iTHEMS生物学セミナー
165 イベント
生物学に関連する様々なトピックを扱ったセミナーを定期的に開催しています。生物学と数学・物理学との境界を低くし、接点を見つけ出すことで、新しい学際的な研究のアイデアが生まれることを期待しています。
詳細はiTHEMS生物学セミナースタディーグループのページをご覧下さい。
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Waveform Analysis of Biological Rhythms
2020年7月1日(水) 10:00 - 11:00
儀保 伸吾 (数理創造プログラム 特別研究員)
Nonlinear oscillatory phenomena often emerge in various systems, for example circadian rhythms in biological systems and acoustic vibrations in engineering. Analysis and control of these oscillatory phenomena are one of the big problems in science and technology. My main research field is biological oscillations, especially circadian clocks. The circadian clocks are based on gene-activity rhythms with approximately 24-hour period, and its temporal waveforms are of various shapes. Recently, we theoretically showed that the period of circadian clocks is proportional to the waveform distortion from sinusoidal waves. Interestingly, we found the waveform is important for periods not only in biological oscillations but also in several other types of nonlinear oscillator models.
会場: via Zoom
イベント公式言語: 英語
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Turing Patterns in Biology and Beyond
2020年6月10日(水) 10:00 - 10:45
スクロツキ マーティン (数理創造プログラム 客員研究員 / Fellow, German Academic Scholarship Foundation, Germany)
In his 1952 paper "The chemical basis of morphogenesis", Alan M. Turing presented a model for the formation of skin patterns. While it took several decades, the model has been validated, e.g. in the skin pattern formation of zebrafish. More surprising, seemingly unrelated pattern formations can also be studied via the model, like e.g. the formation of plant patches around termite hills. In 1984, David A. Young proposed a discretization of Turing's model, reducing it to a activator/inhibitor process on a discrete domain. In my talk, I will present both the model of Turing and its discretization. We will then consider a generalization to pattern-formation in three-dimensional space and investigate the related parameter space.
会場: via Zoom
イベント公式言語: 英語
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Quantification model of energy of loop structure on biopolymer
2020年6月3日(水) 10:00 - 10:45
横田 宏 (数理創造プログラム 特別研究員)
During cell division, the chromatin fiber condenses into a rod-like shape, which is the so-called chromosome. The chromosome is constructed by consecutive chromatin loop structures whose excluded volume interaction gives chromosome its stiffness. So far, the energy source for the loop growing has remained a controversial issue. In this seminar, we quantify the energy source by calculating the free energy difference before and after a model polymer chain creating a loop structure.
会場: via Zoom
イベント公式言語: 英語
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セミナー
Forgetting in Reinforcement Learning Links Sustained Dopamine Signals to Motivation
2020年5月27日(水) 10:00 - 10:45
加藤 郁佳 (理化学研究所 脳神経科学研究センター (CBS) / 東京大学 博士課程)
Dopamine (DA) has been suggested to have two reward-related roles: (1) representing reward-prediction-error (RPE), and (2) providing motivational drive. Role(1) is based on the physiological results that DA responds to unpredicted but not predicted reward, whereas role(2) is supported by the pharmacological results that blockade of DA signaling causes motivational impairments such as slowdown of self-paced behavior. Whereas synaptic/circuit mechanisms for role(1), i.e., how RPE is calculated in the upstream of DA neurons and how RPE-dependent update of learned-values occurs through DA-dependent synaptic plasticity, have now become clarified, mechanisms for role(2) remain unclear. We modeled self-paced behavior by a series of ‘Go’ or ‘No-Go’ selections in the framework of reinforcement-learning assuming DA's role(1), and demonstrated that incorporation of decay/forgetting of learned-values, which is presumably implemented as decay of synaptic strengths storing learned-values, provides a potential unified mechanistic account for the DA's two roles, together with its various temporal patterns.
会場: via Zoom
イベント公式言語: 英語
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Models to describe how virus spreads in vitro
2020年5月13日(水) 10:00 - 10:45
カトゥリン・ボシゥメン (数理創造プログラム 客員主管研究員 / Professor, Department of Physics, Ryerson University, Canada)
This is meant as an introductory talk about my research field, virophysics, in which I apply the rigour and methods of physics to study virology. My focus is primarily in vitro (how virus spreads cell-to-cell in a cell culture) but I occasionally do some in vivo work. Recently, my hobby became tracking COVID-19 spread.
会場: via Zoom
イベント公式言語: 英語
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セミナー
Slip or (k)not: Geometry and mechanical performance of physical knots
2020年5月7日(木) 17:00 - 17:45
佐野 友彦 (PD, École polytechnique fédérale de Lausanne, Switzerland)
Knots can impart unique mechanical function to filamentary structures, with examples ranging across length scales, including DNA, polymer-chains, shoelaces, climbing ropes, tennis racket, and surgical sutures. Even though knot theory has a long history of studies in the realm of mathematics, mechanics-based studies of physical knots are much rarer. The fundamental challenge in the understanding of their mechanics under a wide range of loading conditions stems from the fact that their topology, geometry, elasticity, and friction are all tangled ingredients. In this talk, combining experiments, simulations and theory, we present the recent progress on the predictive framework for the knot performance.
会場: via Zoom
イベント公式言語: 英語
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Analyses of large-scale sequence data from “PROTIST” can reveal the eukaryotic phylogeny and evolution
2020年4月30日(木) 10:00 - 10:45
矢﨑 裕規 (数理創造プログラム 特別研究員)
Most of the phylogenetic diversity of eukaryotes is made up of unicellular eukaryotic microorganisms called protists, some of which have not known phylogenetic home (called Orphans). Orphans are likely to hold important keys to the evolution of eukaryotes. In this seminar, I will introduce present case studies that reveal phylogenetic home and organelle evolution of orphan protists through sequence analysis based on large-scale sequence data.
会場: via Zoom
イベント公式言語: 英語
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セミナー
Social evolution in viruses
2020年4月22日(水) 10:00 - 10:45
アッシャー・リークス (数理創造プログラム 国際プログラム・アソシエイト / Ph.D. Student, Department of Zoology, University of Oxford, UK)
Viruses are normally thought of as solitary organisms. However, in reality viruses often interact with one another, and these interactions can have important consequences for how viruses evolve and cause disease. In this talk, I will show how simple models of virus-virus interactions can help us to understand some puzzling aspects of virus biology. At the end, I will also talk about a new modelling project on Covid-19 joint with Ryosuke, which considers how human actions such as social distancing could influence the evolution of virulence.
会場: via Zoom
イベント公式言語: 英語
165 イベント
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