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Search Results: 1 - 10 of 150159 matches for " H. Takagi "
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An Analytical Approach for Degree Correlations in Complex Network  [PDF]
Kosuke Takagi
World Journal of Mechanics (WJM) , 2012, DOI: 10.4236/wjm.2012.23020
Abstract: We investigate correlations between neighbor degrees in the scale-free network. According to the empirical studies, it is known that the degree correlations exhibit nontrivial statistical behaviors. With using an analytical approach, we show that the scale-freeness and one of statistical laws for degree correlations can be reproduced consistently in a unified framework. Our result would have its importance in understanding the mechanisms which generate the complex network.
An Analytical Model of the Power Law Distributions in the Complex Network  [PDF]
Kosuke Takagi
World Journal of Mechanics (WJM) , 2012, DOI: 10.4236/wjm.2012.24027
Abstract: It is known that complex networks in nature exhibit some significant statistical features. We notice power law distributions which frequently emerge with respect to network structures of various quantities. One example is the scale-freeness which is described by the degree distribution in the power law shape. In this paper, within an analytical approach, we investigate the analytical conditions under which the distribution is reduced to the power law. We show that power law distributions are obtained without introducing conditions specific to each system or variable. Conversely, if we demand no special condition to a distribution, it is imposed to follow the power law. This result explains the universality and the ubiquitous presence of the power law distributions in complex networks.
Perspective of Adaptive CN System for Forecasting Congestion of Road Traffic Flow  [PDF]
Tasuku Takagi
Communications and Network (CN) , 2014, DOI: 10.4236/cn.2014.62008

Basing upon the Weber-Fechner Law with respect to the stimulus (distance-headway) to the vehicle driver and the driver’s sensation (speed), the characteristic speed Vβ is defined, which is the critical vehicles flow speed just before going to congestion in road traffic flow. From the information of real time measurement of traffic flow speed (V) and time-headway (T) at the specific positions along the road, the value of Vβ is calculated and used for forecasting the flow. Discussed is how to use each Vβ to forecast the congestion. The CN system devoted to the management of road traffic flow is proposed. The idea may contribute not only to easing the traffic flow but also to optimizing it to get high efficient traffic flow.

X-ray Sources and Star Formation Activity in the Sgr B2 Cloud Observed with Chandra
S. Takagi,H. Murakami,K. Koyama
Physics , 2002, DOI: 10.1086/340499
Abstract: We report the X-ray population study in the giant molecular cloud Sagittarius B2 (SgrB2). More than a dozen of X-ray cloud members (and candidates) are discovered with Chandra. Two bright X-ray sources are located near Sgr B2 Main, the most copious complex of the ultra compact HII sources. The X-ray spectra are fitted with a thin thermal plasma model of 5-10 keV temperature. The intrinsic luminosity after correcting the absorption of 5 x 10^23 H/cm^2 is about 10^33 erg/s. Although these two X-ray sources are attributable to young stellar objects (YSOs) in the same HII complex, they are in sharp contrast; one at the center of the HII complex exhibits strong K-shell transition lines of iron, while the other near the east has only weak lines. The other HII complexes, SgrB2 North and South, also show hard and highly absorbed X-ray emissions due possibly to the star formation activity. The composite X-ray spectrum of the other cloud member X-ray sources is fitted with a thin thermal plasma of about 10-keV temperature with the hydrogen column density (N_H) of 1.3 x 10^23 H/cm^2, and the individual X-ray luminosity of a few times of 10^31-32$ erg/s. These are likely to be a single or cluster of YSO(s), but neither radio nor infrared counterpart is found. An alternative scenario of isolated white dwarfs powered by the Bondi-Hoyle accretion from the dense cloud gas is also discussed. The X-ray spectra exhibit an additional 6.4-keV line of neutral or low-ionization irons, which indicates that the environment gas is concentrated near at the sources.
Universality of the Mott-Ioffe-Regel limit in metals
N. E. Hussey,K. Takenaka,H. Takagi
Physics , 2004, DOI: 10.1080/14786430410001716944
Abstract: The absence of resistivity saturation in many strongly correlated metals, including the high-temperature superconductors, is critically examined from the viewpoint of optical conductivity measurements. Coherent quasiparticle conductivity, in the form of a Drude peak centred at zero frequency, is found to disappear as the mean free path (at $\omega$ = 0) becomes comparable to the interatomic spacing. This basic loss of coherence at the so-called Mott-Ioffe-Regel (MIR) limit suggests that the universality of the MIR criterion is preserved even in the presence of strong electron correlations. We argue that the shedding of spectral weight at low frequencies, induced by strong correlation effects, is the primary origin of the extended positive slope of the resistivity to high temperatures observed in all so-called "bad metals". Moreover, in common with those metals which exhibit resistivity saturation at high temperatures, the scattering rate itself, as extracted from optical spectra, saturates at a value consistent with the MIR limit. We consider possible implications that this ceiling in the scattering rate may have for our understanding of transport within a wide variety of bad metals and suggest a better method for analysing their optical response.
Evolution of genetic code through isologous diversification of cellular states
H. Takagi,K. Kaneko,T. Yomo
Physics , 2000,
Abstract: Evolution of genetic code is studied as the change in the choice of enzymes that are used to synthesize amino acids from the genetic information of nucleic acids. We propose the following theory: the differentiation of physiological states of a cell allows for the different choice of enzymes, and this choice is later fixed genetically through evolution. To demonstrate this theory, a dynamical systems model consisting of the concentrations of metabolites, enzymes, amino acyl tRNA synthetase, and tRNA-amino acid complex in a cell is introduced and numerically studied. It is shown that the biochemical states of cells are differentiated by cell-cell interaction, and each differentiated type takes to use different synthetase. Through the mutation of genes, this difference in the genetic code is amplified and stabilized. Relevance of this theory to the evolution of non-universal genetic code in mitochondria is suggested. The present theory for the evolution of genetic code is based on our recent theory of isologous symbiotic speciation, which is briefly reviewed. According to the theory, phenotypes of organisms are first differentiated into distinct types through the interaction and developmental dynamics, even though they have identical genotypes, and later with the mutation in genotype, the genotype also differentiates into discrete types, while maintaining the `symbiotic' relationship between the types. Relevance of the theory to natural as well as artificial evolution is discussed.
Nonpolar resistance switching of metal/binary-transition-metal oxides/metal sandwiches: homogeneous/inhomogeneous transition of current distribution
I. H. Inoue,S. Yasuda,H. Akinaga,H. Takagi
Physics , 2007, DOI: 10.1103/PhysRevB.77.035105
Abstract: Exotic features of a metal/oxide/metal (MOM) sandwich, which will be the basis for a drastically innovative nonvolatile memory device, is brought to light from a physical point of view. Here the insulator is one of the ubiquitous and classic binary-transition-metal oxides (TMO), such as Fe2O3, NiO, and CoO. The sandwich exhibits a resistance that reversibly switches between two states: one is a highly resistive off-state and the other is a conductive on-state. Several distinct features were universally observed in these binary TMO sandwiches: namely, nonpolar switching, non-volatile threshold switching, and current--voltage duality. From the systematic sample-size dependence of the resistance in on- and off-states, we conclude that the resistance switching is due to the homogeneous/inhomogeneous transition of the current distribution at the interface.
Edoxaban for prevention of venous thromboembolism after major orthopedic surgery
Kawaji H, Ishii M, Tamaki Y, Sasaki K, Takagi M
Orthopedic Research and Reviews , 2012, DOI: http://dx.doi.org/10.2147/ORR.S24583
Abstract: oxaban for prevention of venous thromboembolism after major orthopedic surgery Review (2177) Total Article Views Authors: Kawaji H, Ishii M, Tamaki Y, Sasaki K, Takagi M Published Date May 2012 Volume 2012:4 Pages 53 - 64 DOI: http://dx.doi.org/10.2147/ORR.S24583 Received: 02 February 2012 Accepted: 18 April 2012 Published: 28 May 2012 Hiroyuki Kawaji,1 Masaji Ishii,1 Yasunobu Tamaki,1 Kan Sasaki,2 Michiaki Takagi,2 1Department of Orthopaedic Surgery, Saiseikai Yamagata Saisei Hospital, 2Department of Orthopaedic Surgery, Yamagata University Faculty of Medicine, Yamagata, Japan Abstract: Fatal pulmonary thromboembolism is the most serious complication following surgery. Patients undergoing major orthopedic surgeries, including total hip replacement, total knee replacement, and hip fracture surgery, represent a group at particularly high risk of venous thromboembolism. Therefore, prophylaxis for thromboembolic events has been of great concern to surgeons. Edoxaban is a novel, orally available, and highly specific and direct factor Xa inhibitor. This new agent was approved for the prevention of venous thromboembolism in patients undergoing major orthopedic surgery, including total hip replacement, total knee replacement, and hip fracture surgery, by the Japanese Ministry of Health, Labor, and Welfare in 2011. Preclinical and Phase I clinical trials demonstrated several promising properties. Its rapid absorption and short life-time in blood are known. Edoxaban inhibits factor Xa activity directly and selectively. It also has a strong antithrombotic effect without any influence of food intake. Coagulation monitoring is not required. Edoxaban has predictable linear pharmacokinetic and pharmacodynamic profiles. Phase II and III clinical trials have been completed to examine its efficacy and safety in patients undergoing major orthopedic surgery. In these clinical trials, oral administration of edoxaban showed efficacy superior to that of oral placebo or subcutaneously administered dalteparin or enoxaparin. Edoxaban can be regarded as a first choice to prevent venous thromboembolism after major orthopedic surgery.
Kawaji H, Ishii M, Tamaki Y, Sasaki K, Takagi M
Orthopedic Research and Reviews , 2012, DOI: http://dx.doi.org/10.2147/ORR.S39527
Abstract: Erratum Erratum (695) Total Article Views Authors: Kawaji H, Ishii M, Tamaki Y, Sasaki K, Takagi M Published Date November 2012 Volume 2012:4 Pages 103 - 104 DOI: http://dx.doi.org/10.2147/ORR.S39527 Received: 24 October 2012 Accepted: Published: 08 November 2012 Edoxaban for prevention of venous thromboembolism after major orthopedic surgery. Kawaji H, Ishii M, Tamaki Y, Sasaki K, Takagi M. Orthopedic Research and Reviews. 2012;4:53–64. On page 58, right-hand column, the second 17.0% (in the second line from the bottom) should be 6.9%. Read the original article. Post to: Cannotea Citeulike Del.icio.us Facebook LinkedIn Twitter Other articles by Dr Hiroyuki Kawaji Edoxaban for prevention of venous thromboembolism after major orthopedic surgery Readers of this article also read: Performance in L1 and L2 observed in Arabic-Hebrew bilingual aphasic following brain tumor: A case constitutes double dissociation Local anesthetic failure associated with inflammation: verification of the acidosis mechanism and the hypothetic participation of inflammatory peroxynitrite Imaging of peripheral vascular disease Alogliptin: a new addition to the class of DPP-4 inhibitors Morgellons disease: Analysis of a population with clinically confirmed microscopic subcutaneous fibers of unknown etiology Subset-directed antiviral treatment of 142 herpesvirus patients with chronic fatigue syndrome Health literacy and health seeking behavior among older men in a middle-income nation Epigenomics in cancer management Evaluation of in-vitro antibiotic susceptibility of different morphological forms of Borrelia burgdorferi Intercellular cancer collisions generate an ejected crystal comet tail effect with fractal interface embryoid body reassembly transformation
Regional CO2 flux estimates for 2009–2010 based on GOSAT and ground-based CO2 observations
S. Maksyutov,H. Takagi,V. K. Valsala,M. Saito
Atmospheric Chemistry and Physics Discussions , 2012, DOI: 10.5194/acpd-12-29235-2012
Abstract: We present the application of an integrated global carbon cycle modeling system to the estimation of monthly regional CO2 fluxes from the column-averaged dry air mole fractions of CO2 (XCO2) retrieved from the spectral observations made by the Greenhouse gases Observing SATellite (GOSAT). The regional flux estimates are to be publicly disseminated as the GOSAT Level 4 data product. The forward modeling components of the system include an atmospheric tracer transport model, an anthropogenic emissions inventory, a terrestrial biosphere exchange model, and an oceanic flux model. The atmospheric tracer transport was simulated using isentropic coordinates in the stratosphere and was tuned to reproduce the age of air. We used a fossil fuel emission inventory based on large point source data and observations of nighttime lights. The terrestrial biospheric model was optimized by fitting model parameters to match observed atmospheric CO2 seasonal cycle, net primary production data, and a biomass distribution map. The oceanic surface pCO2 distribution was estimated with a 4-D variational data assimilation system based on reanalyzed ocean currents. Monthly CO2 fluxes of 64 sub-continental regions, between June 2009 and May 2010, were estimated from the GOSAT FTS SWIR Level 2 XCO2 retrievals (ver. 02.00) gridded to 5° × 5° cells and averaged on a monthly basis and monthly-mean GLOBALVIEW-CO2 surface-based observations. Our result indicated that adding the GOSAT XCO2 retrievals to the GLOBALVIEW observations in the flux estimation would bring changes to fluxes of tropics and other remote regions where the surface-based observations are sparse. The uncertainty of these remote fluxes was reduced by as much as 60% through such addition. For many of these regions, optimized fluxes are brought closer to the prior fluxes by the addition of GOSAT data. For the most of the regions and seasons considered here, the estimated fluxes fell within the range of natural flux variability estimated with the component models.
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