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Antioxidants in experimental ischemia-reperfusion injury of the testis: Where are we heading towards?

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World Journal of Methodology 2017年第2期7卷 37-45页

作者： George Vaos nick zavras Department of Paediatric Surgery "ATTIKON" University General Hospital National and Kapodis- trian University of Athens School of Medicine

Testicular torsion(TT) is a medical emergency that primary affects newborns and young *** causes testicular injury due to the torsion of the spermatic cord and its components, initially in the venous blood flow and finally in the arterial blood *** diagnosis and early surgical management are necessary in managing this urgent *** process of the pathophysiological events in ischemia-reperfusion is multifactorial and deals with the perception of the oxidative stress responsible for the consequences of ischemia/reperfusion(I/R) stress following *** and severity of torsion also play a significant role in the oxidative stress.A detrimental result of the defense system of the testes takes place resulting finally in testicular atrophy and impaired *** factors have been experimentally studied in an effort to front this *** have been classified as endogenous or exogenous *** antioxidants comprise a structure of enzymic enzymatic and nonenzymic enzymatic particles presented within cytoplasm and numerous other subunits in the *** antioxidants include a variety of natural and pharmaceutical agents that may prevent or ameliorate the harmful effects of I/R *** this study we review those factors and their ability to enhance the oxidative status of the testis.A feature insight into where we are heading is attempted.

关键词： Testis Torsion Experimental Ischemia-reperfusion injury Antioxidants

Alimentary tract duplications in infancy and childhood. A 25-year experience with focus on rare types of the disease

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Open Journal of Pediatrics 2013年第4期3卷 324-330页

作者： nick zavras Efstratios Christianakis Dimitrios Papakonstantinou Konstantinos Velaoras Konstantinos Tsilikas Khalil Ereikat 3^rd Department of Surgery ATTIKO University Hospital Athens Greece Pediatric Surgery Department Penteli General Children’s Hospital Athens Greece Radiology Department Penteli General Children’s Hospital Athens Greece

Background: Alimentary tract duplications (ATDs) are rare congenital anomalies of the gut tube, seen mainly in neonates and infants. Their presentations are often mimicking other conditions, thus posing a diagnostic challenge. Surgical treatment is required in all cases. Objective: The aim of this study is to present our experience in the diagnosis and management of this condition. Subjects and Method: We, retrospectively, reviewed 7 duplications in 7 patients and analyzed sex, age, clinical presentation, location, complications, diagnostic work-up, surgical methods and post-operative course. Encountered diagnostic and surgical difficulties were also reviewed in two extremely rare cases. Results: Patients’ age varied between 2 months and 10 years. All duplications were single. Six of them were intra-abdominal and one thoracoabdominal Three ADTs were asymptomatic and discovered during routine X-ray imaging. One ADT involving the cecum was mimicking appendicitis and complicated by recurrent intussusceptions. The thoracoabdominal one proved a surgical challenge as it was a completely isolated ATD. All patients underwent surgery without postoperative complications. We conclude that despite their rarity, ATDs require a high level of clinical suspicion, especially if they are presented as thoracic masses. Appropriate diagnostic investigation of the pediatric patients is always necessary to avoid delay in diagnosis.

关键词： Alimentary Tract Duplication Infants Children

Current Trends in the Management of Inguinal Hernia in Children

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International Journal of Clinical Medicine 2014年第13期5卷 770-777页

作者： nick zavras Alexia Christou Evangelos Misiakos Christos Salakos Anestis Charalampopoulos Dimitrios Schizas Anastasios Machairas Department of Pediatric Surgery ATTIKO University Hospital Athens Greece Department of Pediatric Surgery General Hospital St. Panteleimon Nikaia-Peiraius Greece Third Department of Surgery ATTIKO University Hospital Athens Greece

Inguinal hernia repairs in one of the most common surgical procedures in the pediatric population. Its diagnosis is made easily and the repair is usually performed by open surgery and with low complications rates. However, a substantial number of topics concerning anesthetic management, the precise time of operation especially in premature and high-risk infants, and the need of contralateral exploration have not yet been resolved. Recently, the introduction of laparoscopic repair seems to play a significant role regarding the safety, the examination and possible simultaneously repair of the contralateral groin, and the better cosmetic results. In this review, the current trends of the above mentioned topics will be discussed.

关键词： Inguinal Hernia Children Management

History of the infantile hepatic hemangioma:From imaging to generating a differential diagnosis

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World Journal of Clinical Pediatrics 2016年第3期5卷 273-280页

作者： Maria Gnarra Gerald Behr Alison Kitajewski June K Wu Sudha A Anupindi Carrie J Shawber nick zavras Dimitrios Schizas Chris Salakos Konstantinos P Economopoulos Vascular Biology Program Department of SurgeryBoston Children's Hospital and Harvard Medical School Department of Radiology Columbia University Medical Center Department of Surgery Columbia University Medical Center Department of Radiology the Children's Hospital of PhiladelphiaUniversity of Pennsylvania Perelman School of Medicine Department of OB/GYN Columbia University Medical Center Department of Pediatric Surgical "ATTIKO" General University Hospital Society of Junior Doctors Surgery Working Group Department of Surgery Massachusetts General HospitalHarvard Medical School

We aim to provide an up-to-date summary of infantile hepatic hemangioma(IHH) and its misnomers and to dialectically present the differential diagnosis of these rare entities of the *** peer-reviewed articles on hepatic infantile hemangiomas,published between 2000 and 2015,were reviewed for this *** is the most common hepatic vascular tumor in *** a liver mass is identified in an infant,the differential diagnosis ranges from vascular malformations to benign and malignant tumors including mesenchymal hamartoma,hepatoblastoma,metastatic neuroblastoma,so careful physical examination,imaging studies,and,if indicated,tumor markers and biopsy,are of pivotal importance to ascertain the correct *** the benign nature of IHHs,some of these lesions may demand medical and/or surgical intervention,especially for multiple and diffuse *** can include hepatomegaly,hypothyroidism and cardiac ***,a close follow-up is required until complete involution of the *** propose an algorithm to guide the physicians towards the proper management of hepatic lesions.

关键词： Hepatic hemangiomas Infant Children Vascular tumors

ATC simulation for flight training:The missing link

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International Journal of Modeling, Simulation, and Scientific Computing 2017年第4期8卷 1-9页

作者： nick Papadopoli Engineering CPL Montreal QuebecCanada Nick.Papadopoli@***

This paper presents the state of piloted flight simulation fidelity with a focus on the missing link needed to complete the flight simulation experience,namely the simulated ATC environment(SATCE).To date,there has been a great deal of effort invested in providing the highest level of flight realism ***,little investment has gone into systems which are used to improve communication skills with ATC while in a populated active *** is important to note that the relatively few SATCEs is not due to the lack of technology,since such products have been available for about a *** primary reason for its absence is the inability and unwillingness for operators to justify the investment in such a training *** the meantime,the aviation industry has recognized that pilots need to have better communication skills while operating in various *** ICAO,with help from ARINC Industry Activities/FSEMC,has already taken steps to recommend the inclusion of SATCE characteristics in flight simulation *** aviation and research communities need to assist efforts by producing the necessary studies and metrics which can be used to evaluate and validate SATCEs used in the flight training.

关键词： Simulated air traffic control environment SATCE ATC communications artificial intelligent controllers flight training

Understanding the need for pre-injection from permeability measurements: What is the connection?

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Journal of Rock Mechanics and Geotechnical Engineering 2019年第3期11卷 576-597页

作者： nick Barton Eda Quadros nick Barton & Associates OsloNorway BGTech Soil and Rock Engineering Ltd. Sao PauloBrazil

Pre-grouting ahead of tunnels has three main functions:to control water inflow into the tunnel,to limit groundwater drawdown above the tunnel,and to make tunnelling progress more predictable since rock mass quality is effectively *** helps to avoid settlement damage caused by consolidation of clay deposits beneath built-up areas,since towns tend to be built where terrain is more flat,due to the clay *** are so many instances of settlement damage that the profession needs to take note of the need for high-pressure pre-grouting,to use micro-cements and micro-silica *** use of highpressure injection may cause joint jacking,but this is local in extent when the rapid pressure decay away from an injection hole is *** effect is variable and depends on the geometrical parameters of the *** pressure-decay advantage must not be violated by maintaining high pressure when grout flow from the injection hole has *** latter can cause damage to the grouting already *** methods of estimating mean hydraulic apertures(e)from Lugeon testing are described,and from more sophisticated three-dimensional(3D)permeability *** estimation of the larger mean physical joint apertures(E)is based on the joint roughness coefficient(JRC).Comparison is then made with the empirical aperture-particle size criterion E>4d95,where d95 represents almost the largest cement particle *** on joint set orientations and on the available micro-cements,the decision must be made of which range of pre-injection pressure should be aimed for,using successive reductions of the water-cement ratio w/*** simple estimation of permeability,also with depth dependence,can be made with the empirical link between a modified rock mass quality Q and permeability,which is termed *** value of this parameter can be based on core-logging or intunnel face *** 3D before-and-after-grouting permeability measurements have been use

关键词： Pre-grouting Micro-cement Hydraulic apertures Physical joint apertures Joint roughness Particle size Anisotropic permeability

Mixed reality emergency management:bringing virtual evacuation simulations into real-world built environments

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International Journal of Digital Earth 2019年第2期12卷 190-208页

作者： Ian Lochhead nick Hedley Department of Geography Simon Fraser UniversityBurnabyCanada

Computer-based evacuation simulations are important tools for emergency *** simulations vary in complexity and include 2D and 3D GIS-based network analyses,agent-based models,and sophisticated models built on documented human behaviour and particle *** the influential role of built environments in determining human movement,a disconnect often exists between the features of the real world and the way they are represented within these simulation *** proliferation of emergency management location-aware mobile devices,along with a recent infatuation for augmented reality(AR),has resulted in new wayfinding and hazard assessment tools that bridge this gap,allowing users to visualize geospatial information superimposed on the real *** this paper,we report research and development that has produced AR geovisual analytical systems,enabling visual analysis of human dynamics in multilevel built environments with complex thoroughfare network *** demonstrate prototypes that show how mixed reality visual analysis of intelligent human movement simulations built in virtual spaces can become part of real *** research introduces a fundamentally new way to view and link simulations of people with the real-world context of the built environment:mixed reality crowd simulation in real space.

关键词： Augmented reality 3D geovisualization situated simulation human movement analysis emergency management

Risk of shear failure and extensional failure around over-stressed excavations in brittle rock

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Journal of Rock Mechanics and Geotechnical Engineering 2017年第2期9卷 210-225页

作者： nick Barton Baotang Shen nick Barton&Associates OsloNorway CSIRO Energy BrisbaneAustralia

The authors investigate the failure modes surrounding over-stressed tunnels in *** lines of investigation are employed:failure in over-stressed three-dimensional(3D) models of tunnels bored under 3D stress,failure modes in two-dimensional(2D) numerical simulations of 1000 m and 2000 m deep tunnels using FRACOD,both in intact rock and in rock masses with one or two joint sets,and finally,observations in TBM(tunnel boring machine) tunnels in hard and medium hard massive *** reason for 'stress-induced' failure to initiate,when the assumed maximum tangential stress is approximately(0.4-0.5)σ_c(UCS,uniaxial compressive strength) in massive rock,is now known to be due to exceedance of a critical extensional strain which is generated by a Poisson's ratio ***,because similar 'stress/strength' failure limits are found in mining,nuclear waste research excavations,and deep road tunnels in Norway,one is easily misled into thinking of compressive stress induced *** of this,the empirical SRF(stress reduction factor in the Q-system) is set to accelerate as the estimated ratio σ_(θmax)/σ_c >> *** mining,similar 'stress/strength' ratios are used to suggest depth of *** reality behind the fracture initiation stress/strength ratio of '0.4' is actually because of combinations of familiar tensile and compressive strength ratios(such as 10) with Poisson's ratio(say0.25).We exceed the extensional strain limits and start to see acoustic emission(AE) when tangential stress σθ ≈ 0.4σc,due to simple *** combination of 2D theoretical FRACOD models and actual tunnelling suggests frequent initiation of failure by 'stable' extensional strain fracturing,but propagation in 'unstable' and therefore dynamic *** the case of very deep tunnels(and 3D physical simulations),compressive stresses may be too high for extensional strain fracturing,and shearing will dominate,both ahead of the face and following the *** shallower,the conc

关键词： Fracture propagation Tension Shear Poisson’s ratio Break-out Rock burst Deep tunnels FRACOD model

Computational fluid dynamics simulation of Hyperloop pod predicting laminar–turbulent transition

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Railway Engineering Science 2020年第1期28卷 97-111页

作者： Nathalie nick Yohei Sato Department of Mechanical and Process Engineering Swiss Federal Institute of TechnologyETH ZurichLEO B 9.1Leonhardstrasse 278092 ZurichSwitzerland Nuclear Energy and Safety Research Division Paul Scherrer InstituteForschungsstrasse 1115232 Villigen PSISwitzerland

Three-dimensional compressible flow simulationswere conducted to develop a Hyperloop pod. Thenovelty is the usage of Gamma transition model, in whichthe transition from laminar to turbulent flow can be ***, a mesh dependency study was undertaken,showing second-order convergence with respect to themesh refinement. Second, an aerodynamic analysis for twodesigns, short and optimized, was conducted with thetraveling speed 125 m/s at the system pressure 0.15 *** concept of the short model was to delay the transitionto decrease the frictional drag;meanwhile that of theoptimized design was to minimize the pressure drag bydecreasing the frontal area and introduce the transitionmore toward the front of the pod. The computed resultsshow that the transition of the short model occurred moreon the rear side due to the pod shape, which resulted in 8%smaller frictional drag coefficient than that for the optimizedmodel. The pressure drag for the optimized designwas 24% smaller than that for the short design, half ofwhich is due to the decrease in the frontal area, and theother half is due to the smoothed rear-end shape. The totaldrag for the optimized model was 14% smaller than that forthe short model. Finally, the influence of the systempressure was investigated. As the system pressure and theReynolds number increase, the frictional drag coefficientincreases, and the transition point moves toward the front,which are the typical phenomena observed in the transitionregime.

关键词： Computational fluid dynamics(CFD) Drag Subsonic compressible flow Hyperloop Laminar-turbulent transition