Aomori Shi, Japan
Aomori Shi, Japan

Aomori University is a private university located in the city of Aomori, Japan, founded in 1968. Wikipedia.

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Shirasaka S.,Tokyo Institute of Technology | Kurebayashi W.,Aomori University | Nakao H.,Tokyo Institute of Technology
Chaos | Year: 2017

Phase reduction framework for limit-cycling systems based on isochrons has been used as a powerful tool for analyzing the rhythmic phenomena. Recently, the notion of isostables, which complements the isochrons by characterizing amplitudes of the system state, i.e., deviations from the limit-cycle attractor, has been introduced to describe the transient dynamics around the limit cycle [Wilson and Moehlis, Phys. Rev. E 94, 052213 (2016)]. In this study, we introduce a framework for a reduced phase-amplitude description of transient dynamics of stable limit-cycling systems. In contrast to the preceding study, the isostables are treated in a fully consistent way with the Koopman operator analysis, which enables us to avoid discontinuities of the isostables and to apply the framework to system states far from the limit cycle. We also propose a new, convenient bi-orthogonalization method to obtain the response functions of the amplitudes, which can be interpreted as an extension of the adjoint covariant Lyapunov vector to transient dynamics in limitcycling systems. We illustrate the utility of the proposed reduction framework by estimating the optimal injection timing of external input that efficiently suppresses deviations of the system state from the limit cycle in a model of a biochemical oscillator.

Shirasaka S.,Tokyo Institute of Technology | Kurebayashi W.,Aomori University | Nakao H.,Tokyo Institute of Technology
Physical Review E - Statistical, Nonlinear, and Soft Matter Physics | Year: 2017

Hybrid dynamical systems characterized by discrete switching of smooth dynamics have been used to model various rhythmic phenomena. However, the phase reduction theory, a fundamental framework for analyzing the synchronization of limit-cycle oscillations in rhythmic systems, has mostly been restricted to smooth dynamical systems. Here we develop a general phase reduction theory for weakly perturbed limit cycles in hybrid dynamical systems that facilitates analysis, control, and optimization of nonlinear oscillators whose smooth models are unavailable or intractable. On the basis of the generalized theory, we analyze injection locking of hybrid limit-cycle oscillators by periodic forcing and reveal their characteristic synchronization properties, such as ultrafast and robust entrainment to the periodic forcing and logarithmic scaling at the synchronization transition. We also illustrate the theory by analyzing the synchronization dynamics of a simple physical model of biped locomotion. © 2017 American Physical Society.

Honda M.,University of Tokyo | Athar M.S.,Aligarh Muslim University | Kajita T.,University of Tokyo | Kasahara K.,Waseda University | Midorikawa S.,Aomori University
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2015

We extend our calculation of the atmospheric neutrino fluxes to polar and tropical regions. It is well known that the air density profiles in the polar and the tropical regions are different from the mid-latitude region. Also there are large seasonal variations in the polar region. In this extension, we use the NRLMSISE-00 global atmospheric model J.M. Picone, J. Geophys. Res. 107, SIA 15 (2002), replacing the U.S.-standard 1976 atmospheric model, which has no positional or seasonal variations. With the NRLMSISE-00 atmospheric model, we study the atmospheric neutrino flux at the polar and tropical regions with seasonal variations. The geomagnetic model international geomagnetic reference field (IGRF) we have used in our calculations seems accurate enough in the polar regions also. However, the polar and the equatorial regions are the two extremes in the IGRF model, and the magnetic field configurations are largely different from one another. Note that the equatorial region is also the tropical region generally. We study the effect of the geomagnetic field on the atmospheric neutrino flux in these extreme regions. © 2015 American Physical Society.

Sajjad Athar M.,Aligarh Muslim University | Honda M.,University of Tokyo | Kajita T.,University of Tokyo | Kasahara K.,Waseda University | Midorikawa S.,Aomori University
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2013

We present the calculation of the atmospheric neutrino fluxes for the neutrino experiments proposed at INO, South Pole and Pyhäsalmi. Neutrino fluxes have been obtained using ATMNC, a simulation code for cosmic ray in the atmosphere. Even using the same primary flux model and the interaction model, the calculated atmospheric neutrino fluxes are different for the different sites due to the geomagnetic field. The prediction of these fluxes in the present Letter would be quite useful in the experimental analysis. © 2012 Elsevier B.V.

Yamazaki A.,Tohoku University | Kidachi Y.,Aomori University | Minokawa T.,Tohoku University
Development Growth and Differentiation | Year: 2012

Blastomere composition and expression profiles of wnt8 and hox11/13b orthologues were examined in the primitive indirect-developing echinoid Prionocidaris baculosa. We found that blastomere composition in the 16-cell-stage Prionocidaris embryos was different from that of the indirect-developing echinoids belonging to Euechinoidea, a derived group of the echinoids. The sizes of the blastomeres in the 16-cell-stage embryo varied, and no embryos formed a "micromere quartet," a group of four equal-sized micromeres. The smallest blastomere was usually located around the vegetal pole. We also found significant differences in early expression profiles of wnt8 orthologues of the Prionocidaris and euechinoids. Unlike euechinoids, the expression of wnt8 orthologue of Prionocidaris was not detected at the 16-cell stage; it began at the 32-cell stage in the broad area containing the vegetal pole. However, in later stages, the expression profiles of hox11/13b and wnt8 orthologues of Prionocidaris were similar to that of euechinoid orthologues. The present study suggests that there are considerable differences between Prionocidaris and euechinoids in early developmental mechanisms in the vicinity of the vegetal pole. © 2012 Japanese Society of Developmental Biologists.

Osada K.,Health Sciences University of Hokkaido | Kurihara K.,Aomori University | Izumi H.,Health Sciences University of Hokkaido | Kashiwayanagi M.,Asahikawa Medical College
PLoS ONE | Year: 2013

Background:The common grey wolf (Canis lupus) is found throughout the entire Northern hemisphere and preys on many kinds of mammals. The urine of the wolf contains a number of volatile constituents that can potentially be used for predator-prey chemosignalling. Although wolf urine is put to practical use to keep rabbits, rodents, deer and so on at bay, we are unaware of any prior behavioural studies or chemical analyses regarding the fear-inducing impact of wolf urine on laboratory mice.Methodology/Principal Findings:Three wolf urine samples harvested at different times were used in this study. All of them induced stereotypical fear-associated behaviors (i.e., avoidance and freezing) in female mice. The levels of certain urinary volatiles varied widely among the samples. To identify the volatiles that provoked avoidance and freezing, behavioural, chemical, and immunohistochemical analyses were performed. One of the urine samples (sample C) had higher levels of 2,6-dimethylpyrazine (DMP), trimethylpyrazine (TMP), and 3-ethyl-2,5-dimethyl pyrazine (EDMP) compared with the other two urine samples (samples A and B). In addition, sample C induced avoidance and freezing behaviours more effectively than samples A and B. Moreover, only sample C led to pronounced expression of Fos-immunoreactive cells in the accessory olfactory bulb (AOB) of female mice. Freezing behaviour and Fos immunoreactivity were markedly enhanced when the mice were confronted with a mixture of purified DMP, TMP, and EDMP vs. any one pyrazine alone.Conclusions/Significance:The current results suggest that wolf urinary volatiles can engender aversive and fear-related responses in mice. Pyrazine analogues were identified as the predominant active components among these volatiles to induce avoidance and freezing behaviours via stimulation of the murine AOB. © 2013 Osada et al.

Yamazaki A.,Tohoku University | Kidachi Y.,Aomori University | Yamaguchi M.,Kanazawa University | Minokawa T.,Tohoku University
Development (Cambridge) | Year: 2014

Echinoids (sea urchins) are divided into two major groups -cidaroids (a 'primitive' group) and euechinoids (a 'derived' group). The cidaroids are a promising model species for understanding the ancestral developmental mechanisms in echinoids, but little is known about the molecular mechanisms of cidaroid development. In euechinoids, skeletogenic mesenchyme cell specification is regulated by the double-negative gate (DNG), in which hesC represses the transcription of the downstream mesenchyme specification genes (alx1, tbr and ets1), thereby defining the prospective mesenchyme region. To estimate the ancestral mechanism of larval mesenchyme cell specification in echinoids, the expression patterns and roles of mesenchyme specification genes in the cidaroid Prionocidaris baculosa were examined. The present study reveals that the expression pattern and function of hesC in P. baculosa were inconsistent with the DNG model, suggesting that the euechinoid-type DNG is not utilized during cidaroid mesenchyme specification. In contrast with hesC, the expression patterns and functions of alx1, tbr and ets1 were similar between P. baculosa and euechinoids. Based on these results, we propose that the roles of alx1, tbr and ets1 in mesenchyme specification were established in the common ancestorof echinoids, and that the DNG system was acquired in the euechinoid lineage after divergence from the cidaroid ancestor. The evolutionary timing of the establishment of the DNG suggests that the DNG was originally related to micromere and/or primary mesenchyme cell formation but not to skeletogenic cell differentiation. © 2014. Published by The Company of Biologists Ltd.

Honda M.,University of Tokyo | Kajita T.,University of Tokyo | Kasahara K.,Waseda University | Midorikawa S.,Aomori University
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2011

We present the calculation of the atmospheric neutrino fluxes with an interaction model named JAM, which is used in PHITS (Particle and Heavy-Ion Transport code System). The JAM interaction model agrees with the HARP experiment a little better than DPMJET-III. After some modifications, it reproduces the muon flux below 1GeV/c at balloon altitudes better than the modified DPMJET-III, which we used for the calculation of atmospheric neutrino flux in previous works. Some improvements in the calculation of atmospheric neutrino flux are also reported. © 2011 American Physical Society.

Nagakura Y.,Aomori University
Expert Opinion on Drug Discovery | Year: 2015

'Dysfunctional pain', a type of chronic pain, is associated with a broad range of clinical disorders, including fibromyalgia, irritable bowel syndrome and interstitial cystitis. It is emerging as a serious issue due to the negative impact of inexplicable pain on quality of life, lack of effective therapies and health care cost. Although drug discovery efforts in pain research have so far focused primarily on inflammatory and neuropathic pain, this editorial attracts attention to dysfunctional pain research and discusses a possible fundamental framework for tackling this difficult issue. While dysfunctional pain is characterized by chronic widespread or regional pain symptoms and occurrence of pain amplification, underlying pathophysiologies remain to be identified. Thus, a pivotal step in future research would be the exploration of pathophysiological pathways, such as relevant molecular networks, which are responsible for dysfunctional pain. Utilization of developing technologies paves the way for the identification of underlying pathophysiologies and the development of effective drugs which would eventually solve the clinical issues associated with dysfunctional pain. © 2015 © Informa UK, Ltd.

Kurihara K.,Aomori University
BioMed Research International | Year: 2015

Three umami substances (glutamate, 5′-inosinate, and 5′-guanylate) were found by Japanese scientists, but umami has not been recognized in Europe and America for a long time. In the late 1900s, umami was internationally recognized as the fifth basic taste based on psychophysical, electrophysiological, and biochemical studies. Three umami receptors (T1R1 + T1R3, mGluR4, and mGluR1) were identified. There is a synergism between glutamate and the 5′-nucleotides. Among the above receptors, only T1R1 + T1R3 receptor exhibits the synergism. In rats, the response to a mixture of glutamate and 5′-inosinate is about 1.7 times larger than that to glutamate alone. In human, the response to the mixture is about 8 times larger than that to glutamate alone. Since glutamate and 5′-inosinate are contained in various foods, we taste umami induced by the synergism in daily eating. Hence umami taste induced by the synergism is a main umami taste in human. © 2015 Kenzo Kurihara.

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