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Search Results: 1 - 10 of 149826 matches for " Takeyama H "
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Precise Measurement of a Magnetic Field Generated by the Electromagnetic Flux Compression Technique
D. Nakamura,H. Sawabe,Y. H. Matsuda,S. Takeyama
Physics , 2013, DOI: 10.1063/1.4798543
Abstract: The precision of the values of a magnetic field generated by electromagnetic flux compression was investigated in ultra-high magnetic fields of up to 700 T. In an attempt to calibrate the magnetic field measured by pickup coils, precise Faraday rotation (FR) measurements were conducted on optical (quartz and crown) glasses. A discernible "turn-around" phenomenon was observed in the FR signal as well as the pickup coils before the end of a liner implosion. We found that the magnetic field measured by pickup coils should be corrected by taking into account the high-frequency response of the signal transmission line. Near the peak magnetic field, however, the pickup coils failed to provide reliable values, leaving the FR measurement as the only method to precisely measure an extremely high magnetic fields.
Effects of short-term pulmonary rehabilitation on exercise capacity and quality of life in patients with chronic obstructive pulmonary disease.
Miyahara N,Eda R,Takeyama H,Kunichika N
Acta Medica Okayama , 2000,
Abstract: Although the rehabilitation of patients with chronic obstructive pulmonary disease (COPD) improves both exercise capacity and quality of life, a standard protocol for COPD patients has not been established. To clarify whether physiologic and quality-of-life improvements can be achieved by an inpatient pulmonary rehabilitation program 5 days per week for 3 weeks, 18 patients with COPD were enrolled in a rehabilitation program. The physical exercise training regimen consisted of respiratory muscle stretch gymnastics and cycle ergometer exercise training. Pulmonary function tests, an incremental ergometer exercise test, a 6-min walking test, and a quality of life assessment by the Chronic Respiratory Questionnaire were administered before and after the program. The peak VO2, an indicator of maximal exercise capacity, did not increase, although the 6-min walking distance, an indicator of functional exercise capacity, increased significantly after rehabilitation. There was a significant improvement in the quality of life in terms of dyspnea, fatigue, and emotional state. These findings suggest that even a 3-week program may be beneficial for COPD patients. Increases in functional exercise capacity, even without an increase in maximal exercise capacity, are helpful for reducing dyspnea and improving quality of life parameters in patients with COPD.
A recursion formula for the correlation functions of an inhomogeneous XXX model
H. Boos,M. Jimbo,T. Miwa,F. Smirnov,Y. Takeyama
Physics , 2004,
Abstract: A new recursion formula is presented for the correlation functions of the integrable spin 1/2 XXX chain with inhomogeneity. It relates the correlators involving n consecutive lattice sites to those with n-1 and n-2 sites. In a series of papers by V. Korepin and two of the present authors, it was discovered that the correlators have a certain specific structure as functions of the inhomogeneity parameters. Our formula allows for a direct proof of this structure, as well as an exact description of the rational functions which has been left undetermined in the previous works.
Dynamical Process of Liner Implosion in the Electromagnetic Flux Compression for Ultra-high Magnetic Fields
Daisuke Nakamura,Hironobu Sawabe,Yasuhiro H Matsuda,Shojiro Takeyama
Physics , 2013,
Abstract: The spatial distribution of magnetic fields that are generated by the electromagnetic flux compression technique is investigated, with emphasis on the dynamical processes of an imploding liner. By comparing with the results of computer simulations, we found that the non-uniform implosion of a liner is important in order to explain the magnetic field's distribution during the liner's implosion. In addition, our results suggest that the initial inwards compressing spool-like motion of the liner subsequently turns out to be outwards stretching barrel-like motion along the magnetic field axis.
Density matrix of a finite sub-chain of the Heisenberg anti-ferromagnet
H. Boos,M. Jimbo,T. Miwa,F. Smirnov,Y. Takeyama
Physics , 2005, DOI: 10.1007/s11005-006-0054-x
Abstract: We consider a finite sub-chain on an interval of the infinite XXX model in the ground state. The density matrix for such a subsystem was described in our previous works for the model with inhomogeneous spectral parameters. In the present paper, we give a compact formula for the physically interesting case of the homogeneous model.
Hidden Grassmann Structure in the XXZ Model II: Creation Operators
H. Boos,M. Jimbo,T. Miwa,F. Smirnov,Y. Takeyama
Mathematics , 2008, DOI: 10.1007/s00220-008-0617-z
Abstract: In this article we unveil a new structure in the space of operators of the XXZ chain. We consider the space of all quasi-local operators, which are products of the disorder field with arbitrary local operators. In analogy with CFT the disorder operator itself is considered as primary field. In our previous paper, we have introduced the annhilation operators which mutually anti-commute and kill the primary field. Here we construct the creation counterpart and prove the canonical anti-commutation relations with the annihilation operators. We show that the ground state averages of quasi-local operators created by the creation operators from the primary field are given by determinants.
Fermionic basis for space of operators in the XXZ model
H. Boos,M. Jimbo,T. Miwa,F. Smirnov,Y. Takeyama
Mathematics , 2007,
Abstract: In the recent study of correlation functions for the infinite XXZ spin chain, a new pair of anti-commuting operators $b(z), c(z)$ was introduced. They act on the space of quasi-local operators, which are local operators multiplied by the disorder operator. For the inhomogeneous chain with the spectral parameters $\xi_{k}$, these operators have simple poles at $z^2=\xi_{k}^2$. The residues are denoted by $b_{k}, c_{k}$. At $q=i$, we show that the operators $b_{k}, c_{k}$ are cubic monomials in free fermions. In other words, the action of these operators is very simple in the fermion basis. We give an explicit construction of these fermions. Then, we show that the existence of the fermionic basis is a consequence of the Grassmann relation, the equivariance with respect to the action of the symmetric group and the reduction property, which are all valid for the operators $b_{k}, c_{k}$ in the case of generic $q$.
Algebraic representation of correlation functions in integrable spin chains
H. Boos,M. Jimbo,T. Miwa,F. Smirnov,Y. Takeyama
Mathematics , 2006, DOI: 10.1007/s00023-006-0285-5
Abstract: Taking the XXZ chain as the main example, we give a review of an algebraic representation of correlation functions in integrable spin chains obtained recently. We rewrite the previous formulas in a form which works equally well for the physically interesting homogeneous chains. We discuss also the case of quantum group invariant operators and generalization to the XYZ chain.
Hidden Grassmann structure in the XXZ model
H. Boos,M. Jimbo,T. Miwa,F. Smirnov,Y. Takeyama
Mathematics , 2006, DOI: 10.1007/s00220-007-0202-x
Abstract: For the critical XXZ model, we consider the space W of operators which are products of local operators with a disorder operator. We introduce two anti-commutative family of operators b(z), c(z) which act on the space W. These operators are constructed as traces over representations of the q-oscillator algebra, in close analogy with Baxter's Q-operators. We show that the vacuum expectation values of operators in W can be expressed in terms of an exponential of a quadratic form of b(z), c(z).
Traces on the Sklyanin algebra and correlation functions of the eight-vertex model
H. Boos,M. Jimbo,T. Miwa,F. Smirnov,Y. Takeyama
Mathematics , 2005, DOI: 10.1088/0305-4470/38/35/003
Abstract: We propose a conjectural formula for correlation functions of the Z-invariant (inhomogeneous) eight-vertex model. We refer to this conjecture as Ansatz. It states that correlation functions are linear combinations of products of three transcendental functions, with theta functions and derivatives as coefficients. The transcendental functions are essentially logarithmic derivatives of the partition function per site. The coefficients are given in terms of a linear functional on the Sklyanin algebra, which interpolates the usual trace on finite dimensional representations. We establish the existence of the functional and discuss the connection to the geometry of the classical limit. We also conjecture that the Ansatz satisfies the reduced qKZ equation. As a non-trivial example of the Ansatz, we present a new formula for the next-nearest neighbor correlation functions.
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