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Ion source parameters and hydrogen scrambling in the ECD of selectively deuterated peptides
No full textInternational audienceHydrogen/deuterium exchange monitored by mass spectrometry (HDX-MS) has become an important method to study protein dynamics in solution. Recently, electron-based fragmentation methods (ECD and ETD) have been utilized in HDX-MS/MS experiments as experimental tools to increase the spatial resolution (the ability to obtain deuterium levels of individual residues). An essential prerequisite for this approach is that the level of hydrogen scrambling is negligible. The occurrence of hydrogen scrambling depends critically on the extent of vibrational excitation in the mass spectrometer. In particular, the desolvation process in the electrospray ion source is likely to induce scrambling at standard operating conditions. Consequently, finding experimental conditions that minimize hydrogen scrambling to a negligible level is thus pivotal for the application of electron-based fragmentation in HDX-MS/MS experiments. In the present work, we investigate the occurrence of scrambling in the Apollo I electrospray ion source using ECD of selectively deuterium labeled peptides. The electrospray ion source settings leading to minimal scrambling were identified. Furthermore, an energy dependent loss of deuterium occurring in the ion source was also observed. This loss was critically dependent on the occurrence of scrambling
Toward modelization of quark and gluon transversity generalized parton distributions
No full text6 pages, DIS 2014, XXII. International Workshop on Deep-Inelastic Scattering and Related Subjects, 28 April - 2 May 2014, Warsaw, PolandQuark and gluon helicity flip generalized parton distributions (GPDs) encode the information on the nucleon structure in the transversity sector. In order to build a theoretically consistent phenomenological parametrization for these hadronic matrix element within the framework of the dual parametrization of GPDs (or with the equivalent approach of the SO(3) partial waves (PW) expansion with the Mellin-Barnes integral techniques) we establish the set of combinations of parton helicity flip GPDs suitable for the expansion in the cross channel SO(3) PWs
3D direct and inverse solvers for eddy current testing of deposits in steam generator
No full text34pWe consider the inverse problem of estimating the shape profile of an unknown deposit from a set of eddy current impedance measurements. The measurements are acquired with an axial probe, which is modeled by a set of coils that generate a magnetic field inside the tube. For the direct problem, we validate the method that takes into account the tube support plates, highly conductive part, by a surface impedance condition. For the inverse problem, finite element and shape sensitivity analysis related to the eddy current problem are provided in order to determine the explicit formula of the gradient of a least square misfit functional. A geometrical-parametric shape inversion algorithm based on cylindrical coordinates is designed to improve the robustness and the quality of the reconstruction. Several numerical results are given in the experimental part. Numerical experiments on synthetic deposits, nearby or far away from the tube, with different shapes are considered in the axisymmetric configuration
Visible-emitting hybrid sol–gel materials comprising lanthanide ions: thin film behaviour and potential use as phosphors for solid-state lighting
No full textInternational audienceThe synthesis and characterization, as well as the film-forming and luminescent properties of four visible-emitting hybrid organic-inorganic sol-gel materials are reported. They show thermal stability up to 165°C. Deposition conditions were optimized to coat these materials as homogeneous and transparent thin films (~50 nm) with smooth surface, as probed by AFM. They were specifically designed to emit the primary colors. The blue-emitting material 1 was made up of a polyfluorene derivative embedded in a silica matrix, while the green (2) and red (3)-emissive materials comprise the TbIII and EuIII ions bound to the matrix, respectively. The films showed relatively high emission quantum yields efficiencies, with values of 19% (blue), 46% (green), and 21% (red). The three emitters were used to design a single emissive material (4) that showed emission colors from yellow-green to blue in a wide range of excitation wavelengths (254-380 nm). In particular, white light was obtained after excitation at 340 nm
Defects and strain enhancements of second-harmonic generation in Si/Ge superlattices
No full textInternational audienceStarting from experimental findings and interface growth problems in Si/Ge superlattices, we have investigated through ab initio methods the concurrent and competitive behavior of strain and defects in the second-harmonic generation process. Interpreting the second-harmonic intensities as a function of the different nature and percentage of defects together with the strain induced at the interface between Si and Ge, we found a way to tune and enhance the second-harmonic generation response of these systems. (C) 2014 AIP Publishing LLC
Optimization of running strategies based on anaerobic energy and variations of velocity
No full textParallel sessionInternational audience1 Keller's model 2 Variable energy recreation 3 Bounding the derivative of
The Nef Reaction of Isocyanides
No full textInternational audienceThe interaction of isocyanides with acyl chlorides was first reported by Nef in 1892. The resulting α-keto imidoyl chlorides may be hydrolyzed to form α-keto amides. Relatively few data are available on this reaction and the chemistry of α-keto imidoyl chlorides has been largely underestimated until some recent uses in intra- and intermolecular couplings with a variety of nucleophiles. The present review brings a comprehensive presentation of the Nef reaction of isocyanides focusing on mechanism and regioselectivity issues
Posterior concentration rates for empirical Bayes procedures, with applications to Dirichlet Process mixtures
No full textIn this paper we provide general conditions to check on the model and the prior to derive posterior concentration rates for data-dependent priors (or empirical Bayes approaches). We aim at providing conditions that are close to the conditions provided in the seminal paper by Ghosal & van der Vaart (2007). We then apply the general theorem to two different settings: the estimation of a density using Dirichlet process mixtures of Gaussian random variables with base measure depending on some empirical quantities and the estimation of the intensity of a counting process under the Aalen model. A simulation study for inhomogeneous Poisson processes also illustrates our results. In the former case we also derive some results on the estimation of the mixing density and on the deconvolution problem. In the latter, we provide a general theorem on posterior concentration rates for counting processes with Aalen multiplicative intensity with priors not depending on the data
Transport Optimal Martingale et Problèmes de Maximisation d'Utilité
No full textThis PhD dissertation presents two independent research topics dealing with contemporary issues from financial mathematics, the second one being composed of two distinct problems. In the first part we study the question of martingale optimal transport, which comes from the questions of no-arbitrage optimal bounds of liabilities. We first consider the question in discret time of the existence of a martingale law with given marginals. This result was first proved by Strassen (1965) and is the starting point of martingale optimal transport. We provide a new proof of this theorem based on utility maximization technics, adapted from a proof of the fundamental theorem of asset pricing by Rogers. We then consider the question of martingale optimal transport in continuous time, introduced in the framework of lookback options by Galichon, Henry-Labordère et Touzi. We first establish a partial duality result concerning the robust superhedging of any contingent claim. For that purpose, we adapt recent technics developed by Neufeld and Nutz in the context of martingale optimal transport. In a second time we study a robust utility maximization of a contingent claim with exponential utility in the context of martingale optimal transport, and we deduce its robust utility indifference price, given that the underlying's dynamic has a constant and well-known sharpe ratio. We prove that this robust utility indifference price is equal to the robust superhedging price. The second part of this disseration considers first the problem of optimal liquidation of an indivisible asset. We study the advantage that an agent can take from having a dynamic trading strategy in an orthogonal asset. The question of its influence on the optimal liquidation rule is asked. We then provide examples illustrating our results. The last chapter of this thesis concerns the utility indifference price of a European option in the context of small transaction costs. We use technics developed by Soner and Touzi to obtain an asymptotic expansion of the Merton value functions with and without the option. These expansions are obtained by using homogenization technics. We formally obtain a system of equations verified by the values involved in the expansion and show rigorously that they are solutions. We then deduce an asymptotic expansion of the utility indifference price.Cette thèse présente deux principaux sujets de recherche indépendants, le dernier regroupant deux problématiques distinctes. Dans la première partie nous nous intéressons au problème du transport optimal martingale, dont le but premier est de trouver des bornes de non-arbitrage pour des options quelconques. Nous nous intéressons tout d'abord à la question en temps discret de l'existence d'une loi de probabilité sous laquelle le processus canonique est martingale, ayant deux lois marginales fixées. Ce résultat dû à Strassen (1965) est le point de départ pour le problème primal de transport optimal martingale. Nous en donnons une preuve basée sur des techniques financières de maximisation d'utilité, en adaptant une méthode développée par Rogers pour prouver le théorème fondamental d'évaluation d'actif. Ces techniques correspondent à une version en temps discrétisé du transport optimal martingale. Nous considérons ensuite le problème de transport optimal martingale en temps continu introduit dans le cadre des options lookback par Galichon, Henry-Labordère et Touzi. Nous commencons par établir un résultat de dualité partiel concernant la surcouverture robuste d'une option quelconque. Pour cela nous adaptons au transport optimal martingale des travaux récents de Neufeld et Nutz. Nous étudions ensuite le problème de maximisation d'utilité robuste d'une option quelconque avec fonction d'utilité exponentielle dans le cadre du transport optimal martingale, et en déduisons le prix d'indifférence d'utilité robuste, sous une dynamique où le ratio de sharpe est constant et connu. Nous prouvons en particulier que ce prix d'indifférence d'utilité robuste est égal au prix de surcouverture robuste. La deuxième partie de cette thèse traite tout d'abord d'un problème de liquidation optimale d'un actif indivisible. Nous étudions la profitabilité de l'ajout d'une stratégie d'achat et de vente d'un actif orthogonal au premier sur la stratégie de liquidation optimale de l'actif indivisible. Nous fournissons ensuite quelques exemples illustratifs. Le dernier chapitre de cette thèse concerne le problème du prix d'indifférence d'utilité d'une option européenne en présence de petits coûts de transaction. Nous nous inspirons des travaux récents de Soner et Touzi pour obtenir un développement asymptotique des fonctions valeurs des problèmes de Merton avec et sans l'option. Ces développements sont obtenus en utilisant des techniques d'homogénisation. Nous obtenons formellement un système d'équations vérifiées par les composantes du problème et nous vérifions que celles-ci en sont bien solution. Nous en déduisons enfin un développement asymptotique du prix d'indifférence d'utilité souhaité
A combination of algebraic, geometric and numerical methods in the contrast problem by saturation in magnetic resonance imaging
No full textPapier non paru.In this article, the contrast imaging problem by saturation in nuclear magnetic resonance is modeled as a Mayer problem in optimal control. The optimal solution can be found as an extremal solution of the Maximum Principle and analyzed with the recent advanced techniques of geometric optimal control. This leads to a numerical investigation based on shooting and continuation methods implemented in the HamPath software. The results are compared with a direct approach to the optimization problem and implemented within the Bocop toolbox. In complement lmi techniques are used to estimate a global optimum. It is completed with the analysis of the saturation problem of an ensemble of spin particles to deal with magnetic fields inhomogeneities