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Academic literature on the topic 'SPIKE PULSER'

Author: Grafiati
Published: 11 September 2023

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Journal articles on the topic "SPIKE PULSER"

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Boileau, Etienne, and Christoph Dieterich. "RNA Modification Level Estimation with pulseR." Genes 9, no. 12 (December 10, 2018): 619. http://dx.doi.org/10.3390/genes9120619.

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RNA modifications regulate the complex life of transcripts. An experimental approach called LAIC-seq was developed to characterize modification levels on a transcriptome-wide scale. In this method, the modified and unmodified molecules are separated using antibodies specific for a given RNA modification (e.g., m6A). In essence, the procedure of biochemical separation yields three fractions: Input, eluate, and supernatent, which are subjected to RNA-seq. In this work, we present a bioinformatics workflow, which starts from RNA-seq data to infer gene-specific modification levels by a statistical model on a transcriptome-wide scale. Our workflow centers around the pulseR package, which was originally developed for the analysis of metabolic labeling experiments. We demonstrate how to analyze data without external normalization (i.e., in the absence of spike-ins), given high efficiency of separation, and how, alternatively, scaling factors can be derived from unmodified spike-ins. Importantly, our workflow provides an estimate of uncertainty of modification levels in terms of confidence intervals for model parameters, such as gene expression and RNA modification levels. We also compare alternative model parametrizations, log-odds, or the proportion of the modified molecules and discuss the pros and cons of each representation. In summary, our workflow is a versatile approach to RNA modification level estimation, which is open to any read-count-based experimental approach.
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Kumar, N. Pavan, and V. H. Patankar. "Design and development of water-immersible two-channel high-voltage spike pulser for under-water inspection and gauging of pipes." Review of Scientific Instruments 93, no. 1 (January 1, 2022): 014703. http://dx.doi.org/10.1063/5.0072733.

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Cai, Changsi, Qiushi Ren, Neal J. Desai, Joseph F. Rizzo, and Shelley I. Fried. "Response variability to high rates of electric stimulation in retinal ganglion cells." Journal of Neurophysiology 106, no. 1 (July 2011): 153–62. http://dx.doi.org/10.1152/jn.00956.2010.

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To improve the quality of prosthetic vision, it is important to understand how retinal neurons respond to electric stimulation. Previous studies present conflicting reports as to the maximum rate at which retinal ganglion cells can “follow” pulse trains, i.e., generate one spike for each pulse of the train. In the present study, we measured the response of 5 different types of rabbit retinal ganglion cells to pulse trains of 100–700 Hz. Surprisingly, we found significant heterogeneity in the ability of different types to follow pulse trains. For example, brisk transient (BT) ganglion cells could reliably follow pulse rates up to 600 pulses per second (PPS). In contrast, other types could not even follow rates of 200 PPS. There was additional heterogeneity in the response patterns across those types that could not follow high-rate trains. For example, some types generated action potentials in response to approximately every other pulse, whereas other types generated one spike per pulse for a few consecutive pulses and then did not generate any spikes in response to the next few pulses. Interestingly, in the types that could not follow high-rate trains, we found a second type of response: many pulses of the train elicited a biphasic waveform with an amplitude much smaller than that of standard action potentials. This small waveform was often observed following every pulse for which a standard spike was not elicited. A possible origin of the small waveform and its implication for effective retinal stimulation are discussed.
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Shim, Chi Hyun, Ki Moon Nam, Yong Woon Parc, and Dong Eon Kim. "Isolated terawatt sub-attosecond high-energy x-ray pulse generated by an x-ray free-electron laser." APL Photonics 7, no. 5 (May 1, 2022): 056105. http://dx.doi.org/10.1063/5.0067074.

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The endless quest for dynamics in natural phenomena has resulted in the generation and application of attosecond pulses to trace electron dynamics in atomic and molecular systems. The next challenge is to generate powerful pulses on the zeptosecond time scale, which is currently inaccessible. Through a simulation study, a new type of x-ray source that can generate an isolated terawatt sub-attosecond pulse at high-energy x rays by combining attosecond pulse technology with free-electron laser technology is proposed. The successful generation of a sub-attosecond pulse necessitates the consideration of nanometer-wide current-spikes, the sub-attosecond pulse amplification, and pulse duration and background noise control. The underlying interaction mechanism between a sub-attosecond pulse and a current-spike is closely investigated using the simulation results. The proposed method is expected to produce an isolated ∼700 zs pulse with a peak output of 2.9 TW at a photon energy of 247.5 keV.
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Tanner, Kylie M., Chinyere Obasi, Ian A. Herrick, and L. Stan Leung. "Effects of Propofol on Hippocampal Synaptic Transmission in Behaving Rats." Anesthesiology 93, no. 2 (August 1, 2000): 463–72. http://dx.doi.org/10.1097/00000542-200008000-00026.

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Background The action of propofol has been studied in vitro and in vivo, but the effects of intravenously administered propofol on synaptic transmission in freely behaving rats have not been studied before. Methods Rats were implanted with recording electrodes in the dentate gyrus and with stimulation electrodes in the medial perforant path (MPP). Paired pulses at different interpulse intervals (IPIs) were delivered to the MPP, and average evoked potentials were recorded in the dentate gyrus before and after a bolus of propofol (10 or 20 mg/kg administered intravenously) or control vehicle was injected via femoral vein cannula. Because of the layered structure of the hippocampus, population excitatory postsynaptic potentials and population spikes could be distinguished and analyzed. Results Propofol has no significant effect on the population excitatory postsynaptic potentials or population spike evoked by a single MPP stimulus pulse. However, paired-pulse inhibition of the dentate population spikes was increased at IPI of 20 and 30 ms. Paired-pulse inhibition of the population spike was most prominent when tail pinch response was lost (deep and moderate anesthesia), but it persisted during light anesthesia. At 200 ms IPI, paired-pulse facilitation of population spikes was observed during moderate anesthesia in most rats. Conclusions In freely behaving rats, intravenous propofol enhanced paired-pulse inhibition at < 50 ms IPI, likely by enhancing gamma-aminobutyric acid A receptor-mediated inhibition. Propofol also increased paired-pulse facilitation at 200 ms IPI through an unknown mechanism, which may contribute to the neuroexcitatory effect of propofol.
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Saito, Mitsuru, Yoshinaka Murai, Hajime Sato, Yong-Chul Bae, Tadashi Akaike, Masahiko Takada, and Youngnam Kang. "Two Opposing Roles of 4-AP–Sensitive K+ Current in Initiation and Invasion of Spikes in Rat Mesencephalic Trigeminal Neurons." Journal of Neurophysiology 96, no. 4 (October 2006): 1887–901. http://dx.doi.org/10.1152/jn.00176.2006.

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The axon initial segment plays important roles in spike initiation and invasion of axonal spikes into the soma. Among primary sensory neurons, those in the mesencephalic trigeminal nucleus (MTN) are exceptional in their ability to initiate soma spikes (S-spikes) in response to synaptic inputs, consequently displaying two kinds of S-spikes, one caused by invasion of an axonal spike arising from the sensory receptor and the other initiated by somatic inputs. We investigated where spikes are initiated in such MTN neurons and whether there are any differences between the two kinds of S-spikes. Simultaneous patch-clamp recordings from the soma and axon hillock revealed a spike-backpropagation from the spike-initiation site in the stem axon to the soma in response to 1-ms somatic current pulse, which disclosed the delayed emergence of S-spikes after the current-pulse offset. These initiated S-spikes were smaller in amplitude than S-spikes generated by stimulation of the stem axon; however, 4-AP (≤0.5 mM) eliminated the amplitude difference. Furthermore, 4-AP dramatically shortened the delay in spike initiation without affecting the spike-backpropagation time in the stem axon, whereas it substantially prolonged the refractory period of S-spikes arising from axonal-spike invasion without significantly affecting that of presumed axonal spikes. These observations suggest that 4-AP–sensitive K+ currents exert two opposing effects on S-spikes depending on their origins: suppression of spike initiation and facilitation of axonal-spike invasion at higher frequencies. Consistent with these findings, strong immunoreactivities for Kv1.1 and Kv1.6, among 4-AP–sensitive and low-voltage–activated Kv1 family examined, were detected in the soma but not in the stem axon of MTN neurons.
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Gomez, G., and J. Atema. "Temporal resolution in olfaction II: time course of recovery from adaptation in lobster chemoreceptor cells." Journal of Neurophysiology 76, no. 2 (August 1, 1996): 1340–43. http://dx.doi.org/10.1152/jn.1996.76.2.1340.

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1. Adaptation and disadaptation rates determine the temporal response properties of sensory receptor cells. In chemoreception, temporal filter properties of receptor cells are poorly understood. We studied the time course of disadaptation in lobster antennular chemoreceptor cells by using in situ high-resolution stimulus measurement and extracellularly recorded spike responses. Fifteen receptor cells were each tested with two series (one at 10 microM, one at 100 microM) of three odor (hydroxyproline) pulses: a 200-ms test pulse, a 5-s adapting pulse, and a 200-ms probe pulse after time intervals ranging from 1 to 60 s. After complete adaptation by the adapting pulse, individual cells recovered at different rates. After 1 s, a third of the cells responded with a mean response of 3 spikes/cell, representing approximately 20% recovery. All cells fully recovered between 10 and 30 s. Mean full recovery was within 25 s, with a time constant of 14 s, independent of stimulus concentration.
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Butkus, Paulius, Sonata Tolvaišienė, and Sebastjanas Kurčevskis. "Validation of a SPICE Model for High Frequency Electroporation Systems." Electronics 8, no. 6 (June 23, 2019): 710. http://dx.doi.org/10.3390/electronics8060710.

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In this paper, we present an analysis and a validation of a simulation program with integrated circuit emphasis (SPICE) model for a pulse forming circuit of a high frequency electroporation system, which can deliver square-wave sub-microsecond (100–900 ns) electric field pulses. The developed SPICE model is suggested for use in evaluation of transient processes that occur due to high frequency operations in prototype systems. A controlled crowbar circuit was implemented to support a variety of biological loads and to ensure a constant electric pulse rise and fall time during electroporation to be independent of the applied buffer bioimpedance. The SPICE model was validated via a comparison of the simulation and experimental results obtained from the already existing prototype system. The SPICE model results were in good agreement with the experimental results, and the model complexity was found to be sufficient for analysis of transient processes. As result, the proposed SPICE model can be useful for evaluation and compensation of transient processes in sub-microsecond pulsed power set-ups during the development of new prototypes.
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Fried, S. I., H. A. Hsueh, and F. S. Werblin. "A Method for Generating Precise Temporal Patterns of Retinal Spiking Using Prosthetic Stimulation." Journal of Neurophysiology 95, no. 2 (February 2006): 970–78. http://dx.doi.org/10.1152/jn.00849.2005.

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The goal of retinal prosthetic devices is to generate meaningful visual information in patients that have lost outer retinal function. To accomplish this, these devices should generate patterns of ganglion cell activity that closely resemble the spatial and temporal components of those patterns that are normally elicited by light. Here, we developed a stimulus paradigm that generates precise temporal patterns of activity in retinal ganglion cells, including those patterns normally generated by light. Electrical stimulus pulses (≥1-ms duration) elicited activity in neurons distal to the ganglion cells; this resulted in ganglion cell spiking that could last as long as 100 ms. However, short pulses, <0.15 ms, elicited only a single spike within 0.7 ms of the leading edge of the pulse. Trains of these short pulses elicited one spike per pulse at frequencies ≤250 Hz. Patterns of short electrical pulses (derived from normal light elicited spike patterns) were delivered to ganglion cells and generated spike patterns that replicated the normal light patterns. Finally, we found that one spike per pulse was elicited over almost a 2.5:1 range of stimulus amplitudes. Thus a common stimulus amplitude could accommodate a 2.5:1 range of activation thresholds, e.g., caused by differences arising from cell biophysical properties or from variations in electrode-to-cell distance arising when a multielectrode array is placed on the retina. This stimulus paradigm can generate the temporal resolution required for a prosthetic device.
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Wüstenberg, Daniel G., Milena Boytcheva, Bernd Grünewald, John H. Byrne, Randolf Menzel, and Douglas A. Baxter. "Current- and Voltage-Clamp Recordings and Computer Simulations of Kenyon Cells in the Honeybee." Journal of Neurophysiology 92, no. 4 (October 2004): 2589–603. http://dx.doi.org/10.1152/jn.01259.2003.

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The mushroom body of the insect brain is an important locus for olfactory information processing and associative learning. The present study investigated the biophysical properties of Kenyon cells, which form the mushroom body. Current- and voltage-clamp analyses were performed on cultured Kenyon cells from honeybees. Current-clamp analyses indicated that Kenyon cells did not spike spontaneously in vitro. However, spikes could be elicited by current injection in approximately 85% of the cells. Of the cells that produced spikes during a 1-s depolarizing current pulse, approximately 60% exhibited repetitive spiking, whereas the remaining approximately 40% fired a single spike. Cells that spiked repetitively showed little frequency adaptation. However, spikes consistently became broader and smaller during repetitive activity. Voltage-clamp analyses characterized a fast transient Na+ current ( INa), a delayed rectifier K+ current ( IK,V), and a fast transient K+ current ( IK,A). Using the neurosimulator SNNAP, a Hodgkin–Huxley-type model was developed and used to investigate the roles of the different currents during spiking. The model led to the prediction of a slow transient outward current ( IK,ST) that was subsequently identified by reevaluating the voltage-clamp data. Simulations indicated that the primary currents that underlie spiking are INa and IK,V, whereas IK,A and IK,ST primarily determined the responsiveness of the model to stimuli such as constant or oscillatory injections of current.
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Dissertations / Theses on the topic "SPIKE PULSER"

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Keith, William Douglas. "Microbial reduction in flour and spice using pulsed electric fields." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ33308.pdf.

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Tang, Yunxin. "Investigation of multi-joule TEA CO2 laser based on magnetic-spiker sustainer discharge technology." Thesis, Heriot-Watt University, 1998. http://hdl.handle.net/10399/1995.

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Mejecaze, Guillaume. "Analyse des destructions d'alimentations électroniques soumises à un courant impulsionnel fort niveau." Thesis, Bordeaux, 2019. http://www.theses.fr/2019BORD0204.

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Depuis plus d'une trentaine d'années, la menace d'impulsion électromagnétique provoquée par une explosion à haute altitude (IEMN-HA) d'une arme nucléaire est un sujet d'actualité avec les préoccupations croissantes de sécurité. L'IEMN-HA se couple de manière privilégiée sur les lignes aériennes de distribution en électricité permettant d'alimenter les habitations et les usines. Une fois couplée à ces lignes, la contrainte générée peut alors se propager de façon conduite jusqu'aux premiers systèmes qu'elle rencontrera, et les perturber voire les détruire. Dans la majorité des cas, ces systèmes sont les alimentations des appareils domestiques ou industriels. Dans ce cadre, les effets de destruction d'alimentations électroniques lors de l'injection d'un courant impulsionnel de forte amplitude sont étudiés grâce à un moyen d'injection appelé PIC pour Plateforme d'Injection en Courant. Une alimentation à découpage de type flyback, représentative d'une majorité des alimentations actuelles, a été conçue pour la thèse afin de maîtriser entièrement sa topologie et ses constituants. Les composants les plus susceptibles dans une alimentation à découpage ont été mis en évidence, et il a été montré qu'ils sont détruits à cause d'une amplitude trop importante de courant pendant une durée excessive par rapport aux maximums de leurs capacités. Des analyses aux rayons~X et au microscope optique ont été réalisées sur les composants pour aider à la compréhension. Celles-ci ont permis de fournir des premières hypothèses sur la cause de leur destruction, qui ont ensuite été confirmées par des mesures de courants et de tensions autour de chaque composant lors de l'injection de l'impulsion en entrée de l'alimentation. Enfin, le moyen d'injection ainsi que l'alimentation conçue ont été modélisés sous un logiciel de simulation électronique de type Spice. Cette thèse est la première étape d'un travail dont l'objectif final est de modéliser la susceptibilité des alimentations à découpage afin de prédire leur niveau de destruction
For thirty years, the threat of electromagnetic pulses caused by a high-altitude nuclear explosion (NEMP / HEMP) is still an actual concern in the field of security and safety. NEMP couples efficiently on aerial lines of the electricity network allowing to supply houses and factories. Once coupled to these lines, the generated interference can then be propagated to the first encountered systems and disturb or destroy them. In most cases, these systems are household or industries appliances power supplies. In this context, destruction effects of electronic power supplies due to high level current pulse injectionare studied thanks to an injection generator called PIC for Current Injection Platform. A flyback switch mode power supply (SMPS), representative of a majority of common power supplies, has been designed for the thesis in order to fully control its topology and components. The most susceptible components in SMPS have been identified and have been destroyed due to a too high level current over an excessive duration compared to their maximum ratings. These understandings have been supported by X-rays and optical microscope analyzes. These ones allowed to provide first hypotheses on their destruction cause, which were then confirmed by current and voltage measurements on each component during the pulse injection. Finally, PIC and the designed SMPS have been modeled using a Spice electronic simulation software. This thesis is the first step of a work whose final objective is to model the susceptibility of SMPS in order to predict their destruction level
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Hanna, Hanna. "Electropermeabilization of inner and outer cell membranes with microsecond pulsed electric fields : effective new tool to control mesenchymal stem cells spontaneous Ca2+ oscillations." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLS493/document.

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Les champs électriques pulsés sont largement utilisés dans la recherche, la médecine, l'industrie alimentaire et d'autres procédés biotechnologiques. L'interaction d'une impulsion de 100 µs avec la membrane plasmique et la membrane du réticulum endoplasmique a été évaluée dans deux types cellulaires différents. La perméabilisation des organites cellulaires avec ce type d'impulsions est démontrée expérimentalement pour la première fois. L'utilisation d'une telle impulsion afin de contrôler les oscillations calciques spontanées dans les cellules souches mésenchymateuses humaines issues du tissu adipeux a été évaluée. En créant des pics calciques électro-induits d’amplitudes différentes, l'impulsion peut ou bien induire un pic calcique supplémentaire ou bien inhiber les oscillations spontanées pour quelques dizaines de minutes. Cette inhibition rend possible d’imposer à la cellule des pics d’amplitude et de fréquence désirés. Un essai d’application de l'impulsion 100 µs à des cellules souches subissant une différenciation osseuse a aussi été réalisé. Une impulsion électrique semble retarder la différenciation. Lors d'une différenciation osseuse, plusieurs couches cellulaires ont été observées. La caractérisation de ces couches a donné des résultats qui pourraient aider à obtenir des ostéoblastes matures dans un temps moindre que la normale. L'utilisation des champs électriques pulsés microsecondes, pour perméabiliser la membrane plasmique et les membranes internes des cellules, ainsi que pour moduler les concentrations du calcium intracellulaire, semble donc très intéressante pour étudier le rôle du calcium dans de nombreux processus physiologiques et pour manipuler les dynamiques calciques (oscillations, vagues, pics) dans différents types de cellules. Ainsi, cette technologie simple, facile à appliquer et disponible dans beaucoup de laboratoires serait envisageable pour la modulation et le contrôle de fonctions cellulaires basiques telles que la prolifération, la différenciation et l'apoptose
Pulsed electric fields are widely used in research, medicine, food industry and other biotechnological processes. The interaction of one 100 µs pulse with the plasma membrane and the endoplasmic reticulum membrane was evaluated in two different cell types. Pulse amplitude ranged between 100 and 3 000 V/cm. Organelles membrane permeabilization using this kind of pulses was experimentally demonstrated for the first time. The use of such a pulse to control the spontaneous calcium oscillations in human-adipose mesenchymal stem cells was also assessed. By creating electro-induced calcium spikes of different amplitudes, the pulse can either add a supplementary spike, or, on the contrary, inhibit the spontaneous oscillations for some tens of minutes. During this inhibition period, the electric pulse-mediated addition of calcium spikes of desired amplitude and frequency is still possible. The delivery of 100 µs pulses to stem cells undergoing osteodifferentiation was also performed. The electric pulse seemed to delay the differentiation. Moreover, during osteogenic differentiation, cells cultures displayed an organization in a few cell layers. The characterization of these layers gave results that may help to obtain mature osteoblast in less time than usual one. The use of the microsecond electric pulses technology to permeabilize the plasma and the internal cell membranes as well as to modulate internal calcium concentrations is therefore interesting to study the role of calcium in many physiological processes and to manipulate the cell calcium dynamics (oscillations, waves, spikes) in different cell types. Doing so, this available, simple and easy to apply technology could be used for the modulation and the control of basic cellular functions such as proliferation, differentiation and apoptosis
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Rodriguez, Mayra Mercedes Zegarra. "Análise da evolução da dinâmica de uma cultura de neurônios dissociados em matriz de microeletrodos usando Coerência Parcial Direcionada e Redes Complexas." Universidade Federal de São Carlos, 2012. https://repositorio.ufscar.br/handle/ufscar/516.

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Made available in DSpace on 2016-06-02T19:06:01Z (GMT). No. of bitstreams: 1 4845.pdf: 2916613 bytes, checksum: aa64366fdbe9befa8f14547fa4545763 (MD5) Previous issue date: 2012-08-18
Multi-Electrode Array, MEA, was developed more than thirty years ago. This planar device of multiple microelectrodes has been used to detect local electric potential variations created by the ion movement through the protein channels that traverses the cell membranes in the near neighborhood. MEA offers the possibility of non invasive registering of the cell and their network s activities, allowing to know how the neurons start to connect through the synapses forming a network and generating spontaneous electrophysiological activities. In order to understand the neural network dynamics in face of the spontaneous activities and its evolution in dissociated hippocampal cell cultures, important properties in the synaptic plasticity, in this work it is proposed the analysis of the evolution and modeling of the hippocampal cell cultures in MEA using the theory of Partial Directed Coherence and Complex Networks. There were used the electrophysiological records obtained using MEA60 System, of the dissociated neurons of 18 days old Wistar rat embyo, in an experiment denoted as 371, realized at the University of Genoa, Italy. As the results obtained using the Partial Directed Coherence approach, it was verified that the method is capable to detect neuronal connectivity in the neuron cultures using MEA, even with the noisy signals. It was also verified that different time delays between signals during application of the PDC method do not affect directly on the results of the causality. PDC allowed to show that in MEA the amount of direct connections resulted is less than the amount of indirect connections, through the microelectrodes. This can indicate that the neurons prefer to communicate through existing connections than creating new connections. It was also observed that it is easier to lose direct connections than indirect connections between microelectrodes through the time. Through the experiments it can be observed that the culture in 25 DIV (Days In Vitro) developed more amount of connections between neighboring electrodes, with less overall connections than the culture in 46 DIV, that had more overall connections with less neighborhood connections. Since one of the PDC features is the directionality detection between connections, it was observed direction changes through the connections through the time, even though we do not know the physiological meaning of these changes in the cognitive process. It was also observed that the established connections do not follow random patterns, showing an indicative of a free scale network, although we used small statistical measures to characterize the networks.
Há mais de 30 anos a Matriz de microeletrodos (Multi-Electrode Array,MEA) foi desenvolvida. Este dispositivo planar de múltiplos microeletrodos tem permitido detectar as variações do potencial elétrico local que são criadas pelo movimento de íons através dos canais de proteínas que atravessam as membranas das células neuronais em sua vizinhança imediata. A MEA oferece a possibilidade de gravação não-invasiva da atividade das células e de redes de células, permitindo-nos conhecer como os neurônios se comunicam através de sinapses formando uma rede e disparando atividades eletrofisiológicas espontâneas evocadas. No sentido de poder entender melhor a dinâmica das redes neurais em termos de atividades espontâneas e sua evolução em culturas de células hipocampais dissociadas, que são as propriedades mais importantes na plasticidade sináptica, neste trabalho é proposta a análise da evolução e o modelamento de culturas de células hipocampais na MEA usando a teoria de Coerência Parcial Direcionada (PDC) e de Redes Complexas. Foram usados os registros eletrofisiológicos obtidos usando o sistema MEA60, de neurônios dissociados de embrião de rato Wistar, de 18 dias de vida em um experimento denotado como 371, realizado na Universidade de Gênova, Itália. Como resultados obtidos ao utilizar o método de Coerência Parcial Direcionada, verificou-se que o método é capaz de detectar conectividade neuronal nas culturas de neurônios da MEA, mesmo com sinais com presença de ruído. Também verificou-se que tempos de atraso diferentes na aplicação do PDC não tem uma influência direta nos resultados de causalidade. O PDC permitiu mostrar que na MEA a quantidade de conexões diretas estabelecidas foram sempre em menor quantidade do que as conexões indiretas, através de caminhos. Isso pode ser um indicativo de que os neurônios preferem estabelecer comunicações usando caminhos ja existentes do que criando novas conexões. Também observou-se que com o passar do tempo é mais fácil se perderem conexões diretas do que conexões intermediárias entre neurônios. Através dos experimentos realizados pode se obervar que a cultura no 25 DIV (dias in vitro) desenvolveu maior quantidade de conexões com nós vizinhos, possuindo menos conexões em total, do que a rede no 46 DIV que teve maior quantidade de conexões total mas menor quantidade de conexões com nós vizinhos. Como uma das características do PDC é a deteção da direcionalidade nas conexões, observouse mudanças no sentido das conexões ao longo do registro, embora não saibamos ainda o significado fisiológico dessas mudanças em processos cognoscitivos. Também observou-se que as conexões estabelecidas não seguiam um padrão aleatório, encontrando-se um indicativo de um comportamento de redes livres de escala, embora não possamos afirmar isso por ter utilizado poucas medidas estatísticas para caracterizar as redes.
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JAIN, MANISHA. "DESIGN OF SPIKE PULSER FOR ULTRASONIC APPLICATIONS." Thesis, 2023. http://dspace.dtu.ac.in:8080/jspui/handle/repository/20134.

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The spike pulser serves the purpose of generating high-energy pulses with precise characteristics necessary to excite ultrasonic transducers effectively. It consists of essential elements including an amplifier stage, timing/control circuitry, and power supply components. By receiving an input signal, typically in the form of pulses or square waves, the spike pulser triggers the production of high-energy pulses with specific timing and amplitude properties. In the realm of ultrasonic imaging, the spike pulser plays a vital role in exciting the transducer, which converts electrical energy into ultrasonic waves that propagate through the target medium. The resulting echoes from the medium are subsequently received and processed to produce detailed images of internal structures or potential defects. The pulse characteristics of the spike pulser, including amplitude, duration, and repetition rate, significantly impact the quality and resolution of the resulting ultrasound images. Non-destructive testing and industrial applications also heavily rely on the spike pulser to assess the integrity of materials. By transmitting ultrasonic waves and detecting their reflections, the spike pulser facilitates flaw detection, identification of cracks, and evaluation of material properties. Its ability to generate high-energy pulses enables the detection of subtle flaws and the accurate characterization of materials. This thesis discusses the design and simulation of a high-voltage spike pulser that can deliver voltage up to 650V . The pulse width of the input signal given to the spike pulser is in range from 20ns to 100000ns. Also discussed were power consumed, the amplitude of the spike at the output of spike pulser, and current at load for different pulse widths of input signal given to spike pulser.
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Hung-PangLung and 龍弘邦. "Generation of spiked pulse laser with polymer-stabilized liquid crystals." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/5dqdae.

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碩士
國立成功大學
光電科學與工程學系
105
In this thesis, we study the method to generate spiked pulse laser with polymer-stabilized liquid crystals (PSLCs). By using the characteristic that the transmission of PSLCs can be controlled by an applied electric field, we can apply an AC signal on the PSLC and make it become an optical switch. Furthermore, we place the PSLC into the solid-state laser cavity and cause the laser system to be between the cycle of on-state and off-state. Controlling the laser system in the situation that as soon as the first spiking shows up, the laser system turns off immediately. Therefore, we can get a steady spiked pulse train theoretically. By changing the modulation electric signal, the length of the laser cavity or the weight concentration of polymer monomer in PSLC can control the behavior of spiked pulse.
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Books on the topic "SPIKE PULSER"

1

United States. National Aeronautics and Space Administration., ed. Pulse shaped 8-PSK bandwidth efficiency and spectral spike elimination. Las Cruces, N.M: New Mexico State University, 1998.

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United States. National Aeronautics and Space Administration., ed. Pulse shaped 8-PSK bandwidth efficiency and spectral spike elimination. Las Cruces, N.M: New Mexico State University, 1998.

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United States. National Aeronautics and Space Administration., ed. Pulse shaped 8-PSK bandwidth efficiency and spectral spike elimination. Las Cruces, N.M: New Mexico State University, 1998.

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United States. National Aeronautics and Space Administration., ed. Pulse shaped 8-PSK bandwidth efficiency and spectral spike elimination. Las Cruces, N.M: New Mexico State University, 1998.

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(Editor), Bahram Javidi, and Demetri Psaltis (Editor), eds. Intense Microwave Pulses V (SPIE Proceedings). SPIE-International Society for Optical Engine, 1997.

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(Editor), Victor F. Tarasenko, Georgy V. Mayer (Editor), Gueorgii G. Petrash (Editor), and P. N. Lebedev (Editor), eds. International Conference on Atomic and Molecular Pulsed Lasers IV (Proceedings of SPIE). SPIE Society of Photo-Optical Instrumentation Engi, 2002.

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Fredrich, Raymond P. Nail Pullers. AuthorHouse, 2005.

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Moore, Michael R., and Ehab Farag. Unstable Cervical Spine and Airway Management. Edited by David E. Traul and Irene P. Osborn. Oxford University Press, 2018. http://dx.doi.org/10.1093/med/9780190850036.003.0012.

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In patients with cervical myelopathy, the spinal cord is already compromised to a point at which there is little reserve for surgical maneuvers and the slightest adverse action can result in dramatic consequences. Awake fiberoptic intubation and neurological assessment before induction of anesthesia could be the safest way to avoid waking up the patient before proceeding with surgery in the case of absent motor evoke potentials (MEPs) in spite of increasing the stimulating voltage together with increasing the rate of stimulating pulses. Hypotension is an additional factor, which may lead to irreversible neurologic deficit in a partially compressed but functionally intact spinal cord. Intraoperative neurophysiologic monitoring for cervical myelopathy should include somatosensory evoked potentials, transcranial electric MEPs, and electromyography to provide complementary information and monitor different spinal cord tracts and individual nerve roots.
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Society of Photo-Optical Instrumentation Engineers (Corporate Author) and Yehuda B. Band (Editor), eds. Optical Pulse and Beam Propagation: Proceedings of Spie 27-28 January 1999 San Jose, California (Proceedings of Spie--the International Society for Optical Engineering, V. 3609.). Society of Photo Optical, 1999.

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Intense Microwave Pulses VI: Proceedings of Spie 5 - 6 April 1999, Orlando, Florida (Proceedings of Spie--the International Society for Optical Engineering, Laser Optics '98). Society of Photo Optical, 1999.

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Book chapters on the topic "SPIKE PULSER"

1

Perthame, Benoît. "Spikes, Spots and Pulses." In Lecture Notes on Mathematical Modelling in the Life Sciences, 87–103. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-19500-1_5.

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Rosenthal, Richard M. "Pulsed Radiofrequency Procedures in Clinical Practice." In Image-Guided Spine Interventions, 175–205. New York, NY: Springer New York, 2010. http://dx.doi.org/10.1007/978-1-4419-0352-5_9.

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Kobayashi, Takayoshi. "Elimination of Coherence Spike in Reflection-Type Pump-Probe Measurements." In Ultrashort Pulse Lasers and Ultrafast Phenomena, 269–74. Boca Raton: CRC Press, 2023. http://dx.doi.org/10.1201/9780429196577-41.

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Kabe, Takahiro, Hiroyuki Torikai, and Toshimichi Saito. "Synchronization Via Multiplex Spike-Trains in Digital Pulse Coupled Networks." In Neural Information Processing, 1141–49. Berlin, Heidelberg: Springer Berlin Heidelberg, 2006. http://dx.doi.org/10.1007/11893295_126.

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Weisbein, Jackie, Michael Esposito, Timothy R. Deer, and Nomen Azeem. "Types of Radiofrequency Ablation-Pulsed Radiofrequency Ablation." In Essentials of Radiofrequency Ablation of the Spine and Joints, 31–40. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-78032-6_3.

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Liu, X. Y., Y. Y. Wang, H. Wan, and Z. G. Shang. "Novel Algorithm to Suppress Random Pulse Interference in Spikes." In IFMBE Proceedings, 554–57. Berlin, Heidelberg: Springer Berlin Heidelberg, 2013. http://dx.doi.org/10.1007/978-3-642-29305-4_145.

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Posner, Fred, and Karl Gerlach. "The Life and Times of A Sea Spike: A Study of Wideband Sea Clutter at High Range Resolutions and Very Low Grazing Angles." In Ultra-Wideband, Short-Pulse Electromagnetics 6, 75–84. Boston, MA: Springer US, 2003. http://dx.doi.org/10.1007/978-1-4419-9146-1_7.

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Joachimczak, Michal, Beata Grzyb, and Daniel Jelinski. "Universal Spike-Train Processor for a High-Speed Simulation of Pulsed Para-neural Networks." In Neural Information Processing, 416–21. Berlin, Heidelberg: Springer Berlin Heidelberg, 2004. http://dx.doi.org/10.1007/978-3-540-30499-9_63.

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Suedomi, Yasuhiro, Hakaru Tamukoh, Michio Tanaka, Kenji Matsuzaka, and Takashi Morie. "Parameterized Digital Hardware Design of Pulse-Coupled Phase Oscillator Model toward Spike-Based Computing." In Neural Information Processing, 17–24. Berlin, Heidelberg: Springer Berlin Heidelberg, 2013. http://dx.doi.org/10.1007/978-3-642-42051-1_3.

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Stoeter, P., and N. Prey. "Pulse-Synchronous Alterations of Contrast Density During Carotid Angiography." In Imaging of Brain Metabolism Spine and Cord Interventional Neuroradiology Free Communications, 649–52. Berlin, Heidelberg: Springer Berlin Heidelberg, 1989. http://dx.doi.org/10.1007/978-3-642-74337-5_186.

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Conference papers on the topic "SPIKE PULSER"

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Tarpara, Eaglekumar G., and V. H. Patankar. "Design and development of high voltage ultrasonic spike pulser for immersion applications." In 2017 International Conference on Intelligent Computing, Instrumentation and Control Technologies (ICICICT). IEEE, 2017. http://dx.doi.org/10.1109/icicict1.2017.8342638.

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Watson, Ian A., Chris C. Chatwin, Donny W. McDonald, and Brain F. Scott. "A pulsed CO2 laser to process high damage threshold materials." In The European Conference on Lasers and Electro-Optics. Washington, D.C.: Optica Publishing Group, 1994. http://dx.doi.org/10.1364/cleo_europe.1994.cml7.

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Pulsed CO2 lasers with suitable output characteristics can efficiently process high reflectivity and/or refractory materials. Following a combined simulation and experimental research programme on both the laser and the interaction process, a transversely excited, high PRF, CO2 laser was constructed.1,2 Fig. 1 shows the pumping circuit configuration. To enter the highly absorbing interaction regime, an incident flux intensity of 1011W m-2 is required with a pulse duration between 6–8µs and, to avoid the deleterious melt-freeze process of conventional pulse modulated CW sources, a pulse repetition frequency (PRF) of 5–10 kHz is necessary. The specific energy density of the pumping medium to generate such optical pulses is approximately 12 J 1-1atmosphere-1. Consequently, the gas discharge operates in a substantially different regime to that of TEA lasers, and instabilities due to gas shock wave effects are reduced. Conventional trigger wires were utilised to generate an auxiliary preionising discharge to form stable, uniform glow discharges in a 3-litre cavity over a range of operating conditions, i.e., gas pressure and mixture composition. Analysis of the spatio-temporal development of the electron gain indicates that owing to the low applied E/N the discharge breaks down via the Townsend mechanism. A gas circulation system convectively clears the heated gas from the discharge region. Experimental results are presented for the maximum PRFs achieved with this simple technique of preionisation both with planar-planar electrodes using different laser cavity flow shaping designs (Fig. 3) and for a prototype segmented, ballasted cathode (Fig. 4). Large, gain-switched spikes in the laser output pulse generate intensities sufficiently high to form a plasma above the workpiece. Excessive plasma growth decouples the beam from the workpiece, severely degrading the efficiency of the interaction process. Consequently, the magnitude of the gain-switched spike must be controlled. This can be achieved by optimising the design parameters of the optical resonator and the composition of the laser gas mixture.3 Results are presented that clearly demonstrate the effect of the gas composition on the spike power relative to the total power in the laser output pulse (Fig. 5).
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3

Young, Chris, and Charles Fisher. "Solid state spiker/sustainer drivers for excimer lasers." In OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1989. http://dx.doi.org/10.1364/oam.1989.tuaa4.

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Spiker/sustainer or prepulse-type drivers are required for several kinds of excimer laser excitation. This topology offers increased efficiency and discharge stability and increased electrode life. It does this by initiating or preconditioning the discharge to allow uniform energy loading from a modulator that is electrically matched to the discharge impedance. By matching the driver and discharge impedance, bidirectional current oscillations (after the laser pulse) are greatly decreased or eliminated. We present recent advances at Spectra Technology associated with spiker/sustainer drivers for XeCl and KrF lasers. These advances include multiple parallel ferrite isolation switches and solid state techniques for power conditioning. Use of spike/sustainer techniques with a magnetic isolation switch eliminates the need for a low inductance switch for the full discharge current, thus allowing scaling of excimer lasers to high powers. Solid state switching has the potential for improved lifetime over gaseous discharge-type switches. Recent development of pulse compression and spiker/sustainer circuits has opened the way for development of solid state switched modulators for high power excimer laser use.
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MacPherson, D. C., R. C. Swanson, and John L. Carlsten. "Quantum fluctuations and soliton formation in stimulated Raman scattering." In OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1988. http://dx.doi.org/10.1364/oam.1988.fq3.

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We used the Stokes output from an H2 Raman generator at 10 atm to seed a Raman amplifier. Before entering the amplifier a phase shift was electrooptically placed in the Stokes seed. Although a solitonlike pulse was regularly produced in the pump beam, its amplitude varied greatly. Subsequent studies of the Stokes seed’s power spectrum revealed large shot-to-shot fluctuations. The power spectrum normally consisted of a single near-transform-limited spike whose location jumped from shot to shot and for some shots consisted of two well-resolved spikes. Druhl found theoretically that shifting the Stokes seed slightly off resonance caused the soliton pulse to decay. These frequency fluctuations may thus explain soliton decay. It has also been predicted that solitons will be produced in the output of the Raman generator due to phase shifts resulting from the quantum noise which initiates the Stokes pulse.
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5

Yamasaki, F. S., E. Schamiloglu, J. O. Rossi, and J. J. Barroso. "Spice simulations of nonlinear gyromagnetic lines." In 2015 IEEE Pulsed Power Conference (PPC). IEEE, 2015. http://dx.doi.org/10.1109/ppc.2015.7296895.

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6

Stoyanov, D. V., L. L. Gurdev, and T. N. Dreischuh. "Filtering of Pulse-Spike-Induced Uncertainty In Deconvolved Doppler-Lidar Power Profiles." In Coherent Laser Radar. Washington, D.C.: Optica Publishing Group, 1995. http://dx.doi.org/10.1364/clr.1995.wb4.

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The deconvolution of lidar profiles is an effective software way to improve the lidar resolution and to extract small-scale aerosol inhomogeneities, especially in coherent CO2 (Doppler and DIAL) lidars, where long laser pulses are emitted as a rule by TE (TEA) CO2 laser transmitters (see e.g.[1]). Different deconvolution techniques, based on the Fourier transformation or Volterra integral equation or a recurrence relation have been developed in [2,3]. As shown in [4], the uncertainty in the measurement of the laser pulse shape (e.g. a spike cut) causes a shift up or down as a whole of the restored lidar profile (with respect to the true one) and distortions in the spectrum of the retrieved inhomogeneities. As a rule the spike duration does not exceed several sampling intervals Δt. On the other hand, the increase of the sampling rate to reduce the uncertainty causes hardware problems such as higher data rate, lower dynamic range etc.
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7

Post, Madison J., and Richard E. Cupp. "The Effects of CO2 Gain-Switched Spikes on Estimating Lidar Doppler Shifts." In Coherent Laser Radar. Washington, D.C.: Optica Publishing Group, 1991. http://dx.doi.org/10.1364/clr.1991.mb2.

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We reported earlier1 that, despite having achieved single-mode output from the TEA laser in NOAA’s pulsed Doppler lidar, we could not estimate Doppler shifts to accuracies better than 100 kHz rms, or about 0.6 m s–1 using a complex pulse-pair algorithm. Inaccuracies of this magnitude are acceptable for mesoscale or terrain-induced flows, but they limit the usefulness of the lidar in studying convective flows and turbulent transfers, where accuracies near 0.1 m s–1 are required.
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8

Yoganandan, Narayan, Prashant Khandelwal, Vaibhav Porwal, and John Humm. "Human Thoracolumbar Spine Tolerance to Injury and Mechanisms From Caudo-Cephalad Impacts." In ASME 2020 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/imece2020-23828.

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Abstract The human thoracolumbar spinal column sustains axial loading under physiological and traumatic loading situations. Clinical studies have focused on the former scenario, and the investigation of low back pain issues and spinal stabilization using artificial devices such as arthroplasty are examples. Investigative studies have largely used quasi-static and vibration loading on the spine segment(s) and spinal columns. The traumatic loading scenario is relatively less researched, and it is a dynamic event. Injuries under this scenario occur in sports, automotive, and combat environments. Impact vectors include flexion-extension modes in automotive crash events. Vertical or caudal to cephalad oriented impacts have been identified in both automotive and military scenarios. Frontal impacts to restrained occupants in the automotive and underbody blast impacts from improvised explosive device in combat situations are examples of the vertical loading vector. Although some studies have been conducted using whole body human cadavers and isolated spinal columns, determinations have not been made of the injury risks and stress and strain responses for a variety of accelerative pulses. The aims of the present investigation were to delineate the internal biomechanics of the spinal column under this impact vector and assess the probability of injury. Male and female whole-body human finite element models were used in the study. The occupants were restrained and positioned on the seat, and caudo-cephalad impacts were applied to the base. Different acceleration-time profiles (pulse durations ranging from 50 to 200 ms and peak accelerations varying from 11 g to 46 g) were used as inputs in both male and female models. The resulting stress-strain profiles in the cortical and cancellous bones were evaluated at different vertebral levels. Using the peak transmitted forces at the thoracolumbar disc level as the response variable, the probability of injury for the male spine was obtained from experimental risk curves for the various accelerative pulses. Results showed that the shorter pulse durations and rise times impart greater loading on the thoracolumbar spine. The analysis of von Mises stress and strain distributions showed that the compression-related fractures of vertebrae are multifaceted with contributions from both the cortical and cancellous bony components of the body. Profiles are provided in the body of the paper for different spinal levels. The intervertebral disc may be involved in the fracture mechanism, because it acts as a medium of load transfer between adjacent vertebrae. Injury risks for the shortest pulse was sixty-three percent, and for the widest pulse it was close to zero, and injury probabilities for other pulses are given. The present computational modeling study provides insights into the mechanisms of the internal load transfer and describe the injury risk levels from caudal to cephalad impacts.
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Bhadani, P. K., Y. X. Tang, and R. G. Harrison. "Multijoule TE CO2 laser using a novel magnetic-spiker sustainer excitation circuit." In The European Conference on Lasers and Electro-Optics. Washington, D.C.: Optica Publishing Group, 1994. http://dx.doi.org/10.1364/cleo_europe.1994.cml5.

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Recently we investigated several innovative approaches for electrical excitation of a TEA CO2 laser1-5 in order to overcome the limitations of existing discharge and switching technology and to provide an overall improvement in the laser performance. In particular, the magneticspiker sustainer excitation circuit has proved to be a power approach for efficient excitation of large volume pulsed CO2 lasers. This has provided high efficiency (15%) variable flat top long duration laser pulses (1–5µs), helium-free operation, and elimination of plasma switch (thyratron/spark gap) from the main discharge path, leading to the development of laser systems with a long operational lifetime and high reliability.
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10

Rossi, Jose O., Joaquim J. Barroso, and Mario Ueda. "Spice Simulation for Hard-Tube Modulators Design." In 2007 IEEE Pulsed Power Plasma Science Conference. IEEE, 2007. http://dx.doi.org/10.1109/ppps.2007.4346092.

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Reports on the topic "SPIKE PULSER"

1

Guercio, Miguel D. A Spice-Based Code for ARL's 4.5-MJ Electromagnetic Launcher Pulsed Power Supply System. Fort Belvoir, VA: Defense Technical Information Center, September 2001. http://dx.doi.org/10.21236/ada398467.

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Jones, Scott B., Shmuel P. Friedman, and Gregory Communar. Novel streaming potential and thermal sensor techniques for monitoring water and nutrient fluxes in the vadose zone. United States Department of Agriculture, January 2011. http://dx.doi.org/10.32747/2011.7597910.bard.

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The “Novel streaming potential (SP) and thermal sensor techniques for monitoring water and nutrient fluxes in the vadose zone” project ended Oct. 30, 2015, after an extension to complete travel and intellectual exchange of ideas and sensors. A significant component of this project was the development and testing of the Penta-needle Heat Pulse Probe (PHPP) in addition to testing of the streaming potential concept, both aimed at soil water flux determination. The PHPP was successfully completed and shown to provide soil water flux estimates down to 1 cm day⁻¹ with altered heat input and timing as well as use of larger heater needles. The PHPP was developed by Scott B. Jones at Utah State University with a plan to share sensors with Shmulik P. Friedman, the ARO collaborator. Delays in completion of the PHPP resulted in limited testing at USU and a late delivery of sensors (Sept. 2015) to Dr. Friedman. Two key aspects of the subsurface water flux sensor development that delayed the availability of the PHPP sensors were the addition of integrated electrical conductivity measurements (available in February 2015) and resolution of bugs in the microcontroller firmware (problems resolved in April 2015). Furthermore, testing of the streaming potential method with a wide variety of non-polarizable electrodes at both institutions was not successful as a practical measurement tool for water flux due to numerous sources of interference and the M.S. student in Israel terminated his program prematurely for personal reasons. In spite of these challenges, the project funded several undergraduate students building sensors and several master’s students and postdocs participating in theory and sensor development and testing. Four peer-reviewed journal articles have been published or submitted to date and six oral/poster presentations were also delivered by various authors associated with this project. We intend to continue testing the "new generation" PHPP probes at both USU and at the ARO resulting in several additional publications coming from this follow-on research. Furthermore, Jones is presently awaiting word on an internal grant application for commercialization of the PHPP at USU.
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Huatian, Xu, and Bi Wuxi. PR469-183600-R01 The Influence of Solid State Decouplers on Pipeline CP Surveys. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), October 2020. http://dx.doi.org/10.55274/r0011935.

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The objectives of this research are to figure out how solid state decouplers (SSDs) influence the surveys related to pipeline cathodic protection (CP) and provide corresponding field guidelines on how to mitigate the adverse effects of SSDs. Firstly, by combining the classical capacitor discharge theory and the equivalent circuit of the CP system, a four-stage physical model is built to explain how SSDs' discharge current pulse influences the CP related readings. From the physical model, we can obtain the following conclusions: (1) The driving force behind the discharging of an SSD's capacitor, after CP currents are cut off, is the voltage drop in the pipeline; (2)There are two contributors to the CP instant-off potential spikes: self-induced pipeline current and SSD discharge current; (3) The time constant ( and tau;=RC) of an SSD installation determines how fast the SSD finishes its discharging process; (4) The adverse effects of SSDs can be mitigated by making the SSD discharge time constant and tau; small enough (3 and tau; Before performing numerical modeling, some commonly used SSDs are tested for their capacitances in the lab according to the classical capacitor impedance theory. The test results show that the typical SSD capacitance is between 0.15 F and 0.36 F. The target pipeline for numerical modeling is a 50 km pipeline with different levels of coating quality, SSD grounding resistance, and SSD capacitance. An equivalent circuit model with ten parallel branches is built accordingly, and solved by an open-source electrical circuit software module. The numerical modeling results firmly support the primary conclusions drawn from the four-stage physical model. Moreover, the parallel analog circuit tests in the lab further prove the rationality of the four-stage model. Finally, comprehensive field tests are performed to study how SSDs influence the CP install-off potential survey, close interval potential survey, direct current voltage gradient, and alternating current voltage gradient. Practical field guidelines on how to mitigate SSDs' influence are proposed.
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