452 research outputs found

    Spatiotemporal control of root immune responses during microbial colonization.

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    The entire evolutionary trajectory of plants towards large and complex multi-cellular organisms has been accompanied by incessant interactions with omnipresent unicellular microbes. This led to the evolution of highly complex microbial communities, whose members display the entire spectrum of pathogenic to mutualistic behaviors. Plant roots are dynamic, fractally growing organs and even small Arabidopsis roots harbor millions of individual microbes of diverse taxa. It is evident that microbes at different positions on a root surface could experience fundamentally different environments, which, moreover, rapidly change over time. Differences in spatial scales between microbes and roots compares to humans and the cities they inhabit. Such considerations make it evident that mechanisms of root-microbe interactions can only be understood if analyzed at relevant spatial and temporal scales. This review attempts to provide an overview of the rapid recent progress that has been made in mapping and manipulating plant damage and immune responses at cellular resolution, as well as in visualizing bacterial communities and their transcriptional activities. We further discuss the impact that such approaches will have for a more predictive understanding of root-microbe interactions

    Laser pose estimation and tracking using fuzzy extended information filtering for an autonomous mobile robot

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    This paper presents methodologies and techniques for posture estimation and tracking of an autonomous mobile robot (AMR) using a laser scanner with at least three retro-reflectors. A three-point laser triangulation method is presented to find an initial posture of the robot and then a fuzzy extended information filtering (FEIF) method is used to improve the accuracy of the robot's posture estimation. With the odometric information from the driving wheels, a FEIF-based posture tracking algorithm is proposed to continuously keep trace of the robot's posture at slow speeds. Simulation and experimental results are conducted to show the efficacy and usefulness of the proposed methods

    Multisensor 3D posture determination of a mobile robot using inertial and ultrasonic sensors

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    This paper presents methodologies and techniques for fusing inertial and ultrasonic sensors to estimate the current posture of a mobile robot navigating over indoor uneven terrain. This new type of pose tracking system is developed by means of fusing an inertial navigation subsystem (INS) and an ultrasonic localization subsystem. Extended Kalman filtering (EKF)-based algorithm for integrating both the subsystems is proposed to obtain reliable attitude and position estimates of the vehicle and to eliminate the accumulation errors caused by wheel slippage and surface roughness. Experimental results are conducted to illustrate feasibility and effectiveness of the proposed system and method

    Essential role of PKC delta in histone deacetylase inhibitor-induced Epstein-Barr virus reactivation in nasopharyngeal carcinoma cells

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    Histone deactylase inhibitors (HDACi) are common chemotherapeutic agents that stimulate Epstein-Barr virus (EBV) reactivation; the detailed mechanism remains obscure. In this study, it is demonstrated that PKC delta is required for induction of the EBV lytic cycle by HDACi. Inhibition of PKC delta abrogates HDACi-mediated transcriptional activation of the Zta promoter and downstream lytic gene expression. Nuclear translocation of PKC delta is observed following HDACi stimulation and its overexpression leads to progression of the EBV lytic cycle. Our study suggests that PKC delta is a crucial mediator of EBV reactivation and provides a novel insight to study the regulation of the EBV lytic cycle

    Photoresponsive and Ultraviolet to Visible-Light Range Photocatalytic Properties of ZnO:Sb Nanowires

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    100學年度研究獎補助論文[[abstract]]Zinc oxide (ZnO) doped antimony (Sb) nanowires have been synthesized for improving ultraviolet sensing and photocatalytic properties. Upon illumination by UV light (365nm , 2.33mWcm−2 ), the photoelectric current of the ZnO:Sb nanowires exhibited a rapid photoresponse as compared to that of the ZnO nanowires. A highest ratio of photocurrent to dark current of around 48.8-fold was achieved in the as-synthesized ZnO:Sb nanowires. A UV-visible spectrophotometer was used to investigate the absorbance spectrum of the ZnO:Sb nanowires, which exhibited a high absorbance ratio with redshift effect in contrast to that of the ZnO nanowires. Visible-light photocatalysis and UV photoresponsive properties of the ZnO:Sb nanowires are superior to those of the ZnO nanowires.[[notice]]補正完畢[[incitationindex]]SCI[[booktype]]電子

    The Influences of Diesel Particulate Filter Installation on Air Pollutant Emissions for Used Vehicles

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    Three kinds of diesel particulate filters (DPFs) were installed on used diesel-powered vehicles to investigate their influences on air pollutant emissions. The air pollutant emissions were measured before, after and running for specific distances to assess the deterioration effect. The emission measurement was performed on a chassis dynamometer. The results show that emissions of smoke, CO and HC are all reduced after DPF installation. After 20000 km driving, the emission concentrations of the above 3 criteria air pollutants do not increase in comparison with that right after installation. When DPFs are installed, the emissions of PAHs (polycyclic aromatic hydrocarbons) are reduced by 85.6-89.4% and 69.0-89.2% for heavy-duty diesel vehicles (HDVs) and light-duty diesel vehicles (LDVs), respectively. After driving 20000 km for HDVs and 2500 km for LDVs, PAH emissions do not increase in comparison with that right after installation, indicating that the DPFs do not deteriorate after driving for the test mileages. The lower molecular weight PAHs predominates in the exhaust both before and after DPF installation. The results also show the reduction rate is higher for higher molecular weight PAHs due to their tendency to adsorb on particulate

    The effects of the bacterial interaction with visible-light responsive titania photocatalyst on the bactericidal performance

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    Bactericidal activity of traditional titanium dioxide (TiO2) photocatalyst is effective only upon irradiation by ultraviolet light, which restricts the potential applications of TiO2 for use in our living environments. Recently carbon-containing TiO2 was found to be photoactive at visible-light illumination that affords the potential to overcome this problem; although, the bactericidal activity of these photocatalysts is relatively lower than conventional disinfectants. Evidenced from scanning electron microscopy and confocal Raman spectral mapping analysis, we found the interaction with bacteria was significantly enhanced in these anatase/rutile mixed-phase carbon-containing TiO2. Bacteria-killing experiments indicate that a significantly higher proportion of all tested pathogens including Staphylococcus aureus, Shigella flexneri and Acinetobacter baumannii, were eliminated by the new nanoparticle with higher bacterial interaction property. These findings suggest the created materials with high bacterial interaction ability might be a useful strategy to improve the antimicrobial activity of visible-light-activated TiO2

    C-reactive protein, sodium azide, and endothelial connexin43 gap junctions

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    We investigated the effect of C-reactive protein (CRP) and sodium azide (NaN(3)) on endothelial Cx43 gap junctions. Human aortic endothelial cells (HAEC) were treated with (a) detoxified CRP, (b) detoxified dialyzed CRP, (c) detoxified dialyzed CRP plus NaN(3), (d) NaN(3), or (e) dialyzed NaN(3). The concentration of CRP in all preparations was fixed to 25 mu g/ml and that of NaN(3) in the preparations of (c) to (e) was equivalent to that contained in the 25 mu g/ml CRP purchased commercially. The results showed that both the expression of Cx43 protein and gap junctional communication function post-48-h incubation were reduced and inhibited by the detoxified CRP, NaN(3), or detoxified dialyzed CRP plus NaN(3), but not by the detoxified dialyzed CRP or dialyzed NaN(3). Reverse transcription-polymerase chain reaction analysis of cells treated for 72 h also showed a pattern of transcriptional regulation essentially the same as that for the proteins. We concluded that CRP does not have a significant effect on Cx43 gap junctions of HAEC, but NaN(3) inhibited the viability of cells and downregulate their junctions

    Why did Warrant Markets Close in China but not Taiwan?

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    The paper bridges a gap in the literature by using moment analysis, CAPM statistics, stochastic dominance (SD) test, and volume analysis to examine investor preferences for warrants between China and Taiwan, and investigating why the market for warrants in China has to close while the market for Taiwan warrants is successful. Using moment analysis, it is shown that that buying China warrants has a higher likelihood of losses than its Taiwan counterpart. Using CAPM analysis, in general, both the Sharpe ratio and Jensen index for warrants from the Taiwan market are more reasonable, while that from the China market is too negative. On the other hand, the Treynor index for China warrants shows that China warrants are highly volatile. This could make investors avoid investing in China warrants which, in turn, could lead to its closure. Using SD analysis, though there is no arbitrage opportunity between the China and Taiwan warrant markets, it is shown that the markets for China and Taiwan warrants are not efficient, and second- and third-order risk averters prefer to invest in China warrants to warrants in Taiwan. This implies that the warrant issuers prefer to issue Taiwan warrants than China warrants. Using volume analysis, the China warrant market is much more active than the Taiwan warrant market. This could imply that there are more speculative activities in China than in Taiwan which, in turn, could lead to China’s decision to close its warrant market. The findings in the paper are useful for investors for investment decisions regarding Taiwan and China warrants, for academic analysis for modelling Taiwan and China warrants, and policy makers for policy making related to Taiwan and China warrants. In the future, China may rethink reopening warrant markets and learning from mature-covered warrant markets such as Taiwan how to inhibit excess speculation and educate warrant investors

    Relativistic wave equations for interacting massive particles with arbitrary half-intreger spins

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    New formulation of relativistic wave equations (RWE) for massive particles with arbitrary half-integer spins s interacting with external electromagnetic fields are proposed. They are based on wave functions which are irreducible tensors of rank n(n (n=s-\frac12$) antisymmetric w.r.t. n pairs of indices, whose components are bispinors. The form of RWE is straightforward and free of inconsistencies associated with the other approaches to equations describing interacting higher spin particles
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