Curious Skin

Some of Henry Wellcome’s collection of tattoos on human skin will be on display in our forthcoming Skin exhibition. But how did the Parisian doctor from whom they were acquired come by his macabre collection of tattoos in the first place, and what did they mean to those whose skin they were on? It’s Gemma Angel‘s job to find out

Visualizing Rotations and Composition of Rotations with Rodrigues' Vector

The purpose of this paper is to show that the mathematical treatment of three dimensional rotations can be simplified, and its geometrical understanding improved, by using the Rodrigues' vector representation. We present a novel geometrical interpretation of the Rodrigues' vector. Based on this interpretation and simple geometrical considerations, we derive Euler Rodrigues' formula, Cayley's rotation formula, and the composition law for finite rotations. The level of this discussion should be suitable for undergraduate physics or engineering courses where rotations are discussed.Comment: 12 pages, 7 figure

Reply to Comment on "Existence of Internal Modes of sine-Gordon Kinks"

In this reply to the comment by C. R. Willis, we show, by quoting his own statements, that the simulations reported in his original work with Boesch [Phys. Rev. B 42, 2290 (1990)] were done for kinks with nonzero initial velocity, in contrast to what Willis claims in his comment. We further show that his alleged proof, which assumes among other approximations that kinks are initially at rest, is not rigorous but an approximation. Moreover, there are other serious misconceptions which we discuss in our reply. As a consequence, our result that quasimodes do not exist in the sG equation [Phys. Rev. E 62, R60 (2000)] remains true.Comment: Reply to a comment by C. R. Willis on Phys. Rev. E 62, R60 (2000), to appear in Physical Review

Monetary Policy Targeting in Argentina and Canada in the 1990s: A Comparison, Some Contrasts, and a Tentative Evaluation

There are two generally accepted ways of plotting the aggregate demand (AD) and aggregate supply (AS) curves in the goods market. One puts the price level on the vertical axis (the P - y approach); the other plots the real interest rate on the vertical axis (the r - y approach). This paper develops the theoretical connections between these two approaches that permit one to tell a coherent dynamic story with the AD-AS model and also explores the conditions under which one approach or the other yields greater insight into the working of the model.Monetary Policy; Monetary; Policy