Recognizing the importance of scale in the ecology and management of riverine fish

Processes affecting fish populations range in scale from local to global. Fish response is also scale‐dependent, with some activities varying locally while others depend on large‐scale connectivity within or between watersheds. These issues are still only partly recognized, with large‐scale research often affected by non‐independent sampling, weak inference, poor model testing or model over‐extrapolation. Available multi‐scale studies can reach different conclusions about factors affecting fishes from local studies, but results vary between examples. Potential explanations are (i) effects on fishes are context‐dependent; (ii) different species or life‐stages are limited in different ways; (iii) multi‐scale studies are too few for generalization. We advocate improved use of geostatistical tools to guide sampling or interpret the spatial extent of management problems, and we illustrate this using brown trout in Welsh streams. Our strongest recommendation is that fish ecologists recognize the importance of interactions across scales in quantifying effects on fishes so that management decisions can be better based on evidence rather than judgement or extrapolation. Copyright © 2006 John Wiley & Sons, Ltd.     

Accurate Depth of Field Simulation in Real Time

We present a new post processing method of simulating depth of field based on accurate calculations of circles of confusion. Compared to previous work, our method derives actual scene depth information directly from the existing depth buffer, requires no specialized rendering passes, and allows easy integration into existing rendering applications. Our implementation uses an adaptive, two‐pass filter, producing a high quality depth of field effect that can be executed entirely on the GPU, taking advantage of the parallelism of modern graphics cards and permitting real time performance when applied to large numbers of pixels.     

激光光束质量因子的研究进展

本文详细分析了各种光场下光束质量M2因子。在不同的场中,A.E.Siegman当初所定义的M2因子,已经有了很大的变化,因而M2因子的特性也与当初不同,不仅M2因子可以大于等于1,而且可以小于1,甚至小于0。其反映的物理意义,也从经典场中的衍射极限倍数,变化为非经典场中的准直性量度以及对空间相干性的某些反映。此外还列举并分析了几种特殊的光束质量因子,最后讨论了M2因子应用的问题并指出了其局限性。     

小径落叶松材制作空间网架杆件的选择与设计

通过对小径落叶松材的力学性能、与金属套筒连接性能及胶粘剂的选择试验,设计用小径落叶松材制作空间网架,扩大了小径材在建筑领域的使用范围。     

机械制图虚拟实验室的研究与设计

论述了一个网络化，信息化实验系统开发的方法和思路。该系统以虚拟技术为支撑，以图学教育的宗旨为核心，综合利用了虚拟技术的各种开发工具和理论，具有虚拟现实系统常有的特点，沉浸感，交互性，构想。     

Preliminary Study in Spatial Data Warehouse of Flood Control and Disaster Mitigation in Yangtze River Basin

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"Recovery of spatial alternation deficits following selective hippocampal destruction with kainic acid": Correction to Kesslak and Gage (1986).

Reports an error in "Recovery of spatial alternation deficits following selective hippocampal destruction with kainic acid" by J. Patrick Kesslak and Fred H. Gage (Behavioral Neuroscience, 1986[Apr], Vol 100[2], 280-283). In the aforementioned article, the degrees of freedom reported in the Results section are incorrect. In the sixth paragraph on page 281, the second sentence should read as follows: Results of the ANOVA indicated a significant effect for surgical treatments. F(2, 25)=25.44, p1986-21445-001.) Examined whether the sympathetic ingrowth of superior cervical ganglion (SCG) fibers sprouting into the hippocampus following kainic acid (KA) lesion of CA3 and CA4 pyramidal cells in male Sprague-Dawley rats would contribute to behavioral recovery. 31 Ss were trained on a forced-choice task. After reaching criterion performance levels, Ss received either KA (8 nM/0.4 μl) or saline injections into the hippocampus and were again tested on the forced-choice task. Half of the Ss had their SCG removed 35 days after injections, and all were again tested on the forced-choice task. Analysis of variance (ANOVA) showed Ss receiving KA took significantly longer to reach criterion following injections. Removal of the SCG after recovery reintroduced the performance deficit of KA-treated Ss on the alternation task; no other group showed any effect for SCG removal. Results indicate that the SCG may have a modulatory effect in behavioral recovery, although other mechanisms may also be operating. (22 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Analysis of polarization plane rotation characteristic in 2D photonic crystal waveguide with chiral medium by condensed node spatial network

Using the photonic band gap in photonic crystals, the fundamental waveguide structures for the light wavelength range have been developed. Based on the fine structure of these many functional devices have been proposed by analytical or numerical simulation methods and the experiments of trial manufacture. In this paper, the treatment of chiral dielectric in the Condensed Node Spatial Network for the vector potential is explained, and we show the polarization plane rotation property in air‐hole and pillar type photonic crystal waveguide structures with the chiral medium substrate. Then, we show the fundamental advantage of the air‐hole type photonic crystal waveguide structure in application to a mode converter. © 2005 Wiley Periodicals, Inc. Electr Eng Jpn, 152(1): 7–14, 2005; Published online in Wiley InterScience ( www.interscience. wiley.com ). DOI 10.1002/eej.20098     

一种降低电离层梯度影响的Hatch滤波算法

目前,地基增强系统（Ground-Based Augment System,GBAS）中的主要问题是：尽管使用载波平滑降低了伪距噪,利用差分技术消除了用户和基准站间的大部分共同误差,从而减少了差分改正值中的误差。但是电离层时间梯度和空间梯度于这两个过程中产生了额外的误差,阻碍了差分改正值质量的进一步提高。基于对电离层时间和空间梯度引起的额外误差的分析,并考虑平滑伪距噪声,文章提出了一种新的Hatch滤波方法,该滤波器的时间常数是随卫星仰角、电离层时间和空间梯度以及用户与参考站之间的距离而实时变化的。该方法降低了差分改正值误差,提高了定位精度。并且通过差分定位仿真并对比传统的单频Hatch滤波方法,发现使用该方法后,减小了差分校正值的误差。     

基于MultiGen Creator/Vega的校园虚拟现实研究

VR与GIS相结合是VR技术的一个非常重要的应用,是实现＂数字地球＂、＂数字城市＂、＂数字区域＂等的关键技术之一。以武汉大学信息学部教学区为研究区域,利用教学区的航空影像、数字化地图、实测数据以及区内建筑物的数字影像,在MultiGen Creator/Vega软件平台上建立该区域的虚拟现实场景,实现三维模型漫游。并将此场景用于GIS,实现了GIS属性查询功能。