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Doping technique, i.e., incorporation of dilute amount of additional element, has been widely applied to add new functions for various kinds of materials. Appropriate doping can change their specific properties significantly, e.g., electric, magnetic, optical, mechanical and chemical properties, etc. It is, of course, fundamental to know the crystal and electronic structures of such materials. In addition to such studies, it is mandatory to investigate the local environment of dopants on an atomic scale to understand the mechanism of appearance of new properties by doping and to design new materials with desired properties by such doping technique. Although crystal structure analysis has been widely carried out by the X-ray diffraction (XRD) technique, it is very difficult to determine the local environment of dilute dopants only by XRD. There are some experimental methods to investigate such local environment of dilute dopants. Among these methods, X-ray absorption near-edge structure (XANES) analysis by using the synchrotron radiations is one of the most powerful methods, which enables us to determine the local environment of dopant at an ultra-dilute concentration level, such as atomic ppm level of concentration [1]. We have reported quantitative analysis of XANES from many different kinds of functional materials [2, 3] with the aid of the first-principles calculations within the density functional theory (DFT). The fingerprint type analysis is widely accepted for various kinds of analysis, but such strategy requires reliable fingerprints to be compared with the newly observed result. However, in the case of local environment analysis by XANES, observed XANES spectrum from dopant often shows different profile from any of the standard ones, which yields that fingerprint type of analysis does not work for the local environment analysis. From such reason, theoretical fingerprint prepared by using first-principles calculation plays a key role for the local environment analysis of dopant by XANES. In the current study, we focus upon local environment analysis of dilute dopants in phosphor materials. After introduction of our analytical method of the local environment analysis with XANES and first-principles calculation, several results on such dopants, rare-earth ions and 3d-transition metal ions in perovskite structured oxides, will be shown. As an example, Ga XANES analysis of Ga doped SrTiO3:Pr, in which Ga codoping enhances red luminescence of Pr doped SrTiO3 [3], is shown in Fig. 1. References [1] I. Tanaka et al., Nature Materials 2 (2003) 541. [2] I. Tanaka et al., J Am. Cer. Soc. 88 (2005) 2013. [3] T. Yamamoto et al., J. Phys.: Condens. Matter 21 (2009) 104211. Figure 1

We discuss here a self-similar structure of an aggregate of crystals or noncrystalline grains. In particular, the sufficient condition for a polycrystal to be filled with an arbitrary finite number of self-similar crystals is investigated using a topological concept.

Diffusion-weighted imaging (DWI) has been used to characterize not only the brain, but also the breast by implementation of faster imaging techniques and higher magnetic field strengths. However, the optimum b value, which is an important scan parameter for DW images contrast on 3 T breast magnetic resonance imaging (MRI) has not been established. The purpose of this study was to investigate the influence of different b value combinations on the image contrast and apparent diffusion coefficient (ADC) in patients with known invasive carcinoma, ductal carcinoma in situ (DCIS), and normal mammary gland in breast DWI. The analysis procedure consisted of the following methods: 1) T(2) correction of DW images with echo-planar imaging (EPI) T(2)-weighted images; 2) contrast measurement between normal mammary gland and tumor tissues; 3) ADC measurement of normal mammary gland and tumor tissues. In many cases, the highest contrast between normal mammary gland and tumor tissues was obtained using a b value of 1500 s/mm(2). Our results indicated that when only one b value is used, the b value in which signal intensities of normal mammary gland decreases down to noise level, and the contrast between normal mammary gland and tumor tissues is recommended. ADC value decreased with increasing b value. Therefore, when determining the ADC threshold level, it is important to perform the evaluation using ADC values calculated from DW images with the same b value in clinical studies.

Organ doses are useful for estimating radiation doses to patients. However, it is impossible to determine specific organ doses for each patient. The aim of this study was to examine the relationship between specific organ doses and volumetric CT dose indices (CTDIvols) in multidetector CT studies to estimate specific organ doses in each patient. Radiophotoluminescent glass dosimeters were placed at locations corresponding to specific organs of an anthropomorphic phantom. Thereafter, the phantoms were examined with respect to various imaging ranges and protocols, including cranial, thoracic and abdominal acquisitions using a 64-section multidetector CT. Concurrently, we recorded the mean CTDIvol for each acquisition range. In the cranial acquisition, the displayed mean CTDIvol was 69.0mGy, and the absorbed doses for brain and intra-ocular lenses were 57.2±2.6 and 57.1±3.0mGy, respectively. In the thoracic acquisition, the displayed mean CTDIvol was 16.3mGy, and the absorbed doses for breast and lung were 19.1±6.4 and 31.7±2.2mGy, respectively. In the abdominal acquisition, the displayed mean CTDIvol was 21.6mGy, and the absorbed doses for stomach and colon were 28.2±6.1 and 28.0±8.6mGy, respectively. The displayed mean CTDIvols overestimated the specific organ doses in the cranial acquisition and underestimated them in the thoracic and abdominal acquisitions. However, the approximate specific organ doses may be estimated by multiplying the displayed mean CTDIvols with a conversion factor for each organ.

Three types of functional ceramic materials, (1) dilute magnetic semiconductor, (2) phosphor and (3) electrolyte of a solid fuel cell, are fabricated by the conventional solid state reaction method. Local environments of dopants in these ceramic materials here synthesized are systematically investigated by using the x-ray absorption near-edge structure (XANES) with the aid of first-principles calculations. Our present analytical method by combined use of XANES and first principles calculations has successfully explained the local environment of dopants in the above ceramic materials.

The present study measures entrance surface doses of radiation administered to patients during various fluoroscopic procedures using a dose-area product meter as well as the duration of each procedure. A conversion factor for entrance skin dose to patients was calculated. The average dose to patient during the insertion of intravenous hyperalimentation was 10.2 (maximum, 74.0) mGy, during a barium meal, 58.4 (maximum, 184.0) mGy, for endoscopic retrograde cholangio-pancreatography (ERCP), 97.3 (maximum, 376.0) mGy and for a barium enema, 86.1 (maximum, 271.0) mGy. Doses tended to increase in the abdominal domain and when patients undergo not only diagnostic evaluation but also treatment requiring procedures such as drainage. The management of radiation doses determined using a dose-area product meter is very important and that of individual patients is enabled using the Radiation Information System (RIS).

The classical three-body problem of the helium atom is numerically studied. For most initial conditions, orbits show chaotic transients until one of the electrons always escapes to infinity, leading to autoionization. For the remaining parts of initial conditions, several types of stable quasiperiodic motions (on tori) are found, which have a finite measure in the phase space. This discovery enables us to treat semiclassically a strongly correlated electronic system.

In interventional radiology (IVR) procedures, automatic brightness control (ABC) is helpful in maintaining good image quality by adjusting kV and/or mA based on the subject's thickness. However, it was difficult to measure effective energy using half-value layer (HVL). We investigated the usefulness of measuring effective energy and entrance surface dose using a fluorescent glass dosimeter in IVR procedures, and we made an HVL folder and IVR-phantom for that purpose. Effective energy measured using the HVL folder correlated well with reference ionization dosimeter (y=0.992x, r=0.963). The result indicated that the present method using an HVL folder and IVR-phantom provides accurate measurements of effective energy and entrance surface dose in IVR procedures. In conclusion, the present measurement method may be useful for quality control of IVR equipment. In addition, the development of this measurement technique may be useful for comparisons of exposure levels in different hospitals.

Gd-EOB-DTPA is a new liver specific MRI contrast media. In the hepatobiliary phase, contrast media is trapped in normal liver tissue, a normal liver shows high intensity, tumor/liver contrast becomes high, and diagnostic ability improves. In order to indicate the degree of uptake of the contrast media, the enhancement ratio (ER) is calculated. The ER is obtained by calculating (signal intensity (SI) after injection-SI before injection) / SI before injection. However, because there is no linearity between contrast media concentration and SI, ER is not correctly estimated by this method. We discuss a method of measuring ER based on SI and T(1) values using the phantom. We used a column phantom, with an internal diameter of 3 cm, that was filled with Gd-EOB-DTPA diluted solution. Moreover, measurement of the T(1) value by the IR method was also performed. The ER measuring method of this technique consists of the following three components: 1) Measurement of ER based on differences in 1/T(1) values using the variable flip angle (FA) method, 2) Measurement of differences in SI, and 3) Measurement of differences in 1/T(1) values using the IR method. ER values calculated by these three methods were compared. In measurement made using the variable FA method and the IR method, linearity was found between contrast media concentration and ER. On the other hand, linearity was not found between contrast media concentration and SI. For calculation of ER using Gd-EOB-DTPA, a more correct ER is obtained by measuring the T(1) value using the variable FA method.

Acoustic noise both in terms of its magnitude and frequency during magnetic resonance imaging (MRI) scan is influenced by imaging parameters and pulse sequences. It varies because of many different factors such as structure, materials, and magnetic field strength. The purpose of our study is to evaluate the characteristics of acoustic noise independent of MRI scan protocol by measuring a gradient-pulse-to-acoustic-noise transfer function (GPAN-TF) at various MRI scanners.We measured sound pressure levels in the frequency domain in a 0.4-T, seven 1.5-T, and three 3.0-T clinical MRI systems when applying a simple narrower trapezoidal gradient pulse. We calculated a GPAN-TF [μPa/(mT/m)] in each gradient coil (ie, X, Y, and Z-axis) by the deconvolution process.GPAN-TF at a high-frequency range (1000-10,000 Hz) was larger than that at low frequency for all MRI (P0.01) scanners except for a low static field machine. For high frequency (1000 Hz), the 3.0-T MRI scanner had a larger GPAN-TF than that of 0.4-T and 1.5-T (P.01). MR scanner with a vacuum chamber reduced GPAN-TF at a lower frequency (P.01), but this effect decreased at higher frequency.GPAN-TF analysis makes it possible to obtain more detailed information on acoustic noise properties among MRI scanners.

This report presents the fundamental temporospatial characteristics of a dynamic flat-panel detector (FPD) system. We investigated the relationship between pixel value and X-ray pulse output, and examined reproducibility, dependence on pulse width, tube voltage, and pulse rate. Sequential images were obtained using a direct conversion-type dynamic FPD. The exposure conditions were: 110 kV, 80 mA, 6.3 ms, 7.5 fps, source-to-image distance (SID) 1.5 m. X-ray pulse output was measured using a dosimetry system with a sampling interval of 70 μs, to determine temporal changes in each X-ray pulse output. Temporal changes in pixel value were measured in the obtained images, and the relationship between pixel value and X-ray pulse output was examined. Reproducibility was assessed by comparing the results in two sequential images obtained under the same exposure conditions. Moreover, the relationships and properties were evaluated by changing the pulse width (12 ms and 25 ms), tube voltage (80 kV, 90 kV, and 100 kV), and pulse rate (3.75 fps and 15 fps). The results showed a good correlation between the X-ray pulse output and pixel values. Fluctuation of the pixel value measured in sequential images is thought to be mainly due to changes in X-ray pulse output, and is not caused by FPD.

Magnetic resonance imaging (MRI) is useful in the quantitative evaluation of brain atrophy, because the superior contrast resolution facilitates separation of the gray and white matter. Quantitative assessment of brain atrophy has mainly been performed by manual measurement, which requires considerable time and effort to determine the brain volume. Therefore, computer-aided quantitative measurement methods for the diagnosis of brain atrophy are required. We have developed a method of segmenting the cerebrum, cerebellum–brainstem, and temporal lobe simultaneously on MR images obtained in a single sequence. It is important to measure the volume of not only these regions but also the frontal lobe in clinical use. However, for segmenting the frontal lobe, it is necessary to identify the Sylvian fissure and the central sulcus, which represent boundaries. Here, we developed a method of identifying the central sulcus from MR images obtained with a 1.5 T MRI scanner. The brain and the cerebrospinal fluid (CSF) regions were segmented using semiautomated segmentation method on MR images. The central sulcus shows an oblique line from the inside to the outside on the convexity view. The almost straight appearance of the central sulcus was used for segmentation of the central sulcus from the segmented CSF images. The central sulcus was identified with this technique in 77% of the images obtained by all sequences. This technique for identifying the central sulcus is very important not only for volumetry, but also for clinical diagnosis.

金沢大学附属病院放射線部, Our purpose in this study was to evaluate the preliminary clinical efficacy of soft-copy reading of digital mammography, for a 15-mega-sub-pixel (MsP) and a 9-MsP super-high-resolution liquid-crystal display (SHR-LCD) by use of an independent sub-pixel driving technology. We performed three kinds of phantom observation studies by six radiological technologists. Detectability of a contrast-detail phantom and simulated small objects (SSOs) resembling microcalcifications (MCLs), and shape discrimination ability of SSOs with round and square shapes, were examined and compared with a 5-MP conventional LCD (5-MP LCD). In each study, four types of display magnification ratio were used. The detectability and the shape discrimination ability of the 15-MsP SHR-LCD were highest among the three LCDs of most of the display magnification ratios. The 9-MsP SHR-LCD indicated a higher or equal performance as compared with the 5-MP LCD in the SSO detection and shape studies. The results of our study demonstrated that the SHR-LCDs had good potential to detect MCLs and to evaluate the shape in high-resolution digital mammography. © 2009 Japanese Society of Radiological Technology and Japan Society of Medical Physics.

Actinophage TG1 forms stable lysogens by integrating at a unique site on chromosomes of Streptomyces strains. The phage (attP(TG1)) and bacterial (attB(TG1)) attachment sites for TG1 were deduced from comparative genomic studies on the TG1-lysogen and nonlysogen of Streptomyces avermitilis. The attB(TG1) was located within the 46-bp region in the dapC gene (SAV4517) encoding the putative N-succinyldiaminopimelate aminotransferase. TG1-lysogens of S. avermitilis, however, did not demand either lysine or diaminopimelate for growth, indicating that the dapC annotation of S. avermitilis requires reconsideration. A bioinformatic survey of DNA databases using the fasta program for the attB(TG1) sequence extracted possible integration sites from varied streptomycete genomes, including Streptomyces coelicolor A3(2) and Streptomyces griseus. The gene encoding the putative TG1 integrase (int(TG1)) was located adjacent to the attP(TG1) site. TG1 integrase deduced from the int(TG1) gene was a protein of 619 amino acids having a high sequence similarity to phiC31 integrase, especially at the N-terminal catalytic region. By contrast, sequence similarities at the C-terminal regions crucial for the recognition of attachment sites were moderate or low. The site-specific recombination systems based on TG1 integrase were shown to work efficiently not only in Streptomyces strains but also in heterologous Escherichia coli.

We have previously shown that, in vivo, the integration system based on the gene encoding the TG1 integrase and the corresponding attB TG1 and attP TG1 sites works well not only in Streptomyces strains, but also in Escherichia coli. Furthermore, the attachment sites for TG1 integrase are distinct from those of ϕC31 integrase. In this report, we expressed TG1 integrase as a GST-TG1 integrase fusion protein and then used affinity separation and specific cleavage to release purified integrase. Conditions for in vitro recombination were established using the purified TG1 integrase and its cognate attP TG1 and attB TG1 sites. TG1 integrase efficiently catalyzed a site-specific recombination between attB TG1 and attP TG1 sites irrespective of their substrate topology. The minimal sequences of attP TG1 and attB TG1 sites required for the substrates of TG1 integrase were demonstrated to be 43 and 39-bp, respectively. These results provide the basic features of the TG1 integrase system to be used as biotechnological tools, as well as to unravel the mechanism of the serine integrase.

We have studied the stability and ferroelectric properties of hexagonal $R{\text{GaO}}_{3}$ and $R{\text{InO}}_{3}$ ($R$: rare-earth elements) by first-principles calculations. Computed spontaneous polarization in the series shows a systematic increase with the rare-earth elements, with values being larger in $R{\text{InO}}_{3}$ than in the corresponding $R{\text{GaO}}_{3}$. The largest polarization found is about $10\text{ }\ensuremath{\mu}\text{C}/{\text{cm}}^{2}$ for ${\text{ErInO}}_{3}$, which is about twice as large as those observed in hexagonal $R{\text{MnO}}_{3}$. The polarization can be further increased by applying in-plane compressive stress. The Born effective charges of constituent ions in the compounds are found to be similar to their formal values, implying that the ferroelectric displacements are merely driven by the ionic size effect. A transition to the high-symmetry phase at around 1500 K was confirmed in ${\text{GdInO}}_{3}$ and ${\text{DyInO}}_{3}$ by in situ high-temperature powder x-ray diffractometry. The present systems should belong to the family of geometric ferroelectrics.

We compared effective doses for recent computed tomography (CT) examinations calculated based on International Commission on Radiological Protection publication number 103 (ICRP 103) with those calculated based on ICRP publication number 60 (ICRP 60), and considered the usefulness of the effective dose in CT dose evaluation. After placing radiophotoluminescence glass dosimeters (RPLDs) inside or outside an anthropomorphic phantom, we examined from the chest to the pelvis, cardiac, and cranial regions of the phantom. The absorbed dose was calculated by multiplying calibrated dose values of RPLD by the mass energy coefficient ratio. The effective dose was calculated as the sum total of the value for each tissue, which was multiplied by the equivalent dose according to the tissue weighting factor recommended in ICRP 103 and ICRP 60. Calculated effective doses based on ICRP 103 were different by –11% to +82% compared with those based on ICRP 60. The values of absorbed doses for selective tissues were relatively higher than the values for the effective dose. The effective dose represents only a mean dose value for an average human. Therefore, assessing the absolute dose of particular individuals in CT examinations based exclusively on the effective dose is not recommended.

The degrees of completion in microphase separation for segmented polyurethanes containing a block segment of poly(ethylene oxide)-b-poly(dimethylsiloxane)-b-poly(ethylene oxide) (PES) were investigated. The results were compared with those for PES-free polyurethanes having the same molecular weight of the soft segment.

Structure and orientational behavior of two kinds of segmented poly(urethaneurea)s, SPUUs, having different soft segment molecular weights, were investigated by dynamic infrared absorption dichroism (DIR). DIR is a rheo-optical technique and a powerful tool to study orientational behavior of individual segments on multi-phase polymers under sinusoidal mechanical stimuli. SPUUs, being multi-block copolymers, consist of hard segment domains and soft segment matrix. Analysis of the temperature and frequency dependence of the dynamic strain–dichroic ratio coefficient, L* disclosed the following: (1) both the hard and soft segments are deformed synchronously (in-phase) with respect to applied strain, (2) the Arrhenius plot for the shift factor of L* is composed of two contributions, β (the glass transition) and γ dispersions (local motions related to methylene sequences). These observed dispersions were consistent with the corresponding mechanical dispersions, and (3) the hard segment of SPUU, having a larger soft segment molecular weight (TM-3), has a higher capability of orientation in response to external strain than that having a smaller soft segment molecular weight (TM-1).

The miscibility and surface selectivity of cellulose/poly(vinyl alcohol) (PVA) blends were investigated by Fourier-transform infra-red ( FT i.r.) and attenuated total reflection ( FT i.r.-a.t.r.) spectroscopy. The blends were prepared in film form by casting mixed polymer solutions in a common solvent (dimethylsulphoxide-tetraethylammonium chloride) onto a glass plate and successively coagulating the solutions with ethanol. The dried films were optically clear irrespective of blend composition. The transmission FT i.r. measurements revealed that the crystallinity of each polymer component decreased with increasing content of the blending partner. These findings strongly suggest a certain level of miscibility of cellulose and PVA. The compositions of the film surfaces on the glass (substrate) side and the ethanol (coagulant) side were also examined by FT i.r.-a.t.r. via two methods: (1) a method using the ratio of the integrated area of an absorption peak centred at 897 cm −1 (cellulose) to that of a peak centred at 918 cm −1 (PVA); and (2) a least-squares curve-fitting method in the range 850 to 1200 cm −1 . The results obtained by both these methods lead to the conclusion that the concentration of PVA was higher than that of cellulose at the glass-side surface, whereas no selectivity was detected at the ethanol-side surface.

Molecular orbital calculations were performed for Ne–Ne quasi-molecules formed during collisions by changing the internuclear distance between 0.01 and 10 a.u. using the discrete variational (DV)-Xα MO calculational method. The equilibrium number of electrons on the basis atomic orbitals were estimated as a function of internuclear distance from which the critical internuclear distance to form quasi-molecular orbitals were deduced.

Chest computed tomographic (CT) scans are the most effective examinations for detecting lung cancer at an early stage. In chest CT examinations, it is important to consider the reduction of radiation dose, particularly to the mammary gland. The objective of this study was to assess breast doses and effective doses on chest CT examinations between three-dimensional and z-axis automatic tube current modulation (ATCM) techniques.Absorbed dose to the breast, lung, mediastinum, and skin was evaluated with an anthropomorphic phantom and radiophotoluminescence glass dosimeters using two different CT scanners. The dosimeters were placed inside and outside the phantom. The phantom was scanned using three-dimensional and z-axis ATCM techniques after scanning localizer radiographs from the horizontal and vertical directions. After scanning, each organ dose was calculated. Moreover, the dose-length product recorded in the dose reports was examined, and each effective dose was calculated.Compared with z-axis ATCM, three-dimensional ATCM reduced breast dose by 0.7% to 18.6% and effective dose by 4.9% to 10.2%. In particular, three-dimensional ATCM reduced frontal breast dose. For other organs, three-dimensional ATCM reduced absorbed doses by 3.4% to 13.6% compared to z-axis ATCM.Three-dimensional ATCM can reduce absorbed doses to the breast and other organs, in addition to reducing effective dose, compared to z-axis ATCM.

The purpose of this study is to realize the mechanically-controllable needle-insertion system using the CMTD (curved multi-tube device) which was developed by authors. A CMTD, which consists of a straight outer needle and a curved inner needle, was developed for minimally-invasive surgery and needle insertion. And we use ultrasound as a sensing device to detect the position of tumor and the orientation of the needle which is inserted into tumor. This system makes safe minimally-invasive surgery possible, because all complex mechanisms are arranged outside of the body.

The structure and orientational behaviour of polyurethanes containing polydimethylsiloxane in the main chain was investigated by means of infrared dichroism, small angle light scattering and differential scanning calorimetry. It was found that the introduction of polydimethylsiloxane in the main chain reduced the crystallization capability of the soft segments. Hard and soft segments are oriented positively on uniaxial stretching. The orientational behaviour of the hard segments is different from that for most segmented polyurethanes and poly(urethaneurea)s, in which hard segments show negative orientation at low elongation. The difference in orientational behaviour is discussed in terms of the capability of self-cohesion of hard segments.

Measurement of the pituitary height was performed on magnetic resonance (MR) images of 213 subjects with no known or suspected pituitary and/or hypothalamic disorders. Midsagittal, T1-weighted images were used for measurements and mean heights in each age and sex group were obtained. In the 10 to 69 year range, the pituitary heights were greater in females than in males. The groups of 0-9 years of both genders showed the minimum mean pituitary height. The maximum of the mean height was observed in the 10 to 19 year age groups of both genders. The height gradually decreased with increasing age after age 20 years. There were no subjects with a height of greater than or equal to 9.0 mm in females or greater than or equal to 8.0 mm in males. There was a marked discrepancy between MR and autopsy findings in the older subjects, probably related to the upward concavity that is often encountered in the aged gland. Because of this concavity, the midsagittal MR measurement will induce underestimation of the whole gland.

Humanoid robots demand high performance on actuators, such as power-to-weight ratio, durability, occupation volume, and freedom of placement. Also, for robots to interact with unknown objects, flexibility is necessary. Backdrivability is effective when both flexibility and high output torque needs to be realized, which were often contradicting requirement. In this paper, backdrivable hydrostatic transmission is proposed to satisfy requirements above. First, development of hydrostatic actuator including conditions of backdrivability is explained. Second design of backdrivable pump, hydraulic motor and manifold design is explained. Next, design of an anthropomorphic robot hand using developed hydrostatic transmission is discussed. Finally, developed hand is presented and experiments on backdrivability, force sensing, and grasping were performed.

This study was performed for evaluation of high- and low-contrast resolution in multidetector-row CT (MDCT) with 16 detector rows. For evaluating high-contrast resolution, a phantom was scanned ten times at 100 mA s with 24 patterns of scan parameters under several X-ray beam widths, X-ray tube voltages, X-ray tube rotation times, and helical pitches. Three radiological technologists observed the images visually. For evaluating low-contrast resolution, a phantom was scanned ten times at 100 mA s with the 24 patterns of scan parameters, which were the same as for high-contrast resolution. The images were examined based on receiver operating characteristic (ROC) curves. The high-contrast resolution deteriorated in the off-center locations when helical pitches of 1.375:1 or 1.75:1 were used. High helical pitch (>0.9375:1) and low tube voltage had significant effects on the low-contrast resolution. However, a wide X-ray beam width and short X-ray tube rotation time had no definite influence. Therefore, a helical pitch of 0.5625:1 should be used when the contrast resolutions are really important, and a wide X-ray beam width and short X-ray tube rotation time can improve the temporal resolution without deterioration of contrast resolution.

Theoretical calculations of Zn $K$ and Fe $K$ x-ray absorption near-edge structures (XANES) using a first-principles method have been performed to evaluate the degree of cation disordering in spinel zinc ferrite $(\mathrm{Zn}{\mathrm{Fe}}_{2}{\mathrm{O}}_{4})$ thin film prepared by a sputtering method, $\mathrm{Zn}{\mathrm{Fe}}_{2}{\mathrm{O}}_{4}$ thin films annealed at elevated temperatures, and $\mathrm{Zn}{\mathrm{Fe}}_{2}{\mathrm{O}}_{4}$ bulk specimen prepared by a solid-state reaction. Using the full-potential linearized augmented plane-wave + local orbitals method, a theoretical spectrum is generated for the tetrahedral and octahedral environments for each of the two cations. The experimental XANES spectrum of the thin film annealed at $800\phantom{\rule{0.2em}{0ex}}\ifmmode^\circ\else\textdegree\fi{}\mathrm{C}$ as well as that of bulk specimen is successfully reproduced by using either the theoretical spectrum for ${\mathrm{Zn}}^{2+}$ on the tetrahedral site ($A$ site) or that for ${\mathrm{Fe}}^{3+}$ on the octahedral site ($B$ site), which is indicative of the normal spinel structure. For the as-deposited film, on the other hand, excellent agreement between theoretical and experimental spectra is obtained by considering the presence of either ion in both the $A$ and $B$ sites. The degree of cation disordering, $x$, defined as ${[\mathrm{Zn}_{1\ensuremath{-}x}{}^{2+}\mathrm{Fe}_{x}{}^{3+}]}_{A}{[\mathrm{Zn}_{x}{}^{2+}\mathrm{Fe}_{2\ensuremath{-}x}{}^{3+}]}_{B}{\mathrm{O}}_{4}$, is estimated to be approximately 0.6 in the as-deposited film, which is consistent with the analysis of the extended x-ray absorption fine structure on the Zn $K$ edge. Curious magnetic properties as we previously observed for the as-deposited thin film---i.e., ferrimagnetic behaviors accompanied by large magnetization at room temperature and cluster spin-glass-like behavior---are discussed in connection with disordering of ${\mathrm{Zn}}^{2+}$ and ${\mathrm{Fe}}^{3+}$ ions in the spinel-type structure.

The aim of this study was to develop an automated method of segmenting the cerebrum, cerebellum-brain stem, and temporal lobe simultaneously on magnetic resonance (MR) images.We obtained T1-weighted MR images from 10 normal subjects and 19 patients with brain atrophy. To perform automated volumetry from MR images, we performed the following three steps: (1) segmentation of the brain region; (2) separation between the cerebrum and the cerebellum-brain stem; and (3) segmentation of the temporal lobe. Evaluation was based on the correctly recognized region (CRR) (i.e., the region recognized by both the automated and manual methods).The mean CRRs of the normal and atrophic brains were 98.2% and 97.9% for the cerebrum, 87.9% and 88.5% for the cerebellum-brain stem, and 76.9% and 85.8% for the temporal lobe, respectively.We introduce an automated volumetric method for the cerebrum, cerebellum-brain stem, and temporal lobe on brain MR images. Our method can be applied to not only the normal brain but also the atrophic brain.

Migration of Li+ ions via the vacancy mechanism in LiX (X = F, Cl, Br, and I) with the rocksalt and hypothetical zinc blende structures and Li2X (X = O, S, Se, and Te) with the antifluorite structure has been investigated using first-principles projector augmented wave calculations with the generalized gradient approximation. The migration paths and energies, determined by the nudged-elastic-band method, are discussed on the basis of two idealized models: the rigid-sphere and charged-sphere models. The trajectories and energy profiles of the migration in these lithium compounds vary between these two models, depending on the anion species and crystal structure. The migration energies in LiX with both the rocksalt and hypothetical zinc blende structures show a tendency to decrease with increasing periodic number of the anion species in the periodic table. This is consistent with the widely accepted view that anion species with large ionic radii and high polarizabilities are favorable for good ionic conduction. In contrast, Li2O exhibits the lowest migration energy among Li2X compounds, although O is the smallest among the chalcogens, indicating that electrostatic attractive interactions play the dominant role in the inter-ion interactions in Li2O and, therefore, in the ion migration.

The temperature dependence of cationic disorder in $\mathrm{Mg}{\mathrm{Al}}_{2}{\mathrm{O}}_{4}$ spinel is investigated using a combination of first-principles total-energy calculations, a cluster expansion, and canonical Monte Carlo simulations. The formation energies of the possible cation-disordered structures within the spinel unit cell are predicted to be all positive, suggesting that the ground state is the normal spinel in consistency with a widely accepted view. The temperature dependence of cationic disorder is well reproduced by considering many effective cluster interactions up to quadruplets. The order-disorder transition temperature is estimated at about $860\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ based on the anomaly of specific heat. The cluster expansion of the volume of $\mathrm{Mg}{\mathrm{Al}}_{2}{\mathrm{O}}_{4}$ indicates that it decreases as more cations exchange.

To avoid radiation injury from interventional radiology (IVR), quality assurance (QA) of IVR equipment based on dosimetry is important. In this study, we investigated the usefulness of measuring patient skin dose with a passive integrating dosimeter and water phantom. The optically stimulated luminescence dosimeter (OSLD) was chosen from among various passive integrating dosimeters. The characteristics of the OSLD were compared with a reference ionization dosimeter. The effective energy obtained from the OSLD was compared with that found by the aluminum attenuation method for using the reference ionization dosimeter. Doses and effective energies measured by OSLD correlated well with those of the reference ionization dosimeter. (dose: y=0.971x, r=0.999, effective energy: y=0.990x, r=0.994). It was suggested that OSLD could simultaneously and correctly measure both patient skin dose and effective energy. Patient skin dose rate and effective energy for 15 IVR units of 10 hospitals were investigated using OSLD and a water phantom for automatic brightness control fluoroscopy. The measurement was performed at the surface of a water phantom that was located on the interventional reference point, and source image intensifier distance was fixed to 100 cm. When the 9-inch field size was selected, the average patient skin dose rate was 16.3+/-8.1 mGy/min (3.6-32.0 mGy/min), the average effective energy was 34.6+/-4.1 keV (30.5-42.5 keV). As a result, it was suggested that QA should be performed not only for patient dose but also for effective energy. QA of equipment is integral to maintaining consistently appropriate doses. Consequently, the dosimetry of each IVR unit should be regularly executed to estimate the outline of patient skin dose. It was useful to investigate patient skin dose/effective energy with the passive integrating dosimeter for IVR equipment.

Aiming at opening up a new stage of humanoid robotics, we have been studying on the mechanically soft structure for humanoids and have developed a full-body muscle-driven flexible-spine humanoid robots. In this paper, we discuss body structure of humanoids, describing the advantages of musculoskeletal flexible body and briefly introducing the previous works on constructing hardware and software of flexible spine robots. This paper also presents the design and development of a novel musculoskeletal humanoid named Kotaro

Excessive radiation exposure in pediatric computed tomography （CT） scanning has become a serious problem and it is difficult to select scan parameters for the scanning of small patients such as children. We investigated differences in absorbed dose and standard deviation in Hounsfield unit （HU） caused by differences in the form of the subject using a body‑type phantom with removable body parts. Using four X‑ ray CT scanners measurements were made with values from 50 mAs to 300 mAs with slices of 50 mAs using scan protocols that were assumed to perform thorough examinations. The results showed that the mAs values and absorbed doses were almost proportional and the absorbed doses in the phantom without body parts were about 1.1–2.2‑fold higher than those of the phantom with body parts at the same points. The SD values obtained indicated that the absorbed doses in the phantom with body parts were 0.3–0.6 times those of the phantom without body parts when the mAs values used were adjusted so that both SD values were the same. The absorbed doses in various patient forms can be estimated from these results and they will be‑ come critical data for the selection of appropriate scan protocols. Summary

Zirconia, $\mathrm{Zr}{\mathrm{O}}_{2}$, is one of the most important ceramic materials in modern technology. Its versatility is closely related to phase transformations. Although the transformations have been repeatedly investigated by experiments, fundamental aspects of the transformations are still under debate. In the present paper, we have made first principles calculations to study the lattice dynamics of $\mathrm{Zr}{\mathrm{O}}_{2}$ polymorphs and phase transformation at finite temperatures. Cubic phase shows a soft mode at the $X$ point in the Brillouin zone, which should spontaneously induce cubic-to-tetragonal transformation. In tetragonal and monoclinic $\mathrm{Zr}{\mathrm{O}}_{2}$, all vibrational modes have real frequency. Calculations of Helmholtz free energies show that the tetragonal phase becomes more stable than the monoclinic phase above $1350\phantom{\rule{0.3em}{0ex}}\mathrm{K}$, which is in quantitative agreement with experimental results. This confirms that vibrational entropy contributes to destabilize monoclinic $\mathrm{Zr}{\mathrm{O}}_{2}$ at elevated temperatures.

Local environments of solutes in $\ensuremath{\beta}$- and spinel ${\mathrm{Si}}_{6\ensuremath{-}z}{\mathrm{Al}}_{z}{\mathrm{O}}_{z}{\mathrm{N}}_{8\ensuremath{-}z}$ are investigated by means of Al $K$ x-ray absorption near-edge structure. The experimental spectra are found to be the same throughout the wide solubility range. This suggests that the local environments of Al are independent of the solute concentration. First-principles band-structure calculations are systematically made to interpret the experimental spectra. Effect of a core hole was included into the calculation. Theoretical spectra were obtained using variety of different model structures constructed by a set of plane-wave pseudopotentials calculations in our previous study [K. Tatsumi, I. Tanaka, H. Adachi, and M. Yoshiya, Phys. Rev. B 66, 165210 (2002)]. The numbers of models were 51 and 45 for both $\ensuremath{\beta}$ and spinel, respectively. They are classified and averaged according to the local atomic structure of Al solutes. The combination of experimental spectra and theoretical results can unambiguously lead to the conclusion that Al atoms are preferentially coordinated by O atoms in both $\ensuremath{\beta}$ and spinel phases. This is consistent with the conclusion obtained by the first-principles total-energy calculations. In the spinel phase, Al atoms are found to be located preferentially at the octahedral cationic site. This agrees with the conclusion in a recent report on the nuclear magnetic resonance experiment.

A recent high pressure experiment on ${\mathrm{L}\mathrm{a}\mathrm{A}\mathrm{l}\mathrm{O}}_{3}$ has revealed that the compound is an exception for the ``general rule'' of displacive phase transition associated with zone-boundary phonons. In the present study, the experimental result is successfully confirmed by first principles calculations. The pressure dependence of phonon frequencies as well as the phase transition pressure is quantitatively well reproduced. We found that the behavior is not peculiar to ${\mathrm{L}\mathrm{a}\mathrm{A}\mathrm{l}\mathrm{O}}_{3}$ but rather ubiquitous. $R{\mathrm{A}\mathrm{l}\mathrm{O}}_{3}$ ($R=\mathrm{L}\mathrm{a}$, Nd, Sm, and Gd) and ${\mathrm{L}\mathrm{a}\mathrm{G}\mathrm{a}\mathrm{O}}_{3}$ can be classified in the same group.

Dexterity of human behavior arises from the ability to discover and exploit so-called “knacks”, or the essential reference frames (coordinates in the phase space) for successful control under unknown perturbations. This strategy differs from the traditional robot control in that it only partially specifies/controls the phase space trajectory, pushing the system into a desired natural dynamics, letting it do the job. As the first example of such a strategy, we investigated a “roll-andrise” motion, a fully dynamic whole-body motion with unpredictable perturbations due to multiple contacts with the ground. The “knacks” of the motion are identified and analyzed by a systematic search of the phase space. A successful experiment with an adult-size whole body humanoid robot is presented; it rose from a flat-lying posture to a crouching posture within 2 seconds.

First-principles calculations of ELNES and XANES of selected wide-gap materials: Dependence on crystal structure and orientation Author(s) Mizoguchi, T; Tanaka, I; Yoshioka, S; Kunisu, M; Yamamoto, T; Ching, WY Citation PHYSICAL REVIEW B (2004), 70(4) Issue Date 2004-07 URL http://hdl.handle.net/2433/39865 Right Copyright 2004 American Physical Society Type Journal Article Textversion none; publisher KURENAI : Kyoto University Research Information Repository

This paper proposes a system which can capture a dynamic 3D scene and synthesize its arbitrary views in real time. Our system consists of four components: a fresnel lens, a micro-lens array, an IEEE1394 digital camera, and a PC for rendering purpose. The micro-lens array forms an image which consists of a set of elemental images, in other words, multiple viewpoint images of the scene. The fresnel lens controls the depth of field by demagnifying the 3D scene. The problem is that the scene demagnified by the fresnel lens is compressed along its optical axis. Therefore, we propose a method for recovering the original scene from the compressed scene. The IEEE1394 digital camera captures multiple viewpoint images at 15 frames per second, and transfers these images to the PC. The PC synthesizes any perspective of the captured scene from the multiple viewpoint images using image-based rendering techniques. The proposed system synthesizes one perspective of the captured scene within 1/15 second. This means that a user can interactively move his/her viewpoint and observe even a moving object from various directions.