731 research outputs found

    Narrow Leaf Mutants in the Grass Family

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    Leaf morphology is critical for the survival of plant species. After a leaf primordium is initiated at the flank of shoot apical meristem (SAM), the development along the medial‐lateral direction enlarges the leaf‐blades, leading to the increase of photosynthetic activities. Thus, the revelation of mechanisms that control development across a leaf is quite important for plant breeding. A variety of narrow leaf mutants have been identified in the grass family, which includes particularly important crops in the world. Here, the molecular mechanisms underlying the leaf development in the medial‐lateral direction are discussed as we introduce the three major groups of narrow leaf mutants in the grass family: (1) auxin‐related mutants, (2) cellulose synthase‐like D (CSLD)‐related mutants, and (3) polarity‐related mutants. The results obtained from these analyses could be directly applied to the breeding of major cereal crops such as maize, rice, and barley; therefore, they could contribute to the increase of food production

    Non-equilibrium Ionization State of Warm-Hot Intergalactic Medium

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    Time evolution of the ionization state of metals in the cosmic baryons is investigated in a cosmological context without the assumption of ionization equilibrium. We find that a significant fraction of ionized oxygen ions (OVII and OVIII) in the warm-hot intergalactic medium (WHIM) is not in the ionization equilibrium state at a redshift of z~0. We also investigate the effect on the detectability and observables of WHIM as a consequence of such deviation from ionization equilibrium. It is found that the detectability of WHIM is not altered very much both through its emission and absorption signatures, but line ratios between OVII and OVIII are significantly different from those in the ionization equilibrium state.Comment: 25 pages, 18 figures, accepted for publication in PAS

    Temporal change in rock-magnetic properties of volcanic ashes ejected during a 1-year eruption event: a case study on the Aso Nakadake 2019-2020 eruption

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    We investigated temporal changes in the rock-magnetic properties of volcanic ash ejected from the Aso Nakadake volcano during a sequence of ash eruptions from 2019 to 2020. For 39 volcanic ash samples, magnetic hysteresis parameters, including saturation magnetization (M-s), saturation remanent magnetization (M-rs), coercivity (B-c), and coercivity of remanence (B-cr), were obtained. Curie temperature (T-c) of the samples was also estimated using thermomagnetic analyses. Titanium-rich and -poor titanomagnetites were the dominant magnetic minerals in the volcanic ash, of which the titanium-rich phase was dominant. Systematic magnetic measurements of the volcanic ash ejected during the 1-year eruption event indicate that temporal changes in the hysteresis parameters occurred throughout the event. These temporal changes suggest that the M-rs/M-s and B-c values of the volcanic ash increased considerably during several periods. The clear increases in M-rs/M-s and B-c, associated with the central peak in FORC diagrams, indicate that non-interacting single-domain grains increased. For these high M-rs/M-s and B-c samples, thermal demagnetizations of 3-axis IRM show that the low unblocking-temperature component up to 250-300 & DEG;C has apparently higher coercivity, suggesting that the above-mentioned, non-interacting single-domain grains are Ti-rich titanomagnetite. Interestingly, the high M-rs/M-s and B-c values were synchronous with observations of volcanic glow. These results suggest that changes in the magnetic properties of titanomagnetite grains in volcanic ash reflect changes in physical conditions from the vent to the conduit of the volcano

    Systematic Errors in the Hubble Constant Measurement from the Sunyaev-Zel'dovich effect

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    The Hubble constant estimated from the combined analysis of the Sunyaev-Zel'dovich effect and X-ray observations of galaxy clusters is systematically lower than those from other methods by 10-15 percent. We examine the origin of the systematic underestimate using an analytic model of the intracluster medium (ICM), and compare the prediction with idealistic triaxial models and with clusters extracted from cosmological hydrodynamical simulations. We identify three important sources for the systematic errors; density and temperature inhomogeneities in the ICM, departures from isothermality, and asphericity. In particular, the combination of the first two leads to the systematic underestimate of the ICM spectroscopic temperature relative to its emission-weighed one. We find that these three systematics well reproduce both the observed bias and the intrinsic dispersions of the Hubble constant estimated from the Sunyaev-Zel'dovich effect.Comment: 26 pages, 7 figures, accepted for publication in ApJ, Minor change

    Shape-preserving diffusion of a high-order mode

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    The close relation between the processes of paraxial diffraction and coherent diffusion is reflected in the similarity between their shape-preserving solutions, notably the Gaussian modes. Differences between these solutions enter only for high-order modes. Here we experimentally study the behavior of shape-preserving high-order modes of coherent diffusion, known as 'elegant' modes, and contrast them with the non-shape-preserving evolution of the corresponding 'standard' modes of optical diffraction. Diffusion of the light field is obtained by mapping it onto the atomic coherence field of a diffusing vapor in a storage-of-light setup. The growth of the elegant mode fits well the theoretical expectations

    A nonlinear parametric model based on a power law relationship for predicting the coastal tsunami height

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    When a subduction-zone earthquake occurs, the tsunami height must be predicted to cope with the damage generated by the tsunami. Therefore, tsunami height prediction methods have been studied using simulation data acquired by large-scale calculations. In this research, we consider the existence of a nonlinear power law relationship between the water pressure gauge data observed by the Dense Oceanfloor Network System for Earthquakes and Tsunamis (DONET) and the coastal tsunami height. Using this relationship, we propose a nonlinear parametric model and conduct a prediction experiment to compare the accuracy of the proposed method with those of previous methods and implement particular improvements to the extrapolation accuracy

    Chemo-Sensitive Running Droplet

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    Chemical control of the spontaneous motion of a reactive oil droplet moving on a glass substrate under an aqueous phase is reported. Experimental results show that the self-motion of an oil droplet is confined on an acid-treated glass surface. The transient behavior of oil-droplet motion is also observed with a high-speed video camera. A mathematical model that incorporates the effect of the glass surface charge is built based on the experimental observation of oil-droplet motion. A numerical simulation of this mathematical model reproduced the essential features concerning confinement within a certain chemical territory of oil-droplet motion, and also its transient behavior. Our results may shed light on physical aspects of reactive spreading and a chemotaxis in living things.Comment: 17 pages, 10 figure

    Induction of neuron-like tubes and liposome networks by cooperative effect of gangliosides and phospholipids

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    AbstractAlthough there is a rather large abundance of gangliosides in neurons, their functional role is still unclear. We focused on a physicochemical role of gangliosides in the formation of tubular structures, such as axons or dendrites in neurons. When a ganglioside, GM3, was added to cell-size liposomes that consisted of dioleoylphosphatidyl-choline, tubular structures were induced and liposome networks connected by the tubes were observed by differential interference microscopy and fluorescence microscopy. The potential for various gangliosides to induce tubes was dependent on the structures of their hydrophilic head group. With a large excess of gangliosides, the tubes are destabilized and small fragments, or micelles, are generated. The phenomenon was suggested by physical model calculation. Gangliosides may play a role as building material in neural unique tubular structures
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