Seminars in Natural Sciences

Abstract:  NO DATA

RECENT SEMINARS:

Abstract:  A moduli space is a space of shapes. When our brain recognizes the similarity in two different shapes, we are unconsciously measuring the distance between two points on the moduli space.

In this talk we present a visual construction of the moduli space, the Weil-Petersson metric, leads us to the integral calculus on the moduli space. The goal of the talk is to illustrate the works of Kontsevich (1992), Mirzakhani (2007) and Mulase-Safnuk (2008) that connect topology of the moduli spaces with analysis of differential equations such as KdV equations and the action of the Virasoro algebra.

Abstract:  We report briefly recent progresses of light-ion, photon and neutrino probes for nuclear particle physics and the APPEAL network (Advanced Physics with Photons, Electrons, and Leptons). APPEAL is an international network formed at JASRI to promote advanced physics with new probes of photons, electrons, and leptons.* The following three subjects are discussed.

1. High energy-resolution light-ion probes at RCNP for hadron nuclear physics.
2. Multi MeV/GeV photon probes at JASRI for quark nuclear physics.
3. Neutrino probes for neutrino nuclear physics.

* H. Ejiri, RCNP, http://www.spring8.or.jp/ext/en/appeal

Abstract:  The results of OECD Programme for International Student Assessment (PISA) conducted in 2006 were released on December 4, 2007. PISA assesses how well our youngsters at 15 years olds are prepared for challenges to real world issues by applying their knowledge and skills and compare the results across countries. PISA in 2006 focused on scientific literacy area and Mr. Ogura was one of key members in developing and analyzing this survey. The talk will address what scientific literacy is in PISA, how it was assessed, and explain he results including reflections on Japanese science literacy education.

Abstract:  Recently, study on direct and indirect interactions between above- and below-ground organisms is a growing field in ecology. Scoliid wasp is an example of organisms linking between above- and below-ground ecosystems, because adult wasps fly around and forage flowers above-ground, while females dig into the soil and hunt soil-dwelling grubs for their offspring. Host search and attack must be very difficult tasks for below-ground parasitoids such as scoliid wasps. In previous observations, it has been suggested that scoliid wasps can detect host grubs in the soil from the surface. However, no empirical studies have examined the host searching behavior of the wasps. How do they locate the host grubs in the soil? In this seminar, I present a new view of the host searching process of scoliid wasps based on my experimental results.

Abstract:  Estrogenic substances which are kinds of endocrine disrupting chemicals (EDCs) cause vitellogenesis of male or immature female fish, and testis-ova formation, one of intersex phenomena, in male fish have been reported by the exposure to high level of estrogens. Estrogenic substances are loaded to river or coastal area from sewage treatment plant (STP). The concentration of estrogenic substances in treated water decreased gradually through the treatment processes, but complete removal of estrogens is not achieved by the present treatment system. However, the treatment method using stones contact oxidization, which was introduced as a test plant in STP in Hyogo Prefecture, was effective for the removal of estrogenic substances. And degradability of estrogens by the microorganism in biofilm on surface of gravels collected from STP was superior to those in Muko River.

Abstract:  The classical way of representing a set in terms of either in affirmation or negation of its membership elements had resulted in inadequacy of mathematical expressions to represent linguistic concepts. A novel path breaking idea called fuzzy sets by Lotfi Asker Zadeh in 1965 made it possible to overcome this to a very large extent. It virtually describes a linguistic concept in a very lucid fashion (not as it was described with limited tools and rigid ideas). This paradigm shift from the Aristotelian two valued logic has opened the flood gates which generated lot of research in this area. Today’s talk tries to introduce the concept of fuzzy sets, its refined form called fuzzy numbers and fuzzy linear programming.

Abstract:  This talk concerns an ongoing project in my lab in which we are trying to gain a better understanding of how archaeal microbes produce pentose (five-carbon sugars) as precursors to DNA and RNA. Archaea are microscopic prokaryotes that make up a separate kingdom of life on earth, distinct from the Bacteria and Eukarya. They are fundamentally different - in terms of their genetic evolutionary history and in many cases their biochemistry - from organisms in the two other kingdoms. Many archaea are 'extremophiles', thriving in conditions that until fairly recently were thought to be incompatible with living things: in the boiling, sulfurous waters of hot springs, in concentrated salt water, and near geothermal vents thousands of metres under the ocean, far from any sources of light or oxygen. The success of recent efforts to sequence the complete genomic blueprints of more than twenty archaeal species has helped to shed light on the details of the biochemistry of these unique organisms. Although many of the known pathways appear to be in place, there are also a large number of cases where enzymes critical to the function of bacterial and eukaryotic cells appear to be missing or unrecognizable. We focus our attention on the 'pentose phosphate pathway' of sugar catabolism, and I will describe in my talk how we cloned and characterized an enzyme called transaldolase.

Abstract:  When valuing and risk-managing exotic derivatives, practitioners demand fast and accurate prices and sensitivities. As the financial models and option contracts used in practice are becoming increasingly complex, efficient methods have to be developed to cope with such models. Aside from nonstandard exotic derivatives, plain vanilla options in many stock markets are actually of the American type, and it is of the utmost importance to be able to value these American options quickly and accurately. To price these options, we can distinguish three types of methods: Monte Carlo simulation, numerical solution of the corresponding partial-(integro) differential equation and numerical integration. The talk presents a novel quadrature-based method for pricing options with early exercise features and provides numerical results based on the FFT algorithm.

Abstract:  Currently we are working on the development of methods for calculating positron scattering off polyatomic molecules and positron affinities of polyatomic molecules. The talk will give an introduction to the methodology, and will present some recent results from our R-matrix calculations group.

Abstract:  Recently, a detailed shape model of an asteroid was reported in Nature, following the first success in asteroid landing and takeoff in the world in autumn 2005, when the asteroidal unmanned explorer HAYABUSA landed on asteroid Itokawa. The shape of Itokawa and its origin will be accompanied by a recent hot topic on planet definition.

Abstract:  Diamond has very promising properties for bio-sensor applications, as it is chemically inert, biocompatible and shows the best electrochemical electrode properties. In addition, the surface conductivity of undoped diamond can be used to process high quality in-plane transistor structures for pH sensing. In this presentation, I will introduce two techniques which we apply to modify diamond surface properties. One is a photochemical attachment process of alkene linker molecules and the second is an electrochemical process which generates a phenyl surface linker layer. Those modified diamond surfaces are used to bond single strand DNA which is then used to detect complementary DNA strands. We apply XPS, electrochemical AFM, fluorescence microscopy, cyclic voltammetry and field effect characterization experiments to reveal the properties of linker and DNA layer on diamond which will be summarized in the seminar. Especially, the amperometric and potentiometric sensitivities of DNA sensors from diamond will be discussed.

Abstract:  Many real systems can be described as networks, composed of a set of nodes and a set of edges connecting the nodes. Interestingly, it has been found that most biological and non-biological networks (e.g., internet, social networks, metabolic and protein-protein interaction networks) have a common architecture, termed scale-free or broad-tail topology. Here, we present our recent research on scale-free networks in biological systems together with an integrative analysis on gene expression space and metabolic space. In particular, we integrate environmental signal-induced expression data with structural data of the yeast metabolic network and analyze the topological properties of the induced or repressed sub-networks. They reveal significant discrepancies from random networks, and in particular exhibit a high connectivity, allowing them to be mapped back to complete metabolic routes.

Abstract:  The filtered cathodic vacuum arc has been proven to be able to deposit high quality films, ranging from diamond-like carbon to metal and metal oxide films. ln this presentation shall like to give a short summary of some of the materials we are currently exploring and their engineering applications. These include 1) studying of depositing both thick and thin diamond-like carbon films with applications in microelectromechanical systems (MEMS). 2) detailed understanding behind the material properties of metal oxide films with applications in optical technology and 3) exploring thefeasibility of using the filtered cathodic vacuum arc to deposit metal and/or metal oxide nanoclusters embedded in diamond-like carbon. Hopefully, this is able to intergrate the excellentproperties of both nanosized materials with the inherent excellent properties of diamond-like carbon for further advanced applications.

Abstract:  Recently, fate and behavior of a pesticide applied for the control of Chi-ronomidae in small stream have been investigated, including the degrada-tion of an organophosphorus pesticide by the bacteria isolated from river water. Fate of natural estrogens such as estron and estradiol in sewage treatment plant were also studied. The main findings will be introduced in the talk.

Abstract:
Imposex, the superimposition of male genital organs (penis and vas deferens) on female gastropods, is cause-specific and occurs at low concentrations of certain organotins such as tributyltin (TBT) and triphenyltin (TPT). Reproductive failure is known to occur in severely affected stages. Here, we will report the present status of gastropod imposex and organotin pollution in Japan, together with endocrine disruption observed in abalone. Among rock shell (Thais clavigera) samples collected between January 1999 and November 2001 from 174 locations along the Japan coast, imposex was still extensively observed. Temporal trends of TBT and TPT in tissues of T. clavigera will be also discussed. The occurrence of imposex, and decreases in catches and in the amount of spawning from parent snails at seed-producing facilities have been recognized in the ivory shell (Babylonia japonica). It can be inferred that suppressed ovarian maturity including spermatogenesis in some cases appeared as dysfunction of ovaries and this might be the cause of the reduction in the spawning volume. Abalone catches in Japan have been decreasing since the 1970s. Various studies have been conducted to determine the cause of the decrease but it still remains unresolved. With the hypothesis that organotins (TBT and TPT) cause reproductive insufficiency in abalone, we have been studying this subject since 1994. Our findings thus far are outlined here. We also have studied the basic biology of T. clavigera to clarify the mode of action of TBT and TPT in the development of imposex. Based on results of experiments to assess the existed hypotheses, such as aromatase- inhibition, we have failed to support them. Finally, we discovered that organotins bound the human retinoid X receptors (hRXRs) with high affinity, and that injection of 9-cis retinoic acid, the natural ligand of hRXRs into females of T. clavigera induced the development of imposex. Cloning of the RXR homologue from T. clavigera revealed that the ligand-binding domain of rock shell RXR was very similar to vertebrate RXR and bound to both 9-cis RA and to organotins. These suggest that RXR plays an important role in inducing the development of imposex, the differentiation and growth of male genital tracts in female gastropods.

Abstract:
We have developed a new class of electrolytes for lithium batteries, based on organosilicon compounds. The new electrolytes have many advantages: they are highly conducting, very stable, nonflammable, nontoxic, and harmless in the environment. The new organosilicon electrolytes are now being used in implantable neurostimulators useful for treating serious medical conditions such as stroke, epilepsy, and spinal cord damage. The chemistry of these new materials will be outlined, and examples of their useful applications will be described.

Abstract:
Our attempts to comprehend the Universe push the atomic physics into regimes which are often beyond current experimental or theoretical capabilities of the field. In this talk I will give examples of the role of atomic physics in the formation of the first stars and protogalaxies, in X-ray emission from active galactic nuclei, in ionization balance calculations, and in studies of the solar wind. For each of these examples, I will discuss our ongoing experimental and theoretical studies which are designed to address these issues.

(NSF)

Abstract:
Borneo is the third largest island in the world and has the richest fauna and flora. However, its forest ecosystem has been rapidly lost in these years. To avoid the further loss of the biodiversity in the island, Malaysia, one of three countries which occupy the island, registered two national parks, Mulu and Kinabalu, as UNESCO's World Heritages. It helped natural reservation and development of 'eco- tourism' in these areas. On the other hand, Indonesian Academy of Science (LIPI) choose Muller Range in Central Kalimantan as a candidate of World Heritage, and asked researchers in the world to participate in basic research in the area. Agreeing with the idea, we have botanized the Muller Range in December 2004, supported by Mitsubishi Foundation. I will introduce how botanization in remote area is carried out, showing various photographs including of new plant species discovered in the area.

Abstract:
One step forward or way back? The space shuttle flight mission STS-114, the first of Return-to-flight series, blasted off on July 26, 2006. After the delay of more than two years, Japanese astronaut Mr. Noguchi flew into space. The minutes of medical and human factor side of the current space flight operations, as well as the new Crew Explosion Vehicle operation aspects will be presented in this talk.