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Collaborating remotely:an evaluation of immersive capabilities on spatial experiences and team membership

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International Journal of Digital Earth 2018年第4期11卷 420-436页

作者： Danielle Oprean mark Simpson alexander Klippel Department of Architecture The Pennsylvania State UniversityUniversity ParkPAUSA Department of Geography The Pennsylvania State UniversityUniversity ParkPAUSA

Today’s workforce environments are steadily becoming more distributed across the globe,calling for improved ways of facilitating collaborations at a distance,including geo-collaborations or collaborations at critical *** technology is allowing distributed teams to move away from traditional conference rooms,taking collaborations into the field and giving remote teams more information about the *** idea of situating a remote collaborator’s experiences in the field,virtually,promises to enhance the understanding of geographically remote *** technologies in virtual reality(VR)hold promise for providing mobile spatial experiences in real-time,without being tied to fixed hardware,such as systems in conference *** exploratory study using VR technology on remote user experiences in a collaboration was conducted to identify the added value for remote *** findings suggest immersive capabilities improve feelings of presence in the remote locations and perceptions of being in the remote location increase feelings of team membership.

关键词： Presence geo-collaboration virtual reality

Deep cover bleeder entry performance and support loading: A case study

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International Journal of Mining Science and Technology 2018年第1期28卷 85-93页

作者： Ted M.Klemetti mark alexander Van Dyke Ihsan Berk Tulu Ground Control Branch NIOSHPittsburgh Mining Research Division Mining Engineering Department West Virginia University

Several questions have emerged in relation to deep cover bleeder entry performance and support loading:how well do current modeling procedures calculate the rear abutment extent and loading? Does an improved understanding of the rear abutment extent warrant a change in standing support in bleeder entries? To help answer these questions and to determine the current utilization of standing support in bleeder entries, four bleeder entries at varying distances from the startup room were instrumented,observed, and numerically *** paper details observations made by NIOSH researchers in the bleeder entries of a deep cover longwall panel—specifically data collected from instrumented pumpable cribs, observations of the conditions of the entries, and numerical modeling of the bleeder entries during longwall *** primary focus was on the extent and magnitude of the abutment loading experienced by the standing *** expected, the instrumentation of the standing supports showed very little loading relative to the capacity of the standing supports—less than 23 Mg load and 2.54 cm *** Flac3D program was used to evaluate these four bleeder entries using previously defined modeling and input parameter estimation *** results indicated only a minor increase in load during the extraction of the longwall *** model showed a much greater increase in stress due to the development of the gateroad and bleeder entries, with about 80% of the increase associated with development and 20% with longwall *** Flac3D model showed very good correlation between expected gateroad loading during panel extraction and that expected based on previous *** results of this study showed that the rear abutment stress experienced by this bleeder entry design was *** farther away from the startup room, the lower the applied load and smaller the convergence in the entry if all else is held ***, the numerical modeling method

关键词： Bleeder entry Standing supports Abutment loading Longwall mining Full extraction

Three-dimensional steep wave impact on a vertical cylinder

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Journal of Hydrodynamics 2016年第4期28卷 523-533页

作者： Ioannis K.CHATJIGEORGIOU alexander A.KOROBKIN mark J.COOKER School of Mathematics University of East Anglia School of Naval Architecture and Marine Engineering National Technical University of Athens

In the present study we investigate the 3-D hydrodynamic slamming problem on a vertical cylinder due to the impact of a steep wave that is moving with a steady *** linear theory of the velocity potential is employed by assuming inviscid,incompressible fluid and irrotational *** the problem is set in 3-D space,the employment of the Wagner condition is *** set of equations we pose,is presented as a mixed boundary value problem for Laplace＇s equation in *** from the mixedtype of boundary conditions,the problem is complicated by considering that the region of wetted surface of the cylinder is a set whose boundary depends on the vertical coordinate on the cylinder up to the *** make some simple assumptions at the start but otherwise we proceed *** find closed-form relations for the hydrodynamic variables,namely the time dependent potential,the pressure impulse,the shape of the wave front（from the contact point to beyond the cylinder） and the slamming force.

关键词： cylinder hydrodynamic incompressible steep Wagner employment otherwise coordinate analytically assumptions

A bioactive compliant vascular graft modulates macrophage polarization and maintains patency with robust vascular remodeling

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Bioactive Materials 2023年第1期19卷 167-178页

作者： alexander Stahl Dake Hao Janos Barrera Dominic henn Sien Lin Seyedsina Moeinzadeh Sungwoo Kim William Maloney Geoffrey Gurtner Aijun Wang Yunzhi Peter Yang Department of Orthopaedic Surgery Stanford University240 Pasteur DriveStanfordCA94304USA Department of Chemistry Stanford University121 Mudd BuildingStanfordCA94305USA Department of Surgery School of MedicineUniversity of California DavisSacramentoCA95817USA Institute for Pediatric Regenerative Medicine Shriners Hospitals for ChildrenSacramentoCA95817USA Department of Surgery Stanford University300 Pasteur DriveStanfordCA94305USA Department of Biomedical Engineering University of California DavisDavisCA95616USA Department of Materials Science and Engineering Stanford University496 Lomita MallStanfordCA94305USA Department of Bioengineering Stanford University443 Via OrtegaStanfordCA4305USA

Conventional synthetic vascular grafts are associated with significant failure rates due to their mismatched mechanical properties with the native vessel and poor regenerative *** different tissue engineering approaches have been used to improve the biocompatibility of synthetic vascular grafts,it is still crucial to develop a new generation of synthetic grafts that can match the dynamics of native vessel and direct the host response to achieve robust vascular *** size of pores within implanted biomaterials has shown significant effects on macrophage polarization,which has been further confirmed as necessary for efficient vascular formation and ***,we developed biodegradable,autoclavable synthetic vascular grafts from a new polyurethane elastomer and tailored the grafts’interconnected pore sizes to promote macrophage populations with a pro-regenerative phenotype and improve vascular regeneration and patency *** synthetic vascular grafts showed similar mechanical properties to native blood vessels,encouraged macrophage populations with varying M2 to M1 phenotypic expression,and maintained patency and vascular regeneration in a one-month rat carotid interposition model and in a four-month rat aortic interposition *** innovative bioactive synthetic vascular graft holds promise to treat clinical vascular diseases.

关键词： Vascular graft Vascular compliance Pore size Macrophage polarization Vascular remodeling

Isolation of Single-Walled Carbon Nanotube Enantiomers by Density Differentiation

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Nano Research 2009年第1期2卷 69-77页

作者： alexander A.Green Matthew C.Duch mark C.Hersam Department of Materials Science and Engineering and Department of Chemistry Northwestern UniversityEvanstonIllinois 60208-3108USA

Current methods of synthesizing single-walled carbon nanotubes(SWNTs)result in racemic mixtures that have impeded the study of left-and right-handed *** we present a method of isolating different SWNT enantiomers using density gradient *** separation is enabled by the chiral surfactant sodium cholate,which discriminates between left-and right-handed SWNTs and thus induces subtle differences in their buoyant *** sorting strategy can be employed for simultaneous enrichment by handedness and roll-up vector of SWNTs having diameters ranging from 0.7 to 1.5 *** addition,circular dichroism of enantiomer refined samples enables identification of high-energy optical transitions in SWNTs.

关键词： Carbon nanotube separation handedness enantiomer optical activity chirality

Evolution of laparoscopy in colorectal surgery:An evidencebased review

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World Journal of Gastroenterology 2014年第17期20卷 4926-4933页

作者： alexander Emmanuel Blackmore mark Te Ching Wong Choong Leong Tang Department of Colorectal Surgery Singapore General HospitalSingapore 169856Singapore

Open surgery for colorectal disease has progressed significantly over the past century from humble beginnings to form the mainstay of treatment for colorectal cancer and a number of benign *** the introduction of laparoscopic abdominal surgery,the next stage in the evolution of the specialty began in the 1990s with the first laparoscopic colonic *** some early concerns regarding its safety and oncological efficacy during the latter part of that decade,laparoscopic colorectal surgery rapidly came into mainstream use in the early part of the current century with evidence supporting its use being made available from large scale randomised controlled *** article provides an evidence-based summary of this evolutionary process as it relates to both benign and malignant colorectal disease,as well as discussion of the next phase of new technologies such as robotic surgery.

关键词： Colorectal surgery Colorectal cancer Pelvic floor Laparoscopy Robotics Laparoscopic resection of gastrointestinal

Effects of historic wildfire and prescribed fire on site occupancy of bats in Shenandoah National Park,Virginia,USA

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Journal of Forestry Research 2020年第4期31卷 1255-1270页

作者： Lauren V.Austin alexander Silvis W.mark Ford Karen E.Powers Department of Fish and Wildlife Conservation Virginia TechBlacksburgVA 24061USA Resource Environmental Solutions WarrentonVA 20187USA U.S.Geological Survey Virginia Cooperative Fish and Wildlife Research UnitBlacksburgVA 24061USA Biology Department Radford UniversityRadfordVA 24141USA

Given the likelihood of regional extirpation of several once-common bat species in eastern North America from white-nose syndrome,it is critical that the impacts of forest management activities,such as prescribed fire,are known in order to minimize potentially additive negative effects on bat *** wildfires may offer a suitable surrogate to assess long-term burn impacts on bats for planning,implementing and assessing burn *** examine the effects of historic fire on bats,we sampled bat activities at 24 transect locations in burned and unburned forest stands in the central Appalachian Mountains of Shenandoah National Park(SNP),Virginia,*** was limited evidence of positive fire effects over time on hoary bats(Lasiurus cinereus Beauvois)and big brown bats(Eptesicus fuscus Beauvois)***,there were few or mostly equivocal relationships of bat occupancy relative to burn conditions or time since fire in SNP across species using a false-positive occupancy *** results suggest that fire does not strongly affect bat site occupancy short-or long-term in the central Appalachians.

关键词： Appalachian mountains Bats False-positive occupancy Prescribed fire Wildfire

Improved thromboresistance and analytical performance of intravascular amperometric glucose sensors using optimized nitric oxide release coatings

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Chinese Chemical Letters 2015年第4期26卷 464-468页

作者： alexander K.Wolf Yu Qin Terry C.Major mark E.Meyerhoff Department of Chemistry University of Michigan Department of Chemistry Nanjing University Department of Surgery University of Michigan

In this work, nitric oxide （NO） release coatings designed for intravenous amperometric glucose sensors are optimized through the use ofa polylactic acid （PLA） layer doped with a lipophilic diazeniumdiolated species that releases NO through a proton-driven mechanism. An Elast-Eon E2As polyurethane coating is used to both moderate NO release from the sensor surface and increase the sensor＇s linear detection range toward glucose. These sensors were evaluated for thromboresistance and in vivo glucose performance through implantation in rabbit veins. By maintaining NO flux on a similar scale to endogenous endothelial cells, implanted glucose sensors exhibited reduced surface clot formation which enables more accurate quantitative glucose measurements continuously. An in vivo time trace of implanted venous sensors demonstrated glucose values that correlated well with the discrete measurements of blood samples on a benchtop point-of-care sensor-based instrument. The raw measured currents from the implanted glucose sensors over 7 h time periods were converted to glucose concentration through use of both a one-point in vivo calibration and a calibration curve obtained in vitro within a bovine serum solution. Control sensors, assembled without NO release functionality, exhibit distinctive surface clotting over the 7 h in vivo implantation period.

关键词： Nitric oxide release coatingsGlucose sensorsPolylactic acid layerQuantitative glucose measurements

Importance of charge self-consistency in first-principles description of strongly correlated systems

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npj Computational Materials 2021年第1期7卷 1949-1956页

作者： Swagata Acharya Dimitar Pashov alexander N.Rudenk Malte Rösner mark van Schilfgaarde Mikhail I.Katsnelson Institute for Molecules and Materials Radboud UniversityNijmegen 6525 AJThe Netherlands Theory and Simulation of Condensed Matter King's College LondonThe StrandLondon WC2R2LSUK National Renewable Energy Laboratory Golden80401 ColoradoUSA

First-principles approaches have been successful in solving many-body Hamiltonians for real materials to an extent when correlations are weak or *** the electronic correlations become stronger often embedding methods based on first-principles approaches are used to better treat the correlations by solving a suitably chosen many-body Hamiltonian with a higher level *** success of such embedding theories,often referred to as second-principles,is commonly measured by the quality of self-energy E which is either a function of energy or momentum or ***,E should,in principle,also modify the electronic eigenfunctions and thus change the real space charge *** such practices are not prevalent,some works that use embedding techniques do take into account these *** such cases,choice of partitioning,of the parameters defining the correlated Hamiltonian,of double-counting corrections,and the adequacy of low-level Hamiltonian hosting the correlated subspace hinder a systematic and unambiguous understanding of such ***,for a large variety of correlated systems,strong correlations are largely confined to the charge *** an adequate non local low-order theory is important,and the high-order local correlations embedding contributes become *** we study the impact of charge self-consistency within two example cases,TiSez and CrBrs,and show how real space charge re-distribution due to correlation effects taken *** within a first-principles Green's function-based many-body perturbative approach is key in driving qualitative changes to the final electronic structure of these materials.

关键词： theory charge principles