Topological enhancement of non-normality in non-Hermitian skin effects

The non-Hermitian skin effects are representative phenomena intrinsic to non-Hermitian systems: the energy spectra and eigenstates under the open boundary condition (OBC) drastically differ from those under the periodic boundary condition (PBC). Whereas a non-trivial topology under the PBC characterizes the non-Hermitian skin effects, their proper measure under the OBC has not been clarified yet. This paper reveals that topological enhancement of non-normality under the OBC accurately quantifies the non-Hermitian skin effects. Correspondingly to spectrum and state changes of the skin effects, we introduce two scalar measures of non-normality and argue that the non-Hermitian skin effects enhance both macroscopically under the OBC. We also show that the enhanced non-normality correctly describes phase transitions causing the non-Hermitian skin effects and reveals the absence of non-Hermitian skin effects protected by average symmetry. The topological enhancement of non-normality governs the perturbation sensitivity of the OBC spectra and the anomalous time-evolution dynamics through the Bauer-Fike theorem.Comment: 33 pages, 14 figure

Novel 3D-CT evaluation of carotid stent volume: greater chronological expansion of stents in patients with vulnerable plaques

Although self-expanding carotid stents may dilate gradually, the degrees of residual stenosis have been quantified by the NASCET criteria, which is too simple to reflect the configuration of the stented artery. We measured the volumes of the stent lumens chronologically by 3D-CT in patients after carotid artery stenting (CAS), and analyzed the correlations between the volume change and medical factors. Fourteen patients with carotid artery stenosis were treated using self-expanding, open-cell stents. All patients underwent preoperative plaque MRI (magnetization-prepared rapid acquisition gradient-echo, MPRAGE) and chronological 3D-CT examinations of their stents immediately after their placement and 1 day, 1 week, and 1 month after the procedure. The volume of the stent lumen was measured using a 3D workstation. The correlations between stent volume and various factors including the presence of underlying diseases, plaque characteristics, and the results of the CAS procedure were analyzed. Stent volume gradually increased in each case and had increased by 1.04-1.55 (mean, 1.25)-fold at 1 postoperative month. The presence of underlying medical diseases, plaque length, the degree of residual stenosis immediately after CAS, and plaque calcification did not have an impact on the change in stent volume. On the other hand, the stent volume increase was significantly larger in the patients with vulnerable plaques that demonstrated high MPRAGE signal intensity (P < 0.05). A 3D-CT examination is useful for precisely measuring stent volume. Self-expanding stents in carotid arteries containing vulnerable plaques expand significantly more than those without such plaques in a follow-up period

Optogenetic Stimulation of 5-HT Neurons in the Median Raphe Nucleus Affects Anxiety and Respiration

Anxiety affects respiration, and in turn perturbs the internal environment, although the neuronal systems controlling anxiety-related respiration remain unclear. Recent reports indicate that serotonin（5-HT）neurons in the median raphe nucleus（MRN）enhance anxiety. In the present study, we aimed to clarify the contribution of 5-HT neurons in the MRN to anxiety and respiratory control using mice expressing a channelrhodopsin-2 variant-enhanced yellow fluorescent protein（ChR2 ［C128S］-EYFP; a step-function opsin）in the central 5-HT neurons. We applied an optogenetic method to bigenic mice expressing ChR2［C128S］-EYFP in 5-HT neurons and to monogenic mice without such expression. Photostimulation of free-moving mice was performed using a wireless system through an optical fiber pre-inserted above the MRN, and respiratory variables were measured using whole-body plethysmography. Anxiety was evaluated using an elevated-plus maze test. In the bigenic mice, we confirmed ChR2［C128S］-EYFP expression in tryptophan hydroxylase 2（a brain 5-HT synthase）-positive neurons in the raphe nuclei of the mesopontine, such as the MRN and the dorsal raphe nucleus. Blue light illumination to the MRN of the bigenic mice significantly increased respiratory rate and minute ventilation without affecting tidal volume, and significantly decreased the time spent in the open arms of the elevated plus maze without changing distance traveled, compared with monogenic mice. These results suggest that 5-HT neuron activity in the MRN increases anxiety-like behavior without affecting locomotor activity, enhances respiratory rhythm and minute ventilation without changing tidal volume, and can mimic anxiety-related respiratory responses in humans

Dimensional reduction by geometrical frustration in a cubic antiferromagnet composed of tetrahedral clusters

Dimensionality is a critical factor in determining the properties of solids and is an apparent built-in character of the crystal structure. However, it can be an emergent and tunable property in geometrically frustrated spin systems. Here, we study the spin dynamics of the tetrahedral cluster antiferromagnet, pharmacosiderite, via muon spin resonance and neutron scattering. We find that the spin correlation exhibits a two-dimensional characteristic despite the isotropic connectivity of tetrahedral clusters made of spin 5/2 Fe3+ ions in the three-dimensional cubic crystal, which we ascribe to two-dimensionalisation by geometrical frustration based on spin wave calculations. Moreover, we suggest that even one-dimensionalisation occurs in the decoupled layers, generating low-energy and one-dimensional excitation modes, causing large spin fluctuation in the classical spin system. Pharmacosiderite facilitates studying the emergence of low-dimensionality and manipulating anisotropic responses arising from the dimensionality using an external magnetic field

2017～2019年度 関西大学研究拠点形成支援経費研究成果報告書

目次・研究成果の概要・2-1　工藤 宏人・宮前 翼・上田 正人・村山 憲弘・林 順一 "ノーリア骨格をテンプレートとした空孔内に水酸基を有する架橋化合物の合成とそれらの金属イオン包接性能" ネットワークポリマー論文集 vol.41, No.2, 65 - 71 (2020).・2-2　Mitsuaki Matsuoka, Kaho Yokoyama, Kohei Okura, Norihiro Murayama, Masato Ueda, Makio Naito " Synthesis of Geopolymers from Mechanically Activated Coal Fly Ash and Improvement of Their Mechanical Properties" Minerals 9, 791- 801 (2019).・2-3　Daisuke Shimoyama, Ryo Sekiya, Hiroto Kudo, Takeharu Haino, "Feet-to-Feet Connected Trisresorcinarenes" Organic Letters 22, 352 - 356 (2019).・2-4　Masato Ueda, Masahiko Ikeda, Shigeo Mori, Kenji Doi, Hisashi Kitagaki, Shuntaro Terauchi "Mechanical Properties of Additively Manufactured Porous Titanium with Sub-Millimetre Structural Units" Materials Transactions Vol.60, No.9, 1792 - 1798 (2019).・2-5　五十井 浩平・白杉 文香・松岡 光昭・林 順一・村山 憲弘 "種々のMg-Fe系複合酸化物を用いた希薄水溶液中のホウ素およびヒ素の除去" 環境資源工学 66, 29 - 35 (2019).・2-6　Toru Maruyama, Mitsuyoshi Tamaki, Keisuke Nakamura, Gou Nakamura "EFFECT OF MOLTEN METAL TEMPERATURE ON MOLD FILLING IN EVAPORATIVE PATTERN CASTING" International Journal of Metalcasting 13, 611–617 (2019).・2-7　Ryuta Saito, Toru Maruyama, Toshiki Nakamura, Hitoshi Yanagitani, Takahiro Sakai, Kouji Nakamoto "Influence of Tellurium Addition to Spheroidal Graphite Cast Iron on the Number of Graphite Particles" International Journal of Metalcasting Vol.13, 3, 571-577 (2018).・2-8　Masato Ueda, Rika Yamaguchi, Chika Fujita, Masahiko Ikeda "Control of Cell Adhesion on Titanium Dioxide by Light Irradiation" Materials Science Forum Vol.941, 2507 - 2512 (2018).・2-9　Hiroto Kudo, Mari Fukunaga, Kohei Shiotsuki, Hiroya Takeda, Hiroki Yamamoto, Takahiro Kozawa, Takeo Watanabe "Synthesis of hyperbranched polyacetals containing C-(4-t-butylbenz)calix[4]resorcinarene: Resist properties for extreme ultraviolet (EUV) lithography" Reactive and Functional Polymers 131, 361 - 367 (2018).・2-10　大隈 修・前 一廣・林 順一 "直接液化による豪州ビクトリア褐炭の高度利用 : 改新BCLプロセスによる化学原料の生産" Journal of the Japan Institute of Energy 98, 17 - 26 (2019).・2-11　Issei Suzuki, Ayako Kakinuma, Masato Ueda, Takahisa Omata "Flux growth of β-NaGaO₂ single crystals" Journal of Crystal Growth 504, 26 -30 (2018).・2-12　上田 正人、坂本 貴則、池田 勝彦 "電気抵抗率の精密測定による純チタンの組織評価" 環境資源工学 65, 74 -76 (2018).・2-13　Satoshi Imasaka, Hiroyasu Ishii, Jun\u27ichi Hayashi, Sadao Araki, Hideki Yamamoto "Synthesis of CHA-type titanosilicate zeolites using titanium oxide as Ti source and evaluation of their physicochemical properties" Microporous and Mesoporous Materials 273, 243-248 (2019).・2-14　Hiroto Kudo, Shizuya Ohori, Hiroya Takeda, Hiroki Ogawa, Takeo Watanbe, Hiroki Yamamoto, Takahiro Kozawa "Synthesis and Property of Tannic Acid Derivatives and Their Application for Extreme Ultraviolet Laser Lithography System" Journal of Photopolymer Science and Technology Vol.31, 221 - 225 (2018).・2-15　Hiroto Kudo, Tsubasa Miyamae, Kouta Kitagawa, Kohei Isoi, Norihiro Murayama, Jun\u27ichi Hayashi " Synthesis and Metal-Complexation Ability of Cross-Linking Materials Containing Noria-Templated Cavities with Pendant Carboxylic Acid Groups" Chemistry Select 3, 2223 - 2228 (2018).・2-16　上田 正人、池田 勝彦、土井 研児、 森 重雄、北垣 壽、寺内 俊太郎、関 あずさ "骨部分置換用ポーラスチタン : ポリグリコール酸 : 炭酸カルシウム複合体の開発" 高分子論文集 Vol.75, No.1, 69 - 74 (2018).・2-17　Alexandru C Sonoc, Jacob Jeswiet, Norihiro Murayama, Junji Shibata "A study of the application of Donnan dialysis to the recycling of lithium ion batteries" Hydrometallurgy 175, 133 - 143 (2018).2-3は、著作権の関係により非公開としております。2-8は、著作権の関係により非公開としております。2-9は、著作権の関係により非公開としております。2-10は、著作権の関係により非公開としております。2-11は、著作権の関係により非公開としております。2-16は、著作権の関係により非公開としております

Automatic acquisition of motion trajectories: Tracking hockey players

We accept this thesis as conformin

Active exploration of training data for improved object detection

This thesis concerns the problem of object detection, which is defined as finding all instances of an object class of interest and fitting each of them with a tight bounding window. This seemingly easy task for humans is still extremely difficult for machines. However, recent advances in object detection have enabled machines to categorize many classes of objects. Statistical models are often used for representing an object class of interest. These models learn from extensive training sets and generalize with low error rates to unseen data in a highly generic manner. But, these statistical methods have a major drawback in that they require a large amount of training data. We approach this problem by making the process of acquiring labels less tedious and less costly by reducing human labelling effort. Throughout this thesis, we explore means of efficient label acquisition for realizing cheaper training, faster development time, and higher-performance of object detectors. We use active learning with our novel interface to combine machine intelligence with human interventions, and effectively improve a state-of-the-art classifier by using additional unlabelled images from the Web. As the approach relies on a small amount of label input from a human oracle, there is still room to further reduce the amount of human effort. An ideal solution is, if possible, to have no humans involved in labelling novel data. Given a sparsely labelled video that contains very few labels, our novel self-learning approach achieves automatic acquisition of additional labels from the unlabelled portion of the video. Our approach combines colour segmentation, object detection and tracking in order to discover potential labels from novel data. We empirically show that our self-learning approach improves the performance of models that detect players in broadcast footage of sports games.Science, Faculty ofComputer Science, Department ofGraduat

Automatic acquisition of motion trajectories : tracking hockey players

We address the problem of automatically analyzing hockey scenes by estimating the panning, tilting and zooming parameters of the broadcasting cameras, tracking hockey players in these scenes, and constructing a visual description of the scenes as trajectories of those players. Given quite fast and non-smooth camera motions to capture highly complex and dynamic scenes of hockey, tracking hockey players that are small blob-like, non-rigid and amorphous becomes an extremely difficult task. We suggest a new method of automatically computing the mappings to represent the globally consistent map of the hockey scenes by removing camera motions, and implement a color-based sequential Monte Carlo tracker to track hockey players to estimate their real world position on the rink. The result demonstrates a quite successful performance on both objectives. We make two new contributions in this research. First, we introduce a new model fitting algorithm to reduce projection errors. Second, we use an adaptive model to improve the current state-of-art color-based probablistic tracker. Our approach is also applicable for video annotation in other sports, surveillance, or many other situations that require obect tracking on a planar surface. Since there have not been any hockey annotation systems developed in the past, we hope that our system would become a stepping stone for automatic video annotation in hockey.Science, Faculty ofComputer Science, Department ofGraduat