83 research outputs found

    High-pressure xenon gas time projection chamber with scalable design and its performance at around the Q value of 136^{136}Xe double-beta decay

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    We have been developing a high-pressure xenon gas time projection chamber (TPC) to search for neutrinoless double beta (0νββ0\nu\beta\beta) decay of 136^{136}Xe. The unique feature of this TPC is in the detection part of ionization electrons, called ELCC. ELCC is composed of multiple units, and one unit covers 48.5 cm2\mathrm{cm}^2. A 180 L size prototype detector with 12 units, 672 channels, of ELCC was constructed and operated with 7.6 bar natural xenon gas to evaluate the performance of the detector at around the Q value of 136^{136}Xe 0νββ0\nu\beta\beta. The obtained FWHM energy resolution is (0.73 ±\pm 0.11) % at 1836 keV. This corresponds to (0.60 ±\pm 0.03) % to (0.70 ±\pm 0.21) % of energy resolution at the Q value of 136Xe^{136}Xe 0νββ0\nu\beta\beta. This result shows the scalability of the AXEL detector with ELCC while maintaining high energy resolution. Factors determining the energy resolution were quantitatively evaluated and the result indicates further improvement is feasible. Reconstructed track images show distinctive structures at the endpoint of electron tracks, which will be an important feature to distinguish 0νββ0\nu\beta\beta signals from gamma-ray backgrounds.Comment: 33 pages, 24 figures, preprint accepted by PTE

    Activin signaling as an emerging target for therapeutic interventions

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    After the initial discovery of activins as important regulators of reproduction, novel and diverse roles have been unraveled for them. Activins are expressed in various tissues and have a broad range of activities including the regulation of gonadal function, hormonal homeostasis, growth and differentiation of musculoskeletal tissues, regulation of growth and metastasis of cancer cells, proliferation and differentiation of embryonic stem cells, and even higher brain functions. Activins signal through a combination of type I and II transmembrane serine/threonine kinase receptors. Activin receptors are shared by multiple transforming growth factor-β (TGF-β) ligands such as myostatin, growth and differentiation factor-11 and nodal. Thus, although the activity of each ligand is distinct, they are also redundant, both physiologically and pathologically in vivo. Activin receptors activated by ligands phosphorylate the receptor-regulated Smads for TGF-β, Smad2 and 3. The Smad proteins then undergo multimerization with the co-mediator Smad4, and translocate into the nucleus to regulate the transcription of target genes in cooperation with nuclear cofactors. Signaling through receptors and Smads is controlled by multiple mechanisms including phosphorylation and other posttranslational modifications such as sumoylation, which affect potein localization, stability and transcriptional activity. Non-Smad signaling also plays an important role in activin signaling. Extracellularly, follistatin and related proteins bind to activins and related TGF-β ligands, and control the signaling and availability of ligands

    Robot-Assisted Eccentric Contraction Training of the Tibialis Anterior Muscle Based on Position and Force Sensing

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    The purpose of this study was to determine the clinical effects of a training robot that induced eccentric tibialis anterior muscle contraction by controlling the strength and speed. The speed and the strength are controlled simultaneously by introducing robot training with two different feedbacks: velocity feedback in the robot controller and force bio-feedback based on force visualization. By performing quantitative eccentric contraction training, it is expected that the fall risk reduces owing to the improved muscle function. Evaluation of 11 elderly participants with months training period was conducted through a cross-over comparison test. The results of timed up and go (TUG) tests and 5 m walking tests were compared. The intergroup comparison was done using the Kruskal-Wallis test. The results of cross-over test indicated no significant difference between the 5-m walking time measured after the training and control phases. However, there was a trend toward improvement, and a significant difference was observed between the training and control phases in all subjects

    IMPLANTABLE GLUCOSE SENSOR - PROBLEMS AWAITING SOLUTIONS FOR LONG-TERM CLINICAL APPLICATION

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    We developed an indwelling, exchangeable and disposable glucose sensor. For preserving excellent in vivo characteristics and extending sensor longevity, the most crucial points are the elegant membrane design and the software backup system. We have developed a band path filter, which was effective in eliminating several types of electrical noises evoked by muscle works or electrical disturbances. The new glucose sensor covered by alginate-polylysine-alginate membrane as a biocompatible one could preserve the sensor activity for 14 days after implantation in subcutaneous tissue of normal dogs. These data indicated that further improvements in membrane design might augment the long-term clinical applicability of glucose sensor

    MEMBRANE DESIGN OF GLUCOSE SENSOR FOR LONG-TERM CLINICAL USE - APPLICATION OF ALGINATE-POLYLYSINE-ALGINATE MEMBRANE -

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    For extending sensor longevity, we coated the alginate-polylysinealginate membrane on the needle-type glucose sensor. The glucose sensor could determine the whole blood glucose concentration directly and preserve the sensor activity for 14 days after implantation. These data indicated that further improvements in membrane design might augment the long-term clinical applicability of glucose sensor
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