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Kamirenjaku, Japan

International Christian University is a non-denominational private university located in Mitaka, Tokyo, Japan. Commonly known as ICU , the university was founded in 1949. ICU offers 32 majors in undergraduate program as the liberal arts college in Japan. Wikipedia.

Munakata A.,Miyagi University of Education | Kobayashi M.,International Christian University
General and Comparative Endocrinology

Sexual behavior is one of the most profound events during the life cycle of animals that reproduce sexually. After completion of gonadal development that is mediated by various hormones, oviparous teleosts perform a suite of behaviors, often termed as spawning behavior. This is particularly important for teleosts that have their gametes fertilized externally as the behavior patterns ensures the close proximity of both sexes for gamete release, fusion and ultimately the production of offspring. As in other vertebrates, sexual behavior of fish is also under the control of hormones. Testicular androgen is a requirement for male sexual behavior to occur in most fish species that have been studied. Unlike tetrapods, however, ovarian estrogen does not appear to be essential for the occurrence of female sexual behavior for fish that have their gametes fertilized externally. Prostaglandins produced in the ovary after ovulation act as a trigger in some teleosts to induce female sexual behavior. Potentiating effects of gonadotropin-releasing hormone in the brain on sexual behavior are reported in some species. Under endocrine regulation, male and female fish exhibit gender-typical behavior during spawning, but in some fish species there is also some plasticity in their sexual behavior. Sex changing fish can perform both male-typical and female-typical sexual behaviors during their lifetime and this sexual plasticity can also be observed in non-sex changing fish when undergoing hormonal treatment. Although the neuroanatomical basis is not clear in fish, results of field and laboratory observations suggest that some teleosts possess a sexually bipotential brain which can regulate two types of behaviors unlike most other vertebrates which have a discrete sex differentiation of their brain and can only perform gender-typical sexual behavior. © 2009 Elsevier Inc. All rights reserved. Source

Hirashima D.S.,International Christian University
Journal of the Physical Society of Japan

Conditions for the existence of a completely flat band in a crystal of finite thickness are clarified. Furthermore, the condition for the localization of the flat band states near the surfaces is also discussed. It is also found that a completely flat band can appear in a crystal where a lattice point has multiple orbital states. In addition to the known results for honeycomb and diamond lattices, a localized completely flat band is found in a crystal of the wurtzite structure of finite thickness. A completely flat band is also found in many other crystals, but it is extended in the direction perpendicular to the surface. © 2016 The Physical Society of Japan. Source

Okamura H.,International Christian University
Optics Letters

We propose an external-cavity laser diode that uses an electromagnetically actuated collimating lens for wavelength tuning. Because the wavelength in the grating equation is highly sensitive to the incident angle, a slight (~ 1 μm) transverse displacement of the collimating lens induces a wavelength shift of ~1nm.We experimentally demonstrate a single-mode, stable, reproducible, and cw tuning over a range of 8nm. The wavelength is proportional to the current applied to the lens actuator, and no hysteresis is observed within the experimental error. By changing the current, we achieve fast and reproducible wavelength switching. © 2010 Optical Society of America. Source

Imaoka T.,Tokyo Institute of Technology | Kitazawa H.,Tokyo Institute of Technology | Chun W.-J.,International Christian University | Omura S.,Tokyo Institute of Technology | And 2 more authors.
Journal of the American Chemical Society

A relationship between the size of metal particles and their catalytic activity has been established over a nanometer scale (2-10 nm). However, application on a subnanometer scale (0.5-2 nm) is difficult, a possible reason being that the activity no longer relies on the size but rather the geometric structure as a cluster (or superatomic) compound. We now report that the catalytic activity for the oxygen reduction reaction (ORR) significantly increased when only one atom was removed from a magic number cluster composed of 13-platinum atoms (Pt13). The synthesis with an atomic-level precision was successfully achieved by using a dendrimer ligand as the macromolecular template strictly defining the number of metal atoms. It was quite surprising that the Pt12 cluster exhibited more than 2-fold catalytic activity compared with that of the Pt13 cluster. ESI-TOF-mass and EXAFS analyses provided information about the structures. These analyses suggested that the Pt12 has a deformed coordination, while the Pt13 has a well-known icosahedral atomic coordination as part of the stable cluster series. Theoretical analyses based on density functional theory (DFT) also supported this idea. The present results suggest potential activity of the metastable clusters although they have been "missing" species in conventional statistical synthesis. © 2013 American Chemical Society. Source

Jung J.-Y.,International Christian University
First Monday

This paper examines the use of social media after the 2011 Great East Japan Earthquake. Based on media system dependency theory, the study focuses on the ways in which people used different types of social media to cope with a highly ambiguous situation created by the earthquake. A survey of Japanese university students revealed that the respondents used different forms of social media with different goals. Moreover, use of a particular social media type influenced the relative importance of social media for understanding developments relating to the Fukushima nuclear accident. Social media users and non-users also differed with regard to their use of other media. The implications of the current study in the context of ongoing research of the role of media in disaster situations are discussed. Source

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