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Search Results: 1 - 10 of 906 matches for " Yoshitaka Ishihara "
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Flat connected finite quandles
Yoshitaka Ishihara,Hiroshi Tamaru
Mathematics , 2015,
Abstract: Quandles can be regarded as generalizations of symmetric spaces. In the study of symmetric spaces, the notion of flatness plays an important role. In this paper, we define the notion of flat quandles, by referring to the theory of Riemannian symmetric spaces, and classify flat connected finite quandles.
Comparison of Pine Needles and Mosses as Bio-Indicators for Polycyclic Aromatic Hydrocarbons  [PDF]
Yoshitaka Oishi
Journal of Environmental Protection (JEP) , 2013, DOI: 10.4236/jep.2013.48A1013

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous environmental contaminants known to be hazardous to human health. Pine needles and mosses are useful bio-indicators for assessing PAH pollutions; however, the differences in their PAH uptake mechanisms have not been sufficiently discussed. In this study, the properties of pine needles and mosses as bio-indicators of PAHs were investigated on the basis of differences in their PAH profiles. Five sets each of pine needle and moss samples were collected from circular sampling plots and analyzed for 16 PAHs. A comparison of PAH profiles revealed that the proportion of lower molecular weight PAHs (2 - 3 aromatic rings; LMW PAHs) was significantly higher in pine needles (78.5% ± 4.8%) than in mosses (35.4% ± 6.8%). In contrast, the proportion of higher molecular weight PAHs (5 - 6 aromatic rings; HMW PAHs) was lower in pine needles (4.3% ± 2.9%) than in mosses (25.1% ± 3.3%). Further, the combination of PAH isomer ratios showed that PAH sources between pine needles and mosses were not the same. These differences were explained by their uptake mechanisms and partly by the absorption of PAHs from soil particles by mosses. These findings indicate that pine needles are useful for assessing airborne LMW PAH pollution, whereas mosses can be integrated indicators for assessing complex HMW PAH pollution of the atmospheric and soil environments. On the basis of these properties, the usefulness of these bio-indicators should also be evaluated according to the objective of the assessment and the areas where they are applied.

Regional Mapping of Vertical Hydraulic Gradient Using Uncertain Well Data: A Case Study of the Toyohira River Alluvial Fan, Japan  [PDF]
Yoshitaka Sakata, Ryuji Ikeda
Journal of Water Resource and Protection (JWARP) , 2013, DOI: 10.4236/jwarp.2013.58083

Vertical hydraulic gradient (VHG) provides detailed information on 3D groundwater flows in alluvial fans, but its regional mapping is complicated by a lack of piezometer nests and uncertainty in conventional well data. Especially, determining representative depth of well screen in each well is problematic. Here, a VHG map of the Toyohira River alluvial fan, Sapporo, Japan, is constructed based on groundwater table elevation (GTE), using available well-data of various screen lengths and depths. The water-level data after 1988, when subway constructions are mostly completed in the city, are divided into those of shallow wells (≤20 m deep), and those of deep wells (>20 m deep). First, the GTE map is generated by kriging interpolation of shallow well data with topographic drift. Next, the individual VHG value of each deep well is calculated using its top, middle, and bottom elevations of the screen depths, respectively. The VHG maps of three cases are then obtained using neighborhood kriging. The VHG map of the bottom screen depths has proven most valid by cross-validation. The VHG map better visualizes that downward flows of groundwater are predominant over the fan. Positive area of VHG is mostly vanished around the fan-toe, indicating urbanization effect such as artificial withdrawals. A negative peak of VHG corresponds to recharge area, and is seen along the distinct losing section in the river. The negative peak also expands upstream to the fan-apex where a basement is suddenly depressed.

Effects of Improving Public Services for Tourism Developments in Islands: The Case of Remote Islands in Nagasaki, Japan  [PDF]
Tadahiro Okuyama, Hayato Ishihara
Open Journal of Social Sciences (JSS) , 2015, DOI: 10.4236/jss.2015.36018
Abstract: Growths of numbers of tourists who stay long-term in tourism sites are an important policy for local governments in islands due to their locations that are far from urban areas. However, many tourists hesitate to stay long-term in islands owing to not only the expensive travel costs but also the lack of public services in islands. The purpose of this study is to examine effects of improving public services in islands for tourists’ willingness to pays (WTPs) and non-tourists’ attitudes for long-term stays. Data on tourism activity for islands, Nagasaki, Japan were used. Respondents were asked about their WTPs for long-term stays and their needs for public services of islands; reductions of costs for rent or purchasing houses for long-term stays and travel costs, easy to take a vacation, to enhance medical services, educational services and job search services. The logit model was used for estimations. Median and mean values of WTPs (per year) were calculated JPY 151,629 (USD 1184) and JPY 242,110 (USD 3008). Positive effects on five public services (without travel costs) were confirmed. For example, the median values of WTPs were increased to JPY 478,369 (USD 5943) when the medical services were improved, and JPY 1,484,704 (USD 18,446) when all public services were improved. The results showed that improvement of public services have the effect 1) to improve tourists’ benefits and 2) to change many non-tourists’ attitudes from the rejection of staying long term in islands to the acceptance. Thus, results indicate that it would be better for central and/or local governments in islands to enhance islands’ public services.
Characterization of a novel variant of the second domain of bikunin with increased leukocyte elastase inhibitory activity  [PDF]
Masaki Nakamura, Takashi Takeuchi, Yoshitaka Maeda, Yoshitaka Hosaka, Shoji Furusako
Journal of Biophysical Chemistry (JBPC) , 2012, DOI: 10.4236/jbpc.2012.32015
Abstract: The light chain of inter-α inhibitor, also known as bikunin or urinary trypsin inhibitor, is composed of two tandemly arranged Kunitz-type protease inhibitor domains. The second domain of bikunin has factor Xa inhibitory activity which previously was enhanced by mutating two amino acids, glutamine 19 and tyrosine 46 to lysine and aspartate, respectively. In this study, we tried to potentiate its inhibitory activity against leukocyte elastase. A molecular docking model of the second domain of bikunin with leukocyte elastase revealed that P5 arginine 11 was a candidate residue for a third substitution. We generated six triple point mutants using site-directed mutagenesis, compared their leukocyte elastase-inhibitory activities, and selected the most potent variant with arginine 11 substituted to serine. The IC50 values for factor XIa, factor Xa, and leukocyte elastase were 182, 302, and 273 nM, respectively. Moreover, this triple point mutant prolonged the activated partial thromboplastin time and moderately reduced leukocyte elastase-induced endothelial injury. Additionally, favorable conformations created by these mutations were speculated using the structure of the Kunitz protease inhibitor domain of protease nexin 2 complexed with factor XIa as a reference. We discovered a novel triple point mutant of the second domain of bikunin that has potent inhibitory activities against factor XIa, factor Xa, and leukocyte elastase. This variant exhibited anticoagulant activity in plasma and suppressed endothelial cell injury.
Temporal Prediction of Aircraft Loss-of-Control: A Dynamic Optimization Approach  [PDF]
Chaitanya Poolla, Abraham K. Ishihara
Intelligent Control and Automation (ICA) , 2015, DOI: 10.4236/ica.2015.64023
Abstract: Loss of Control (LOC) is the primary factor responsible for the majority of fatal air accidents during past decade. LOC is characterized by the pilot’s inability to control the aircraft and is typically associated with unpredictable behavior, potentially leading to loss of the aircraft and life. In this work, the minimum time dynamic optimization problem to LOC is treated using Pontryagin’s Maximum Principle (PMP). The resulting two point boundary value problem is solved using stochastic shooting point methods via a differential evolution scheme (DE). The minimum time until LOC metric is computed for corresponding spatial control limits. Simulations are performed using a linearized longitudinal aircraft model to illustrate the concept.
Transformation of QTL genotypic effects to allelic effects
Yoshitaka Nagamine
Genetics Selection Evolution , 2005, DOI: 10.1186/1297-9686-37-6-579
Abstract: (To access the full article, please see PDF)
Mathematical morphology-based approach to the enhancement of morphological features in medical images
Yoshitaka Kimori
Journal of Clinical Bioinformatics , 2011, DOI: 10.1186/2043-9113-1-33
Abstract: The proposed method involves two steps: (1) selective extraction of target features by mathematical morphology and (2) enhancement of the extracted features by two contrast modification techniques.The goal of the proposed method is to enable enhancement of fine morphological features of a lesion region with high suppression of surrounding tissues. The effectiveness of the method was evaluated in quantitative terms of the contrast improvement ratio. The results clearly show that the method outperforms five conventional contrast enhancement methods. The effectiveness and usefulness of the proposed method were further demonstrated by application to three types of medical images: a mammographic image, a chest radiographic image, and a retinal image.The proposed method enables specific extraction and enhancement of mass lesions, which is essential for clinical diagnosis based on medical image analysis. Thus, the method can be expected to achieve automatic recognition of lesion location and quantitative analysis of legion morphology.In contemporary medical practices, image-based diagnosis is a crucial component of disease evaluation. Medical images of various modalities such as X-ray, mammography, computed tomography, magnetic resonance imaging, color fundus imaging, and ultrasound contain important information for clinical diagnosis.Computer-aided detection (CADe) and/or diagnosis (CADx) [1-4] is used to assist physicians in interpreting image-based information accurately and efficiently. CADe is the system of identifying the location of potential lesions within a medical image. CADx is the system of evaluating or characterizing the lesions, which were initially located by CADe. In general, both systems are referred to collectively as CAD. It includes the following fundamental components: image processing, image segmentation, classification, registration, modeling, visualization, etc. The schematic diagram of typical CAD system is shown in Figure 1.Of these, image proces
Espectros eletr?nicos de alguns complexos de geometria octaédrica de Ni2+: uma introdu??o prática à teoria do campo cristalino no curso de gradua??o
Gushikem, Yoshitaka;
Química Nova , 2005, DOI: 10.1590/S0100-40422005000100027
Abstract: the experiment introduces the undergraduate students to the crystal field theory. the electronic spectra of the octahedral complexes of [ni(l)n]2+ (l = h2o, dmso, nh3 and en) obtained in the experiment are used to calculate 10dq and b parameters. the experiment shows how the parameters can be calculated and correlated with the nature of the ligands and the field intensities produced.
Relating $e^+e^-$ annihilation to high energy scattering at weak and strong coupling
Hatta, Yoshitaka
High Energy Physics - Phenomenology , 2008, DOI: 10.1088/1126-6708/2008/11/057
Abstract: We explore the correspondence between the final state in e^+e^- annihilation and the small-x hadronic wavefunction in the transverse plane both in weakly coupled QCD and strongly coupled N=4 SYM. At strong coupling, the virtual and static photon produced in e^+e^- annihilation can be treated as a shock wave propagating in AdS space leaving spherical energy and charge distributions on the boundary. This is shown to be mathematically identical to the computation of energy and charge distributions in the transverse plane generated by a high energy color singlet state. At weak coupling, the correspondence is useful in studying interjet observables. By performing the stereographic projection to the BFKL equation, we construct an exact solution to the evolution equation derived by Marchesini and Mueller, and find the angular distribution of small-x gluons in the interjet region. Finally we argue that the correspondence holds also for the energy correlation functions.
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