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A probabilistic model for sediment entrainment:The role of bed irregularity

International Journal of Sediment Research 2017年第2期32卷 137-148页

作者： Mohamed Elhakeem A.N.Thanos Papanicolaou achilleas g.tsakiris Abu Dhabi University University of Tennessee Civil and Environmental Engineering University of Tennessee

A generalized probabilistic model is developed in this study to predict sediment entrainment under the incipient motion,rolling,and pickup modes.A novelty of the proposed model is that it incorporates in its formulation the probability density function of the bed shear stress,instead of the near-bed velocity fluctuations,to account for the effects of both flow turbulence and bed surface irregularity on sediment *** proposed model incorporates in its formulation the collective effects of three parameters describing bed surface irregularity,namely the relative roughness,the volumetric fraction and relative position of sediment particles within the active *** key feature of the model is that it provides a criterion for estimating the lift and drag coefficients jointly based on the recognition that lift and drag forces acting on sediment particles are interdependent and vary with particle protrusion and packing *** model was validated using laboratory data of both fine and coarse sediment and was compared with previously published *** study results show that all the examined models perform adequately for the fine sediment data,where the sediment particles have more uniform gradation and relative roughness is not a *** proposed model was particularly suited for the coarse sediment data,where the increased bed irregularity was captured by the new parameters introduced in the model *** a result,the proposed model yielded smaller prediction errors and physically acceptable values for the lift coefficient compared to the other models in case of the coarse sediment data.

关键词： Sediment entrainment Probabilistic models Bed surface irregularity Active layer relative roughness Packing density Volumetric fraction of sediment

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Influence of Collective Boulder Array on the Surrounding Time-averaged and Turbulent Flow Fields

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Journal of Mountain Science 2014年第6期11卷 1420-1428页

作者： achilleas g.tsakiris A.N.Thanos PAPANICOLAOU Seyed M.HAJIMIRZAIE James H.J.BUCHHOLZ IIHR-Hydroscience &Engineering The University of Iowa Iowa City IA 52246-1585 USA Department of Civil and Environmental Engineering The University of Tennessee at Knoxville 412 John D. Tickle Building Knoxville TN37996 USA South Florida WaterManagementDistrict WestPalm Beach FL 33416 USA

Arrays of large immobile boulders,which are often encountered in steep mountain streams,affect the timing and magnitude of sediment transport events through their interactions with the approach *** their importance in the quantification of the bedload rate,the collective influence of a boulder array on the approach timeaveraged and turbulent flow field has to date been *** overarching objective is,thus,to assess the collective effects of a boulder array on the time-averaged and turbulent flow fields surrounding an individual boulder within the array,placing particular emphasis on highlighting the bed shear stress spatial *** objective of this study is pursued by resolving and comparing the timeaveraged and turbulent flow fields developing around a boulder,with and without an array of isolated boulders being *** results show that the effects of an individual boulder on the time-averaged streamwise velocity and turbulence intensity were limited to the boulder's immediate vicinity in the streamwise(x/d c ged streamwise velocity was found to be globally *** global deceleration was attributed to the form drag generated collectively by the boulder *** importantly,the boulder array reduced the applied shear stress exerted on theindividual boulders found within the array,by absorbing a portion of the total applied ***,the array was found to have a "homogenizing" effect on the near-bed turbulence thus significantly reducing the turbulence intensity in the near-bed *** findings of this study suggest that the collective boulder array bears a portion of the total applied bed shear stress as form drag,hence reducing the available bed shear stress for transporting incoming mobile ***,the effects of the boulder array should not be ignored in sediment transport *** effects are enc

关键词： Boulder array Form drag Bed shear stress Time-averaged velocity Turbulence intensity

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Modeling the impact of climate change on sediment transport and morphology in coupled watershed-coast systems:A case study using an integrated approach

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International Journal of Sediment Research 2014年第3期29卷 304-315页

作者： achilleas g.SAMARAS Christopher g KOUTITAS Research Fellow CIRI-ECFluid Dynamics Research UnitUniversity of BolognaVia del Lazzaretto 15/5Bologna 40131Italy Department of Civil Engineering Aristotle University of ThessalonikiUniversity Campus

Climate change is an issue of major concern *** impact on the natural and human environment is studied intensively,as the expected shift in climate will be significant in the next few *** experience shows that the effects will be critical in coastal areas,resulting in erosion and inundation phenomena *** addition to that,coastal areas are subject to "pressures" from upstream watersheds in terms of water quality and sediment *** present paper studies the impact of climate change on sediment transport and morphology in the aforementioned coupled *** study regards a sandy coast and its upstream watershed in Chalkidiki,North greece;it is based on:(a)an integrated approach for the quantitative correlation of the two through numerical modeling,developed by the authors,and(b)a calibrated application of the relevant models Soil and Water Assessment Tool(SWAT)and PELNCON-M,applied to the watershed and the coastal zone,*** examined climate change scenarios focus on a shift of the rainfall distribution towards fewer and more extreme rainfall events,and an increased frequency of occurrence of extreme wave *** indicate the significance of climatic pressures in wide-scale sediment dynamics,and are deemed to provide a useful perspective for researchers and policy planners involved in the study of coastal morphology evolution in a changing climate.

关键词： Climate change Sediment transport Coastal morphology Integrated approach Numerical modeling

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Autophagic flux response and glioblastoma sensitivity to radiation

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Cancer Biology & Medicine 2018年第3期15卷 260-274页

作者： achilleas g.Mitrakas Dimitra Kalamida Alexandra giatromanolaki Stamatia Pouliliou Avgi Tsolou Rafail Kyranas Michael I.Koukourakis Department of Radiotherapy/Oncology democritus university of thraceand university general hospital of alexandroupolisAlexandroupolis 68200Greece Department of Pathology Democritus University of Thraceand University General Hospital of AlexandroupolisAlexandroupolis 68200Greece

Objective:glioblastoma is the most common primary brain tumor in adults and one of the most lethal human *** constitutes a unique non-metastasizing human tumor model with high resistance to radiotherapy and *** current study investigates the association between autophagic flux and glioblastoma cell ***:The expression kinetics of autophagy-and lysosome-related proteins following exposure of two glioblastoma cell lines(T98 and U87)to clinically relevant radiation doses was ***,the response of cells resistant to radiotherapy and chemotherapy was investigated after silencing of LC3A,LC3B,and TFEB genes in vitro and in ***:Following irradiation with 4 gy,the relatively radioresistant T98 cells exhibited enhanced autophagic *** more radiosensitive U87 cell line suffered a blockage of autophagic *** of LC3A,LC3B,and TFEB genes in vitro,significantly sensitized cells to radiotherapy and temozolomide(U87:Pg of the LC3A gene sensitized mouse xenografts to ***:Autophagy in cancer cells may be a key factor of radio-resistance and chemo-resistance in glioblastoma *** autophagy may improve the efficacy of radiochemotherapy for glioblastoma patients.

关键词： glioblastoma autophagy radiation temozolomide TFEB

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CO_(2) capture using membrane contactors:a systematic literature review

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Frontiers of Chemical Science and Engineering 2021年第4期15卷 720-754页

作者： Sanaa Hafeez Tayeba Safdar Elena Pallari george Manos Elsa Aristodemou Zhien Zhang S.M.Al-Salem achilleas Constantinou Division of Chemical and Energy Engineering School of EngineeringLondon South Bank UniversityLondon SE10AAUK Medical Research Council Clinical Trials Unit University College LondonLondon WC1V 6LJUK Department of Chemical Engineering University College LondonLondon WCIE 7JEUK William g.Lowrie Department of Chemical and Biomolecular Engineering The Ohio State UniversityColumbusOH 43210USA Environment&Life Sciences Research Centre Kuwait Institute for Scientific ResearchSafat 13109Kuwait Department of Chemical Engineering Cyprus University of Technology Limassol 3036Cyprus

With fossil fuel being the major source of energy,CO_(2) emission levels need to be reduced to a minimal amount namely from anthropogenic *** consumption is expected to rise by 48%in the next 30 years,and global warming is becoming an alarming issue which needs to be addressed on a thorough technical ***,exploring CO_(2) capture using membrane contactor technology has shown great potential to be applied and utilised by industry to deal with post-and pre-combustion of CO_(2).A systematic review of the literature has been conducted to analyse and assess CO_(2) removal using membrane contactors for capturing techniques in industrial *** review began with a total of 2650 papers,which were obtained from three major databases,and then were excluded down to a final number of 525 papers following a defined set of *** results showed that the use of hollow fibre membranes have demonstrated popularity,as well as the use of amine solvents for CO_(2) *** current systematic review in CO_(2) removal and capture is an important milestone in the synthesis of up to date research with the potential to serve as a benchmark databank for further research in similar areas of *** study provides the first systematic enquiry in the evidence to research further sustainable methods to capture and separate CO_(2).

关键词： CO_(2)capture preferred reporting items for systematic reviews and meta-analysec membranc contactor absorbent

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Associations between nonalcoholic fatty liver disease and ischemic stroke

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World Journal of Hepatology 2018年第7期10卷 474-478页

作者： Stelina Alkagiet achilleas Papagiannis Konstantinos Tziomalos First Propedeutic Department of Internal Medicine Medical School Aristotle University of Thessaloniki AHEPA Hospital

Nonalcoholic fatty liver disease(NAFLD) is the commonest chronic liver disease and affects a considerab-le proportion of the general population. NAFLD is independently associated with increased risk for cardiovascular events, particularly coronary heart disease. Importantly, even though NAFLD is more prevalent in patients with major cardiovascular risk factors(e.g., type 2 diab-etes mellitus, ob-esity and hypertension), the association b-etween NAFLD and cardiovascular disease appears to b-e independent of these risk factors. However, NAFLD also appears to increase the risk for ischemic stroke, a leading cause of mortality and long-term disab-ility worldwide. It also appears that nonalcoholic steatohepatitis is more strongly related to the risk of ischemic stroke than isolated hepatic steatosis. Moreover, emerging data suggest that patients with NAFLD experience more severe ischemic stroke and have more unfavorab-le prognosis after an acute ischemic stroke in terms of functional dependency and short-and long-term mortality. These associations have major pub-lic health implications, since ischemic stroke is the second leading cause of death worldwide and an important cause of long-term disab-ility. The aim of the present review is to summarize the current knowledge regarding the relationship b-etween NAFLD and ischemic stroke incidence, severity and outcome. given these associations, it might b-e useful to evaluate patients with acute ischemic stroke for the presence of NAFLD and to manage those with NAFLD more aggressively.

关键词： Nonalcoholic fatty liver disease Ischemic stroke Risk Incidence Severity Outcome Functional dependency

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Extracorporeal organ support for critically ill patients:Overcoming the past,achieving the maximum at present,and redefining the future

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World Journal of Critical Care Medicine 2024年第2期13卷 19-28页

作者： Panagiotis Papamichalis Katerina g Oikonomou Maria Xanthoudaki Asimina Valsamaki Apostolia-Lemonia Skoura Sophia K Papathanasiou achilleas Chovas Intensive Care Unit General Hospital of LarissaLarissa 41221Greece Department of Transfusion Medicine University Hospital of LarissaLarissa 41110Greece Department of Internal Medicine General Hospital of LarissaLarissa 41221Greece

Extracorporeal organ support(ECOS)has made remarkable progress over the last few *** replacement therapy,introduced a few decades ago,was the first available application of *** subsequent evolution of ECOS enabled the enhanced support to many other organs,including the heart[veno-arterial extracorporeal membrane oxygenation(ECMO),slow continuous ultrafiltration],the lungs(veno-venous ECMO,extracorporeal carbon dioxide removal),and the liver(blood purification techniques for the detoxification of liver toxins).Moreover,additional indications of these methods,including the suppression of excessive inflammatory response occurring in severe disorders such as sepsis,coronavirus disease 2019,pancreatitis,and trauma(blood purification techniques for the removal of exotoxins,endotoxins,or cytokines),have *** organ support therapy is crucial since a vast majority of critically ill patients present not with a single but with multiple organ failure(MOF),whereas,traditional therapeutic approaches(mechanical ventilation for acute respiratory failure,antibiotics for sepsis,and inotropes for cardiac dysfunction)have reached the maximum efficacy and cannot be improved ***,several issues remain to be clarified,such as the complexity and cost of ECOS systems,standardization of indications,therapeutic protocols and initiation time,choice of the patients who will benefit most from these interventions,while evidence from randomized controlled trials supporting their use is still ***,these methods are currently a part of routine clinical practice in intensive care *** editorial presents the past,present,and future considerations,as well as perspectives regarding these *** better understanding of these methods,the pathophysiology of MOF,the crosstalk between native organs resulting in MOF,and the crosstalk between native organs and artificial organ support systems when applied sequentially or simultaneously,will lead t

关键词： Kidney-liver replacement therapy Heart-lung support Blood purification Native–artificial organ crosstalk Multiple organ support therapy Extracorporeal organ support

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