Roma Tre University

About: Roma Tre University is a education organization based out in Rome, Lazio, Italy. It is known for research contribution in the topics: Large Hadron Collider & Galaxy. The organization has 4434 authors who have published 15352 publications receiving 374888 citations. The organization is also known as: Universita degli Studi Roma Tre & RomaTre.

An accurate model for capacitive micromachined ultrasonic transducers

Abstract: Modeling of capacitive micromachined ultrasonic transducers (cMUTs) is based on a two-port network with an electrical and a mechanical side. To obtain a distributed model, a solution of the differential equation of motion of the diaphragm for each element of the transducer has to be found. Previous works omit the mechanical load of the cavity behind the diaphragm, i.e., the effect of the gas inside. In this paper, we propose a distributed model for cMUTs that takes this effect into account. A closed-form solution of the mechanical impedance of the membranes has been obtained, including the effect of the restoring forces because of the stiffness of the membrane and because of the compression of the air in the cavity. Simulation results based on the presented model are compared with the experimental data for two types of cMUTs reported in the recent literature. It is demonstrated that the compression of the air has a significant effect on the fundamental frequency of the air transducer, with a deviation of about 22% from the prediction of a model that does not consider the interaction between the vibrating diaphragm and the air cushion.

Discovery of six Lyα emitters near a radio galaxy at z ∼ 5.2

Abstract: We present the results of narrow-band and broad-band imaging with the Very Large Telescope* of the field surrounding the radio galaxy TN J0924-2201 at z = 5.2. Fourteen candidate Lya emitters with a rest-frame equivalent width of >20 A were detected. Spectroscopy of 8 of these objects showed that 6 have redshifts similar to that of the radio galaxy. The density of emitters at the redshift of the radio galaxy is estimated to be a factor 1.5-6.2 higher than in the field, and comparable to the density of Lya emitters in radio galaxy protoclusters at z = 4.1, 3.1 and 2.2. The Lya emitters near TN J0924-2201 could therefore be part of a structure that will evolve into a massive cluster. These observations confirm that substantial clustering of Lyα emitters occurs at z > 5 and support the idea that radio galaxies pinpoint high density regions in the early Universe.

Measurement of the production cross section of jets in association with a Z boson in pp collisions at √s = 7 TeV with the ATLAS detector

Abstract: Measurements of the production of jets of particles in association with a Z boson in pp collisions at root s = 7 TeV are presented, using data corresponding to an integrated luminosity of 4.6 fb(-1) collected by the ATLAS experiment at the Large Hadron Collider. Inclusive and differential jet cross sections in Z events, with Z decaying into electron or muon pairs, are measured for jets with transverse momentum p(T) > 30 GeV and rapidity vertical bar y vertical bar < 4.4. The results are compared to next-to-leading-order perturbative QCD calculations, and to predictions from different Monte Carlo generators based on leading-order and next-to-leading-order matrix elements supplemented by parton showers.

Interplay between nonlocality and nonlinearity in nematic liquid crystals.

Abstract: Spatial nonlocality has a crucial role in the optical response of bulk liquid crystals. With specific reference to one-dimensional modulation instability, we demonstrate the tuning of transverse nonlocality in the nonlinear response of nematics.