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Populations with individual variation in dispersal in heterogeneous environments: Dynamics and competition with simply diffusing populations

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Science China Mathematics 2020年第3期63卷 441-464页

作者： Robert Stephen cantrell Chris Cosner Xiao Yu Department of Mathematics University of MiamiCoral GablesFL 33146USA School of Mathematical Sciences South China Normal UniversityGuangzhou 510631China

We consider a model for a population in a heterogeneous environment, with logistic-type local population dynamics, under the assumption that individuals can switch between two different nonzero rates of diffusion. Such switching behavior has been observed in some natural systems. We study how environmental heterogeneity and the rates of switching and diffusion affect the persistence of the population. The reactiondiffusion systems in the models can be cooperative at some population densities and competitive at others. The results extend our previous work on similar models in homogeneous environments. We also consider competition between two populations that are ecologically identical, but where one population diffuses at a fixed rate and the other switches between two different diffusion rates. The motivation for that is to gain insight into when switching might be advantageous versus diffusing at a fixed rate. This is a variation on the classical results for ecologically identical competitors with differing fixed diffusion rates, where it is well known that "the slower diffuser wins".

关键词： reaction-diffusion ecology and evolutionary biology population dynamics animal behavior individual variation in dispersal evolution of dispersal

Evaluation of nest site preferences of a nest dismantler,the Hair-crested Drongo(Dicrurus hottentottus) in Dongzhai National Nature Reserve of central China

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Chinese Birds 2016年第2期7卷 125-131页

作者： Andrew cantrell Lei Lv Yong Wang Jianqiang Li Zhengwang Zhang College of Agricultural Life and Natural Sciences Alabama A&M University School of Life Sciences Beijing Normal University

Background:The Hair-crested Drongo(Dicrurus hottentottus) exhibits a unique nest-dismantling behavior after the fledging of the *** hypothesis explaining this behavior is dismantling one's own nest may reduce potential competition for nest sites in the following breeding season because suitable breeding habitat might be limited,and sites are often ***:By comparing the habitat features at nest and random locations,we determined the nest habitat preference of the Hair-crested Drongo within Dongzhai National Nature Reserve,Henan,*** also compared habitat features with nesting success to determine if any trends could be ***:We found that nest tree height,diameter at breast height,live crown ratio,tree rank,and presence of overstory were significantly higher at nesting locations than random locations;slope,leaf litter cover percentage and depth,presence of understory and midstory,and number of trees per hectare were significantly lower at nest sites than random *** preferred to use some tree species,such as Metasequoia glyptostroboides,Castanea mollissima,and Pterocarya stenoptera for *** nests were often associated with habitat with higher percentage of leaf litter on the ***:Our data support that selection of nest sites does occur for this species at this site and therefore support the hypothesis that breeding habitat limitation could be one of the driving forces for the development of the nestdismantling behavior in this species.

关键词： Hair-crested Drongo Nest dismantling behavior Nest site selection China Dongzhai National Nature Reserve

Post-operative prevention and monitoring of Crohn’s disease recurrence

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Gastroenterology Report 2022年第1期10卷 217-226页

作者： Kate E.Lee Sarah cantrell Bo shen Adam S.Faye Department of Medicine Duke University Medical CenterDurhamNCUSA Duke University Medical Center Library&Archives Duke University School of MedicineDurhamNCUSA Center for Inflammatory Bowel Diseases NewYork-Presbyterian/Columbia University Irving Medical CenterNew YorkNYUSA Division of Gastroenterology NYU Grossman School of MedicineNew YorkNYUSA

Crohn’s disease(CD)and ulcerative colitis(UC)are relapsing and remitting chronic inflammatory diseases of the gastrointestinal *** surgery for UC can provide a cure,surgery for CD is rarely *** the past few decades,research has identified risk factors for postsurgical CD recurrence,enabling patient risk stratification to guide monitoring and prophylactic treatment to prevent CD recurrence.A MEDLINE literature review identified articles regarding post-operative monitoring of CD recurrence after resection *** this review,we discuss the evidence on risk factors for postoperative CD recurrence as well as suggestions on post-operative management.

关键词： post-operative Crohn’s management recurrence biologics

Physics-based modeling of crowd evacuation in the Unity game engine

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International Journal of Modeling, Simulation, and Scientific Computing 2018年第4期9卷 108-138页

作者： Walter Alan cantrell Mikel D.Petty Samantha L.Knight Whitney K.Schueler University of Alabama in Huntsville 301 Sparkman Drive OKT N353Huntsville Alabama 35899United States of America

Crowds of people are often found in enclosed or constricted *** in such situations is usually conducted calmly,but real or perceived danger may trigger *** panicked crowds,the interpersonal distance crowd members normally observe is often overwhelmed by the physical pressure of crowd members pushing against each *** pressure can both slow evacuation and lead to injury or *** have been developed to study crowd evacuation in a range of *** paper describes the implementation,testing,and validation of a crowd evacuation model using Unity,a commercial computer game engine.A realistic physics-based model of crowd movement that calculates and considers the physical pressure crowd members exert on each other was implemented in *** implemented model was tested under both nonpanicked and panicked scenarios;those tests exhibited known qualitative characteristics of such *** model was then quantitatively validated by comparing its results to the outcome of an actual evacuation event,the 2003 fire at The Station nightclub in Rhode *** implementation and validation show that Unity can be an effective tool for evacuation modeling.

关键词： Crowd modeling crowd movement evacuation modeling game engines Unity.

Ectoparasites and other invertebrates in the nests of the Hair-crested Drongo (Dicrurus hottentottus)

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Chinese Birds 2013年第4期4卷 314-318页

作者： Andrew cantrell 吕磊王勇张正旺李建强美国阿拉巴马农工大学生物与环境科学系生物多样性与生态工程教育部重点实验室北京师范大学生命科学学院北京1000875

Ectoparasites and other invertebrates are known to play a role in bird behavior and in evolutionary adaptations such as preening and foraging strategies. We conducted an exploratory study by macro- and microscopically evaluating the nests of Hair-crested Drongos(Dicrurus hottentottus) at Dongzhai National Nature Reserve, Henan Province, China in 2011 to determine if there was a presence of invertebrates. We developed a modified funneling technique to collect invertebrate samples and reduce contamination from outside sources in a field setting. We found several species of ectoparasites(lice and ticks) and other invertebrates(springtails and rove beetles) within the nests. Our findings warrant further investigation as to whether or not the presence of invertebrates in the nests of Hair-crested Drongos plays a role in the adaptation of the unique nest dismantling behavior exhibited by this species.

关键词： China Dicrurus hottentottus Dongzhai National Nature Reserve ectoparasite invertebrate modified funneling technique

Signal generation and spatial resolution in scanning electron acoustic microscopy

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Chinese Journal of Acoustics 1991年第3期10卷 209-218页

作者： QIAN Menglu Jhon H.cantrell

The thermal conduction and Navier- Stokes equations are used to obtain the stress field generated by a chopped electron beam incident on a disk sample. The piezoelectric equation is then used to obtain the output signal of the transducer coupled to the sample. The results lead to a consideration of the signal generation mechanism and spatial resolution in scanning electron acoustic microscopy ( SEAM). It is shown that a time- variant heat source generated both a thermal wave and an acoustic wave simultaneously, and thermal- to- acoustic wave mode conversion oc-cured on the boundary surfaces depends on the amplitudes and the gradients at boundary surfaces of both heat source and thermal waves. It is argued that the spatial resolution of a imaging system operated in the near field, such as SEAM and thermal wave microscope, is dependent on the distance between the heat source and scatterer and, at best, the lateral resolution in SEAM is of the order of the diameter of the focal spot of the electron beam.

关键词： exp Signal generation and spatial resolution in scanning electron acoustic microscopy 一仃

扫描电子声显微镜的信号激发和像的空间分辨率

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声学学报 1991年第3期16卷 161-169页

作者：钱梦(马彔) John H.cantrell 同济大学声学研究所上海200092 NASA Langley Research Center

求解热传导方程及Navier-Stokes方程,得到强度以频率f调制的电子束在一圆盘状试样内所激发的三维应力场。再由压电方程得出与试样直接相耦合的压电换能器的输出信号。并由此理论结果讨论了信号激发机理及像的空间分辨率。它表明,一个交... 详细信息

求解热传导方程及Navier-Stokes方程,得到强度以频率f调制的电子束在一圆盘状试样内所激发的三维应力场。再由压电方程得出与试样直接相耦合的压电换能器的输出信号。并由此理论结果讨论了信号激发机理及像的空间分辨率。它表明,一个交变热源同时激发出热波和声波;在界面上发生的热波-声波的模式转换,与热波和热源两者有关,并取决于两者在界面上的幅值及界面上的梯度大小,同时表明,在扫描电子声显微镜和热波显微镜这类近场成象系统中,像的空间分辨率将与源和散射体之间的距离有关,预计扫描电子声显微镜中最佳的横向分辨率约为聚焦电子束直径的量级。

关键词： SEAM 显微镜信号激发空间分辨率

Utilization of Cotton DNA Markers in Cotton Breeding

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棉花学报 2008年第S1期20卷 15-页

作者： cantrell Roy G Monsanto Company 800 N.Lindbergh Blvd. St.Louis MO 63167

Informative,portable,and efficient DNA markers have the potential to accelerate genetic gain in cotton *** and widespread application of DNA markers to cotton has

关键词： DNA Utilization of Cotton DNA Markers in Cotton Breeding

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扫描电子声显微镜用于维氏硬度压痕的研究

计量学报 1992年第4期13卷 312-313,319页

作者：钱梦騄 John H.cantrell 同济大学声学研究所 NASA Langley Research Center HamptonVA 23665-5225

扫描电子声显微镜(SEAM)是80年代发展起来的无损检测设备。利用SEAM对脆性材料上维氏硬度压痕进行检测的结果充分显示了它在材料科学和硬度计量研究中的潜在应用前景。本文将对SEAM技术的基本原理及其在硬度计量上的可能应用作一简要的... 详细信息

扫描电子声显微镜(SEAM)是80年代发展起来的无损检测设备。利用SEAM对脆性材料上维氏硬度压痕进行检测的结果充分显示了它在材料科学和硬度计量研究中的潜在应用前景。本文将对SEAM技术的基本原理及其在硬度计量上的可能应用作一简要的介绍。当一有确定形状的压头,在恒定的试验力P的作用下压入试件表面时,试件在与压头的接触表面上所产生的反作用力F与形变的特征尺度a之间的关系可简化为图1的曲线,在施加试验力的半周期中,

关键词：脆性材料声显微镜硬度无损检测