Catalog. For simulated events distributed uniformly in a fiducial volume, we improve the sensitive hypervolume with respect to the standard cWB search by approximately 28% and 34% for the stellar-mass and intermediate mass black hole binary mergers respectively, detected with a false-alarm rate less than 1/100 yr-1. We show the robustness of the ML-enhanced search for detection of generic BBH signals by reporting increased sensitivity to the spin-precessing and eccentric BBH events as compared to the standard cWB search. Furthermore, we compare the improvement of the ML-enhanced cWB search for different detector networks

Mental health and violence among sixth grade students from a city in the state of São Paulo

OBJECTIVE: To analyze risk and protective factors for mental health problems among adolescents. METHODS: Cross-sectional study with a random sample (N=327; attrition rate=6.9%) of sixth grade students from all public and private schools in the city of Barretos, Southeastern Brazil, conducted in 2004. The factors studied were: exposure to intrafamilial and urban violence, family socioeconomic level, sex, motherless household, participation in social activities (protective factor). All the independent risk and protective factors were included in the initial logistic regression model. Only the variable with a significance level of p<0.05 remained in the model. RESULTS: It was observed that exposure to violence was the only factor associated with mental health problems in the final logistic regression model (p=0.02, 95% CI: 1.12;4.22). In addition, adolescents exposed to intrafamilial violence were three times more likely to have problems than those exposed to urban violence (p=0.04; 95% CI: 1.03;7.55). CONCLUSIONS: Intrafamilial violence was associated with mental heath problems among adolescents studied and it could be more important than urban violence in medium-sized cities.OBJETIVO: Analisar fatores de proteção e de risco para problemas de saúde mental entre adolescentes. MÉTODOS: Estudo transversal realizado com amostra aleatória (N=327; perda=6,9%) de estudantes da sexta série de todas as escolas públicas e privadas de Barretos, SP, em 2004. Os fatores examinados foram: exposição à violência doméstica e urbana, nível socioeconômico familiar, sexo, morar sem a mãe, participar de atividades sociais (fator de proteção). As associações entre esses fatores e problemas de saúde mental foram analisadas por meio de modelos de regressão logística. Todos os fatores de risco e proteção independentes foram incluídos no modelo inicial de regressão logística, permanecendo no modelo final apenas a variável com nível de significância inferior a 0,05. RESULTADOS: Verificou-se que apenas exposição à violência permaneceu no modelo final como fator associado a problemas de saúde mental (p=0,02; IC 95%: 1,12;4,22). Crianças expostas à violência doméstica tinham três vezes mais chances de apresentarem estes problemas do que aquelas expostas à violência urbana (p=0,04; IC 95%: 1,03;7,55). CONCLUSÕES: A violência doméstica associou-se a problemas de saúde mental nos adolescentes do estudo, podendo ser mais importante que a violência urbana em cidades de médio porte.Universidade Presbiteriana Mackenzie Programa de Pós-graduação em Distúrbios do DesenvolvimentoUniversidade Federal de São Paulo (UNIFESP) Departamento de Psiquiatria Setor de Psiquiatria SocialUNIFESP Departamento de Psiquiatria Unidade de Psiquiatria da Infância e AdolescênciaUNIFESP, Depto. de Psiquiatria Setor de Psiquiatria SocialUNIFESP, Depto. de Psiquiatria Unidade de Psiquiatria da Infância e AdolescênciaSciEL

Safety of Rapid Daratumumab Infusion: A Retrospective, Multicenter, Real-Life Analysis on 134 Patients With Multiple Myeloma

Background: The anti-CD38 monoclonal antibody daratumumab is the backbone of most anti-multiple myeloma (MM) regimens. To mitigate the risk of infusion-related reactions (IRRs), intravenous daratumumab administration requires 7 hours for the first infusion and 3.5-4 hours thereafter, thus making daratumumab-containing regimens burdensome for patients and health care resources. Preliminary data suggest that a rapid (90-minute) infusion of daratumumab is safe and does not increase IRRs. The rapid schedule was adopted by our centers since 2019. Methods: We conducted an observational multi-center, real-life study to assess the safety of rapid daratumumab infusion protocol from the third administration in relapsed MM patients receiving daratumumab alone or in combination with lenalidomide-dexamethasone or bortezomib-dexamethasone. The primary endpoint was the safety of the rapid infusion protocol, particularly in terms of IRRs. Results: A total of 134 MM patients were enrolled. IRRs occurred in 7 (5%) patients and were mostly mild (6/7 of grade 1-2), with only 1 patient experiencing a grade 3 IRR. Due to the IRRs, 5 (3.7%) patients discontinued the rapid infusions and resumed daratumumab at the standard infusion rate, while 1 patient permanently discontinued daratumumab. In 4/7 patients (57%), IRRs occurred while resuming rapid daratumumab infusions after a temporary interruption (2-4 months). No other adverse event was considered related to the rapid infusion protocol. Conclusions: Our findings confirmed the safety of rapid daratumumab infusions starting from the third administration. In case of prolonged daratumumab interruption, it is advisable to resume infusions at the standard rate (3.5 hours) before switching to the rapid infusion