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Actin-binding domain of Rng2 sparsely bound on F-actin strongly inhibits actin movement on myosin II
Get PDFWe report a case in which sub-stoichiometric binding of an actin-binding protein has profound structural and functional consequences, providing an insight into the fundamental properties of actin regulation. Rng2 is an IQGAP contained in contractile rings in the fission yeast Schizosaccharomyces pombe. Here, we used high-speed atomic force microscopy and electron microscopy and found that sub-stoichiometric binding of the calponin-homology actin-binding domain of Rng2 (Rng2CHD) induces global structural changes in skeletal muscle actin filaments, including shortening of the filament helical pitch. Sub-stoichiometric binding of Rng2CHD also reduced the affinity between actin filaments and muscle myosin II carrying ADP and strongly inhibited the motility of actin filaments on myosin II in vitro. On skeletal muscle myosin II–coated surfaces, Rng2CHD stopped the actin movements at a binding ratio of 11%. Rng2CHD also inhibited actin movements on myosin II of the amoeba Dictyostelium, but in this case, by detaching actin filaments from myosin II–coated surfaces. Thus, sparsely bound Rng2CHD induces apparently cooperative structural changes in actin filaments and inhibits force generation by actomyosin II.journal articl
Dielectric response in the antiferromagnetic phase of Fe1.10Te
Get PDFFe1.10Te was studied by scanning tunneling microscopy (STM) and dielectric response to elucidate the charge fluctuation. The cleaved a-b surface was clearly imaged by UHV-STM at T = 8.3 K. From the line profiles, each Fe site was thought to be equivalent suggesting no static charge order in the antiferromagnetic phase. The temperature dependence of the dielectric permittivity was obtained by measuring the complex impedance. The dielectric permittivity increased with decreasing temperature below the Neel temperature TN. The temperature dependence followed the Curie law, indicating the paraelectric state. It suggests charges fluctuate dynamically in the antiferromagnetic state. We conclude that the dynamical charge fluctuation cooperates with the antiferromagnetic order in Fe1.10Te.journal articl
ESTIMATING TRIP PURPOSES OF A SHARED BICYCLE SYSTEM APPLYING A MACHINE LEARNING
Get PDF近年，日本を含む多くの国でシェアリングサイクルのサービスが拡大している．シェアサイクルの今後の発展や，利用状況の改善には利用者ニーズの把握は必要不可欠である．一方で，無人管理シェアサイクルが多い日本においては利用者ニーズの収集は困難である．そこで本研究では，利用実績データとアンケ ートデータ，ポート周辺の建物面積データを組み合わせ，機械学習モデルであるランダムフォレストモデル及びXGBoostモデルを適用することで，利用目的を推定するモデルを構築した．SHAP指標を用いて各モデルを解釈した結果，移動距離や移動開始時刻が利用目的を判別するうえで重要な説明変数であることが示された．また複数年度の利用実績データにモデルを適用し，利用者の行動変化を把握した．In recent years, shared cycle services have expanded in many countries, including Japan. Understanding the needs of users is essential for the future development of shared-cycle services and for improving their usage. On the other hand, it is difficult to collect user needs in Japan, where there are many unmanned shared-cycle services. In this study, we constructed a model to estimate the purpose of use by combining actual use data, questionnaire data, and building area data around ports, and applying machine learning models, Random Forest Model and XGBoost Model, to the model. The results of interpreting each model using the SHAP indicator indicated that travel distance and travel start time were important explanatory variables in determining the purpose of use. In addition, we applied the models to the actual usage data for multiple years to understand changes in user behavior.journal articl
弾性梁を持つ歩行型圧電リニアアクチュエータの性能と操作機能に関する研究
Get PDF室蘭工業大学Muroran Institute of Technology博士（工学）精密位置決め分野の急速な発展に伴い，高精度、高速応答、大ストロークの特徴を持つ圧電アクチュエータへの需要が増加している。過去数十年にわたり，様々な非共振型圧電アクチュエータが登場し，バイオ技術，光学機器，マイクロ/ナノ位置決めプラットフォーム，半導体技術など， 多くの産業分野で応用に成功している。しかし，既存の非共振圧電アクチュエータにはまだ限界がある。例えば，半導体製造におけるリソグラフィプロセスのモニタリングに使用される走査型電子顕微鏡（ SEM）のアパーチャーの駆動など 1）大きなストロークを伴う低速駆動，（ 2）逆方向に動作しない 3）高い位置決め分解能，が要求される特定の精密位置決めアプリケーションにおいて，既存の圧電アクチュエータでは十分とは言えない。本研究の目的は，既存の圧電アクチュエータの限界を克服し， SEMの光学系におけるアパーチャープレートの駆 動要件や，その他の精密位置決め分野に対応できる新しい圧電リニアアクチュエータの開発である。まず、平行配列のデュアルステータを用いた両側駆動の歩行型圧電リニアアクチュエータを提案した。単一ステータの駆動脚の動作原理と楕円軌道を解析した。試作・実験の結果，アクチュエータが逆方向に動作する問題があることがわかった。次に、両側駆動の歩行型圧電リニアアクチュエータの逆方向への動作を解決するため，三角形のコンプライアンス機構を持つシンプルなステータ構造を開発した（片側駆動）。また、 x方向および y方向のダイナミックモ デルを構築し，片側駆動圧電アクチュエータの出力特性を評価した。最後に、片側駆動圧電アクチュエータを試作し，複数の実験からシミュレーションとの比較を行った。その結果、ダイナミックモデルの実現可能性が実証された。実験結果から，アクチュエータは広い速度範囲，逆方向に動作しないステッピング，高精度な位置決めの優れた複合性能を実現した。したがって，走査型電子顕微鏡の対物レンズのアパーチャープレートの駆動の可能性が示された。With the rapid development of the precision positioning field, the demand for piezoelectric actuators with high accuracy, quick response, and large stroke is increasing. Various non-resonant piezoelectric actuators have emerged in recent decades and have been applied successfully in many industrial fields, such as biological technology, optical instruments, micro/nano positioning platforms, and semiconductor technologies. However, existing non-resonant piezoelectric actuators still have limitations. They cannot be used in some specific precision positioning applications requiring (1) a low speed with a large stroke, (2) no backward motion, and (3) high positioning resolution, such as the driving of the aperture of a scanning electron microscope (SEM) used to monitor lithography process in semiconductor manufacturing. This research aims to develop a new type of piezoelectric linear actuator to overcome the limitations of the existing piezoelectric actuators and meet the driving requirements of the aperture plate in the optical system of SEM and other precision positioning fields.
First, a dual-side drive walking-type piezoelectric linear actuator with the parallel-arrangement dual stator was proposed. The operating principles and elliptical trajectory of the driving feet of a single-stator design were analyzed. A prototype was fabricated for the experimental evaluation; the results indicate that the actuator has a problem with backward motion.
Then, to solve the backward motion of the dual-side drive walking-type piezoelectric linear actuator, a simple stator structure with triangular-compliant mechanisms was further developed (single-side drive). Dynamic models in the x- and y-directions were established to evaluate the output characteristics of the single-side drive piezoelectric actuator.
Finally, a prototype of the single-side drive piezoelectric actuator was manufactured, and a series of experiments were carried out for comparison with simulation results. As a result, the feasibility of the dynamic models was verified. The experimental results indicate that the actuator realizes superior multiple performances of a wide range of velocity, stepping without backward motion, and high-precision positioning. Therefore, the possibility of driving the objective lens aperture plate in scanning electron microscopes was implied.doctoral thesi
締固め土の三軸液状化特性に及ぼす諸要因の影響とその評価に関する研究
Get PDF室蘭工業大学Muroran Institute of Technology博士（工学）我が国では，頻発する大規模な自然災害を受けて，それらの対策はもちろんのこと，土構造物に対する要求性能が高度化している．その中でも地盤の液状化に関する研究は，地震災害の歴史と共に発展をみせてきた．
液状化試験の基礎的研究では，新潟地震が発生した1964年から試験基準が制定された1990年頃にかけて多くの成果が残されており，1984年にとりまとめが行われた「砂地盤の工学的性質の評価法に関する研究委員会」による報告では，測定器具の仕様や設置方法，供試体条件による結果の違いが示され，それらを統一する必要性が示されている．このような基礎的研究は，当該試験の基準化に当たって十分な検討が行われ，その成果を基に議論が進められることが多いが，地盤材料試験に対する需要の変化によって，力学特性の基礎となる供試体条件についても，更に詳細な知見が必要なケースが出ている．特に，同じ作製方法による設定条件の違いについては，静的載荷による力学試験結果と比較すると，繰返し載荷試験による試験結果は大幅に少ないのが現状である．現在，供試体の準備方法として，空中落下法や各種締固め法など多くの供試体作製方法が提案されているが，実務での適用が多いのは主に湿潤締固めによる作製方法である．実務において，湿潤締固め法の需要が高い理由は，試料の粒度組成や含水状態など物理的条件に対する選択の幅が広いこと，使用する器具が簡易であることである．
本研究では，この湿潤締固め法に着目し，粒度組成の異なる2種類の砂質土を用いて，異なる作製条件下の供試体を作製し，繰返し非排水三軸試験と2種類の画像解析を実施している．画像解析では，はじめにX線CT画像によって供試体作製時の供試体内部構造を把握し，その後，PIV（Particle Image Velocimetry）解析結果によって繰返し載荷中の供試体表面における軸方向ひずみを計測し，締固め層厚が三軸液状化特性に及ぼす諸要因の影響について明らかにしている．また，2種類の砂質土による結果の比較を行うことで，粒度組成による液状化特性の相違についての考察を行っている．
得られた結果では，現行基準の供試体作製方法における問題点・留意点が述べられ，また湿潤締固め法による供試体作製時の適切な締固め層厚（層数）を提案し，本研究を総括している．Due to a lot of natural disasters in Japan, not only countermeasures against such disasters, but also the required performance of soil structures is becoming more sophisticated. Countermeasures against liquefaction have been also promoted, and along with that, the design have been developed. From 1964, when the Niigata Earthquake occurred, to around 1990, when test standards were enacted, many results were obtained in fundamental research on liquefaction testing reported by the "Research Committee on Evaluation Methods for Measurements". There are also cases where more detailed knowledge is required for test specimen conditions. In particular, regarding the difference in setting conditions for the same preparation method, the investigation cases of cyclic loading tests are significantly smaller than those of monotonic loading tests. It has been well known in laboratory element tests that liquefaction properties are affected by the difference in specimen preparation methods. Among various specimen preparation methods, the moist-tamping method has been often used in laboratory-element tests, which has a high reproducibility because grain size distribution and water content can be widely selected. In specimen preparation by the moist-tamping method, test specimens are generally prepared by compacting soil samples layer by layer. As a result, it has been reported that the non-uniformity in the specimen is induced during the compaction process. In this study, a series of cyclic undrained triaxial tests was performed on two kinds of sandy soils which are fine sand and well-graded sand to investigate the effects of the specimen-preparation methods on liquefaction resistance. In particular, the effects of the differences in grain size distribution and compaction thickness of the compacted specimens on liquefaction properties are discussed.
A series of cyclic undrained triaxial tests was conducted under the different conditions of grain size distribution and compaction thickness to reveal the effects of specimen preparation methods on liquefaction properties of two types of sandy soils. The specimens were prepared using the moist-tamping method. The number of compaction layers was either 1, 4, or 10. The results showed that the liquefaction resistance was influenced by the thickness of the compaction layer, and its tendency changed depending on the grain size distribution and the compaction degree, Dc. In addition, it was found that a difference in the initial moisture content had an influence on deformation properties during cyclic loadings. In particular, the deformation behavior of the specimens compacted under lower moisture content was similar to that of loose specimens. Furthermore, in the case of well-graded sand, there was no significant difference in liquefaction resistance between specimens of 10 and 4 layers; however, the liquefaction properties of a 1 layer specimen were significantly different from that of other compaction layers. Based on the results, the points to note in the current standard preparation method are described, and the thickness of compaction layer by moist-tamping method is proposed, summarizing this study.doctoral thesi
高クロム系多合金白鋳鉄のアブレシブ摩耗及びエロージョン摩耗特性
Get PDF室蘭工業大学Muroran Institute of Technology博士（工学）application/pdf本論文では、Cr、V、W、Mo、Coなどの遷移金属を含む多合金白鋳鉄（MWCI）の耐摩耗性に関する研究を行った。Cr量の増加により、MWCIの組織中に炭化物がより多く形成される可能性があるため，耐摩耗性の向上が期待できる。また、二次炭化物の析出や熱処理の組織改質が供試材の耐摩耗性に与える影響も関与している。そこで、各供試材の摩耗特性を明らかにするため、組織、硬度、炭化物破壊靭性などを系統的に調査した。さらに、実際の工学分野での材料選定に重要な、より包括的な改善情報を提供するため、いくつかの先行研究で使用した供試材との比較を行った。その結果，大荷重アブレシブ摩耗には，C量の多い28Cr-3Ni供試材は高い炭化物面積率及び硬度を有するため，珪砂のサイズにかかわらず、優れた耐アブレシブ摩耗性を示したが，低荷重でサイズの小さい珪砂にてアブレシブ摩耗を行った場合には、C量の少ない28Cr-3Ni供試材が優れた耐アブレシブ摩耗性を示した。このことより、アブレシブ摩耗には珪砂のサイズ及び荷重が支配的であることが明らかになった。また、28Cr-3Ni-2.8C供試材は高クロム系多合金白鋳鉄（Hi-Cr MWCI）に比べ，炭化物面積率及び硬度が低いため耐摩耗性に劣る。Moを0-3wt.%範囲内に添加した高クロム白鋳鉄（HCCI）の場合、Mo量の増加により16Cr白鋳鉄の硬度が上昇し、耐アブレシブ摩耗性が著しく向上した。一方、26Cr白鋳鉄に1wt.%Mo添加すると硬度が上昇し、耐アブレシブ摩耗性が向上したが、3wt.%Mo添加すると、炭化物面積率が減少し、耐摩耗性が低下した。Hi-Cr MWCIはMo添加HCCIに比べ、耐アブレシブ摩耗性が高く、特に18Cr MWCIが著しく高い。これはHi-Cr MWCIの析出した炭化物の種類（M7C3、M2C及びM23C6）がMo添加HCCIの炭化物の種類（M7C3及びM23C6）より多いためである。しかしながら、Hi-Cr MWCIはMWCIに比べ、炭化物の種類が少ないが、高い炭化物面積率及び硬度を有するため、優れた耐アブレシブ摩耗特性を示した。また、18Cr-MWCI及び27Cr-MWCIにおいて、焼入れ材と焼き戻し材を比較した場合、炭化物面積率が高いほど耐アブレシブ摩耗性が低下することが確認された。そして、エロージョン摩耗特性にも同じ結果を示した。Crを大量に添加すると、凝固時のミクロ偏析現象により、Cがより多く消費され、組織中に炭化物が多く形成されることで、基地中のCが少なくなり、硬度が低下したため耐摩耗性が低下したと考えられる。また、Crの増加に伴い二次炭化物が粗大化することも耐摩耗性低下の一因と考えられる。結言として、全供試材の耐摩耗性は、組織構成や硬度に強く依存するものであるResearch about wear resistance development of multi component white cast iron (MWCI) which contains several transition metals such as Cr, V, W, Mo, and Co has been conducted in this thesis. Due to the possibility in forming more carbide volume fraction in the microstructure of MWCI by increasing the amount of Cr addition, it is expected in better abrasive and erosive wear resistance. The effect of matrix modification and precipitation of secondary carbide during destabilization heat treatment process on the wear behavior of targeted materials also have been involved. The systematic investigation that involved microstructure characterization, hardness, and fracture toughness of carbide gives more meaningful elucidation to the wear behavior of each targeted materials. Besides that, the comparison to several previous materials provides the more comprehensive information about the improvement which is very important for materials selection in real engineering fields. The results show that by comparing 28Cr-3Ni-1.4C and 28Cr-3Ni-2.8C cast alloy to high Cr MWCIs, they have lower wear resistance owing to lower carbide volume fraction and hardness value. The similar condition also occurs when comparing HCCI with Mo addition (0-3 wt.%) and the high Cr MWCIs, which the wear resistance of HCCIs with Mo addition is much lower. The better wear resistance of these two new materials (18Cr and 27Cr MWCIs) is associated to the more types of precipitated carbides in the microstructure such as M7C3, M2C, and M23C6 as expected. Meanwhile, the opposite result happens when both high Cr MWCIs are compared to MWCI. Even though the types carbide of MWCI is more than high Cr MWCIs, but it has lower abrasive wear resistance. It can be understood that the better wear resistance of high Cr MWCIs is owing to the higher hardness. In addition, it is shown that the 18Cr MWCI after quenching has better abrasive wear resistance compared to quenching tempering specimens or 27Cr MWCI either after quenching or tempering. The same condition also occurs in the case erosive wear test when comparing as cast, quenched and quenched-tempered although in the case of as cast the 27Cr MWCI is better than 18Cr MWCI. It is known that 27Cr MWCI consumed more C content to form the eutectic carbide during solidification process and exacerbated in coarsening secondary carbide during heat treatment process leaving less available C in the matrix. Eventually, the hardness is lower resulting lower three-body abrasive or erosive wear resistance compared to 18Cr MWCI.doctoral thesi
A Text in the Northern Dialect of Uilta: Mother
Get PDF本稿では、2010 年にエレーナ A. ビビコワ（Elena Alekseevna BIBIKOVA：1940 年生まれのウイルタ女性）から筆者が採録したウイルタ語北方言による語りをテキスト化し、訳注を付けて紹介する。語りは、語り手自身の母アンナ B. ボリソワ（Anna Borisovna BORISOVA：1917-1961）のウイルタ名や人柄を主題とする、1950 年前後の思い出話とみられる。母は「フムラーンジ」および「コルゴルジ」というウイルタ名を持ち、活発でよく働く、強い女性だったという。ビビコワは、その母の手仕事を手伝いながら、切り紙文様や刺繍などの伝統的な技術を身につけた。journal articl
Classification of Depression and Its Severity Based on Multiple Audio Features Using a Graphical Convolutional Neural Network
Get PDFAudio features are physical features that reflect single or complex coordinated movements in the vocal organs. Hence, in speech-based automatic depression classification, it is critical to consider the relationship among audio features. Here, we propose a deep learning-based classification model for discriminating depression and its severity using correlation among audio features. This model represents the correlation between audio features as graph structures and learns speech characteristics using a graph convolutional neural network. We conducted classification experiments in which the same subjects were allowed to be included in both the training and test data (Setting 1) and the subjects in the training and test data were completely separated (Setting 2). The results showed that the classification accuracy in Setting 1 significantly outperformed existing state-of-the-art methods, whereas that in Setting 2, which has not been presented in existing studies, was much lower than in Setting 1. We conclude that the proposed model is an effective tool for discriminating recurring patients and their severities, but it is difficult to detect new depressed patients. For practical application of the model, depression-specific speech regions appearing locally rather than the entire speech of depressed patients should be detected and assigned the appropriate class labels.journal articl
Electroabsorption and Stark Fluorescence Spectroscopies of Thioflavin T
Get PDFThioflavin T (ThT) is a typical fluorescent marker for detecting the formation of amyloid fibrils, because its fluorescence intensity increases by more than two orders of magnitude upon complexation with the fibrils. Strong electrostatic fields on protein surfaces are known to be a significant factor in chemical reactions and biological functions. Therefore, ThT bound to amyloid fibrils must experience strong electric fields. This study employed electroabsorption and Stark fluorescence spectroscopies to clarify the effects of external electric fields on the photophysics of ThT. The absorption spectrum shows two bands ascribed to locally excited (LE) and charge transfer (CT) states. Coupling between the LE and CT states is enhanced in the presence of an external electric field, resulting in fluorescence quenching. The electric field strength of the amyloid fibril surface was inferred from the fluorescence quenching efficiency of ThT.journal articl
Photoexcited Carrier Transfer in CuInS2 Nanocrystal Assembly by Suppressing Resonant‐Energy Transfer
Get PDFHigh-density assemblies or superlattice structures
composed of colloidal semiconductor nanocrystals have attracted
attention as key materials for next-generation photoelectric
conversion devices such as quantum-dot solar cells. In these
nanocrystal solids, unique transport and optical phenomena occur
due to quantum coupling of localized energy states, charge-carrier
hopping, and electromagnetic interactions among closely arranged
nanocrystals. In particular, the photoexcited carrier dynamics in
nanocrystal solids is important because it significantly affects various
device parameters. In this study, we report the photoexcited carrier
dynamics in a solid film of CuInS2 nanocrystals, which is one of the
potential nontoxic substitutes with Cd- and Pb-free compositions.
Meanwhile, these subjects have been extensively studied in
nanocrystal solids formed by CdSe and PbS systems. A carrierhopping
mechanism was confirmed using temperature-dependent
photoluminescence spectroscopy, which yielded a typical value of the
photoexcited carrier-transfer rate of (2.2 ± 0.6) × 107 s−1 by
suppressing the influence of the excitation-energy transfer.journal articl