スポーツ史における社会学，経済学そして「文化経済学」のアプローチ : 新しい方向のための提言

departmental bulletin pape

Parallel Finite Element Subdivision Method for Electromagnetic Analysis of a Large Interior Space

In high-frequency electromagnetic field analysis, it is necessary to divide the waveform into elements whose maximum side length is 1/10 to 1/20 of the wavelength so that the waveform can be expressed with low error when a space is divided. Therefore, in many cases, it becomes a largescale problem. In this study, due to the need for electromagnetic compatibility (EMC) evaluation of the surrounding electromagnetic field generated when a microwave scalpel is used in surgery, a large-scale electromagnetic analysis method for the microwave region inside the operating room has been developed. In this paper, the introduced parallel mesh subdivision function enables highspeed mesh generation with hundreds of millions of elements. In addition, this method provided a successful analysis

Observation of the Color-Suppressed Decay B̅ 0→D0π0

journal articl

Effects of negative ions on discharge characteristics of water plasma source for a miniature microwave discharge ion thruster

This work analyzes the discharge characteristics of water plasma for a miniature microwave discharge ion thruster via three-dimensional particle-in-cell simulations with Monte Carlo collisions. It incorporates the negative ions (H−, O−, and OH−) into the simulation code, aside from the three major positive ion species (H2O+, OH+, and H+), and investigates their effects on the discharge characteristics. On the one hand, the simulation results indicate that H2O+ is the dominant species and the negative ions have little effect on the positive ion density and transport. On the other hand, this study confirms the axial oscillation of the OH− negative ion density, in addition to azimuthal rotation, causing plasma instability with a periodic low-frequency anomalous diffusion. The azimuthal rotation is similar to the phenomena observed in other E × B devices, where the difference in spatial distributions of magnetized electrons and unmagnetized ions causes the local potential hump and the resultant instability. Moreover, the axial oscillation, not observed in the previous study considering only positive ions, is due to the generation of OH− by the charge transfer collision reaction between H2O and H−, and this oscillation frequency is double that of the azimuthal rotation. Both the azimuthal rotation and the axial oscillation result in the periodic double peaks of the potential time evolution. These fluctuations have an influence on electron transport across the magnetic field.journal articl

特集1 : 研究解説 : バックステップ流れのLES計算

ステップ拡大率1.5のバックステップ流れについてLESによる数値計算を実行した。ステップ高さおよび主流速度によるレイノルズ数は4.6×104である。格子の細かい計算例では、従来の乱流モデルで再現が困難であった再付着距離についても、実験結果をほぼ再現する結果を得た。平均速度場、乱流量等について計算結果と実験結果との比較を行い、はく離を含む流れ場においてもLESの有効性が確認された特集 乱流の数値シミュレーション（NST） その7departmental bulletin pape

Full Determination of Zero Field Splitting Tensor of the Excited Triplet State of C₆₀ Derivatives of Arbitrary Symmetry from High Field TREPR in Liquid Crystals

The low-lying photoexcited triplet state of a series of fullerene C60 adducts has been studied by high-field TREPR (time-resolved EPR) spectroscopy in a partially oriented phase. The fullerenes adopt a biaxial alignment, driven by the substituents, that has allowed to fully determine the ZFS and g tensors, i.e., their principal values and the orientation of the principal axes in the molecular skeleton. This has been accomplished by combining line shape analysis and theoretical prediction of molecular order. A strong dependence of the magnetic tensors on the substitution pattern has been found

Sequence, Structure, and Dynamic Determinants of Hsp27 (HspB1) Equilibrium Dissociation Are Encoded by the N-Terminal Domain

Human small heat shock protein 27 (Hsp27) undergoes concentration-dependent equilibrium dissociation from an ensemble of large oligomers to a dimer. This phenomenon plays a critical role in Hsp27 chaperone activity in vitro enabling high affinity binding to destabilized proteins. In vivo dissociation, which is regulated by phosphorylation, controls Hsp27 role in signaling pathways. In this study, we explore the sequence determinants of Hsp27 dissociation and define the structural basis underlying the increased affinity of Hsp27 dimers to client proteins. A systematic cysteine mutagenesis is carried out to identify residues in the N-terminal domain important for the equilibrium between Hsp27 oligomers and dimers. In addition, spin-labels were attached to the cysteine mutants to enable electron paramagnetic resonance (EPR) analysis of residue environment and solvent accessibility in the context of the large oligomers, upon dissociation to the dimer, and following complex formation with the model substrate T4 Lysozyme (T4L). The mutagenic analysis identifies residues that modulate the equilibrium dissociation in favor of the dimer. EPR analysis reveals that oligomer dissociation disrupts subunit contacts leading to the exposure of Hsp27 N-terminal domain to the aqueous solvent. Moreover, regions of this domain are highly dynamic with no evidence of a packed core. Interaction between T4L and sequences in this domain is inferred from transition of spin-labels to a buried environment in the substrate/Hsp27 complex. Together, the data provide the first structural analysis of sHSP dissociation and support a model of chaperone activity wherein unstructured and highly flexible regions in the N-terminal domain are critical for substrate binding

Dynamics of Alkoxy−Oligothiophene Ground and Excited States in Nanochannels

Two oligothiophenes, 4,4‘-dipentoxy-2,2‘-dithiophene and 4,4‘ ‘-dipentoxy-2,2‘:5‘,2‘ ‘:5‘ ‘,2‘ ‘‘-tetrathiophene, have been included in the nanochannels of the autoassembling host TPP (tris-o-phenylenedioxycyclotriphosphazene). The effect of the confinement on the structure and properties of the two dyes, as conformational arrangements, dynamics, and photophysical behavior, was addressed by the combination of high spinning speed solid-state NMR and time-resolved EPR spectroscopy. We compared the conformations of the dyes in their ground and photoexcited triplet states and described in detail the dynamics of the supramolecular adducts from 4 K to room temperature. Above 200 K surprisingly fast spinning rates of the dithiophene core were discovered, while the side chains show far slower reorientation motion, being in bulky gauche-rich conformations. These lateral plugs keep the planar core as appended in the space like a nanoscale gyroscope, allowing a reorientation in the motion regime of liquids and a long triplet lifetime at unusually high temperature. The nuclear magnetic properties of the guest dyes are also largely affected by the aromatic rings of the neighboring host, imparting an impressive magnetic susceptibility effect (2 ppm proton shift). The high mobility is due to the formation of a nanocage in a channel where aliphatic and aromatic functions isolate the thiophene moieties. Instead, two conformers of the tetrathiophene twisted on the central bond are stabilized by interaction with the host. They interconvert fast enough to be averaged in the NMR time scale

Structural Characterization of a High Affinity Mononuclear Site in the Copper(II)-α-Synuclein Complex

Human α-Synuclein (aS), a 140 amino acid protein, is the main constituent of Lewy bodies, the cytoplasmatic deposits found in the brains of Parkinson’s disease patients, where it is present in an aggregated, fibrillar form. Recent studies have shown that aS is a metal binding protein. Moreover, heavy metal ions, in particular divalent copper, accelerate the aggregation process of the protein. In this work, we investigated the high affinity binding mode of truncated aS (1−99) (aS99) with Cu(II), in a stoichiometric ratio, to elucidate the residues involved in the binding site and the role of copper ions in the protein oligomerization. We used Electron Paramagnetic Resonance spectroscopy on the Cu(II)-aS99 complex at pH 6.5, performing both multifrequency continuous wave experiments and pulsed experiments at X-band. The comparison of 9.5 and 95 GHz data showed that at this pH only one binding mode is present. To identify the nature of the ligands, we performed Electron Spin Echo Envelope Modulation, Hyperfine Sublevel Correlation Spectroscopy, and pulsed Davies Electron−Nuclear Double Resonance (Davies-ENDOR) experiments. We determined that the EPR parameters are typical of a type-II copper complex, in a slightly distorted square planar geometry. Combining the results from the different pulsed techniques, we obtained that the equatorial coordination is {NIm, N−, H2O, O}, where Nim is the imino nitrogen of His50, N− a deprotonated amido backbone nitrogen that we attribute to His50, H2O an exchangeable water molecule, and O an unidentified oxygen ligand. Moreover, we propose that the free amino terminus (Met1) participates in the complex as an axial ligand. The MXAN analysis of the XAS k-edge absorption data allowed us to independently validate the structural features proposed on the basis of the magnetic parameters of the Cu(II)-aS99 complex and then to further refine the quality of the proposed structural model

Broken Helix in Vesicle and Micelle-Bound α-Synuclein: Insights from Site-Directed Spin Labeling-EPR Experiments and MD Simulations

Broken Helix in Vesicle and Micelle-Bound α-Synuclein: Insights from Site-Directed Spin Labeling-EPR Experiments and MD Simulation