A Patient-Specific Equivalent Dipole Model

International audienceSophisticated models for the electrocardiographic inverse problem are available, but their reliance on imaging data and large numbers of electrodes limit their use. Simple models such as the equivalent dipole model (EDM) therefore remain relevant. We developed a probabilistic approach to the equivalent unbounded uniform single dipole problem and developed a natural extension to the bounded nonuniform case that relies on a patientspecific statistical inference of the propagation mechanism between the location of the dipole and the electrode locations. The two models were tested on data simulated with a detailed heart-torso model with four different activation sequences and three different sets of tissue characteristics. We observed a throughout enhancement of the ability to reconstruct the ECG of the patient-specific model when compared to the uniform unbounded dipole model

Méthodes de rang faible pour les données hétérogènes et multi-source

In modern applications of statistics and machine learning, one often encounters many data imperfections. In particular, data are often heterogeneous, i.e. combine quantitative and qualitative information, incomplete, with missing values caused by machine failure or nonresponse phenomenons, and multi-source, when the data result from the compounding of diverse sources. In this dissertation, we develop several methods for the analysis of multi-source, heterogeneous and incomplete data. We provide a complete framework, and study all the aspects of the different methods, with thorough theoretical studies, open source implementations, and empirical evaluations. We study in details two particular applications from ecology and medical sciences.Dans les applications modernes des statistiques et de l'apprentissage, il est courant que les données récoltées présentent un certain nombre d'imperfections. En particulier, les données sont souvent hétérogènes, c'est-à-dires qu'elles contiennent à la fois des informations quantitatives et qualitatives, incomplètes, lorsque certaines informations sont inaccessibles ou corrompues, et multi-sources, c'est-à-dire qu'elles résultent de l'agrégation de plusieurs jeux de données indépendant. Dans cette thèse, nous développons plusieurs méthodes pour l'analyse de données hétérogènes, incomplètes et multi-source. Nous nous attachons à étudier tous les aspects de ces méthodes, en fournissant des études théoriques précises, ainsi que des implémentations disponibles au public, et des évaluations empiriques. En particulier, nous considérons en détail deux applications issues de l'écologie pour la première et de la médecine pour la seconde

A Patient-Specific Equivalent Dipole Model

International audienceSophisticated models for the electrocardiographic inverse problem are available, but their reliance on imaging data and large numbers of electrodes limit their use. Simple models such as the equivalent dipole model (EDM) therefore remain relevant. We developed a probabilistic approach to the equivalent unbounded uniform single dipole problem and developed a natural extension to the bounded nonuniform case that relies on a patientspecific statistical inference of the propagation mechanism between the location of the dipole and the electrode locations. The two models were tested on data simulated with a detailed heart-torso model with four different activation sequences and three different sets of tissue characteristics. We observed a throughout enhancement of the ability to reconstruct the ECG of the patient-specific model when compared to the uniform unbounded dipole model

A Patient-Specific Equivalent Dipole Model

International audienceSophisticated models for the electrocardiographic inverse problem are available, but their reliance on imaging data and large numbers of electrodes limit their use. Simple models such as the equivalent dipole model (EDM) therefore remain relevant. We developed a probabilistic approach to the equivalent unbounded uniform single dipole problem and developed a natural extension to the bounded nonuniform case that relies on a patientspecific statistical inference of the propagation mechanism between the location of the dipole and the electrode locations. The two models were tested on data simulated with a detailed heart-torso model with four different activation sequences and three different sets of tissue characteristics. We observed a throughout enhancement of the ability to reconstruct the ECG of the patient-specific model when compared to the uniform unbounded dipole model

Synthesis and Photophysics of Thioindigo Diimines and Related Compounds

We report the synthesis and comprehensive characterization of diamine and diimine derivatives of the fluorescent compound thioindigo. Diamines <b>1</b> were obtained by metal-mediated amine condensation reaction with thioindigo. Oxidation of the products of the coupling reaction provided the diimines <b>2</b>. X-ray crystal structures, cyclic voltammetry, and spectral and photophysical data of the compounds are presented. X-ray crystal structures demonstrate a planar structure for the diimine derivatives and a twisted conformation for the diamines. The diamine compounds <b>1</b> absorb in the UV (λ_max 324–328 nm), significantly blue-shifted from the absorption spectrum of thioindigo. Diamines <b>1</b> exhibit moderate fluorescence (Φ_F = 0.25, 0.045). A transient triplet state is observed in laser flash photolysis (LFP) experiments of <b>1</b>, with lifetimes 1 order of magnitude longer than those of thioindigo. The diimine compounds <b>2</b> absorb at longer wavelengths (λ_max 495–510 nm) than the diamines but are still slightly blue-shifted from thioindigo, with molar extinction coefficients 17–70% higher compared to thioindigo. The diimine compounds are not emissive, and LFP studies indicate transient species with microsecond lifetimes. Quenching experiments and transient absorption spectra are consistent with trans–cis isomerization

Diastereomerically Differentiated Excited State Behavior in Ruthenium(II) Hexafluoroacetylacetonate Complexes of Diphenyl Thioindigo Diimine

Mono- and diruthenium hexafluoroacetylacetonate (hfac) complexes of the thioindigo-<i>N</i>,<i>N</i>′-diphenyldiimine chelating ligand <b>3</b> have been prepared. The thioindigo diimine ligand binds to ruthenium in a bidentate fashion in the mononuclear compound <b>2</b> and serves as a bidentate chelating bridging ligand in the diruthenium complexes <b>1a</b> and <b>1b</b>. Compound <b>2</b> was isolated as a racemic mixture while the diruthenium complexes were isolated as the <i>meso</i> (ΔΛ) <b>1a</b> and <i>rac</i> (ΔΔ and ΛΛ) <b>1b</b> diastereomers. In-depth structural characterization of the compounds was performed, including X-ray crystallography, ¹H, ¹³C, and ¹⁹F nuclear magnetic resonance (NMR) spectroscopy, and 2D NMR correlation experiments. Electrochemical properties were evaluated utilizing cyclic voltammetry. Ground state optical properties of the complexes were examined using UV–visible spectroscopy and spectroelectrochemistry. The excited state dynamics of the series were investigated by ultrafast transient absorption spectroscopy. Variable temperature NMR experiments demonstrated that the <i>rac</i> diruthenium compound <b>1b</b> undergoes conformational exchange with a rate constant of 8700 s^–1 at 298 K, a behavior that is not observed in the <i>meso</i> diastereomer <b>1a</b>. The series of complexes possess metal-to-ligand charge transfer (MLCT) absorption bands in the near-infrared (λ_max 689–783 nm). The compounds do not display photoluminescence in room temperature solution-phase experiments or in experiments at 77 K. Transient absorption spectroscopy measurements revealed excited states with picosecond lifetimes for <b>1a</b>, <b>1b</b>, and <b>2</b>, and spectroelectrochemical experiments confirmed assignment of the transient species as arising from MLCT transitions. Unexpectedly, the transient absorption measurements revealed disparate time constants for the excited state decay of diastereomers <b>1a</b> and <b>1b</b>