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Search Results: 1 - 10 of 5332 matches for " Olivier Xhaet "
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Atrial Tachycardias Arising from Ablation of Atrial Fibrillation: A Proarrhythmic Bump or an Antiarrhythmic Turn?
Ashok J. Shah,Amir Jadidi,Xingpeng Liu,Shinsuke Miyazaki,Andrei Forclaz,Isabelle Nault,Lena Rivard,Nick Linton,Olivier Xhaet,Nicolas Derval,Frederic Sacher,Pierre Bordachar,Philippe Ritter,Meleze Hocini,Pierre Jais,Michel Haissaguerre
Cardiology Research and Practice , 2010, DOI: 10.4061/2010/950763
Abstract: The occurrence of atrial tachycardias (AT) is a direct function of the volume of atrial tissue ablated in the patients with atrial fibrillation (AF). Thus, the incidence of AT is highest in persistent AF patients undergoing stepwise ablation using the strategic combination of pulmonary vein isolation, electrogram based ablation and left atrial linear ablation. Using deductive mapping strategy, AT can be divided into three clinical categories viz. the macroreentry, the focal and the newly described localized reentry all of which are amenable to catheter ablation with success rate of 95%. Perimitral, roof dependent and cavotricuspid isthmus dependent AT involve large reentrant circuits which can be successfully ablated at the left mitral isthmus, left atrial roof and tricuspid isthmus respectively. Complete bidirectional block across the sites of linear ablation is a necessary endpoint. Focal and localized reentrant AT commonly originate from but are not limited to the septum, posteroinferior left atrium, venous ostia, base of the left atrial appendage and left mitral isthmus and they respond quickly to focal ablation. AT not only represents ablation-induced proarrhythmia but also forms a bridge between AF and sinus rhythm in longstanding AF patients treated successfully with catheter ablation. 1. Introduction Atrial fibrillation (AF) is no longer a formidable rhythm since ablationists challenged this notorious arrhythmia more than a decade ago in their unprecedented quest for sinus rhythm (SR) [1]. Ablation strategies are based on clinical types of AF but nevertheless, the volume of tissue ablated to treat AF is highest for any cardiac arrhythmia described so far. Paroxysmal AF is amenable to catheter ablation with minimum atrial tissue destruction such that electrical isolation of pulmonary veins (PVs) suffices for establishing cure [2]. Persistent and longer lasting forms of AF necessitate extensive atrial tissue ablation in addition to PV isolation to restore SR [3–7]. Besides having evolved as a therapeutic option in symptomatic AF, surgical ablation has become a routine adjunct to many valvular surgeries and may be employed with surgical coronary revascularization and also as a “standalone” procedure [8, 9]. Despite improvements in ablation strategies, relatively high volume of tissue ablation is performed in AF. Together with remodeling of atria, it provides a favourable substrate for the development of sustained atrial tachycardia(s) during and after AF ablation (ATp) [4]. 2. Magnitude of ATp Burden Based on our observation and also that of
And If Bell’s Inequality Were Not Violated  [PDF]
Olivier Serret
Journal of Modern Physics (JMP) , 2014, DOI: 10.4236/jmp.2014.514137

It briefly recalls the theory of Bell’s inequality and some experimental measures. Then measurements are processed on one hand according to a property of the wave function, on the other hand according to the sum definition. The results of such processed measures are apparently not the same, so Bell’s inequality would not be violated. It is a use of the wave function which implies the violation of the inequality, as it can be seen on the last flowcharts.

Thermodynamics and Irreversibility: From Some Paradoxes to the Efficiency of Effective Engines  [PDF]
Olivier Serret
Journal of Modern Physics (JMP) , 2014, DOI: 10.4236/jmp.2014.516159
Abstract: The traditional thermodynamic theory explains the reversible phenomena quite well, except that reversible phenomena are rare or even impossible in practice. Here the purpose is to propose an explanation valid for reversible and also irreversible phenomena, irreversibility being common or realistic. It previously exposed points tricky to grasp, as the sign of the work exchange, the adiabatic expansion in vacuum (free expansion) or the transfer of heat between two bodies at the same temperature (isothermal transfer). After having slightly modified the concepts of heat transfer (each body produces heat according to its own temperature) and work (distinguishing external pressure from internal pressure), the previous points are more easily explained. At last, an engine efficiency in case of irreversible transfer is proposed. This paper is focused on the form of thermodynamics, on “explanations”; it does not question on “results” (except the irreversible free expansion of 1845...) which remain unchanged.
How to Demonstrate the Lorentz Factor: Variable Time v.s. Variable Inertial Mass  [PDF]
Olivier Serret
Journal of Modern Physics (JMP) , 2015, DOI: 10.4236/jmp.2015.63030
Abstract: For a century, hypothesis of a variable time is laid down by the Relativity Theory. This hypothesis can explain many Nature observations, experiments and formulas, for example the Lorentz factor demonstration. Because of such good explanations, the hypothesis of a variable time has been validated. Nevertheless, it remains some paradoxes and some predictions which are difficult to measure, as a reversible time or the time variation itself. The purpose of this article is to study another hypothesis. If it gives interesting results, it would mean that this alternative hypothesis can also be validated. The idea in this paper is to replace the variable time by a variable inertial mass. To the difference with the Theory of Relativity (where the inertial mass and the gravitational mass are equal and variable), the gravitational mass is here supposed to be constant. So, starting from the definition of the kinetic energy, it is introduced the Lorentz factor. And then it is demonstrated the value of the Lorentz factor thanks to a variable inertial mass. This variable inertial mass can also explain experiments, like Bertozzi experiment. If this alternative demonstration was validated, it could help to open doors, other physical effects could be explained like the addition of velocities.
Velocity Addition Demonstrated from the Conservation of Linear Momenta, an Alternative Expression  [PDF]
Olivier Serret
Journal of Modern Physics (JMP) , 2015, DOI: 10.4236/jmp.2015.66077
Abstract: Is it possible to demonstrate the velocity addition without using a variable time (as it is done in theory of relativity)? The topic of this paper is to propose and demonstrate an alternative expres-sion based on the conservation of linear momenta. The method proposed here is to start from a physical object (and not from a mathematical point), i.e. from an object with a mass. And the hy-pothesis is inertial mass to be different from gravitational mass. Then, when impulses are added, we get an expression of the velocity addition itself. When numerical predictions are compared with experimental results, the differences are lower than the measures uncertainty. And these numerical results are much close to those predicts by the theory of relativity, nevertheless with a little difference at high velocities. If this demonstration and this expression were validated, it would allow giving an alternative explanation to some experiments and nature observations as Doppler Effect on light celerity. But first, it would be necessary to get from laboratories more precise experimental results, in order to validate or not this hypothesis of the sum of linear momenta with a Variable Inertial Mass.
A Chart of Conversion Supporting EPR Paradox vs. Bell’s Inequalities Violation  [PDF]
Olivier Serret
Journal of Modern Physics (JMP) , 2015, DOI: 10.4236/jmp.2015.613201
Abstract: Quantum Mechanics formalism remains difficult to understand and sometimes is confusing, especially in the explanation of ERP paradox and of Bell’s inequalities with entanglement photons. So a chart of conversion, in which elements are named differently, is proposed. Next, experiment about Bell’s inequalities violation is described in another way, and we hope a clearer one. Main result is Bell’s inequalities would not be violated! The explanation would come from confusion between the definition of the correlation function S1, and a property S2. And consequently, Einstein, Podolski and Rosen would be right on the local “hidden” variable.
An Alternative Demonstration of the Carnot Efficiency “Without” Using the Entropy Function  [PDF]
Olivier Serret
Journal of Modern Physics (JMP) , 2016, DOI: 10.4236/jmp.2016.72020
Abstract: Entropy function is used to demonstrate the Carnot efficiency, even if it is not always easy to understand its bases: the reversible movement or the reversible heat transfer. Here, it is proposed to demonstrate the Carnot efficiency “without” using the Entropy function. For this, it is necessary to enhance two concepts: heat transfer based on the source temperature and work transfer based on external pressure. This is achieved through 1) a balance exchanged heat, based on the source temperature and the system temperature, and 2) a balance exchanged work, based on the external pressure and the internal pressure. With these enhanced concepts, Laplace function \"\" and Carnot efficiency \"\" can be demonstrated without using the Entropy function (S). This is only a new formalism. Usual thermodynamics results are not changed. This new formalism can help to get a better description of realistic phenomena, like the efficiency of a realistic cycle.
Net Force F = γ3ma at High Velocity  [PDF]
Olivier Serret
Journal of Modern Physics (JMP) , 2016, DOI: 10.4236/jmp.2016.77065
Abstract: Newton’s theory of gravitation has been outdated by relativity theory explaining specific phenomena like perihelion precession of Mercury, light deflection and very recently the detection of gravitational waves. But the disappearance of the obvious gravitational force and the variation of time are arguable concepts difficult to directly prove. Present methodology is based on hypotheses as expressed in a previous article: a universal time and an inertial mass variable according to the Lorentz factor (which could not be envisioned at Newton’s age). Because this methodology is mainly stood on Newtonian mechanics, it will be called neo-Newtonian mechanics. This theory is in coherence with the time of the Quantum Mechanics. In Newtonian mechanics, all forces, including gravitational force, are deducted from the linear momentum. Introducing the variable inertial mass, the result of the demonstration is an updated expression of the net force at high velocity: F = γ3mga. If such a factor in γ3 can look a bit strange at first sight for a force, let us remind that the lost energy in a synchrotron is already measured in γ4. Next article will be on the perihelion precession of Mercury within neo-Newtonian mechanics.
Reply to “A Simple Derivation of the Lorentz Transformation”  [PDF]
Olivier Serret
Journal of Modern Physics (JMP) , 2017, DOI: 10.4236/jmp.2017.813132
Abstract: The theory of Relativity is consistent with the Lorentz transformation. Thus Pr. Lévy proposed a simple derivation of it, based on the Relativity postulates. A reply is provided: Some related results (five ones) are found and developed step by step which would invalid it. So Lorentz transformation would not be simply derived by this way. Finally an alternative demonstration of Lorentz transformation is reminded, consistent with Quantum Mechanics.
Gravity vs. Dark Energy, about the Expansion of the Universe  [PDF]
Olivier Serret
Journal of Modern Physics (JMP) , 2018, DOI: 10.4236/jmp.2018.91006
Abstract: Dark energy is argued by the accelerating expansion of the Universe but has not been directly measured. In this article, some uncertainties are pointed out, first one being the determination of the Hubble constant. And the main parameters (magnitude, distance, redshift, velocity) are checked. Distinguishing the instantaneous velocity from the average velocity, it is then concluded from the same data that the expansion would not be accelerating, and that the Gravity would slightly slow down the motion of explosion. Moreover, at the end of the paper, it is proposed a neo-Newtonian approach to get the computed values in a closer agreement with the observed values; this Neo-Newtonian Mechanics is in coherence with the Quantum Mechanics.
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