Recent Insights into the Mechanisms of <em>De Novo</em> and Maintenance of DNA Methylation in Mammals

DNA methylation is one of the key epigenetic mechanisms essential for transcriptional regulation, silencing of transposable elements, and genome stabilization. Under physiological conditions, DNA methylation is erased and then established genome-wide during gametogenesis and embryogenesis. De novo DNA methylation by the enzymatic reaction of the de novo DNA methyltransferases (DNMTs), DNMT3A and DNMT3B, occurs during the establishment of DNA methylation patterns specific to each germ cell type or somatic cell type after the erasure. Once cell type-specific DNA methylation patterns are established during embryogenesis, which can extend to early childhood, the maintenance of DNA methyltransferase DNMT1 and its cofactor UHRF1 cooperatively maintain the pattern throughout the individual’s lifetime. Recently, our group found that UHRF1 is also involved in de novo DNA methylation during oogenesis. Moreover, our group has identified two genes, CDCA7 and HELLS, to be the causative genes of ICF syndrome, characterized by hypomethylation of centromeric and pericentromeric repetitive sequences. Because CDCA7/HELLS comprise a chromatin remodeling complex, there are evidently certain regions where chromatin remodeling is required to achieve maintenance of DNA methylation. In this chapter, the current situation with respect to our understanding of de novo and maintenance of DNA methylation mechanisms under physiological conditions in mammals is summarized

Entanglement Purification through Zeno-like Measurements

We present a novel method to purify quantum states, i.e. purification through Zeno-like measurements, and show an application to entanglement purification.Comment: 5 pages, 1 figure; Contribution to the Proceedings of "Mysteries, Puzzles and Paradoxes in Quantum Mechanics", Gargnano, Italy, 2003 (to be published in J. Mod. Opt.

Blind estimation of room acoustic parameters from speech signals based on extended model of room impulse response

The speech transmission index (STI) and room acoustic parameters (RAPs), which are derived from a room impulse response (RIR), such as reverberation time and early decay time, are essential to assess speech transmission and to predict the listening difficulty in a sound field. Since it is difficult to measure RIR in daily occupied spaces, simultaneous blind estimation of STI and RAPs must be resolved as it is an imperative and challenging issue. This paper proposes a deterministic method for blindly estimating STI and five RAPs on the basis of an RIR stochastic model that approximates an unknown RIR. The proposed method formulates a temporal power envelope of a reverberant speech signal to obtain the optimal parameters for the RIR model. Simulations were conducted to evaluate STI and RAPs from observed reverberant speech signals. The root-mean-square errors between the estimated and ground-truth results were used to comparatively evaluate the proposed method with the previous method. The results showed that the proposed method can estimate STI and RAPs effectively without any training.Comment: 5-pages, 3 figures, 2 table

Optimization of electrolysis conditions for ti film electrodeposition from lif-licl eutectic molten salt

PRiME 2020, Honolulu, USA, October 4-9, 2020.The optimum conditions for electrodepositing compact, smooth, and adherent Ti films in LiF–LiCl–Li₃TiF₆ at 823 K were investigated. The Li₃TiF₆ was formed in-situ in the melt via comproportionation reaction between Li₂TiF₆ and Ti powder. The solubility of Li₃TiF₆ was confirmed to be higher than 7.1 mol% by cyclic voltammetry and ICP-AES measurement. Galvanostatic electrolysis was conducted on Ni plate substrates at various concentrations of Li₃TiF₆ (0.55, 2.6, 7.1 mol%) and cathodic current density (50–1200 mA cm⁻²). Ti films with smoother surface were obtained at higher Li₃TiF₆ concentration and lower current density. In the present study, Ti films having the smoothest surface were obtained at 7.1 mol% of Li₃TiF₆ and 50 mA cm⁻²

Effects of Temperature, Ti(III) Ion Concentration, and Current Density on Electrodeposition of Ti Films in LiF-LiCl Melt

The effects of temperature, Ti(III) ion concentration, and current density on the electrodeposition of Ti films were investigated in the eutectic LiF–LiCl melt at 823–973 K. The Ti(III) ions were prepared by adding Li₂TiF₆ and Ti metal to the melt. The diffusion coefficients of Ti(III) were 1.4, 1.8, 2.3, and 3.2 × 10⁻⁵ m² s⁻¹, at 823, 873, 923, and 973 K, respectively. Galvanostatic electrolysis was conducted at 823–973 K. The surface roughness (Sa) of the Ti films decreases with decreasing temperature. Thus, the electrodeposition of Ti films was conducted at the lowest temperature of 823 K with various Li3TiF6 concentrations (0.55–7.1 mol%) and cathodic current densities (50–1200 mA cm⁻²). The Sa was lower at higher Ti(III) ion concentrations and lower current densities. The smoothest Ti films with a Sa of 1.23 μm and a thickness of 10 μm were obtained at a cathodic current density of 50 mA cm⁻² and Li₃TiF₆ concentration of 7.1 mol%

情報化社会に対応する総合学習 : 情報分析・プレゼンテーション能力の育成を目指して

従来の教科教育とは別に創設された総合学習は, 教科教育との整合性をどのようにつけながら教育活動に位置付けられればよいであろうか。この問題に対し, 筆者は, 「情報化社会に生きる市民」に必要とされる能力の育成が総合学習において重要であると考えた。この情報化社会で必要とされる能力とは, 他者の意見を批判的に分析できる能力であり, 自らの意見を説得的に相手に伝える能力であろう。本年度, 本校の総合学習の時間であるLIFEにおいて, こうした能力を育成するための授業に取り組んできた。授業内容は, 意見を分析するための枠組み(フレームワーク)を習得することと, この枠組みを使って社会的論争問題(本年度は「夫婦別姓」の問題)について, 他者の意見を分析したり, 自らの意見を形成したりすることを中心に構成した。その授業の展開案の一部を提示する

高校世界史Aにおける近現代の内容構成 : 日本の近代化の構造-機能-変動理論的分析

南北問題を近現代史の中心的課題としてとらえたとき,非西洋諸国の近代化・産業化の過程をどのように内容構成すればよいであろうか。近現代史を中心に構成される世界史Aの内容構成として中核となる課題である。非西洋発展途上国が近代化を始めるとき,それは自らの文化的伝統と異質な西洋の文化を社会に移植し新しい文化を創造するという行為となる。そのため多くの国々は近代化の過程で歪みや停滞を余儀なくされ,近代化の達成に苦闘している。その意味では,こうした非西洋発展途上国の近代化を分析的に見る視点が求められているといえる。本小論では富永健一氏の機能-構造-変動理論に基づく「近代化理論」を分析の枠組みとし,近代産業社会の形成に成功した日本の近代化を分析することで,富永氏の「近代化理論」の非西洋発展途上国の近代化に対する有効性を検証した

世界史Aにおける前近代の構成について : 8世紀の世界・唐王朝と東アジア世界

国際化という流れの中で,国際社会に生きる資質を養うことを目的として,今年度から世界史Aという科目が始められた。この世界史Aという科目の特質は,2単位という少ない授業時間数で,19・20世紀を近現代とし,ヨーロッパを中心に一体化した世界を主題的にまとめて理解させるような内容構成がされている。この世界史Aにおいて近現代は従来の世界史とそれほどの違いはないが,前近代の内容は大幅に変わった。基本的には4つの文化圏を中心に,その特質を理解することが中心となり,各文化圏の歴史的な展開過程については2世紀,8世紀,13世紀,16世紀,17・18世紀の各時代から2つを選び,補足するという程度にまで精選されている。こうした空白の多い前近代の扱いをどのようにすればよいのか。文化圏の発展過程を眺める時代の視点をどのように設定すればよいのか。こうした課題を考察することにした