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Search Results: 1 - 10 of 117747 matches for " T. Nakamori "
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Design of RLS Wiener Smoother and Filter for Colored Observation Noise in Linear Discrete-Time Stochastic Systems  [PDF]
Seiichi Nakamori
Journal of Signal and Information Processing (JSIP) , 2012, DOI: 10.4236/jsip.2012.33041
Abstract: Almost estimators are designed for the white observation noise. In the estimation problems, rather than the white observation noise, there might be actual cases where the observation noise is modeled by the colored noise process. This paper examines to design a new estimation technique of recursive least-squares (RLS) Wiener fixed-point smoother and filter for colored observation noise in linear discrete-time wide-sense stationary stochastic systems. The observation y(k) is given as the sum of the signal z(k)=Hx(k) and the colored observation noise vc(k). The RLS Wiener estimators explicitly require the following information: 1) the system matrix for the state vector x(k); 2) the observation matrix H; 3) the variance of the state vector x(k); 4) the system matrix for the colored observation noise vc(k); 5) the variance of the colored observation noise; 6) the input noise variance in the state equation for the colored observation noise.
RLS Wiener Smoother for Colored Observation Noise with Relation to Innovation Theory in Linear Discrete-Time Stochastic Systems
Seiichi Nakamori
International Journal of Information Technology and Computer Science , 2013,
Abstract: Almost estimators are designed for the white observation noise. In the estimation problems, rather than the white observation noise, there might be actual cases where the observation noise is colored. This paper, from the viewpoint of the innovation theory, based on the recursive least-squares (RLS) Wiener fixed-point smoother and filter for the colored observation noise, newly proposes the RLS Wiener fixed-interval smoothing algorithm in linear discrete-time wide-sense stationary stochastic systems. The observation y(k) is given as the sum of the signal z(k)=Hx(k) and the colored observation noise (v_c)(k). The RLS Wiener fixed-interval smoother uses the following information: (a) the system matrix for the state vector x(k); (b) the observation matrix H; (c) the variance of the state vector; (d) the system matrix for the colored observation noise (v_c)(k); (e) the variance of the colored observation noise; (f) the input noise variance in the state equation for the colored observation noise.
Magnetization measurements on Li2Pd3B superconductor
P. Badica,T. Kondo,T. Kudo,Y. Nakamori,S. Orimo,K. Togano
Physics , 2004, DOI: 10.1063/1.1814433
Abstract: Magnetization in DC magnetic fields and at different temperatures have been measured on the Li2Pd3B compound. This material was recently found to show superconductivity at 7-8K. Critical fields Hc1(0) and Hc2(0) have been determined to be 135Oe and 4T, respectively. Critical current density, scaling of the pinning force within the Kramer model and the irreversibility field data are presented. Several superconductivity parameters were deduced: x(csi)=9.1 nm, l(lamda)=194nm and k=21. The material resembles other boride superconductors from the investigated points of view.
Multiband Diagnostics of Unidentified 1FGL Sources with Suzaku and Swift X-ray Observations
Y. Takeuchi,J. Kataoka,K. Maeda,Y. Takahashi,T. Nakamori,M. Tahara
Physics , 2013, DOI: 10.1088/0067-0049/208/2/25
Abstract: We have analyzed all the archival X-ray data of 134 unidentified (unID) gammaray sources listed in the first Fermi/LAT (1FGL) catalog and subsequently followed up by Swift/XRT. We constructed the spectral energy distributions (SEDs) from radio to gamma-rays for each X-ray source detected, and tried to pick up unique objects that display anomalous spectral signatures. In these analysis, we target all the 1FGL unID sources, using updated data from the second Fermi/LAT (2FGL) catalog on their LAT position and spectra. We found several potentially interesting objects, particularly three sources, 1FGL J0022.2-1850, 1FGL J0038.0+1236 and 1FGL J0157.0-5259, which were then more deeply observed with Suzaku as a part of an AO7 program in 2012. We successfully detected an X-ray counterpart for each source whose X-ray spectra were well fitted by a single power-law function. The positional coincidence with a bright radio counterpart (currently identified as AGN) in the 2FGL error circles suggests these are definitely the X-ray emission from the same AGN, but their SEDs show a wide variety of behavior. In particular, the SED of 1FGL J0038.0+1236 is difficult to be explained by conventional emission models of blazars. The source 1FGL J0022.2-1850 may be in a transition state between a low-frequency peaked BL Lac and a high-frequency peaked BL Lac object, and 1FGL J0157.0-5259 could be a rare kind of extreme blazar. We discuss the possible nature of these three sources observed with Suzaku, together with the X-ray identification results and SEDs of all 134 sources observed with Swift/XRT.
X-ray and Radio Follow-up Observations of High-Redshift Blazar Candidates in the Fermi-LAT Unassociated Source Population
Y. Takahashi,J. Kataoka,K. Niinuma,M. Honma,Y. Inoue,T. Totani,S. Inoue,T. Nakamori,K. Maeda
Physics , 2013, DOI: 10.1088/0004-637X/773/1/36
Abstract: We report on the results of X-ray and radio follow-up observations of two GeV gamma-ray sources 2FGL J0923.5+1508 and 2FGL J1502.1+5548, selected as candidates for high-redshift blazars from unassociated sources in the {\it Fermi} Large Area Telescope Second Source Catalog. We utilize the Suzaku satellite and the VLBI Exploration of Radio Astrometry (VERA) telescopes for X-ray and radio observations, respectively. For 2FGL J0923.5+1508, a possible radio counterpart NVSS J092357+150518 is found at 1.4 GHz from an existing catalog, but we do not detect any X-ray emission from it and derive a flux upper limit $F_{\rm 2-8 keV} <$ 1.37 $\times$ 10$^{-14}$ erg cm$^{-2}$ s$^{-1}$. Radio observations at 6.7 GHz also result in an upper limit of $S_{\rm 6.7 GHz}$ $<$ 19 mJy, implying a steep radio spectrum that is not expected for a blazar. On the other hand, we detect X-rays from NVSS J150229+555204, the potential 1.4 GHz radio counterpart of 2FGL J1502.1+5548. The X-ray spectrum can be fitted with an absorbed power-law model with a photon index $\gamma$=1.8$^{+0.3}_{-0.2}$ and the unabsorbed flux is $F_{\rm 2-8 keV}$=4.3$^{+1.1}_{-1.0}$ $\times$ 10$^{-14}$ erg cm$^{-2}$ s$^{-1}$. Moreover, we detect unresolved radio emission at 6.7 GHz with flux $S_{\rm 6.7 GHz}$=30.1 mJy, indicating a compact, flat-spectrum radio source. If NVSS J150229+555204 is indeed associated with 2FGL J1502.1+5548, we find that its multiwavelength spectrum is consistent with a blazar at redshift $z \sim 3-4$.
Activated Carbons Containing Dispersed Metal Oxide Particles for Removal of Methyl Mercaptan in Air  [PDF]
Hisashi Tamai, Miki Nakamori, Masayoshi Nishikawa, Takeshi Shiono
Materials Sciences and Applications (MSA) , 2011, DOI: 10.4236/msa.2011.21007
Abstract: Activated carbons containing dispersed metal oxide particles were prepared by carbonization of phenol resin containing metal compounds followed by steam activation. Acetylacetonates of Fe, Mn and V, and Cu nitrate were used as the sources of metals. The removal of a small amount of methyl mercaptan (CH3SH) in air with these activated carbons was tested in a flow system. Compared with activated carbons without metal oxides, the carbons exhibited high activity for the removal of CH3SH in air. In particular, activated carbon obtained from Novolac containing 5 wt% Cu showed excellent behavior over a long time.
Effectiveness of a Custom-Made Temporary Obturator after Bilateral Total Maxillectomy  [PDF]
Kenji Nakamori, Manabu Yamagishi, Keigo Takaya, Tomohiro Igarashi, Hiroyoshi Hiratsuka
Surgical Science (SS) , 2013, DOI: 10.4236/ss.2013.47063
Abstract:

Large oro-antral communication, associated with total maxillectomy, may lead speech and/or swallowing dysfunction. These surgical defects are packed with obuturator or prosthesis following surgery; however, achieving retention and stability is dependent on anatomical conditions. A 68-year-old Japanese female with large oro-antral communication arising because of bilateral total maxillectomy was referred for evaluating application of obturator. The temporary obturator was constructed as underlying 3 mm thick and covereing 1.5 - 2 mm thick ethylene vinyl acetate sheet (EVA). These two sheets formed the flexible hollow bulb portion, which aided retention and stability by engaging the undercut portion of the surgical defect. For the patients who have difficulty anatomical features for conventional prosthesis, this type of temporary obturator made with EVA sheets could be an effective solution in the early postoperative period.

Suzaku observations of the diffuse x-ray emission across the fermi bubbles' edges
J. Kataoka,M. Tahara,T. Totani,Y. Sofue,L. Stawarz,Y. Takahashi,Y. Takeuchi,H. Tsunemi,M. Kimura,Y. Takei,C. C. Cheung,Y. Inoue,T. Nakamori
Physics , 2013, DOI: 10.1088/0004-637X/779/1/57
Abstract: We present Suzaku X-ray observations along two edge regions of the Fermi Bubbles, with eight ~20 ksec pointings across the northern part of the North Polar Spur (NPS) surrounding the north bubble and six across the southernmost edge of the south bubble. After removing compact X-ray features, diffuse X-ray emission is clearly detected and is well reproduced by a three-component spectral model consisting of unabsorbed thermal emission (temperature kT ~0.1 keV from the Local Bubble (LB), absorbed kT ~0.3 keV thermal emission related to the NPS and/or Galactic Halo (GH), and a power-law component at a level consistent with the cosmic X-ray background. The emission measure (EM) of the 0.3 keV plasma decreases by ~50% toward the inner regions of the north-east bubble, with no accompanying temperature change. However, such a jump in the EM is not clearly seen in the south bubble data. While it is unclear if the NPS originates from a nearby supernova remnant or is related to previous activity within/around the Galactic Center, our Suzaku observations provide evidence suggestive of the latter scenario. In the latter framework, the presence of a large amount of neutral matter absorbing the X-ray emission as well as the existence of the kT ~ 0.3 keV gas can be naturally interpreted as a weak shock driven by the bubbles' expansion in the surrounding medium, with velocity v_exp ~300 km/s (corresponding to shock Mach number M ~1.5), compressing the GH gas to form the NPS feature. We also derived an upper limit for any non-thermal X-ray emission component associated with the bubbles and demonstrate, that in agreement with the findings above, the non-thermal pressure and energy estimated from a one-zone leptonic model of its broad-band spectrum, are in rough equilibrium with that of the surrounding thermal plasma.
Suzaku X-ray Imaging of the Extended Lobe in the Giant Radio Galaxy NGC6251 Associated with the Fermi-LAT Source 2FGLJ1629.4+8236
Y. Takeuchi,J. Kataoka,L. Stawarz,Y. Takahashi,K. Maeda,T. Nakamori,C. C. Cheung,A. Celotti,Y. Tanaka,T. Takahashi
Physics , 2012, DOI: 10.1088/0004-637X/749/1/66
Abstract: We report the results of a Suzaku X-ray imaging study of NGC6251, a nearby giant radio galaxy with intermediate FR I/II radio properties. Our pointing direction was centered on the gamma -ray emission peak recently discovered with Fermi-LAT around the position of the north-west radio lobe 15 arcmin offset from the nucleus. After subtracting two "off-source" pointings adjacent to the radio lobe, and removing possible contaminants in the XIS field of view, we found significant residual X-ray emission most likely diffuse in nature. The spectrum of the excess X-ray emission is well fit by a power law with photon index \Gamma = 1.90 +- 0.15 and a 0.5 - 8 keV flux of 4 x 10^{-13} erg cm^{-2} s^{-1}. We interpret this diffuse X-ray emission component as being due to inverse-Compton up-scattering of the cosmic microwave background photons by ultrarelativistic electrons within the lobe, with only a minor contribution from the beamed emission of the large-scale jet. Utilizing archival radio data for the source, we demonstrate by means of broad-band spectral modeling that the -ray flux of the Fermi-LAT source 2FGL J1629.4+8236 may well be accounted for by the high-energy tail of the inverse-Compton continuum of the lobe. Thus, this claimed association of gamma-rays from the north-west lobe of NGC6251, together with the recent Fermi-LAT imaging of the extended lobes of Centaurus A, indicates that particles may be efficiently (re-)accelerated up to ultrarelativistic energies within extended radio lobes of nearby radio galaxies in general.
The Role of Alpha-Dystrobrevin in Striated Muscle
Masayuki Nakamori,Masanori P. Takahashi
International Journal of Molecular Sciences , 2011, DOI: 10.3390/ijms12031660
Abstract: Muscular dystrophies are a group of diseases that primarily affect striated muscle and are characterized by the progressive loss of muscle strength and integrity. Major forms of muscular dystrophies are caused by the abnormalities of the dystrophin glycoprotein complex (DGC) that plays crucial roles as a structural unit and scaffolds for signaling molecules at the sarcolemma. α-Dystrobrevin is a component of the DGC and directly associates with dystrophin. α-Dystrobrevin also binds to intermediate filaments as well as syntrophin, a modular adaptor protein thought to be involved in signaling. Although no muscular dystrophy has been associated within mutations of the α-dystrobrevin gene, emerging findings suggest potential significance of α-dystrobrevin in striated muscle. This review addresses the functional role of α-dystrobrevin in muscle as well as its possible implication for muscular dystrophy.
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