A Twin Spiral Planar Antenna for UWB Medical Radars

A planar-spiral antenna to be used in an ultrawideband (UWB) radar system for heart activity monitoring is presented. The antenna, named “twin,” is constituted by two spiral dipoles in a compact structure. The reflection coefficient at the feed point of the dipoles is lower than −8 dB over the 3–12 GHz band, while the two-dipoles coupling is about −20 dB. The radiated beam is perpendicular to the plane of the spiral, so the antenna is wearable and it may be an optimal radiator for a medical UWB radar for heart rate detection. The designed antenna has been also used to check some hypotheses about the UWB radar heart activity detection mechanism. The radiation impedance variation, caused by the thorax vibrations associated with heart activity, seems to be the most likely explanation of the UWB radar operation

Quantum spin Hall effect in bound states in continuum

Moving the polarization of the incident wave along a meridian of the Poincaré sphere, experimentally we show that the coupling with the fundamental Bloch's surface waves of the mode, provide a spatially coherent, macroscopic spinmomentum locked propagation along the symmetry axes of the PhCM. This novel mechanism of light-spin manipulation enables a versatile implementation of spin-optical structures that may pave the way to novel strategies for light spin technology and photonic multiplatform implementations

Regulation of Pharmaceutical Advertising

Federal trade commission regulation of pharmaceutical advertising is a subject of considerable current interest. The criteria for determining the acceptability of these advertisements are still evolving, and a definitive set of rules has not yet been fully articulated. Nevertheless certain trends are developing.\u27 One of the major objectives of this paper is to predict the ultimate form of these rules

Regulation of Pharmaceutical Advertising

Federal trade commission regulation of pharmaceutical advertising is a subject of considerable current interest. The criteria for determining the acceptability of these advertisements are still evolving, and a definitive set of rules has not yet been fully articulated. Nevertheless certain trends are developing.\u27 One of the major objectives of this paper is to predict the ultimate form of these rules

Active macro-zone approach for incremental elastoplastic-contact analysis

The symmetric boundary element method, based on the Galerkin hypotheses, has found an application in the nonlinear analysis of plasticity and in contact-detachment problems, but both dealt with separately. In this paper, we want to treat these complex phenomena together as a linear complementarity problem. A mixed variable multidomain approach is utilized in which the substructures are distinguished into macroelements, where elastic behavior is assumed, and bem-elements, where it is possible that plastic strains may occur. Elasticity equations are written for all the substructures, and regularity conditions in weighted (weak) form on the boundary sides and in the nodes (strong) between contiguous substructures have to be introduced, in order to attain the solving equation system governing the elastoplastic-contact/detachment problem. The elastoplasticity is solved by incremental analysis, called for active macro-zones, and uses the well-known concept of self-equilibrium stress field here shown in a discrete form through the introduction of the influence matrix (self-stress matrix). The solution of the frictionless contact/detachment problem was performed using a strategy based on the consistent formulation of the classical Signorini equations rewritten in discrete form by utilizing boundary nodal quantities as check elements in the zones of potential contact or detachment

Elastoplastic analysis by active macro-zones with linear kinematic hardening and von Mises materials

In this paper a strategy to perform elastoplastic analysis with linear kinematic hardening for von Mises materials under plane strain conditions is shown. The proposed approach works with the Symmetric Galerkin Boundary Element Method applied to multidomain problems using a mixed variables approach, to obtain a more stringent solution. The elastoplastic analysis is carried out as the response to the loads and the plastic strains, the latter evaluated through the self-equilibrium stress matrix. This matrix is used both, in the predictor phase, for trial stress evaluation and, in the corrector phase, for solving a nonlinear global system which provides the elastoplastic solution of the active macro-zones, i.e. those zones collecting bem-elements where the plastic consistency condition has been violated. The simultaneous use of active macro-zones gives rise to a nonlocal approach which is characterized by a large decrease in the plastic iteration number, although the proposed strategy requires the inversion and updating of Jacobian operators generally of big dimensions. A strategy developed in order to reduce the computational efforts due to the use of this matrix, in a recursive process, is shown

A predicative and decidable characterization of the polynomial classes of languages

Characterizations of PTIME, PSPACE, the polynomial hierarchy and its elements are given, which are decidable (membership can be decided by syntactic inspection to the constructions), predicative (according to points of view by Leivant and others), and are obtained by means of increasing restrictions to course-of-values recursion on trees (represented in a dialect of Lisp). (C) 2001 Elsevier Science B.V. All rights reserved