We introduce a new class of Sequential Monte Carlo (SMC) methods, which we call free energy SMC. ... more We introduce a new class of Sequential Monte Carlo (SMC) methods, which we call free energy SMC. This class is inspired by free energy methods, which originate from Physics, and where one samples from a biased distribution such that a given function ξ(θ) of the state θ is forced to be uniformly distributed over a given interval. From an initial sequence of distributions (πt) of interest, and a particular choice of ξ(θ), a free energy SMC sampler computes sequentially a sequence of biased distributions (πt) with the following properties: (a) the marginal distribution of ξ(θ) with respect toπt is approximatively uniform over a specified interval, and (b)πt and πt have the same conditional distribution with respect to ξ. We apply our methodology to mixture posterior distributions, which are highly multimodal. In the mixture context, forcing certain hyper-parameters to higher values greatly faciliates mode swapping, and makes it possible to recover a symetric output. We illustrate our approach with univariate and bivariate Gaussian mixtures and two real-world datasets.
The synthesis of two trifluoromethyl-derived enaminone ligands, L1H (bidentate) and L2H 2 , (trid... more The synthesis of two trifluoromethyl-derived enaminone ligands, L1H (bidentate) and L2H 2 , (tridentate), which bear a fluorescent 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (Bodipy) moiety, leads to the preparation and characterization of two Cu II complexes {[Cu(L1) 2 ]·2(CH 2 Cl 2 ) (A) and [Cu 4 (L2) 4 ]·4(C 4 H 8 O 2 ) (B)} that exhibit different architectures. The magnetic properties of the cubane-like complex B evidence a dominant ferromagnetic behavior characterized by exchange coupling constants J 1 = +20.56(3) cm -1 and J 2 = -10.29(2) cm -1 . Indeed, whereas the luminescence properties [a] Université Claude Job/Unit: I42714
The synthesis of several methyl and benzyl c-ylidenetetronates was accomplished and the brominati... more The synthesis of several methyl and benzyl c-ylidenetetronates was accomplished and the bromination reactions of these derivatives, using bromine or N-bromosuccinimide (NBS), were found to occur under mild conditions. Several new brominated c-unsaturated lactones derived from tetronic acid were prepared in moderate to good yields, with some of them characterized by single crystal X-ray diffraction.
The Journal of the American Association of Gynecologic Laparoscopists, 2004
Study Objective. To determine the efficacy of gonadotropinreleasing hormone (GnRH) analogs plus a... more Study Objective. To determine the efficacy of gonadotropinreleasing hormone (GnRH) analogs plus add-back therapy compared with GnRH analogs alone and estroprogestin in patients with relapse of endometriosis-associated pain. Methods. One hundred thirty-three women with relapse of endometriosis-related pain after previous endometriosis surgery were enrolled. Forty-six women were treated with GnRH analog plus add-back therapy, 44 women were given GnRH analog alone, and 43 women received estroprogestin, for 12 months. Pain evaluation by a visual analog scale, quality of life in treated patients using the SF-36 questionnaire, and occurrence of adverse effects including bone mass density loss, at pretreatment, after 6 months of treatment, at the end of treatment, and 6 months after discontinuation of treatment were evaluated. Measurements and Main Results. Patients treated either
Dedicated to Doctor Alain Tressaud with recognition on the occasion of his receipt of the 2011 AC... more Dedicated to Doctor Alain Tressaud with recognition on the occasion of his receipt of the 2011 ACS Award for Creative Work in Fluorine Chemistry.
This study was designed to investigate the intra-operative characteristics and the risk of intra-... more This study was designed to investigate the intra-operative characteristics and the risk of intra- and post-operative complications in cases of total laparoscopic hysterectomy (TLH) in overweight, obese and non-obese patients. This cohort study includes all patients undergoing TLH for benign pathologies between January 1993 and June 2007 in Cochin university hospital (Paris). Demographic and surgical data were analysed. A comparison between overweight and obese patients versus non-obese patients and multivariate analyses were performed. Of 1460 patients undergoing TLH, 101 patients (6.9%) had a BMI of 30 or higher and 338 (23.2%) were overweight. After adjustment with respect to the patients' characteristics and past history (age, parity, past history of laparotomies, previous Cesarean section, menopausal status), no significant difference was found whether in terms of intra-operative (haemorrhage, transfusion, thrombosis, ureter, bladder or bowel injuries) or post-operative complications (hyperthermia, infections, fistula). Concerning the intra- and post-operative characteristics of these patients, only a significantly longer operating time was noted in the case of obesity (RR = 1.80; CI 95%: 1.16-2.81). In our experience, provided that the operating technique is meticulous, the intra- and post-operative complications are not increased in the case of obesity, although the operating time is longer.
A new family of [Cu 4 L 4 ] cubane complexes have been synthesized by the self-assembly of Cu II ... more A new family of [Cu 4 L 4 ] cubane complexes have been synthesized by the self-assembly of Cu II salts and β-aminovinyl trifluoromethyl ketone ligands. The resulting polynuclear architectures were especially designed to exhibit magnetic properties arising from the metallic cubane architecture as well as electro-or photosensitive properties arising from the ligands. The optical and electrochemical behaviours of the compounds were measured in solution to confirm that the properties of the free ligands were retained within the elaborated complexes. DFT investigations of the organic moieties [a] Université Claude 5058 Scheme 2. Designed β-aminovinyl trifluoromethyl ketone ligands L1H 2 -L4H 2 .
New polyfunctional bidentate and tetradentate trifluoromethylated enaminone ligands that bear red... more New polyfunctional bidentate and tetradentate trifluoromethylated enaminone ligands that bear redox-active and photosensitive moieties were synthesized in moderate to good yields and their coordination chemistry with copper(II) was examined. The crystal structures revealed the formation of mononuclear Cu II complexes with all ligands, where the metal ion is located in almost perfect to distorted square planar environments. The deviation from an ideal square [a]
Objective: An abnormality of the optical transmission waveform obtained during measurement of the... more Objective: An abnormality of the optical transmission waveform obtained during measurement of the activated partial thromboplastin time (aPTT) has been described to identify a high-risk intensive care unit population consisting of patients with sepsis or with higher mortality rates than patients with normal aPTT waveforms. We investigated the abnormal aPTT biphasic waveform as a diagnostic and prognostic marker of infection.
The integrated likelihood (also called the marginal likelihood or the normalizing constant) is a ... more The integrated likelihood (also called the marginal likelihood or the normalizing constant) is a central quantity in Bayesian model selection and model averaging. It is defined as the integral over the parameter space of the likelihood times the prior density. The Bayes factor for model comparison and Bayesian testing is a ratio of integrated likelihoods, and the model weights in Bayesian model averaging are proportional to the integrated likelihoods. We consider the estimation of the integrated likelihood from posterior simulation output, aiming at a generic method that uses only the likelihoods from the posterior simulation iterations. The key is the harmonic mean identity, which says that the reciprocal of the integrated likelihood is equal to the posterior harmonic mean of the likelihood. The simplest estimator based on the identity is thus the harmonic mean of the likelihoods. While this is an unbiased and simulation-consistent estimator, its reciprocal can have infinite variance and so it is unstable in general.
Structured additive regression models are perhaps the most commonly used class of models in stati... more Structured additive regression models are perhaps the most commonly used class of models in statistical applications. It includes, among others, (generalized) linear models, (generalized) additive models, smoothing spline models, state space models, semiparametric regression , spatial and spatiotemporal models, log-Gaussian Cox processes and geostatistical and geoadditive models. We consider approximate Bayesian inference in a popular subset of struc-tured additive regression models, latent Gaussian models, where the latent field is Gaussian, controlled by a few hyperparameters and with non-Gaussian response variables. The posterior marginals are not available in closed form owing to the non-Gaussian response variables. For such models, Markov chain Monte Carlo methods can be implemented, but they are not without problems, in terms of both convergence and computational time. In some practical applications, the extent of these problems is such that Markov chain Monte Carlo sampling is simply not an appropriate tool for routine analysis. We show that, by using an integrated nested Laplace approximation and its simplified version, we can directly compute very accurate approximations to the posterior marginals. The main benefit of these approximations is computational: where Markov chain Monte Carlo algorithms need hours or days to run, our approximations provide more precise estimates in seconds or minutes. Another advantage with our approach is its generality , which makes it possible to perform Bayesian analysis in an automatic, streamlined way, and to compute model comparison criteria and various predictive measures so that models can be compared and the model under study can be challenged.
We introduce a new class of Sequential Monte Carlo (SMC) methods, which we call free energy SMC. ... more We introduce a new class of Sequential Monte Carlo (SMC) methods, which we call free energy SMC. This class is inspired by free energy methods, which originate from Physics, and where one samples from a biased distribution such that a given function ξ(θ) of the state θ is forced to be uniformly distributed over a given interval. From an initial sequence of distributions (πt) of interest, and a particular choice of ξ(θ), a free energy SMC sampler computes sequentially a sequence of biased distributions (πt) with the following properties: (a) the marginal distribution of ξ(θ) with respect toπt is approximatively uniform over a specified interval, and (b)πt and πt have the same conditional distribution with respect to ξ. We apply our methodology to mixture posterior distributions, which are highly multimodal. In the mixture context, forcing certain hyper-parameters to higher values greatly faciliates mode swapping, and makes it possible to recover a symetric output. We illustrate our approach with univariate and bivariate Gaussian mixtures and two real-world datasets.
The synthesis of two trifluoromethyl-derived enaminone ligands, L1H (bidentate) and L2H 2 , (trid... more The synthesis of two trifluoromethyl-derived enaminone ligands, L1H (bidentate) and L2H 2 , (tridentate), which bear a fluorescent 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (Bodipy) moiety, leads to the preparation and characterization of two Cu II complexes {[Cu(L1) 2 ]·2(CH 2 Cl 2 ) (A) and [Cu 4 (L2) 4 ]·4(C 4 H 8 O 2 ) (B)} that exhibit different architectures. The magnetic properties of the cubane-like complex B evidence a dominant ferromagnetic behavior characterized by exchange coupling constants J 1 = +20.56(3) cm -1 and J 2 = -10.29(2) cm -1 . Indeed, whereas the luminescence properties [a] Université Claude Job/Unit: I42714
The synthesis of several methyl and benzyl c-ylidenetetronates was accomplished and the brominati... more The synthesis of several methyl and benzyl c-ylidenetetronates was accomplished and the bromination reactions of these derivatives, using bromine or N-bromosuccinimide (NBS), were found to occur under mild conditions. Several new brominated c-unsaturated lactones derived from tetronic acid were prepared in moderate to good yields, with some of them characterized by single crystal X-ray diffraction.
The Journal of the American Association of Gynecologic Laparoscopists, 2004
Study Objective. To determine the efficacy of gonadotropinreleasing hormone (GnRH) analogs plus a... more Study Objective. To determine the efficacy of gonadotropinreleasing hormone (GnRH) analogs plus add-back therapy compared with GnRH analogs alone and estroprogestin in patients with relapse of endometriosis-associated pain. Methods. One hundred thirty-three women with relapse of endometriosis-related pain after previous endometriosis surgery were enrolled. Forty-six women were treated with GnRH analog plus add-back therapy, 44 women were given GnRH analog alone, and 43 women received estroprogestin, for 12 months. Pain evaluation by a visual analog scale, quality of life in treated patients using the SF-36 questionnaire, and occurrence of adverse effects including bone mass density loss, at pretreatment, after 6 months of treatment, at the end of treatment, and 6 months after discontinuation of treatment were evaluated. Measurements and Main Results. Patients treated either
Dedicated to Doctor Alain Tressaud with recognition on the occasion of his receipt of the 2011 AC... more Dedicated to Doctor Alain Tressaud with recognition on the occasion of his receipt of the 2011 ACS Award for Creative Work in Fluorine Chemistry.
This study was designed to investigate the intra-operative characteristics and the risk of intra-... more This study was designed to investigate the intra-operative characteristics and the risk of intra- and post-operative complications in cases of total laparoscopic hysterectomy (TLH) in overweight, obese and non-obese patients. This cohort study includes all patients undergoing TLH for benign pathologies between January 1993 and June 2007 in Cochin university hospital (Paris). Demographic and surgical data were analysed. A comparison between overweight and obese patients versus non-obese patients and multivariate analyses were performed. Of 1460 patients undergoing TLH, 101 patients (6.9%) had a BMI of 30 or higher and 338 (23.2%) were overweight. After adjustment with respect to the patients' characteristics and past history (age, parity, past history of laparotomies, previous Cesarean section, menopausal status), no significant difference was found whether in terms of intra-operative (haemorrhage, transfusion, thrombosis, ureter, bladder or bowel injuries) or post-operative complications (hyperthermia, infections, fistula). Concerning the intra- and post-operative characteristics of these patients, only a significantly longer operating time was noted in the case of obesity (RR = 1.80; CI 95%: 1.16-2.81). In our experience, provided that the operating technique is meticulous, the intra- and post-operative complications are not increased in the case of obesity, although the operating time is longer.
A new family of [Cu 4 L 4 ] cubane complexes have been synthesized by the self-assembly of Cu II ... more A new family of [Cu 4 L 4 ] cubane complexes have been synthesized by the self-assembly of Cu II salts and β-aminovinyl trifluoromethyl ketone ligands. The resulting polynuclear architectures were especially designed to exhibit magnetic properties arising from the metallic cubane architecture as well as electro-or photosensitive properties arising from the ligands. The optical and electrochemical behaviours of the compounds were measured in solution to confirm that the properties of the free ligands were retained within the elaborated complexes. DFT investigations of the organic moieties [a] Université Claude 5058 Scheme 2. Designed β-aminovinyl trifluoromethyl ketone ligands L1H 2 -L4H 2 .
New polyfunctional bidentate and tetradentate trifluoromethylated enaminone ligands that bear red... more New polyfunctional bidentate and tetradentate trifluoromethylated enaminone ligands that bear redox-active and photosensitive moieties were synthesized in moderate to good yields and their coordination chemistry with copper(II) was examined. The crystal structures revealed the formation of mononuclear Cu II complexes with all ligands, where the metal ion is located in almost perfect to distorted square planar environments. The deviation from an ideal square [a]
Objective: An abnormality of the optical transmission waveform obtained during measurement of the... more Objective: An abnormality of the optical transmission waveform obtained during measurement of the activated partial thromboplastin time (aPTT) has been described to identify a high-risk intensive care unit population consisting of patients with sepsis or with higher mortality rates than patients with normal aPTT waveforms. We investigated the abnormal aPTT biphasic waveform as a diagnostic and prognostic marker of infection.
The integrated likelihood (also called the marginal likelihood or the normalizing constant) is a ... more The integrated likelihood (also called the marginal likelihood or the normalizing constant) is a central quantity in Bayesian model selection and model averaging. It is defined as the integral over the parameter space of the likelihood times the prior density. The Bayes factor for model comparison and Bayesian testing is a ratio of integrated likelihoods, and the model weights in Bayesian model averaging are proportional to the integrated likelihoods. We consider the estimation of the integrated likelihood from posterior simulation output, aiming at a generic method that uses only the likelihoods from the posterior simulation iterations. The key is the harmonic mean identity, which says that the reciprocal of the integrated likelihood is equal to the posterior harmonic mean of the likelihood. The simplest estimator based on the identity is thus the harmonic mean of the likelihoods. While this is an unbiased and simulation-consistent estimator, its reciprocal can have infinite variance and so it is unstable in general.
Structured additive regression models are perhaps the most commonly used class of models in stati... more Structured additive regression models are perhaps the most commonly used class of models in statistical applications. It includes, among others, (generalized) linear models, (generalized) additive models, smoothing spline models, state space models, semiparametric regression , spatial and spatiotemporal models, log-Gaussian Cox processes and geostatistical and geoadditive models. We consider approximate Bayesian inference in a popular subset of struc-tured additive regression models, latent Gaussian models, where the latent field is Gaussian, controlled by a few hyperparameters and with non-Gaussian response variables. The posterior marginals are not available in closed form owing to the non-Gaussian response variables. For such models, Markov chain Monte Carlo methods can be implemented, but they are not without problems, in terms of both convergence and computational time. In some practical applications, the extent of these problems is such that Markov chain Monte Carlo sampling is simply not an appropriate tool for routine analysis. We show that, by using an integrated nested Laplace approximation and its simplified version, we can directly compute very accurate approximations to the posterior marginals. The main benefit of these approximations is computational: where Markov chain Monte Carlo algorithms need hours or days to run, our approximations provide more precise estimates in seconds or minutes. Another advantage with our approach is its generality , which makes it possible to perform Bayesian analysis in an automatic, streamlined way, and to compute model comparison criteria and various predictive measures so that models can be compared and the model under study can be challenged.
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Papers by Nicolas Chopin