1,721,168 research outputs found
LIGO AND VIRGO GRAVITATIONAL WAVES DATA ANALYSIS
No full textThe LIGO and Virgo detectors collected long stretches of science data in the last years. The analysis of these data in the search for gravitational waves applied different methods and strategies targeted to the identification and characterisation of signals emitted by multiple possible sources. In this brief report we will outline the recent scientific results for signals coming from compact coalescing binary systems involving neutron stars and black holes, burst-like and continuous gravitational waves signals and signals from a broadband and continous background of gravitational waves that could be produced by a large collection of incoherent sources
A powerful veto for gravitational wave searches using data from Virgo's first scientific run
No full textThe use of vetoes generated from auxiliary channels suppresses most of the
high amplitude noise triggers that impair gravitational wave (GW) burst and
binary inspiral searches. DuringVirgo’s first scientific run (VSR1),many of the
remaining loud burst and inspiralVirgo triggerswere observedwith nearly equal
significance in both the in-phase (ACp) and quadrature (ACq) interferometer
output channels, while we expect the ACq channel to be insensitive to a GW
signal. We describe a veto based on the ratio of the amplitude of the ACp and
ACq signals. From studying hardware signal injections, we demonstrate that
the ratio of the amplitude of coincident ACp and ACq triggers can be safely
used to define a veto; we show its efficiency for the burst and binary inspiral
analyses of the VRS1 data
A time-domain veto for binary inspirals search
Full text linkWe describe a test to distinguish between actual gravitational waves from
binary inspiral and false noise triggers. The test operates in the time domain,
and considers the time evolution of the correlator and its statistical distribution.
It should distinguish true versus noisy events with the same signal-to-noise
ratio and chi-square frequency distribution. A similar test has been applied to
S1 LIGO data
Performance of a 'generalized δ-filter' for the detection of burst events
No full textIn this work we report on the performance of a complete implementation of the generalized delta filter detector for burst events, tested against simulated data. We measure the receiver operating characteristics in the case of noise having the expected spectral density of the Virgo interferometer, injecting test signals taken from the Zwerger–Müller library of simulated events, predicted to result from the collapse of type II supernovae, for different levels of signal to noise ratio
A power filter for the detection of burst events based on time–frequency spectrum estimation
No full textWe propose as a statistic for the detection of bursts in a gravitational wave interferometer the 'energy' of the events estimated with a time-dependent calculation of the spectrum. This statistic has an asymptotic Gaussian distribution with known statistical moments, which makes it possible to perform a uniformly most powerful test (McDonough R N and Whalen A D 1995 Detection of Signals in Noise (New York: Academic)) on the energy mean. We estimate the receiver operating characteristic (ROC, from the same book) of this statistic for different levels of the signal-to-noise ratio in the specific case of a simulated noise having the spectral density expected for Virgo, using test signals taken from a library of possible waveforms emitted during the collapse of the core of type II supernovae
Bistability without hysteresis in chemical reaction systems: A theoretical analysis of irreversible transitions between multiple steady states
No full textSCOPUS: ar.jinfo:eu-repo/semantics/publishe
From bistability to oscillations in a model for the isocitrate dehydrogenase reaction
No full textConsidered is a bienzymatic system consisting of isocitrate dehydrogenase (IDH, EC 1.1.1.42), which transforms NADP+ into NADPH, and of diaphorase (DIA, EC 1.8.1.4), which catalyzes the reverse reaction. Experimental evidence as well as a theoretical model show the possibility of a coexistence between two stable steady states in this reaction system. The phenomenon originates from the regulatory properties of IDH. We extend the analysis of a theoretical model proposed for the IDH-DIA bienzymatic system and investigate the occurrence of different modes of bistability, with or without hysteresis, i.e. in the presence of two or only one limit point bounding the domain of multiple steady states. The analysis indicates that the two types of bistability may sometimes be observed sequentially as a given control parameter is progressively increased. We further obtain conditions in which sustained oscillations develop in the model. These results establish the isocitrate dehydrogenase reaction coupled to diaphorase as a suitable candidate for further experimental and theoretical studies of bistability and oscillations in biochemical systems.SCOPUS: cp.jinfo:eu-repo/semantics/publishe
Bistability without hysteresis in chemical reaction systems: The case of nonconnected branches of coexisting steady states
No full textSCOPUS: ar.jinfo:eu-repo/semantics/publishe
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