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Since the discovery of the Y-Ba-Cu-O superconductors, their physical properties have been investigated by various methods. The chemical state of Cu in Y-Ba-Cu-O compounds la one of the greatest issues because the mechanism of superconductivity in Y-Ba-Cu-O is not understood theoretically. We are analyzing X-ray fluorescence spectra of Cu compounds including superconductors, intending to analyze the chemical state of Cu in Y-Ba-Cu-O. As for other 3d transition elements, structures due to unpaired electrons appear clearly on the lower energy side of the Kα1 line of the element. However there are little differences observed among Cu Kα spectra of Cu compounds even if they are measured by a high-resolution two-crystal spectrometer (see Fig. 1). Although Cu is a member of 3d transition elements, its Kα spectrum shows somewhat different behavior compared with other 3d transition elements. This point is one subject we are interested in.
We showed that it is feasible to measure the mass of a single star by observing the variation of gravitational deflection caused by the orbital motion of the Earth. When the distance of a star is less than 60 pc and some appropriate sources are within 1 arcsec. in its background, not only the distance but also the mass of the star may be determined by measuring the deflection with an accuracy of 10 μ arcsec. In the case of photometric microlensing by a MACHO, the observation of astrometric gravitational deflection is also useful. By measuring the separation between the primary image and the secondary image, the ratio of mass to distance of the MACHO will be obtained. Further, the orbital motion of the Earth modifying the light curve of the source is discussed.
The relation between the units and the readings of time and space coordinates of the terrestrial and the barycentric frames is discussed from the viewpoint of general relativity. Attention is paid to the unit of space coordinates since the International Astronomical Union (IAU) regulates only the unit of time coordinate in the above two frames. Two definitions on unit of length are examined and their effects on the numerical expression of coordinate transformation, equations of planetary motions, and those for light propagation time are discussed. A clear conflict is found between the IAU(1976) recommendation on the definition of the time-scales in different frames and the statement that all constants in the IAU(1976) new system of astronomical constants are defined in terms of the international system of units (SI units). In order to dissolve this conflict, one of the two examined definitions on unit of length is proposed to be adopted, which requests the least alteration on the current procedures to analyze the astrometric observations such as radar/laser rangings, range and range-rate measurements, and very long baseline interferometric observations. An interpretation of numerical values in the IAU(1976) system of astronomical constants is also presented. It is stressed that the definition proposed in this paper requires that a slightly different formula from the current one be used in the numerical transformation of coordinates between the terrestrial and the barycentric frames.
The treatment of the coordinate systems is briefly reviewed in the Newtonian mechanics, in the special theory of relativity, and in the general relativistic theory, respectively. Some reference frames and coordinate systems proposed within the general relativistic framework are introduced. With use of the ideas on which these coordinate systems are based, the proper reference frame comoving with a system of mass-points is defined as a general relativistic extension of the relative coordinate system in the Newtonian mechanics. The coordinate transformation connecting this and the background coordinate systems is presented explicitly in the post-Newtonian formalism. The conversion formulas of some physical quantities caused by this coordirate transformation are discussed. The concept of the rotating coordinate system is reexamined within the relativistic framework. A modification of the introduced proper reference frame is proposed as the basic coordinate system in the astrometry. The relation between the solar system barycentric coordinate system and the terrestrial coordinate system is given explicitly.
Research in Celestial Mechanics, for the past three years, has mainly focused on the understanding of Chaos on all its aspects. The always larger number of potential applications (meteors, KBO, NEA, asteroids of the main belt but also exoplanets or galactic motions) and the development of new efficient tools, like the symplectic integrators, have allowed the passage from QUALITATIVE models (for example the transfer mechanisms) to real QUANTITATIVE results (like the calculation of lifetimes). This important step has contributed to (re)create collaborations between theoreticians and observers (for example, in the prediction of catastrophic impacts) and to situate the Celestial Mechanics in a wider scientific context.
The projects LIGHT and MIRA are the space-borne and ground-based optical/Infrared-interferometer projects of the National Astronomical Observatory of Japan. The contents of each project are gradually developing, and the descriptions given below are the preliminary ones studied at the present time.
LIGHT (Light Interferometer satellite for the studies of Galactic Halo Tracers) is a scanning astrometric satellite for stellar and galactic astronomy planned to be launched between 2007 and 2010 by a M-V launcher of ISAS, Japan. Two sets of Fizeau-type 40cm-pupil interferometers with 1 m baseline are the basic structure of the satellite optics. The multi-color (U, B, V, R, I, and K) CCD arrays are planned to be used in the focal plane of the interferometer, optimized for detecting the precise locations of fringe patterns. LIGHT is expected to observe the parallaxes and proper motions of nearly a hundred million stars up to 18th visual (15thK-band) magnitude with the precision better than 0.1 milli-arcsecond (about 50 microarcsecond in V-band and 90 micro-arcsecond in K-band) in parallaxes and better than 0.1 milli-arcsecond per year in proper motions, as well as the precise photometric characteristics of the observed stars. Almost all of the giant and supergiant stars belonging to the disk and halo components of our Galaxy within 10 to 15 kpc from the sun will be observed by LIGHT to study the most fundamental structure and evolution of the Galaxy. LIGHT will become a precursor of a more sophisticated future astrometric interferometer satellite like GAIA (Lindegren and Perryman, 1996).
Elucidating how the human brain is structured and how it functions is a fundamental aim of human neuroscience. To achieve such an aim, the activity of the human brain has been measured using noninvasive neuroimaging techniques, the most popular of which is functional magnetic resonance imaging (fMRI) (Ogawa et al. 1990). The fMRI signals are obtained at a spatial resolution of typically 3mm and measure changes of blood flow and blood oxygen consumption whose temporal dynamics are slower than that of neuronal electrical activities, resulting in a poor temporal resolution of the order of seconds. In contrast, magnetoencephalography (MEG) and electroencephalography (EEG) can detect changes of neuronal activities by the millisecond measurement of magnetic and electric fields, respectively, outside the skull (Hämäläinen et al. 1993; Nunez & Srinivasan 2006). The high temporal resolution of MEG (and EEG) is useful, especially for studying the dynamic integration of functionally specialized brain regions, which is a subject of growing interest in human neuroscience (de Pasquale et al. 2012).
The major problem of MEG is that spatial brain activity patterns are not easily understandable from sensor measurements. This is because the magnetic fields produced by neuronal current sources are superimposed to form rather uninterpretable spatial patterns of signals on sensors. Estimating the position and intensity of these current sources from the sensor measurements is called source reconstruction, or source localization. Solving the source reconstruction problem allows the mapping of temporally dynamic electrical activities in the human brain (Baillet et al. 2001). Since how brain regions are dynamically integrated to produce a variety of functions is of great interest in human neuroscience research, the mission of MEG source reconstruction is not only to localize position of the current sources, but also to identify directed interactions between these sources. A possible approach to this involves constructing a dynamic model of brain electrical activities, as well as developing an estimation algorithm for the source positions and interactions that are parametrized in this model.
Bone contouring is currently the best treatment for fibro-osseous lesions after bone growth arrest. Navigation systems available for this surgery allow intra-operative visualisation with improved cosmetic outcomes. However, conventional navigation systems using superficial skin registration cannot prevent subtle discrepancies.
To address this problem, we used a non-invasive cranial bone registration that uses patient-specific dental templates to maintain exact registration. We created the preset goal using the mirror image of the unaffected side for unilateral lesions, and using images obtained before the onset of symptoms for bilateral lesions. This system achieved precise pre-operative simulation. A sound aid in the navigation system provided information regarding proximity to critical structures and to the preset goal.
We used this system to contour fibro-osseous lesions in three patients. All patients achieved good facial contours and improvement in symptoms.
This method offers a safe, rapid surgical aid in treating orbital fibro-osseous lesions.
The objective of this study was to examine temporal and regional variations of sporadic Creutzfeldt–Jakob disease (sCJD) in a retrospective study using Japanese national surveillance data from 2001 to 2010. We calculated the incidence of sCJD by age and sex, derived the standardized incidence in each of the 47 prefectures, and performed spatial disease clustering analysis. The average annual incidence of sCJD was 1·026 per million in men (637 patients) and 1·132 per million in women (733 patients), a significant sex difference after adjustment for age (P = 0·001). The ratios of familial CJD to sCJD apparently increased between 2001–2005 and 2006–2010, possibly as a result of the nationwide introduction of genetic testing after 2006. Based on the data of 2006–2010, certain geographical clusters of sCJD were identified. The incidence of sCJD was higher in several specific prefectures compared to the national average. Thus, sCJD appears to have regional variations, suggesting the existence of genetic or region-specific factors affecting the incidence of the disease.
To enhance the catalytic activities of zeolites for the polycondensation reactions of humic precursors, Fe was loaded into a zeolite via an ion-exchange reaction and the resulting product was subjected to calcination at 773 K. Two types iron-loaded zeolites were prepared using one equivalent (Fe-Z-1) and 10-equivalents (Fe-Z-10) of Fe2+ to the cation-exchange capacity of a natural zeolite from Niki town (Hokkaido, Japan). X-ray diffraction (XRD) patterns and X-ray photoelectron spectroscopy (XPS) spectra showed that the Fe(II) that was originally loaded into the cation-exchange sites in the zeolite became oxidized to a Fe(III) ionic species during the preparation. The catalytic activities of each zeolite were evaluated, based on the degree of darkening for reaction mixtures containing catechol, glycine and glucose as model humic precursors. The catalytic activities of Fe-Z-1 and Fe-Z-10 were higher than that for an untreated zeolite, and increased with the amount of Fe in the zeolite.
The Commission 4 Organizing Committee began its work for the 2009-2012 triennium by revising the commission's terms of reference, which serve as our “mission statement.” The new terms of reference are:
(a)Maintain cooperation and collaboration between the national offices providing ephemerides, prediction of phenomena, astronomical reference data, and navigational almanacs.
(b)Encourage agreement on the bases (reference systems, time scales, models, and constants) of astronomical ephemerides and reference data in the various countries. Promote improvements to the usability and accuracy of astronomical ephemerides, and provide information comparing computational methods, models, and results to ensure the accuracy of data provided.
(c)Maintain databases, available on the Internet to the national ephemeris offices and qualified researchers, containing observations of all types on which the ephemerides are based. Promote the continued importance of observations needed to improve the ephemerides, and encourage prompt availability of these observations, especially those from space missions, to the science community.
(d)Encourage the development of software and web sites that provide astronomical ephemerides, prediction of phenomena, and astronomical reference data to the scientific community and public.
Promote the development of explanatory material that fosters better understanding of the use and bases of ephemerides and related data.
Polycondensation reactions between amino acids and phenols are one of the pathways for the formation of humic substances, and clay minerals are able to catalyse these reactions. To investigate the catalytic power of allophane, an allophane fraction (ALF) was separated from weathered pumice (WP) that contained imogolite as an impurity by taking advantage of differences in sedimentation velocity. The iron content in the separated ALF was increased by up to 3.0% compared to that in the starting WP (1.3%), and the ALF was further treated with sodium dithionate and citric acid (ALF-DC) to remove the iron. The catalytic powers of WP, ALF and ALF-DC were evaluated, based on the degree of darkening of reaction mixtures from polycondensation reactions between catechol and tryptophan, model compounds for precursors of humic substances. The catalytic power for ALF was significantly higher than the corresponding values for WP and ALF-DC. This can be attributed to the high iron content of the ALF, which serves as a Lewis acid that can enhance nucleophilic reactions which occur during the polycondensation reactions.
The heteroepitaxy of InP on Si substrates was investigated using MOCVD. A thin GaAs intermediate layer was used to alleviate the 8.4% lattice mismatch between InP and Si. With the use of this intermediate layer, four inch size, single domain InP epilayer with small residual stress was reproducibly grown on off-(100) oriented Si substrates. The etch pit density (EPD) of as-grown InP layer was 5x107~1x108 cm-2 . The post growth annealing of this epilayer at 800~850ºC in aPH3+H2 ambient reduced EPD to 1~2x107 cm-2
Pseudoelastic behavior of Fe3Ga single crystals regardless of a thermoelastic martensitic transformation was investigated focusing on the dislocation structure and the phase constituent. Large pseudoelasticity of 5 % recoverable strain appeared in Fe3Ga single crystals sufficiently annealed in the D03 single-phase region. In the crystals, uncoupled and paired 1/4 superpartial dislocations moved dragging the nearest-neighbor (NN) and next-nearest neighbor (NNN) anti-phase boundaries (APBs) during loading, respectively. During unloading, these APBs pulled back the superpartials resulting in large pseudoelasticity, which is similar to D03-ordered Fe3Al crystals. The dislocation configuration was closely related to the ordered domain structure developed in the D03 phase. Moreover, the precipitation of the thermally stable L12 phase was so slow that the metastable D03 phase developed even if the crystals were annealed in the (a+ L12) and (D03+ L12) phase fields in Fe-Ga equilibrium phase diagram. The metastable D03 phase also demonstrated large pseudoelasticity of which recovery ratio was above 80 %. On the other hand, if the L12 phase precipitated by long time annealing in the (a+ L12) region, the reversible motion of 1/4 superpartials was suppressed by the L12 phase resulting in a decrease in recovery ratio. In addition, the crystals aged in the (a+ D03) phase region showed small strain recovery.
Yttria-doped tetragonal zirconia polycrystals (Y-TZP) containing 2 and 3 mol% of Y2O3 uniformly alloyed by 0-15 mol% of CeO2 or diffusing CeO2 on the surface were fabricated, and the mechanical properties and thermal stability of the sintered bodies were evaluated by annealing in humidity conditions at 50–600° C. The tetragonal-to-monoclinic phase transformation proceeded at 100–500°C in air, and accompanied microcracks. The phase transformation proceeded rapidly on the surface, but slowly inside the body. The bending strength of the annealed specimens depended on the depth of the transformation layer thickness, but not on the degree of the phase transformation on the surface. Alloying CeO2 was useful to improve the thermal stability of Y-TZP, but noticeably decreased the fracture strength. Diffusing CeO2 on the suface of Y-TZP seemed to be useful to improve the thermal stability without loss of the fracture strength.
Carbon in LEC GaAs was found to be introduced as CO from the ambient atmosphere; the oxygen concentration in the crystals decreased with increase in the duration of melting. An equilibrium segregation coefficient of oxygen in GaAs crystals was found by charged particle activation analysis to be 0.1, the value of which was smaller by a factor of 3~4 than that reported before.