Search

Your search keyword '"Nakajima, Takuro"' showing total 14 results
Start Over Author "Nakajima, Takuro"
14 results on '"Nakajima, Takuro"'

1. Controllable inter-skyrmion attractions and resulting skyrmion-lattice structures in two-dimensional chiral magnets with in-plane anisotropy

Author

Kameda, Mai, Koyama, Rio, Nakajima, Takuro, and Kawaguchi, Yuki

Subjects
Condensed Matter - Mesoscale and Nanoscale Physics
Abstract

We study inter-skyrmion interactions and stable spin configurations in a 2D chiral magnet with in-plane anisotropies of a tilted magnetic field and the magneto-crystalline anisotropy on a (011) thin film. We find that in both cases a small deformation of a skyrmion shape makes the inter-skyrmion interaction anisotropic, and that the skyrmions are weakly bounded along a certain direction due to an emergent attractive interaction. Furthermore, when the magneto-crystalline anisotropy is comparable to the Zeeman energy, skyrmions embedded in a uniform magnetization are tightly bound by creating a magnetic domain between them. The formation of the magnetic domain, and thus the strength of the inter-skyrmion interaction, can be controlled by the direction of an external magnetic field. The anisotropic interaction also affects the skyrmion alignment in the skyrmion crystal (SkX) phase. By employing the Monte Carlo simulation and the micromagnetic simulation, we obtain an elongated triangular lattice structure in the SkX phase. In particular, in the presence of a strong magneto-crystalline anisotropy, magnetic domains appear in the background of the lattice structure, and bimerons aligned on the domain walls form an elongated triangular lattice. We also find a parameter region that the SkX phase is stabilized due to the inter-skyrmion attraction., Comment: 21 pages,17 figures

Published
2021
Full Text
View/download PDF

4. Effects of growth hormone and cortisol administration on plasma insulin-like growth factor binding proteins in juveniles of three subspecies of masu salmon (Oncorhynchus masou)

Author

Yamaguchi, Ginnosuke, Habara, Shiori, Suzuki, Shotaro, Ugachi, Yuki, Kawai, Hisashi, Nakajima, Takuro, Shimizu, Munetaka, Yamaguchi, Ginnosuke, Habara, Shiori, Suzuki, Shotaro, Ugachi, Yuki, Kawai, Hisashi, Nakajima, Takuro, and Shimizu, Munetaka

Abstract

In this study, we examined the effects of porcine growth hormone (GH) and cortisol on plasma insulin-like growth factor binding proteins (IGFBPs) in juveniles of three subspecies of Oncorhynchus masou (masu, amago, and Biwa salmon). Ligand blotting using digoxigenin-labeled human IGF-I was used to detect and semi-quantify three major circulating IGFBP bands at 41, 28, and 22 kDa, corresponding to IGFBP-2b, -1a, and -1b, respectively. GH increased plasma IGFBP-2b concentration in masu and Biwa salmon but suppressed it in amago salmon. Plasma IGFBP-2b levels were increased by cortisol in the three subspecies. Cortisol induced plasma IGFBP-1a in the three subspecies, whereas GH had a suppressive effect in masu and Biwa salmon. Sham and cortisol injections increased plasma IGFBP-1b levels after 1 day in masu and amago salmon, suggesting that IGFBP-1b is induced following exposure to stressors via cortisol. Increased IGFBP-1b levels were restored to basal levels when co-injected with GH in Biwa salmon, and the same trend was seen in masu and amago salmon. However, the suppressive effect of GH disappeared 2 days after injection in the three subspecies. Despite some differences among subspecies, the findings suggest that cortisol is a primary inducer of plasma IGFBP-1b; however, GH counteracts it in the short term. Therefore, GH has the potential to modulate the degree of increase in circulating IGFBP-1b levels during acute stress.

Published
2021

6. Power stabilization of high‐power CO laser by gas composition control

Author

Naohito Yamaguchi, Tatsuji Taira, Hirotaka Kanazawa, and Nakajima Takuro

Subjects
Materials science, Gas laser, business.industry, chemistry.chemical_element, Laser, Oxygen, Power level, law.invention, Power (physics), chemistry.chemical_compound, chemistry, law, Carbon dioxide, Optoelectronics, Gas composition, business, Instrumentation, Carbon monoxide
Abstract

Long time, stable operation of a high‐power discharge‐excited CO laser has been attained by controlling the laser gas composition. Firstly, stable obtainable laser output power was measured against the quantities of CO2 and of O2 added to the laser gas. Next, laser gas composition was recorded during sealed‐off operation with various initial gas conditions and cooling conditions. Finally, the detractive effect of O2 (added to enhance attainable output power through discharge stabilization) of quickening CO2 generation and CO depletion, was counteracted through continuous extraction of the laser gas and parallel replacement with fresh gas of predetermined composition. The resulting stabilization of the laser gas composition reduced output power variations to ±3% at 3 kW power level.

Published
1991

8. Relationships between gill Na+,K+-ATPase activity and endocrine and local insulin-like growth factor-I levels during smoltification of masu salmon (Oncorhynchus masou)

Author

Shimomura, Takahiro, Nakajima, Takuro, Horikoshi, Moeri, Iijima, Anai, Urabe, Hirokazu, Mizuno, Shinya, Hiramatsu, Naoshi, Hara, Akihiko, Shimizu, Munetaka, Shimomura, Takahiro, Nakajima, Takuro, Horikoshi, Moeri, Iijima, Anai, Urabe, Hirokazu, Mizuno, Shinya, Hiramatsu, Naoshi, Hara, Akihiko, and Shimizu, Munetaka

Abstract

We established profiles of insulin-like growth factor (IGF)-I mRNA in the liver, gill and white muscle and circulating IGF-I during smoltification of hatchery-reared masu salmon, and compared with that of gill Na+,K+-ATPase (NKA) activity. Gill NKA activity peaked in May, and dropped in June. Liver igf1mRNA was high in March and decreased to low levels thereafter. Gill igf1 increased from March, maintained its high levels during April and May and decreased in June. Muscle igf1 mRNA levels were relatively high during January and April when water temperature was low. Serum IGF-I continuously increased from March through June. Serum IGF-I during March and May showed a positive correlation with NKA activity, although both were also related to fish size. These parameters were standardized with fork length and re-analyzed. As a result, serum IGF-I and gill igf1 were correlated with NKA activity. On the other hand, samples from desmoltification period (June) that had high serum IGF-I levels and low NKA activity disrupted the relationship. Expression of two IGF-I receptor (igf1r) subtypes in the gill decreased in June, which could account for the disruption by preventing circulating IGF-I from acting on the gill and retaining it in the blood. The present study suggests that the increase in gill NKA activity in the course of smoltification of masu salmon was supported by both endocrine and local IGF-I, and the decrease during desmoltification in freshwater was due at least in part to the down-regulation of gill IGF-I receptors.

Published
2012

10. Power stabilization of high-power industrial CO laser using gas exchange

Author

Nakajima Takuro, Yasunori Hamano, Tatsuji Taira, Ryoichi Satani, Naohito Yamaguchi, and Hirotaka Kanazawa

Subjects
chemistry.chemical_compound, chemistry, High power lasers, Waste management, law, Carbon dioxide, Gas composition, Laser, Carbon monoxide, law.invention, Power (physics)
Abstract

Power stabilization of high power industrial CO laser usinggas exchaflgHirotaka Kanazawa, Naohito Yamaguchi, Takuro Nakajima, Yasunori Hamano,Ryoichi Satani and Tatsuji TairaMechatronics Products Development Department,Ishikawajima-Harima Heavy Industries Co. Ltd.,1 Shin-nakahara-cho, Isogo, Yokohama 235, JapanABSTRACTA long time stable operation of a high-power discharge-excited CO laser was attainedby controlling a laser gas composition.

Published
1991

11. Relationships between gill Na+,K+-ATPase activity and endocrine and local insulin-like growth factor-I levels during smoltification of masu salmon (Oncorhynchus masou)

Author

Shimomura, Takahiro, Nakajima, Takuro, Horikoshi, Moeri, Iijima, Anai, Urabe, Hirokazu, Mizuno, Shinya, Hiramatsu, Naoshi, Hara, Akihiko, and Shimizu, Munetaka

Subjects
*ADENOSINE triphosphatase, *ENDOCRINE system, *SOMATOMEDIN, *MESSENGER RNA, *SMOLTING, *ONCORHYNCHUS masou, *FISH anatomy
Abstract

Abstract: We established profiles of insulin-like growth factor (IGF)-I mRNA in the liver, gill and white muscle and circulating IGF-I during smoltification of hatchery-reared masu salmon, and compared with that of gill Na+,K+-ATPase (NKA) activity. Gill NKA activity peaked in May and dropped in June. Liver igf1 mRNA was high in March and decreased to low levels thereafter. Gill igf1 increased from March, maintained its high levels during April and May and decreased in June. Muscle igf1 mRNA levels were relatively high during January and April when water temperature was low. Serum IGF-I continuously increased from March through June. Serum IGF-I during March and May showed a positive correlation with NKA activity, although both were also related to fish size. These parameters were standardized with fork length and re-analyzed. As a result, serum IGF-I and gill igf1 were correlated with NKA activity. On the other hand, samples from desmoltification period (June) that had high serum IGF-I levels and low NKA activity disrupted the relationship. Expression of two IGF-I receptor (igf1r) subtypes in the gill decreased in June, which could account for the disruption by preventing circulating IGF-I from acting on the gill and retaining it in the blood. The present study suggests that the increase in gill NKA activity in the course of smoltification of masu salmon was supported by both endocrine and local IGF-I, and the decrease during desmoltification in freshwater was due at least in part to the down-regulation of gill IGF-I receptors. [Copyright &y& Elsevier]

Published
2012
Full Text
View/download PDF

14. Lack of hormonal stimulation prevents the landlocked Biwa salmon (Oncorhynchus masou subspecies) from adapting to seawater.

Author

Nakajima T, Shimura H, Yamazaki M, Fujioka Y, Ura K, Hara A, and Shimizu M

Subjects
Animal Migration, Animals, Fish Proteins metabolism, Gene Expression Regulation, Gills enzymology, Growth Hormone blood, Hydrocortisone blood, Oncorhynchus blood, Oncorhynchus genetics, RNA, Messenger metabolism, Receptors, Glucocorticoid drug effects, Receptors, Glucocorticoid genetics, Receptors, Glucocorticoid metabolism, Receptors, Somatotropin drug effects, Receptors, Somatotropin genetics, Receptors, Somatotropin metabolism, Salinity, Seasons, Sodium-Potassium-Exchanging ATPase metabolism, Species Specificity, Time Factors, Fresh Water, Growth Hormone pharmacology, Hydrocortisone pharmacology, Oncorhynchus metabolism, Salt Tolerance drug effects, Seawater
Abstract

Landlocking of salmon relaxes selective pressures on hypoosmoregulatory ability (seawater adaptability) and may lead to the abandonment of its physiological system. However, little is known about the mechanism and consequence of the process. Biwa salmon is a strain/subspecies of Oncorhynchus masou that has been landlocked in Lake Biwa for an exceptionally long period (about 500,000 years) and has low ability to adapt to seawater. We compared activity of gill Na(+),K(+)-ATPase (NKA) of Biwa salmon with those of anadromous strains of the same species (masu and amago salmon) during downstream migration periods and after exogenous hormone treatment. Gill NKA activity in anadromous strains increased during their migration periods, while that in Biwa salmon remained low. However, treatments of Biwa salmon with growth hormone (GH) and cortisol increased gill NKA activity. Cortisol treatment also improved the whole body seawater adaptability of Biwa salmon. Receptors for GH and cortisol responded to hormonal treatments, whereas their mRNA levels during downstream migration period were essentially unchanged in Biwa salmon. Circulating levels of cortisol in masu salmon showed a peak during downstream migration period, while no such increase was seen in Biwa salmon. The present results indicate that Biwa salmon can improve its seawater adaptability by exogenous hormonal treatment, and hormone receptors are capable of responding to the signals. However, secretion of the endogenous hormone (cortisol) was not activated during the downstream migration period, which explains, at least in part, their low ability to adapt to seawater., (Copyright © 2014 the American Physiological Society.)

Published
2014
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results