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Choi, June-Sang,Hasanov, Anvar,Turaev, Mamasali The Honam Mathematical Society 2011 호남수학학술지 Vol.33 No.2
In investigation of boundary-value problems for certain partial differential equations arising in applied mathematics, we often need to study the solution of system of partial differential equations satisfied by hypergeometric functions and find explicit linearly independent solutions for the system. Here we choose the Exton functions $X_1$ and $X_2$ among his twenty functions to show how to find the linearly independent solutions of partial differential equations satisfied by these functions $X_1$ and $X_2$.
DECOMPOSITION FORMULAS AND INTEGRAL REPRESENTATIONS FOR THE KAMP¶E DE F¶ERIET FUNCTION F0:3;3
June sang Choi,Mamasali Turaev 충청수학회 2010 충청수학회지 Vol.23 No.4
By developing and using certain operators like those initiated by Burchnall-Chaundy, the authors aim at investigating several decomposition formulas associated with the Kamp¶e de F¶eriet function F0:3;3 2:0;0 [x; y]. For this purpose, many operator identities in- volving inverse pairs of symbolic operators are constructed. By employing their decomposition formulas, they also present a new group of integral representations of Eulerian type for the Kamp¶e de F¶eriet function F0:3;3 2:0;0 [x; y], some of which include several hyperge- ometric functions such as 2F1, 3F2, an Appell function F3, and the Kamp¶e de F¶eriet functions F0:3;3 2:0;0 and F0:2;31:0;1 .
SEVERAL RESULTS ASSOCIATED WITH THE RIEMANN ZETA FUNCTION
June sang Choi 충청수학회 2009 충청수학회지 Vol.22 No.3
In 1859, Bernhard Riemann, in his epoch-making mem-oir, extended the Euler zeta function ³(s) (s > 1; s 2 R) to the Riemann zeta function ³(s) (<(s) > 1; s 2 C) to investigate the pattern of the primes. Sine the time of Euler and then Riemann, the Riemann zeta function ³(s) has involved and appeared in a variety of mathematical research subjects as well as the function itself has been being broadly and deeply researched. Among those things, we choose to make a further investigation of the following subjects: Evaluation of ³(2k) (k 2 N); Approximate functional equations for ³(s); Series involving the Riemann zeta function.
CERTAIN INTEGRAL REPRESENTATIONS OF EULER TYPE FOR THE EXTON FUNCTION X<sub>8</sub>
Choi, June-Sang,Hasanov, Anvar,Turaev, Mamasali Korean Mathematical Society 2012 대한수학회논문집 Vol.27 No.2
Exton introduced 20 distinct triple hypergeometric functions whose names are $X_i$ (i = 1, ${\ldots}$, 20) to investigate their twenty Laplace integral representations whose kernels include the confluent hypergeometric functions $_0F_1$, $_1F_1$, a Humbert function ${\Psi}_1$, and a Humbert function ${\Phi}_2$. The object of this paper is to present 18 new integral representations of Euler type for the Exton hypergeometric function $X_8$, whose kernels include the Exton functions ($X_2$, $X_8$) itself, the Horn's function $H_4$, the Gauss hypergeometric function $F$, and Lauricella hypergeometric function $F_C$. We also provide a system of partial differential equations satisfied by $X_8$.
Clinical characteristics of papillary thyroid carcinoma arising from the pyramidal lobe
Sang Gab Yoon,Jin Wook Yi,Chan-Yong Seong,Jong-Kyu Kim,Su-Jin Kim,Young Jun Chai,June Young Choi,Kyu Eun Lee 대한외과학회 2017 Annals of Surgical Treatment and Research(ASRT) Vol.92 No.3
Purpose: Papillary thyroid carcinoma (PTC) arising from the pyramidal lobe is rare; therefore, clinicopathologic evaluation is lacking. In addition, the rate of occult malignancy in the pyramidal lobe after thyroid surgery is unclear. This study is to evaluate the clinical characteristics of PTCs that involve the pyramidal lobe. Methods: The study enrolled 1,107 patients who underwent thyroid surgery for PTC at Seoul National University Hospital from 2006 to 2015. Pyramidal lobe status in pathologic reports was clear in all cases. “Pyramidal lobe-dominant PTC” was defined as single pyramidal lobe cancer or multifocal cancer with larger pyramidal lobe tumor. “Incidental pyramidal lobe PTC” was defined as occult cancer identified after thyroidectomy or as multifocal cancer with smaller pyramidal lobe tumor. Results: Ten patients were included in the pyramidal lobe-dominant PTC group. The mean age was 58 ± 12.5 years, and the mean tumor size was 0.7 ± 0.7 cm. Cervical lymph node metastasis was found in 5 patients (50%). Three patients had microscopic lymphatic invasion, and 7 had advanced American Joint Comitee on Cancer (AJCC) stage disease (5 with stage III and 2 with stage IV). Compared with conventional PTC (n = 1,058), pyramidal lobe-dominant PTC was significantly associated with lymphatic invasion (P = 0.031) and advanced AJCC stage (P = 0.022). The prevalence of incidental pyramidal lobe PTC was 3.56%. Conclusion: Pyramidal lobe PTC is relatively small in size; however, the rate of extrathyroidal extension and lymph node metastasis is high. Preoperative evaluation of nodal status is important, and the extent of surgery should be determined in accordance with the preoperative diagnosis.
Open Channel Block of Kv3.1 Currents by Fluoxetine
Sung, Min Ji,Ahn, Hye Sook,Hahn, Sang June,Choi, Bok Hee The Japanese Pharmacological Society 2008 Journal of pharmacological sciences Vol.106 No.1
<P>The action of fluoxetine, a serotonin reuptake inhibitor, on the cloned neuronal rat Kv3.1 channels stably expressed in Chinese hamster ovary cells was investigated using the whole-cell patch-clamp technique. Fluoxetine reduced Kv3.1 whole-cell currents in a reversible, concentration-dependent manner, with an IC<SUB>50</SUB> value and a Hill coefficient of 13.4 μM and 1.4, respectively. Fluoxetine accelerated the decay rate of inactivation of Kv3.1 currents without modifying the kinetics of current activation. The inhibition increased steeply between 0 and +30 mV, which corresponded with the voltage range for channel opening. In the voltage range positive to +30 mV, inhibition displayed a weak voltage dependence, consistent with an electrical distance δ of 0.38. The binding (k<SUB>+1</SUB>) and dissociation (k<SUB>−</SUB><SUB>1</SUB>) rate constants for fluoxetine-induced block of Kv3.1 were 5.7 μM<SUP>−</SUP><SUP>1</SUP>s<SUP>−</SUP><SUP>1</SUP> and 53.5 s<SUP>−</SUP><SUP>1</SUP>, respectively. The theoretical K<SUB>D</SUB> value derived by k<SUB>−</SUB><SUB>1</SUB>/k<SUB>+1</SUB> yielded 9.3 μM. Fluoxetine did not affect the ion selectivity of Kv3.1. Fluoxetine slowed the deactivation time course, resulting in a tail crossover phenomenon when the tail currents, recorded in the presence and absence of fluoxetine, were superimposed. Inhibition of Kv3.1 by fluoxetine was use-dependent. The present results suggest that fluoxetine acts on Kv3.1 currents as an open-channel blocker.</P>
Choi, Hongyoon,Cheon, Gi Jeong,Kim, Han-Joon,Choi, Seung Hong,Lee, Jae Sung,Kim, Yong-il,Kang, Keon Wook,Chung, June-Key,Kim, E. Edmund,Lee, Dong Soo Society of Nuclear Medicine 2014 The Journal of nuclear medicine Vol.55 No.10
<P>Attenuation correction (AC) with an ultrashort echo time (UTE) sequence has recently been used in combination with segmentation for cortical bone identification for brain PET/MR studies. The purpose of this study was to evaluate the quantification of <SUP>18</SUP>F-fluoropropyl-carbomethoxyiodophenylnortropane (<SUP>18</SUP>F-FP-CIT) binding in brain PET/MR, particularly focusing on effects of UTE-based AC including bone segmentation. <B>Methods:</B> Sixteen patients with initially suspected parkinsonism were prospectively enrolled. An emission scan was acquired 110 min after <SUP>18</SUP>F-FP-CIT injection on a dedicated PET/MR scanner, immediately followed by another emission scan using a PET/CT scanner 120 min after the injection. A UTE-based attenuation map was used to classify the voxels into 3 tissues: bone, soft tissue, and air. All PET images were spatially normalized, and a specific-to-nonspecific dopamine transporter (DAT) binding ratio (BR) was calculated using statistical probabilistic anatomic mapping. The level of agreement was assessed with intraclass correlation coefficients (ICCs). Voxelwise comparison between PET images acquired from PET/MR and PET/CT was performed. We compared non–attenuation-corrected images to analyze UTE-based AC effects on DAT quantification. <B>Results:</B> BR in the putamen obtained from PET/MR and PET/CT showed low interequipment variability, whereas BR in the caudate nucleus showed significant variability (ICC = 0.967 and 0.682 for putamen and caudate nucleus, respectively). BR in the caudate nucleus was significantly underestimated by PET/MR, compared with PET/CT (mean difference of BR = 0.66, <I>P</I> < 0.0001). Voxelwise analysis revealed that PET/MR showed significantly low BR in the periventricular regions, which was caused by a misclassification of the ventricle as air on the attenuation map. We also compared non-AC images, revealing low interequipment variability even in the caudate nucleus (ICC = 0.937 and 0.832 for putamen and caudate nucleus, respectively). <B>Conclusion:</B> Our data demonstrate spatial bias of the DAT BR on <SUP>18</SUP>F-FP-CIT PET/MR. Voxelwise analysis and comparison to non-AC images identified the misclassification of ventricle as air to be the cause of bias. To obtain reliable quantification for brain PET/MR studies including <SUP>18</SUP>F-FP-CIT PET, alternative and more reliable segmentation strategies are required.</P>
Choi, June-Sang,Hasanov, Anvar,Turaev, Mamasali Department of Mathematics 2012 Kyungpook mathematical journal Vol.52 No.2
We aim at presenting certain unexpected functional relations among various hypergeometric functions of one or several variables (for example, see the identities in Corollary 5) by making use of Carlson's method employed in his work (Some extensions of Lardner's relations between $_0F_3$ and Bessel functions, SIAM J. Math. Anal. 1(2)(1970), 232-242).