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533 results on '"Nakamura, Ken-Ichi"'

1. Traveling wave dynamics for Allen-Cahn equations with strong irreversibility

Author

Akagi, Goro, Kuehn, Christian, and Nakamura, Ken-Ichi

Subjects
Mathematics - Analysis of PDEs
Abstract

Constrained gradient flows are studied in fracture mechanics to describe strongly irreversible (or unidirectional) evolution of cracks. The present paper is devoted to a study on the long-time behavior of non-compact orbits of such constrained gradient flows. More precisely, traveling wave dynamics for a one-dimensional fully nonlinear Allen-Cahn type equation involving the positive-part function is considered. Main results of the paper consist of a construction of a one-parameter family of degenerate traveling wave solutions (even identified when coinciding up to translation) and exponential stability of such traveling wave solutions with some basin of attraction, although they are unstable in a usual sense.

Published
2020
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7. Front propagation and blocking for the competition-diffusion system in a domain of half-lines with a junction.

Author

Morita, Yoshihisa, Nakamura, Ken-Ichi, and Ogiwara, Toshiko

Subjects
SPECIES
Abstract

The two-component Lotka-Volterra competition-diffusion system is well accepted as a model describing the invasion of a superior species into a new habitat. Under a bistable condition, we deal with the system in a domain of half-lines with a single junction and investigate the condition for the invasion from some of the half-lines beyond the junction or blocking the propagation of the superior species. We first give a sufficient condition for the invasion in the whole domain by a subsolution. Then, making use of sub- and supersolutions, we construct a standing front solution blocking the propagation if the number of half-lines occupied by the inferior species is sufficiently larger than that occupied by the superior species. [ABSTRACT FROM AUTHOR]

Published
2023
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8. Establishment of the Norwegian Parliamentary Democracy in 1814: Competition of Christian Frederik and Carl Johan to Gain Control of the Crown

Author

Nakamura, Ken-ichi

Subjects
Storting, parliamentary democracy, Christian Frederik, Carl Johan, the Norwegian Crown
Abstract

Robert A. Dahl and other political scientists have pointed out that Norwegian parliamentary government is one of the most stable democracies in the world. Storting, the supreme legislature of Norway, was established at the constituent assembly at Eidsvoll in 1814. The establishment of the Norwegian constitution was the most important legacy of 1814. This essay illustrates the reasons and the process by which the 112 representatives at Eidsvoll were able to establish the parliamentary democracy in 1814. The constitutional assembly of 1814 faced extraordinary challenges such as the final stage of the Napoleonic War and turmoil in the European political order. To constitute a new political order in Norway, the Norwegian representatives needed not only authority to legitimate themselves, but also power to guarantee their newly established political regime. Unfortunately, the most important players of the Norwegian democracy were neither equipped with adequate authority nor enough power. At this critical moment of change in Norwegian politics, two foreign players stood out -- Christian Frederik and Carl Johan, who competed with each other to gain control of the Norwegian Crown. Christian Frederik, Crown Prince of Denmark-Norway had the authority over Norwegian people and could initiate to establish the constituent assembly at Eidsvoll. Carl Johan, the former French marshal named Jean Baptiste Jules Bernadotte, was elected by Swedish parliament as heir to the Swedish throne. He had shown remarkable military skills and administrative capabilities. This essay notes the two historical factors, which contributed to establish the Norwegian parliamentary democracy. First, the synergy of the liberal nationalism of Norwegian representatives alongside the ambitious initiatives of Christian Frederik, and second the compromises between the Norwegian representatives and the cautious pragmatism of Carl Johan.

Published
2022

10. Quantitative fluorescence in situ hybridization measurement of telomere length in skin with/without sun exposure or actinic keratosis

Author

Ikeda, Hiroyuki, Aida, Junko, Hatamochi, Atsushi, Hamasaki, Yoichiro, Izumiyama-Shimomura, Naotaka, Nakamura, Ken-ichi, Ishikawa, Naoshi, Poon, Steven S., Fujiwara, Mutsunori, Tomita, Ken-ichiro, Hiraishi, Naoki, Kuroiwa, Mie, Matsuura, Masaaki, Sanada, Yukihiro, Kawano, Youichi, Arai, Tomio, and Takubo, Kaiyo

Published
2014
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15. Carbon and nitrogen dynamics in the coastal Sea of Japan inferred from 15 years of measurements of stable isotope ratios of Calanus sinicus

Author

Nakamura, Ken-ichi, Nishimoto, Atsushi, Yasui-Tamura, Saori, Kogure, Yoichi, Nakae, Misato, Iguchi, Naoki, Morimoto, Haruyuki, and Kodama, Taketoshi

Abstract

Both nitrogen and carbon dynamics have changed in the Sea of Japan. We hypothesized that the carbon and nitrogen stable isotope ratios (δ13C and δ15N) of the copepod Calanus sinicus could record changes in the coastal environment of the Sea of Japan. Consequently, these isotope ratios were monitored during the spring at four stations from 2006 to 2020 to identify the changes in carbon and nitrogen dynamics. The δ13C values ranged from −24.7 ‰ to −15.0 ‰ and decreased from the spring bloom (February–March) to the post-bloom (June–July) seasons. These variations were attributed to changes in the physiology of both C. sinicus and phytoplankton δ13C contents. The δ15N values range from 2.8 ‰ to 8.8 ‰, indicating that C. sinicus is a secondary producer; the tendency of the δ15N values to increase from the bloom to the post-bloom seasons was attributable to an increase in the δ15N of phytoplankton. A generalized linear model (GLM) approach indicated that >70 % of the variations in δ13C can be explained by sea surface temperature (SST), sea surface chlorophyll a concentration (SSC), carbon:nitrogen ratio of C. sinicus (C/N ratio), and geographic differences. The residuals of δ13C in the GLM decreased yearly (−0.035 ‰ yr−1). The GLM for δ15N of C. sinicus indicated that δ15N varies with the stage or sex in addition to SST, SSC, C/N ratio, and geographic differences. The δ15N values of female C. sinicus and stage V copepodites were the lowest and highest, respectively. The residuals of δ15N in the GLM did not exhibit a significant interannual trend. These results suggest that the carbon isotope ratio in the secondary producer has linearly changed in the coastal Sea of Japan over the past 15 years. Moreover, the changes in carbon dynamics of this area have been recorded and observed to impact the marine ecosystem, while the nitrogen dynamics have not been recorded despite the increasing nitrogenous nutrient inputs in this sea.

Published
2022

22. Feeding ecology of juvenile Pacific bluefin tuna

Author

Sato, Takuya, primary, Nakamura, Ken-ichi, additional, Nishimoto, Atsushi, additional, Tawa, Atsushi, additional, Kodama, Taketoshi, additional, Suzuki, Nobuaki, additional, Ashida, Hiroshi, additional, and Tanaka, Hiroshige, additional

Published
2021
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24. Telomere attrition in beta and alpha cells with age

Author

Tamura, Yoshiaki, Izumiyama-Shimomura, Naotaka, Kimbara, Yoshiyuki, Nakamura, Ken-ichi, Ishikawa, Naoshi, Aida, Junko, Chiba, Yuko, Matsuda, Yoko, Mori, Seijiro, Arai, Tomio, Fujiwara, Mutsunori, Poon, Steven SS, Ishizaki, Tatsuro, Araki, Atsushi, Takubo, Kaiyo, and Ito, Hideki

Published
2016
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27. Hepatocellular Telomere Length in Biliary Atresia Measured by Q-FISH

Author

Sanada, Yukihiro, Aida, Junko, Kawano, Youichi, Nakamura, Ken-ichi, Shimomura, Naotaka, Ishikawa, Naoshi, Arai, Tomio, Poon, Steven S. S., Yamada, Naoya, Okada, Noriki, Wakiya, Taiichi, Hayashida, Makoto, Saito, Takeshi, Egami, Satoshi, Hishikawa, Shuji, Ihara, Yoshiyuki, Urahashi, Taizen, Mizuta, Koichi, Yasuda, Yoshikazu, Kawarasaki, Hideo, and Takubo, Kaiyo

Published
2012
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39. Regulation of DNA replication machinery by Mrc1 in fission yeast

Author

Nitani, Naoki, Nakamura, Ken-ichi, Nakagawa, Chie, Masukata, Hisao, and Nakagawa, Takuro

Subjects
DNA replication -- Analysis, Yeast fungi -- Physiological aspects, Yeast fungi -- Genetic aspects, Cell division -- Research, Genetic regulation, Biological sciences
Abstract

Faithful replication of chromosomes is crucial to genome integrity. In yeast, the ORC binds replication origins throughout the cell cycle. However, Cdc45 binds these before S-phase, and, during replication, it moves along the DNA with MCM helicase. When replication progression is inhibited, checkpoint regulation is believed to stabilize the replication fork; the detailed mechanism, however, remains unclear. To examine the relationship between replication initiation and elongation defects and the response to replication elongation block, we used fission yeast mutants of Orc1 and Cdc45--orp1-4 and sna41-928, respectively--at their respective semipermissive temperatures with regard to BrdU incorporation. Both orp1 and sna41 cells exhibited HU hypersensitivity in the absence of Chk1, a DNA damage checkpoint kinase, and were defective in full activation of Cds1, a replication checkpoint kinase, indicating that normal replication is required for Cds1 activation. Mrc1 is required to activate Cdsl and prevent the replication machinery from uncoupling from DNA synthesis. We observed that, while either the orp1 or the sna41 mutation partially suppressed HU sensitivity of cds1 cells, sna41 specifically suppressed that of mrc1 cells. Interestingly, sna41 alleviated the defect in recovery from HU arrest without increasing Cdsl activity. In addition to sna41, specific mutations of MCM suppressed the HU sensitivity of mrc1 cells. Thus, during elongation, Mrc1 may negatively regulate Cdc45 and MCM helicase to render stalled forks capable of resuming replication.

Published
2006

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