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Search Results: 1 - 10 of 323 matches for " Tomoki Michida "
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Gastric ESD under Heparin Replacement at High-Risk Patients of Thromboembolism Is Technically Feasible but Has a High Risk of Delayed Bleeding: Osaka University ESD Study Group
Toshiyuki Yoshio,Tsutomu Nishida,Naoki Kawai,Kiyonori Yuguchi,Takuya Yamada,Takamasa Yabuta,Masato Komori,Shinjiro Yamaguchi,Shinji Kitamura,Hideki Iijima,Shusaku Tsutsui,Tomoki Michida,Eiji Mita,Masahiko Tsujii,Tetsuo Takehara
Gastroenterology Research and Practice , 2013, DOI: 10.1155/2013/365830
Abstract: Objectives. Heparin replacement (HR) is often performed in patients with a high risk of thrombosis undergoing endoscopic procedures. However, information about the influence of HR is scarce. The aim of this study is to assess the clinical impact of HR for gastric endoscopic submucosal dissection (ESD). Methods. This is a retrospective study comprising approximately 1310 consecutive gastric neoplasms in 1250 patients, who underwent ESD in 5 institutes. We assessed the clinical findings and outcomes of ESD under HR, compared to ESD without HR as control. Results. A total of 24 EGC lesions in 24 patients were treated by ESD under HR. In the HR group, the complete en-bloc resection rate was 100%. The delayed bleeding rate was, however, higher in the HR group than in the controls (38% versus 4.6%). The timing of bleeding in the HR group was significantly later than in controls. In the control group, 209 patients discontinued antithrombotic therapy during perioperative period, and their delayed bleeding rate was not different from those without antithrombotic therapy (5.7% versus. 4.4%). A thromboembolic event was encountered in 1 patient under HR after delayed bleeding. Conclusion. ESD under HR is technically feasible but has a high risk of delayed bleeding. 1. Introduction Endoscopic resection of early gastric cancer (EGC) started as endoscopic mucosal resection (EMR) [1] and has dramatically developed and been applied in many patients, owing to the establishment of criteria for node-negative tumors [2] and the advancements of endoscopic submucosal dissection (ESD) [3–6]. We recently reported, in a multicenter study, that ESD is a feasible method for treating EGC [7] and that long-term outcome of gastric ESD is satisfactory [8]. We also showed that almost all recurrent lesions, synchronous or metachronous, were treatable by endoscopic resection by scheduled endoscopic surveillance [8]. ESD has become a more acceptable option for EGC than gastrectomy in elderly patients, who often have several comorbidities [9] and accompanying medication such as antithrombogenic agents for the primary and secondary prevention of cerebrovascular and cardiovascular diseases. Some patients with comorbidities such as valvular heart disease, atrial fibrillation with history of cerebrovascular accident have a high risk of developing thrombotic disease. Discontinuation of antithrombotic agents in these patients may cause life-threatening cerebrovascular and cardiovascular events. Such patients are often treated under heparin replacement (HR) of antithrombotic drugs, as a bridge
Optimal Location of Facilities on a Network in Which Each Facility is Operating as an M/G/1 Queue  [PDF]
Tomoki Hamaguchi, Koichi Nakade
Journal of Service Science and Management (JSSM) , 2010, DOI: 10.4236/jssm.2010.33036
Abstract: In this paper, we consider a facility location problem in which customers and facilities are located on a network, and each facility is assumed to be operating as an M/G/1 queuing system. In many situations, the customer chooses the nearest facility to receive service. Customer satisfaction is evaluated by the probability of waiting less than or equal to a certain time for a customer that is chosen randomly from all customers who arrives to the system. By using a computational method for obtaining the probability on the waiting time, we propose the computational heuristic methods for finding the optimal location. Numerical results show the following. First, it is shown that the tabu search with an initial solution generated by random numbers gives the near-optimal solution with the highest probability among several algorithms. Second, the computation time and solution quality are not sensitive to the sharp of the service time distribution. Third, the computation time and solution quality are highly sensitive to the system utilization. Fourth, the complete enumeration might be the best solution methodology for highly utilized systems.
Note on Dilogarithm Identities from Nilpotent Double Affine Hecke Algebras
Tomoki Nakanishi
Symmetry, Integrability and Geometry : Methods and Applications , 2012,
Abstract: Recently Cherednik and Feigin [arXiv:1209.1978] obtained several Rogers-Ramanujan type identities via the nilpotent double affine Hecke algebras (Nil-DAHA). These identities further led to a series of dilogarithm identities, some of which are known, while some are left conjectural. We confirm and explain all of them by showing the connection with Y-systems associated with (untwisted and twisted) quantum affine Kac-Moody algebras.
Dirac-field model of inflation in Einstein-Cartan theory
Tomoki Watanabe
Physics , 2009,
Abstract: We present a cosmological model in which a single Dirac field with a flat potential can give rise to inflation within the framework of the Einstein-Cartan theory. It is shown that our Dirac-field model leads to a nearly scale-invariant spectrum of density fluctuations owing to the spin-interaction which naturally arises from the field equations of the Einstein-Cartan theory.
Fusion, mass, and representation theory of the Yangian algebra
Tomoki Nakanishi
Physics , 1994, DOI: 10.1016/0550-3213(94)00458-Q
Abstract: Based on the formulation of Drinfel'd, Chari, and Pressley, a technique to analyze the structure of tensor products of the Yangian algebra representations is presented. We then apply the results to the $S$-matrix theory of the $G\otimes G$-invariant nonlinear $\sigma$-model ($G$-principal chiral model) by Ogievetsky, Reshetikhin, and Wiegmann. We show how the physical data such as mass formula, fusion angle, and the spins of integrals of motion can be extracted from the Yangian highest weight representations.
Appearance of a quark matter phase in hybrid stars
Tomoki Endo
Physics , 2013, DOI: 10.1088/1742-6596/509/1/012075
Abstract: The appearance of quark matter in the core of hybrid stars is a fundamental issue in such compact stars. The central density of these stars is sufficiently high such that nuclear matter undergoes a further change into other exotic phases that consist of hyperons and quarks. However, the equation of state (EOS) for the high-density matter is still not clear and several recent observations have indicated the limitations of the EOSs; theoretical studies should try to elucidate the EOSs. It is believed that the inner regions of the stars should consist of a mixed hadron-quark phase. We study the mixed hadron-quark phase, taking into account finite-size effects, and find that that the mixed phase should be restricted to a narrower region. Therefore, a quark matter phase should appear in the central region.
Hadronic matter phases and their application to rapidly rotating neutron stars
Tomoki Endo
Physics , 2015,
Abstract: Neutron stars are commonly considered as astronomical objects having highdensity interiors and an inner core region in which various hadronic matter phases are expected. Several studies show that the inner structures affect macroscopic phenomena of the star. However, we know that the inner structures of the star strongly depend on the equation of state (EOS). The EOS of high-density matter is still not clear and several recent observations indicate restrictions to EOSs. Theoretical studies should elucidate EOSs at high density and/or high temperature. For instance, many theoretical studies have attempted to account for the rotation effect of rapidly rotating neutron stars (i.e., pulsars). Accordingly, we also apply our EOSs to rapidly rotating stars. Furthermore, neutron stars generate a strong magnetic field. Several recent studies indicate that this magnetic field exerts restrictions on the EOS. In this paper, we focus on the investigation of the inner structures and the application of our EOSs to rotating stars. We find that one of our EOSs is consistent with observations, and another is inconsistent. We also find an important relation between the radius and rotation.
Region of hadron-quark mixed phase in hybrid stars
Tomoki Endo
Physics , 2011, DOI: 10.1103/PhysRevC.83.068801
Abstract: Hadron--quark mixed phase is expected in a wide region of the inner structure of hybrid stars. However, we show that the hadron--quark mixed phase should be restricted to a narrower region to because of the charge screening effect. The narrow region of the mixed phase seems to explain physical phenomena of neutron stars such as the strong magnetic field and glitch phenomena, and it would give a new cooling curve for the neutron star.
Investigation of the rotation effects on high--density matter in hybrid stars
Tomoki Endo
Physics , 2014,
Abstract: The equation of state (EOS) of high-density matter is still not clear and several recent observations indicate restrictions to EOSs. Theoretical studies should thus elucidate EOSs at high density and/or high temperature. Many theoretical studies have attempted to account for the effect of rotation of rapidly rotating neutron stars (pulsars), which are commonly observed astronomical objects having high-density interiors. Furthermore, neutron stars generate a strong magnetic field. Several recent studies indicate that this magnetic field exerts some restrictions on the EOS. Theoretical studies should thus incorporate these effects. In this paper, we focus on the effect of rotation. We find that one of our EOSs is consistent with these observations, and another is inconsistent. We also find an important relation between radius and rotation.
Tessellation and Lyubich-Minsky laminations associated with quadratic maps II: Topological structures of 3-laminations
Tomoki Kawahira
Mathematics , 2006,
Abstract: According to an analogy to quasi-Fuchsian groups, we investigate topological and combinatorial structures of Lyubich and Minsky's affine and hyperbolic 3-laminations associated with the hyperbolic and parabolic quadratic maps. We begin by showing that hyperbolic rational maps in the same hyperbolic component have quasi-isometrically the same 3-laminations. This gives a good reason to regard the main cardioid of the Mandelbrot set as an analogue of the Bers slices in the quasi-Fuchsian space. Then we describe the topological and combinatorial changes of laminations associated with hyperbolic-to-parabolic degenerations (and parabolic-to-hyperbolic bifurcations) of quadratic maps. For example, the differences between the structures of the quotient 3-laminations of Douady's rabbit, the Cauliflower, and $z \mapsto z^2$ are described. The descriptions employ a new method of tessellation inside the filled Julia set introduced in Part I that works like external rays outside the Julia set.
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