Optimized hand fabricated AFM probes for simultaneous topographical and electrochemical tapping mode imaging

In this work hybrid AFM-electrochemical (SECM) probes to be used in dynamic atomic force microscopy are presented. These nanosensors are hand fabricated from gold microwires using a simple benchtop method. They display proportions close to commercially available silicon and silicon nitride cantilevers giving comparable performance in terms of resolution and imaging stability. The remarkable characteristic of these hybrid nanosensors is that they allow the coupling of 3D imaging ability and versatility of atomic force microscopy with the power of electrochemical methods. Local measurement of electrochemical-activity of a test sample consisting of gold bands functionalized by redox-labeled nanometer-sized polyethylene glycol chains has been achieved with simultaneous imaging of the 3D surface topography at high resolution. These hybrid AFM-SECM tips are capable of sensing local electrochemical currents down to ∼10 fA emphasizing the sensitivity and resolution of this technique.     

Interactive view-dependent rendering over networks

For a client-server based view-dependent rendering system, the overhead of view-dependent rendering and the network latency are major obstacles in achieving interactivity. In this paper, we first present a multiresolution hierarchy traversal management strategy to control the overhead of view-dependent rendering for low-capacity clients. Then we propose a predictive parallel strategy to overcome the network latency for client-server based view-dependent multiresolution rendering systems. Our solution is to make the client process and the server process run in parallel, using the rendering time to cover the network latency. For networks with long round-trip times, we manage to overlap the network latency for one frame with the rendering time for multiple frames. View-parameters prediction is incorporated to make the parallelism of the client and the server feasible. In order to maintain an acceptable view-dependent rendering quality in the network environment, we develop a synchronization mechanism and a dynamic adjustment mechanism to handle the transient network slowdowns and the changes of the network condition. Our experimental results, in comparison with the sequential method, show that our predictive parallel approach can achieve an interactive frame rate while keeping an acceptable rendering quality for large triangle models over networks with relatively long round-trip times.     

Structural stability of linear dynamically varying (LDV) controllers

LDV systems are linear systems with parameters varying according to a nonlinear dynamical system. This paper examines the robust stability of such systems in the face of perturbations of the nonlinear system. Three classes of perturbations are examined: differentiable functions, Lipschitz continuous functions and continuous functions. It is found that in the first two cases the system remains stable. Whereas, if the perturbations are among continuous functions, the closed-loop may not be asymptotically stable, but, instead, is asymptotically bounded with the diameter of the residual set bounded by a function that is continuous in the size of the perturbation. It is also shown that in the case of differential perturbations, the resulting optimal LDV controller is continuous in the size of the perturbation. An example is presented that illustrates the continuity of the variation of the controller in the case of a nonstructurally stable dynamical system.     

硬盘消失之谜

羡慕我吧？最新的H55主板加i5661。由于不太玩3D游戏,所以并没有搭载独立显卡,不过硬盘倒是挂得满满的。因为咱是高清玩家,所以硬盘里塞满了30Mbps以上的高清电影。3个500GB的硬盘和三个1TB的硬盘几乎都要被填满了,于是最近又加了一个新的1TB硬盘,装在了第三方芯片组控制的两个SATA接口上。     

Nitrogen budget for the Oldman River Basin, southern Alberta, Canada

The Oldman River Basin (OMRB), located in southern Alberta (Canada), with an area of 28,200 km², is mainly forested in its western part and is used for intensive agriculture in its eastern part. The objective of this paper is to estimate the nitrogen (N) budget for the Oldman River Basin as a whole and its sub-basins, and to discuss differences in the N budget between various sub-basins. Better knowledge of the N budget in this watershed may be also utilized for understanding N dynamics in similar watersheds within semi-arid climatic regions. The model used is a mass-balance spreadsheet model that takes into account N inputs and N export through surface water. During the last 120 years, anthropogenic N inputs to the OMRB have increased circa 40 fold. By the end of the 20th century, the OMRB received an annual N input of about 5174 kg N km⁻² yr⁻¹, whereas only about 25 kg N km⁻² yr⁻¹ were exported via riverine flow. For the sub-basins, annual N inputs ranged from 2516 to 19011 kg N km⁻² yr⁻¹, and annual N export via riverine flows varied between 6 and 277 kg N km⁻² yr⁻¹. Over 85% of total N inputs to the OMRB are due to anthropogenic activities, including manure (55%), synthetic fertilizer (27%), and N fixation on agricultural lands (4%). Sewage accounted for less than 1%, and N inputs from atmospheric deposition and fixation in forests represented 6 and 8% respectively. Despite increasing anthropogenic N inputs, N export with riverine flow currently accounts for only 1% of the inputs, indicating that most of the N inputs are currently retained in the OMRB or are re-emitted into the atmosphere.     

超频你的Firefox

你知道Firefox可以通过内部的一些设置．加快浏览网页的速度吗?不管你的电脑和网络是快是慢，Firefox都可以为你量身定做，将你的上网速度提到最高点。     

Psychological Processes Underlying Risky Decisions in Drug Abusers.

Decision-making deficits are considered to be a significant contributing factor for drug abuse. Drug abusers performed poorly on a simulated gambling task (A. Bechara, H. Damasio, D. Tranel, & S. Anderson, 1994); however, the psychological processes that contribute to these deficits are unknown. The authors used cognitive decision models with a simulated gambling task (SGT) to examine underlying processes of decision making in 66 drug abusers and 58 control participants. As expected, male drug abusers performed more poorly than male controls, and model results showed that male drug abusers placed greater emphasis on wins. The findings for women were less clear because control women performed at chance level on the SGT. Additional studies of gender differences on the SGT are needed to clarify these findings of discrepant performance in the control women. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

建立岩土本构模型的数值方法

根据反问题的理论,阐明了建立岩土本构模型属于反问题,提出了建模的四个基本步骤.在试验数据中蕴藏着应力应变关系的信息,直接提炼本构规律是可能的.神经网络是强有力的反演工具,借助于它建立了砂土和粘性土的非线性和弹塑性神经网络模型.研究结果表明,这种数值建模方法具有许多优越性,已成为求解边值问题的主要工具,也必将在建立岩土本构模型中发挥重要作用.     

Finite-Time Sideslip Differentiator-Based LOS Guidance for Robust Path Following of Snake Robots

This paper presents a finite-time sideslip differentiator-based line-of-sight(LOS) guidance method for robust path following of snake robots. Firstly, finite-time stable sideslip differentiator and adaptive LOS guidance method are proposed to counteract sideslip drift caused by cross-track velocity. The proposed differentiator can accurately observe the cross-track error and sideslip angle for snake robots to avoid errors caused by calculating sideslip angle approximately. In our method, the des...