ニュース
217件のニュース / 2022年
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2022-02-02
セミナーレポート
DMWG Seminar by Dr. Kenji Kadota on January 31, 2022
Weakly Interacting Massive Particles (WIMPs) have long been a leading candidate of dark matter(DM). However, no signatures are found in any kinds of experiments. Investigation of the alternatives is now rapidly growing. Primordial black holes (PBHs), which are formed in the early Universe and source the gravitational potential for baryonic components to evolve, are being widely discussed and searched now. Recent progress of the gravitational, as well as electromagnetic, observations of the Universe already excludes a large portion of the parameter space of PBH as DM. So if it contributes to DM, it is natural to also consider contributions from other components such as WIMPs. In such a situation, PBHs are dressed with WIMP halos. Then WIMP annihilation proceeds in the vicinity of the central PBH and a cored structure is expected depending on the annihilation rate. This dependence of the core structure on the annihilation rate leads to a tricky behavior in the constraints for PBH-WIMP mixed scenarios. Also, when PBHs are abundantly formed, we cannot neglect their clustering effects on the constraints obtained in the observable Universe because the dressed PBH with WIMP indicates the clustering of WIMP halos in host galaxies. In this case, the boost factor, which appears naturally in the scenario of pure WIMP DM models, needs to be evaluated in such a way that regarding the clustering of PBHs. Those interesting phenomena are only a part of examples that we can expect in the PBH-WIMP mixed scenario for DM. Varieties of possibilities are waiting for our investigations. Discussions are blooming now! Reported by Nagisa Hiroshima
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2022-02-02
書籍
寄生虫進化生態学
Robert Poulin [著] 片平 浩孝／川西 亮太／入谷 亮介 [訳] Translated from "Evolutionary Ecology of Parasites: Second Edition" ( Princeton University Press, 2007) by Robert Poulinを翻訳
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2022-01-28
セミナーレポート
Quantum Matter SG seminar by Prof. Rafael I. Nepomechie on January 26, 2022
The Quantum Matter Study Group invited Prof. Rafael Nepomechie from the University of Miami to talk about the Bethe ansatz and realizing Bethe states in quantum computers. In the beginning, he used the Heisenberg chain to introduce the coordinate Bethe ansatz. In condensed matter physics, it is extremely difficult to solve many-body Hamiltonians. For this specific Heisenberg model, Bethe came up with a judicious method for finding the exact many-body wave function. The many-body problem is transformed to solving the Bethe equations. Unfortunately, it is also hard to solve these equations completely. Prof. Nepomechie presented an alternative approach to find the exact wave function and hence the solution to the Bethe equations through quantum computation. He found that, by using specific quantum operations, the exact wave function of the Heisenberg model can be presented in the quantum computer with a probability decaying as the factorial of the number magnons that make up the wave function. It is interesting to learn about this connection between the Bethe ansatz and quantum computing. Discussions were made how to increase the probability of the discussed scheme and how to extend it to find the complete set of Bethe roots for larger systems. Reported by Thore Posske (University of Hamburg, Germany) and Ching-Kai Chiu
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2022-01-28
セミナーレポート
iTHEMS Biology Seminar by Prof. Kenta Ishimoto on January 27, 2022
We successfully had a great time thanks to Dr. Kenta Ishimoto's fantastic talk, in which he talked about the basic background of fluid dynamics, followed by two topics of his own research. Thank you again for the fantastic talk! Reported by Ryosuke Iritani
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2022-01-27
今週の論文Week 5, January 2022
Title: Gopakumar-Vafa type invariants of holomorphic symplectic 4-folds Author: Yalong Cao, Georg Oberdieck, Yukinobu Toda arXiv: http://arxiv.org/abs/2201.10878v1 Title: Universal Properties of Weakly Bound Two-Neutron Halo Nuclei Author: Masaru Hongo, Dam Thanh Son arXiv: http://arxiv.org/abs/2201.09912v1 Title: On the evolution of the Hubble constant with the SNe Ia Pantheon Sample and Baryon Acoustic Oscillations: a feasibility study for GRB-cosmology in 2030 Author: Maria Giovanna Dainotti, Biagio De Simone, Tiziano Schiavone, Giovanni Montani, Enrico Rinaldi, Gaetano Lambiase, Malgorzata Bogdan, Sahil Ugale arXiv: http://arxiv.org/abs/2201.09848v2 Title: Foundations and Applications of Quantum Kinetic Theory Author: Yoshimasa Hidaka, Shi Pu, Qun Wang, Di-Lun Yang arXiv: http://arxiv.org/abs/2201.07644v1 Title: Global study of the scalar quasi-normal modes of Kerr-AdS${}_5$ black holes: Stability, thermality, and horizon area quantization Author: Issei Koga, Naritaka Oshita, Kazushige Ueda arXiv: http://arxiv.org/abs/2201.07267v1
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2022-01-25
セミナーレポート
NEW WG Seminar by Mr. Tomohiro Tanogami on January 20, 2022
Tomohiro Tanogami from Kyoto University gave a talk titled "A simple XY model for cascade transfer." Cascade transfer is a ubiquitous phenomenon that appears in various physical systems. During a cascade transfer an inviscid conserved quantity such as energy is transferred conservatively from large/small to small/large scales, which results in a universal scaling law in the spectrum (e.g., Kolmogorov energy spectrum). In the talk, Tomohiro proposed a simple XY model which shows inverse energy cascade with a non-Kolmogorov energy spectrum and pointed out that the model may characterize a novel "universality class" of cascade transfer. Tomohiro also explained possible relations between his model and, e.g., spin and atmospheric turbulences. About 20 physicists have joined the seminar and enjoyed discussions from various viewpoints. Reported by Hidetoshi Taya
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2022-01-24
プレスリリース
シグナル伝達による多様な細胞応答の起源 －実験と理論の融合による反応特性の決定
細胞が外界のシグナル分子を受け取る受容体の1つのグループに、ERBB1、ERBB2、ERBB3、ERBB4からなるERBBファミリーがあります。ERBB受容体は、シグナル分子を受け取ると、互いに結合やリン酸化などの反応を行い、これをきっかけに細胞の増殖や分化などの多様な応答が起こります。ところが、4種のERBBの結合反応やリン酸化反応の詳細は計測が難しく、シグナルに対する多様な応答がどのように作り出されるのかわかっていませんでした。 これに対し、京都大学ウイルス・再生医科学研究所の望月敦史教授、 理化学研究所の岡田崇上級研究員、宮城拓研究員（研究当時）、佐甲靖志主任研究員、廣島通夫研究員らの研究グループは、ERBBの組成を様々に変えた細胞と複数のシグナル分子を用いた計測実験を行い、ERBBの可能な反応を全て取り込んだ数理モデルを適用することで、4種のERBBの反応の性質やシグナルによる反応の変化を初めて特定しました。さらに、数理解析を進め、応答の多様性に本質的な役割をになう反応を明らかにしました。ERBBの反応の詳細が分かったことで、将来的には増殖や分化などのシグナル伝達が引き起こす応答を制御できる可能性があります。 詳細は関連リンクの京都大学のプレスリリース記事をご覧ください。
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2022-01-20
イベントスケジュール
Events for the 5th week of January 2022
Thursday, January 27, 10:00– 11:00 iTHEMS Biology Seminar Friday, January 28, 12:30- Coffee Meeting Saturday, January 29, 15:30- 16:40 RIKEN AIP-Suri-joshi Joint Seminar
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2022-01-20
セミナーレポート
iTHEMS Biology Seminar by Dr. Hiroyasu Miyazaki on January 20, 2022
In the iTHEMS Biology Seminar on 20th January, Dr. Hiroyasu Miyazaki (RIKEN iTHEMS) gave a talk on the topological aspect of chemical reaction network. His talk is composed of two parts: motivation and result part and method part. In the first part, he mentioned the reduction of the chemical reaction network in E. Coli and its result which shows the same steady state as that before the reduction. In the second part, he explained how the network should be reduced. The topological information of the network can be described by using the matrix and the vector. He explained that the quotient network is defined to have a sequence of linear maps called “exact sequence”, which describes the relation among the original network, the subnetwork and the quotient network. We enjoyed his beautiful talk. From the audiences, the lively discussion arose during and after the talk. Thank you very much, Hiroyasu! Reported by Hiroshi Yokota
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2022-01-20
今週の論文Week 4, January 2022
Title: Current-induced inverse symmetry breaking and asymmetric critical phenomena at current-driven tricritical point Author: Masataka Matsumoto, Shin Nakamura arXiv: http://arxiv.org/abs/2201.06894v1 Title: Global study of the scalar quasi-normal modes of Kerr-AdS${}_5$ black holes: Stability, thermality, and horizon area quantization Author: Issei Koga, Naritaka Oshita, Kazushige Ueda arXiv: http://arxiv.org/abs/2201.07267v1
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2022-01-18
セミナーレポート
DMWG Seminar by Dr. Kanji Mori on January 17, 2022
In this era of multi-messenger astronomy, axion-like particle (ALP) searches using astrophysical transients are now excitingly discussed. ALPs are an extended class of particles from QCD axion, which could solve the strong CP problem of the Standard Model, and dark matter (DM) candidates of various connections to the physics beyond the Standard Model. ALPs could interact with our sector through their coupling to the photon, electron, and/or nucleons. The coupling of ALP to the photon is previously investigated using observations of SN 1987A, the most famous supernova explosion. MeV gamma-ray signals are expected when considering the conversion of ALP outside the stellar envelope, hence no observations of the associated gamma-ray emission to the supernova lead to the constraint on the coupling strength, for example. Also, the existence of such coupling should modify the dynamics of supernovae. When a star explodes, the difference between the masses of the progenitor star and the resulting compact object sources the radiation, neutrino emission, and kinetic energy of the ejecta material. ALP could be an additional channel for the energy release while its absorption heats the supernova. The balance between heating and cooling controls the supernova dynamics and shock restoration, which directly relates to the electromagnetic observables. Dr. Mori has shown that the heating rate is very sensitive to the coupling strength and enhancement of the electromagnetic emission is expected in the pre-supernova stage. The signatures could also be visible in the neutrino sector after the explosion. The results are fantastic, and there are a lot of things to do. For example, the inclusion of the ALP-nucleon coupling effects is an interesting direction to pursue. Updates in the understanding of stellar models are important as well. We should see the signature of ALP in the near future in this field! Reported by Nagisa Hiroshima
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2022-01-17
セミナーレポート
iTHEMS Biology Seminar by Dr. Wataru Nishima on January 13, 2022
Dr. Wataru Nishima (New Mexico Consortium, USA) gave a very interesting presentation about his published paper on the spike protein of the SARS-CoV-2, the virus which causes COVID-19 [1]. He described the conformational change which the SARS-CoV-2 spike protein undergoes when it fuses with the host cell to initiate infection. His work offers and interesting alternative view of the process wherein parts of the spike protein ends up inside the host cell. This differs from the usual view where the spike protein would be left on the outside of the cell after virus fusion with the host. This alternative hypothesis could have important implication for better understanding disease severity, e.g. based on the possible toxic effect of spike protein components shed as part of the fusion process. Dr. Nishima's expertise is primarily in Molecular Dynamics and Bioinformatics and he is very interested to establish new collaborations with iTHEMS members. Reported by Catherine Beauchemin
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2022-01-17
ホットトピック
「数理の窓から世界を読みとく」若手研究者たちの感性に注目
「数理の窓から世界を読みとく」についてのコラム記事がイマジニア社のテンミニッツTVに掲載されました。 iTHEMSの若手研究者たちが執筆陣を担った共著「数理の窓から世界を読みとく: 素数・AI.生物・宇宙をつなぐ」 (初田哲男・柴藤亮介編著、岩波書店)をもとに数理の魅力が紹介されています。 詳細は関連リンクをご覧下さい。
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2022-01-14
リサーチニュース
RIKEN NEWS: ゲノム情報に隠された進化の法則を探る
ジェフリ・フォーセット上級研究員のインタビュー記事が、理研の研究紹介ページ「クローズアップ科学道 2022」に掲載されました。 地球上に生命が誕生して約40憶年。長い年月を経て生物は多種多様に進化してきました。これはゲノムの進化の歴史でもあります。種ごとの違いはどのようにして生じてきたのか、ジェフリ・フォーセット上級研究員（以下、研究員）は、数理科学のアプローチを取り入れながらこの謎の解明に挑戦しています。 続きは、関連リンクをご覧ください。
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2022-01-13
今週の論文Week 3, January 2022
Title: Biexciton-like quartet condensates in an electron-hole liquid Author: Yixin Guo, Hiroyuki Tajima, Haozhao Liang arXiv: http://arxiv.org/abs/2201.03031v1 Title: Optimized Two-Baryon Operators in Lattice QCD Author: Yan Lyu, Hui Tong, Takuya Sugiura, Sinya Aoki, Takumi Doi, Tetsuo Hatsuda, Jie Meng, Takaya Miyamoto arXiv: http://arxiv.org/abs/2201.02782v1 Title: A MeerKAT, e-MERLIN, H.E.S.S. and Swift search for persistent and transient emission associated with three localised FRBs Author: James O. Chibueze, et al.; H.E.S.S. Collaboration (Naomi Tsuji) arXiv: http://arxiv.org/abs/2201.00069v1 Title: Analyticity of the energy in an Ising spin glass with correlated disorder Author: Hidetoshi Nishimori Journal Reference: J. Phys. A 55, 045001 (2022) doi: https://doi.org/10.1088/1751-8121/ac44ef arXiv: http://arxiv.org/abs/2110.01196v2 Title: The hyperon spectrum from lattice QCD Author: Nolan Miller, Grant Bradley, M. A. Clark, Ben Hörz, Dean Howarth, Malcolm Lazarow, Henry Monge-Camacho, Amy Nicholson, Enrico Rinaldi, Pavlos Vranas, André Walker-Loud arXiv: http://arxiv.org/abs/2201.01343v1 Title: A path integral derivation of the equations of anomalous Hall effect Author: Kazuo Fujikawa, Koichiro Umetsu arXiv: http://arxiv.org/abs/2201.01104v1 Title: Gravitational wave asteroseismology on cooling neutron stars Author: Hajime Sotani, Akira Dohi arXiv: http://arxiv.org/abs/2201.00648v1 Title: Non-Equilibrating a Black Hole with Inhomogeneous Quantum Quench Author: Kanato Goto, Masahiro Nozaki, Kotaro Tamaoka, Mao Tian Tan, Shinsei Ryu arXiv: http://arxiv.org/abs/2112.14388v1 Title: Chaos by Magic Author: Kanato Goto, Tomoki Nosaka, Masahiro Nozaki arXiv: http://arxiv.org/abs/2112.14593v1 Title: Cooling of Isolated Neutron Stars with Pion Condensation: Possible Fast Cooling in a Low-Symmetry-Energy Model Author: Akira Dohi, Helei Liu, Tsuneo Noda, Masa-aki Hashimoto arXiv: http://arxiv.org/abs/2112.13302v1 Title: Dynamical stability and filamentary instability in holographic conductors Author: Shuta Ishigaki, Shunichiro Kinoshita, Masataka Matsumoto arXiv: http://arxiv.org/abs/2112.11677v2
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2022-01-13
イベントスケジュール
Events for the 4th week of January 2022
Monday, January 17, 11:00– 12:00 DMWG Seminar Thursday, January 20, 10:00– 11:00 iTHEMS Biology Seminar Thursday, January 20, 13:30– 15:00 NEW WG Seminar Friday, January 21, 12:30- Coffee Meeting
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2022-01-12
セミナーレポート
iTHEMS Biology Seminar by Prof. Tetsuya Yamamoto on January 6, 2022
On January 6th, Prof. Tetsuya Yamamoto gave us a comprehensive talk about the physical aspects of nuclear bodies. He first introduced the liquid-liquid phase separation and other self-assembly mechanisms in soft-matter physics, such as micelle formation, with motivations from the experimental side. In the main part, he told us about three recent topics regarding how RNAs' dynamics and sequence properties lead to different types of assembly of nuclear bodies. The mathematical formulation, schematic figures, and comparisons with experiments were clear to understand. We are very grateful to Prof. Yamamoto for the exciting seminar. Reported by Kyosuke Adachi
217件のニュース / 2022年