The projection dynamic, the replicator dynamic and the geometry of population games

Every population game defines a vector field on the set of strategy distributions X. The projection dynamic maps each population game to a new vector field: namely, the one closest to the payoff vector field among those that never point outward from X. We investigate the geometric underpinnings of the projection dynamic, describe its basic game-theoretic properties, and establish a number of close connections between the projection dynamic and the replicator dynamic

Single coronary artery incidence in 215,140 patients undergoing coronary angiography

Background: The aim of our study is to determine the incidence of single coronary artery (SCA). SCA is a rarely seen coronary anomaly in which the right coronary artery and the left main coronary artery arise from single aortic sinus. Although SCA has a benign course in most cases and its clinical significance is unknown, in some autopsy studies it was shown to be related to sudden cardiac death. Materials and methods: SCA patients detected among 215,140 coronary angiographies (CAG) performed between 1998 and 2013 in SANKO Hospital were included in our study. The classification of CAG was made according to the two different classifications defined by Smith and Lipton and colleagues. Results: A total number of 215,140 patients who underwent routine CAG were included in the study, and SCA was detected in 67 (0.031%) patients. There were 6 (9%) type R-I, 23 (34%) type R-II, 10 (15%) type R-III, 16 (24%) type L-I and 12 (18%) type L-II patients according to the angiographic classification. Conclusions: SCA is rarely seen during routine cardiac catheterisation and its incidence is 0.014–0.066% in angiographic series. In our study, the incidence was shown to be similar to the previous studies.

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Matrizant approach to acoustic analysis of perforated multiple pipe mufflers carrying mean flow

A new method based on the matrizant theory is developed for acoustic analysis of perforated pipe muffler components. The analysis is presented in a generality encompassing any number of parallel pipes that communicate along a common length. The utility and potential of the method is demonstrated on a plug muffler and a reverse flow muffler. The analysis shows, for the first time, that the distributed parameter theory of plane wave propagation in a perforated pipe provides a more satisfactory setting than the segmentation method for the analysis of the effects of axially varying quantities such as the mean how velocity. The effect of the mean flow velocity gradient on the transmission loss of the plug and reversed flow mufflers are computed and are shown to be insignificant for practical purposes. (C) 1996 Academic Press Limite

An exact transfer matrix formulation of plane sound wave transmission in inhomogeneous ducts

The impedance, or the reflection coefficient, of plane sound waves in inhomogeneous ducts satisfies a Riccati equation. The present paper shows that the duct impedance matrix, or the scattering matrix, can be related explicitly to the solutions of the associated linear equation of the Riccati equation for duct impedance, or reflection coefficient, respectively. New exact analytical scattering matrix solutions, which follow as consequences of this connection, are given for two significant duct acoustics problems, namely, the sound transmission in non-uniform ducts carrying an incompressible subsonic low Mach number mean flow and the transmission of sound in uniform ducts with a full quadratic axial mean temperature gradient. (C) 1998 Academic Press

On transmission of sound in circular and rectangular narrow pipes with superimposed mean flow

The problem of transmission of sound in a narrow pipe carrying a mean flow has been dealt with in recent papers by solving the convected acoustic equations simplified in the manner of the Zwikker and Kosten theory. A significant difference between these studies appertains to the form of the axial mean flow velocity profile assumed in the analysis. Results have been presented previously for uniform and parabolic profiles. This paper presents a comparative study of these for pipes having circular and rectangular cross-sections. The solution of the governing equations for these cases has been presented in previous papers, except for the case of a rectangular pipe carrying a uniform mean flow, which is presented in this paper for the first time. The results indicate that the assumption of a uniform mean profile closely predicts the results based on a parabolic profile. An area in which the theories considered in this paper find application is the acoustical modelling of the honeycomb structure of a monolithic catalytic converter. Previous acoustic models proposed for the honecomb structure assume that the honeycomb pores to be circular. In the present paper a new model is presented for honeycomb structures with rectangular pores. (C) 1998 Academic Press Limited

On one-port characterization of noise sources in ducts by using external loads

Equivalent acoustic source characterization of duct-borne fluid machinery noise is often undertaken by interpolating the results of two-microphone pressure measurements with different external acoustic loads over a linear one-port source model. If the source is time-invariant, the one-port source characteristics can be determined by using only two external loads. This is well known as the two-load method. An extension of the two-load method for time-variant sources is also available and known as the multiple-load method. In these methods the source is treated as a 'black-box'. This paper addresses the problem of one-port source characterization when the linear operations inherent in the 'black-box' are known explicitly. The equations governing the explicit one-port source models are derived and the source characteristics are shown to be measurable using only few acoustic loads. It is not the purpose of this paper to discuss the application of these models to any specific fluid machinery; however, of particular interest are the explicit source models that require only two loads. Numerical results are presented to show some features of such time-invariant and time-variant explicit one-port source models. (C) 2002 Elsevier Science Ltd. All rights reserved

An approximate dispersion equation for sound waves in a narrow pipe with ambient gradients

There is some interest on the effect of temperature gradient on sound propagation in a catalytic monolith. Some results are available in the literature for the effect of a constant temperature gradient on non-isentropic propagation in a narrow pipe modelling a monolith pore, but the effect of mean flow is neglected in these solutions. This paper presents an approximate solution in which the presence of a mean flow, which is assumed to have a uniform velocity profile, is taken into account. The solution also includes the effect of a constant pressure gradient. A dispersion equation is derived by assuming that the spatial variations of the ambient variables can be lumped by using their average values. This approximation limits the range of application of the solution to small ambient gradients or relatively high frequencies. For typical catalytic monolith cylinder dimensions, the present solution can be used to predict the mean flow effects over a useful frequency range. (C) 2001 Academic Press