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Search Results: 1 - 10 of 354 matches for " Takumi "
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Fermented Brown Sugar Residue Prolongs the Caenorhabditis elegans Lifespan via DAF-16  [PDF]
Takumi Satoh, Kazuichi Sakamoto
Food and Nutrition Sciences (FNS) , 2017, DOI: 10.4236/fns.2017.89061
Abstract: Purification of biomass ethanol from the products of brown sugar yeast-fermentation produces a large amount of residue. This fermentation residue contains abundant brown sugar-derived nutrients and is mainly used as compost or livestock feed. However, the in vivo physiological effects of oral residue ingestion are not known. The purpose of this study was to elucidate the physiological action and molecular mechanism of fermented brown sugar residue in nematode stress tolerance, aging, and lifespan using Caenorhabditis elegans. Fermented brown sugar residue was divided into two layers, supernatant and precipitate, and each was given to nematodes. Analysis of motility and survival rate under thermal stress revealed reduced mobility and increased survival rate following treatment with fermented brown sugar residue. The survival rate of nematodes under 1% H2O2 was markedly increased by the residue and mitochondrial membrane depolarization was induced and mitochondrial radical oxygen species levels increased. Furthermore, aging dependent reduction of motility was suppressed, and the average life span of nematodes was extended by treatment with fermented brown sugar residue. Moreover, the effects of fermented brown sugar residue on stress tolerance, lifespan elongation, and decreased aging dependent momentum reduction were lost in the daf-16 mutant. Taken together, our results show that the various physiological actions of fermented brown sugar residue, including stress tolerance and lifespan extension, occur via DAF-16.
Theoretical Status of Pentaquarks
Doi, Takumi
High Energy Physics - Phenomenology , 2007, DOI: 10.1143/PTPS.168.45
Abstract: We review the current status of the theoretical pentaquark search from the direct QCD calculation. The works from the QCD sum rule and the lattice QCD in the literature are carefully examined. The importance of the framework which can distinguish the exotic pentaquark state (if any) from the NK scattering state is emphasized.
Pulmonary Vein Isolation with a Multielectrode Basket Catheter
Takumi Yamada
Indian Pacing and Electrophysiology Journal , 2007,
Abstract: Pulmonary vein (PV) isolation (PVI) techniques have evolved as a curative treatment of atrial fibrillation (AF) since PVI guided by circumferential mapping with a circular catheter was initially proposed. A multielectrode basket catheter (MBC) is also useful for PVI because of some advantages; (1) an MBC provides some information about the PV anatomy on the fluoroscopic image, (2) an MBC can utilize the non-fluoroscopic navigation system, (3) an MBC enables the direct three-dimensional mapping around the PV ostium and antrum, (4) the distal electrodes of the MBC can be used to monitor some activation changes within the PV in real time and thereby indicate the effects of ablation at the ostium and antrum as radiofrequency lesions are created. PVI with an MBC is an effective and safe procedure to cure AF by integrating the PV anatomy and electrophysiology in combination with a non-fluoroscopic three-dimensional navigation system for the ablation catheter.
Interplay between kaon condensation and hyperons in highly dense matter
Takumi Muto
Physics , 2007, DOI: 10.1103/PhysRevC.77.015810
Abstract: Possible coexistence and/or competition of kaon condensation with hyperons are investigated in hyperonic matter, where hyperons are mixed in the ground state of neutron-star matter. The formulation is based on the effective chiral Lagrangian for the kaon-baryon interaction and the nonrelativistic baryon-baryon interaction model. First, the onset condition of the s-wave kaon condensation realized from hyperonic matter is reexamined. It is shown that the usual assumption of the continuous phase transition is not always kept valid in the presence of the negatively charged hyperons. Second, the equation of state (EOS) of the kaon-condensed phase in hyperonic matter is discussed. In the case of the stronger kaon-baryon attractive interaction, it is shown that a local energy minimum with respect to the baryon number density appears as a result of considerable softening of the EOS due to both kaon condensation and hyperon-mixing and recovering of the stiffness of the EOS at very high densities. This result implies a possible existence of self-bound objects with kaon condensates on any scale from an atomic nucleus to a neutron star.
Kaon-condensed hypernuclei as highly dense self-bound objects
Takumi Muto
Physics , 2008, DOI: 10.1016/j.nuclphysa.2008.02.302
Abstract: The structure of $K^-$-condensed hypernuclei, which may be produced in the laboratory in strangeness-conserving processes, is investigated using an effective chiral Lagrangian for the kaon-baryon interaction, combined with a nonrelativistic baryon-baryon interaction model. It is shown that a large number of negative strangeness is needed for the formation of highly dense and deeply bound state with kaon condensates and that part of the strangeness should be carried by hyperons mixed in the nucleus. The properties of kaon-condensed hypernuclei such as the ground state energy and particle composition are discussed. Such a self-bound object has a long lifetime and may decay only through weak interaction processes. Comparison with other possible nuclear states is also made, such as kaon-condensed nuclei without mixing of hyperons and noncondensed multistrange hypernuclei. Implications of kaon-condensed hypernuclei for experiments are mentioned.
Kaonic modes in hyperonic matter and p-wave kaon condensation
Takumi Muto
Physics , 2001, DOI: 10.1016/S0375-9474(01)01226-X
Abstract: Kaon excitations (kaonic modes) are investigated in hyperonic matter, where hyperons ($\Lambda$, $\Sigma^-$, $\Xi^-$) are mixed in the ground state of neutron-star matter. $P$-wave kaon-baryon interactions as well as the s-wave interactions are taken into account within chiral effective Lagrangian, and the nonrelativistic effective baryon-baryon interactions are incorporated. When the hyperon $\Lambda$ is more abundant than the proton at high baryon density, a proton-particle-$\Lambda$-hole mode, which has the $K^+$ quantum number, appears in addition to other particle-hole modes with the $K^-$ quantum number. It is shown that the system becomes unstable with respect to a spontaneous creation of a pair of the particle-hole modes with $K^+$ and $K^-$ quantum numbers, stemming from the p-wave kaon-baryon interaction. The onset density of this p-wave kaon condensation may be lower than that of the s-wave $K^-$ condensation.
Meson Condensations in High-Density Matter
Takumi Muto
Physics , 2003, DOI: 10.1143/PTPS.153.174
Abstract: Recent studies on meson condensations (pions and kaons) in high-density hadronic matter are reviewed. After summarizing onset mechanisms of pion and kaon condensations, we discuss implications for neutron star phenomena such as rapid cooling through neutrino emission, static and dynamic properties of neutron stars. Recent studies on coexistence problem of pion and kaon condensations are briefly introduced. Finally, relevance of meson condensations in hadronic matter to those in color superconductivity are briefly mentioned.
A rigidity theorem in Alexandrov spaces with lower curvature bound
Takumi Yokota
Mathematics , 2009,
Abstract: Distance functions of metric spaces with lower curvature bound, by definition, enjoy various metric inequalities; triangle comparison, quadruple comparison and the inequality of Lang-Schroeder-Sturm. The purpose of this paper is to study the extremal cases of these inequalities and to prove rigidity results. The spaces which we shall deal with here are Alexandrov spaces which possibly have infinite dimension and are not supposed to be locally compact.
A unified understanding of the two formulae for the traces of the inverse powers of a positive definite symmetric tridiagonal matrix
Takumi Yamashita
Mathematics , 2014,
Abstract: For an upper bidiagonal matrix $B$ where all the diagonal and the upper subdiagonal entries are positive, two subtraction-free formulae for computation of the traces $J_{M} ( B ) = \textrm{Tr} ( ( B^{\top} B )^{- M} ) = \textrm{Tr} ( ( B B^{\top} )^{- M} )$ $( M = 1, 2, \dots )$ have been presented in the two preceding works. A few lower bounds of the minimal singular value of $B$ are obtained from these traces. In this paper, we clarify some properties of these formulae and present a new subtraction-free formula for the traces $J_{M} ( B )$. An interpretation of some quantities in one of the preceding works in terms of matrix theory is given. Some relationships between some quantities in the preceding works are also given. From these relationships, the new subtraction-free formula for the traces $J_{M} ( B )$ is obtained.
Perelman's reduced volume and a gap theorem for the Ricci flow
Takumi Yokota
Mathematics , 2008,
Abstract: In this paper, we show that any ancient solution to the Ricci flow with the reduced volume whose asymptotic limit is sufficiently close to that of the Gaussian soliton is isometric to the Euclidean space for all time. This is a generalization of Anderson's result for Ricci-flat manifolds. As a corollary, a gap theorem for gradient shrinking Ricci solitons is also obtained.
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