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MULTISCALE HOMOGENIZATION OF NONLINEAR HYPERBOLIC EQUATIONS WITH SEVERAL TIME SCALES

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Acta Mathematica Scientia 2011年第3期31卷 843-856页

作者： jean louis Woukeng David Dongo Department of Mathematics and Computer Science Faculty of Science University of Dschang

We study the multiscale homogenization of a nonlinear hyperbolic equation in a periodic *** obtain an accurate homogenization *** also show that as the nonlinear term depends on the microscopic time variable,the global homogenized problem thus obtained is a system consisting of two hyperbolic *** is also shown that in spite of the presence of several time scales,the global homogenized problem is not a reiterated one.

关键词： hyperbolic multiscale nonlinear

Soluble CD40 ligand in prediction of acute severe pancreatitis

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World Journal of Gastroenterology 2006年第10期12卷 1613-1616页

作者： jean louis Frossard Philippe morel Brenda Kwak Catherine Pastor Thierry Berney Léo Buhler Alain Von Laufen Sandrine Demulder Francois Mach Division of Gastroenterology Geneva University HospitalGenève Switzerland Clinic of Digestive Surgery Geneva University Hospital Genève Switzerland Division of Cardiology Geneva University Hospital Genève Switzerland

AIM： TO assess the early predictability of the soluble CD40L （sCD40L） in pancreatitis severity. METHODS： Between February 2000 and February 2003, 279 consecutive patients with acute pancreatitis were prospectively enrolled in our study. In this report, 40 patients with mild and 40 patients with severe pancreatitis were randomly studied, sCD40L concentrations were measured 48 hours after admission. RESULTS： sCD40L levels were significantly higher 48 hours after admission in severe pancreatitis than in mild pancreatitis. Using a cutoff of 1000 pg/L, the sensitivity and specificity of sCD40L to detect a severe course of the disease were 78% and 62% respectively compared to 72% and 81% for CRP. Logistic regression analysis found that CRP was the only statistically significant marker able to detect a severe course of the disease. CONCLUSION： These findings indicate that CRP remains a valuable marker to determine the severity and prognosis of acute pancreatitis whereas sCD40L levels should be assessed in further studies.

关键词： Acute pancreatitis Prognostic factor sCD40

Multiscale Analysis of Semilinear Damped Stochastic Wave Equations

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Acta Mathematica Sinica,English Series 2023年第7期39卷 1305-1331页

作者： Aurelien FOUETIO Gabriel NGUETSENG jean louis WOUKENG Department of Mathematics Higher Teacher Training CollegeUniversity of NgaoundereP.O.Box 652BertouaCameroon Department of Mathematics University of Yaounde IP.O.Box 812YaoundeCameroon Department of Mathematics and Computer Science University of DschangP.O.Box 67DschangCameroon

In this paper we proceed with the multiscale analysis of semilinear damped stochastic wave motions. The analysis is made by combining the well-known sigma convergence method with its stochastic counterpart, associated to some compactness results such as the Prokhorov and Skorokhod theorems. We derive the equivalent model, which is of the same type as the micro-model. One of the novelties of the work is that the corrector problem is solved in the classical sense of distributions,thereby allowing numerical computations of the homogenized coefficients.

关键词： Hyperbolic stochastic equations Wiener Process sigma convergence tightness of probability measures

The Séchilienne (France) Landslide:a Non-typical Progressive Failure Implying Major Risks

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Journal of Mountain Science 2011年第2期8卷 117-123页

作者： jean-louis DURVILLE Christophe BONNARD Pierre POTHERAT Conseil général de l'environnement et du développement durable Paris France Independent expert PBBG SA Lausanne Switzerland Centred'études techniques de l'équipement Lyon France

The National Road RN 91 has been threatened for about twenty-five years by a huge landslide, located 25 km south-east to the town of Grenoble (France). If several million cubic meters of rock fall down, the debris will dam the valley. Then the failure of the dam by overtopping and rapid erosion might result in a catastrophic flood and dramatic consequences for human life, environment and economy throughout the valley. The paper presents the hazard assessment based on geological and hydrological surveys, including small scale hydraulic tests, as well as the risk evaluation that has been performed. The risk management relies first upon a high level monitoring and an emergency plan; various mitigation strategies have been considered.

关键词： Landslide Progressive failure Séchilienne France

H2/CO/air premixed and partially premixed flame structure at different pressures based on reaction limit analysis

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Science Bulletin 2018年第19期63卷 1260-1266页

作者： Zaigang Liu Wenjun Kong jean-louis Consalvi Wenhu Han Key Laboratory of Light-Duty Gas-Turbine Institute of Engineering Thermophysics Chinese Academy of Sciences Beijing 100190 China School of Engineering Sciences. University of Chinese Academy of Sciences Beijing 100049 China IUSTI UMR 7343 Aix-Marseille Universite CNRS Marseille 13453 France

Premixed and partially premixed flames (PPFs) of H2/CO/air syngas are studied numerically to investigate the effect of pressure on syngas PPF structure. Chemical characteristics of the syngas flame at different pressures are investigated based on reaction limit analysis using a one-dimensional configuration. The results show that CO affects the syngas reaction limits through both physical effects that consist mainly in dilution and chemical effects that are related to both R23 (CO+OH=CO2+H) and HCO pathway. In particular, the HCO pathway weakens the flame at low pressures due to the chain-terminating effect of R25 (HCO+O2=CO+HO2) and R26 (HCO+H=CO+H2), and enhances the flame at high pressures because of the contribution of R25 to the HO2chain-branching process. These CO chemical characteristics are also observed in the premixed zone of 50%H2+50%CO syngas PPFs whereas only R23 is important in the non-premixed zone.

关键词： Syngas Partially premixed flame Pressure effect Reaction limit Flame structure

Totally laparoscopic trans-hiatal gastroesophagectomy for benign diseases of the esophago-gastric junction

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World Journal of Gastroenterology 2007年第2期13卷 285-288页

作者： jean-louis Dulucq Pascal Wintringer Ahmad Mahajna Department of Abdominal Surgery Institute of Laparoscopic Surgery Maison de Santé Protestante Bagatelle Hospital Route de Toulouse 203 Talence-Bordeaux 33401 France

AIM： To prospectively present our initial experience with totally laparoscopic transhiatal esophagogastrectomies for benign diseases of the cardia and distal esophagus. METHODS： Laparoscopic gastric mobilization and tubularization combined with transhiatal esophageal dissection and intrathoradc esophagogastric anastomosis accomplished by a circular stapler was done in 3 patients. There were 2 females and 1 male patient with a mean age of 73 ± 5 years. RESULTS： Two patients were operated on due to benign stromal tumor of the cardia and one patient had severe oesophageal peptic stenosis. Mean blood loss was 47 ± 15 mL and mean operating time was 130 ± 10 rain. There were no cases that required conversion to laparotomy. All patients were extubated immediately after surgery. Soft diet intake and ambulation times were 5.1 ± 0.4 d and 2.6 ±0.6 d, respectively. There were no intraoperative and postoperative complications and there were no perioperative deaths. The average length of hospital stay was 9.3 ± 3 d. All procedures were curative and all resected margins were tumor free. The mean number of retrieved lymph nodes was 18 ±8. CONCLUSION： Laparoscopic transhiatal esophagogastrectomy for benign lesions has good effects and proves feasible and safe.

关键词： Esophagogastrectomy Transhiatal resection Cardial tumor Laparoscopy Stromal tumor

Experimental evidence of obesity as a risk factor for severe acute pancreatitis

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World Journal of Gastroenterology 2009年第42期15卷 5260-5265页

作者： jean-louis Frossard Pierre Lescuyer Catherine M Pastor Service of Gastroenterology Geneva University HospitalsGeneva 1205Switzerland Laboratory of pathophysiology and molecular imaging Geneva University HospitalsGeneva 1205Switzerland Service of Genetics and Central Laboratory Geneva University HospitalsGeneva 1205Switzerland

The incidence of acute pancreatitis, an inflammation of the pancreas, is increasing worldwide. Pancreatic injury is mild in 80%-90% of patients who recover without complications. The remaining patients may develop a severe disease with local complications such as acinar cell necrosis, abscess and remote organ injury including lung injury. The early prediction of the severity of the disease is an important goal for physicians in management of patients with acute pancreatitis in order to optimize the therapy and to prevent organ dysfunction and local complications. For that purpose, multiple clinical scale scores have been applied to patients with acute pancreatitis. Recently, a new problem has emerged： the increased severity of the disease in obese patients. However, the mechanisms by which obesity increases the severity of acute pancreatitis are unclear. Several hypotheses have been suggested：（1） obese patients have an increased inflammation within the pancreas; （2） obese patients have an increased accumulation of fat within and around the pancreas where necrosis is often located; （3） increase in both peri- and intra-pancreatic fat and inflammatory cells explain the high incidence of pancreatic inflammation and necrosis in obese patients; （4） hepatic dysfunction associated with obesity might enhance the systemic inflammatory response by altering the detoxiflcation of inflammatory mediators; and （5） ventilation/perfusion mismatch leading to hypoxia associated with a low pancreatic flow might reduce the pancreatic oxygenation and further enhance pancreatic injury. Recent experimental investigations also show an increased mortality and morbidity in obese rodents with acute pancreatitis and the implication of the adipokines leptin and adiponectin. Such models are important to investigate whether the inflammatory response of the disease is enhanced by obesity. It is exciting to speculate that manipulation of the adipokine milieu has the potential to influence the severi

关键词： Acute pancreatitis Obesity Adiponectin Leptin

Clopidogrel and proton pump inhibitors-where do we stand in 2012?

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World Journal of Gastroenterology 2012年第18期18卷 2161-2171页

作者： Michael D Drepper Laurent Spahr jean louis Frossard Division of Gastroenterology Department of Internal MedicineGeneva University Hospital14 Geneva CH-1211Switzerland

Clopidogrel in association with aspirine is considered state of the art of medical treatment for acute coronary syndrome by reducing the risk of new ischemic *** treatment with proton pump inhibitors in order to prevent gastrointestinal side effects is recommended by clinical *** needs metabolic activation predominantly by the hepatic cytochrome P450 isoenzyme Cytochrome 2C19(CYP2C19) and proton pump inhibitors(PPIs) are extensively metabolized by the CYP2C19 isoenzyme as *** pharmacodynamic studies investigating a potential clopidogrel-PPI interaction found a significant decrease of the clopidogrel platelet antiaggregation effect for omeprazole,but not for *** clinical cohort studies in 2009 reported an increased risk for adverse cardiovascular events,when under clopidogrel and PPI treatment at the same *** observations led the United States Food and Drug Administration and the European Medecines Agency to discourage the combination of clopidogrel and PPI(especially omeprazole) in the same *** contrast,more recent retrospective cohort studies including propensity score matching and the only existing randomized trial have not shown any difference concerning adverse cardiovascular events when concomitantly on clopidogrel and PPI or only on *** meta-analyses report an inverse correlation between clopidogrel-PPI interaction and study quality,with high and moderate quality studies not reporting any association,rising concern about unmeasured confounders biasing the low quality ***,no definite evidence exists for an effect on *** PPI induced risk reduction clearly overweighs the possible adverse cardiovascular risk in patients with high risk of gastrointestinal bleeding,combination of clopidogrel with the less CYP2C19 inhibiting pantoprazole should be recommended.

关键词： Clopidogrel Thienopyridine Proton pump inhibitors Drug interaction Platelet reactivity Antiplatelet therapy Cytochromes Acute coronary syndrome Gastrointestinal bleeding

High prevalence of cholestasis, with increased conjugated bile acids in inflammatory bowel diseases patients

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World Journal of Clinical Cases 2018年第4期6卷 44-53页

作者： Marc Girardin Antoine Hadengue jean-louis Frossard Service of Gastroenterology and Hepatology Geneva University Hospital

AIM To investigate the prevalence and causes of cholestasis in patients with inflammatory bowel diseases in the Swiss Inflammatory Bowel Diseases Cohort. METHODS A retrospective cohort study was performed of all the patients in the Swiss Inflammatory bowel disease Cohort. Total bile acid was measured for all patients and cholestasis was defined as a concentration > 8 μmol/L. The characteristics of patients with or without cholestasis were compared. Bile acid profiles were then determined for 80 patients with high total bile acid and 80 matched patients with low total bile acid. Bile acid profiles were compared for smokers vs nonsmokers, ileal vs colonic disease, and inflammatory vs non inflammatory *** Ninety-six patients had more than 8 μmol/L total bile acid, giving a prevalence of 7.15%. Patients with an obvious cause of cholestasis, such as primary sclerosing cholangitis, were then excluded, leaving 1190 participants with total bile acid 8 μmol/L. In multivariate analysis, calcium supplementation was significantly associated with cholestasis(odds ratio, 2.36, 95%CI: 1.00-5.21, P = 0.040) whereas current smoking significantly reduced the risk of cholestasis(odds ratio, 0.42, 95%CI: 0.17-0.91, P = 0.041). Levels of all conjugated bile acids were higher in the cholestasis group than in the control group. When we compared patients with ileal vs colonic disease, the former had higher levels of primary, secondary, and tertiary bile acids whereas patients with colonic disease had higher levels of conjugated bile *** Prevalence of cholestasis is high. Smoking appears to reduce cholestasis. Conjugated bile acids are higher in cholestasis and in colonic disease whereas unconjugated in ileal disease.

关键词： Lipid Liver Crohn’s disease Ulcerative colitis Cholestasis