電信利権交渉からみる近代中国の国際通信(1900-1937) : 技術、通信特許権と国際関係

学位の種別: 課程博士審査委員会委員 : (主査)東京大学准教授 川島 真, 東京大学教授 代田 智明, 東京大学教授 村田 雄二郎, 東京大学教授 三谷 博, 神奈川大学教授 孫 安石University of Tokyo(東京大学

SARS Pandemic Exposure Impaired Early Childhood Development in China

Social and mental stressors associated with the pandemic of a novel infectious disease, e.g., COVID-19 or SARS may promote long-term effects on child development. However, reports aimed at identifying the relationship between pandemics and child health are limited. A retrospective study was conducted to associate the SARS pandemic in 2003 with development milestones or physical examinations among longitudinal measurements of 14,647 children. Experiencing SARS during childhood was associated with delayed milestones, with hazard ratios of 3.17 (95% confidence intervals CI: 2.71, 3.70), 3.98 (3.50, 4.53), 4.96 (4.48, 5.49), or 5.57 (5.00, 6.20) for walking independently, saying a complete sentence, counting 0–10, and undressing him/herself for urination, respectively. These results suggest relevant impacts from COVID-19 on child development should be investigated

Arabidopsis blue light receptor phototropin 1 undergoes blue light-induced activation in membrane microdomains

Phototropin (phot)-mediated signaling initiated by blue light (BL) plays a critical role in optimizing photosynthetic light capture at the plasma membrane (PM) in plants. However, the mechanisms underlying the regulation of phot activity at the PM in response to BL remain largely unclear. In this study, by single-particle tracking and step-wise photobleaching analysis we demonstrated that in the dark phot1-GFP proteins remain in an inactive state and mostly present as a monomer. The phot1-GFP diffusion rate and its dimerization increased in a dose-dependent manner in response to BL. In contrast, BL did not affect the lateral diffusion of kinase-inactive phot1 -GFP, whereas it did enhance its dimerization, suggesting that phot1 dimerization is independent of its phosphorylation. Förster resonance energy transfer-fluorescence lifetime imaging microscopy (FRET-FLIM) analysis revealed that the interaction between phot1-GFP and AtRem1.3-mCherry was enhanced along with increased time of BL treatment. However, the BL-dependent interaction was not obvious in plants co-expressing phot1 -GFP and AtRem1.3-mCherry, implicating that BL facilitated the translocation of functional phot1-GFP into AtRem1.3-labeled microdomains to activate phot-mediated signaling. Conversely, sterol depletion attenuated phot1-GFP dynamics, dimerization, and phosphorylation. Taken together, these results indicate that membrane microdomains act as an organizing platform essential for proper function of activated phot1 at the PM

Association between birthweight and ambient PM_2.5 in the United States:Individually-varied susceptibility and spatial heterogeneity

The association between maternal exposure to PM2.5 and birthweight varies geographically, which may be caused by susceptibility. Whether this population-level association is a function of mixtures of individuals with different susceptibilities is unclear. We investigated the probability distribution of individuals with different susceptibilities to PM2.5-related birthweight change, and evaluated spatial variation of the effect across the United States (US). We estimated the individual-level susceptibility using the effect of PM2.5 among a homogenous subpopulation, which was defined by a specific combination of modifiers. According to frequencies for all combinations, we derived the probability distribution of differential susceptibilities across the US and by states. From birth certificates across the US (1999–2004), we analyzed a total of 18,317,707 samples of singletons. Of the samples, 54–55% were assigned valid exposures, and linked to PM2.5. The subpopulation-specific associations of PM2.5 on birthweight change (i.e., susceptibilities) ranged from negative to positive. For the first-trimester exposure, 61.4% of the associations were negative, and the mean was −1.01 g (95% confidence interval, CI: −1.63, −0.38) of birthweight change per 5 μg/m3 increase of PM2.5. The state-level associations varied (from −2.04 g [−2.76, −1.31] in New Hampshire to −0.30 g [−1.01, 0.41] in Texas) with demographic compositions in the US. The between-state variations of maternal race and education level were the greatest contributors to the spatial heterogeneity. Our findings may be useful to the policymaker in planning interventions for subpopulations susceptible to ambient pollution

ÔØ Å ÒÙ× Ö ÔØ Constructing a Reliable Web Graph with Information on Browsing Behavior ACCEPTED MANUSCRIPT Constructing a Reliable Web Graph with Information on Browsing Behavior

Abstract Page quality estimation is one of the greatest challenges for Web search engines. Hyperlink analysis algorithms such as PageRank and TrustRank are usually adopted for this task. However, low quality, unreliable and even spam data in the Web hyperlink graph makes it increasingly difficult to estimate page quality effectively. Analyzing large-scale user browsing behavior logs, we found that a more reliable Web graph can be constructed by incorporating browsing behavior information. The experimental results show that hyperlink graphs constructed with the proposed methods are much smaller in size than the original graph. In addition, algorithms based on the proposed "surfing with prior knowledge" model obtain better estimation results with these graphs for both high quality page and spam page identification tasks. Hyperlink graphs constructed with the proposed methods evaluate Web page quality more precisely and with less computational effort. HIGHLIGHTS 1. With user browsing behavior information, it is possible to improve the performance of quality estimation results for commercial search engines. 2. Three different kinds of Web graphs were proposed which combines original hyperlink and user browsing behavior information. 3. Differences between the constructed graphs and the original Web graph show that the constructed graphs provide more reliable information and can be adopted for practical quality estimation tasks. 4. The incorporation of user browsing information is more important than the selection of link analysis algorithms for the task of quality estimation

Exploring the Spatiotemporal Organization of Membrane Proteins in Living Plant Cells

Plasma membrane proteins have important roles in transport and signal transduction. Deciphering the spatiotemporal organization of these proteins provides crucial information for elucidating the links between the behaviors of different molecules. However, monitoring membrane proteins without disrupting their membrane environment remains difficult. Over the past decade, many studies have developed single-molecule techniques, opening avenues for probing the stoichiometry and interactions of membrane proteins in their native environment by providing nanometer-scale spatial information and nanosecond-scale temporal information. In this review, we assess recent progress in the development of labeling and imaging technology for membrane protein analysis. We focus in particular on several single-molecule techniques for quantifying the dynamics and assembly of membrane proteins. Finally, we provide examples of how these new techniques are advancing our understanding of the complex biological functions of membrane proteins

A modified GFP facilitates counting membrane protein subunits by step-wise photobleaching in Arabidopsis

Membrane proteins exert functions by forming oligomers or molecular complexes. Currently, step-wise photobleaching has been applied to count the fluorescently labelled subunits in plant cells, for which an accurate and reliable control is required to distinguish individual subunits and define the basal fluorescence. However, the common procedure using immobilized GFP molecules is obviously not applicable for analysis in living plant cells. Using the spatial intensity distribution analysis (SpIDA), we found that the A206K mutation reduced the dimerization of GFP molecules. Further ectopic expression of Myristoyl-GFP(A206K) driven by the endogenous AtCLC2 promoter allowed imaging of individual molecules at a low expression level. As a result, the percentage of dimers in the transgenic pCLC2::Myristoyl-mGFP(A206K) line was significantly reduced in comparison to that of the pCLC2::Myristoyl-GFP line, confirming its application in defining the basal fluorescence intensity of GFP. Taken together, our results demonstrated that pCLC2::Myristoyl-mGFP(A206K) can be used as a standard control for monomer GFP, facilitating the analysis of the step-wise photobleaching of membrane proteins in Arabidopsis thaliana