315 research outputs found

    Interpreting Cytokinin Action as Anterograde Signaling and Beyond

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    Among the major phytohormones, the cytokinin exhibits unique features for its ability to positively affect the developmental status of plastids. Even early on in its research, cytokinins were known to promote plastid differentiation and to reduce the loss of chlorophyll in detached leaves. Since the discovery of the components of cytokinin perception and primary signaling, the genes involved in photosynthesis and plastid differentiation have been identified as those directly targeted by type-B response regulators. Furthermore, cytokinins are known to modulate versatile cellular processes such as promoting the division and differentiation of cells and, in concert with auxin, initiating the de novo formation of shoot apical meristem (SAM) in tissue cultures. Yet how cytokinins precisely participate in such diverse cellular phenomena, and how the associated cellular processes are coordinated as a whole, remains unclear. A plausible presumption that would account for the coordinated gene expression is the tight and reciprocal communication between the nucleus and plastid. The fact that cytokinins affect plastid developmental status via gene expression in both the nucleus and plastid is interpreted here to suggest that cytokinin functions as an initiator of anterograde (nucleus-to-plastid) signaling. Based on this viewpoint, we first summarize the physiological relevance of cytokinins to the coordination of plastid differentiation with de novo shoot organogenesis in tissue culture systems. Next, the role of endogenous cytokinins in influencing plastid differentiation within the SAM of intact plants is discussed. Finally, a presumed plastid-derived signal in response to cytokinins for coupled nuclear gene expression is proposed

    Magnetic-Field-Independent Ultrasonic Dispersions in the Magnetically Robust Heavy Fermion System SmOs4Sb12

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    Elastic properties of the filled skutterudite compound SmOs4_4Sb12_{12} have been investigated by ultrasonic measurements. The elastic constant C11(ω)C_{11}(\omega) shows two ultrasonic dispersions at \sim15 K and \sim53 K for frequencies ω\omega between 33 and 316 MHz, which follow a Debye-type formula with Arrhenius-type temperature-dependent relaxation times, and remain unchanged even with applied magnetic fields up to 10 T. The corresponding activation energies were estimated to be E2E_2 = 105 K and E1E_1 = 409 K, respectively. The latter, E1E_1, is the highest value reported so far in the Sb-based filled skutterudites. The presence of magnetically robust ultrasonic dispersions in SmOs4_4Sb12_{12} implies a possibility that an emergence of a magnetically insensitive heavy fermion state in this system is associated with a novel local charge degree of freedom which causes the ultrasonic dispersion.Comment: 5 pages, 4 figure

    Atomic structure and electronic properties of MgO grain boundaries in tunnelling magnetoresistive devices

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    Polycrystalline metal oxides find diverse applications in areas such as nanoelectronics, photovoltaics and catalysis. Although grain boundary defects are ubiquitous their structure and electronic properties are very poorly understood since it is extremely challenging to probe the structure of buried interfaces directly. In this paper we combine novel plan-view high-resolution transmission electron microscopy and first principles calculations to provide atomic level understanding of the structure and properties of grain boundaries in the barrier layer of a magnetic tunnel junction. We show that the highly [001] textured MgO films contain numerous tilt grain boundaries. First principles calculations reveal how these grain boundaries are associated with locally reduced band gaps (by up to 3 eV). Using a simple model we show how shunting a proportion of the tunnelling current through grain boundaries imposes limits on the maximum magnetoresistance that can be achieved in devices

    The 1988-1989 explosive eruption of Tokachi-dake, central Hokkaido, Its sequence and mode

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    On December 16, 1988, after 26 years of dormancy since the last eruption in 1962, Tokachi-dake began to erupt from the 62-II crater. The eruption started with phreatic explosions. Then, on December 19, the activity changed into phreatomagmatic explosions of Vulcanian type and continued intermittently until March 5, 1989. Although the composition of the essential ejecta, mafic andesite, is similar to those of 1926 and 1962 eruptions, the mode of the present eruption is considerably diffrent The present eruption consists of a series of 23 discrete cannon-like explosions, being frequently accompanied with small-scale pyrcclastic surges and flows. The total volume of ejecta amounts to approximately 6×105 m3, of which about 20% is essential ejecta. A complete sequence of events was compiled and distribution maps of the ash-fall, ballistic blocks, and pyroclastic surges and flows were drawn for each of the larger eruptions. The pyrrolastic surges and flows of the present eruption were small scale, low temperature pyroclastic flows, rich in accessory clasts and unaccompanied by sector collapse. Therefore, the sudden melting of snow causing disastrous mudflows, as in the case of the 1926 eruption, fortunately did not occur

    Pyrogallol inhibits NFAT signal

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    As the expression level of allergic disease sensitive genes are correlated with the severity of allergic symptoms, suppression of these gene expressions could be promising therapeutics. We demonstrated that protein kinase Cδ / heat shock protein 90-mediated H1R gene expression signaling and nuclear factor of activated T-cells (NFAT)-mediated IL-9 gene expression signaling are responsible for the pathogenesis of pollinosis. Treatment with Awa-tea combined with wild grape hot water extract suppressed these signaling and alleviated nasal symptoms in toluene-2,4-diisocyanate (TDI)-sensitized rats. However, the underlying mechanism of its anti-allergic activity is not elucidated yet. Here, we sought to identify an anti-allergic compound from Awa-tea and pyrogallol was identified as an active compound. Pyrogallol strongly suppressed ionomycin-induced up-regulation of IL-9 gene expression in RBL-2H3 cells. Treatment with pyrogallol in combination with epinastine alleviated nasal symptoms and suppressed up-regulation of IL-9 gene expression in TDI-sensitized rats. Pyrogallol itself did not inhibit calcineurin phosphatase activity. However, pyrogallol suppressed ionomycin-induced dephosphorylation and nuclear translocation of NFAT. These data suggest pyrogallol is an anti-allergic compound in Awa-tea and it suppressed NFAT-mediated IL-9 gene expression through the inhibition of dephosphorylation of NFAT. This might be the underlying mechanism of the therapeutic effects of combined therapy of pyrogallol with antihistamine

    Application of CFD to Prediction of Heat Exchanger Temperature and Indoor Airflow Control Simulation in Room Air Conditioner Development

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    In the development of room air conditioners, repeated experiments are conducted to improve product performance. In experiments, temperatures, and air velocities, however, the number and locations of sensors that can be installed in experiments are limited, and it is difficult to estimate the background of a phenomenon based on experimental data alone. Therefore, in design practice, we utilize quantitative verification by CFD in addition to experimental analysis. In this chapter, we describe two CFD models. The first model is a heat exchanger model of an indoor unit that has a cross-flow fan and a heat exchanger. This model is coupled with CFD model and one-dimensional refrigerant flow circuit model. This calculates airflow velocity, temperature, refrigerant flow pressure, and enthalpy. The second model is an indoor airflow model of a room. The room air conditioner can control the temperature and the velocity distribution of airflow in a room, which influences user thermal comfort by controlling the direction, temperature, and volume of airflow by using the indoor unit outlet. This model can predict airflow velocity and temperature in a room

    What is prototypical face of \u27SHOUTOKU TAISHI\u27 ? (1) : Extracting prototypical facial images by means of Projection Pursuit

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    ここに聖徳太子に関する8種類の顔がある。肖像画であったり,像であったり種類もまちまちである。はたして飛鳥時代の聖徳太子はどんな顔をしていたのだろうか?これが,この報告の出発点である。計算機統計学の興味深い手法の中の1つに,射影追跡(Projection pursuit)法がある。これは,多次元データを少次元で表現して情報を集約することによって何らかのデータ構造を探索する。この論文では,聖徳太子に関する8種類の顔イメージデータを対象として,従来の手法と射影追跡との有効性について比較検討を行なった。There are eight kinds of faces concerning the \u27SHOUTOKU TAISHI\u27. The type of faces are various ;portrait, image, atc. I wonder what prototypical facial image of \u27SHOUTOKU TAISHI\u27 in the Asuka age really had. This is a starting point of this report. One of the interesting techniques of Computational Statistics study is Projection Pursuit method. This method explores some data structures by representing multidimensional data by a lower dimension and consolidating information. In this paper, the comparison examination of an classical technique and effectiveness with the projection pursuit was done for eight kinds of face image data concerning the \u27SHOUTOKU TAISHI\u27

    Orbital apex syndrome associated with herpes zoster ophthalmicus

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    We report our findings for a patient with orbital apex syndrome associated with herpes zoster ophthalmicus. Our patient was initially admitted to a neighborhood hospital because of nausea and loss of appetite of 10 days’ duration. The day after hospitalization, she developed skin vesicles along the first division of the trigeminal nerve, with severe lid swelling and conjunctival injection. On suspicion of meningoencephalitis caused by varicella zoster virus, antiviral therapy with vidarabine and betamethasone was started. Seventeen days later, complete ptosis and ophthalmoplegia developed in the right eye. The light reflex in the right eye was absent and anisocoria was present, with the right pupil larger than the left. Fat-suppressed enhanced T1-weighted magnetic resonance images showed high intensity areas in the muscle cone, cavernous sinus, and orbital optic nerve sheath. Our patient was diagnosed with orbital apex syndrome, and because of skin vesicles in the first division of the trigeminal nerve, the orbital apex syndrome was considered to be caused by herpes zoster ophthalmicus. After the patient was transferred to our hospital, prednisolone 60 mg and vidarabine antiviral therapy was started, and fever and headaches disappeared five days later. The ophthalmoplegia and optic neuritis, but not the anisocoria, gradually resolved during tapering of oral therapy. From the clinical findings and course, the cause of the orbital apex syndrome was most likely invasion of the orbital apex and cavernous sinus by the herpes virus through the trigeminal nerve ganglia
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