AIP Publishing Acta Medica Okayama 1070-6631 36 3 2024 Effect of non-local near-resonant interactions of Rossby waves on formation of large-scale zonal flows in unforced two-dimensional turbulence on rotating sphere 036617 EN Yusuke Hagimori Graduate School of Environmental, Life, Natural Science and Technology, Okayama University Kiori Obuse Graduate School of Environmental, Life, Natural Science and Technology, Okayama University Michio Yamada Research Institute for Mathematical Sciences, Kyoto University This study investigates the effect of nonlinear interactions of Rossby waves on large-scale zonal flow formation in two-dimensional turbulence on a rotating sphere. The coefficients of nonlinear interactions are first calculated. Then, the non-local, near-resonant, and non-local near-resonant interactions are investigated in detail. The results show that the formation of large-scale westward circumpolar zonal flows is directly caused by non-local energy transfer due to the three-wave near-resonant interactions of Rossby waves. No potential conflict of interest relevant to this article was reported.

Physical Society of Japan Acta Medica Okayama 0031-9015 89 6 2020 Energy Transfer to Resonant Zonal Rossby Modes in Two-Dimensional Turbulence on a Rotating Sphere 064401 EN Kiori Obuse Graduate School of Environmental and Life Science, Okayama University Michio Yamada Research Institute for Mathematical Sciences, Kyoto University The transfer of energy by the nonlinear interaction of Rossby waves in two-dimensional turbulence on a rotating sphere was investigated in this study. Although it has been suggested that three-wave resonant interaction dominates nonlinear interactions when the rotation rate of the sphere is sufficiently high, resonant interactions do not transfer energy to zonal Rossby waves, resulting in the nonresonant interaction of Rossby waves being responsible for the generation of zonal flows [Reznik, Piterbarg, and Kartashova, Dyn. Atmos. Oceans 18, 235 (1993); Obuse and Yamada, Phys. Rev. Fluids 4, 024601 (2019)]. The resonant and nonresonant interactions of Rossby waves were investigated in this study, and it was found that although energy is transferred to the zonal Rossby modes by the nonresonant three-wave interaction of Rossby waves, the target of this nonresonant energy transfer is only the resonant zonal Rossby waves. No potential conflict of interest relevant to this article was reported.

Springer Acta Medica Okayama 1436-2228 2020 Comparative Gene Analysis Focused on Silica Cell Wall Formation: Identification of Diatom-Specific SET Domain Protein Methyltransferases EN Michiko Nemoto Graduate School of Environmental and Life Science, Okayama University Sayako Iwaki Graduate School of Environmental and Life Science, Okayama University Hisao Moriya Graduate School of Environmental and Life Science, Okayama University Yuki Monden Graduate School of Environmental and Life Science, Okayama University Takashi Tamura Graduate School of Environmental and Life Science, Okayama University Kenji Inagaki Graduate School of Environmental and Life Science, Okayama University Shigeki Mayama Department of Biology, Tokyo Gakugei University Kiori Obuse Graduate School of Environmental and Life Science, Okayama University Silica cell walls of diatoms have attracted attention as a source of nanostructured functional materials and have immense potential for a variety of applications. Previous studies of silica cell wall formation have identified numerous involved proteins, but most of these proteins are species-specific and are not conserved among diatoms. However, because the basic process of diatom cell wall formation is common to all diatom species, ubiquitous proteins and molecules will reveal the mechanisms of cell wall formation. In this study, we assembled de novo transcriptomes of three diatom species, Nitzschia palea, Achnanthes kuwaitensis, and Pseudoleyanella lunata, and compared protein-coding genes of five genome-sequenced diatom species. These analyses revealed a number of diatom-specific genes that encode putative endoplasmic reticulum-targeting proteins. Significant numbers of these proteins showed homology to silicanin-1, which is a conserved diatom protein that reportedly contributes to cell wall formation. These proteins also included a previously unrecognized SET domain protein methyltransferase family that may regulate functions of cell wall formation-related proteins and long-chain polyamines. Proteomic analysis of cell wall-associated proteins in N. palea identified a protein that is also encoded by one of the diatom-specific genes. Expression analysis showed that candidate genes were upregulated in response to silicon, suggesting that these genes play roles in silica cell wall formation. These candidate genes can facilitate further investigations of silica cell wall formation in diatoms. No potential conflict of interest relevant to this article was reported.

American Physical Society Acta Medica Okayama 2469990X 4 2 2019 Three-wave resonant interactions and zonal flows in two-dimensional Rossby-Haurwitz wave turbulence on a rotating sphere 024601 EN Kiori Obuse 1Graduate School of Environmental and Life Science, Okayama University Michio Yamada Research Institute for Mathematical Sciences, Kyoto University This paper addresses three-wave resonant interactions of Rossby-Haurwitz waves in two-dimensional turbulence on a rotating sphere. Zonal modes are often omitted from the "resonant wave set" even when they satisfy the conditions for three-wave resonant interactions, as they do not transfer any energy to other modes in a resonant manner. However, the presence of zonal flows induces phase shifts in other modes, and it is not at all clear that their influence is negligible. Since it is expected that three-wave resonant interactions govern the entire dynamics of turbulence if the rotation rate of the sphere is sufficiently high, by analogy with the theorem regarding three-wave resonant interactions of Rossby waves on a beta plane with sufficiently large beta previously proven by Yamada and Yoneda [Physica D 245, 1 (2013)], an appropriate definition of the resonant wave set was determined by comparing the time evolution of several wave sets on a rapidly rotating sphere. It was found that zonal waves of the form Y-l(m=0) exp(i omega t) with odd l, where Y(l)(m )are the spherical harmonics, should be considered for inclusion in the resonant wave set to ensure that the dynamics of the resonant wave set determine the overall dynamics of the turbulence on a rapidly rotating sphere. Consequently, it is suggested that the minimal resonant wave set that must be considered in the discussion of the three-wave interaction of Rossby-Haurwitz waves is the set consisting of nonzonal resonant waves and zonal waves of the form Y-l(0) exp(icot) with odd l. No potential conflict of interest relevant to this article was reported.