The Experts below are selected from a list of 359100 Experts worldwide ranked by ideXlab platform
Pavel Georgiev - One of the best experts on this subject based on the ideXlab platform.
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E(y)2/Sus1 is required for blocking PRE silencing by the Wari Insulator in Drosophila melanogaster
Chromosoma, 2010Co-Authors: Maksim Erokhin, Pavel Georgiev, Alexander Parshikov, Darya ChetverinaAbstract:Chromatin Insulators affect interactions between promoters and enhancers/silencers and function as barriers to the spread of repressive chromatin. Recently, we have found an Insulator, named Wari, located on the 3′ side of the white gene. Here, we show that the previously identified 368-bp core of this Insulator is sufficient for blocking Polycomb response element-mediated silencing. Although Wari does not contain binding sites for known Insulator proteins, the E(y)2 and CP190 proteins bind to Wari as well as to the Su(Hw)-containing Insulators in vivo. It may well be that these proteins are recruited to the Insulator by as yet unidentified DNA-binding protein. Partial inactivation of E(y)2 in a weak e(y)2 ^ u1 mutation impairs only the anti-silencing but not the enhancer-blocking activity of the Wari Insulator. Thus, the E(y)2 protein in different Drosophila Insulators serves to protect gene expression from silencing.
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'Insulator bodies' are aggregates of proteins but not of Insulators.
EMBO reports, 2008Co-Authors: A. K. Golovnin, Larisa Melnikova, Ilya Volkov, Margarita Kostuchenko, Alexander V. Galkin, Pavel GeorgievAbstract:Chromatin Insulators are thought to restrict the action of enhancers and silencers. The best-known Insulators in Drosophila require proteins such as Suppressor of Hairy wing (Su(Hw)) and Modifier of mdg4 (Mod(mdg4)) to be functional. The Insulator-related proteins apparently colocalize as nuclear speckles in immunostained cells. It has been asserted that these speckles are ‘Insulator bodies' of many Su(Hw)–Insulator DNA sites held together by associated proteins, including Mod(mdg4). As we show here using flies, larvae and S2 cells, a mutant Mod(mdg4) protein devoid of the Q-rich domain supports the function of Su(Hw)-dependent Insulators and efficiently binds to correct Insulator sites on the chromosome, but does not form or enter the Su(Hw)-marked nuclear speckles; conversely, the latter accumulate another (C-truncated) Mod(mdg4) mutant that cannot interact with Su(Hw) or with the genuine Insulators. Hence, it is not the functional genomic Insulators but rather aggregated proteins that make the so-called ‘Insulator bodies'.
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Loss of Insulator activity by paired Su(Hw) chromatin Insulators.
Science (New York N.Y.), 2001Co-Authors: Ekaterina Muravyova, A. K. Golovnin, Elena O. Gracheva, Aleksander Parshikov, Tatiana Belenkaya, Vincenzo Pirrotta, Pavel GeorgievAbstract:Chromatin Insulators are regulatory elements that block the action of transcriptional enhancers when interposed between enhancer and promoter. The Drosophila Suppressor of Hairy wing [Su(Hw)] protein binds the Su(Hw) Insulator and prevents enhancer-promoter interaction by a mechanism that is not understood. We show that when two copies of the Su(Hw) Insulator element, instead of a single one, are inserted between enhancer and promoter, Insulator activity is neutralized and the enhancer-promoter interaction may instead be facilitated. This paradoxical phenomenon could be explained by interactions between protein complexes bound at the Insulators.
C Y Liu - One of the best experts on this subject based on the ideXlab platform.
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Electric field distribution improvement of series connection of glass Insulator to the high voltage end of composite Insulator
Gaodianya Jishu High Voltage Engineering, 2010Co-Authors: Wen-xia Sima, J.-z. Deng, D. Yan, M Lu, Qing Yang, C Y LiuAbstract:In order to improve the electric field and potential distribution, taking the combined use of composite Insulators and glass Insulators as an example, we put forward a new method to improve the electric field distribution of composite Insulators, established a three-dimensional electric field calculation model of composite Insulators in the transmission line, and studied the improved situation of surface potential and electric field distribution of composite Insulators with glass Insulators installed in the high voltage side of composite Insulators at different levels of voltage. The results show that by this means, the voltage that the conducting wire side of composite Insulators can withstand is lowered; distorted electric field is eliminated; the electric field distribution in the ends of composite Insulators is improved. Finally, we recommend the number of glass Insulators which should be installed in the high voltage side of composite Insulators at different levels. According to the test results of 110 kV composite Insulator carried in the artificial fog chamber, the result shows that the flashover voltage is obviously improved and the voltage gradient is slightly changed after series connection glass Insulator, because the pressure effect of glass Insulator and the flashover arcing are inhibited certainly.
Ayman H. El-hag - One of the best experts on this subject based on the ideXlab platform.
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Autonomous Drone-Based Powerline Insulator Inspection via Deep Learning
Robot 2019: Fourth Iberian Robotics Conference, 2020Co-Authors: Anas Muhammad, Adnan Shahpurwala, Shayok Mukhopadhyay, Ayman H. El-hagAbstract:Accumulation of pollutants on ceramic Insulators is one of the major causes of dry band arcing, a predecessor to flashovers, which may further cause major outages of electricity. It is critical to know locations of polluted Insulators to prevent flashovers to make the power-grid reliable. This paper proposes a solution to detect the location of polluted Insulators along an overhead transmission line using a quadcopter. Once provided with the GPS locations of the electrical powerline transmission towers, the quadcopter autonomously hovers along the line. And while doing so, it sends a live video feed of the transmission line to the ground station. A pre-trained neural network on the ground station then detects Insulators in the video and classifies the detected Insulators as polluted or clean. Only if the Insulator detected is polluted, its location is recorded and reported back to the ground station. The novelty of this work is the use of a drone to automate the process of Insulator inspection via a deep learning based neural network approach. Experiments show that accurate inspection results are obtained. This work is an initial step in the direction of achieving completely autonomous drone-based powerline Insulator inspection.
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ROBOT (1) - Autonomous Drone-Based Powerline Insulator Inspection via Deep Learning.
Advances in Intelligent Systems and Computing, 2019Co-Authors: Anas Muhammad, Adnan Shahpurwala, Shayok Mukhopadhyay, Ayman H. El-hagAbstract:Accumulation of pollutants on ceramic Insulators is one of the major causes of dry band arcing, a predecessor to flashovers, which may further cause major outages of electricity. It is critical to know locations of polluted Insulators to prevent flashovers to make the power-grid reliable. This paper proposes a solution to detect the location of polluted Insulators along an overhead transmission line using a quadcopter. Once provided with the GPS locations of the electrical powerline transmission towers, the quadcopter autonomously hovers along the line. And while doing so, it sends a live video feed of the transmission line to the ground station. A pre-trained neural network on the ground station then detects Insulators in the video and classifies the detected Insulators as polluted or clean. Only if the Insulator detected is polluted, its location is recorded and reported back to the ground station. The novelty of this work is the use of a drone to automate the process of Insulator inspection via a deep learning based neural network approach. Experiments show that accurate inspection results are obtained. This work is an initial step in the direction of achieving completely autonomous drone-based powerline Insulator inspection.
Zhang Zhijiang - One of the best experts on this subject based on the ideXlab platform.
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An Online Measurement Method for Insulator Creepage Distance on Transmission Lines
Energies, 2018Co-Authors: Huang Jing, Kejian Liu, Dan Zeng, Zhang ZhijiangAbstract:Insulators play a crucial role in ensuring the normal operation of the power system, and the creepage distance is an important electrical parameter of Insulators. Most available solutions focus mainly on offline measurement methods, and online measurement for Insulator creepage distance on transmission lines remains a challenging task. To address this issue and to further improve the corresponding work efficiency, an online measurement method for Insulator creepage distance is presented in this paper. Considering the glass material of the Insulator and the long measuring distance, this method recognizes the Insulator type indirectly by calculating the structural parameters of the Insulators based on their geometric features, and then obtaining the creepage distance. Accordingly, a measurement system, which mainly includes an electronic total station and a camera with a telephoto lens, is designed in this paper. Moreover, this paper also proposes an error analysis model aimed at reducing the errors caused by the layout of this system. In the conducted experiments, this proposed method effectively obtains the creepage distance and the error correction model can further improve the measurement accuracy of structural parameters.
Douglas A. Johnson - One of the best experts on this subject based on the ideXlab platform.
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Mutational analysis identifies functional Rap1, Su(Hw), and CTCF Insulator sites in Arabidopsis thaliana
Plant Cell Reports, 2020Co-Authors: Anh Tran, Douglas A. JohnsonAbstract:Key message Genetic analysis identifies multiple, potential protein binding sites important for Insulator function in Arabidopsis thaliana: Rap1 site in UASrpg, Su(Hw) site in UASrpg, and CTCF site in BEAD1c. Abstract Three non-plant Insulators UASrpg, BEAD1c, and gypsy isolated from Ashbya gossypii , Homo sapiens and Drosophila melanogaster gypsy retrotransposon, respectively, demonstrate Insulator function in transgenic Arabidopsis thaliana . Here, the hypothesis that DNA sequences functional in A. thaliana are the same as those in the original host as previously assumed, was tested. Genetic analyses of the cloned fragments in an enhancer blocking assay system was performed through deletions and mutations to identify more precisely which sequences within the cloned fragments function as Insulators. Significant loss of Insulator activity was observed when the UASrpg Rap1 binding site R2 was mutated but not R1. Cloned fragments containing BEAD1c are effective Insulators in our assay system and the previously investigated gypsy Insulator is non-functional. Further analyses identified potential Su(Hw) and CTCF sites within UASrpg, of which only the Su(Hw) site was functional. Thus, the activity of non-plant Insulators in A. thaliana is context dependent. These results support the hypothesis that Insulator function is conserved across kingdoms.
