4,676 research outputs found

    Regulation of ethylene receptor expression in Arabidopsis

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    The ethylene receptor family of Arabidopsis consists of five members, ETR1, ETR2, ERS1, ERS2, and EIN4. Regulation of ethylene receptor expression in Arabidopsis was studied using three different approaches. First, the effect of ethylene-pathway mutations upon expression of ETR1 was examined. Ethylene-insensitive mutations in ETR1 resulted in a post-transcriptional increase in levels of the mutant receptor. Treatment of seedlings with silver, which leads to ethylene insensitivity, also resulted in an increase in levels of ETR1. Mutations in other components of the ethylene pathway had little effect upon expression of ETR1. Second, microarray analysis was performed using reciprocal mutants to examine ethylene-regulated gene expression. A large subset of ethylene-induced genes were involved in ethylene signal transduction. Among these, the ethylenereceptors ETR2, ERS1, and ERS2 showed pronounced induction, ETR1 displayed limited induction, and EIN4 remained unchanged. Third, the effect of abiotic stress upon expression of ethylene receptors was examined. Microarray analysis indicated that the expression of ETR1, ETR2, and ERS1 was reduced after exposure to salt stress, while expression of ERS2 and EIN4 remained unchanged. Changes in gene expression were reflected at the protein level as levels of the ETR1 protein decreased following salt and osmotic stress. A role for ethylene signal transduction in the plants\u27 response to abiotic stress was confirmed by examining the effect of salt and osmotic stress upon the germination of ethylene pathway mutants. My results demonstrate that changes in expression level of ethylene receptors provide a means by which ethylene signal transduction can be activated or repressed

    Superconductivity in pure and electron doped MgB2: Transport properties and pressure effects

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    The normal state and superconducting properties of MgB2 and Mg1-xAlxB2 are discussed based on structural, transport, and high pressure experiments. The positive Seebeck coefficient and its linear temperature dependence for Tc<T<160 K provide evidence that the low-temperature transport in MgB2 is due to hole-like metallic carriers. Structural and transport data show the important role of defects as indicated by the correlation of Tc, the residual resistance ratio, and the microstrain extracted from x-ray spectra. The decrease of Tc with hydrostatic pressure is well explained by the strong-coupling BCS theory. The large scatter of the pressure coefficients of Tc for different MgB2 samples, however, cannot be explained within this theory. We speculate that pressure may increase the defect density, particularly in samples with large initial defect concentration.Comment: Presented at NATO Advanced Research Workshop "New Trends in Superconductivity", Yalta (Ukraine) 16-20 September, 200

    Hierarchical video surveillance architecture: a chassis for video big data analytics and exploration

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    There is increasing reliance on video surveillance systems for systematic derivation, analysis and interpretation of the data needed for predicting, planning, evaluating and implementing public safety. This is evident from the massive number of surveillance cameras deployed across public locations. For example, in July 2013, the British Security Industry Association (BSIA) reported that over 4 million CCTV cameras had been installed in Britain alone. The BSIA also reveal that only 1.5% of these are state owned. In this paper, we propose a framework that allows access to data from privately owned cameras, with the aim of increasing the efficiency and accuracy of public safety planning, security activities, and decision support systems that are based on video integrated surveillance systems. The accuracy of results obtained from government-owned public safety infrastructure would improve greatly if privately owned surveillance systems ‘expose’ relevant video-generated metadata events, such as triggered alerts and also permit query of a metadata repository. Subsequently, a police officer, for example, with an appropriate level of system permission can query unified video systems across a large geographical area such as a city or a country to predict the location of an interesting entity, such as a pedestrian or a vehicle. This becomes possible with our proposed novel hierarchical architecture, the Fused Video Surveillance Architecture (FVSA). At the high level, FVSA comprises of a hardware framework that is supported by a multi-layer abstraction software interface. It presents video surveillance systems as an adapted computational grid of intelligent services, which is integration-enabled to communicate with other compatible systems in the Internet of Things (IoT)

    Water Content and Superconductivity in Na0.3CoO2*yH2O

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    We report here the correlation between the water content and superconductivity in Na0.3CoO2*yH2O under the influences of elevated temperature and cold compression. The x-ray diffraction of the sample annealed at elevated temperatures indicates that intergrowths exist in the compound at equilibrium when 0.6 < y < 1.4. Its low-temperature diamagnetization varies linearly with y, but is insensitive to the intergrowth, indicative of quasi-2D superconductivity. The Tc-onset, especially, shifts only slightly with y. Our data from cold compressed samples, on the other hand, show that the water-loss non-proportionally suppresses the diamagnetization, which is suggestive of weak links.Comment: 10 pages, 10 figures; submitted to Physica C (August 13, 2003

    The Location of Critical Reliability Slip Surface in Soil Slope Stability Analysis

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    AbstractThis study aims to find the difference between the slip surface having minimum factor of safety(called critical slip surface in deterministic analysis of slopes) and the slip surface having minimum reliability index(called critical reliability slip surface). The performance function used in reliability analysis was formulated by unbalanced thrust force method and the value of reliability index regarding given potential slip surface was obtained by Rosenbleuth method. The harmony search algorithm was adopted to alter the potential slip surface in order to locate the critical reliability slip surface. One complicated soil slope was analyzed and the results have shown that the critical slip surface is considerably different from critical reliability slip surface for multi-layer slopes and the reliability index of critical slip surface is larger than that of critical reliability slip surface

    Pressure Effect on the Superconducting and Magnetic Transitions of the Superconducting Ferromagnet RuSr2GdCu2O8

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    The superconducting ferromagnet RuSr2GdCu2O8 was investigated at high pressure. The intra-grain superconducting transition temperature, Tc, is resolved in ac-susceptibility as well as resistivity measurements. It is shown that the pressure shift of Tc is much smaller than that of other high-Tc compounds in a similar doping state. In contrast, the ferromagnetic transition temperature, Tm, increases with pressure at a relative rate that is about twice as large as that of Tc. The high-pressure data indicate a possible competition of the ferromagnetic and superconducting states in RuSr2GdCu2O8
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