Transfer Matrix Analysis of the Unidirectional Grating-Assisted Codirectional Coupler

The unidirectional grating-assisted codirectional coupler (U-GACC) has recently been proposed. This unique structure permits irreversible coupling between orthogonal waveguide eigenmodes by means of simultaneous modulation of both the real and imaginary parts of the refractive index in the coupling region. Analysis of the U-GACC has until now relied on coupled mode theory, which can be restrictive in its application as a design tool. We analyze the U-GACC by the transfer matrix method, which demonstrates in a simple fashion why the device operates in a unidirectional manner. In addition, we show that for all practical designs, there is a limit to the minimum cross talk between outputs, a phenomenon that has not been previously identified

Representations of G+++ and the role of space-time

We consider the decomposition of the adjoint and fundamental representations of very extended Kac-Moody algebras G+++ with respect to their regular A type subalgebra which, in the corresponding non-linear realisation, is associated with gravity. We find that for many very extended algebras almost all the A type representations that occur in the decomposition of the fundamental representations also occur in the adjoint representation of G+++. In particular, for E8+++, this applies to all its fundamental representations. However, there are some important examples, such as An+++, where this is not true and indeed the adjoint representation contains no generator that can be identified with a space-time translation. We comment on the significance of these results for how space-time can occur in the non-linear realisation based on G+++. Finally we show that there is a correspondence between the A representations that occur in the fundamental representation associated with the very extended node and the adjoint representation of G+++ which is consistent with the interpretation of the former as charges associated with brane solutions.Comment: 45 pages, 9 figures, 9 tables, te

Diffeomorphism, kappa transformations and the theory of non-linear realisations

We will show how the theory of non-linear realisations can be used to naturally incorporate world line diffeomorphisms and kappa transformations for the point particle and superpoint particle respectively. Similar results also hold for a general p-brane and super p-brane, however, we must in these cases include an additional Lorentz transformation.Comment: 19pages, no figure. References are added and typos are correcte

Measuring physiological influence in dyads: A guide to designing, implementing, and analyzing dyadic physiological studies.

Scholars across domains in psychology, physiology, and neuroscience have long been interested in the study of shared physiological experiences between people. Recent technological and analytic advances allow researchers to examine new questions about how shared physiological experiences occur. Yet comprehensive guides that address the theoretical, methodological, and analytic components of studying these processes are lacking. The goal of this article is to provide such a guide. We begin by addressing basic theoretical issues in the study of shared physiological states by presenting five guiding theoretical principles for making psychological inferences from physiological influence-the extent to which one dyad member's physiology predicts the other dyad member's physiology at a future time point. Second, keeping theoretical and conceptual concerns at the forefront, we outline considerations and recommendations for designing, implementing, and analyzing dyadic psychophysiological studies. In so doing, we discuss the different types of physiological measures one could use to address different theoretical questions. Third, we provide three illustrative examples in which we estimate physiological influence, using the stability and influence model. We conclude by providing detail about power analyses for the model and by comparing the strengths and limitations of this model with preexisting models. (PsycINFO Database Record (c) 2018 APA, all rights reserved)

A review of the influence of physical condition parameters on a typical aerospace stress effect: Decompression sickness

The study examines data on episodes of decompression sickness, particularly from recent Navy work in which the event occurred under multiple stress conditions, to determine the extent to which decompression sickness might be predicted on the basis of personal characteristics such as age, weight, and physical condition. Such information should ultimately be useful for establishing medical selection criteria to screen individuals prior to participation inactivities involving extensive changes in ambient pressure, including those encountered in space operations. The main conclusions were as follows. There is a definite and positive relationship between increasing age and weight and the likelihood of decompression sickness. However, for predictive purposes, the relationship is low. To reduce the risk of bends, particularly for older individuals, strenuous exercise should be avoided immediately after ambient pressure changes. Temperatures should be kept at the low end of the comfort zone. For space activities, pressure changes of over 6-7 psi should be avoided. Prospective participants in future missions such as the Space Shuttle should not be excluded on the basis of age, certainly to age 60, if their general condition is reasonably good and they are not grossly obese. (Modified author abstract

E_11 and M Theory

We argue that eleven dimensional supergravity can be described by a non-linear realisation based on the group E_{11}. This requires a formulation of eleven dimensional supergravity in which the gravitational degrees of freedom are described by two fields which are related by duality. We show the existence of such a description of gravity.Comment: 21 pages, some typos corrected and two references adde