Elastic metamaterials have been investigated to achieve negative effective properties, which cannot be found in the conventional elastic medium. In this paper, planewave propagation and reflection in semi-infinite elastic metamaterials with doubly or triply negative material properties are studied analytically and numerically. The unique negative refractions for the longitudinal (P) wave and tr...

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Background: The inconsistent definition of non-therapeutic medication omissions, under-reporting, and a poor understanding of their associated factors hamper efforts to improve medication administration practices. Aim: To examine the incidence of non-therapeutic medication omissions among acutely ill medical and surgical adult patients; and to identify the patient-, drugand system-related predi...

SOCIAL HISTORY OF CANNABIS USE IN NORTH AMERICA Popular use of cannabis by Europeans and North Americans is a phenome-non of the second third of the twentieth century. The development of popular North American use of cannabis does not appear to have begun until the turn of this century in the southern United States. There was a slow spread of use in North America up to the 1950s and 1960s when ...

THEOREM 1. A finite incidence structure is isomorphic to the design of points and hyperplanes of a finite projective or affine space of dimension greater than or equal to 4 if and only if there are positive integers v, k, and y, with ju > 1 and (/A — l)(v — k) 7* (k — ju) such that the following assumptions hold. (I) Every block is on k points, and every two intersecting blocks are on p. common...

We prove almost tight bounds on incidences between points and k-dimensional varieties of bounded degree in R. Our main tools are the Polynomial Ham Sandwich Theorem and induction on both the dimension and the number of points.

Article history: Received 30 June 2008 Available online 10 April 2010 Communicated by Martin Liebeck

We consider the problem of constructing absorbing boundary conditions for the multi-dimensional wave equation. Here we work directly with a difference approximation to the equation, rather than first finding analytical boundary conditions and then discretizing the analytical conditions. This approach yields some simple and effective discrete conditions. These discrete conditions are consistent ...

We discuss the following problem from the theory of regular incidence-polytopes. Given two regular d-incidence-polytopes 9X and !?2 such that the facets of 0>2 °d the vertex-figures of 0\ are isomorphic to some regular (d l)-incidence-polytope 3C, is there a regular (d +1)incidence-polytope X with facets of type ^ and vertex-figures of type &•?. Such amalgamations X of 0\ and 0*2 along 3iT exis...

Objective: To determine the incidence and types of associated anomalies in children with anorectal