University of Marne-la-Vallée

About: University of Marne-la-Vallée is a based out in . It is known for research contribution in the topics: Estimator & Context (language use). The organization has 831 authors who have published 1855 publications receiving 55316 citations.

Theoretical study of the HNS+/HSN+ radical cations

Abstract: The three dimensional CASSCF-MRCI potential energy functions have been calculated for the X2A′ and A2A″ electronic states of HNS+ and for the X2A′ state of the HSN+ isomer. In HNS+, the two lowest states form a linear-bent Renner–Teller pair, the MRCI barrier to linearity for the X-state has been calculated to be 1876 cm−1. Both isomers possess a conical intersection resulting from the crossing between the 2Σ+ and 2Π states along the colinear H(2S)+NS+(X1Σ+) dissociation path. The minima of both isomers are found to be separated by a large barrier of 18,042 cm−1 (CASSCF), the HNS+ isomer is calculated to be more stable than HSN+ by 12,202 cm−1 (34.9 kcal/mol) (RCCSD(T)). The proton affinity of the NS radical (NS (X2Π)+H+) has been calculated to be 7.59 eV (RCCSD(T)), the dissociation energy of HNS + → H ( 2 S )+ NS + ( X 1 Σ + ) to be 2.86 eV (RCCSD(T)). Due to several low-lying electronic states of NS+, the protonation and the exothermic charge transfer reactions H++NS→H+NS+ are found to proceed via very complex reaction paths including vibronic and spin–orbit couplings. The results of Renner–Teller variational calculations of the rovibronic levels for the electronic ground state of HNS+ are presented. The onset of this coupling is calculated already in the first bending overtone of the X-state. Also the vibrational levels obtained variationally for the X2A′ state of the HSN+ isomer are given.

Nonparametric estimation of renewal processes from count data

Abstract: The authors address the problem of estimating an inter-event distribution on the basis of count data. They derive a nonparametric maximum likelihood estimate of the inter-event distribution utilizing the EM algorithm both in the case of an ordinary renewal process and in the case of an equilibrium renewal process. In the latter case, the iterative estimation procedure follows the basic scheme proposed by Vardi for estimating an inter-event distribution on the basis of time-interval data; it combines the outputs of the E-step corresponding to the inter-event distribution and to the length-biased distribution. The authors also investigate a penalized likelihood approach to provide the proposed estimation procedure with regularization capabilities. They evaluate the practical estimation procedure using simulated count data and apply it to real count data representing the elongation of coffee-tree leafy axes. Les auteurs abordent le probleme de l'estimation d'une loi inter-evenement a partir de donnees de denombrement. Us obtiennent, en utiliisant l'algorithme EM, l'estimateur non parametrique au sens du maximum de vraisemblance de la loi inter-evenement, a la fois dans le cas d'un processus de renouvellement ordinaire et dans celui d'un processus de renouvellement en equilibre. Dans ce dernier cas, la procedure iterative d'estimation suit le schema de base propose par Vardi pour estimer une loi inter-evenement a partir de donnees d'intervalle de temps; elle combine les sorties de l'etape E correspondant a la loi interevenement et a la loi biaisee par la longueur. Les auteurs etudient aussi une approche par penalisation de la vraisemblance afin de donner des capacites de regularisation a la procedure d'estimation proposee. Ils evaluent la procedure pratique d'estimation sur des donnees de denombrement simulees et l'appliquent a des donnees de denombrement reelles representant l'allongement d'axes feuilles de cafeiers.