Illusions and Cloaks for Surface Waves

Open access articleEver since the inception of Transformation Optics (TO), new and exciting ideas have been proposed in the field of electromagnetics and the theory has been modified to work in such fields as acoustics and thermodynamics. The most well-known application of this theory is to cloaking, but another equally intriguing application of TO is the idea of an illusion device. Here, we propose a general method to transform electromagnetic waves between two arbitrary surfaces. This allows a flat surface to reproduce the scattering behaviour of a curved surface and vice versa, thereby giving rise to perfect optical illusion and cloaking devices, respectively. The performance of the proposed devices is simulated using thin effective media with engineered material properties. The scattering of the curved surface is shown to be reproduced by its flat analogue (for illusions) and vice versa for cloaks.Engineering and Physical Sciences Research Council (EPSRC

Effects of Methanethiol on Erythrocyte Membrane Stabilization and on Na ,K -Adenosine Triphosphatase: Relevance to Hepatic Coma1

ABSTRACT This property of CH3SH is in common with other anesthetic agents. Anesthetic agents also inhibit the membrane-associated Na ,K -adenosine triphosphatase (ATPase); however, for effective and nontoxic agents of this type the inhibition of ATPase activity is elicited at concentrations which are at least an order of magnitude higher than those which influence the membrane stability characterized by the antihemolysis effect (P. Seeman, Pharmacol

Erythrocyte Na+, K+-ATPase and serum digoxin concentrations

Digoxin therapy has been made more rational by the measurement of serum digoxin concentrations. However, difficulties remain because of the overlap between "therapeutic" and "toxic" serum concentrations and the lack of an obvious therapeutic endpoint in many patients. An assay which measures the degree of interaction between digoxin and its putative receptor, the membrane Na+, K+-ATPase, might be capable of resolving some of these difficulties. Therefore, as a first approach in this direction we evaluated the relationship between serum digoxin concentration and the degree of inhibition of RBC ghost Na+, K+-ATPase activity in patients receiving digoxin therapy. Utilizing an improved micro-assay technique, Na+, K+-ATPase activity was determined in aliquots of RBC ghosts before and after removal of bound digoxin. In 27 patients a significant relationship was present between serum digoxin concentration and the degree of RBC ghost Na+, K+-ATPase inhibition. However, at any serum digoxin concentration, there was a variation in the magnitude of enzyme inhibition from patient to patient. This study confirms the feasibility of determining the degree of in vivo RBC Na+, K+-ATPase inhibition in man and demonstrates, for the first time, a highly significant but somewhat variable relationship between serum digoxin concentrations and the magnitude of RBC digoxin receptor inactivation. This quantitative, functional, individualized assay of digoxin effects may prove to be of clinical value in the future

Metasurface antennas

International audienceThis chapter reports design and analysis methods for planar antennas based on modulated metasurfaces (MTSs). These antennas transform a surface wave (SW) into a leaky wave by means of the interaction with a MTS having a spatially modulated equivalent impedance. The basic concept is that the MTS imposes the impedance boundary conditions (BCs) seen by the SW, and therefore the MTS controls amplitude, phase, and polarization of the aperture field. Thus, MTS antennas are highly customizable in terms of their performances, by simply changing the MTS and without affecting the overall structure. Several technological solutions can be adopted to implement the MTS, from sub-wavelength patches printed on a grounded slab at microwave frequencies, to a bed of nails structure in the millimetre and sub-millimetre wave range in any case, the resulting device has light weight and a low profile. The design of the MTS is based on a generalized form of the Floquet wave theorem adiabatically applied to curvilinear locally periodic BCs. The design defines the continuous BCs required for reproducing a desired aperture field, and it is verified by a fast full-wave solver for impedance BCs. Next, the continuous BCs are discretized and implemented by a distribution of electrically small printed metallic elements in a regular lattice, like pixels in an image. The final layout is composed of tens of thousands of pixels and it is analyzed by a full-wave solver which makes use of entire domain basis functions combined with a fast-multipole algorithm. Examples of design and realizations of MTS antennas are shown, proving the effectiveness of the concept. © Springer International Publishing AG 2018