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Competition of Squirreltail with Cheatgrass at Three Nitrogen Levels

American Journal of Plant Sciences 2014年第7期5卷 990-996页

作者： Allan R. stevens Val Jo Anderson Rachel Fugal Department of Biology Snow College Ephraim USA Plant and Wildlife Sciences Brigham Young University Provo USA

Squirreltail (Elymus elymoides [Raf] Swezey) can grow in cheatgrass (Bromus tectorum L.) stands, and has reduced the biomass production of cheatgrass in its immediate vicinity. A field experiment was conducted to determine: 1) if competition for nitrogen resources occurs between seedlings of squirreltail and seedlings of cheatgrass, under low, medium, and high nitrogen levels, and;2) if competition for nitrogen resources in the seedling stage is a mechanism that allows squirreltail to establish in cheatgrass stands. Five accessions of squirreltail were each seeded with a single accession of cheatgrass in a cultivated field near Ephraim, Utah in the fall of 1995 and again in 1996. A completely randomized strip-plot design with 3 replications was used including the 5 joint seedings as well as pure seedings of each accession of both species. Three nitrogen levels representing high, medium (control), and low were applied. The study was replicated over 2 years in different areas of the same field. Harvests of above-ground biomass of squirreltail and cheatgrass within each treatment were conducted in July of 1996 and 1997. Using biomass production as a measure of efficient nitrogen use, cheatgrass competed for and used nitrogen resources more efficiently than squirreltail when nitrogen was not limiting. All squirreltail accessions were able to compete for and use nitrogen more efficiently than cheatgrass when there was low availability of nitrogen. Some accessions of squirreltail competed for nitrogen resources more efficiently than others both in the control and at the reduced nitrogen level. White Rock. and Sublette squirreltail accessions were the best competitors with cheatgrass at the low nitrogen level reducing the cheatgrasss biomass by as much as 75% and 67% respectively. An intermediate competitor with cheatgrass was the Gunnison accession. The Washak.e and Pueblo accessions were poor competitors with cheatgrass at low nitrogen levels.

关键词： Accession Biomass Bromus tectorum Elymus elymoides Seedling

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中国苏州与美国15岁学生数学学习特征比较

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心理科学 2008年第1期31卷 58-61,48页

作者：黄辛隐李元桥叶仁敏 Carla J stevens 苏州大学教育学院苏州215123 Houston Independent School District Research Department

本研究首次采用"学生能力国际评估计划"(PISA)的学生问卷,对苏州市504名15岁学生的数学学习心理及特征进行了调查研究,并与美国学生数据作比较。调查表明:中国苏州大多数学生在数学学习上具有较强的竞争意识与合作意识,他们会运用多种... 详细信息

本研究首次采用"学生能力国际评估计划"(PISA)的学生问卷,对苏州市504名15岁学生的数学学习心理及特征进行了调查研究,并与美国学生数据作比较。调查表明:中国苏州大多数学生在数学学习上具有较强的竞争意识与合作意识,他们会运用多种学习策略;那些对数学有更大兴趣和更高动机的学生,有更积极的自我概念和更少的焦虑体验。中美两国学生的数学学习特征性别差异显著。

关键词：学习特征数学 “学生能力国际评估计划”(PISA)

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Modelling changing population distributions:an example of the k.nyan Coast,1979–2009

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International Journal of Digital Earth 2017年第10期10卷 1017-1029页

作者： Catherine Linard Caroline W.k.baria Marius Gilbert Andrew J.Tatem Andrea E.Gaughan Forrest R.stevens Alessandro Sorichetta Abdisalan M.Noor Robert W.Snow Spatial Epidemiology Lab(SpELL) UniversitéLibre de BruxellesBrusselsBelgium Department of Geography Universitéde NamurNamurBelgium Spatial Health Metrics Group KEMRI Wellcome Trust Research ProgrammeNairobiKenya Fonds National de la Recherche Scientifique(F.R.S.-FNRS) BrusselsBelgium WorldPop Department of Geography and EnvironmentUniversity of SouthamptonSouthamptonUK Fogarty International Center National Institutes of HealthBethesdaMDUSA Flowminder Foundation StockholmSweden Department of Geography and Geosciences University of LouisvilleLouisvilleKYUSA Nuffield Department of Clinical Medicine Centre for Tropical Medicine and Global HealthUniversity of OxfordOxfordUK

Large-scale gridded population datasets are usually produced for the year of input census data using a top-down approach and projected back.ard and forward in time using national growth *** temporal projections do not include any subnational variation in population distribution trends and ignore changes in geographical covariates such as urban land cover *** predictions of population distribution changes over time require the use of a limited number of covariates that are time-invariant or temporally *** we mak. use of recently released multi-temporal high-resolution global settlement layers,historical census data and latest developments in population distribution modelling methods to reconstruct population distribution changes over 30 years across the k.nyan *** explore the methodological challenges associated with the production of gridded population distribution time-series in data-scarce countries and show that trade-offs have to be found between spatial and temporal resolutions when selecting the best modelling *** used to fill data gaps may vary according to the local context and the objective of the *** work.will hopefully serve as a benchmark.for future developments of population distribution time-series that are increasingly required for population-at-risk.estimations and spatial modelling in various fields.

关键词： Human population distribution modelling gridded population datasets temporal change k.nya

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A Tutorial to Approximately Invert the Sumudu Transform

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Applied Mathematics 2019年第11期10卷 1004-1028页

作者： Glen Atlas John k.-J. Li Adam Work Department of Anesthesiology Rutgers New Jersey Medical School Newark NJ USA Department of Biomedical Engineering Stevens Institute of Technology Hoboken NJ USA Department of Biomedical Engineering Rutgers University Piscataway NJ USA

Unlik. the traditional Laplace transform, the Sumudu transform of a function, when approximated as a power series, may be readily inverted using factorial-based coefficient diminution. This technique offers straightforward computational advantages for approximate range-limited numerical solutions of certain ordinary, mixed, and partial linear differential and integro-differential equations. Furthermore, discrete convolution (the Cauchy product), may also be utilized to assist in this approximate inversion method of the Sumudu transform. Illustrative examples are provided which elucidate both the applicability and limitations of this method.

关键词： Sumudu Transform Double Series Discrete Convolution Cauchy Product

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Prediction of Impending Drought Scenarios Based on Surface and Subsurface Parameters in a Selected Region of Tropical Queensland, Australia

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Journal of Water Resource and Protection 2021年第8期13卷 605-631页

作者： Bithin Datta Dilip k.mar Roy Jonathan J. k.lley Bradley stevens Discipline of Civil Engineering College of Science and Engineering James Cook University Townsville Australia Irrigation and Water Management Division Bangladesh Agricultural Research Institute Joydebpur Bangladesh

Droughts occur in all climatic regions around the world costing a large expense to global economies. Reasonably accurate prediction of drought events helps water managers proper planning for utilization of limited water resources and distribution of available waters to different sectors and avoid catastrophic consequences. Therefore, a means to create a simplistic approach for forecasting drought conditions with easily accessible parameters is highly desirable. This study proposes and evaluates newly developed accurate prediction models utilizing various hydrologic, meteorological, and geohydrology parameters along with the use of Artificial Neural Network.(ANN) models with various forecast lead times. The present study develops a multitude of forecasting models to predict drought indices such as the Standard Precipitation Index with a lead-time of up to 6 months, and the Soil Moisture Index with a lead-time of 3 months. Furthermore, prediction models with the capability of approximating surface and groundwater storage levels including the Ross River Dam level have been developed with relatively high accuracy with a lead-time of 3 months. The results obtained from these models were compared to current values, revealing that ANN based approach can be used as a simple and effective predictive model that can be utilized for prediction of different aspects of drought scenarios in a typical study area lik. Townsville, North Queensland, Australia which had suffered severe recent drought conditions for almost six recent years (2014 to early 2019).

关键词： Drought Prediction Artificial Neural Network Prediction Model Dam Levels Aquifer Salinity Water Storage Townsville Queensland

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PERCUTANEOUS TRANSLUMINAL EXCIMER LASER CORONARY ANGIOPLASTY CLINICAL REPORT OF SIX CASES

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Chinese Medical Journal 1994年第1期 20-25页

作者：徐成斌蒋宝琦王伟民陈红郭丹杰沈东陈步星 stevens.MehtaHeartInstituteoftheDesertU.S.A CardiovascularInstituteandDepartmentofCardlovascularMedicine People’sHospitalBeningMedicalUniversity

Six patients with 95% to 100% occluded atheroseleroticlesions underwent percutaneous transluminal excimer lasercoronary angioplasty (PTELCA). Among them, 5 were maleand ! was female; their age ranged from 28 to 66 years. Fourpatients had LAD stenosis and 2 LCX *** and clinical success was achieved in all patientsbut one, with a success rate Of 83.3%. It was demonstratedthat PTELCA is a safe and effective therapy for selected pa-tients with coronary artery disease.

关键词： PTCA PERCUTANEOUS TRANSLUMINAL EXCIMER LASER CORONARY ANGIOPLASTY CLINICAL REPORT OF SIX CASES In

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The role of P2Y1 purinergic receptors in regulation of vasopressin and oxytocin release from the neurohypothysis

The role of P2Y1 purinergic receptors in regulation of vasop...

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2008北京国际生理科学学术大会

作者： GOMES Dayane A stevens Wanida SLADEk.Celia D Department of Physiology and Biophysics University of Colorado Denver Health Sciences CenterAuroraCOUSA

ATP and phenylephrine(PE,α1 adrenergic receptor agonist)co-applied to explants of the hypothalamoneurohypophyseal system(HNS)act synergistically to stimulate vasopressin and oxytocin release and generate an extended elevation in intracellular calcium([Ca])in supraoptic nucleus neurons(SON).Both P2X and P2Y purinergic receptors contribute to the ATP-induced increase in[Ca] in *** immunohistochemical and immuno-blotting studies revealed the existence of P2Y1 purinergic receptors(P2Y1R)proteins in ***, the functional role of P2YlRs in regulation of vasopressin(VP)and oxytocin(OT)release was evaluated by studies perfusing the HNS *** of P2Y1Rs by the specific agonist 2-Methyl-thio-ADP significantly increased VP release from HNS explants compared to *** the other hand,exposure to the specific P2Y1R antagonist,MRS2179,suppressed the ATP+PE stimulated synergistic VP release from the HNS *** results were obtained for OT *** findings strongly support an essential role for P2Y1Rs in regulating VP and OT hormone release from *** studies are ongoing to clarify the mechanisms underlying the regulation of VP and OT release by P2YRs.

关键词： purinergic receptor vasopressin supraoptic nucleus ATP

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Understanding China’s Success in Africa

Understanding China’s Success in Africa

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2012 2nd International Conference on Applied Social Science(ICASS 2012)

作者： Mijitaba Maman Moustapha Randriamalala Jean Luc stevens School of Management Huazhong University of Science and Technology School of Management Wuhan University of Technology Wuhan

China is becoming undeniably a world economic leader. The present work.tries to explore the reasons of such success by considering the relationship between the country and the African continent. Conversely to developed economies such as America and European nations, China emphasizes on mutual benefits through a dynamic politico-economic strategy relying on five dimensions: understanding Africa’s development needs, supporting in-difficulties countries, building a win-win relationship, a non-interference principle, and a dynamic diplomacy. To implement and support its strategy, China offers foreign aids and promotes cultural integration and studies. With the establishment of the Forum on China-Africa Cooperation （FOCAC） in 2000, the country look. forward to overcome any obstacle to the bi-partite relationship.

关键词： China-Africa cooperation international trade strategies

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水彩植物艺术

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作者： (英)Mary Ann Scott (英)Margaret stevens

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检测地面温度记录中的气候信号

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气象科技 1999年第2期27卷 14-26页

作者： Gerald R.North Mark.J.stevens 美国得克萨斯A&M大学

利用最佳信号检测理论于１００年的地面温度资料中寻找与４个特定辐射强迫的气候响应。分析中所用的资料来源于地球上的３６个单元，而且被限定在０．０６～０．１３ｒ／ａ的频带（１６．６７～７．６９ａ）内。估算了气候对太阳变率、... 详细信息

利用最佳信号检测理论于１００年的地面温度资料中寻找与４个特定辐射强迫的气候响应。分析中所用的资料来源于地球上的３６个单元，而且被限定在０．０６～０．１３ｒ／ａ的频带（１６．６７～７．６９ａ）内。估算了气候对太阳变率、火山气溶胶、温室气体和人类活动产生的气溶胶的响应强度。最佳滤波器由一个用二维能量平衡模式（ＥＢＭ）计算出的信号波形组成。最佳权重是用地球物理流体动力学实验室（ＧＦＤＬ）和Ｍａｘ－Ｐｌａｎｋ研究所耦合的海气模式的１０００年控制试验和噪声强迫的ＥＢＭ１００００年控制试验计算得到的。作者还利用了ＧＦＤＬ混和层模式的１０００年试验。结果这４个独立的模式有合理的一致性。我们发现，垂直于其他信号的火山分量非常强，且很显著。与此类似，垂直于其他信号的温室气体分量也非常强且很显著。当所有４个气候强迫组合时，气候响应超过噪音水平的３个标准差。

关键词：气候变化地面温度太阳变率温室气体气溶胶

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