Colloquium

The 6th MACS Colloquium

November 8 (Thu) at 15:00 - 17:30, 2018

Chikara Furusawa (Team Leader, Laboratory for Multiscale Biosystem Dynamics, RIKEN Center for Biosystems Dynamics Research (BDR) / Professor, The University of Tokyo)
Ken Takai (Program Director, Extremobiosphere Research Program, Institute of Biogeosciences, Japan Agency for Marine-Earth Science and Technology (JAMSTEC))

15:00- Teatime 15:15- Talk by Prof. Chikara Furusawa 16:30- Talk by Dr. Ken Takai The 6th MACS colloquium supported by iTHEMS. It will be broadcasted to Wako, but if you can join the colloquium physically in Kyoto, that would be better. iTHEMS provides good cakes/cookies at Kyoto!

Venue: Lecture room #401, Graduate School of Science Building No 6, Kyoto University

Event Official Language: Japanese

Economic Networks: a Physicist's View

October 3 (Wed) at 15:00 - 16:30, 2018

Hideaki Aoyama (Senior Visiting Scientist, iTHEMS / Professor, Graduate School of Science, Kyoto University)

Economic phenomena occur on networks formed by agents, such as firms and financial institutions. In order to understand the dynamic nature of economy, we need to understand structures of those networks and interactions between economic agents on it. In this talk, I will review several important research results on this theme, most of which uses Japanese rich, actual (not simulated) network data, including trade (production) network of about one million firms. Community structures, simulation of effect of natural disasters, new methodology required for such inquiry are some of the topics to be covered.

Venue: Large Meeting Room, 2F Welfare and Conference Building (Cafeteria)

Broadcast:R511, Computational Science Research Building / SUURI-COOL (Kyoto) / SUURI-COOL (Sendai)

Event Official Language: English

Bell's Theorem, Entanglement, Quantum Teleportation and All That

July 19 (Thu) at 16:00 - 17:30, 2018

Anthony James Leggett (Professor, University of Illinois at Urbana-Champaign, USA)

iTHEMS-CEMS Joint Colloquium. Professor Leggett is widely recognized as a world leader in the theory of low-temperature physics, and his pioneering work on superfluidity was recognized by the 2003 Nobel Prize in Physics. Abstract: One of the most surprising aspects of quantum mechanics is that under certain circumstances it does not allow individual physical systems, even when isolated, to possess properties in their own right. This feature, first clearly appreciated by John Bell in 1964, has over the last half-century been tested experimentally and found (in most people's opinion) to be spectacularly confirmed. More recently it has been realized that it permits various operations which are classically impossible, such as "teleportation" and secure-in-principle cryptography. This talk is a very basic introduction to the subject, which requires only elementary quantum mechanics.

Venue: Okochi Hall

Broadcast:#311, Computational Science Research Building / SUURI-COOL (Kyoto) / 2F Seminar Room, AIMR Main Building

Event Official Language: English

The 5th MACS Colloquium

July 3 (Tue) at 15:00 - 17:30, 2018

Keisuke Fujii (Program-Specific Associate Professor, Graduate School of Science, Kyoto University)
Takao Hirajima (Kyoto University)

15:00- Teatime 15:15- Talk by Dr. Keisuke Fujii (Kyoto University) 16:30- Talk by Prof. Takao Hirajima (Kyoto University) The 5th MACS colloquium supported by iTHEMS. It will be broadcasted to Wako by Skype, but if you can join the colloquium physically in Kyoto, that would be better. iTHEMS provides good cakes/cookies at Kyoto!

Venue: Lecture room #401, Graduate School of Science Building No 6, Kyoto University

Broadcast:Seminar Room #160

Event Official Language: Japanese

Systems Biology of Cellular Rhythms

July 2 (Mon) at 15:00 - 16:30, 2018

Albert Goldbeter (Professor, Unit of Theoretical Chronobiology, Faculty of Sciences, Université Libre de Bruxelles, Belgium)

Rhythmic phenomena occur at all levels of biological organization, with periods ranging from milliseconds to years. Among biological rhythms, circadian clocks, of a period close to 24h, play a key role as they allow the adaptation of living organisms to the alternation of day and night. Biological rhythms represent a phenomenon of temporal self-organization in the form of sustained oscillations of the limit cycle type. Mathematical models show how the emergent property of oscillatory behavior arises from molecular interactions in cellular regulatory networks, which explains why cellular rhythms represent a major research topic in systems biology. After providing an introduction to biological rhythms and their modeling, I will focus on mathematical models for two major examples of rhythmic behavior at the cellular level : the circadian clock and the cell cycle. The coupling of these rhythms allows for their synchronization and for the occurrence of more complex patterns of oscillatory behavior. I will discuss the reasons why models for cellular rhythms tend to become more complex, upon incorporating new experimental observations. The case of cellular rhythms allows us to compare the merits of simple versus complex models for the dynamics of biological systems.

Venue: Suzuki Umetaro Hall

Broadcast:#305-2, Computational Science Research Building / SUURI-COOL (Kyoto) / 2F Seminar Room, AIMR Main Building

Event Official Language: English

On the interplay between intrinsic and extrinsic instabilities of spatially localized patterns

June 7 (Thu) at 15:00 - 16:30, 2018

Yasumasa Nishiura (Professor, Advanced Institute for Materials Research (AIMR), Tohoku University)

Spatially localized dissipative structures are observed in various fields, such as neural signaling, chemical reactions, discharge patterns, granular materials, vegetated landscapes, binary convection and block copolymer nanoparticles. These patterns are much simpler than single living cells, however they seem to inherit several characteristic “living state” features, such as generation of new patterns, self-replication, switching to new dynamics via collisions and adaptive morphological changes to environments. These behaviors stem from an interplay between the intrinsic instability of each localized pattern and the strength of external signals. To understand such an interplay, we explore the global geometric interrelation amongst all relevant solution branches of a corresponding system with approximate unfolding parameters. For instance, it has been uncovered that large deformation via strong collision is mapped into the network of unstable patterns in infinite dimensional space, and that an organizing center for 1D pulse generators is a double homoclinicity of butterfly type. Large deformation of patterns is unavoidable so that a global geometric structure formed by all relevant solution branches gives us much more insight rather than conventional PDE approaches. We illustrate the impact of this approach for the case of pulse generators. We also report on the recent exciting finding, namely the formation of exotic 3D nanoparticles of block copolymers caused by the interplay between internal repulsion and affinity to external solvent, which is consistent with experimental results.

Venue: Nishina Hall

Broadcast:#305-2, Computational Science Research Building / SUURI-COOL (Kyoto)

Event Official Language: English

The 4th MACS Colloquium

April 27 (Fri) at 15:00 - 16:45, 2018

Yuji Tachikawa (Professor, Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU), The University of Tokyo)

15:00- Teatime 15:15- Talk by Prof. Yuji Tachikawa 16:45- MACS Student Conference FY2018 The 4th MACS colloquium supported by iTHEMS. It will be broadcasted to Wako by Skype, but if you can join the colloquium physically in Kyoto, that would be better. iTHEMS provides good cakes/cookies at Kyoto!

Venue: Lecture room #401, Graduate School of Science Building No 6, Kyoto University

Broadcast:#433, Main Research Building

Event Official Language: Japanese

The Description of Biological Phenomena as Open System / Every Biological Variable has a Different Dynamic Range

April 23 (Mon) at 15:00 - 16:30, 2018

Kazuhiro Sakurada (Deputy Program Director, Medical Sciences Innovation Hub Program, RIKEN Cluster for Science, Technology and Innovation Hub (RCSTI))
Jun Seita (Unit Leader, AI based Healthcare and Medical Data Analysis Standardization Unit, RIKEN Cluster for Science, Technology and Innovation Hub (RCSTI))

The Description of Biological Phenomena as Open System / Dr. Sakurada Every Biological Variable has a Different Dynamic Range / Dr. Seita

Venue: Okochi Hall

Broadcast:6F auditorium, Computational Science Research Building / SUURI-COOL (Kyoto) / SUURI-COOL (Sendai)

Event Official Language: English

Approaches to inflationary cosmology

December 19 (Tue) at 15:00 - 16:30, 2017

Jun'ichi Yokoyama (The University of Tokyo)

The 24th iTHES Theoretical Science Colloquium

Venue: Okochi Hall

Event Official Language: English

Simulations and machine learning going hand in hand for clinical medicine

October 30 (Mon) at 15:00 - 16:30, 2017

Hiroshi Suito (Professor, Advanced Institute for Materials Research (AIMR), Tohoku University)

The 23rd iTHES Theoretical Science Colloquium Recent rapid progress of AI technologies has strongly affected the medical community, profoundly enhancing medical image analysis as well as improving decision-making in clinical practice. Nevertheless, black-box systems cannot be accepted easily in clinical medicine because of issues related to accountability and incorporation of new and rapidly developing medical technologies. This talk presents a bilateral approach to cardiovascular problems consisting of (1) machine learning approach for estimation of fluid dynamical forces such as wall shear stress and oscillatory shear index by using geometrical information of the vessels; and (2) simulation approach for understanding physical mechanisms, from vessel geometry to wall forces distributions via flow patterns, using fluid–structure interaction analysis based on partial differential equations. This work was conducted as part of our JST-CREST project: "New challenges for mathematical modeling in clinical medicine."

Venue: 2F Large Meeting Room, RIBF Building, RIKEN Wako Campus

Broadcast:R511, Computational Science Research Building

Event Official Language: English

Introduction to topological quantum computing

July 28 (Fri) at 15:00 - 16:30, 2017

Zhenghan Wang (University of California Santa Barbara, USA)

The 22nd iTHES Theoretical Science Colloquium Topological quantum computing is a paradigm to build a quantum computer with topological phases of matter. Majorana physics is the best example of topological physics besides quantum Hall. I will give an introduction to building a topological quantum computer with Majorana zero modes.

Venue: Suzuki Umetaro Hall

Event Official Language: English

Shapes of discrete groups

May 18 (Thu) at 15:30 - 17:00, 2017

Takashi Tsuboi (Deputy Program Director, iTHEMS)

The 21st iTHES Theoretical Science Colloquium I will talk about several attempts to understand infinite groups. The group structure appears almost everywhere in mathematics. Groups describe the symmetry of mathematical objects. A discrete group is a space with usually countably many points which is not an interesting topological space. But people began distinguishing shapes of different groups. For example, the free group on two generators and the free abelian group of rank two should have different shapes. One may think that the shape of the free group on two generators is infinite four valent tree while the shape of the free abelian group of rank two is the lattice on the Euclidean plane. The idea of geometric group theory has been developed to describe the properties of discrete groups. For a finitely presented group, Gromov defined the hyperbolicity of it by looking at its Cayley graph and showed that the hyperbolic groups have many nice properties and it looks like free groups. When we need to investigate groups, first we may look at its abelianization, and then, for example, we may look at its nilpotent approximation. If its abelianization is the trivial group, however, then we should find another way. In this case, we have the commutator length function on the group. Bavard established the notion of stable commutator length and relate it to the space of homogeneous quasimorphisms. We can also look at the conjugation invariant norms. My interest on these invariants came from the study on diffeomorphism groups of manifolds. The identity connected components of diffeomorphism groups of compact connected manifolds have been known to be simple. I could show that for manifolds of dimensions other than 2 and 4, the commutator length function is bounded. There are many interesting infinite simple groups with unbounded commutator length functions, and it would be very interesting to find new methods to describe their shapes.

Venue: Suzuki Umetaro Hall

Event Official Language: English

General Relativity and Gravitational Waves

April 13 (Thu) at 15:00 - 16:30, 2017

Takahiro Tanaka (Professor, Division of Physics and Astronomy, Graduate School of Science, Kyoto University)

The 20th iTHES Theoretical Science Colloquium A hundred years have passed since general relativity was proposed by A. Einstein. This beautiful theory passed all experimental tests so far but almost always in a week gravity regime where perturbative expansion around flat spacetime gives a good approximation. Recent direct detection of gravitational waves by LIGO opened up a new window to test general relativity in a strong gravity regime. At the same time, cosmological observations are getting more and more accurate, which also gives a ground to test the validity of general relativity. I'd like to discuss the progress of this area in the past and what will happen in near future.

Venue: Okochi Hall

Event Official Language: English

Quantum computing by quantum annealing

January 27 (Fri) at 15:00 - 16:30, 2017

Hidetoshi Nishimori (Professor, Tokyo Institute of Technology)

The 19th iTHES Theoretical Science Colloquium Quantum annealing is a generic platform to solve a class of computational problems using quantum mechanical effects. D-Wave Systems in Canada has built hardware to realize quantum annealing and has sold several of their machine to Google, NASA, Los Alamos National Laboratory, and Lockheed-Martin, which raised a good amount of interest not just from scientific communities but also from a wider public. In this talk, I will explain the basic theoretical framework of quantum annealing, overview the current status of hardware and theoretical developments, and discuss its impact on the society in general.

Venue: Okochi Hall

Event Official Language: English