DSpace Collection:
http://hdl.handle.net/2115/20039
2022-01-18T01:53:08ZEffect of Hydrogen Gas Pressure on Calcium-Aluminum-rich Inclusion Formation in the Protosolar Disk : a Laboratory Simulation of Open-system Melt Crystallization
http://hdl.handle.net/2115/83821
Title: Effect of Hydrogen Gas Pressure on Calcium-Aluminum-rich Inclusion Formation in the Protosolar Disk : a Laboratory Simulation of Open-system Melt Crystallization
Authors: Kamibayashi, Michiru; Tachibana, Shogo; Yamamoto, Daiki; Kawasaki, Noriyuki; Yurimoto, Hisayoshi
Abstract: Calcium-aluminum-rich inclusions (CAIs) are the oldest materials that formed in the protosolar disk. Igneous CAIs experienced melting and subsequent crystallization in the disk during which the evaporation of relatively volatile elements such as Mg and Si occurred. Evaporation from the melt would have played a significant role in the variation of chemical, mineralogical, and petrologic characteristics of the igneous CAIs. In this study, we investigated crystallization of CAI analog melt under disk-like low-pressure hydrogen (P (H2)) conditions of 0.1, 1, and 10 Pa to constrain the pressure condition of the early solar system in which type B CAIs were formed. At P (H2) = 10 Pa, the samples were mantled by melilite crystals, as observed for type B1 CAIs. However, the samples heated at P (H2) = 0.1 Pa exhibited random distribution of melilite, as in type B2 CAIs. At the intermediate P (H2) of 1 Pa, type-B1-like structure formed when the cooling rate was 5 degrees C hr(-1), whereas the formation of type-B2-like structure required a cooling rate faster than 20 degrees C hr(-1). The compositional characteristics of melilite in type B1 and B2 CAIs could also be reproduced by experiments. The results of the present study suggest that P (H2) required for type-B1-like textural and chemical characteristics is greater than 1 Pa. The hydrogen pressure estimated in this study would impose an important constraint on the physical condition of the protosolar disk where type B CAIs were formed.2021-11-30T15:00:00ZKamibayashi, MichiruTachibana, ShogoYamamoto, DaikiKawasaki, NoriyukiYurimoto, HisayoshiCalcium-aluminum-rich inclusions (CAIs) are the oldest materials that formed in the protosolar disk. Igneous CAIs experienced melting and subsequent crystallization in the disk during which the evaporation of relatively volatile elements such as Mg and Si occurred. Evaporation from the melt would have played a significant role in the variation of chemical, mineralogical, and petrologic characteristics of the igneous CAIs. In this study, we investigated crystallization of CAI analog melt under disk-like low-pressure hydrogen (P (H2)) conditions of 0.1, 1, and 10 Pa to constrain the pressure condition of the early solar system in which type B CAIs were formed. At P (H2) = 10 Pa, the samples were mantled by melilite crystals, as observed for type B1 CAIs. However, the samples heated at P (H2) = 0.1 Pa exhibited random distribution of melilite, as in type B2 CAIs. At the intermediate P (H2) of 1 Pa, type-B1-like structure formed when the cooling rate was 5 degrees C hr(-1), whereas the formation of type-B2-like structure required a cooling rate faster than 20 degrees C hr(-1). The compositional characteristics of melilite in type B1 and B2 CAIs could also be reproduced by experiments. The results of the present study suggest that P (H2) required for type-B1-like textural and chemical characteristics is greater than 1 Pa. The hydrogen pressure estimated in this study would impose an important constraint on the physical condition of the protosolar disk where type B CAIs were formed.Zinc-Dependent Oligomerization of Thermus thermophilus Trigger Factor Chaperone
http://hdl.handle.net/2115/83819
Title: Zinc-Dependent Oligomerization of Thermus thermophilus Trigger Factor Chaperone
Authors: Zhu, Haojie; Matsusaki, Motonori; Sugawara, Taiga; Ishimori, Koichiro; Saio, Tomohide
Abstract: Simple Summary:& nbsp;Metal ions often play important roles in biological processes. Thermus thermophilus trigger factor (TtTF) is a zinc-dependent molecular chaperone where Zn2+ has been shown to enhance its folding-arrest activity. However, the mechanisms of how Zn2+ binds to TtTF and how Zn2+ affects the activity of TtTF are yet to be elucidated. As a first step in understanding the mechanism, we performed in vitro biophysical experiments on TtTF to investigate the zinc-binding site on TtTF and unveil how Zn2+ alters the physical properties of TtTF, including secondary structure, thermal stability, and oligomeric state. Our results showed that TtTF binds Zn2+ in a 1:1 ratio, and all three domains of TtTF are involved in zinc-binding. We found that Zn2+ does not affect the thermal stability of TtTF, whereas it does induce partial structural change and promote the oligomerization of TtTF. Given that the folding-arrest activity of Escherichia coli TF (EcTF) is regulated by its oligomerization, our results imply that TtTF exploits Zn2+ to modulate its oligomeric state to regulate the activity.<br>Thermus thermophilus trigger factor (TtTF) is a zinc-dependent molecular chaperone whose folding-arrest activity is regulated by Zn2+. However, little is known about the mechanism of zinc-dependent regulation of the TtTF activity. Here we exploit in vitro biophysical experiments to investigate zinc-binding, the oligomeric state, the secondary structure, and the thermal stability of TtTF in the absence and presence of Zn2+. The data show that full-length TtTF binds Zn2+, but the isolated domains and tandem domains of TtTF do not bind to Zn2+. Furthermore, circular dichroism (CD) and nuclear magnetic resonance (NMR) spectra suggested that Zn2+-binding induces the partial structural changes of TtTF, and size exclusion chromatography-multi-angle light scattering (SEC-MALS) showed that Zn2+ promotes TtTF oligomerization. Given the previous work showing that the activity regulation of E. coli trigger factor is accompanied by oligomerization, the data suggest that TtTF exploits zinc ions to induce the structural change coupled with the oligomerization to assemble the client-binding site, thereby effectively preventing proteins from misfolding in the thermal environment.2021-10-31T15:00:00ZZhu, HaojieMatsusaki, MotonoriSugawara, TaigaIshimori, KoichiroSaio, TomohideSimple Summary:& nbsp;Metal ions often play important roles in biological processes. Thermus thermophilus trigger factor (TtTF) is a zinc-dependent molecular chaperone where Zn2+ has been shown to enhance its folding-arrest activity. However, the mechanisms of how Zn2+ binds to TtTF and how Zn2+ affects the activity of TtTF are yet to be elucidated. As a first step in understanding the mechanism, we performed in vitro biophysical experiments on TtTF to investigate the zinc-binding site on TtTF and unveil how Zn2+ alters the physical properties of TtTF, including secondary structure, thermal stability, and oligomeric state. Our results showed that TtTF binds Zn2+ in a 1:1 ratio, and all three domains of TtTF are involved in zinc-binding. We found that Zn2+ does not affect the thermal stability of TtTF, whereas it does induce partial structural change and promote the oligomerization of TtTF. Given that the folding-arrest activity of Escherichia coli TF (EcTF) is regulated by its oligomerization, our results imply that TtTF exploits Zn2+ to modulate its oligomeric state to regulate the activity.<br>Thermus thermophilus trigger factor (TtTF) is a zinc-dependent molecular chaperone whose folding-arrest activity is regulated by Zn2+. However, little is known about the mechanism of zinc-dependent regulation of the TtTF activity. Here we exploit in vitro biophysical experiments to investigate zinc-binding, the oligomeric state, the secondary structure, and the thermal stability of TtTF in the absence and presence of Zn2+. The data show that full-length TtTF binds Zn2+, but the isolated domains and tandem domains of TtTF do not bind to Zn2+. Furthermore, circular dichroism (CD) and nuclear magnetic resonance (NMR) spectra suggested that Zn2+-binding induces the partial structural changes of TtTF, and size exclusion chromatography-multi-angle light scattering (SEC-MALS) showed that Zn2+ promotes TtTF oligomerization. Given the previous work showing that the activity regulation of E. coli trigger factor is accompanied by oligomerization, the data suggest that TtTF exploits zinc ions to induce the structural change coupled with the oligomerization to assemble the client-binding site, thereby effectively preventing proteins from misfolding in the thermal environment.Theoretical method for near-field Raman spectroscopy with multipolar Hamiltonian and real-time-TDDFT : Application to on- and off-resonance tip-enhanced Raman spectroscopy
http://hdl.handle.net/2115/83818
Title: Theoretical method for near-field Raman spectroscopy with multipolar Hamiltonian and real-time-TDDFT : Application to on- and off-resonance tip-enhanced Raman spectroscopy
Authors: Takenaka, Masato; Taketsugu, Tetsuya; Iwasa, Takeshi
Abstract: Tip-enhanced Raman spectroscopy in combination with scanning tunneling microscopy could produce ultrahigh-resolution Raman spectra and images for single-molecule vibrations. Furthermore, a recent experimental study successfully decoupled the interaction between the molecule and the substrate/tip to investigate the intrinsic properties of molecules and their near-field interactions by Raman spectroscopy. In such a circumstance, more explicit treatments of the near field and molecular interactions beyond the dipole approximation would be desirable. Here, we propose a theoretical method based on the multipolar Hamiltonian that considers full spatial distribution of the electric field under the framework of real-time time-dependent density functional theory. This approach allows us to treat the on- and off-resonance Raman phenomena on the same footing. For demonstration, a model for the on- and off-resonance tip-enhanced Raman process in benzene was constructed. The obtained Raman spectra are well understood by considering both the spatial structure of the near field and the molecular vibration in the off-resonance condition. For the on-resonance condition, the Raman spectra are governed by the transition moment, in addition to the selection rule of off-resonance Raman. Interestingly, on-resonance Raman can be activated even when the near field forbids the pi-pi (*) transition at equilibrium geometry due to vibronic couplings originating from structural distortions.2021-01-13T15:00:00ZTakenaka, MasatoTaketsugu, TetsuyaIwasa, TakeshiTip-enhanced Raman spectroscopy in combination with scanning tunneling microscopy could produce ultrahigh-resolution Raman spectra and images for single-molecule vibrations. Furthermore, a recent experimental study successfully decoupled the interaction between the molecule and the substrate/tip to investigate the intrinsic properties of molecules and their near-field interactions by Raman spectroscopy. In such a circumstance, more explicit treatments of the near field and molecular interactions beyond the dipole approximation would be desirable. Here, we propose a theoretical method based on the multipolar Hamiltonian that considers full spatial distribution of the electric field under the framework of real-time time-dependent density functional theory. This approach allows us to treat the on- and off-resonance Raman phenomena on the same footing. For demonstration, a model for the on- and off-resonance tip-enhanced Raman process in benzene was constructed. The obtained Raman spectra are well understood by considering both the spatial structure of the near field and the molecular vibration in the off-resonance condition. For the on-resonance condition, the Raman spectra are governed by the transition moment, in addition to the selection rule of off-resonance Raman. Interestingly, on-resonance Raman can be activated even when the near field forbids the pi-pi (*) transition at equilibrium geometry due to vibronic couplings originating from structural distortions.Comprehensive Transcriptome Sequencing of Tanaidacea with Proteomic Evidences for Their Silk
http://hdl.handle.net/2115/83798
Title: Comprehensive Transcriptome Sequencing of Tanaidacea with Proteomic Evidences for Their Silk
Authors: Kakui, Keiichi; Fleming, James F; Mori, Masaru; Fujiwara, Yoshihiro; Arakawa, Kazuharu
Abstract: Tanaidaceans are small benthic crustaceans that mainly inhabit diverse marine environments, and they comprise one of the most diverse and abundant macrofaunal groups in the deep sea. Tanaidacea is one of themost thread-dependent taxa in the Crustacea, constructing tubes, spunwith their silk, for shelter. In thiswork,we sequenced and assembled the comprehensive transcriptome of 23 tanaidaceans encompassing 14 families and 4 superfamilies of Tanaidacea, and performed silk proteomics of Zeuxo ezoensis to search for its silk genes. As a result, we identified two families of silk proteins that are conserved across the four superfamilies. The long and repetitive nature of these silk genes resembles that of other silk-producing organisms, and the two families of proteins are similar in composition to silkworm and caddisworm fibroins, respectively. Moreover, the amino acid composition of the repetitive motifs of tanaidacean silk tends to be more hydrophilic, and therefore could be a useful resource in studying their unique adaptation of silk use in a marine environment. The availability of comprehensive transcriptome data in these taxa, coupled with proteomic
evidence of their silk genes, will facilitate evolutionary and ecological studies.2021-11-30T15:00:00ZKakui, KeiichiFleming, James FMori, MasaruFujiwara, YoshihiroArakawa, KazuharuTanaidaceans are small benthic crustaceans that mainly inhabit diverse marine environments, and they comprise one of the most diverse and abundant macrofaunal groups in the deep sea. Tanaidacea is one of themost thread-dependent taxa in the Crustacea, constructing tubes, spunwith their silk, for shelter. In thiswork,we sequenced and assembled the comprehensive transcriptome of 23 tanaidaceans encompassing 14 families and 4 superfamilies of Tanaidacea, and performed silk proteomics of Zeuxo ezoensis to search for its silk genes. As a result, we identified two families of silk proteins that are conserved across the four superfamilies. The long and repetitive nature of these silk genes resembles that of other silk-producing organisms, and the two families of proteins are similar in composition to silkworm and caddisworm fibroins, respectively. Moreover, the amino acid composition of the repetitive motifs of tanaidacean silk tends to be more hydrophilic, and therefore could be a useful resource in studying their unique adaptation of silk use in a marine environment. The availability of comprehensive transcriptome data in these taxa, coupled with proteomic
evidence of their silk genes, will facilitate evolutionary and ecological studies.Geometric analysis of anharmonic downward distortion following paths
http://hdl.handle.net/2115/83749
Title: Geometric analysis of anharmonic downward distortion following paths
Authors: Ebisawa, Shuichi; Tsutsumi, Takuro; Taketsugu, Tetsuya
Abstract: A mathematical aspect of the anharmonic downward distortion following (ADDF) path is discussed. The ADDF method is utilized as an automated reaction path search method, which can explore transition state geometries on a potential energy surface from a potential minimum. We show that the maximum number of the ADD stationary paths intersecting the potential minimum is 2(f + 1) - 2, where f denotes the degree of freedom of the system. We also show that the bifurcation of the ADD stationary path is essential to detect all the transition states connected from a given minimum. The ADDF computation is demonstrated for a H2O molecule in which pitchfork bifurcation is observed.2021-01-04T15:00:00ZEbisawa, ShuichiTsutsumi, TakuroTaketsugu, TetsuyaA mathematical aspect of the anharmonic downward distortion following (ADDF) path is discussed. The ADDF method is utilized as an automated reaction path search method, which can explore transition state geometries on a potential energy surface from a potential minimum. We show that the maximum number of the ADD stationary paths intersecting the potential minimum is 2(f + 1) - 2, where f denotes the degree of freedom of the system. We also show that the bifurcation of the ADD stationary path is essential to detect all the transition states connected from a given minimum. The ADDF computation is demonstrated for a H2O molecule in which pitchfork bifurcation is observed.Massive core/star formation triggered by cloud-cloud collision : Effect of magnetic field
http://hdl.handle.net/2115/83748
Title: Massive core/star formation triggered by cloud-cloud collision : Effect of magnetic field
Authors: Sakre, Nirmit; Habe, Asao; Pettitt, Alex R.; Okamoto, Takashi
Abstract: We study the effect of magnetic field on massive dense core formation in colliding unequal molecular clouds by performing magnetohydrodynamic simulations with sub-parsec resolution (0.015 pc) that can resolve the molecular cores. Initial clouds with the typical gas density of the molecular clouds are immersed in various uniform magnetic fields. The turbulent magnetic fields in the clouds consistent with the observation by Crutcher et al. (2010, ApJ, 725, 466) are generated by the internal turbulent gas motion before the collision, if the uniform magnetic field strength is 4.0 mu G. The collision speed of 10 km s(-1) is adopted, which is much larger than the sound speeds and the Alfven speeds of the clouds. We identify gas clumps with gas densities greater than 5 x 10(-20) g cm(-3) as the dense cores and trace them throughout the simulations to investigate their mass evolution and gravitational boundness. We show that a greater number of massive, gravitationally bound cores are formed in the strong magnetic field (4.0 mu G) models than the weak magnetic field (0.1 mu G) models. This is partly because the strong magnetic field suppresses the spatial shifts of the shocked layer that should be caused by the nonlinear thin shell instability. The spatial shifts promote the formation of low-mass dense cores in the weak magnetic field models. The strong magnetic fields also support low-mass dense cores against gravitational collapse. We show that the numbers of massive, gravitationally bound cores formed in the strong magnetic field models are much larger than in the isolated, non-colliding cloud models, which are simulated for comparison. We discuss the implications of our numerical results on massive star formation.2020-12-31T15:00:00ZSakre, NirmitHabe, AsaoPettitt, Alex R.Okamoto, TakashiWe study the effect of magnetic field on massive dense core formation in colliding unequal molecular clouds by performing magnetohydrodynamic simulations with sub-parsec resolution (0.015 pc) that can resolve the molecular cores. Initial clouds with the typical gas density of the molecular clouds are immersed in various uniform magnetic fields. The turbulent magnetic fields in the clouds consistent with the observation by Crutcher et al. (2010, ApJ, 725, 466) are generated by the internal turbulent gas motion before the collision, if the uniform magnetic field strength is 4.0 mu G. The collision speed of 10 km s(-1) is adopted, which is much larger than the sound speeds and the Alfven speeds of the clouds. We identify gas clumps with gas densities greater than 5 x 10(-20) g cm(-3) as the dense cores and trace them throughout the simulations to investigate their mass evolution and gravitational boundness. We show that a greater number of massive, gravitationally bound cores are formed in the strong magnetic field (4.0 mu G) models than the weak magnetic field (0.1 mu G) models. This is partly because the strong magnetic field suppresses the spatial shifts of the shocked layer that should be caused by the nonlinear thin shell instability. The spatial shifts promote the formation of low-mass dense cores in the weak magnetic field models. The strong magnetic fields also support low-mass dense cores against gravitational collapse. We show that the numbers of massive, gravitationally bound cores formed in the strong magnetic field models are much larger than in the isolated, non-colliding cloud models, which are simulated for comparison. We discuss the implications of our numerical results on massive star formation.G-Tutte Polynomials and Abelian Lie Group Arrangements
http://hdl.handle.net/2115/83747
Title: G-Tutte Polynomials and Abelian Lie Group Arrangements
Authors: Liu, Ye; Tan Nhat Tran; Yoshinaga, Masahiko
Abstract: For a list A of elements in a finitely generated abelian group Gamma and an abelian group G, we introduce and study an associated G-Tutte polynomial, defined by counting the number of homomorphisms from associated finite abelian groups to G. The G-Tutte polynomial is a common generalization of the (arithmetic) Tutte polynomial for realizable (arithmetic) matroids, the characteristic quasi-polynomial for integral arrangements, Branden-Moci's arithmetic version of the partition function of an abelian group-valued Potts model, and the modified Tutte-Krushkal-Renhardy polynomial for a finite CW complex. As in the classical case, G-Tutte polynomials carry topological and enumerative information (e.g., the Euler characteristic, point counting, and the Poincare polynomial) of abelian Lie group arrangements. We also discuss differences between the arithmetic Tutte and the G-Tutte polynomials related to the axioms for arithmetic matroids and the (non-)positivity of coefficients.2020-12-31T15:00:00ZLiu, YeTan Nhat TranYoshinaga, MasahikoFor a list A of elements in a finitely generated abelian group Gamma and an abelian group G, we introduce and study an associated G-Tutte polynomial, defined by counting the number of homomorphisms from associated finite abelian groups to G. The G-Tutte polynomial is a common generalization of the (arithmetic) Tutte polynomial for realizable (arithmetic) matroids, the characteristic quasi-polynomial for integral arrangements, Branden-Moci's arithmetic version of the partition function of an abelian group-valued Potts model, and the modified Tutte-Krushkal-Renhardy polynomial for a finite CW complex. As in the classical case, G-Tutte polynomials carry topological and enumerative information (e.g., the Euler characteristic, point counting, and the Poincare polynomial) of abelian Lie group arrangements. We also discuss differences between the arithmetic Tutte and the G-Tutte polynomials related to the axioms for arithmetic matroids and the (non-)positivity of coefficients.A dual enhancer-silencer element, DES-K16, in mouse spermatocyte-derived GC-2spd(ts) cells
http://hdl.handle.net/2115/83746
Title: A dual enhancer-silencer element, DES-K16, in mouse spermatocyte-derived GC-2spd(ts) cells
Authors: Bandara, Thusitha A. M. K.; Otsuka, Kai; Matsubara, Shin; Shiraishi, Akira; Satake, Honoo; Kimura, Atsushi P.
Abstract: The multifunctionality of genome is suggested at some loci in different species but not well understood. Here we identified a DES-K16 region in an intron of the Kctd16 gene as the chromatin highly marked with epigenetic modifications of both enhancers (H3K4me1 and H3K27ac) and silencers (H3K27me3) in mouse spermatocytes. In vitro reporter gene assay demonstrated that DES-K16 exhibited significant enhancer activity in spermatocyte-derived GC-2spd(ts) and hepatic tumor-derived Hepa1-6 cells, and a deletion of this sequence in GC-2spd(ts) cells resulted in a decrease and increase of Yipf5 and Kctd16 expression, respectively. This was consistent with increased and decreased expression of Yipf5 and Kctd16, respectively, in primary spermatocytes during testis development. While known dual enhancer silencers exert each activity in different tissues, our data suggest that DES-K16 functions as both enhancer and silencer in a single cell type, GC-2spd(ts) cells. This is the first report on a dual enhancer-silencer element which activates and suppresses gene expression in a single cell type. (C) 2020 Elsevier Inc. All rights reserved.2020-12-31T15:00:00ZBandara, Thusitha A. M. K.Otsuka, KaiMatsubara, ShinShiraishi, AkiraSatake, HonooKimura, Atsushi P.The multifunctionality of genome is suggested at some loci in different species but not well understood. Here we identified a DES-K16 region in an intron of the Kctd16 gene as the chromatin highly marked with epigenetic modifications of both enhancers (H3K4me1 and H3K27ac) and silencers (H3K27me3) in mouse spermatocytes. In vitro reporter gene assay demonstrated that DES-K16 exhibited significant enhancer activity in spermatocyte-derived GC-2spd(ts) and hepatic tumor-derived Hepa1-6 cells, and a deletion of this sequence in GC-2spd(ts) cells resulted in a decrease and increase of Yipf5 and Kctd16 expression, respectively. This was consistent with increased and decreased expression of Yipf5 and Kctd16, respectively, in primary spermatocytes during testis development. While known dual enhancer silencers exert each activity in different tissues, our data suggest that DES-K16 functions as both enhancer and silencer in a single cell type, GC-2spd(ts) cells. This is the first report on a dual enhancer-silencer element which activates and suppresses gene expression in a single cell type. (C) 2020 Elsevier Inc. All rights reserved.Reduction of contextual control of conditioned responses by extended Pavlovian training in an insect
http://hdl.handle.net/2115/83745
Title: Reduction of contextual control of conditioned responses by extended Pavlovian training in an insect
Authors: Sato, Misato; Alvarez, Beatriz; Mizunami, Makoto
Abstract: The effect of repetitive training on learned behavior has been an important subject in neuroscience. In instrumental conditioning in mammals, learned action early in training is often goal-driven and controlled by outcome expectancy, but as training progresses, it becomes more habitual and insensitive to outcome devaluation. Similarly, we recently showed in Pavlovian conditioning in crickets (Gryllus bimaculatus) that a conditioned response (CR) is initially sensitive to devaluation of the unconditioned stimulus but becomes insensitive to it after extended training. It is known that habitual responses after extended instrumental training are characterized by a higher context specificity than are initial goal-directed actions in mammals. In this study, we investigated whether this is applicable to Pavlovian conditioning in crickets. In crickets that received a standard amount of training to associate an odor with water reward under illumination, CR under illumination was stronger than that in the dark. In crickets that received extended training under illumination, on the other hand, the level of CR did not differ in different light conditions. Further experiments confirmed that context specificity decreases with the development of behavioral automaticity by extended training, as opposed to findings in instrumental training in mammals. We conclude that the nature of habitual behaviors after extended training differs in different learning systems of animals.2020-12-31T15:00:00ZSato, MisatoAlvarez, BeatrizMizunami, MakotoThe effect of repetitive training on learned behavior has been an important subject in neuroscience. In instrumental conditioning in mammals, learned action early in training is often goal-driven and controlled by outcome expectancy, but as training progresses, it becomes more habitual and insensitive to outcome devaluation. Similarly, we recently showed in Pavlovian conditioning in crickets (Gryllus bimaculatus) that a conditioned response (CR) is initially sensitive to devaluation of the unconditioned stimulus but becomes insensitive to it after extended training. It is known that habitual responses after extended instrumental training are characterized by a higher context specificity than are initial goal-directed actions in mammals. In this study, we investigated whether this is applicable to Pavlovian conditioning in crickets. In crickets that received a standard amount of training to associate an odor with water reward under illumination, CR under illumination was stronger than that in the dark. In crickets that received extended training under illumination, on the other hand, the level of CR did not differ in different light conditions. Further experiments confirmed that context specificity decreases with the development of behavioral automaticity by extended training, as opposed to findings in instrumental training in mammals. We conclude that the nature of habitual behaviors after extended training differs in different learning systems of animals.THE MOTION OF WEAKLY INTERACTING LOCALIZED PATTERNS FOR REACTION-DIFFUSION SYSTEMS WITH NONLOCAL EFFECT
http://hdl.handle.net/2115/83744
Title: THE MOTION OF WEAKLY INTERACTING LOCALIZED PATTERNS FOR REACTION-DIFFUSION SYSTEMS WITH NONLOCAL EFFECT
Authors: Ei, Shin-Ichiro; Ishii, Hiroshi
Abstract: In this paper, we analyze the interaction of localized patterns such as traveling wave solutions for reaction-diffusion systems with nonlocal effect in one space dimension. We consider the case that a nonlocal effect is given by the convolution with a suitable integral kernel. At first, we deduce the equation describing the movement of interacting localized patterns in a mathematically rigorous way, assuming that there exists a linearly stable localized solution for general reaction-diffusion systems with nonlocal effect. When the distances between localized patterns are sufficiently large, the motion of localized patterns can be reduced to the equation for the distances between them. Finally, using this equation, we analyze the interaction of front solutions to some nonlocal scalar equation. Under some assumptions, we can show that the front solutions are interacting attractively for a large class of integral kernels.2020-12-31T15:00:00ZEi, Shin-IchiroIshii, HiroshiIn this paper, we analyze the interaction of localized patterns such as traveling wave solutions for reaction-diffusion systems with nonlocal effect in one space dimension. We consider the case that a nonlocal effect is given by the convolution with a suitable integral kernel. At first, we deduce the equation describing the movement of interacting localized patterns in a mathematically rigorous way, assuming that there exists a linearly stable localized solution for general reaction-diffusion systems with nonlocal effect. When the distances between localized patterns are sufficiently large, the motion of localized patterns can be reduced to the equation for the distances between them. Finally, using this equation, we analyze the interaction of front solutions to some nonlocal scalar equation. Under some assumptions, we can show that the front solutions are interacting attractively for a large class of integral kernels.