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Wavefront-optimized surface retreatments of refractive error following previous laser refractive surgery: a retrospective study

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Eye and Vision 2016年第1期3卷 22-28页

作者： Kevin M.Broderick Rose K Sia Denise S.Ryan Richard D.Stutzman Michael J.Mines Travis C.frazier mark f.torres Kraig S.Bower Ophthalmology Service Walter Reed National Military Medical Center8901 Wisconsin AvenueBethesdaMD 20814USA Warfighter Refractive Eye Surgery Program and Research Center Ft.BelvoirVAUSA Ophthalmology Service Madigan Army Medical CenterTacomaWAUSA The Wilmer Eye Institute Johns Hopkins UniversityBaltimoreMDUSA

Background:Retreatments are sometimes necessary to correct residual or induced refractive errors following refractive *** different combinations of primary treatment methods and retreatment techniques have been studied,however,few studies have investigated wavefront-optimized(WfO)technology for retreatment following primary refractive *** study aimed to report the outcomes of WfO photorefractive keratectomy(PRK)retreatments of refractive error following previous laser refractive surgery with PRK,laser in situ keratomileusis(LASIK),or laser-assisted subepithelial keratectomy(LASEK).Methods:We reviewed records of patients who underwent WfO PRK retreatments using the Allegretto Wave Eye-Q 400 Hz Excimer Laser System(Alcon Surgical)between January 2008 and April 2011 at Walter Reed Army Medical Center and Madigan Army Medical *** were recorded in terms of uncorrected distance visual acuity(UDVA),manifest refraction spherical equivalent(MRSE),corrected distance visual acuity(CDVA),and complications at 1 month(M),3 M,and 6 M ***:Seventy-eight patients(120 eyes)underwent WfO PRK retreatment during the study *** surgery was surface ablation in 87 eyes(78 PRK,9 LASEK)and LASIK in 33 *** mean spherical equivalent before retreatment was−0.79±0.94 D(−3.00 to 1.88 D).UDVA was≥20/20 in 69 eyes(60.0%)at 1 M,54 eyes(71.1%)at 3 M,and 27 eyes(73.0%)at 6 M *** was within±0.50 D of emmetropia in 78 eyes(67.8%)at 1 M,59 eyes(77.6%)at 3 M,and 25 eyes(67.6%)at 6 M *** was maintained within±1 line of pre-op in 113 of 115 eyes(98.3%)at 1 M,74 of 76 eyes(97.4%)at 3 M,and 37 eyes(100%)at 6 M ***:Although follow-up was limited beyond 3 M,WfO PRK retreatments in patients with residual refractive error may be a safe and effective *** studies are necessary to determine the long-term safety and stability of outcomes.

关键词： Wavefront-optimized PRK LASIK LASEK Retreatment Enhancement

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Modification Design Method for an Enveloping Hourglass Worm Gear with Consideration of Machining and Misalignment Errors

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Chinese Journal of Mechanical Engineering 2013年第5期26卷 948-956页

作者： DENG Xingqiao WANG Jinge HORSTEMEYER mark f School of Mechanical Engineering and Automation Xihua University Center for Advanced Vehicular Systems Mississippi State University

The influences of machining and misalignment errors play a very critical role in the performance of the anti-backlash double-roller enveloping hourglass worm gear(ADEHWG).However,a corresponding efficient method for eliminating or reducing these errors on the tooth profile of the ADEHWG is seldom *** gear engagement equation and tooth profile equation for considering six different errors that could arise from the machining and gear misalignment are derived from the theories of differential geometry and gear ***,the tooth contact analysis(TCA) is used to systematically investigate the influence of the machining and misalignment errors on the contact curves and the tooth profile by means of numerical analysis and three-dimensional solid *** research results show that vertical angular misalignment of the worm wheel(Δβ) has the strongest influences while the tooth angle error(Δα) has the weakest influences on the contact curves and the tooth profile.A novel efficient approach is proposed and used to minimize the effect of the errors in manufacturing by changing the radius of the grinding wheel and the approaching point of *** results from the TCA and the experiment demonstrate that this tooth profile design modification method can indeed reduce the machining and misalignment *** modification design method is helpful in understanding the manufacturing technology of the ADEHWG.

关键词： worm gears tooth contact analysis machining and misalignment errors tooth profile errors modification method

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Runout of submarine landslide simulated with material point method

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Journal of Hydrodynamics 2017年第3期29卷 438-444页

作者： Youkou Dong Dong Wang mark f.Randolph Centre for Offshore foundation Systems the University of Western Australia Shandong Provincial Key Laboratory of Marine Environment and Geological Engineering Ocean University of China

Most of the present knowledge on submarine landslides relies upon back-analysis of post-failure deposits identified using geophysical *** this paper,the runout of slides on rigid bases is explored using the material point method（MPM）with focus on the geotechnical aspects of the *** MPM,the sliding material and bases are discretised into a number of Lagrangian particles,and a background Eulerian mesh is employed to update the state of the *** morphologies of the slide can be reproduced by tracking the Lagrangian particles in the dynamic processes.A real case history of a submarine slide is back-analyzed with the MPM and also a depth-averaged *** of the slides from steep slopes to moderate bases are *** different combinations of soil and basal parameters are assumed to trigger runout mechanisms of elongation,block sliding and *** runout distances predicted by the MPM match well with those from large deformation finite element analysis for the elongation and block sliding *** and grabens are shaped in a spreading ***,the current MPM simulations for materials with high sensitivities are relatively mesh sensitive.

关键词： Submarine landslide runout morphology material point method large deformation

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Telomeres:Linking stress and survival,ecology and evolution

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Current Zoology 2010年第6期56卷 714-727页

作者： mark f.HAUSSMANN Nicole M.MARCHETTO Department of Biology Bucknell University

Telomeres are protective structures at the ends of eukaryotic chromosomes. The loss of telomeres through cell division and oxidative stress is related to cellular aging, organismal growth and disease. In this way, telomeres link molecular and cellular mechanisms with organismal processes, and may explain variation in a number of important life-history traits. Here, we discuss how telomere biology relates to the study of physiological ecology and life history evolution. We emphasize current knowledge on how telomeres may relate to growth, survival and lifespan in natural populations. We finish by examining interest- ing new connections between telomeres and the glucocorticoid stress response. Glucocorticoids are often employed as indices of physiological condition, and there is evidence that the glucocorticoid stress response is adaptive. We suggest that one way that glucocorticoids impact organismal survival is through elevated oxidative stress and telomere loss. future work needs to establish and explore the link between the glucocorticoid stress response and telomere shortening in natural populations. If a link is found, it provides an explanatory mechanism by which environmental perturbation impacts life history trajectories [Current Zoology 56 （6）： 714-727, 2010].

关键词： Corticosterone Stress Survival Telomeres

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Impact of hypothermia on the biomechanical effect of epithelium-off corneal cross-linking

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Eye and Vision 2021年第3期8卷 31-35页

作者： Hormoz Abdshahzadeh Reyhaneh Abrishamchi Emilio A.torres-Netto Sabine Kling Nikki L.Hafezi mark Hillen farhad Hafezi Ocular Cell Biology Group Center for Applied Biotechnology and Molecular MedicineUniversity of ZurichWinterthurerstrasse 1908057 ZurichSwitzerland ELZA Institute Dietikon/ZurichSwitzerland Department of Ophthalmology Paulista School of MedicineFederal University of Sao PauloSao PauloBrazil faculty of Medicine University of GenevaGenevaSwitzerland OPTIC-team Computer Vision LaboratoryETH ZurichZurichSwitzerland Department of Ophthalmology University of WenzhouWenzhouChina USC Roski Eye Institute USC Los AngelesLos AngelesCAUSA

Background:The corneal cross-linking(CXL)photochemical reaction is essentially dependent on oxygen and hypothermia,which usually leads to higher dissolved oxygen levels in tissues,with potentially greater oxygen availability for ***,we evaluate whether a reduction of corneal temperature during CXL may increase oxygen availability and therefore enhance the CXL biomechanical stiffening effect in ex vivo porcine ***:One hundred and twelve porcine corneas had their epithelium manually debrided before being soaked with 0.1%hypo-osmolaric *** corneas were equally assigned to one of four *** 2 and 4 underwent accelerated epithelium-off CXL using 9 mW/cm^(2) irradiance for 10 min,performed either in a cold room temperature(group 2,4℃)or at standard room temperature(group 4,24℃).Groups 1 and 3 served as non-crosslinked,temperature-matched *** a stress-strain extensometer,the elastic moduli of 5-mm wide corneal strips were analyzed as an indicator of corneal ***:Accelerated epithelium-off CXL led to significant increases in the elastic modulus between 1 and 5%of strain when compared to non-cross-linked controls(Pficant difference was found between control groups(P=0.846)or between groups in which CXL was performed at low or standard room temperature(P=0.969).Conclusions:Although initial oxygen availability should be increased under hypothermic conditions,it does not appear to play a significant role in the biomechanical strengthening effect of epithelium-off CXL accelerated protocols in ex vivo porcine corneas.

关键词： Corneal cross-linking CXL Keratoconus Temperature Oxygen diffusion Hypothermia

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Quantification of ventilation enhancement using the Eye CAN roof support

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International Journal of Mining Science and Technology 2017年第1期27卷 153-158页

作者： Shook Michael T Sindelar mark f, Jiang Hua Luo Yi Burrell Mining Products Inc.New KensingtonPA 15068USA Department of Mining Engineering West Virginia UniversityMorgantownWV 26506USA

Convergence of roof and floor in underground mine openings is a common occurrence. This convergence not only adversely affects the ability of workers, equipment and supplies to travel through the mine, it also reduces the effectiveness of the mine ventilation system, which is essential for the dilution of methane gas and airborne respirable dust. While installing secondary standing supports to control floor and roof convergence, such supports, by nature, partially obstruct a portion of the airway. These added obstructions inhibit the ability of the ventilation system to operate as efficiently as it could by increasing the resistance in and reducing the cross-sectional area of the airway. This study introduces and demonstrates the benefits of The Eye CAN^(TM) standing roof support, which controls floor and roof convergence and is less obstructive to air flow than conventional wooden cribs. Laboratory findings show that the normal resistance of a supported lined airway is reduced by using this new product from Burrell Mining Products, Inc., while providing the same roof support characteristics of an established product—The CANò. Load vs. displacement curves generated from laboratory tests demonstrated that this new product behaves with the same roof support characteristics as others in The CAN product family. Ventilation data gathered from a simulated mine entry was then used for computational fluid dynamics(CfD) *** CfD analysis showed an improvement with The Eye CAN vs. other accepted forms of standing roof support. This proof-of-concept study suggests that, when using this new product made by Burrell Mining Products, Inc., not only will the convergence from the roof and floor be controlled, but airway resistance will also be reduced.

关键词： Standing roof support CAN Ventilation Load-displacement Eye CAN

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Compressive and cyclic flexural response of double-hooked-end steel fiber reinforced concrete

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frontiers of Structural and Civil Engineering 2022年第9期16卷 1104-1126页

作者： Demewoz W.MENNA Aikaterini S.GENIKOMSOU mark f.GREEN Department of Civil Engineering Queen’s UniversityKingstonON K7L 3N6Canada

Recent developments on high-performance double-hooked-end steel fibers have enhanced the wide applications of steel fiber reinforced concrete(SfRC).This study presents the compressive properties and the cyclic flexural performance of the SfRC that were experimentally *** different double-hooked-end steel fibers at 0.25%,0.5%,0.75%,and 1%volume fractions were *** fiber types had similar length to diameter ratios,while the first two fiber types had similar anchorage mechanisms(4D)and tensile strength and the third type had different anchorage mechanism(5D)and a higher tensile *** increased volumetric ratio of the fibers increased the post-peak compressive strain(ductility),the tensile strength,and the cyclic flexural strength and cumulative energy dissipation characteristics of the *** the 4D fibers,the mixtures with the larger steel fibers showed higher flexural strength and more energy dissipation compared to the SfRCs with smaller size *** 1%steel fiber dosage,4D and 5D specimens showed similar cyclic flexural ***,a 3D finite element model that can predict the monotonic and cyclic flexural responses of the double-hooked-end SfRC was *** calibration process considered the results obtained from the inverse analysis to determine the tensile behavior of the SfRC.

关键词： steel fiber reinforced concrete fiber geometry cyclic loading energy dissipation finite element modeling inverse analysis

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Capsule endoscopy:Current practice and future directions

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World Journal of Gastroenterology 2014年第24期20卷 7752-7759页

作者： Melissa f Hale Reena Sidhu mark E McAlindon Department of Gastroenterology Royal Hallamshire HospitalSheffield S10 2JFUnited Kingdom

Capsule endoscopy (CE) has transformed investigation of the small bowel providing a non-invasive, well tolerated means of accurately visualising the distal duodenum, jejunum and ileum. Since the introduction of small bowel CE thirteen years ago a high volume of literature on indications, diagnostic yields and safety profile has been presented. Inclusion in national and international guidelines has placed small bowel capsule endoscopy at the forefront of investigation into suspected diseases of the small bowel. Most commonly, small bowel CE is used in patients with suspected bleeding or to identify evidence of active Crohn’s disease (CD) (in patients with or without a prior history of CD). Typically, CE is undertaken after upper and lower gastrointestinal flexible endoscopy has failed to identify a diagnosis. Small bowel radiology or a patency capsule test should be considered prior to CE in those at high risk of strictures (such as patients known to have CD or presenting with obstructive symptoms) to reduce the risk of capsule retention. CE also has a role in patients with coeliac disease, suspected small bowel tumours and other small bowel disorders. Since the advent of small bowel CE, dedicated oesophageal and colon capsule endoscopes have expanded the fields of application to include the investigation of upper and lower gastrointestinal disorders. Oesophageal CE may be used to diagnose oesophagitis, Barrett’s oesophagus and varices but reliability in identifying gastroduodenal pathology is unknown and it does not have biopsy capability. Colon CE provides an alternative to conventional colonoscopy for symptomatic patients, while a possible role in colorectal cancer screening is a fascinating prospect. Current research is already addressing the possibility of controlling capsule movement and developing capsules which allow tissue sampling and the administration of therapy.

关键词： Capsule endoscopy Small bowel Indications Technology Oesophageal Colon

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Effect of process parameters on the density and porosity of laser melted AlSi10Mg/SiC metal matrix composite

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frontiers of Mechanical Engineering 2018年第4期13卷 520-527页

作者： Omotoyosi H. fAMODIMU mark STANfORD Chike f. ODUOZA Lijuan ZHANG faculty of Science and Engineering School of Engineering Telford Campus University of Wolverhampton WV1 1LY Wolverhampton UK

Laser melting of aluminium alloy-AlSi10Mg has increasingly been used to create specialised products in various industrial applications, however, research on utilising laser melting of aluminium matrix composites in replacing specialised parts have been slow on the uptake. This has been attributed to the complexity of the laser melting process, metal/ceramic feedstock for the process and the reaction of the feedstock material to the laser. Thus, an understanding of the process, material microstructure and mechanical properties is important for its adoption as a manufacturing route of aluminium metal matrix composites. The effects of several parameters of the laser melting process on the mechanical blended composite were thus investigated in this research. This included single track formations of the matrix alloy and the composite alloyed with 5% and 10% respectively for their reaction to laser melting and the fabrication of density blocks to investigate the relative density and porosity over different scan speeds. The results from these experiments were utilised in determining a process window in fabricating near-fully dense parts.

关键词： selective laser melting additive manufacturing mechanical alloying powder metallurgy aluminium metal matrix composite

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Analysis of gateroad stability at two longwall mines based on field monitoring results and numerical model analysis

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International Journal of Mining Science and Technology 2019年第1期29卷 35-43页

作者： Gabriel S.Esterhuizen David f.Gearhart Ted Klemetti Heather Dougherty mark van Dyke National Institute for Occupational Safety and Health

Coal mine longwall gateroads are subject to changing loading conditions induced by the advancing longwall face. The ground response and support requirements are closely related to the magnitude and orientation of the stress changes, as well as the local geology. This paper presents the monitoring results of gateroad response and support performance at two longwall mines at a 180-m and 600-m depth of *** the first mine, a three-entry gateroad layout was used. The second mine used a four-entry, yieldabutment-yield gateroad pillar system. Local ground deformation and support response were monitored at both sites. The monitoring period started during the development stage and continued during first panel retreat and up to second panel retreat. The two data sets were used to compare the response of the entries in two very different geotechnical settings and different gateroad layouts. The monitoring results were used to validate numerical models that simulate the loading conditions and entry response for these widely differing conditions. The validated models were used to compare the load path and ground response at the two mines. This paper demonstrates the potential for numerical models to assist mine engineers in optimizing longwall layouts and gateroad support systems.

关键词： Coal mining Longwall Gateroad Support Numerical models

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