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Spread of common native and invasive grasses and ruderal trees following anthropogenic disturbances in a tropical dry forest

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Ecological Processes 2017年第1期6卷 394-407页

作者： Xavier A.Jaime Skip J.Van Bloem Frank H.Koch Stacy A.c.Nelson Department of Ecosystem Science and Management Texas A&M University2138 TAMUCollege StationTX 77843-2138USA Belle W.Baruch Institute of coastal Ecology and Forest Science Clemson UniversityPO Box 596GeorgetownSC 29442USA USDA Forest Service Southern Research Station3041 East Cornwallis RoadResearch Triangle ParkNC 27709USA center for Geospatial Analytics Department of Forestry and Environmental ResourcesNorth Carolina State UniversityRaleighNC 27695USA.

Introduction:A fundamental challenge to the integrity of tropical dry forest ecosystems is the invasion of nonnative grass *** grasses compete for resources and fuel anthropogenic *** 2012,a bulldozer from the Puerto Rico Electric Power Authority cleared a 570-m trail from a state road into a mature dry forest section of Guánica Forest to control a *** monitored colonization by a non-native invasive grass(Megathyrsus maximus),a highly invasive tree(Leucaena leucocephala),and a native grass(Uniola virgata),as well as natural regeneration,along the bulldozer *** determined whether bulldozing facilitated colonization by these species into the forest and the extent of ***:Distance from propagule source and temporal variations strongly influenced colonization by our three focal *** maximus invaded along the trail from source populations by the state *** establishment of new colonies of *** seedlings went as far as 570 m inside the forest(i.e.,at the end of the bulldozer trail),but we found most new colonies within 270 m of the *** leucocephala exhibited a similar spreading *** disturbance,Uniola virgata was distributed widely across the forest,but the highest densities were found in areas near the latter portion(>401 m)of the bulldozer ***,the species formed new clumps along more than half of the trail(250 to 570 m),apparently colonizing from undisturbed patches ***:Bulldozing facilitated the invasion of non-native *** projected community assemblage will be more fire-prone than before since *** carries fire across the landscape better than ***,emphasizing the capacity of invasive plant colonization to alter local ecological processes after only a single wildfire and bulldoze *** results provide a valuable baseline for short-term vegetation response to anthropogenic disturbances in tropical semi-deciduous dry forests.

关键词： Tropical dry forest Grass invasions Bulldozing Wildfire Leucaena leucocephala Megathyrsus(Panicum)maximus Uniola virgata

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A statistical model to predict total column ozone in Peninsular Malaysia

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Frontiers of Earth Science 2016年第1期10卷 63-73页

作者： K. c. TAN H. S. LIM M. Z. MAT JAFRI School of Physics Universiti Sains Malaysia Penang 11800 Malaysia

This study aims to predict monthly columnar ozone in Peninsular Malaysia based on concentrations of several atmospheric gases. Data pertaining to five atmo- spheric gases （cO2, 03, cH4, NO2, and H2O vapor） were retrieved by satellite scanning imaging absorption spectro- metry for atmospheric chartography from 2003 to 2008 and used to develop a model to predict columnar ozone in Peninsular Malaysia. Analyses of the northeast monsoon （NEM） and the southwest monsoon （SWM） seasons were conducted separately. Based on the Pearson correlation matrices, columnar ozone was negatively correlated with HzO vapor but positively correlated with cOz and NO2 during both the NEM and SWM seasons from 2003 to 2008. This result was expected because NO/is a precursor of ozone. Therefore, an increase in columnar ozone concentration is associated with an increase in NO2 but a decrease in H/O vapor. In the NEM season, columnar ozone was negatively correlated with H20 （-0.847）, NO2 （0.754）, and cO2 （0.477）; columnar ozone was also negatively but weakly correlated with cH4 （-0.035）. In the SWM season, columnar ozone was highly positively correlated with NO2 （0.855）, cO2 （0.572）, and cH4（0.321） and also highly negatively correlated with H2O（-0.832）. Both multiple regression and principal component analyses were used to predict the columnar ozone value in Peninsular Malaysia. We obtained the best-fitting regression equations for the columnar ozone data using four independent variables. Our results show approxi- mately the same R value （≈0.83） for both the NEM and SWM seasons.

关键词： ozone ScIAMAcHY principal componentanalysis Peninsular Malaysia

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Evaluation of hydrogeochemical characteristics and the impact of weathering in seepage water collected within the sedimentary formation

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Acta Geochimica 2017年第1期36卷 44-51页

作者： M.V.Prasanna R.Nagarajan S.chidambaram A.Anand Kumar c.Thivya Department of Applied Geology Faculty of Engineering and ScienceCurtin University Sarawak Department of Earth Sciences Annamalai University Department of Geology University of Madras

A study was conducted by collecting eight seepage water samples that drain through the sedimentary rocks, mainly sandstone and shale, to evaluate the hydro- geochemical characteristics. The collected samples were analyzed for physico-chemical parameters using standard procedures. Three water types were identified in the Piper plot and the hydrogeochemical evolution starts from a ca- c1 facies （type 1） via mixed ca-Mg-c1 and ca-Na-HcO3 facies （type 2） to Na-c1 facies （type 3）. Increasing trend of electrical conductivity （Ec） values were observed from type 1 water to type 3 water. Lower ionic concentrations with an average Ec value of 35.7 kts/cm in ca-c1 facies indicate the recharge water by monsoonal rainfall, and ion exchange/weathering process is reflected in the mixing zone. Higher ionic concentration with an average Ec value of 399 kts/cm is noted in Na-c1 facies, which indicates the ion exchange during water-rock interaction. Higher log pcO2 values are also found in this facies, revealing the longer residence time of seepage water in the rock matrix, which release more ions into the water. The relative mobility of elements during weathering suggest that the order of mobility in both sandstone and shale is Na 〉 ca 〉 Mg 〉 K. It was observed that thehydrogeochemistry of seepage water is mainly controlled by the bedrock geology.

关键词： Hydrogeochemistry Seepage water Water rock interaction Weathering Mobility of elements

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PREDIcTION OF cARBON cONcENTRATION AND FERRITE VOLUME FRAcTION OF HOT-ROLLED STEEL STRIP DURING LAMINAR cOOLING

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Acta Metallurgica Sinica(English Letters) 2007年第4期20卷 251-257页

作者： Y.T. Zhang c.Z. Wang D.Z. Li Y.Y. Li School of Material Science and Engineering Shenyang Ligong University Shenyang 110168 China Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China

A phase transformation model was presented for predicting the phase fraction transformed and the carbon concentration in austenite for austenite to ferrite transformation during laminar cooling on run-out table in hot rolling strip mill. In this model, the parameter k in Avrami equation was developed for carbon steels. The wide range of chemical composition, the primary austenite grain size, and the retained strain were taken into account. It can be used to predict the ferrite volume fraction and the carbon concentration in austenite of hot-rolled steel strip during laminar cooling on run-out table. The coiling temperature controlling model was also presented to calculate the temperature of steel strip. The transformation kinetics of austenite to ferrite and the evolution of carbon concentration in austenite at different temperatures during cooling were investigated in the hot rolled Q235B strip for thickness of 9.35, 6.4, and 3.2mm. The ferrite volume fraction along the length of the strip was also calculated. The calculated ferrite volume fraction was compared with the log data from hot strip mill and the calculated results were in agreement with the experimental ones. The present study is a part of the prediction of the mechanical properties of hot-rolled steel strip, and it has already been used on-line and off-line in the hot strip mill.

关键词： carbon concentration ferrite volume fraction laminar cooling hot rolling

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Generation of time-varying orbital angular momentum beams with space-time-coding digital metasurface

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Advanced Photonics 2023年第3期5卷 92-100页

作者： Jingxin Zhang Peixing Li Ray c.c.cheung Alex M.H.Wong Jensen Li The Hong Kong University of Science and Technology Department of PhysicsHong KongChina city University of Hong Kong Department of Electrical EngineeringHong KongChina city University of Hong Kong State Key Laboratory of Terahertz and Millimeter WavesHong KongChina

The recently proposed extreme-ultraviolet beams with time-varying orbital angular momentum(OAM)realized by high-harmonic generation provide extraordinary tools for quantum excitation control and particle ***,such an approach is not easily scalable to other frequency *** design a space-time-coding digital metasurface operating in the microwave regime to experimentally generate time-varying OAM *** to the flexible programmability of the metasurface,a higher-order twist in the envelope wavefront structure of time-varying OAM beams can be further designed as an additional degree of *** time-varying OAM field patterns are dynamically mapped by developing a two-probe measurement *** approach in combining the programmability of space-time-coding digital metasurfaces and the two-probe measurement technique provides a versatile platform for generating and observing time-varying OAM and other spatiotemporal excitations in *** proposed time-varying OAM beams have application potentials in particle manipulation,time-division multiplexing,and information encryption.

关键词： time-varying orbital angular momentum digital-coding metasurfaces wavefront structure

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Transcriptional control of SET DOMAIN GROUP 8 and cAROTENOID ISOMERASE during Arabidopsis Development

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Molecular Plant 2010年第1期3卷 174-191页

作者： christopher I. cazzonelli Andrea c. Roberts Melanie E. carmody Barry J. Pogson Australian Research council centre of Excellence in Plant Energy Biology Research School of Biology The Australian National University Canberra ACT0200 Australia

carotenoids are pigments required for photosynthesis, photoprotection and the production of carotenoid- derived hormones such as ABA and strigolactones. The carotenoid biosynthetic pathway bifurcates after lycopene to produce epsilon- and beta-carotenoids and this branch is critical for determining carotenoid composition. Here, we show how the branch point can be regulated by the chromatin-modifying histone methyltransferase, Set Domain Group 8 （SDG8） targeting the carotenoid isomerase （cRTISO）. SDG8 is required to maintain permissive expression of cRTISO during seedling development, in leaves, shoot apex, and some floral organs. The cRTISO and SDG8 promoters show overlapping tissue-specific patterns of reporter gene activity. Interestingly, cRTISO showed atypical reporter gene expression in terms of greater variability between different lines compared to the cauliflower Mosaic Virus 35S promoter （caMV35s） and ~LcY promoters, potentially due to chromosomal position effects. Regulation of the cRTISO promoter was dependent in part upon the presence or absence of SDG8. Knockouts of SDG8 （carotenoid and chloroplast regulation （ccrl）） and cRTISO （ccr2） result in altered carotenoid composition and this could be restored in ccr2 using the caMV35s or cRTISO promoters. In contrast, varying degrees of GUS expression and carotenoid complementation by cRTISO overexpression using caMV35S or cRTISO promoters in the ccrl background demonstrated that both the cRTISO promoter and open reading frame are necessary for SDG8-mediated expression of cRTISO.

关键词： Photosynthesis secondary metabolism--terpenoids, isoprenoids, and carotenoids chloroplast biology epigenetics gene expression gene regulation.

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Roles of tensor and isoscalar pairing interactions in β-decay calculations for possible r-process waiting point nuclei with N~82 and 126

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chinese Physics c 2022年第11期46卷 221-230页

作者： c.L.Bai D.L.Fang H.Q.Zhang School of physics science and technology Sichuan UniversityChengdu 610065China Institute of Modern Physics Chinese Academy of SciencesLanzhou 730000China School of Nuclear Science University of Chinese Academy of SciencesBeijing 100049China china Institute of Atomic Energy Beijing 10400China

In this study,we adopt the self-consistent Hartree-Fock-Bogoliubov(HFB) theory with the proton-neutron quasi-particle random phase approximation(pnQRPA) based on the Skyrme force for calculation of the β^(-) -decay half-lives for nuclei with N~82 and 126 on possible r-process *** the calculations,the Skyrme interaction(e.g.,SKO’) is adopted,and the tensor interaction is added self-consistently in both HFB and QRPA *** systematically study how the half-life is changed by varying the strength of the triplet-even(TE) and triplet-odd(TO) components as well as the IS *** find that a variation in strength of the IS pairing of approximately 20% does not produce a substantial effect on β-decay rates with or without the tensor force,while a strength variation of the TO tensor force considerably affects the change in the β-decay half-lives for the very neutron rich N~82 and 126 isotonic *** addition,with the inclusion of the tensor force,the GT decay becomes dominant for very neutron-rich nuclei.

关键词： nuclear structure weak decay density functional theory

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MicroRNA expression profiles and functions in the brain

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Neural Regeneration Research 2008年第12期3卷 1380-1385页

作者： Yanting Qi Yu Zhao Zhuyin chen Xiaona chen Marie c. Lin Xiangfu Kong Lihui Lai Institute of Molecular and chemical Biology East China Normal University Shanghai 200062 China Stanley Ho centre for Emerging Infectious Diseases Faculty of Medicine The Chinese University of Hong Kong Hong Kong SpecialAdministrative Region China Department of chemistry Open Laboratory of Chemical Biology University of Hong Kong Hong Kong Special Administrative Region China

MicroRNAs are abundant in the brains of vertebrates and some show a brain-specific or brain-enriched expression pattern. Because microRNAs regulate the expression of hundreds of target genes, it is not surprising that they have profoundly important functions in brain development and pathological processes. For example, miR-124 plays an important role in inducing and maintaining neuronal identity through targeting at least two anti-neural factors. MicroRNAs have also been implicated in brain disorders, including brain tumors and neurodegenerative diseases. This review aims to present an overview of the expression profiles and functions of microRNAs in the developing brains of vertebrates.

关键词： neurogenesis neural cell specification synaptic plasticity posttranscriptional regulator epigenetic control

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ISOcHRONOUS STRESS-STRAIN cURVES OF LOW ALLOY STEEL cROSS-WELD-SPEcIMEN AT HIGH TEMPERATURE

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Acta Metallurgica Sinica(English Letters) 2004年第4期17卷 612-617页

作者： c.W.Ma F.Z.Xuan Z.D.Wang S.T.Tu East china University of Science and Technology Shanghai 200237 ChinaEast China University of Science and Technology Shanghai 200237 ChinaEast China University of Science and Technology Shanghai 200237 ChinaEast China University of Science and Technology Shanghai 200237 China Nanjing University of Technology Nanjing 210009 China

In this work, a parametric approach is presented and utilized to determine the creep properties of weldments; then the model of creep strain for cross weld specimen is given. On the basis of the experimental results, attempt has been made to establish equations of the isochronous stress-strain for weld joint that can predict the function of loading and service time in use of the creep data of base metal and weld metal.

关键词： isochronous stress-strain curve creep deformation high temperature welded joint low alloy steel

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EVALUATION OF THE TIME DEPENDENT FAILURE ASSESSMENT cURVES FOR 10crMo910 AND 316 SS AT 550℃

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Acta Metallurgica Sinica(English Letters) 2004年第4期17卷 443-449页

作者： F.Z.Xuan S.D.Tu Z.D.Wang c.W.Ma School of Mechanical Engineering East China University of Science and Technology Shanghai 200237ChinaSchool of Mechanical Engineering East China University of Science and Technology Shanghai 200237ChinaSchool of Mechanical Engineering East China University of Science and Technology Shanghai 200237ChinaSchool of Mechanical Engineering East China University of Science and Technology Shanghai 200237China

10crMo910 and 316 stainless steel are widely adopted in high temperature structures of power generations, chemical processing plants and petroleum refineries. In this work, a total of 10000 hour tensile creep test on 16 specimens of such two materials was conducted at 550℃. On the basis of the experimental results, the isochronous stress-strain curves and time-dependent failure assessment curves of the two materials were given. Finally, the formulae of time dependent failure assessment curve for 10crMo910 and 316 stainless steel corresponding to long-term creep cases, which could be utilized in the high temperature defects assessment, were established. The procedure for defining the time-dependent failure assessment curves was also presented.

关键词： 10crMo910 316 stainless steel creep time-dependent failure assessment curve

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