The phase diagram of the three-dimensional Z2 gauge Higgs system at zero and finite temperature

We study the effect of adding a matter field to the Z2 gauge model in three dimensions at zero and finite temperature. Up to a given value of the parameter regulating the coupling, the matter field produces a slight shift of the transition line without changing the universality class of the pure gauge theory, as seen by finite size scaling analysis or by comparison, in the finite temperature case, to exact formulas of conformal field theory. At zero temperature the critical line turns into a first-order transition. The fate of this kind of transition in the finite temperature case is discussed.Comment: 6 pages, 10 figures, based on a poster by AR and a talk by FG at Lattice2002(higgssusy

Confinement-deconfinement and universal string effects from random percolation

The 't Hooft criterion leading to confinement out of a percolating cluster of central vortices suggests defining a novel three-dimensional gauge theory directly on a random percolation process. Wilson loop is viewed as a counter of topological linking with the random clusters. Beyond the percolation threshold large Wilson loops decay with an area law and show the universal shape effects due to flux tube fluctuations. Wilson loop correlators define a non-trivial glueball spectrum. The crumbling of the percolating cluster when one periodic direction narrows accounts for the finite temperature deconfinement, which belongs to 2D percolation universality class.Comment: 3 pages, Lattice2003(topology

Time Domain Analysis of Elastic Nonlinearity in Concrete Using Continuous Waves

Concrete and consolidated granular media in general exhibit a strong nonlinear hysteretic elastic behavior when excited by ultrasonic wave perturbations. Due to the sensitivity of their elastic properties to the small changes that can appear in their microstructure, the dynamic stress-strain relationship considered at low strains is affected by the presence of microcracks and hence the progression of damage. Tracking the nonlinear behavior can be made through the dependence on the excitation amplitude of the amplitude of higher order harmonics or of the resonance frequency of the sample. The present chapter shows a time domain analysis of elastic nonlinearity based on the break of the superposition principle when ultrasonic continuous waves are propagating in concrete samples. The latter, which can be of different microstructures (grain sizes, mortar, or polymer matrix), helps to understand the physical mechanisms involved in the different nonlinear elastic responses

Reasoning about Typicality and Probabilities in Preferential Description Logics

In this work we describe preferential Description Logics of typicality, a nonmonotonic extension of standard Description Logics by means of a typicality operator T allowing to extend a knowledge base with inclusions of the form T(C) v D, whose intuitive meaning is that normally/typically Cs are also Ds. This extension is based on a minimal model semantics corresponding to a notion of rational closure, built upon preferential models. We recall the basic concepts underlying preferential Description Logics. We also present two extensions of the preferential semantics: on the one hand, we consider probabilistic extensions, based on a distributed semantics that is suitable for tackling the problem of commonsense concept combination, on the other hand, we consider other strengthening of the rational closure semantics and construction to avoid the so-called blocking of property inheritance problem.Comment: 17 pages. arXiv admin note: text overlap with arXiv:1811.0236

Ultrasonic Monitoring of the Interaction between Cement Matrix and Alkaline Silicate Solution in Self-Healing Systems

Alkaline solutions, such as sodium, potassium or lithium silicates, appear to be very promising as healing agents for the development of encapsulated self-healing concretes. However, the evolution of their mechanical and acoustic properties in time has not yet been completely clarified, especially regarding their behavior and related kinetics when they are used in the form of a thin layer in contact with a hardened cement matrix. This study aims to monitor, using linear and nonlinear ultrasonic methods, the evolution of a sodium silicate solution interacting with a cement matrix in the presence of localized cracks. The ultrasonic inspection via linear methods revealed that an almost complete recovery of the elastic and acoustic properties occurred within a few days of healing. The nonlinear ultrasonic measurements contributed to provide further insight into the kinetics of the recovery due to the presence of the healing agent. A good regain of mechanical performance was ascertained through flexural tests at the end of the healing process, confirming the suitability of sodium silicate as a healing agent for self-healing cementitious systems

Percutaneous Mechanical Circulatory Support Devices: Systems and Clinical Options

Cardiogenic shock (CS) still remains a leading cause of hospital death. The adoption of percutaneous ventricular assist devices (pVADs) as treatment of CS is an option which continues to rise. Several types of pVADs have been developed by time to provide full cardiac support with few related complications and easy implantation settings. pVADs are used to support the failing heart as a bridge to recovery, decision, durable device or heart transplantation. None of these devices adopted in the clinical practice is ideal for all patients. Disadvantages may be related to the risk of limb/arm ischaemia or cerebral stroke or haemolysis. The most important choice is to identify the best device for each patient depending on haemodynamics, clinical scenario and patient anatomical/pathological issues. This chapter discusses the current pVAD options to treat CS patients

Tunable photo-responsive elastic metamaterials

The metamaterial paradigm has allowed an unprecedented space-time control of various physical fields, including elastic and acoustic waves. Despite the wide variety of metamaterial configurations proposed so far, most of the existing solutions display a frequency response that cannot be tuned, once the structures are fabricated. Few exceptions include systems controlled by electric or magnetic fields, temperature, radio waves and mechanical stimuli, which may often be unpractical for real-world implementations. To overcome this limitation, we introduce here a polymeric 3D-printed elastic metamaterial whose transmission spectrum can be deterministically tuned by a light field. We demonstrate the reversible doubling of the width of an existing frequency band gap upon selective laser illumination. This feature is exploited to provide an elastic-switch functionality with a one-minute lag time, over one hundred cycles. In perspective, light-responsive components can bring substantial improvements to active devices for elastic wave control, such as beam-splitters, switches and filters