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Search Results: 1 - 10 of 3592 matches for " Tetsuya Saito "
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Rationality and Stability of Equilibrium in a Search-Theoretic Model of Money  [PDF]
Tetsuya Saito
Theoretical Economics Letters (TEL) , 2012, DOI: 10.4236/tel.2012.23052
Abstract: In this short note, I examine the rationality of money-search equilibrium in a basic second-generation money search model, which is a perfectly divisible goods and indivisible money model. I then show that only an inflationary economy can generate a socially and individually rational stable equilibrium. On the basis of this finding, I demonstrate that there is no loss of generality in an analysis that assumes dictatorial buyers in an inflationary economy, since the properties of a dictatorial buyers model are identical to those of a general inflationary economy model. The result of this paper is especially useful for empirical applications since we are generally incapable of finding data showing bargaining power. This result also alerts us against employing the second-generation model to analyze a deflationary economy and commodity money.
Neutron stars with Hyperons in Dirac-Brueckner-Hartree-Fock approach
Tetsuya Katayama,Koichi Saito
Physics , 2014,
Abstract: Using the Dirac-Brueckner-Hartree-Fock (DBHF) approach including the hyperon degrees of freedom, we investigate the properties of neutron-star matter. To handle the hyperons in matter, we first examine the importance of the space part of baryon self-energies at high densities, and secondly study the effect of negative-energy states of baryons, which can provide an unambiguous relationship between the in-medium reaction matrices for baryon-baryon scattering and the baryon self-energies. We solve the coupled, Bethe-Salpeter equations in the nuclear-matter rest frame by using the Bonn potentials. We assume that eight kinds of nonstrange and strange mesons ($\sigma,\,\delta,\,\omega,\,\rho,\,\eta,\,\pi,\,K,\,K^{\ast}$) take part in the interactions between two baryons. Then, we calculate the baryon self-energies, the energy density and pressure of matter. The present calculation provides a hard equation of state in neutron-star matter at high densities, which is generated by the effect of Pauli exclusion, the short-range correlations between two baryons, etc. We finally predict the maximum neutron-star mass of $2.02\,M_{\odot}$, which is consistent with both the recently observed masses, $1.97\pm0.04M_{\odot}$ (J1614-2230) and $2.01\pm0.04M_{\odot}$ (J0348+0432).
Hyperons in neutron stars
Tetsuya Katayama,Koichi Saito
Physics , 2015,
Abstract: Using the Dirac-Brueckner-Hartree-Fock approach, the properties of neutron-star matter including hyperons are investigated. In the calculation, we consider both time and space components of the vector self-energies of baryons as well as the scalar ones. Furthermore, the effect of negative-energy states of baryons is partly taken into account. We obtain the maximum neutron-star mass of $2.08\,M_{\odot}$, which is consistent with the recently observed, massive neutron stars. We discuss a universal, repulsive three-body force for hyperons in matter.
Properties of dense, asymmetric nuclear matter in Dirac-Brueckner-Hartree-Fock approach
Tetsuya Katayama,Koichi Saito
Physics , 2013, DOI: 10.1103/PhysRevC.88.035805
Abstract: Within the Dirac-Brueckner-Hartree-Fock approach, using the Bonn potentials, we investigate the properties of dense, asymmetric nuclear matter and apply it to neutron stars. In the actual calculations of the nucleon self-energies and the energy density of matter, we study in detail the validity of an angle-averaged approximation and an averaging of the total momentum squared of interacting two-nucleons in nuclear matter. For practical use, we provide convenient parametrizations for the equation of state for symmetric nuclear matter and pure neutron matter. We also parametrize the nucleon self-energies in terms of polynomials of nucleon momenta. Those parametrizations can accurately reproduce the numerical results up to high densities.
Surgical Correction of Bifid Nose Due to Tessier’s No. 0 Cleft  [PDF]
Hiroki Shibayama, Takatoshi Yotsuyanagi, Tamotsu Saito, Ken Yamashita, Makoto Yamauchi, Tetsuya Suda
Modern Plastic Surgery (MPS) , 2014, DOI: 10.4236/mps.2014.41001

Bifid nose is a rare congenital abnormality and its surgical correction is difficult. We represent a case of bifid nose with mild nasal deformity without cerebral or lip deformity. We performed rhinoplasty with a kind of the forked flap at one year of age and the appearance improved.

Effects of Fock term, tensor coupling and baryon structure variation on a neutron star
Tsuyoshi Miyatsu,Tetsuya Katayama,Koichi Saito
Physics , 2011, DOI: 10.1016/j.physletb.2012.02.009
Abstract: The equation of state for neutron matter is calculated within relativistic Hartree-Fock approximation. The tensor couplings of vector mesons to baryons are included, and the change of baryon internal structure in matter is also considered using the quark-meson coupling model. We obtain the maximum neutron-star mass of $\sim 2.0 M_\odot$, which is consistent with the recently observed, precise mass, $1.97\pm0.04 M_{\odot}$. The Fock contribution is very important and, in particular, the inclusion of tensor coupling is vital to obtain such large mass. The baryon structure variation in matter also enhances the mass of a neutron star.
EoS for massive neutron stars
Tetsuya Katayama,Tsuyoshi Miyatsu,Koichi Saito
Physics , 2012, DOI: 10.1088/0067-0049/203/2/22
Abstract: Using relativistic Hartree-Fock approximation, we investigate the properties of the neutron-star matter in detail. In the present calculation, we consider not only the tensor coupling of vector mesons to octet baryons and the form factors at interaction vertexes but also the internal (quark) structure change of baryons in dense matter. The relativistic Hartree-Fock calculations are performed in two ways: one is the calculation with the coupling constants determined by SU(6) (quark model) symmetry, the other is with the coupling constants based on SU(3) (flavor) symmetry. For the latter case, we use the latest Nijmegen (ESC08) model. Then, it is very remarkable that the particle composition of the core matter in SU(3) symmetry is completely different from that in SU(6) symmetry. In SU(6) symmetry, all octet baryons appear in the density region below $\sim 1.2$ fm$^{-3}$, while, in the ESC08 model, only the \Xi^- hyperon is produced. Furthermore, the medium modification of the internal baryon structure hardens the equation of state for the core matter. Taking all these effects into account, we can obtain the maximum neutron-star mass which is consistent with the recently observed mass, 1.97 \pm 0.04 M_\sun (PSR J1614-2230). We therefore conclude that the extension from SU(6) symmetry to SU(3) symmetry in the meson-baryon couplings and the internal baryon-structure variation in matter certainly enhance the mass of neutron star. Furthermore, the effects of the form factor at vertex and the Fock contribution including the tensor coupling due to the vector mesons are indispensable to describe the core matter. In particular, the Fock term is very vital in reproducing the preferable value of symmetry energy, a_4 (\simeq 30 - 40 MeV), in nuclear matter.
Characteristics of a Transactive Phenomenon in Relationships among Older Adults with Dementia, Nurses as Intermediaries, and Communication Robot  [PDF]
Kyoko Osaka, Hiroko Sugimoto, Tetsuya Tanioka, Yuko Yasuhara, Rozzano Locsin, Yueren Zhao, Kikuko Okuda, Ken Saito
Intelligent Control and Automation (ICA) , 2017, DOI: 10.4236/ica.2017.82009
Abstract: Healthcare for older adults with dementia is an important healthcare problem in Japan and in other developed countries. Importantly, healthcare workers in Japan are also getting older. In order to address solutions to this problem, using robots is being realized and is starting to assist healthcare and welfare practice needs. The aim of this study was to identify the characteristics of a transactive phenomenon in relationships among older adults with dementia, with nurses as intermediaries and with a cognitive skill-aid robot. Subjects were two institutionalized older adults who were diagnosed with dementia using Hasegawa’s Dementia Scale-Revised; a Kabochan (Nodding Kabochan) fixed with a remote-controlled speaker, Pechat (Kabochan with Pechat). Measurements of autonomic nervous activity were done using wearable electrocardiography attached to the subjects for four hours. Heart Rate Variability data were assessed at various frequency bands using a HRV software tool. In a continuously recorded data, interbeat (R-R) intervals were obtained for a 1-min segment using the maximum entropy method. In this study, the two major spectral components of HRV, the variances of the low-frequency (LF: 0.04 - 0.15 Hz) band and high-frequency (HF: 0.15 - 0.4 Hz) band, were calculated. Activities and behaviors of subjects transacting with Kabochan were observed by the expert nurses and video-recorded. Throughout the transaction period, observations were recorded of patients’ behavior, words uttered and over-all contents of the transactive conversation with the Kabochan or Kabochan with Pechat. Identified characteristics were transactive relationship phenomenon; changes in autonomic nervous system activity of persons with dementia are expressed as per one minute, linguistic response of elderly people, transactive relations among Kabochan, Kabochan with Pechat, and nurses as intermediaries. These were exhibited as Figures: Situation 1, A Sense of Fear, Situation 2, A Pleasant Sensation, and Situation 3, Misunderstanding and Confusion. It also showed that autonomic nervous system activity of persons with communication skills is actively changing in older adults with dementia. Conversation of adding Pechat to the Kabochan illustrated that nurses as intermediaries showed emotional conversations as established by effectively manipulating the Pechat. Also, it was revealed that if Kabochan with Pechat uttered words about patient’s personal information in a conversation, the patient felt a sense of fear. The researchers suggest that when developing future
Efforts to Improve the Images from 67Ga Whole-Body Scintigraphy  [PDF]
Kyoko Saito, Yasuyuki Takahashi, Naomi Ogano, Hirotaka Shimada, Takao Kanzaki, Hiroki Okada, Kei Yokota, Kaori Hatano, Yuki Yoshida, Tetsuya Higuchi
World Journal of Nuclear Science and Technology (WJNST) , 2015, DOI: 10.4236/wjnst.2015.51001
Abstract: The acquisition method for planar 67Ga imaging has hardly changed for 30 years. In this study, in order to improve image quality and diagnostic accuracy, we take steps to optimize the acquisition method, and to choose a scatter correction. First, we acquired individual images from the 93 keV, 185 keV, and 300 keV photopeak; then the images were added together and compared to the individual images. Second, we compared results from a low-medium-energy (LME) collimator with those from a conventional medium-energy (ME) collimator. Also, we examined whether to combine the data from all three of the usual window locations (set about 93 keV, 185 keV, and 300 keV) or to use the data from only two. Third, we compared results from a conventional photopeak ± 10 window with those from a photopeak ± 9 keV window. Fourth, for scatter correction we compared results using the triple energy window (TEW) method with those using the multi-photopeak dual window (MDW) method. The phantoms studied were cold rods in a uniform background, and hot spheres within a cylinder containing uniformly radioactive water. The clinical study involved 22 patients with lung lesions. By the comparison by the contrast ratio in cold rods phantom, 15.6% is improved in LME (2 peaks) than ME (3 peaks), and 3.2% is improved in photopeak ± 9 keV than photopeak ± 10%, 10.2% is improved in TEW than MDW. However, the TEW scatter correction method recognized unstable to the contrast ratio in a clinical study. In addition, a body outline might disappear.
Characteristic Autonomic Nervous Activity of Institutionalized Elders with Dementia  [PDF]
Shoko Fuji, Tetsuya Tanioka, Yuko Yasuhara, Miki Sato, Ken Saito, Marguerite J. Purnell, Rozzano Locsin, Toshiyuki Yasui
Open Journal of Psychiatry (OJPsych) , 2016, DOI: 10.4236/ojpsych.2016.61004
Abstract: This study clarified the characteristic autonomic nervous activity of institutionalized elders diagnosed with dementia using Hasegawa’s Dementia Scale-Revised. Twenty-six healthy adult persons (HPs) in their 20 s - 40 s met the inclusion criteria, and 16 persons (27.6 ± 8.2 years old) completed the research procedure. Of 70 persons with dementia (PDs) residing at the one geriatric health services facilities, only 24 persons met the inclusion criteria, and only nine (N = 9, 83.44 ± 9.45 years old) completed the procedure. Actigraph and ambulatory electrocardiographic instruments measuring autonomic nervous activity were attached to the subjects for 24 hours. Activities and behaviors of PDs and HPs were observed by clinically experienced staff nurses and care workers. High frequency (HF) power indicating parasympathetic activity and LF/HF ratio indicating sympathetic activity were calculated. When awake, PDs’ LF/HF ratio was significantly lower than HP’s (Z = -2.60, p < 0.01), showing significant differences in the LF/HF ratios between waking and sleeping, more than those of the PDs (p < 0.001). Similarly, when awake, significant positive correlations were observed in the LF/HF ratio and actigraph activity count (AC) in 11 HPs and 3 PDs (range r = 0.17 to 0.49, p < 0.05); however, significant negative correlation was found in HF and AC of 12 HPs and 3 PDs (range r = -0.55 to -0.18, p < 0.05). While sleeping, significant positive correlations were observed in LF/HF and AC of 3 HPs and 1 PD (range r = 0.35 to 0.42, p < 0.05) and significant negative correlation was found in the HF and AC of 1 HP (r= -0.32, p < 0.001) and 1 PD (r = -0.32, p < 0.05). The mean value of LF/HF in a wakeful state was significantly lower for PDs than HPs. Combined results of behavioral observation, actigrapy and heart rate variability (HRV) analyses suggested that PDs showed positive correlations between LF/HF and AC in a wakeful state. Compared to those who showed no positive correlation, they did not require much nursing care.
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