133 research outputs found

    Universal scaling for the spin-electricity conversion on surface states of topological insulators

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    We have investigated spin-electricity conversion on surface states of bulk-insulating topological insulator (TI) materials using a spin pumping technique. The sample structure is Ni-Fe|Cu|TI trilayers, in which magnetic proximity effects on the TI surfaces are negligibly small owing to the inserted Cu layer. Voltage signals produced by the spin-electricity conversion are clearly observed, and enhanced with decreasing temperature in line with the dominated surface transport at lower temperatures. The efficiency of the spin-electricity conversion is greater for TI samples with higher resistivity of bulk states and longer mean free path of surface states, consistent with the surface spin-electricity conversion

    Japan Tsunami Current Flows Observed by HF Radars on Two Continents

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    Quantitative real-time observations of a tsunami have been limited to deep-water, pressure-sensor observations of changes in the sea surface elevation and observations of sea level fluctuations at the coast, which are essentially point measurements. Constrained by these data, models have been used for predictions and warning of the arrival of a tsunami, but to date no detailed verification of flow patterns nor area measurements have been possible. Here we present unique HF-radar area observations of the tsunami signal seen in current velocities as the wave train approaches the coast. Networks of coastal HF-radars are now routinely observing surface currents in many countries and we report clear results from five HF radar sites spanning a distance of 8,200 km on two continents following the magnitude 9.0 earthquake off Sendai, Japan, on 11 March 2011. We confirm the tsunami signal with three different methodologies and compare the currents observed with coastal sea level fluctuations at tide gauges. The distance offshore at which the tsunami can be detected, and hence the warning time provided, depends on the bathymetry: the wider the shallow continental shelf, the greater this time. Data from these and other radars around the Pacific rim can be used to further develop radar as an important tool to aid in tsunami observation and warning as well as post-processing comparisons between observation and model predictions

    An attempt of dissemination of potential fishing zones prediction map of Japanese common squid in the coastal water, southwestern Hokkaido, Japan

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    Accurate prediction of potential fishing zones is regarded as one of the most immediate and effective approaches in operational fisheries. It helps fishermen reduce their cost on fuel and also decrease the uncertainty of their fish catches. To predict potential fishing zones of Japanese common squid, we derived fishing positions from the Defense Meteorological Satellite Program (DMSP) Operational Linescan System (OLS), combine with bathymetry and model-derived environmental factors from the 4D-VAR data assimilation system and fitted using habitat suitability index (HSI) model. Validations with an independent DMSP/OLS dataset showed better performance of the model in figuring out the squid aggregations than our previous model established with satellite-derived environmental data. Nighttime visible images during June and early July of 2013 derived from Day/Night band (DNB) of Visible Infrared Imaging Radiometer Suite (VIIRS) sensor with a better resolution and quality compared to DMSP/OLS, were also applied for validation and results showed differences of fitness between actual fishing activities and predictions in Japan Sea and Tsugaru Strait

    Effectiveness of Magnifying Narrow-Band Imaging Endoscopy for Differential Diagnosis between the High-Risk Mixed-Type and Low-Risk Simple-Type of Low-Grade, Well-Differentiated Gastric Tubular Adenocarcinoma

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    Backgrounds. Magnifying endoscopy with narrow-band imaging (NBI-ME) is useful for diagnosing differentiated early gastric cancer (D-EGC). D-EGC is classified as high- or low-grade based on its glandular architectural and cytological atypia. Low-grade, well-differentiated tubular adenocarcinoma (LG-tub1) mixed with high-grade tub1 (HG-tub1) and/or other histological types (M-LG-tub1) may indicate a primitive high-risk malignant lesion compared to histologically simple-type LG-tub1 (S-LG-tub1). Because LG-tub1 is occasionally difficult to diagnose due to its unclear demarcation under conventional white light endoscopy, early precise diagnoses are important. Methods. We compared NBI-ME and postendoscopic submucosal dissection histological findings for 30 S-LG-tub1 and 15 M-LG-tub1 lesions. We classified the NBI-ME findings of S-LG-tub1 (and not D-EGC) into four patterns. The differential diagnosis between M-LG-tub1 and S-LG-tub1 depended on the presence of more than one of these patterns without or with other patterns (referred to as “limited-to-four-pattern [LFP] sign-positive” and “sign-negative”, resp.). Result. The sensitivity, specificity, accuracy, positive and negative predictive values, and intraobserver and interobserver agreement, using the “LFP sign” for the differential diagnosis between M-LG-tub1 and S-LG-tub1, were 87.9%, 91.7%, 88.9%, 96.7%, 73.3%, and k = 0.842 and k = 0.737, respectively. Conclusion. NBI-ME may be useful in differentiating between high-risk M-LG-tub1 and low-risk S-LG-tub1

    Changing Abundance of Magnetofossil Morphologies in Pelagic Red Clay Around Minamitorishima, Western North Pacific

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    金沢大学理工研究域地球社会基盤学系Recent investigations have discovered an unexpected abundance of magnetofossils in oxic pelagic red clays. These have potential to serve as paleoenvironmental tracers in otherwise nonfossiliferous sediments. Here, we report on variations in the abundance and morphology of magnetofossils in red clay from the western North Pacific. Magnetic measurements revealed that magnetofossils dominate the magnetic mineral assemblage of the sediments. An endmember analysis of isothermal remanent magnetization acquisition curves, supplemented by an analysis of S ratios, indicates that the magnetic assemblage can be unmixed into three endmembers, two corresponding to magnetofossils and one to terrigenous magnetic minerals. Direct counting of magnetofossil morphologies under a transmission electron microscope shows that the two magnetofossil endmembers differentiate equant magnetofossils and bullet-shaped magnetofossils, respectively. The stratigraphic variation of the endmember contributions revealed that the equant magnetofossils are dominant for the most part, while an interval at around 7 m in core depth shows higher abundance of the bullet-shaped magnetofossils. This may reflect enhanced organic carbon flux to the sediments. The organic carbon content is low throughout the sediments, and it does not show any change corresponding to the increase of bullet-shaped magnetofossils, pointing at extensive remineralization of the organic carbon. On the basis of lithostratigraphic correlation to nearby drilling sites, we tentatively estimate the age of the bullet-shaped magnetofossil increase as sometime between ∼75 and 25 Ma. These results suggest that environmental information can be obtained from magnetofossils in pelagic red clay. © 2017. American Geophysical Union. All Rights Reserved

    OMAE2011-49594 DEVELOPMENT OF 6% NICKEL STEEL FOR LNG STORAGE TANKS

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    ABSTRACT 9% Ni steel has been used for LNG storage tanks for more than four decades although 5.5% Ni steel (N-TUF CR196) was developed in the 1970's using a special heat treatment method named L-treatment. The reason why the actual application of 5.5% Ni steel has not been attained to LNG storage tanks is mainly because the requirement of fracture properties is not confirmed for the tanks. Under the circumstances of expanding demand for natural gas and double-integrity in LNG storage tanks, we restarted developing low Ni steel for LNG storage tanks by using both conventional and advanced techniques. For the application of low Ni steel to the present LNG storage tanks, both fracture initiation and propagation properties of base metal plates and welded joints should be concerned. The fracture initiation and propagation properties of base metal were compensated with the intercritical reheating process (L-treatment), and the propagation property was additionally enhanced by combining TMCP with L-treatment. In addition, the chemical composition adjustment and the homogenization treatment of solute elements were conducted for improving the fracture initiation and propagation properties of welded joints. 6% Ni steel plates were manufactured by the process of continuous casting, reheating, hot rolling, direct quenching (TMCP), L-treatment, and tempering, and their chemical composition was 0.05C-0.06Si-1.0Mn-6.3Ni-Cr-Mo. As the results of fracture property evaluation including large-scale fracture tests such as the duplex ESSO test and the wide plate tensile test, it was demonstrated that 6% Ni steel has good characteristics regarding brittle fracture initiation and propagation in base metal plates and welded joints

    Individual Education Support System Using ICT for Developmental Disabilities

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    Children with developmental disabilities require special support to help them in different aspects of daily life, and individual educational support is a crucial part of such support. We developed a collaborative system for supporting children with developmental disabilities using ICT to be used by teachers, parents, and supporters. This chapter introduces this system, which provides close and immediate support through instantaneously sharing daily behavior information about the child between teacher-parent-supporters. In addition, storing the data in a highly secure cloud system facilitates passing information to children’s next educational level. Moreover, AI can match support needs and support services according to the characteristics of individual children by using ICF codes for suggesting immediate, dynamic support

    Identification of paleomagnetic remanence carriers in ca. 3.47 Ga dacite from the Duffer Formation, the Pilbara Craton

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    金沢大学理工研究域地球社会基盤学系The ca. 3.47 Ga Duffer Formation has been considered to carry one of the oldest paleomagnetic records. Yet, the lack of rock magnetic data limits the interpretation of the nature of the remanence. We conducted a rock magnetic and paleomagnetic investigation on columnar dacite of the Duffer Formation. The main magnetic minerals are phenocrysts of titanomagnetite and magnetite, and secondary hematite in groundmass. Detailed thermal demagnetization revealed more complex natural remanence than previously estimated, consisting of four components with typical unblocking temperature of 200–350, 200–500, 590, and 690 °C. Combined with alternating field demagnetization and rock magnetic data, they are attributed to titanomagnetite, coarse-grained magnetite, fine-grained magnetite, and hematite, respectively. The comparison of unblocking temperature and coercivity suggests that the previously proposed secondary component is carried by fine-grained magnetite as well as hematite, while the putative primary component is carried by coarse-grained magnetite and titanomagnetite. Microscopic observations showed that coarse-grained magnetite and titanomagnetite are primary crystals, although this does not necessarily indicate they preserve primary remanence. The remanence directions of all components revealed higher scatter than the previous studies, suggesting the need for caution in interpretation. The low unblocking temperature of titanomagnetite suggests that if their remanence is truly primary, the rocks must have kept below ~ 250 °C for ~3.47 billion years. © 2020 Elsevier B.V.Embargo Period 24 month
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