Full Self-Consistent Projection Operator Approach to Nonlocal Excitations in Solids (10 pages)

Kakehashi, Y.,Nakamura, T.,Fulde, P. PHYSICAL SOC JAPAN 2009 Journal of the Physical Society of Japan Vol.78 No.12

Nonlocal Excitations and 1/8 Singularity in Cuprates

Yoshiro Kakehashi,M. Atiqur R. Patoary,Sumal Chandra 한국물리학회 2013 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.62 No.12

Momentum-dependent excitation spectra of the two-dimensional Hubbard model on a squarelattice have been investigated at zero temperature on the basis of the full self-consistent projectionoperator method in order to clarify nonlocal effects of electron correlations on the spectra. Intersiteantiferromagnetic correlations are found to cause shadow bands and enhance the Mott-Hubbardsplittings near the half-filling. Furthermore, nonlocal excitations are shown to move the criticaldoping concentration δh , at which the singular quasiparticle peak is located just on the Fermi level,from δh = 0.153 (the single-site value) to δh = 0.123. The latter suggests the occurrence of aninstability such as the stripe at δh = 1/8.

Preventive Effects of Spirogyra neglecta and a Polysaccharide Extract against Dextran Sodium Sulfate Induced Colitis in Mice

Taya, Sirinya,Kakehashi, Anna,Wongpoomchai, Rawiwan,Gi, Min,Ishii, Naomi,Wanibuchi, Hideki Asian Pacific Journal of Cancer Prevention 2016 Asian Pacific journal of cancer prevention Vol.17 No.4

Ulcerative colitis (UC) results from colonic epithelial barrier defects and impaired mucosal immune responses. In this study, we aimed to investigate the modifying effects of a Spirogyra neglecta extract (SNE), a polysaccharide extract (PE) and a chloroform fraction (CF) on dextran sodium sulfate (DSS)-induced colitis in mice and to determine the mechanisms. To induce colitis, ICR mice received 3% DSS in their drinking water for 7 days. Seven days preceding the DSS treatment, oral administration of SNE, PE and CF at doses of 50, 25 and 0.25 mg/kg body weight (low dose), 200, 100 and 1 mg/kg body weight (high dose) and vehicle was started and continued for 14 days. Histologic findings showed that DSS-induced damage of colonic epithelial structure and inflammation was attenuated in mice pre-treated with SNE, PE and CF. Furthermore, SNE and PE significantly protected colonic epithelial cells from DSS-induced cell cycle arrest, while SNE, PE and CF significantly diminished apoptosis. Proteome analysis demonstrated that SNE and PE might ameliorate DSS-induced colitis by inducing antioxidant enzymes, restoring impaired mitochondria function, and regulating inflammatory cytokines, proliferation and apoptosis. These results suggest that SNE and PE could prevent DSS-induced colitis in ICR mice by protection against and/or aiding recovery from damage to the colonic epithelium, reducing ROS and maintaining normal mitochondrial function and apoptosis.

Factors Affecting Breast Cancer Screening Behavior in Japan - Assessment using the Health Belief Model and Conjoint Analysis

Tsunematsu, Miwako,Kawasaki, Hiromi,Masuoka, Yuko,Kakehashi, Masayuki Asian Pacific Journal of Cancer Prevention 2013 Asian Pacific journal of cancer prevention Vol.14 No.10

Background: Japanese women in their 40s or older have been encouraged to attend breast cancer screening. However, the breast cancer screening rate in Japan is not as high as in Europe and the United States. The aim of this study was to identify psychological and personal characteristics of women concerning their participation in breast cancer screening using the Health Belief Model (HBM). In addition, the attributes of screening more easily accepted by participants were analyzed by conjoint analysis. Materials and Methods: In this cross sectional study of 3,200 age 20-69 women, data were collected by an anonymous questionnaire. Questions were based on HBM and personal characteristics, and included attitudes on hypothetical screening attributes. Data of women aged 40-69 were analyzed by logistic regression and conjoint analysis to clarify the factors affecting their participation in breast cancer screening. Results: Among responses collected from 1,280 women of age 20-69, the replies of 993 women of age 40-69 were used in the analysis. Regarding the psychological characteristics based on HBM, the odds ratios were significantly higher in "importance of cancer screening" (95%CI: 1.21-2.47) and "benefits of cancer screening" (95%CI: 1.09-2.49), whereas the odds ratio was significantly lower in "barriers to participation before cancer screening" (95%CI: 0.27-0.51). Conjoint analysis revealed that the respondents, overall, preferred screening to be low cost and by female staff members. Furthermore, it was also clarified that attributes of screening dominant in decision-making were influenced by the employment status and the type of medical insurance of the women. Conclusions: In order to increase participation in breast cancer screening, it is necessary to disseminate accurate knowledge on cancer screening and to reduce barriers to participation. In addition, the attributes of screening more easily accepted were inexpensive, provided by female staff, executed in a hospital and finished in a short time.

Quantitative Approaches to Assess Key Carcinogenic Events of Genotoxic Carcinogens

Shoji Fukushima,Min Gi,Masaki Fujioka,Anna Kakehashi,Hideki Wanibuchi,Michiharu Matsumoto 한국독성학회 2018 Toxicological Research Vol.34 No.4

Chemical carcinogenesis is a multistep process. Genotoxic carcinogens, which are DNA-reactive, induce DNA adduct formation and genetic alterations in target cells, thereby generating mutated cells (initiation). Subsequently, preneoplastic lesions appear through clonal proliferation of the mutated cells and transform into tumors (promotion and progression). Many factors may influence these processes in a dose-dependent manner. Therefore, quantitative analysis plays an important role in studies on the carcinogenic threshold of genotoxic carcinogens. Herein, we present data on the relationship between key carcinogenic events and their deriving point of departure (PoD). Their PoDs were also compared to those of the carcinogenesis pathway. In an experiment, the liver of rats exposed to 2-amino-3,8-dimethylimidazo-(4,5-f)quinoxaline (MeIQx) was examined to determine the formation of MeIQx-DNA adducts, generation of mutations at LacI transgene, and induction of preneoplastic glutathione S-transferase placental form (GST-P)-positive foci and tumors (benign and malignant). The PoDs of the above key events in the carcinogenicity of MeIQx were increased as the carcinogenesis advanced; however, these PoDs were lower than those of tumor induction. Thus, the order of key events during tumor induction in the liver was as follows: formation of DNA adducts ≪ Mutations ≪ GST-positive foci (preneoplasia) ≪ Tumor (adenoma and carcinoma). We also obtained similar data on the genotoxic and carcinogenic PoDs of other hepatocarcinogens, such as 2-amino-3,8-dimethylimidazo(4,5-f)quinoline. These results contribute to elucidating the existence of a genotoxic and carcinogenic threshold.

First-principles Molecular-dynamics Study on the Magnetic Structure of Mn3Pt

Takashi Uchida,Nobuyuki Kimura,Yoshiro Kakehashi 한국물리학회 2013 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.62 No.12

A first-principles molecular-dynamics (MD) approach to the magnetic structure of itinerant magnetsis proposed and applied to the magnetic structure of Mn3Pt, which is a three-dimensionalfrustrated magnet with an octahedral configuration of Mn local magnetic moments and exhibitstwo ordered phases at temperatures below the N´eel temperature. The theory is formulated byincorporating the first-principles tight-binding linear muffin-tin orbital Hamiltonian into the MDapproach for itinerant magnets on the basis of the functional integral method and the isothermal MDtechnique, and determines automatically the magnetic structures of itinerant magnets at finite temperatures. Numerical results at 25 K for a 3×3×3 fcc unit cell reveal a triangular-type noncollinearmagnetic structure, which is consistent with the experimentally-proposed magnetic structure of thelow-temperature-ordered phase (D-phase). With increasing temperature in the D-phase region, theamplitude and the thermal average of Mn local moments were found to decrease gradually. The stabilityof the experimentally-suggested magnetic structure of the higher-temperature-ordered phase(F-phase) in Mn3Pt is discussed on the basis of the nonmagnetic ground-state density of states,which shows a sharp sub-peak consisting of the Eg states of Mn at the Fermi energy.

Effectiveness of Cervical Cancer Screening Based on a Mathematical Screening Model using data from the Hiroshima Prefecture Cancer Registry

Ito, Katsura,Tsunematsu, Miwako,Satoh, Kenichi,Kakehashi, Masayuki,Nagata, Yasushi Asian Pacific Journal of Cancer Prevention 2013 Asian Pacific journal of cancer prevention Vol.14 No.8

Here we assessed the effectiveness of cervical cancer screening using data from the Hiroshima Prefecture Cancer Registry regarding patient age at the start of screening and differences in screening intervals. A screening model was created to calculate the health status in relation to prognosis following cervical cancer screening and its influence on life expectancy. Epidemiological data on the mortality rate of cervical cancer by age groups and mortality rates from the Hiroshima Prefecture Cancer Registry were used for the model projections. Our results showed that life expectancy when screening rate was 100% compared with 0% was extended by approximately 1 month. Furthermore, when the incidence of cervical cancer was 0% compared with the screening rate was 100%, life expectancy was extended by a maximum of 3 months. Moreover, among individuals affected by cervical c ancer, a difference of 13 years in life expectancy was calculated between screened and unscreened groups.

Maximum-Efficiency Tracking Scheme for Piezoelectric-Transformer Inverter with Dimming Control

Satoshi Nakashima,Hiroshi Ogasawara,Hidenori Kakehashi,Tamotsu Ninomiya 전력전자학회 2001 ICPE(ISPE)논문집 Vol.2001 No.10

This paper provides a solution for the problem of efficiency decrease caused by load variation. A novel control scheme of tracking the PT's operation frequency for the maximum efficiency is proposed. As a result, a high efficiency over 80% has been achieved even under the output-current decrease down to 10% of the full load current.

IMPROVEMENT IN HIGH FREQUENCY MAGNETIC PROPERTIES OF THIN AMORPHOUS RIBBONS BY SURFACE OXIDATION

K.Ooae,H.Fukunaga,H.Kakehashi,H.Ogasawara 한국자기학회 1995 韓國磁氣學會誌 Vol.5 No.5

The effects of surface oxidation on magnetic properties were investigated at high frequencies (10k-10㎒) for 7-18㎛ thick Co_(70)Fe_5Si_(15)B_(10) amorphous ribbons with controlled domain structure. Oxidation was accelerated by acid-treatment or anodic oxidation treatment, and the insulation layers were prepared on the surfaces of the ribbons. The acid-treatment was effective in improving permeability and magnetic loss. Although the anodic oxidation treatment was effective in both making oxide layer and thinning, the magnetic properties were not improved compared with the case of the acid-treatment.

MAGNETIC PROPERTIES OF FERRITE CORES UNDER DC - BIASED FIELD

H. Fukunaga,S. Masumoto,Y. Ohta,H. Kakehashi,H. Ogasawara 한국자기학회 1995 韓國磁氣學會誌 Vol.5 No.5

Ferrite cores are often magnetized under DC-biased field because they have been intensively used in electronic circuits such as an inverter circuit and a switching regulator circuit. Thus we investigated the effects of DC-biased field on magnetic properties in the frequency range of DC-100㎑ for two kinds of ferrite cores, TDK PC38 and TDK H₃S, which have different shapes of B-H loop from each other. The magnetic loss per cycle, W/f, in the H₃S core decreased with increasing the strength of DC-biased field, although W/f in the PC38 core increased monotonically with DC-biased field. The observed decreasing tendency differs from the previous result for Si-Fe and ferrite cores, and can be attributed to decrease in eddy current loss as well as that in hysteresis loss.