Search Results - (Author, Cooperation:J. Takahashi)

2018-02-13

American Physical Society (APS)

0556-2821

1089-4918

Physics

Phenomenological aspects of field theory, general methods

2018-10-04

American Physical Society (APS)

0556-2813

1089-490X

Physics

Nuclear Structure

2018-05-16

BMJ Publishing

2044-6055

Medicine

Geriatric medicine, Open access, Public health

2015-05-09

American Association for the Advancement of Science (AAAS)

0036-8075

1095-9203

Biology

Chemistry and Pharmacology

Computer Science

Medicine

Natural Sciences in General

Physics

Animals ; Antigens, CD44/genetics ; Antigens, CD55/*genetics ; Cell Differentiation/genetics ; Cells, Cultured ; Erythrocytes/cytology/metabolism/*parasitology ; Genetic Testing ; Hematopoietic Stem Cells/cytology ; Host-Parasite Interactions/*genetics ; Humans ; Malaria, Falciparum/*genetics/*parasitology ; Plasmodium falciparum/*pathogenicity ; RNA, Small Interfering/genetics

2018-10-16

American Physical Society (APS)

0556-2813

1089-490X

Physics

Errata

2018-12-11

Genetics Society of America (GSA)

2160-1836

Biology

1089-7550

AIP Digital Archive

Physics

The shape effect of anisotropic-shaped microvoid defects in Czochralski-grown silicon wafers on the intensity of laser scattering has been investigated. The size and shape of the defects were examined by means of transmission electron microscopy. Octahedral voids in conventional (nitrogen-undoped) wafers showed an almost isotropic scattering property under the incident condition of a p-polarization beam. On the other hand, parallelepiped-plate-shaped voids in nitrogen-doped wafers showed an anisotropic scattering property on both p- and s-polarized components of scattered light, depending strongly on the incident laser direction. The measured results were explained not by scattering calculation using Born approximation but by calculation based on Rayleigh scattering. It was found that the s component is explained by an inclination of a dipole moment induced on a defect from the scattering plane. Furthermore, using numerical electromagnetic analysis it was shown that the asymmetric behavior of the s component on the parallelepiped-plate voids is ascribed to the parallelepiped shape effect. These results suggest that correction of the scattering intensity is necessary to evaluate the size and volume of anisotropic-shaped defects from the scattered intensity. © 2001 American Institute of Physics.

Electronic Resource

1077-3118

AIP Digital Archive

Physics

Irradiation by synchrotron radiation on SiO2 films induces continuous removal of this material at elevated temperatures. The photostimulated evaporation rate for a thermally grown SiO2 film increases steeply with temperature giving an activation energy of 0.7 eV. The experimental results indicate that photon-induced bond breaking assists decomposition and thermal desorption of the film. Applications to microfabrication of a line-and-space pattern and low-temperature cleaning of Si(100) surface are demonstrated.

Electronic Resource

1471-4159

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

The ontogeny of brain creatine kinase (CK) was studied during chick embryo development. The cytosolic activity increased 270% in 10 h from the 2nd to the 3rd days of incubation; this was followed by a plateau phase throughout development and at the end of incubation there appeared to be another increase of cytosolic and mitochondrial CK activities. Therefore, early embryonic chick brain CK is another‘constitutive’enzyme like the early embryonic chick heart CK since creatine has not been enzymatically detected in the embryo until day 4 of incubation. Insulin does not appear to stimulate the early increase of brain CK activity since the hormone is not present in the embryo until day 5 of incubation. It is likely that CK increase is associated with neuronal multiplication at early stages and possibly to neuronal maturation before hatching.

Electronic Resource

1089-7623

AIP Digital Archive

Physics

Electrical Engineering, Measurement and Control Technology

A high-performance beamline dedicated to vacuum-ultraviolet (VUV)-excited semiconductor processing has been constructed on the compact electron storage ring "Super ALIS". The first toroidal mirror accepts photons (emitted at a bending magnet) for 70 mrad in the horizontal direction, and the reflected parallel beam is focused onto the specimen surface by the second toroidal mirror. A brilliant VUV beam (with a photon density of 1.3×1016 s−1 mm−2 when the ring current is 300 mA) illuminates a circular field (10 mm in diameter) on the target surface. The eight 5-m-long differential pumping stages allow the reactant gas to be introduced into the reaction chamber at pressures up to 0.1 Torr. The processing is monitored in real time by using ultraviolet phase-modulated spectroscopic ellipsometry, and VUV-stimulated evaporation of SiO2 film has been demonstrated. © 1998 American Institute of Physics.

Electronic Resource

1077-3118

AIP Digital Archive

Physics

We report on the photostimulated evaporation of amorphous SiO2 and microcrystalline Si by synchrotron radiation in ultrahigh vacuum and in H2 ambients up to 0.08 Torr. For a-SiO2, the evaporation was slowed by introduction of H2, which suggests that the highly efficient decomposition process is hindered by hydrogen termination (-OH species formation). For μc-Si, the evaporation rate in ultrahigh vacuum was strongly affected by the degree of crystallization. The evaporation rate doubled with introduction of 0.08 Torr H2. Hydrogenation of the surface (SiHx species formation) slightly reduces the activation barrier for evaporation.

Electronic Resource

1365-2842

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

summary  Tooth preparation is an essential technique for dental treatment, but it is a skill not easily learned by a dental student. To facilitate this leaning process, a new tooth preparation support system with a parallel link mechanism was developed. This study reports the educational efficiency of this system for dental students. Dental students with no experience in clinical practice were selected and divided into two groups; one trained with this support system; and the other, with freehand preparation. They prepared axial walls in right maxillary second premolars and molars mounted in a phantom manikin with an air-turbine handpiece. Convergence angles of the axial walls and parallelisms between axes of prepared teeth were evaluated. Training with the support system led to significantly smaller convergence angles and parallelisms as compared with freehand preparation training. With the freehand preparation after training, the convergence angles and parallelisms became smaller in the group trained with the support system than those trained with freehand. The above findings suggest that training in tooth preparation utilizing the newly developed support system can be one of practical programs that are useful for dental students to achieve greater competency in tooth preparation.

Electronic Resource

1365-2842

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

To accomplish computerized 3D morphological analyses of maxillary and mandibular casts with malocclusions on the same co-ordinate system, a new reference co-ordinate located on soft tissue has been proposed consisting of the top of maxillary bilateral tubercles and incisive papilla on the maxillary cast. To test the validity of this co-ordinate system, the angles of the occlusal plane in this system were examined on 10 subjects with normal occlusion. In addition, to analyse maxillary and mandibular casts on the same co-ordinate system, a bite block was made under the intercuspal position. The maxillary cast was measured by 3D measuring system, then, the bite block was placed on maxillary casts, and measured similarly. To examine the position reproducibility of this method, 3D co-ordinates of the apex of the buccal cusp of the mandibular pre-molar in five bite blocks were determined. The angles formed of the occlusal plane were 1·3 ± 1·3° and 0·2 ± 1·1° on the sagittal and frontal base plane, respectively. This co-ordinate system had enough stability to replace the occlusal plane. By the measurement of bite blocks, the co-ordinates of the mandibular cusp tips were determined within the deviation of 0·2 mm.

Electronic Resource

1365-2842

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Titanium (Ti) and Ag–Pd–Cu–Au alloy were examined for their polishing behaviour by conducting manually controlled polishing tests using five dental abrasives [carborundum point (CR) and silicone points (R1 and R2)] driven by a high torque micromotor with rotational speeds ranging from 2000 to 15 000 r.p.m. Polishing of Ti resulted in less volume of removal upon polishing, a rougher surface and larger loss of abrasives, compared with polishing of Ag–Pd–Cu–Au alloy. Polishing of Ti with a rotational speed of 15 000 r.p.m. led to the largest volume of removal upon polishing, whilst that of 10 000 r.p.m. produced the optimal volume for Ag–Pd–Cu–Au alloy. It was concluded that Ti was much more difficult to polish, requiring special care (e.g. frequent exchange of abrasives). Development of new abrasives for polishing Ti is required.

Electronic Resource

1365-2842

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Two commercial visible-light (VL)-cured composite resins were examined for their optical properties by diffuse reflectance measurements in VL spectrum and Kubelka–Munk's theory. Cured Silux Plus® displayed diffuse reflectance similar to that of cured Z100®, although uncured Silux Plus® showed diffuse reflectance less than that of uncured Z100®. By Kubelka–Munk's analyses, two optical constants of the composites at eight wavelengths such as absorption and scattering coefficients were calculated using the difference in diffuse reflectance of the composites backed between white and black standards. Upon curing, the two optical constants of the composites significantly altered especially in the shorter wavelengths. By lowering the wavelength, two optical constants of the composites tended to increase, giving rise to less light reflection and transmission. The theoretical optical transmittance of the composites was expressed in terms of hyperbolic functions of thickness of the composites at eight wavelengths in VL, dependent upon the two optical constants. The actual optical transmittance of 1 mm composites were fairly comparative with the theoretical values at 1 mm. The depth of cure of the two composites matched well with the thickness of the uncured composites which yielded the minimum theoretical optical transmittance in the wavelength region of 400–500 nm.

Electronic Resource

1365-2842

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

summary  The morphologic characteristics of the dentition with maxillary prognathism and reversed occlusion were examined by a computer-assisted dental cast analysing system. Dental casts with normal occlusion, maxillary prognathism and reversed occlusion were selected and measured by a 3D shape measuring system. The dental arches and anteroposterior occlusal curves were approximated numerically by the polynomial expression with a fourth order and second order coefficients, respectively. The coefficients were analysed statistically. Maxillary dental arches with mandibular prognathism showed a more acuminate shape (V-shape) with a significant larger second order coefficient, while arches with reversed occlusion showed more angulate shapes (U-shape) with significantly smaller second order coefficients compared with arches with normal occlusions. However, a notable difference in the shape of the mandibular dental arches was not observed. The mandibular dental arches with maxillary prognathism were positioned backward relative to maxillary dental arches, while the arches with reversed occlusion were positioned forward. The anteroposterior occlusal curves with maxillary prognathism showed larger curvatures in maxilla and mandible, while the curves with reversed occlusion showed smaller curvatures in mandible comparing with the curves with normal occlusion. These results suggest that the present method could offer a useful and objective examination technique for the diagnosis of malocclusion.

Electronic Resource

1365-2842

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

summary The purpose of this investigation was to examine by reverse-transcriptase polymerase chain reaction analysis the osteogenic differentiation of twice-passaged Sprague–Dawley rat bone marrow stromal cells in type I collagen gel cultured for 3 weeks. Two culture media were used here, namely Dulbecco's modified Eagle (DME) medium supplemented with vitamin C [Dex (–)] and those with vitamin C, dexamethasone and β-glycerophosphate [Dex (+)]. Culture with Dex (–) medium in collagen gel for 3 weeks brought about the well-developed cell network and middle-stage osteogenic phenotype expression characterized by mRNA for alkaline phosphatase, osteonectin and osteopontin while those for bone sialo protein and osteocalcin were not detected. On the contrary, culture with Dex (+) medium in collagen gel for 3 weeks lead to necrosis of the cells. These results indicate that culture in collagen gel with Dex (–) DME medium containing vitamin C was useful for three-dimensional culture and middle-stage osteogenic differentiation of twice-passaged bone marrow stromal cells.This study might contribute to tissue engineering therapy to fix bone and periodontal defects in the future.

Electronic Resource

1365-2842

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Cytotoxicity of Ni ions were examined using C3H mouse derived 10T1/2 fibroblast cells. It became evident that Ni ions had dose-dependent cytotoxicity. The cell number incubated in DME medium containing 0·04 mm/L Ni ion for 6 days was reduced to half that in control DME medium without Ni. The cell totally disappeared in DME medium containing 2 mm/L Ni ion. The dissolution of Ni ions from Ni-containing metallic restorations must be lower than these concentration levels so that oral tissues might not be damaged. No neoplastic transformation was found on all cells examined.

Electronic Resource

1365-2842

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

The aim of this study was to reveal the effect of metal wire on the adaptation of the denture reinforced with it. Forty maxillary dentures were made with two polymerization systems (DS system and SR-Ivocap system). The dentures were divided into two groups: (1) the unreinforced dentures (control) and (2) the dentures reinforced with metal wire 1·0 mm in diameter. Discrepancies between the denture base and the stone cast were measured at five points immediately after polymerization and after a 30-day immersion in water. The data were analysed using a two-way or one-way ANOVA test. Dentures reinforced with metal wire exhibited significantly lower adaptation to the stone cast than the unreinforced ones for each polymerization system. Immersion in water did not affect the adaptation of dentures reinforced with metal wire for each polymerization. Unreinforced dentures made by the DS system had significantly smaller discrepancies compared with the dentures processed with the SR-Ivocap system. The adaptation of the dentures reinforced with metal wire decreased in comparison with the unreinforced ones regardless of the polymerization method. This should be considered when metal wire is used clinically as reinforcement.

Electronic Resource

1365-2842

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

The purpose of this study was to investigate the influence of bruxism on the stomatognathic system. A new device for measuring nocturnal mandibular movements was developed using a PIN photodiode sensor, integrated with polysomnography including electromyography (EMG), electroencephalography (EEG) and electro oculography (EOG). One bruxing event was defined depending upon EMG activities above 5% maximum voluntary contraction (MVC), and mandibular movement for each event was classified into three patterns (clenching, grinding and mix). Three subjects were selected for this study. Two of these reported a bruxing habit and one subject had some symptoms of temporomandibular dysfunction (TMD). Mandibular movement was analysed for these subjects. Frequency and duration of the bruxism events were 4·5–10·9 and 47·8–174·9 s h–1 respectively. Clenching type bruxism was most frequently observed for all three subjects and EMG activities during clenching were stronger than grinding.

Electronic Resource