Vincent Charles

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The introductory chapter begins with a brief introduction to data envelopment analysis (DEA) and its origin, followed by the basic assumptions. Further, the concept of efficiency is introduced, through worked examples and graphs, to researchers unfamiliar with the technique. Finally, the basic models of DEA are provided for direct reference for those(More)
Low-gradient (LG), low-flow (LF), severe aortic stenosis (AS) with preserved ejection fraction (PEF) is considered by some authors as an advanced form of AS associated with very poor outcome. The aim of this Doppler echocardiographic study was to investigate changes over time in the hemodynamic severity of LG/LF AS with PEF. We retrospectively identified in(More)
This paper is motivated by recent concerns, prompted by the recent financial crisis, that regulatory capital guidelines on loan loss reserves can generate dysfunctional outcomes and, moreover, by the fact that the Greek bonds held by the banks have an important impact on the risk level of the bank portfolio. The purpose of this paper is to incorporate risk(More)
Abstract: The field of chance constrained fractional programming (CCFP) has grown into a huge area over the last few years because of its applications in real life problems. Therefore, finding a solution technique to it is of paramount importance. The solution technique so far has been deriving deterministic equivalence of CCFP with random coefficients in(More)
Uncertainty is certain in the world of uncertainty. Measuring the performance of any entity in such an uncertain environment is unavoidable. Fuzzy rough data envelopment analysis (FRDEA) provides a room to evaluate the relative efficiency of homogenous entities, widely known as decision making units (DMUs) in the data envelopment analysis (DEA) literature.(More)
Atrial fibrillation (AF) is frequently encountered in patients with aortic stenosis (AS) and its incidence also increases with age. In the general population, AF is known to increase cardiovascular risk. We sought to investigate the prognostic importance of AF associated with AS in the context of routine clinical practice. This analysis was based on 809(More)
Structural redundancies in mathematical programming models are nothing uncommon and nonlinear programming problems are no exception. Over the past few decades numerous papers have been written on redundancy. Redundancy in constraints and variables are usually studied in a class of mathematical programming problems. However, main emphasis has so far been(More)