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Search Results: 1 - 10 of 129 matches for " Tamotsu Kamishima "
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Multi-Detector-Row CT Diagnosis of Adrenal Incidentaloma in Patients with Hepatocellular Carcinoma  [PDF]
Taisuke Harada, Tamotsu Kamishima, Satoshi Terae, Yuya Onodera, Hiroki Shirato
Advances in Computed Tomography (ACT) , 2013, DOI: 10.4236/act.2013.21007
Abstract: We investigate the diagnostic reliability of differentiating between lipid-poor adrenal adenomas and metastatic adrenal tumors originating from hepatocellular carcinoma (HCC) using a routine dynamic CT protocol for liver imaging. Eighteen metastatic adrenal tumors originating from HCC and 13 lipid-poor adrenal adenomas were identified. Dynamic CT data were analyzed for CT attenuation of adrenal lesions before and after contrast administration. When a cutoff of 36 HU was set for adrenal lesions at pre-contrast attenuation, the sensitivity and specificity for the diagnosis of metastatic lesions were 94.4%and 92.3%, respectively. Attenuation criteria on pre-contrast CT may help optimize the differentiation between these lesions.
Synovial chondromatosis originating from the synovium of the anterior cruciate ligament: a case report
Tokifumi Majima, Tamotsu Kamishima, Kouichi Susuda
Sports Medicine, Arthroscopy, Rehabilitation, Therapy & Technology , 2009, DOI: 10.1186/1758-2555-1-6
Abstract: Synovial chondromatosis is a relatively rare disease and large joints such as knee-joints, hip-joints, and elbow-joints are more commonly affected [1,2]. Among knee-joints, cases originating from the cruciate ligament of the knee are very rare and only 2 cases have been reported on presentation from the posterior cruciate ligament [3,4]. We experienced a case of synovial chondromatosis originating from the synovium of the anterior cruciate ligament (ACL) of the knee and report the results.A healthy 36-year-old male with no existing history or family history complained of pain in the left knee when in motion since 2000. Following diagnosis of a damaged meniscus in 2003, he received an intra-articular injection of hyaluronic acid at another institution. The symptoms were improved temporarily, but pain in the left knee reoccurred in the winter of the same year and locking-like symptoms were also expressed. We initially examined this patient with major complaints of pain in the left knee and a restricted range of left-knee motion in 2004. At the time of the initial visit, squatting was difficult and pain in the left-knee appeared when walking and climbing up or down a staircase. Swelling was detected in the left-knee joint and there was a restriction with an extension of -20° and a flexion of 120° in the range of left-knee motion (hereinafter referred to as ROM). Forceful extension of the knee was elastically inhibited and pain was felt at this time, presenting similar symptoms to locking at the time of meniscus damage. The results of Lachman test, anterior drawer test, and varus/valgus stress test were all negative as was the result of McMurray's test.No signs were detected in radiographic findings at the initial visit and no calcifications were found within the joint (Figure 1). Magnetic resonance imaging (MRI) showed the ACL was swollen and iso-signals to high-signals at TIWI and high-signals at T2WI, indicating significant signal changes compared to the MRI of a nor
Association of Renal Volume with the Degree of Aortic Contrast Enhancement in Abdominal CT  [PDF]
Natalia S. Muto, Tamotsu Kamishima, Tsukasa Sasaki, Satoshi Terae, Khin Khin Tha, Hiroki Shirato, Kyongtae T. Bae
Advances in Computed Tomography (ACT) , 2013, DOI: 10.4236/act.2013.22011
Abstract: To assess the correlation of renal volume measured on CT with aortic contrast enhancement on the hepatic arterial phase of dynamic CT, 64 consecutive patients (34 men, 30 women) were retrospectively examined. Renal volumes were measured on CT. The aortic contrast enhancement was inversely correlated with renal medullary volume (r = -0.52, p < 0.0001), and renal cortical volume (r = -0.3, p = 0.02). Renal volume may have inverse correlation with aortic contrast enhancement on the hepatic arterial phase of dynamic CT. This might call for adjustment of contrast material dose based in part on renal volume in the future.
On Quaternionic 3 CR-Structure and Pseudo-Riemannian Metric  [PDF]
Yoshinobu Kamishima
Applied Mathematics (AM) , 2018, DOI: 10.4236/am.2018.92008
Abstract:
A CR-structure on a 2n +1-manifold gives a conformal class of Lorentz metrics on the Fefferman S1-bundle. This analogy is carried out to the quarternionic conformal 3-CR structure (a generalization of quaternionic CR- structure) on a 4n + 3 -manifold M. This structure produces a conformal class [g] of a pseudo-Riemannian metric g of type (4n + 3,3) on M × S3. Let (PSp(n +1,1), S4n+3) be the geometric model obtained from the projective boundary of the complete simply connected quaternionic hyperbolic manifold. We shall prove that M is locally modeled on (PSp(n +1,1), S4n+3) if and only if (M × S3 ,[g]) is conformally flat (i.e. the Weyl conformal curvature tensor vanishes).
Late Quaternary Geomorphology of the Tonami Plain and Activity of the Tonami-Heiya Fault Zone, Toyama Prefecture, Central Japan  [PDF]
Toshio Kamishima, Akira Takeuchi
International Journal of Geosciences (IJG) , 2016, DOI: 10.4236/ijg.2016.77073
Abstract: The Holocene alluvial fans and flood plains formed by the Sho and Oyabe Rivers spread out in the Tonami plain from the central through the northern parts in the Toyama Prefecture, central Japan. Along the foot of the surrounding mountains and hills, higher, middle and lower terraces of late Pleistocene-Holocene in age are distributed. These terraces have been displaced, by the reverse dip-slip activities of Tonami-heiya fault zone in a sense of upheaval in the mountains side, even during the Holocene time. We examined stratigraphic cross section utilizing borehole data and geomorphologically analyzed 5 m-DEM data in order to elucidate the fault trace of the Isurugi fault which Tonami-heiya fault zone. As the results, the northern segment of Isurugi fault seems to run along the northeastern foot of Hodatsu Hills and extends underground through the lower-most Oyabe River into the Toyama Bay. Consequently, its total length reaches about 30 km. In the southern segment, a continuous fault scarplet was recognized to cut across the lower dissected fans. The slip-rate of Isurugi fault is estimated to be 0.31 - 0.64 m/kyr. In the Hokuriku region, reverse faulting and related folding with strike in a NE-SW direction have occurred during the late Quaternary. The hinge line of block movement due to the activities of the Tonami-heiya fault zone is revealed to have shifted from the mountain side into the plain side within the Holocene time. In conclusion, the Quaternary folding and faulting associated with the crustal warping at a wavelength of about 20 km is currently in progress, causing both the subsidence of Tonami plain and the upheaval of surrounding mountains and hills.
Nonexistence of cusp cross-section of one-cusped complete complex hyperbolic manifolds II
Yoshinobu Kamishima
Mathematics , 2006,
Abstract: D. D. Long and A. W. Reid have shown that some compact flat 3-manifold cannot be diffeomorphic to a cusp cross-section of any complete finite volume 1-cusped real hyperbolic 4-manifold. This note concerns the complex hyperbolic case. We give a negative answer that there exists a 3-dimensional closed Heisenberg infranilmanifold which cannot be diffeomorphic to a cusp cross-section of any complete finite volume 1-cusped complex hyperbolic 2-manifold.
Lorentzian similarity manifold
Yoshinobu Kamishima
Mathematics , 2011,
Abstract: If an $m+2$-manifold $M$ is locally modeled on $\RR^{m+2}$ with coordinate changes lying in the subgroup $G=\RR^{m+2}\rtimes ({\rO}(m+1,1)\times \RR^+)$ of the affine group ${\rA}(m+2)$, then $M$ is said to be a \emph{Lorentzian similarity manifold}. A Lorentzian similarity manifold is also a conformally flat Lorentzian manifold because $G$ is isomorphic to the stabilizer of the Lorentz group ${\rPO}(m+2,2)$ which is the full Lorentzian group of the Lorentz model $S^{2n+1,1}$. It contains a class of Lorentzian flat space forms. We shall discuss the properties of compact Lorentzian similarity manifolds using developing maps and holonomy representations.
Conformally flat Lorentz manifolds and Fefferman Lorentz metrics
Yoshinobu Kamishima
Mathematics , 2009,
Abstract: We study conformal Fefferman-Lorentz manifolds introduced by Fefferman. To do so, we introduce Fefferman-Lorentz structure on (2n+2)-dimensional manifolds. By using causal conformal vector fields preserving that structure, we shall establish two theorems on compact Fefferman-Lorentz manifolds: One is the coincidence of vanishing curvature between Weyl conformal curvature tensor of Fefferman metrics on a Lorentz manifold $S^1\times N$ and Chern-Moser curvature tensor on a strictly pseudoconvex CR-manifold $N$. Another is the analogue of the conformal rigidity theorem of Obata and Lelong to the compact Fefferman-Lorentz manifolds admitting noncompact closed causal conformal Fefferman-Lorentz transformations.
Profit-Sharing and the Endogenous Order of Moves in Oligopoly  [PDF]
Hiroyuki Takami, Tamotsu Nakamura
Theoretical Economics Letters (TEL) , 2012, DOI: 10.4236/tel.2012.22023
Abstract: Whether firms move sequentially or simultaneously is one of the most important questions in the oligopoly theory. Forms of firms and/or their remuneration systems influence the decisions. This paper analyzes the effect of profit-sharing on the endogenous order of moves in a wage-setting stage of a unionized duopoly where one adopts profit-sharing while the other does not. It is shown that the two firms do not move simultaneously. In addition, if a fraction of profits going to the union is large, the Stackelberg equilibrium with the profit sharing firm moving first emerges endogenously.
Pseudo-conformal quaternionic CR structure on (4n+3)-dimensional manifolds
Dmitri Alekseevsky,Yoshinobu Kamishima
Mathematics , 2005,
Abstract: The purpose of this paper is to introduce a geometric structure called pseudo-conformal quaternionic CR structure on a (4n+3)-dimensional mamnifold and then exhibit a quaternionic analogue of Chern-Moser's CR structure and uniformization.
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