The Experts below are selected from a list of 111 Experts worldwide ranked by ideXlab platform
Elaine A Backus - One of the best experts on this subject based on the ideXlab platform.
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epg waveform library for graphocephala atropunctata hemiptera cicadellidae effect of adhesive Input Resistor and voltage levels on waveform appearance and stylet probing behaviors
Journal of Insect Physiology, 2018Co-Authors: Felix A Cervantes, Elaine A BackusAbstract:Abstract Blue-green sharpshooter, Graphocephala atropunctata, is a native California vector of Xylella fastidiosa (Xf), a foregut-borne bacterium that is the causal agent of Pierce’s disease in grapevines. A 3rd-generation, AC-DC electropenetrograph (EPG monitor) was used to record stylet probing and ingestion behaviors of adult G. atropunctata on healthy grapevines. This study presents for the first time a complete, updated waveform library for this species, as well as effects of different electropenetrograph settings and adhesives on waveform appearances. Both AC and DC applied signals were used with Input Resistor (Ri) levels (amplifier sensitivities) of 106, 107, 108 and 109 Ohms, as well as two type of adhesives, conducting silver paint and handmade silver glue. Waveform description, characterization of electrical origins (R versus emf components), and proposed biological meanings of waveforms are reported, as well as qualitative differences in waveform appearances observed with different electropenetrograph settings and adhesives. In addition, a quantitative study with AC signal, using two applied voltage levels (50 and 200 mV) and two Ri levels (107 and 109 Ohms) was performed. Intermediate Ri levels 107 and 108 Ohms provided EPG waveforms with the greatest amount of information, because both levels captured similar proportions of R and emf components, as supported by appearance, clarity, and definition of waveforms. Similarly, use of a gold wire loop plus handmade silver glue provided more definition of waveforms than a gold wire loop plus commercial conducting silver paint. Qualitative/observational evidence suggested that AC applied signal caused fewer aberrant behaviors/waveforms than DC applied signal. In the quantitative study, behavioral components of the sharpshooter X wave were the most affected by changes in Ri and voltage level. Because the X wave probably represents X. fastidiosa inoculation behavior, future studies of X. fastidiosa inoculation via EPG will require carefully determined instrument settings. An intermediate Ri level such as 108 Ohms with low voltage, AC applied signal, and gold wire loop plus silver glue is recommended as the best electropenetrograph methods to conduct future EPG studies of sharpshooter inoculation behaviors on Xf-resistant and -susceptible grapevine.
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Certain applied electrical signals during EPG cause negative effects on stylet probing behaviors by adult Lygus lineolaris (Hemiptera: Miridae)
Journal of Insect Physiology, 2017Co-Authors: Elaine A Backus, Felix A Cervantes, Larry D. Godfrey, Waseem Akbar, Thomas L. Clark, M. G. RojasAbstract:Abstract This study is the first to fully evaluate whether electrical signals applied to large insects during electropenetrography (EPG; also called electrical penetration graph) negatively affect insect behavior. During EPG, electrical signals are applied to plants, and thus to the gold-wire-tethered insects feeding on them. The insect completes an electrical circuit whose changes in voltage reflect the insect’s stylet probing/penetration behaviors, recorded as waveform output. For nearly 50 years of EPG science, evidence has supported that there are no or negligible effects on tiny insects from applied electricity during EPG. Recently however, EPG studies of large-bodied hemipterans such as heteropterans and sharpshooter leafhoppers have been published. The wider stylet diameters of such large insects cause them to have lower inherent resistances to applied signals compared with smaller insects, conveying more electrical current. The present study asked whether such increased currents would affect insect stylet probing, by comparing Lygus lineolaris behaviors on pin-head cotton squares using an AC-DC electropenetrograph. Effects of AC or DC applied signals were separately examined in two factorial studies, each comparing four Input Resistor (Ri) levels (10 6 , 10 7 , 10 8 and 10 9 Ω) and four applied voltage levels (2, 60, 150 and 250 mV). Results showed that changes in both probing and non-probing behaviors were indeed caused by changing signal type, Ri level, or applied voltage. Negative effects on feeding were numerically greater overall for DC than AC applied signals, perhaps due to muscular tetany from DC; however, AC versus DC could not be statistically tested. Results strongly support the need for flexible Ri and applied voltage levels and types, to tailor instrument settings to the size and special needs of each insect subject. Our findings will facilitate further EPG studies of Lygus spp., such as host plant resistance or insecticidal assays/bioassays to assess mode of action and appropriate dosage. It is hoped that this study will also inform EPG studies of similar, large heteropterans in the future.
Bernard Reynaud - One of the best experts on this subject based on the ideXlab platform.
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Electrical penetration graphs from Cicadulina mbila on maize, the fine structure of its stylet pathways and consequences for the transmission efficiency of geminiviruses
2002Co-Authors: Jean-michel Lett, Martine Granier, Martial Grondin, Patrick Turpin, Frédéric Chiroleu, Michel Peterschmitt, Bernard ReynaudAbstract:The efficiency with which a plant virus is transmitted by its vector(s) depends from its feeding behavior on plants. Using a DC based system, an electrical penetration graph analysis was carried out on maize with die leafhopper Cicadulina mbila Naude (Homaptera: Cicadellidae), vector of Maize streak virus (Mastrevirus, Geminiviridae). Five distinct electrical penetration graph waveforms were distinguished by temporal and spectral features as well as by statistical analysis of their median voltage and duration. By changing the polarity of the system voltage and the level of the Input Resistor it was shown that the waveforms are mainly determined by electromotive forces (emf). Based on the correlation between waveforms and the fine structure of the stylet pathways using transmission electron microscopy, the insect's activities have been associated with five waveforms: stylet pathway (waveform 1), active ingestion (waveform 2), stylet work (waveform 3), salivation (waveform 4) and passive ingestion (waveform 5). Like waveform El and E2 of aphids, waveforms 4 and 5 of C. mbila correspond to feeding activities in sieve tubes. However, unlike aphids which probe briefly in non-vascular cells, waveform 2 corresponds to active ingestion in these cells, of which their cell content is partially ingested and their organelles integrity severely affected. These observations suggest that this specific feeding feature, typical of leafhoppers, determines their ability to acquire geminivirus virions located in the plant cell nucleus. This specific feeding behavior was compared to that of whiteflies of the genus Bemisia, vector of the geminiviruses of the genus Begomovirus, for which such a vigorous probing was not described. (Texte integral)
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Electrical penetration graphs from Cicadulina mbila on maize, the fine structure of its stylet pathways and consequences for virus transmission efficiency
Entomologia Experimentalis et Applicata, 2001Co-Authors: Jean-michel Lett, Martine Granier, Martial Grondin, Patrick Turpin, Franck Molinaro, Frédéric Chiroleu, Michel Peterschmitt, Bernard ReynaudAbstract:Five distinct electrical penetration graph waveforms characterising the feeding behaviour of the leafhopper Cicadulina mbila Naudé (Homoptera: Cicadellidae) on maize ( Zea mays L.) were obtained using a DC based system. The waveforms were distinguished by spectral features and by statistical analysis of their median voltages, durations and time to first waveform recording. By changing the polarity of the system voltage and the level of the Input Resistor it was shown that the waveforms are mainly determined by the electromotive force (emf) component. Based on the correlation between waveforms and the fine structure of the stylet pathways observed by transmission electron microscopy, insect's activities have been associated with five waveforms: stylet pathway formation (waveform 1), active ingestion (waveform 2), putative stylet work (waveform 3), salivation (waveform 4) and passive ingestion (waveform 5). Like waveform E1 and E2 of aphids, waveforms 4 and 5 of C. mbila correspond to feeding activities in sieve tubes. However, unlike aphids which probe briefly in non-vascular cells, waveform 2 corresponds to active ingestion in cells, where the cell content is partially ingested and hence the organelles' integrity severely affected. These observations suggest that this specific feeding feature, typical of leafhoppers, determines their ability to acquire geminivirus virions located in the plant cell nucleus.
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Electrical penetration graphs from Cicadulina mbila on maize, the fine structure of its stylet pathways and consequences for virus transmission efficiency
Entomologia Experimentalis Et Applicata, 2001Co-Authors: Jean-michel Lett, Martine Granier, Martial Grondin, Patrick Turpin, Franck Molinaro, Frédéric Chiroleu, Michel Peterschmitt, Bernard ReynaudAbstract:Five distinct electrical penetration graph waveforms characterising the feeding behaviour of the leafhopper Cicadulina mbila Naude (Homoptera: Cicadellidae) on maize (Zea mays L.) were obtained using a DC based system. The waveforms were distinguished by spectral features and by statistical analysis of their median voltages, durations and time to first waveform recording. By changing the polarity of the system voltage and the level of the Input Resistor it was shown that the waveforms are mainly determined by the electromotive force (emf) component. Based on the correlation between waveforms and the fine structure of the stylet pathways observed by transmission electron rnicroscopy, insect's activities have been associated with five waveforms: stylet pathway formation (waveform 1), active ingestion (waveform 2), putative stylet work (waveform 3), salivation (waveform 4) and passive ingestion (waveform 5). Like waveform E1 and E2 of aphids, waveforms 4 and 5 of C. mbila correspond to feeding activities in sieve tubes. However, unlike aphids which probe briefly in non-vascular cells, waveform 2 corresponds to active ingestion in cells, where the cell content is partially ingested and hence the organelles' integrity severely affected. These observations suggest that this specific feeding feature. typical of leafhoppers, determines their ability to acquire gerninivirus virions located in the plant cell nucleus. (Resume d'auteur)
Al Kearney - One of the best experts on this subject based on the ideXlab platform.
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TLP analysis of 0.125 μm CMOS ESD Input protection circuit
Microelectronics Reliability, 2005Co-Authors: Michael Chaine, James Davis, Al KearneyAbstract:Abstract In this investigation, TLP ESD analysis shows that if a large Input Resistor is used in combination with a secondary ggNMOS clamp in the Input protection circuitry, then the trigger voltage, V t1 , of the ggNMOS clamp is not a constant. The value is influenced by the size and properties of the Input Resistor, by current injection problems due to parallel resistive networks formed between the primary and secondary ESD circuits, by reverse bias diode leakage currents effects, and by source elevation effects due to voltage rises along the ESD ground bus.
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TLP analysis of 0.125 μm CMOS ESD Input protection circuit
2003 Electrical Overstress Electrostatic Discharge Symposium, 2003Co-Authors: Michael Chaine, James Davis, Al KearneyAbstract:In this investigation, TLP ESD analysis shows that if a large Input Resistor is used in combination with a ggNMOS clamp in the Input protection circuitry, then the trigger voltage, Vt1, of the ggNMOS increases. More importantly, the HBM injected current required to trigger snapback, It1, is significantly increased which unexpectedly delays the trigger of the ggNMOS secondary clamp and exposes the Input receiver's thin gate oxide to excessive Input pad stress voltages which results in 1-2 kV HBM leakage failures.
Soumyajit Mandal - One of the best experts on this subject based on the ideXlab platform.
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MWSCAS - Digital RF-over-Fiber Links Based on Continuous-Time Delta-Sigma Modulation
2019 IEEE 62nd International Midwest Symposium on Circuits and Systems (MWSCAS), 2019Co-Authors: Jifu Liang, Soumyajit MandalAbstract:Transmission of digitized radio frequency (RF) signals over optical fiber links is attractive because of low loss, extremely broad bandwidth, and robustness to external RF interference (RFI). However, realizing these advantages requires high-speed digitizers with high resolution and low power consumption. In this paper, a fourth-order continuous-time delta-sigma modulator (CT-DSM) with one-bit digital-to-analog converter (DAC) is proposed for this purpose. An assistant circuit is implemented to steer currents from the feedback DAC and Input Resistor to idealize the performance of the operational amplifier (op-amp) in the first integrator stage. The first op-amp also uses chopping to reduce 1/f noise and offset. The proposed modulator is designed in the TSMC 180 nm CMOS process. Simulation results show a maximum signal-to-noise-and-distortion ratio (SNDR) of 89.3 dB for a sample frequency of 100 MHz, a chopping frequency of 50 MHz, and an oversampling ratio (OSR) of 100, resulting in a Walden figure of merit (FoM) of 360 fJ/bit.
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Digital RF-over-Fiber Links Based on Continuous-Time Delta-Sigma Modulation
2019 IEEE 62nd International Midwest Symposium on Circuits and Systems (MWSCAS), 2019Co-Authors: Jifu Liang, Soumyajit MandalAbstract:Transmission of digitized radio frequency (RF) signals over optical fiber links is attractive because of low loss, extremely broad bandwidth, and robustness to external RF interference (RFI). However, realizing these advantages requires high-speed digitizers with high resolution and low power consumption. In this paper, a fourth-order continuous-time delta-sigma modulator (CT-DSM) with one-bit digital-to-analog converter (DAC) is proposed for this purpose. An assistant circuit is implemented to steer currents from the feedback DAC and Input Resistor to idealize the performance of the operational amplifier (op-amp) in the first integrator stage. The first op-amp also uses chopping to reduce 1/f noise and offset. The proposed modulator is designed in the TSMC 180 nm CMOS process. Simulation results show a maximum signal-to-noise-and-distortion ratio (SNDR) of 89.3 dB for a sample frequency of 100 MHz, a chopping frequency of 50 MHz, and an oversampling ratio (OSR) of 100, resulting in a Walden figure of merit (FoM) of 360 fJ/bit.
Felix A Cervantes - One of the best experts on this subject based on the ideXlab platform.
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epg waveform library for graphocephala atropunctata hemiptera cicadellidae effect of adhesive Input Resistor and voltage levels on waveform appearance and stylet probing behaviors
Journal of Insect Physiology, 2018Co-Authors: Felix A Cervantes, Elaine A BackusAbstract:Abstract Blue-green sharpshooter, Graphocephala atropunctata, is a native California vector of Xylella fastidiosa (Xf), a foregut-borne bacterium that is the causal agent of Pierce’s disease in grapevines. A 3rd-generation, AC-DC electropenetrograph (EPG monitor) was used to record stylet probing and ingestion behaviors of adult G. atropunctata on healthy grapevines. This study presents for the first time a complete, updated waveform library for this species, as well as effects of different electropenetrograph settings and adhesives on waveform appearances. Both AC and DC applied signals were used with Input Resistor (Ri) levels (amplifier sensitivities) of 106, 107, 108 and 109 Ohms, as well as two type of adhesives, conducting silver paint and handmade silver glue. Waveform description, characterization of electrical origins (R versus emf components), and proposed biological meanings of waveforms are reported, as well as qualitative differences in waveform appearances observed with different electropenetrograph settings and adhesives. In addition, a quantitative study with AC signal, using two applied voltage levels (50 and 200 mV) and two Ri levels (107 and 109 Ohms) was performed. Intermediate Ri levels 107 and 108 Ohms provided EPG waveforms with the greatest amount of information, because both levels captured similar proportions of R and emf components, as supported by appearance, clarity, and definition of waveforms. Similarly, use of a gold wire loop plus handmade silver glue provided more definition of waveforms than a gold wire loop plus commercial conducting silver paint. Qualitative/observational evidence suggested that AC applied signal caused fewer aberrant behaviors/waveforms than DC applied signal. In the quantitative study, behavioral components of the sharpshooter X wave were the most affected by changes in Ri and voltage level. Because the X wave probably represents X. fastidiosa inoculation behavior, future studies of X. fastidiosa inoculation via EPG will require carefully determined instrument settings. An intermediate Ri level such as 108 Ohms with low voltage, AC applied signal, and gold wire loop plus silver glue is recommended as the best electropenetrograph methods to conduct future EPG studies of sharpshooter inoculation behaviors on Xf-resistant and -susceptible grapevine.
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Certain applied electrical signals during EPG cause negative effects on stylet probing behaviors by adult Lygus lineolaris (Hemiptera: Miridae)
Journal of Insect Physiology, 2017Co-Authors: Elaine A Backus, Felix A Cervantes, Larry D. Godfrey, Waseem Akbar, Thomas L. Clark, M. G. RojasAbstract:Abstract This study is the first to fully evaluate whether electrical signals applied to large insects during electropenetrography (EPG; also called electrical penetration graph) negatively affect insect behavior. During EPG, electrical signals are applied to plants, and thus to the gold-wire-tethered insects feeding on them. The insect completes an electrical circuit whose changes in voltage reflect the insect’s stylet probing/penetration behaviors, recorded as waveform output. For nearly 50 years of EPG science, evidence has supported that there are no or negligible effects on tiny insects from applied electricity during EPG. Recently however, EPG studies of large-bodied hemipterans such as heteropterans and sharpshooter leafhoppers have been published. The wider stylet diameters of such large insects cause them to have lower inherent resistances to applied signals compared with smaller insects, conveying more electrical current. The present study asked whether such increased currents would affect insect stylet probing, by comparing Lygus lineolaris behaviors on pin-head cotton squares using an AC-DC electropenetrograph. Effects of AC or DC applied signals were separately examined in two factorial studies, each comparing four Input Resistor (Ri) levels (10 6 , 10 7 , 10 8 and 10 9 Ω) and four applied voltage levels (2, 60, 150 and 250 mV). Results showed that changes in both probing and non-probing behaviors were indeed caused by changing signal type, Ri level, or applied voltage. Negative effects on feeding were numerically greater overall for DC than AC applied signals, perhaps due to muscular tetany from DC; however, AC versus DC could not be statistically tested. Results strongly support the need for flexible Ri and applied voltage levels and types, to tailor instrument settings to the size and special needs of each insect subject. Our findings will facilitate further EPG studies of Lygus spp., such as host plant resistance or insecticidal assays/bioassays to assess mode of action and appropriate dosage. It is hoped that this study will also inform EPG studies of similar, large heteropterans in the future.