Scuola superiore di Catania

About: Scuola superiore di Catania is a based out in . It is known for research contribution in the topics: Complex network & Graphene. The organization has 103 authors who have published 271 publications receiving 16218 citations.

Fuzzy-based motion estimation for video stabilization using SIFT interest points

Abstract: In this paper we present a technique which infers interframe motion by tracking SIFT features through consecutive frames: feature points are detected and their stability is evaluated through a combination of geometric error measures and fuzzy logic modelling. Our algorithm does not depend on the point detector adopted prior to SIFT descriptor creation: therefore performance have been evaluated against a wide set of point detection algorithms, in order to investigate how to increase stabilization quality with an appropriate detector.

Lateral homogeneity of the electronic properties in pristine and ion-irradiated graphene probed by scanning capacitance spectroscopy

Abstract: In this article, a scanning probe method based on nanoscale capacitance measurements was used to investigate the lateral homogeneity of the electron mean free path both in pristine and ion-irradiated graphene. The local variations in the electronic transport properties were explained taking into account the scattering of electrons by charged impurities and point defects (vacancies). Electron mean free path is mainly limited by charged impurities in unirradiated graphene, whereas an important role is played by lattice vacancies after irradiation. The local density of the charged impurities and vacancies were determined for different irradiated ion fluences.

Direct Higgs-gravity interaction and stability of our universe

Abstract: The Higgs effective potential becomes unstable at approximately $1{0}^{11}\text{ }\text{ }\mathrm{GeV}$, and if only standard model interactions are considered, the lifetime $\ensuremath{\tau}$ of the electroweak vacuum turns out to be much larger than the age of the Universe ${T}_{U}$. It is well known, however, that $\ensuremath{\tau}$ is extremely sensitive to the presence of unknown new physics: the latter can enormously lower $\ensuremath{\tau}$. This poses a serious problem for the stability of our Universe, demanding for a physical mechanism that protects it from a disastrous decay. We have found that there exists a universal stabilizing mechanism that naturally originates from the nonminimal coupling between gravity and the Higgs boson. As this Higgs-gravity interaction necessarily arises from the quantum dynamics of the Higgs field in a gravitational background, this stabilizing mechanism is certainly present. It is not related to any specific model, being rather natural and universal as it comes from fundamental pillars of our physical world: gravity, the Higgs field, and the quantum nature of physical laws.

HERMES: Simulating the propagation of ultra-high energy cosmic rays

Abstract: The study of ultra-high energy cosmic rays (UHECR) at Earth cannot prescind from the study of their propagation in the Universe. In this paper, we present HERMES, the ad hoc Monte Carlo code we have developed for the realistic simulation of UHECR propagation. We discuss the modeling adopted to simulate the cosmology, the magnetic fields, the interactions with relic photons and the production of secondary particles. In order to show the potential applications of HERMES for astroparticle studies, we provide an estimation of the surviving probability of UHE protons, the GZK horizons of nuclei and the all-particle spectrum observed at Earth in different astrophysical scenarios. Finally, we show the expected arrival direction distribution of UHECR produced from nearby candidate sources. A stable version of HERMES will be released in the next future for public use together with libraries of already propagated nuclei to allow the community to perform mass composition and energy spectrum analysis with our simulator.

Influence of cosmological models on the GZK horizon of ultrahigh energy protons

Abstract: We investigate how the density of baryonic and cold dark matter, the density of dark energy and the value of the Hubble parameter at the present time influence the propagation of ultrahigh energy protons in the nearby Universe. We take into account energy losses in the cosmic microwave radiation, the only one relevant for protons above $10^{18}$ eV, and we explore the dependence of Greisen-Zatsepin-Kuz'min (GZK) horizon on the cosmology. We investigate several cosmological scenarios, from matter dominated to energy dominated ones, and we consider the impact of uncertainties in the Hubble parameter in a $\Lambda-$Cold Dark Matter (CDM) Universe, estimated from recent observations, on the GZK horizon. The impact of the (unknown) extragalactic magnetic field on our study is discussed, as well as possible probes of the Hubble parameter attainable by current and future experiments.