Recent progress in the relative equilibria of point vortices — In memoriam Hassan Aref

AbstractHassan Aref, who sadly passed away in 2011, was one of the world's leading researchers in the dynamics and equilibria of point vortices. We review two problems on the subject of point vortex relative equilibria in which he was engaged at the time of his death: bilinear relative equilibria and the geometry of the three-vortex problem as it relates to equilibria. A set of point vortices is in relative equilibrium if it is at most rotating rigidly around the center of vorticity, and the configuration is bilinear if the vortices are placed on two orthogonal lines in the co-rotating frame. A very complete characterisation of the bilinear case can be obtained when one of the lines contains only two vortices. The classic three-vortex problem can be viewed anew by considering the dy- namics of the circle circumscribing the vortex triangle and the interior angles of that triangle. This approach leads naturally to the observation that the equilateral triangle is the only equilibrium configuration for three point vortices, regardless of their strength values

Auditor’s perceptions of CEOs overconfidence in Egypt : a quasi-experimental study

Purpose: This study aims to explore auditor’s perceptions of CEOs overconfidence in Egypt as one of the emerging countries. Design/methodology/approach: A quasi-experimental study is used on a sample comprises of 101 practicing auditors at public accounting firms in Egypt to assess (i) CEO overconfidence in a case scenario, (ii) the quality of earnings that would be provided by this overconfident CEO, and (iii) how overconfident CEO would be considered when they are assessing fraud risk, audit risk, audit effort and audit fees. Findings: The results suggest that not all the auditors in the sample were able to discover the same degree of overconfidence personal traits in a case scenario, and it was done by the sense, and they generally agree that overconfident CEO are more likely to provide lower earnings quality. Accordingly, they raise their assessment for audit fees as a result of an increase in fraud risk, audit risk, and audit effort. Practical implications: This study has significant implications for accounting and auditing professionals, market participants and regulators; where auditors should consider the overconfidence of the CEO during the audit process, market participants should consider managerial overconfidence when they are making investment decisions. Moreover, this study highlights the gap between auditing standards and the professional practice; which requires regulators to consider personal overconfidence traits as an indicator of financial reporting risk. Originality/value: This study helps in filling a gap in the literature; where auditor’s perceptions of CEOs overconfidence have not been fully investigated in emerging economies.peer-reviewe

Statistics of the Eigenvalues of a Noisy Multi-Soliton Pulse

For Nonlinear-Frequency Division-Multiplexed (NFDM) systems, the statistics of the received nonlinear spectrum in the presence of additive white Gaussian noise (AWGN) is an open problem. We present a novel method, based on the Fourier collocation algorithm, to compute these statistics.Comment: Accepted for presentation at European Conference on Optical Communications (ECOC) 201