Quantum ratchets in dissipative chaotic systems

Using the method of quantum trajectories we study a quantum chaotic dissipative ratchet appearing for particles in a pulsed asymmetric potential in the presence of a dissipative environment. The system is characterized by directed transport emerging from a quantum strange attractor. This model exhibits, in the limit of small effective Planck constant, a transition from quantum to classical behavior, in agreement with the correspondence principle. We also discuss parameter values suitable for implementation of the quantum ratchet effect with cold atoms in optical lattices.Comment: Significant changes: Several text improvements and new results. Figure 2 modified. Figure 4 adde

Rotating "Black Holes" with Holes in the Horizon

Kerr-Schild solutions of the Einstein-Maxwell field equations, containing semi-infinite axial singular lines, are investigated. It is shown that axial singularities break up the black hole, forming holes in the horizon. As a result, a tube-like region appears which allows matter to escape from the interior without crossing the horizon. It is argued that axial singularities of this kind, leading to very narrow beams, can be created in black holes by external electromagnetic or gravitational excitations and may be at the origin of astrophysically observable effects such as jet formation.Comment: Revtex, 6 pages, 3 figures. Corrected version. To appear in Phys Rev D, Rapid Communication

CARBOXYLATED-CELLULOSE NANOCRYSTALS PRODUCED FROM LIGNOCELLULOSIC SOURCES AND USED AS BARRIER COATING FOR PET FILMS

The obtainment of Cellulose nanocrystal (CNC) from different cellulosic sources recently gained a great attention due to their physical and mechanical properties. CNC can be extracted from variety of bio-based and renewable sources, such as wood, cotton, bacterial cellulose, tunicate cellulose and softwood cellulose and used as reinforced nanocomposites, functional materials and oxygen-barrier layers. The most important factor affecting the nanocellulose production is the relative proportion of cellulose, hemicellulose, and lignin in the source material. The extraction of CNC from cellulosic materials started with a pre-treatment of biomass involving the complete or partial removal of hemicelluloses, lignin, etc. and isolation of cellulose component. After the separation of matrix materials, controlled hydrolysis of the cellulosic fibers is performed in order to produce colloidal suspensions of cellulose crystals. Using of ammonium persulfate (APS) has recently achieved the obtainment of CNC from different cellulose sources without any pre-treatment. APS, a strong oxidizing agent with high water solubility, is able to produce carboxylated CNC having high crystallinity and active carboxyl groups. The conversion of the carboxylic acid groups to the carboxylate form offers active sites for surface modification and templates for the synthesis of nanoparticles. Incorporation of carboxylated–CNC as a functional layer on different substrates have enhanced the barrier (oxygen permeability), mechanical, optical, and antifog properties of the nanocomposites. The aim of this work was to obtain the CNC from two lignocellulosic sources and to characterize them in terms of morphology, crystallinity, charge density and coating properties in order to use CNC as barrier coating for PET films

On a non-isothermal model for nematic liquid crystals

A model describing the evolution of a liquid crystal substance in the nematic phase is investigated in terms of three basic state variables: the {\it absolute temperature} \teta, the {\it velocity field} \ub, and the {\it director field} \bd, representing preferred orientation of molecules in a neighborhood of any point of a reference domain. The time evolution of the velocity field is governed by the incompressible Navier-Stokes system, with a non-isotropic stress tensor depending on the gradients of the velocity and of the director field \bd, where the transport (viscosity) coefficients vary with temperature. The dynamics of \bd is described by means of a parabolic equation of Ginzburg-Landau type, with a suitable penalization term to relax the constraint |\bd | = 1. The system is supplemented by a heat equation, where the heat flux is given by a variant of Fourier's law, depending also on the director field \bd. The proposed model is shown compatible with \emph{First and Second laws} of thermodynamics, and the existence of global-in-time weak solutions for the resulting PDE system is established, without any essential restriction on the size of the data

Bridging the gap between 3D navigation and semantic search. The INCEPTION platform

The paper presents the main outcomes and future development of the INCEPTION project, “Inclusive Cultural Heritage in Europe through 3D semantic modelling”, funded by the European Commission under the Horizon 2020 Work Programme Europe in a changing world – inclusive, innovative and reflective Societies (Call Reflective-7-2014, Advanced 3D modelling for accessing and understanding European cultural assets) and completed in May 2019. In particular, the key-targeted project achievement will be presented: a specific cloud-based platform conceived to accomplish the main objectives of accessing, understanding and strengthening European Cultural Heritage by means of enriched 3D models. The need for digital data interpretation, in addition to documentation, guided the overall process of the cross-disciplinary work methodology, based on new methods and tools for 3D surveying and H-BIM modelling, new approaches and methodologies for Cultural Heritage 3D data inclusive access and exploitation by means of the Platform

ICTs for Accessing, Understanding and Safeguarding Cultural Heritage: The Experience of INCEPTION and ROCK H2020 Projects

Today digital technologies offer great opportunities in the field of Cultural Heritage (CH). After a general overview of the European policy documents on CH digitisation, the paper aims to reflect on tools, procedures and methodologies in the use of Information and Communication Technologies (ICTs) as a new way of visualization, application and data collection towards accessing, understanding and safeguarding our historic built environment. The focus will be on two ongoing H2020 projects, INCEPTION and ROCK, selected to address the problem of CH digitisation and the access to the corresponding digitized resources in relation to historic buildings and urban districts. Therefore, they are presented as inspiring good practices for tackling this issue considering its impacts both at the architectural and urban scale. Stressing the potentials of enabling technologies, such as 3D laser surveys, environment and climate sensors, large crowd monitoring tools and CH analytic, they are also able to orient future research beyond 2020

Bridging the gap between 3D navigation and semantic search. The INCEPTION platform

The paper presents the main outcomes and future development of the INCEPTION project, “Inclusive Cultural Heritage in Europe through 3D semantic modelling”, funded by the European Commission under the Horizon 2020 Work Programme Europe in a changing world – inclusive, innovative and reflective Societies (Call Reflective-7-2014, Advanced 3D modelling for accessing and understanding European cultural assets) and completed in May 2019. In particular, the key-targeted project achievement will be presented: a specific cloud-based platform conceived to accomplish the main objectives of accessing, understanding and strengthening European Cultural Heritage by means of enriched 3D models. The need for digital data interpretation, in addition to documentation, guided the overall process of the cross-disciplinary work methodology, based on new methods and tools for 3D surveying and H-BIM modelling, new approaches and methodologies for Cultural Heritage 3D data inclusive access and exploitation by means of the Platform

Patch-repetition correlation length in glassy systems

We obtain the patch-repetition entropy Sigma within the Random First Order Transition theory (RFOT) and for the square plaquette system, a model related to the dynamical facilitation theory of glassy dynamics. We find that in both cases the entropy of patches of linear size l, Sigma(l), scales as s_c l^d+A l^{d-1} down to length-scales of the order of one, where A is a positive constant, s_c is the configurational entropy density and d the spatial dimension. In consequence, the only meaningful length that can be defined from patch-repetition is the cross-over length xi=A/s_c. We relate xi to the typical length-scales already discussed in the literature and show that it is always of the order of the largest static length. Our results provide new insights, which are particularly relevant for RFOT theory, on the possible real space structure of super-cooled liquids. They suggest that this structure differs from a mosaic of different patches having roughly the same size.Comment: 6 page

The new scintillating fiber detector of E835 at Fermilab

Abstract The scintillating fiber tracker for the measurement of the polar coordinate θ for experiment E835 at Fermilab has been upgraded, by adding two extra layers (240 fibers each), at R ≈9 cm from the beam axis. Photons from the fibers are detected by Visible Light Photon Counters (VLPCs). The high granularity, flexibility and fast response of the scintillating fibers, combined with the high quantum efficiency of the VLPCs, allow high rate capability, high efficiency, good tracking and time resolution. Signals from the outer two layers are used to provide θ information to the first-level trigger

New mathematical framework for spherical gravitational collapse

A theorem, giving necessary and sufficient condition for naked singularity formation in spherically symmetric non static spacetimes under hypotheses of physical acceptability, is formulated and proved. The theorem relates existence of singular null geodesics to existence of regular curves which are super-solutions of the radial null geodesic equation, and allows us to treat all the known examples of naked singularities from a unified viewpoint. New examples are also found using this approach, and perspectives are discussed.Comment: 8 pages, LaTeX2