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Search Results: 1 - 10 of 167631 matches for " E. Monticone "
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High intrinsic energy resolution photon number resolving detectors
L. Lolli,E. Taralli,C. Portesi,E. Monticone,M. Rajteri
Physics , 2013,
Abstract: Transition Edge Sensors (TESs) are characterized by the intrinsic figure of merit to resolve both the energy and the statistical distribution of the incident photons. These properties lead TES devices to become the best single photon detector for quantum technology experiments. For a TES based on titanium and gold has been reached, at telecommunication wavelength, an unprecedented intrinsic energy resolution (0.113 eV). The uncertainties analysis of both energy resolution and photon state assignment has been discussed. The thermal properties of the superconductive device have been studied by fitting the bias curve to evaluate theoretical limit of the energy resolution.
Development of new assessment tools in physical medicine and rehabilitation: A challenge to current research
Monticone Marco
Indian Journal of Medical Sciences , 2009,
Fabrication and electrical characterization of three-dimensional graphitic microchannels in single crystal diamond
F. Picollo,D. Gatto Monticone,P. Olivero,B. A. Fairchild,S. Rubanov,S. Prawer,E. Vittone
Physics , 2012, DOI: 10.1088/1367-2630/14/5/053011
Abstract: We report on the systematic characterization of conductive micro-channels fabricated in single-crystal diamond with direct ion microbeam writing. Focused high-energy (~MeV) helium ions are employed to selectively convert diamond with micrometric spatial accuracy to a stable graphitic phase upon thermal annealing, due to the induced structural damage occurring at the end-of-range. A variable-thickness mask allows the accurate modulation of the depth at which the microchannels are formed, from several {\mu}m deep up to the very surface of the sample. By means of cross-sectional transmission electron microscopy (TEM) we demonstrate that the technique allows the direct writing of amorphous (and graphitic, upon suitable thermal annealing) microstructures extending within the insulating diamond matrix in the three spatial directions, and in particular that buried channels embedded in a highly insulating matrix emerge and electrically connect to the sample surface at specific locations. Moreover, by means of electrical characterization both at room temperature and variable temperature, we investigate the conductivity and the charge-transport mechanisms of microchannels obtained by implantation at different ion fluences and after subsequent thermal processes, demonstrating that upon high-temperature annealing, the channels implanted above a critical damage density convert to a stable graphitic phase. These structures have significant impact for different applications, such as compact ionizing radiation detectors, dosimeters, bio-sensors and more generally diamond-based devices with buried three-dimensional all-carbon electrodes.
Effective gap at microwave frequencies in MgB2 thin films with strong interband scattering
G. Ghigo,D. Botta,A. Chiodoni,L. Gozzelino,R. Gerbaldo,F. Laviano,E. Mezzetti,E. Monticone,C. Portesi
Physics , 2005, DOI: 10.1103/PhysRevB.71.214522
Abstract: The microwave properties of polycrystalline MgB2 thin films prepared by the so-called in-situ method are investigated. The characterization of the films at microwave frequencies was obtained by a coplanar resonator technique. The analysis of the experimental data results in the determination of penetration depth, surface impedance and complex conductivity. The aim of this work is to set the experimental results in a consistent framework, involving the two-band model in the presence of impurity scattering. The energy gaps are calculated and the contribution of intra- and inter-band scattering is considered. From the comparison between the calculated gap values and the experimental data it turns out that the temperature dependence of the penetration depth can be accounted for by an effective mean energy gap, in agreement with the predictions of Kogan et al. [Phys. Rev. B 69, 132506 (2004)]. On the other hand, the temperature dependence of the real part of the microwave conductivity and of the surface resistance is accounted for by the single smaller gap, in agreement with the work of Jin et al. [Phys. Rev. Lett. 91, 127006 (2003)]. Since these findings rely on the same calculated gap structure, the required consistency is fulfilled.
Do Cloaked Objects Really Scatter Less?
Francesco Monticone,Andrea Alu
Physics , 2013,
Abstract: We discuss the global scattering response of invisibility cloaks over the entire frequency spectrum, from static to very high frequencies. Based on linearity, causality and energy conservation we show that the total extinction and scattering, integrated over all wavelengths, of any linear, passive, causal and non-diamagnetic cloak necessarily increases compared to the uncloaked case. In light of this general principle, we provide a quantitative measure to compare the global performance of different cloaking techniques and we discuss solutions to minimize the global scattering signature of an object using thin, superconducting shells. Our results provide important physical insights on how invisibility cloaks operate and affect the global scattering of an object, suggesting ways to defeat countermeasures aimed at detecting cloaked objects using short impinging pulses.
A Local Proinflammatory Signalling Loop Facilitates Adverse Age-Associated Arterial Remodeling
Mingyi Wang,Gaia Spinetti,Robert E. Monticone,Jing Zhang,James Wu,Liqun Jiang,Benjamin Khazan,Richard Telljohann,Edward G. Lakatta
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0016653
Abstract: The coincidence of vascular smooth muscle cells (VSMC) infiltration and collagen deposition within a diffusely thickened intima is a salient feature of central arterial wall inflammation that accompanies advancing age. However, the molecular mechanisms involved remain undefined.
Increased Aortic Calpain-1 Activity Mediates Age-Associated Angiotensin II Signaling of Vascular Smooth Muscle Cells
Liqun Jiang, Mingyi Wang, Jing Zhang, Robert E. Monticone, Richard Telljohann, Gaia Spinetti, Gianfranco Pintus, Edward G. Lakatta
PLOS ONE , 2008, DOI: 10.1371/journal.pone.0002231
Abstract: Background Angiotensin II (Ang II) signaling, including matrix metalloproteinase type II (MMP2) activation, has been linked to an age-associated increase in migration capacity of vascular smooth muscle cells (VSMC), and to other proinflammatory features of arterial aging. Calpain-1 activation is required for MMP2 expression in fibroblasts and is induced in cardiomyocytes by Ang II. The consequences of engagement of calpain-1 with its substrates, however, in governing the age-associated proinflammatory status within the arterial wall, remains unknown. Methodology/Principal Findings The present findings demonstrate that transcription, translation, and activity of calpain-1 are significantly up-regulated in rat aortae or early-passage aortic VSMC from old (30-mo) rats compared to young (8-mo). Dual immunolabeling of the arterial wall indicates that colocalization of calpain-1 and Ang II increases within the aged arterial wall. To further explore the relationship of calpain-1 to Ang II, we chronically infused Ang II into young rats, and treated cultured aortic rings or VSMC with Ang II. We also constructed adenoviruses harboring calpain-1 (CANP1) or its endogenous inhibitor calpastatin (CAST) and infected these into VSMC. Ang II induces calpain-1 expression in the aortic walls in vivo and ex vivo and VSMC in vitro. The Ang II mediated, age-associated increased MMP2 activity and migration in VSMC are both blocked by calpain inhibitor 1 or CAST. Over-expression of calpain-1 in young VSMC results in cleavage of intact vimentin, and an increased migratory capacity mimicking that of old VSMC, which is blocked by the MMP inhibitor, GM6001. Conclusions/Significance Calpain-1 activation is a pivotal molecular event in the age-associated arterial Ang II/MMP2 signaling cascade that is linked to cytoskeleton protein restructuring, and VSMC migration. Therefore, targeting calpain-1 has the potential to delay or reverse the arterial remodeling that underlies age-associated diseases i.e. atherosclerosis.
Systematic study of defect-related quenching of NV luminescence in diamond with time correlated single photon counting spectroscopy
D. Gatto Monticone,F. Quercioli,R. Mercatelli,S. Soria,S. Borini,T. Poli,M. Vannoni,E. Vittone,P. Olivero
Physics , 2013, DOI: 10.1103/PhysRevB.88.155201
Abstract: We report on the systematic characterization of photoluminescence (PL) lifetimes in NV- and NV0 centers in 2 MeV H+ implanted type Ib diamond samples by means of a time correlated single photon counting (TCSPC) microscopy technique. A dipole-dipole resonant energy transfer model was applied to interpret the experimental results, allowing a quantitative correlation of the concentration of both native (single substitutional nitrogen atoms) and ion-induced (isolated vacancies) PL-quenching defects with the measured PL lifetimes. The TCSPC measurements were carried out in both frontal (i.e. laser beam probing the main sample surface along the same normal direction of the previously implanted ions) and lateral (i.e. laser beam probing the lateral sample surface orthogonally with respect to the same ion implantation direction) geometries. In particular, the latter geometry allowed a direct probing of the centers lifetime along the strongly nonuniform damage profiles of MeV ions in the crystal. The extrapolation of empirical quasi-exponential decay parameters allowed the systematic estimation of the mean quantum efficiency of the centers as a function of intrinsic and ion-induced defect concentration, which is of direct relevance for the current studies on the use of diamond color centers for photonic applications.
Self consistent, absolute calibration technique for photon number resolving detectors
A. Avella,G. Brida,I. P. Degiovanni,M. Genovese,M. Gramegna,L. Lolli,E. Monticone,C. Portesi,M. Rajteri,M. L. Rastello,E. Taralli,P. Traina,M. White
Physics , 2011, DOI: 10.1364/OE.19.023249
Abstract: Well characterized photon number resolving detectors are a requirement for many applications ranging from quantum information and quantum metrology to the foundations of quantum mechanics. This prompts the necessity for reliable calibration techniques at the single photon level. In this paper we propose an innovative absolute calibration technique for photon number resolving detectors, using a pulsed heralded photon source based on parametric down conversion. The technique, being absolute, does not require reference standards and is independent upon the performances of the heralding detector. The method provides the results of quantum efficiency for the heralded detector as a function of detected photon numbers. Furthermore, we prove its validity by performing the calibration of a Transition Edge Sensor based detector, a real photon number resolving detector that has recently demonstrated its effectiveness in various quantum information protocols.
Point-Contact Spectroscopy in MgB_2: from Fundamental Physics to Thin-Film Characterization
R. S. Gonnelli,D. Daghero,A. Calzolari,G. A. Ummarino,V. Dellarocca,V. A. Stepanov,S. M. Kazakov,J. Karpinski,C. Portesi,E. Monticone,V. Ferrando,C. Ferdeghini
Physics , 2003, DOI: 10.1088/0953-2048/17/5/001
Abstract: In this paper we highlight the advantages of using point-contact spectroscopy (PCS) in multigap superconductors like MgB_2, both as a fundamental research tool and as a non-destructive diagnostic technique for the optimization of thin-film characteristics. We first present some results of crucial fundamental interest obtained by directional PCS in MgB_2 single crystals, for example the temperature dependence of the gaps and of the critical fields and the effect of a magnetic field on the gap amplitudes. Then, we show how PCS can provide useful information about the surface properties of MgB_2 thin films (e.g. Tc, gap amplitude(s), clean or dirty-limit conditions) in view of their optimization for the fabrication of tunnel and Josephson junctions for applications in superconducting electronics.
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