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Les eaux usées véhiculent des quantités élevées d’énergie qui peuvent être récupérées au moyen d’une pompe à chaleur et d’un échangeur thermique. L’estimation du potentiel de récupération de chaleur des eaux usées demande de connaître essentiellement leur débit et la quantité de chaleur à extraire ΔT (°C). Pour cette dernière, la valeur de 4,5 °C est couramment utilisée pour des études de cartographie énergétique des systèmes d’assainissement, car elle représente la valeur moyenne des opérations existantes en France. Toutefois cette valeur ne prend pas en compte le potentiel impact sur la station de traitement des eaux usées (STEU). En effet, récupérer trop de chaleur dans le réseau d’assainissement peut provoquer une diminution de la température des effluents au niveau de la STEU. Cet abaissement peut compromettre la qualité des processus biologiques de nitrification et dénitrification. D’après la littérature, une baisse de 1 °C en entrée de STEU ne représenterait pas de risque de dégradation des procédés biologiques à condition que la station ne fonctionne pas au maximum de sa capacité et que la température ne descende pas au-dessous de la température minimale de dimensionnement. En respectant ces conditions à l’entrée de La Wantzenau, principale STEU de l’Eurométropole de Strasbourg, les quantités de chaleur à extraire ΔT (°C) dans tout point du réseau ont été estimées. Cela a permis de calculer un potentiel de récupération qui tient compte de l’impact sur la STEU et de le comparer avec un potentiel théorique calculé avec une extraction de 4,5 °C. Les résultats montrent que, sur certains points, l’extraction de 4,5 °C provoque des variations de température supérieures à 1 °C en entrée de STEU et conduit à des surestimations du potentiel de récupération. La puissance de récupération de chaleur calculée, en intégrant l’impact prévisionnel sur La Wantzenau, est ainsi plus réduite, mais constitue un réel intérêt pour identifier des projets de récupération qui semblent plus réalistes.

We focus on a toy problem which corresponds to a simplification of a boiling twophase flow model. This model is a hyperbolic system of balance laws with a source term defined as a discontinuous function of the unknown. Several discretizations of this source terms are studied, and we illustrate their capacity to capture steady states.

Resume Objectif L’objectif de cette etude etait d’analyser les caracteristiques epidemiologiques des urgences ophtalmologiques du Centre Hospitalier de Bourges (CHB) et d’identifier les criteres associes a un score de severite eleve en contexte d’offre de soin deficitaire. Methode Il s’agit d’une etude retrospective sur les urgences ophtalmologiques du CHB conduite entre le 1er janvier 2019 et le 30 avril 2019. Sept criteres demographiques et 9 medicaux ont ete colliges, puis classes selon le score de severite Base Score. Des regressions lineaires uni et multivariees ont identifie les criteres dont le score de severite etait eleve. Resultats Le nombre de patients inclus etaient de 1809 (âge moyen : 53,3 ± 22,7 ans, 51,4 % de femmes) et 1619 (89,5 %) patients consultaient sans avoir ete oriente par un professionnel de sante. Les pathologies de la surface oculaire (12,5 %) representaient le diagnostic le plus frequent. Les variables sexe masculin, consultation orientee par un medecin specialiste ou non, la distance eloignee entre le CHB et le domicile, un delai court de consultation depuis l’apparition des symptomes etaient significativement associees a un diagnostic plus severe selon le Base Score. Le coefficient de regression etait superieur a 1 uniquement pour le mode d’orientation par un medecin specialiste, ophtalmologue ou non. Conclusion Notre etude montre que lorsqu’un acces direct est possible en structure d’urgence ophtalmologique dans un territoire a offre de soin deficitaire, 9 patients sur 10 consultent d’eux-memes. Les items d’urgences oculaires adresses par le reseau medical de proximite peuvent etre consideres comme severe a priori.

The Ambulatory Clinic for Cataract Surgery (CACC) is a public department of the Bourges Medical Center, with a fast-track protocol without perioperative anesthesia care launched in 2015. This study aimed to evaluate the benefits of the CACC in terms of access to cataract surgery.This retrospective study included all patients undergoing cataract surgery between 2012 and 2018. Data were collected from the French PMSI database. In order to evaluate the impact of the CACC, the surgical activity and change in indicators of patient flow and usage, as well as clinical and economic factors were analyzed.Between 2012 and 2018, with the same number of ophthalmologists, surgical activity increased by 50.2% in the Cher (vs. a mean increase of 22.7% in France). The patient loss ratio decreased by 5.9 points, the attraction and self-sufficiency ratios increased by 2.3 and 8.6 points respectively. The standardized rate of healthcare utilization for cataract surgery increased by 4.3 points (from 11.6 to 15.9 surgeries per 1000 inhabitants). As a result, Cher became the second highest French Department in 2018 in terms of utilization rate despite its 96th place out of 109 Departments in terms of density of ophthalmologists.The ambulatory cataract surgery center without anesthesia for selected patients might represent a solution in medical deserts to improve access to cataract surgery without increasing costs.

This study aimed to analyse the epidemiological characteristics of ophthalmological emergencies at the Bourges Medical Center (CHB) and to identify factors associated with severity according to the Base Score in a region of France considered a healthcare desert.All consecutive charts of patients seen for an eye-related condition between January 1 and April 30, 2019 in the ocular emergency department of the CHB were studied retrospectively. Seven demographic and nine medical variables were collected, and ocular severity was defined according to the Base Score. Linear regressions were performed to identify the factors associated with higher severity.1809 patients were included (mean age: 53.3±22.7 years, 51.4% women), of whom 1619 (89.5%) were self-referred. Ocular surface disease (12.5%) was the most frequent diagnosis. The severity of the eye-related condition was significantly associated with the following factors: male gender, distance from home to the emergency department, presentation soon after the onset of symptoms, and referral from a physician (ophthalmologist or not). The regression coefficient was greater than 1 only for the patient referral pattern.The current study highlights that when patients with ocular emergencies can self-refer to an ocular emergency department within a French healthcare desert, 9 patients out of 10 self-refer. Referral from a physician is the main factor associated with ocular severity; thus, these cases should be considered severe until proven otherwise.

Resume Introduction L’atteinte oculomotrice dans l’orbitopathie dysthyroidienne est a l’origine de troubles oculomoteurs restrictifs. Nous rapportons notre prise en charge chirurgicale chez ces patients. Patients et methodes Nous presentons une etude retrospective portant sur 32 patients operes entre 2008 et 2017. La chirurgie etait proposee en phase inactive avec troubles oculomoteurs stables depuis au moins 6 mois. Elle etait realisee sous anesthesie generale avec comme geste principal un recul des muscles restrictifs sans suture ajustable. Nous avons hierarchise les resultats postoperatoires en fonction, de la persistance ou non d’une diplopie en position primaire ou en position de lecture, et en fonction d’un recours ou non a une compensation prismatique. Resultats Trente-deux patients, dont 21 femmes et 11 hommes, d’âge moyen 53 ans ont ete inclus dans cette etude. Le recul moyen est de 9,6 mois. Huit patients avaient un trouble oculomoteur apparu suite a une decompression orbitaire. Quinze patients ont ete operes d’une chirurgie verticale, 8 d’une chirurgie horizontale et 9 d’une chirurgie mixte. Le nombre moyen de temps chirurgical est de 1,31 (1 a 3). A l’issue des differents temps operatoires, nous obtenons un resultat excellent chez 28 patients (87,5 %), bon chez 4 patients (12,5 %) et une amelioration statistiquement significative de la vision stereoscopique en postoperatoire (p Conclusion Cette technique chirurgicale avec sutures fixes, nous permet d’obtenir d’excellents resultats sur l’alignement oculaire et la disparition de la diplopie, avec un taux de reintervention comparable a d’autres techniques, telles que les sutures ajustables, ou la correction de la restriction musculaire.

This work consists of the validation of a new Grid Based Boltzmann Solver (GBBS) conceived for the description of the transport and energy deposition by energetic particles for radiotherapy purposes. The entropic closure and a compact mathematical formulation allow our code (M1) to calculate the delivered dose with an accuracy comparable to the Monte-Carlo (MC) codes with a computational time that is reduced to the order of few minutes without any special processing power requirement. A validation protocol with heterogeneity inserts has been defined for different photon sources. The comparison with the MC calculated depth-dose curves and transverse profiles of the beam at different depths shows an excellent accuracy of the M1 model.

Particle transport in radiation therapy can be modelled by a kinetic equation which must be solved numerically. Unfortunately, the numerical solution of such equations is generally too expensive for applications in medical centers. Moment methods provide a hierarchy of models used to reduce the numerical cost of these simulations while preserving basic properties of the solutions. Moment models require a closure because they have more unknowns than equations. The entropy-based closure is based on the physical description of the particle interactions and provides desirable properties. However, computing this closure is expensive. We propose an approximation of the closure for the first two models in the hierarchy, the $$M_1$$M1 and $$M_2$$M2 models valid in one, two or three dimensions of space. Compared to other approximate closures, our method works in multiple dimensions. We obtain the approximation by a careful study of the domain of realizability and by invariance properties of the entropy minimizer. The $$M_2$$M2 model is shown to provide significantly better accuracy than the $$M_1$$M1 model for the numerical simulation of a dose computation in radiotherapy. We propose a numerical solver using those approximated closures. Numerical experiments in dose computation test cases show that the new method is more efficient compared to numerical solution of the minimum entropy problem using standard software tools.

The transport of photons and electrons is studied in the field of radiotherapy to compute the dose, that is, the quantity of energy transferred to the medium by a beam of particles at each position. A kinetic model is proposed, and to decrease the computation times, it is reduced through a moment extraction. Entropy-based angular moment models of order up to two (M1 and M2 models) are shown to provide accurate results compared to a reference code with much lower computational costs.

A new deterministic method for calculating the dose distribution in the electron radiotherapy field is presented. The aim of this work was to validate our model by comparing it with the Monte Carlo simulation toolkit, GEANT4. A comparison of the longitudinal and transverse dose deposition profiles and electron distributions in homogeneous water phantoms showed a good accuracy of our model for electron transport, while reducing the calculation time by a factor of 50. Although the Bremsstrahlung effect is not yet implemented in our model, we propose here a method that solves the Boltzmann kinetic equation and provides a viable and efficient alternative to the expensive Monte Carlo modeling.

Typical external radiotherapy treatments consist in emitting beams of energetic photons targeting the tumor cells. Those photons are transported through the medium and interact with it. Such interactions affect the motion of the photons but they are typically weakly deflected which is not well modeled by standard numerical methods. The present work deals with the transport of photons in water. The motion of those particles is modeled by an entropy-based moment model, i.e. the M 1 model. The main difficulty when constructing numerical approaches for photon beam modelling emerges from the significant difference of magnitude between the diffusion effects in the forward and transverse directions. A numerical method for the M 1 equations is proposed with a special focus on the numerical diffusion effects.

Thyroid-related immune orbitopathy often results in a restrictive strabismus. We report our experience of surgical management in these cases.We present a retrospective case series conducted on 32 patients, operated between 2008 and 2017. Strabismus surgery was proposed in the postinflammatory stage with stable clinical findings for at least 6 months. It was performed under general anesthesia by recessions of restrictive muscles using a fixed suture technique. Outcomes were graded as excellent, good or poor, according to the presence or absence of diplopia in primary or reading positions, and according to whether prism prescription was necessary.The study included 32 patients (21 women, 11 men) with a mean age of 53 years. Average follow-up was 9.6 months. Eight patients developed diplopia after orbital decompression. Fifteen patients had vertical surgery, 8 horizontal surgery, 9 mixed surgery. A mean of 1.31 surgeries (range 1-3) were performed. After all surgeries, 28 patients (87.5 %) had an excellent outcome, 4 (12.5 %) had a good outcome, and none had a poor outcome. There was a significant improvement in stereoscopic acuity (P0.01), but not motility. Among the 8 patients who developed diplopia after orbital decompression, a clinically acceptable final outcome was achieved after only one surgery.Strabismus surgery using conventional non-adjustable sutures provides excellent ocular alignment and relief from diplopia in the majority of patients with dysthyroid strabismus. The reoperation rate is similar to other techniques, such adjustable suture and intraoperative relaxed muscle technique.

Dans le cadre de la modernisation d’une usine de production d’eau potable, il a ete procede a la mise en oeuvre d’une decarbonatation sur resines. La regeneration de ces resines s’effectuait a l’acide chlorhydrique. Quelques mois apres la mise en service de l’installation, la defaillance d’une des deux pompes doseuses d’acide chlorhydrique a conduit a un deversement important d’acide dans la structure nouvellement rehabilitee, entrainant des degâts irreversibles sur l’equipement.Il a finalement ete decide de reconstruire une nouvelle installation neuve sur le site existant et de deconstruire celles existantes.

Introduction The majority of patients affected by cancer are nowadays treated by radiotherapy, which consists in delivering a homogeneous dose with energetic particles. Magnetic Resonance Imaging (MRI)-guided radiotherapy shows precisely the tumor position in real time and allows to direct the photon beams to the tumor while sparing organs at risks. Our work consists in the validation of a new model developped to simulate the energy deposition of the particles used in radiotherapy (electrons, photons and protons) in the presence of strong magnetic field, within human tissues, and its adaptation to this new technology. Material and methods This model is based on a kinetic entropic closure of the linearized Boltzmann equation [1] , which describes the transport of energetic particles in the matter. This equation takes a lot of computation time to be solved due to the high number of variables. To simplify this, we replace fluences by angular moments, which allows getting rid of the angular variables and improve the calculation time. We obtain a set of angular moments equations, and we close this set using the Boltzmann’s principle of entropy maximization on the two first equations of the set. This model has an accuracy comparable to references Monte-Carlo (MC) codes [2] (Geant4, MCNPx, Penelope), and is less time-consuming than these ones. We added the Lorentz force into our code to study the influence of a magnetic field on the dose deposition, and compared it to the reference full MC code FLUKA. To further validate our model, we have carried out an experimental campaign in which we irradiated a composition of materials of different mass densities, with 6 and 18 MV photon beams of a Varian Clinac 21Ex accelerator, without and with the influence of a 0.87 T magnetic field of amplitude induced by a permanent magnet. Results We show a good agreement between our model and the FLUKA code ( Fig. 1 ). We highlight the effects that occur on the propagation of particles in the matter in presence of a magnetic field of a few Tesla. Indeed, it modifies the dose deposition by shifting the deposition of energy, leading to an increased diffusion depending on the orientation of the magnetic field. Moreover, it also leads to an increase or decrease of the dose deposited at the interfaces between materials depending on their difference between mass densities. The results of our experiments lead to the same conclusions. These effects have to be taken into account in order to prevent creation of hot spots or a spread of energy distribution in a human body, within computation times compatible with the clinical environment. Conclusion Our model is a good candidate for future Treatment Planning Systems since it allows a faster and efficient way to plan a viable treatment for a patient in presence of strong magnetic fields. A magnetic field modifies the profile of the dose deposition such as it has to be taken into account in calculations to prevent the dramatic changes which occur at interfaces between media of different density. This work takes place in the framework of POPRA (Programme Optique Physique et Radiotherapie en Aquitaine), which involves several laboratories around problematics on the topic of cancer treatment.

Introduction This work proposes a completely new Grid-Based Boltzmann Solver (GBBS) developed for the transport and energy deposition by energetic particles. Its entropic closure and mathematical formulation allow our entropic model to calculate the delivered dose with an accuracy comparable to Monte Carlo (MC) codes with a computational time that is reduced to the order of few seconds without any special processing power requirement. Methods In contrast to discrete ordinates angular discretization methods, such as Acuros®, our method is based on a reduced number of moment equations closed with Boltzmann’s H-theorem. Keeping a good accuracy of calculations, the algorithm can simulate different treatment techniques such as the external radiotherapy even in presence of magnetic field [1] , [2] (e.g., MRI-guided radiotherapy), brachytherapy or intra-operative radiation therapy. The first validation step consists in simulating dose distributions in complex numerical phantoms including a large number of heterogeneity shapes such as bone, lung and air. For both brachytherapy and external beam radiotherapy, simulations based on CT scan, using the real phase-space of the source, have been performed. The entropic model is validated by a direct comparison with the reference MC code PENELOPE. Results The code is capable of calculating 3D dose distributions with 1 mm3voxels without statistical uncertainties in few seconds instead of several minutes like PENELOPE. In brachytherapy applications the dose distributions significantly differ from those calculated with the TG-43 approximations, thanks to its capability to account for inhomogeneities and strong density gradients. Moreover, for both applications the code shows an excellent agreement with PENELOPE within the 1%/1 mm gamma-index criterion. Conclusions In the comparison with the MC results the excellent accuracy of the model is demonstrated. Thanks to its reduced computational time and its accuracy, this model is a promising candidate to become a real-time dose calculation algorithm.

Because of stability constraints, most numerical schemes applied to hyperbolic systems of equations turn out to be costly when the flux term is multiplied by some very large scalar. This problem emerges with the M1 system of equations in the field of radiotherapy when considering heterogeneous media with very disparate densities. Additionally, the flux term of the M1 system is non-linear, and in order for the model to be well-posed the numerical solution needs to fulfill conditions called realizability. In this paper, we propose a numerical method that overcomes the stability constraint and preserves the realizability property. For this purpose, we relax the M1 system to obtain a linear flux term. Then we extend the stencil of the difference quotient to obtain stability. The scheme is applied to a radiotherapy dose calculation example.

Les changements climatiques sont annonces comme inevitables pour les decennies a venir (augmentation des temperatures, phenomenes meteorologiques extremes plus frequents et plus marques). Leurs repercussions sur les systemes d’assainissement ont ete examinees : certaines seront positives (reactions biologiques accelerees), d’autres negatives (consommations energetiques supplementaires). Le reseau d’assainissement sera plus affecte que les stations d’epuration, en particulier au niveau de la gestion des temps de pluie. Les problemes lies aux odeurs et a une acceleration des phenomenes de corrosion se poseront egalement avec acuite. Enfin, les politiques de gestion des crises (preservation du patrimoine et des equipements, securite, prevention des risques sanitaires) devront etre mises en place localement pour faire face a des accidents meteorologiques plus aigus et plus frequents.

Numerical schemes for systems of transport equations are commonly constrained by a stability condition of Courant-Friedrichs-Lewy (CFL) type. We consider a system modeling the steady transport of photons and electrons in the field of radiotherapy. Naive discretizations of such a system are commonly constrained by a very restrictive CFL condition. This issue is circumvented by constructing an implicit scheme based on a relaxation approach.We use an entropy-based moment model, namely the M1 model. Such a system of equations possesses the non-linear flux terms of a hyperbolic system but no time derivative. The flux terms are well-defined only under a condition on the unknowns, called realizability, which corresponds to the positivity of an underlying kinetic distribution function.The present numerical approach is applicable to non-linear systems which possess no hyperbolic operator, and it preserves the realizability property. However, the discrete equations are non-linear, and we propose a numerical method to solve such non-linear systems.Our approach is tested on academic and practical cases in 1D, 2D, and 3D and it is shown to require significantly less computational power than reference methods.