37 research outputs found
Monotonically convergent optimization in quantum control using Krotov's method
The non-linear optimization method developed by Konnov and Krotov [Automation
and Remote Control 60, 1427 (1999)] has been used previously to extend the
capabilities of optimal control theory from the linear to the non-linear
Schr\"odinger equation [Sklarz and Tannor, Phys. Rev. A 66, 053619 (2002)].
Here we show that based on the Konnov-Krotov method, monotonically convergent
algorithms are obtained for a large class of quantum control problems. It
includes, in addition to non-linear equations of motion, control problems that
are characterized by non-unitary time evolution, non-linear dependencies of the
Hamiltonian on the control, time-dependent targets and optimization functionals
that depend to higher than second order on the time-evolving states. We
furthermore show that the non-linear (second order) contribution can be
estimated either analytically or numerically, yielding readily applicable
optimization algorithms. We demonstrate monotonic convergence for an
optimization functional that is an eighth-degree polynomial in the states. For
the 'standard' quantum control problem of a convex final-time functional,
linear equations of motion and linear dependency of the Hamiltonian on the
field, the second-order contribution is not required for monotonic convergence
but can be used to speed up convergence. We demonstrate this by comparing the
performance of first and second order algorithms for two examples
A Chebychev propagator for inhomogeneous Schr\"odinger equations
We present a propagation scheme for time-dependent inhomogeneous
Schr\"odinger equations which occur for example in optimal control theory or in
reactive scattering calculations. A formal solution based on a polynomial
expansion of the inhomogeneous term is derived. It is subjected to an
approximation in terms of Chebychev polynomials. Different variants for the
inhomogeneous propagator are demonstrated and applied to two examples from
optimal control theory. Convergence behavior and numerical efficiency are
analyzed.Comment: explicit description of algorithm and two appendices added version
accepted by J Chem Phy
Control of molecular dynamics with zero-area fields: Application to molecular orientation and photofragmentation
The constraint of time-integrated zero-area on the laser field is a
fundamental, both theoretical and experimental requirement in the control of
molecular dynamics. By using techniques of local and optimal control theory, we
show how to enforce this constraint on two benchmark control problems, namely
molecular orientation and photofragmentation. The origin and the physical
implications on the dynamics of this zero-area control field are discussed.Comment: 19 pages, 7 figure
A Chebychev propagator with iterative time ordering for explicitly time-dependent Hamiltonians
A propagation method for time-dependent Schr\"odinger equations with an
explicitly time-dependent Hamiltonian is developed where time ordering is
achieved iteratively. The explicit time-dependence of the time-dependent
Schr\"odinger equation is rewritten as an inhomogeneous term. At each step of
the iteration, the resulting inhomogeneous Schr\"odinger equation is solved
with the Chebychev propagation scheme presented in J. Chem. Phys. 130, 124108
(2009). The iteratively time-ordering Chebychev propagator is shown to be
robust, efficient and accurate and compares very favorably to all other
available propagation schemes
Systèmes à libération contrôlée pH-dépendants de principes actifs hydrophobes à partir d’oléogels
Les rhumatismes inflammatoires chroniques sont une cause importante d'invalidité dans le monde entier. De ce fait, les affections rhumatismales chroniques font peser une lourde charge sociale et économique sur toutes les sociétés, pas seulement sur celles où l’espérance de vie est élevée. L’objectif principal de ce travail était d’étudier le profil de libération pH-dépendante de principes actifs hydrophobes à partir d’oléogels oraux et/ou cutanés. La formulation des oléogels a été réalisée selon une méthode sol-gel, reproductible à grande échelle. La caractérisation et le suivi dans le temps ont montré une bonne stabilité des oléogels. Les valeurs de pH des oléogels étaient globalement acides (entre 4,3 et 5,8) et dépendaient de la quantité de gélifiant utilisée. Les études de libération du kétoprofène, principe actif hydrophobe, en fonction du pH des milieux de dissolution ont montré des profils de libération d’une cinétique du premier ordre d’équation =+. avec des coefficients de détermination proches de 1 (milieux à pH égal à 1,2 et 5,5). Une meilleure libération du kétoprofène a été obtenue dans un milieu intestinal simulé (pH égal à 6,8) pour les formulations qui présentaient déjà une saturation en milieu gastrique simulé (pH égal à 1,2). Cette étude qui a permis de formuler, d’évaluer et de modéliser le profil de libération du kétoprofène à partir d’oléogels peut constituer une étape importante dans un objectif de souveraineté thérapeutique des pays d’Afrique subsaharienne notamment le Sénégal.Mots clés : Oléogels, rhumatismes inflammatoires chroniques, kétoprofène, libération contrôlée, pH-dépendant.
English Title: pH-dependent controlled release systems of hydrophobic active pharmaceutical ingredients from oleogels
Chronic inflammatory rheumatism is a major cause of disability around the world. As a result, chronic rheumatic diseases place a heavy social and economic burden on all societies, not just those with high life expectancy. The main objective of this work was to control the pH-dependent release of hydrophobic active pharmaceutical ingredients from oral and / or skin oleogels. The formulation of the oleogels was carried out using a sol-gel large-scale reproducible method. Characterization and monitoring over time have shown good stability of the oleogels. The pH values of the oleogels were overall acid (between 4.3 and 5.8) and depended on the amount of gelling agent used. The release studies of ketoprofen, a hydrophobic active pharmaceutical ingredient, as a function of the pH of the dissolution media have shown release profiles of first-order kinetics of equation =+. with coefficients of determination close to 1 (media at pH equal to 1.2 and 5.5). Better release of ketoprofen was obtained in simulated intestinal medium (pH equal to 6.8) for formulations which already exhibited saturation in simulated gastric medium (pH equal to 1.2). This study, which made it possible to formulate, evaluate and model the release profile of ketoprofen from oleogels, may constitute an important step in an objective of therapeutic sovereignty of the countries of sub-Saharan Africa, particularly Senegal.Keywords: oleogels - chronic inflammatory rheumatism - ketoprofen - controlled release – pH-dependent
Barcoding: Comparison of Variation Degree of COI and Cytochrome b Mitochondrial Markers in Two Species Primary Maize Pests (Sitophilus zeamais and Sitophilus oryzae)
The phylogeny, taxonomy and identification of insects were originally based upon shared or derived morphological and anatomy criteria. However, these processes are confronted with the barrier of the existence of sympatric or cryptic species. Thus, genetic analyses have more recently played an increasingly important role in confirming existing or establishing often radically different insect
Two-photon coherent control of femtosecond photoassociation
Photoassociation with short laser pulses has been proposed as a technique to
create ultracold ground state molecules. A broad-band excitation seems the
natural choice to drive the series of excitation and deexcitation steps
required to form a molecule in its vibronic ground state from two scattering
atoms. First attempts at femtosecond photoassociation were, however, hampered
by the requirement to eliminate the atomic excitation leading to trap
depletion. On the other hand, molecular levels very close to the atomic
transition are to be excited. The broad bandwidth of a femtosecond laser then
appears to be rather an obstacle. To overcome the ostensible conflict of
driving a narrow transition by a broad-band laser, we suggest a two-photon
photoassociation scheme. In the weak-field regime, a spectral phase pattern can
be employed to eliminate the atomic line. When the excitation is carried out by
more than one photon, different pathways in the field can be interfered
constructively or destructively. In the strong-field regime, a temporal phase
can be applied to control dynamic Stark shifts. The atomic transition is
suppressed by choosing a phase which keeps the levels out of resonance. We
derive analytical solutions for atomic two-photon dark states in both the
weak-field and strong-field regime. Two-photon excitation may thus pave the way
toward coherent control of photoassociation. Ultimately, the success of such a
scheme will depend on the details of the excited electronic states and
transition dipole moments. We explore the possibility of two-photon femtosecond
photoassociation for alkali and alkaline-earth metal dimers and present a
detailed study for the example of calcium
Analyse physico-chimique de l’eau de l’unité d’hémodialyse du chr de Saint- Louis (Sénégal)
L’insuffisance rénale chronique est un des problèmes majeurs de la santé publique dans le monde. Au Sénégal, une étude récente réalisée dans la population générale adulte avait retrouvé une prévalence de l’ordre de 6,1%. «L’eau pour dilution de concentrées d’hémodialyse» est produite en continue et utilisée en grande quantité chez l’hémodialysé chronique, donc il apparaît primordial de veiller à sa bonne qualité. Au Sénégal, aucune étude n’a été faite à ce jour pour évaluer l’efficacité du système de traitement de l’eau pour dilution des concentrés de dialyse dans les différents centres de dialyse du pays. L’objectif de ce travail est de contrôler l’efficacité du système de traitement de l’eau pour dilution de concentrées d’hémodialyse afin de s’assurer de son innocuité. Les prélèvements ont été effectués au niveau de trois points clés du circuit de traitement de l’eau pour hémodialyse. A l’entrée et à la sortie de l’osmoseur, à la sortie de la boucle de distribution. Les analyses ont été effectuées à l’aide d’électrodes spécifiques. Les valeurs de potentiels ont permis de tracer les courbes d’étalonnage. La détermination par régression des pentes et des ordonnées à l’origine de la relation de Nernst donne E(mV ) = B - A Log Cm avec des coefficients de corrélation variant entre 0,988 et 0,999 prouvant que 98% au moins des variations de tensions mesurées (E) sont attribuables à la concentration. L’analyse physico-chimique des teneurs en chlorures, nitrates et fluorures révèle des teneurs plus élevées à l’entrée de l’osmoseur qu’à la sortie. Ces basses valeurs découlent du rôle de l’osmoseur qui filtre une grande partie des électrolytes. Par contre, à la sortie de la boucle de distribution les teneurs en électrolytes des différents échantillons étaient plus importantes que celles à la sortie de l’osmoseur. Cette forte concentration en électrolytes atteste d’une pollution par la boucle de distribution de l’eau déjà filtrée par l’osmoseur. L’intérêt de cette étude réside dans le fait qu’elle met en lumière l’importance du contrôle de la qualité de l’eau pour l’hémodialyse et la nécessité d’un bon planning de maintenance préventive efficace de l’ensemble de la boucle de traitement d’eau au sein de chaque centre.© 2016 International Formulae Group. All rights reserved.Mots clés: Hémodialyse, eau, chlorures, fluorures, nitrates, électrodes spécifiquesEnglish Title: Physicochemical analysis of Saint–Louis regional hospital’s hemodialysis unit’s water (Senegal)English AbstractChronic kidney disease is a major public health problem worldwide. In Senegal, a recent study in the general adult population found a prevalence of about 6,1%. "Water for diluting concentrated hemodialysis" is produced and used continuously at high levels in hemodialysis chronic. It is therefore essential to ensure its quality. In Senegal, no study has been done to assess the effectiveness of water treatment system for dialysis concentrates dilution in different dialysis centers of the country. The objective of this work is to monitor the effectiveness of the water treatment system for hemodialysis concentrated dilution to ensure its safety. The samples were taken on key issues of hemodialysis water’s treatment circuit. Three levels of sampling were selected. At the entrance and at the outlet of the reverse osmosis unit at the outlet of the distribution loop. Analyses were performed using specific electrodes. Potential values allowed us to map the calibration curves. Determination by regression of slopes and intercepts of the Nernst relation gives with correlation coefficients ranging from 0.988 to 0.999 showing that at least 98% of the measured voltages fluctuations (E) are attributable to the concentration. Physicochemical analysis of the levels of chlorides, nitrates and fluorides reveals higher levels at the entrance of the reverse osmosis unit than at the outlet. These low values resulting of the role of reverse osmosis which filter much of the electrolytes. For against, at the outlet of the distribution loop the electrolyte content of the different samples were greater than those at the outlet of the reverse osmosis unit. This high electrolyte concentration attests to pollution of the water distribution loop already filtered by reverse osmosis. The interest of this study lies in the fact that it highlights the importance of monitoring the quality of water for hemodialysis and the need for good planning for effective preventive maintenance throughout the water treatment loop within each center.© 2016 International Formulae Group. All rights reserved.Keywords: Hemodialysis, water, nitrates, fluoride, chloride, specific electrode
Evaluation de l’état hydrique chez les patients hémodialysés chroniques : une étude transversale monocentrique: Assessment of the hydration status in chronic hemodialysis patients: a single-center cross-sectional study
Context and objective. For many practitioners, blood pressure is the main indicator of the hydration status of the chronic hemodialysis patient. The objective of this study was to assess the extent to which bioimpedance analysis (BIA) can assist in determining acute changes in fluid volume during the hemodialysis session. Methods. This was a 9-week longitudinal study. The total body water (TBW) was measured with a BIA analyzer, before and after 6 successive sessions. The ΔWeight was compared to the ΔTBW by calculating the P/V ratio (ΔWeight/ΔTBW) with the assumption that the dry weight is reached when P/V = 1. Results. The measurements made in 22 patients (46.6 years, 54.5% men, 92.3 months on dialysis) were reproducible. There was no statistically significant difference between ΔTBW and ΔWeight. However, at the individual level, significant differences had been observed. Using hypertension as a marker for a state of hyperhydration, a 31.8% agreement was noted between the P/V ratio and hypertension. Conclusion. Although the loss of water predicted by the BIA did not always correspond to the weight loss, BIA is a technique that can be used to assess the variations in TBW during the hemodialysis session in patients.
Contexte et objectif. La pression artérielle est pour de nombreux praticiens, l’indicateur principal du statut hydrique du patient hémodialysé chronique. L’objectif de la présente étude était d’évaluer dans quelle mesure l’analyse d’impédance bioélectrique (BIA) pourrait aider à la détermination des variations aigues du volume hydrique au cours de la séance d’hémodialyse. Méthodes. Il s’agissait d’une étude de suivi longitudinal sur 9 semaines. Le volume total d’eau (VTE) a été mesuré par BIA, avant et après 6 séances. Le ΔPoids a été comparé au ΔVTE par le calcul du ratio P/V (ΔPoids / ΔVTE) dans l’hypothèse que le poids sec est atteint lorsque P/V = 1. Résultats. Les mesures faites chez 22 patients (46,6 ans, 54,5% hommes, 92,3 mois en dialyse) étaient reproductibles. Il n’y avait pas de différence statistiquement significative entre le ΔVTE et le ΔPoids. Cependant à l’échelon individuel des différences importantes étaient observées. En utilisant l’hypertension artérielle (HTA) comme marqueur d’un état d’hyperhydratation, une concordance de 31,8% était notée entre le ratio P/V et l’HTA. Conclusion. Bien que la perte d’eau prédite par la BIA ne corresponde pas toujours à celle du poids, la BIA est une technique qui peut être utilisée pour évaluer les variations du VTE au cours de la séance d’hémodialys