基于自适应帧聚合机制的无线局域网吞吐量分析

在分析IEEE 802.11n中A-MSDU和A-MPDU两种MAC层帧聚合机制的基础上,针对MAC层帧聚合中子帧必须使用相同调制编码方式以及具有最大帧长限制的问题,引入物理层超帧,并采用自适应帧聚合机制来改善系统的吞吐量性能.推导了有扰信道下采用DCF接入机制时各类帧聚合以及帧分段方式在饱和状态的吞吐量,讨论了网络站...     

An energy conduction model for cell image segmentation

Cell image segmentation is an essential step in cytopathological analysis.Although their execution speed is fast,the results of cell image segmentation by conventional pixel-based,edge-based and continuity-based methods are often coarse.Fine structures in a cell image can be obtained with a method that quickly adjusts the threshold levels.However,the processing time of such a method is usually long and the final results may be sensitive to intensity differences and other factors.In this article,a new energy model is proposed that synthesizes a differential equation from the conventional and level set methods,and utilizes the nonuniformity property of cell images (e.g.cytoplasms are more uneven than the background).The feasibility and robustness of the proposed model was demonstrated by processing relatively complicated background images of both simulated and real cell images.     

“大学英语”合作教学法在课堂的应用

合作学习是一种富有创意和实效的教学理论与策略体系。将合作学习的理念引入大学英语教学之中,能对学生的英语应用能力、与他人的合作能力、自主学习能力以及竞争意识进行全方位的培养。本文对合作学习在大学英语课堂中的教学过程和实际操作进行实证探讨,得出积极的效果。     

平面上的随机Dirichlet级数

研究了全平面上随机Dirichlet级数的增长性性质.在文中条件(3)限制下得到了增长级的性质.     

Integrative genomics identifies MCU as an essential component of the mitochondrial calcium uniporter

Mitochondria from diverse organisms are capable of transporting large amounts of Ca(2+) via a ruthenium-red-sensitive, membrane-potential-dependent mechanism called the uniporter. Although the uniporter's biophysical properties have been studied extensively, its molecular composition remains elusive. We recently used comparative proteomics to identify MICU1 (also known as CBARA1), an EF-hand-containing protein that serves as a putative regulator of the uniporter. Here, we use whole-genome phylogenetic profiling, genome-wide RNA co-expression analysis and organelle-wide protein coexpression analysis to predict proteins functionally related to MICU1. All three methods converge on a novel predicted transmembrane protein, CCDC109A, that we now call 'mitochondrial calcium uniporter' (MCU). MCU forms oligomers in the mitochondrial inner membrane, physically interacts with MICU1, and resides within a large molecular weight complex. Silencing MCU in cultured cells or in vivo in mouse liver severely abrogates mitochondrial Ca(2+) uptake, whereas mitochondrial respiration and membrane potential remain fully intact. MCU has two predicted transmembrane helices, which are separated by a highly conserved linker facing the intermembrane space. Acidic residues in this linker are required for its full activity. However, an S259A point mutation retains function but confers resistance to Ru360, the most potent inhibitor of the uniporter. Our genomic, physiological, biochemical and pharmacological data firmly establish MCU as an essential component of the mitochondrial Ca(2+) uniporter.     

基于对称损失函数下Poisson分布变异系数的估计

对应用统计中常用的参数Karl-Pearson变异系数,在给定的一组Poisson样本下,用对称损失函数研究了它的Bayes估计的形式与性质,并由此讨论了它的一类估计的可容许性和不可容许性,模拟结果表明:所得到的Karl-Pearson变异系数的Bayes估计具有较高的精度,可以在统计判决问题中使用.     

水稻转座子Pong特异性RNAi载体TPAS的构建和农杆菌介导的遗传转化条件的优化

为研究水稻转座子Pong的功能,构建了Pong的特异RNAi表达载体TPAS,并利用农杆菌介导法将这个载体转化到水稻的成熟胚愈伤组织,获得了PCR阳性的再生植株.同时通过对农杆菌侵染途径、侵染浓度和侵染时间等的研究,建立并优化了水稻的遗传转化程序,结果表明:在农杆菌侵染成熟胚愈伤组织的时间为3 min,共培养2～4 d...     

土壤有机质测定方法对比分析

采用不同方法(TOC分析仪法、550℃烧失量法、950℃烧失量法和水合热重铬酸钾氧化比色法)测定长江底沉积物标准物质中有机质含量,并分析不同测定方法的准确度、精密度及对测定土壤有机质含量的影响,结果表明:在实验准确度和精密度方面,TOC分析仪法最高,950℃烧失量法最低.采用以上4种方法对南京秦淮河沿程5个断面采取的表...     

全息条纹读数仪法在生物固体力学及振动定量分析中的应用

本文提出了采用全息条纹三维读数仪法与双曝光全息法相结合,对人体颅骨颞部和额窦部受集中载荷时的三维位移场进行定量分析;与夹层全息干涉法等相结合,对矫齿时施行上颌快速扩大术之牙颌变化进行定量分析;用以研究矫齿力的各种参数及牙颌组织变化;与频闪全息法相结合,对小提琴桥马的三维振动位移场进行定量分析。测点上之三维位移值都由微机处理、计算得到.     

半导体陶瓷湿敏机理的探讨

对多孔半导体陶瓷的湿敏机理做了定量分析．我们把整个湿度范围分成高湿区和低湿区，针对不同的湿度区，建立了两种不同的电导模型．通过理论推导，得出了电阻与相对湿度关系的解析表达式．