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An accurate model for the thin film flow

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Acta Mechanica Sinica 2008年第4期24卷 375-380页

作者： hamid Ait Abderahmane georgios h.vatistas Department of Mechanical and Industrial Engineering Concordia University 1455 de Maisonneuve Blvd West Montreal OC h3G 1M8 Canada

This paper deals with the linear stability of a liquid film flowing down an inclined plane. The Navier-Stokes equations were reduced into four evolution equations that describe the development of the film depth, the flow rate, the free surface velocity, and the wall shear stress, using the Karman-Polhausen boundary layer integral method. Thus, we were able to determine the stability threshold and approach well the critical wave number for long waves. The obtained results were found to be in good agreement with the experiments of Liu et al.

关键词： Liquid film Linear stability Flow model

On the refracted patterns produced by liquid vortices

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Acta Mechanica Sinica 2007年第1期23卷 11-15页

作者： Yasser Aboelkassem georgios h.vatistas McGill University MontrealQCH3A-2K6Canada Concordia University MontrealQCH3G 1M8Canada

A theoretical analysis of the refracted shadows produced by steady and time-decaying liquid vortices under uniform illumination from above is given in this article. An expression for the induced shadow intensity is derived and found to be a function of the vortex＇s free surface profile, i.e., function of the static pressure distribution. The patterns for different focusing depth are given and compared with previous visualization results from the literature. The phenomenon is examined and illustrated as a bench mark case by using both steady and time-decaying algebraic vortex models. however, this study can be extended to check the feasibility of recovering the main flow properties by analyzing the luminous image intensity of the refracted patterns. The present analysis is valid only when the swirl velocity is order of magnitude higher than the meridional flow components and the vorticity is concentrated within the core region and of intense conditions.

关键词： Fluid dynamics - Vortices - Dark shadows Intensity - Time decay

A Study on Refractive Index Sensors Based on Optical Micro-Ring Resonators

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Photonic Sensors 2017年第3期7卷 217-225页

作者： georgios N. TSIGARIDAS Department of Physics School of Applied Mathematical and Physical Sciences National Technical University of Athens Zografou Campus GR-15780 Zografou Athens Greece

In this work, the behavior of refractive index sensors based on optical micro-ring resonators is studied in detail. Using a result of waveguide perturbation theory in combination with numerical simulations, the optimum design parameters of the system, maximizing the sensitivity of the sensor, are determined. It is found that, when optimally designed, the sensor can detect relative refractive index changes of the order of △n/n≈3×10^-4, assuming that the experimental setup can detect relative wavelength shifts of the order of △λ/λ≈3×10^-5. The behavior of the system as bio-sensor has also been examined. It is found that, when optimally designed, the system can detect refractive index changes of the order of △n≈ 10^-3 for a layer thickness of t=- 10 nm, and changes in the layer thickness of the order of △t≈0.24 nm, for a refractive index change of △n=0.05.

关键词： Optical micro-ring resonators refractive index sensors bio-sensors nano-photonic sensors

Model Reference Adaptive Control for Networked Distributed Systems with Strong Interconnections and Communication Delays

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Journal of Systems Science & Complexity 2018年第1期31卷 38-68页

作者： LYMPEROPOULOS georgios IOANNOU Petros Department of Electrical Engineering University of Southern California

In recent years, networked distributed control systems（NDCS） have received research attention. Two of the main challenges that such systems face are possible delays in the communication network and the effect of strong interconnections between agents. This paper considers an NDCS that has delays in the communication network, as well as strong interconnections between its agents. The control objective is to make each agent track efficiently a reference model by attenuating the effect of strong interconnections via feedback based on the delayed information. First, the authors assume that each agent knows its own dynamics, as well as the interconnection parameters, but receives information about the states of its neighbors with some communication delay. The authors propose a distributed control scheme and prove that if the interconnections can be weakened and if the communication delays are small enough, then the proposed scheme guarantees that the tracking error of each agent is bounded with a bound that depends on the size of the weakened interconnections and delays, and reduces to zero as these uncertainties reduce to zero. The authors then consider a more realistic situation where the interconnections between agents are unknown despite the cooperation and sharing of state information. For this case the authors propose a distributed adaptive control scheme and prove that the proposed scheme guarantees that the tracking errors are bounded and small in the mean square sense with respect to the size of the weakened interconnections and delays, provided the weakened interconnections and time delays are small enough. The authors then consider the case that each agent knows neither its dynamics nor the interconnection matrices. For this case the authors propose a distributed adaptive control scheme and prove that the proposed scheme guarantees that the tracking errors are bounded and small in the mean square sense provided the weakened interconnections and time delays are

关键词： Adaptive control network distributed control delay systems

hepatocellular carcinoma and metabolic syndrome: The times are changing and so should we

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World Journal of Gastroenterology 2019年第29期25卷 3842-3848页

作者： georgios Tsoulfas Department of Surgery Aristotle University of Thessaloniki

Although hepatocellular carcinoma (hCC) is as prevalent as ever as a cancerrelated mortality, and some would even argue that it is increasing, the pattern of its etiologies has been changing. Specifically, the domination of viral hepatitis C virus is being overcome, partly because of the emergence of the antiviral treatments, and partly because of the significant increase, especially in developed countries, of the combination of obesity, diabetes, metabolic syndrome, nonalcoholic fatty liver disease and non-alcoholic steatohepatitis. This editorial will explore the interconnection of this group of diseases and how they are linked to hCC. More importantly, it will argue that this shift in hCC etiology essentially means that we have to change how we approach the treatment of hCC, by changing our focus (and resources) to earlier stages of the disease development in order to prevent the appearance and progression of hCC.

关键词： hepatocellular carcinoma Diabetes Obesity Steatosis Non-alcoholic fatty liver disease Body-mass index Non-alcoholic steatohepatitis

Risk of colorectal neoplasm in patients with acromegaly: A meta-analysis

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World Journal of Gastroenterology 2008年第22期14卷 3484-3489页

作者： Theodoros Rokkas Dimitrios Pistiolas Panos Sechopoulos georgios Margantinis georgios Koukoulis Gastroenterology Clinic Henry Dunant Hospital 107 Messogion Ave. Athens 11526 Greece

AIM: To examine the risk of colorectal neoplasm in acromegalic patients by meta-analyzing all relevant controlled studies. METhODS: Extensive English language medical literature searches for human studies, up to December 2007, were performed using suitable keywords. Pooled estimates [odds ratio (OR) with 95% confidence intervals (CI)] were obtained using either the fixed or random-effects model as appropriate. heterogeneity between studies was evaluated with the Cochran Q test whereas the likelihood of publication bias was assessed by constructing funnel plots. Their symmetry was estimated by the adjusted rank correlation test. RESULTS: For hyperplastic polyps the pooled ORs with 95% CI were 3.557 (2.587-4.891) by fixed effects model and 3.703 (2.565-5.347) by random effects model. The Z test values for overall effect were 7.81 and 6.984, respectively (P he pooled ORs with 95% CI were 2.486 (1.908-3.238) (fixed effects model) and 2.537 (1.914-3.364) (random effects model). The Z test values were 6.747 and 6.472, respectively (P he pooled OR with 95% CI was identical for both fixed and random effects model (OR, 4.351; 95% CI, 1.533-12.354; Z = 2.762, P = 0.006]. There was no significant heterogeneity and no publication bias in all the above meta-analyses. CONCLUSION: Acromegaly is associated with an increased risk of colorectal neoplasm.

关键词： Acromegaly Colon cancer Colon polyps Colon neoplasia Meta-analysis

Anion effect on Li/Na/K hybrid electrolytes for Graphite//NCA(LiNi_(0.8)Co_(0.15)Al_(0.05)O_(2))Li-ion batteries

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Journal of Energy Chemistry 2022年第1期31卷 451-462,I0012页

作者： Aiman Jrondi georgios Nikiforidis Meriem Anouti Laboratoire PCM2E Universite de ToursFaculte des sciences et technologiePare de Grandmont37200 ToursFrance LE STUDIUM Institute for Advanced Studies 45000 OrleansFrance

The electrolyte is an essential component of a battery system since it is responsible for the conduction of ions between the *** the quest for cheaper alternatives to common organic electrolytes for lithium-ion batteries(LIB),we formulated hybrid electrolytes comprising a mixture of Na,K,and Li alkaline salts with ethylene carbonate(EC),ethyl methyl carbonate(EMC),and lithium hexafluorophosphate(LiPF_(6)),giving a total salt concentration of 1.5 M;we determined their physicochemical properties and investigated their electrochemical behavior on a nickel cobalt aluminum oxide(NCA)cathode and graphite(Gr)*** electrolytes demonstrated a melting transition peak(T_(m)).eutectic behavior,and ionic conductivities(-13 mS cm^(-1))close to those of a commercial LIB electrolyte(SE,EC/EMC+1 M LiPF_(6))and activation energies of ca.3 kJ mol^(-1).The half-cell coin cells revealed high coulombic efficiency(99%),specific capacity(175 mAh g^(-1) at C/10),and capacity retention(92% for NaCF_(3)SO_(3))for the NCA cathode and a moderate performance(coulombic efficiency of 98%for 20 cycles)on the graphite anode after the formation of the SEI *** hybrid electrolytes were cycled at 25℃ in a Gr//NCA cell yielding specific capacities of ca.225 mAh g^(-1) at a C/5 rate,corroborating that the anion plays a key role and highlighting their potential for energy storage applications.

关键词： hybrid electrolyte Alkali salts NCA//Li cell Li-ion battery

Obstetrical and gynecologic challenges in the liver transplant patient

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World Journal of Transplantation 2020年第11期10卷 320-329页

作者： Ioannis A Ziogas Muhammad h hayat georgios Tsoulfas Medical School Aristotle University of ThessalonikiThessaloniki 54124Greece Department of Medicine Division of GastroenterologyHepatology and NutritionVanderbilt University Medical CenterNashvilleTN 37212United States Department of Surgery Papageorgiou University HospitalAristotle University of ThessalonikiThessaloniki 54622Greece

An increasing number of childbearing agewomen undergo liver transplantation(LT)in the United *** in this patient subgroup poses a significant challenge regarding the plans for future fertility,particularly in terms of immunosuppression and optimal timing of *** LT is only rarely performed as the outcome is commonly dismal for the mother or more commonly the *** the other hand,the outcomes of pregnancy in LT recipients are favorable,and children born to LT recipients are relatively *** on pregnancy should start before LT and continue after LT up until pregnancy,while all pregnant LT recipients must be managed by amultidisciplinary team,including both an obstetrician and a transplant ***,an interval of at least 1-2 years after successful LT is recommended before considering ***-induced hypertension,pre-eclampsia,and gestational diabetes mellitus are reported more commonly during the pregnancies of LT recipients than in the pregnancies of non-transplant *** adverse fetal outcomes,such asmiscarriage,abortion,stillbirth,or ectopic pregnancy,may occur more often than in the non-transplant population,early planning or delivery either through a planned induction of labor or cesarean section is critical to minimize the risk of *** significant long-term physical or phycological abnormalities have been reported in children born to LT recipients.

关键词： Liver transplantation Pregnancy Obstetric complications Immunosuppression Fetal outcomes End-stage liver disease

Prediction of severe acute pancreatitis:Current knowledge and novel insights

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World Journal of Gastroenterology 2008年第41期14卷 6273-6275页

作者： georgios I Papachristou Department of Medicine Division of Gastroenterology Hepatology and Nutrition University of Pittsburgh Medical Center

Acute pancreatitis (AP) is a common and potentially lethal acute inflammatory process with a highly variable clinical course. It is still unclear why some patients progress to organ failure and others do not. Physicians, ability to predict which patients will develop severe disease is limited. Routine clinical and laboratory data and multi-factorial clinical scores measured on admission and during the first 48 h of hospitalization are currently the standards of care used to estimate the magnitude of the inflammatory response to injury. Current literature highlights several common environmental, metabolic and genetic factors that increase the risk of AP development and subsequent adverse sequelae. Several cytokines have been found to play a critical role in the pathogenesis of AP by driving the subsequent inflammatory response, to include tumor necrosis factor-α (TNF-α), Interleukin-1 (IL-1), IL-6 and monocyte chemotactic protein-1 (MCP-1). Large, prospective studies are still needed to address these questions by identifying AP risk factors and serum biomarkers of severe disease.

关键词： Acute pancreatitis Prediction Severity Monocyte chemotactic protein-1