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Search Results: 1 - 10 of 118600 matches for " T. Taniguchi "
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Dwarf galaxy formation induced by galaxy interactions
T. Okazaki,Y. Taniguchi
Physics , 2000, DOI: 10.1086/317109
Abstract: Growing evidence has been accumulated for that some gas-rich dwarf galaxies are formed from material liberated by galaxy collisions and/or mergers. Also, gas-poor dwarf elliptical galaxies are often found in the central regions of clusters of galaxies. These observations suggest strongly that the formation of most dwarf galaxies is linked to galaxy interactions. Therefore, now seems like the right time to investigate the formation efficiency of such tidal dwarf galaxies. Adopting the galaxy interaction scenario proposed by Silk & Norman, we find that if only a few dwarf galaxies are formed in each galaxy collision, we are able to explain the observed morphology-density relations for both dwarf and giant galaxies in the field, groups of galaxies, and clusters of galaxies. It seems worthwhile noting that the tidal dwarf formation may be coupled with the transformation from gas-rich disk galaxies to early-type galaxies such as S0 and elliptical galaxies.
How Do We See the Nuclear Region (r < 0.1 pc) of Narrow-Line Seyfert 1 Galaxies?
T. Murayama,T. Nagao,Y. Taniguchi
Physics , 2000, DOI: 10.1016/S1387-6473(00)00078-6
Abstract: We propose two statistical tests to investigate how we see the nuclear region (r < 0.1 pc) of Narrow-Line Seyfert 1 galaxies (NLS1s). 1) The high-ionization nuclear emission-line region (HINER) test: Seyfert 1 galaxies (S1s) have systematically higher flux ratios of [Fe VII] lambda 6087 to [O III] lambda 5007 than Seyfert 2 galaxies (S2s). This is interpreted in that a significant part of the [Fe VII] lambda 6087 emission arises from the inner walls of dusty tori that cannot be seen in S2s (Murayama & Taniguchi 1998a,b). 2) The mid-infrared test: S1s have systematically higher flux ratios of the L band (3.5 micrometer) to the IRAS 25 micrometer band than S2s. This is also interpreted in that a significant part of the L band emission arises from the inner walls of dusty tori, because the tori are optically thick enough to absorb the L band emission if the tori are viewed nearly edge on (Murayama et al. 2000). Applying these tests to a sample of NLS1s, we have found that the NLS1s possibly have nearly the same properties as S1s.
The Narrow-Line Region of Seyfert Galaxies: Narrow-Line Seyfert 1 Galaxies versus Broad-Line Seyfert 1 Galaxies
T. Nagao,T. Murayama,Y. Taniguchi
Physics , 2000, DOI: 10.1086/318300
Abstract: It is known that the spectral energy distribution (SED) of the nuclear radiation of narrow-line Seyfert 1 galaxies (NLS1s) has different shapes with respect to that of ordinary broad-line Seyfert 1 galaxies (BLS1s), particularly in wavelengths of X-ray. This may cause some differences in the ionization degree and the temperature of gas in narrow-line regions (NLRs) between NLS1s and BLS1s. This paper aims to examine whether or not there are such differences in the physical conditions of NLR gas between them. For this purpose, we have compiled the emission-line ratios of 36 NLS1s and 83 BLS1s from the literature. Comparing these two samples, we have found that the line ratios of [O {\sc i}]$\lambda$6300/[O {\sc iii}]$\lambda$5007 and [O {\sc iii}]$\lambda$4363/[O {\sc iii}]$\lambda$5007, which represent the ionization degree and the gas temperature respectively, are statistically indistinguishable between NLS1s and BLS1s. Based on new photoionization model calculations, we show that these results are not inconsistent with the difference of the SED between them. The influence of the difference of SEDs on the highly ionized emission lines is also briefly discussed.
The unexpected emotional similarities and behavioral differences of Japanese men experiencing parenthood in Japan and the USA  [PDF]
Hatsumi Taniguchi
Open Journal of Nursing (OJN) , 2012, DOI: 10.4236/ojn.2012.23031
Abstract: The purpose of this study was to understand the impact of childbirth and the experience of fatherhood on Japanese men in Japan and a foreign country. Descriptive phenomenology was used to study a total of 14 Japanese men who attended childbirth and experienced parenting in the United States and Japan. The Colaizzi method of data analysis was used to analyze responses to open-ended questions. Responses to these questions showed several similarities between the two groups of men. First, men in both countries felt closer to with their spouses having gone through the experience of childbirth together. Second, both groups nevertheless recognized a strong bond between mother and the baby, leading them to feel at times isolated. Third, both groups were concerned about their wives’ emotional swings during pregnancy and child rearing. Finally, both groups were more focused on their wives and babies than themselves. There were also several interesting differences. Japanese men who were living in Hawaii were more involved in taking care of their children and in helping with household chores than those living in Japan. This was due to living in a more family-oriented society, as well as a result of limited support from their extended families back in Japan. A result of spending more time with their wives and babies was that Japanese men in the United States understood more fully the stress of childcare. On the other hand, due to Japan’s work-oriented society, men in Japan relied more on support from their extended families, leaving them less time with their wives and children. This study clearly shows that social support systems alter gender roles and behavior, leading to significant differences in the experience of parenthood in Japan and a foreign country.
The Impact of Liberalization on the Production of Electricity in Japan: Stochastic Frontier Analysis  [PDF]
Miyuki Taniguchi
Open Journal of Applied Sciences (OJAppS) , 2014, DOI: 10.4236/ojapps.2014.44016
Abstract: This study aims to measure the impact of liberalization on the efficiency of electricity production in Japan using Stochastic Frontier Analysis (SFA). In addition, this study also aims to examine whether or not economies of scale exist in the electricity generation sector and the transmission sector, and whether or not economies of scope exist between electricity generation and transmission. Since 1995, liberalization of the electricity market in Japan has been phased in and regulations on entry have been relaxed three times. One motivation for these regularity changes has been to improve the efficiency of electricity production by introducing competition. Using a panel data set on the nine main power companies in Japan over the period 1970-2010, estimates of fixed-effects and stochastic frontier models of the cost function are obtained and compared. Estimates of the cost function show that liberalization has improved cost efficiency when both frontier models and non-frontier models are estimated. Estimates of the fixed-effects model are used to calculate economies of scale and economies scope because the data support the fixed-effects model. Economies of scope are found to exist for all nine power companies, while overall economies of scope declined in the 1970s and have improved little by little since the 1980s.
Super Characteristic Classes and Riemann-Roch Type Formula  [PDF]
Tadashi Taniguchi
Advances in Pure Mathematics (APM) , 2015, DOI: 10.4236/apm.2015.56034
Abstract:

The main purpose of this article is to define the super characteristic classes on a super vector bundle over a superspace. As an application, we propose the examples of Riemann-Roch type formula. We also introduce the helicity group and cohomology with respect to coefficient of the helicity group. As an application, we propose the examples of Gauss-Bonnet type formula.

SIMPLE DESIGN METHOD OF MIMO MULTIUSER DOWNLINK SYSTEM BASED ON BLOCK-DIAGONALIZATION
T. taniguchi,Y. Karasawa,N. Natajima
International Journal of New Computer Architectures and their Applications , 2011,
Abstract: Block diagonalization (BD) technique is widely used in multiple input multiple output (MIMO) multiuser downlink systems because of its simplicity and high ability for eliminating the interuser interferences. In this study, very simple weight design algorithms based on BD are proposed, in which the order of steps is swapped, namely, receiver weights are calculated first, and then transmisson weights are derived using zero forcing (ZF) approach. It is shown through computer simulations that the proposed method achieves better performance that the conventional BD under certain conditions. Additionally, the condition on the degrees of freedom is released, hence it can be utilized for the transmitters with small number of antennas to which BD cannot be applied.
Cosmic star formation history associated with QSO activity: an approach using the black hole to bulge mass correlation
Y. P. Wang,T. Yamada,Y. Taniguchi
Physics , 2002, DOI: 10.1086/373983
Abstract: The tight correlation between the masses of central black holes and their host spheroids in nearby galaxies and active galactic nuclei suggests that black hole growth is closely related to their spheroid formation. Based on our previous work regarding such a joint evolutionary scheme and the consequential black hole to bulge mass correlation, we use the X-ray luminosity function of AGN and the cosmological evolution rate which are from ROSAT X-ray surveys to estimate the cosmic star formation history associated with the black hole growth. By the Basic assumption that the major black hole growth occurs during the luminous AGN phase, the luminosity function of AGNs as a function of redshift traces not only the accretion history of the black holes but also the cosmic star formation history of the spheroids. Although the space density of the especially luminous QSOs is very low, we show that the total amount of star formation associated with the massive black hole growth is almost the same as that of Lyman Break Galaxies detected by the current optical deep surveys. We thus argue that the optical deep surveys may miss about half of the net star formation in our Universe, This is probably due to in part significant dust extinction as well as the small field of view of previous optical surveys which cannot sample such rare events with relatively short time scale. However, the far infrared emission from the dust heated by star fomation on-going during the black hole growth could sufficiently account for the observed SCUBA number counts, and would be the probable dominating energy source of the SUBA population.
A Geometrical Relationship between Broad-Line Clouds and an Accretion Disk around Active Galactic Nuclei
S. Nishiura,T. Murayama,Y. Taniguchi
Physics , 1998, DOI: 10.1093/pasj/50.1.31
Abstract: Recent hard X-ray spectroscopy of active galactic nuclei has strongly suggested that double-peaked, very broad Fe K emission arises from an accretion disk around the central engine. Model fitting of the observed Fe K emission line profile makes it possible to estimate a probable inclination angle of the accretion disk. In order to study the geometrical relationship between the accretion disk and broad emission-line regions (BLRs), we investigate the correlation between the inclination angle of the accretion disk and the velocity width of BLRs for 18 type-1 Seyfert galaxies. We found that there may be a negative correlation between them, i.e., Seyfert nuclei with a more face-on accretion disk tend to have larger BLR velocity widths, suggesting that the BLRs are not coplanar with respect to the accretion disk. The most probable interpretation may be that the BLRs arise from outer parts ({\it r} $\sim$ 0.01 pc) of a warped accretion disk illuminated by the central engine.
Theoretical study of spin-torque oscillator coupled with a nano-magnet by dipole-dipole interaction
H. Arai,T. Taniguchi,H. Imamura
Physics , 2013,
Abstract: The dynamics of a spin-torque-oscillator (STO) coupled with a nano-magnet through dipole-dipole interaction was studied numerically by using the macrospin model for the application of the STO as a read head sensor of hard disk drives. We found that the current, which is required to induce the oscillation of the free-layer (FL) of the STO, depends strongly on the distance between the FL and the nano-magnet as well as on the relative orientation of the magnetizations between them. To determine the dynamics of the STO it is indispensable to consider the dynamics of the dipole-coupled nano-magnet. We showed that we could detect the orientation of the magnetization of a nano-magnet, or a recording-bit, by the modulation of the oscillation frequency of the STO.
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