382 research outputs found
Measuring Economic Localization: Evidence from Japanese Firm-level Data
This paper examines location patterns of Japan’s manufacturing industries using a unique firm-level dataset on the geographic location of firms. Following the point-pattern approach proposed by Duranton and Overman (2005), we find the following. First, about half of Japan’s manufacturing industries can be classified as localized and the number of localized industries is largest for a distance level of 40 km or less. Second, several industries in the textile mill products sector are among the most localized, which is similar to findings for the UK, suggesting that there exist common factors across countries determining the concentration of industrial activities. Third, the distribution of distances between entrant (exiting) firms and remaining firms is, in most industries, not significantly different from a random distribution. These results suggest that most industries in Japan neither become more localized nor more dispersed over time and are in line with similar findings by Duranton and Overman (2008) for the UK. Fourth, a comparison with the service sector indicates that the share of localized industries is higher in manufacturing than in services, although the extent of localization among the most localized manufacturing industries is smaller than that among the most localized service industries, including financial service industriesMicro-geographic data, Economic geography
In-vivo bone CT based on phase contrast
Hard X-ray phase-contrast imaging is sensitive to density variation in objects and shows a great dose advantage for in vivo observation over absorption-contrast imaging. We examined the capability of propagation-based phase-contrast tomography (PB-PCT) with single-distance phase retrieval for tracking of bone structure and mineral changes using monochromatic synchrotron light. Female mice underwent ovariectomy and drill-hole surgery in the right tibial diaphysis and were divided into two groups: OVX and OVX-E (n = 6 each); the latter group was treated with intraperitoneal administration of 14,15-epoxyeicosatrienoic acid (14,15-EET) for promoting bone repair. Age-matched mice subjected to sham ovariectomy and drill-hole surgery (Sham) were also prepared (n = 6). In vivo CT scans of the drilled defect were acquired 3, 7, and 11 days after surgery, and tomographic images were matched by three-dimensional registration between successive time points for monitoring the process of defect filling. Additionally, using absorption-contrast CT as the reference method, the validity of PB-PCT was evaluated in one mouse by comparing images of tibial metaphyseal bone between the two methods in terms of bone geometry as well as the measure of mineralization. Although phase retrieval is strictly valid only for single-material objects, PB-PCT, with its lower radiation dose, could provide a depiction of bone structure similar to that from absorption-contrast CT. There was a significant correlation of linear absorption coefficients between the two methods, indicating the possibility of a rough estimate of the measure of mineralization by PB-PCT. Indeed, delayed bone regeneration (OVX vs. Sham) and the efficacy of 14,15-EET for improving osteoporotic bone repair (OVX-E vs. OVX) could be detected in both bone volume and mineralization by PB-PCT. Thus, in combination with single-distance phase retrieval, PB-PCT would have great potential for providing a valuable tool to track changes in bone structure and mineralization, and for evaluating the effects of therapeutic interventions as well
Measuring Economic Localization: Evidence from Japanese firm-level data
This paper examines the extent of localization in Japan's manufacturing sector using a unique firm-level dataset on the geographic location of firms. Following the point-pattern approach proposed by Duranton and Overman (2005), we find the following. First, approximately half of Japan's manufacturing industries can be classified as localized and the number of localized industries is largest for a distance of 40 km or less. Second, several industries in the textile mill products sector are among the most localized, which is similar to findings for the UK. This suggests that there exist common factors across countries that determine the concentration of industrial activities. Third, the distribution of distances between entrant (exiting) firms and remaining firms is, in most industries, not significantly different from a random distribution. The results by Durantan and Overman (2008) for the UK and our results for Japan suggest that most industries neither become more localized nor more dispersed over time.
Strain-field calculation based on X-ray CT images via point matching of impurities using Voronoi diagram
Ishii Akio, Horikawa Keitaro, Hoshino Masato, et al. Strain-field calculation based on X-ray CT images via point matching of impurities using Voronoi diagram. Materialia 36, 102175 (2024); https://doi.org/10.1016/j.mtla.2024.102175.We propose an approach for calculating the strain field inside materials using X-ray computed tomography (CT) images obtained during deformation tests. Our approach is based on the point matching of the detected impurities from the CT images, and the points in the reference and deformed CT images are used to construct a Voronoi diagram. In addition to the change in distance between the reference and deformed points, the volume and shape of the Voronoi polyhdra at each point are used for point matching. By applying the proposed method to a notched Al alloy sample, we calculated the change in the strain field around the notch during deformation in a tensile test using X-ray CT images, and our method was validated
CT dose reduction factors in the thousands using X-ray phase contrast
Phase-contrast X-ray imaging can improve the visibility of weakly absorbing
objects (e.g. soft tissues) by an order of magnitude or more compared to
conventional radiographs. Previously, it has been shown that combining phase
retrieval with computed tomography (CT) can increase the signal-to-noise ratio
(SNR) by up to two orders of magnitude over conventional CT at the same
radiation dose, without loss of image quality. Our experiments reveal that as
radiation dose decreases, the relative improvement in SNR increases. We
discovered this enhancement can be traded for a reduction in dose greater than
the square of the gain in SNR. Upon reducing the dose 300 fold, the
phase-retrieved SNR was still almost 10 times larger than the absorption
contrast data. This reveals the potential for dose reduction factors in the
tens of thousands without loss in image quality, which would have a profound
impact on medical and industrial imaging applications
Development of an X-ray real-time stereo imaging technique using synchrotron radiation
An X-ray stereo imaging system with synchrotron radiation was developed to perform real-time stereo imaging and stereo angiography
Space weathering structures on the surface micro-nano morphologies of Itokawa regolith particles.
第3回極域科学シンポジウム/第35回南極隕石シンポジウム 11月30日(金) 国立国語研究所 2階講
Discovery of primitive CO2-bearing fluid in an aqueously altered carbonaceous chondrite
隕石中に閉じ込められたCO2に富む液体の水を世界で初めて発見 --太陽系形成時に誕生した小天体がその後の木星の軌道変化に伴なって移動した証拠--. 京都大学プレスリリース. 2021-04-22.Water is abundant as solid ice in the solar system and plays important roles in its evolution. Water is preserved in carbonaceous chondrites as hydroxyl and/or H₂O molecules in hydrous minerals, but has not been found as liquid. To uncover such liquid, we performed synchrotron-based x-ray computed nanotomography and transmission electron microscopy with a cryo-stage of the aqueously altered carbonaceous chondrite Sutter’s Mill. We discovered CO₂-bearing fluid (CO₂/H₂O > ~0.15) in a nanosized inclusion incorporated into a calcite crystal, appearing as CO₂ ice and/or CO₂ hydrate at 173 K. This is direct evidence of dynamic evolution of the solar system, requiring the Sutter’s Mill’s parent body to have formed outside the CO₂ snow line and later transportation to the inner solar system because of Jupiter’s orbital instability
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