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Gsa 유전자의 돌연변이가 쥐의 소마토스타틴 수용체 유전자의 발현에 미치는 효과
양인명,박승준,장호강,이군자,오승준,김성운,김진우,김영설,최영길 대한내분비학회 1999 Endocrinology and metabolism Vol.14 No.4
Background: The growth hormone (GH)-secreting pituitary adenoma with mutation of Gsa gene (gsp oncogene) is known to show a higher response to somatostatin. The mechanism for the higher response is unclear. We previously demonstrated that transcription of the rat somatostatin receptor (SSTR) gene was increased by cAMP. Therefore, we investigated whether the mutation of Gsa gene can increase SSTR gene expression. Methods: The mutant Gsa expressing plasmid of which arginine of codon 201was replaced with histidine was transfected transiently and permanently into GH3 cells. cAMP and rat GH were measured by radioimmunoassay. mRNA expression of the rat SSTR2 was determined by a semiquantitative RT-PCR. Results: The intracellular cAMP production was increased by 1.8 folds in the transiently transfected cells and by 1.5 folds in permanently transfected cells compared to those in the cells transfected with the vehicle plasmid, plasmid expressing the wild type or the plasmid expressing the silent mutant of codon 226. The transcriptional activation by cAMP response element of somatostatin.gene was also increased by 2 folds 24 hours after transient transfection and by 3.5 folds in the permanently transfected cells. The transcriptional activation was not enhanced by forskolin in the transiently transfected cells, whereas it was more remarkably inhibited by somatostatin compared to that in the other transfected cells. The expression of SSTR2 was increased by 1.8 folds 24 hours after transfection in the transiently transfected cells and by 3 folds in the permanently transfected cells, and it was not enhanced by forskolin and isobutylmethylxanthine. The secretion of GH from the transiently transfected cells was not significantly higher than that from the wild type-expressing cells, but it was higher in the permanently transfected cells. The suppression of GH by somatostatin was more prominent in the permanently transfected cells compared to the other transfected cells. Conclusion: This study suggests that a higher expression of SSTR induced by the mutant Gsa may be a mechanism by which gsp-positive adenomas showed a higher response to somatostatin (J Kor Soc Endocrinol 14:657-666, 1999).
Progress in the Study of RF Heating and Stabilization on HANBIT Mirror Device
Kwon, M.,Bak, J. G.,Choh, K.,Choi, J. H.,Choi, J. W.,England, A. C.,Hong, J. S.,Jhang, H. G.,Kim, J. Y.,Kim, S. S.,Ko, W. H.,Lee, D. K.,Lee, J. H.,Lee, S. G.,Lee, H. G.,Lho, T.,Na, H. K.,Park, B. H.,P Informa UK (TaylorFrancis) 2005 Fusion science and technology Vol.47 No.1
Observation of the intrinsic rotation in KSTAR Ohmic L-mode plasmas
Na, D.H.,Na, Yong-Su,Lee, S.G.,Angioni, C.,Yang, S.M.,Kim, H.-S.,Hahm, T.S.,Ko, W.H.,Jhang, H.,Lee, W.J. International Atomic Energy Agency 2016 Nuclear fusion Vol.56 No.3
<P>Two types of experiments were carried out to conduct an intrinsic rotation study in KSTAR. The first was a density ramp-up experiment without neutral beam injection, and the second was an experiment with beam blip technique. In these experiments, some characteristics of the intrinsic rotation were observed in the KSTAR Ohmic L-mode plasmas including: (i) a non-monotonic dependence of the core intrinsic rotation, called U-curve behaviour, with respect to the electron density and the collisionality related to the gradient of the toroidal rotation profile; and (ii) the behaviour of the anchor point in the intrinsic rotation profile for which the region exhibits a roughly flat shape and stays at nearly the same value even if the gradient of the toroidal rotation changes significantly in the core region. The location of the anchor point seems to be related to the <I>q</I> profile, and the toroidal rotation at the anchor point changes with the plasma operation parameters. These observations in the KSTAR Ohmic L-mode plasmas seem to be related to the rotation reversal phenomenon. A transport analysis was performed for the beam blip experiments in order to evaluate the intrinsic torque so that the U-curve behaviour can be further understood. The first results of the transport analysis in the KSTAR Ohmic L-mode plasmas show a correlation of the momentum fluxes and the intrinsic torques with the electron density and the collisionality. The rough magnitude and profiles of the intrinsic torque was experimentally obtained, and their possible mechanism is briefly discussed.</P>
C. Kim,홍병식,G. Jhang,E. Joo,K. S. Lee,이경세,S. Lee,S. K. Lee,S. K. Park,H. H. Shim,S. S. Shin,K. S. Sim,H. K. Cha 한국물리학회 2012 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.60 No.5
Here, we report on the measurement of scintillation responses of scintillation fibers for precision dose verification in proton therapy. A detector equipped with two layers of 1-mm-thick scintillation fibers and 46-channel silicon photodiodes was constructed and tested with 45-MeV proton beams provided by the MC50 proton cyclotron at the Korea Institute of Radiological and Medical Science (KIRAMS). Scintillation responses of the detector for the protons were measured as a function of depth in an absorber made of PMMA (poly methyl methacrylate) and PET (polyester) films whose thicknesses varied from 0.148 to 2.0 g·cm.2. Quenching of the scintillation responses of the detector was evaluated by comparison of the data to the specific energy loss predicted by GEANT4-based simulations. The first-order parameter of the Birks model, kB, for scintillation fibers, as derived from the ratios of specific energy losses to scintillation responses, was (2.38 ± 0.17) × 10^(-2).
Frequency and field dependent conductivity of carbon nanotube networks
A.B.Kaiser,K.J.Challis,G.C.McIntosh,G.T.Kim,H.Y.Yu,J.G.Park,S.H.Jhang,Y.W.Park 한국물리학회 2002 Current Applied Physics Vol.2 No.2
The measured resistance of carbon nanotube networks is often dominated by defects, inter-tube and inter-rope contacts. Weshow that the peak reported in the frequency-dependent conductivity of single-wall carbon nanotube networks is consistent withpendence of the conductivity. Using Sheng’s model, we calculate the eld dependence of uctuation-assisted tunnelling conductionbetween metallic regions separated by an insulating barrier, obtaining nonlinearities consistent with our experimental data oncarbon nanotube networks.. 2002 Elsevier Science B.V. All rights reserved.
Progress of physics studies in the Hanbit mirror device
kwang-il You,A. C. England,B. H. Park,D. C. Seo,D. K. Lee,H. G. Jhang,H. K. Na,J. Chung,J. G. Bak,J. H. Lee,J. H. Yeom,J. S. Hong,K. K. Choh,M. K. Park,S. G. Lee,S. H. Seo,S. J. Yoo,S. S. Kim,S. W. Yo 한국물리학회 2006 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.49 No.III
The Hanbit is a complex mirror device that has a slot and a double half-turn antennas in the central cell to launch high power ion cyclotron resonance frequency range waves for plasma production, heating, and stabilization. However, there is no other device, such as a neutral beam injector, to heat the plasma ions. Hanbit also has three low-power supplies to launch electron cyclotron resonance frequency range waves for heating electrons. Under these circumstances, the main physics study in the Hanbit device has been devoted to RF-wave and plasma interaction studies, including MHD stabilization by using only the RF waves. In this paper, we briefly report the main results of the RF-heating research, MHD stability studies and discharge analysis during the past few years, as well as the future plans.
Stabilization of Interchange Modes in Mirror Plasmas by a Nonlinear rf-Plasma Wave Coupling Process
Jhang, Hogun,Lee, S. G.,Kim, S. S.,Park, B. H.,Bak, J. G. American Physical Society 2005 Physical review letters Vol.95 No.3
<P>Experimental and theoretical studies are made of the consequences of a nonlinear coupling process between pump rf waves and interchange modes in mirror plasmas. It is demonstrated that the interchange-stable operation window exists depending on the applied rf power and gamma=omega(0)/Omega(i), where omega(0) (Omega(i)) is the angular frequency of the applied rf wave (ion cyclotron frequency). Results are shown that the nonlinear wave coupling process gives rise to the operation window near the resonance (gamma approximately equal to 1), which is elucidated by theoretical analyses combined with full rf wave simulations.</P>