Inositol (1,4,5)-triphosphate Modulates Pollen Tube Polar Growth

Pollen tube is characterized by polarized elon-gation at the apex. Through polar growth, pollentube drives the sperm cells into the ovary to fulfillfertilization. So this process is essential for higherplants sexual propagation and food production[1].During finding its way to the ovary, pollen tubeshould always adjust its growth direction accordingto the external signals that are subsequently con-verted to the internal signals on plasma membrane.Ins(1,4,5)P3is one of such second messengers in…     

An Object-Based Fast Motion Estimation Algorithm in MPEG-4

Introduction The MPEG has successfully developed theMPEG-4 standard[1]to address a wide range ofmultimedia data compression applications. As oneof the major parts of MPEG-4 standard, MPEG-4video aims at providing standardized core technolo-gies allowing efficient storage, transmission andmanipulation of video data in multimedia environ-ments[2]. Compared with its predecessor, MPEG-4 em-ploys many new compression techniques[3]. One ofthe main new features of MPEG-4 is its ability tore…     

双变流器—电机能量互馈式试验平台控制系统

针对大功率变频试验平台能耗大、对电网干扰大的特点,提出双变流器-电机能量互馈式试验平台控制系统,阐述其硬、软件控制的特点.试验和波形表明该方案是可行的.     

列车运行速度及走行距离测试的原理分析

推导了列车运行速度、走行距离与测速发电机输出电压频率的数学关系式，给出了利用ＣＭＯＳ数字集成电路和频率合成原理实现上述关系的电路框图，并对其速度接口电路、轮径输入方法及频率合成电路、分频电路和ＢＣＤ比例乘法器电路、显示电路、基准频率发生电路、电源电路等作了分析与说明。通过大量测量，获得了准确可靠的数据，表明电路设计是正确的。     

四冲程船用柴油机的建模和实时仿真

根据准稳态的概念，在充分多的试验数据的基础上，结合工作原理建立了适用于实时仿真的四冲程船用柴油机推进装置的多阶非线性动态模型。这种模型能反映柴油机内部各参数，精度较高，计算工作量适中。     

基于四因素指数的区域公路网布局形态比较分析

为提高公路网对经济社会发展的适应性,针对区域公路网布局优化问题,以建设成本、土地占用机会成本、运输成本、公路网使用效率四因素为决策变量,构建公路网四因素指数.根据公路交通资源的分布特征将区域公路网布局形态划分为分散型布局和集中型布局,以四因素指数为支撑,对两种布局形态的性能特征进行比较分析,从三节点公路网的布局形态入手,分析节点位置、交通需求分布对两种布局形态四因素指数的作用规律,最后以广州—湛江运输通道为例,分析复杂情景下两种布局形态的四因素指数.研究结果表明:公路网四因素指数可综合反映公路网系统功能及其对社会经济发展的贡献,方便布局方案的评价和比选;集中型布局在土地集约利用、交通运行效率等方面具有明显优势,是区域公路网布局优化的有效选择.     

北京经济技术开发区4S店区域停车问题研究

为探讨停车相关技术、政策,优化区域交通环境,以北京经济技术开发区汽车4S店为研究 对象,通过对停车设施的数量及利用率的调查,分析4S 店区域的停车现状。从4S 店区域停车需 求多样性入手,分析其内部停车需求与外部停车需求,考虑公共停车场、路内停车场、停车管理 政策及公共交通问题,统筹动态交通和静态交通两方面,协调供需发展关系,提出4S 店区域停 车问题的解决对策：挖掘停车潜力、建立立体停车库、施划路内停车、扩大停车设施供给,以满 足内部停车需求;实行车位共享,规范路内停车,推进区域信息化,以满足外部停车需求;优化 停车管理政策、加快发展公共交通、加大违法停车处罚力度、提高合法停车意识,以引导交通出 行者;各种措施应相互配合,以缓解4S店区域停车压力。     

NT4p53(C22)Ant融合基因重组腺病毒的构建及对肝癌细胞的杀伤作用

目的构建编码融合基因NT4p53(C22)Ant嵌合肽的重组腺病毒表达载体,并研究其对人肝癌HepG2细胞的杀伤作用。方法使用分子克隆技术,通过同源重组获得重组腺病毒rAVV-NT4p53(C22)Ant,收集上清、大量扩增并测定其滴度。感染人肝癌HepG2细胞,采用免疫组化法检测p53表达,MTT实验、流式细胞仪观察rAAVNT4p53(C22)Ant对肿瘤细胞的杀伤作用。结果成功构建重组腺病毒表达载体,感染人肝癌HepG2细胞后p53表达率为(44.88±2.45)%;MTT检测显示,细胞存活率随作用时间延长明显降低,与空病毒组及对照组比较差异均有统计学意义(P<0.05),流式细胞仪检测显示G0/G1期细胞比例及凋亡细胞较空病毒组及对照组增加。结论构建的NT4p53(C22)Ant重组腺病毒在肝癌细胞中能有效表达,对肝癌HepG2细胞有抑制增殖和促进凋亡的作用。     

Comparisons of vehicle stability controls based on 4WS,Brake, Brake-FAS and IMC techniques

This paper proposes three different kinds of vehicle stability control systems all based on internal model control (IMC) strategy which are 4WS (4 wheel steer: front- and rear-wheel active steer) IMC, Brake-FAS (brake and front-wheel active steer) IMC and Brake IMC, respectively. Inverse system method is introduced to solve the nonlinearity coupled with brake involved vehicle stability control systems. Based on an 11-DOF (degrees of freedom) Matlab/Simulink^® vehicle model testified by CarSim7^®, simulations combined with different driving manoeuvres and road surfaces are performed, and detailed comparisons and analyses are given based on simulation results.     

Real time assimilation of HF radar currents into a coastal ocean model

A real time assimilation and forecasting system for coastal currents is presented. The purpose of the system is to deliver current analyses and forecasts on based on assimilation of high-frequency radar surface current measurements. The local Vessel Traffic Service monitoring the ship traffic to two oil terminals on the coast of Norway received the analyses and forecasts in real time.A new assimilation method based on optimal interpolation is presented where spatial covariances derived from an ocean model are used instead of simplified mathematical formulations. An array of high frequency radar antennae provides the current measurements. A suite of nested ocean models comprises the model system. The observing system is found to yield good analyses and short range forecasts that are significantly improved compared to a model twin without assimilation. The system is fast, analysis and 6-h forecasts are ready at the Vessel Traffic Service 45 min after acquisition of radar measurements.