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Direct-to-indirect mapping for optimal 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 Department of Aerospace Engineering and Engineering Mechanics The University of Texas at AustinAustinTexas78712USA

Optimal,many-revolution spacecraft trajectories are challenging to solve.A connection is made for a class of models between optimal direct and indirect *** transfers that minimize thrust-acceleration-squared,primer vector theory maps direct,many-impulsive-maneuver trajectories to the indirect,continuous-thrust-acceleration *** mapping algorithm is independent of how the direct solution is obtained and requires only a solver for a boundary value problem and its partial derivatives.A Lambert solver is used for the two-body problem in this *** mapping is simple because the impulsive maneuvers and co-states share the same linear space around an optimal *** numerical results,the direct coast-impulse solutions are demonstrated to converge to the indirect continuous solutions as the number of impulses and segments *** two-body design space is explored with a set of three many-revolution,many-segment examples changing semimajor axis,eccentricity,and *** first two examples involve a small change to either semimajor axis or eccentricity,and the third example is a transfer to geosynchronous *** a single processor,the optimization runtime is seconds to minutes for revolution counts of 10 to 100,and on the order of one hour for examples with up to 500 *** of these thrust-acceleration-squared solutions are good candidates to start a homotopy to a higher-fidelity minimization problem with practical constraints.

关键词： direct optimization indirect optimization impulsive maneuvers Lambert's problem two-body dynamics primer vectortheory

The great catastrophe: causes of the permo-Triassic marine mass extinction

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

作者： paul 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 permo-Triassic mass extinction were the worst ever experienced. All groups were badly affected, especially amongst the benthos(e.g. brachiopods, corals, bryozoans, foraminifers,ostracods). planktonic populations underwent a fundamental change with eukaryotic algae being replaced by nitrogen-fixing bacteria, green-sulphur bacteria, sulphate-reducing bacteria and prasinophytes. Detailed studies of boundary sections, especially those in South China, have resolved the crisis to a ～55 kyr interval straddling the permo-Triassic boundary. Many of the losses occur at the beginning and end of this interval painting a picture of a two-phase extinction. Improved knowledge of the extinction has been supported by numerous geochemical studies that allow diverse proposed 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 rapidly rising temperatures and many extinction scenarios attribute the losses to both anoxia and high *** kill mechanisms include ocean acidification for which there is conflicting support from geochemical proxies and, even less likely, siltation(burial under a massive influx of terrigenous sediment) which lacks substantive sedimentological evidence. The ultimate driver of the catastrophic changes at the end of the permian was likely Siberian Trap eruptions and their associated carbon dioxide emissions with consequences such as warming, ocean stagnation and acidification. Volcanic winter episodes stemming from Siberian volcanism have also been linked to the crisis, but the short-term nature of these episodes(pid 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 productivity collapse volcanic winter

A combined experimental and DEM investigation of grain interlocking in sheared granular assemblies

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particuology 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-Speed Railway Engineering(Southwest Jiaotong University) Ministry of EducationChengdu 610031China School of Civil Engineering University of LeedsLeeds LS29JTUK Department of Civil Engineering McMaster UniversityHamiltonONCanada

Compacted granular material,integral to geotechnical engineering,undergoes translation,rotation,and interlocking when subject to shear displacements or external *** present study focuses on the interlocking of heterogeneous granular materials,a complex behavior influenced by gradation,compaction,and varying particle 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 compaction and normal *** of the mixes also underwent subsequent shear reversal to explore the differences in grain interlocking between the two shearing processes on the shear *** analyzing the laboratory results,a mesoscopic scale investigation was performed by replicating the test using discrete element *** facilitate this,granular particle geometries were measured using 3D laser scanning based on the physical lab ***,based on these scans,discrete element R-block and ball models were utilized to construct both the coarse and fine particles within the *** vibro-compaction was employed to regulate the degree of *** results indicate that an increase in vertical pressure,coupled with a zero dilatancy angle,results in a rising stress ratio,indicative of grain *** interlocking exhibits a positive correlation with both the coarse content and the degree of compaction,and varies depending on the shear *** interlocking progresses,the shear band,induced by particle movement,expands and is associated with reduced particle rotation near the shear *** study further reveals a consistent positive correlation between interlocking and the principal orientation angle of strong normal c

关键词： Granular material Interlocking Shear resistance Direct shear Discrete element method Vibro-compaction

portable ultrasonography in mass casualty incidents:The CAVEAT examination

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World Journal of Orthopedics 2010年第1期1卷 10-19页

作者： Stanislaw peter Stawicki James M Howard John p pryor david p bahner Melissa L Whitmill Anthony J Dean Department of Surgery Division of Critical CareTraumaand BurnThe Ohio State University Medical CenterColumbusOH 43210United States Department of Surgery Division of Traumatology and Surgical Critical CareUniversity of Pennsylvania School of MedicinePhiladelphiaPA 19104United States Department of Emergency Medicine The Ohio State University Medical CenterColumbusOH 43210United States Department of Emergency Medicine University of Pennsylvania School of MedicinePhiladelphiaPA 19104United States

Ultrasonography used by practicing clinicians has been shown to be of utility in the evaluation of time-sensitive and critical illnesses in a range of environments,including pre-hospital triage,emergency department,and critical care *** increasing availability of lightweight,robust,user-friendly,and low-cost portable ultrasound equipment is particularly suited for use in the physically and temporally challenging environment of a multiple casualty incident(MCI).Currently established ultrasound applications used to identify potentially lethal thoracic or abdominal conditions offer a base upon which rapid,focused protocols using hand-carried emergency ultrasonography could be *** a detailed review of the current use of portable ultrasonography in military and civilian MCI settings,we propose a protocol for sonographic evaluation of the chest,abdomen,vena cava,and extremities for acute *** protocol is two-tiered,based on the urgency and technical difficulty of the sonographic *** addition to utilization of well-established bedside abdominal and thoracic sonography applications,this protocol incorporates extremity assessment for long-bone *** of the proposed protocol will need to be conducted to determine its utility in simulated and actual MCI settings.

关键词： Focused Assessment with Sonography in Trauma Chest,abdomen,vena cava,and extremities for acute triage Ultrasonography Disaster Field triage pre-hospital care Mass casualty incident

TRAIL and Celastrol Combinational Treatment Suppresses proliferation, Migration, and Invasion of Human Glioblastoma Cells via Targeting Wnt/β-catenin Signaling pathway

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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 Developmental Biology Department of Cell Biology and GeneticsSchool of Basic Medical SciencesChongqing Medical UniversityChongqing(400016)China Department of Biochemistry and Molecular Biology School of Basic Medical SciencesChongqing Medical UniversityChongqing(400016)China

Objective To investigate the mechanistic basis for the anti-proliferation and anti-invasion effect of tumor necrosis factor-related apoptosis-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 groups,namely control,TRAIL(TRAIL 100 ng/mL),Cel(celastrol 0.5µmol/L)and TCCT(TRAIL 100 ng/mL+celastrol 0.5µmol/L).Cell proliferation,migration,and invasion were detected by colony formation,wound healing,and Transwell assays,*** reverse transcription polymerase chain reaction and Western blotting were performed to assess the levels of epithelial-mesenchymal transition(EMT)markers(zona occludens,N-cadherin,vimentin,zinc finger E-box-binding homeobox,Slug,and β-catenin).Wnt pathway was activated by lithium chloride(LiCl,20 mol/L)and the mechanism for action of TCCT was *** Celastrol and TRAIL synergistically inhibited the proliferation,migration,invasion,and EMT of U87 cells(pp-regulated the expression of GSK-3β and down-regulated the expression of β-catenin and its associated proteins(ppproteinase(MMp)-*** addition,LiCl,an activator of the Wnt signaling pathway,restored the inhibitory effects of TCCT on the expression of β-catenin and its downstream genes,as well as the migration and invasion of glioblastoma cells(ppppress glioblastoma cell migration,invasion,and EMT,potentially through inhibition of Wnt/β-catenin *** underlies a novel mechanism of action for TCCT as an effective therapy for glioblastoma.

关键词： celastrol Chinese medicine tumor necrosis factor-related apoptosis-induced ligand glioblastoma β-catenin Tripterygium wilfordii

Utilization of pH-driven methods to fortify nanoemulsions with multiple polyphenols

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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 Department of Food Science and Technology College of Agricultural and Environmental SciencesUniversity of GeorgiaGriffinGA 30223USA Biopolymers and Colloids Laboratory Department of Food ScienceUniversity of MassachusettsAmherstMA 01003USA Department of Food Science&Bioengineering Zhejiang Gongshang UniversityHangzhou 310018China

Simple but effective methods are required to incorporate multiple bioactive polyphenols into delivery systems to increase their dispersibility,stability and *** developed and tested three p Hdriven protocols for creating nanoemulsions loaded with multiple lipophilic *** protocols differed in how the different polyphenols were incorporated into the *** impact of these three methods on the formation,properties,and gastrointestinal fate of nanoemulsions loaded with curcumin,resveratrol,and quercetin was *** three methods produced nanoemulsions with similar initial particle properties:droplet diameters(0.15,0.16,and 0.15μm)and zeta-potentials(–59,–58,and–58 m V),***,the average encapsulation efficiencies(82%,88%,and 61%),gastrointestinal stabilities(83%,97%,and 29%)and bioaccessibilities(77%,90%,and 73%)for curcumin,resveratrol,and quercetin were somewhat *** particular,more quercetin degradation occurred using the approach that held it under alkaline conditions for extended *** general,the p H-driven method provides researchers with a versatile approach of incorporating multiple polyphenols with different characteristics into functional food and beverages using a simple and inexpensive method.

关键词： polyphenols pH-Driven encapsulation Nanoemulsions Gastrointestinal fate Functional foods

Harnessing the power of complex light propagation in multimode fibers for spatially resolved sensing

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photonics 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-HEIDEpRIEM david J.OTTAWAY STEpHEN C.WARREN-SMITH Institute for photonics and Advanced Sensing and School of physics 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 physics and photonics Devices Laboratory University of South AustraliaMawson LakesSA 5095Australia

The propagation of coherent light in multimode optical fibers results in a speckled output that is both complex and sensitive to environmental *** properties can be a powerful tool for sensing,as small perturbations lead to significant changes in the output of the ***,the mechanism to encode spatially resolved sensing information into the speckle pattern and the ability to extract this information are thus far *** this paper,we demonstrate that spatially dependent mode coupling is crucial to achieving spatially resolved *** leverage machine learning to quantitatively extract the spatially resolved sensing information from three fiber types with dramatically different characteristics and demonstrate that the fiber with the highest degree of spatially dependent mode coupling provides the greatest accuracy.

关键词： fiber spatially 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 Department of Earth and Space Sciences University of Washington townSeattleWA 98105USA

Over the course of the postglacial period has managed to add degrade a substantial portion of the world's potential agricultural land. The soil loss and degradation that has repeatedly impacted regional societies around the world resulted from agricultural practices that increased the physical loss of soil(erosion), reduced soil organic matter, changed p H(acidification) or salinity,and disrupted or altered communities of soil life. In the coming century, as continued soil degradation threatens global food security while the global population keeps rising it is imperative that farmers develop and adopt soilhealth building(regenerative) practices to solve a problem that has plagued societies throughout history. Growing evidence suggests that agricultural systems that combine cover crops, 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 post-oil world, global food security would benefit from a global effort to promote soil restoration to help addresses the challenge of sustainably feeding the world, increase soil-based carbon sequestration,protect on-farm biodiversity and reduce off-farm water pollution. Because soil security sets a solid foundation for global food security, agricultural policies and subsidies should be reformed to encourage farmers to adopt regenerative,soil-building practices.

关键词： Agriculture soil security food security regenerative

液体活检在肺癌管理中新技术的发展和临床应用的拓展

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Science Bulletin 2024年第10期69卷 1556-1568页

作者：陈克终何越王文香袁晓秋 david p.Carbone 杨帆 Department of Thoracic Surgery Peking University People’s HospitalBeijing 100044China peking University people’s Hospital Thoracic Oncology Institute&Research Unit of Intelligence Diagnosis and Treatment in Early Non-small Cell Lung Cancer Beijing 100044China peking University Health Science Center Beijing 100191China Thoracic Oncology Center Ohio State UniversityColumbus 43026USA

Lung cancer is an exceedingly malignant tumor reported as having the highest morbidity and mortality of any cancer worldwide,thus posing a great threat to global *** the growing demand for precision medicine,current methods for early clinical detection,treatment and prognosis monitoring in lung cancer are hampered by certain *** have found that during the formation and development of a tumor,molecular substances carrying tumor-related genetic information can be released into body *** biopsy(LB),a method for detecting these tumor-related markers in body fluids,maybe a way to make progress in these *** recent years,LB technology has undergone rapid ***,this review will provide information on technical updates to LB and its potential clinical applications,evaluate its effectiveness for specific applications,discuss the existing limitations of LB,and present a look forward to possible future clinical ***,this paper will introduce technical updates from the prospectives of engineering breakthroughs in the detection of membrane-based LB biomarkers and other improvements in sequencing ***,it will summarize the latest applications of liquid biopsy for the early detection,diagnosis,treatment,and prognosis of lung *** will present the interconnectedness of clinical and laboratory issues and the interplay of technology and application in LB today.

关键词： Liquid biopsy techniques Lung cancer Circulating tumor cells Circulating tumor DNA Sequencing technology Clinical application