Lack of BV bounds for approximate solutions to a two-phase transition model arising from vehicular traffic

We consider wave-front tracking approximate solutions to a two-phase transition model for vehicular traffic. We construct an explicit example showing that the total variation in space of the solution blows up in finite time even for an initial datum with bounded total variation

La grossesse chez les hémodialysées chroniques

La survenue d'une grossesse en hémodialyse chronique (HDC) est rare, mais depuis la description du premier cas par Confortini en 1971, plusieursobservations ont été rapportées. L'hémodialyse a considérablement  amélioré la fertilité de ces patientes. Nous rapportons l'expérience de  douze grossesses survenues entre 1999 et 2014, chez douze patientes d'âge médian 34 ans (22-44), en hémodialyse (HD) depuis 40 mois  (3-72), l'âge gestationnel moyen de diagnostic est de 16 semaines  d'aménorrhée, la grossesse était compliquée dans 50% des cas par un hydramnios. Le terme moyen est de 35 semaine d'aménorrhée (SA) et l'accouchement a été réalisé dans 90% des grossesses par voie basse. Le poids moyen des nouveau-nés est de 1800g. De telles grossesses sont à haut risque du fait de la fréquence des complications. Elles devraient être contrôlées par les équipes multidisciplinaires, et la consultation prénatal ne devrait pas être négligée. L'objectif de ce travail est de rapporter notre expérience concernant la survenue d'une grossesse chez les patientes dialysées et de la confronter aux données de la littérature

Profil des insuffisants rénaux chroniques diabétiques à l’initiation de l’hémodialyse au service de néphrologie et dialyse de l’hôpital militaire de Rabat, Maroc

Le diabète constitue une cause fréquente d'insuffisance rénale chronique terminale (IRCT) dans le monde. Ce travail présente une étude clinique rétrospective dont le but est de décrire le profil clinico-biologique des patients diabétiques en IRCT, de le comparer aux patients non-diabétiques au stade d'IRCT, et de suivre l'évolution de leurs abords vasculaires, afin d'en déduire des conclusions sur une prise en charge particulière des patients diabétiques. Les paramètres cliniques et biologiques concernant les patients mis en hémodialyse dans notre formation entre le 01 janvier 2006 et le 31 décembre 2011, ont été recueilli et analysés. Nous avons procédé à l'étude comparative des patients en fonction de l'existence ou non d'une néphropathie diabétique, et nous nous sommes intéressés à l'évolution de leurs abords vasculaires. Il s'agit de 207 patients insuffisants rénaux chroniques, dont 86 diabétiques. Le groupe des patients diabétiques était moins suivi avant la mise en hémodialyse (3,66 mois vs. 6,32 mois), avec une prise beaucoup plus importante d'antihypertenseurs (1,87 vs. 1,14, p<0,001). L'échec des abords vasculaires était plus important chez les patients diabétiques (45% vs. 27%, p=0,006), avec une survie moyenne plus faible de leurs abords vasculaires (509 vs 753 jours, p=0,003). L'étude comparative des taux d'hémoglobine, de parathormone intacte, d'albuminémie et de C-réactive protéine, entre le groupe de patients diabétiques et non diabétiques était non significative. Notre étude soulève le problème du suivi néphrologique chez les diabétiques, pourtant censés être mieux suivis, et son retentissement sur l'avenir de leurs abords vasculaires.Key words: Diabète, insuffisance rénale chronique, hémodialys

Averaging level control to reduce off-spec material in a continuous pharmaceutical pilot plant

The judicious use of buffering capacity is important in the development of future continuous pharmaceutical manufacturing processes. The potential benefits are investigated of using optimal-averaging level control for tanks that have buffering capacity for a section of a continuous pharmaceutical pilot plant involving two crystallizers, a combined filtration and washing stage and a buffer tank. A closed-loop dynamic model is utilized to represent the experimental operation, with the relevant model parameters and initial conditions estimated from experimental data that contained a significant disturbance and a change in setpoint of a concentration control loop. The performance of conventional proportional-integral (PI) level controllers is compared with optimal-averaging level controllers. The aim is to reduce the production of off-spec material in a tubular reactor by minimizing the variations in the outlet flow rate of its upstream buffer tank. The results show a distinct difference in behavior, with the optimal-averaging level controllers strongly outperforming the PI controllers. In general, the results stress the importance of dynamic process modeling for the design of future continuous pharmaceutical processes

Mathematical Modeling, Design, and Optimization of a Multisegment Multiaddition Plug-Flow Crystallizer for Antisolvent Crystallizations

This document is the Accepted Manuscript version of a Published Work that appeared in final form in Organic Process Research and Development, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see http://dx.doi.org/10.1021/acs.oprd.5b00110In the pharmaceutical industries, the requirements of rapid process development and scalable design have made the tubular crystallizer a promising platform for continuous manufacturing and crystallization processes, capable of replacing conventional capital- and labor-intensive batch operations. This paper takes a process systems engineering (PSE) approach to the optimal design of a continuous antisolvent addition crystallizer to deliver the most promising product qualities, such as the crystal size distribution. A multisegment multiaddition plug-flow crystallizer (MSMA-PFC) is considered as an example of a continuous antisolvent crystallization process, in which the total number, location, and distribution of antisolvent additions are to be optimized. First-principles dynamic and steady-state mathematical models for the MSMA-PFC are presented, based on example kinetic models for nucleation and growth of paracetamol crystallizing in acetone, with water as the antisolvent. The performances of different crystallizer configurations operated under optimal design conditions are then compared. The configuration in which antisolvent could be added at a variety of different locations along the tube length and at optimal flow rates was able to outperform previous designs in the literature which considered equally spaced antisolvent additions. The use of dynamic models to detect problems during startup of an MSMA-PFC was also highlighted

Bronchodilation induced by PGE2 is impaired in Group-III pulmonary hypertension

BACKGROUND AND PURPOSE: In patients with pulmonary hypertension (PH) associated with lung disease and/or hypoxia (Group III), a reduction of pulmonary vascular tone and tissue hypoxia are considered therapeutically beneficial. Prostaglandin (PG) E2 and PGI2 induce potent relaxation of human bronchi from non-PH (control) patients via EP4 and IP receptors, respectively. However, the effects of PGE2 /PGI2 and their mimetics on human bronchi from PH-patients are unknown. Our aim was to compare the relaxant effects of several PGI2 -mimetics approved for treating PH-Group I with several PGE2 -mimetics in bronchial preparations derived from PH-Group III and control patients. EXPERIMENTAL APPROACH: Using an organ bath system, the tone of bronchial muscle was investigated in tissue from either control or PH-Group III patients. Expression of prostanoid receptors were analyzed by Western blot and real-time PCR and endogenous PGE2 , PGI2 and cAMP levels were determined by ELISA. KEY RESULTS: Maximal relaxations induced by different EP4 agonists (PGE2 , L-902688, ONO-AE1-329) were significantly decreased in human bronchi from PH-patients versus controls. In contrast, the maximal relaxations produced by PGI2 -mimetics (iloprost, treprostinil, beraprost) were similar for both groups of patients. Both EP4 and IP receptor protein and mRNA expressions were significantly lower in human bronchi from PH-patients. cAMP levels significantly correlated with PGI2 but not with PGE2 levels. CONCLUSION AND IMPLICATIONS: This study shows that PGI2 -mimetics have preserved maximal bronchodilation in PH-Group III patients. The decreased bronchodilation induced by EP4 agonists suggests that restoration of EP4 expression in airways of PH-patients with respiratory diseases could bring additional therapeutic benefit

The accumulation of assembly intermediates of the mitochondrial complex I matrix arm is reduced by limiting glucose uptake in a neuronal-like model of MELAS syndrome

Ketogenic diet (KD) which combined carbohydrate restriction and the addition of ketone bodies has emerged as an alternative metabolic intervention used as an anticonvulsant therapy or to treat different types of neurological or mitochondrial disorders including MELAS syndrome. MELAS syndrome is a severe mitochondrial disease mainly due to the m.3243A > G mitochondrial DNA mutation. The broad success of KD is due to multiple beneficial mechanisms with distinct effects of very low carbohydrates and ketones. To evaluate the metabolic part of carbohydrate restriction, transmitochondrial neuronal-like cybrid cells carrying the m.3243A > G mutation, shown to be associated with a severe complex I deficiency was exposed during 3 weeks to glucose restriction. Mitochondrial enzyme defects were combined with an accumulation of complex I (CI) matrix intermediates in the untreated mutant cells, leading to a drastic reduction in CI driven respiration. The severe reduction of CI was also paralleled in post-mortem brain tissue of a MELAS patient carrying high mutant load. Importantly, lowering significantly glucose concentration in cell culture improved CI assembly with a significant reduction of matrix assembly intermediates and respiration capacities were restored in a sequential manner. In addition, OXPHOS protein expression and mitochondrial DNA copy number were significantly increased in mutant cells exposed to glucose restriction. The accumulation of CI matrix intermediates appeared as a hallmark of MELAS pathophysiology highlighting a critical pathophysiological mechanism involving CI disassembly, which can be alleviated by lowering glucose fuelling and the induction of mitochondrial biogenesis, emphasizing the usefulness of metabolic interventions in MELAS syndrome

Mathematical modeling and design of layer crystallization in a concentric annulus with and without recirculation

A solution layer crystallization process in a concentric annulus is presented that removes the need for filtration. A dynamic model for layer crystallization with and without a recirculation loop is developed in the form of coupled partial differential equations describing the effects of mass transfer, heat transfer, and crystallization kinetics. The model predicts the variation of the temperature, concentration, and dynamic crystal thickness along the pipe length, and the concentration and temperature along the pipe radius. The model predictions are shown to closely track experimental data that were not used in the model's construction, and also compared to an analytical solution that can be used for quickly obtaining rough estimates when there is no recirculation loop. The model can be used to optimize product yield and crystal layer thickness uniformity, with constraints on the supersaturation to avoid bulk nucleation by adjusting cooling temperatures in the core and jacket. © 2013 American Institute of Chemical Engineers

Mathematical modeling and design of layer crystallization in a concentric annulus with and without recirculation [Abstract]

Mathematical modeling and design of layer crystallization in a concentric annulus with and without recirculation [Abstract