University of Tsukuba

About: University of Tsukuba is a education organization based out in Tsukuba, Ibaraki, Japan. It is known for research contribution in the topics: Population & Gene. The organization has 36352 authors who have published 79483 publications receiving 1934752 citations. The organization is also known as: Tsukuba daigaku & Tsukuba University.

Ehd2, a Rice Ortholog of the Maize INDETERMINATE1 Gene, Promotes Flowering by Up-Regulating Ehd1

Abstract: Recent research into the flowering of rice (Oryza sativa) has revealed both unique and conserved genetic pathways in the photoperiodic control of flowering compared with those in Arabidopsis (Arabidopsis thaliana). We discovered an early heading date2 (ehd2) mutant that shows extremely late flowering under both short- and long-day conditions in line with a background deficient in Heading date1 (Hd1), a rice CONSTANS ortholog that belongs to the conserved pathway. This phenotype in the ehd2 mutants suggests that Ehd2 is pivotal for the floral transition in rice. Map-based cloning revealed that Ehd2 encodes a putative transcription factor with zinc finger motifs orthologous to the INDETERMINATE1 (ID1) gene, which promotes flowering in maize (Zea mays). Ehd2 mRNA in rice tissues accumulated most abundantly in developing leaves, but was present at very low levels around the shoot apex and in roots, patterns that are similar to those of ID1. To assign the position of Ehd2 within the flowering pathway of rice, we compared transcript levels of previously isolated flowering-time genes, such as Ehd1, a member of the unique pathway, Hd3a, and Rice FT-like1 (RFT1; rice florigens), between the wild-type plants and the ehd2 mutants. Severely reduced expression of these genes in ehd2 under both short- and long-day conditions suggests that Ehd2 acts as a flowering promoter mainly by up-regulating Ehd1 and by up-regulating the downstream Hd3a and RFT1 genes in the unique genetic network of photoperiodic flowering in rice.

Measurements of higher order flow harmonics in Au+Au collisions at √sNN=200GeV

Abstract: Flow coefficients nu(n) for n = 2, 3, 4, characterizing the anisotropic collective flow in Au + Au collisions at root s(NN) = 200 GeV, are measured relative to event planes Psi(n), determined at large rapidity We report nu(n) as a function of transverse momentum and collision centrality, and study the correlations among the event planes of different order n The nu(n) are well described by hydrodynamic models which employ a Glauber Monte Carlo initial state geometry with fluctuations, providing additional constraining power on the interplay between initial conditions and the effects of viscosity as the system evolves This new constraint can serve to improve the precision of the extracted shear viscosity to entropy density ratio eta/s

Early Metal Enrichment by Pregalactic Outflows. II. Three-dimensional Simulations of Blow-Away

Abstract: Supernova (SN)-driven pregalactic outflows may be an efficient mechanism for distributing the product of stellar nucleosynthesis over large cosmological volumes prior to the reionization epoch. Here, we present results from three-dimensional numerical simulations of the dynamics of SN-driven bubbles as they propagate through and escape the grasp of subgalactic halos with masses M = 108 h-1 M☉ at redshift z = 9. Halos in this mass range are characterized by very short dynamical timescales (and even shorter gas cooling times) and may therefore form stars in a rapid but intense burst before SN "feedback" quenches further star formation. The hydrodynamic simulations use a nested grid method to follow the evolution of explosive multi-SN events operating on the characteristic timescale of a few times 107 yr, the lifetime of massive stars. The results confirm that if the star formation efficiency of subgalactic halos is 10%, a significant fraction of the halo gas will be lifted out of the potential well ("blow-away"), shock the intergalactic medium, and pollute it with metal-enriched material, a scenario recently advocated by Madau, Ferrara, & Rees. The volume filling factor of the ejecta is of order unity. Depending on the stellar distribution, we find that less than 30% of the available SN energy gets converted into kinetic energy of the blown-away material, the remainder being radiated away. It appears that mechanical feedback is less efficient than expected from simple energetic arguments, as off-nuclear SN explosions drive inward-propagating shocks that tend to collect and pile up cold gas in the central regions of the host halo. Low-mass galaxies at early epochs may survive multiple SN events and continue forming stars.

Silicon array of elongated through-holes for monodisperse emulsion droplets

Abstract: Monodisperse emulsions are of great significance in both scientific and industrial fields, since they have advantages such as their better stability and simplified physical properties. A novel micromachined emulsification device has been developed for monodisperse emulsion droplets. It has uniformly sized through-holes, called straightthrough microchannel (MC), on a silicon microchip. An oblong straightthrough MC successfully yielded monodisperse oil-in-water (O/W) emulsion droplets with an average droplet diameter of 32.5 μm and a coefficient of variation below 2% by forcing the dispersed phase into the continuous phase through the straightthrough MC. On the other hand, a circular straightthrough MC yielded polydisperse emulsion droplets. Straightthrough MC emulsification revealed that an elongated cross-sectional shape in the oblong straightthrough MC contributes significantly to the spontaneous formation of monodisperse emulsion droplets without any turbulent mixing.