The buffered chemostat with non-monotonic response functions

We study how a particular spatial structure with a buffer impacts the number of equilibria and their stability in the chemostat model. We show that the occurrence of a buffer can allow a species to persist or on the opposite to go extinct, depending on the characteristics of the buffer. For non-monotonic response functions, we characterize the buffered configurations that make the chemostat dynamics globally asymptotically stable, while this is not possible with single, serial or parallel vessels of the same total volume and input flow. These results are illustrated with the Haldane kinetic function.Comment: 9th IFAC Symposium on Nonlinear Control Systems (NOLCOS 2013), Toulouse : France (2013

Mathematical modeling of an urban pigeon population subject to local management strategies

International audienceThis paper addresses the issue of managing urban pigeon population using some possible actions that makes it reach a density target with respect to socio-ecological constraints. A mathematical model describing the dynamic of this population is introduced. This model incorporates the effect of some regulatory actions on the dynamic of this population. We then used mathematical viability theory, which provides a framework to study compatibility between dynamics and state constraints. The viability study shows when and how it is possible to regulate the pigeon population with respect to the constraints

Input-output decoupling and linearization of nonlinear two-input two-output time-varying delay systems

International audienceIn this paper, we study the input-output decoupling and linearization of nonlinear two-input two-output time-varying delay systems. When working with delay systems, two problems may arise when constructing a feedback transformation for which the input-output map of the feedback modified systems is linear. The first issue is the boundedness of the control and the second one is its causality. We develop an algorithm allowing the construction of a causal and bounded feedback which permits to solve the input-output decoupling and linearization problem. The idea of our algorithm is to introduce, at each step, when the input-output decoupling is not possible, an artificial delay for the input that appears " too early " in the system. To that end, we propose, at each step, a precise procedure for defining a simple feedback transformation

Procédé et système de traitement biologique pour bioprocédés continus susceptibles de présenter une inhibition

brevet paru le 9/08/2013 (Bulletin Officiel de la Propriété Industrielle n° 32) hal-01095712The method comprises, given a value of a volume of reference (V) of a reactor supplied with a constant flow (Q), dividing the volume into a first digester of a first volume (V1) and a second digester of a second volume (V2) such that a sum of the first volume and the second volume is equal to that the volume of reference, inoculating the second digester by a microbial ecosystem to convert a part of a substrate and to present an inhibition of growth by the substrate in an initialization phase, dividing the flow into a first flow and a second flow such that the first flow supplies exclusively the first digester, and the second flow supplies initially second digester before being redistributed in the first digester. The method further comprises predetermining a target value of concentration in the substrate, in which the first volume (V1=rV) is a percentage volume of reference with r as a parameter, the second volume (V2=(1-r)V) is percentage complementary to the volume of reference, the second flow (Q2=alpha Q) is a percentage of the rate of constant flow with alpha as a parameter, and the first flow (Q1= (1-alpha )Q) is complementary percentage to the rate of constant flow; determining a dilution ratio of the second volume of the second digester and the dilution rate to be less than the value of the curve growth of the data on the microbial ecosystem for the given substrate; deducing a concentration value in the substrate corresponding to that of the dilution ratio from the growth curve; determining a set of values according to the value of the dilution rate and the value of the dilution ratio; choosing a subset of values from the determined set of values; determining a function representative of a speed or specific contribution in the substrate in the first digester at a given concentration based on a value of the parameter; selecting a value from the chosen values such that a variation curve of the function meets a graph of the function at more than one point; selecting a value from the chosen values such that the variation curve of the function does not meet a graph of the function at more than one point as the single point corresponds to a value of concentration in the weakest possible substrate; comparing the output concentration with the target value; and modifying the value of the parameter and/or the dilution ratio according to the result of the comparison. The volume of reference is equal to the rate of constant flow divided by a dilution rate, where the dilution rate is equal to a value of curve growth on microbial ecosystem data for the given substrate at a predetermined target value. An independent claim is included for an effluent treatment system.L'invention concerne un bioprocédé continu de traitement d'un effluent à débit d'alimentation (Q) constant et comprenant un substrat à une concentration d'entrée (Sin) et de sortie (S**) ; comprenant des étapes consistant à : - déterminer un volume de référence (V) d'un réacteur alimenté par le débit (Q), - scinder le volume (V) en un premier digesteur de premier volume (V1) et un deuxième digesteur de deuxième volume (V2), tels que le premier volume (V1) plus deuxième volume (V2) égalent ledit volume (V), - ensemencer préalablement au moins le deuxième digesteur par un écosystème microbien susceptible de convertir ledit substrat et de présenter une inhibition de croissance ; - distribuer ledit débit (Q) en : o un premier débit (Q1) alimentant exclusivement le premier digesteur et un deuxième débit (Q2) alimentant d'abord le deuxième digesteur avant le premier digesteur

Stability criteria for singularly perturbed linear switching systems

International audienceWe present some results on the uniform exponential stability of singularly perturbed linear systems undergoing switching. In absence of dwell-time constraints, the switching parameter can evolve on the same time scale as the fast variables, or even faster. We investigate the effect of switching laws evolving at a time scale comparable with the fast variables, describing the corresponding asymptotic effect on the slow variable. Based on this analysis, we propose stability criteria for the overall system, uniform for small values of the parameter of singular perturbation

Further remarks on input-output linearization of SISO time-varying delay systems

International audienceIn this paper, the problem of input-output linearization of nonlinear single-input single-output time-varying delay systems (with delays in the input and the output) is discussed and illustrated via several examples. Sufficient conditions have been recently developed by the authors. Here, we propose to discuss these conditions and give some insight allowing to improve them

Mini percutaneous nephrolithotomy treat the large upper ureteric stone

Background. The incidence of kidney stones has been raised all over the world. Nephrolithiasis is the most common cause of illnesses in western countries and has been rising in its incidence in developing countries. PCNL describe the management of large renal calculi when measuring >20 mm and even for smaller ones of lower pole with excellent stone-free rate reach to 98%. Aim. To evaluate the mini-percutaneous nephrolithotomy (mini-PCNL) safety used to cure upper ureteral and renal stones with assessing the complication and procedure outcome in Iraqi patients. Method. This is a prospective study done between October 2022 and September 2023 in Ghazi Al-Hariri for Surgical Specialties Hospital, Medical city, with 100 patients enrolled who underwent mini-PCNL. All patients had upper ureteral and renal stones (size ≥20 mm). The nephroscope tube was utilized. The stones were destroyed by pneumatic lithotripter. Complications and outcomes were determined immediately postoperative via X-ray of the ureters, kidneys and bladder. Ultra-sonography also used to determine safety and efficacy of procedure. Results. The cases mean age was 55.8 ± 12.3 years, and their BMI was 29.5 ± 5.9 kg/m2. The size of mean stone was 22.5 ± 17.9 mm. The stone-free rate (SFR) was 94.7%. The post-operative hospital stay mean was 3.6 ± 2.7 days. The Hb drop mean was 0.6 ± 0.3 g/dL. There were none of our cases had organ trauma or any complications. Thirty cases required additional subsequent extra-corporeal shock wave lithotripsy. Conclusion. The mini-PCNL is effective and safe in cases of upper ureteral and renal stones ≥20 mm. Researches with a larger multi-center cohorts may be needed to validate these techniques

Antimicrobial resistance among migrants in Europe: a systematic review and meta-analysis

BACKGROUND: Rates of antimicrobial resistance (AMR) are rising globally and there is concern that increased migration is contributing to the burden of antibiotic resistance in Europe. However, the effect of migration on the burden of AMR in Europe has not yet been comprehensively examined. Therefore, we did a systematic review and meta-analysis to identify and synthesise data for AMR carriage or infection in migrants to Europe to examine differences in patterns of AMR across migrant groups and in different settings. METHODS: For this systematic review and meta-analysis, we searched MEDLINE, Embase, PubMed, and Scopus with no language restrictions from Jan 1, 2000, to Jan 18, 2017, for primary data from observational studies reporting antibacterial resistance in common bacterial pathogens among migrants to 21 European Union-15 and European Economic Area countries. To be eligible for inclusion, studies had to report data on carriage or infection with laboratory-confirmed antibiotic-resistant organisms in migrant populations. We extracted data from eligible studies and assessed quality using piloted, standardised forms. We did not examine drug resistance in tuberculosis and excluded articles solely reporting on this parameter. We also excluded articles in which migrant status was determined by ethnicity, country of birth of participants' parents, or was not defined, and articles in which data were not disaggregated by migrant status. Outcomes were carriage of or infection with antibiotic-resistant organisms. We used random-effects models to calculate the pooled prevalence of each outcome. The study protocol is registered with PROSPERO, number CRD42016043681. FINDINGS: We identified 2274 articles, of which 23 observational studies reporting on antibiotic resistance in 2319 migrants were included. The pooled prevalence of any AMR carriage or AMR infection in migrants was 25·4% (95% CI 19·1-31·8; I2 =98%), including meticillin-resistant Staphylococcus aureus (7·8%, 4·8-10·7; I2 =92%) and antibiotic-resistant Gram-negative bacteria (27·2%, 17·6-36·8; I2 =94%). The pooled prevalence of any AMR carriage or infection was higher in refugees and asylum seekers (33·0%, 18·3-47·6; I2 =98%) than in other migrant groups (6·6%, 1·8-11·3; I2 =92%). The pooled prevalence of antibiotic-resistant organisms was slightly higher in high-migrant community settings (33·1%, 11·1-55·1; I2 =96%) than in migrants in hospitals (24·3%, 16·1-32·6; I2 =98%). We did not find evidence of high rates of transmission of AMR from migrant to host populations. INTERPRETATION: Migrants are exposed to conditions favouring the emergence of drug resistance during transit and in host countries in Europe. Increased antibiotic resistance among refugees and asylum seekers and in high-migrant community settings (such as refugee camps and detention facilities) highlights the need for improved living conditions, access to health care, and initiatives to facilitate detection of and appropriate high-quality treatment for antibiotic-resistant infections during transit and in host countries. Protocols for the prevention and control of infection and for antibiotic surveillance need to be integrated in all aspects of health care, which should be accessible for all migrant groups, and should target determinants of AMR before, during, and after migration. FUNDING: UK National Institute for Health Research Imperial Biomedical Research Centre, Imperial College Healthcare Charity, the Wellcome Trust, and UK National Institute for Health Research Health Protection Research Unit in Healthcare-associated Infections and Antimictobial Resistance at Imperial College London