检索结果-南通市图书馆

Water Science and Engineering 2023年第1期16卷 14-25页

作者： Tim J.Grandjean Jaco C.de Smit Jim van Belzen gregory S.Fivash Jeroen van Dalen Tom Ysebaert Tjeerd J.Bouma Department of Estuarine and delta Systems Royal Netherlands Institute for Sea Research(NIOZ)4401 NT YersekeThe Netherlands Faculty of Geosciences Department of Physical GeographyUtrecht University3508 TC UtrechtThe Netherlands

Understanding the sensitivity of tidal flats to environmental changes is ***,most studies rely on process-based models to systematically explain the morphodynamic evolution of tidal *** this study,we proposed an alternative empirical approach to explore tidal flat dynamics using statistical indices based on long-term time series of daily surface elevation *** elevation dynamic(SED)indices focus on the magnitude and period of surface elevation changes,while morphodynamic signature(MDS)indices relate sediment dynamics to environmental *** statistical analyses were applied to an intervention site in the Netherlands to determine the effect of recently constructed groynes on the tidal *** these analyses,we were able to(1)detect a reduction in the daily SED and(2)determine that the changes in the daily SED were predominantly caused by the reduction in wave impact between the groynes rather than the reduction in tidal ***,the presented results showed that the combination of novel statistical indices provides new insights into the trajectories of tidal flats,ecosystem functioning,and sensitivity to physical drivers(wind and tides).Finally,we suggested how the SED and MDS indices may help to explore the future trajectories and climate resilience of intertidal habitats.

关键词： Surface elevation dynamics Tidal flat trajectories Morphodynamic development Morphodynamic signature Bed level dynamics

Sieve element occlusion provides resistance against Aphis gossypii in TGR-1551 melons

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Insect Science 2020年第1期27卷 33-48页

作者： Hsuan-Chieh Peng gregory P.Walker Department of Microbiology and Plant Pathology University of CaliforniaRiversideCaliforniaUSA Department of Entomology University of CaliforniaRiversideCaliforniaUSA

Feeding behavior and plant response to feeding were studied for the aphid Aphis gossypii Glover on susceptible and resistant melons(*** and TGR-1551,respectively).Average phloem phase bout duration on TGR-1551 was<7% of the duration on ***-seven percent of aphids on TGR-1551 never produced a phloem phase that attained ingestion(EPG waveform E2)in contrast to only 7% of aphids on *** bout duration of waveform E2(scored as zero if phloem phase did not attain E2)on TGR-1551 was<3% of the duration on ***,average bout duration of EPG waveform El(sieve element salivation)was 2.8 times greater on TGR-1551 than on *** a second experiment,liquid nitrogen was used to rapidly cryofix leaves and aphids within a few minutes after the aphids penetrated a sieve *** near the penetration site was then examined by confocal laser scanning ***-six percent of penetrated sieve elements were occluded by protein in TGR-1551 in contrast to only 28% in *** in TGR-1551,occlusion was also observed in nearby nonpenetrated sieve ***,a calcium channel blocker,trivalent lanthanum,was used to prevent phloem occlusion in TGR-1551,and *** feeding behavior and the plants phloem response were compared between lanthanum-treated and control *** treatment eliminated the sieve element protein occlusion response and the aphids readily ingested phloem sap from treated *** study provides strong evidence that phloem occlusion is a mechanism for resistance against *** in TGR-1551.

关键词： aphid feeding behavior Aphis gossypii Cucumis melo insect-plant resistance phloem occlusion sieve element occlusion proteins

Sub-50 fs pulses at 2050 nm from a picosecond Ho:YLF laser using a two-stage Kagome-fiber-based compressor

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Photonics Research 2022年第3期10卷 637-645页

作者： Krishna Murari Giovanni Cirmi Hüseyin Cankaya gregory J.Stein Benoit Debord Frederic Gerome Felix Ritzkosky Fetah Benabid Oliver Muecke Franz X.Kärtner Center for Free Electron Laser Science CFEL Deutsches Elektronen-Synchrotron DESY22607 HamburgGermany Max-Planck Institute for Structure and Dynamics of Matter(MPSD) 22761 HamburgGermany ELI-ALPS ELI-HU Non-Profit Ltd.Szeged H-6728Hungary The Hamburg Center for Ultrafast Imaging&Department of Physics University of Hamburg22761 HamburgGermany GPPMM Group XLIM Research InstituteUMR 7252 CNRSUniversity of LimogesLimogesFrance show less

The high-energy few-cycle mid-infrared laser pulse beyond 2μm is of immense importance for attosecond science and strong-field ***,the limited gain bandwidth of laser crystals such as Ho:YLF and Ho:YAG allows the generation of picosecond(ps)long pulses and,hence,makes it challenging to generate few-cycle pulse at 2μm without utilizing an optical parametric chirped-pulse amplifier(OPCPA).Moreover,the exclusive use of the near-infrared wavelength has limited the generation of wavelengths beyond 4μm(OPCPA).Furthermore,high harmonic generation(HHG)conversion efficiency reduces dramatically when driven by a long-wavelength *** schemes such as multi-color HHG have been proposed to enhance the harmonic ***,it is highly desirable to generate few-cycle to femtosecond pulses from a 2μm laser for driving these ***,we utilize two-stage nonlinear spectral broadening and pulse compression based on the Kagome-type hollow-core photonic crystal fiber(HC-PCF)to compress few-ps pulses to sub-50 fs from a Ho:YLF amplifier at 2μm at 1 kHz repetition *** demonstrate both experimentally and numerically the compression of 3.3 ps at 140μJ pulses to 48 fs at 11μJ with focal intensity reaching 10^(13)W/cm^(***,this system can be used for driving HHG in solids at 2μ*** the first stage,the pulses are spectrally broadened in Kagome fiber and compressed in a silicon-based prism compressor to 285 fs at a pulse energy of 90μ*** the second stage,the 285 fs pulse is self-compressed in air-filled *** fine-tuning of the group delay dispersion(GDD)externally in a 3 mm window,a compressed pulse of 48 fs is *** leads to a 70-fold compression of the ps pulses at 2050 *** further used the sub-50 fs laser pulses to generate white light by focusing the pulse into a thin medium of YAG.

关键词： fiber amplifier compressor

The enduring link between forest cover and rainfall： a historical perspective on science and policy discussions

在线全文

学校读者我要写书评

暂无评论

Forest Ecosystems 2018年第1期5卷 53-61页

作者： Brett M.Bennett gregory A.Barton School of Humanities and Communication Arts Western Sydney UniversityLocked Bag 1797PenrithNSW 2751Australia Department of Historical Studies Faculty of HumanitiesUniversity of JohannesburgC-Ring 2-Orange Block(Kingsway Campus)Corner Kingsway and University RoadAuckland ParkSouth Africa

Background： This article traces the history of scientific ideas connecting forest cover with rainfall to inform ongoing debates about whether forests are net users or producers of water in the hydrological cycle. Scholars of the supply-side school argue that forests are net producers and magnifiers that increase rainfall at regional scales. Supply-side scholars seek to challenge the dominance of demand-side thinking. The demand-side school emphasizes that trees are net users of water within a catchment that decrease overall water available for other users. This scientific debate has significant implications for the development of policies to manage forests and water. Results： Scientists have debated the question of whether forests improve or worsen water balance for over two hundred years. Connections between forests and rainfall gained prominence in scientific circles during the second half of the nineteenth century and again during the past three decades. The popularity of forest- rainfall connections has paralleled societal and scientific interest in anthropogenic climate change and deforestation. Theories connecting forests with rainfall peaked in popularity in the 1850s to 1880s, a period when scientists expressed alarm that deforestation caused regional declines in precipitation. Forests were understood to create rain within a locality and region. Scientific consensus shifted by the early twentieth century to the view that forests did not play a significant role in determining rainfall. The forest-rainfall connection reemerged in the 1980s alongside advances in climate modelling and growing fears of anthropogenic global warming and tropical deforestation. Using new data and theories, supply-side advocates have once again placed a strong forest-rainfall connection into scientific prominence. Conclusion： Supply-side management policies have a checkered history that should elicit caution, while demand-side policies, which are based on almost a century of hydrolog

关键词： Climate change Environmental history Forests Hydrology Rain Water

Dynamic Modeling, Testing, and Stability Analysis of an Ornithoptic Blimp

在线全文

学校读者我要写书评

暂无评论

Journal of Bionic Engineering 2011年第4期8卷 375-386页

作者： John Dietl Thomas Herrmann gregory Reich Ephrahim Garcia Sibley School of Mechanical and Aerospace Engineering Cornell University Ithaca New York USA Air Force Research Laboratory Wright-Patterson AFB OH 45433-7542 USA

In order to study omithopter flight and to improve a dynamic model of flapping propulsion, a series 0f tests are conducted on a flapping-wing blimp. The blimp is designed and constructed from mylar plastic and balsa wood as a test platform for aerodynamics and flight dynamics. The blimp, 2.3 meters long and 420 gram mass, is propelled by its flapping wings. Due to buoyancy the wings have no lift requirement so that the distinction between lift and propulsion can be analyzed in a flight platform at low flight speeds. The blimp is tested using a Vicon motion tracking system and various initial conditions are tested including accelerating flight from standstill, decelerating from an initial speed higher than its steady state, and from its steady-state speed but disturbed in pitch angle. Test results are used to estimate parameters in a coupled quasi-steady aerodynamics/Newtonian flight dynamics model. This model is then analyzed using Floquet theory to determine local dynamic modes and stability. It is concluded that the dynamic model adequately describes the vehicle＇s nonlinear behavior near the steady-state velocity and that the vehicle＇s linearized modes are akin to those of a fixed-wing aircraft.

关键词： omithopter blimp flight dynamics stability analysis

Dietary supplementation with 0.4%L-arginine between days 14 and 30 of gestation enhances NO and polyamine syntheses and water transport in porcine placentae

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Animal Science and Biotechnology 2023年第2期14卷 627-639页

作者： Cassandra M.Herring Fuller W.Bazer gregory A.Johnson Heewon Seo Shengdi Hu Mohammed Elmetwally Wenliang He Daniel B.Long Guoyao Wu Department of Animal Science Texas A&M UniversityCollege StationTX 77843USA Department of Veterinary Integrative Biosciences Texas A&M UniversityCollege StationTX 77843USA.

Background:Most embryonic loss in pigs occurs before d 30 of *** supplementation with L-arginine(Arg) during early gestation can enhance the survival and development of conceptuses(embryo/fetus and its extraembryonic membranes) in ***,the underlying mechanisms remain largely ***:Between d 14 and 30 of gestation,each gilt was fed daily 2 kg of a corn-and soybean-meal based diet(12% crude protein) supplemented with either 0.4% Arg(as Arg-HCl) or an isonitrogenous amount of L-alanine(Control).There were 10 gilts per treatment *** d 30 of gestation,gilts were fed either Arg-HCl or L-alanine 30 min before they were hysterectomized,followed by the collection of placentae,embryos,fetal membranes,and fetal *** and allantoic fluids were analyzed for nitrite and nitrate [NOx;stable oxidation products of nitric oxide(NO)],polyamines,and amino *** were analyzed for syntheses of NO and polyamines,water and amino acid transport,concentrations of amino acid-related metabolites,and the expression of angiogenic factors and aquaporins(AQPs).Results:Compared to the control group,Arg supplementation increased(P < 0.05) the number of viable fetuses by 1.9 per litter,the number and diameter of placental blood vessels(+ 25.9% and + 17.0% respectively),embryonic survival(+ 18.5%),total placental weight(+ 36.5%),the total weight of viable fetuses(+ 33.5%),fetal crown-to-rump length(+ 4.7%),and total allantoic and amniotic fluid volumes(+ 44.6% and + 75.5% respectively).Compared to control gilts,Arg supplementation increased(P < 0.05) placental activities of GTP cyclohydrolase-1(+ 33.1%) and ornithine decarboxylase(+ 29.3%);placental syntheses of NO(+ 26.2%) and polyamines(+ 28.9%);placental concentrations of NOx(+ 22.5%),tetrahydrobiopterin(+ 21.1%),polyamines(+ 20.4%),c AMP(+ 27.7%),and c GMP(+ 24.7%);total amounts of NOx(+ 61.7% to + 96.8%),polyamines(+ 60.7% to + 88.7%),amino acids(+ 39% to + 118%),glucose(+ 60.5% to + 62.6

关键词： Angiogenesis Arginine Fetus Placenta Reproduction

Impact of oxygen-containing carbonyl and ether groups on dielectric properties of poly(oxa)norbornene cyclic olefins

在线全文

学校读者我要写书评

暂无评论

Journal of Advanced Dielectrics 2023年第4期13卷 65-68页

作者： Chao Wu Ajinkya A.Deshmukh Lihua Chen Rampi Ramprasad gregory A.Sotzing Yang Cao Institute of Materials Science University of Connecticut StorrsCT 06269USA School of Materials Science and Engineering Georgia Institute of Technology AtlantaGA 30332USA Department of Electrical and Computer Engineering University of Connecticut StorrsCT 06269USA

Flexible dielectric polymers that can withstand high electric field and simultaneously have high dielectric constant are desired for high-density energy ***,we systematically investigated the impact of oxygen-containing ether and carbonyl groups in the backbone structure on dielectric properties of a series of cyclic *** comparison to the influence of the-CF3 pendant groups that had more impact on the dielectric constant rather than the band gap,the change of the backbone structure affected both the dielectric constant and band *** one polymer with ether and carbonyl groups in the backbone has the largest band gap and highest discharge efficiency,while it has the lowest dielectric *** polymer without any ether groups in the backbone has the smallest band gap and lowest discharge efficiency,but it has the highest dielectric *** that have no dipolar relaxation exhibit an inversely correlated dielectric constant and band *** the dipolar relaxation through rational molecular structure design can be a novel way to break through the exclusive constraint of dielectric constant and band gap for high-density energy storage.

关键词： Polymer dielectric band gap glass transition conduction energy density DFT

Provision of nutrients after acute spinal cord injury: the implications of feast and famine

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Neural Regeneration Research 2015年第7期10卷 1061-1062页

作者： Sarah Garber gregory Hawryluk Department of Neurosurgery University of Utah Salt Lake CityClinical Neurosciences Center

Traumatic spinal cord injury（SCI）often leaves patients with devastating neurological *** traumatic event–or primary injury–can be due to mechanisms such as compression,distraction,shear,laceration or（rarely）even *** SCI patients are vulnerable to progressive,delayed damage as a result of secondary insults and secondary *** insults such as hypoxia and hypotension occur at the level of the organism from a myriad of causes.

关键词： PTP the implications of feast and famine Provision of nutrients after acute spinal cord injury

Regulation of Iron Uptake by IRT1： Endocytosis Pulls the Trigger

在线全文

学校读者我要写书评

暂无评论

Molecular Plant 2015年第7期8卷 977-979页

作者： Zelazny, Enric Vert, gregory Univ Paris 11 CEA CNRS Inst Integrat Biol Cell I2BC F-91190 Gif Sur Yvette France

The past two decades of research on plant iron nutrition have completed the casting of the major transporters involved in iron uptake from the soil, long-distance transport, and intracellular distribution. Among these transporters, most of the attention was given to the root iron transporter IRT1, which plays a critical role in iron uptake from the soil and mediates transport of other non-iron metals （zinc, manganese, cobalt, cadmium） under iron-limiting conditions.

关键词： Regulation Uptake Endocytosis

Cloud-based storage and computing for remote sensing big data:a technical review

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

International Journal of Digital Earth 2022年第1期15卷 1417-1445页

作者： Chen Xu Xiaoping Du Xiangtao Fan gregory Giuliani Zhongyang Hu Wei Wang Jie Liu Teng Wang Zhenzhen Yan Junjie Zhu Tianyang Jiang Huadong Guo Key Lab of Digital Earth Sciences Aerospace Information Research InstituteChinese Academy of SciencesBeijingPeople’s Republic of China International Research Center of Big Data for Sustainable Development Goals BeijingPeople’s Republic of China College of Resources and Environment University of Chinese Academy of SciencesBeijingPeople’s Republic of China Institute for Environmental Sciences/GRID-Geneva University of GenevaGenevaSwitzerland Institute for Marine and Atmospheric research Utrecht (IMAU) Utrecht UniversityUtrechtThe Netherlands State Key Laboratory of Computer Science Institute of SoftwareChinese Academy of SciencesBeijingPeople’s Republic of China Tianyi Cloud People’s Republic of China Telecom Co.LtdGuangzhouPeople’s Republic of China Department of Computer Science and Technology Tsinghua UniversityBeijingPeople's Republic of China

The rapid growth of remote sensing big data(RSBD)has attracted considerable attention from both academia and *** the progress of computer technologies,conventional computing implementations have become technically inefficient for processing *** computing is effective in activating and mining large-scale heterogeneous data and has been widely applied to RSBD over the past *** study performs a technical review of cloud-based RSBD storage and computing from an interdisciplinary viewpoint of remote sensing and computer ***,we elaborate on four critical technical challenges resulting from the scale expansion of RSBD applications,*** storage,metadata management,data homogeneity,and computing ***,we introduce state-of-the-art cloud-based data management technologies for RSBD *** unit for manipulating remote sensing data has evolved due to the scale expansion and use of novel technologies,which we name the RSBD data *** data models are suggested,***,ARD,data cubes,and composite ***,we summarize recent research on the application of various cloud-based parallel computing technologies to RSBD computing ***,we categorize the architectures of mainstream RSBD *** research provides a comprehensive review of the fundamental issues of RSBD for computing experts and remote sensing researchers.

关键词： Remote sensing big data cloud computing data cube analysis ready data parallel computing data model