1,561 research outputs found
False discovery rate: setting the probability of false claim of detection
When testing multiple hypothesis in a survey --e.g. many different source
locations, template waveforms, and so on-- the final result consists in a set
of confidence intervals, each one at a desired confidence level. But the
probability that at least one of these intervals does not cover the true value
increases with the number of trials. With a sufficiently large array of
confidence intervals, one can be sure that at least one is missing the true
value. In particular, the probability of false claim of detection becomes not
negligible. In order to compensate for this, one should increase the confidence
level, at the price of a reduced detection power. False discovery rate control
is a relatively new statistical procedure that bounds the number of mistakes
made when performing multiple hypothesis tests. We shall review this method,
discussing exercise applications to the field of gravitational wave surveys.Comment: 7 pages, 3 table, 3 figures. Prepared for the Proceedings of GWDAW 9
(http://lappc-in39.in2p3.fr/GWDAW9) A new section was added with a numerical
example, along with two tables and a figure related to the new section. Many
smaller revisions to improve readibilit
Selective readout and back-action reduction for wideband acoustic gravitational wave detectors
We present the concept of selective readout for broadband resonant mass
gravitational wave detectors. This detection scheme is capable of specifically
selecting the signal from the contributions of the vibrational modes sensitive
to the gravitational waves, and efficiently rejecting the contribution from non
gravitationally sensitive modes. Moreover this readout, applied to a dual
detector, is capable to give an effective reduction of the back-action noise
within the frequency band of interest. The overall effect is a significant
enhancement in the predicted sensitivity, evaluated at the standard quantum
limit for a dual torus detector. A molybdenum detector, 1 m in diameter and
equipped with a wide area selective readout, would reach spectral strain
sensitivities 2x10^{-23}/sqrt{Hz} between 2-6 kHz.Comment: 9 pages, 4 figure
Dynamical two-mode squeezing of thermal fluctuations in a cavity opto-mechanical system
We report the experimental observation of two-mode squeezing in the
oscillation quadratures of a thermal micro-oscillator. This effect is obtained
by parametric modulation of the optical spring in a cavity opto-mechanical
system. In addition to stationary variance measurements, we describe the
dynamic behavior in the regime of pulsed parametric excitation, showing
enhanced squeezing effect surpassing the stationary 3dB limit. While the
present experiment is in the classical regime, our technique can be exploited
to produce entangled, macroscopic quantum opto-mechanical modes
Correlation between Gamma-Ray bursts and Gravitational Waves
The cosmological origin of -ray bursts (GRBs) is now commonly
accepted and, according to several models for the central engine, GRB sources
should also emit at the same time gravitational waves bursts (GWBs). We have
performed two correlation searches between the data of the resonant
gravitational wave detector AURIGA and GRB arrival times collected in the BATSE
4B catalog. No correlation was found and an upper limit \bbox{} on the averaged amplitude of gravitational waves
associated with -ray bursts has been set for the first time.Comment: 7 pages, 3 figures, submitted to Phys. Rev.
Control of Recoil Losses in Nanomechanical SiN Membrane Resonators
In the context of a recoil damping analysis, we have designed and produced a
membrane resonator equipped with a specific on-chip structure working as a
"loss shield" for a circular membrane. In this device the vibrations of the
membrane, with a quality factor of , reach the limit set by the intrinsic
dissipation in silicon nitride, for all the modes and regardless of the modal
shape, also at low frequency. Guided by our theoretical model of the loss
shield, we describe the design rationale of the device, which can be used as
effective replacement of commercial membrane resonators in advanced
optomechanical setups, also at cryogenic temperatures
Strategies of tailored nanomaterials for electrochemiluminescence signal enhancements
Nanomaterials and their applications were studied extensively over the past few decades due to their properties which are associated mainly with the nanoscale sizes and unique characteristics that they have. Among many applications, these nanomaterials have been playing great, multifaceted roles in increasing the analytical performances of electrochemiluminescence (ECL). In this article, we review the main possible approaches – based on nanoparticles – to modify the photophysical properties of the excited state generated as a consequence of the electrochemical stimulus and in particular taking profit of the so-called metal-enhanced fluorescence (MEF) and resonance energy transfer (RET) processes. We believe that these strategies will lead to the design of very efficient systems that can substantially increase the possible successful applications of ECL
Photoluminescence-Based Techniques for the Detection of Micro- and Nanoplastics
The growing numbers related to plastic pollution are impressive, with ca. 70 % of produced plastic (>350 tonnes/year) being indiscriminately wasted in the environment. The most dangerous forms of plastic pollution for biota and human health are micro- and nano-plastics (MNPs), which are ubiquitous and more bioavailable. Their elimination is extremely difficult, but the first challenge is their detection since existing protocols are unsatisfactory for microplastics and mostly absent for nanoplastics. After a discussion of the state of the art for MNPs detection, we specifically revise the techniques based on photoluminescence that represent very promising solutions for this problem. In this context, Nile Red staining is the most used strategy and we show here its pros and limitations, but we also discuss other more recent approaches, such as the use of fluorogenic probes based on perylene-bisimide and on fluorogenic hyaluronan nanogels, with the added values of biocompatibility and water solubility
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
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