468 research outputs found

    ダッチアイリスの休眠を調節する要因に関する研究, 特にホルモン的観点より

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    京都大学0048新制・論文博士農学博士乙第2809号論農博第585号新制||農||201(附属図書館)学位論文||S50||N783(農学部図書室)4626UT51-50-J372(主査)教授 塚本 洋太郎, 教授 深海 浩, 教授 瀧本 敦学位規則第5条第2項該当Kyoto UniversityDA

    Approximating the longest path length of a stochastic DAG by a normal distribution in linear time

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    AbstractThis paper presents a linear time algorithm for approximating, in the sense below, the longest path length of a given directed acyclic graph (DAG), where each edge length is given as a normally distributed random variable. Let F(x) be the distribution function of the longest path length of the DAG. Our algorithm computes the mean and the variance of a normal distribution whose distribution function F˜(x) satisfies F˜(x)⩽F(x) as long as F(x)⩾a, given a constant a (1/2⩽a<1). In other words, it computes an upper bound 1−F˜(x) on the tail probability 1−F(x), provided x⩾F−1(a). To evaluate the accuracy of the approximation of F(x) by F˜(x), we first conduct two experiments using a standard benchmark set ITC'99 of logical circuits, since a typical application of the algorithm is the delay analysis of logical circuits. We also perform a worst case analysis to derive an upper bound on the difference F˜−1(a)−F−1(a)

    High-speed atomic force microscopy for observing protein molecules in dynamic action

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    Directly observing protein molecules in dynamic action at high spatiotemporal resolution has long been a holy grail for biological science. To materialize this long quested dream, I have been developing high-speed atomic force microscopy (HS-AFM) since 1993. Tremendous strides were recently accomplished in its high-speed and low-invasive performances. Consequently, various dynamic molecular actions, including bipedal walking of myosin V and rotary propagation of structural changes in F1-ATPase, were successfully captured on video. The visualized dynamic images not only provided irrefutable evidence for speculated actions of the protein molecules but also brought new discoveries inaccessible with other approaches, thus giving great mechanistic insights into how the molecules function. HS-AFM is now transforming "static" structural biology into dynamic structural bioscience. © 2017 SPIE

    High-speed atomic force microscopy coming of age

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    High-speed atomic force microscopy (HS-AFM) is now materialized. It allows direct visualization of dynamic structural changes and dynamic processes of functioning biological molecules in physiological solutions, at high spatiotemporal resolution. Dynamic molecular events unselectively appear in detail in an AFM movie, facilitating our understanding of how biological molecules operate to function. This review describes a historical overview of technical development towards HS-AFM, summarizes elementary devices and techniques used in the current HS-AFM, and then highlights recent imaging studies. Finally, future challenges of HS-AFM studies are briefly discussed. © 2012 IOP Publishing Ltd

    Video imaging of biomolecular processes by high-speed AFM

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    金沢大学理工研究域数物科学系The imaging rate of conventional atomic force microscopy (AFM) is too low to capture the dynamic behavior of biomolecules. To overcome this problem, we have been developing various devices and techniques, including small cantilevers and high-speed scanners. The feedback bandwidth in the tapping-mode now exceeds 100 kHz and hence the maximum possible imaging rate reaches 25 frames per sec (fps). Importantly the tip-force exerting onto the sample is dramatically reduced. Thus, it is now possible to take video images of dynamically moving protein molecules in action without disturbing their function, including walking myosin V molecules along actin tracks

    Techniques developed for high-speed AFM

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    This article describes fundamental devices and control techniques that have materialized high-speed atomic force microscopy (AFM) capable of recording dynamic processes of individual biomolecules on video at an imaging rate of 10-25 frames/s, without disturbing their biological functions. © 2011 Springer-Verlag Berlin Heidelberg

    Molecular machines directly observed by high-speed atomic force microscopy

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    Molecular machines made of proteins are highly dynamic and carry out sophisticated biological functions. The direct and dynamic high-resolution visualization of molecular machines in action is considered to be the most straightforward approach to understanding how they function but this has long been infeasible until recently. High-speed atomic force microscopy has recently been realized, making such visualization possible. The captured images of myosin V, F1-ATPase, and bacteriorhodopsin have enabled their dynamic processes and structure dynamics to be revealed in great detail, giving unique and deep insights into their functional mechanisms. © 2013 Federation of European Biochemical Societies
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