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Search Results: 1 - 10 of 2024 matches for " Naoki Yasuda "
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Surface Photometric Calibration of the Infrared Tully-Fisher Relation Using Cepheid-based Distances of Galaxies
Masaru Watanabe,Naoki Yasuda,Nobunari Itoh
Physics , 2001, DOI: 10.1086/321471
Abstract: Infrared J and H surface photometry are carried out for nearby 12 galaxies whose distances have been accurately measured via HST Cepheid observations. Using the total, isophotal, and surface-photometric aperture magnitudes we calibrate the infrared luminosity-line width relation (IRTF). It is found that IRTF changes its slope at log W_{20}^c=2.45 in all the examined magnitude systems. The apparent scatter of IRTF is not significantly reduced when surface photometric magnitudes are used instead of the conventionally used synthetic aperture magnitude H_{-0.5}. It is also shown that the color (I-H)_T of the nearby calibrator galaxies is redder by 0.2mag than the Coma cluster galaxies, but such a trend is not clearly visible for the Ursa Major mostly because of poor statistics. The color offset of the Coma is analogous to that previously found in I_T-H_{-0.5}. From the present calibration of H-band IRTF, we obtain the distance to the Coma cluster to be m-M=34.94 +/- 0.13mag, where no account is taken of the I-H color problem. Using the CMB-rest recession velocity of the Coma cluster we obtain H_0=73 +/- 4 km/s/Mpc.
Open Distal Gastrectomy versus Laparoscopic Distal Gastrectomy: As Influenced by Facility Background Factors in the Real World  [PDF]
Nozomu Murakami, Shinichi Kadoya, Masanari Shimada, Naoki Endo, Kaname Ishiguro, Koichiro Sawada, Kouichi Tanabe, Hatsuna Yasuda, Noriyuki Inaki, Tetsuji Yamada, Eiji Kanehira, Tatsuhiko Kashii
Surgical Science (SS) , 2014, DOI: 10.4236/ss.2014.53019

The purpose of our study was to retrospectively evaluate the clinical efficacy and safety of laparoscopy assisted distal gastrectomy (LADG) performed by one operating and advising surgeon in patients with gastric cancer over a period of 10 years. We examined the choice of anastomosis techniques, and compared the duration of surgery, blood loss, number of dissected lymph nodes and intraoperative complications for LADG and open distal gastrectomy (ODG). We studied 254 patients who underwent laparoscopic gastrectomy and 36 patients who underwent ODG. 169 of 254 patients received LADG. Duration of surgery was significantly longer for LADG than that for ODG, blood loss was significantly smaller, and numbers of dissected lymph nodes were similar. With LADG, there was anastomotic leakage in 2 patients and postoperative obstruction in 2 patients. No recurrence of disease and no deaths have been reported to date. Though previous clinical trials have shown that LADG is less invasive, our study of LADG in the real world did not show superiority, but rather equivalence to ODG in terms of other outcomes. This study could be advantageous to evaluate the clinical efficacy and safety of LADG without having to take into account multiple surgeons’ technical levels and the background differences between the facilities.

Instability in the Hotelling’s Non-Price Spatial Competition Model  [PDF]
Yosuke Yasuda
Theoretical Economics Letters (TEL) , 2013, DOI: 10.4236/tel.2013.33A002

This note analyzes a slightly modified Hotelling model in which two firms are allowed to choose multiple store locations. Each firm can endogenously choose the number of stores while opening a store incurs a set-up cost. We show that the principle of minimum differentiation, i.e., both firms open a store each on the center, never holds when the set-up cost is decreasing in the number of stores. Under general cost functions that include non-linear and asymmetric set up costs, we characterize the conditions under which the principle holds. General payoff functions that are non-linear in the market share are also considered.

On Utilization of K-Means for Determination of q-Parameter for Tsallis-Entropy-Maximized-FCM  [PDF]
Makoto Yasuda
Journal of Software Engineering and Applications (JSEA) , 2017, DOI: 10.4236/jsea.2017.107033
Abstract: In this paper, we consider a fuzzy c-means (FCM) clustering algorithm combined with the deterministic annealing method and the Tsallis entropy maximization. The Tsallis entropy is a q-parameter extension of the Shannon entropy. By maximizing the Tsallis entropy within the framework of FCM, membership functions similar to statistical mechanical distribution functions can be derived. One of the major considerations when using this method is how to determine appropriate q values and the highest annealing temperature, Thigh?, for a given data set. Accordingly, in this paper, a method for determining these values simultaneously without introducing any additional parameters is presented. In our approach, the membership function is approximated by a series of expansion methods and the K-means clustering algorithm is utilized as a preprocessing step to estimate a radius of each data distribution. The results of experiments indicate that the proposed method is effective and both q and Thigh can be determined automatically and algebraically from a given data set.
Deregulation of histone lysine methyltransferases contributes to oncogenic transformation of human bronchoepithelial cells
Hideo Watanabe, Kenzo Soejima, Hiroyuki Yasuda, Ichiro Kawada, Ichiro Nakachi, Satoshi Yoda, Katsuhiko Naoki, Akitoshi Ishizaka
Cancer Cell International , 2008, DOI: 10.1186/1475-2867-8-15
Abstract: We observed differential HKMT expression in a lung cancer model in which normal human bronchial epithelial (NHBE) cells expressing telomerase, SV40 large T antigen, and Ras were immortal, formed colonies in soft agar, and expressed specific HKMTs for H3 lysine 9 and 27 residues but not for H3 lysine 4 residue. Modifications in the H3 tails affect the binding of proteins to the histone tails and regulate protein function and the position of lysine methylation marks a gene to be either activated or repressed. In the present study, suppression by siRNA of HKMTs (EZH2, G9A, SETDB1 and SUV39H1) that are over-expressed in immortalized and transformed cells lead to reduced cell proliferation and much less anchorage-independent colony growth. We also found that the suppression of H3-K9, G9A and SUV39H1 induced apoptosis and the suppression of H3-K27, EZH2 caused G1 arrest.Our results indicate the potential of these HKMTs in addition to the other targets for epigenetics such as DNMTs and HDACs to be interesting therapeutic targets.Alterations in the processing of the genetic information in carcinogenesis result from stable genetic mutations involving tumor suppressor genes, oncogenes and DNA stability genes as well as from potentially reversible epigenetic changes leading to modifications in gene function [1,2]. It is well established that epigenetic modifications of nucleosomal histones are central to proper gene expression and aberrant DNA methylation of genes play an important role in tumor progression. However, still relatively little is known about histone modifications, especially methylation, with respect to tumorigenesis. The N-terminus of histone tails is modified by amino-acid phosphorylation, acetylation or methylation to form a code for specifying downstream events and consequently a certain chromatin structure. Tens of histone lysine methyltransferases (HKMTs) have been identified and histone lysine methylation is now considered to be a critical regulator of tra
Proper motions with Subaru II. A sample in the Subaru/XMM-Newton Deep Survey field
Michael W. Richmond,Tomoki Morokuma,Mamoru Doi,Yutaka Komiyama,Naoki Yasuda,Sadanori Okamura
Physics , 2009, DOI: 10.1093/pasj/62.1.91
Abstract: We search for stars with proper motions in a set of deep Subaru images, covering about 0.48 square degrees to a depth of $i' \simeq 26$, taken over a span of five and a half years. We follow the methods described in \citet{Richmond2009} to reduce and analyze this dataset. We present a sample of 69 stars with motions of high significance, and discuss briefly the populations from which they are likely drawn. Based on photometry and motions alone, we expect that 14 of the candidates may be white dwarfs. Our candidate with the largest proper motion is surprisingly faint and likely to prove interesting: its colors and motions suggest that it might be an M dwarf moving at over 500 km/sec or an L dwarf in the halo.
Early Science Result from the Japanese Virtual Observatory: AGN and Galaxy Clustering at z = 0.3 to 3.0
Yuji Shirasaki,Masahiro Tanaka,Masatoshi Ohishi,Yoshihiko Mizumoto,Naoki Yasuda,Tadafumi Takata
Physics , 2009, DOI: 10.1093/pasj/63.sp2.S469
Abstract: We present the result of projected cross correlation analysis of AGNs and galaxies at redshifts from 0.3 to 3.0. The Japanese Virtual Observatory (JVO) was used to obtain the Subaru Suprime-Cam images and UKIDSS catalog data around AGNs. We investigated 1,809 AGNs, which is about ten times larger a sample than that used in previous studies on AGN-galaxy clustering at redshifts larger than 0.6. 90% of the AGN samples are optically-selected AGN from the SDSS and 2dF catalogs. The galaxy samples at low redshift includes many redder objects from UKIDSS survey, while at higher redshift they are mainly blue galaxies from Suprime-Cam. We found significant excess of galaxies around the AGNs at redshifts from 0.3 to 1.8. For the low redshift samples ($z<0.9$), we obtained correlation length of $r_{0} = $5--6 $h^{-1}$Mpc ($\gamma = 1.8$), which indicates that the AGNs at this redshift range reside in a similar environment around typical local galaxies. We also found that AGNs at higher redshift ranges reside in a denser environment than lower redshift AGNs; For $z=1.3 \sim 1.8$ AGNs, the cross correlation length was measured as 11$^{+6}_{-3}$ $h^{-1}$Mpc ($\gamma=1.8$). Considering that our galaxies sample is based on optical observations with Suprime-Cam at the redshift range, it is expected that blue star-forming galaxies comprise the majority of objects that are observed to be clustered around the AGNs. It is successfully demonstrated that the use of the archive through the Virtual Observatory system can provide a powerful tool for investigating the small scale environment of the intermediate redshift AGNs.
Retrieving Bulge and Disk Parameters and Asymptotic Magnitudes from the Growth Curves of Galaxies
Sadanori Okamura,Naoki Yasuda,Kazuhiro Shimasaku,Masafumi Yagi,David H. Weinberg
Physics , 1998, DOI: 10.1086/316298
Abstract: We show that the growth curves of galaxies can be used to determine their bulge and disk parameters and bulge-to-total luminosity ratios, in addition to their conventional asymptotic magnitudes, provided that the point spread function is accurately known and signal-to-noise ratio is modest (S/N$\gtrsim30$). The growth curve is a fundamental quantity that most future large galaxy imaging surveys will measure. Bulge and disk parameters retrieved from the growth curve will enable us to perform statistical studies of luminosity structure for a large number of galaxies.
Characterisation of Sloan Digital Sky Survey Stellar Photometry
Masataka Fukugita,Naoki Yasuda,Mamoru Doi,James E. Gunn,Donald G. York
Physics , 2010, DOI: 10.1088/0004-6256/141/2/47
Abstract: We study the photometric properties of stars in the data archive of the Sloan Digital Sky Survey (SDSS), the prime aim being to understand the photometric calibration over the entire data set. It is confirmed that the photometric calibration for point sources has been made overall tightly against the SDSS standard stars. We have also confirmed that photometric synthesis of the SDSS spectrophotometric data gives broad band fluxes that agree with broad band photometry with errors no more than 0.04 mag and little tilt along the wide range of colours, verifying that the response functions of the SDSS 2.5 m telescope system are well characterised. We locate stars in the SDSS photometric system, so that stars can roughly be classified into spectral classes from the colour information. We show how metallicity and surface gravity affect colours, and that stars contained in the SDSS general catalogue, plotted in colour space, show the distribution that matches well with what is anticipated from the variations of metallicity and surface gravity. The colour-colour plots are perfectly consistent among the three samples, stars in the SDSS general catalogue, SDSS standard stars and spectrophotometric stars of Gunn & Stryker, especially when some considerations are taken into account of the differences (primarily metallicity) of the samples. We show that the g-r - inverse temperature relation is tight and can be used as a good estimator of the effective temperature of stars over a fairly wide range of effective temperatures. We also confirm that the colours of G2V stars in the SDSS photometric system match well with the Sun.
The SDSS Imaging Pipelines
Robert Lupton,James E. Gunn,Zeljko Ivezic,Gillian R. Knapp,Stephen Kent,Naoki Yasuda
Physics , 2001,
Abstract: We summarise the properties of the Sloan Digital Sky Survey (SDSS) project, discuss our software infrastructure, and outline the architecture of the SDSS image processing pipelines. We then discuss two of the algorithms used in the SDSS image processing; the KL-transform based modelling of the spatial variation of the PSF, and the use of galaxy models in star/galaxy separation. We conclude with the first author's personal opinions on the challenges that the astronomical community faces with major software projects.
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