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Wave Equation Simulation Using a Compressed Modeler

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American Journal of Computational Mathematics 2013年第3期3卷 231-241页

作者： Victor pereyra Energy Resources Engineering Stanford University Stanford USA

Repeated simulations of large scale wave propagation problems are prevalent in many fields. In oil exploration earth imaging problems, the use of full wave simulations is becoming routine and it is only hampered by the extreme computational resources required. In this contribution, we explore the feasibility of employing reduced-order modeling techniques in an attempt to significantly decrease the cost of these calculations. We consider the acoustic wave equation in two-dimensions for simplicity, but the extension to three-dimensions and to elastic or even anysotropic problems is clear. We use the proper orthogonal decomposition approach to model order reduction and describe two algorithms: the traditional one using the SVD of the matrix of snapshots and a more economical and flexible one using a progressive QR decomposition. We include also two a posteriori error estimation procedures and extensive testing and validation is presented that indicates the promise of the approach.

关键词： Wave Equation POD Model Order Reduction Earth Imaging

Anemia and iron deficiency in gastrointestinal and liver conditions

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World Journal of Gastroenterology 2016年第35期22卷 7908-7925页

作者： Jürgen Stein Susan Connor Garth Virgin David Eng Hui Ong Lisandro pereyra Interdisciplinary Crohn Colitis Centre Rhein-Main Frankfurt am Main Department of Gastroenterology and Clinical Nutrition DGD Clinics Sachsenhausen Frankfurt am Main60594 Frankfurt Germany Department of Gastroenterology and Hepatology Liverpool Hospital South Western Clinical School University of New South Wales Vifor Pharma Flughofstrasse 61 CH-8152 Zurich Switzerland Division of Gastroenterology and Hepatology University Medicine Cluster National University Hospital Servicio de Gastroenterología y Endoscopia Hospital Alemán

Iron deficiency anemia(IDA) is associated with a number of pathological gastrointestinal conditions other than inflammatory bowel disease, and also with liver disorders. Different factors such as chronic bleeding, malabsorption and inflammation may contribute to IDA. Although patients with symptoms of anemia are frequently referred to gastroenterologists, the approach to diagnosis and selection of treatment as well as follow-up measures is not standardized and suboptimal. Iron deficiency, even without anemia, can substantially impact physical and cognitive function and reduce quality of life. Therefore, regular iron status assessment and awareness of the clinical consequences of impaired iron status are critical. While the range of options for treatment of IDA is increasing due to the availability of effective and well-tolerated parenteral iron preparations, a comprehensive overview of IDA and its therapy in patients with gastrointestinal conditions is currently lacking. Furthermore, definitions and assessment of iron status lack harmonization and there is a paucity of expert guidelines on this topic. This review summarizes current thinking concerning IDA as a common co-morbidity in specific gastrointestinal and liver disorders, and thus encourages a more unified treatment approach to anemia and iron deficiency, while offering gastroenterologists guidance on treatment options for IDA in everyday clinical practice.

关键词： Iron deficiency anemia Gastrointestinal bleeding Nonsteroidal anti-inflammatory drugs Gastritis Infection Bariatric surgery Celiac disease Gastrointestinal neoplasm Chronic hepatitis Nonalcoholic fatty liver disease

Imaging Applications with Variable Projections

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American Journal of Computational Mathematics 2019年第4期9卷 261-281页

作者： Victor pereyra Godela Scherer Smart Fields Stanford University Stanford CA USA Department of Mathematics University of Reading Reading GB

We review two important fields of application for the method of Variable Projections (VARPRO): Seismic Prospecting and Medical Imaging. We cover the period since 2002 when a first review was published. Variable Projections is a method for the solution of nonlinear least squares problems where the model is a linear combination of nonlinear functions. Its success is based on the fact that the reduced functional, where the linear parameters are eliminated converges always faster than if the same method of solution is applied to the original problem. More importantly, many of these problems are very hard to solve in their original format and VARPRO has shown its value in many different applications.

关键词： Medical Imaging Geophysics Variable Projections Nonlinear Least Squares

Epidemiology and risk factors for mortality in critically ill patients with pancreatic infection

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Journal of Intensive Medicine 2024年第1期4卷 81-93页

作者： Marie Dejonckheere Massimo Antonelli Kostoula Arvaniti Koen Blot Ben CreaghBrown Dylan Wde Lange Jan De Waele Mieke Deschepper Yalim Dikmen George Dimopoulos Christian Eckmann Guy Francois Massimo Girardis Despoina Koulenti Sonia Labeau Jeffrey Lipman Fernando Lipovestky Emilio Maseda Philippe Montravers Adam Mikstacki JoseArtur Paiva Cecilia pereyra Jordi Rello JeanFrancois Timsit Dirk Vogelaers Stijn Blot the Abdominal Sepsis Study(AbSeS)group on behalf of the Trials Group of the European Society of Intensive Care Medicine Department of Internal Medicine and Pediatrics Faculty of Medicine and Health SciencesGhent UniversityGhentBelgium Department of Anesthesiology Intensive Care and Emergency MedicineFondazione Policlinico Universitario A.Gemelli IRCCSRomeItaly UniversitàCattolica del Sacro Cuore RomeItaly Intensive Care Unit Papageorgiou University Affiliated HospitalThessaloníkiGreece Department of Epidemiology and Public Health SciensanoIxellesBelgium Surrey Perioperative Anaesthetic Critical Care Collaborative Research Group(SPACeR) Royal Surrey County HospitalGuildfordUK Department of Clinical and Experimental Medicine University of SurreyGuildfordUK Department of Intensive Care Medicine University Medical Center UtrechtUniversity UtrechtUtrechtthe Netherlands Department of Intensive Care Medicine Ghent University HospitalGhentBelgium Data Science Institute Ghent University HospitalGhentBelgium Department of Anesthesiology and Reanimation Cerrahpasa School of MedicineIstanbul University-CerrahpasaIstanbulTurkey rd Department of Critical Care “EVGENIDIO”HospitalNational and Kapodistrian University of AthensAthensGreece Department of General Visceral and Thoracic SurgeryKlinikum Hannoversch-MuendenGoettingen UniversityGöttingenGermany Division of Scientific Affairs-Research European Society of Intensive Care MedicineBrusselsBelgium Anesthesia and Intensive Care Department University Hospital of ModenaModenaItaly UQ Centre for Clinical Research Faculty of MedicineThe University of QueenslandBrisbaneQLDAustralia nd Critical Care Department Attikon University HospitalAthensGreece Department of Nursing Faculty of EducationHealth and Social WorkUniversity College GhentGhentBelgium Jamieson Trauma Institute The University of QueenslandBrisbaneQLDAustralia Nimes University Hospital University of MontpellierNimesFrance Critical Care Department Hospital of the Interamerican Open University(UAI)Buenos AiresArgentina Surgical Critical Care Department of AnesthesiaHospital Universitario

Background:The AbSeS-classification defines specific phenotypes of patients with intra-abdominal infection based on the(1)setting of infection onset(community-acquired,early onset,or late-onset hospital-acquired),(2)presence or absence of either localized or diffuse peritonitis,and(3)severity of disease expression(infection,sepsis,or septic shock).This classification system demonstrated reliable risk stratification in intensive care unit(ICU)patients with intra-abdominal *** study aimed to describe the epidemiology of ICU patients with pancreatic infection and assess the relationship between the components of the AbSeS-classification and ***:This was a secondary analysis of an international observational study(“AbSeS”)investigating ICU patients with intra-abdominal *** patients with pancreatic infection were included in this analysis(n=165).Mortality was defined as ICU mortality within 28 days of observation for patients discharged earlier from the *** with mortality were assessed using logistic regression analysis and reported as odds ratio(OR)and 95%confidence interval(CI).Results:The overall mortality was 35.2%(n=58).The independent risk factors for mortality included older age(OR=1.03,95%CI:1.0 to 1.1 P=0.023),localized peritonitis(OR=4.4,95%CI:1.4 to 13.9 P=0.011),and persistent signs of inflammation at day 7(OR=9.5,95%CI:3.8 to 23.9,P<0.001)or after the implementation of additional source control interventions within the first week(OR=4.0,95%CI:1.3 to 12.2,P=0.013).Gramnegative bacteria were most frequently isolated(n=58,49.2%)without clinically relevant differences in microbial etiology between survivors and ***:In pancreatic infection,a challenging source/damage control and ongoing pancreatic inflammation appear to be the strongest contributors to an unfavorable short-term *** this limited series,essentials of the AbSeS-classification,such as the setting of infection onset,diffuse

关键词： Pancreatic infection Intensive care unit Mortality Intra-abdominal infection Sepsis

Does Coronary Microvascular Spasm Exist?Objective Evidence from Intracoronary Doppler Flow Measurements During Acetylcholine Testing

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Cardiovascular Innovations and Applications 2020年第1期4卷 205-209页

作者： Fabian Guenther Andreas Seitz Valeria Martinez pereyra Raffi Bekeredjian Udo Sechtem Peter Ong Department of Cardiology Robert-Bosch-KrankenhausAuerbachstr.11070376 StuttgartGermany

A 43-year-old woman with recurrent atypical angina underwent invasive coronary angiography including intracoronary Doppler blood flow assessment and coronary spasm provocation *** obstructive epicardial disease could be ruled-out angiographically,the patient experienced reproduction of her angina symptoms after intracoronary administration of acetylcholine(100μg)during spasm provocation ***,the ECG showed new-onset ST-segment depression in the absence of epicardial *** addition,coronary fl ow velocity was signifi cantly reduced after acetylcholine compared to the baseline *** intracoronary administration of nitroglycerine(200μg),the patient’s symptoms as well as the ECG changes and coronary flow reduction were *** the ongoing challenges in appropriate evaluation of the pathophysiological mechanisms of coronary microvascular dysfunction,simultaneous intracoronary Doppler flow measurement during spasm testing–as shown in this case–may provide objective evidence for microvascular spasm in addition to the standardized diagnostic criteria,especially if they are ambiguous.

关键词： acetylcholine coronary microcirculation coronary flow reserve coronary spasm

Colonic preparation before colonoscopy in constipated and non-constipated patients:A randomized study

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World Journal of Gastroenterology 2013年第31期19卷 5103-5110页

作者： Lisandro pereyra Daniel Cimmino carlos González Malla Mariano Laporte Nicolás Rotholtz carlos Peczan Sandra Lencinas Silvia Pedreira Hugo Catalano Luis Boerr Department of Endoscopy Hospital Alemán 1118 Buenos Aires Argentina Department of Internal Medicine Hospital Alemán 1118 Buenos Aires Argentina Department of Surgery Hospital Alemán 1118 Buenos Aires Argentina

AIM: To compare the efficacy of different doses of sodium phosphate(NaP) and polyethylenglicol(PEG) alone or with bisacodyl for colonic cleansing in constipated and non-constipated ***: Three hundred and forty-nine patients,older than 18 years old,with low risk for renal damage and who were scheduled for outpatient colonoscopy were randomized to receive one of the following preparations(prep): 90 mL of NaP(prep 1);45 mL of NaP + 20 mg of bisacodyl(prep 2);4 L of PEG(prep 3) or 2 L of PEG + 20 mg of bisacodyl(prep 4).Randomization was stratified by ***,endoscopists,endoscopists' assistants and data analysts were blinded.A blinding challenge was performed to endoscopist in order to reassure *** primary outcome was the efficacy of colonic cleansing using a previous reported *** outcomes were tolerability,compliance,side effects,endoscopist perception about the necessity to repeat the study due to an inadequate colonic preparation and patient overall ***: Information about the primary outcome was obtained from 324 patients(93%).There were no significant differences regarding the preparation quality among different groups in the overall *** was higher in the NaP preparations being even higher in half-dose with bisacodyl: 94%(prep 1),100%(prep 2),81%(prep 3) and 87%(prep 4)(2 vs 1,3 and 4,P < 0.01;1 vs 3,4,P < 0.05).The combination of bisacodyl with NaP was associated with insomnia(P = 0.04).In non-constipated patients the preparation quality was also similar between different groups,but endoscopist appraisal about the need to repeat the study was more frequent in the half-dose PEG plus bisacodyl than in whole dose NaP preparation: 11%(prep 4) vs 2%(prep 1)(P < 0.05).Compliance in this group was also higher with the NaP preparations: 95%(prep 1),100%(prep2) vs 80%(prep 3)(P < 0.05).Bisacodyl was associated with abdominal pain: 13%(prep 1),31%(prep 2),21%(prep 3) and 29%(prep 4),(2,4 vs 1,2

关键词： Colonic cleansing Sodium phosphate Polyethylenglicol Bisacodyl constipation Colonoscopy

Zinc bioleaching from an iron concentrate using Acidithiobacillus ferrooxidans strain from Hercules Mine of Coahuila,Mexico

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International Journal of Minerals,Metallurgy and Materials 2011年第5期18卷 523-526页

作者： Diola Marina Nunez-Ramirez Aquiles Solis-Soto JavierLopez-Miranda Javier Lopez-Miranda Benito pereyra-Alfere Mirtam Rutlaga-Qumones Luis Medina- Torres Hiram Medrano-Roldan Food and Biotechnology Postgraduate Unit Institute of Technology of Durango Durango 34080 Mexico Institute of Biotechnology Autonomous University ofNuevo Le6n Monterrey N.L. 66451 Mexico Department of Chemical Engineering Faculty of Chemistry Autonomous National University of Mexico Mexico City 04510 Mexico

The iron concentrate from Hercules Mine of Coahuila,Mexico,which mainly contained pyrite and pyrrhotite,was treated by the bioleaching process using native strain Acidithiobacillus ferrooxidans （***） to determine the ability of these bacteria on the leaching of *** native bacteria were isolated from the iron concentrate of the *** bioleaching experiments were carried out in shake flasks to analyze the effects of pH values,pulp density,and the ferrous sulfate concentration on the bioleaching *** results obtained by microbial kinetic analyses for the evaluation of some aspects of zinc leaching show that the native bacteria ***,which is enriched with a 9K Silverman medium under the optimum conditions of pH 2.0,20 g/L pulp density,and 40 g/L FeSO4,increases the zinc extraction considerably observed by monitoring during15 d,i.e.,the zinc concentration has a decrease of about 95% in the iron concentrate.

关键词： pyrite pyrrhotite bioleaching zinc

Chemical analysis and antioxidant content of various propolis samples collected from different regions and their impact on antimicrobial activities

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Asian Pacific Journal of Tropical Medicine 2018年第7期11卷 436-442页

作者： Soumaya Touzani Noori Al-Waili Nawal El Menyiy Bratko Filipic Adriana pereyra Ilham EL Arabi Wail Al-Waili Badiaa Lyoussi Laboratory of Physiology Pharmacology & Environmental Health Faculty of Science University Sidi Mohamed Ben Abdellah New York Medical Care for Nephrology Institute for Microbiology and Immunology Medical Faculty of Ljubljana University of Ljubljana

Objective: To assess the antioxidant content, antimicrobial and antioxidant activities of various propolis samples. Methods: Seven propolis samples were collected from different locations in Morocco, which are characterized by different plant predominant vegetations. The resin, wax and balsam of hydroalcoholic extract of propolis content were identified, and the antioxidant content was analyzed with the use of HPLC and colorimetric methods. The antioxidant activity was assessed by DPPH, ABTS.^+ and ferric reducing power assays. The antimicrobial activity was assessed against bacterial species, including methicillin resistant Staphylococcus aureus and Candida albicans, and expressed as the minimal inhibitory concentration. Results: The propolis samples showed significant variations in the chemical composition and in the antioxidant or antimicrobial activities even when the samples were collected from the same location. Propolis with high resin and low wax content had high level of antioxidant compounds, and strong antioxidant and antimicrobial activities. Gram-positive bacteria, especially, methicillin resistant Staphylococcus aureus were more sensitive to all propolis samples than Gram-negative bacteria and Candida albicans. Conclusions: The chemical composition and the antioxidant and antimicrobial activities of various propolis samples are different and rely on the geographic and plant origin of propolis collection. Propolis samples with low wax and high resin content might be more suitable to be used in future preclinical or clinical investigations.

关键词： Propolis Antimicrobial Antioxidant Phenol Candida albicans Methicillin resistant Staphylococcus aureus

Extracellular Polymeric Substance (EPS) Production by Nostoc minutum under Different Laboratory Conditions

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Advances in Microbiology 2016年第5期6卷 374-380页

作者： Dante S. Videla pereyra Susana G. Ferrari Laboratorio de Microbiología Universidad Nacional de San Luis Ejército de los Andes y Estado de Israel San Luis Argentina

A study of the influence of different laboratory growth conditions on the biomass and EPS production by Nostoc minutum, a diazothophic cyanobacterium locally isolated, was carried out. Two culture media were tested, with or without NaNO3 addition, and three luminous intensities: low (4530 lux), intermediate (7300 lux) and high (9860 lux). BW3 medium was better than BG11 for N. minutum growth, with maximal values of biomass concentration (4.98 DO) and the highest growth rate (0.019 h-1) at 9860 lux of light intensity. A progressive increase in culture viscosity of N. minutum cultures was observed, for stirred condition and non-diazotrophic growth in BG11 medium, together with the production of maximal EPS concentration (2.485 g/L). On the other hand, the EPS production in BW3 medium was maximal in diazotrophic conditions, both for still (1.66 g/L) and stirred (2.56 g/L) cultures. The different yields of EPS reported for each condition, results in the requirement of a species-specific optimization of the cultivation conditions for the exploitation of an efficient technology for the production of N. minutum EPS.

关键词： Exopolysaccharides Cyanobacteria Nostoc minutum