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Mark C Hersam - One of the best experts on this subject based on the ideXlab platform.
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multi terminal memtransistors from polycrystalline monolayer molybdenum disulfide
Nature, 2018Co-Authors: Vinod K Sangwan, Hongsub Lee, Hadallia Bergeron, Itamar Balla, Megan E Beck, Kan Sheng Chen, Mark C HersamAbstract:Memristors are two-terminal passive circuit elements that have been developed for use in non-volatile resistive random-access memory and may also be useful in neuromorphic computing. Memristors have higher endurance and faster read/write times than flash memory and can provide multi-bit data storage. However, although two-terminal memristors have demonstrated capacity for basic neural functions, synapses in the human brain outnumber neurons by more than a thousandfold, which implies that multi-terminal memristors are needed to perform complex functions such as heterosynaptic plasticity. Previous attempts to move beyond two-terminal memristors, such as the three-terminal Widrow-Hoff memristor and field-effect transistors with nanoionic gates or floating gates, did not achieve memristive switching in the transistor. Here we report the experimental realization of a multi-terminal hybrid memristor and transistor (that is, a memtransistor) using polycrystalline monolayer molybdenum disulfide (MoS2) in a scalable fabrication process. The two-dimensional MoS2 memtransistors show gate tunability in Individual Resistance states by four orders of magnitude, as well as large switching ratios, high cycling endurance and long-term retention of states. In addition to conventional neural learning behaviour of long-term potentiation/depression, six-terminal MoS2 memtransistors have gate-tunable heterosynaptic functionality, which is not achievable using two-terminal memristors. For example, the conductance between a pair of floating electrodes (pre- and post-synaptic neurons) is varied by a factor of about ten by applying voltage pulses to modulatory terminals. In situ scanning probe microscopy, cryogenic charge transport measurements and device modelling reveal that the bias-induced motion of MoS2 defects drives resistive switching by dynamically varying Schottky barrier heights. Overall, the seamless integration of a memristor and transistor into one multi-terminal device could enable complex neuromorphic learning and the study of the physics of defect kinetics in two-dimensional materials.
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multi terminal memtransistors from polycrystalline monolayer molybdenum disulfide
Nature, 2018Co-Authors: Vinod K Sangwan, Hadallia Bergeron, Itamar Balla, Kan Sheng Chen, Megan Beck, Mark C HersamAbstract:Polycrystalline monolayer molybdenum disulfide is used to fabricate a multi-terminal device combining a memristor and a transistor, which can mimic biological neurons with multiple synapses for neuromorphic computing applications. Memristors are two-terminal devices whose Resistance exhibits a memory effect that depends on the current or voltage history. This memory enables such devices to mimic the behaviour of a neural synapse, making them of great interest for creating brain-inspired neuromorphic computing architectures. Basic neural functions have been demonstrated with two-terminal devices, but more complex functions, such as heterosynaptic plasticity, will probably require devices with multiple terminals. Mark Hersam and colleagues combine the restive switching behaviour of a memristor with the gate-tunability of a transistor into one multi-terminal device called a memtransistor. Based on two-dimensional layers of molybdenum disulfide, such memtransistors not only exhibit conventional neural learning behaviour but also heterosynaptic functionality, providing a platform for mimicking biological neurons with multiple synapses. Memristors are two-terminal passive circuit elements that have been developed for use in non-volatile resistive random-access memory and may also be useful in neuromorphic computing1,2,3,4,5,6. Memristors have higher endurance and faster read/write times than flash memory4,7,8 and can provide multi-bit data storage. However, although two-terminal memristors have demonstrated capacity for basic neural functions, synapses in the human brain outnumber neurons by more than a thousandfold, which implies that multi-terminal memristors are needed to perform complex functions such as heterosynaptic plasticity3,9,10,11,12,13. Previous attempts to move beyond two-terminal memristors, such as the three-terminal Widrow–Hoff memristor14 and field-effect transistors with nanoionic gates15 or floating gates16, did not achieve memristive switching in the transistor17. Here we report the experimental realization of a multi-terminal hybrid memristor and transistor (that is, a memtransistor) using polycrystalline monolayer molybdenum disulfide (MoS2) in a scalable fabrication process. The two-dimensional MoS2 memtransistors show gate tunability in Individual Resistance states by four orders of magnitude, as well as large switching ratios, high cycling endurance and long-term retention of states. In addition to conventional neural learning behaviour of long-term potentiation/depression, six-terminal MoS2 memtransistors have gate-tunable heterosynaptic functionality, which is not achievable using two-terminal memristors. For example, the conductance between a pair of floating electrodes (pre- and post-synaptic neurons) is varied by a factor of about ten by applying voltage pulses to modulatory terminals. In situ scanning probe microscopy, cryogenic charge transport measurements and device modelling reveal that the bias-induced motion of MoS2 defects drives resistive switching by dynamically varying Schottky barrier heights. Overall, the seamless integration of a memristor and transistor into one multi-terminal device could enable complex neuromorphic learning and the study of the physics of defect kinetics in two-dimensional materials18,19,20,21,22.
Vinod K Sangwan - One of the best experts on this subject based on the ideXlab platform.
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multi terminal memtransistors from polycrystalline monolayer molybdenum disulfide
Nature, 2018Co-Authors: Vinod K Sangwan, Hongsub Lee, Hadallia Bergeron, Itamar Balla, Megan E Beck, Kan Sheng Chen, Mark C HersamAbstract:Memristors are two-terminal passive circuit elements that have been developed for use in non-volatile resistive random-access memory and may also be useful in neuromorphic computing. Memristors have higher endurance and faster read/write times than flash memory and can provide multi-bit data storage. However, although two-terminal memristors have demonstrated capacity for basic neural functions, synapses in the human brain outnumber neurons by more than a thousandfold, which implies that multi-terminal memristors are needed to perform complex functions such as heterosynaptic plasticity. Previous attempts to move beyond two-terminal memristors, such as the three-terminal Widrow-Hoff memristor and field-effect transistors with nanoionic gates or floating gates, did not achieve memristive switching in the transistor. Here we report the experimental realization of a multi-terminal hybrid memristor and transistor (that is, a memtransistor) using polycrystalline monolayer molybdenum disulfide (MoS2) in a scalable fabrication process. The two-dimensional MoS2 memtransistors show gate tunability in Individual Resistance states by four orders of magnitude, as well as large switching ratios, high cycling endurance and long-term retention of states. In addition to conventional neural learning behaviour of long-term potentiation/depression, six-terminal MoS2 memtransistors have gate-tunable heterosynaptic functionality, which is not achievable using two-terminal memristors. For example, the conductance between a pair of floating electrodes (pre- and post-synaptic neurons) is varied by a factor of about ten by applying voltage pulses to modulatory terminals. In situ scanning probe microscopy, cryogenic charge transport measurements and device modelling reveal that the bias-induced motion of MoS2 defects drives resistive switching by dynamically varying Schottky barrier heights. Overall, the seamless integration of a memristor and transistor into one multi-terminal device could enable complex neuromorphic learning and the study of the physics of defect kinetics in two-dimensional materials.
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multi terminal memtransistors from polycrystalline monolayer molybdenum disulfide
Nature, 2018Co-Authors: Vinod K Sangwan, Hadallia Bergeron, Itamar Balla, Kan Sheng Chen, Megan Beck, Mark C HersamAbstract:Polycrystalline monolayer molybdenum disulfide is used to fabricate a multi-terminal device combining a memristor and a transistor, which can mimic biological neurons with multiple synapses for neuromorphic computing applications. Memristors are two-terminal devices whose Resistance exhibits a memory effect that depends on the current or voltage history. This memory enables such devices to mimic the behaviour of a neural synapse, making them of great interest for creating brain-inspired neuromorphic computing architectures. Basic neural functions have been demonstrated with two-terminal devices, but more complex functions, such as heterosynaptic plasticity, will probably require devices with multiple terminals. Mark Hersam and colleagues combine the restive switching behaviour of a memristor with the gate-tunability of a transistor into one multi-terminal device called a memtransistor. Based on two-dimensional layers of molybdenum disulfide, such memtransistors not only exhibit conventional neural learning behaviour but also heterosynaptic functionality, providing a platform for mimicking biological neurons with multiple synapses. Memristors are two-terminal passive circuit elements that have been developed for use in non-volatile resistive random-access memory and may also be useful in neuromorphic computing1,2,3,4,5,6. Memristors have higher endurance and faster read/write times than flash memory4,7,8 and can provide multi-bit data storage. However, although two-terminal memristors have demonstrated capacity for basic neural functions, synapses in the human brain outnumber neurons by more than a thousandfold, which implies that multi-terminal memristors are needed to perform complex functions such as heterosynaptic plasticity3,9,10,11,12,13. Previous attempts to move beyond two-terminal memristors, such as the three-terminal Widrow–Hoff memristor14 and field-effect transistors with nanoionic gates15 or floating gates16, did not achieve memristive switching in the transistor17. Here we report the experimental realization of a multi-terminal hybrid memristor and transistor (that is, a memtransistor) using polycrystalline monolayer molybdenum disulfide (MoS2) in a scalable fabrication process. The two-dimensional MoS2 memtransistors show gate tunability in Individual Resistance states by four orders of magnitude, as well as large switching ratios, high cycling endurance and long-term retention of states. In addition to conventional neural learning behaviour of long-term potentiation/depression, six-terminal MoS2 memtransistors have gate-tunable heterosynaptic functionality, which is not achievable using two-terminal memristors. For example, the conductance between a pair of floating electrodes (pre- and post-synaptic neurons) is varied by a factor of about ten by applying voltage pulses to modulatory terminals. In situ scanning probe microscopy, cryogenic charge transport measurements and device modelling reveal that the bias-induced motion of MoS2 defects drives resistive switching by dynamically varying Schottky barrier heights. Overall, the seamless integration of a memristor and transistor into one multi-terminal device could enable complex neuromorphic learning and the study of the physics of defect kinetics in two-dimensional materials18,19,20,21,22.
D. W. Cooper - One of the best experts on this subject based on the ideXlab platform.
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effects of a gonadotropin releasing hormone agonist implant on reproduction in a male marsupial macropus eugenii
Biology of Reproduction, 2004Co-Authors: Catherine A Herbert, Geoff Shaw, T E Trigg, Douglas C Eckery, Marilyn B Renfree, D. W. CooperAbstract:This study evaluated the potential of slow-release GnRH agonist (deslorelin) implants to inhibit reproductive function in the male tammar wallaby. The specific aim was to measure the effects of graded dosages of deslorelin on testes size and plasma LH and testosterone concentrations. Adult male tammar wallabies were assigned to four groups (n = 6 per group) and received the following treatment: control, placebo implant; low dose, 5 mg deslorelin; medium dose, 10 mg; high dose, 20 mg. All dosages of deslorelin induced acute increases (P 0.05). These results suggest that the male tammar wallaby is resistant to the contraceptive effects of chronic GnRH agonist treatment. Despite the maintenance of testosterone secretion, the majority of male tammars (10 of 17) failed to respond to a GnRH challenge with a release of LH between Days 186 and 197 of treatment. The failure of animals to respond to exogenous GnRH suggests a direct effect of deslorelin on the pituitary, resulting in a level of desensitization that was sufficient to inhibit a LH surge but insufficient to inhibit basal LH secretion. The variation between animals is believed to result from earlier recovery of some Individuals, in particular those that received a lower dose, or Individual Resistance to the desensitization process.
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effects of a gonadotropin releasing hormone agonist implant on reproduction in a male marsupial macropus eugenii
Biology of Reproduction, 2004Co-Authors: Catherine A Herbert, Geoff Shaw, T E Trigg, Douglas C Eckery, Marilyn B Renfree, D. W. CooperAbstract:This study evaluated the potential of slow-release GnRH agonist (deslorelin) implants to inhibit reproductive function in the male tammar wallaby. The specific aim was to measure the effects of graded dosages of deslorelin on testes size and plasma LH and testosterone concentrations. Adult male tammar wallabies were assigned to four groups (n 5 6 per group) and received the following treatment: control, placebo implant; low dose, 5 mg deslorelin; medium dose, 10 mg; high dose, 20 mg. All dosages of deslorelin induced acute increases (P , 0.001) in plasma LH and testosterone concentrations within 2 h, with concentrations remaining elevated during the first 24 h but returning to pretreatment levels by Day 7. Thereafter, there was no evidence of a treatment-induced decline in plasma testosterone concentrations. There was no detectable difference in basal LH concentrations between treated and control animals, nor was there a significant change in testes width or length (P . 0.05). These results suggest that the male tammar wallaby is resistant to the contraceptive effects of chronic GnRH agonist treatment. Despite the maintenance of testosterone secretion, the majority of male tammars (10 of 17) failed to respond to a GnRH challenge with a release of LH between Days 186 and 197 of treatment. The failure of animals to respond to exogenous GnRH suggests a direct effect of deslorelin on the pituitary, resulting in a level of desensitization that was sufficient to inhibit a LH surge but insufficient to inhibit basal LH secretion. The variation between animals is believed to result from earlier recovery of some Individuals, in particular those that received a lower dose, or Individual Resistance to the desensitization process.
Geoffrey M Attardo - One of the best experts on this subject based on the ideXlab platform.
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frequency of sodium channel genotypes and association with pyrethrum knockdown time in populations of californian aedes aegypti
Parasites & Vectors, 2021Co-Authors: Lindsey K Mack, Erin Taylor Kelly, Yoosook Lee, Katherine K Brisco, Kaiyuan Victoria Shen, Aamina Zahid, Tess Van Schoor, Anthony J Cornel, Geoffrey M AttardoAbstract:Since their detection in 2013, Aedes aegypti has become a widespread urban pest in California. The availability of cryptic larval breeding sites in residential areas and Resistance to insecticides pose significant challenges to control efforts. Resistance to pyrethroids is largely attributed to mutations in the voltage gated sodium channels (VGSC), the pyrethroid site of action. However, past studies have indicated that VGSC mutations may not be entirely predictive of the observed Resistance phenotype. To investigate the frequencies of VGSC mutations and the relationship with pyrethroid insecticide Resistance in California, we sampled Ae. aegypti from four locations in the Central Valley, and the Greater Los Angeles area. Mosquitoes from each location were subjected to an Individual pyrethrum bottle bioassay to determine knockdown times. A subset of assayed mosquitoes from each location was then analyzed to determine the composition of 5 single nucleotide polymorphism (SNP) loci within the VGSC gene. The distribution of knockdown times for each of the five Californian populations sampled was non-parametric with potentially bimodal distributions. One group succumbs to insecticidal effects around 35–45 min and the second group lasts up to and beyond the termination of the assay (120+ min). We detected 5 polymorphic VGSC SNPs within the sampled California populations. One is potentially new and alternatively spliced (I915K), and four are documented and associated with Resistance: F1534C, V1016I, V410L and S723T. The Central Valley populations (Clovis, Dinuba, Sanger and Kingsburg) are fairly homogenous with only 5% of the mosquitoes showing heterozygosity at any given position. In the Greater LA mosquitoes, 55% had at least one susceptible allele at any of the five SNP loci. The known Resistance allele F1534C was detected in almost all sampled mosquitoes (99.4%). We also observe significant heterogeneity in the knockdown phenotypes of Individuals with the identical VGSC haplotypes suggesting the presence of additional undefined Resistance mechanisms. Resistance associated VGSC SNPs are prevalent, particularly in the Central Valley. Interestingly, among mosquitoes carrying all 4 Resistance associated SNPs, we observe significant heterogeneity in bottle bioassay profiles suggesting that other mechanisms are important to the Individual Resistance of Ae. aegypti in California. Keywords: Aedes aegypti, Resistance, Pyrethroid, IPLEX genotyping, Voltage gated sodium channel, California.
Hadallia Bergeron - One of the best experts on this subject based on the ideXlab platform.
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multi terminal memtransistors from polycrystalline monolayer molybdenum disulfide
Nature, 2018Co-Authors: Vinod K Sangwan, Hongsub Lee, Hadallia Bergeron, Itamar Balla, Megan E Beck, Kan Sheng Chen, Mark C HersamAbstract:Memristors are two-terminal passive circuit elements that have been developed for use in non-volatile resistive random-access memory and may also be useful in neuromorphic computing. Memristors have higher endurance and faster read/write times than flash memory and can provide multi-bit data storage. However, although two-terminal memristors have demonstrated capacity for basic neural functions, synapses in the human brain outnumber neurons by more than a thousandfold, which implies that multi-terminal memristors are needed to perform complex functions such as heterosynaptic plasticity. Previous attempts to move beyond two-terminal memristors, such as the three-terminal Widrow-Hoff memristor and field-effect transistors with nanoionic gates or floating gates, did not achieve memristive switching in the transistor. Here we report the experimental realization of a multi-terminal hybrid memristor and transistor (that is, a memtransistor) using polycrystalline monolayer molybdenum disulfide (MoS2) in a scalable fabrication process. The two-dimensional MoS2 memtransistors show gate tunability in Individual Resistance states by four orders of magnitude, as well as large switching ratios, high cycling endurance and long-term retention of states. In addition to conventional neural learning behaviour of long-term potentiation/depression, six-terminal MoS2 memtransistors have gate-tunable heterosynaptic functionality, which is not achievable using two-terminal memristors. For example, the conductance between a pair of floating electrodes (pre- and post-synaptic neurons) is varied by a factor of about ten by applying voltage pulses to modulatory terminals. In situ scanning probe microscopy, cryogenic charge transport measurements and device modelling reveal that the bias-induced motion of MoS2 defects drives resistive switching by dynamically varying Schottky barrier heights. Overall, the seamless integration of a memristor and transistor into one multi-terminal device could enable complex neuromorphic learning and the study of the physics of defect kinetics in two-dimensional materials.
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multi terminal memtransistors from polycrystalline monolayer molybdenum disulfide
Nature, 2018Co-Authors: Vinod K Sangwan, Hadallia Bergeron, Itamar Balla, Kan Sheng Chen, Megan Beck, Mark C HersamAbstract:Polycrystalline monolayer molybdenum disulfide is used to fabricate a multi-terminal device combining a memristor and a transistor, which can mimic biological neurons with multiple synapses for neuromorphic computing applications. Memristors are two-terminal devices whose Resistance exhibits a memory effect that depends on the current or voltage history. This memory enables such devices to mimic the behaviour of a neural synapse, making them of great interest for creating brain-inspired neuromorphic computing architectures. Basic neural functions have been demonstrated with two-terminal devices, but more complex functions, such as heterosynaptic plasticity, will probably require devices with multiple terminals. Mark Hersam and colleagues combine the restive switching behaviour of a memristor with the gate-tunability of a transistor into one multi-terminal device called a memtransistor. Based on two-dimensional layers of molybdenum disulfide, such memtransistors not only exhibit conventional neural learning behaviour but also heterosynaptic functionality, providing a platform for mimicking biological neurons with multiple synapses. Memristors are two-terminal passive circuit elements that have been developed for use in non-volatile resistive random-access memory and may also be useful in neuromorphic computing1,2,3,4,5,6. Memristors have higher endurance and faster read/write times than flash memory4,7,8 and can provide multi-bit data storage. However, although two-terminal memristors have demonstrated capacity for basic neural functions, synapses in the human brain outnumber neurons by more than a thousandfold, which implies that multi-terminal memristors are needed to perform complex functions such as heterosynaptic plasticity3,9,10,11,12,13. Previous attempts to move beyond two-terminal memristors, such as the three-terminal Widrow–Hoff memristor14 and field-effect transistors with nanoionic gates15 or floating gates16, did not achieve memristive switching in the transistor17. Here we report the experimental realization of a multi-terminal hybrid memristor and transistor (that is, a memtransistor) using polycrystalline monolayer molybdenum disulfide (MoS2) in a scalable fabrication process. The two-dimensional MoS2 memtransistors show gate tunability in Individual Resistance states by four orders of magnitude, as well as large switching ratios, high cycling endurance and long-term retention of states. In addition to conventional neural learning behaviour of long-term potentiation/depression, six-terminal MoS2 memtransistors have gate-tunable heterosynaptic functionality, which is not achievable using two-terminal memristors. For example, the conductance between a pair of floating electrodes (pre- and post-synaptic neurons) is varied by a factor of about ten by applying voltage pulses to modulatory terminals. In situ scanning probe microscopy, cryogenic charge transport measurements and device modelling reveal that the bias-induced motion of MoS2 defects drives resistive switching by dynamically varying Schottky barrier heights. Overall, the seamless integration of a memristor and transistor into one multi-terminal device could enable complex neuromorphic learning and the study of the physics of defect kinetics in two-dimensional materials18,19,20,21,22.