126 research outputs found

    A Beam Focusing Antenna for the TE(0)n Mode High-Power Millimeter Wave

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    This paper describes a method to design an antenna to focus millimeter-wave beam generated by a gyrotron. The antenna, which has been proposed by the authors, consists of a stair-cut circular waveguide and two cylindrical reflectors; one is elliptic and the other is parabolic. Its principle is based on the geometrical optics though slightly modified to consider the diffraction effect. Results of low-power experiments agree well with the design on beam direction, beam width and the position of the focal point. At 35.5 GHz using TE(01) mode, a focused beam with half-power thickness of 13 mm x 10 mm was obtained. This type of antennas find applications to millimeter-wave scattering measurement in fusion plasma research and high- energy-density source for material heating

    Shining light on the function of NPH3/RPT2-like proteins in phototropin signalling

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    Palisade cell shape affects the light-induced chloroplast movements and leaf photosynthesis

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    Leaf photosynthesis is regulated by multiple factors that help the plant to adapt to fluctuating light conditions. Leaves of sun-light-grown plants are thicker and contain more columnar palisade cells than those of shade-grown plants. Light-induced chloroplast movements are also essential for efficient leaf photosynthesis and facilitate efficient light utilization in leaf cells. Previous studies have demonstrated that leaves of most of the sun-grown plants exhibited no or very weak chloroplast movements and could accomplish efficient photosynthesis under strong light. To examine the relationship between palisade cell shape, chloroplast movement and distribution, and leaf photosynthesis, we used an Arabidopsis thaliana mutant, angustifolia (an), which has thick leaves that contain columnar palisade cells similar to those in the sun-grown plants. In the highly columnar cells of an mutant leaves, chloroplast movements were restricted. Nevertheless, under white light condition (at 120 µmol m-2 s-1), the an mutant plants showed higher chlorophyll content per unit leaf area and, thus, higher light absorption by the leaves than the wild type, which resulted in enhanced photosynthesis per unit leaf area. Our findings indicate that coordinated regulation of leaf cell shape and chloroplast movement according to the light conditions is pivotal for efficient leaf photosynthesis

    Simple and straightforward construction of a mouse gene targeting vector using in vitro transposition reactions

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    In a gene targeting experiment, the generation of a targeting construct often requires complex DNA manipulations. We developed a set of cassettes and plasmids useful for creating targeting vectors to modify the mammalian genome. A positive selection marker cassette (PGK/EM7p-npt), which included dual prokaryotic and eukaryotic promoters to permit consecutive selection for recombination in Escherichia coli and then in mouse embryonic stem cells, was flanked by two FRT-loxP sequences. The PGK/EM7p-npt cassette was placed between the minimum regions of a Tn7 transposable element for insertion into another DNA by means of Tn7 transposase in vitro. We also constructed a plasmid having a loxP-Zeo-loxP cassette between the modified Tn5 outer elements. These cassettes can be integrated randomly into a given genomic DNA through the in vitro transposition reaction, thus producing a collection of genomic segments flanked by loxP sites (floxed) at various positions without the use of restriction enzymes and DNA ligase. We confirmed that this system remarkably reduced the time and labor for the construction of complex gene targeting vectors

    Luminal acidification of diverse organelles by V-ATPase in animal cells

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    Eukaryotic cells contain organelles bounded by a single membrane in the cytoplasm. These organelles have differentiated to carry out various functions in the pathways of endocytosis and exocytosis. Their lumina are acidic, with pH ranging from 4.5 to 6.5. This article describes recent studies on these animal cell organelles focusing on (1) the primary proton pump (vacuolar-type H+-ATPase) and (2) the functions of the organelle luminal acidity. We also discuss similarities and differences between vacuolar-type H+-ATPase and F-type ATPase. Our own studies and interests are emphasized

    RPT2/NCH1 subfamily of NPH3-like proteins is essential for the chloroplast accumulation response in land plants

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    葉緑体が光に集まる反応を制御する新たな因子の発見. 京都大学プレスリリース. 2016-08-30.In green plants, the blue light receptor kinase phototropin mediates various photomovements and developmental responses, such as phototropism, chloroplast photorelocation movements (accumulation and avoidance), stomatal opening, and leaf flattening, which facilitate photosynthesis. In Arabidopsis, two phototropins (phot1 and phot2) redundantly mediate these responses. Two phototropin-interacting proteins, NONPHOTOTROPIC HYPOCOTYL 3 (NPH3) and ROOT PHOTOTROPISM 2 (RPT2), which belong to the NPH3/RPT2-like (NRL) family of BTB (broad complex, tramtrack, and bric à brac) domain proteins, mediate phototropism and leaf flattening. However, the roles of NRL proteins in chloroplast photorelocation movement remain to be determined. Here, we show that another phototropin-interacting NRL protein, NRL PROTEIN FOR CHLOROPLAST MOVEMENT 1 (NCH1), and RPT2 redundantly mediate the chloroplast accumulation response but not the avoidance response. NPH3, RPT2, and NCH1 are not involved in the chloroplast avoidance response or stomatal opening. In the liverwort Marchantia polymorpha, the NCH1 ortholog, MpNCH1, is essential for the chloroplast accumulation response but not the avoidance response, indicating that the regulation of the phototropin-mediated chloroplast accumulation response by RPT2/NCH1 is conserved in land plants. Thus, the NRL protein combination could determine the specificity of diverse phototropin-mediated responses

    Can the liver with Gilbert's syndrome be used as graft of living-related liver transplantation?

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    Gilbert’s syndrome is the common cause of non hemolytic unconjugated hyperbilirubinemia with a prevalance of 3~7%. Gilbert’s syndrome may introduce a selection of potential liver donors from brain death patients. We present a case of living-related liver transplantation (LRLT) from a donor with Gilbert’s syndrome. A 22-year-old woman had been diagnosed as having liver cirrhosis at the age of 5. She underwent liver transplantation with the donor’s left lobe as the graft. The donor, who was the father of the patient, had been diagnosed with Gilbert’s syndrome. Although the recipient was well until 11 months after surgery, she died of subacute fulminant hepatitis 16 months after surgery. However, it was clear that the liver with Gilbert’s syndrome could be used as a graft of living-related liver transplantation for adult recipients

    Effect of intermittent liver ischemia on outcome in patients with hepatocellular carcinoma on liver cirrhosis

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    The influence on postoperative liver function of intermittent normothermic hepatic ischemia in cirrhotic patients was studied retrospectively. The mean total ischemia time was 88 (range30 - 140) minutes in the hemi-hepatic occlusion group, and68 (range 10 - 187) minutes in the total occlusion group. There were no operative deaths due to hepatic failure. Postoperative liver function improved within 1 week of the opera-tion. There was no significant difference in the incidence of postoperative complications between the groups. Thus normothermic hepatic ischemia is tolerated for up to 180minutes in the cirrhotic liver when an intermittent technique (15 minutes clamped and5 minutes unclamped) is used
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