Attributes associated with probability of infestation by the pi?on ips, Ips confusus (Coleoptera: Scolytidae), in pi?on pine, Pinus edulis

We examined attributes of pi?on pine ( Pinus edulis ) associated with the probability of infestation by pi?on ips ( Ips confuses ) in an outbreak in the Coconino National Forest, Arizona. We used data collected from 87 plots, 59 infested and 28 uninfested, and a logistic regression approach to estimate the probability of infestation based on plot and tree-level attributes. Pi?on pine stand density index was a good predictor of the likelihood of infestation by pi?on ips at the plot level, and a cross-validation analysis confirmed that the model correctly classified 82% of the cases. Diameter at root collar and pi?on dwarf mistletoe infestation level were good predictors of individual tree infestation, and a cross-validation analysis indicated that the model correctly classified 72% of the cases. Results suggest that the occurrence of pi?on ips infestations may be related to stress factors associated with increased stocking and pi?on dwarf mistletoe infestations.     

Sperm viability in the reproductive tract of females in a population of Sceloporus mucronatus exhibiting asynchronous reproduction

Asynchronous reproduction is a common phenomenon in high-elevation populations of lizards from Central México. Sperm storage in the reproductive tract of females is the mechanism for making oocyte fertilization possible. Our study addresses questions related to functional oviductal sperm storage of females mating on different dates throughout the reproductive season. A population of Sceloporus mucronatus with copulation in the summer and ovulation in the fall was chosen for this experiment. Eleven females that copulated in the field during June and 13 females that copulated in captivity during August were maintained in the laboratory until parturition. The number of pregnant females and the litter sizes produced in each experimental group were indicative of the viability of the stored sperm. Sperm stored in the reproductive tract of females were able to fertilize eggs after 4 months. No significant differences were found in the number of pregnant females between the 2 experimental groups nor in the litter sizes that they produced. We found that the amount of time sperm were held in the female reproductive tract (ca. 3 months) had no effect on the capacity of sperm to fertilize eggs. Histological examination of 8 oviducts collected before the mating season eliminated the possibility of sperm storage from one year to the next. In this system, sperm retention could have evolved as a response mechanism to deal with the asynchrony between sexes in the reproductive cycles. However, we cannot rule out alternative hypotheses.     

具有抗艾滋病毒活性的多肽T22([T5,12yr,L7yr]-PolyphemusinⅡ)骨架构象模拟

用势能平滑搜索方法，在平滑修饰的势能面上对具有抗艾滋病毒HIV－1活性的肽T22（[Tyr^5,12,Tyr^7]-PolyphemusinⅡ）骨架结构进行了全程搜索，得到了该分子骨加结构在修饰势能面上的分子构象全集。用多构象优化方法，选择较适用于肽OPLS力场，采用GB／SA水溶剂模型，优化上述构象集，得到T22骨架结构在水溶液中优势构象集。结果表明势能平滑搜索与多构象优化相结合的构象分析方法是解决含有环结构的柔性分子构象分析中多重最小问题的有效方法。     

交错群A_p的数量刻画(英文)

证明了若p≥ 5且p与p - 2 均为素数 ,则交错群Ap 可用元的阶刻画     

H_∞ Control of a 5th- order Model of Synchronous Generators

1　IntroductionThe control of synchronous generators is one of the most important and widely studiedproblem in the area of power systems control.Such a problem is a non-trivial one,mainlybecause of the highly nonlinear behaviour of synchronous machines.As a matter of fact,their dynamic dramatically changes when passing from a working condition to another.Asa consequence,standard PID-based controllers can not guarantee high performances overthe entire working range.Among the various control a…     

A System for Generating Operational Sketches Based on the Multi- level Graphic Library

1　IntroductionLittle previous work has been reported on the generation of operational sketches.However,there are two major strategies for generating operational sketches. The first iscalled geometric model method in which geometric information of a work-piece is organizedinto a model called solid model or feature solid model with the 3 D modeler. Theoperational sketches are generated by projecting into a projective plane which is chosenwith care.Feasible as it appears,this drawing obtained d…     

A Java-Based Approach for Developing Web Application System

1.INTRoDUCTIONCreatingInternet,IntranetandExtranetapplicationsarecurrentlycenterofprogrammingfocus.Theyallbelongtoweb-basedbusinessapplications[1lthatrequiredatabaseconnec-tion,userauthentication,sessionmanagementanddynamicHTMLgeneration.Web-basedapplicationsshouldhavefollowingfeatures:1)Platform-independelltontheclientside,usuallyabrowser;2)Platform-independentontheserverside,suchasincludingbothUnixandWindowsenvironments;3)Beabletoconnecttoavarietyofdatabase,suchasincludingoracle,Inf…     

进行动物实验应遵循的基本原则

１引言尽管由于国家、文化背景和宗教信仰不同，人们对待动物的态度千差万别，但是，以科学研究为目的使用动物时，有一条根本原则，即负责任、合乎道德地使用动物。使研究结果具有可重复性、可比性、科学性。在科学探索中使用动物是一种贡献，而不是权力，对这种贡献必须...     

用电子能量消失谱法研究P.tinctorius—P.massoniana菌根

在实验室条件下用12株外生菌根菌，对马尾松（Pinus massoniana)培养苗进行高效菌种的接种试验，筛选并证明分布于台湾的采色豆马勃（Pisolithus tinctorius)，具有生长快，对生态环境要求不严格，接种成功率大的特点。用能量消失谱技术对细胞内N、P营养元素进行定位测定，表明了这一菌株具有对N、P元素的吸收和贮存能力。