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Direct-to-indirect map.ing for op.imal low-thrust trajectories

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Astrodynamics 2024年第1期8卷 27-46页

作者： david Ottesen Ryan p.Russell Dep.rtment of Aerosp.ce Engineering and Engineering Mechanics The University of Texas at AustinAustinTexas78712USA

Op.imal,many-revolution sp.cecraft trajectories are challenging to solve.A connection is made for a class of models between op.imal direct and indirect *** transfers that minimize thrust-acceleration-squared,p.imer vector theory map. direct,many-imp.lsive-maneuver trajectories to the indirect,continuous-thrust-acceleration *** map.ing algorithm is indep.ndent of how the direct solution is obtained and requires only a solver for a boundary value p.oblem and its p.rtial derivatives.A Lambert solver is used for the two-body p.oblem in this *** map.ing is simp.e because the imp.lsive maneuvers and co-states share the same linear sp.ce around an op.imal *** numerical results,the direct coast-imp.lse solutions are demonstrated to converge to the indirect continuous solutions as the number of imp.lses and segments *** two-body design sp.ce is exp.ored with a set of three many-revolution,many-segment examp.es changing semimajor axis,eccentricity,and *** first two examp.es involve a small change to either semimajor axis or eccentricity,and the third examp.e is a transfer to geosynchronous *** a single p.ocessor,the op.imization runtime is seconds to minutes for revolution counts of 10 to 100,and on the order of one hour for examp.es with up.to 500 *** of these thrust-acceleration-squared solutions are good candidates to start a homotop. to a higher-fidelity minimization p.oblem with p.actical constraints.

关键词： direct op.imization indirect op.imization imp.lsive maneuvers Lambert's p.oblem two-body dynamics p.imer vectortheory

The great catastrop.e: causes of the p.rmo-Triassic marine mass extinction

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National Science Review 2024年第1期11卷 37-50页

作者： p.ul B.Wignall david p.G.Bond School of Earth & Environment University of Leeds School of Environmental Sciences University of Hull

The marine losses during the p.rmo-Triassic mass extinction were the worst ever exp.rienced. All group. were badly affected, esp.cially amongst the benthos(e.g. brachiop.ds, corals, bryozoans, foraminifers,ostracods). p.anktonic p.p.lations underwent a fundamental change with eukaryotic algae being rep.aced by nitrogen-fixing bacteria, green-sulp.ur bacteria, sulp.ate-reducing bacteria and p.asinop.ytes. Detailed studies of boundary sections, esp.cially those in South China, have resolved the crisis to a ～55 kyr interval straddling the p.rmo-Triassic boundary. Many of the losses occur at the beginning and end of this interval p.inting a p.cture of a two-p.ase extinction. Imp.oved knowledge of the extinction has been sup.orted by numerous geochemical studies that allow diverse p.op.sed extinction mechanisms to be studied. A transition from oxygenated to anoxic-euxinic conditions is seen in most sections globally, although the intensity and timing shows regional variability. Decreased ocean ventilation coincides with rap.dly rising temp.ratures and many extinction scenarios attribute the losses to both anoxia and high *** kill mechanisms include ocean acidification for which there is conflicting sup.ort from geochemical p.oxies and, even less likely, siltation(burial under a massive influx of terrigenous sediment) which lacks substantive sedimentological evidence. The ultimate driver of the catastrop.ic changes at the end of the p.rmian was likely Siberian Trap.erup.ions and their associated carbon dioxide emissions with consequences such as warming, ocean stagnation and acidification. Volcanic winter ep.sodes stemming from Siberian volcanism have also been linked to the crisis, but the short-term nature of these ep.sodes(p.d warming during the crisis makes this an unlikely cause. Finally, whilst the extinction is well studied in equatorial latitudes, a different history is found in northern Boreal latitudes

关键词： ocean anoxia ocean acidification siltation p.oductivity collap.e volcanic winter

A combined exp.rimental and DEM investigation of grain interlocking in sheared granular assemblies

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p.rticuology 2024年第7期90卷 436-451页

作者： Rui Lu Qiang Luo Tengfei Wang david p.Connolly Tao Xie School of Civil Engineering Southwest Jiaotong UniversityChengdu 610031China Key Laboratory of High-Sp.ed Railway Engineering(Southwest Jiaotong University) Ministry of EducationChengdu 610031China School of Civil Engineering University of LeedsLeeds LS29JTUK Dep.rtment of Civil Engineering McMaster UniversityHamiltonONCanada

Comp.cted granular material,integral to geotechnical engineering,undergoes translation,rotation,and interlocking when subject to shear disp.acements or external *** p.esent study focuses on the interlocking of heterogeneous granular materials,a comp.ex behavior influenced by gradation,comp.ction,and varying p.rticle geometry,and has consequently received limited attention in existing *** address this research gap.we conducted an analysis on the effect of grain interlocking on the shear resistance of granular assemblies,using a combination of laboratory testing and the discrete element method(DEM).Initially,large-scale direct shear tests were conducted on gravel−sand mixes with varying degrees of comp.ction and normal *** of the mixes also underwent subsequent shear reversal to exp.ore the differences in grain interlocking between the two shearing p.ocesses on the shear *** analyzing the laboratory results,a mesoscop.c scale investigation was p.rformed by rep.icating the test using discrete element *** facilitate this,granular p.rticle geometries were measured using 3D laser scanning based on the p.ysical lab ***,based on these scans,discrete element R-block and ball models were utilized to construct both the coarse and fine p.rticles within the *** vibro-comp.ction was emp.oyed to regulate the degree of *** results indicate that an increase in vertical p.essure,coup.ed with a zero dilatancy angle,results in a rising stress ratio,indicative of grain *** interlocking exhibits a p.sitive correlation with both the coarse content and the degree of comp.ction,and varies dep.nding on the shear *** interlocking p.ogresses,the shear band,induced by p.rticle movement,exp.nds and is associated with reduced p.rticle rotation near the shear *** study further reveals a consistent p.sitive correlation between interlocking and the p.incip.l orientation angle of strong normal c

关键词： Granular material Interlocking Shear resistance Direct shear Discrete element method Vibro-comp.ction

Evaluation of corneal p.rameter changes under different accommodative stimuli with Scheimp.lug imaging-based tomograp.y

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国际眼科杂志 2024年第9期24卷 1357-1366页

作者： Farid J Bedrán-García david p.p.ñero Dep.rtment of Op.ics Pharmacology and AnatomyUniversity of AlicanteAlicante 03690Spain

AIM:To evaluate the reliability of measurements of corneal changes with accommodation in healthy eyes using a Scheimp.lug imaging-based system and how these measurements distribute in the normal ***:p.osp.ctive,non-randomized,comp.rative study including 27 healthy subjects(54 eyes),including emmetrop.a(13 eyes),myop.a(17 eyes),hyp.rop.a(4 eyes)and astigmatism(20 eyes)*** all cases,a comp.ete eye examination was p.rformed,including the analysis of corneal changes with different accommodative stimuli(+2.00,0.00 and-3.00 D)using the p.ntacam AXL *** investigation was structured in 2 p.ases:rep.atability analysis and characterization of accommodation-related corneal changes in healthy ***:In the rep.atability analysis,the index of height asymmetry(IHA)showed the greatest variability with the three accommodative stimuli,being the results for the rest of p.rameters *** group.of emmetrop.s showed significant differences with accommodative changes in the p.sition of maximum keratometry(Kmax;p.0.05),whereas in the astigmatism group.significant changes were not only observed in the p.sition of Kmax,but also in minimum corneal thickness(MCT),corneal sp.erical aberration,and total and low order aberration root mean square(all p.0.05).Likewise,a significant difference was found in the disp.acement of the X p.sition of Kmax with+2.00 D and-3.00 D in the myop.a group.p.0.033)as well as in changes with+2.00 D and-3.00 D in the magnitude of the p.sition vector of Kmax in the emmetrop.a group.p.0.05).No significant changes were found between accommodative stimuli in the disp.acement of coordinates of MCT(p.0.109).CONCLUSION:The p.sition of Kmax and MCT in healthy corneas can change significantly when p.esenting different accommodative stimuli using the accommodation mode of the p.ntacam system,with different trends in these accommodation-related corneal changes between refractive ***,the consistency of the measurement

关键词： corneal biomechanics keratometry corneal thickness p.chymetry corneal aberrations p.ntacam accommodation

合并冠心病的糖尿病—不断进展的治疗,不断改变的目标

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中国循证心血管医学杂志 2009年第5期1卷 315-316页

作者： William E. Boden david p. taggart 徐绍鹏

糖尿病的患病率正在以惊人的速度增加,预计到2030年其患病人数将会增加一倍.现在全球有171 00万人患糖尿病,其中23 600万在美国.糖尿病微血管和大血管的并发症是众所周知的,伴随着动脉粥样硬化,使得糖尿病患者易患冠心病乃至心肌梗死和... 详细信息

糖尿病的患病率正在以惊人的速度增加,预计到2030年其患病人数将会增加一倍.现在全球有171 00万人患糖尿病,其中23 600万在美国.糖尿病微血管和大血管的并发症是众所周知的,伴随着动脉粥样硬化,使得糖尿病患者易患冠心病乃至心肌梗死和死亡的比例较一般人更高.治疗策略旨在减少这些事件的发生,现在已经包括最佳的药物治疗(生活方式干预,注意血糖控制和强化二级预防)以及介入治疗(导管和外科的再血管化治疗).

关键词：糖尿病患合并冠心病药物治疗动脉粥样硬化生活方式干预再血管化治疗患病人数心肌梗死

TRAIL and Celastrol Combinational Treatment Sup.resses p.oliferation, Migration, and Invasion of Human Glioblastoma Cells via Targeting Wnt/β-catenin Signaling p.thway

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Chinese Journal of Integrative Medicine 2024年第4期30卷 322-329页

作者： QIN Jing-jing NIU Meng-da CHA Zhe GENG Qing-hua LI Yu-lin REN Chun-guang david p.Molloy YU Hua-rong Research Center of Neuroscience School of Basic Medical SciencesChongqing Medical UniversityChongqing(400016)China Laboratory of Develop.ental Biology Department of Cell Biology and GeneticsSchool of Basic Medical SciencesChongqing Medical UniversityChongqing(400016)China Dep.rtment of Biochemistry and Molecular Biology School of Basic Medical SciencesChongqing Medical UniversityChongqing(400016)China

Objective To investigate the mechanistic basis for the anti-p.oliferation and anti-invasion effect of tumor necrosis factor-related ap.p.osis-induced ligand(TRAIL)and celastrol combination treatment(TCCT)in glioblastoma *** Cell counting kit-8 was used to detect the effects of different concentrations of celastrol(0-16µmol/L)and TRAIL(0-500 ng/mL)on the cell viability of glioblastoma cells.U87 cells were randomly divided into 4 group.,namely control,TRAIL(TRAIL 100 ng/mL),Cel(celastrol 0.5µmol/L)and TCCT(TRAIL 100 ng/mL+celastrol 0.5µmol/L).Cell p.oliferation,migration,and invasion were detected by colony formation,wound healing,and Transwell assays,*** reverse transcrip.ion p.lymerase chain reaction and Western blotting were p.rformed to assess the levels of ep.thelial-mesenchymal transition(EMT)markers(zona occludens,N-cadherin,vimentin,zinc finger E-box-binding homeobox,Slug,and β-catenin).Wnt p.thway was activated by lithium chloride(LiCl,20 mol/L)and the mechanism for action of TCCT was *** Celastrol and TRAIL synergistically inhibited the p.oliferation,migration,invasion,and EMT of U87 cells(p.0.01).TCCT up.regulated the exp.ession of GSK-3β and down-regulated the exp.ession of β-catenin and its associated p.oteins(p.0.05 or p.0.01),including c-Myc,Cyclin-D1,and matrix metallop.oteinase(MMp.-*** addition,LiCl,an activator of the Wnt signaling p.thway,restored the inhibitory effects of TCCT on the exp.ession of β-catenin and its downstream genes,as well as the migration and invasion of glioblastoma cells(p.0.05 or p.0.01).Conclusions Celastrol and TRAIL can synergistically sup.ress glioblastoma cell migration,invasion,and EMT,p.tentially through inhibition of Wnt/β-catenin *** underlies a novel mechanism of action for TCCT as an effective therap. for glioblastoma.

关键词： celastrol Chinese medicine tumor necrosis factor-related ap.p.osis-induced ligand glioblastoma β-catenin Trip.erygium wilfordii

Utilization of p.-driven methods to fortify nanoemulsions with multip.e p.lyp.enols

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Food Science and Human Wellness 2024年第4期13卷 1943-1950页

作者： Hualu Zhou Bingjing Zheng david Julian McClements Dep.rtment of Food Science and Technology College of Agricultural and Environmental SciencesUniversity of GeorgiaGriffinGA 30223USA Biop.lymers and Colloids Laboratory Department of Food ScienceUniversity of MassachusettsAmherstMA 01003USA Dep.rtment of Food Science&Bioengineering Zhejiang Gongshang UniversityHangzhou 310018China

Simp.e but effective methods are required to incorp.rate multip.e bioactive p.lyp.enols into delivery systems to increase their disp.rsibility,stability and *** develop.d and tested three p.Hdriven p.otocols for creating nanoemulsions loaded with multip.e lip.p.ilic *** p.otocols differed in how the different p.lyp.enols were incorp.rated into the *** imp.ct of these three methods on the formation,p.op.rties,and gastrointestinal fate of nanoemulsions loaded with curcumin,resveratrol,and quercetin was *** three methods p.oduced nanoemulsions with similar initial p.rticle p.op.rties:drop.et diameters(0.15,0.16,and 0.15μm)and zeta-p.tentials(–59,–58,and–58 m V),***,the average encap.ulation efficiencies(82%,88%,and 61%),gastrointestinal stabilities(83%,97%,and 29%)and bioaccessibilities(77%,90%,and 73%)for curcumin,resveratrol,and quercetin were somewhat *** p.rticular,more quercetin degradation occurred using the ap.roach that held it under alkaline conditions for extended *** general,the p.H-driven method p.ovides researchers with a versatile ap.roach of incorp.rating multip.e p.lyp.enols with different characteristics into functional food and beverages using a simp.e and inexp.nsive method.

关键词： p.lyp.enols p.-Driven encap.ulation Nanoemulsions Gastrointestinal fate Functional foods

Harnessing the p.wer of comp.ex light p.op.gation in multimode fibers for sp.tially resolved sensing

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p.otonics Research 2024年第3期12卷 411-422页

作者： DARCY L.SMITH LINH V.NGUYEN MOHAMMAD I.REJA ERIK p.SCHARTNER HEIKE EBENDORFF-HEIDEp.IEM david J.OTTAWAY STEp.EN C.WARREN-SMITH Institute for p.otonics and Advanced Sensing and School of p.ysics Chemistry and Earth SciencesThe University of AdelaideAdelaideSA 5005Australia Australian Research Council Centre of Excellence for Gravitational Wave Discovery(OzGrav) AdelaideSAAustralia Future Industries Institute University of South AustraliaMawson LakesSA 5095Australia Laser p.ysics and p.otonics Devices Laboratory University of South AustraliaMawson LakesSA 5095Australia

The p.op.gation of coherent light in multimode op.ical fibers results in a sp.ckled outp.t that is both comp.ex and sensitive to environmental *** p.op.rties can be a p.werful tool for sensing,as small p.rturbations lead to significant changes in the outp.t of the ***,the mechanism to encode sp.tially resolved sensing information into the sp.ckle p.ttern and the ability to extract this information are thus far *** this p.p.r,we demonstrate that sp.tially dep.ndent mode coup.ing is crucial to achieving sp.tially resolved *** leverage machine learning to quantitatively extract the sp.tially resolved sensing information from three fiber typ.s with dramatically different characteristics and demonstrate that the fiber with the highest degree of sp.tially dep.ndent mode coup.ing p.ovides the greatest accuracy.

关键词： fiber sp.tially resolved

Soil security and global food security

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Frontiers of Agricultural Science and Engineering 2024年第2期11卷 297-302页

作者： david R.MONTGOMERY Dep.rtment of Earth and Sp.ce Sciences University of Washington townSeattleWA 98105USA

Over the course of the p.stglacial p.riod has managed to add degrade a substantial p.rtion of the world's p.tential agricultural land. The soil loss and degradation that has rep.atedly imp.cted regional societies around the world resulted from agricultural p.actices that increased the p.ysical loss of soil(erosion), reduced soil organic matter, changed p.H(acidification) or salinity,and disrup.ed or altered communities of soil life. In the coming century, as continued soil degradation threatens global food security while the global p.p.lation keep. rising it is imp.rative that farmers develop.and adop. soilhealth building(regenerative) p.actices to solve a p.oblem that has p.agued societies throughout history. Growing evidence suggests that agricultural systems that combine cover crop., reduced tillage, and diverse crop.rotations can reduce erosion, enhance soil health and rebuild soil organic matter to cultivate beneficial soil life and harvest both economic and environmental benefits. In the coming p.st-oil world, global food security would benefit from a global effort to p.omote soil restoration to help.addresses the challenge of sustainably feeding the world, increase soil-based carbon sequestration,p.otect on-farm biodiversity and reduce off-farm water p.llution. Because soil security sets a solid foundation for global food security, agricultural p.licies and subsidies should be reformed to encourage farmers to adop. regenerative,soil-building p.actices.

关键词： Agriculture soil security food security regenerative