The Impact of Endothall on the Aquatic Plant Community of Kress Lake, Washington

CA dense mat-forming population of Eurasian watermilfoil ( Myriophyllum spicatum L . ) was interfering with fishing and recreation in a small western Washington lake. A low concentration (1.5 mg/L active ingredient) of the herbicide endothall formulated as Aquathol® K was used in 2000 to attempt to selectively control the Eurasian watermilfoil. Aquatic plant biomass and frequency data were collected before treatment, ten weeks after treatment and during the growing season for 3 additional years. Macrophyte data were analyzed to assess the herbicide’s impacts on Eurasian watermilfoil as well as the rest of the aquatic plant community. Results showed a significant decrease in Eurasian watermilfoil biomass and frequency 10 weeks after treatment. The Eurasian watermilfoil continued to be present, but at a significantly reduced level through the remainder of the study (3 years after treatment). Of the native plant species, large-leaf pondweed ( Potamogeton amplifolius Tucker . ) frequency and biomass was significantly reduced after treatment. Common elodea ( Elodea canadensis Rich.), muskgrass ( Chara sp. Vallaint.) and bladderwort ( Utricularia sp. L.) all increased significantly after treatment. (PDF has 6 pages.)

La máquina de Marly

Duración (en horas): De 21 a 30 horas. Destinatario: Estudiante y Docente

Relationship between water quality, watermilfoil frequency, and weevil distribution in the State of Washington

During the summer of 1997, we surveyed 50 waterbodies in Washington State to determine the distribution of the aquatic weevil Euhrychiopsis lecontei Dietz. We collected data on water quality and the frequency of occurrence of watermilfoil species within selected watermilfoil beds to compare the waterbodies and determine if they were related to the distribution E. lecontei . We found E. lecontei in 14 waterbodies, most of which were in eastern Washington. Only one lake with weevils was located in western Washington. Weevils were associated with both Eurasian ( Myriophyllum spicatum L.) and northern watermilfoil ( M. sibiricum K.). Waterbodies with E. lecontei had significantly higher ( P < 0.05) pH (8.7 ± 0.2) (mean ± 2SE), specific conductance (0.3 ± 0.08 mS cm -1 ) and total alkalinity (132.4 ± 30.8 mg CaCO 3 L -1 ). We also found that weevil presence was related to surface water temperature and waterbody location ( = 24.3, P ≤ 0.001) and of all the models tested, this model provided the best fit (Hosmer- Lemeshow goodness-of-fit = 4.0, P = 0.9). Our results suggest that in Washington State E. lecontei occurs primarily in eastern Washington in waterbodies with pH ≥ 8.2 and specific conductance ≥ 0.2 mS cm -1 . Furthermore, weevil distribution appears to be correlated with waterbody location (eastern versus western Washington) and surface water temperature.

Panel Discussion - Management of Eurasian watermilfoil in the United States using native insects: State regulatory and management issues

While researchers have evaluated the potential of native insect herbivores to manage nonindigenous aquatic plant species such as Eurasian watermilfoil ( Myriophyllum spicatum L.), the practical matters of regulatory compliance and implementation have been neglected. A panel of aquatic nuisance species program managers from three state natural resource management agencies (Minnesota, Vermont and Washington) discussed their regulatory and policy concerns. In addition, one ecological consultant attempting to market one of the native insects to manage Eurasian watermilfoil added his perspective on the special challenges of distributing a native biological control agent for management of Eurasian watermilfoil.

Information Preservation (IP) Method in Simulation

This paper reviews firstly methods for treating low speed rarefied gas flows: the linearised Boltzmann equation, the Lattice Boltzmann method (LBM), the Navier-Stokes equation plus slip boundary conditions and the DSMC method, and discusses the difficulties in simulating low speed transitional MEMS flows, especially the internal flows. In particular, the present version of the LBM is shown unfeasible for simulation of MEMS flow in transitional regime. The information preservation (IP) method overcomes the difficulty of the statistical simulation caused by the small information to noise ratio for low speed flows by preserving the average information of the enormous number of molecules a simulated molecule represents. A kind of validation of the method is given in this paper. The specificities of the internal flows in MEMS, i.e. the low speed and the large length to width ratio, result in the problem of elliptic nature of the necessity to regulate the inlet and outlet boundary conditions that influence each other. Through the example of the IP calculation of the microchannel (thousands long) flow it is shown that the adoption of the conservative scheme of the mass conservation equation and the super relaxation method resolves this problem successfully. With employment of the same measures the IP method solves the thin film air bearing problem in transitional regime for authentic hard disc write/read head length ( ) and provides pressure distribution in full agreement with the generalized Reynolds equation, while before this the DSMC check of the validity of the Reynolds equation was done only for short ( ) drive head. The author suggests degenerate the Reynolds equation to solve the microchannel flow problem in transitional regime, thus provides a means with merit of strict kinetic theory for testing various methods intending to treat the internal MEMS flows.

Information preservation (IP) method in simulation of internal rarefied gas flows in MEMS

This paper reviews firstly methods for treating low speed rarefied gas flows: the linearised Boltzmann equation, the Lattice Boltzmann method (LBM), the Navier-Stokes equation plus slip boundary conditions and the DSMC method, and discusses the difficulties in simulating low speed transitional MEMS flows, especially the internal flows. In particular, the present version of the LBM is shown unfeasible for simulation of MEMS flow in transitional regime. The information preservation (IP) method overcomes the difficulty of the statistical simulation caused by the small information to noise ratio for low speed flows by preserving the average information of the enormous number of molecules a simulated molecule represents. A kind of validation of the method is given in this paper. The specificities of the internal flows in MEMS, i.e. the low speed and the large length to width ratio, result in the problem of elliptic nature of the necessity to regulate the inlet and outlet boundary conditions that influence each other. Through the example of the IP calculation of the microchannel (thousands m ? long) flow it is shown that the adoption of the conservative scheme of the mass conservation equation and the super relaxation method resolves this problem successfully. With employment of the same measures the IP method solves the thin film air bearing problem in transitional regime for authentic hard disc write/read head length ( 1000 L m ? = ) and provides pressure distribution in full agreement with the generalized Reynolds equation, while before this the DSMC check of the validity of the Reynolds equation was done only for short ( 5 L m ? = ) drive head. The author suggests degenerate the Reynolds equation to solve the microchannel flow problem in transitional regime, thus provides a means with merit of strict kinetic theory for testing various methods intending to treat the internal MEMS flows.

Monte Carlo Modeling of Micro Scale Gas Flows

An information preservation (IP) method has been used to simulate many micro scale gas flows. It may efficiently reduce the statistical scatter inherent in conventional particle approaches such as the direct simulation Monte Carlo (DSMC) method. This paper reviews applications of IP to some benchmark problems. Comparison of the IP results with those given by experiment, DSMC, and the linearized Boltzmann equation, as well as the Navier-Stokes equations with a slip boundary condition, and the lattice Boltzmann equation, shows that the IP method is applicable to micro scale gas flows over the entire flow regime from continuum to free molecular.

Single curved fiber sedimentation under gravity

Dynamics of single curved fiber sedimentation under gravity are simulated by using the lattice Boltzmann method. The results of migration and rotation of the curved fiber at different Reynolds numbers are reported. The results show that the rotation and migration processes are sensitive to the curvature of the fiber. (c) 2007 Elsevier Ltd. All rights reserved.

模拟MEMS中气体流动的工具——信息保存法

MEMS中气体流动因特征尺度小而是稀薄气体的领域,本文首先介绍处理低速稀薄气体流动的一些方法:线化Boltzmann方程,Lattice Boltzmann方法,加滑移边界的Navier-Stoks方程,以及DSMC方法,并讨论它们模拟MEMS中过渡领域低速流动所遇到的困难。信息保存法克服了流速低使得信息噪声比小引起统计模拟的困难,已成功模拟了一些一维和二维问题。MEMS中流速低和大的长宽比的特点还引起出入口边界条件相互影响需要协调的问题,通过微槽道流动的算例,在模拟中采用守恒形式的质量守恒方程和超松弛法成功地解决了这一问题。处理有温度变化的MEMS流动问题和跨越领域的混合算法是重要的问题,本文用信息保存法也进行了有益的尝试。

Cosmology in an accelerated universe: observations and phenomenology

En las últimas décadas la cosmología ha experimentado notables avances como consecuencia del desarrollo de nuevos experimentos que nos han abastecido con precisos datos observacionales. La calidad de estos datos ha permitido construir una imagen global del universo actual; un universo acelerado compuesto principalmente por materia oscura (23%) distinta a la materia ordinaria (5%), y energía oscura (70%), la componente del universo que contrarresta el efecto gravitatorio y explica la expansión acelerada de éste. Con la existencia de estas dos principales componentes se puede explicar la situación actual del universo y los fenómenos que tienen lugar en él. Sin embargo, su naturaleza es todavía un misterio, por lo que nos encontramos ante un largo y apasionante camino que recorrer.Es en este contexto donde se enmarca el trabajo presentado en esta tesis, cuyo principal objetivo es ir más allá y obtener algunas pistas nuevas sobre la naturaleza de la energía oscura. Las investigaciones llevadas a cabo durante esta tesis tratan de hacer frente a este sector ¿oscuro" desde varias perspectivas, combinando la teoría y el análisis de datos astronómicos.Como primer acercamiento, en el capítulo 2 se propone un nuevo modelo para unificar el sector ¿oscuro¿: materia y energía oscura. En los capítulos 3 y 4 se aborda el problema de la energía oscura desde una nueva perspectiva y se presentan unas nuevas parametrizaciones de la ecuación de estado de la energía oscura. Por último, en el capítulo 5, a través de los datos del fondo cósmico de microondas, se da un paso más allá en física de las épocas tempranas del universo, y se obtienen restricciones sobre el exceso de densidad de radiación observado. Por otra parte, se da una explicación a este fenómeno: se atribuye este exceso al fondo cósmico de ondas gravitacionales primordiales producido por las cuerdas cósmicas, bajo condiciones adiabáticas.

Additional information on the length-weight relationship of skipjack tuna from the Eastern Tropical Pacific Ocean

ENGLISH: Results of a study of the length-weight relationships of yellowfin (Neothunnus macropterus) and skipjack (Katsuwonus pelamis) tuna from several fishing areas of the Eastern Tropical Pacific Ocean have been published by Chatwin (1959). In that report, a very low exponential value of 2.6261 was obtained for skipjack from Area 14 (off northern Chile, see Chatwin, Figure 1). It was pointed out, however, that this estimate was based on two samples of fish with a very narrow range of total lengths, not representative of the range in the catch, and that it would be desirable to obtain a further estimate based on a larger range of total lengths. In addition, there proved to be significantly large differences among exponents for the areas sampled, precluding use of a single regression equation for all areas. Two important fishing areas remained unsampled (Areas 10 and 13, see Chatwin, Figure 1), and it appeared desirable to collect length-weight measurement data from them, so that estimating equations would be available for all areas. Subsequent to publication of Chatwin's study, samples of skipjack length-weight measurements were obtained from the desired areas. Estimates derived from these data, and their effects on the previous analysis are presented herein. SPANISH:Los resultados de un estudio sobre las relaciones entre la longitud y el peso del atún aleta amarilla (Neothunnus macropterus) y del barrilete (Katsuwonus pelamis) de las diferentes áreas de pesca en el Pacífico Oriental Tropical ya han sido publicados por Chatwin (1959). En ese informe se obtuvo un valor exponencial muy bajo de 2.626 para el barrilete del Area 14 (frente a la costa norte de Chile, ver Chatwin, Figura 1). Se hizo hincapié, sin embargo, en que esta estimación se basaba en dos muestras de peces con una amplitud muy estrecha de longitudes totales, no representativa de la amplitud en la pesca, y que sería deseable obtener una estimación adicional basada en una amplitud mayor de longitudes totales. Además, se comprobó que habian diferencias significativamente grandes entre los exponentes de las áreas muestreadas lo que impedía el usa de una sola ecuación de regresión para todas las áreas. Se quedaron sin muestrear dos importantes áreas de pesca (Areas 10 y 13, ver Chatwin, Figura 1) y pareció deseable recolectar datos de medidas de longitud y peso de estas áreas, de tal manera que hubiesen disponibles ecuaciones estimadoras para todas las áreas. Después de la publicación del estudio de Chatwin, so obtuvieron muestras de medidas de longitud y peso de barriletes de las áreas deseadas. Las estimaciones derivadas de estos datos y sus efectos sabre el análisis previo se dan en el presente informe.

Diário da Constituinte [gravação de vídeo] : [programa n. 656]

Os constituintes começaram a apresentar os pedidos de Destaques para votação das emendas em separados. O prazo para a entrega dos requerimentos vai até o dia 22.7.1988 a meia-noite. Cada constituinte tem o direito de apresentar 4 (quatro) Destaques. O primeiro a chegar foi o Líder do PMDB, Nelson Jobim. Até o final da tarde mais de 180 constituintes já tinham apresentado seu Destaque, como foi o caso dos deputados Francisco Kuster (PMDB-SC) e Nelson Frederich (PMDB-PR). O Centrão que fez algumas reuniões anteriormente, já sabe o que quer retirar do texto e acredita que têm votos suficientes para isto. Os constituintes considerados progressistas acham que os temas que foram objeto de acordo no 1º Turno devem permanecer no texto e acreditam que pouca coisa deve ser modificada. Jair Menegheli (Presidente da CUT) disse que os sindicalistas já estão preparados para a defesa de seus direitos no 2º Turno.

钱学森技术科学思想与力学

本书收录会议论文60篇。

　　本书内容大体分为三类。一类着重介绍了钱学森先生的风范，他的爱国主义，他的勤奋好学，他的治学精神和治学态度，他在学术上的重大贡献以及他的科学思想。第二类是介绍在他的领导或影响下，五十年来我国力学研究取得的成就及进一步的进展。第三类涉及我国力学界正在开展的其他方面的学术研究进展。我们的共同目的是继承优良传统，开拓我国力学在新世纪的发展。

　　读者对象：力学、航空航天、机械等领域的工程技术人员，研究人员。

稀薄气体动力学

der="0" alt="" hspace="8" width="100" height="100" align="left" />通常的气体动力学方法，当气体分子的平均自由程与流场特征长度相比不可忽略时，不再适用，要采用稀薄气体动力学的方法。这适用于航天飞行器在高空飞行时受的力和热，也适用于微机电系统和真空系统等离子体材料加工等21世纪技术前沿领域。本书系统、简明地阐述稀薄气体动力学方法，给出方法的基础并着重介绍直接模拟Monte Carlo(DSMC)方法以及与低速稀薄气体流动相关的前沿课题。全书共分7章。前两章是作为学科的基础引入的，第1章以空气为对象对于分子能态结构、能态分布以极小篇幅作了简要概括的叙述，以作为了解稀薄气流非平衡现象物理基础的初步。第2章对包括双体碰撞、Boltzmann方程以及气体的平衡态等分子动理论的基础做了必要的讨论，其中包括了对唯像论分子相互作用模型、变径硬球（VHS）、变径软球（VSS）和概括化硬球（GHS）等模型的介绍。第3章讨论了各种分子和表面的相互作用模型，包括反映细致平衡的互易原理和基于此原理的CLL模型的阐述。第4章讨论自由分子流。第5章讨论应用于滑流领域的各连续介质方程及滑流边界条件，一些简单解以及热泳问题。第6章则较全面、概括地介绍了求解过程领域中的各种解析和数值方法。第7章介绍了直接模拟Monte Carlo(DSMC)方法，讨论了非平衡流动及低速稀薄流动等前沿课题，包括处理内能松弛、化学反应的方法、用于复杂流场通用软件的方法、低速稀薄流动的信息保存（IP）方法等。　　本书适合高等学校力学一航空航天专业高年级学生、研究生及从事气动力学和航天研究的科研人员参考阅读。

通常的气体动力学方法，当气体分子的平均自由程与流场特征长度相比不可忽略时，不再适用，要采用稀薄气体动力学的方法。这适用于航天飞行器在高空飞行时受的力和热，也适用于微机电系统和真空系统等离子体材料加工等21世纪技术前沿领域。本书系统、简明地阐述稀薄气体动力学方法，给出方法的基础并着重介绍直接模拟Monte Carlo(DSMC)方法以及与低速稀薄气体流动相关的前沿课题。

符号表
绪论
第1节 稀薄气体动力学的提出
第2节 气体的分子模型
第3节 分子平均自由程
第4节 流动的领域划分
第5节 非平衡现象与稀薄气体动力学
第6节 相似准则
第1章 分子结构与能态
第1节 双原子分子
第2节 分子的能态分布
第3节 分子的内能、内自由度和内能分布函数
第2章 分子动理论基础
第1节 速度分布函数
第2节 宏观量的表达
第3节 分子的双体碰撞模型
第4节 碰撞截面与分子模型
第5节 Boltzmann方程
第6节 碰撞积分与气体分子的总碰撞数
第7节 碰撞积分的计算
第8节 Maxwell输运方程——矩方程
第9节 Maxwell分布
第10节 气体的平衡态
第11节 8速度气体模型
第12节 混合气体
第3章 分子表面相互作用
第1节 引言
第2节 镜面反射与漫反射，适应系数
第3节 互易性原理
第4节 CLL分子表面相互作用模型
第4章 自由分子流
第1节 气体中的分子数目通量和动量通量
第2节 作用于物体的气动力
第3节 表面元素的热传导
第4节 自由分子流出与热流逸
第5节 Couette流动与平板间的传热问题
第6节 无碰撞Boltzmann方程的通解，非定常流动
第5章 连续介质模型
第1节 引言
第2节 基本方程
第3节 滑流边界条件
第4节 一些简单问题的求解
第5节 热蠕动与热泳
第6章 过渡领域
第1节 概述
第2节 线化的BoltzmanN方程
第3节 矩方法
第4节 模型方程
第5节 有限差分法
第6节 间断纵坐标方法
第7节 积分方法
第8节 直接模拟方法
第7章 直接模拟Monte方法
第1节 引言
第2节 碰撞的取样
第3节 DSMC方法求解问题实例
第4节 内能的激发与松弛
第5节 化学反应的模拟
第6节 复杂流场的计算，位置元方法
第7节 微尺度低速气体流动，信息保存法
附录I 气体的性质和分子性质
附录II 分布函数求矩遇到的积分
附录III 具有给定分布的随机数的取样
附录IV Couette问题程序
参考文献
主题词索引

Year class mortality, abundance and yield-per-recruit of yellowfin tuna in the eastern Pacific Ocean, 1954-1959

ENGLISH: One primary duty of the Inter-American Tropical Tuna Commission is to estimate the maximum sustainable catches of yellowfin tuna (Neothunnus macropterus) and skipjack (Katsuwonus pelamis), and to investigate and recommend proposals to maintain the stocks at levels which will permit these catches to be obtained. To do this, there is required some means of predicting yields relative to fishing intensity. . . The age composition of catch, and growth rate of yellowfin tuna for recent years have now been estimated (Hennemuth, 1961). In this paper, relative abundance at age of yellowfin tuna shall be estimated -and used, in turn, to estimate total mortality rate. Yield-per-recruit calculations, based on Beverton and Holt's (1957) simple equation, will be presented to compare present utilization with theoretical maxima under varying levels of fishing mortality and different ages at first capture. SPANISH: Uno de los principales deberes de la Comisión Interamericana del Atún Tropical es estimar las pescas máximas sostenibles de los atunes aleta amarilla (Neothunnus macropterus) y barrilete (Katsuwonus pelamis) , así como estudiar y recomendar proposiciones para mantener los stocks a niveles que permitan obtener estas pescas. Para lograr este propósito se requieren algunos medios que permitan predecir el rendimiento en relación con la intensidad de la pesca. . La composición de edades de la pesca y la tasa de crecimiento del atún aleta amarilla en años recientes han sido estimadas ahora (Hennemuth, 1961). En este trabajo, la abundancia relativa a una edad dada de esta especie será estimada y usada, a su vez, para estimar la tasa de mortalidad total. Los cálculos del rendimiento por recluta, basados en la ecuación simple de Beverton y Holt (1957), serán presentados para comparar la utilización actual con los máximos teóricos bajo valores variables de mortalidad por la pesca y a diferentes edades a la primera captura.