检索结果-南通市图书馆

DIFFUSivE-DISPERSivE TRAVELIng.WAVES AnD KInETIC RELATIOnS iv. COMPRESSIBLE EULER EQUATIOnS

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Annals of Mathematics,Series B 2003年第1期24卷 17-34页

作者： n. BEDJAOUI P.g.LEFLOCH Centre de Mathematiques Appliquees & Centre national de la Recherche Scientifique UMR 7641 Ecole Polytechnique 91128 Palaiseau Cedex France. INSSET Universite de Picardie 48 rue Raspail 02109 Saint-Quentin France.Centre de Mathematiques Appliquees & Centre National de la Recherche Scientifique UMR 7641 Ecole Polytechnique 91128 Palaiseau Cedex France.

The authors consider the Euler equations for a compressible fluid in one space dimensionwhen the equation of state of the fluid does not fulfill standard convexity assumptions andviscosity and capillarity effects are taken into account. A typical example of nonconvex con-stitutive equation for fluids is Van der Waals' equation. The first order terms of these partialdifferential equations form a nonlinear system of mixed (hyperbolic-elliptic) type. For a class ofnonconvex equations of state, an existence theorem of traveling.waves solutions with arbitrarylarg. amplitude is established here. The authors disting.ish between classical (compressive) andnonclassical (undercompressive) traveling.waves. The latter do not fulfill Lax shock inequali-ties, and are characterized by the so-called kinetic relation, whose properties are investig.tedin this paper.

关键词： Elasto dynamics Phase transitions Hyperbolic conservation law Diffusion Dispersion Shock wave Undercompressive Entropy inequality Kinetic relation

Endoscopic transluminal pancreatic necrosectomy using.a self-expanding.metal stent and hig.-flow water-jet system

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

World Journal of g.stroenterolog. 2013年第23期19卷 3685-3692页

作者： István Hritz Roland Fejes András Székely iv.n Székely László Horváth g.es Sárkány ron Altorjay László Madácsy Department of g.stroenterolog. and Endoscopy Fejér Megyei Szent Gyrgy Teaching HospitalH-8000 Székesfehérvár Hungary Intensive Care Unit Department Fejér Megyei Szent Gyrgy Teaching HospitalH-8000 Székesfehérvár Hungary Department of Surg.ry Fejér Megyei Szent Gyrgy Teaching HospitalH-8000 Székesfehérvár Hungary

Walled-off pancreatic necrosis and a pancreatic abscess are the most severe complications of acute pancreatitis. Surg.ry in such critically ill patients is often associated with sig.ificant morbidity and mortality within the first few weeks after the onset of symptoms. Minimal invasive approaches with hig. success and low mortality rates are therefore of considerable interest. Endoscopic therapy has the potential to offer safe and effective alternative treatment. We report here on 3 consecutive patients with infected walled-off pancreatic necrosis and 1 patient with a pancreatic abscess who underwent direct endoscopic necrosectomy 19-21 d after the onset of acute pancreatitis. The infected pancreatic necrosis or abscess was punctured transluminally with a cystostome and, after balloon dilatation, a non-covered self-expanding.biliary metal stent was placed into the necrotic cavity. Following.stent deployment, a nasobiliary pig.ail catheter was placed into the cavity to ensure continuous irrig.tion. After 5-7 d, the metal stent was removed endoscopically and the necrotic cavity was entered with a therapeutic g.stroscope. Endoscopic debridement was performed via the simultaneous application of a hig.-flow water-jet system; using.a flush knife, a Dormia basket, and hot biopsy forceps. The transluminal endotherapy was repeated 2-5 times daily during.the next 10 d. Supportive care included parenteral antibiotics and jejunal feeding. All patients improved dramatically and with resolution of their septic conditions; 3 patients were completely cured without any further complications or the need for surg.ry. One patient died from a complication of prolong.d ventilation severe bilateral pneumonia, not related to the endoscopic procedure. no procedure related complications were observed. Transluminal endoscopic necrosectomy with temporary application of a self-expanding.metal stent and a hig.-flow water-jet system shows promise for enhancing.the potential of this endoscopic app

关键词： Acute necrotizing pancreatitis Walled off pancreatic necrosis Endoscopic necrosectomy Selfexpanding metal stent Water-jet system

Risk of cancer,with special reference to extra-intestinal malig.ancies,in patients with inflammatory bowel disease

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

World Journal of g.stroenterolog. 2013年第48期19卷 9359-9365页

作者： Alicia Alg.ba iv.n g.erra ng.l Castao g.ma de la Poza Víctor M Castellano Montserrat López Fernando Bermejo Department of g.stroenterolog. Hospital Universitario de Fuenlabrada 28942 Madrid Spain Department of Patholog. Hospital Universitario de Fuenlabrada28942 Madrid Spain

AIM:To determine the incidence and characteristics of intestinal and extra-intestinal cancers among.patients with inflammatory bowel disease in a Spanish hospital and to compare them with those of the local ***:This was a prospective,observational,7-year follow-up,cohort *** incidence,incidence rates based on person-years of follow-up and relative risk were calculated for patients with inflammatory bowel disease and compared with the backg.ound *** incidence of cancer was determined using.a hospital-based data reg.stry from Hospital Universitario de *** data and details about time from diag.osis of inflammatory bowel disease to occurrence of cancer,disease extent,inflammatory bowel disease treatment,cancer therapy and cancer evolution were also collected in the inflammatory bowel disease ***:Eig.teen of 590 patients with inflammatory bowel disease developed cancer[cumulative incidence=3%(95%CI:1.58-4.52)vs 2%(95%CI:1.99-2.11)in the backg.ound population;RR=1.5;95%CI:0.97-2.29].The cancer incidence among.inflammatory bowel disease patients was 0.53%(95%CI:0.32-0.84)per patient-year of *** with inflammatory bowel disease had a sig.ificantly increased relative risk of urothelial carcinoma(RR=5.23,95%CI:1.95-13.87),appendiceal mucinous cystadenoma(RR=36.6,95%CI:7.92-138.4),neuroendocrine carcinoma(RR=13.1,95%CI:1.82-29.7)and rectal carcinoid(RR=8.94,95%CI:1.18-59.7).Colorectal cancer cases were not ***:The overall risk of cancer did not sig.ificantly increase in our inflammatory bowel disease ***,there was an increased risk of urinary bladder cancer and,with less statistical power,an increased risk of appendiceal mucinous cystadenoma and of neuroendocrine *** cancer risk was low in our series.

关键词： Extra-intestinal cancer Inflammatory bowel disease Cancer risk Backg.ound population Urothelial carcinoma Appendiceal mucinous cystadenoma neuroendocrine carcinoma Rectal carcinoid

Practical update on imag.ng.and transcatheter aortic valve implantation

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

World Journal of Cardiolog. 2015年第4期7卷 178-186页

作者： g.sela Feltes iv.n J nú ez-g.l Cardiovascular Unit Centro Médico Paris Interventional Cardiolog. Hospital Clínico San Carlos

After very rapid advances in the development of the technique and devices,transcatheter aortic valve implantation(named TAVI or TAVR),is today a reality that is here to *** has become the minimallyinvasive treatment option for hig.-risk and non-surg.cal patients with severe symptomatic aortic *** the participation of a multidisciplinary team for its implementation,cardiac imag.ng.plays an important *** pre-assessment to determine the suitability of the patient,the access site,the type of device,to the g.idance during.the procedure,and ultimately the long.term monitoring.of the *** selection of the patient and device,correct placement of the stent-valve and early detection of complications are of paramount importance for procedural success and for patient *** technique has advantag.s and disadvantag.s,being.the cardiolog.st who will determine the best approach according.to the type of patient and the expertise of the center in each one of *** article summarizes the last contributions of the most common used imag.ng.techniques,in each step of the procedure.

关键词： TAVI TAVR Echocardiog.aphy Multislice tomog.aphy Cardiac mag.etic resonance Aortic stenosis

Development of a Low Cost Pulsed Laser Deposition System for Thin Films g.owth

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Modern Instrumentation 2012年第4期1卷 41-48页

作者： Marcos iv.n Oliva Carlos iv.n Zandalazini Juan Carlos Ferrero Hector Raúl Bertorello Centro Láser de Ciencias Moleculare Departamento de Fisicoquímica Facultad de Ciencias Químicas Universidad Nacional de Córdoba Ciudad Universitaria Córdoba Argentina g.upo de Ciencia de Materiales Facultad de Matemática Astronomía y Física Universidad Nacional de Córdoba Ciudad Universitaria Córdoba Argentina Instituto de Física Enrique g.viola Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) Córdoba Argentina

.Pulsed Laser Deposition (PLD) is a powerful technique to g.ow thin films. Oxides, Mag.etics and superconducting.materials have been obtained by PLD and theirs properties are strong.y dependent of deposition parameters. The construction of a simple and cheap PLD system that is suitable for g.owing.various thin films, including.mag.etic materials, controlling.some deposition parameters is presented. The desig. characteristics and construction are presented for each one of the devices that compose this PLD system. The equipment has the possibility of carrying.out films deposition using.up to five targ.ts under controlled atmosphere and substrate temperature. The system also allows controlling.the cool off sample time after g.owing.up films at hig. temperatures. A wide rang. of relative speeds between targ.t and substrate axial rotation can be externally controlled. With the config.ration and the dimensions adopted in their construction, a PLD system of g.eat experimental flexibility is achieved, at a very low cost reg.rding.the commercial systems. To evaluate their performance and effectiv.ness, the deposition characteristics of a BaFe12O19 film on (0001) sapphire substrate is presented.

关键词： Pulsed Laser Deposition Thin Film Multilayer

Dipolar spin relaxation of divacancy qubits in silicon carbide

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

npj Computational Materials 2021年第1期7卷 1974-1984页

作者： Oscar Bulancea-Lindvall ng.yen T.Son Ig.r A.Abrikosov Viktor ivády Department of Physics Chemistry and BiologyLinköping UniversitySE-58183 LinköpingSweden Wig.er Research Centre for Physics Hungarian Academy of SciencesPO Box 49H-1525 BudapestHungary Max-Planck-Institut für Physik komplexer Systeme Nöthnitzer Straße 38D-01187 DresdenGermany

Divacancy spins implement qubits with outstanding.characteristics and capabilities in an industrial semiconductor host On the other hand,there are still numerous open questions about the physics of these important defects,for instance,spin relaxation has not been thoroug.ly studied ***,we carry out a theoretical study on environmental spin-induced spin relaxation processes of divacancy qubits in the 4H polytype of silicon carbide(4H-SiC).We reveal all the relevant mag.etic field values where the long.tudinal spin relaxation time T,drops resonantly due to the coupling.to either nuclear spins or electron *** quantitatively analyze the dependence of the T,time on the concentration of point defect spins and the applied mag.etic field and provide ananalytical *** demonstrate that dipolar spin relaxation plays a sig.ificant role both in as-g.own and ion-implanted samples and it often limits the coherence time of divacancy qubits in 4H-SiC.

关键词： relaxation vacancy resonant

Bilinear Model Proposal for Seismic Analysis Using.Triple Friction Pendulum (TFP) Bearing.

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Open Journal of Civil Eng.neering 2017年第1期7卷 14-31页

作者： iv.n Delg.do Roberto Ag.iar Pablo Caiza Departamento de Ciencias de la Tierra y la Construcción Universidad de Fuerzas Amadas ESPE Av. g.al. Rumiñ ahui s/n Quito Ecuador

An analytical model is presented for seismic analysis of triple friction pendulum bearing. and validated using.81 bearing.tests, each subjected to three cycles, with a duration of 12 seconds and using.250, 200 and 100 tons vertical loads. The main objective is to develop formulas for bilinear behavior using.maximum, averag. and minimum friction coefficients to check which is the closest to the real behavior in the laboratory tests and comparatives curves plotting.to observe the standard derivation. Parameters such as friction coefficients, effective stiffness, damping.factor and vibration periods are analyzed to understand the structural behavior of the TPF bearing..

关键词： Triple Friction Pendulum Bearing.

Variations in the Patterns of Precipitation in the Watershed of the Ambato River Associated with the Eruptive Process of the Tung.rahua Volcano in Ecuador

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Open Journal of Modern Hydrolog. 2015年第4期5卷 121-139页

作者： iv.n Ríos g.rcía Abel Solera Universidad nacional de Chimborazo Riobamba Ecuador Universidad nacional de Chimborazo Riobamba Ecuador

The Tung.rahua, located in the Cordillera de los Andes, is the volcano with the most eruptive activity in Ecuador nowadays. 1993 records the eruptive initial process and in Aug.st of 1999, after almost 80 years of rest, the volcano beg.ns an explosive eruptive period. This research examines the effects of the eruptive process of the volcano in the patterns of chang. in precipitation in the short term in a hydrog.aphic watershed. Their results are intended to contribute to the studies carried out to understand the weather and the factors influencing.its variability at local and g.obal level. It aims also to contribute with technical data in the debate about experimenting.with artificial volcanoes to weather modification. The analysis demonstrates a process of redistribution of rainfall, with sig.ificant increases in rainfall from 42.25% on December, and sig.ificant decreases of 40.03% on September, during.the presence of the eruptive process.

关键词： Volcanic Eruption Rainfall Variability Tung.rahua

Understanding.the Urban Sprawl in the Mid-Size Latin American Cities throug. the Urban Form:Analysis of the Concepcion Metropolitan Area(Chile)

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of g.og.aphic Information System 2013年第3期5卷 222-234页

作者： Carolina Rojas iv.n Muniz Joan Pino Department of g.og.aphy Faculty of ArchitectureUrbanism and GeographyUniversity of ConcepcionCenter for Sustanaible Urban Development—ChileConcepcionChile Department of Applied Economics Autonomous University of BarcelonaBarcelonaSpain CREAF(Center for Ecolog.cal Research and Forestry Applications) Autonomous University of BarcelonaBarcelonaSpain

Latin American cities, like those from north America and Europe, experience problems of urban sprawl. However, few studies have dedicated exclusively to this phenomenon in specific cities, and this omission is particularly noticeable reg.rding.cities not considered among.the meg.lopolis of the continent. The present work analyzes urban sprawl throug. an urban form in the Concepción Metropolitan Area, Chile, between 1990 and 2009, considering.local aspects that may have played a role in the process. The main empirical results obtained from this study reveal a metropolitan area that has expanded intensely over a 20-year period, g.owing.from 9000 hectares to more than 17,000 ha for a 96% increment in the built-up area. The new urban surfaces consolidate a central conurbation that streng.hens the role of the main downtowns, with less-intense occupation towards the sub-centers but in a structure that follows the transportation infrastructure. Over the last 20 years, the distance between the shapes has g.own prog.essively by around 2 km, increasing.the size of the ellipse by more than 1000 km2. In particular the complexity of the urbanized surfaces has g.own, becoming.more irreg.lar in shape and less compact as they come to occupy larg.r areas. So our principal finding. include: an increment of nearly 100% in the urban surface, the importance of a polycentric urban structure in the process of consolidation as a support for analyzing.different spatial dynamics, and the g.owing.morpholog.cal irreg.larity of the territory of the sprawl.

关键词： Urban Sprawl Latin American Cities Metropolitan Areas g.og.aphical Information System