Academic literature on the topic 'Burst potential'
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Journal articles on the topic "Burst potential"
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Brown, Colin H., Gareth Leng, Mike Ludwig, and Charles W. Bourque. "Endogenous Activation of Supraoptic Nucleus κ-Opioid Receptors Terminates Spontaneous Phasic Bursts in Rat Magnocellular Neurosecretory Cells." Journal of Neurophysiology 95, no. 5 (May 2006): 3235–44. http://dx.doi.org/10.1152/jn.00062.2006.
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Phasic activity in magnocellular neurosecretory vasopressin cells is characterized by alternating periods of activity (bursts) and silence. During phasic bursts, action potentials (spikes) are superimposed on plateau potentials that are generated by summation of depolarizing after-potentials (DAPs). Burst termination is believed to result from autocrine feedback inhibition of plateau potentials by the κ-opioid peptide, dynorphin, which is copackaged in vasopressin neurosecretory vesicles and exocytosed from vasopressin cell dendrites during phasic bursts. Here we tested this hypothesis, using intracellular recording in vitro to show that κ-opioid receptor antagonist administration enhanced plateau potential amplitude to increase postspike excitability during spontaneous phasic activity. The antagonist also increased postburst DAP amplitude in vitro, indicating that endogenous dynorphin probably reduces plateau potential amplitude by inhibiting the DAP mechanism. However, the κ-opioid receptor antagonist did not affect the slow depolarization that follows burst termination, suggesting that recovery from endogenous κ-opioid inhibition does not contribute to the slow depolarization. We also show, by extracellular single-unit recording, that that there is a strong random element in the timing of burst initiation and termination in vivo. Administration of a κ-opioid receptor antagonist eliminated the random element of burst termination but did not alter the timing of burst initiation. We conclude that dendritic dynorphin release terminates phasic bursts by reducing the amplitude of plateau potentials to reduce the probability of spike firing as bursts progress. By contrast, dendritic dynorphin release does not greatly influence the membrane potential between bursts and evidently does not influence the timing of burst initiation.
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Salmanpour, Aryan, Lyndon J. Brown, Craig D. Steinback, Charlotte W. Usselman, Ruma Goswami, and J. Kevin Shoemaker. "Relationship between size and latency of action potentials in human muscle sympathetic nerve activity." Journal of Neurophysiology 105, no. 6 (June 2011): 2830–42. http://dx.doi.org/10.1152/jn.00814.2010.
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We employed a novel action potential detection and classification technique to study the relationship between the recruitment of sympathetic action potentials (i.e., neurons) and the size of integrated sympathetic bursts in human muscle sympathetic nerve activity (MSNA). Multifiber postganglionic sympathetic nerve activity from the common fibular nerve was collected using microneurography in 10 healthy subjects at rest and during activation of sympathetic outflow using lower body negative pressure (LBNP). Burst occurrence increased with LBNP. Integrated burst strength (size) varied from 0.22 ± 0.07 V at rest to 0.28 ± 0.09 V during LBNP. Sympathetic burst size (i.e., peak height) was directly related to the number of action potentials within a sympathetic burst both at baseline ( r = 0.75 ± 0.13; P < 0.001) and LBNP ( r = 0.75 ± 0.12; P < 0.001). Also, the amplitude of detected action potentials within sympathetic bursts was directly related to the increased burst size at both baseline ( r = 0.59 ± 0.16; P < 0.001) and LBNP ( r = 0.61 ± 0.12; P < 0.001). In addition, the number of detected action potentials and the number of distinct action potential clusters within a given sympathetic burst were correlated at baseline ( r = 0.7 ± 0.1; P < 0.001) and during LBNP ( r = 0.74 ± 0.03; P < 0.001). Furthermore, action potential latency (i.e., an inverse index of neural conduction velocity) was decreased as a function of action potential size at baseline and LBNP. LBNP did not change the number of action potentials and unique clusters per sympathetic burst. It was concluded that there exists a hierarchical pattern of recruitment of additional faster conducting neurons of larger amplitude as the sympathetic bursts become stronger (i.e., larger amplitude bursts). This fundamental pattern was evident at rest and was not altered by the level of baroreceptor unloading applied in this study.
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Korn, S. J., J. L. Giacchino, N. L. Chamberlin, and R. Dingledine. "Epileptiform burst activity induced by potassium in the hippocampus and its regulation by GABA-mediated inhibition." Journal of Neurophysiology 57, no. 1 (January 1, 1987): 325–40. http://dx.doi.org/10.1152/jn.1987.57.1.325.
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Intracellular and extracellular recordings were made from pyramidal neurons in hippocampal slices in order to study spontaneous paroxysmal bursting induced by raising the extracellular potassium concentration from 3.5 to 8.5 mM. Extracellular recordings from all hippocampal subfields indicated that spontaneous bursts appeared to originate in region CA3c or CA3b as judged by burst onset. Burst intensity was also greatest in regions CA3b and CA3c and became progressively less toward region CA2. Intracellular recordings indicated that in 8.5 mM potassium, large spontaneous excitatory postsynaptic potentials (EPSPs), large burst afterhyperpolarizations, and rhythmic hyperpolarizing-depolarizing waves of membrane potential were invariably present in CA3c neurons. High potassium (8.5 mM) induced a positive shift (+9 mV) in the reversal potential of GABAergic inhibitory postsynaptic potentials (IPSPs) in CA3c neurons without changing input resistance or resting potential. This resulted in a drastic reduction in amplitude of the IPSP. Reduction of IPSP amplitude occurred before the onset of spontaneous bursting and was reversible upon return to normal potassium. A new technique to quantify the relative intensity of interictal-like burst discharges is described. Pentobarbital, diazepam, and GABA uptake inhibitors, which enhance GABA-mediated synaptic inhibition, reduced the intensity of potassium-induced bursts, whereas the GABA antagonist bicuculline increased burst intensity. Diphenylhydantoin and phenobarbital, anticonvulsants that have little effect on GABAergic inhibition, were without effect on spontaneous bursts. Burst frequency was reduced by bicuculline and 4,5,6,7-tetrahydroisoxazolo[5,4-c]pyridin-3-ol but was unaffected by other drugs. Reduction of slice temperature from 35 to 19 degrees C dramatically reduced burst intensity but did not markedly affect burst frequency. We hypothesize that high potassium induces a rise in intracellular chloride concentration, possibly by activating an inward KCl pump or by a passive Donnan effect, which results in a decreased IPSP amplitude. With inhibition suppressed, the large spontaneous EPSPs that appear in high potassium cause individual CA3c neurons to fire. A combination of synaptic and electrical interactions among CA3c cells then synchronizes discharges into interictal spike bursts.
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Robinson, H. P., M. Kawahara, Y. Jimbo, K. Torimitsu, Y. Kuroda, and A. Kawana. "Periodic synchronized bursting and intracellular calcium transients elicited by low magnesium in cultured cortical neurons." Journal of Neurophysiology 70, no. 4 (October 1, 1993): 1606–16. http://dx.doi.org/10.1152/jn.1993.70.4.1606.
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1. In Mg(2+)-free external solution, rat cortical neurons in cultured networks entered a stable firing mode, consisting of regular bursts of action potentials superimposed on long-lasting depolarizations. The average separation between bursts varied from culture to culture, but was usually between 5 and 20 s. The distribution of burst intervals followed a Gaussian or normal distribution, with a standard deviation of typically 10% of the average burst period. 2. A gradually depolarizing pacemaker potential was never observed between bursts, but the threshold for action potentials during the quiescent phase was > or = 10 mV above the resting potential. No progressive change in conductance or excitability was observed during the quiescent period. Intracellular stimulation of action potentials did not reproduce the long-lasting depolarization. 3. Switching from current clamp to voltage clamp at the resting potential revealed large postsynaptic currents, mainly excitatory but with a small inhibitory component, at the same phase and frequency as the spike bursts, showing that periodic synaptic input is responsible for the burst-depolarizations. The current could be eliminated by local application of 2-amino-5-phosphonovaleric acid (APV) or 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) to the postsynaptic cell. In the presence of tetrodotoxin, irregular miniature excitatory postsynaptic currents were observed. 4. A fluorescent calcium indicator (fluo-3, 100 microM) was included in the whole-cell pipette solution, to allow simultaneous electrical and calcium measurements in the same cell. In current clamp, transient intracellular calcium increases were found, which were synchronized to the spike bursts. The Ca2+ rise lasted as long as the action potential burst, and was followed by an exponential decay considerably slower than that of the membrane potential. Calcium transients disappeared during voltage clamp at the resting potential, suggesting that calcium influx through voltage-dependent calcium channels greatly exceeds that through synaptic channels. 5. Multisite Ca2+ recording, after loading with fluo-3 acetoxymethyl (AM) ester, revealed that the onsets of burst-related calcium transients were synchronized in all active cells of each view-field, to within approximately 20 ms. Occasionally, secondary rhythms were observed in which only a subset of cells participated. The times to peak and the decay times of calcium transients varied among synchronized cells. 6. The pharmacology of the burst-related calcium transients was investigated by bath application of a variety of compounds.(ABSTRACT TRUNCATED AT 400 WORDS)
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Dicaprio, R. "Plateau potentials in motor neurons in the ventilatory system of the crab." Journal of Experimental Biology 200, no. 12 (January 1, 1997): 1725–36. http://dx.doi.org/10.1242/jeb.200.12.1725.
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The motor neurons in the crab ventilatory system have previously been considered to be passive output elements in that the generation of bursts of action potentials in these neurons during ventilation was thought to be due to cyclic inhibition and excitation from the interneurons in the ventilatory central pattern generator. This study demonstrates that the large-amplitude depolarization that underlies bursts of action potentials in ventilatory motor neurons is produced by a plateau potential. These motor neurons satisfy a number of the experimental tests that have been proposed for plateau potentials, such as triggering of the burst by a brief depolarization, termination of the burst by a hyperpolarizing input, and an all-or-none suppression of the depolarizing potential by the injection of hyperpolarizing current.
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Lu, S. M., W. Guido, and S. M. Sherman. "Effects of membrane voltage on receptive field properties of lateral geniculate neurons in the cat: contributions of the low-threshold Ca2+ conductance." Journal of Neurophysiology 68, no. 6 (December 1, 1992): 2185–98. http://dx.doi.org/10.1152/jn.1992.68.6.2185.
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1. Thalamic relay cells, including those of the lateral geniculate nucleus, display a low-threshold spike (LT spike), which is a large depolarization due to an increased Ca2+ conductance. Typically riding the crest of each LT spike is a burst of from two to seven action potentials, which we refer to as the LT burst. The LT spike is voltage dependent, because if the cell's resting membrane potential is more depolarized than roughly -60 mV, the LT spike is inactivated, but if more hyperpolarized, the spike is deinactivated and can be activated by a depolarization, such as from an afferent excitatory postsynaptic potential (EPSP). Thalamic relay cells thus display two response modes: a relay or tonic mode, when the cell is depolarized and LT spikes are inactivated, leading to tonic firing of action potentials; and a burst mode, when the cell is hyperpolarized and tends to respond with LT spikes and their associated bursts of action potentials. 2. We were interested in the contribution of the LT spike on the transmission of visually evoked signals through geniculate relay cells to visual cortex. We recorded intracellularly from geniculate cells in an anesthetized, paralyzed, in vivo cat preparation to study the effects of membrane voltage, and thus the presence or absence of LT spikes, on responses to drifting sine-wave gratings. We monitored the visually evoked responses of 14 geniculate neurons (6 X, 7 Y, and 1 unclassified) at different membrane potentials at which LT spikes were inactivated or deinactivated. 3. Changing membrane voltage during visual stimulation switched the response mode of every cell between the relay and burst modes. In the burst mode, LT spikes occurred in phase with the visual stimulus and not at rhythmic intervals uncorrelated to visual stimuli. To any given stimulus cycle, the cell responded usually with an LT burst or a tonic response, and rarely was more than one LT burst evoked by a stimulus cycle. Occasionally a single cycle evoked both an LT burst and tonic response, but always the LT burst occurred first. 4. The spatial tuning characteristics of the cells did not differ dramatically as a function of membrane potential, because the tuning of the LT bursts was quite similar to that of the tonic response component. Although we did not obtain complete temporal tuning properties, we did note that hyperpolarized cells responded reliably with LT bursts at several temporal frequencies. 5. A consistent difference was seen between the LT burst and tonic response components in terms of response linearity.(ABSTRACT TRUNCATED AT 400 WORDS)
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Wang, Yu-Feng, and Glenn I. Hatton. "Milk Ejection Burst-Like Electrical Activity Evoked in Supraoptic Oxytocin Neurons in Slices From Lactating Rats." Journal of Neurophysiology 91, no. 5 (May 2004): 2312–21. http://dx.doi.org/10.1152/jn.00697.2003.
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To examine the mechanisms underlying milk-ejection bursts of oxytocin (OT) neurons during suckling, both in vivo and in vitro studies were performed on supraoptic OT neurons from lactating rats. The bursts were first recorded extracellularly in anesthetized rats. Burst-related electrical parameters were essentially the same as previous reports except for a trend toward transient decreases in basal firing rates immediately preceding the burst. From putative OT neurons in slices with extracellular recordings, bursts that closely mimicked the in vivo bursts were elicited by phenylephrine, an α1-adrenoceptor agonist, in a low-Ca2+ medium. Moreover, in whole cell patch-clamp recordings, the in vitro bursts were recorded from immunocytochemically identified OT neurons. After a transient decrease in the basal firing rate, the in vitro bursts started with a sudden increase in the firing rate, quickly reaching a peak level, then gradually decaying, and ended with a postburst inhibition. A brief depolarization of the membrane potential and an increase in membrane conductance appeared after the onset of the burst. Spikes during a burst were characterized by a significant increase in the duration and decrease in the amplitude around the peak rate firing. These bursts were significantly different from short-lasting burst firing of vasopressin neurons in membrane potential changes, time to reach peak firing rate, spike amplitude and duration during peak rate firing. Our extensive analysis of these results suggests that the in vitro burst is a useful model for further study of mechanisms underlying milk-ejection bursts of OT neurons in vivo.
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Cohen, Dror, and Menahem Segal. "Network bursts in hippocampal microcultures are terminated by exhaustion of vesicle pools." Journal of Neurophysiology 106, no. 5 (November 2011): 2314–21. http://dx.doi.org/10.1152/jn.00969.2010.
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Synchronized network activity is an essential attribute of the brain. Yet the cellular mechanisms that determine the duration of network bursts are not fully understood. In the present study, synchronized network bursts were evoked by triggering an action potential in a single neuron in otherwise silent microcultures consisting of 4–30 hippocampal neurons. The evoked burst duration, ∼2 s, depended on the recovery time after a previous burst. While interburst intervals of 35 s enabled full-length bursts, they were shortened by half at 5-s intervals. This reduction in burst duration could not be attributed to postsynaptic parameters such as glutamate receptor desensitization, accumulating afterhyperpolarization, inhibitory tone, or sodium channel inactivation. Reducing extracellular Ca2+ concentration ([Ca2+]o) relieved the effect of short intervals on burst duration, while depletion of synaptic vesicles with α-latrotoxin gradually eliminated network bursts. Finally, a transient exposure to high [K+]o slowed down the recovery time following a burst discharge. We conclude that the limiting factor regulating burst duration is most likely the depletion of presynaptic resources.
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Golanov, E. V., and D. J. Reis. "Vasodilation evoked from medulla and cerebellum is coupled to bursts of cortical EEG activity in rats." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 268, no. 2 (February 1, 1995): R454—R467. http://dx.doi.org/10.1152/ajpregu.1995.268.2.r454.
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Cerebral blood flow (rCBF), measured by laser-Doppler flowmetry, spontaneously fluctuates at approximately 6 events/min in the anesthetized rat. These cerebrovascular waves (CWs) are preceded by simultaneous and synchronous bursts of electrocorticographic activity similar to burst-suppression/spindle-burst electroencephalogram patterns. Identical burst-CW complexes are evoked by single electrical pulses of specific sites in the cerebellar fastigial nucleus or rostral ventrolateral medulla. These consist, sequentially, of a constant initial triphasic (positive-negative-positive) potential reversing polarity in lamina V, variable afterbursts, and transient elevations of rCBF appearing approximately 1.2 s after burst onset. Evoked bursts are occluded by spontaneous bursts appearing < 50 s earlier. Procainization of the cortex reversibly blocks burst-CW complexes. Gradually increasing stimulus frequency proportionally increases the numbers of burst-CW complexes before rCBF rises. We conclude that spontaneous and evoked burst-CW complexes result from excitation of common neurons in lamina V. These intracortical “vasodilator” neurons are spontaneously excited by thalamocortical afferents generating burst-suppression electroencephalogram (EEG) patterns and excited reflexively by afferent signals from the fastigial nucleus or rostral ventrolateral medulla and couple intrinsic neuronal activity to local vascular mechanisms generating vasodilation.
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Hudetz, Anthony G., and Olga A. Imas. "Burst Activation of the Cerebral Cortex by Flash Stimuli during Isoflurane Anesthesia in Rats." Anesthesiology 107, no. 6 (December 1, 2007): 983–91. http://dx.doi.org/10.1097/01.anes.0000291471.80659.55.
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Background The degree of suppression of sensory functions during general anesthesia is controversial. Here, the authors investigated whether discrete flash stimuli induced cortical field potential responses at an isoflurane concentration producing burst suppression and compared the spatiotemporal properties and frequency spectra of flash-induced burst responses with those occurring spontaneously. Methods Rats were equipped with multiple epidural and intracortical electrodes to record cortical field potentials in the right hemisphere at several locations along the anterior-posterior axis. At isoflurane concentrations of 1.1, 1.4, and 1.8%, discrete light flashes were delivered to the left eye while cortical field potentials were continuously recorded. Results Isoflurane at 1.4-1.8% produced burst suppression. Each flash produced a visual evoked potential in the primary visual cortex followed by secondary bursting activity in more anterior regions. The average latency and duration of these bursts were 220 and 810 ms, respectively. The spontaneous and flash-induced bursts were similar in frequency, duration, and spatial distribution. They had maximum power in the frontal (primary motor) cortex with a dominant frequency of 10 Hz. Conclusions The results suggest that discrete flash stimuli activate the motor regions of the cerebral cortex during isoflurane anesthesia and that these activations are analogous with those that occur spontaneously during burst suppression. Electrocortical suppression of the cortex during anesthesia does not prevent its response to visual stimuli.
Dissertations / Theses on the topic "Burst potential"
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Akin, Faith W., Owen D. Murnane, and Tina M. Proffitt. "The Effects of Click and Tone-Burst Stimulus Parameters on the Vestibular Evoked Myogenic Potential (vemp)." Digital Commons @ East Tennessee State University, 2003. https://dc.etsu.edu/etsu-works/1790.
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Vestibular evoked myogenic potentials (VEMP) are short latency electromyograms (EMG) evoked by high-level acoustic stimuli and recorded from surface electrodes over the tonically contracted sternocleidomastoid (SCM) muscle and are presumed to originate in the saccule. The present experiments examined the effects of click and tone-burst level and stimulus frequency on the latency, amplitude, and threshold of the VEMP in subjects with normal hearing sensitivity and no history of vestibular disease. VEMPs were recorded in all subjects using 100 dB nHL click stimuli. Most subjects had VEMPs present at 500, 750, and 1000 Hz, and few subjects had VEMPs present at 2000 Hz. The response amplitude of the VEMP increased with click and tone-burst level, whereas VEMP latency was not influenced by the stimulus level. The largest tone-burst-evoked VEMPs and lowest thresholds were obtained at 500 and 750 Hz. VEMP latency was independent of stimulus frequency when tone-burst duration was held constant.
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Frizzo, Ana Claudia Figueiredo. "Potenciais evocados auditivos de média latência. Estudo para diferentes níveis de intensidade sonora com estímulo tone-burst em crianças de 10 a 13 anos de idade." Universidade de São Paulo, 2004. http://www.teses.usp.br/teses/disponiveis/17/17140/tde-28092006-105527/.
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Introdução: A captação e o estudo de respostas cerebrais evocadas por um estímulo sonoro vem permitindo a investigação objetiva do processamento da informação auditiva e uma melhor compreensão da via auditiva central. A utilidade deste método diagnóstico tem sido cada vez mais valorizada pelos audiologistas, no entanto sua aplicação clínica corrente requer a realização de uma quantidade mais expressiva de estudos, especialmente na literatura nacional, para um conhecimento mais profundo deste método, sobretudo quanto a normatizações, critérios de identificação das ondas e interferências de variáveis como idade, sexo e parâmetros utilizados na aquisição. Os Potenciais Evocados Auditivos de Média Latência são compostos por uma seqüência de ondas com latências em torno de 10 a 80ms, com origem neurogênica múltipla (projeções tálamo-corticais e córtex auditivo, colículo inferior e formação reticular em menor escala). O presente estudo tem como objetivo pesquisar os componentes dos PEAMLs, numa população de crianças saudáveis, estudando a latência e amplitude das ondas, a fim de conhecer as características dos PEAMLs para esta faixa etária. Metodologia: Participaram do estudo 32 crianças de ambos os sexos com idade entre 10 e 13 anos, otologicamente normais e sem histórias neurológicas. A análise estatística incluiu a realização da estatística descritiva (média e desvio-padrão) e análise da variância pelo teste F. Os PEAMLs foram pesquisados utilizando como estímulo tone-burst, nas intensidades de 50, 60 e 70 dBNA. Resultados e conclusão: Os valores médios de latência dos componentes foram Na=20,79ms, Pa=35,34ms, Nb=43,27ms e Pb=53,36ms. Para a amplitude Na-Pa os valores médios obtidos no estudo variaram entre 0,2 e 1,9mV (M=1,0mV). As formas de onda Na-Pa constituíram os componentes mais consistentes e mais facilmente identificáveis. Pode-se concluir que a amplitude aumenta e a latência diminui com o aumento da intensidade sonora. Na intensidade de 50dBNA as latências obtidas são significativamente maiores que as intensidades de 60 e 70 dBNA para a onda Na. A partir de 60dBNA os valores se estabilizam e não há mudanças significativas na latência ou morfologia da onda. Nas comparações inter e intra-individual foram observadas latências mais longas e amplitudes menores para o lado E (A1/Cz). Numa análise posterior dos dados segundo queixa de dificuldade escolar não foram observadas diferenças ao nível de significância para os componentes Na, Pa, Nb e Pb para os grupos de crianças com e sem queixa de dificuldades escolares. Nestas crianças foram observadas anormalidades na morfologia das ondas, as quais não foram atribuídas exclusivamente à queixa de dificuldade escolar, já que poderia haver também interferência da idade do sujeito avaliado e do neuro-desenvolvimento do Sistema Nervoso Auditivo Central. O presente estudo possibilitou um melhor conhecimento das características dos PEAMLs, o que contribuirá para a aplicação mais segura da técnica. Porém, outros estudos ainda se fazem necessários, principalmente na literatura nacional, a fim de estabelecer padrões normativos para o uso na rotina clínica.Introduction: The record and study of corticals responses evoked by auditory stimulus has allowed the objective investigation from process of auditory information and a better understanding of central auditory path. The utility of the procedure has been valued by audiologists, nevertheless her clinical aplication current demand the a execution a sum more significative of the study, especially in nationals researchs, to knowledge profoundest this procedure, over all as for normative studys, waves?s identification criterion and interference of the variables with age, gender and parameters used in records. The PEAMLs are composed of a waves?s sequence with latency are around 10 a 80ms, with multiple neurogenic origen (thalamus corticais projections and auditory cortex, coliculus inferior and reticular formation in small scale). The present study objetive examined the components dos PEAMLs, in healthy childrens, researching the waves?s latency and amplitude, to know the PEAML in this band of age. Methods: make part of study 32 childrens in both genders between the ages of 10 e 13, normal hearing without neurological desorders. The statistical analises involved the descrition statistical (mean and standard deviation) and variance analises by test F. The PEAMLs are investigated with tone-burst stimuli in 50, 60 e 70 dBNA. Results and conclusions: the means values of the components are Na=20,79ms, Pa=35,34ms, Nb=43,27ms e Pb=53,36ms. To the amplitude Na-Pa the means values obtained in the study varies between 0,2 and 1,9mV (M=1,0mV). The waveforms are more consistents e more easyly identifiable. We are able to conclude that the amplitude increase and latency decrease with growth of intensity of sound. In 50dBNA the latency are significative higher that 60 and 70 dBNA to wave Na. From 60dBNA the values are stabilize and there is no significatives changes in the latency ou morphology of wave. In the comparisions inter e inta-hemisferical were observed latencys lengthest and amplitudes higher to side left (A1/Cz). In a posterior analises in conformity to complaint of hardness scholar were observeds diferrences no significants to the components Na, Pa, Nb e Pb in the childrens groups with and without complaint of hardness scholar. Anormalities in the morphology of waves were viewed in this childrens wich weren´t atribute to complaint of hardness scholar exclusively once there was interference of the patient?s age and the neural development of Central Auditory System Nervous. The present study made possible a better knowledge of PEAMLs and will contribute to securest aplication this procedure. But, another studys still are requisite, essentialy in the researchs national to established normatives standard to utily in the clinical practice.
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Elijah, Daniel. "Neural encoding by bursts of spikes." Thesis, University of Manchester, 2014. https://www.research.manchester.ac.uk/portal/en/theses/neural-encoding-by-bursts-of-spikes(56f4cf97-3887-4e89-bc0d-8db183ce9ce1).html.
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Neurons can respond to input by firing isolated action potentials or spikes. Sequences of spikes have been linked to the encoding of neuron input. However, many neurons also fire bursts; mechanistically distinct responses consisting of brief high-frequency spike firing. Bursts form separate response symbols but historically have not been thought to encode input. However, recent experimental evidence suggests that bursts can encode input in parallel with tonic spikes. The recognition of bursts as distinct encoding symbols raises important questions; these form the basic aims of this thesis: (1) What inputs do bursts encode? (2) Does burst structure provide extra information about different inputs. (3) Is burst coding robust against the presence of noise; an inherent property of all neural systems? (4) What mechanisms are responsible for burst input encoding? (5) How does burst coding manifest in in-vivo neurons. To answer these questions, bursting is studied using a combination of neuron models and in-vivo hippocampal neuron recordings. Models ranged from neuron-specific cell models to models belonging to three fundamentally different burst dynamic classes (unspecific to any neural region). These classes are defined using concepts from non-linear system theory. Together, analysing these model types with in-vivo recordings provides a specific and general analysis of burst encoding. For neuron-specific and unspecific models, a number of model types expressing different levels of biological realism are analysed. For the study of thalamic encoding, two models containing either a single simplified burst-generating current or multiple currents are used. For models simulating three burst dynamic classes, three further models of different biological complexity are used. The bursts generated by models and real neurons were analysed by assessing the input they encode using methods such as information theory, and reverse correlation. Modelled bursts were also analysed for their resilience to simulated neural noise. In all cases, inputs evoking bursts and tonic spikes were distinct. The structure of burst-evoking input depended on burst dynamic class rather than the biological complexity of models. Different n-spike bursts encoded different inputs that, if read by downstream cells, could discriminate complex input structure. In the thalamus, this n-spike burst code explains informative responses that were not due to tonic spikes. In-vivo hippocampal neurons and a pyramidal cell model both use the n-spike code to mark different LFP features. This n-spike burst may therefore be a general feature of bursting relevant to both model and in-vivo neurons. Bursts can also encode input corrupted by neural noise, often outperforming the encoding of single spikes. Both burst timing and internal structure are informative even when driven by strongly noise-corrupted input. Also, bursts induce input-dependent spike correlations that remain informative despite strong added noise. As a result, bursts endow their constituent spikes with extra information that would be lost if tonic spikes were considered the only informative responses.
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Dalvald, Momo. "Korrelerar startlereaktion med reaktionstid?" Thesis, University of Gävle, Department of Education and Psychology, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-321.
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Bilder av potentiella hot upptäcks snabbt och leder till en snabbare reaktionstid än bilder av icke-potentiella hot. Potentiella hot stjäl också fokus och kognitiva resurser, med en långsammare reaktionstid som följd. Rädsla, som kan mätas genom startlereflexen, leder till antingen ökad handlingsberedskap (snabbare reaktionstid) eller kognitiv distraktion (långsammare reaktionstid). Fem försöksdeltagare fick reagera på en visuell probe som lades ovanpå djurbilder, både potentiella hot och icke-potentiella hot i ett kombinerat reaktionstids- och startleprobeexperiment, där ljudstötar utdelades i hörlurar. Startlereaktion, hjärtfrekvens och reaktionstid mättes, varefter korrelationskoefficienter räknades ut. Resultatet visade på en svag negativ korrelation mellan reaktionstid och startlepotentiering på gruppnivå, men inga signifikanta samband påvisades på individnivå. Resultatet på gruppnivå kan bero på att de individuella resultaten tenderar samlas i kluster och därför skapar ett skensamband. Även en positiv korrelation mellan hjärtfrekvensförändring och startlereaktion påvisades, men ingen korrelation mellan hjärtfrekvens och reaktionstid.
Pictures of fear relevant animals are detected fast and lead to shorter reaction time, compared to pictures of fear irrelevant animals. Fear relevant animals also capture attention and steals focus, which leads to slower reaction time. Fear leads to either preparedness for action (faster reaction time) or cognitive distraction (slower reaction time). In a combined startle probe and reaction time experiment, five participants were requested to react to a visual probe, superimposed on pictures of animals, both relevant and irrelevant to fear. Startle probes were given as noise bursts in headphones. Startle reaction, heart rate and reaction time were measured. A negative correlation between reaction time and startle potentiation was found on group level, whereas no significant correlations were found on the individual level. However, the individual results tend to gather in clusters, which might give a significant result on group level even if there is none.
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Porto, Maria Angelica de Almeida [UNIFESP]. "Potencial evocado auditivo de tronco encefálico – tone burst e resposta auditiva de estado estável em lactentes." Universidade Federal de São Paulo (UNIFESP), 2009. http://repositorio.unifesp.br/handle/11600/9951.
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Introdução: A necessidade da realização de diagnóstico audiológico nas primeiras semanas ou meses de vida aumentou com a consolidação dos programas de triagem auditiva neonatal. As emissões otoacústicas (EOA) e o potencial evocado auditivo de tronco encefálico (PEATE) com estímulo clique são amplamente utilizados. Para que a intervenção precoce tenha sucesso, informações precisas quanto ao tipo, grau e configuração da perda auditiva tornam-se necessárias. A realização do PEATE com o estímulo tone burst (TB) e da pesquisa da resposta auditiva de estado estável (RAEE) vêm se mostrando de grande valia, já que tais testes fornecem informações específicas por freqüência, permitindo uma avaliação audiológica mais detalhada. Objetivo: Analisar a aplicabilidade clínica do PEATE TB e da RAEE em 2 kHz, em lactentes nascidos a termo e pré-termo. Método: A casuística foi composta por 17 lactentes pré-termo e 19 lactentes a termo, de ambos os gêneros. O estudo foi realizado na UNIFESP e os lactentes, em sono natural, foram submetidos ao PEATE TB e à RAEE na freqüência de 2000 Hz, utilizando-se o equipamento Smart EP da Intelligent Hearing Systems. Resultados: A comparação entre as respostas da orelha direita e esquerda não apresentou diferenças estatisticamente significantes, permitindo considerar a amostra como um todo. A comparação das respostas dos lactentes pré-termo e a termo não apresentou diferenças estatisticamente significantes, com exceção do tempo de duração da RAEE. As latências médias da onda V no PEATE TB foram de 7,9 ms a 80 dBnNA, 8,9 ms a 60 dBnNA, 9,9 ms a 40 dBnNA e 10,8 ms a 30 dBnNA. A resposta eletrofisiológica mínima obtida com o PEATE TB foi de 32,4 dBnNA (52,4 dBNPS), em média. A RAEE mínima obtida foi de 13,8 dBNA (26,4 dBNPS), em média. A duração média do PEATE TB foi de 21,1 min e da RAEE de 22 min. Conclusões: O PEATE TB e a RAEE têm aplicabilidade clínica na freqüência de 2 kHz em lactentes, não havendo diferenças entre indivíduos a termo e pré-termo.
Introduction: Audiological diagnosis in the first weeks or months of life has increased with the consolidation of newborn hearing screening programs. Otoacoustic emissions (OAE) and auditory brainstem response (ABR) with click stimuli are widely used for this purpose. For a successful early intervention, accurate information about type, degree, and configuration of hearing loss are necessary. ABR with tone burst stimuli (TB ABR) and auditory steady-state response (ASSR) exams have been of great value, since these tests provide specific frequency information, resulting in a more detailed hearing evaluation. Objective: Analyze the clinical applicability of TB ABR and ASSR at 2 kHz, in full-term and premature infants. Method: The study was conducted at UNIFESP. Subjects were consisted of 17 premature infants and 19 full-term infants, male and female. In natural sleep, they have undergone TB ABR and ASSR exams (Smart EP - Intelligent Hearing Systems), at 2000 Hz. Results: Right and left ears responses showed no statistically significant differences, therefore they were considered as a whole. Wave V mean latencies in TB ABR were 7.9 ms to 80 dBnHL, 8.9 ms to 60 dBnHL, 9.9 ms to 40 dBnHL and 10.8 ms to 30 dBnHL. Electrophysiological minimum response obtained with TB ABR was 32.4 dBnHL (52.4 dBSPL), on average. ASSR minimum response was 13.8 dBHL (26.4 dBSPL), on average. TB ABR and ASSR exams lasted 21.1 min and 22 min, respectively. Premature and full-term infants responses showed no statistically significant differences, except for ASSR duration. Conclusions: Both TB ABR and ASSR have clinical applicability at 2 kHz in infants, with no differences between premature and full-term individuals.
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BV UNIFESP: Teses e dissertações
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Madhavan, Radhika. "Role of spontaneous bursts in functional plasticity and spatiotemporal dynamics of dissociated cortical cultures." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/24756.
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Thesis (Ph.D.)--Biomedical Engineering, Georgia Institute of Technology, 2007.Committee Chair: Potter, Steve; Committee Member: Butera, Robert; Committee Member: DeWeerth, Stephen; Committee Member: Schumacher, Eric; Committee Member: Wenner, Pete.
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Sonkajärvi, E. (Eila). "The brain's electrical activity in deep anaesthesia:with special reference to EEG burst-suppression." Doctoral thesis, Oulun yliopisto, 2015. http://urn.fi/urn:isbn:9789526209722.
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Abstract Several anaesthetics are able to induce a burst-suppression (B-S) pattern in the electroencephalogram (EEG) during deep levels of anaesthesia. A burst-suppression pattern consists of alternating high amplitude bursts and periods of suppressed background activity. All monitors measuring the adequacy of anaesthesia recognize the EEG B-S as one criterion. A better understanding of EEG burst-suppression is important in understanding the mechanisms of anaesthesia. The aim of the study was to acquire a more comprehensive understanding of the function of neural pathways during deep anaesthesia. The thesis is comprised of four prospective clinical studies with EEG recordings from 64 patients, and of one experimental study of a porcine model of epilepsy with EEG registrations together with BOLD fMRI during isoflurane anaesthesia (II). In study I, somatosensory cortical evoked responses to median nerve stimulation were studied under sevoflurane anaesthesia at EEG B-S levels. In study III, The EEGs of three Parkinson`s patients were observed to describe the characteristics of B-S during propofol anaesthesia using scalp electrodes and depth electrodes in the subthalamic nucleus. In study IV, EEG topography was observed in 20 healthy children under anaesthesia mask induction with sevoflurane. Twenty male patients were randomized to either controlled hyperventilation or spontaneous breathing groups for anaesthesia mask induction with sevoflurane in study V. EEG alterations in relation to haemodynamic responses were examined in studies IV and V. Somatosensory information reached the cortex even during deep anaesthesia at EEG burst-suppression level. Further processing of these impulses in the cortex was suppressed. The EEG slow wave oscillations were synchronous over the entire cerebral cortex, while spindles and sharp waves were produced by the sensorimotor cortex. The development of focal epileptic activity could be detected as a BOLD signal increase, which preceded the EEG spike activity. The epileptogenic property of sevoflurane used at high concentrations especially during hyperventilation but also during spontaneous breathing together with heart rate increase, was confirmed in healthy children and male. Spike- and polyspike waveforms concentrated in a multifocal manner frontocentrallyTiivistelmä Useat anestesia-aineet pystyvät aiheuttamaan aivosähkökäyrän (EEG) purskevaimentuman syvän anestesian aikana. Purskevaimentuma koostuu EEG:n suuriamplitudisten purskeiden sekä vaimentuneen taustatoiminnan vaihtelusta. Kaikkien anestesian syvyyttä mittaavien valvontalaitteiden toiminta perustuu osaltaan EEG:n purskevaimentuman tunnistamiseen. Tämän ilmiön parempi tunteminen on tärkeää anestesiamekanismien ymmärtämiseksi. Tutkimuksen päämääränä oli saada kattavampi käsitys hermoratojen toiminnasta syvässä anestesiassa. Väitöskirjatyö koostuu neljästä prospektiivisesta yhteensä 64 potilaan EEG-rekisteröinnit sisältävästä tutkimuksesta sekä yhdestä kokeellisen epilepsiatutkimuksen koe-eläintyöstä, jossa porsailla käytettiin isofluraanianestesiassa sekä EEG-rekisteröintejä sekä että magneettikuvantamista (fMRI) samanaikaisesti (II). Ensimmäisessä osatyössä tutkittiin keskihermon stimulaation aiheuttamia somatosensorisia herätepotentiaaleja aivokuorella EEG:n purskevaimentumatasolla sevofluraanianestesian aikana. Kolmannessa osatyössä selvitettiin propofolianestesian aiheuttamaa EEG:n purskevaimentumaa kolmelta Parkinsonin tautia sairastavalta potilaalta käyttäen sekä pintaelektrodien että subtalamisen aivotumakkeen syväelektrodien rekisteröintejä. Neljännessä osatyössä tutkittiin EEG:n topografiaa 20:llä terveeellä lapsella indusoimalla anestesia sevofluraanilla. Kaksikymmentä miespotilasta nukutettiin sevofluraanilla ja heidät satunnaistettiin joko kontrolloidun hyperventilaation tai spontaanin hengityksen ryhmiin osatyössä V. EEG-muutoksia sekä niiden yhteyttä verenkiertovasteisiin selviteltiin molemmissa osatöissä IV ja V. Omasta kehosta tuleviin tuntoärsykkeisiin liittyvä somatosensorinen informaatio saavutti aivokuoren myös syvässä EEG:n purskevaimentumatasoisessa anestesiassa. Impulssien jatkokäsittely aivokuorella oli kuitenkin estynyt. EEG:n hidasaaltotoiminta oli synkronista koko aivokuoren alueella, sen sijaan unisukkulat ja terävät aallot paikantuivat sensorimotoriselle aivokuorelle. Paikallisen epileptisen toiminnan kehittyminen oli mahdollista havaita jo ennen piikikkäiden EEG:n aaltomuotojen ilmaantumista edeltävänä BOLD-ilmiöön liittyvänä aivoverenkierron lisääntymisenä. Sevofluraanin epileptogeenisyys varmistui erityisesti hyperventilaation, mutta myös spontaanin hengityksen yhteydessä ja näihin liittyi sykkeen nousu sekä terveillä lapsilla että miehillä. Piikkejä ja monipiikkejä käsittävien aaltomuotojen keskittymistä esiintyi otsalohkon keskialueilla
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Käse, Mirjam [Verfasser], and Andreas J. [Akademischer Betreuer] Fallgatter. "Transkranielle Theta-Burst-Behandlung depressiver Patienten : Untersuchung der Wirkung auf evozierte Potentiale in einem Oddball Paradigma / Mirjam Käse. Betreuer: Andreas J. Fallgatter." Würzburg : Universitätsbibliothek der Universität Würzburg, 2012. http://d-nb.info/1019944838/34.
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Silva, Bárbara Cristiane Sordi. "O uso do mascaramento no potencial evocado auditivo de tronco encefálico com estímulo tone burst por condução aérea em indivíduos com perda auditiva unilateral." Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/25/25143/tde-12062018-190631/.
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A utilização do mascaramento contralateral durante a pesquisa do potencial evocado auditivo de tronco encefálico é uma temática bastante discutida, visto a inexistência de um consenso na literatura acerca de sua necessidade. O objetivo deste estudo foi verificar a necessidade do uso do mascaramento contralateral no potencial evocado auditivo de tronco encefálico com estímulo tone burst apresentado com fone de inserção 3A e propor a aplicabilidade do ruído mascarador white noise na perda auditiva sensorioneural unilateral de graus severo ou profundo. Foram avaliados 15 indivíduos, de ambos os sexos, com o diagnóstico audiológico prévio de perda auditiva sensorioneural unilateral de graus severo ou profundo, com idades entre 2 a 40 anos. Para tanto, foi pesquisada a resposta neural definida pela presença da onda V na orelha com perda auditiva, nas frequências de 500, 1000, 2000 e 4000 Hz. Nos casos em que houve o registro, a pesquisa foi repetida com mascaramento white noise na orelha contralateral. Os registros foram analisados por dois juízes experientes em eletrofisiologia, a fim de verificar a concordância entre as análises. O Coeficiente Kappa (1,00) apresentou força de concordância quase perfeita e o de Correlação Intraclasse (1,00) foi excelente, entre as duas avaliadoras, em todas as análises. Como resultado, foi observada a audição cruzada, ao menos uma vez, em todas as frequências analisadas. Os níveis de mascaramento contralateral mínimos necessários para eliminar a participação da orelha não testada variaram de 10 a 20 dBnNA acima do limiar eletrofisiológico da orelha sem perda auditiva. Não foi possível realizar a análise para a frequência de 500 Hz devido à presença de artefato e ruído elétricos. Conclui-se que o uso do mascaramento contralateral no potencial evocado auditivo de tronco encefálico com estímulo tone burst apresentado com fone de inserção 3A é necessário nas frequências de 1000, 2000 e 4000 Hz em indivíduos com perda auditiva sensorioneural unilateral de graus severo ou profundo, nas intensidades de 15, 20 e 10 dB acima dos limiares eletrofisiológicos, respectivamente.The use of contralateral masking on the investigation of auditory brainstem response is a topic widely discussed, however there is no consensus in literature about its necessity. The aim of this study was to verify the need of using masking in auditory brainstem response with tone burst stimulus presented with 3A insert earphones and to propose the applicability of white noise masking in severe or profound unilateral sensorineural hearing loss. Fifteen individuals of both genders with previous audiological diagnosis of severe or profound unilateral sensorineural hearing loss, aged between 2 to 40 years, were evaluated. For this, the neural response, which is defined by the presence of the V wave in the ear with hearing loss, was investigated in frequencies of 500, 1000, 2000 and 4000 Hz. In cases where there was a record, the search was repeated using white noise masking in the contralateral ear. The records were analyzed by two judges experienced in electrophysiology, in order to verify the concordance between the analyses. The Kappa coefficient (1.00) had almost perfect agreement strength and the Intraclass Correlation (1.00) was excellent between the two evaluators in all analyses. As a result, cross-audition was observed at least once in all analyzed frequencies. The minimum contralateral masking levels required to eliminate the untested ear involvement varied from 10 to 20 dBnNA above the electrophysiological threshold of the ear without hearing loss. It was not possible to perform the analysis for the frequency of 500 Hz due to the presence of electrical artifact and noise. It is concluded that the use of contralateral masking in the auditory brainstem response with tone burst stimulus presented with 3A insert earphone is necessary in frequencies of 1000, 2000 and 4000 Hz in individuals with severe or profound unilateral sensorineural hearing loss in intensities of 15, 20 and 10 dB above the electrophysiological thresholds, respectively.
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Ortiz, Cantin. "Study of neural correlates of attention in mice with spectro-spatio-temporal approaches." Thesis, KTH, Skolan för datavetenskap och kommunikation (CSC), 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-220948.
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While signatures of attention can be observed in widespread areas within and outside of cortex, the control of attention is thought to be regulated by higher cognitive brain areas, such as the prefrontal cortex. In their recent study on mice Kim et al. could show that successful allocation of attention is characterized by increased spiking of a specific type of inhibitory interneurons, the parvalbumin neurons, and higher oscillatory activity in the gamma band in the local prefrontal network. It was recently demonstrated that encoding of working memory in prefrontal areas is linked to bursts of gamma oscillations, a discontinuous network process characterized by short periods of intense power in the gamma band. The relationship between attention and working memory is unclear, and it is possible that these two cognitive processes share encoding principles. To address this gap, the electrophysiological data collected in the Carlén Lab have been analyzed with advanced spatio-temporal approaches. In particular, we have analyzed bursting gamma activity in medial prefrontal cortex during attentional processing and investigated the similarities to gamma bursting observed during working memory. Gamma-band bursts during attention were reliably detected with several methods. We have characterized several features of the bursts, including the occurrence, duration and amplitude. The neuronal firing rates during and outside of bursts have also been computed. We investigated the correlation between different criteria characterizing the gamma burst and successful vs failed allocation of attention. Control data were generated to discuss the obtained results. The aim of the study was to explore the hypothesis that the medial prefrontal cortex encodes attention trough gamma bursts, which could reveal some similarities and differences in coding of central cognitive processes. No clear difference was found in the characterization between successful and failed allocation of attention. In addition, results were very similar in control set and original data. No underlying mechanism could be identified from this analysis. Therefore, as the bursts occurring in the gamma band in the prefrontal cortex (PFC) were not discriminative with respect to the different tested conditions, they do not seem to encode information related to attention.Även fast flera olika hjärnområdens aktivitet kan korreleras med uppmärksamhet, anses kontrollen av uppmärksamhet regleras av högre kognitiva hjärnområden, såsom främre hjärnbarken. I en nyligen publicerad artikel studerade Kim et al. hjärnaktiviteten hos möss och kunde visa att en framgångsrik uppmärksamhet kännetecknas av en ökad aktivitet av en specifik typ av inhiberande nervceller, parvalbumin celler, och högre oscillerande aktivitet i gammafrekvens i främre hjärnbarkens lokala nätverk. Det har nyligen visats att kodning av arbetsminne i främre hjärnbarken är kopplat till utbrott av gamma-oscillationer, en diskontinuerlig nätverksprocess som kännetecknas av korta perioder av intensiva oscillationer av det lokala nätverket i gammafrekvens . Relationen mellan uppmärksamhet och arbetsminne är oklar, och det är möjligt att dessa två kognitiva processer delar kodningsprinciper. För att minska detta gap av kunskap har den elektrofysiologiska datan som samlats in i Carlén Lab analyserats med avancerade spatio-temporala tillvägagångssätt. I synnerhet har vi analyserat utbrott i gammaaktivitet i främre hjärnbarken under uppmärksamhet och undersökt likheterna med gamma- utbrott observerade under arbetsminne. Gamma-bandutbrott under uppmärksamhet påvisades på ett tillförlitligt sätt med flera metoder. Vi har karaktäriserat flera funktioner hos utbrotten, inklusive förekomsten, varaktigheten och amplituden. De enskilda cellernas aktivitet undersöktes även under och utanför utprotten av gamma-oscillationer. Vi undersökte sambandet mellan de olika kriterier som karakteriserar gamma-utbrott under framgångsrik mot misslyckad allokering av uppmärksamhet. Kontrolldata genererades för att diskutera de erhållna resultaten. Syftet med studien var att utforska hypotesen att den främre hjärnbarken kodar uppmärksamhet genom gamma-utbrott, vilket kan avslöja vissa likheter och skillnader i kodning av centrala kognitiva processer. Ingen klar skillnad hittades i karaktäriseringen mellan framgångsrik och misslyckad allokering av uppmärksamhet. Dessutom var resultaten mycket likartade i kontrolluppsättningen och den ursprungliga datan. Ingen underliggande mekanism kunde identifieras ur denna analys. Eftersom de utbrott som uppstod i gamma-bandet i främre hjärnbarken inte var unika med hänsyn till de olika testade förhållandena, tycks de därför inte koda information relaterad till uppmärksamhet.
Books on the topic "Burst potential"
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Hagyard, M. J. Nonpotential magnetic fields at sites of gamma-ray flares. [Huntsville, Ala.?: Marshall Space Flight Center, 1988.
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Burst of Conscious Light: Near-Death Experiences, the Shroud of Turin, and the Limitless Potential of Humanity. Inner Traditions International, Limited, 2020.
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Silverman, Andrew. Burst of Conscious Light: Near-Death Experiences, the Shroud of Turin, and the Limitless Potential of Humanity. Inner Traditions International, Limited, 2020.
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Hunter, Jennifer M., and Thomas Fuchs-Buder. Neuromuscular blockade and reversal. Edited by Michel M. R. F. Struys. Oxford University Press, 2017. http://dx.doi.org/10.1093/med/9780199642045.003.0016.
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Over the past 70 years since the introduction of d-tubocurarine, the search for an ideal neuromuscular blocking agent has led to the development of the depolarizing drug, succinylcholine (suxamethonium), with its rapid onset of action and plasma metabolism, and a series of non-depolarizing agents of which there are two groups: benzylisoquinoliniums (e.g. atracurium, cisatracurium and mivacurium) and aminosteroidal agents (e.g. pancuronium, vecuronium and rocuronium). The need to monitor neuromuscular block perioperatively to ensure the appropriate dose of any neuromuscular blocking drug is given has led to the development of several nerve stimulation techniques. Particularly useful clinically are the train-of-four twitch response, double-burst stimulation, and the post-tetanic count. Their benefits and limitations are considered in this chapter. The most suitable equipment to monitor neuromuscular block and the appropriate anatomical sites for stimulation are discussed. To prevent residual block with its pathophysiological consequences such as upper airway and pharyngeal dysfunction and potential respiratory failure at the end of surgery, antagonizing agents are used. These are of two types: anticholinesterases such as neostigmine and edrophonium, and the γ-cyclodextrin, sugammadex. The pharmacodynamics and pharmacokinetics of neuromuscular blocking drugs and their antagonists are altered by the extremes of age, obesity, and several disease states including renal and hepatic failure, neuromuscular disorders, and critical illness. The altered response to all these drugs in these pathologies, which is related to their metabolism and excretion, is considered in detail, together with their other side-effects including the particular disadvantages to the use of succinylcholine.
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Government, U. S., National Aeronautics and Space Administration (NASA), World Spaceflight News (WSN), and National Science and Technology Council. National Space Weather Action Plan and Strategy: Potential Effects - Power Outages, Infrastructure, Communication, Mitigation Plans, Forecasting, Induced Geo-Electric Fields, Solar Radio Bursts. Independently Published, 2017.
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Beninger, Richard J. Neuroanatomy and dopamine systems. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198824091.003.0011.
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Neuroanatomy and dopamine systems explains how sensory signals ascend the central nervous system via a series of nuclei; axons detecting specific elements converge onto higher-order neurons that respond to particular stimulus features. Assemblies of feature-detection cells in the cerebral cortex detect complex stimuli such as faces. These cell assemblies project to motor nuclei of the dorsal and ventral striatum where they terminate on dendritic spines of efferent medium spiny neurons. Dopaminergic projections from ventral mesencephalic nuclei terminate on the same spines. Individual corticostriatal afferents contact relatively few medium spiny neurons and individual dopaminergic neurons contact a far larger number. Stimuli activate specific subsets of corticostriatal synapses. Synaptic activity that is closely followed by a rewarding stimulus, that produces a burst of action potentials in dopaminergic neurons, is modified so that those specific corticostriatal synapses acquire an increased ability to elicit approach and other responses in the future, i.e., incentive learning.
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Brown, Stewart J., Peter Nockles, and James Pereiro. Introduction. Edited by Stewart J. Brown, Peter Nockles, and James Pereiro. Oxford University Press, 2017. http://dx.doi.org/10.1093/oxfordhb/9780199580187.013.50.
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In the wake of an era of political and social turmoil, the Oxford Movement represented an effort to recover the Catholic and apostolic patrimony of the Church of England. It had its precursors and background context, but burst forth in 1833 as a potentially disruptive force, challenging contemporaries and provoking opposition. Although the personality and genius of John Henry Newman lay at its heart, the Movement proved greater and more enduring than Newman’s personal Anglican history and took on new life after his departure for Rome in 1845. As the Movement moved away from its Oxford origins to the parishes and wider world, it became increasingly problematic, especially in the context of the rise of Ritualism, as to who could be considered its genuine descendants. Yet the Movement also exercised a profound influence, developing many variations and permutations, and its legacy continues to inform Church life.
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Swanepoel, R., and J. T. Paweska. Crimean-Congo haemorrhagic fever. Oxford University Press, 2011. http://dx.doi.org/10.1093/med/9780198570028.003.0033.
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Crimean-Congo haemorrhagic fever (CCHF) is an acute disease of humans, caused by a tick-borne virus which is widely distributed in eastern Europe, Asia and Africa. Cattle, sheep and small mammals such as hares undergo inapparent or mild infection with transient viraemia, and serve as hosts from which the tick vectors of the virus can acquire infection. Despite serological evidence that there is widespread infection of livestock in nature, infection of humans is relatively uncommon. Humans acquire infection from tick bite, or from contact with infected blood or other tissues of livestock or human patients, and the disease is characterized by febrile illness with headache, malaise, myalgia, and a petechial rash, frequently followed by a haemorrhagic state with necrotic hepatitis. The mortality rate is variable but averages about approximately 30 per cent. Inactivated vaccine prepared from infected mouse brain was used for the protection of humans in eastern Europe and the former Soviet Union in the past, but the development of a modern vaccine is inhibited by limited potential demand. The voluminous literature on the disease has been the subject of several reviews from which the information presented here is drawn, except where indicated otherwise (Chumakov 1974; Hoogstraal 1979; 1981; Watts et al. 1989; Swanepoel 1994; 1995; Swanepoel and Burt, 2004; Burt and Swanepoel, 2005; Whitehouse 2004; Ergunol and Whitehouse 2007; Ergunol 2008).
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Rees, Martin J. Global Catastrophic Risks. Edited by Nick Bostrom and Milan M. Cirkovic. Oxford University Press, 2008. http://dx.doi.org/10.1093/oso/9780198570509.001.0001.
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A global catastrophic risk is one with the potential to wreak death and destruction on a global scale. In human history, wars and plagues have done so on more than one occasion, and misguided ideologies and totalitarian regimes have darkened an entire era or a region. Advances in technology are adding dangers of a new kind. It could happen again. In Global Catastrophic Risks 25 leading experts look at the gravest risks facing humanity in the 21st century, including asteroid impacts, gamma-ray bursts, Earth-based natural catastrophes, nuclear war, terrorism, global warming, biological weapons, totalitarianism, advanced nanotechnology, general artificial intelligence, and social collapse. The book also addresses over-arching issues - policy responses and methods for predicting and managing catastrophes. This is invaluable reading for anyone interested in the big issues of our time; for students focusing on science, society, technology, and public policy; and for academics, policy-makers, and professionals working in these acutely important fields.
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Verschuur, Gerrit L. Impact! Oxford University Press, 1996. http://dx.doi.org/10.1093/oso/9780195101058.001.0001.
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Most scientists now agree that some sixty-five million years ago, an immense comet slammed into the Yucatan, detonating a blast twenty million times more powerful than the largest hydrogen bomb, punching a hole ten miles deep in the earth. Trillions of tons of rock were vaporized and launched into the atmosphere. For a thousand miles in all directions, vegetation burst into flames. There were tremendous blast waves, searing winds, showers of molten matter from the sky, earthquakes, and a terrible darkness that cut out sunlight for a year, enveloping the planet in freezing cold. Thousands of species of plants and animals were obliterated, including the dinosaurs, some of which may have become extinct in a matter of hours. In Impact, Gerrit L. Verschuur offers an eye-opening look at such catastrophic collisions with our planet. Perhaps more important, he paints an unsettling portrait of the possibility of new collisions with earth, exploring potential threats to our planet and describing what scientists are doing right now to prepare for this awful possibility. Every day something from space hits our planet, Verschuur reveals. In fact, about 10,000 tons of space debris fall to earth every year, mostly in meteoric form. The author recounts spectacular recent sightings, such as over Allende, Mexico, in 1969, when a fireball showered the region with four tons of fragments, and the twenty-six pound meteor that went through the trunk of a red Chevy Malibu in Peekskill, New York, in 1992 (the meteor was subsequently sold for $69,000 and the car itself fetched $10,000). But meteors are not the greatest threat to life on earth, the author points out. The major threats are asteroids and comets. The reader discovers that astronomers have located some 350 NEAs ("Near Earth Asteroids"), objects whose orbits cross the orbit of the earth, the largest of which are 1627 Ivar (6 kilometers wide) and 1580 Betula (8 kilometers). Indeed, we learn that in 1989, a bus-sized asteroid called Asclepius missed our planet by 650,000 kilometers (a mere six hours), and that in 1994 a sixty-foot object passed within 180,000 kilometers, half the distance to the moon. Comets, of course, are even more deadly. Verschuur provides a gripping description of the small comet that exploded in the atmosphere above the Tunguska River valley in Siberia, in 1908, in a blinding flash visible for several thousand miles (every tree within sixty miles of ground zero was flattened). He discusses Comet Swift-Tuttle--"the most dangerous object in the solar system"--a comet far larger than the one that killed off the dinosaurs, due to pass through earth's orbit in the year 2126. And he recounts the collision of Comet Shoemaker-Levy 9 with Jupiter in 1994, as some twenty cometary fragments struck the giant planet over the course of several days, casting titanic plumes out into space (when Fragment G hit, it outshone the planet on the infrared band, and left a dark area at the impact site larger than the Great Red Spot). In addition, the author describes the efforts of Spacewatch and other groups to locate NEAs, and evaluates the idea that comet and asteroid impacts have been an underrated factor in the evolution of life on earth. Astronomer Herbert Howe observed in 1897: "While there are not definite data to reason from, it is believed that an encounter with the nucleus of one of the largest comets is not to be desired." As Verschuur shows in Impact, we now have substantial data with which to support Howe's tongue-in-cheek remark. Whether discussing monumental tsunamis or the innumerable comets in the Solar System, this book will enthrall anyone curious about outer space, remarkable natural phenomenon, or the future of the planet earth.
Book chapters on the topic "Burst potential"
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Whyatt, J. K., T. J. Williams, and M. P. Board. "Examination of the support potential of cemented fills for rock burst control." In Innovations in Mining Backfill Technology, 209–15. London: CRC Press, 2021. http://dx.doi.org/10.1201/9781003211488-25.
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Dar, Mohd Akbar, Prince Ahad, Mubashir H. Masoodi, Showkat Rasool Mir, and Seema Akbar. "Lady’s Purse (Capsella bursa-pastoris L.): Current Perspective on Its Ethnopharmacological, Therapeutic Potential, and Phytochemistry." In Edible Plants in Health and Diseases, 425–55. Singapore: Springer Singapore, 2022. http://dx.doi.org/10.1007/978-981-16-4959-2_14.
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Cutsuridis, Vassilis. "Action Potential Bursts Modulate the NMDA-R Mediated Spike Timing Dependent Plasticity in a Biophysical Model." In Artificial Neural Networks – ICANN 2010, 107–16. Berlin, Heidelberg: Springer Berlin Heidelberg, 2010. http://dx.doi.org/10.1007/978-3-642-15819-3_15.
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Neto, Arnaldo Fim, Julia Baldi De Luccas, Bruno Leonardo Bianquenti, Tiago Paggi Almeida, Maria Sheila Rocha, Takashi Yoneyama, Fabio Luiz Franceschi Godinho, and Diogo Coutinho Soriano. "Estimation of Beta Burst Durations from Subthalamic Nucleus Local Field Potentials in Parkinson’s Disease Through Hilbert and Continuous Wavelets Transforms." In IFMBE Proceedings, 85–90. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-30648-9_12.
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Khanna, Omaditya, Geoffrey P. Stricsek, and James S. Harrop. "Thoracolumbar Burst Fractures." In Spinal Neurosurgery, 123–32. Oxford University Press, 2018. http://dx.doi.org/10.1093/med/9780190887773.003.0013.
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Ten to twenty percent of all thoracolumbar spine fractures are burst fractures. Burst fractures are typically a result of an axial-loading mechanism, such as from jumping or a fall from height. In this chapter, the authors provide an overview of the different classification systems for thoracolumbar fractures, including the Arbeitsgemeinschaft für Osteosynthesefragen (AO) classification system and Thoracolumbar Injury Classification and Severity (TLICS) score. The various treatment options, both surgical and nonsurgical, are discussed, including criteria for when surgical intervention is warranted. The authors discuss the various surgical approaches for treatment of these fractures and their relative efficacies and outcomes. Finally, the authors review the evidence, outcomes, and potential complications of the various treatment options in order to aid the surgeon in their decision-making when these fractures are encountered in their practice.
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Vlachos, Kyriakos. "Optical Burst Switching." In Encyclopedia of Internet Technologies and Applications, 375–82. IGI Global, 2008. http://dx.doi.org/10.4018/978-1-59140-993-9.ch053.
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Switching in core optical networks is currently being performed using high-speed electronic or all-optical circuit switches. Switching with high-speed electronics requires optical-to-electronic (O/E) conversion of the data stream, making the switch a potential bottleneck of the network: any effort (including parallelization) for electronics to approach the optical speeds seems to be already reaching its practical limits. Furthermore, the store-and-forward approach of packet-switching does not seem suitable for all-optical implementation due to the lack of practical optical Random-Access-Memories to buffer and resolve contentions. Circuit switching on the other hand, involves a pre-transmission delay for call setup and requires the aggregation of microflows into circuits, sacrificing the granularity and the control over individual flows, and is inefficient for bursty traffic. Optical burst switching (OBS) has been proposed by Qiao, C., ?[1] to combine the advantages of both packet and circuit switching and is considered a promising technology for the next generation optical internet.
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Martin Usrey, W., and S. Murray Sherman. "Intrinsic Membrane Properties." In Exploring Thalamocortical Interactions, 25–42. Oxford University Press, 2021. http://dx.doi.org/10.1093/med/9780197503874.003.0003.
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This chapter summarizes basic membrane properties of thalamic and cortical neurons, starting with a consideration of current flow within these cells based on modeling of the somadendritic tree as a series of branched cables with leaky membranes. This assumes passive membrane properties and provides some useful first approximations of neuronal functioning, but these neurons have a number of active ionic conductances that are also described and play important roles in neuronal activity. These involve various ligand-, voltage-, and time-dependent ion channels. The ubiquitous voltage- and time-dependent Na+ channel underlying the action potential is the best known example of such channels, and these are found virtually in all thalamic and cortical neurons. Another important voltage- and time-dependent channel is the T-type Ca2+ channel, and thalamic neurons are relatively unique in having these channels distributed so densely in their somadendritic membranes that, when evoked, they can produce all-or-none Ca2+ spikes that propagate through the soma and dendrites; these spikes, in turn, evoke a burst of conventional action potentials. Some cortical cells show similar burst firing based on a different voltage- and time-dependent Ca2+ channel. Details of these processes and speculation of their functional significance are discussed.
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Hu, Feng, and Haibo Wei. "An Empirical Study of Green Finance Research Through Bibliometrics." In Green Finance for Sustainable Global Growth, 84–106. IGI Global, 2019. http://dx.doi.org/10.4018/978-1-5225-7808-6.ch004.
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Green finance issues have triggered the increasing research enthusiasm of researchers. With the rapid growing of publications related to green finance, it is difficult for readers to deeply understand the intellectual structure, research hotspots, and trends. In addition, the dynamic nature of a research front poses challenges for the scientists, research policymakers, and many others to keep up with the rapid advances of the state of the art in science. Therefore, the authors conducted a bibliometric analysis from the Web of Science over the period of 1998–2017. Co-word analysis and co-citation analysis are employed to explore institution distribution, journal co-citation analysis, author co-citation analysis, document co-citation analysis, and keyword co-word analysis, particularly in high frequency items, intellectual turning points, burst points, and emerging trends. The results can be useful for institutions and researchers worldwide to understand the panorama of green finance research, find the potential research gaps, and focus on the future research trends.
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Hudec, R., and V. Simon. "GRB POTENTIAL OF ESA GAIA." In Gamma-ray Bursts: 15 Years of GRB Afterglows, 639–44. EDP Sciences, 2020. http://dx.doi.org/10.1051/978-2-7598-1002-4-103.
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Hudec, R., and V. Simon. "GRB POTENTIAL OF ESA GAIA." In Gamma-ray Bursts: 15 Years of GRB Afterglows, 639–44. EDP Sciences, 2020. http://dx.doi.org/10.1051/978-2-7598-1002-4.c103.
Full textConference papers on the topic "Burst potential"
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Blakely, C., J. Yu, and H. Zhang. "Preliminary Investigation of Fuel Rod Burst Potential Under LBLOCA with Burnup Extension." In Tranactions - 2019 Winter Meeting. AMNS, 2019. http://dx.doi.org/10.13182/t30864.
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Stonehouse, Mark, Tony Paulin, Charles Becht, and Charles Becht. "Burst Tests of B16.9 Welded Tees." In ASME 2014 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/pvp2014-28265.
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This paper presents the results of a small sample of ASME B16.9 welding tee burst tests. The intent of this study was to make a comparison between what is commonly accepted in industry as a B16.9 welding tee to the burst test requirements of B16.9 paragraph 9. The tests conducted show that the current fabrication techniques and some accepted criteria for B16.9 certification can produce thin sections in the tee which do not meet the required burst test pressures. The test descriptions and results are presented as well as recommendations for future study and potential modifications to the ASME B16.9 standard to address the concerns.
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Baschuk, J. J., Alan West, and B. W. Leitch. "Small Scale Burst Facility: Experimental Investigation of Fluid-Structure Interaction in a PHWR." In ASME 2013 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/pvp2013-97422.
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The Pressurized Heavy Water Reactor (PHWR) is based on natural uranium fuel and heavy water moderator. A unique feature of the PHWR is the horizontal fuel channel that allows for on-line re-fuelling and fuel management. A fuel channel consists of two concentric tubes, each approximately 6 meters long. The inner tube, known as the pressure tube, contains the uranium fuel bundles and the pressurized (∼10 MPa) primary coolant. The outer tube, known as the calandria tube, separates the heavy water moderator (∼70°C) from the pressure tube (∼300°C). A potential accident scenario is the bursting of a fuel channel. The escaping hot fluid generates a pressure wave in the moderator, which would interact with the adjacent pressure/calandria tube assemblies and the outer containment calandria vessel, potentially damaging components within the reactor core. To improve the understanding of channel bursts and associated fluid structure interaction, a 1:6 scale reactor vessel test facility (Small Scale Burst Facility) was constructed at the Atomic Energy of Canada Ltd, Chalk River Laboratories. The test facility allows for the measurement of transient pressures, the development and collapse of the steam bubble created by the burst tube, and resultant response of the neighboring tubes and scaled calandria vessel. A single bursting tube, or a single tube bursting within an array of neighboring tubes, can be tested. The results from recent tests are presented, which include a three-dimensional map of the pressure pulse from a single, bursting tube. Future work will include 3-D mapping of near wall bursts and modeling the experiments using Arbitary Lagrangian Eulerian methods in the finite element program, LS-DYNA. This work is part of the development of a next generation modeling tool for fuel channel phenomena.
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Hamada, Seiichi, Yasuki Ogawa, Hideo Iida, Tomoki Kuroiwa, Masahiko Kuroki, and Manabu Hayakawa. "Application of Potential Drop Technique to the Inspection of Welded Boiler Pressure Parts." In ASME/JSME 2004 Pressure Vessels and Piping Conference. ASMEDC, 2004. http://dx.doi.org/10.1115/pvp2004-2697.
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In this paper, a practical method using the electrical potential drop technique was discussed to evaluate the creep damage accumulated in the welded power piping such as main steam pipe and hot reheat pipe. Round robin experimental measurements conducted by the authors et al. as academic activities in the Japanese Society for Non-destructive Inspection showed that the potential drop technique is effective for the application to the inspection of welded boiler pressure parts. The authors have conducted additional experimental and numerical studies for verification focusing on the application of the pulsed direct current potential drop technique. The authors have proposed technical requirements on the potential drop technique for the application to the inspection of welded power piping to be implemented in JSME Codes for Thermal Power Generation Facilities (2003 Edition) as a non-mandatory appendix JA. And the practical on-line measurement in the high temperature and high pressure burst test using the repair-welded power piping has been conducted. In this burst test, Tokyo Electric Power Company has tried to monitor the creep damage accumulated in the seam-welded area using the commercialized tool based on pulsed direct current potential drop technique.
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Fujisawa, T., K. Nishio, T. Nagase, M. Hashisaka, K. Muraki, Jisoon Ihm, and Hyeonsik Cheong. "Time Resolved Potential Measurement At Quantum Point Contacts Under Irradiation Of Surface Acoustic Burst Wave." In PHYSICS OF SEMICONDUCTORS: 30th International Conference on the Physics of Semiconductors. AIP, 2011. http://dx.doi.org/10.1063/1.3666357.
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Brechan, B., S. Sangesland, and S. Dale. "Improved Model for Tubular Burst." In ASME 2019 38th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/omae2019-95819.
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Abstract Modern casing design can reduce significant amounts of CO2 and considerable cost per well [1]. Collapse design was modernized by ISO/API Technical committee 67, Sub Committee 5, Work Group 2b (ISO/API TC67/SC5/WG2b). Modernization of burst design has so far not had the same focus and only minor changes have been made. A new burst design model has been developed to add to the collapse prediction for a complete environmental and cost effective well design tool. It is based on the theories of Lubinski [2] (1975) and presents designs using “exact von Mises ellipsis” together with the Klever and Stewart ductile rupture model [3]. This paper presents the model developed for burst design and the improvement compared to current industry practice. Inspired by the current most accurate collapse prediction model [4], the modified burst model (prototype) is the first to consider actual wall thickness to predict a more accurate internal yield of OCTG (Oil Country Tubular Goods). Investigations show that the standard 12.5% wall thickness reduction for manufacturing tolerances may be obsolete. ISO 10400 offers physical measurements and statistics of tubular properties. Following the principals by WG2b applied with the Klever & Tamano collapse prediction, there is a set of data to be used for a specific batch of tubulars or they are deducted through large quantum of measurements; ensemble Probability Density Function (PDF). The value proposed as “ensemble PDF” for wall thickness is based on more than 10 000 measurements of tubulars from 11 vendors distributed over Electrical Weld (EW) and quenched and tempered (Q&T) qualities of miscellaneous sizes and grades. The batch specific value proposed is based on more modest numbers of specimens from 4 sources but offers “minimum measured wall thickness” for all the samples. Adding to the confidence of the final design is the automated ductile burst calculation, which is one of the latest contributions to burst modeling in the industry [4] [5] [6]. It is a useful aid for the design engineer to know the potential failure mode and the limit before loss of integrity. However, burst is limited to yield because exceeding this limit may lead to loss of the pipe’s effective diameter and eventually loss of integrity. Therefore, the ductile burst prediction is proposed as a visual aid only.
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Emblom, William J., Ayotunde Olayinka, Scott W. Wagner, Thomas C. Pesacreta, and Muhammad A. Wahab. "Multiscale Sheet Metal Hydroforming and Burst Pressure Estimates." In ASME 2017 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/imece2017-70347.
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Micro- and multiscale material properties must be considered when manufacturing miniature devices, especially when considering utilizing multiscale sheet metal hydroforming processes. One of the critical considerations during the design process is the burst pressure for the sheet metal which is a limiting factor for potential hydroforming operations. In order to simplify determining tearing or rupture conditions, it is sometimes desired to use analytical methods for estimating material properties, including burst pressures, which occur shortly after material instability. Many researchers have developed approximate methods for predicting deformation during open die hydroforming based upon analytical approaches for biaxial conditions for circular and elliptical dies. Additionally, extracting material properties of sheet metal under biaxial conditions such as bulge hydroforming more closely matches forming conditions that the sheet metal will undergo for actual parts. The objective of the current research was to evaluate the analytically developed models’ ability to predict burst conditions and compare those burst results to those obtained from finite element models and experimentation. Stainless steel (annealed 0.2-mm thick AISI 304) was hydroformed in a circular open die with diameter of 11mm. Elliptical dies were also evaluated that had minor diameters of 11mm and aspect ratios down to 0.5. It was found that using the analytical method developed specifically for circular dies was a good predictor for the burst pressure while the more general analytical method for elliptical dies did not agree with either results from finite element analysis or experimental results.
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Chiodo, Mario S. G., and Claudio Ruggieri. "Burst Pressure Predictions of Corroded Pipelines With Long Defects: Failure Criteria and Validation." In ASME 2009 Pressure Vessels and Piping Conference. ASMEDC, 2009. http://dx.doi.org/10.1115/pvp2009-77179.
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This study examines the applicability of a stress-based criterion based upon plastic instability analysis to predict the failure pressure of corroded pipelines with axial defects. A central focus is to gain additional insight into effects of defect geometry and material properties on the attainment of a local limit load to support the development of stress-based burst strength criteria. A verification study conducted on burst testing of large-diameter pipe specimens with different defect length shows the effectiveness of a stress-based criterion using local ligament instability in burst pressure predictions, even though the adopted burst criterion exhibits a potential dependence on defect geometry and possibly on material’s strain hardening capacity. Overall, the results presented here suggests that use of stress-based criteria based upon plastic instability analysis of the defect ligament is a valid engineering tool for integrity assessments of pipelines with axial corroded defects.
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Dong, Liang, Huipeng Qu, Min Wang, Jun Lin, and Gunnan Gao. "L band solar radio burst events — A potential interference for navigation signal and pre-alarm method research." In 2014 XXXIth URSI General Assembly and Scientific Symposium (URSI GASS). IEEE, 2014. http://dx.doi.org/10.1109/ursigass.2014.6930006.
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Bajwa, Christopher S., Earl P. Easton, Darrell S. Dunn, and Robert E. Shewmaker. "Potential Effects of Recent Road Transportation Accidents on Radioactive Material Shipments." In ASME 2008 Pressure Vessels and Piping Conference. ASMEDC, 2008. http://dx.doi.org/10.1115/pvp2008-61568.
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In 2007, two severe transportation accidents, involving primarily long-haul tractor trailers, occurred in the State of California. In the first, which occurred in Oakland in the “MacArthur Maze” section of Interstate 580, a tractor trailer carrying gasoline impacted an overpass support column and burst into flames. The subsequent fire, which burned for over 2 hours, led to the collapse of the overpass onto the remains of the tractor trailer, due to the loss of strength in the steel exposed to the fire. The second incident was a chain-reaction accident involving several tractor trailers in the I-5 “Newhall Pass” truck bypass tunnel in Santa Clarita. This accident also involved an intense fire that damaged the tunnel and required the closing of the tunnel for repairs to the concrete walls. The US Nuclear Regulatory Commission is studying both these accidents to examine any potential regulatory implications related to the safe transport of radioactive materials and spent nuclear fuel in the United States. This paper will provide a summary of that effort.
Reports on the topic "Burst potential"
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Choudhary, Ruplal, Victor Rodov, Punit Kohli, Elena Poverenov, John Haddock, and Moshe Shemesh. Antimicrobial functionalized nanoparticles for enhancing food safety and quality. United States Department of Agriculture, January 2013. http://dx.doi.org/10.32747/2013.7598156.bard.
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Original objectives The general goal of the project was to utilize the bactericidal potential of curcumin- functionalizednanostructures (CFN) for reinforcement of food safety by developing active antimicrobial food-contact surfaces. In order to reach the goal, the following secondary tasks were pursued: (a) further enhancement of the CFN activity based on understanding their mode of action; (b) preparing efficient antimicrobial surfaces, investigating and optimizing their performance; (c) testing the efficacy of the antimicrobial surfaces in real food trials. Background to the topic The project dealt with reducing microbial food spoilage and safety hazards. Cross-contamination through food-contact surfaces is one of the major safety concerns, aggravated by bacterial biofilm formation. The project implemented nanotech methods to develop novel antimicrobial food-contact materials based on natural compounds. Food-grade phenylpropanoidcurcumin was chosen as the most promising active principle for this research. Major conclusions, solutions, achievements In agreement with the original plan, the following research tasks were performed. Optimization of particles structure and composition. Three types of curcumin-functionalizednanostructures were developed and tested: liposome-type polydiacetylenenanovesicles, surface- stabilized nanoparticles and methyl-β-cyclodextrin inclusion complexes (MBCD). The three types had similar minimal inhibitory concentration but different mode of action. Nanovesicles and inclusion complexes were bactericidal while the nanoparticlesbacteriostatic. The difference might be due to different paths of curcumin penetration into bacterial cell. Enhancing the antimicrobial efficacy of CFN by photosensitization. Light exposure strengthened the bactericidal efficacy of curcumin-MBCD inclusion complexes approximately three-fold and enhanced the bacterial death on curcumin-coated plastic surfaces. Investigating the mode of action of CFN. Toxicoproteomic study revealed oxidative stress in curcumin-treated cells of E. coli. In the dark, this effect was alleviated by cellular adaptive responses. Under light, the enhanced ROS burst overrode the cellular adaptive mechanisms, disrupted the iron metabolism and synthesis of Fe-S clusters, eventually leading to cell death. Developing industrially-feasible methods of binding CFN to food-contact surfaces. CFN binding methods were developed for various substrates: covalent binding (binding nanovesicles to glass, plastic and metal), sonochemical impregnation (binding nanoparticles to plastics) and electrostatic layer-by-layer coating (binding inclusion complexes to glass and plastics). Investigating the performance of CFN-coated surfaces. Flexible and rigid plastic materials and glass coated with CFN demonstrated bactericidal activity towards Gram-negative (E. coli) and Gram-positive (Bac. cereus) bacteria. In addition, CFN-impregnated plastic material inhibited bacterial attachment and biofilm development. Testing the efficacy of CFN in food preservation trials. Efficient cold pasteurization of tender coconut water inoculated with E. coli and Listeriamonocytogeneswas performed by circulation through a column filled with CFN-coated glass beads. Combination of curcumin coating with blue light prevented bacterial cross contamination of fresh-cut melons through plastic surfaces contaminated with E. coli or Bac. licheniformis. Furthermore, coating of strawberries with CFN reduced fruit spoilage during simulated transportation extending the shelf life by 2-3 days. Implications, both scientific and agricultural BARD Report - Project4680 Page 2 of 17 Antimicrobial food-contact nanomaterials based on natural active principles will preserve food quality and ensure safety. Understanding mode of antimicrobial action of curcumin will allow enhancing its dark efficacy, e.g. by targeting the microbial cellular adaptation mechanisms.
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Hodul, M., H. P. White, and A. Knudby. A report on water quality monitoring in Quesnel Lake, British Columbia, subsequent to the Mount Polley tailings dam spill, using optical satellite imagery. Natural Resources Canada/CMSS/Information Management, 2022. http://dx.doi.org/10.4095/330556.
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In the early morning on the 4th of August 2014, a tailings dam near Quesnel, BC burst, spilling approximately 25 million m3 of runoff containing heavy metal elements into nearby Quesnel Lake (Byrne et al. 2018). The runoff slurry, which included lead, arsenic, selenium, and vanadium spilled through Hazeltine Creek, scouring its banks and picking up till and forest cover on the way, and ultimately ended up in Quesnel Lake, whose water level rose by 1.5 m as a result. While the introduction of heavy metals into Quesnel Lake was of environmental concern, the additional till and forest cover scoured from the banks of Hazeltine Creek added to the lake has also been of concern to salmon spawning grounds. Immediate repercussions of the spill involved the damage of sensitive environments along the banks and on the lake bed, the closing of the seasonal salmon fishery in the lake, and a change in the microbial composition of the lake bed (Hatam et al. 2019). In addition, there appears to be a seasonal resuspension of the tailings sediment due to thermal cycling of the water and surface winds (Hamilton et al. 2020). While the water quality of Quesnel Lake continues to be monitored for the tailings sediments, primarily by members at the Quesnel River Research Centre, the sample-and-test methods of water quality testing used, while highly accurate, are expensive to undertake, and not spatially exhaustive. The use of remote sensing techniques, though not as accurate as lab testing, allows for the relatively fast creation of expansive water quality maps using sensors mounted on boats, planes, and satellites (Ritchie et al. 2003). The most common method for the remote sensing of surface water quality is through the use of a physics-based semianalytical model which simulates light passing through a water column with a given set of Inherent Optical Properties (IOPs), developed by Lee et al. (1998) and commonly referred to as a Radiative Transfer Model (RTM). The RTM forward-models a wide range of water-leaving spectral signatures based on IOPs determined by a mix of water constituents, including natural materials and pollutants. Remote sensing imagery is then used to invert the model by finding the modelled water spectrum which most closely resembles that seen in the imagery (Brando et al 2009). This project set out to develop an RTM water quality model to monitor the water quality in Quesnel Lake, allowing for the entire surface of the lake to be mapped at once, in an effort to easily determine the timing and extent of resuspension events, as well as potentially investigate greening events reported by locals. The project intended to use a combination of multispectral imagery (Landsat-8 and Sentinel-2), as well as hyperspectral imagery (DESIS), combined with field calibration/validation of the resulting models. The project began in the Autumn before the COVID pandemic, with plans to undertake a comprehensive fieldwork campaign to gather model calibration data in the summer of 2020. Since a province-wide travel shutdown and social distancing procedures made it difficult to carry out water quality surveying in a small boat, an insufficient amount of fieldwork was conducted to suit the needs of the project. Thus, the project has been put on hold, and the primary researcher has moved to a different project. This document stands as a report on all of the work conducted up to April 2021, intended largely as an instructional document for researchers who may wish to continue the work once fieldwork may freely and safely resume. This research was undertaken at the University of Ottawa, with supporting funding provided by the Earth Observations for Cumulative Effects (EO4CE) Program Work Package 10b: Site Monitoring and Remediation, Canada Centre for Remote Sensing, through the Natural Resources Canada Research Affiliate Program (RAP).