285 research outputs found
Advances in YBa2Cu3O7-delta grain boundary biepitaxial Josephson junctions: Transport properties and mesoscopic effects
No full textWe report on the latest developments in the study of transport properties of YBa2CU3O7-delta (YBCO)-based grain boundary (GB) biepitaxial Josephson junctions. We have successfully extended the fabrication process s,. originally developed for (110) oriented SrTiO3 substrates, to (110) oriented LaAlO3 substrates in view of microwave applications. We will report, also, on the observation of conductance fluctuations, we believe related to the coherent diffusion of quasi-particles across the GB. These results, together with the recent observation of macroscopic quantum tunneling and energy level quantization in these Junctions, could help cast some light on the mechanism involved in transport across grain boundaries and in revising the role and the effect of quasi particles in d-wave transport
Mesoscopic conductance fluctuations in high-T-c grain boundary Josephson junctions: Coherent quasiparticle transport
No full textMagneto-fluctuations of the normal resistance RN have been reproducibly observed in YBa2Cu3O7-delta (HTS) biepitaxial grain boundary junctions at low temperatures. We attribute them to mesoscopic transport in narrow channels across the grain boundary line. The Thouless energy appears to be the relevant energy scale. Possible implications on the understanding of coherent transport of quasiparticles in HTS and of the dissipation mechanisms are discussed. (c) 2007 Elsevier B.V. All rights reserved
Alle origini della conquista dell’Italia meridionale: Arduino e l’entrata dei Normanni a Melfi
No full textIl contributo analizza le fonti inerenti l'entrata dei Normanni a Melfi e la relazione esistente tra Impero, Normanni e Regno d'Italia attraverso la figura del milanese Arduino
The motor skills of early Neolithic potters: 3-D kinematics traces the origins of a new expertise
No full textopenIl presente elaborato si inserisce nella ricerca "Becoming an Expert" condotta in collaborazione con il Dipartimento di Beni Culturali (DBC) dell'Università di Padova. L’esperimento preso in esame intendeva testare l'acquisizione delle abilità motorie relative alla lavorazione della ceramica attraverso l'analisi cinematica 3-D del movimento. Ai partecipanti veniva chiesto di eseguire azioni di rifinitura di una ciotola d’argilla grezza con l’uso di una spatola preposta allo scopo. Sulla mano destra venivano applicati dei markers passivi riflettenti l’infrarosso, la cui posizione nello spazio e nel tempo veniva registrata da sei telecamere digitali. Le misurazioni sono state effettuate sia su un gruppo sperimentale che su un gruppo di controllo, in due sessioni a distanza di due mesi. Solo il gruppo sperimentale ha svolto un training tra le due sessioni, durante il quale ha appreso le tecniche di lavorazione della ceramica adottate dai primi vasai del Neolitico. Attraverso il confronto tra i due gruppi nel pre- e post-training, si intendeva verificarne l'efficacia nell'acquisizione delle abilità motorie che hanno segnato la nascita di una nuova competenza. Coerentemente con le nostre ipotesi, i risultati hanno mostrato un miglioramento nella sessione successiva al training, limitato al gruppo sperimentale
Underlying physical aspects of fluctuations in YBa 2 Cu 3 O 7- grain boundary Josephson junctions
No full textHigh quality YBa2Cu3O7d biepitaxial grain boundary junctions allowed one of the first evidences of macroscopic quantum behavior
and mesoscopic transport in high critical temperature superconductors (HTS) systems. Both these studies touch delicate issues on fluctuations
and give important feedback on the understanding of coherent transport of quasiparticles and of the dissipation mechanisms in
HTS
System-level design tool for switched capacitor DC-DC energy scavenging converters
No full textThis thesis deals with the system modelling and design of a Switched Capacitor DC-DC (SC DC-DC) nano-power converter in Complementary Metal Oxide Semiconductor (CMOS) technology for energy harvesting applications.
First of all, after a critical evaluation on the whole Integrated Circuit (IC) system structure, a Python script has been created in order to accurately analyse any system analytical behaviours before instantiating and running the Cadence usual simulations.
The code is an upgrade with respect to a pre-existing one ([1]): several comparisons are listed and explained to show the differences between the two, as well as stressing on our new dedicated features.
In order to validate the model on the code, then, a feasibility study has been performed with a 180 nm United Microelectronics Corporation (UMC) technology process in the Cadence Virtuoso design suite. Good results let us state its reliability in being used both for the most of SC DC-DC architectures pre-design analysis and post-design verification: a full design space exploration shows how to use the script.
Finally, the SC DC-DC circuit D for bluetooth applications that we present uses the Taiwan Semiconductor Manufacturing Company (TSMC) 55 nm technology process and its design has been mostly realized by Luca Intaschi, during his PhD, and Francesco Dalena from Dialog Semiconductor in Livorno. The circuit D converter is meant to be part of a sensor node (that needs to survive in total absence of battery recharge) supplied by a Thermo Electric Generator (TEG) which guarantees a very low input voltage to the system of about 0.2 - 0.25 V. Our work on it has focused on looking for an upgrade in order to increase its Power Conversion Efficiency (PCE). A new design which is able to properly work has been simulated and we provide some insight and constraints for future following upgrades
Measurements of Spectrally Averaged Absorptivity and Emissivity for a Selective Solar Absorber in High Vacuum under Direct Solar Illumination
No full textThe innovative ultra-high vacuum technology applied to solar thermal flat panels, allows to reach high operating temperatures (up to 200 °C) without concentration, cutting out both convective and conductive thermal losses of the internal gas. The system losses are mainly due to the radiative energy emitted by the absorber. In this paper, a power balance equation has been used to perform the best fit of the data recorded with the absorber first exposed to the Sun illumination (up to the stagnation temperature, typically above 300 °C) and then cooled down by using an opaque shield. In particular, the fitting procedure is useful to evaluate the spectrally averaged absorptivity and the temperature dependent spectrally averaged emissivity of the absorber in a realistic operating condition
Development of diagnostic tools for quantitative detection of Apiospora marii using qPCR and ddPCR technologies
No full textApiospora marii (sin. Arthrinium marii) is an ascomycete recently associated with olive tree dieback in Italy and Spain. With this study, quantitative (q)PCR and digital droplet (dd)PCR protocols were developed and validated to detect and quantify A. marii. Two primers/probe sets (AM135 and AM158) were designed on the ITS sequences of the fungus. The optimization of the PCR conditions allowed to identify 60 °C as the best annealing temperature and 500/250 nM as the best primers/probe concentration in both qPCR and ddPCR. Under these conditions, up to 1 fg μL-1 of DNA of the A. marii DiSSPA_A1 was detected in qPCR (Cq=34 for both AM135 and AM158). The same DNA concentration was the lowest one detected in ddPCR after 40 cycles of amplification and corresponded to 0.20 and 0.12 DNA copies μL-1,
respectively for AM135 and AM158. The specificity of both primer/probe sets was tested against a panel of microorganisms commonly associated with olive wood of several olive varieties. Untargeted amplifications were observed after 35 cycles, using the DNA of Armillaria mellea, Pseudophaeomoniella oleae, and Verticillium dahliae, and in accordance
with the qPCR – LoD was Cq 35. For the assay validation, healthy and A. marii artificially-inoculated olive plants were analysed simultaneously in qPCR assay and on potato dextrose agar medium, confirming a sound performance of the qPCR assay. Results achieved in this work let to improve monitoring and surveillance of this new olive pathogen
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