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http://hdl.handle.net/2115/116
2021-09-18T08:50:01ZWidespread Tissintite in Strongly Shock-Lithified Lunar Regolith Breccias
http://hdl.handle.net/2115/82680
Title: Widespread Tissintite in Strongly Shock-Lithified Lunar Regolith Breccias
Authors: Zhang, Ai-Cheng; Jiang, Qin-Ting; Tomioka, Naotaka; Guo, Yan-Jun; Chen, Jia-Ni; Li, Yang; Sakamoto, Naoya; Yurimoto, Hisayoshi
Abstract: Shock-lithification is a fundamental process of making rocks from fine-grained and porous regoliths on the surface of the Moon. Previous investigations have constrained potential shock pressures during shock-lithification based on experimental and numerical simulations. However, pressure and temperature conditions during shock-lithification have not been directly inferred from natural lunar breccias. Here, we report the discovery of widespread tissintite in strongly shock-lithified lunar meteorites, accompanied occasionally by Si-rich corundum and coesite. The coexistence of tissintite and coesite and the absence of stishovite in molten regions indicate a shock pressure of 4-8 GPa, which might be the pressure boundary between weak and strong shock-lithification. Meanwhile, the presence of Si-rich corundum imposes a temperature constraint of similar to 2,300 K for the intergranular melts. This temperature constraint has profound significance for interpreting the behaviors of volatile and moderately volatile elements and remanent magnetization records during strongly shock-lithification of lunar breccias.2021-03-15T15:00:00ZZhang, Ai-ChengJiang, Qin-TingTomioka, NaotakaGuo, Yan-JunChen, Jia-NiLi, YangSakamoto, NaoyaYurimoto, HisayoshiShock-lithification is a fundamental process of making rocks from fine-grained and porous regoliths on the surface of the Moon. Previous investigations have constrained potential shock pressures during shock-lithification based on experimental and numerical simulations. However, pressure and temperature conditions during shock-lithification have not been directly inferred from natural lunar breccias. Here, we report the discovery of widespread tissintite in strongly shock-lithified lunar meteorites, accompanied occasionally by Si-rich corundum and coesite. The coexistence of tissintite and coesite and the absence of stishovite in molten regions indicate a shock pressure of 4-8 GPa, which might be the pressure boundary between weak and strong shock-lithification. Meanwhile, the presence of Si-rich corundum imposes a temperature constraint of similar to 2,300 K for the intergranular melts. This temperature constraint has profound significance for interpreting the behaviors of volatile and moderately volatile elements and remanent magnetization records during strongly shock-lithification of lunar breccias.Soft supersymmetry breaking terms and lepton flavor violations in modular flavor models
http://hdl.handle.net/2115/82664
Title: Soft supersymmetry breaking terms and lepton flavor violations in modular flavor models
Authors: Kobayashi, Tatsuo; Shimomura, Takashi; Tanimoto, Morimitsu
Abstract: We study the soft supersymmetry (SUSY) breaking terms due to the modulus F-term in the modular flavor models of leptons. It is found that the soft SUSY breaking terms are constrained by the modular forms, and specific patterns are derived. Those phenomenological implications are discussed in such as the lepton flavor violation mu -> e + gamma and mu -> 3e decays and mu -> e conversion in nuclei. In order to examine numerically, two modular flavor A4 models are taken. The SUSY breaking scale is significantly constrained by inputting the observed upper bound of the mu -> e +gamma decay. The SUSY mass scale is larger than around 8 TeV and 5 TeV for the two A4 models, respectively. Therefore, the current experimental upper bound for the mu -> e + gamma decay corresponds to the new physics of the SUSY particle at the 5-10 TeV scale in the modular flavor models. The SUSY scale will be explored by future experiments of lepton flavor violation up to 8 - 17 TeV. The predicted branching ratio depends on a modulus tau significantly. It decreases of one order at the large Im tau. We also calculate the branching ratios of tauon decays to e + gamma and mu + gamma. Predicted ones are at most O(10(-15)), which are much below the current experimental bounds. (C) 2021 The Author(s). Published by Elsevier B.V.2021-08-09T15:00:00ZKobayashi, TatsuoShimomura, TakashiTanimoto, MorimitsuWe study the soft supersymmetry (SUSY) breaking terms due to the modulus F-term in the modular flavor models of leptons. It is found that the soft SUSY breaking terms are constrained by the modular forms, and specific patterns are derived. Those phenomenological implications are discussed in such as the lepton flavor violation mu -> e + gamma and mu -> 3e decays and mu -> e conversion in nuclei. In order to examine numerically, two modular flavor A4 models are taken. The SUSY breaking scale is significantly constrained by inputting the observed upper bound of the mu -> e +gamma decay. The SUSY mass scale is larger than around 8 TeV and 5 TeV for the two A4 models, respectively. Therefore, the current experimental upper bound for the mu -> e + gamma decay corresponds to the new physics of the SUSY particle at the 5-10 TeV scale in the modular flavor models. The SUSY scale will be explored by future experiments of lepton flavor violation up to 8 - 17 TeV. The predicted branching ratio depends on a modulus tau significantly. It decreases of one order at the large Im tau. We also calculate the branching ratios of tauon decays to e + gamma and mu + gamma. Predicted ones are at most O(10(-15)), which are much below the current experimental bounds. (C) 2021 The Author(s). Published by Elsevier B.V.Two secured FACT recruitment mechanisms are essential for heterochromatin maintenance
http://hdl.handle.net/2115/82663
Title: Two secured FACT recruitment mechanisms are essential for heterochromatin maintenance
Authors: Takahata, Shinya; Chida, Saori; Ohnuma, Aoi; Ando, Motoyoshi; Asanuma, Takahiro; Murakami, Yota
Abstract: FACT (facilitate chromatin transcription) is involved in heterochromatic silencing, but its mechanisms and function remain unclear. We reveal that the Spt16 recruitment mechanism operates in two distinct ways in heterochromatin. First, Pob3 mediates Spt16 recruitment onto the heterochromatin through its Spt16 dimerization and tandem PH domains. Without Pob3, Spt16 recruitment is partially reduced, exhibiting a silencing defect and impaired H2A/H2B organization. Second, heterochromatin protein 1 (HP1)/Swi6 mediates Spt16 recruitment onto the heterochromatin by physical interaction of the Swi6 chromo-shadow domain (CSD) and Spt16 peptidase-like domains. Several CSD mutants are tested for Spt16 binding activity, and the charged loop connecting beta 1 and beta 2 is critical for Spt16 binding and heterochromatic silencing. Loss of these pathways causes a severe defect in H3K9 methylation and HP1/Swi6 localization in the pericentromeric region, exhibiting transcriptional silencing defects and disordered heterochromatin. Our findings suggest that FACT and HP1/Swi6 work intimately to regulate heterochromatin organization.2021-08-16T15:00:00ZTakahata, ShinyaChida, SaoriOhnuma, AoiAndo, MotoyoshiAsanuma, TakahiroMurakami, YotaFACT (facilitate chromatin transcription) is involved in heterochromatic silencing, but its mechanisms and function remain unclear. We reveal that the Spt16 recruitment mechanism operates in two distinct ways in heterochromatin. First, Pob3 mediates Spt16 recruitment onto the heterochromatin through its Spt16 dimerization and tandem PH domains. Without Pob3, Spt16 recruitment is partially reduced, exhibiting a silencing defect and impaired H2A/H2B organization. Second, heterochromatin protein 1 (HP1)/Swi6 mediates Spt16 recruitment onto the heterochromatin by physical interaction of the Swi6 chromo-shadow domain (CSD) and Spt16 peptidase-like domains. Several CSD mutants are tested for Spt16 binding activity, and the charged loop connecting beta 1 and beta 2 is critical for Spt16 binding and heterochromatic silencing. Loss of these pathways causes a severe defect in H3K9 methylation and HP1/Swi6 localization in the pericentromeric region, exhibiting transcriptional silencing defects and disordered heterochromatin. Our findings suggest that FACT and HP1/Swi6 work intimately to regulate heterochromatin organization.Complex scaling: Physics of unbound light nuclei and perspective
http://hdl.handle.net/2115/82635
Title: Complex scaling: Physics of unbound light nuclei and perspective
Authors: Myo, Takayuki; Katō, Kiyoshi
Abstract: The complex scaling method (CSM) is one of the most powerful methods of describing the resonances with complex energy eigenstates based on non-Hermitian quantum mechanics. We present the basic application of CSM to the properties of the unbound phenomena of light nuclei. In particular, we focus on many-body resonant and non-resonant continuum states observed in unstable nuclei. We also investigate the continuum level density (CLD) in the scattering problem in terms of the Green’s function with CSM. We discuss the explicit effects of resonant and non-resonant contributions in CLD and transition strength functions.2020-11-30T15:00:00ZMyo, TakayukiKatō, KiyoshiThe complex scaling method (CSM) is one of the most powerful methods of describing the resonances with complex energy eigenstates based on non-Hermitian quantum mechanics. We present the basic application of CSM to the properties of the unbound phenomena of light nuclei. In particular, we focus on many-body resonant and non-resonant continuum states observed in unstable nuclei. We also investigate the continuum level density (CLD) in the scattering problem in terms of the Green’s function with CSM. We discuss the explicit effects of resonant and non-resonant contributions in CLD and transition strength functions.Decomposition of scattering phase shifts of coupled-channels systems in the complex scaling method
http://hdl.handle.net/2115/82633
Title: Decomposition of scattering phase shifts of coupled-channels systems in the complex scaling method
Authors: Odsuren, Myagmarjav; Myo, Takayuki; Kikuchi, Yuma; Teshigawara, Manabu; Kato, Kiyoshi
Abstract: The decomposition of scattering phase shifts in single-channel systems is extended to coupled-channels systems in the complex scaling method. The present method describes the contribution of the resonant states to the phase shift separately from the background in each channel phase shift of the coupled-channels system. We apply this method to the (H-3 + p) + (He-3 + n) model for He-4, and show that the decomposition of phase shifts in coupled-channels systems provides useful information about the structure of scattering states.2021-07-29T15:00:00ZOdsuren, MyagmarjavMyo, TakayukiKikuchi, YumaTeshigawara, ManabuKato, KiyoshiThe decomposition of scattering phase shifts in single-channel systems is extended to coupled-channels systems in the complex scaling method. The present method describes the contribution of the resonant states to the phase shift separately from the background in each channel phase shift of the coupled-channels system. We apply this method to the (H-3 + p) + (He-3 + n) model for He-4, and show that the decomposition of phase shifts in coupled-channels systems provides useful information about the structure of scattering states.Electron self-energy from quantum charge fluctuations in the layered t-J model with long-range Coulomb interaction
http://hdl.handle.net/2115/82622
Title: Electron self-energy from quantum charge fluctuations in the layered t-J model with long-range Coulomb interaction
Authors: Yamase, Hiroyuki; Bejas, Matias; Greco, Andres
Abstract: Employing a large-N scheme of the layered t-J model with the long-range Coulomb interaction, which captures the fine details of the charge excitation spectra recently observed in cuprate superconductors, we explore the role of charge fluctuations on the electron self-energy. We fix the temperature at zero and focus on quantum charge fluctuations. We find a pronounced asymmetry of the imaginary part of the self-energy Im Sigma(k, omega) with respect to omega = 0, which is driven by strong electron correlation effects. The quasiparticle weight is reduced dramatically, which occurs almost isotropically along the Fermi surface. Concomitantly, an incoherent band and a sharp side band are generated and acquire sizable spectral weight. All these features are driven by the usual on-site charge fluctuations, which are realized in a rather high-energy region and yield plasmon excitations. On the other hand, the low-energy region with the scale of the superexchange interaction J is dominated by bond-charge fluctuations. Surprisingly, compared with the effect of on-site charge fluctuations, their effect on the electron self-energy is much weaker, even if the system approaches close to bond-charge instabilities. Furthermore, quantum charge dynamics does not produce a clear kink nor a pseudogap in the electron dispersion.2021-07-25T15:00:00ZYamase, HiroyukiBejas, MatiasGreco, AndresEmploying a large-N scheme of the layered t-J model with the long-range Coulomb interaction, which captures the fine details of the charge excitation spectra recently observed in cuprate superconductors, we explore the role of charge fluctuations on the electron self-energy. We fix the temperature at zero and focus on quantum charge fluctuations. We find a pronounced asymmetry of the imaginary part of the self-energy Im Sigma(k, omega) with respect to omega = 0, which is driven by strong electron correlation effects. The quasiparticle weight is reduced dramatically, which occurs almost isotropically along the Fermi surface. Concomitantly, an incoherent band and a sharp side band are generated and acquire sizable spectral weight. All these features are driven by the usual on-site charge fluctuations, which are realized in a rather high-energy region and yield plasmon excitations. On the other hand, the low-energy region with the scale of the superexchange interaction J is dominated by bond-charge fluctuations. Surprisingly, compared with the effect of on-site charge fluctuations, their effect on the electron self-energy is much weaker, even if the system approaches close to bond-charge instabilities. Furthermore, quantum charge dynamics does not produce a clear kink nor a pseudogap in the electron dispersion.Pincer-Type Phosphorus Compounds with Boryl-Pendant and Application in Catalytic H-2 Generation from Ammonia-Borane: A Theoretical Study
http://hdl.handle.net/2115/82595
Title: Pincer-Type Phosphorus Compounds with Boryl-Pendant and Application in Catalytic H-2 Generation from Ammonia-Borane: A Theoretical Study
Authors: Yang, Deshuai; Bao, Panqing; Yang, Zhen; Chen, Zhaoxu; Sakaki, Shigeyoshi; Maeda, Satoshi; Zeng, Guixiang
Abstract: Metal-free catalysts composed of heavy main group element(s) have been limited. Herein, a theoretical study unveils that pincer-type phosphorus compound bearing a boryl-pendant is good catalyst for H-2 generation from ammonia borane through phosphorus-boryl (P-B) cooperation function. Pincer-type phosphorus compound without boryl-pendant is not active for this reaction, indicating the important role of the P-B cooperation function.2021-09-02T15:00:00ZYang, DeshuaiBao, PanqingYang, ZhenChen, ZhaoxuSakaki, ShigeyoshiMaeda, SatoshiZeng, GuixiangMetal-free catalysts composed of heavy main group element(s) have been limited. Herein, a theoretical study unveils that pincer-type phosphorus compound bearing a boryl-pendant is good catalyst for H-2 generation from ammonia borane through phosphorus-boryl (P-B) cooperation function. Pincer-type phosphorus compound without boryl-pendant is not active for this reaction, indicating the important role of the P-B cooperation function.DRD1, a SWI/SNF-like chromatin remodeling protein, regulates a heat-activated transposon in Arabidopsis thaliana
http://hdl.handle.net/2115/82571
Title: DRD1, a SWI/SNF-like chromatin remodeling protein, regulates a heat-activated transposon in Arabidopsis thaliana
Authors: Takehira, Kanako; Hayashi, Yui; Nozawa, Kosuke; Chen, Lu; Suzuki, Takamasa; Masuta, Yukari; Kato, Atsushi; Ito, Hidetaka
Abstract: ONSEN is a heat-activated LTR retrotransposon in Arabidopsis thaliana. Screens to identify transcriptional regulatory factors of ONSEN revealed a SWI/SNF-like chromatin remodeling protein, DRD1, which cooperates with plant-specific RNA polymerase and is involved in RNA-directed DNA methylation. ONSEN transcript level was increased in the drd1 mutant relative to wild-type under heat stress, indicating that DRD1 plays a significant role in the silencing of activated ONSEN under the stress condition. The transcript level of HsfA2, which is directly involved in transcriptional activation of ONSEN, was not higher in the drd1 mutant than in the wild-type. Interestingly, no transgenerational transposition of ONSEN was observed in the drd1 mutant, even though DNA methylation levels were significantly reduced and expression levels were increased compared to the wild-type. These results suggest that other factors are involved in the regulation of ONSEN transposition in addition to the transcript level of ONSEN.2021-08-07T15:00:00ZTakehira, KanakoHayashi, YuiNozawa, KosukeChen, LuSuzuki, TakamasaMasuta, YukariKato, AtsushiIto, HidetakaONSEN is a heat-activated LTR retrotransposon in Arabidopsis thaliana. Screens to identify transcriptional regulatory factors of ONSEN revealed a SWI/SNF-like chromatin remodeling protein, DRD1, which cooperates with plant-specific RNA polymerase and is involved in RNA-directed DNA methylation. ONSEN transcript level was increased in the drd1 mutant relative to wild-type under heat stress, indicating that DRD1 plays a significant role in the silencing of activated ONSEN under the stress condition. The transcript level of HsfA2, which is directly involved in transcriptional activation of ONSEN, was not higher in the drd1 mutant than in the wild-type. Interestingly, no transgenerational transposition of ONSEN was observed in the drd1 mutant, even though DNA methylation levels were significantly reduced and expression levels were increased compared to the wild-type. These results suggest that other factors are involved in the regulation of ONSEN transposition in addition to the transcript level of ONSEN.Double coverings of arrangement complements and 2-torsion in Milnor fiber homology
http://hdl.handle.net/2115/82566
Title: Double coverings of arrangement complements and 2-torsion in Milnor fiber homology
Authors: Yoshinaga, Masahiko
Abstract: We prove that the mod 2 Betti numbers of double coverings of a complex hyperplane arrangement complement are combinatorially determined. The proof is based on a relation between the mod 2 Aomoto complex and the transfer long exact sequence. Applying the above result to the icosidodecahedral arrangement (16 planes in the three-dimensional space related to the icosidodecahedron), we conclude that the first homology of the Milnor fiber has non-trivial 2-torsion.2020-08-31T15:00:00ZYoshinaga, MasahikoWe prove that the mod 2 Betti numbers of double coverings of a complex hyperplane arrangement complement are combinatorially determined. The proof is based on a relation between the mod 2 Aomoto complex and the transfer long exact sequence. Applying the above result to the icosidodecahedral arrangement (16 planes in the three-dimensional space related to the icosidodecahedron), we conclude that the first homology of the Milnor fiber has non-trivial 2-torsion.Free hyperplane arrangements over arbitrary fields
http://hdl.handle.net/2115/82565
Title: Free hyperplane arrangements over arbitrary fields
Authors: Torielli, Michele; Palezzato, Elisa
Abstract: In this paper, we study the class of free hyperplane arrangements. Specifically, we investigate the relations between freeness over a field of finite characteristic and freeness over Q.2020-08-31T15:00:00ZTorielli, MichelePalezzato, ElisaIn this paper, we study the class of free hyperplane arrangements. Specifically, we investigate the relations between freeness over a field of finite characteristic and freeness over Q.