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Sample records for affects p300 amplitude

  1. Intraindividual reaction time variability affects P300 amplitude rather than latency

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    Anusha eRamchurn

    2014-07-01

    Full Text Available The neural correlates of intraindividual response variability were investigated in a serial choice reaction time (CRT task. Reaction times (RTs from the faster and slower portions of the RT distribution for the task were separately aggregated and associated P300 event-related potentials computed. Independent behavioral measures of executive function and IQ were also recorded. Across frontal, fronto-central, central, centro-parietal and parietal scalp regions, P300 amplitudes were significantly greater for faster relative to slower behavioral responses. However, P300 peak amplitude latencies did not differ according to the speed of the behavioral RT. Importantly, controlling for select independent measures of executive function attenuated shared variance in P300 amplitude for faster and slower trials. The findings suggest that P300 amplitude rather than latency is associated with the speed of behavioral RTs, and the possibility that fluctuations in executive control underlie variability in speeded responding.

  2. A single high dose of escitalopram increases mismatch negativity without affecting processing negativity or P300 amplitude in healthy volunteers

    DEFF Research Database (Denmark)

    Wienberg, M; Glenthøj, Birte Yding; Jensen, K S

    2009-01-01

    processing. The present study was designed to replicate and further extent the results of our initial study on the effects of a low dose of escitalopram (10 mg) on MMN, PN and P300 amplitude. In a randomised, double-blind, cross-over experiment, 20 healthy male volunteers received either a single, orally...... administered dose of 15 mg escitalopram (a highly selective serotonin reuptake inhibitor (SSRI)) or placebo, after which their PN, MMN and P300 amplitude were assessed. Similar to our initial study with 10 mg escitalopram, 15 mg escitalopram significantly increased MMN, while it did not affect P300 amplitude....... In contrast to our initial study, however, the currently higher dose of escitalopram did not increase PN. Results support the view that a broad range of increased serotonergic activity enhances MMN, while the relationship between serotonin and PN seems more complex. The current study does not support...

  3. A model–based approach totrial–by–trial P300 amplitude fluctuations

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    Antonio eKolossa

    2013-02-01

    Full Text Available It has long been recognized that the amplitude of the P300 component of event–related brain potentials is sensitive to the degree to which eliciting stimuli are surprising to the observers (Donchin, 1981. While Squires et al. (1976 showed and modeled dependencies of P300 amplitudes from observed stimuli on various time scales, Mars et al. (2008 proposed a computational model keeping track of stimulus probabilities on a long–term time scale. We suggest here a computational model which integrates prior information with short–term, long–term, and alternation–based experiential influences on P300 amplitude fluctuations. To evaluate the new model, we measured trial–by–trial P300 amplitude fluctuations in a simple two–choice response time task, and tested the computational models of trial–by–trial P300 amplitudes using Bayesian model evaluation. The results reveal that the new digital filtering (DIF model provides a superior account of the trial–by–trial P300 amplitudes when compared to both, Squires et al.’s (1976 model, and Mars et al.’s (2008 model. We show that the P300–generating system can be described as two parallel first–order infinite impulse response (IIR low–pass filters and an additional fourth–order finite impulse response (FIR high–pass filter. Implications of the acquired data are discussed with regard to the neurobiological distinction between short–term, long–term, and working memory as well as from the point of view of predictive coding models and Bayesian learning theories of cortical function.

  4. A Model-Based Approach to Trial-By-Trial P300 Amplitude Fluctuations

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    Kolossa, Antonio; Fingscheidt, Tim; Wessel, Karl; Kopp, Bruno

    2013-01-01

    It has long been recognized that the amplitude of the P300 component of event-related brain potentials is sensitive to the degree to which eliciting stimuli are surprising to the observers (Donchin, 1981). While Squires et al. (1976) showed and modeled dependencies of P300 amplitudes from observed stimuli on various time scales, Mars et al. (2008) proposed a computational model keeping track of stimulus probabilities on a long-term time scale. We suggest here a computational model which integrates prior information with short-term, long-term, and alternation-based experiential influences on P300 amplitude fluctuations. To evaluate the new model, we measured trial-by-trial P300 amplitude fluctuations in a simple two-choice response time task, and tested the computational models of trial-by-trial P300 amplitudes using Bayesian model evaluation. The results reveal that the new digital filtering (DIF) model provides a superior account of the trial-by-trial P300 amplitudes when compared to both Squires et al.’s (1976) model, and Mars et al.’s (2008) model. We show that the P300-generating system can be described as two parallel first-order infinite impulse response (IIR) low-pass filters and an additional fourth-order finite impulse response (FIR) high-pass filter. Implications of the acquired data are discussed with regard to the neurobiological distinction between short-term, long-term, and working memory as well as from the point of view of predictive coding models and Bayesian learning theories of cortical function. PMID:23404628

  5. P300 latency and amplitude in Alzheimer's disease: a systematic review.

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    Pedroso, Renata Valle; Fraga, Francisco J; Corazza, Danilla Icassatti; Andreatto, Carla Andrezza Almeida; Coelho, Flávia Gomes de Melo; Costa, José Luiz Riani; Santos-Galduróz, Ruth Ferreira

    2012-01-01

    The P300 plays a key role as a method for monitoring and evaluating dementia, including Alzheimer's disease. The goal of this study was to search for articles which analyzed P300 latency and amplitude values in Alzheimer's disease. We searched in the following databases: Web of Science, Pub Med, Psyc Info, Medline, Biological Abstracts and Scielo using the following keywords: speed of information processing, processing speed, information processing, aged, older, elderly, older people, alzheimer dementia, alzheimer disease, Alzheimer and cross-references of selected articles. We found eight studies matching the inclusion criteria. These studies showed that there is a consensus on a P300 latency increase of elderly patients with Alzheimer's disease compared with subjects without the disease. However, it appears that, with respect to the P300 amplitude, there is still no consensus; however, it may be related to different methodological variables adopted in the reviewed studies. There is a need to standardize the variables involved in P300 measurement for senior citizens with Alzheimer's disease in order to be able to compare P300 latency and amplitude values for this population.

  6. Differences in P300 amplitudes and topography between cycloid psychosis and schizophrenia in Leonhard's classification.

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    Strik, W K; Dierks, T; Franzek, E; Maurer, K; Beckmann, H

    1993-03-01

    In a polydiagnostic approach, we investigated the parameters of auditory P300 in a group of 18 remitted schizophrenics and in 18 age- and sex-matched controls. All patients fulfilled the criteria of schizophrenic disorder according to DSM-III-R. Applying Leonhard's classification, patients were to be subdivided into 7 cycloid psychosis and 11 Leonhard's schizophrenics. Patients with cycloid psychosis fulfilled the operational criteria of Brockington et al. We found significantly lower P300 amplitudes in the group of Leonhard's schizophrenics than in controls and in cycloid psychosis, whereas no difference could be shown between patients with cycloid psychosis and controls. Both the maxima and the minima of the P300 field map were dislocated significantly to the right in the group of Leonhard's schizophrenics but not in cycloid psychosis.

  7. Reduced P300 amplitude during a visuospatial attention task in idiopathic rapid eye movement sleep behavior disorder.

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    Byun, Jung-Ick; Lee, Byeong Uk; Kim, Minah; Sunwoo, Jun-Sang; Lim, Jung-Ah; Moon, Jangsup; Lee, Soon-Tae; Jung, Keun-Hwa; Chu, Kon; Kim, Man-Ho; Jeong, Min Hee; Cha, Kwang Su; Choi, Jeong Woo; Kim, Kyung Hwan; Lee, Sang Kun; Jung, Ki-Young

    2017-10-01

    Idiopathic rapid eye movement sleep behavior disorder (IRBD) patients are prone to cognitive deficits, which include attention, executive, and visuospatial dysfunctions. Even patients with normal cognition may exhibit subclinical electrophysiological dysfunction. This study aimed to evaluate visuospatial attention processing in IRBD patients with normal cognition and to compare their findings with those of age- and sex-matched healthy controls. We recorded event-related potentials (ERPs) and performance measures during a variant of the Posner task in 14 IRBD patients and 14 control subjects. Behavioral data and the mean P300 amplitude were compared between groups. No group difference was found for reaction time or accuracy, but a significant group effect was observed for the P300 amplitude. IRBD patients had reduced P300 amplitude (μV) than controls in both valid (IRBD: 0.53 ± 1.05 vs Controls: 1.61 ± 0.95; p = 0.008) and invalid (IRBD: 0.74 ± 0.99 vs Controls: 1.73 ± 0.86; p = 0.009) conditions. The P300 amplitude was correlated with Montreal cognitive assessment (MOCA) scores (r = 0.424, p = 0.024). Reduced P300 amplitude during the Posner task provides electrophysiological evidence for subclinical visuospatial attention deficits in cognitively normal IRBD patients. The results of this study imply that cortical dysfunction is already present in patients with IRBD in their early disease stage. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. Mental Rotational Ability Is Correlated with Spatial but Not Verbal Working Memory Performance and P300 Amplitude in Males

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    Christie, Gregory J.; Cook, Charles M.; Ward, Brian J.; Tata, Matthew S.; Sutherland, Janice; Sutherland, Robert J.; Saucier, Deborah M.

    2013-01-01

    This study investigated how both sex and individual differences in a mental rotation test (MRT) influence performance on working memory (WM). To identify the neural substrate supporting these differences, brain electrical activity was measured using the event-related potential technique. No significant sex differences were observed in a test of verbal WM, however males were significantly faster than females to respond to probe stimuli in a test of spatial WM. This difference was no longer significant after controlling for differences in MRT score, suggesting that rotational ability mediates performance in the spatial memory task for both sexes. A posterior P300 was observed in both tasks as participants encoded information into memory, however the amplitude of the P300 correlated with RT in the spatial task but not in the verbal task. Individual differences in the MRT also correlated with RT and with the amplitude of the P300, but again only in the spatial task. After splitting the analysis by sex, partial correlations controlling for MRT revealed that for males, individual differences in rotational ability completely mediated the correlation between the P300 and RT in the spatial task. This mediating effect was not observed for the female participants. The results therefore suggest a relatively stronger association in males between innate mental rotational ability, spatial memory performance, and brain electrophysiological processes supporting spatial memory. PMID:23437381

  9. P300- like event related potential amplitude in rats is a correlate of conditioned reinforcement

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    William D. Klipec; Steven Faux

    2012-01-01

    We have developed a methodology for recording a robust P300 event related potential (ERP) in rats. In these experiments a contingency shaped model of the human “oddball’ paradigm was employed in which rats were shaped to press a lever for food reinforcement signaled by the click of the pellet dispenser. A target tone cued the insertion of the lever that retracted after 1­sec or immediately following a single reinforced response, while a non­target tone was randomly ...

  10. Moderate financial incentive does not appear to influence the P300 Concealed Information Test (CIT) effect in the Complex Trial Protocol (CTP) version of the CIT in a forensic scenario, while affecting P300 peak latencies and behavior.

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    Rosenfeld, J Peter; Sitar, Evan; Wasserman, Joshua; Ward, Anne

    2018-03-01

    Previous research indicated that the skin conductance response (SCR) of the Autonomic Nervous System (ANS) in the Concealed Information Test (CIT) is typically increased in subjects who are financially and otherwise incentivized to defeat the CIT (the paradoxical "motivational impairment" effect). This is not the case for RT-based CITs, nor for P300 tests based on the 3-stimulus protocol or Complex Trial Protocol for detection of cognitive malingering (although these are not the same as forensic CITs). The present report extends earlier studies of malingerers by running five groups of subjects (15-16 per group yielding 78 total) in a mock crime (forensic) scenario: paid (to beat the test) and unpaid, instructed and uninstructed, and simply guilty. There was no evidence that the "CIT effect" (probe-minus-irrelevant P300 differences) differed among groups, although behavioral differences among groups were seen. Copyright © 2018 Elsevier B.V. All rights reserved.

  11. Effects of aging on P300 between late young-age and early middle-age adulthood: an electroencephalogram event-related potential study.

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    Bourisly, Ali K

    2016-09-28

    The aim of this study was to identify age-related changes of P300 peak amplitude and P300 latency between closely separated nonsenile age groups (late young-aged adults and early middle-aged adults) and to investigate whether or not P300 has the potential to be used as a measure of cognitive aging even among nonsenile age groups. Twenty-eight adults (25-55 years old) completed an event-related potential oddball task. The elicitation of both P300 peak amplitude and P300 latency indicated age-related changes of P300. The results of the study showed that the P300 target peak amplitude was significantly larger in late young age compared with early middle age and that P300 target latency was also significantly delayed in early middle age compared with late young age. The results of this work contribute toward research efforts on a consensus on how aging affects event-related potential and/or P300. The main conclusions are that there exist significant age-related P300 changes even between closely separated, relatively younger, and nonsenile age groups, and that P300 has the potential to be used as a measure for cognitive aging even in nonsenile adults.

  12. The effect of jogging on P300 event related potentials.

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    Nakamura, Y; Nishimoto, K; Akamatu, M; Takahashi, M; Maruyama, A

    1999-03-01

    Physical exercise has beneficial effects not only on cardiovascular system and fat metabolism, may also directly effect the cognitive process. We studied the effect of physical exercise on cognitive processes by measuring the P300 event related-potential (ERP) after jogging. Seven well-trained joggers were enrolled in this study and the P300 potentials using auditory oddball paradigm. ERPs were measured before and after 30 minutes of jogging. The amplitude of the P300 significantly increased after jogging compared to values recorded before jogging. These findings suggest that jogging has the effect of facilitating cognitive processes involved in generation of the P300.

  13. Musical rhythms and their influence on P300 velocity in young females.

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    Sá, Cintia Ishii de; Pereira, Liliane Desguado

    2011-01-01

    Exposure to music may be useful in the P300 retest and avoid habituation. To verify the influence of the exposure to different kinds of music in P300 in young females. Clinical prospective. Forty-five women aged from 20 to 36 years were evaluated. P300 was studied before and after musical stimulation with different rhythms. Brazilian songs, international songs, and classical music melodies were selected. Each song had its velocity altered and was named as fast and slow. Subjects were divided into 2 groups exposed to music: one group was exposed to the fast version and the other to the slow version. The control group not exposed to music and was evaluated within the same time period of the others. There were statistically significant differences when comparing P300 amplitude in the first and third stimulation with the comparison group. In the same subject, several sequential registrations of P300 caused habituation, which was not seen during exposure to music before P300 recording. Exposure to music at preset different velocities did not affect the P300 in young females.

  14. Specific P300 features in patients with cycloid psychosis.

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    Strik, W K; Fallgatter, A J; Stoeber, G; Franzek, E; Beckmann, H

    1997-01-01

    In previous studies, low amplitudes and asymmetrical topography with right-sided peaks of the P300-evoked response have been repeatedly described in schizophrenic patients. A sample consisting of 18 patients with cycloid psychosis fulfilling the criteria of Perris and Brockington and 18 controls was investigated with a standard auditory odd-ball paradigm and multichannel evoked potential recordings. Patients had normal P300 topographies and latencies but significantly higher amplitudes than the controls. Higher than normal P300 amplitudes have not been described in any other psychiatric disorder until now, and indicate an enhanced level of arousal. Future studies are expected to shed light on the question of whether high P300 amplitudes are transitory sequelae of the acute psychotic episode or a trait of cycloid psychosis.

  15. Obstructive sleep apnea and P300 evoked auditory potential.

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    Martins, Carlos Henrique; Castro Júnior, Ney de; Costa Filho, Orozimbo Alves; Souza Neto, Osmar Mesquita de

    2011-01-01

    The obstructive sleep apnea syndrome (OSAS) reduces attention span, memory and concentration capacities, all associated with cognition. The analysis of the auditory P300 parameters could help infer cognitive dysfunction. To compare the data from polysomnography and the auditory P300 in adults, primary snorers with OSAS patients. Prospective study with primary snorers (N=12) and in OSAS patients (N=54), submitted to polysomnography, defined by the apnea-hypopnea index (AHI). The polysomnography and P300 variables were compared by the t-Student test, the Exact Fisher's Test, logistic regression and analysis of correlation with a significance level of 5%. AIH had an inverse correlation with the oximetry in both groups. The P300 prevalence was lower in the OSAS group (Fisher's Exact Test, p=0.027). Patient age did not influence the P300 prevalence (regression analysis; p=0.232). The P300 amplitude was lower in the OSAS group (t-Student test; p=0.003) and the P300 latency was similar in both groups (t-Student test; p=0.89). The reduction in the P300 amplitude in patients with OSAS suggests cognitive dysfunction induced by a reduction in auditory memory.

  16. Musical rhythms and their influence on P300 velocity in young females Ritmos musicais diferentes: influência da velocidade no P300 em jovens mulheres

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    Cintia Ishii de Sá

    2011-04-01

    Full Text Available Exposure to music may be useful in the P300 retest and avoid habituation. AIM: To verify the influence of the exposure to different kinds of music in P300 in young females. STUDY DESIGN: Clinical prospective. MATERIAL AND METHOD: Forty-five women aged from 20 to 36 years were evaluated. P300 was studied before and after musical stimulation with different rhythms. Brazilian songs, international songs, and classical music melodies were selected. Each song had its velocity altered and was named as fast and slow. Subjects were divided into 2 groups exposed to music: one group was exposed to the fast version and the other to the slow version. The control group not exposed to music and was evaluated within the same time period of the others. RESULT: There were statistically significant differences when comparing P300 amplitude in the first and third stimulation with the comparison group. CONCLUSION: In the same subject, several sequential registrations of P300 caused habituation, which was not seen during exposure to music before P300 recording. Exposure to music at preset different velocities did not affect the P300 in young females.Exposição musical pode auxiliar na reavaliação do P300 e evitar habituação. OBJETIVO: Verificar influência à exposição a diferentes tipos de música e velocidades no P300 em mulheres. FORMA DO ESTUDO: Clínico prospectivo. MATERIAIS E MÉTODOS: Participaram 45 mulheres, entre 20 e 36 anos. Estudamos o P300 antes e após estimulação musical. Selecionamos uma melodia brasileira, melodia não brasileira e melodia clássica. A mesma música teve sua velocidade alterada para rápida e lenta. A amostra foi constituída por dois grupos com exposição à música: um grupo foi exposto aos três tipos de música com velocidade lenta e o outro grupo exposto às mesmas músicas com velocidade rápida. E, um grupo comparação cujas medidas foram feitas sem exposição musical respeitando-se apenas os intervalos de tempo

  17. Cognitive deterioration and changes of P300 during total sleep deprivation.

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    Lee, Heon-Jeong; Kim, Leen; Suh, Kwang-Yoon

    2003-10-01

    The study was conducted to evaluate the cognitive deteriorations induced by sleep deprivation with the computerized neurocognitive tests and the P300 event-related potential. Thirty healthy college students (22 men, eight women) participated in the present study. Subjects remained awake for 38 h under continuous surveillance. In the morning and the evening of the two study days, the computerized neurocognitive tests and the P300 were performed. In vigilance test and reaction unit test, there were significant cognitive impairments during sleep deprivation. However, in the cognitrone test there was significant functional improvement, which might be due to the practice effect. The P300 latency was significantly prolonged and the amplitudes decreased during sleep deprivation. The cognitive impairment during 38 h of sleep deprivation was mainly in terms of vigilance and reaction time. In contrast, higher complex cognitive function such as fine perceptual analyses, visual discrimination and working memory might be not affected by 38 h of total sleep deprivation. The changes of P300 were significantly correlated with the results of vigilance and reaction unit tests but not with the cognitrone test. Taken together, these results suggest that the P300 changes that occur during sleep deprivation are a reflection of the decrement in vigilance, which prolongs reaction time.

  18. P300 from normals and adult children of alcoholics.

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    Polich, J; Bloom, F E

    1987-01-01

    The P300 event-related brain potential (ERP) was obtained from 24 pairs of undergraduate male subjects. One member of each pair reported having a father who was alcoholic (FH+), the other reported no alcoholic family member (FH-). Pairs were matched on height, weight, academic performance, and personal drinking history. Three auditory task situations were employed which manipulated stimulus discrimination difficulty. All tasks employed 20% target and 80% standard tones randomly presented with the subjects required to move their index finger whenever a target tone was detected. No differences in P300 amplitude or latency were obtained between the groups. FH+ subjects tended to demonstrate decreased amplitudes with increased amounts of reported alcohol consumption but only for the most difficult task. The results of the present study suggest that the relationship between the P300 and the heritability for alcoholism is not yet clear and may be modulated by differences in task requirements, subject populations, and personal drinking history.

  19. [Normative aspects of somatosensory evoked P300 components].

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    Louzã Neto, M R; Maurer, K; Neuhauser, B

    1989-06-01

    Using a somatosensory version of the oddball-paradigma the influence of age and gender on the P300-component and the comparison of the potential after stimulation of the right and left median nerve was studied in 30 healthy right handed volunteers (age: 20-35 years). Latency, amplitude, area and duration of the P300-potential were analysed. No relationship between age, gender and the P300-parameters were observed. The amplitude and the area of the potential obtained from the F3 electrode were greater after stimulation of the right median nerve compared to the potential after stimulation of the left median nerve. All other results were not significantly different. Strong positive correlations between the results after stimulation of the right and left median nerve were observed. These results showed that by a young group of volunteers age and gender did not influence the P300-component. Although the P300-Parameters had a between-subject variability, their mean remained constant over the study, their correlation coefficients were strong positive and the side of stimulation did not influence them (except for the electrode F3).

  20. Visual event-related potencial (P300: a normative study Potencial evocado visual relacionado a evento (P300: estudo normativo

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    Heloisa Veiga

    2004-09-01

    Full Text Available The P300 component of the Event-Related Potential (ERP is a general measurement of "cognitive efficiency". It is an index of the ability of an individual's Central Nervous System (CNS to process incoming information. OBJECTIVE: To develop a normative database for the visual P300. METHODOLOGY: 30 right-handed individuals (same number of each sex, between 20 and 30 years of age, healthy, free of any cognitive impairment and not making use of psychoactive substances. Participants were submitted to a visual discrimination task, which employed the "oddball" paradigm. RESULTS: The expected scalp distribution trend was seen for latency but not for amplitude values. CONCLUSION: A high variability of latency and amplitude values was observed across the age span. Mean reaction time for the entire sample of the study was 391.56 ± 37.03 ms.O componente P300 do Potencial Evocado Relacionado a Evento é uma medida geral de "eficiência cognitiva" e um índice da qualidade do processamento e armazenamento de informações pelo sistema nervoso central. OBJETIVO: Desenvolvimento de um banco normativo do P300 visual. METODOLOGIA: 30 sujeitos destros (ambos os sexos, entre 20 e 30 anos de idade, sadios e livres de qualquer déficit cognitivo. Os sujeitos não estavam fazendo uso de substâncias psicotrópicas ou psicoativas e foram submetidos a uma tarefa de discriminação visual utilizando o paradigma "oddball". RESULTADOS: O padrão de distribuição cortical esperado foi observado para os valores de latência, mas não para os de amplitude. CONCLUSÃO: Foi observada grande variabilidade dos valores de latência e amplitude no grupo analisado. O tempo de reação médio da amostra foi 391,56 ± 37,03 ms.

  1. P300 component of event-related potentials in persons with asperger disorder.

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    Iwanami, Akira; Okajima, Yuka; Ota, Haruhisa; Tani, Masayuki; Yamada, Takashi; Yamagata, Bun; Hashimoto, Ryuichiro; Kanai, Chieko; Takashio, Osamu; Inamoto, Atsuko; Ono, Taisei; Takayama, Yukiko; Kato, Nobumasa

    2014-10-01

    In the present study, we investigated auditory event-related potentials in adults with Asperger disorder and normal controls using an auditory oddball task and a novelty oddball task. Task performance and the latencies of P300 evoked by both target and novel stimuli in the two tasks did not differ between the two groups. Analysis of variance revealed that there was a significant interaction effect between group and electrode site on the mean amplitude of the P300 evoked by novel stimuli, which indicated that there was an altered distribution of the P300 in persons with Asperger disorder. In contrast, there was no significant interaction effect on the mean P300 amplitude elicited by target stimuli. Considering that P300 comprises two main subcomponents, frontal-central-dominant P3a and parietal-dominant P3b, our results suggested that persons with Asperger disorder have enhanced amplitude of P3a, which indicated activated prefrontal function in this task.

  2. Coupled particle filtering : A new approach for P300-based analysis of mental fatigue

    NARCIS (Netherlands)

    Jarchi, Delaram; Sanei, Saeid; Mohseni, Hamid R.; Lorist, Monicque M.

    A new method for investigating mental fatigue based on P300 variability is presented here. In this approach a new coupled particle filtering for tracking variability of P300 subcomponents, i.e., P3a and P3b, across trials is developed. The latency, amplitude, and width of each subcomponent, as the

  3. Financial incentive does not affect P300 (in response to certain episodic and semantic probe stimuli) in the Complex Trial Protocol (CTP) version of the Concealed Information Test (CIT) in detection of malingering.

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    Rosenfeld, J Peter; Labkovsky, Elena; Davydova, Elena; Ward, Anne; Rosenfeld, Lauren

    2017-05-01

    Previous research indicated that the skin conductance response of the autonomic nervous system in the Concealed Information Test (CIT) is typically increased in subjects who are financially and otherwise incentivized to defeat the CIT (the paradoxical "motivational impairment" effect). This is not the case for RT-based CITs, nor P300 tests based on the three-stimulus protocol for detection of cognitive malingering (although these are not the same as CITs). The present report is the first attempt to study the effect of financial motivation on the P300-based Complex Trial Protocol using both episodic and semantic memory probe and irrelevant stimuli. The Test of Memory Malingering (TOMM) was used to validate behavioral differences between the two groups we created by offering one (paid) group but not another (unpaid) group a financial reward for beating our tests. Group behavioral differences on the TOMM did confirm group manipulations. Probe-minus-irrelevant P300 differences did not differ between groups, although as previously, semantic memory-evoked P300s were larger than episodic memory-evoked P300s. © 2017 Society for Psychophysiological Research.

  4. Regional cerebral blood flow and P300 in neurosurgical disorders

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    Funahashi, Kazuyoshi; Hyoutani, Genhachi; Maeshima, Shinichirou; Miyamoto, Kazuki; Kuwata, Toshikazu; Terada, Tomoaki; Komai, Norihiko (Wakayama Medical Coll. (Japan))

    1990-08-01

    Changes in regional cerebral blood flow (rCBF), P300 and higher brain function were studied in neurosurgical patients with localized lesions on computed tomography (CT). Twenty-five patients ranging in age from 30 to 81 were studied. Nineteen of these suffered from cerebrovascular disease and six had tumors. Using the oddball paradigm, P300 components were elicited by rate tones (2 KHz) and recorded at Cz and Pz referred to linked ear-lobe electorodes. The P300 latencies of the patients were statistically compared with those of 27 normal subjects. Higher brain function was evaluated with the following psychological tests: a rating scale for psychological function (Sano and Tanemura), Mini-Mental State (MMS), Hasegawa's Dementia Scale (HDS) and the 'Kanahiroi' test. Regional CBF was measured in the bilateral cerebral cortices (the frontal, temporal and occipital lobes), thalamus and basal ganglia by means of a cold xenon CT method. The laterality indices of rCBF (Rt. rCBF/Lt. rCBF) in the bilateral symmetrical areas of the patients were compared to those of 8 normal subjects. Of the 25 patients, 12 revealed prolongation of P300 latency. Ten (86%) of the 12 with prolonged P300 latency showed reduction of rCBF in the right cerebral hemisphere (rt. frontal lobe, rt. thalamus and rt. basal ganglia). Significant correlations (P<0.025) were recognized between the P300 latencies and the laterality indices of rCBF in the frontal lobe and thalamus. There was a significant correlation (P<0.05) between the scores of MMS and HDS and the laterality indicies of rCBF in the frontal lobe only. In the 13 patients with normal P300 latency, 6 (46%) displayed no reduction in rCBF. The remaining 7 patients with normal P300 showed reduction of rCBF in the left hemisphere. Both right frontal lobe and right thalamus have an important role affecting the prolongation of P300 latency and disturbance of cognitive functions. (author).

  5. Regional cerebral blood flow and P300 in neurosurgical disorders

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    Funahashi, Kazuyoshi; Hyoutani, Genhachi; Maeshima, Shinichirou; Miyamoto, Kazuki; Kuwata, Toshikazu; Terada, Tomoaki; Komai, Norihiko

    1990-01-01

    Changes in regional cerebral blood flow (rCBF), P300 and higher brain function were studied in neurosurgical patients with localized lesions on computed tomography (CT). Twenty-five patients ranging in age from 30 to 81 were studied. Nineteen of these suffered from cerebrovascular disease and six had tumors. Using the oddball paradigm, P300 components were elicited by rate tones (2 KHz) and recorded at Cz and Pz referred to linked ear-lobe electorodes. The P300 latencies of the patients were statistically compared with those of 27 normal subjects. Higher brain function was evaluated with the following psychological tests: a rating scale for psychological function (Sano and Tanemura), Mini-Mental State (MMS), Hasegawa's Dementia Scale (HDS) and the 'Kanahiroi' test. Regional CBF was measured in the bilateral cerebral cortices (the frontal, temporal and occipital lobes), thalamus and basal ganglia by means of a cold xenon CT method. The laterality indices of rCBF (Rt. rCBF/Lt. rCBF) in the bilateral symmetrical areas of the patients were compared to those of 8 normal subjects. Of the 25 patients, 12 revealed prolongation of P300 latency. Ten (86%) of the 12 with prolonged P300 latency showed reduction of rCBF in the right cerebral hemisphere (rt. frontal lobe, rt. thalamus and rt. basal ganglia). Significant correlations (P<0.025) were recognized between the P300 latencies and the laterality indices of rCBF in the frontal lobe and thalamus. There was a significant correlation (P<0.05) between the scores of MMS and HDS and the laterality indicies of rCBF in the frontal lobe only. In the 13 patients with normal P300 latency, 6 (46%) displayed no reduction in rCBF. The remaining 7 patients with normal P300 showed reduction of rCBF in the left hemisphere. Both right frontal lobe and right thalamus have an important role affecting the prolongation of P300 latency and disturbance of cognitive functions. (author)

  6. P300 in individuals with sensorineural hearing loss

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    Ana Cláudia Mirandola Barbosa Reis

    2015-04-01

    Full Text Available INTRODUCTION: Behavioral and electrophysiological auditory evaluations contribute to the understanding of the auditory system and of the process of intervention.OBJECTIVE: To study P300 in subjects with severe or profound sensorineural hearing loss.METHODS: This was a descriptive cross-sectional prospective study. It included 29 individuals of both genders with severe or profound sensorineural hearing loss without other type of disorders, aged 11 to 42 years; all were assessed by behavioral audiological evaluation and auditory evoked potentials.RESULTS: A recording of the P3 wave was obtained in 17 individuals, with a mean latency of 326.97 ms and mean amplitude of 3.76 V. There were significant differences in latency in relation to age and in amplitude according to degree of hearing loss. There was a statistically significant association of the P300 results with the degrees of hearing loss (p = 0.04, with the predominant auditory communication channels (p < 0.0001, and with time of hearing loss.CONCLUSIONS: P300 can be recorded in individuals with severe and profound congenital sensorineural hearing loss; it may contribute to the understanding of cortical development and is a good predictor of the early intervention outcome.

  7. Neuronal correlates of a virtual-reality-based passive sensory P300 network.

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    Chun-Chuan Chen

    Full Text Available P300, a positive event-related potential (ERP evoked at around 300 ms after stimulus, can be elicited using an active or passive oddball paradigm. Active P300 requires a person's intentional response, whereas passive P300 does not require an intentional response. Passive P300 has been used in incommunicative patients for consciousness detection and brain computer interface. Active and passive P300 differ in amplitude, but not in latency or scalp distribution. However, no study has addressed the mechanism underlying the production of passive P300. In particular, it remains unclear whether the passive P300 shares an identical active P300 generating network architecture when no response is required. This study aims to explore the hierarchical network of passive sensory P300 production using dynamic causal modelling (DCM for ERP and a novel virtual reality (VR-based passive oddball paradigm. Moreover, we investigated the causal relationship of this passive P300 network and the changes in connection strength to address the possible functional roles. A classical ERP analysis was performed to verify that the proposed VR-based game can reliably elicit passive P300. The DCM results suggested that the passive and active P300 share the same parietal-frontal neural network for attentional control and, underlying the passive network, the feed-forward modulation is stronger than the feed-back one. The functional role of this forward modulation may indicate the delivery of sensory information, automatic detection of differences, and stimulus-driven attentional processes involved in performing this passive task. To our best knowledge, this is the first study to address the passive P300 network. The results of this study may provide a reference for future clinical studies on addressing the network alternations under pathological states of incommunicative patients. However, caution is required when comparing patients' analytic results with this study. For example

  8. Neuronal correlates of a virtual-reality-based passive sensory P300 network.

    Science.gov (United States)

    Chen, Chun-Chuan; Syue, Kai-Syun; Li, Kai-Chiun; Yeh, Shih-Ching

    2014-01-01

    P300, a positive event-related potential (ERP) evoked at around 300 ms after stimulus, can be elicited using an active or passive oddball paradigm. Active P300 requires a person's intentional response, whereas passive P300 does not require an intentional response. Passive P300 has been used in incommunicative patients for consciousness detection and brain computer interface. Active and passive P300 differ in amplitude, but not in latency or scalp distribution. However, no study has addressed the mechanism underlying the production of passive P300. In particular, it remains unclear whether the passive P300 shares an identical active P300 generating network architecture when no response is required. This study aims to explore the hierarchical network of passive sensory P300 production using dynamic causal modelling (DCM) for ERP and a novel virtual reality (VR)-based passive oddball paradigm. Moreover, we investigated the causal relationship of this passive P300 network and the changes in connection strength to address the possible functional roles. A classical ERP analysis was performed to verify that the proposed VR-based game can reliably elicit passive P300. The DCM results suggested that the passive and active P300 share the same parietal-frontal neural network for attentional control and, underlying the passive network, the feed-forward modulation is stronger than the feed-back one. The functional role of this forward modulation may indicate the delivery of sensory information, automatic detection of differences, and stimulus-driven attentional processes involved in performing this passive task. To our best knowledge, this is the first study to address the passive P300 network. The results of this study may provide a reference for future clinical studies on addressing the network alternations under pathological states of incommunicative patients. However, caution is required when comparing patients' analytic results with this study. For example, the task

  9. Slow movement execution in event-related potentials (P300).

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    Naruse, Kumi; Sakuma, Haruo; Hirai, Takane

    2002-02-01

    We examined whether slow movement execution has an effect on cognitive and information processing by measuring the P300 component. 8 subjects performed a continuous slow forearm rotational movement using 2 task speeds. Slow (a 30-50% decrease from the subject's Preferred speed) and Very Slow (a 60-80% decrease). The mean coefficient of variation for rotation speed under Very Slow was higher than that under Slow, showing that the subjects found it difficult to perform the Very Slow task smoothly. The EEG score of alpha-1 (8-10 Hz) under Slow Condition was increased significantly more than under the Preferred Condition; however, the increase under Very Slow was small when compared with Preferred. After performing the task. P300 latency under Very Slow increased significantly as compared to that at pretask. Further, P300 amplitude decreased tinder both speed conditions when compared to that at pretask, and a significant decrease was seen under the Slow Condition at Fz, whereas the decrease under the Very Slow Condition was small. These differences indicated that a more complicated neural composition and an increase in subjects' attention might have been involved when the task was performed under the Very Slow Condition. We concluded that slow movement execution may have an influence on cognitive function and may depend on the percentage of decrease from the Preferred speed of the individual.

  10. p300 Knockout Promotes Butyrate Resistance

    OpenAIRE

    Lazarova, Darina L.; Bordonaro, Michael

    2017-01-01

    Dietary fiber is linked to a reduced risk of colorectal cancer (CRC), and this protective activity is likely due to its fermentation product, butyrate. Dependent upon the hyperactivation of Wnt signaling, butyrate represses CRC cell growth and induces apoptosis. However, resistance to butyrate activity may allow for CRC development even in the context of relatively high fiber intake. We have previously determined that CRC cells resistant to butyrate are deficient in p300 expression. The histo...

  11. P300 during response inhibition is associated with ad-lib alcohol consumption in social drinkers.

    Science.gov (United States)

    Jones, Andrew; Field, Matt; Christiansen, Paul; Stancak, Andrej

    2013-06-01

    Reduced amplitude of the cortical P300 event-related potential (ERP) component during response inhibition is associated with vulnerability to alcohol use disorders. In the current study, we investigated the effect of an experimental manipulation of response conflict on the amplitude of the P300 component during response inhibition, and examined whether individual differences in the amplitude of this P300 component would predict voluntary ad-lib alcohol consumption, in social drinkers. Using a repeated measures design, 16 participants performed a stop-signal task after receiving instructions that either emphasised or de-emphasised response conflict while their electroencephalogram (EEG) was concurrently recorded, before their ad-lib drinking was assessed. Results revealed that task instructions had the predicted effects on behavioural indices of response inhibition and the associated P300 components. Most importantly, individual differences in the amplitude of P300 subcomponents during response inhibition were negatively correlated with ad-lib alcohol consumption. Results provide the first experimental support for theoretical models that posit that reduced amplitude of the P300 during response inhibition is associated with alcohol-seeking behaviour in humans.

  12. Does the 'P300' speller depend on eye gaze?

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    Brunner, P.; Joshi, S.; Briskin, S.; Wolpaw, J. R.; Bischof, H.; Schalk, G.

    2010-10-01

    Many people affected by debilitating neuromuscular disorders such as amyotrophic lateral sclerosis, brainstem stroke or spinal cord injury are impaired in their ability to, or are even unable to, communicate. A brain-computer interface (BCI) uses brain signals, rather than muscles, to re-establish communication with the outside world. One particular BCI approach is the so-called 'P300 matrix speller' that was first described by Farwell and Donchin (1988 Electroencephalogr. Clin. Neurophysiol. 70 510-23). It has been widely assumed that this method does not depend on the ability to focus on the desired character, because it was thought that it relies primarily on the P300-evoked potential and minimally, if at all, on other EEG features such as the visual-evoked potential (VEP). This issue is highly relevant for the clinical application of this BCI method, because eye movements may be impaired or lost in the relevant user population. This study investigated the extent to which the performance in a 'P300' speller BCI depends on eye gaze. We evaluated the performance of 17 healthy subjects using a 'P300' matrix speller under two conditions. Under one condition ('letter'), the subjects focused their eye gaze on the intended letter, while under the second condition ('center'), the subjects focused their eye gaze on a fixation cross that was located in the center of the matrix. The results show that the performance of the 'P300' matrix speller in normal subjects depends in considerable measure on gaze direction. They thereby disprove a widespread assumption in BCI research, and suggest that this BCI might function more effectively for people who retain some eye-movement control. The applicability of these findings to people with severe neuromuscular disabilities (particularly in eye-movements) remains to be determined.

  13. Síndrome da apneia obstrutiva do sono e o potencial auditivo P300 Obstructive sleep apnea and P300 evoked auditory potential

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    Carlos Henrique Martins

    2011-12-01

    Full Text Available A Síndrome da Apneia Obstrutiva do Sono (SAOS diminui as capacidades da atenção, memória e concentração, fatores relacionados com a cognição. A análise dos parâmetros do P300 auditivo permitiria inferir disfunção cognitiva. OBJETIVO: Comparar os dados da polissonografia e do P300 auditivo em adultos, roncopatas primários com portadores de SAOS. CASUÍSTICA E MÉTODO: Estudo prospectivo em roncopatas primários (N=12 e em portadores de SAOS (N=54, submetidos à polissonografia definidos pelo índice de apneia e hipopneia (IAH. As variáveis da polissonografia e as do P300 foram comparadas, pelos testes "T" de Student, exato de Fisher, regressão logística e análise de correlação com nível de significância de 5%. RESULTADOS: O IAH apresentou correlação inversa com a oximetria em ambos os grupos. A prevalência do P300 foi menor no G.SAOS (teste exato de Fisher, p=0,027. A idade dos pacientes não influenciou a prevalência do P300 (análise de regressão; p=0,232. A amplitude do P300 foi menor do G.SAOS (teste "T" de Student; p=0,003 a latência do P300 foi semelhante em ambos os grupos (teste "T" de Student; p=0,89. CONCLUSÃO: A redução da amplitude do P300 nos portadores de SAOS sugere disfunção cognitiva induzida por diminuição da memória auditiva.The obstructive sleep apnea syndrome (OSAS reduces attention span, memory and concentration capacities, all associated with cognition. The analysis of the auditory P300 parameters could help infer cognitive dysfunction. OBJECTIVE: To compare the data from polysomnography and the auditory P300 in adults, primary snorers with OSAS patients. MATERIALS AND METHODS: Prospective study with primary snorers (N=12 and in OSAS patients (N=54, submitted to polysomnography, defined by the apnea-hypopnea index (AHI. The polysomnography and P300 variables were compared by the t-Student test, the Exact Fisher's Test, logistic regression and analysis of correlation with a significance

  14. Auditory P300 event-related potential in tobacco smokers.

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    Guney, Figen; Genc, Bulent Oguz; Kutlu, Ruhusen; Ilhan, Bilge Cetin

    2009-10-01

    The aim of this study was to elucidate the chronic effects of tobacco smoking on the P300, a neurophysiological index of cognitive function. Prospective study participants were recruited from a family medicine polyclinic. We selected 32 right-handed smokers who had smoked more than 15 cigarettes per day, by inhalation, for more than 2 years. The control population consisted of 32 right-handed, age-matched healthy individuals who had never smoked. Event-related potentials (ERPs) were recorded with the auditory "oddball" two-tone discrimination task. The data from the central (Cz) and frontal (Fz) electrodes were analyzed. The P300 and N1 amplitudes at Fz were lower in the study population compared to the control group. The early component of ERP, the measure of mental speed (N1) latency at Fz was prolonged in the study group compared to the controls, possibly because early cognitive processes such as sensory input or initial encoding of sensory information were delayed in this group. For those who smoke, a decreased N1 amplitude might indicate delayed information processing and possibly short-term memory disturbance. Thus, chronic tobacco smoking may produce prefrontal cognitive dysfunction.

  15. Association between auditory P300, psychopathology, and memory function in drug-naïve schizophrenia.

    Science.gov (United States)

    Chang, Wei-Hung; Chen, Kao-Chin; Yang, Yen-Kuang; Chen, Po-See; Lu, Ru-Band; Yeh, Tzung-Lieh; Wang, Carol Sheei-Meei; Lee, I-Hui

    2014-03-01

    The aim of this study was to explore memory deficits and psychopathology and their relationships with P300 in drug-naïve patients with schizophrenia. The Positive and Negative Syndrome Scale (PANSS) and the Wechsler Memory Scale-Revised were administered. Auditory event-related potentials elicited by an oddball paradigm were obtained. After controlling for age, sex, the results showed a statistically significant negative correlation between the total PANSS score and P300 amplitude at the parietal position (r = -0.66, p visual memory was significantly positively correlated with P300 amplitude at the parietal position (r = 0.67, p memory decompensation in P300 among drug-naïve patients with schizophrenia may be considered, and the compensatory or Default Model Network might be a possible explanation of this association. Copyright © 2013. Published by Elsevier B.V.

  16. Use of a Green Familiar Faces Paradigm Improves P300-Speller Brain-Computer Interface Performance.

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    Li, Qi; Liu, Shuai; Li, Jian; Bai, Ou

    2015-01-01

    A recent study showed improved performance of the P300-speller when the flashing row or column was overlaid with translucent pictures of familiar faces (FF spelling paradigm). However, the performance of the P300-speller is not yet satisfactory due to its low classification accuracy and information transfer rate. To investigate whether P300-speller performance is further improved when the chromatic property and the FF spelling paradigm are combined. We proposed a new spelling paradigm in which the flashing row or column is overlaid with translucent green pictures of familiar faces (GFF spelling paradigm). We analyzed the ERP waveforms elicited by the FF and proposed GFF spelling paradigms and compared P300-speller performance between the two paradigms. Significant differences in the amplitudes of four ERP components (N170, VPP, P300, and P600f) were observed between both spelling paradigms. Compared to the FF spelling paradigm, the GFF spelling paradigm elicited ERP waveforms of higher amplitudes and resulted in improved P300-speller performance. Combining the chromatic property (green color) and the FF spelling paradigm led to better classification accuracy and an increased information transfer rate. These findings demonstrate a promising new approach for improving the performance of the P300-speller.

  17. Visual P300s in long-term abstinent chronic alcoholics.

    Science.gov (United States)

    Fein, George; Chang, Maria

    2006-12-01

    Evidence of reduced P3b amplitudes in chronic alcoholics and individuals at risk for developing alcoholism suggest that the P3b may be an endophenotypic marker for alcoholism. If this is the case, then long-term abstinent alcoholics (LTAAs) should exhibit reduced P3b amplitudes. Thus far, P3b studies on chronic alcoholics have focused primarily on samples with relatively short-term abstinence (less than 15 months). This study examines the amplitude and latency of the P3b and P3a event-related brain electrical components in LTAAs compared with normal controls (NCs) and whether these measures are related to alcohol use and other subject variables. Electroencephalographs (EEGs) were recorded on 48 LTAAs (mean abstinence=6.7 years) compared with 48 age-matched and gender-matched NCs during a visual P300 experiment consisting of standard, target, and rare nontarget conditions. This paradigm elicited the P3b (target condition) and the P3a (rare nontarget condition) components. Long-term abstinent alcoholics had reduced P3b amplitudes and increased P3b latencies in comparison with NCs. Long-term abstinent alcoholics also exhibited delayed P3a components, but no P3a amplitude reductions. Alcohol use variables, a family history of alcohol problems, and the duration of alcohol abstinence were not associated with any amplitude or latency variables. Even after very prolonged abstinence, reduced P3b amplitudes are present in chronic alcoholics and are not associated with any family history or alcohol use variables. These results provide equivocal support for reduced P3b amplitude being an endophenotypic marker for alcoholism, but are also consistent with P3b being affected by a threshold of alcohol abuse, with the effect not resolving over long periods of abstinence.

  18. P300 and the risk for alcoholism: family history, task difficulty, and gender.

    Science.gov (United States)

    Polich, J; Burns, T; Bloom, F E

    1988-04-01

    P300 event-related brain potentials (ERPs) were obtained from 20 pairs of male and 20 pairs of female undergraduate subjects. One member of each pair reported having a father who was alcoholic (FHP), the other reported no known alcoholic biological relative (FHN). Pair members were matched on age, height, weight, grade point average, and personal drinking history. Three auditory tasks which differed in stimulus discrimination difficulty were presented to each subject. All tasks employed 20% target and 80% standard tones with the subject required to move their index finger whenever a target stimulus was detected. No significant differences in P300 amplitude or latency were obtained between the family history subject groups, although female FHP subjects tended to have smaller P300 amplitudes than their FHN counterparts. P300 amplitude decreased with increases in the amount of self-reported alcohol consumed for FHP subjects but significantly so only for the most difficult task situation. The results suggest that the relationship between the P300 ERP and the inheritability of alcoholism is not yet clear and may be subject to modulation by task requirements, population differences, and subject sex.

  19. P300 and alcohol consumption in normals and individuals at risk for alcoholism. A preliminary report.

    Science.gov (United States)

    Polich, J; Bloom, F E

    1986-01-01

    Pairs of college student subjects (36 male, 36 female) were matched on age, sex, and personal drinking history. One pair member had a parent who met the DSM III criteria of alcoholism, while the other pair member had no close alcoholic relative. The P300 event-related brain potential (ERP) was obtained from each subject with auditory stimuli in an "oddball" paradigm. Target stimuli occurred randomly on 20% of the trials in a frequency discrimination task, a relatively easy intensity discrimination task, and a more difficult intensity discrimination task. Subjects indicated when the target items occurred by moving their index finger. No significant overall effects were obtained for family history for either P300 latency or amplitude. P300 latency increased and amplitude decreased with increases in the reported amount of alcohol consumption in all subjects only for the difficult intensity task but were statistically significant only for individuals with a negative family history for alcoholism.

  20. Application of the P300 Event-Related Potential in the Diagnosis of Epilepsy Disorder: A Review

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    Kandhasamy Sowndhararajan

    2018-03-01

    Full Text Available Epilepsy is one of the most serious chronical neurological disorders, affecting more than 50 million people worldwide. It can be defined as a spectrum disorder, and patients with epilepsy possess abnormalities in cognitive functions. A number of factors can cause cognitive dysfunctions in epileptic syndromes, including etiology, the age of onset, type of seizure and severity, duration, and antiepileptic drugs. Event-related potentials (ERPs are very useful clinical and research instruments to evaluate cognitive function in patients with neuropsychiatry disorders. Event-related potentials directly reflect cortical neuronal activity and provide a particular level of temporal resolution. Among various ERP components, the P300 is the most important component for assessing cognitive processes such as attention, working memory, and concentration. Numerous studies have reported the abnormalities in amplitude or latency of P300 component of ERP in epileptic patients, and these abnormalities are indicative of cognitive dysfunction. Therefore, the purpose of this review is to consolidate the existing literature in connection with the use of P300 in epileptic patients.

  1. [The P300-based brain-computer interface: presentation of the complex "flash + movement" stimuli].

    Science.gov (United States)

    Ganin, I P; Kaplan, A Ia

    2014-01-01

    The P300 based brain-computer interface requires the detection of P300 wave of brain event-related potentials. Most of its users learn the BCI control in several minutes and after the short classifier training they can type a text on the computer screen or assemble an image of separate fragments in simple BCI-based video games. Nevertheless, insufficient attractiveness for users and conservative stimuli organization in this BCI may restrict its integration into real information processes control. At the same time initial movement of object (motion-onset stimuli) may be an independent factor that induces P300 wave. In current work we checked the hypothesis that complex "flash + movement" stimuli together with drastic and compact stimuli organization on the computer screen may be much more attractive for user while operating in P300 BCI. In 20 subjects research we showed the effectiveness of our interface. Both accuracy and P300 amplitude were higher for flashing stimuli and complex "flash + movement" stimuli compared to motion-onset stimuli. N200 amplitude was maximal for flashing stimuli, while for "flash + movement" stimuli and motion-onset stimuli it was only a half of it. Similar BCI with complex stimuli may be embedded into compact control systems requiring high level of user attention under impact of negative external effects obstructing the BCI control.

  2. Association between auditory P300, psychopathology, and memory function in drug-naïve schizophrenia

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    Wei-Hung Chang

    2014-03-01

    Full Text Available The aim of this study was to explore memory deficits and psychopathology and their relationships with P300 in drug-naïve patients with schizophrenia. The Positive and Negative Syndrome Scale (PANSS and the Wechsler Memory Scale—Revised were administered. Auditory event-related potentials elicited by an oddball paradigm were obtained. After controlling for age, sex, the results showed a statistically significant negative correlation between the total PANSS score and P300 amplitude at the parietal position (r = −0.66, p < 0.05. Moreover, visual memory was significantly positively correlated with P300 amplitude at the parietal position (r = 0.67, p < 0.05. After controlling for the duration of illness, the above correlations remained statistically significant. The correlation between P300 and the severity of psychopathology was reconfirmed in drug-naïve patients with schizophrenia. A possible contribution of memory decompensation in P300 among drug-naïve patients with schizophrenia may be considered, and the compensatory or Default Model Network might be a possible explanation of this association.

  3. Manipulating attention via mindfulness induction improves P300-based brain-computer interface performance

    Science.gov (United States)

    Lakey, Chad E.; Berry, Daniel R.; Sellers, Eric W.

    2011-04-01

    In this study, we examined the effects of a short mindfulness meditation induction (MMI) on the performance of a P300-based brain-computer interface (BCI) task. We expected that MMI would harness present-moment attentional resources, resulting in two positive consequences for P300-based BCI use. Specifically, we believed that MMI would facilitate increases in task accuracy and promote the production of robust P300 amplitudes. Sixteen-channel electroencephalographic data were recorded from 18 subjects using a row/column speller task paradigm. Nine subjects participated in a 6 min MMI and an additional nine subjects served as a control group. Subjects were presented with a 6 × 6 matrix of alphanumeric characters on a computer monitor. Stimuli were flashed at a stimulus onset asynchrony (SOA) of 125 ms. Calibration data were collected on 21 items without providing feedback. These data were used to derive a stepwise linear discriminate analysis classifier that was applied to an additional 14 items to evaluate accuracy. Offline performance analyses revealed that MMI subjects were significantly more accurate than control subjects. Likewise, MMI subjects produced significantly larger P300 amplitudes than control subjects at Cz and PO7. The discussion focuses on the potential attentional benefits of MMI for P300-based BCI performance.

  4. P300 correlates with learning & memory abilities and fluid intelligence.

    Science.gov (United States)

    Amin, Hafeez Ullah; Malik, Aamir Saeed; Kamel, Nidal; Chooi, Weng-Tink; Hussain, Muhammad

    2015-09-23

    Educational psychology research has linked fluid intelligence with learning and memory abilities and neuroimaging studies have specifically associated fluid intelligence with event related potentials (ERPs). The objective of this study is to find the relationship of ERPs with learning and memory recall and predict the memory recall score using P300 (P3) component. A sample of thirty-four healthy subjects between twenty and thirty years of age was selected to perform three tasks: (1) Raven's Advanced Progressive Matrices (RAPM) test to assess fluid intelligence; (2) learning and memory task to assess learning ability and memory recall; and (3) the visual oddball task to assess brain-evoked potentials. These subjects were divided into High Ability (HA) and Low Ability (LA) groups based on their RAPM scores. A multiple regression analysis was used to predict the learning & memory recall and fluid intelligence using P3 amplitude and latency. Behavioral results demonstrated that the HA group learned and recalled 10.89 % more information than did the LA group. ERP results clearly showed that the P3 amplitude of the HA group was relatively larger than that observed in the LA group for both the central and parietal regions of the cerebrum; particularly during the 300-400 ms time window. In addition, a shorter latency for the P3 component was observed at Pz site for the HA group compared to the LA group. These findings agree with previous educational psychology and neuroimaging studies which reported an association between ERPs and fluid intelligence as well as learning performance. These results also suggest that the P3 component is associated with individual differences in learning and memory recall and further indicate that P3 amplitude might be used as a supporting factor in standard psychometric tests to assess an individual's learning & memory recall ability; particularly in educational institutions to aid in the predictability of academic skills.

  5. Snail acetylation by histone acetyltransferase p300 in lung cancer

    OpenAIRE

    Chang, Rui; Zhang, Yinjie; Zhang, Peng; Zhou, Qinghua

    2017-01-01

    Background Epithelial to mesenchymal transition (EMT) is a complex and dynamic molecular event in lung cancer metastasis that has not yet been thoroughly investigated. EMT transcriptional factors, such as Snail, play a central role in regulation of the EMT process. In this study, we sought to identify an association between p300 and Snail in lung cancer, as well as the engagement of p300 in Snail acetylation. Methods We transfected p300 small interfering RNA into lung cancer cells to detect S...

  6. Prediction of auditory and visual p300 brain-computer interface aptitude.

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    Sebastian Halder

    Full Text Available OBJECTIVE: Brain-computer interfaces (BCIs provide a non-muscular communication channel for patients with late-stage motoneuron disease (e.g., amyotrophic lateral sclerosis (ALS or otherwise motor impaired people and are also used for motor rehabilitation in chronic stroke. Differences in the ability to use a BCI vary from person to person and from session to session. A reliable predictor of aptitude would allow for the selection of suitable BCI paradigms. For this reason, we investigated whether P300 BCI aptitude could be predicted from a short experiment with a standard auditory oddball. METHODS: Forty healthy participants performed an electroencephalography (EEG based visual and auditory P300-BCI spelling task in a single session. In addition, prior to each session an auditory oddball was presented. Features extracted from the auditory oddball were analyzed with respect to predictive power for BCI aptitude. RESULTS: Correlation between auditory oddball response and P300 BCI accuracy revealed a strong relationship between accuracy and N2 amplitude and the amplitude of a late ERP component between 400 and 600 ms. Interestingly, the P3 amplitude of the auditory oddball response was not correlated with accuracy. CONCLUSIONS: Event-related potentials recorded during a standard auditory oddball session moderately predict aptitude in an audiory and highly in a visual P300 BCI. The predictor will allow for faster paradigm selection. SIGNIFICANCE: Our method will reduce strain on patients because unsuccessful training may be avoided, provided the results can be generalized to the patient population.

  7. Does Fundus Fluorescein Angiography Procedure Affect Ocular Pulse Amplitude?

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    Gökhan Pekel

    2013-01-01

    Full Text Available Purpose. This study examines the effects of fundus fluorescein angiography (FFA procedure on ocular pulse amplitude (OPA and intraocular pressure (IOP. Materials and Methods. Sixty eyes of 30 nonproliferative diabetic retinopathy patients (15 males, 15 females were included in this cross-sectional case series. IOP and OPA were measured with the Pascal dynamic contour tonometer before and after 5 minutes of intravenous fluorescein dye injection. Results. Pre-FFA mean OPA value was  mmHg and post-FFA mean OPA value was  mmHg (. Pre-FFA mean IOP value was  mmHg and post-FFA mean IOP value was  mmHg (. Conclusion. Although both mean OPA and IOP values were decreased after FFA procedure, the difference was not statistically significant. This clinical trial is registered with Australian New Zealand Clinical Trials Registry number ACTRN12613000433707.

  8. A P300 brain-computer interface based on a modification of the mismatch negativity paradigm.

    Science.gov (United States)

    Jin, Jing; Sellers, Eric W; Zhou, Sijie; Zhang, Yu; Wang, Xingyu; Cichocki, Andrzej

    2015-05-01

    The P300-based brain-computer interface (BCI) is an extension of the oddball paradigm, and can facilitate communication for people with severe neuromuscular disorders. It has been shown that, in addition to the P300, other event-related potential (ERP) components have been shown to contribute to successful operation of the P300 BCI. Incorporating these components into the classification algorithm can improve the classification accuracy and information transfer rate (ITR). In this paper, a single character presentation paradigm was compared to a presentation paradigm that is based on the visual mismatch negativity. The mismatch negativity paradigm showed significantly higher classification accuracy and ITRs than a single character presentation paradigm. In addition, the mismatch paradigm elicited larger N200 and N400 components than the single character paradigm. The components elicited by the presentation method were consistent with what would be expected from a mismatch paradigm and a typical P300 was also observed. The results show that increasing the signal-to-noise ratio by increasing the amplitude of ERP components can significantly improve BCI speed and accuracy. The mismatch presentation paradigm may be considered a viable option to the traditional P300 BCI paradigm.

  9. P300 WAVE CONFIRMATION IN PATIENTS WITH PARKINSON’S DISEASE

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    Marko Pišljar

    2001-11-01

    Full Text Available Background. Mild to moderate cognitive dysfunction is a frequent complaint of patients with Parkinson’s disease, though the clinical picture of dementia is rarely reported.Methods. The development of cognitive deficits seams to be associated with hypokinesia and rigidy rather than tremor. In our study, auditory ERP were used to confirm cognitive alterations in two groups of non-demented patients with idiopathic Parkinson’s disease. Mini mental test was performed to exclude clinical picture of dementia. Patients were classified according to the Hoehen-Yahr and Webster scale. The Beck depression score in Parkinson’s patient was assessed.Auditory event related potentials were recorded using the »oddball« paradigm. The waves N100, P200, N200 and P300 were recorded and their latencies and amplitudes measured.Results and conclusions. The P300 latencies in both patients group were significantly longer (p < 0.05, than in the control group. P300 latency was longer in non tremor group. There were no significant statistical differences in latencies between the both groups. All patients had normal N100 latency. Significant decline of P300 amplitude was found only in non-tremor group (p < 0.001.

  10. A portable auditory P300 brain-computer interface with directional cues.

    Science.gov (United States)

    Käthner, Ivo; Ruf, Carolin A; Pasqualotto, Emanuele; Braun, Christoph; Birbaumer, Niels; Halder, Sebastian

    2013-02-01

    The main objective of the current study was to implement and evaluate a P300 based brain-computer interface (BCI) speller that uses directional cues of auditory stimuli, which are presented over headphones. The interstimulus interval (ISI) was successively reduced to determine the optimal combination of speed and accuracy. The study further aimed at quantifying the differences in subjective workload between the auditory and the visual P300 spelling application. The influence of workload, mood and motivation on BCI performance and P300 amplitude was investigated. Twenty healthy participants performed auditory and visual spelling tasks in an EEG experiment with online feedback. Sixteen of twenty participants performed at or above a level necessary for satisfactory communication (≥70% spelling accuracy) with the auditory BCI. Average bit rates of up to 2.76 bits/min (best subject 7.43 bits/min) were achieved. A significantly higher workload was reported for the auditory speller compared to the visual paradigm. Motivation significantly influenced P300 amplitude at Pz in the auditory condition. The results of the online study suggest that the proposed paradigm offers a means of communication for most healthy users. The described auditory BCI can serve as a communication channel for completely paralyzed patients. Copyright © 2012 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

  11. Comparison of Auditory Event-Related Potential P300 in Sighted and Early Blind Individuals

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    Fatemeh Heidari

    2010-06-01

    Full Text Available Background and Aim: Following an early visual deprivation, the neural network involved in processing auditory spatial information undergoes a profound reorganization. In order to investigate this process, event-related potentials provide accurate information about time course neural activation as well as perception and cognitive processes. In this study, the latency and amplitude of auditory P300 were compared in sighted and early blind individuals in age range of 18-25 years old.Methods: In this cross-sectional study, auditory P300 potential was measured in conventional oddball paradigm by using two tone burst stimuli (1000 and 2000 Hz on 40 sighted subjects and 19 early blind subjects with mean age 20.94 years old.Results: The mean latency of P300 in early blind subjects was significantly smaller than sighted subjects (p=0.00.( There was no significant difference in amplitude between two groups (p>0.05.Conclusion: Reduced latency of P300 in early blind subjects in comparison to sighted subjects probably indicates the rate of automatic processing and information categorization is faster in early blind subjects because of sensory compensation. It seems that neural plasticity increases the rate of auditory processing and attention in early blind subjects.

  12. Cognitive Evoked Potential Measurement, P300, in a group of healthy Colombian individuals

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    Natalia Gutiérrez Giraldo

    2013-05-01

    Full Text Available Cognitive evoked potentials are electrophysiological measurements of cognitive functions. Cognitivepotential P300 is specifically related to attention processes. Objetive: the aim of this studywas to establish reference values for latency and amplitude of P300 wave in the Colombian population and determine their variability with age, gender and education of the subjects. Methods:we studied 122 healthy subjects between 6 and 80 years, are practical potential measurementmethodology as odd-ball, in leads Cz and Pz. Results: we were able to establish reference valuesfor different age groups, and statistical significance was found with which the latency of P300wave increases with the age of individuals, and instead thereof the amplitude tends to decrease.Similarly to correlate latency and amplitude was shown an inverse relationship between them.Conclusions: no differences were found for latency and wave amplitude, gender-related or schoolsubjects as well as no difference was found when measuring the Pz derivation obtained comparedwith the wave in lead Cz.

  13. P300 brain computer interface: current challenges and emerging trends

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    Reza eFazel-Rezai

    2012-07-01

    Full Text Available A brain-computer interface (BCI enables communication without movement based on brain signals measured with electroencephalography (EEG. BCIs usually rely on one of three types of signals: the P300 and other components of the event-related potential (ERP, steady state visual evoked potential (SSVEP, or event related desynchronization (ERD. Although P300 BCIs were introduced over twenty years ago, the past few years have seen a strong increase in P300 BCI research. This closed-loop BCI approach relies on the P300 and other components of the event-related potential (ERP, based on an oddball paradigm presented to the subject. In this paper, we overview the current status of P300 BCI technology, and then discuss new directions: paradigms for eliciting P300s; signal processing methods; applications; and hybrid BCIs. We conclude that P300 BCIs are quite promising, as several emerging directions have not yet been fully explored and could lead to improvements in bit rate, reliability, usability, and flexibility.

  14. Auditory evoked potential P300 in adults: reference values.

    Science.gov (United States)

    Didoné, Dayane Domeneghini; Garcia, Michele Vargas; Oppitz, Sheila Jacques; Silva, Thalisson Francisco Finamôr da; Santos, Sinéia Neujahr Dos; Bruno, Rúbia Soares; Filha, Valdete Alves Valentins Dos Santos; Cóser, Pedro Luis

    2016-01-01

    To establish reference intervals for cognitive potential P300 latency using tone burst stimuli. This study involved 28 participants aged between 18 and 59 years. P300 recordings were performed using a two-channel device (Masbe, Contronic). Electrode placement was as follows: Fpz (ground electrode), Cz (active electrode), M1 and M2 (reference electrodes). Intensity corresponded to 80 dB HL and frequent and rare stimulus frequencies to 1,000Hz and 2,000Hz, respectively. Stimuli were delivered binaurally. Mean age of participants was 35 years. Average P300 latency was 305ms. Maximum acceptable P300 latency values of 362.5ms (305 + 2SD 28.75) were determined for adults aged 18 to 59 years using the protocol described. Estabelecer valores de referência para a latência do potencial cognitivo P300 com estímulos tone burst. Participaram do estudo 28 indivíduos entre 18 e 59 anos. O registro do P300 foi realizado no equipamento Masbe da marca Contronic. Os eletrodos foram fixados nas posições Fpz (eletrodo terra), Cz (eletrodo ativo), M1 e M2 (eletrodos referência). A intensidade foi de 80 dB NA. A frequência do estímulo frequente foi de 1.000Hz e a do estímulo raro de 2.000Hz. Os estímulos foram apresentados na forma binaural. A média de idade dos indivíduos foi de 35 anos. A média de latência para P300 de 305ms. Usando o protocolo descrito, o valor máximo de latência aceitáveis para P300 foram de 362,5ms (305 + 2DP 28,75) na faixa etária do adulto de 18 a 59 anos.

  15. P300 brain potential among workers exposed to organic solvents

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    Bente E. Moen

    2009-10-01

    Full Text Available  SUMMARYThe P300 component of the auditory event-related brain potential was examined in a group of 11workers exposed to low levels of organic solvents in a paint factory and 11 unexposed controls beforeand after 3 weeks of summer vacation. The P300 latency time was found to be prolonged among theexposed workers compared to the reference group before the summer vacation, and to be significantlylonger before the vacation than after in the exposed group.The P300 component was also examined in a group of 85 seamen from chemical tankers, experiencingpeak exposures to organic solvents. They were compared to a reference group of unexposedseamen. Comparing these two groups, no difference was found in the P300 latency time. No relationshipbetween the P300 latency time and exposure was found in a multiple regression analysis, includingthe variables age, alcohol consumption, smoking and cerebral concussions.The study indicates the occurrence of an acute biological effect in the nervous system related toorganic solvent exposure, expressed by prolonged P300 latency time. This was found at very lowexposure levels and should be studied further.

  16. Potencial evocado auditivo tardio relacionado a eventos (P300 na síndrome de Down Late auditory event-related evoked potential (P300 in Down's syndrome patients

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    Carla Patrícia Hernandez Alves Ribeiro César

    2010-04-01

    Full Text Available A síndrome de Down é causada pela trissomia do cromossomo 21 e está associada com alteração do processamento auditivo, distúrbio de aprendizagem e, provavelmente, início precoce de Doença de Alzheimer. OBJETIVO: Avaliar as latências e amplitudes do potencial evocado auditivo tardio relacionado a eventos (P300 e suas alterações em indivíduos jovens adultos com síndrome de Down. MATERIAL E MÉTODO: Estudo de caso prospectivo. Latências e amplitudes do P300 foram avaliadas em 17 indivíduos com síndrome de Down e 34 indivíduos sadios. RESULTADOS: Foram identificadas latências do P300 (N1, P2, N2 e P3 prolongadas e amplitude N2 - P3 diminuída nos indivíduos com síndrome de Down quando comparados ao grupo controle. CONCLUSÃO: Em indivíduos jovens adultos com síndrome de Down ocorre aumento das latências N1, P2, N2 e P3, e diminuição significativa da amplitude N2-P3 do potencial evocado auditivo tardio relacionado a eventos (P300, sugerindo prejuízo da integração da área de associação auditiva com as áreas corticais e subcorticais do sistema nervoso central.Down syndrome is caused by a trisomy of chromosome 21 and is associated with central auditory processing deficit, learning disability and, probably, early-onset Alzheimer's disease. AIM: to evaluate the latencies and amplitudes of evoked late auditory potential related to P300 events and their changes in young adults with Down's syndrome. MATERIALS AND METHODS: Prospective case study. P300 test latency and amplitudes were evaluated in 17 individuals with Down's syndrome and 34 healthy individuals. RESULTS The P300 latency (N1, P2, N2 and P3 was longer and the N2-P3 amplitude was lower in individuals with Down syndrome when compared to those in the control group. CONCLUSION: In young adults with Down syndrome, N1, P2, N2 and P3 latencies of late auditory evoked potential related to P300 events were prolonged, and N2 - P3 amplitudes were significantly reduced

  17. Superior temporal gyrus volume reduction and P300 in schizophrenia prior to treatment

    International Nuclear Information System (INIS)

    Hirayasu, Akira; Hokama, Hiroto; Ogura, Chikara; Ohta, Hirokazu; Arakaki, Hajime; Asato, Naohiko; Yamaguchi, Keiichiro

    1998-01-01

    Authors measured the superior temporal gyrus volume by 3D MRI imaging for the schizophrenics and simultaneously recorded the P300 component during the auditory odd-ball exercise. Subjects were 8 cases of schizophrenics and the sex- and age-matched healthy control adults. In schizophrenics, the superior temporal gyrus volume reduction was found. When the superior temporal gyrus was divided into two parts, the anterior part containing the primary auditory area, and the posterior part containing the planum temporale and the Wernicle speech area, the volume reduction of left side in the posterior part was remarkable. There was no difference in the latent time and the P300 amplitude between schizophrenics and healthy controls, suggesting that the superior temporal gyrus abnormalities will appear prior to P300 abnormalities. We could not find any correlation between findings of MRI and P300 and psychic symptoms. We discuss the possible contribution on the elucidation of the pathogenesis of the schizophrenia by simultaneous recordings of 3D MRI imaging and the event-related potentials. (K.H.)

  18. The value of P300 event related potentials in the assessment of cognitive function in subclinical hypothyroidism.

    Science.gov (United States)

    Dejanović, Mirjana; Ivetić, Vesna; Nestorović, Vojkan; Milanović, Zvezdan; Erić, Mirela

    2017-03-01

    Mild hypothyroidism (thyroid stimulating hormone [TSH] less than 10 mIU/L) induces reversible cognitive dysfunction, which can be evaluated by event related potentials (ERP). So far, only little is known about the impact of subclinical hypothyroidism on ERP as electrophysiological markers of cognitive activity. The aim of this study was to follow-up P300 latencies and amplitudes in patients with subclinical hypothyroidism and to evaluate the influence of thyroxine treatment which led to the normalization of TSH level in serum. We recorded the P300 wave using an auditory oddball paradigm in 60 patients (mean age 51.1±6.2 years, range 40-62 years), with subclinical hypothyroidism (normal mean value of FT4, with elevated TSH levels) at baseline, after 3 months, after 6 months and in 30 healthy control subjects. 30 patients treated six months with L-thyroxine until the normalization of TSH and 30 patients received placebo. The P300 latencies in patients with subclinical hypothyroidism were significantly longer, and the P300 amplitudes were significantly smaller than those of the control group. In the thyroxine treated patients P300 latency continuously decreased over the observation period with a significant difference after 6 months compared to baseline (Phypothyroidism. The P300 latency stands out as a marker for cognitive function recovery during treatment with thyroxine.

  19. ABR and auditory P300 findings inchildren with ADHD

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    Schochat Eliane

    2002-01-01

    Full Text Available Auditory processing disorders (APD, also referred as central auditory processing disorders (CAPD and attention deficit hyperactivity disorders (ADHD have become popular diagnostic entities for school age children. It has been demonstrated a high incidence of comorbid ADHD with communication disorders and auditory processing disorder. The aim of this study was to investigate ABR and P300 auditory evoked potentials in children with ADHD, in a double-blind study. Twenty-one children, ages between 7 and 10 years, with a primary diagnosis of ADHD, participated in this experiment. Results showed that all children had normal ABR with normal latency for wave V. Results also showed that among 42 ears combined 52.38% did not have P300. For the medicated subjects we observed that among 28 ears, 42.85% did not have P300 and for the non-medicated 71.43% (N = 14 ears did not have P300. Our results suggest that the medicated subjects had more presence of P300 (57.15% than the non-medicated group (28.57%, though the absence of these potentials were high among the group - 52.38%.

  20. CREB-binding protein, p300, butyrate, and Wnt signaling in colorectal cancer.

    Science.gov (United States)

    Bordonaro, Michael; Lazarova, Darina L

    2015-07-21

    This paper reviews the distinctive roles played by the transcriptional coactivators CREB-binding protein (CBP) and p300 in Wnt/β-catenin signaling and cell physiology in colorectal cancer (CRC). Specifically, we focus on the effects of CBP- and p300-mediated Wnt activity on (1) neoplastic progression; (2) the activities of butyrate, a breakdown product of dietary fiber, on cell signaling and colonic cell physiology; (3) the development of resistance to histone deacetylase inhibitors (HDACis), including butyrate and synthetic HDACis, in colonic cells; and (4) the physiology and number of cancer stem cells. Mutations of the Wnt/β-catenin signaling pathway initiate the majority of CRC cases, and we have shown that hyperactivation of this pathway by butyrate and other HDACis promotes CRC cell apoptosis. This activity by butyrate may in part explain the preventive action of fiber against CRC. However, individuals with a high-fiber diet may still develop neoplasia; therefore, resistance to the chemopreventive action of butyrate likely contributes to CRC. CBP or p300 may modify the ability of butyrate to influence colonic cell physiology since the two transcriptional coactivators affect Wnt signaling, and likely, its hyperactivation by butyrate. Also, CBP and p300 likely affect colonic tumorigenesis, as well as stem cell pluripotency. Improvement of CRC prevention and therapy requires a better understanding of the alterations in Wnt signaling and gene expression that underlie neoplastic progression, stem cell fate, and the development of resistance to butyrate and clinically relevant HDACis. Detailed knowledge of how CBP- and p300 modulate colonic cell physiology may lead to new approaches for anti-CRC prevention and therapeutics, particularly with respect to combinatorial therapy of CBP/p300 inhibitors with HDACis.

  1. N300, P300 and the emotional processing of visual stimuli.

    Science.gov (United States)

    Carretié, L; Iglesias, J; García, T; Ballesteros, M

    1997-08-01

    Two components of the ERPs elicited by emotional visual stimuli, N300 and P300, were investigated. The emotional charge is explained through two dimensions: arousal (relaxing (R) or activating (A)) and valence (attractive (+) or repulsive (-)). Stimuli were slides of nudes (A+), human remains (A-), landscapes (R), and buildings (neutral (N)). The peculiar structure of the stimuli, along with a distracting task which allowed us to disguise the real aim of the experiment, helped to avoid a sort of 'relevance-for-task effect', mainly related to cognitive processes, which could explain P300 reactions in response to emotional visual stimuli found in several experiments. The ERPs were recorded from 32 subjects at F3, Fz, F4, C3, Cz, C4, P3, Pz and P4. In contrast to previous studies, P300 did not show greater amplitudes in response to emotional stimuli than to N. N300 showed greater amplitudes in response to A+ at parietal sites, the greatest differences being those with respect to A-. No inter-hemispheric differences were found. N300 confirms its usefulness as a variable for studying emotional reactions to visual stimuli.

  2. Contralateral Noise Stimulation Delays P300 Latency in School-Aged Children.

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    Thalita Ubiali

    Full Text Available The auditory cortex modulates auditory afferents through the olivocochlear system, which innervates the outer hair cells and the afferent neurons under the inner hair cells in the cochlea. Most of the studies that investigated the efferent activity in humans focused on evaluating the suppression of the otoacoustic emissions by stimulating the contralateral ear with noise, which assesses the activation of the medial olivocochlear bundle. The neurophysiology and the mechanisms involving efferent activity on higher regions of the auditory pathway, however, are still unknown. Also, the lack of studies investigating the effects of noise on human auditory cortex, especially in peadiatric population, points to the need for recording the late auditory potentials in noise conditions. Assessing the auditory efferents in schoolaged children is highly important due to some of its attributed functions such as selective attention and signal detection in noise, which are important abilities related to the development of language and academic skills. For this reason, the aim of the present study was to evaluate the effects of noise on P300 responses of children with normal hearing.P300 was recorded in 27 children aged from 8 to 14 years with normal hearing in two conditions: with and whitout contralateral white noise stimulation.P300 latencies were significantly longer at the presence of contralateral noise. No significant changes were observed for the amplitude values.Contralateral white noise stimulation delayed P300 latency in a group of school-aged children with normal hearing. These results suggest a possible influence of the medial olivocochlear activation on P300 responses under noise condition.

  3. Neuroprotection against vascular dementia after acupuncture combined with donepezil hydrochloride: P300 event related potential

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    Qiang Liu

    2016-01-01

    Full Text Available Acupuncture can be used to treat various nervous system diseases. Here, 168 vascular dementia patients were orally administered donepezil hydrochloride alone (5 mg/day, once a day for 56 days, or combined with acupuncture at Shenting (DU24, Tianzhu (BL10, Sishencong (Extra, Yintang (Extra, Renzhong (DU26, Neiguan (PC6, Shenmen (HT7, Fengchi (GB20, Wangu (GB12 and Baihui (DU20 (once a day for 56 days. Compared with donepezil hydrochloride alone, P300 event related potential latency was shorter with an increased amplitude in patients treated with donepezil hydrochloride and acupuncture. Mini-Mental State Examination score was also higher. Moreover, these differences in P300 latency were identified within different infarcted regions in patients treated with donepezil hydrochloride and acupuncture. These findings indicate that acupuncture combined with donepezil hydrochloride noticeably improves cognitive function in patients with vascular dementia, and exerts neuroprotective effects against vascular dementia.

  4. P300 Event-Related Potentials in Children with Dyslexia

    Science.gov (United States)

    Papagiannopoulou, Eleni A.; Lagopoulos, Jim

    2017-01-01

    To elucidate the timing and the nature of neural disturbances in dyslexia and to further understand the topographical distribution of these, we examined entire brain regions employing the non-invasive auditory oddball P300 paradigm in children with dyslexia and neurotypical controls. Our findings revealed abnormalities for the dyslexia group in…

  5. Caracterização da normalidade do P300 em adultos jovens Standard characterization of P300 in young adults

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    Cíntia Santos Silva Machado

    2009-01-01

    Full Text Available OBJETIVO: Comparar com a literatura os valores de latência e amplitude de P300 em adultos jovens brasileiros saudáveis a fim de estabelecer um padrão normativo para futuros estudos, e verificar se os valores encontrados na amostra possuem correlação com o sexo, situação proposta na metodologia do exame e fases do ciclo menstrual. MÉTODOS: A amostra constou de 22 indivíduos saudáveis, sem queixa de desatenção, sem problemas neurológicos e auditivos, de 18 a 30 anos de idade. Todos os indivíduos foram submetidos à avaliação audiológica básica a fim de excluir aqueles com perda de audição. As respostas do P300 foram obtidas com equipamento AMPLAID MK22, de dois canais e em ambiente silencioso. RESULTADOS: Os resultados de latência encontrados na amostra, depois de comparados à literatura, enquadraram-se melhor nos intervalos de latência entre 220 e 380 ms. Somente os valores de amplitude foram influenciados pelas variáveis sexo e fase do ciclo menstrual. CONCLUSÃO: Os valores de latência da amostra não sofreram influência da variável sexo, ciclo menstrual e situação, e aproximaram-se com mais fidedignidade aos valores de intervalos de latência entre 220 e 380 ms. Contudo, os intervalos para a amplitude sofreram influência das variáveis sexo e ciclo menstrual, mas não se enquadraram adequadamente aos valores de intervalo encontrados na literatura.PURPOSE: To compare the values of latency and amplitude of P300 of healthy Brazilian young adults with the data available on the literature, in order to establish a normative standard for future studies. In addition, the aim was also to verify if the values found in the sample were correlated to gender, situation proposed in the methodology of the examination, and phase of menstrual cycle. METHODS: The sample consisted of 22 healthy individuals, without any attention complaints, neurological or auditory disorders, and with ages ranging from 18 to 30 years. All subjects

  6. Acute caffeine effect on repeatedly measured P300

    OpenAIRE

    Pan, Jingbo; Takeshita, Tatsuya; Morimoto, Kanehisa

    2000-01-01

    The acute effect of a single-dose of caffeine on the P300 event-related brain potential (ERP) was assessed in a study using a repeatedly presented auditory oddball button-press task. A dose (5mg/kg body-weight) of either caffeine or placebo lactose, dissolved in a cup of decaffeinated coffee, was administered double-blindly to coffee drinkers who had abstained from coffee for 24hrs, with the presentation order of the sessions counterbalanced and separated by 2–4 weeks. The caffeine-treatment ...

  7. SOA-dependent N400 and P300 semantic priming effects using pseudoword primes and a delayed lexical decision.

    Science.gov (United States)

    Hill, Holger; Ott, Friederike; Weisbrod, Matthias

    2005-06-01

    In a previous semantic priming study, we found a semantic distance effect on the lexical-decision-related P300 when SOA was short (150 ms) only, but no different RT and N400 priming effects between short and long (700 ms) SOAs. To investigate this further, we separated priming from lexical decision, using a delayed lexical decision in the present study. In the short SOA only, primed targets evoked an early peaking (approximately 480 ms) P300-like component, probably because the subject detected the semantic relationship implicitly. We hypothesize that in tasks requiring an immediate lexical decision, this early P300 and the later lexical decision P300 (approximately 600 ms) are additive. Secondly, we found both a direct and an indirect priming effect for both SOAs for the ERP amplitude of the N400 time window. However the N400 component itself was considerably larger in the long SOA than in the short SOA. We interpreted this finding as an ERP correlate for deeper semantic processing in the long SOA, due to increased attention that was provoked by the use of pseudoword primes. In contrast, in the short SOA, subjects might have used a shallowed semantic processing. N400, P300, and RTs are sensitive to semantic priming-but the modulation patterns are not consistent. This raises the question as to which variable reflects an immediate physiological correlate of semantic priming, and which variable reflects co-occurring processes associated with semantic priming.

  8. Detection of concealed information: combining a virtual mock crime with a P300-based Guilty Knowledge Test.

    Science.gov (United States)

    Hahm, Jinsun; Ji, Hyung Ki; Jeong, Je Young; Oh, Dong Hoon; Kim, Seok Hyeon; Sim, Kwee-Bo; Lee, Jang-Han

    2009-06-01

    The present study examined the detection of concealed information by combining a virtual mock crime with a P300-based Guilty Knowledge Test (GKT). Thirty-eight male participants were assigned to one of two groups: a guilty group that committed a mock crime to conceal a lost roll of bills in a computer simulation of a virtual library and an innocent group that was free from concealed information. Remarkably, the guilty group reacted with stronger P300 peak amplitudes to crime-relevant than to irrelevant stimuli, whereas the innocent group had similar P300 responses between crime-relevant and irrelevant stimuli. Deception-related cognitive activity based on P300 was revealed as a valid marker to differentiate between guilty and innocent. This is a highly empirical study combining a virtual mock crime with a P300-based GKT to detect deception. These results may be applied to a variety of areas dealing with not only forensic investigation but also health and medical research concerning deception as a symptom.

  9. Electroencephalography Amplitude Modulation Analysis for Automated Affective Tagging of Music Video Clips

    Science.gov (United States)

    Clerico, Andrea; Tiwari, Abhishek; Gupta, Rishabh; Jayaraman, Srinivasan; Falk, Tiago H.

    2018-01-01

    The quantity of music content is rapidly increasing and automated affective tagging of music video clips can enable the development of intelligent retrieval, music recommendation, automatic playlist generators, and music browsing interfaces tuned to the users' current desires, preferences, or affective states. To achieve this goal, the field of affective computing has emerged, in particular the development of so-called affective brain-computer interfaces, which measure the user's affective state directly from measured brain waves using non-invasive tools, such as electroencephalography (EEG). Typically, conventional features extracted from the EEG signal have been used, such as frequency subband powers and/or inter-hemispheric power asymmetry indices. More recently, the coupling between EEG and peripheral physiological signals, such as the galvanic skin response (GSR), have also been proposed. Here, we show the importance of EEG amplitude modulations and propose several new features that measure the amplitude-amplitude cross-frequency coupling per EEG electrode, as well as linear and non-linear connections between multiple electrode pairs. When tested on a publicly available dataset of music video clips tagged with subjective affective ratings, support vector classifiers trained on the proposed features were shown to outperform those trained on conventional benchmark EEG features by as much as 6, 20, 8, and 7% for arousal, valence, dominance and liking, respectively. Moreover, fusion of the proposed features with EEG-GSR coupling features showed to be particularly useful for arousal (feature-level fusion) and liking (decision-level fusion) prediction. Together, these findings show the importance of the proposed features to characterize human affective states during music clip watching. PMID:29367844

  10. Evidence suggesting superiority of visual (verbal) vs. auditory test presentation modality in the P300-based, Complex Trial Protocol for concealed autobiographical memory detection.

    Science.gov (United States)

    Rosenfeld, J Peter; Ward, Anne; Frigo, Vincent; Drapekin, Jesse; Labkovsky, Elena

    2015-04-01

    One group of participants received a series of city name stimuli presented on trials of the Complex Trial Protocol (CTP) version of a P300-based, concealed information test (CIT). Stimuli were presented on alternating trials in either auditory or visual presentation modality. In 1/7 of the trials the participant's home town (probe) repeatedly appeared in a series of 6 other (irrelevant) repeated city names. In both modalities, probe stimuli produced larger P300s than irrelevant stimuli. Visual stimuli produced shorter behavioral reaction times and P300 latencies, as well as larger P300 probe amplitudes, probe-irrelevant amplitude differences, and individual diagnostic accuracies than the same stimuli presented in the auditory modality. Possible reasons for these effects are discussed, and subject to discussed limitations, the applied conclusion reached is that in all CITs, visual presentation of stimuli, if feasible, should be preferentially used. Copyright © 2015 Elsevier B.V. All rights reserved.

  11. Comparison of speech-evoked v tone-evoked P300 response: implications for predicting outcomes in patients with traumatic brain injury.

    Science.gov (United States)

    Lew, H L; Slimp, J; Price, R; Massagli, T L; Robinson, L R

    1999-01-01

    The P300 response is a cognitive event-related potential recorded over the scalp. The tone-evoked P300 response has been used to predict outcomes of patients with brain injury. However, it may lead to false predictions because some normal people have a very small tone-evoked P300 response. It is hypothesized that speech may generate a more robust P300 response than tones. A voice-generator prototype was designed for this study. The rare speech signal was the word "mommy" in a female voice. The common signal was a 1000-Hz tone. Twenty-two normal adults (11 males, 11 females; age range, 18-60 yr) were tested for both speech-evoked and tone-evoked P300 responses. Speech-evoked P300 responses had significantly larger amplitudes (mean, 12.1 microV) than the tone-evoked responses (mean, 5.9 microV; P < 0.0001). Six subjects with brain injury were also tested using the same protocol: two subjects with severe brain injury showed no response to either stimulus. Both died within 1 wk after the testing. Although two subjects with moderate brain injury could not complete the testing because of agitated behavior, two other subjects with mild traumatic brain injury showed a larger speech-evoked than tone-evoked P300 response. The speech-evoked P300 response may be promising in predicting outcomes of patients with brain injury.

  12. Do Amplitudes of Water Level Fluctuations Affect the Growth and Community Structure of Submerged Macrophytes?

    Science.gov (United States)

    Wang, Mo-Zhu; Liu, Zheng-Yuan; Luo, Fang-Li; Lei, Guang-Chun; Li, Hong-Li

    2016-01-01

    Submerged macrophytes are subjected to potential mechanical stresses associated with fluctuating water levels in natural conditions. However, few experimental studies have been conducted to further understand the effects of water level fluctuating amplitude on submerged macrophyte species and their assemblages or communities. We designed a controlled experiment to investigate the responses of three submerged macrophyte species (Hydrilla verticillata, Ceratophyllum demersum and Elodea nuttallii) and their combinations in communities to three amplitudes (static, ± 30 cm, ± 60 cm) of water level fluctuations. Results showed that water level fluctuating amplitude had little effects on the community performance and the three tested species responded differently. H. verticillata exhibited more growth in static water and it was negatively affected by either of the water level fluctuations amplitude, however, growth parameters of H. verticillata in two fluctuating water level treatments (i.e., ± 30 cm, ± 60 cm) were not significantly different. On the other hand, the growth of C. demersum was not significantly correlated with different amplitude treatments. However, it became more abundant when water levels fluctuated. E. nuttallii was inhibited by the two fluctuating water level treatments, and was less in growth parameters compared to the other species especially in water level fluctuating conditions. The inherent differences in the adaptive capabilities of the tested species indicate that C. demersum or other species with similar responses may be dominant species to restore submerged macrophyte communities with great fluctuating water levels. Otherwise, H. verticillata, E. nuttallii or other species with similar responses could be considered for constructing the community in static water conditions.

  13. Do Amplitudes of Water Level Fluctuations Affect the Growth and Community Structure of Submerged Macrophytes?

    Directory of Open Access Journals (Sweden)

    Mo-Zhu Wang

    Full Text Available Submerged macrophytes are subjected to potential mechanical stresses associated with fluctuating water levels in natural conditions. However, few experimental studies have been conducted to further understand the effects of water level fluctuating amplitude on submerged macrophyte species and their assemblages or communities. We designed a controlled experiment to investigate the responses of three submerged macrophyte species (Hydrilla verticillata, Ceratophyllum demersum and Elodea nuttallii and their combinations in communities to three amplitudes (static, ± 30 cm, ± 60 cm of water level fluctuations. Results showed that water level fluctuating amplitude had little effects on the community performance and the three tested species responded differently. H. verticillata exhibited more growth in static water and it was negatively affected by either of the water level fluctuations amplitude, however, growth parameters of H. verticillata in two fluctuating water level treatments (i.e., ± 30 cm, ± 60 cm were not significantly different. On the other hand, the growth of C. demersum was not significantly correlated with different amplitude treatments. However, it became more abundant when water levels fluctuated. E. nuttallii was inhibited by the two fluctuating water level treatments, and was less in growth parameters compared to the other species especially in water level fluctuating conditions. The inherent differences in the adaptive capabilities of the tested species indicate that C. demersum or other species with similar responses may be dominant species to restore submerged macrophyte communities with great fluctuating water levels. Otherwise, H. verticillata, E. nuttallii or other species with similar responses could be considered for constructing the community in static water conditions.

  14. Stacked Autoencoders for the P300 Component Detection

    Directory of Open Access Journals (Sweden)

    Lukáš Vařeka

    2017-05-01

    Full Text Available Novel neural network training methods (commonly referred to as deep learning have emerged in recent years. Using a combination of unsupervised pre-training and subsequent fine-tuning, deep neural networks have become one of the most reliable classification methods. Since deep neural networks are especially powerful for high-dimensional and non-linear feature vectors, electroencephalography (EEG and event-related potentials (ERPs are one of the promising applications. Furthermore, to the authors' best knowledge, there are very few papers that study deep neural networks for EEG/ERP data. The aim of the experiments subsequently presented was to verify if deep learning-based models can also perform well for single trial P300 classification with possible application to P300-based brain-computer interfaces. The P300 data used were recorded in the EEG/ERP laboratory at the Department of Computer Science and Engineering, University of West Bohemia, and are publicly available. Stacked autoencoders (SAEs were implemented and compared with some of the currently most reliable state-of-the-art methods, such as LDA and multi-layer perceptron (MLP. The parameters of stacked autoencoders were optimized empirically. The layers were inserted one by one and at the end, the last layer was replaced by a supervised softmax classifier. Subsequently, fine-tuning using backpropagation was performed. The architecture of the neural network was 209-130-100-50-20-2. The classifiers were trained on a dataset merged from four subjects and subsequently tested on different 11 subjects without further training. The trained SAE achieved 69.2% accuracy that was higher (p < 0.01 than the accuracy of MLP (64.9% and LDA (65.9%. The recall of 58.8% was slightly higher when compared with MLP (56.2% and LDA (58.4%. Therefore, SAEs could be preferable to other state-of-the-art classifiers for high-dimensional event-related potential feature vectors.

  15. Evaluation of psychoacoustic tests and P300 event-related potentials in elderly patients with hyperhomocysteinemia.

    Science.gov (United States)

    Díaz-Leines, Sergio; Peñaloza-López, Yolanda R; Serrano-Miranda, Tirzo A; Flores-Ávalos, Blanca; Vidal-Ixta, Martha T; Jiménez-Herrera, Blanca

    2013-01-01

    Hyperhomocysteinemia as a risk factor for hearing impairment, neuronal damage and cognitive impairment in elderly patients is controversial and is limited by the small number of studies. The aim of this work was determine if elderly patients detected with hyperhomocysteinemia have an increased risk of developing abnormalities in the central auditory processes as compared with a group of patients with appropriate homocysteine levels, and to define the behaviour of psychoacoustic tests and long latency potentials (P300) in these patients. This was a cross-sectional, comparative and analytical study. We formed a group of patients with hyperhomocysteinemia and a control group with normal levels of homocysteine. All patients underwent audiometry, tympanometry and a selection of psychoacoustic tests (dichotic digits, low-pass filtered words, speech in noise and masking level difference), auditory evoked brainstem potentials and P300. Patients with hyperhomocysteinemia had higher values in the test of masking level difference than did the control group (P=.049) and more protracted latency in P300 (P=.000). Hyperhomocysteinemia is a factor that alters the central auditory functions. Alterations in psychoacoustic tests and disturbances in electrophysiological tests suggest that the central portion of the auditory pathway is affected in patients with hyperhomocysteinemia. Copyright © 2012 Elsevier España, S.L. All rights reserved.

  16. Phosphorylation of p300 by ATM controls the stability of NBS1

    Energy Technology Data Exchange (ETDEWEB)

    Jang, Eun Ryoung [Department of Molecular Science and Technology, College of Natural Sciences, Ajou University, Suwon 443-749 (Korea, Republic of); Choi, Jae Duk [Department of Molecular Science and Technology, College of Natural Sciences, Ajou University, Suwon 443-749 (Korea, Republic of); School of Biological Sciences, Seoul National University, Seoul 151 (Korea, Republic of); Jeong, Gajin [School of Biological Sciences, Seoul National University, Seoul 151 (Korea, Republic of); Lee, Jong-Soo, E-mail: jsjlee@mail.ajou.ac.kr [Department of Molecular Science and Technology, College of Natural Sciences, Ajou University, Suwon 443-749 (Korea, Republic of)

    2010-07-09

    Acetyltransferase, p300 is a transcriptional cofactor of signal-responsive transcriptional regulation. The surveillance kinase ataxia-telangiectasia mutated (ATM) plays a central role in regulation of a wide range of cellular DNA damage responses. Here, we investigated whether and how ATM mediates phosphorylation of p300 in response to DNA damage and how p300 phosphorylation is functionally linked to DNA damage. ATM-phosphorylated p300 in vitro and in vivo, in response to DNA damage. Phosphorylation of p300 proteins was observed upon {gamma}-irradiation in ATM{sup +} cells but not ATM{sup -} cells. Importantly, expression of nonphosphorylatable serine to alanine form of p300 (S106A) destabilized both p300 and NBS1 proteins, after DNA damage. These data demonstrate that ATM transduces a DNA damage signal to p300, and that ATM-dependent phosphorylation of p300 is required for stabilization of NBS1 proteins in response to DNA damage.

  17. Affects of spanwise heterogeneity and topographic height on Amplitude and Frequency modulation in channel flow turbulence

    Science.gov (United States)

    Awasthi, Ankit; Anderson, William

    2017-11-01

    We study the affects of spanwise heterogeneity on amplitude and frequency modulation of small-scale roughness-sublayer structures due to the passage of large-scale structures in the logarithmic region. Recent studies on amplitude and frequency modulation have prompted the development of a predictive model for near-wall dynamics. Such a model is of great interest to large-eddy simulation (LES), since near-wall processes are, by definition, never resolved. Here, we have used LES to model flows over a series of spanwise-heterogeneous topographies, where a domain with very long streamwise extent is used to ensure that very-large-scale motions are (or, can be) resolved. We report that the secondary flows globally disrupt the turbulence from channel physics, wherein the ``outer peak'' is either shifted to different wavelengths or nonexistent. This spectral density redistribution is assured to alter amplitude and frequency modulation rates within the roughness sublayer, and we present correlations of the small and large scales to demonstrate precisely that (following the wavelet decomposition, as outlined by). Thus, spanwise heterogeneity should be regarded as a model parameter in any rough-wall-generalized prognostic wall models. Air Force Office of Scientific Research, Grant # FA9550-14-1-0101.

  18. P300 Source Localization Contrasts in Body-Focused Repetitive Behaviors and Tic Disorders

    Science.gov (United States)

    Sauvé, Geneviève; O’Connor, Kieron P.; Blanchet, Pierre J.

    2017-01-01

    Tic disorders (TD) and body-focused repetitive behaviors (BFRB) have similar phenotypes that can be challenging to distinguish in clinical settings. Both disorders show high rates of comorbid psychiatric conditions, dysfunctional basal ganglia activity, atypical cortical functioning in the prefrontal and motor cortical regions, and cognitive deficits. Clinicians frequently confound the two disorders and it is important to find reliable objective methods to discriminate TD and BFRB. Neuropsychological tests and event-related potential (ERP) studies have yielded inconsistent results regarding a possible context updating deficit in TD and BFRB patients. However, most previous studies did not control for the presence of comorbid psychiatric condition and medication status, which might have confounded the findings reported to date. Hence, we aimed to investigate the psychophysiology of working memory using ERP in carefully screened TD and BFRB patients excluding those with psychiatric comorbidity and those taking psychoactive medication. The current study compared 12 TD patients, 12 BRFB patients, and 15 healthy control participants using a motor oddball task (button press). The P300 component was analyzed as an index of working memory functioning. Results showed that BFRB patients had decreased P300 oddball effect amplitudes over the right hemisphere compared to the TD and control groups. Clinical groups presented different scalp distributions compared to controls, which could represent a potential endophenotype candidate of BFRB and TD. PMID:28671557

  19. P300 Source Localization Contrasts in Body-Focused Repetitive Behaviors and Tic Disorders

    Directory of Open Access Journals (Sweden)

    Geneviève Sauvé

    2017-07-01

    Full Text Available Tic disorders (TD and body-focused repetitive behaviors (BFRB have similar phenotypes that can be challenging to distinguish in clinical settings. Both disorders show high rates of comorbid psychiatric conditions, dysfunctional basal ganglia activity, atypical cortical functioning in the prefrontal and motor cortical regions, and cognitive deficits. Clinicians frequently confound the two disorders and it is important to find reliable objective methods to discriminate TD and BFRB. Neuropsychological tests and event-related potential (ERP studies have yielded inconsistent results regarding a possible context updating deficit in TD and BFRB patients. However, most previous studies did not control for the presence of comorbid psychiatric condition and medication status, which might have confounded the findings reported to date. Hence, we aimed to investigate the psychophysiology of working memory using ERP in carefully screened TD and BFRB patients excluding those with psychiatric comorbidity and those taking psychoactive medication. The current study compared 12 TD patients, 12 BRFB patients, and 15 healthy control participants using a motor oddball task (button press. The P300 component was analyzed as an index of working memory functioning. Results showed that BFRB patients had decreased P300 oddball effect amplitudes over the right hemisphere compared to the TD and control groups. Clinical groups presented different scalp distributions compared to controls, which could represent a potential endophenotype candidate of BFRB and TD.

  20. Statistical Properties of Real-Time Amplitude Estimate of Harmonics Affected by Frequency Instability

    Science.gov (United States)

    Bellan, Diego; Pignari, Sergio A.

    2016-07-01

    This work deals with the statistical characterization of real-time digital measurement of the amplitude of harmonics affected by frequency instability. In fact, in modern power systems both the presence of harmonics and frequency instability are well-known and widespread phenomena mainly due to nonlinear loads and distributed generation, respectively. As a result, real-time monitoring of voltage/current frequency spectra is of paramount importance as far as power quality issues are addressed. Within this framework, a key point is that in many cases real-time continuous monitoring prevents the application of sophisticated algorithms to extract all the information from the digitized waveforms because of the required computational burden. In those cases only simple evaluations such as peak search of discrete Fourier transform are implemented. It is well known, however, that a slight change in waveform frequency results in lack of sampling synchronism and uncertainty in amplitude estimate. Of course the impact of this phenomenon increases with the order of the harmonic to be measured. In this paper an approximate analytical approach is proposed in order to describe the statistical properties of the measured magnitude of harmonics affected by frequency instability. By providing a simplified description of the frequency behavior of the windows used against spectral leakage, analytical expressions for mean value, variance, cumulative distribution function, and probability density function of the measured harmonics magnitude are derived in closed form as functions of waveform frequency treated as a random variable.

  1. Menopause Analytical Hormonal Correlate Outcome Study (MAHCOS) and the association to brain electrophysiology (P300) in a clinical setting.

    Science.gov (United States)

    Braverman, Eric R; Han, David; Oscar-Berman, Marlene; Karikh, Tatiana; Truesdell, Courtney; Dushaj, Kristina; Kreuk, Florian; Li, Mona; Stratton, Danielle; Blum, Kenneth

    2014-01-01

    Various studies have demonstrated that increased leptin levels and obesity are inversely related to cognitive decline in menopausal women. It is hypothesized that adiposity is inversely correlated with cognitive decline, as women with increased weight are less vulnerable to diminishing cognition. However, it is increasingly observed that menopausal women, even with increased adiposity, experience significant cognitive decline. Positron emission tomography (PET) has been used to analyze cognitive function and processing in menopausal women. Evoked potentials (P300) and neurophysiologic tests have validated brain metabolism in cognitively impaired patients. Post-hoc analyses of 796 female patients entering PATH Medical Clinic, between January 4, 2009 and February 24, 2013, were performed as part of the "Menopause Analytical Hormonal Correlate Outcome Study" (MAHCOS). Patient age range was 39-76 years (46.7 ± 0.2). P300 latency and amplitude correlated with a number of hormones: follicle stimulating hormone (FSH), luteinizing hormone (LH), estradiol, estrone, estriol, DHEA, pregnenolone, progesterone, free and total testosterone, thyroid stimulating hormone (TSH), Vitamins D 1.25 and D 25OH, leptin, and insulin-like growth factor-binding protein 3 (IGF-BP3). Corrected statistics did not reveal significant associations with P300 latency or amplitude for these hormones except for leptin plasma levels. However, factor analysis showed that FSH and LH clustered together with Vitamin D1.25 and Vitamin D25OH, P300 latency (not amplitude), and log leptin were found to be associated in the same cluster. Utilizing regression analysis, once age adjusted, leptin was the only significant predictor for latency or speed (p = 0.03) with an effect size of 0.23. Higher plasma leptin levels were associated with abnormal P300 speed (OR = 0.98). Our findings show a significant relationship of higher plasma leptin levels, potentially due to leptin resistance, and prolonged P300 latency

  2. [Dynamical examination of auditory event-related potentials P300 and sympathetic skin response in people with insomia of Sweet Dream Capsule therapy].

    Science.gov (United States)

    Zheng, Xu-Ning; Zhang, Ling-Ju; Liang, Hui; Chen, Wei; Zhu, Xiong-Chao; Yuan, Min; Liu, Yang

    2004-08-01

    To observe the change of auditory event-related potentials (P300) and sympathetic skin response (SSR) in people with insomia of Sweet Dream Capsule therapy. 30 patients meeting criteria for primary insomnia and 30 healthy volunteers with age matching controls were selected for the study. P300 and SSR were measured before treatment of Sweet Dream Capsule and at week 4 , 8 of the therapeutic course. That the change of P300 and SSR before and after treatment and their relations with PSQI were studied. Compared with those of normal controls, both P300 latency and SSR latency were prolonged while amplitude was decreased in patients with insomnia (P insomia of Sweet Dream Capsule therapy while SSR im proves significantly, and PSQI scores are ameliorated too.

  3. Children with chronic lung diseases have cognitive dysfunction as assessed by event-related potential (auditory P300) and Stanford-Binet IQ (SB-IV) test.

    Science.gov (United States)

    Kamel, Terez Boshra; Abd Elmonaem, Mahmoud Tarek; Khalil, Lobna Hamed; Goda, Mona Hamdy; Sanyelbhaa, Hossam; Ramzy, Mourad Alfy

    2016-10-01

    Chronic lung disease (CLD) in children represents a heterogeneous group of many clinico-pathological entities with risk of adverse impact of chronic or intermittent hypoxia. So far, few researchers have investigated the cognitive function in these children, and the role of auditory P300 in the assessment of their cognitive function has not been investigated yet. This study was designed to assess the cognitive functions among schoolchildren with different chronic pulmonary diseases using both auditory P300 and Stanford-Binet test. This cross-sectional study included 40 school-aged children who were suffering from chronic chest troubles other than asthma and 30 healthy children of similar age, gender and socioeconomic state as a control group. All subjects were evaluated through clinical examination, radiological evaluation and spirometry. Audiological evaluation included (basic otological examination, pure-tone, speech audiometry and immittancemetry). Cognitive function was assessed by auditory P300 and psychological evaluation using Stanford-Binet test (4th edition). Children with chronic lung diseases had significantly lower anthropometric measures compared to healthy controls. They had statistically significant lower IQ scores and delayed P300 latencies denoting lower cognitive abilities. Cognitive dysfunction correlated to severity of disease. P300 latencies were prolonged among hypoxic patients. Cognitive deficits in children with different chronic lung diseases were best detected using both Stanford-Binet test and auditory P300. P300 is an easy objective tool. P300 is affected early with hypoxia and could alarm subtle cognitive dysfunction.

  4. Evaluation of the Effect of Modafinil on Cognitive Functions in Patients with Idiopathic Hypersomnia with P300.

    Science.gov (United States)

    Yaman, Mehmet; Karakaya, Fatıma; Aydin, Tuğçe; Mayda, Hasan; Güzel, Hail İbrahim; Kayaalp, Dilek

    2015-06-27

    Modafinil is a well-tolerated psychostimulant drug with low addictive potential that is used to treat patients with narcolepsy and other excessive sleepiness. Whereas favorable effects of modafinil on cognitive functions have been shown in a large number of studies, there are very few reports presenting the effects of modafinil electrophysiologically. The aim of this study was to investigate the effects of modafinil on auditory P300 latency and amplitude electrophysiologically. Eighteen patients (age range: 16-48 years) with a diagnosis of idiopathic hypersomnia (IH) were included in the present study. As a standard treatment, 200 mg/day modafinil was administered to each patient. The P300 auditory test was performed for each patient before and at the end of 1 week of modafinil treatment. After 1 week of modafinil treatment, mean P300 latencies (at all electrode sites) were significantly lower than the latencies before the treatment (P values for Fz, Cz and Pz recording sites were 0.039, 0.002, and 0.004, respectively). An increase in the P300 amplitudes was detected only at the Fz recording site, but not at Cz or Pz recording sites (P values for Fz, Cz, and Pz recording sites were 0.014, 0.100, and 0.05, respectively). One week of modafinil treatment improved the cognitive performance, alertness, and executive functions in IH patients. Our electrophysiologically obtained findings provide further confirmation for previous reports in which modafinil has been shown to exert favorable effects on cognitive performance, alertness, and executive functions.

  5. SIK2 regulates fasting-induced PPARα activity and ketogenesis through p300.

    Science.gov (United States)

    Zhang, Zhen-Ning; Gong, Lulu; Lv, Sihan; Li, Jian; Tai, Xiaolu; Cao, Wenqi; Peng, Bing; Qu, Shen; Li, Weida; Zhang, Chao; Luan, Bing

    2016-03-17

    Fatty acid oxidation and subsequent ketogenesis is one of the major mechanisms to maintain hepatic lipid homeostasis under fasting conditions. Fasting hormone glucagon has been shown to stimulate ketone body production through activation of PPARα; however, the signal pathway linking glucagon to PPARα is largely undiscovered. Here we report that a SIK2-p300-PPARα cascade mediates glucagon's effect on ketogenesis. p300 interacts with PPARα through a conserved LXXLL motif and enhances its transcriptional activity. SIK2 disrupts p300-PPARα interaction by direct phosphorylation of p300 at Ser89, which in turn decreases PPARα-mediated ketogenic gene expression. Moreover, SIK2 phosphorylation defective p300 (p300 S89A) shows increased interaction with PPARα and abolishes suppression of SIK2 on PPARα-mediated ketogenic gene expression in liver. Taken together, our results unveil the signal pathway that mediates fasting induced ketogenesis to maintain hepatic lipid homeostasis.

  6. Cinnamoyl compounds as simple molecules that inhibit p300 histone acetyltransferase.

    Science.gov (United States)

    Costi, Roberta; Di Santo, Roberto; Artico, Marino; Miele, Gaetano; Valentini, Paola; Novellino, Ettore; Cereseto, Anna

    2007-04-19

    Cinnamoly compounds 1a-c and 2a-d were designed, synthesized, and in vitro tested as p300 inhibitors. At different degrees, all tested compounds were proven to inactivate p300, particularly, derivative 2c was the most active inhibitor, also showing high specificity for p300 as compared to other histone acetyltransferases. Most notably, 2c showed anti-acetylase activity in mammalian cells. These compounds represent a new class of synthetic inhibitors of p300, characterized by simple chemical structures.

  7. DRD2 A1 allele and P300 abnormalities in obesity

    Energy Technology Data Exchange (ETDEWEB)

    Blum, K. [Univ. of Texas Health Science Center, San Antonio, TX (United States)]|[PATH Foundation, Princeton, NJ (United States); Wood, R.; Sheridan, L.P.J. [Univ. of Texas Health Science Center, San Antonio, TX (United States)] [and others

    1994-09-01

    Obesity is a heterogeneous and prevalent disorder having both inheritable and environmental components. The role of the dopamine system in P300 has been implicated. We genotyped 193 neuropsychiatrically ill patients with and without comorbid drug and alcohol/abuse/dependence and obesity for the prevalence of the A1 allele of the DRD2 gene. We found a significant linear trend ({chi}{sup 2} = 40.4, df=1, p<0.00001) where the percent prevalence of the A1 increased with increasing polysubstance abuse. Where the A1 allele was found in 44% of 40 obese subjects, the A1 allele prevalence was found in as much as 91% of 11 obese subjects with comorbid polysubstance abuse. 53 obese subjects having a mean body weight (BMI) of 34.6{+-}8.2 were mapped for brain electrical activity and compared with 15 controls with a BMI of 22.3{+-}3.0 (P<.001). The P3 amplitude was significantly different (two tailed; t=3.24, df=16.2, P = 0.005), whereas P3 latency was not significant. Preliminarily, we found a significant decreased P3 amplitude correlated with parental polysubstance abuse (p=0.4) with prolongation of P3 latency correlated with the three risk factors of parental substance abuse, chemical dependency and carbohydrate bingeing (P<0.02). Finally, in a small sample, the A1 allele was present in 25% of probands having 0 risk compared to 66% in those obese subjects with any risk. This work represents the first electrophysiological data to implicate P3 abnormalities in a subset of obesity and further confirms an association of the DRD2 gene and a electrophysiological marker previously indicated to have predictive value in vulnerability to addictive behaviors.

  8. Recording visual evoked potentials and auditory evoked P300 at 9.4T static magnetic field.

    Science.gov (United States)

    Arrubla, Jorge; Neuner, Irene; Hahn, David; Boers, Frank; Shah, N Jon

    2013-01-01

    Simultaneous recording of electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) has shown a number of advantages that make this multimodal technique superior to fMRI alone. The feasibility of recording EEG at ultra-high static magnetic field up to 9.4 T was recently demonstrated and promises to be implemented soon in fMRI studies at ultra high magnetic fields. Recording visual evoked potentials are expected to be amongst the most simple for simultaneous EEG/fMRI at ultra-high magnetic field due to the easy assessment of the visual cortex. Auditory evoked P300 measurements are of interest since it is believed that they represent the earliest stage of cognitive processing. In this study, we investigate the feasibility of recording visual evoked potentials and auditory evoked P300 in a 9.4 T static magnetic field. For this purpose, EEG data were recorded from 26 healthy volunteers inside a 9.4 T MR scanner using a 32-channel MR compatible EEG system. Visual stimulation and auditory oddball paradigm were presented in order to elicit evoked related potentials (ERP). Recordings made outside the scanner were performed using the same stimuli and EEG system for comparison purposes. We were able to retrieve visual P100 and auditory P300 evoked potentials at 9.4 T static magnetic field after correction of the ballistocardiogram artefact using independent component analysis. The latencies of the ERPs recorded at 9.4 T were not different from those recorded at 0 T. The amplitudes of ERPs were higher at 9.4 T when compared to recordings at 0 T. Nevertheless, it seems that the increased amplitudes of the ERPs are due to the effect of the ultra-high field on the EEG recording system rather than alteration in the intrinsic processes that generate the electrophysiological responses.

  9. An Asynchronous P300 BCI With SSVEP-Based Control State Detection

    DEFF Research Database (Denmark)

    Panicker, Rajesh C.; Puthusserypady, Sadasivan; Sun, Ying

    2011-01-01

    In this paper, an asynchronous brain–computer interface (BCI) system combining the P300 and steady-state visually evoked potentials (SSVEPs) paradigms is proposed. The information transfer is accomplished using P300 event-related potential paradigm and the control state (CS) detection is achieved...

  10. Effect of the Green/Blue Flicker Matrix for P300-Based Brain-Computer Interface: An EEG-fMRI Study.

    Science.gov (United States)

    Ikegami, Shiro; Takano, Kouji; Wada, Makoto; Saeki, Naokatsu; Kansaku, Kenji

    2012-01-01

    The visual P300-brain-computer interface, a popular system for EEG-based BCI, utilizes the P300 event-related potential to select an icon arranged in a flicker matrix. In the conventional P300-BCI speller paradigm, white/gray luminance intensification of each row/column in the matrix is used. In an earlier study, we applied green/blue luminance and chromatic change in the P300-BCI system and reported that this luminance and chromatic flicker matrix was associated with better performance and greater subject comfort compared with the conventional white/gray luminance flicker matrix. In this study, we used simultaneous EEG-functional magnetic resonance imaging (fMRI) recordings to identify brain areas that were more enhanced in the green/blue flicker matrix than in the white/gray flicker matrix, as these may highlight areas devoted to improved P300-BCI performance. The peak of the positive wave in the EEG data was detected under both conditions, and the peak amplitudes were larger at the parietal and occipital electrodes, particularly in the late components, under the green/blue condition than under the white/gray condition. fMRI data showed activation in the bilateral parietal and occipital cortices, and these areas, particularly those in the right hemisphere, were more activated under the green/blue condition than under the white/gray condition. The parietal and occipital regions more involved in the green/blue condition were part of the areas devoted to conventional P300s. These results suggest that the green/blue flicker matrix was useful for enhancing the so-called P300 responses.

  11. An improved P300 pattern in BCI to catch user’s attention

    Science.gov (United States)

    Jin, Jing; Zhang, Hanhan; Daly, Ian; Wang, Xingyu; Cichocki, Andrzej

    2017-06-01

    Objective. Brain-computer interfaces (BCIs) can help patients who have lost control over most muscles but are still conscious and able to communicate or interact with the environment. One of the most popular types of BCI is the P300-based BCI. With this BCI, users are asked to count the number of appearances of target stimuli in an experiment. To date, the majority of visual P300-based BCI systems developed have used the same character or picture as the target for every stimulus presentation, which can bore users. Consequently, users attention may decrease or be negatively affected by adjacent stimuli. Approach. In this study, a new stimulus is presented to increase user concentration. Honeycomb-shaped figures with 1-3 red dots were used as stimuli. The number and the positions of the red dots in the honeycomb-shaped figure were randomly changed during BCI control. The user was asked to count the number of the dots presented in each flash instead of the number of times they flashed. To assess the performance of this new stimulus, another honeycomb-shaped stimulus, without red dots, was used as a control condition. Main results. The results showed that the honeycomb-shaped stimuli with red dots obtained significantly higher classification accuracies and information transfer rates (p  <  0.05) compared to the honeycomb-shaped stimulus without red dots. Significance. The results indicate that this proposed method can be a promising approach to improve the performance of the BCI system and can be an efficient method in daily application.

  12. Latency of auditory P300 correlates with self-control as measured by the Sixteen Personality Factor Questionnaire.

    Science.gov (United States)

    Lee, Heon-Jeong; Kim, Leen; Han, Chang-Su; Kim, Yong-Ku; Kim, Seung-Hyun; Lee, Min-Soo; Joe, Sook-Haeng; Jung, In-Kwa

    2005-08-01

    The reception, processing, and storage of information about experience define personality. The present study investigated the relationship between auditory event-related potentials (AERP) and personality traits. The AERP were recorded using a standard auditory oddball paradigm, and personality was evaluated by Cattell's Sixteen Personality Factor Questionnaire (16PF) in 20 healthy young male subjects. The P300 latency was found to be significantly associated with rule consciousness (factor G in the 16PF), perfectionism (factor Q3), and self-control (factor SC): it was negatively correlated with G score (r = -0.56, P = 0.01), Q3 score (r = -0.67, P = 0.001), and SC score (r = -0.65, P = 0.002). Moreover, the P300 amplitude and N100 amplitude were negatively correlated with reasoning (factor B; r = -0.46, P = 0.044; and r = -0.72, P = 0.002, respectively). These results indicate that the personality traits of self-control, perfectionism, high superego, and reasoning are related to information processing in the brain.

  13. Distinct neurophysiological mechanisms for manic and cycloid psychoses: evidence from a P300 study on manic patients.

    Science.gov (United States)

    Strik, W K; Ruchsow, M; Abele, S; Fallgatter, A J; Mueller, T J

    1998-12-01

    Pathologically asymmetrical P300 fields with right lateralized peaks were described in core schizophrenia as an expression of left-temporal functional deficits, while higher than normal amplitudes were found in cycloid psychosis. This latter finding appeared to be specific for cycloid psychosis and was explained by a generalized cerebral hyperarousal. Based on some psychopathological analogies with cycloid psychosis, and on the comparable pharmacological treatment of the acute episodes, a group of 19 manic patients was investigated immediately after remission and clinical stabilization of an episode. Patients with psychotic features were excluded to avoid overlaps with cycloid psychosis. Patients showed normal P300 amplitudes and no pathological asymmetries of the field, but more posterior positive areas compared to age- and sex-matched controls. This indicates that the neurophysiological changes underlying mania are different from both core schizophrenia and cycloid psychosis. Based on previous three-dimensional source location studies, this finding indicates that disinhibition due to reduced frontal lobe activity, and not hyperarousal, is the basic functional mechanism of manic disorders.

  14. The changing face of P300 BCIs: a comparison of stimulus changes in a P300 BCI involving faces, emotion, and movement.

    Directory of Open Access Journals (Sweden)

    Jing Jin

    Full Text Available One of the most common types of brain-computer interfaces (BCIs is called a P300 BCI, since it relies on the P300 and other event-related potentials (ERPs. In the canonical P300 BCI approach, items on a monitor flash briefly to elicit the necessary ERPs. Very recent work has shown that this approach may yield lower performance than alternate paradigms in which the items do not flash but instead change in other ways, such as moving, changing colour or changing to characters overlaid with faces.The present study sought to extend this research direction by parametrically comparing different ways to change items in a P300 BCI. Healthy subjects used a P300 BCI across six different conditions. Three conditions were similar to our prior work, providing the first direct comparison of characters flashing, moving, and changing to faces. Three new conditions also explored facial motion and emotional expression. The six conditions were compared across objective measures such as classification accuracy and bit rate as well as subjective measures such as perceived difficulty. In line with recent studies, our results indicated that the character flash condition resulted in the lowest accuracy and bit rate. All four face conditions (mean accuracy >91% yielded significantly better performance than the flash condition (mean accuracy = 75%.Objective results reaffirmed that the face paradigm is superior to the canonical flash approach that has dominated P300 BCIs for over 20 years. The subjective reports indicated that the conditions that yielded better performance were not considered especially burdensome. Therefore, although further work is needed to identify which face paradigm is best, it is clear that the canonical flash approach should be replaced with a face paradigm when aiming at increasing bit rate. However, the face paradigm has to be further explored with practical applications particularly with locked-in patients.

  15. A new hybrid BCI paradigm based on P300 and SSVEP.

    Science.gov (United States)

    Wang, Minjue; Daly, Ian; Allison, Brendan Z; Jin, Jing; Zhang, Yu; Chen, Lanlan; Wang, Xingyu

    2015-04-15

    P300 and steady-state visual evoked potential (SSVEP) approaches have been widely used for brain-computer interface (BCI) systems. However, neither of these approaches can work for all subjects. Some groups have reported that a hybrid BCI that combines two or more approaches might provide BCI functionality to more users. Hybrid P300/SSVEP BCIs have only recently been developed and validated, and very few avenues to improve performance have been explored. The present study compares an established hybrid P300/SSVEP BCIs paradigm to a new paradigm in which shape changing, instead of color changing, is adopted for P300 evocation to decrease the degradation on SSVEP strength. The result shows that the new hybrid paradigm presented in this paper yields much better performance than the normal hybrid paradigm. A performance increase of nearly 20% in SSVEP classification is achieved using the new hybrid paradigm in comparison with the normal hybrid paradigm. All the paradigms except the normal hybrid paradigm used in this paper obtain 100% accuracy in P300 classification. The new hybrid P300/SSVEP BCIs paradigm in which shape changing, instead of color changing, could obtain as high classification accuracy of SSVEP as the traditional SSVEP paradigm and could obtain as high classification accuracy of P300 as the traditional P300 paradigm. P300 did not interfere with the SSVEP response using the new hybrid paradigm presented in this paper, which was superior to the normal hybrid P300/SSVEP paradigm. Copyright © 2014 Elsevier B.V. All rights reserved.

  16. The use of event-related potential (P300) and neuropsychological testing to evaluate cognitive impairment in mild traumatic brain injury patients.

    Science.gov (United States)

    Nandrajog, Puneet; Idris, Zamzuri; Azlen, Wan Nor; Liyana, Alwani; Abdullah, Jafri Malin

    2017-01-01

    The aim of the study is to compare the amplitude and latency of the P300 event-related potential (ERP) component between a control group and patients after mild traumatic brain injury (mTBI) during 1-7 days (short duration) and 2-3 months (long duration), and to compare the outcome of neuropsychological tests between the long duration postinjury and control study groups. We studied responses to auditory stimulation in two main and one subgroups, namely the control healthy group (19 patients, both ERP and neuropsychology test done), the mTBI 1 group (17 patients, only ERP done within 7 days after injury), and the mTBI 2 subgroup (the 17 mTBI 1 patients in whom a repeated ERP together with neuropsychological testing was done at 2-3 months postinjury). Auditory evoked responses were studied with two different stimuli (standard and target stimuli), where the P300 amplitude and latency were recorded from three midline sites and results were compared between the groups, as were the neuropsychological test results. There was a significant prolongation of the target P300 latency values shown by the MBI 1 group measured at the central electrode when compared to the control group, which was also seen when the mTBI 1 and mTBI 2 groups were compared. The results of the P300 amplitude values measured at the frontal electrode showed the control group to have higher readings during the presentation of standard tones when compared to the mTBI 1 group. The mTBI 2 group performed better on some neuropsychological tests. The latency of P300 was significantly prolonged in early mTBI patients who improved over time, and the neuropsychological testing on mTBI 2 patients showed them to be comparable to the control group. The study indicates that ERP should be used as an additional modality of investigation in mTBI patients.

  17. An N100-P300 Spelling Brain-Computer Interface with Detection of Intentional Control

    Directory of Open Access Journals (Sweden)

    Hikaru Sato

    2016-12-01

    Full Text Available A brain-computer interface (BCI is a tool to communicate with a computer via brain signals without the user making any physical movements, thus enabling disabled people to communicate with their environment and with others. P300-based ERP spellers are a widely used spelling visual BCI using the P300 component of event-related potential (ERP. However, they have a technical problem in that at least 2 N flashes are required to present N characters. This prevents the improvement of accuracy and restricts the typing speed. To address this issue, we propose a method that uses N100 in addition to P300. We utilize novel stimulus images to detect the user’s gazing position by using N100. By using both P300 and N100, the proposed visual BCI reduces the number of flashes and improves the accuracy of the P300 speller. We also propose using N100 to classify non-control (NC and intentional control (IC states. In our experiments, the detection accuracy of N100 was significantly higher than that of P300 and the proposed method exhibited a higher information transfer rate (ITR than the P300 speller.

  18. Causality in the association between P300 and alpha event-related desynchronization.

    Directory of Open Access Journals (Sweden)

    Weiwei Peng

    Full Text Available Recent findings indicated that both P300 and alpha event-related desynchronization (α-ERD were associated, and similarly involved in cognitive brain functioning, e.g., attention allocation and memory updating. However, an explicit causal influence between the neural generators of P300 and α-ERD has not yet been investigated. In the present study, using an oddball task paradigm, we assessed the task effect (target vs. non-target on P300 and α-ERD elicited by stimuli of four sensory modalities, i.e., audition, vision, somatosensory, and pain, estimated their respective neural generators, and investigated the information flow among their neural generators using time-varying effective connectivity in the target condition. Across sensory modalities, the scalp topographies of P300 and α-ERD were similar and respectively maximal at parietal and occipital regions in the target condition. Source analysis revealed that P300 and α-ERD were mainly generated from posterior cingulate cortex and occipital lobe respectively. As revealed by time-varying effective connectivity, the cortical information was consistently flowed from α-ERD sources to P300 sources in the target condition for all four sensory modalities. All these findings showed that P300 in the target condition is modulated by the changes of α-ERD, which would be useful to explore neural mechanism of cognitive information processing in the human brain.

  19. Operation of a P300-based brain-computer interface by patients with spinocerebellar ataxia

    Directory of Open Access Journals (Sweden)

    Yoji Okahara

    Full Text Available Objective: We investigated the efficacy of a P300-based brain-computer interface (BCI for patients with spinocerebellar ataxia (SCA, which is often accompanied by cerebellar impairment. Methods: Eight patients with SCA and eight age- and gender-matched healthy controls were instructed to input Japanese hiragana characters using the P300-based BCI with green/blue flicker. All patients depended on some assistance in their daily lives (modified Rankin scale: mean 3.5. The chief symptom was cerebellar ataxia; no cognitive deterioration was present. A region-based, two-step P300-based BCI was used. During the P300 task, eight-channel EEG data were recorded, and a linear discriminant analysis distinguished the target from other nontarget regions of the matrix. Results: The mean online accuracy in BCI operation was 82.9% for patients with SCA and 83.2% for controls; no significant difference was detected. Conclusion: The P300-based BCI was operated successfully not only by healthy controls but also by individuals with SCA. Significance: These results suggest that the P300-based BCI may be applicable for patients with SCA. Keywords: BCI, BMI, P300, Visual stimuli, Spinocerebellar ataxia

  20. Connecting the P300 to the diagnosis and prognosis of unconscious patients

    Directory of Open Access Journals (Sweden)

    Ran Li

    2015-01-01

    Full Text Available The residual consciousness of unconscious patients can be detected by studying the P300, a wave among event-related potentials. Previous studies have applied tones, the subject′s name and other names as stimuli. However, the results were not satisfactory. In this study, we changed the constituent order of subjects′two-character names to create derived names. The subject′s derived names, together with tones and their own names, were used as auditory stimuli in event-related potential experiments. Healthy controls and unconscious patients were included in this study and made to listen to these auditory stimuli. In the two paradigms, a sine tone followed by the subject′s own name and the subject′s derived name followed by the subject′s own name were used as standard and deviant stimuli, respectively. The results showed that all healthy controls had the P300 using both paradigms, and that the P300 in the second paradigm had a longer latency and two peaks. All minimally conscious state patients had the P300 in the first paradigm and the majority of them had the P300 in the second paradigm. Most vegetative state patients had no P300. Patients who showed the P300 in the two paradigms had more residual consciousness, and patients with the two-peak P300 had a higher probability of awakening within a short time. Our experimental findings suggest that the P300 event-related potential could reflect the conscious state of unconscious patients.

  1. Cyclin D1 represses p300 transactivation through a cyclin-dependent kinase-independent mechanism.

    Science.gov (United States)

    Fu, Maofu; Wang, Chenguang; Rao, Mahadev; Wu, Xiaofang; Bouras, Toula; Zhang, Xueping; Li, Zhiping; Jiao, Xuanmao; Yang, Jianguo; Li, Anping; Perkins, Neil D; Thimmapaya, Bayar; Kung, Andrew L; Munoz, Alberto; Giordano, Antonio; Lisanti, Michael P; Pestell, Richard G

    2005-08-19

    Cyclin D1 encodes a regulatory subunit, which with its cyclin-dependent kinase (Cdk)-binding partner forms a holoenzyme that phosphorylates and inactivates the retinoblastoma protein. In addition to its Cdk binding-dependent functions, cyclin D1 regulates cellular differentiation in part by modifying several transcription factors and nuclear receptors. The molecular mechanism through which cyclin D1 regulates the function of transcription factors involved in cellular differentiation remains to be clarified. The histone acetyltransferase protein p300 is a co-integrator required for regulation of multiple transcription factors. Here we show that cyclin D1 physically interacts with p300 and represses p300 transactivation. We demonstrated further that the interaction of the two proteins occurs at the peroxisome proliferator-activated receptor gamma-responsive element of the lipoprotein lipase promoter in the context of the local chromatin structure. We have mapped the domains in p300 and cyclin D1 involved in this interaction. The bromo domain and cysteine- and histidine-rich domains of p300 were required for repression by cyclin D1. Cyclin D1 repression of p300 was independent of the Cdk- and retinoblastoma protein-binding domains of cyclin D1. Cyclin D1 inhibits histone acetyltransferase activity of p300 in vitro. Microarray analysis identified a signature of genes repressed by cyclin D1 and induced by p300 that promotes cellular differentiation and induces cell cycle arrest. Together, our results suggest that cyclin D1 plays an important role in cellular proliferation and differentiation through regulation of p300.

  2. Effects of caffeine and maltodextrin mouth rinsing on P300, brain imaging, and cognitive performance.

    Science.gov (United States)

    De Pauw, K; Roelands, B; Knaepen, K; Polfliet, M; Stiens, J; Meeusen, R

    2015-03-15

    Caffeine (CAF) and maltodextrin (MALT) mouth rinses (MR) improve exercise performance. The current experiment aims to determine the effect of CAF and MALT MR on cognitive performance and brain activity. Ten healthy male subjects (age 27 ± 3 yr) completed three experimental trials. Each trial included four Stroop tasks: two familiarization tasks, and one task before and one task after an MR period. The reaction time (in milliseconds) and accuracy (percent) of simple, congruent, and incongruent stimuli were assessed. Electroencephalography was applied throughout the experiment to record brain activity. The amplitudes and latencies of the P300 were determined during the Stroop tasks before and after the MR period. Subjects received MR with CAF (0.3 g/25 ml), MALT (1.6 g/25 ml), or placebo (PLAC) in a randomized, double-blind, crossover design. During MR, the brain imaging technique standardized low-resolution brain electromagnetic tomography was applied. Magnitude-based inferences showed that CAF MR is likely trivial (63.5%) and likely beneficial (36.4%) compared with PLAC MR, and compared with MALT MR likely beneficial to reaction time on incongruent stimuli (61.6%). Additionally, both the orbitofrontal and dorsolateral prefrontal cortex were activated only during CAF MR, potentially explaining the likely beneficial effect on reaction times. MALT MR increased brain activity only within the orbitofrontal cortex. However, this brain activation did not alter the reaction time. Furthermore, no significant differences in the accuracy of stimuli responses were observed between conditions. In conclusion, only CAF MR exerted a likely beneficial effect on reaction time due to the subsequent activation of both the orbitofrontal and dorsolateral prefrontal cortexes. Copyright © 2015 the American Physiological Society.

  3. Performance analysis of a Principal Component Analysis ensemble classifier for Emotiv headset P300 spellers.

    Science.gov (United States)

    Elsawy, Amr S; Eldawlatly, Seif; Taher, Mohamed; Aly, Gamal M

    2014-01-01

    The current trend to use Brain-Computer Interfaces (BCIs) with mobile devices mandates the development of efficient EEG data processing methods. In this paper, we demonstrate the performance of a Principal Component Analysis (PCA) ensemble classifier for P300-based spellers. We recorded EEG data from multiple subjects using the Emotiv neuroheadset in the context of a classical oddball P300 speller paradigm. We compare the performance of the proposed ensemble classifier to the performance of traditional feature extraction and classifier methods. Our results demonstrate the capability of the PCA ensemble classifier to classify P300 data recorded using the Emotiv neuroheadset with an average accuracy of 86.29% on cross-validation data. In addition, offline testing of the recorded data reveals an average classification accuracy of 73.3% that is significantly higher than that achieved using traditional methods. Finally, we demonstrate the effect of the parameters of the P300 speller paradigm on the performance of the method.

  4. SIK2 regulates fasting-induced PPARα activity and ketogenesis through p300

    OpenAIRE

    Zhen-Ning Zhang; Lulu Gong; Sihan Lv; Jian Li; Xiaolu Tai; Wenqi Cao; Bing Peng; Shen Qu; Weida Li; Chao Zhang; Bing Luan

    2016-01-01

    Fatty acid oxidation and subsequent ketogenesis is one of the major mechanisms to maintain hepatic lipid homeostasis under fasting conditions. Fasting hormone glucagon has been shown to stimulate ketone body production through activation of PPAR?; however, the signal pathway linking glucagon to PPAR? is largely undiscovered. Here we report that a SIK2-p300-PPAR? cascade mediates glucagon?s effect on ketogenesis. p300 interacts with PPAR? through a conserved LXXLL motif and enhances its transc...

  5. Dynamic bookmarking of primary response genes by p300 and RNA polymerase II complexes.

    Science.gov (United States)

    Byun, Jung S; Wong, Madeline M; Cui, Wenwu; Idelman, Gila; Li, Quentin; De Siervi, Adriana; Bilke, Sven; Haggerty, Cynthia M; Player, Audrey; Wang, Yong Hong; Thirman, Michael J; Kaberlein, Joseph J; Petrovas, Constantinos; Koup, Richard A; Longo, Dan; Ozato, Keiko; Gardner, Kevin

    2009-11-17

    Profiling the dynamic interaction of p300 with proximal promoters of human T cells identified a class of genes that rapidly coassemble p300 and RNA polymerase II (pol II) following mitogen stimulation. Several of these p300 targets are immediate early genes, including FOS, implicating a prominent role for p300 in the control of primary genetic responses. The recruitment of p300 and pol II rapidly transitions to the assembly of several elongation factors, including the positive transcriptional elongation factor (P-TEFb), the bromodomain-containing protein (BRD4), and the elongin-like eleven nineteen lysine-rich leukemia protein (ELL). However, transcription at many of these rapidly induced genes is transient, wherein swift departure of P-TEFb, BRD4, and ELL coincides with termination of transcriptional elongation. Unexpectedly, both p300 and pol II remain accumulated or "bookmarked" at the proximal promoter long after transcription has terminated, demarking a clear mechanistic separation between the recruitment and elongation phases of transcription in vivo. The bookmarked pol II is depleted of both serine-2 and serine-5 phosphorylation of its C-terminal domain and remains proximally positioned at the promoter for hours. Surprisingly, these p300/pol II bookmarked genes can be readily reactivated, and elongation factors can be reassembled by subsequent addition of nonmitogenic agents that, alone, have minimal effects on transcription in the absence of prior preconditioning by mitogen stimulation. These findings suggest that p300 is likely to play an important role in biological processes in which transcriptional bookmarking or preconditioning influences cellular growth and development through the dynamic priming of genes for response to rechallenge by secondary stimuli.

  6. Moving Away From Error-Related Potentials to Achieve Spelling Correction in P300 Spellers.

    Science.gov (United States)

    Mainsah, Boyla O; Morton, Kenneth D; Collins, Leslie M; Sellers, Eric W; Throckmorton, Chandra S

    2015-09-01

    P300 spellers can provide a means of communication for individuals with severe neuromuscular limitations. However, its use as an effective communication tool is reliant on high P300 classification accuracies ( > 70%) to account for error revisions. Error-related potentials (ErrP), which are changes in EEG potentials when a person is aware of or perceives erroneous behavior or feedback, have been proposed as inputs to drive corrective mechanisms that veto erroneous actions by BCI systems. The goal of this study is to demonstrate that training an additional ErrP classifier for a P300 speller is not necessary, as we hypothesize that error information is encoded in the P300 classifier responses used for character selection. We perform offline simulations of P300 spelling to compare ErrP and non-ErrP based corrective algorithms. A simple dictionary correction based on string matching and word frequency significantly improved accuracy (35-185%), in contrast to an ErrP-based method that flagged, deleted and replaced erroneous characters (-47-0%) . Providing additional information about the likelihood of characters to a dictionary-based correction further improves accuracy. Our Bayesian dictionary-based correction algorithm that utilizes P300 classifier confidences performed comparably (44-416%) to an oracle ErrP dictionary-based method that assumed perfect ErrP classification (43-433%).

  7. Memory timeline: Brain ERP C250 (not P300) is an early biomarker of short-term storage.

    Science.gov (United States)

    Chapman, Robert M; Gardner, Margaret N; Mapstone, Mark; Dupree, Haley M; Antonsdottir, Inga M

    2015-04-16

    Brain event-related potentials (ERPs) offer a quantitative link between neurophysiological activity and cognitive performance. ERPs were measured while young adults performed a task that required storing a relevant stimulus in short-term memory. Using principal components analysis, ERP component C250 (maximum at 250 ms post-stimulus) was extracted from a set of ERPs that were separately averaged for various task conditions, including stimulus relevancy and stimulus sequence within a trial. C250 was more positive in response to task-specific stimuli that were successfully stored in short-term memory. This relationship between C250 and short-term memory storage of a stimulus was confirmed by a memory probe recall test where the behavioral recall of a stimulus was highly correlated with its C250 amplitude. ERP component P300 (and its subcomponents of P3a and P3b, which are commonly thought to represent memory operations) did not show a pattern of activation reflective of storing task-relevant stimuli. C250 precedes the P300, indicating that initial short-term memory storage may occur earlier than previously believed. Additionally, because C250 is so strongly predictive of a stimulus being stored in short-term memory, C250 may provide a strong index of early memory operations. Copyright © 2015 Elsevier B.V. All rights reserved.

  8. Change in the P300 index - a pilot randomized controlled trial of low-frequency electrical stimulation of acupuncture points in middle-aged men and women.

    Science.gov (United States)

    Choi, Kwang-Ho; Kwon, O Sang; Cho, Seong Jin; Lee, Sanghun; Kang, Seok-Yun; Ryu, Yeon Hee

    2017-05-03

    The P300 is a major index used to evaluate improvements in brain function. Although a few studies have reported evaluating the effectiveness of manual acupuncture or electro-acupuncture by monitoring the P300, research in this field is not yet very active. The aim of this study was to investigate the effects of periodic low-frequency electrical stimulation applied to BL62 and KI6 on brain activity by analyzing the P300. The study was conducted as a randomized double-blind test of 55 subjects in their 50s, including 26 males and 29 females. Each subject received 12 sessions of stimulation over a one-month period. In each session, low-frequency electrical stimulation at an average of 24 μA and 2 Hz was applied to the acupuncture points BL62 and KI6, and event-related potentials (ERPs) were measured before the first session and after the last session of the electrical stimulation. The results of a chi-square test indicated that the double-blind test was conducted correctly. Compared to the Sham group, all the subjects in the Real stimulation group showed a tendency toward a decreasing P300 latency and increasing P300 amplitude after all 12 sessions of stimulation. In the women, the amplitude significantly increased at Fz, Fcz, Cz, Cpz, and Pz. With this experiment, the low-frequency electrical stimulation of two acupuncture points (BL62 and K16) was confirmed to have a positive influence on the prevention of natural cerebral aging. This study was registered at the Clinical Research Information Service (CRIS) of the National Research Institute of Health ( https://cris.nih.go.kr/cris/search/search_result_st01_en.jsp? , Registration Number: KCT0001940). The date of registration was June 9, 2016.

  9. [Impacts of acupuncture at Jing-well points on the differentiated meridians and temple-three-needle therapy on P300 of patients with early vascular cognitive impairment].

    Science.gov (United States)

    Li, Fei; Cai, Rong-Lin; Zhai, Liang; Gao, Kang; Yang, Jun

    2013-09-01

    To observe the efficacy on post-stroke mild cognitive impairment (MCI) treated with acupuncture at Jing-well points on the differentiated meridians and temple-three-needle therapy. Seventy-three of stroke patients were randomized into an acupuncture group (37 cases) and a conventional treatment group (36 cases). Twenty healthy aged people in physical examination were collected as a control group. In the acupuncture group, on the basis of the conventional treatment of internal medication, the acupuncture at Jing-well points on the differentiated meridians and temple-three-needle therapy were applied. In the conventional treatment group, no any therapy was used except the conventional treatment of internal medication. In the control group, no any intervention was adopted. Neuroscan Nuamps electroencephalogram recording analysis system was used to determine the event-related potentials P300, and the amplitude and mini mental state examination (MMSE) score was observed before and after treatment in both groups. After treatment, in the acupuncture group, P300 latent stage was shortened, and the amplitude and the score of MMSE were increased (P 0.05). Compared with the conventional treatment group, the differences in P300 latent stage, amplitude and MMSE score were remarkable in the acupuncture group (P acupuncture at Jing-well points on the differentiated meridians and temple-three-needle therapy improves the cognitive function of the patients with MCI.

  10. Influence of education level on design-induced N170 and P300 components of event related potentials in the human brain.

    Science.gov (United States)

    Begum, Tahamina; Reza, Faruque; Ahmed, Izmer; Abdullah, Jafri Malin

    2014-03-01

    Simple geometric and organic shapes and their arrangement are being used in different neuropsychology tests for the assessment of cognitive function, special memory and also for the therapy purpose in different patient groups. Until now there is no electrophysiological evidence of cognitive function determination for simple geometric, organic shapes and their arrangement. Then the main objective of this study is to know the cortical processing and amplitude, latency of visual induced N170 and P300 event related potential components on different geometric, organic shapes and their arrangement and different educational influence on it, which is worthwhile to know for the early and better treatment for those patient groups. While education influenced on cognitive function by using auditory oddball task, little is known about the influence of education on cognitive function induced by visual attention task in case of the choice of geometric, organic shapes and their arrangements. Using a 128-electrode sensor net, we studied the responses of the choice of the different geometric and organic shapes randomly in experiment 1 and their arrangements in experiment 2 in the high, medium and low education groups. In both experiments, subjects push the button "1" or "2" if like or dislike, respectively. Total 45 healthy subjects (15 in each group) were recruited. ERPs were measured from 11 electrode sites and analyzed to see the evoked N170/N240 and P300 ERP components. There were no differences between like and dislike in amplitudes even in latencies in every stimulus in both experiments. We fixed geometric shapes and organic shapes stimuli only, not like and dislike. Upon the stimulus types, N170 ERP component was found instead of N240, in occipito-temporal (T5, T6, O1 and O2) locations where the amplitude is the highest at O2 location and P300 was distributed in the central (Cz and Pz) locations in both experiments in all groups. In experiment 1, significant low amplitude and

  11. REHABILITATION OF PATIENTS WITH ENCEPHALOPATHY CAUSED BY ACUTE CHEMICAL AGENTS POISONING. P300 OF AUDITORY EVENT RELATED POTENTIALS AND ELECTROENCEPHALOGRAPHY

    Directory of Open Access Journals (Sweden)

    I. U. Berezina

    2014-01-01

    Full Text Available RELEVANCE. Patients with encephalopathy due to acute chemical agents poisoning have some brain functioning changes and a cognitive impairment during the rehabilitation program. These changes require correction of appropriate diagnostic protocol and treatment.AIM. The aim of this study was to estimate changes of electroencephalography (EEG and the P3 component of the event related potential (P300 ERP that are observed in patients with encephalopathy due to acute chemical agents poisoning during stage of rehabilitation.MATERIAL AND METHODS. The study was included 25 patients (age 37 (32; 51 poisoned different kind of neurotoxic substances (drugs, ethanol and complicated by toxic and hypoxic encephalopathy. They have got the treatment of encephalopathy by mexidol intravenously, mesodiencephalic modulation (MDM and hyperbaric oxygen therapy (HBOT. All patients were recoded EEG (electroencephalograph of “MBN” company, Russia and P300 ERP (“Neuron-Spectrum-5/EP” of “Neurosoft”, Russia according to the international recommendations of clinical neurophysiologists. Neuropsychological testing was used for the assessment of cognitive functions.RESULTS. There were some disturbances in primary electroencephalograms of all subjects. The follow-up EEG recording showed the main group of patients who had got the treatment (mexidol, MDM, HBOT had more often (11 patients the EEG improvements compared to the controls (1 patient. The main group had more rarely the EEG impairments compared to the control group. 6 patients of main group and 3 patients of controls did not have EEG changes during the follow-up EEG recordings. All controls and 17 patients of the main group patients had different cognitive disturbances. After the treatment 15 patients of the main group had improved on neuropsychological tests (MMSE, Munsterberg test, Schulte table, Number Connecting Test. They also had a decrease in the N200, P300 peak latency and an increase in the N200, P300

  12. [Effects of acupuncture of "Zhongchong" (PC 9) and "Yongquan" (KI 1) on P300 of event-related potentials in rats with vascular dementia].

    Science.gov (United States)

    Li, Fei; Cai, Rong-Lin; Wu, Sheng-Bing; Zhai, Liang; Gao, Kang

    2013-08-01

    To observe the effect of electroacupuncture (EA) stimulation of "Zhongchong" (PC 9) and "Yongquan" (KI 1) on P 300 of event-related potentials (ERPs) in rats with vascular dementia. A total of 48 Wistar rats were randomly divided into sham group (n = 12), model group (n = 12), EA group (n = 12) and medication group (n = 12). Vascular dementia model was established by occlusion of the bilateral vertebral arteries and cervical arteries. EA (1-2 mA, 2 Hz/20 Hz) was applied to bilateral "Zhongchong" (PC 9) and "Yongquan" (KI 1) for 15 min, once daily for 28 days. Rats of the medication group were treated by intragastric perfusion of Nimodipine (12 mg/kg), twice daily for 28 days. The rats' learning-memory ability was detected by step-down passive and active avoidance tests, and P 300 of ERPs detected by Neuroscan Nuamps system. Compared with the sham group, the reaction time and error times of learning performance and error times of memory performance as well as P 300 latency in the model group were significantly increased (P 0.05). EA of PC 9 and KI 1 can significantly improve the ability of learning and memory and the latency and amplitude of P 300 in rats with vascular dementia.

  13. P300 and Neuropsychological assessment in Mild Cognitive Impairment and Alzheimer Dementia

    Directory of Open Access Journals (Sweden)

    Mario eParra

    2012-12-01

    Full Text Available Only a small proportion of individuals with Mild Cognitive Impairment (MCI will convert to dementia. Methods currently available to identify risk for conversion do not combine enough sensitivity and specificity, which is even more problematic in low-educated populations. Current guidelines suggest the use of combined markers for dementia to enhance the prediction accuracy of assessment methods. The present study adhered to this proposal and investigated the sensitivity and specificity of the electrophysiological component P300 and standard neuropsychological tests to assess patients with Alzheimer’s disease (AD and MCI recruited from a low-income country. The neuropsychological battery comprised tests of memory, attention, language, praxis and executive functions. The P300 was recorded using a classical visual odd-ball paradigm. Three variables were found to achieve sensitivity and specificity values above 80% (Immediate and Delayed recall of word list – CERAD – and the latency of P300 for both MCI and AD. When they entered the model together (i.e., combined approach the sensitivity for MCI increased to 96% and the specificity remained high (80%. Our preliminary findings suggest that the combined use of sensitive neuropsychological tasks and the analysis of the P300 may offer a very useful method for the preclinical assessment of AD, particularly in populations with low socioeconomic and educational levels. Our results provide a platform and justification to employ more resources to convert P300 and related parameters into a biological marker for AD.

  14. P300 and neuropsychological assessment in mild cognitive impairment and Alzheimer dementia.

    Science.gov (United States)

    Parra, Mario A; Ascencio, Lindsay Lorena; Urquina, Hugo Fenando; Manes, Facundo; Ibáñez, Agustín M

    2012-01-01

    Only a small proportion of individuals with Mild Cognitive Impairment (MCI) will convert to dementia. Methods currently available to identify risk for conversion do not combine enough sensitivity and specificity, which is even more problematic in low-educated populations. Current guidelines suggest the use of combined markers for dementia to enhance the prediction accuracy of assessment methods. The present study adhered to this proposal and investigated the sensitivity and specificity of the electrophysiological component P300 and standard neuropsychological tests to assess patients with Alzheimer's disease (AD) and MCI recruited from a low-income country. The neuropsychological battery comprised tests of memory, attention, language, praxis, and executive functions. The P300 was recorded using a classical visual odd-ball paradigm. Three variables were found to achieve sensitivity and specificity values above 80% (Immediate and Delayed recall of word list - CERAD - and the latency of P300) for both MCI and AD. When they entered the model together (i.e., combined approach) the sensitivity for MCI increased to 96% and the specificity remained high (80%). Our preliminary findings suggest that the combined use of sensitive neuropsychological tasks and the analysis of the P300 may offer a very useful method for the preclinical assessment of AD, particularly in populations with low socioeconomic and educational levels. Our results provide a platform and justification to employ more resources to convert P300 and related parameters into a biological marker for AD.

  15. Haloperidol counteracts the ketamine-induced disruption of processing negativity, but not that of the P300 amplitude

    DEFF Research Database (Denmark)

    Oranje, Bob; Gispen-de Wied, Christine C; Westenberg, Herman G M

    2009-01-01

    Antagonists of the N-methyl-D-aspartate (NMDA) receptors such as ketamine, induce abnormalities in healthy subjects similar to those found in schizophrenia. However, recent evidence, suggests that most of the currently known NMDA antagonists have a broader receptor profile than originally thought....... Besides exerting an antagonistic effect on NMDA receptors, they have agonistic effects on dopamine D2 receptors. Can haloperidol (D2 antagonist) counteract the disruptive effects of ketamine on psychophysiological parameters of human attention? In a randomized, double-blind, placebo-controlled experiment...... 18 healthy male volunteers received placebo/placebo, placebo/ketamine (0.3 mg/kg i.v.) and haloperidol (2 mg)/ketamine (0.3 mg/kg i.v.) on three separate test days, after which they were tested in an auditory selective-attention paradigm. Haloperidol/ketamine reduced task performance compared...

  16. Haloperidol counteracts the ketamine-induced disruption of processing negativity, but not that of the P300 amplitude

    NARCIS (Netherlands)

    Oranje, Bob; Gispen-de Wied, Christine C.; Westenberg, Herman G. M.; Kemner, Chantal; Verbaten, Marinus N.; Kahn, Rene S.

    Antagonists of the N-methyl-D-aspartate (NMDA) receptors such as ketamine, induce abnormalities in healthy subjects similar to those found in schizophrenia. However, recent evidence, suggests that most of the currently known NMDA antagonists have a broader receptor profile than originally thought.

  17. Statistical examination of orbital elements affecting radial velocity semi-amplitude of host star in star-planet systems

    Science.gov (United States)

    Öztürk, O.; Erdem, A.

    2018-02-01

    Radial velocity semi-amplitude of the host star in a star-planet system is affected by four parameters: the orbital period and mass of the planet, mass of the host star, and orbital eccentricity. Statistical distribution of the orbital elements was examined using sensitive data from the spectroscopic orbital solutions of 737 systems given in the Exoplanet Orbit Database and Exoplanet Data Explorer (exoplanet.org). The orbital element distribution of the exoplanets was plotted in separate diagrams to highlight the basic features of the host star and planet in star-planet systems.

  18. The Performance of EEG-P300 Classification using Backpropagation Neural Networks

    Directory of Open Access Journals (Sweden)

    Arjon Turnip

    2013-12-01

    Full Text Available Electroencephalogram (EEG recordings signal provide an important function of brain-computer communication, but the accuracy of their classification is very limited in unforeseeable signal variations relating to artifacts. In this paper, we propose a classification method entailing time-series EEG-P300 signals using backpropagation neural networks to predict the qualitative properties of a subject’s mental tasks by extracting useful information from the highly multivariate non-invasive recordings of brain activity. To test the improvement in the EEG-P300 classification performance (i.e., classification accuracy and transfer rate with the proposed method, comparative experiments were conducted using Bayesian Linear Discriminant Analysis (BLDA. Finally, the result of the experiment showed that the average of the classification accuracy was 97% and the maximum improvement of the average transfer rate is 42.4%, indicating the considerable potential of the using of EEG-P300 for the continuous classification of mental tasks.

  19. Fusion of P300 and eye-tracker data for spelling using BCI2000

    Science.gov (United States)

    Kalika, Dmitry; Collins, Leslie; Caves, Kevin; Throckmorton, Chandra

    2017-10-01

    Objective. Various augmentative and alternative communication (AAC) devices have been developed in order to aid communication for individuals with communication disorders. Recently, there has been interest in combining EEG data and eye-gaze data with the goal of developing a hybrid (or ‘fused’) BCI (hBCI) AAC system. This work explores the effectiveness of a speller that fuses data from an eye-tracker and the P300 speller in order to create a hybrid P300 speller. Approach. This hybrid speller collects both eye-tracking and EEG data in parallel, and the user spells characters on the screen in the same way that they would if they were only using the P300 speller. Online and offline experiments were performed. The online experiments measured the performance of the speller for sixteen non-disabled participants, while the offline simulations were used to assess the robustness of the hybrid system. Main results. Online results showed that for fifteen non-disabled participants, using eye-gaze in a Bayesian framework with EEG data from the P300 speller improved accuracy (0.0163+/- 2.72 , 0.085+/- 0.111 , 0.080+/- 0.106 for estimated, medium and high variance configurations) and reduced the average number of flashes required to spell a character compared to the standard P300 speller that relies solely on EEG data (-53.27+/- 25.87 , -36.15+/- 19.3 , -18.85+/- 12.43 for estimated, medium and high variance configurations). Offline simulations indicate that the system provides more robust performance than a standalone eye gaze system. Significance. The results of this work on non-disabled participants shows the potential efficacy of hybrid P300 and eye-tracker speller. Further validation on the amyotrophic lateral sceloris population is needed to assess the benefit of this hybrid system.

  20. Brain fingerprinting classification concealed information test detects US Navy military medical information with P300

    Science.gov (United States)

    Farwell, Lawrence A.; Richardson, Drew C.; Richardson, Graham M.; Furedy, John J.

    2014-01-01

    A classification concealed information test (CIT) used the “brain fingerprinting” method of applying P300 event-related potential (ERP) in detecting information that is (1) acquired in real life and (2) unique to US Navy experts in military medicine. Military medicine experts and non-experts were asked to push buttons in response to three types of text stimuli. Targets contain known information relevant to military medicine, are identified to subjects as relevant, and require pushing one button. Subjects are told to push another button to all other stimuli. Probes contain concealed information relevant to military medicine, and are not identified to subjects. Irrelevants contain equally plausible, but incorrect/irrelevant information. Error rate was 0%. Median and mean statistical confidences for individual determinations were 99.9% with no indeterminates (results lacking sufficiently high statistical confidence to be classified). We compared error rate and statistical confidence for determinations of both information present and information absent produced by classification CIT (Is a probe ERP more similar to a target or to an irrelevant ERP?) vs. comparison CIT (Does a probe produce a larger ERP than an irrelevant?) using P300 plus the late negative component (LNP; together, P300-MERMER). Comparison CIT produced a significantly higher error rate (20%) and lower statistical confidences: mean 67%; information-absent mean was 28.9%, less than chance (50%). We compared analysis using P300 alone with the P300 + LNP. P300 alone produced the same 0% error rate but significantly lower statistical confidences. These findings add to the evidence that the brain fingerprinting methods as described here provide sufficient conditions to produce less than 1% error rate and greater than 95% median statistical confidence in a CIT on information obtained in the course of real life that is characteristic of individuals with specific training, expertise, or organizational

  1. Effects of wi-fi signals on the p300 component of event-related potentials during an auditory hayling task.

    Science.gov (United States)

    Papageorgiou, Charalabos C; Hountala, Chrissanthi D; Maganioti, Argiro E; Kyprianou, Miltiades A; Rabavilas, Andreas D; Papadimitriou, George N; Capsalis, Christos N

    2011-06-01

    The P300 component of event-related potentials (ERPs) is believed to index attention and working memory (WM) operation of the brain. The present study focused on the possible gender-related effects of Wi-Fi (Wireless Fidelity) electromagnetic fields (EMF) on these processes. Fifteen male and fifteen female subjects, matched for age and education level, were investigated while performing a modified version of the Hayling Sentence Completion test adjusted to induce WM. ERPs were recorded at 30 scalp electrodes, both without and with the exposure to a Wi-Fi signal. P300 amplitude values at 18 electrodes were found to be significantly lower in the response inhibition condition than in the response initiation and baseline conditions. Independent of the above effect, within the response inhibition condition there was also a significant gender X radiation interaction effect manifested at 15 leads by decreased P300 amplitudes of males in comparison to female subjects only at the presence of EMF. In conclusion, the present findings suggest that Wi-Fi exposure may exert gender-related alterations on neural activity associated with the amount of attentional resources engaged during a linguistic test adjusted to induce WM.

  2. Brain-computer interface using P300 and virtual reality: A gaming approach for treating ADHD

    DEFF Research Database (Denmark)

    Rohani, Darius Adam; Sørensen, Helge Bjarup Dissing; Puthusserypady, Sadasivan

    2014-01-01

    This paper presents a novel brain-computer interface (BCI) system aiming at the rehabilitation of attention-deficit/hyperactive disorder in children. It uses the P300 potential in a series of feedback games to improve the subjects' attention. We applied a support vector machine (SVM) using temporal...... and template-based features to detect these P300 responses. In an experimental setup using five subjects, an average error below 30% was achieved. To make it more challenging the BCI system has been embedded inside an immersive 3D virtual reality (VR) classroom with simulated distractions, which was created...

  3. No Time for Dead Time: Use the Fourier Amplitude Differences to Normalize Dead-time-affected Periodograms

    Science.gov (United States)

    Bachetti, Matteo; Huppenkothen, Daniela

    2018-02-01

    Dead time affects many of the instruments used in X-ray astronomy, by producing a strong distortion in power density spectra. This can make it difficult to model the aperiodic variability of the source or look for quasi-periodic oscillations. Whereas in some instruments a simple a priori correction for dead-time-affected power spectra is possible, this is not the case for others such as NuSTAR, where the dead time is non-constant and long (∼2.5 ms). Bachetti et al. (2015) suggested the cospectrum obtained from light curves of independent detectors within the same instrument as a possible way out, but this solution has always only been a partial one: the measured rms was still affected by dead time because the width of the power distribution of the cospectrum was modulated by dead time in a frequency-dependent way. In this Letter, we suggest a new, powerful method to normalize dead-time-affected cospectra and power density spectra. Our approach uses the difference of the Fourier amplitudes from two independent detectors to characterize and filter out the effect of dead time. This method is crucially important for the accurate modeling of periodograms derived from instruments affected by dead time on board current missions like NuSTAR and Astrosat, but also future missions such as IXPE.

  4. CRE promoter sites modulate alternative splicing via p300-mediated histone acetylation

    Czech Academy of Sciences Publication Activity Database

    Dušková, Eva; Hnilicová, Jarmila; Staněk, David

    2014-01-01

    Roč. 11, č. 7 (2014), s. 865-874 ISSN 1547-6286 R&D Projects: GA ČR(CZ) GBP305/12/G034 Institutional support: RVO:68378050 Keywords : alternative splicing * fibronectin * p300 * histone acetylation * promoter Subject RIV: EB - Gene tics ; Molecular Biology Impact factor: 4.974, year: 2014

  5. Word-level language modeling for P300 spellers based on discriminative graphical models

    Science.gov (United States)

    Delgado Saa, Jaime F.; de Pesters, Adriana; McFarland, Dennis; Çetin, Müjdat

    2015-04-01

    Objective. In this work we propose a probabilistic graphical model framework that uses language priors at the level of words as a mechanism to increase the performance of P300-based spellers. Approach. This paper is concerned with brain-computer interfaces based on P300 spellers. Motivated by P300 spelling scenarios involving communication based on a limited vocabulary, we propose a probabilistic graphical model framework and an associated classification algorithm that uses learned statistical models of language at the level of words. Exploiting such high-level contextual information helps reduce the error rate of the speller. Main results. Our experimental results demonstrate that the proposed approach offers several advantages over existing methods. Most importantly, it increases the classification accuracy while reducing the number of times the letters need to be flashed, increasing the communication rate of the system. Significance. The proposed approach models all the variables in the P300 speller in a unified framework and has the capability to correct errors in previous letters in a word, given the data for the current one. The structure of the model we propose allows the use of efficient inference algorithms, which in turn makes it possible to use this approach in real-time applications.

  6. Spatial Filter Feature Extraction Methods for P300 BCI Speller: A Comparison

    DEFF Research Database (Denmark)

    Chiou, Eleni; Puthusserypady, Sadasivan

    2017-01-01

    classifiers, namely the Support Vector Machine (SVM) and Fisher’s Linear Discriminant Analysis (FLDA). In addition, it is shown that the incorporation of some prior knowledge regarding the location of P300 elicitation on the scalp can reduce the computational load while maintaining or even improving...

  7. Adaptation in P300 braincomputer interfaces: A two-classifier cotraining approach

    DEFF Research Database (Denmark)

    Panicker, Rajesh C.; Sun, Ying; Puthusserypady, Sadasivan

    2010-01-01

    A cotraining-based approach is introduced for constructing high-performance classifiers for P300-based braincomputer interfaces (BCIs), which were trained from very little data. It uses two classifiers: Fishers linear discriminant analysis and Bayesian linear discriminant analysis progressively...

  8. Transgenic Mice Expressing an Inhibitory Truncated Form of p300 Exhibit Long-Term Memory Deficits

    Science.gov (United States)

    Oliveira, Ana M. M.; Wood, Marcelo A.; McDonough, Conor B.; Abel, Ted

    2007-01-01

    The formation of many forms of long-term memory requires several molecular mechanisms including regulation of gene expression. The mechanisms directing transcription require not only activation of individual transcription factors but also recruitment of transcriptional coactivators. CBP and p300 are transcriptional coactivators that interact with…

  9. Inhibition of MITF transcriptional activity independent of targeting p300/CBP coactivators

    Czech Academy of Sciences Publication Activity Database

    Vachtenheim, J.; Šestáková, B.; Tuháčková, Zdena

    2007-01-01

    Roč. 20, č. 1 (2007), s. 41-51 ISSN 0893-5785 Grant - others:GA MZd(CZ) NR8026 Institutional research plan: CEZ:AV0Z50520514 Keywords : microphthalmia-associated transcription factor * E1A * p300 * tyrosinase * melanoma Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 4.288, year: 2007

  10. CRE promoter sites modulate alternative splicing via p300-mediated histone acetylation

    Czech Academy of Sciences Publication Activity Database

    Dušková, E.; Hnilicová, Jarmila; Staněk, D.

    2014-01-01

    Roč. 11, č. 7 (2014), s. 1-10 ISSN 1547-6286 R&D Projects: GA ČR(CZ) GBP305/12/G034 Grant - others:Charles University Prague(CZ) 274111 Institutional support: RVO:61388971 Keywords : alternative splicing * fibronectin * p300 Subject RIV: EE - Microbiology, Virology Impact factor: 4.974, year: 2014

  11. CRE promoter sites modulate alternative splicing via p300-mediated histone acetylation

    Czech Academy of Sciences Publication Activity Database

    Dušková, Eva; Hnilicová, Jarmila; Staněk, David

    2014-01-01

    Roč. 11, č. 7 (2014), s. 865-874 ISSN 1547-6286 R&D Projects: GA ČR(CZ) GBP305/12/G034 Institutional support: RVO:68378050 Keywords : alternative splicing * fibronectin * p300 * histone acetylation * promoter Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 4.974, year: 2014

  12. Effects of ZNF804A on auditory P300 response in schizophrenia.

    LENUS (Irish Health Repository)

    O'Donoghue, T

    2014-01-01

    The common variant rs1344706 within the zinc-finger protein gene ZNF804A has been strongly implicated in schizophrenia (SZ) susceptibility by a series of recent genetic association studies. Although associated with a pattern of altered neural connectivity, evidence that increased risk is mediated by an effect on cognitive deficits associated with the disorder has been equivocal. This study investigated whether the same ZNF804A risk allele was associated with variation in the P300 auditory-evoked response, a cognitively relevant putative endophenotype for SZ. We compared P300 responses in carriers and noncarriers of the ZNF804A risk allele genotype groups in Irish patients and controls (n=97). P300 response was observed to vary according to genotype in this sample, such that risk allele carriers showed relatively higher P300 response compared with noncarriers. This finding accords with behavioural data reported by our group and others. It is also consistent with the idea that ZNF804A may have an impact on cortical efficiency, reflected in the higher levels of activations required to achieve comparable behavioural accuracy on the task used.

  13. Sleep inertia and autonomic effects on post-nap P300 event-related potential.

    Science.gov (United States)

    Takahashi, M; Arito, H

    1998-10-01

    The objective of this study was to examine the relationship between post-nap measures of alertness and performance and non-rapid eye movement (NREM) sleep and parasympathetic activity during brief naps. Thirty healthy subjects were randomly assigned to no-nap, 15-min, and 45-min nap conditions after normal home sleep at prior night. Each nap was taken after lunch and monitored by electroencephalogram (EEG), electromyogram, electrooculogram, and electrocardiogram (ECG). Deep NREM sleep was quantified by EEG delta power density and the parasympathetic activity was quantified by the ECG high-frequency (HF) component of R-R interval variability during the 15- and 45-min naps. The P300 event-related potential, subjective sleepiness, and performance on a 90-min English transcription task were measured 30 min and 3 hr after the naps and tested for their association with the EEG and ECG measures. A positive correlation was obtained between EEG delta power density during the naps and P300 latency 30 min after the naps (r = 0.476, p sleep inertia prolongs the P300 latency immediately after the naps, and that the parasympathetic predominance during the naps may improve subsequent alertness as assessed by the shortened P300 latency 3 hr after the naps.

  14. Activation of Basal Gluconeogenesis by Coactivator p300 Maintains Hepatic Glycogen Storage

    Science.gov (United States)

    Cao, Jia; Meng, Shumei; Ma, Anlin; Radovick, Sally; Wondisford, Fredric E.

    2013-01-01

    Because hepatic glycogenolysis maintains euglycemia during early fasting, proper hepatic glycogen synthesis in the fed/postprandial states is critical. It has been known for decades that gluconeogenesis is essential for hepatic glycogen synthesis; however, the molecular mechanism remains unknown. In this report, we show that depletion of hepatic p300 reduces glycogen synthesis, decreases hepatic glycogen storage, and leads to relative hypoglycemia. We previously reported that insulin suppressed gluconeogenesis by phosphorylating cAMP response element binding protein-binding protein (CBP) at S436 and disassembling the cAMP response element-binding protein-CBP complex. However, p300, which is closely related to CBP, lacks the corresponding S436 phosphorylation site found on CBP. In a phosphorylation-competent p300G422S knock-in mouse model, we found that mutant mice exhibited reduced hepatic glycogen content and produced significantly less glycogen in a tracer incorporation assay in the postprandial state. Our study demonstrates the important and unique role of p300 in glycogen synthesis through maintaining basal gluconeogenesis. PMID:23770612

  15. The p300 event-related potential technique for libido assessment in women with hypoactive sexual desire disorder.

    Science.gov (United States)

    Vardi, Yoram; Sprecher, Elliot; Gruenwald, Ilan; Yarnitsky, David; Gartman, Irena; Granovsky, Yelena

    2009-06-01

    There is a need for an objective technique to assess the degree of hypoactive sexual desire disorder (HSDD). Recently, we described such a methodology (event-related potential technique [ERP]) based on recording of p300 electroencephalography (EEG) waves elicited by auditory stimuli during synchronous exposure to erotic films. To compare sexual interest of sexually healthy women to females with sexual dysfunction (FSD) using ERP, and to explore whether FSD women with and without HSDD would respond differently to two different types of erotic stimuli-films containing (I) or not containing (NI) sexual intercourse scenes. Twenty-two women with FSD, of which nine had HSDD only, and 30 sexually healthy women were assessed by the Female Sexual Functioning Index. ERP methodology was performed applying erotic NI or I films. Significant differences in percent of auditory p300 amplitude reduction (PR) in response to erotic stimuli within and between all three groups for each film type. PRs to each film type were similar in sexually healthy women (60.6% +/- 40.3 (NI) and 51.7% +/- 32.3 [I]), while in women with FSD, reduction was greater when viewing the NI vs. I erotic films (71.4% +/- 41.0 vs. 37.7% +/- 45.7; P = 0.0099). This difference was mainly due to the greater PR of the subgroup with HSDD in response to NI vs. I films (77.7% +/- 46.7 vs. 17.0% +/- 50.3) than in the FSD women without HSDD group or the sexually healthy women (67.5% +/- 38.7 vs. 50.4% +/- 39.4 respectively), P = 0.0084. For comparisons, we used the mixed-model one-way analysis of variance. Differences in neurophysiological response patterns between sexually healthy vs. sexually dysfunctional females may point to a specific inverse discrimination ability for sexually relevant information in the subgroup of women with HSDD. These findings suggest that the p300 ERP technique could be used as an objective quantitative tool for libido assessment in sexually dysfunctional women.

  16. Functional Brain Connectivity as a New Feature for P300 Speller.

    Directory of Open Access Journals (Sweden)

    Aya Kabbara

    Full Text Available The brain is a large-scale complex network often referred to as the "connectome". Cognitive functions and information processing are mainly based on the interactions between distant brain regions. However, most of the 'feature extraction' methods used in the context of Brain Computer Interface (BCI ignored the possible functional relationships between different signals recorded from distinct brain areas. In this paper, the functional connectivity quantified by the phase locking value (PLV was introduced to characterize the evoked responses (ERPs obtained in the case of target and non-targets visual stimuli. We also tested the possibility of using the functional connectivity in the context of 'P300 speller'. The proposed approach was compared to the well-known methods proposed in the state of the art of "P300 Speller", mainly the peak picking, the area, time/frequency based features, the xDAWN spatial filtering and the stepwise linear discriminant analysis (SWLDA. The electroencephalographic (EEG signals recorded from ten subjects were analyzed offline. The results indicated that phase synchrony offers relevant information for the classification in a P300 speller. High synchronization between the brain regions was clearly observed during target trials, although no significant synchronization was detected for a non-target trial. The results showed also that phase synchrony provides higher performance than some existing methods for letter classification in a P300 speller principally when large number of trials is available. Finally, we tested the possible combination of both approaches (classical features and phase synchrony. Our findings showed an overall improvement of the performance of the P300-speller when using Peak picking, the area and frequency based features. Similar performances were obtained compared to xDAWN and SWLDA when using large number of trials.

  17. Dual roles of p300 in chromatin assembly and transcriptional activation in cooperation with nucleosome assembly protein 1 in vitro.

    Science.gov (United States)

    Asahara, Hiroshi; Tartare-Deckert, Sophie; Nakagawa, Takeya; Ikehara, Tsuyoshi; Hirose, Fumiko; Hunter, Tony; Ito, Takashi; Montminy, Marc

    2002-05-01

    In a yeast two-hybrid screen to identify proteins that bind to the KIX domain of the coactivator p300, we obtained cDNAs encoding nucleosome assembly protein 1 (NAP-1), a 60-kDa histone H2A-H2B shuttling protein that promotes histone deposition. p300 associates preferentially with the H2A-H2B-bound form of NAP-1 rather than with the unbound form of NAP-1. Formation of NAP-1-p300 complexes was found to increase during S phase, suggesting a potential role for p300 in chromatin assembly. In micrococcal nuclease and supercoiling assays, addition of p300 promoted efficient chromatin assembly in vitro in conjunction with NAP-1 and ATP-utilizing chromatin assembly and remodeling factor; this effect was dependent in part on the intrinsic histone acetyltransferase activity of p300. Surprisingly, NAP-1 potently inhibited acetylation of core histones by p300, suggesting that efficient assembly requires acetylation of either NAP-1 or p300 itself. As p300 acted cooperatively with NAP-1 in stimulating transcription from a chromatin template in vitro, our results suggest a dual role of NAP-1-p300 complexes in promoting chromatin assembly and transcriptional activation.

  18. Comparison of Classification Methods for P300 Brain-Computer Interface on Disabled Subjects

    Directory of Open Access Journals (Sweden)

    Nikolay V. Manyakov

    2011-01-01

    Full Text Available We report on tests with a mind typing paradigm based on a P300 brain-computer interface (BCI on a group of amyotrophic lateral sclerosis (ALS, middle cerebral artery (MCA stroke, and subarachnoid hemorrhage (SAH patients, suffering from motor and speech disabilities. We investigate the achieved typing accuracy given the individual patient's disorder, and how it correlates with the type of classifier used. We considered 7 types of classifiers, linear as well as nonlinear ones, and found that, overall, one type of linear classifier yielded a higher classification accuracy. In addition to the selection of the classifier, we also suggest and discuss a number of recommendations to be considered when building a P300-based typing system for disabled subjects.

  19. Brain-computer interface using P300 and virtual reality: a gaming approach for treating ADHD.

    Science.gov (United States)

    Rohani, Darius Adam; Sorensen, Helge B D; Puthusserypady, Sadasivan

    2014-01-01

    This paper presents a novel brain-computer interface (BCI) system aiming at the rehabilitation of attention-deficit/hyperactive disorder in children. It uses the P300 potential in a series of feedback games to improve the subjects' attention. We applied a support vector machine (SVM) using temporal and template-based features to detect these P300 responses. In an experimental setup using five subjects, an average error below 30% was achieved. To make it more challenging the BCI system has been embedded inside an immersive 3D virtual reality (VR) classroom with simulated distractions, which was created by combining a low-cost infrared camera and an "off-axis perspective projection" algorithm. This system is intended for kids by operating with four electrodes, as well as a non-intrusive VR setting. With the promising results, and considering the simplicity of the scheme, we hope to encourage future studies to adapt the techniques presented in this study.

  20. Promoter-bound p300 complexes facilitate post-mitotic transmission of transcriptional memory.

    Science.gov (United States)

    Wong, Madeline M; Byun, Jung S; Sacta, Maria; Jin, Qihuang; Baek, SongJoon; Gardner, Kevin

    2014-01-01

    A central hallmark of epigenetic inheritance is the parental transmission of changes in patterns of gene expression to progeny without modification of DNA sequence. Although, the trans-generational conveyance of this molecular memory has been traditionally linked to covalent modification of histone and/or DNA, recent studies suggest a role for proteins that persist or remain bound within chromatin to "bookmark" specific loci for enhanced or potentiated responses in daughter cells immediately following cell division. In this report we describe a role for p300 in enabling gene bookmarking by pre-initiation complexes (PICs) containing RNA polymerase II (pol II), Mediator and TBP. Once formed these complexes require p300 to enable reacquisition of protein complex assemblies, chromatin modifications and long range chromatin interactions that facilitate post-mitotic transmission of transcriptional memory of prior environmental stimuli.

  1. Promoter-bound p300 complexes facilitate post-mitotic transmission of transcriptional memory.

    Directory of Open Access Journals (Sweden)

    Madeline M Wong

    Full Text Available A central hallmark of epigenetic inheritance is the parental transmission of changes in patterns of gene expression to progeny without modification of DNA sequence. Although, the trans-generational conveyance of this molecular memory has been traditionally linked to covalent modification of histone and/or DNA, recent studies suggest a role for proteins that persist or remain bound within chromatin to "bookmark" specific loci for enhanced or potentiated responses in daughter cells immediately following cell division. In this report we describe a role for p300 in enabling gene bookmarking by pre-initiation complexes (PICs containing RNA polymerase II (pol II, Mediator and TBP. Once formed these complexes require p300 to enable reacquisition of protein complex assemblies, chromatin modifications and long range chromatin interactions that facilitate post-mitotic transmission of transcriptional memory of prior environmental stimuli.

  2. Epidermal Growth Factor Receptor activation promotes ADA3 acetylation through the AKT-p300 pathway.

    Science.gov (United States)

    Srivastava, Shashank; Mohibi, Shakur; Mirza, Sameer; Band, Hamid; Band, Vimla

    2017-08-18

    The ADA3 (Alteration/Deficiency in Activation 3) protein is an essential adaptor component of several Lysine Acetyltransferase (KAT) complexes involved in chromatin modifications. Previously, we and others have demonstrated a crucial role of ADA3 in cell cycle progression and in maintenance of genomic stability. Recently, we have shown that acetylation of ADA3 is key to its role in cell cycle progression. Here, we demonstrate that AKT activation downstream of Epidermal Growth Factor Receptor (EGFR) family proteins stimulation leads to phosphorylation of p300, which in turn promotes the acetylation of ADA3. Inhibition of upstream receptor tyrosine kinases (RTKs), HER1 (EGFR)/HER2 by lapatinib and the accompanying reduction of phospho-AKT levels led to a decrease in p300 phosphorylation and ADA3 protein levels. The p300/PCAF inhibitor garcinol also destabilized the ADA3 protein in a proteasome-dependent manner and an ADA3 mutant with K→R mutations exhibited a marked increase in half-life, consistent with opposite role of acetylation and ubiquitination of ADA3 on shared lysine residues. ADA3 knockdown led to cell cycle inhibitory effects, as well as apoptosis similar to those induced by lapatinib treatment of HER2+ breast cancer cells, as seen by accumulation of CDK inhibitor p27, reduction in mitotic marker pH3(S10), and a decrease in the S-phase marker PCNA, as well as the appearance of cleaved PARP. Taken together our results reveal a novel RTK-AKT-p300-ADA3 signaling pathway involved in growth factor-induced cell cycle progression.

  3. MindEdit: A P300-based text editor for mobile devices.

    Science.gov (United States)

    Elsawy, Amr S; Eldawlatly, Seif; Taher, Mohamed; Aly, Gamal M

    2017-01-01

    Practical application of Brain-Computer Interfaces (BCIs) requires that the whole BCI system be portable. The mobility of BCI systems involves two aspects: making the electroencephalography (EEG) recording devices portable, and developing software applications with low computational complexity to be able to run on low computational-power devices such as tablets and smartphones. This paper addresses the development of MindEdit; a P300-based text editor for Android-based devices. Given the limited resources of mobile devices and their limited computational power, a novel ensemble classifier is utilized that uses Principal Component Analysis (PCA) features to identify P300 evoked potentials from EEG recordings. PCA computations in the proposed method are channel-based as opposed to concatenating all channels as in traditional feature extraction methods; thus, this method has less computational complexity compared to traditional P300 detection methods. The performance of the method is demonstrated on data recorded from MindEdit on an Android tablet using the Emotiv wireless neuroheadset. Results demonstrate the capability of the introduced PCA ensemble classifier to classify P300 data with maximum average accuracy of 78.37±16.09% for cross-validation data and 77.5±19.69% for online test data using only 10 trials per symbol and a 33-character training dataset. Our analysis indicates that the introduced method outperforms traditional feature extraction methods. For a faster operation of MindEdit, a variable number of trials scheme is introduced that resulted in an online average accuracy of 64.17±19.6% and a maximum bitrate of 6.25bit/min. These results demonstrate the efficacy of using the developed BCI application with mobile devices. Copyright © 2016 Elsevier Ltd. All rights reserved.

  4. Discovery of a selective catalytic p300/CBP inhibitor that targets lineage-specific tumours

    Energy Technology Data Exchange (ETDEWEB)

    Lasko, Loren M.; Jakob, Clarissa G.; Edalji, Rohinton P.; Qiu, Wei; Montgomery, Debra; Digiammarino, Enrico L.; Hansen, T. Matt; Risi, Roberto M.; Frey, Robin; Manaves, Vlasios; Shaw, Bailin; Algire, Mikkel; Hessler, Paul; Lam, Lloyd T.; Uziel, Tamar; Faivre, Emily; Ferguson, Debra; Buchanan, Fritz G.; Martin, Ruth L.; Torrent, Maricel; Chiang, Gary G.; Karukurichi, Kannan; Langston, J. William; Weinert, Brian T.; Choudhary, Chunaram; de Vries, Peter; Van Drie, John H.; McElligott, David; Kesicki, Ed; Marmorstein, Ronen; Sun, Chaohong; Cole, Philip A.; Rosenberg, Saul H.; Michaelides, Michael R.; Lai, Albert; Bromberg, Kenneth D. (AbbVie); (UCopenhagen); (Petra Pharma); (UPENN); (JHU); (Van Drie); (Faraday)

    2017-09-27

    The dynamic and reversible acetylation of proteins, catalysed by histone acetyltransferases (HATs) and histone deacetylases (HDACs), is a major epigenetic regulatory mechanism of gene transcription1 and is associated with multiple diseases. Histone deacetylase inhibitors are currently approved to treat certain cancers, but progress on the development of drug-like histone actyltransferase inhibitors has lagged behind2. The histone acetyltransferase paralogues p300 and CREB-binding protein (CBP) are key transcriptional co-activators that are essential for a multitude of cellular processes, and have also been implicated in human pathological conditions (including cancer3). Current inhibitors of the p300 and CBP histone acetyltransferase domains, including natural products4, bi-substrate analogues5 and the widely used small molecule C6466,7, lack potency or selectivity. Here, we describe A-485, a potent, selective and drug-like catalytic inhibitor of p300 and CBP. We present a high resolution (1.95 Å) co-crystal structure of a small molecule bound to the catalytic active site of p300 and demonstrate that A-485 competes with acetyl coenzyme A (acetyl-CoA). A-485 selectively inhibited proliferation in lineage-specific tumour types, including several haematological malignancies and androgen receptor-positive prostate cancer. A-485 inhibited the androgen receptor transcriptional program in both androgen-sensitive and castration-resistant prostate cancer and inhibited tumour growth in a castration-resistant xenograft model. These results demonstrate the feasibility of using small molecule inhibitors to selectively target the catalytic activity of histone acetyltransferases, which may provide effective treatments for transcriptional activator-driven malignancies and diseases.

  5. The Apoptotic Effects of the P300 Activator on Breast Cancer and Lung Fibroblast Cell Lines

    Directory of Open Access Journals (Sweden)

    Mohammad Reza Salahshoor

    2013-10-01

    Full Text Available Background: P300 is an enzyme that acetylates histones during stress. It alsoacetylates several non-histone proteins, including P53 which is the most important tumorsuppressor gene. P53 plays an important role in the apoptosis of tumor cells. Hereby,this study describes the potency of cholera toxin B subunit as a P300 activator to induceapoptosis in a breast cancer cell line (MCF-7 and a lung fibroblast cell line (MRC-5as a non-tumorigenic control sample. Methods: MCF-7 and MRC-5 were cultured in RPMI-1640 and treated with orwithout cholera toxin B subunit at the concentration of 85.43 μmol/L, based on the half-maximal inhibitory concentration index at different times (24, 48 and 72 h. Thepercentage of apoptotic cells was measured by flow cytometry. Real-time quantitativeRT-PCR was performed to estimate the mRNA expression of P300 in MCF-7 and MRC-5 with cholera toxin B subunit at different times. We used the ELISA and Bradford proteintechniques to detect levels of total and acetylated P53 protein generated in MCF-7 andMRC-5. Results: Our findings indicated that the cholera toxin B subunit effectively andsignificantly induced more apoptosis in MCF-7 compared to MRC-5. We showed thatexpression of P300 up-regulated by increasing the time of the cholera toxin B subunittreatment in MCF-7 but not in MRC-5. In addition, the acetylated and total P53protein levels increased more in MCF-7 cells than in MRC-5 cells.Conclusion: Cholera toxin B subunit induced significant cell death in MCF-7, butit could be well tolerated in MRC-5. Therefore, cholera toxin B subunit can besuggested as an anti-cancer agent.

  6. Object Extraction in Cluttered Environments via a P300-Based IFCE

    Directory of Open Access Journals (Sweden)

    Xiaoqian Mao

    2017-01-01

    Full Text Available One of the fundamental issues for robot navigation is to extract an object of interest from an image. The biggest challenges for extracting objects of interest are how to use a machine to model the objects in which a human is interested and extract them quickly and reliably under varying illumination conditions. This article develops a novel method for segmenting an object of interest in a cluttered environment by combining a P300-based brain computer interface (BCI and an improved fuzzy color extractor (IFCE. The induced P300 potential identifies the corresponding region of interest and obtains the target of interest for the IFCE. The classification results not only represent the human mind but also deliver the associated seed pixel and fuzzy parameters to extract the specific objects in which the human is interested. Then, the IFCE is used to extract the corresponding objects. The results show that the IFCE delivers better performance than the BP network or the traditional FCE. The use of a P300-based IFCE provides a reliable solution for assisting a computer in identifying an object of interest within images taken under varying illumination intensities.

  7. Salicylate, diflunisal and their metabolites inhibit CBP/p300 and exhibit anticancer activity.

    Science.gov (United States)

    Shirakawa, Kotaro; Wang, Lan; Man, Na; Maksimoska, Jasna; Sorum, Alexander W; Lim, Hyung W; Lee, Intelly S; Shimazu, Tadahiro; Newman, John C; Schröder, Sebastian; Ott, Melanie; Marmorstein, Ronen; Meier, Jordan; Nimer, Stephen; Verdin, Eric

    2016-05-31

    Salicylate and acetylsalicylic acid are potent and widely used anti-inflammatory drugs. They are thought to exert their therapeutic effects through multiple mechanisms, including the inhibition of cyclo-oxygenases, modulation of NF-κB activity, and direct activation of AMPK. However, the full spectrum of their activities is incompletely understood. Here we show that salicylate specifically inhibits CBP and p300 lysine acetyltransferase activity in vitro by direct competition with acetyl-Coenzyme A at the catalytic site. We used a chemical structure-similarity search to identify another anti-inflammatory drug, diflunisal, that inhibits p300 more potently than salicylate. At concentrations attainable in human plasma after oral administration, both salicylate and diflunisal blocked the acetylation of lysine residues on histone and non-histone proteins in cells. Finally, we found that diflunisal suppressed the growth of p300-dependent leukemia cell lines expressing AML1-ETO fusion protein in vitro and in vivo. These results highlight a novel epigenetic regulatory mechanism of action for salicylate and derivative drugs.

  8. Salicylate, diflunisal and their metabolites inhibit CBP/p300 and exhibit anticancer activity

    Science.gov (United States)

    Shirakawa, Kotaro; Wang, Lan; Man, Na; Maksimoska, Jasna; Sorum, Alexander W; Lim, Hyung W; Lee, Intelly S; Shimazu, Tadahiro; Newman, John C; Schröder, Sebastian; Ott, Melanie; Marmorstein, Ronen; Meier, Jordan; Nimer, Stephen; Verdin, Eric

    2016-01-01

    Salicylate and acetylsalicylic acid are potent and widely used anti-inflammatory drugs. They are thought to exert their therapeutic effects through multiple mechanisms, including the inhibition of cyclo-oxygenases, modulation of NF-κB activity, and direct activation of AMPK. However, the full spectrum of their activities is incompletely understood. Here we show that salicylate specifically inhibits CBP and p300 lysine acetyltransferase activity in vitro by direct competition with acetyl-Coenzyme A at the catalytic site. We used a chemical structure-similarity search to identify another anti-inflammatory drug, diflunisal, that inhibits p300 more potently than salicylate. At concentrations attainable in human plasma after oral administration, both salicylate and diflunisal blocked the acetylation of lysine residues on histone and non-histone proteins in cells. Finally, we found that diflunisal suppressed the growth of p300-dependent leukemia cell lines expressing AML1-ETO fusion protein in vitro and in vivo. These results highlight a novel epigenetic regulatory mechanism of action for salicylate and derivative drugs. DOI: http://dx.doi.org/10.7554/eLife.11156.001 PMID:27244239

  9. Identification of lysine acetyltransferase p300 substrates using 4-pentynoyl-coenzyme A and bioorthogonal proteomics.

    Science.gov (United States)

    Yang, Yu-Ying; Yu-Ying, Yang; Grammel, Markus; Markus, Grammel; Hang, Howard C; Howard, Hang C

    2011-09-01

    Proteomic studies have identified a plethora of lysine acetylated proteins in eukaryotes and bacteria. Determining the individual lysine acetyltransferases responsible for each protein acetylation mark is crucial for elucidating the underlying regulatory mechanisms, but has been challenging due to limited biochemical methods. Here, we describe the application of a bioorthogonal chemical proteomics method to profile and identify substrates of individual lysine acetyltransferases. Addition of 4-pentynoyl-coenzyme A, an alkynyl chemical reporter for protein acetylation, to cell extracts, together with purified lysine acetyltransferase p300, enabled the fluorescent profiling and identification of protein substrates via Cu(I)-catalyzed alkyne-azide cycloaddition. We identified several known protein substrates of the acetyltransferase p300 as well as the lysine residues that were modified. Interestingly, several new candidate p300 substrates and their sites of acetylation were also discovered using this approach. Our results demonstrate that bioorthogonal chemical proteomics allows the rapid substrate identification of individual protein acetyltransferases in vitro. Copyright © 2011 Elsevier Ltd. All rights reserved.

  10. The Human Factors and Ergonomics of P300-Based Brain-Computer Interfaces

    Science.gov (United States)

    Powers, J. Clark; Bieliaieva, Kateryna; Wu, Shuohao; Nam, Chang S.

    2015-01-01

    Individuals with severe neuromuscular impairments face many challenges in communication and manipulation of the environment. Brain-computer interfaces (BCIs) show promise in presenting real-world applications that can provide such individuals with the means to interact with the world using only brain waves. Although there has been a growing body of research in recent years, much relates only to technology, and not to technology in use—i.e., real-world assistive technology employed by users. This review examined the literature to highlight studies that implicate the human factors and ergonomics (HFE) of P300-based BCIs. We assessed 21 studies on three topics to speak directly to improving the HFE of these systems: (1) alternative signal evocation methods within the oddball paradigm; (2) environmental interventions to improve user performance and satisfaction within the constraints of current BCI systems; and (3) measures and methods of measuring user acceptance. We found that HFE is central to the performance of P300-based BCI systems, although researchers do not often make explicit this connection. Incorporation of measures of user acceptance and rigorous usability evaluations, increased engagement of disabled users as test participants, and greater realism in testing will help progress the advancement of P300-based BCI systems in assistive applications. PMID:26266424

  11. P300 as an auxiliary method in clinical practice: A review of literature

    Directory of Open Access Journals (Sweden)

    Marina Titlic

    2016-12-01

    Full Text Available Cognitive functions can be assessed and followed up over a period of time with cognitive evoked potentials (CEP P300. In this context, brainstem auditory evoked potentials (BAEP are most commonly used, but visual evoked potentials (VEP are utilized as well. The research in this area has demonstrated that these techniques could be used as a supplemental method in diagnostics of numerous diseases such as Alzheimer's disease, mild cognitive impairment, vascular dementia, epilepsy, craniocerebral trauma, Parkinson's disease, multiple sclerosis, and other degenerative diseases. In addition, P300 can also be used as an auxiliary method in the diagnostics of mental disorders conditions such as schizophrenia, panic disorders, narcotic drug addiction, nicotinism, alcoholism, etc. The method assists in monitoring the course of diseases leading to encephalopathy, such as liver and kidney damage and grave anaemia. The advantages of P300 testing are easy application, non-invasiveness, and an unlimited number of potential applications. Moreover, the results obtained with this method are measurable and can be compared.

  12. The Human Factors and Ergonomics of P300-Based Brain-Computer Interfaces

    Directory of Open Access Journals (Sweden)

    J. Clark Powers

    2015-08-01

    Full Text Available Individuals with severe neuromuscular impairments face many challenges in communication and manipulation of the environment. Brain-computer interfaces (BCIs show promise in presenting real-world applications that can provide such individuals with the means to interact with the world using only brain waves. Although there has been a growing body of research in recent years, much relates only to technology, and not to technology in use—i.e., real-world assistive technology employed by users. This review examined the literature to highlight studies that implicate the human factors and ergonomics (HFE of P300-based BCIs. We assessed 21 studies on three topics to speak directly to improving the HFE of these systems: (1 alternative signal evocation methods within the oddball paradigm; (2 environmental interventions to improve user performance and satisfaction within the constraints of current BCI systems; and (3 measures and methods of measuring user acceptance. We found that HFE is central to the performance of P300-based BCI systems, although researchers do not often make explicit this connection. Incorporation of measures of user acceptance and rigorous usability evaluations, increased engagement of disabled users as test participants, and greater realism in testing will help progress the advancement of P300-based BCI systems in assistive applications.

  13. A p300 and SIRT1 Regulated Acetylation Switch of C/EBPα Controls Mitochondrial Function

    Directory of Open Access Journals (Sweden)

    Mohamad A. Zaini

    2018-01-01

    Full Text Available Summary: Cellular metabolism is a tightly controlled process in which the cell adapts fluxes through metabolic pathways in response to changes in nutrient supply. Among the transcription factors that regulate gene expression and thereby cause changes in cellular metabolism is the basic leucine-zipper (bZIP transcription factor CCAAT/enhancer-binding protein alpha (C/EBPα. Protein lysine acetylation is a key post-translational modification (PTM that integrates cellular metabolic cues with other physiological processes. Here, we show that C/EBPα is acetylated by the lysine acetyl transferase (KAT p300 and deacetylated by the lysine deacetylase (KDAC sirtuin1 (SIRT1. SIRT1 is activated in times of energy demand by high levels of nicotinamide adenine dinucleotide (NAD+ and controls mitochondrial biogenesis and function. A hypoacetylated mutant of C/EBPα induces the transcription of mitochondrial genes and results in increased mitochondrial respiration. Our study identifies C/EBPα as a key mediator of SIRT1-controlled adaption of energy homeostasis to changes in nutrient supply. : Zaini et al. show that the transcription factor C/EBPα is acetylated by p300 and deacetylated by the lysine deacetylase SIRT1. Hypoacetylated C/EBPα induces the transcription of mitochondrial genes and results in increased mitochondrial respiration. C/EBPα is a key mediator of SIRT1-controlled adaption of energy homeostasis to changes in nutrient supply. Keywords: C/EBPα, SIRT1, p300, lysine acetylation, mitochondrial function, cellular metabolism, NAD+, gene regulation

  14. Social value orientation modulates the FRN and P300 in the chicken game.

    Science.gov (United States)

    Wang, Yiwen; Kuhlman, D Michael; Roberts, Kathryn; Yuan, Bo; Zhang, Zhen; Zhang, Wei; Simons, Robert F

    2017-07-01

    Social dilemmas pervade daily life, business, and politics. The manners in which these dilemmas are resolved depend in part on the personal characteristics of those involved. One such characteristic is Social Value Orientation (SVO), a trait-like predisposition to maximize cooperative (Pro-Social) or non-cooperative (Pro-Self) outcomes in social relationships. The present study investigated the role of SVO in modulating neural responses to outcomes in a type of social dilemma known as the Chicken Game. The Chicken Game models real-world situations involving two parties independently making a decision between cooperation and aggression. The EEG of Pro-Socials and Pro-Selfs was recorded while playing Chicken with a computer Opponent. Two ERP components were extracted: Feedback-Related Negativity (FRN) and the P300. Despite no behavioral differences in decision (i.e., cooperation, aggression), FRN results indicate that Pro-Socials experienced unreciprocated cooperation as the least desired outcome. Further, P300 results show a main effect for the Opponent's choice, such that the Opponent's cooperation was more salient than aggression. Additionally, an interaction between the Participant's and Opponent's choice showed that the effect for the Opponent's choice only occurred when the Participant chose cooperation. None of the results for P300 were moderated by SVO. For both ERP components, Pro-Selfs showed no differential responding to Chicken outcomes. In addition, FRN magnitude on trial n predicted choice on trial n+1 for Pro-Socials, but not for Pro-Selfs. P300 magnitude on trial n showed no relationship to choice on trial n+1. Results indicate that individual differences in SVO modulate FRN responses to Chicken outcomes, and that these neural reactions may have utility in predicting subsequent behaviors. For P300, there is no evidence of SVO modulation. Our general pattern of FRN responsiveness in Pro-Socials, but not in Pro-Selfs, is related to similar findings in f

  15. Initial test of a T9-like P300-based speller by an ALS patient

    Science.gov (United States)

    Ron-Angevin, R.; Varona-Moya, S.; da Silva-Sauer, L.

    2015-08-01

    Objective. Visual P300-based brain-computer interface spellers offer a useful communication channel for locked-in patients, who are completely dependent in their daily lives. One of the research goals for these systems is to achieve greater communication rates by means of modifying some features of their interfaces, e.g., reducing the matrix size. However, such modifications may not work well with disabled end-users, such as patients of amyotrophic lateral sclerosis (ALS), due to a supposed reduction of their cognitive resources. The purpose of the present study was to provide a proof of concept that ALS patients could efficiently use a P300-based speller with a 4 × 3 symbol matrix based on the T9 interface developed for mobile phones. Approach. We conducted an experiment with a sample of 11 able-bodied participants and one locked-in patient with ALS. All participants tested our T9-like visual P300-based speller and also two different 7 × 6 matrix spellers based on Farwell and Donchin’s classic proposal—one of them included a word predictor system like the T9-like speller did. Main results. The performance analyses indicated that the locked-in patient benefited from using a reduced matrix size as much as healthy users did, spelling words almost 1.6 times faster and equally accurately when using the T9-like speller than when using the alternative spellers. Significance. Due to counting on only one locked-in patient, the current work constitutes a feasibility study. The actual usability of systems such as the one proposed in this paper should be determined by means of studies with a greater number of end-users in real-life conditions.

  16. CoAdapt P300 speller: optimized flashing sequences and online learning

    OpenAIRE

    Thomas, Eoin; Daucé, Emmanuel; Devlaminck, Dieter; Mahé, Loïc; Carpentier, Alexandra; Munos, Rémi; Perrin, Margaux; Maby, Emmanuel; Mattout, Jérémie; Papadopoulo, Théodore; Clerc, Maureen

    2014-01-01

    International audience; This paper presents a series of recent improvements made on the P300 speller paradigm in the context of the CoAdapt project. The flashing sequence is elicited by a new design called RIPRAND, in which the flashing rate of elements can be controlled independently of grid cardinality. Element-based evidence accumulation allows early-stopping of the flashes as soon as the symbol has been detected with confidence. No calibration session is nec-essary, thanks to a mixture-of...

  17. Clinical study on the value of combining neuropsychological tests with auditory event-related potential P300 for cognitive assessment in elderly patients with cerebral small vessel disease

    Directory of Open Access Journals (Sweden)

    Xiao-ling ZHAO

    2016-11-01

    Full Text Available Objective To investigate the value of combining neuropsychological tests with auditory event-related potential (ERP P300 for cognitive assessment in elderly patients with cerebral small vessel disease (cSVD.  Methods A total of 183 elderly patients with cSVD were enrolled in this study. They were divided into 3 groups according to brain MRI: lacunar infarct (LACI group (N = 62, white matter hyperintensity (WMH group (N = 60 and LACI + WMH group (N = 61. A total of 50 brain MRI normal persons were selected as control group. Montreal Cognitive Assessment (MoCA, Chinese version was used to evaluate the cognitive function, and the amplitude and latency of P300 were measured in each group.  Results Compared with control group, the MoCA total score in LACI, WMH and LACI + WMH groups were significantly lower (P = 0.042, 0.015, 0.000, and the score in LACI + WMH group was significantly lower than that in LACI and WMH groups (P = 0.001, 0.042. In the eight cognitive domains of MoCA scale, the visual space and executive function (P = 0.006, 0.041, 0.035, delayed memory (P = 0.006, 0.012, 0.048, language (P = 0.001, 0.032, 0.047 and calculation (P = 0.009, 0.001, 0.003 in LACI + WMH group were significantly lower than those in control, LACI and WMH groups. The delayed memory in LACI group was significantly lower than that in control group (P = 0.037. The delayed memory (P = 0.005 and language (P = 0.047 in WMH group were significantly lower than those in control group. Compared with control group, the amplitudes of P300 (P = 0.025, 0.033, 0.000 in LACI, WMH and LACI + WMH groups were significantly decreased, and the latencies (P = 0.018, 0.000, 0.000 were significantly prolonged. The amplitude of P300 in LACI + WMH group was significantly lower than that in LACI and WMH groups (P = 0.041, 0.018, and the latency was significantly prolonged (P = 0.000, 0.022.  Conclusions Elderly patients of cSVD all suffer from different degrees of cognitive impairment

  18. Modafinil improves event related potentials P300 and contingent negative variation after 24 h sleep deprivation.

    Science.gov (United States)

    Ray, Koushik; Chatterjee, Abhirup; Panjwani, Usha; Kumar, Sanjeev; Sahu, Surajit; Ghosh, Sayan; Thakur, Lalan; Anand, Jag Parvesh

    2012-08-21

    The efficacy of modafinil as a countermeasure in the reduction of cognitive decline following 24 h of sleep deprivation (SD) on subjective sleepiness scales, event-related potential (ERP) P300, and contingent negative variation (CNV) was evaluated. Eleven healthy males, age 25-30 years participated. The experiment was performed in five sessions on different days between 7 and 8a.m. Session 1, baseline recordings; Session 2, after one night's SD; Session 3, 48 h of recovery from SD; Session 4, after 1 week of Session 1, following one night's SD along with modafinil (400mg/day); Session 5, 48 h of recovery after SD+modafinil. Subjective sleepiness scores increased significantly after SD as compared to baseline (Pmodafinil supplementation. There was an increase in N100 and P300 peak latencies of ERP following SD (Pmodafinil (Pmodafinil (Pmodafinil (Pmodafinil in a dose of 400mg/day, reduces the subjective sleepiness and cognitive decline following 24 h of SD. Copyright © 2012 Elsevier Inc. All rights reserved.

  19. An Asynchronous P300-Based Brain-Computer Interface Web Browser for Severely Disabled People.

    Science.gov (United States)

    Martinez-Cagigal, Victor; Gomez-Pilar, Javier; Alvarez, Daniel; Hornero, Roberto

    2017-08-01

    This paper presents an electroencephalographic (EEG) P300-based brain-computer interface (BCI) Internet browser. The system uses the "odd-ball" row-col paradigm for generating the P300 evoked potentials on the scalp of the user, which are immediately processed and translated into web browser commands. There were previous approaches for controlling a BCI web browser. However, to the best of our knowledge, none of them was focused on an assistive context, failing to test their applications with a suitable number of end users. In addition, all of them were synchronous applications, where it was necessary to introduce a "read-mode" command in order to avoid a continuous command selection. Thus, the aim of this study is twofold: 1) to test our web browser with a population of multiple sclerosis (MS) patients in order to assess the usefulness of our proposal to meet their daily communication needs; and 2) to overcome the aforementioned limitation by adding a threshold that discerns between control and non-control states, allowing the user to calmly read the web page without undesirable selections. The browser was tested with sixteen MS patients and five healthy volunteers. Both quantitative and qualitative metrics were obtained. MS participants reached an average accuracy of 84.14%, whereas 95.75% was achieved by control subjects. Results show that MS patients can successfully control the BCI web browser, improving their personal autonomy.

  20. NF-κB suppresses HIF-1α response by competing for P300 binding

    International Nuclear Information System (INIS)

    Mendonca, Daniela B.S.; Mendonca, Gustavo; Aragao, Francisco J.L.; Cooper, Lyndon F.

    2011-01-01

    Research highlights: → p65 completely blocked HIF-1α activity at the HRE on different cell lines. → p65 caused minor changes in HIF-1α and HIF-1α target genes mRNA expression. → p65 reduced transcription of VEGF promoter. → p65 competes with HIF-1α for p300. -- Abstract: Hypoxia has emerged as a key determinant of osteogenesis. HIF-1α is the transcription factor mediating hypoxia responses that include induction of VEGF and related bone induction. Inflammatory signals antagonize bone repair via the NF-κB pathway. The present investigation explored the functional relationship of hypoxia (HIF-1α function) and inflammatory signaling (NF-κB) in stem like and osteoprogenitor cell lines. The potential interaction between HIF-1α and NF-κB signaling was explored by co-transfection studies in hFOB with p65, HIF-1α and 9x-HRE-luc or HIF-1α target genes reporter plasmids. Nuclear cross-talk was directly tested using the mammalian Gal4/VP16 two-hybrid, and confirmed by co-immunoprecipitation/western blotting assays. The results show that inflammatory stimulation (TNF-α treatment) causes a marked inhibition of HIF-1α function at the HRE in all cell lines studied. Also, co-transfection with p65 expression vector leads to reduced hVEGFp transcription after DFO-induced hypoxia. However, TNF-α treatment had little effect on HIF-1α mRNA levels. The functional interaction of Gal4-HIF-1α and VP16-p300 fusion proteins is effectively blocked by expression of p65 in a dose dependent manner. It was concluded that NF-κB-mediated inflammatory signaling is able to block HIF-1α transactivation at HRE-encoding genes by direct competition for p300 binding at the promoter. Inflammation may influence the stem cell niche and tissue regeneration by influencing cellular responses to hypoxia.

  1. Genetic feature selection to optimally detect P300 in brain computer interfaces.

    Science.gov (United States)

    Atum, Yanina; Gareis, Iván; Gentiletti, Gerardo; Acevedo, Rubén; Rufiner, Leonardo

    2010-01-01

    A Brain Computer Interface is a system that provides an artificial communication between the human brain and the external world. The paradigm based on event related evoked potentials is used in this work. Our main goal was to efficiently solve a binary classification problem: presence or absence of P300 in the registers. Genetic Algorithms and Support Vector Machines were used in a wrapper configuration for feature selection and classification. The original input patterns were provided by two channels (Oz and Fz) of resampled EEG registers and wavelet coefficients. To evaluate the performance of the system, accuracy, sensibility and specificity were calculated. The wrapped wavelet patterns show a better performance than the temporal ones. The results were similar for patterns from channel Oz and Fz, together or separated.

  2. Autoregressive Integrated Adaptive Neural Networks Classifier for EEG-P300 Classification

    Directory of Open Access Journals (Sweden)

    Demi Soetraprawata

    2013-06-01

    Full Text Available Brain Computer Interface has a potency to be applied in mechatronics apparatus and vehicles in the future. Compared to the other techniques, EEG is the most preferred for BCI designs. In this paper, a new adaptive neural network classifier of different mental activities from EEG-based P300 signals is proposed. To overcome the over-training that is caused by noisy and non-stationary data, the EEG signals are filtered and extracted using autoregressive models before passed to the adaptive neural networks classifier. To test the improvement in the EEG classification performance with the proposed method, comparative experiments were conducted using Bayesian Linear Discriminant Analysis. The experiment results show that the all subjects achieve a classification accuracy of 100%.

  3. Discovery of a selective catalytic p300/CBP inhibitor that targets lineage-specific tumours

    DEFF Research Database (Denmark)

    Lasko, Loren M; Jakob, Clarissa G; Edalji, Rohinton P

    2017-01-01

    The dynamic and reversible acetylation of proteins, catalysed by histone acetyltransferases (HATs) and histone deacetylases (HDACs), is a major epigenetic regulatory mechanism of gene transcription and is associated with multiple diseases. Histone deacetylase inhibitors are currently approved...... model. These results demonstrate the feasibility of using small molecule inhibitors to selectively target the catalytic activity of histone acetyltransferases, which may provide effective treatments for transcriptional activator-driven malignancies and diseases....... also been implicated in human pathological conditions (including cancer). Current inhibitors of the p300 and CBP histone acetyltransferase domains, including natural products, bi-substrate analogues and the widely used small molecule C646, lack potency or selectivity. Here, we describe A-485, a potent...

  4. An Efficient Framework for EEG Analysis with Application to Hybrid Brain Computer Interfaces Based on Motor Imagery and P300

    Directory of Open Access Journals (Sweden)

    Jinyi Long

    2017-01-01

    Full Text Available The hybrid brain computer interface (BCI based on motor imagery (MI and P300 has been a preferred strategy aiming to improve the detection performance through combining the features of each. However, current methods used for combining these two modalities optimize them separately, which does not result in optimal performance. Here, we present an efficient framework to optimize them together by concatenating the features of MI and P300 in a block diagonal form. Then a linear classifier under a dual spectral norm regularizer is applied to the combined features. Under this framework, the hybrid features of MI and P300 can be learned, selected, and combined together directly. Experimental results on the data set of hybrid BCI based on MI and P300 are provided to illustrate competitive performance of the proposed method against other conventional methods. This provides an evidence that the method used here contributes to the discrimination performance of the brain state in hybrid BCI.

  5. p300-mediated acetylation of the Rothmund-Thomson-syndrome gene product RECQL4 regulates its subcellular localization

    DEFF Research Database (Denmark)

    Dietschy, Tobias; Shevelev, Igor; Pena Diaz, Javier

    2009-01-01

    RECQL4 belongs to the conserved RecQ family of DNA helicases, members of which play important roles in the maintenance of genome stability in all organisms that have been examined. Although genetic alterations in the RECQL4 gene are reported to be associated with three autosomal recessive disorders...... (Rothmund-Thomson, RAPADILINO and Baller-Gerold syndromes), the molecular role of RECQL4 still remains poorly understood. Here, we show that RECQL4 specifically interacts with the histone acetyltransferase p300 (also known as p300 HAT), both in vivo and in vitro, and that p300 acetylates one or more...... of the lysine residues at positions 376, 380, 382, 385 and 386 of RECQL4. Furthermore, we report that these five lysine residues lie within a short motif of 30 amino acids that is essential for the nuclear localization of RECQL4. Remarkably, the acetylation of RECQL4 by p300 in vivo leads to a significant shift...

  6. Brain-computer interface research at the University of South Florida Cognitive Psychophysiology Laboratory: the P300 Speller.

    Science.gov (United States)

    Sellers, Eric W; Kübler, Andrea; Donchin, Emanuel

    2006-06-01

    We describe current efforts to implement and improve P300-BCI communication tools. The P300 Speller first described by Farwell and Donchin (in 1988) adapted the so-called oddball paradigm (OP) as the operating principle of the brain-computer interface (BCI) and was the first P300-BCI. The system operated by briefly intensifying each row and column of a matrix and the attended row and column elicited a P300 response. This paradigm has been the benchmark in P300-BCI systems, and in the past few years the P300 Speller paradigm has been solidified as a promising communication tool. While promising, we have found that some people who have amyotrophic lateral sclerosis (ALS) would be better suited with a system that has a limited number of choices, particularly if the 6 x 6 matrix is difficult to use. Therefore, we used the OP to implement a four-choice system using the commands: Yes, No, Pass, and End; we also used three presentation modes: auditory, visual, and auditory and visual. We summarize results from both paradigms and also discuss obstacles we have identified while working with the ALS population outside of the laboratory environment.

  7. Correlação do potencial evocado P300 com aspectos cognitivos e depressivos do envelhecimento Correlation of the P300 evoked potential in depressive and cognitive aspects of aging

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    Elisiane Crestani de Miranda

    2012-10-01

    Full Text Available O P300 é um potencial evocado auditivo de longa latência dependente das habilidades cognitivas. Acredita-se que alterações cognitivas decorrentes ou não por sintomas depressivos possam interferir no P300. OBJETIVO: Verificar a influência do envelhecimento, dos aspectos cognitivos e depressivos na latência do P300 em idosos. MÉTODO: Estudo clínico e experimental com 60 idosos com perda auditiva neurossensorial de grau leve a moderadamente grave, sendo 20 do sexo masculino e 40 feminino e idade média de 71,1 anos. Os participantes realizaram o potencial evocado auditivo de longa latência, no qual foi estudada a latência do P300 (milissegundos. Os aspectos cognitivos foram avaliados por meio do Miniexame do Estado Mental (MEEM e Escala de Avaliação da Doença de Alzheimer (ADAS-Cog. Na avaliação da sintomatologia depressiva, foi aplicada a Escala de Depressão Geriátrica (EDG-15. RESULTADOS: Observou-se uma correlação positiva significante entre a Latência e Idade (p = 0,031. Entretanto, não houve diferença significante entre a latência do P300 e as categorias do ADAS-Cog (p = 0,584, MEEM (p = 0,199 e EDG (p = 0,541. CONCLUSÃO:O avanço da idade ocasionou um aumento da latência do P300, porém, o desempenho cognitivo e a presença de sintomatologia depressiva não influenciaram os resultados do P300 nesta população de idosos.The P300 is a long-latency auditory evoked potential highly dependent on cognitive skills. It is believed that cognitive changes caused or not by depressive symptoms may interfere with the P300. AIM: To investigate the influence of aging, cognitive and depression aspects of the P300 latency in elderly people. METHODS: Clinical and experimental study with 60 elderly patients with sensorineural hearing loss of mild to moderately severe level, 20 males and 40 females, average age of 71.1. Participants were submitted to the long latency auditory evoked potential, in which the P300 latency (milliseconds

  8. Rapid P300 brain-computer interface communication with a head-mounted display

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    Ivo eKäthner

    2015-06-01

    Full Text Available Visual ERP (P300 based brain-computer interfaces (BCIs allow for fast and reliable spelling and are intended as a muscle-independent communication channel for people with severe paralysis. However, they require the presentation of visual stimuli in the field of view of the user. A head mounted display could allow convenient presentation of visual stimuli in situations, where mounting a conventional monitor might be difficult or not feasible (e.g. at a patient’s bedside. To explore if similar accuracies can be achieved with a virtual reality (VR headset compared to a conventional flat screen monitor, we conducted an experiment with 18 healthy participants. We also evaluated it with a person in the locked-in state (LIS to verify that usage of the headset is possible for a severely paralyzed person. Healthy participants performed online spelling with three different display methods. In one condition a 5x5 letter matrix was presented on a conventional 22 inch TFT monitor. Two configurations of the VR headset were tested. In the first (glasses A, the same 5x5 matrix filled the field of view of the user. In the second (glasses B, single letters of the matrix filled the field of view of the user. The participant in the LIS tested the VR headset on 3 different occasions (glasses A condition only. For healthy participants, average online spelling accuracies were 94% (15.5 bits/min using three flash sequences for spelling with the monitor and glasses A and 96% (16.2 bits/min with glasses B. In one session, the participant in the LIS reached an online spelling accuracy of 100% (10 bits/min using the glasses A condition. We also demonstrated that spelling with one flash sequence is possible with the VR headset for healthy users (mean: 32.1 bits/min, maximum reached by one user: 71.89 bits/min at 100% accuracy. We conclude that the VR headset allows for rapid P300 BCI communication in healthy users and may be a suitable display option for severely

  9. A novel nuclear Src and p300 signaling axis controls migratory and invasive behavior in pancreatic cancer

    Science.gov (United States)

    Paladino, David; Yue, Peibin; Furuya, Hideki; Acoba, Jared; Rosser, Charles J.; Turkson, James

    2016-01-01

    The presence of Src in the nuclear compartment has been previously reported, although its significance has remained largely unknown. We sought to delineate the functions of the nuclear pool of Src within the context of malignant progression. Active Src is localized within the nuclei of human pancreatic cancer cells and mouse fibroblasts over-expressing c-Src where it is associated with p300. Nuclear Src additionally promotes the tyrosine phosphorylation of p300 in pancreatic cancer Panc-1 cells. Src, together with p300, is associated with the high-mobility group AT-hook (HMGA)2 and SET and MYND domain-containing protein (SMYD)3 gene promoters and regulates their expression in a Src-dependent manner. These nuclear Src-dependent events correlate with anchorage-independent soft-agar growth and the migratory properties in both pancreatic Panc-1 cells and mouse fibroblasts over-expressing Src. Moreover, analyses of human pancreatic ductal adenocarcinoma (PDAC) tumor tissues detected the association of nuclear Src with the HMGA2 and SMYD3 gene promoters. Our findings for the first time show the critical importance of nuclear Src and p300 function in the migratory properties of pancreatic cancer cells. Further, data together identify a previously unknown role of nuclear Src in the regulation of gene expression in association with p300 within the context of cells harboring activated or over-expressing Src. This novel mechanism of nuclear Src-p300 axis in PDAC invasiveness and metastasis may provide an opportunity for developing more effective early clinical interventions for this lethal disease. Active Src is complexed with and phosphorylates p300 in the nucleus, and the complex is bound to HMGA2 and SMYD3 genes, thereby regulating their expression to promote pancreatic tumor cell migration and invasiveness. PMID:26695438

  10. A Fuzzy Integral Ensemble Method in Visual P300 Brain-Computer Interface

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    Francesco Cavrini

    2016-01-01

    Full Text Available We evaluate the possibility of application of combination of classifiers using fuzzy measures and integrals to Brain-Computer Interface (BCI based on electroencephalography. In particular, we present an ensemble method that can be applied to a variety of systems and evaluate it in the context of a visual P300-based BCI. Offline analysis of data relative to 5 subjects lets us argue that the proposed classification strategy is suitable for BCI. Indeed, the achieved performance is significantly greater than the average of the base classifiers and, broadly speaking, similar to that of the best one. Thus the proposed methodology allows realizing systems that can be used by different subjects without the need for a preliminary configuration phase in which the best classifier for each user has to be identified. Moreover, the ensemble is often capable of detecting uncertain situations and turning them from misclassifications into abstentions, thereby improving the level of safety in BCI for environmental or device control.

  11. The portable P300 dialing system based on tablet and Emotiv Epoc headset.

    Science.gov (United States)

    Tong Jijun; Zhang Peng; Xiao Ran; Ding Lei

    2015-08-01

    A Brain-computer interface (BCI) is a novel communication system that translates brain signals into a control signal. Now with the appearance of the commercial EEG headsets and mobile smart platforms (tablet, smartphone), it is possible to develop the mobile BCI system, which can greatly improve the life quality of patients suffering from motor disease, such as amyotrophic lateral scleroses (ALS), multiple sclerosis, cerebral palsy and head trauma. This study adopted a 14-channel Emotiv EPOC headset and Microsoft surface pro 3 to realize a dialing system, which was represented by 4×3 matrices of alphanumeric characters. The performance of the online portable dialing system based on P300 is satisfying. The average classification accuracy reaches 88.75±10.57% in lab and 73.75±16.94% in metro, while the information transfer rate (ITR) reaches 7.17±1.80 and 5.05±2.17 bits/min respectively. This means the commercial EEG headset and tablet has good prospect in developing real time BCI system in realistic environments.

  12. Detection of Drug Effects on Brain Activity using EEG-P300 with Similar Stimuli

    Science.gov (United States)

    Turnip, Arjon; Dwi Esti, K.; Faizal Amri, M.; Simbolon, Artha I.; Agung Suhendra, M.; IsKandar, Shelly; Wirakusumah, Firman F.

    2017-07-01

    Drug addiction poses a serious problem to our species. The worry that our significant family might be involved in drug use and are concerned to know how to detect drug use. Examinations of thirty taped EEG recordings were performed. The subjects consist of three group: addictive, methadone treatment (rehabilitation), and control (normal) which 10 subjects for each group. Statistical analysis was performed for the relative frequency of wave bands. The higher average amplitude is obtained from the addiction subjects. In the comparison with the signals source, channels P3 provide slightly higher average amplitude than other channels for all of subjects.

  13. Enhancing performance of P300-Speller under mental workload by incorporating dual-task data during classifier training.

    Science.gov (United States)

    Chen, Yuqian; Ke, Yufeng; Meng, Guifang; Jiang, Jin; Qi, Hongzhi; Jiao, Xuejun; Xu, Minpeng; Zhou, Peng; He, Feng; Ming, Dong

    2017-12-01

    As one of the most important brain-computer interface (BCI) paradigms, P300-Speller was shown to be significantly impaired once applied in practical situations due to effects of mental workload. This study aims to provide a new method of building training models to enhance performance of P300-Speller under mental workload. Three experiment conditions based on row-column P300-Speller paradigm were performed including speller-only, 3-back-speller and mental-arithmetic-speller. Data under dual-task conditions were introduced to speller-only data respectively to build new training models. Then performance of classifiers with different models was compared under the same testing condition. The results showed that when tasks of imported training data and testing data were the same, character recognition accuracies and round accuracies of P300-Speller with mixed-data training models significantly improved (FDR, p mental-arithmetic-speller (FDR, p training data and testing data was significantly diminished when the dual-task data was introduced to training data (FDR, p training classifier on mixed data proved to be effective in enhancing performance of P300-Speller under mental workload, confirmed the feasibility to build a universal training model and overcome the effects of mental workload in its practical applications. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. Recent Advances in the Discovery of HIF-1α-p300/CBP Inhibitors as Anti-Cancer Agents.

    Science.gov (United States)

    Wei, Jinlian; Yang, Yingrui; Lu, Mengchen; Lei, Yonghua; Xu, Lili; Jiang, Zhengyu; Xu, Xiaoli; Guo, Xiaoke; Zhang, Xiaojin; Sun, Haopeng; You, Qidong

    2018-01-01

    Hypoxia-inducible factor-1 (HIF-1), a heterodimeric (containing α and β subunits) transcription factor, is involved in hypoxia response pathway that regulates the expression of many tumorrelated genes. The stabilized HIF-1 heterodimer couples to the general co-activators p300/CBP (CREB binding protein), forming an active transcription factor to initiate hypoxic responses. Inhibiting the transcription factor-coactivator HIF-1α-p300/CBP interaction represents an attractive approach for blocking hypoxia pathway in tumors. Recently, diverse HIF-1α-p300/CBP inhibitors have been designed and their anti-tumor activities have been evaluated. The developments of inhibitors of HIF-1α- p300/CBP are discussed in this review. An outline of structures and biological activities of these inhibitors can be traced, along with the approaches for inhibitors discovery. The challenges in identifying novel and selective potent inhibitors of HIF-1α-p300/CBP are also put forward. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  15. Event-related potentials (P300 and neuropsychological assessment in boys exhibiting Duchenne muscular dystrophy Potencial evocado cognitivo (P300 e testagem neuropsicológica em pacientes com distrofia muscular de Duchenne

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    Marcus Vinicius Della Coletta

    2007-03-01

    Full Text Available OBJECTIVE: To examine auditory cognitive evoked potentials (P300 potentials and neuropsychological dysfunction in patients with Duchenne muscular dystrophy (DMD. METHOD: P300 potentials and neuropsychological test results were obtained from 16 healthy control boys and 20 DMD patients. Full Intelligence Quotients (IQ were estimated for patients and control group. Mean age was 9.5 years in the DMD patient group, and 10 years in the control group (p>0.05. RESULTS: The mean IQ values were 64.35 in the DMD patients and 82.68 in the control group (p=0.01. Mean P300 values were 347.6 in the DMD group and 337.4 in the control group (p=0.14. There was no significant correlation between parameters in each group. CONCLUSION: DMD patients showed a poor performance as evaluated by P300 potential compared to the control group, although the difference was not statistically significant. Systematic alterations in neuropsychological test results were found, the differences paralleling those detected in IQ.OBJETIVO: Avaliar potenciais evocados cognitivos auditivos (P300 e disfunções neuropsicológicas em pacientes com distrofia muscular de Duchenne (DMD. MÉTODO: Potenciais auditivos P300 e testes neuropsicológicos foram obtidos de 16 controles e 20 pacientes com DMD. Valores de quociente de inteligência (QI foram estimados para os dois grupos. A media de idade foi de 9.5 anos no grupo DMD e 10 anos no grupo controle (p>0.05. RESULTADOS: Os valores médios de QI foram 64.35 no grupo DMD e 82.68 no grupo controle (p=0.01. A média de valores de P300 foi 347.6 no grupo DMD e 337.4 no grupo controle (p=0.14. Não houve correlação significativa entre os parâmetros em cada grupo. CONCLUSÃO: Os pacientes com DMD mostraram um pior desempenho nas testagens de P300 quando comparados com o grupo controle, embora a diferença não tenha apresentado diferença significativa. Alterações sistemáticas foram encontradas nos testes neuropsicológicos, correspondendo

  16. Avaliação pelo P300 de crianças com e sem epilepsia e rendimento escolar Assessment through P300 of epileptic and non-epileptic children and school performance

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    JUCELEI F. VISIOLI-MELO

    2000-06-01

    Full Text Available Dificuldade de aprendizagem é situação comum em crianças com epilepsia. Distúrbios da inteligência têm sido associados com epilepsia. O potencial cognitivo (P300 é um adjunto clínico para mensurar neurofisiologicamente o processo cognitivo. Foram estudadas 99 crianças com 10 anos a 11 anos e 11 meses. Do Grupo I, sem epilepsia, faziam parte 64 crianças, das quais 32 com bom rendimento e outras 32 com mau rendimento escolar. Do Grupo II, com epilepsia, faziam parte 35 crianças, sendo 21 com bom rendimento escolar e 15 com mau rendimento escolar. Não foi encontrada diferença significativa na latência do P300 entre os dois grupos. Quando foram estratificados segundo o desempenho escolar, as crianças do Grupo I, com bom rendimento escolar, apresentaram latência do P300 de 336 ms e as com mau rendimento escolar, latência de 382 ms; as crianças do Grupo II, com bom rendimento escolar, apresentaram latência do P300 de 363 ms e as com mau rendimento escolar, latência de 400 ms, com diferença significativa. Essa diferença estava localizada entre as crianças não epilépticas com bom desempenho escolar e as com mau desempenho escolar, epilépticas ou não.Learning disability is common in epileptic children. Epilepsy has been associated with disorders of intelligence. Cognitive potential (P300 is considered to be a clinical aid in the neurophysiological measurement of the cognitive process. Ninety-nine children between the ages of 10 years and 11 years and 11 months formed our sample, with good and poor school performance. Group I, non-epileptic, had 64 children of whom 32 had good and 32 poor school performance. Group II, epileptic, had 35 children, of whom 21 had good and 15 poor school performance. No significant difference in P300 latency was found between Groups I and II. When groups were stratified based on school performance, Group I children with good school performance had P300 latency of 336 ms, while the ones with poor

  17. Performance of the Emotiv Epoc headset for P300-based applications

    Science.gov (United States)

    2013-01-01

    Background For two decades, EEG-based Brain-Computer Interface (BCI) systems have been widely studied in research labs. Now, researchers want to consider out-of-the-lab applications and make this technology available to everybody. However, medical-grade EEG recording devices are still much too expensive for end-users, especially disabled people. Therefore, several low-cost alternatives have appeared on the market. The Emotiv Epoc headset is one of them. Although some previous work showed this device could suit the customer’s needs in terms of performance, no quantitative classification-based assessments compared to a medical system are available. Methods This paper aims at statistically comparing a medical-grade system, the ANT device, and the Emotiv Epoc headset by determining their respective performances in a P300 BCI using the same electrodes. On top of that, a review of previous Emotiv studies and a discussion on practical considerations regarding both systems are proposed. Nine healthy subjects participated in this experiment during which the ANT and the Emotiv systems are used in two different conditions: sitting on a chair and walking on a treadmill at constant speed. Results The Emotiv headset performs significantly worse than the medical device; observed effect sizes vary from medium to large. The Emotiv headset has higher relative operational and maintenance costs than its medical-grade competitor. Conclusions Although this low-cost headset is able to record EEG data in a satisfying manner, it should only be chosen for non critical applications such as games, communication systems, etc. For rehabilitation or prosthesis control, this lack of reliability may lead to serious consequences. For research purposes, the medical system should be chosen except if a lot of trials are available or when the Signal-to-Noise Ratio is high. This also suggests that the design of a specific low-cost EEG recording system for critical applications and research is still

  18. Performance of the Emotiv Epoc headset for P300-based applications.

    Science.gov (United States)

    Duvinage, Matthieu; Castermans, Thierry; Petieau, Mathieu; Hoellinger, Thomas; Cheron, Guy; Dutoit, Thierry

    2013-06-25

    For two decades, EEG-based Brain-Computer Interface (BCI) systems have been widely studied in research labs. Now, researchers want to consider out-of-the-lab applications and make this technology available to everybody. However, medical-grade EEG recording devices are still much too expensive for end-users, especially disabled people. Therefore, several low-cost alternatives have appeared on the market. The Emotiv Epoc headset is one of them. Although some previous work showed this device could suit the customer's needs in terms of performance, no quantitative classification-based assessments compared to a medical system are available. This paper aims at statistically comparing a medical-grade system, the ANT device, and the Emotiv Epoc headset by determining their respective performances in a P300 BCI using the same electrodes. On top of that, a review of previous Emotiv studies and a discussion on practical considerations regarding both systems are proposed. Nine healthy subjects participated in this experiment during which the ANT and the Emotiv systems are used in two different conditions: sitting on a chair and walking on a treadmill at constant speed. The Emotiv headset performs significantly worse than the medical device; observed effect sizes vary from medium to large. The Emotiv headset has higher relative operational and maintenance costs than its medical-grade competitor. Although this low-cost headset is able to record EEG data in a satisfying manner, it should only be chosen for non critical applications such as games, communication systems, etc. For rehabilitation or prosthesis control, this lack of reliability may lead to serious consequences. For research purposes, the medical system should be chosen except if a lot of trials are available or when the Signal-to-Noise Ratio is high. This also suggests that the design of a specific low-cost EEG recording system for critical applications and research is still required.

  19. Aging does not affect generalized postural motor learning in response to variable amplitude oscillations of the support surface.

    Science.gov (United States)

    Van Ooteghem, Karen; Frank, James S; Allard, Fran; Horak, Fay B

    2010-08-01

    Postural motor learning for dynamic balance tasks has been demonstrated in healthy older adults (Van Ooteghem et al. in Exp Brain Res 199(2):185-193, 2009). The purpose of this study was to investigate the type of knowledge (general or specific) obtained with balance training in this age group and to examine whether embedding perturbation regularities within a balance task masks specific learning. Two groups of older adults maintained balance on a translating platform that oscillated with variable amplitude and constant frequency. One group was trained using an embedded-sequence (ES) protocol which contained the same 15-s sequence of variable amplitude oscillations in the middle of each trial. A second group was trained using a looped-sequence (LS) protocol which contained a 15-s sequence repeated three times to form each trial. All trials were 45 s. Participants were not informed of any repetition. To examine learning, participants performed a retention test following a 24-h delay. LS participants also completed a transfer task. Specificity of learning was examined by comparing performance for repeated versus random sequences (ES) and training versus transfer sequences (LS). Performance was measured by deriving spatial and temporal measures of whole body center of mass (COM) and trunk orientation. Both groups improved performance with practice as characterized by reduced COM displacement, improved COM-platform phase relationships, and decreased angular trunk motion. Furthermore, improvements reflected general rather than specific postural motor learning regardless of training protocol (ES or LS). This finding is similar to young adults (Van Ooteghem et al. in Exp Brain Res 187(4):603-611, 2008) and indicates that age does not influence the type of learning which occurs for balance control.

  20. A region-based two-step P300-based brain-computer interface for patients with amyotrophic lateral sclerosis.

    Science.gov (United States)

    Ikegami, Shiro; Takano, Kouji; Kondo, Kiyohiko; Saeki, Naokatsu; Kansaku, Kenji

    2014-11-01

    The P300-based brain-computer interface (BCI) is designed to help patients with motor disabilities to control their environment, and it has been used successfully in patients with amyotrophic lateral sclerosis (ALS). However, some ALS patients were unable to use the visual P300-BCI with the conventional row/column presentation. In this study, we evaluated the effect of a newly developed region-based two-step P300 speller, which has a larger flashing area than the conventional visual array. Seven ALS patients and seven age- and sex-matched able-bodied control subjects were required to input hiragana characters using our P300 BCI system. We prepared two types of input procedures, the conventional row/column (RC) speller and the two-step speller, and evaluated their online performance. The mean online accuracy of the ALS patients was 24% for the RC condition and 55% for the two-step condition. The accuracy of the control subjects was 71% and 83% for the RC and two-step condition, respectively. Accuracy in ALS patients was significantly lower than that in the control subjects, and the new visual stimuli significantly increased accuracy of ALS patients. Using the new speller, two ALS patients showed an initial accuracy sufficient for practical use (>70%). The other two ALS patients, who performed better in the first trial using the new speller, continued to experience the BCI system, and their mean accuracy increased to 92%. The two-step procedure for the visual P300 BCI system provided significantly increased accuracy for ALS patients compared with a conventional RC speller. The new region-based two-step P300 speller was effective in ALS patients, and the system may be beneficial to expand their range of activities. Copyright © 2014 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

  1. Therapeutic effect of Cryptotanshinone on experimental rheumatoid arthritis through downregulating p300 mediated-STAT3 acetylation.

    Science.gov (United States)

    Wang, Ying; Zhou, Chun; Gao, Hui; Li, Cuixian; Li, Dong; Liu, Peiqing; Huang, Min; Shen, Xiaoyan; Liu, Liang

    2017-08-15

    The balance between T helper 17 (Th17) cells and regulatory T (Treg) cells, plays a critical role in rheumatoid arthritis (RA). The differentiation of Th17 cells requires the activation of STAT3, which determines the balance of Th17/Treg. Here, we investigated the therapeutic effect of Cryptotanshinone (CTS) on collagen induced mouse arthritis and explored the underlying mechanisms. Arthritis was induced in DBA/1 mice with bovine collagen type II and complete Freund's adjuvant. CTS was given at 20mgkg -1 d -1 or 60mgkg -1 d -1 by gavage for 6weeks. The immuno-inflammation and joint destruction were evaluated and the balance of Th17/Treg was determined. STAT3 acetylation and phosphorylation were detected by western blotting, and the involvement of p300 was investigated by siRNA and plasmid overexpression. CTS at a dose of 60mgkg -1 d -1 ameliorated the inflammation and joint destruction in CIA mice. It improved Th17/Treg imbalance, and inhibited both acetylation and phosphorylation of STAT3. CTS reduced p300 expression and its binding to STAT3, but increased phosphorylated AMPK. Knockdown of p300 mimicked the inhibitory effect of CTS on STAT3 acetylation and phosphorylation, which could be partially rescued by overexpression of p300-WT, but not p300-dominant negative (DN) construct. Our study suggested that the anti-arthritis effects of CTS were attained through suppression of p300-mediated STAT3 acetylation. Our data suggest that CTS might be a potential immune modulator for RA treatment. Copyright © 2017 Elsevier Inc. All rights reserved.

  2. A novel algorithm to enhance P300 in single trials: application to lie detection using F-score and SVM.

    Science.gov (United States)

    Gao, Junfeng; Tian, Hongjun; Yang, Yong; Yu, Xiaolin; Li, Chenhong; Rao, Nini

    2014-01-01

    The investigation of lie detection methods based on P300 potentials has drawn much interest in recent years. We presented a novel algorithm to enhance signal-to-noise ratio (SNR) of P300 and applied it in lie detection to increase the classification accuracy. Thirty-four subjects were divided randomly into guilty and innocent groups, and the EEG signals on 14 electrodes were recorded. A novel spatial denoising algorithm (SDA) was proposed to reconstruct the P300 with a high SNR based on independent component analysis. The differences between the proposed method and our/other early published methods mainly lie in the extraction and feature selection method of P300. Three groups of features were extracted from the denoised waves; then, the optimal features were selected by the F-score method. Selected feature samples were finally fed into three classical classifiers to make a performance comparison. The optimal parameter values in the SDA and the classifiers were tuned using a grid-searching training procedure with cross-validation. The support vector machine (SVM) approach was adopted to combine with an F-score because this approach had the best performance. The presented model F-score_SVM reaches a significantly higher classification accuracy for P300 (specificity of 96.05%) and non-P300 (sensitivity of 96.11%) compared with the results obtained without using SDA and compared with the results obtained by other classification models. Moreover, a higher individual diagnosis rate can be obtained compared with previous methods, and the presented method requires only a small number of stimuli in the real testing application.

  3. Coactivators p300 and CBP maintain the identity of mouse embryonic stem cells by mediating long-range chromatin structure.

    Science.gov (United States)

    Fang, Fang; Xu, Yifeng; Chew, Kai-Khen; Chen, Xi; Ng, Huck-Hui; Matsudaira, Paul

    2014-07-01

    Master transcription factors Oct4, Sox2, and Nanog are required to maintain the pluripotency and self-renewal of embryonic stem cells (ESCs) by regulating a specific transcriptional network. A few other transcription factors have been shown to be important in ESCs by interacting with these master transcription factors; however, little is known about the transcriptional mechanisms regulated by coregulators (coactivators and corepressors). In this study, we examined the function of two highly homologous coactivators, p300 and CREB-binding protein (CBP), in ESCs. We find that these two coactivators play redundant roles in maintaining the undifferentiated state of ESCs. They are recruited by Nanog through physical interaction to Nanog binding loci, mediating the formation of long-range chromatin looping structures, which is essential to maintain ESC-specific gene expression. Further functional studies reveal that the p300/CBP binding looping fragments contain enhancer activities, suggesting that the formation of p300/CBP-mediated looping structures may recruit distal enhancers to create a concentration of factors for the transcription activation of genes that are involved in self-renewal and pluripotency. Overall, these results provide a total new insight into the transcriptional regulation mechanism of coactivators p300 and CBP in ESCs, which is important in maintaining self-renewal and pluripotency, by mediating the formation of higher order chromosome structures. © 2014 AlphaMed Press.

  4. p300-mediated acetylation of the Rothmund-Thomson-syndrome gene product RECQL4 regulates its subcellular localization

    Czech Academy of Sciences Publication Activity Database

    Dietschy, T.; Shevelev, Igor; Pena-Diaz, J.; Hühn, D.; Kuenzle, S.; Mak, R.; Miah, M.F.; Hess, D.; Fey, M.; Hottiger, M.O.; Janščák, Pavel; Stagljar, I.

    2009-01-01

    Roč. 122, Pt 8 (2009), s. 1258-1267 ISSN 0021-9533 Institutional research plan: CEZ:AV0Z50520514 Keywords : RECQL4 * RecQ helicases * Genome stability * p300 * Protein acetylation Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 6.144, year: 2009

  5. Loss of p300 and CBP disrupts histone acetylation at the mouse Sry promoter and causes XY gonadal sex reversal.

    Science.gov (United States)

    Carré, Gwenn-Aël; Siggers, Pam; Xipolita, Marilena; Brindle, Paul; Lutz, Beat; Wells, Sara; Greenfield, Andy

    2018-01-01

    CREB-binding protein (CBP, CREBBP, KAT3A) and its closely related paralogue p300 (EP300, KAT3B), together termed p300/CBP, are histone/lysine acetyl-transferases that control gene expression by modifying chromatin-associated proteins. Here, we report roles for both of these chromatin-modifying enzymes in mouse sex determination, the process by which the embryonic gonad develops into a testis or an ovary. By targeting gene ablation to embryonic gonadal somatic cells using an inducible Cre line, we show that gonads lacking either gene exhibit major abnormalities of XY gonad development at 14.5 dpc, including partial sex reversal. Embryos lacking three out of four functional copies of p300/Cbp exhibit complete XY gonadal sex reversal and have greatly reduced expression of the key testis-determining genes Sry and Sox9. An analysis of histone acetylation at the Sry promoter in mutant gonads at 11.5 dpc shows a reduction in levels of the positive histone mark H3K27Ac. Our data suggest a role for CBP/p300 in testis determination mediated by control of histone acetylation at the Sry locus and reveal a novel element in the epigenetic control of Sry and mammalian sex determination. They also suggest possible novel causes of human disorders of sex development (DSD). © The Author 2017. Published by Oxford University Press.

  6. E2A proteins enhance the histone acetyltransferase activity of the transcriptional co-activators CBP and p300.

    Science.gov (United States)

    Hyndman, Brandy D; Thompson, Patrick; Bayly, Richard; Côté, Graham P; LeBrun, David P

    2012-05-01

    The E2A gene encodes the E-protein transcription factors E12 and E47 that play critical roles in B-lymphopoiesis. A somatic chromosomal translocation detectable in 5% of cases of acute lymphoblastic leukemia (ALL) involves E2A and results in expression of the oncogenic transcription factor E2A-PBX1. CREB binding protein (CBP) and its close paralog p300 are transcriptional co-activators with intrinsic histone acetyltransferase (HAT) activity. We and others have shown that direct binding of an N-terminal transcriptional activation domain present in E12/E47 and E2A-PBX1 to the KIX domain of CBP/p300 contributes to E2A protein function. In the current work we show for the first time that the catalytic HAT activity of CBP/p300 is increased in the presence of residues 1-483 of E2A (i.e., the portion present in E2A-PBX1). The addition of purified, recombinant E2A protein to in vitro assays results in a two-fold augmentation of CBP/p300 HAT activity, whereas in vivo assays show a ten-fold augmentation of HAT-dependent transcriptional induction and a five-fold augmentation of acetylation of reporter plasmid-associated histone by CBP in response to co-transfected E2A. Our results indicate that the HAT-enhancing effect is independent of the well-documented E2A-CBP interaction involving the KIX domain and suggest a role for direct, perhaps low affinity binding of E2A to a portion of CBP that includes the HAT domain and flanking elements. Our findings add to a growing body of literature indicating that interactions between CBP/p300 and transcription factors can function in a specific manner to modulate HAT catalytic activity. Copyright © 2012 Elsevier B.V. All rights reserved.

  7. Amplitudes, acquisition and imaging

    Energy Technology Data Exchange (ETDEWEB)

    Bloor, Robert

    1998-12-31

    Accurate seismic amplitude information is important for the successful evaluation of many prospects and the importance of such amplitude information is increasing with the advent of time lapse seismic techniques. It is now widely accepted that the proper treatment of amplitudes requires seismic imaging in the form of either time or depth migration. A key factor in seismic imaging is the spatial sampling of the data and its relationship to the imaging algorithms. This presentation demonstrates that acquisition caused spatial sampling irregularity can affect the seismic imaging and perturb amplitudes. Equalization helps to balance the amplitudes, and the dealing strategy improves the imaging further when there are azimuth variations. Equalization and dealiasing can also help with the acquisition irregularities caused by shot and receiver dislocation or missing traces. 2 refs., 2 figs.

  8. Histone acetyltransferase p300 mediates histone acetylation of PS1 and BACE1 in a cellular model of Alzheimer's disease.

    Directory of Open Access Journals (Sweden)

    Xi Lu

    Full Text Available Epigenetic modifications, particularly histone acetylation, have been implicated in Alzheimer's disease (AD. While previous studies have suggested that histone hypoacetylation may regulate the expression of genes associated with memory and learning in AD, little is known about histone regulation of AD-related genes such as Presenilin 1(PS1 and beta-site amyloid precursor protein cleaving enzyme 1(BACE1. By utilizing neuroblastoma N2a cells transfected with Swedish mutated human amyloid precursor protein (APP (N2a/APPswe and wild-type APP (N2a/APPwt as cellular models of AD, we examined the alterations of histone acetylation at the promoter regions of PS1 and BACE1 in these cells. Our results revealed that histone H3 acetylation in PS1 and BACE1 promoters is markedly increased in N2a/APPswe cells when compared to N2a/APPwt cells and control cells (vector-transfected, respectively, causing the elevated expression of PS1 and BACE1. In addition, expression of histone acetyltransferase (HAT adenoviral E1A-associated 300-kDa protein (p300 is dramatically enhanced in N2a/APPswe cells compared to N2a/APPwt and control cells. We have further demonstrated the direct binding of p300 protein to the PS1 and BACE1 promoters in N2a/APPswe cells. The expression levels of H3 acetylation of the PS1 and BACE1 promoters and p300 protein, however, were found to be not significantly different in N2a/APPwt cells when compared to controls in our studies. Furthermore, curcumin, a natural selective inhibitor of p300 in HATs, significantly suppressed the expression of PS1 and BACE1 through inhibition of H3 acetylation in their promoter regions in N2a/APPswe cells. These findings indicated that histone acetyltransferase p300 plays a critical role in controlling the expression of AD-related genes through regulating the acetylation of their promoter regions, suggesting that p300 may represent a novel potential therapeutic target for AD.

  9. Neuromodulatory effects of caffeine and bromazepam on visual event-related potential (P300: a comparative study Efeitos neuromoduladores da cafeína e do bromazepam no potencial evocado visual relacionado a evento (P300: estudo comparativo

    Directory of Open Access Journals (Sweden)

    Mariana Montenegro

    2005-06-01

    Full Text Available The P300 component of the event-related potential (ERP is a general measurement of "cognitive efficiency". It is an index of the ability of an individual's central nervous system (CNS to process incoming information. OBJECTIVE: To compare the neuromodulatory effects of caffeine and bromazepam on the visual ERP (P300, in relation to a P300 normative database. METHOD: 15 right-handed individuals (7 male and 8 female, between 20 and 30 years of age, healthy, free of any cognitive impairment and not making use of psychoactive substances were studied. Participants were submitted to a visual discrimination task, which employed the "oddball" paradigm, after the administration of caffeine and bromazepam, in a randomized, double-blind design. RESULTS: Statistically significant differences were observed when the caffeine and bromazepam conditions were compared to the normative database. CONCLUSION: The present results suggest that caffeine and bromazepam have distinct modulatory effects on CNS functioning.O componente P300 do potencial evocado relacionado a evento é uma medida geral de "eficiência cognitiva" e um índice da qualidade do processamento e armazenamento de informações pelo sistema nervoso central (SNC. OBJETIVO: Comparar os efeitos neuromoduladores da cafeína e do bromazepam a partir do banco normativo do potencial evocado visual (P300. MÉTODO: 15 sujeitos destros (7 homens e 8 mulheres, entre 20 e 30 anos de idade, sadios, livres de qualquer déficit cognitivo e sem uso de substâncias psicotrópicas ou psicoativas foram estudados. Os sujeitos foram submetidos a uma tarefa de discriminação visual utilizando o paradigma "oddball", após a administração de uma cápsula de cafeína ou de bromazepam, em um desenho duplo-cego randomizado. RESULTADOS: Foram observadas diferenças estatisticamente significativas quando as condições cafeína e bromazepam foram comparadas com o banco normativo. CONCLUSÃO: Os resultados sugerem que a cafe

  10. An efficient word typing P300-BCI system using a modified T9 interface and random forest classifier.

    Science.gov (United States)

    Akram, Faraz; Han, Seung Moo; Kim, Tae-Seong

    2015-01-01

    A typical P300-based spelling brain computer interface (BCI) system types a single character with a character presentation paradigm and a P300 classification system. Lately, a few attempts have been made to type a whole word with the help of a smart dictionary that suggests some candidate words with the input of a few initial characters. In this paper, we propose a novel paradigm utilizing initial character typing with word suggestions and a novel P300 classifier to increase word typing speed and accuracy. The novel paradigm involves modifying the Text on 9 keys (T9) interface, which is similar to the keypad of a mobile phone used for text messaging. Users can type the initial characters using a 3×3 matrix interface and an integrated custom-built dictionary that suggests candidate words as the user types the initials. Then the user can select one of the given suggestions to complete word typing. We have adopted a random forest classifier, which significantly improves P300 classification accuracy by combining multiple decision trees. We conducted experiments with 10 subjects using the proposed BCI system. Our proposed paradigms significantly reduced word typing time and made word typing more convenient by outputting complete words with only a few initial character inputs. The conventional spelling system required an average time of 3.47 min per word while typing 10 random words, whereas our proposed system took an average time of 1.67 min per word, a 51.87% improvement, for the same words under the same conditions. Copyright © 2014 Elsevier Ltd. All rights reserved.

  11. Usage of drip drops as stimuli in an auditory P300 BCI paradigm.

    Science.gov (United States)

    Huang, Minqiang; Jin, Jing; Zhang, Yu; Hu, Dewen; Wang, Xingyu

    2018-02-01

    Recently, many auditory BCIs are using beeps as auditory stimuli, while beeps sound unnatural and unpleasant for some people. It is proved that natural sounds make people feel comfortable, decrease fatigue, and improve the performance of auditory BCI systems. Drip drop is a kind of natural sounds that makes humans feel relaxed and comfortable. In this work, three kinds of drip drops were used as stimuli in an auditory-based BCI system to improve the user-friendness of the system. This study explored whether drip drops could be used as stimuli in the auditory BCI system. The auditory BCI paradigm with drip-drop stimuli, which was called the drip-drop paradigm (DP), was compared with the auditory paradigm with beep stimuli, also known as the beep paradigm (BP), in items of event-related potential amplitudes, online accuracies and scores on the likability and difficulty to demonstrate the advantages of DP. DP obtained significantly higher online accuracy and information transfer rate than the BP ( p  < 0.05, Wilcoxon signed test; p  < 0.05, Wilcoxon signed test). Besides, DP obtained higher scores on the likability with no significant difference on the difficulty ( p  < 0.05, Wilcoxon signed test). The results showed that the drip drops were reliable acoustic materials as stimuli in an auditory BCI system.

  12. Motor imagery, P300 and error-related EEG-based robot arm movement control for rehabilitation purpose.

    Science.gov (United States)

    Bhattacharyya, Saugat; Konar, Amit; Tibarewala, D N

    2014-12-01

    The paper proposes a novel approach toward EEG-driven position control of a robot arm by utilizing motor imagery, P300 and error-related potentials (ErRP) to align the robot arm with desired target position. In the proposed scheme, the users generate motor imagery signals to control the motion of the robot arm. The P300 waveforms are detected when the user intends to stop the motion of the robot on reaching the goal position. The error potentials are employed as feedback response by the user. On detection of error the control system performs the necessary corrections on the robot arm. Here, an AdaBoost-Support Vector Machine (SVM) classifier is used to decode the 4-class motor imagery and an SVM is used to decode the presence of P300 and ErRP waveforms. The average steady-state error, peak overshoot and settling time obtained for our proposed approach is 0.045, 2.8% and 44 s, respectively, and the average rate of reaching the target is 95%. The results obtained for the proposed control scheme make it suitable for designs of prosthetics in rehabilitative applications.

  13. Analysis of the influence of bromazepam on cognitive performance through the visual evoked potential (P300 Análise da influência do bromazepam na performance cognitiva através do potencial evocado visual (P300

    Directory of Open Access Journals (Sweden)

    Fernanda Puga

    2005-06-01

    Full Text Available Benzodiazepines have been used in the pharmacological treatment of anxiety for over four decades. However, very few studies have combined bromazepam and event-related potentials (ERP. The present study aimed at investigating the modulatory effects of this drug on brain dynamics. Specifically, the effects of bromazepam (3mg on the P300 component of the ERP were tested in a double-blind experiment. The sample, consisting of 15 healthy subjects (7 male and 8 female, was submitted to a visual discrimination task, which employed the "oddball" paradigm. Electrophysiological (P300 and behavioral measures (stroop, digit span, and reaction time were analyzed across three experimental conditions: placebo 1, placebo 2, and bromazepam. Results suggest that the effects of bromazepam (3mg on cognitive processes are not apparent. In spite of what seems irrefutable in current literature, bromazepam did not produce evident effects on the behavioral and electrophysiological variables analyzed.Benzodiazepínicos têm sido utilizados no tratamento farmacológico da ansiedade há mais de quatro décadas. No entanto, poucos estudos têm combinado bromazepam e potencial evocado relacionado a evento (PRE. O presente estudo teve por objetivo investigar os efeitos modulatórios desta droga na dinâmica cerebral. Especificamente, os efeitos de 3mg de bromazepam no componente P300 do PRE foram analisados em um experimento duplo-cego. A amostra consistiu de 15 sujeitos sadios (7 homens e 8 mulheres, submetidos a uma tarefa de discriminação visual utilizando o paradigma "oddball". Medidas eletrofisiológicas (P300 e comportamentais (stroop, digit span, e tempo de reação foram analisadas em três condições experimentais: placebo 1, placebo 2 e bromazepam. Os resultados sugerem que os efeitos de 3mg de bromazepam em processos cognitivos não são aparentes. Apesar do que parece irrefutável na literatura, o bromazepam não produziu efeitos evidentes nas vari

  14. Avaliação auditiva central com BERA e P300 na Doença de Parkinson

    Directory of Open Access Journals (Sweden)

    Pineroli José C.A.

    2002-01-01

    Full Text Available Introdução: A Doença de Parkinson (DP é um dos distúrbios do movimento mais encontrados na população idosa. Cursa com perda progressiva e irreversível de células da substância negra (locus niger do mesencéfalo, o que resultará numa diminuição da produção de dopamina, levando à sintomatologia da DP. Objetivo: Averiguar a relevância de testes eletrofisiológicos, capazes de monitorar a integridade funcional das vias cerebrais, no diagnóstico e/ou prognóstico de pacientes com DP, uma vez que tais testes não-invasivos são de fácil aplicabilidade, rápidos e facilmente compreendidos por quem participa de sua aplicação. Forma de estudo: Prospectivo clínico randomizado. Material e Método: Grupo de 32 pacientes com diagnóstico prévio de DP, submetidos aos testes de potencial evocado BERA e P300. Pacientes de ambos os sexos, entre 44 e 85 anos, com tempo de doença variando de 8 meses a 21 anos de evolução. Resultados: os valores do BERA e do P300 encontrados em pacientes com DP não se mostraram diferentes dos limites de normalidade para a idade. Conclusão: Observou-se integridade das vias auditivas em pacientes portadores de DP. Uma vez que a latência do P300 aumenta de forma linear com a idade, a partir dos 45 anos, aceitando-se um aumento de 1 a 1,5ms por ano¹; observou-se integridade nas vias cerebrais que refletem a habilidade de performance cognitiva em pacientes portadores de DP sem comprometimento demencial exuberante.

  15. Recruitment of activated IRF-3 and CBP/p300 to herpes simplex virus ICP0 nuclear foci: Potential role in blocking IFN-β induction

    International Nuclear Information System (INIS)

    Melroe, Gregory T.; Silva, Lindsey; Schaffer, Priscilla A.; Knipe, David M.

    2007-01-01

    The host innate response to viral infection includes the production of interferons, which is dependent on the coordinated activity of multiple transcription factors. Herpes simplex virus 1 (HSV-1) has been shown to block efficient interferon expression by multiple mechanisms. We and others have demonstrated that HSV-1 can inhibit the transcription of genes promoted by interferon regulatory factor-3 (IRF-3), including interferon beta (IFN-β), and that the immediate-early ICP0 protein is sufficient for this function. However, the exact mechanism by which ICP0 blocks IRF-3 activity has yet to be determined. Unlike some other viral proteins that inhibit IRF-3 activity, ICP0 does not appear to affect phosphorylation and dimerization of IRF-3. Here, we show that a portion of activated IRF-3 co-localizes with nuclear foci containing ICP0 at early times after virus infection. Co-localization to ICP0-containing foci is also seen with the IRF-3-binding partners and transcriptional co-activators, CBP and p300. In addition, using immunoprecipitation of infected cell lysates, we can immunoprecipitate a complex containing ICP0, IRF-3, and CBP. Thus we hypothesize that ICP0 recruits activated IRF-3 and CBP/p300 to nuclear structures, away from the host chromatin. This leads to the inactivation and accelerated degradation of IRF-3, resulting in reduced transcription of IFN-β and an inhibition of the host response. Therefore, ICP0 provides an example of how viruses can block IFN-β induction by sequestration of important transcription factors essential for the host response

  16. Interactions of Histone Acetyltransferase p300 with the Nuclear Proteins Histone and HMGB1, As Revealed by Single Molecule Atomic Force Spectroscopy.

    Science.gov (United States)

    Banerjee, S; Rakshit, T; Sett, S; Mukhopadhyay, R

    2015-10-22

    One of the important properties of the transcriptional coactivator p300 is histone acetyltransferase (HAT) activity that enables p300 to influence chromatin action via histone modulation. p300 can exert its HAT action upon the other nuclear proteins too--one notable example being the transcription-factor-like protein HMGB1, which functions also as a cytokine, and whose accumulation in the cytoplasm, as a response to tissue damage, is triggered by its acetylation. Hitherto, no information on the structure and stability of the complexes between full-length p300 (p300FL) (300 kDa) and the histone/HMGB1 proteins are available, probably due to the presence of unstructured regions within p300FL that makes it difficult to be crystallized. Herein, we have adopted the high-resolution atomic force microscopy (AFM) approach, which allows molecularly resolved three-dimensional contour mapping of a protein molecule of any size and structure. From the off-rate and activation barrier values, obtained using single molecule dynamic force spectroscopy, the biochemical proposition of preferential binding of p300FL to histone H3, compared to the octameric histone, can be validated. Importantly, from the energy landscape of the dissociation events, a model for the p300-histone and the p300-HMGB1 dynamic complexes that HAT forms, can be proposed. The lower unbinding forces of the complexes observed in acetylating conditions, compared to those observed in non-acetylating conditions, indicate that upon acetylation, p300 tends to weakly associate, probably as an outcome of charge alterations on the histone/HMGB1 surface and/or acetylation-induced conformational changes. To our knowledge, for the first time, a single molecule level treatment of the interactions of HAT, where the full-length protein is considered, is being reported.

  17. The impact of prior knowledge from participant instructions in a mock crime P300 Concealed Information Test.

    Science.gov (United States)

    Winograd, Michael R; Rosenfeld, J Peter

    2014-12-01

    In P300-Concealed Information Tests used with mock crime scenarios, the amount of detail revealed to a participant prior to the commission of the mock crime can have a serious impact on a study's validity. We predicted that exposure to crime details through instructions would bias detection rates toward enhanced sensitivity. In a 2 × 2 factorial design, participants were either informed (through mock crime instructions) or naïve as to the identity of a to-be-stolen item, and then either committed (guilty) or did not commit (innocent) the crime. Results showed that prior knowledge of the stolen item was sufficient to cause 69% of innocent-informed participants to be incorrectly classified as guilty. Further, we found a trend toward enhanced detection rate for guilty-informed participants over guilty-naïve participants. Results suggest that revealing details to participants through instructions biases detection rates in the P300-CIT toward enhanced sensitivity. Copyright © 2014 Elsevier B.V. All rights reserved.

  18. Asynchronous P300-based brain-computer interface to control a virtual environment: initial tests on end users.

    Science.gov (United States)

    Aloise, Fabio; Schettini, Francesca; Aricò, Pietro; Salinari, Serenella; Guger, Christoph; Rinsma, Johanna; Aiello, Marco; Mattia, Donatella; Cincotti, Febo

    2011-10-01

    Motor disability and/or ageing can prevent individuals from fully enjoying home facilities, thus worsening their quality of life. Advances in the field of accessible user interfaces for domotic appliances can represent a valuable way to improve the independence of these persons. An asynchronous P300-based Brain-Computer Interface (BCI) system was recently validated with the participation of healthy young volunteers for environmental control. In this study, the asynchronous P300-based BCI for the interaction with a virtual home environment was tested with the participation of potential end-users (clients of a Frisian home care organization) with limited autonomy due to ageing and/or motor disabilities. System testing revealed that the minimum number of stimulation sequences needed to achieve correct classification had a higher intra-subject variability in potential end-users with respect to what was previously observed in young controls. Here we show that the asynchronous modality performed significantly better as compared to the synchronous mode in continuously adapting its speed to the users' state. Furthermore, the asynchronous system modality confirmed its reliability in avoiding misclassifications and false positives, as previously shown in young healthy subjects. The asynchronous modality may contribute to filling the usability gap between BCI systems and traditional input devices, representing an important step towards their use in the activities of daily living.

  19. An evaluation of training with an auditory P300 brain-computer interface for the Japanese Hiragana syllabary

    Directory of Open Access Journals (Sweden)

    Sebastian Halder

    2016-09-01

    Full Text Available Gaze-independent brain-computer interfaces (BCIs are a possible communication channel for persons with paralysis. We investigated if it is possible to use auditory stimuli to create a BCI for the Japanese Hiragana syllabary, which has 46 Hiragana characters. Additionally, we investigated if training has an effect on accuracy despite the high amount of different stimuli involved. Able-bodied participants (N=6 were asked to select 25 syllables (out of fifty possible choices using a two step procedure: first the consonant (ten choices and then the vowel (five choices. This was repeated on three separate days. Additionally, a person with spinal cord injury (SCI participated in the experiment. Four out of six healthy participants reached Hiragana syllable accuracies above 70% and the information transfer rate increased from 1.7 bits/min in the first session to 3.2 bits/min in the third session. The accuracy of the participant with SCI increased from 12% (0.2 bits/min to 56% (2 bits/min in session three. Reliable selections from a 10×5 matrix using auditory stimuli were possible and performance is increased by training. We were able to show that auditory P300 BCIs can be used for communication with up to fifty symbols. This enables the use of the technology of auditory P300 BCIs with a variety of applications.

  20. The Tax oncogene enhances ELL incorporation into p300 and P-TEFb containing protein complexes to activate transcription.

    Science.gov (United States)

    Fufa, Temesgen D; Byun, Jung S; Wakano, Clay; Fernandez, Alfonso G; Pise-Masison, Cynthia A; Gardner, Kevin

    2015-09-11

    The eleven-nineteen lysine-rich leukemia protein (ELL) is a key regulator of RNA polymerase II mediated transcription. ELL facilitates RNA polymerase II transcription pause site entry and release by dynamically interacting with p300 and the positive transcription elongation factor b (P-TEFb). In this study, we investigated the role of ELL during the HTLV-1 Tax oncogene induced transactivation. We show that ectopic expression of Tax enhances ELL incorporation into p300 and P-TEFb containing transcriptional complexes and the subsequent recruitment of these complexes to target genes in vivo. Depletion of ELL abrogates Tax induced transactivation of the immediate early genes Fos, Egr2 and NF-kB, suggesting that ELL is an essential cellular cofactor of the Tax oncogene. Thus, our study identifies a novel mechanism of ELL-dependent transactivation of immediate early genes by Tax and provides the rational for further defining the genome-wide targets of Tax and ELL. Published by Elsevier Inc.

  1. Control or non-control state: that is the question! An asynchronous visual P300-based BCI approach

    Science.gov (United States)

    Pinegger, Andreas; Faller, Josef; Halder, Sebastian; Wriessnegger, Selina C.; Müller-Putz, Gernot R.

    2015-02-01

    Objective. Brain-computer interfaces (BCI) based on event-related potentials (ERP) were proven to be a reliable synchronous communication method. For everyday life situations, however, this synchronous mode is impractical because the system will deliver a selection even if the user is not paying attention to the stimulation. So far, research into attention-aware visual ERP-BCIs (i.e., asynchronous ERP-BCIs) has led to variable success. In this study, we investigate new approaches for detection of user engagement. Approach. Classifier output and frequency-domain features of electroencephalogram signals as well as the hybridization of them were used to detect the user's state. We tested their capabilities for state detection in different control scenarios on offline data from 21 healthy volunteers. Main results. The hybridization of classifier output and frequency-domain features outperformed the results of the single methods, and allowed building an asynchronous P300-based BCI with an average correct state detection accuracy of more than 95%. Significance. Our results show that all introduced approaches for state detection in an asynchronous P300-based BCI can effectively avoid involuntary selections, and that the hybrid method is the most effective approach.

  2. Implementation of active electrodes on a brain-computer interface and its application as P300 speller

    International Nuclear Information System (INIS)

    Aguero Rojas, Eliecer

    2013-01-01

    A brain computer interface has implemented using open hardware called Modular EEG, created by The OpenEEG Project and distributed by the company Olimex Ltd. That hardware is modified to use active electrodes, instead of passive electrodes, for acquiring electroencephalographic signals. The application has been given to the interface has been a speller P300; for which has used the BC12000 open software that has the necessary configuration for the application. P300 speller has used a protocol in each session so that could be standardize the method to different users. Valuing the results with three neuropsychological tests, was within the objectives; however, has not been achieved by the limitation in time of project implementation. A brain computer interface has been used with passive electrodes; implemented in the same way that the BCI with active electrodes; and has worked better than the interface with active electrodes. One of the major advantages that has been observed of passive electrodes on the actives has been the size of the same, because the liabilities are smaller and therefore, easier to place preventing the hair of the user, which increases the noise in the signal. (author) [es

  3. Complex network inference from P300 signals: Decoding brain state under visual stimulus for able-bodied and disabled subjects

    Science.gov (United States)

    Gao, Zhong-Ke; Cai, Qing; Dong, Na; Zhang, Shan-Shan; Bo, Yun; Zhang, Jie

    2016-10-01

    Distinguishing brain cognitive behavior underlying disabled and able-bodied subjects constitutes a challenging problem of significant importance. Complex network has established itself as a powerful tool for exploring functional brain networks, which sheds light on the inner workings of the human brain. Most existing works in constructing brain network focus on phase-synchronization measures between regional neural activities. In contrast, we propose a novel approach for inferring functional networks from P300 event-related potentials by integrating time and frequency domain information extracted from each channel signal, which we show to be efficient in subsequent pattern recognition. In particular, we construct brain network by regarding each channel signal as a node and determining the edges in terms of correlation of the extracted feature vectors. A six-choice P300 paradigm with six different images is used in testing our new approach, involving one able-bodied subject and three disabled subjects suffering from multiple sclerosis, cerebral palsy, traumatic brain and spinal-cord injury, respectively. We then exploit global efficiency, local efficiency and small-world indices from the derived brain networks to assess the network topological structure associated with different target images. The findings suggest that our method allows identifying brain cognitive behaviors related to visual stimulus between able-bodied and disabled subjects.

  4. Mono-ADP-ribosylation of histone 3 at arginine-117 promotes proliferation through its interaction with P300.

    Science.gov (United States)

    Ling, Feng; Tang, Yi; Li, Ming; Li, Qing-Shu; Li, Xian; Yang, Lian; Zhao, Wei; Jin, Cong-Cong; Zeng, Zhen; Liu, Chang; Wu, Cheng-Fang; Chen, Wen-Wen; Lin, Xiao; Wang, Ya-Lan; Threadgill, Michael D

    2017-09-22

    Relatively little attention has been paid to ADP-ribosylated modifications of histones, especially to mono-ADP-ribosylation. As an increasing number of mono-ADP-ribosyltransferases have been identified in recent studies, the functions of mono-ADP-ribosylated proteins have aroused research interest. In particular, histones are substrates of some mono-ADP-ribosyltransferases and mono-ADP-ribosylated histone have been detected in physiological or pathological processes. In this research, arginine-117 (Arg-117; R-117) of hsitone3(H3) is identified as the a site of mono-ADP-ribosylation in colon carcinoma(the first such site to be identified); this posttranslational modification may promote the proliferation of colon carcinoma cells in vitro and in vivo . Using a point-mutant lentivirus transfection and using an activator of P300 allowed us to observe the mono-ADP-ribosylation at H3R117 and enhancement of the activity of P300 to up-regulate the level of acetylated β-catenin, which could increase the expression of c-myc and cyclin D1.

  5. Effects of caffeine on visual evoked potencial (P300 and neuromotor performance Efeitos da ingestão de cafeína no potencial evocado visual (p300 e no desempenho neuromotor

    Directory of Open Access Journals (Sweden)

    Andréa Camaz Deslandes

    2004-06-01

    Full Text Available The stimulant effects of caffeine on cognitive performance have been widely investigated. The visual evoked potential, specially the P300 component, has been used in studies that explain the stimulant mechanisms of caffeine through neurophysiological methods. In this context, the present study aimed to investigate electrophysiological changes (P300 latency and modification of cognitive and motor performance produced by caffeine. Fifteen healthy volunteers, 9 women and 6 men (26 ± 5 years, 67 ± 12.5kg were submitted three times to the following procedure: electroencefalographic recording, Word Color Stroop Test, and visual discrimination task. Subjects took a gelatin caffeine capsule (400 mg or a placebo (P1 and P2, in a randomized, crossover, double-blind design. A one-factor ANOVA and Tukey’ post hoc test were used to compare dependent variables on the C, P1 and P2 moments. The statistical analyses indicated a non-significant decrease in reaction time, Stroop execution time and latency at Cz on the caffeine moment when compared to the others. Moreover, a non-significant increase in Stroop raw score and latency at Pz could be observed. The only significant result was found at Fz. These findings suggest that the positive tendency of caffeine to improve cognitive performance is probably associated with changes in the frontal cortex, a widely recognized attention area.Os efeitos estimulantes da cafeína no desempenho cognitivo vêm sendo amplamente investigados. O potencial evocado visual (P300 tem sido empregado em estudos recentes que buscam elucidar os mecanismos excitatórios da cafeína através de métodos neurofisiológicos. Neste contexto, o presente estudo objetivou examinar as variações geradas pela cafeína em respostas eletrofisiológicas (latência do P300 e determinar modificações no desempenho cognitivo e motor. Para tanto, 15 indivíduos hígidos, sendo 9 mulheres e 6 homens (26 ± 5 anos, 67 ± 12,5 kg foram submetidos por

  6. Roles of p300 and cyclic adenosine monophosphate response element binding protein in high glucose-induced hypoxia-inducible factor 1α inactivation under hypoxic conditions.

    Science.gov (United States)

    Ding, Lingtao; Yang, Minlie; Zhao, Tianlan; Lv, Guozhong

    2017-05-01

    Given the high prevalence of diabetes and burn injuries worldwide, it is essential to dissect the underlying mechanism of delayed burn wound healing in diabetes patients, especially the high glucose-induced hypoxia-inducible factor 1 (HIF-1)-mediated transcription defects. Human umbilical vein endothelial cells were cultured with low or high concentrations of glucose. HIF-1α-induced vascular endothelial growth factor (VEGF) transcription was measured by luciferase assay. Immunofluorescence staining was carried out to visualize cyclic adenosine monophosphate response element binding protein (CREB) localization. Immunoprecipitation was carried out to characterize the association between HIF-1α/p300/CREB. To test whether p300, CREB or p300+CREB co-overexpression was sufficient to rescue the HIF-1-mediated transcription defect after high glucose exposure, p300, CREB or p300+CREB co-overexpression were engineered, and VEGF expression was quantified. Finally, in vitro angiogenesis assay was carried out to test whether the high glucose-induced angiogenesis defect is rescuable by p300 and CREB co-overexpression. Chronic high glucose treatment resulted in impaired HIF-1-induced VEGF transcription and CREB exclusion from the nucleus. P300 or CREB overexpression alone cannot rescue high glucose-induced HIF-1α transcription defects. In contrast, co-overexpression of p300 and CREB dramatically ameliorated high glucose-induced impairment of HIF-1-mediated VEGF transcription, as well as in vitro angiogenesis. Finally, we showed that co-overexpression of p300 and CREB rectifies the dissociation of HIF-1α-p300-CREB protein complex in chronic high glucose-treated cells. Both p300 and CREB are required for the function integrity of HIF-1α transcription machinery and subsequent angiogenesis, suggesting future studies to improve burn wound healing might be directed to optimization of the interaction between p300, CREB and HIF-1α. © 2016 The Authors. Journal of Diabetes

  7. Improving the accessibility at home: implementation of a domotic application using a p300-based brain computer interface system

    Directory of Open Access Journals (Sweden)

    Rebeca Corralejo Palacios

    2012-05-01

    Full Text Available The aim of this study was to develop a Brain Computer Interface (BCI application to control domotic devices usually present at home. Previous studies have shown that people with severe disabilities, both physical and cognitive ones, do not achieve high accuracy results using motor imagery-based BCIs. To overcome this limitation, we propose the implementation of a BCI application using P300 evoked potentials, because neither extensive training nor extremely high concentration level are required for this kind of BCIs. The implemented BCI application allows to control several devices as TV, DVD player, mini Hi-Fi system, multimedia hard drive, telephone, heater, fan and lights. Our aim is that potential users, i.e. people with severe disabilities, are able to achieve high accuracy. Therefore, this domotic BCI application is useful to increase

  8. AGO2 Negatively Regulates Type I Interferon Signaling Pathway by Competition Binding IRF3 with CBP/p300

    Directory of Open Access Journals (Sweden)

    Shengyu Wang

    2017-05-01

    Full Text Available Viral infection triggers a series of signaling cascades and host innate immune responses, including interferon (IFN production, which depends on coordinated activity of multiple transcription factors. IFN regulatory factor 3 (IRF3 and transcriptional coactivator CREB binding protein (CBP and/or p300 are core factors that participate in transcriptional complex formation in the nucleus. In general, cells balance the production of IFNs through suppressive and stimulative mechanisms, but viral infections can disrupt such equilibrium. This study determined that H5N1 viral infection reduced the distribution of human argonaute 2 (AGO2 in A549 cell nucleus. AGO2 did not block phosphorylation, nuclear translocation, and DNA binding ability of IRF3 but inhibited its association with CBP. Therefore, this newly revealed mechanism shows that cellular response leads to transfer of AGO2 from cell nucleus and promotes IFN-β expression to increase host survival during viral infection.

  9. Selección de Canales en Sistemas BCI basados en Potenciales P300 mediante Inteligencia de Enjambre

    Directory of Open Access Journals (Sweden)

    V. Martínez-Cagigal

    2017-10-01

    Full Text Available Resumen: Los sistemas Brain-Computer Interface (BCI se definen como sistemas de comunicación que monitorizan la actividad cerebral y traducen determinadas características, correspondientes a las intenciones del usuario, en comandos de control de un dispositivo. La selección de canales en los sistemas BCI es fundamental para evitar el sobre-entrenamiento del clasificador, reducir la carga computacional y aumentar la comodidad del usuario. A pesar de que se han desarrollado varios algoritmos con anterioridad para tal fin, las metaheurísticas basadas en inteligencia de enjambre aún no han sido suficientemente explotadas en los sistemas BCI basados en potenciales P300. En este estudio se muestra una comparativa entre cinco métodos de enjambre, basados en el comportamiento de sistemas biológicos, aplicados con el objetivo de optimizar la selección de canales en este tipo de sistemas. Los métodos se han evaluado sobre la base de datos de la “III BCI Competition 2005”, reportando precisiones similares o, en algunos casos, incluso más altas que las obtenidas sin realizar ningún tipo de selección. Dado que los cinco métodos se han demostrado capaces de disminuir drásticamente los 64 canales originales a menos de la mitad sin comprometer el rendimiento del sistema, así como de superar el conjunto típico de 8 canales y el método backward elimination, se concluye que todos ellos son adecuados para su aplicación en la selección de canales en sistemas P300-BCI. Abstract: Brain-Computer Interfaces (BCI are direct communication pathways between the brain and the environment that translate certain features, which correspond to users’ intentions, into device control commands. Channel selection in BCI systems is essential to avoid over-fitting, to reduce the computational cost and to increase the users’ comfort. Although several algorithms have previously developed for that purpose

  10. Optimizing the stimulus presentation paradigm design for the P300-based brain-computer interface using performance prediction.

    Science.gov (United States)

    Mainsah, B O; Reeves, G; Collins, L M; Throckmorton, C S

    2017-08-01

    The role of a brain-computer interface (BCI) is to discern a user's intended message or action by extracting and decoding relevant information from brain signals. Stimulus-driven BCIs, such as the P300 speller, rely on detecting event-related potentials (ERPs) in response to a user attending to relevant or target stimulus events. However, this process is error-prone because the ERPs are embedded in noisy electroencephalography (EEG) data, representing a fundamental problem in communication of the uncertainty in the information that is received during noisy transmission. A BCI can be modeled as a noisy communication system and an information-theoretic approach can be exploited to design a stimulus presentation paradigm to maximize the information content that is presented to the user. However, previous methods that focused on designing error-correcting codes failed to provide significant performance improvements due to underestimating the effects of psycho-physiological factors on the P300 ERP elicitation process and a limited ability to predict online performance with their proposed methods. Maximizing the information rate favors the selection of stimulus presentation patterns with increased target presentation frequency, which exacerbates refractory effects and negatively impacts performance within the context of an oddball paradigm. An information-theoretic approach that seeks to understand the fundamental trade-off between information rate and reliability is desirable. We developed a performance-based paradigm (PBP) by tuning specific parameters of the stimulus presentation paradigm to maximize performance while minimizing refractory effects. We used a probabilistic-based performance prediction method as an evaluation criterion to select a final configuration of the PBP. With our PBP, we demonstrate statistically significant improvements in online performance, both in accuracy and spelling rate, compared to the conventional row-column paradigm. By accounting for

  11. Optimizing the stimulus presentation paradigm design for the P300-based brain-computer interface using performance prediction

    Science.gov (United States)

    Mainsah, B. O.; Reeves, G.; Collins, L. M.; Throckmorton, C. S.

    2017-08-01

    Objective. The role of a brain-computer interface (BCI) is to discern a user’s intended message or action by extracting and decoding relevant information from brain signals. Stimulus-driven BCIs, such as the P300 speller, rely on detecting event-related potentials (ERPs) in response to a user attending to relevant or target stimulus events. However, this process is error-prone because the ERPs are embedded in noisy electroencephalography (EEG) data, representing a fundamental problem in communication of the uncertainty in the information that is received during noisy transmission. A BCI can be modeled as a noisy communication system and an information-theoretic approach can be exploited to design a stimulus presentation paradigm to maximize the information content that is presented to the user. However, previous methods that focused on designing error-correcting codes failed to provide significant performance improvements due to underestimating the effects of psycho-physiological factors on the P300 ERP elicitation process and a limited ability to predict online performance with their proposed methods. Maximizing the information rate favors the selection of stimulus presentation patterns with increased target presentation frequency, which exacerbates refractory effects and negatively impacts performance within the context of an oddball paradigm. An information-theoretic approach that seeks to understand the fundamental trade-off between information rate and reliability is desirable. Approach. We developed a performance-based paradigm (PBP) by tuning specific parameters of the stimulus presentation paradigm to maximize performance while minimizing refractory effects. We used a probabilistic-based performance prediction method as an evaluation criterion to select a final configuration of the PBP. Main results. With our PBP, we demonstrate statistically significant improvements in online performance, both in accuracy and spelling rate, compared to the conventional

  12. Does chronic exposure to mobile phones affect cognition?

    Science.gov (United States)

    Mohan, Mamta; Khaliq, Farah; Panwar, Aprajita; Vaney, Neelam

    2016-01-01

    Summary Mobile phones form an integral part of our modern lifestyle. Following the drastic rise in mobile phone use in recent years, it has become important to study its potential public health impact. Amongst the various mobile phone health hazards, the most alarming is the possible effect on the brain. The aim of the present study was to explore whether chronic exposure to mobile phones affects cognition. Ninety subjects aged 17–25 years with normal hearing were recruited for the study and divided into three groups according to their duration of mobile phone use. No significant differences in N100, P200, N200, P300 latencies or N2-P300 amplitude were observed. Our results suggest that chronic mobile phone exposure does not have detrimental effects on cognition. PMID:27027894

  13. Preliminary investigation of plasma levels of sex hormones and human growth factor(s, and P300 latency as correlates to cognitive decline as a function of gender

    Directory of Open Access Journals (Sweden)

    Kerner Mallory M

    2009-07-01

    Full Text Available Abstract Background Aging is marked by declines in levels of many sex hormones and growth factors, as well as in cognitive function. The P300 event-related potential has been established as a predictor of cognitive decline. We decided to determine if this measure, as well as 2 standard tests of memory and attention, may be correlated with serum levels of sex hormones and growth factors, and if there are any generalizations that could be made based on these parameters and the aging process. Findings In this large clinically based preliminary study several sex-stratified associations between hormone levels and cognition were observed, including (1 for males aged 30 to 49, both IGF-1 and IGFBP-3 significantly associated negatively with prolonged P300 latency; (2 for males aged 30 to 49, the spearman correlation between prolonged P300 latency and low free testosterone was significant; (3 for males aged 60 to 69, there was a significant negative correlation between P300 latency and DHEA levels; (4 for females aged 50 to 59 IGFBP-3 significantly associated negatively with prolonged P300 latency; (5 for females at all age periods, estrogen and progesterone were uncorrelated with P300 latency; and (6 for females aged 40 to 69, there was significant negative correlation between DHEA levels and P300 latency. Moreover there were no statistically significant correlations between any hormone and Wechsler Memory Scale-III (WMS-111. However, in females, there was a significant positive correlation between estrogen levels and the number of Attention Deficit Disorder (ADD complaints. Conclusion Given certain caveats including confounding factors involving psychiatric and other chronic diseases as well as medications, the results may still have important value. If these results could be confirmed in a more rigorously controlled investigation, it may have important value in the diagnosis, prevention and treatment of cognitive impairments and decline.

  14. The Acetyltransferase p300/CBP-Associated Factor Is a p53 Target Gene in Breast Tumor Cells

    Directory of Open Access Journals (Sweden)

    George S. Watts

    2004-05-01

    Full Text Available p300/CBP-associated factor (PCAF is a coactivator of the tumor suppressor, p53. PCAF participates in p53's transactivation of target genes through acetylation of both bound p53 and histones within p53 target promoters. Using microarrays, we discovered that PCAF itself is induced by p53 in a panel of breast tumor cell lines. Two p53 mutant breast tumor cell lines, BT-549 and UACC-1179, were chosen for further study of PCAF induction by wild-type p53. PCAF induction following adenoviral transduction of p53 expression was confirmed with real-time polymerase chain reaction in a time course experiment. Chromatin immunoprecipitation experiments then showed that PCAF induction was associated with increased p53 binding to the PCAF promoter, which contains p53 consensus-binding sites. PCAF induction by p53 activity was further demonstrated in wild-type p53 MCF10A cells when PCAF expression was induced following activation of endogenous wild-type p53 with doxorubicin in a dose- and time-dependent manner. Furthermore, the doxorubicin-induced increase in PCAF expression was blocked by pretreatment of the MCF10A cells with siRNA (small interfering RNA targeted against p53 mRNA. Taken together, the results show that PCAF expression can be induced by wild-type p53.

  15. An efficient words typing P300-BCI system using a modified T9 interface and random forest classifier.

    Science.gov (United States)

    Akram, Faraz; Han, Hee-Sok; Jeon, Hyun Jae; Park, Kyungmo; Park, Seung-Hun; Cho, Jinsung; Kim, Tae-Seong

    2013-01-01

    The conventional P300-based character spelling BCI system consists of a character presentation paradigm and a classification system. In this paper, we propose modifications to both in order to increase the word typing speed and accuracy. In the paradigm part, we have modified the T9 (Text on Nine keys) interface which is similar to the keypad of mobile phones being used for text messaging. Then we have integrated a custom-built dictionary to give word suggestions to a user while typing. The user can select one out of the given suggestions to complete word typing. Our proposed paradigms significantly reduce the word typing time and make words typing more convenient by typing complete words with only few initial character spellings. In the classification part we have adopted a Random Forest (RF) classifier. The RF improves classification accuracy by combining multiple decision trees. We conducted experiments with five subjects using the proposed BCI system. Our results demonstrate that our system increases typing speed significantly: our proposed system took an average time of 1.83 minutes per word, while typing ten random words, whereas the conventional spelling required 3.35 minutes for the same words under the same conditions, decreasing the typing time by 45.37%.

  16. Structural basis of CBP/p300 recruitment in leukemia induction by E2A-PBX1.

    Science.gov (United States)

    Denis, Christopher M; Chitayat, Seth; Plevin, Michael J; Wang, Feng; Thompson, Patrick; Liu, Shuang; Spencer, Holly L; Ikura, Mitsuhiko; LeBrun, David P; Smith, Steven P

    2012-11-08

    E-proteins are critical transcription factors in B-cell lymphopoiesis. E2A, 1 of 3 E-protein-encoding genes, is implicated in the induction of acute lymphoblastic leukemia through its involvement in the chromosomal translocation 1;19 and consequent expression of the E2A-PBX1 oncoprotein. An interaction involving a region within the N-terminal transcriptional activation domain of E2A-PBX1, termed the PCET motif, which has previously been implicated in E-protein silencing, and the KIX domain of the transcriptional coactivator CBP/p300, critical for leukemogenesis. However, the structural details of this interaction remain unknown. Here we report the structure of a 1:1 complex between PCET motif peptide and the KIX domain. Residues throughout the helical PCET motif that contact the KIX domain are important for both binding KIX and bone marrow immortalization by E2A-PBX1. These results provide molecular insights into E-protein-driven differentiation of B-cells and the mechanism of E-protein silencing, and reveal the PCET/KIX interaction as a therapeutic target for E2A-PBX1-induced leukemia.

  17. Hepatitis C virus core protein regulates p300/CBP co-activation function. Possible role in the regulation of NF-AT1 transcriptional activity

    International Nuclear Information System (INIS)

    Gomez-Gonzalo, Marta; Benedicto, Ignacio; Carretero, Marta; Lara-Pezzi, Enrique; Maldonado-Rodriguez, Alejandra; Moreno-Otero, Ricardo; Lai, Michael M.C.; Lopez-Cabrera, Manuel

    2004-01-01

    Hepatitis C virus (HCV) core is a viral structural protein; it also participates in some cellular processes, including transcriptional regulation. However, the mechanisms of core-mediated transcriptional regulation remain poorly understood. Oncogenic virus proteins often target p300/CBP, a known co-activator of a wide variety of transcription factors, to regulate the expression of cellular and viral genes. Here we demonstrate, for the first time, that HCV core protein interacts with p300/CBP and enhances both its acetyl-transferase and transcriptional activities. In addition, we demonstrate that nuclear core protein activates the NH 2 -terminal transcription activation domain (TAD) of NF-AT1 in a p300/CBP-dependent manner. We propose a model in which core protein regulates the co-activation function of p300/CBP and activates NF-AT1, and probably other p300/CBP-regulated transcription factors, by a novel mechanism involving the regulation of the acetylation state of histones and/or components of the transcriptional machinery

  18. A comparison of recording modalities of P300 event-related potentials (ERP) for brain-computer interface (BCI) paradigm.

    Science.gov (United States)

    Mayaud, L; Congedo, M; Van Laghenhove, A; Orlikowski, D; Figère, M; Azabou, E; Cheliout-Heraut, F

    2013-10-01

    A brain-computer interface aims at restoring communication and control in severely disabled people by identification and classification of EEG features such as event-related potentials (ERPs). The aim of this study is to compare different modalities of EEG recording for extraction of ERPs. The first comparison evaluates the performance of six disc electrodes with that of the EMOTIV headset, while the second evaluates three different electrode types (disc, needle, and large squared electrode). Ten healthy volunteers gave informed consent and were randomized to try the traditional EEG system (six disc electrodes with gel and skin preparation) or the EMOTIV Headset first. Together with the six disc electrodes, a needle and a square electrode of larger surface were simultaneously recording near lead Cz. Each modality was evaluated over three sessions of auditory P300 separated by one hour. No statically significant effect was found for the electrode type, nor was the interaction between electrode type and session number. There was no statistically significant difference of performance between the EMOTIV and the six traditional EEG disc electrodes, although there was a trend showing worse performance of the EMOTIV headset. However, the modality-session interaction was highly significant (P<0.001) showing that, while the performance of the six disc electrodes stay constant over sessions, the performance of the EMOTIV headset drops dramatically between 2 and 3h of use. Finally, the evaluation of comfort by participants revealed an increasing discomfort with the EMOTIV headset starting with the second hour of use. Our study does not recommend the use of one modality over another based on performance but suggests the choice should be made on more practical considerations such as the expected length of use, the availability of skilled labor for system setup and above all, the patient comfort. Copyright © 2013 Elsevier Masson SAS. All rights reserved.

  19. A study of cognitive fatigue in Multiple Sclerosis with novel clinical and electrophysiological parameters utilizing the event related potential P300.

    Science.gov (United States)

    Chinnadurai, Somasundaram Aadhimoolam; Venkatesan, Srinivasan Avathvadi; Shankar, Gobinathan; Samivel, Balasubramanian; Ranganathan, Lakshmi Narasimhan

    2016-11-01

    Although cognitive fatigue plays a significant part in Multiple Sclerosis (MS) related impairment, knowledge regarding it is largely lacking. Until now, not many tools are available to a clinician to detect cognitive fatigue. The subjective tools of fatigue have never been reliable.tabl OBJECTIVES: To assess the prevalence and clinical/ demographic profile of cognitive fatigue in MS using novel clinical and electrophysiological measures and to find their accuracy. We also aimed to test the three leading hypotheses - the temporal fatigue, cognitive load and cognitive domain hypotheses of cognitive fatigue in MS. 50 consecutive MS patients attending the Neurology OPD in Madras Medical College, Chennai from May 2015 to February 2016 satisfying the 2010 revised McDonald criteria for MS with an equal number of matched controls were recruited. Modified versions (a shorter version, and longer and more demanding versions) of the Stroop test, symbol digit modalities test, and serial addition tests were used in addition to modified tests of P300 latency and amplitude each specifically tailored to reveal cognitive fatigue. Out of the seven measures of cognitive fatigue used, 46% (n=23) of MS patients had impairment in two or more of the scores compared to that of 8% (n=4) in the healthy control group. The Expanded disability status scale (EDSS) scores were significantly higher for MS patients with cognitive fatigue compared to those without. All the clinical and electrophysiological measures used in this study had a relatively high sensitivity and specificity. In addition, all the clinical measures correlated with the electrophysiological measures of cognitive fatigue in this study. Our data also supported all three hypotheses implying that cognitive fatigue in MS may be a multifaceted entity. Cognitive fatigue is widely prevalent in MS and can be detected with specific tools. The tools developed and described in this study may be used as an effective means of detecting

  20. Histone acetyltransferase (HAT) activity of p300 modulates human T lymphotropic virus type 1 p30II-mediated repression of LTR transcriptional activity

    International Nuclear Information System (INIS)

    Michael, Bindhu; Nair, Amrithraj M.; Datta, Antara; Hiraragi, Hajime; Ratner, Lee; Lairmore, Michael D.

    2006-01-01

    Human T-lymphotropic virus type-1 (HTLV-1) is a deltaretrovirus that causes adult T cell leukemia/lymphoma, and is implicated in a variety of lymphocyte-mediated inflammatory disorders. HTLV-1 provirus has regulatory and accessory genes in four pX open reading frames. HTLV-1 pX ORF-II encodes two proteins, p13 II and p30 II , which are incompletely defined in virus replication or pathogenesis. We have demonstrated that pX ORF-II mutations block virus replication in vivo and that ORF-II encoded p30 II , a nuclear-localizing protein that binds with CREB-binding protein (CBP)/p300, represses CREB and Tax responsive element (TRE)-mediated transcription. Herein, we have identified p30 II motifs important for p300 binding and in regulating TRE-mediated transcription in the absence and presence of HTLV-1 provirus. Within amino acids 100-179 of p30 II , a region important for repression of LTR-mediated transcription, we identified a single lysine residue at amino acid 106 (K3) that significantly modulates the ability of p30 II to repress TRE-mediated transcription. Exogenous p300, in a dose-responsive manner, reverses p30 II -dependent repression of TRE-mediated transcription, in the absence or presence of the provirus, In contrast to wild type p300, p300 HAT mutants (defective in histone acetyltransferase activity) only partially rescued p30 II -mediated LTR repression. Deacetylation by histone deacetylase-1 (HDAC-1) enhanced p30 II -mediated LTR repression, while inhibition of deacetylation by trichostatin A decreases p30 II -mediated LTR repression. Collectively, our data indicate that HTLV-1 p30 II modulates viral gene expression in a cooperative manner with p300-mediated acetylation

  1. Finite Amplitude Ocean Waves

    Indian Academy of Sciences (India)

    IAS Admin

    plitude waves and finite amplitude waves. This article provides a brief introduction to finite amplitude wave theories. Some of the general characteristics of waves as well as the importance of finite amplitude wave theories are touched upon. 2. Small Amplitude Waves. The topmost and the lowest levels of the waves are re-.

  2. Acetylation mediated by the p300/CBP-associated factor determines cellular energy metabolic pathways in cancer.

    Science.gov (United States)

    Rajendran, Ramkumar; Garva, Richa; Ashour, Hassan; Leung, Travis; Stratford, Ian; Krstic-Demonacos, Marija; Demonacos, Constantinos

    2013-06-01

    Normal cells produce energy either through OXPHOS in the presence of oxygen or glycolysis in its absence. Cancer cells produce energy preferably through glycolysis even in the presence of oxygen, thereby, acquiring survival and proliferative advantages. Oncogenes and tumour suppressors control these metabolic pathways by regulating the expression of their target genes involved in these processes. During hypoxia, HIF-1 favours high glycolytic flux by upregulating glycolytic enzymes. Conversely, p53 inhibits glycolysis and increases OXPHOS expression through TIGAR and SCO2 gene expression, respectively. We hypothesise that the p300/CBP-associated factor (PCAF) as a common co-factor shared between p53 and HIF-1 plays an important role in the regulation of energy production by modulating SCO2 and TIGAR gene expression mediated by these two transcription factors. The possible involvement of HIF-1 in the regulation of SCO2 and TIGAR gene expression was investigated in cells with different p53 status in normoxia- and hypoxia-mimicking conditions. Putative hypoxia response elements (HREs) were identified in the regulatory region of SCO2 and TIGAR gene promoters. Chromatin immunoprecipitation experiments suggested that HIF-1 was recruited to the putative HREs present in the SCO2 and TIGAR promoters in a cell type-dependent manner. Transcriptional assays endorsed the notion that PCAF may be involved in the determination of the SCO2 and TIGAR cellular levels, thereby, regulating cellular energy metabolism, a view supported by assays measuring lactic acid production and oxygen consumption in cells ectopically expressing PCAF. The present study identified HIF-1 as a potential regulator of SCO2 and TIGAR gene expression. Furthermore, evidence to suggest that PCAF is involved in the regulation of cellular energy production pathways in hypoxia-mimicking conditions is presented. This effect of PCAF is exerted by orchestrating differential recruitment of HIF-1α and p53 to the

  3. 3D structure prediction of histone acetyltransferase (HAC proteins of the p300/CBP family and their interactome in Arabidopsis thaliana

    Directory of Open Access Journals (Sweden)

    Amar Cemanovic

    2014-09-01

    Full Text Available Histone acetylation is an important posttranslational modification correlated with gene activation. In Arabidopsis thaliana the histone acetyltransferase (HAC proteins of the CBP family are homologous to animal p300/CREB (cAMP-responsive element-binding proteins, which are important histone acetyltransferases participating in many physiological processes, including proliferation, differentiation, and apoptosis. In this study the 3-D structure of all HAC protein subunits in Arabidopsis thaliana: HAC1, HAC2, HAC4, HAC5 and HAC12 is predicted by homology modeling and confirmed by Ramachandran plot analysis. The amino acid sequences HAC family members are highly similar to the sequences of the homologous human p300/CREB protein. Conservation of p300/CBP domains among the HAC proteins was examined further by sequence alignment and pattern search. The domains of p300/CBP required for the HAC function, such as PHD, TAZ and ZZ domains, are conserved in all HAC proteins. Interactome analysis revealed that HAC1, HAC5 and HAC12 proteins interact with S-adenosylmethionine-dependent methyltransferase domaincontaining protein that shows methyltransferase activity, suggesting an additional function of the HAC proteins. Additionally, HAC5 has a strong interaction value for the putative c-myb-like transcription factor MYB3R-4, which suggests that it also may have a function in regulation of DNA replication.

  4. P300 as a measure of processing capacity in auditory and visual domains in specific language impairment.

    Science.gov (United States)

    Evans, Julia L; Selinger, Craig; Pollak, Seth D

    2011-05-10

    This study examined the electrophysiological correlates of auditory and visual working memory in children with Specific Language Impairments (SLI). Children with SLI and age-matched controls (11;9-14;10) completed visual and auditory working memory tasks while event-related potentials (ERPs) were recorded. In the auditory condition, children with SLI performed similarly to controls when the memory load was kept low (1-back memory load). As expected, when demands for auditory working memory were higher, children with SLI showed decreases in accuracy and attenuated P3b responses. However, children with SLI also evinced difficulties in the visual working memory tasks. In both the low (1-back) and high (2-back) memory load conditions, P3b amplitude was significantly lower for the SLI as compared to CA groups. These data suggest a domain-general working memory deficit in SLI that is manifested across auditory and visual modalities. Copyright © 2010 Elsevier B.V. All rights reserved.

  5. HPSE enhancer RNA promotes cancer progression through driving chromatin looping and regulating hnRNPU/p300/EGR1/HPSE axis.

    Science.gov (United States)

    Jiao, Wanju; Chen, Yajun; Song, Huajie; Li, Dan; Mei, Hong; Yang, Feng; Fang, Erhu; Wang, Xiaojing; Huang, Kai; Zheng, Liduan; Tong, Qiangsong

    2018-03-07

    Recent studies reveal the emerging functions of enhancer RNAs (eRNAs) in gene expression. However, the roles of eRNAs in regulating the expression of heparanase (HPSE), an established endo-β-D-glucuronidase essential for cancer invasion and metastasis, still remain elusive. Herein, through comprehensive analysis of publically available FANTOM5 expression atlas and chromatin interaction dataset, we identified a super enhancer and its derived eRNA facilitating the HPSE expression (HPSE eRNA) in cancers. Gain-of-function and loss-of-function experiments indicated that HPSE eRNA facilitated the in vitro and in vivo tumorigenesis and aggressiveness of cancer cells. Mechanistically, as a p300-regulated nuclear noncoding RNA, HPSE eRNA bond to heterogeneous nuclear ribonucleoprotein U (hnRNPU) to facilitate its interaction with p300 and their enrichment on super enhancer, resulting in chromatin looping between super enhancer and HPSE promoter, p300-mediated transactivation of transcription factor early growth response 1 (EGR1), and subsequent elevation of HPSE expression. In addition, rescue studies in HPSE overexpressing or silencing cancer cells indicated that HPSE eRNA exerted oncogenic properties via driving HPSE expression. In clinical cancer tissues, HPSE eRNA was highly expressed and positively correlated with HPSE levels, and served as an independent prognostic factor for poor outcome of cancer patients. Therefore, these findings indicate that as a novel noncoding RNA, HPSE eRNA promotes cancer progression through driving chromatin looping and regulating hnRNPU/p300/EGR1/HPSE axis.

  6. Superiority of visual (verbal) vs. auditory test presentation modality in a P300-based CIT: The Complex Trial Protocol for concealed autobiographical memory detection.

    Science.gov (United States)

    Deng, Xiaohong; Rosenfeld, J Peter; Ward, Anne; Labkovsky, Elena

    2016-07-01

    This paper continues our efforts to determine which modality is best for presentation of stimuli in the P300-based concealed information test (CIT) called the Complex Trial Protocol (CTP). The first part of the CTP trial involves presentation of the key probe or irrelevant stimuli, and is followed by presentation of target (T) or non-target (NT). In Rosenfeld et al. (2015), probes and irrelevants regularly alternated modality over trials, but Ts and NTs were always visual. In the present study, (in both its experiments, EXP 1 and EXP 2), probes and irrelevants alternated modalities on successive trials, as before. In present EXP 1, Ts and NTs were always auditory, but in EXP 2, they were simultaneously auditory and visual. Probe P300 data were different in each study: In Rosenfeld et al. (2015) and EXP 2 here, the bootstrap-based detection rates based on probe-minus-irrelevant differences, significantly differed favoring visual probe and irrelevant presentation modality. In EXP 1 here, detection rates were the same for the two modalities. In Rosenfeld et al. (2015) there was no main effect of probe modality, visual vs. auditory on probe-minus-irrelevant P300 difference. There were such effects here in EXP 1 (pvisual modality. Probe P300 latencies were shorter for visual than for auditory stimuli in Rosenfeld et al. (2015), a trend specifically reversed in the present pair of studies. RT was faster for visual stimuli in the present studies. The T and NT modality appears to interact with probe/irrelevant modality, and the best protocol for detecting concealed information is with the 2015 study protocol or that of EXP 2, using visual stimulus presentation. Copyright © 2016 Elsevier B.V. All rights reserved.

  7. Diphoton generalized distribution amplitudes

    International Nuclear Information System (INIS)

    El Beiyad, M.; Pire, B.; Szymanowski, L.; Wallon, S.

    2008-01-01

    We calculate the leading order diphoton generalized distribution amplitudes by calculating the amplitude of the process γ*γ→γγ in the low energy and high photon virtuality region at the Born order and in the leading logarithmic approximation. As in the case of the anomalous photon structure functions, the γγ generalized distribution amplitudes exhibit a characteristic lnQ 2 behavior and obey inhomogeneous QCD evolution equations.

  8. On the use of LDA performance as a metric of feature extraction methods for a P300 BCI classification task

    International Nuclear Information System (INIS)

    Gareis, Iván; Atum, Yanina; Gentiletti, Gerardo; Acevedo, Rubén; Bañuelos, Verónica Medina; Rufiner, Leonardo

    2011-01-01

    Brain computer interfaces (BCIs) translate brain activity into computer commands. To enhance the performance of a BCI, it is necessary to improve the feature extraction techniques being applied to decode the users' intentions. Objective comparison methods are needed to analyze different feature extraction techniques. One possibility is to use the classifier performance as a comparative measure. In this work the effect of several variables that affect the behaviour of linear discriminant analysis (LDA) has been studied when used to distinguish between electroencephalographic signals with and without the presence of event related potentials (ERPs). The error rate (ER) and the area under the receiver operating characteristic curve (AUC) were used as performance estimators of LDA. The results show that the number of characteristics, the degree of balance of the training patterns set and the number of averaged trials affect the classifier's performance and therefore, must be considered in the design of the integrated system.

  9. Two Photon Distribution Amplitudes

    International Nuclear Information System (INIS)

    El Beiyad, M.; Pire, B.; Szymanowski, L.; Wallon, S.

    2008-01-01

    The factorization of the amplitude of the process γ*γ→γγ in the low energy and high photon virtuality region is demonstrated at the Born order and in the leading logarithmic approximation. The leading order two photon (generalized) distribution amplitudes exhibit a characteristic ln Q 2 behaviour and obey new inhomogeneous evolution equations

  10. Functional redundancy between the transcriptional activation domains of E2A is mediated by binding to the KIX domain of CBP/p300.

    Science.gov (United States)

    Denis, Christopher M; Langelaan, David N; Kirlin, Alyssa C; Chitayat, Seth; Munro, Kim; Spencer, Holly L; LeBrun, David P; Smith, Steven P

    2014-06-01

    The E-protein transcription factors play essential roles in lymphopoiesis, with E12 and E47 (hereafter called E2A) being particularly important in B cell specification and maturation. The E2A gene is also involved in a chromosomal translocation that results in the leukemogenic oncoprotein E2A-PBX1. The two activation domains of E2A, AD1 and AD2, display redundant, independent, and cooperative functions in a cell-dependent manner. AD1 of E2A functions by binding the transcriptional co-activator CBP/p300; this interaction is required in oncogenesis and occurs between the conserved ϕ-x-x-ϕ-ϕ motif in AD1 and the KIX domain of CBP/p300. However, co-activator recruitment by AD2 has not been characterized. Here, we demonstrate that the first of two conserved ϕ-x-x-ϕ-ϕ motifs within AD2 of E2A interacts at the same binding site on KIX as AD1. Mutagenesis uncovered a correspondence between the KIX-binding affinity of AD2 and transcriptional activation. Although AD2 is dispensable for oncogenesis, experimentally increasing the affinity of AD2 for KIX uncovered a latent potential to mediate immortalization of primary hematopoietic progenitors by E2A-PBX1. Our findings suggest that redundancy between the two E2A activation domains with respect to transcriptional activation and oncogenic function is mediated by binding to the same surface of the KIX domain of CBP/p300. © The Author(s) 2014. Published by Oxford University Press on behalf of Nucleic Acids Research.

  11. An Intelligent Man-Machine Interface-Multi-Robot Control Adapted for Task Engagement Based on Single-Trial Detectability of P300.

    Science.gov (United States)

    Kirchner, Elsa A; Kim, Su K; Tabie, Marc; Wöhrle, Hendrik; Maurus, Michael; Kirchner, Frank

    2016-01-01

    Advanced man-machine interfaces (MMIs) are being developed for teleoperating robots at remote and hardly accessible places. Such MMIs make use of a virtual environment and can therefore make the operator immerse him-/herself into the environment of the robot. In this paper, we present our developed MMI for multi-robot control. Our MMI can adapt to changes in task load and task engagement online. Applying our approach of embedded Brain Reading we improve user support and efficiency of interaction. The level of task engagement was inferred from the single-trial detectability of P300-related brain activity that was naturally evoked during interaction. With our approach no secondary task is needed to measure task load. It is based on research results on the single-stimulus paradigm, distribution of brain resources and its effect on the P300 event-related component. It further considers effects of the modulation caused by a delayed reaction time on the P300 component evoked by complex responses to task-relevant messages. We prove our concept using single-trial based machine learning analysis, analysis of averaged event-related potentials and behavioral analysis. As main results we show (1) a significant improvement of runtime needed to perform the interaction tasks compared to a setting in which all subjects could easily perform the tasks. We show that (2) the single-trial detectability of the event-related potential P300 can be used to measure the changes in task load and task engagement during complex interaction while also being sensitive to the level of experience of the operator and (3) can be used to adapt the MMI individually to the different needs of users without increasing total workload. Our online adaptation of the proposed MMI is based on a continuous supervision of the operator's cognitive resources by means of embedded Brain Reading. Operators with different qualifications or capabilities receive only as many tasks as they can perform to avoid mental

  12. An Intelligent Man-Machine Interface—Multi-Robot Control Adapted for Task Engagement Based on Single-Trial Detectability of P300

    Science.gov (United States)

    Kirchner, Elsa A.; Kim, Su K.; Tabie, Marc; Wöhrle, Hendrik; Maurus, Michael; Kirchner, Frank

    2016-01-01

    Advanced man-machine interfaces (MMIs) are being developed for teleoperating robots at remote and hardly accessible places. Such MMIs make use of a virtual environment and can therefore make the operator immerse him-/herself into the environment of the robot. In this paper, we present our developed MMI for multi-robot control. Our MMI can adapt to changes in task load and task engagement online. Applying our approach of embedded Brain Reading we improve user support and efficiency of interaction. The level of task engagement was inferred from the single-trial detectability of P300-related brain activity that was naturally evoked during interaction. With our approach no secondary task is needed to measure task load. It is based on research results on the single-stimulus paradigm, distribution of brain resources and its effect on the P300 event-related component. It further considers effects of the modulation caused by a delayed reaction time on the P300 component evoked by complex responses to task-relevant messages. We prove our concept using single-trial based machine learning analysis, analysis of averaged event-related potentials and behavioral analysis. As main results we show (1) a significant improvement of runtime needed to perform the interaction tasks compared to a setting in which all subjects could easily perform the tasks. We show that (2) the single-trial detectability of the event-related potential P300 can be used to measure the changes in task load and task engagement during complex interaction while also being sensitive to the level of experience of the operator and (3) can be used to adapt the MMI individually to the different needs of users without increasing total workload. Our online adaptation of the proposed MMI is based on a continuous supervision of the operator's cognitive resources by means of embedded Brain Reading. Operators with different qualifications or capabilities receive only as many tasks as they can perform to avoid mental

  13. Recruitment of CBP/p300, TATA-binding protein, and S8 to distinct regions at the N terminus of adenovirus E1A.

    Science.gov (United States)

    Rasti, Mozhgan; Grand, Roger J A; Mymryk, Joe S; Gallimore, Phillip H; Turnell, Andrew S

    2005-05-01

    The N-terminal region of the adenovirus (Ad) 12S E1A gene product targets several cellular proteins that are essential for the induction of S phase, cellular immortalization, cellular transformation, transcriptional repression, and transcriptional activation. The precise binding sites for these proteins, however, remain to be resolved. We therefore undertook an extensive site-directed mutagenesis approach to generate specific point mutants and to precisely map the binding sites for CBP, p300, TATA-binding protein (TBP), S4, S8, hGcn5, P/CAF, and Ran within the first 30 amino acids of the Ad5 12S E1A protein. We determined that although common residues within the N-terminal region can form partial binding sites for these proteins, point mutants were also generated that could discriminate between binding sites. These data indicate that AdE1A can target each of these proteins individually through distinct binding sites. It was evident, however, that the mutation of specific hydrophobic residues typically had the greatest effect upon AdE1A's ability to bind individual partners. Indeed, the mutation of L at positions 19 and 20 eliminated the ability of AdE1A to interact with any of the N-terminal binding proteins studied here. Interestingly, although TBP and S8 or CBP/p300 can exist as functional complexes, RNA interference revealed that the recruitment of either TBP, S8, or CBP/p300 to AdE1A was not dependent upon the expression of the other proteins. These data further indicate that AdE1A can target individual partner proteins in vivo and that it does not necessarily recruit these proteins indirectly as components of larger macromolecular complexes. Finally, we took advantage of the fine-mapping data to ascertain which proteins were targeted during the transformation process. Consistent with previous studies, CBP/p300 was found to be targeted by AdE1A during this process, although our data suggest that binding to other N-terminal proteins is also important for

  14. Preliminary investigation of plasma levels of sex hormones and human growth factor(s), and P300 latency as correlates to cognitive decline as a function of gender

    OpenAIRE

    Kerner Mallory M; Chen Amanda LC; Chen Thomas JH; Braverman Eric R; Tung Howard; Waite Roger L; Schoolfield John; Blum Kenneth

    2009-01-01

    Abstract Background Aging is marked by declines in levels of many sex hormones and growth factors, as well as in cognitive function. The P300 event-related potential has been established as a predictor of cognitive decline. We decided to determine if this measure, as well as 2 standard tests of memory and attention, may be correlated with serum levels of sex hormones and growth factors, and if there are any generalizations that could be made based on these parameters and the aging process. Fi...

  15. Avaliação dos potenciais evocados relacionados a eventos (ERP-P300) em pacientes com cirrose hepática sem encefalopatia

    OpenAIRE

    Teodoro,Vinicius; Bragagnolo Jr.,Maurício; Lucchesi,Lígia; Kondo,Mário; Tufik,Sérgio

    2008-01-01

    RACIONAL: Na cirrose hepática ocorrem alterações na estrutura do fígado, levando à perda das funções do órgão, com conseqüências neuropsiquiátricas, como disfunções cognitivas. Um dos meios mais efetivos para avaliar objetivamente as funções cognitivas é medir a atividade eletrofisiológica do sistema nervoso central através do potencial evocado relacionado a eventos (ERP-P300). OBJETIVO: Estudar a utilidade do potencial evocado relacionado a eventos (ERP), para avaliar distúrbios cognitivos e...

  16. Avaliação dos potenciais evocados relacionados a eventos (ERP-P300 em pacientes com cirrose hepática sem encefalopatia Evaluation of the event-related potential (ERP-P300 in patients with hepatic cirrhosis without encephalopathy

    Directory of Open Access Journals (Sweden)

    Vinicius Teodoro

    2008-03-01

    Full Text Available RACIONAL: Na cirrose hepática ocorrem alterações na estrutura do fígado, levando à perda das funções do órgão, com conseqüências neuropsiquiátricas, como disfunções cognitivas. Um dos meios mais efetivos para avaliar objetivamente as funções cognitivas é medir a atividade eletrofisiológica do sistema nervoso central através do potencial evocado relacionado a eventos (ERP-P300. OBJETIVO: Estudar a utilidade do potencial evocado relacionado a eventos (ERP, para avaliar distúrbios cognitivos em pacientes com cirrose hepática e como auxiliar no diagnóstico da encefalopatia hepática mínima. MÉTODO: Foram selecionados 50 pacientes, diagnosticados com cirrose hepática sem sinais clínicos de encefalopatia hepática e 35 voluntários saudáveis de idades e sexo semelhantes. Em todos os pacientes foram realizados exames clínico-neurológico e laboratoriais. Para identificação do prejuízo cognitivo foi utilizado o ERP-P300 e obtida a média da latência da onda P300. RESULTADOS: Houve diferença significativa entre as médias da latência do ERP-P300 do grupo cirrótico e controle. CONCLUSÃO: A realização do ERP-P300 é simples, depende de fatores controláveis de variação e tem fácil reprodutibilidade, podendo ser útil para o rastreio de distúrbios cognitivos em pacientes com cirrose e auxiliar no diagnóstico de encefalopatia hepática mínima.BACKGROUND: In hepatic cirrhosis structural liver alterations occur leading to the loss of the organ functions with neuro-psychiatric consequence, as cognitive dysfunctions. One of the most effective ways of objectively evaluating cognition is to measure electrophysiological activity in the central nervous system trough event-related potentials (ERP-P300. AIM: To assess the value of the event-related potential (ERP in order to determine cognitive disturbances in patients with liver cirrhosis and to assist in the diagnosis of minimal hepatic encephalopathy. METHODS: Fifty

  17. The effects of sweep numbers per average and protocol type on the accuracy of the p300-based concealed information test.

    Science.gov (United States)

    Dietrich, Ariana B; Hu, Xiaoqing; Rosenfeld, J Peter

    2014-03-01

    In the first of two experiments, we compared the accuracy of the P300 concealed information test protocol as a function of numbers of trials experienced by subjects and ERP averages analyzed by investigators. Contrary to Farwell et al. (Cogn Neurodyn 6(2):115-154, 2012), we found no evidence that 100 trial based averages are more accurate than 66 or 33 trial based averages (all numbers led to accuracies of 84-94 %). There was actually a trend favoring the lowest trial numbers. The second study compared numbers of irrelevant stimuli recalled and recognized in the 3-stimulus protocol versus the complex trial protocol (Rosenfeld in Memory detection: theory and application of the concealed information test, Cambridge University Press, New York, pp 63-89, 2011). Again, in contrast to expectations from Farwell et al. (Cogn Neurodyn 6(2):115-154, 2012), there were no differences between protocols, although there were more irrelevant stimuli recognized than recalled, and irrelevant 4-digit number group stimuli were neither recalled nor recognized as well as irrelevant city name stimuli. We therefore conclude that stimulus processing in the P300-based complex trial protocol-with no more than 33 sweep averages-is adequate to allow accurate detection of concealed information.

  18. E2A-PBX1 interacts directly with the KIX domain of CBP/p300 in the induction of proliferation in primary hematopoietic cells.

    Science.gov (United States)

    Bayly, Richard; Chuen, Luan; Currie, Richard A; Hyndman, Brandy D; Casselman, Richard; Blobel, Gerd A; LeBrun, David P

    2004-12-31

    The E2A gene encodes DNA-binding transcription factors, called E12 and E47, involved in cell specification and maturation. E2A is also involved in a chromosomal translocation that leads to the expression of an oncogenic transcription factor called E2A-PBX1 in cases of acute leukemia. In the work described here, we elucidate the interaction between E2A-PBX1 and transcriptional co-activators. We confirm that the E2A portion can interact with CBP and PCAF and map required elements on E2A and CBP. On CBP, the interaction involves the KIX domain, a well characterized domain that mediates interactions with several other oncogenic transcription factors. On E2A, the interaction with CBP requires conserved alpha-helical domains that reside within activation domains 1 and 2 (AD1 and AD2, respectively). Using purified, recombinant proteins, we show that the E2A-CBP interaction is direct. Notwithstanding the previously demonstrated ability of AD1 and AD2 to function independently, some of our findings suggest functional cooperativity between these two domains. Finally, we show that the CBP/p300-interactive helical domains of E2A are important in the induction of proliferation in cultured primary bone marrow cells retrovirally transduced with E2A-PBX1. Our findings suggest that some aspects of E2A-PBX1 oncogenesis involve a direct interaction with the KIX domain of CBP/p300.

  19. Reciprocal occupancy of BCL6 and STAT5 on Growth Hormone target genes: contrasting transcriptional outcomes and promoter-specific roles of p300 and HDAC3.

    Science.gov (United States)

    Lin, Grace; LaPensee, Christopher R; Qin, Zhaohui S; Schwartz, Jessica

    2014-09-01

    Expression of the Growth Hormone (GH)-stimulated gene Socs2 (Suppressor of Cytokine Signaling 2) is mediated by the transcription activator STAT5 (Signal Transducer and Activator of Transcription 5) and the transcription repressor BCL6 (B-Cell Lymphoma 6). ChIP-Sequencing identified Cish (Cytokine-Inducible SH2-containing protein) and Bcl6 as having similar patterns of reciprocal occupancy by BCL6 and STAT5 in response to GH, though GH stimulates Cish and inhibits Bcl6 expression. The co-activator p300 occupied Socs2, Cish and Bcl6 promoters, and enhanced STAT5-mediated activation of Socs2 and Cish. In contrast, on Bcl6, p300 functioned as a repressor and inhibited in conjunction with STAT5 or BCL6. The co-repressor HDAC3 (Histone deacetylase 3) inhibited the Socs2, Cish and Bcl6 promoters in the presence of STAT5. Thus transcriptional outcomes on GH-regulated genes occupied by BCL6 and STAT5 are determined in a promoter-specific fashion by co-regulatory proteins which mediate the distinction between activating and repressive transcription factors. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  20. Natural derivatives of curcumin attenuate the Wnt/β-catenin pathway through down-regulation of the transcriptional coactivator p300

    International Nuclear Information System (INIS)

    Ryu, Min-Jung; Cho, Munju; Song, Jie-Young; Yun, Yeon-Sook; Choi, Il-Whan; Kim, Dong-Eun; Park, Byeoung-Soo; Oh, Sangtaek

    2008-01-01

    Curcumin, a component of turmeric (Curcuma longa), has been reported to suppress β-catenin response transcription (CRT), which is aberrantly activated in colorectal cancer. However, the effects of its natural analogs (demethoxycurcumin [DMC] and bisdemethoxycurcumin [BDMC]) and metabolite (tetrahydrocurcumin [THC]) on the Wnt/β-catenin pathway have not been investigated. Here, we show that DMC and BDMC suppressed CRT that was activated by Wnt3a conditioned-medium (Wnt3a-CM) without altering the level of intracellular β-catenin, and inhibited the growth of various colon cancer cells, with comparable potency to curcumin. Additionally, DMC and BDMC down-regulated p300, which is a positive regulator of the Wnt/β-catenin pathway. Notably, THC also inhibited CRT and cell proliferation, but to a much lesser degree than curcumin, DMC, or BDMC, indicating that the conjugated bonds in the central seven-carbon chain of curcuminoids are essential for the inhibition of Wnt/β-catenin pathway and the anti-proliferative activity of curcuminoids. Thus, our findings suggest that curcumin derivatives inhibit the Wnt/β-catenin pathway by decreasing the amount of the transcriptional coactivator p300.

  1. Adapted wavelet transform improves time-frequency representations: a study of auditory elicited P300-like event-related potentials in rats

    Science.gov (United States)

    Richard, Nelly; Laursen, Bettina; Grupe, Morten; Drewes, Asbjørn M.; Graversen, Carina; Sørensen, Helge B. D.; Bastlund, Jesper F.

    2017-04-01

    Objective. Active auditory oddball paradigms are simple tone discrimination tasks used to study the P300 deflection of event-related potentials (ERPs). These ERPs may be quantified by time-frequency analysis. As auditory stimuli cause early high frequency and late low frequency ERP oscillations, the continuous wavelet transform (CWT) is often chosen for decomposition due to its multi-resolution properties. However, as the conventional CWT traditionally applies only one mother wavelet to represent the entire spectrum, the time-frequency resolution is not optimal across all scales. To account for this, we developed and validated a novel method specifically refined to analyse P300-like ERPs in rats. Approach. An adapted CWT (aCWT) was implemented to preserve high time-frequency resolution across all scales by commissioning of multiple wavelets operating at different scales. First, decomposition of simulated ERPs was illustrated using the classical CWT and the aCWT. Next, the two methods were applied to EEG recordings obtained from prefrontal cortex in rats performing a two-tone auditory discrimination task. Main results. While only early ERP frequency changes between responses to target and non-target tones were detected by the CWT, both early and late changes were successfully described with strong accuracy by the aCWT in rat ERPs. Increased frontal gamma power and phase synchrony was observed particularly within theta and gamma frequency bands during deviant tones. Significance. The study suggests superior performance of the aCWT over the CWT in terms of detailed quantification of time-frequency properties of ERPs. Our methodological investigation indicates that accurate and complete assessment of time-frequency components of short-time neural signals is feasible with the novel analysis approach which may be advantageous for characterisation of several types of evoked potentials in particularly rodents.

  2. Reinforcing Saccadic Amplitude Variability

    Science.gov (United States)

    Paeye, Celine; Madelain, Laurent

    2011-01-01

    Saccadic endpoint variability is often viewed as the outcome of neural noise occurring during sensorimotor processing. However, part of this variability might result from operant learning. We tested this hypothesis by reinforcing dispersions of saccadic amplitude distributions, while maintaining constant their medians. In a first experiment we…

  3. Light Meson Distribution Amplitudes

    CERN Document Server

    Arthur, R.; Brommel, D.; Donnellan, M.A.; Flynn, J.M.; Juttner, A.; de Lima, H.Pedroso; Rae, T.D.; Sachrajda, C.T.; Samways, B.

    2010-01-01

    We calculated the first two moments of the light-cone distribution amplitudes for the pseudoscalar mesons ($\\pi$ and $K$) and the longitudinally polarised vector mesons ($\\rho$, $K^*$ and $\\phi$) as part of the UKQCD and RBC collaborations' $N_f=2+1$ domain-wall fermion phenomenology programme. These quantities were obtained with a good precision and, in particular, the expected effects of $SU(3)$-flavour symmetry breaking were observed. Operators were renormalised non-perturbatively and extrapolations to the physical point were made, guided by leading order chiral perturbation theory. The main results presented are for two volumes, $16^3\\times 32$ and $24^3\\times 64$, with a common lattice spacing. Preliminary results for a lattice with a finer lattice spacing, $32^3\\times64$, are discussed and a first look is taken at the use of twisted boundary conditions to extract distribution amplitudes.

  4. Classification of EEG-P300 Signals Extracted from Brain Activities in BCI Systems Using ν-SVM and BLDA Algorithms

    Directory of Open Access Journals (Sweden)

    Ali MOMENNEZHAD

    2014-06-01

    Full Text Available In this paper, a linear predictive coding (LPC model is used to improve classification accuracy, convergent speed to maximum accuracy, and maximum bitrates in brain computer interface (BCI system based on extracting EEG-P300 signals. First, EEG signal is filtered in order to eliminate high frequency noise. Then, the parameters of filtered EEG signal are extracted using LPC model. Finally, the samples are reconstructed by LPC coefficients and two classifiers, a Bayesian Linear discriminant analysis (BLDA, and b the υ-support vector machine (υ-SVM are applied in order to classify. The proposed algorithm performance is compared with fisher linear discriminant analysis (FLDA. Results show that the efficiency of our algorithm in improving classification accuracy and convergent speed to maximum accuracy are much better. As example at the proposed algorithms, respectively BLDA with LPC model and υ-SVM with LPC model with8 electrode configuration for subject S1 the total classification accuracy is improved as 9.4% and 1.7%. And also, subject 7 at BLDA and υ-SVM with LPC model algorithms (LPC+BLDA and LPC+ υ-SVM after block 11th converged to maximum accuracy but Fisher Linear Discriminant Analysis (FLDA algorithm did not converge to maximum accuracy (with the same configuration. So, it can be used as a promising tool in designing BCI systems.

  5. Light on! Real world evaluation of a P300-based brain-computer interface (BCI) for environment control in a smart home.

    Science.gov (United States)

    Carabalona, Roberta; Grossi, Ferdinando; Tessadri, Adam; Castiglioni, Paolo; Caracciolo, Antonio; de Munari, Ilaria

    2012-01-01

    Brain-computer interface (BCI) systems aim to enable interaction with other people and the environment without muscular activation by the exploitation of changes in brain signals due to the execution of cognitive tasks. In this context, the visual P300 potential appears suited to control smart homes through BCI spellers. The aim of this work is to evaluate whether the widely used character-speller is more sustainable than an icon-based one, designed to operate smart home environment or to communicate moods and needs. Nine subjects with neurodegenerative diseases and no BCI experience used both speller types in a real smart home environment. User experience during BCI tasks was evaluated recording concurrent physiological signals. Usability was assessed for each speller type immediately after use. Classification accuracy was lower for the icon-speller, which was also more attention demanding. However, in subjective evaluations, the effect of a real feedback partially counterbalanced the difficulty in BCI use. Since inclusive BCIs require to consider interface sustainability, we evaluated different ergonomic aspects of the interaction of disabled users with a character-speller (goal: word spelling) and an icon-speller (goal: operating a real smart home). We found the first one as more sustainable in terms of accuracy and cognitive effort.

  6. Fully automated high-throughput chromatin immunoprecipitation for ChIP-seq: identifying ChIP-quality p300 monoclonal antibodies.

    Science.gov (United States)

    Gasper, William C; Marinov, Georgi K; Pauli-Behn, Florencia; Scott, Max T; Newberry, Kimberly; DeSalvo, Gilberto; Ou, Susan; Myers, Richard M; Vielmetter, Jost; Wold, Barbara J

    2014-06-12

    Chromatin immunoprecipitation coupled with DNA sequencing (ChIP-seq) is the major contemporary method for mapping in vivo protein-DNA interactions in the genome. It identifies sites of transcription factor, cofactor and RNA polymerase occupancy, as well as the distribution of histone marks. Consortia such as the ENCyclopedia Of DNA Elements (ENCODE) have produced large datasets using manual protocols. However, future measurements of hundreds of additional factors in many cell types and physiological states call for higher throughput and consistency afforded by automation. Such automation advances, when provided by multiuser facilities, could also improve the quality and efficiency of individual small-scale projects. The immunoprecipitation process has become rate-limiting, and is a source of substantial variability when performed manually. Here we report a fully automated robotic ChIP (R-ChIP) pipeline that allows up to 96 reactions. A second bottleneck is the dearth of renewable ChIP-validated immune reagents, which do not yet exist for most mammalian transcription factors. We used R-ChIP to screen new mouse monoclonal antibodies raised against p300, a histone acetylase, well-known as a marker of active enhancers, for which ChIP-competent monoclonal reagents have been lacking. We identified, validated for ChIP-seq, and made publicly available a monoclonal reagent called ENCITp300-1.

  7. Toward a P300 based Brain-Computer Interface for aphasia rehabilitation after stroke: Presentation of theoretical considerations and a pilot feasibility study

    Directory of Open Access Journals (Sweden)

    Sonja C Kleih

    2016-11-01

    Full Text Available People with post-stroke motor aphasia know what they would like to say but cannot express it through motor pathways due to disruption of cortical circuits. We present a theoretical background for our hypothesized connection between attention and aphasia rehabilitation and suggest why in this context, Brain-Computer Interfaces (BCI use might be beneficial for patients diagnosed with aphasia. Not only could BCI technology provide a communication tool, it might support neuronal plasticity by activating language circuits and thereby boost aphasia recovery. However, stroke may lead to heterogeneous symptoms that might hinder BCI use which is why the feasibility of this approach needed to be investigated first. In this pilot study, we included five participants diagnosed with post-stroke aphasia. Four participants were initially unable to use the visual P300 speller paradigm. By adjusting the paradigm to their needs, all participants could successfully learn to use the speller for communication with accuracies up to 100%. We describe necessary adjustments to the paradigm and present future steps to further investigate the here presented approach.

  8. miR-17-5p targets the p300/CBP-associated factor and modulates androgen receptor transcriptional activity in cultured prostate cancer cells

    International Nuclear Information System (INIS)

    Gong, Ai-Yu; Eischeid, Alex N; Xiao, Jing; Zhao, Jian; Chen, Dongqing; Wang, Zhao-Yi; Young, Charles YF; Chen, Xian-Ming

    2012-01-01

    Androgen receptor (AR) signalling is critical to the initiation and progression of prostate cancer (PCa). Transcriptional activity of AR involves chromatin recruitment of co-activators, including the p300/CBP-associated factor (PCAF). Distinct miRNA expression profiles have been identified in PCa cells during the development and progression of the disease. Whether miRNAs regulate PCAF expression in PCa cells to regulate AR transcriptional activity is still unclear. Expression of PCAF was investigated in several PCa cell lines by qRT-PCR, Western blot, and immunocytochemistry. The effects of PCAF expression on AR-regulated transcriptional activity and cell growth in PCa cells were determined by chromatin immunoprecipitation, reporter gene construct analysis, and MTS assay. Targeting of PCAF by miR-17-5p was evaluated using the luciferase reporter assay. PCAF was upregulated in several PCa cell lines. Upregulation of PCAF promoted AR transcriptional activation and cell growth in cultured PCa cells. Expression of PCAF in PCa cells was associated with the downregulation of miR-17-5p. Targeting of the 3’-untranslated region of PCAF mRNA by miR-17-5p caused translational suppression and RNA degradation, and, consequently, modulation of AR transcriptional activity in PCa cells. PCAF is upregulated in cultured PCa cells, and upregulation of PCAF is associated with the downregulation of miR-17-5p. Targeting of PCAF by miR-17-5p modulates AR transcriptional activity and cell growth in cultured PCa cells

  9. miR-17-5p targets the p300/CBP-associated factor and modulates androgen receptor transcriptional activity in cultured prostate cancer cells

    Directory of Open Access Journals (Sweden)

    Gong Ai-Yu

    2012-10-01

    Full Text Available Abstract Background Androgen receptor (AR signalling is critical to the initiation and progression of prostate cancer (PCa. Transcriptional activity of AR involves chromatin recruitment of co-activators, including the p300/CBP-associated factor (PCAF. Distinct miRNA expression profiles have been identified in PCa cells during the development and progression of the disease. Whether miRNAs regulate PCAF expression in PCa cells to regulate AR transcriptional activity is still unclear. Methods Expression of PCAF was investigated in several PCa cell lines by qRT-PCR, Western blot, and immunocytochemistry. The effects of PCAF expression on AR-regulated transcriptional activity and cell growth in PCa cells were determined by chromatin immunoprecipitation, reporter gene construct analysis, and MTS assay. Targeting of PCAF by miR-17-5p was evaluated using the luciferase reporter assay. Results PCAF was upregulated in several PCa cell lines. Upregulation of PCAF promoted AR transcriptional activation and cell growth in cultured PCa cells. Expression of PCAF in PCa cells was associated with the downregulation of miR-17-5p. Targeting of the 3’-untranslated region of PCAF mRNA by miR-17-5p caused translational suppression and RNA degradation, and, consequently, modulation of AR transcriptional activity in PCa cells. Conclusions PCAF is upregulated in cultured PCa cells, and upregulation of PCAF is associated with the downregulation of miR-17-5p. Targeting of PCAF by miR-17-5p modulates AR transcriptional activity and cell growth in cultured PCa cells.

  10. Quantitative Analysis of GPR Signals: Transmitted Wavelet, Amplitude Decay, and Sampling-Related Amplitude Distortions

    Science.gov (United States)

    Dossi, M.; Forte, Emanuele; Pipan, M.

    2017-12-01

    We study the importance of accurately recording signal amplitudes for the quantitative analysis of GPR data sets. Specifically, we measure the peak amplitudes of signals emitted by GPR antennas with different central frequencies and study their amplitude decay with distance, in order to extrapolate the peak amplitude of the wavelet initially transmitted by each antenna. The purpose is to compare the reference and reflected amplitudes in order to accurately estimate the subsurface EM impedance contrasts. Moreover, we study how sampling-related amplitude distortions can affect the quantitative analysis, and subsequently the resulting subsurface models, even in the absence of aliasing effects. The well-known Nyquist-Shannon theorem gives practical lower limits for the sampling rate in order to preserve the spectral content of a digitized signal; however, we show that it does not prevent possible amplitude distortions. In particular, we demonstrate that significant and unrecoverable loss of amplitude information occurs even at sampling rates well above the Nyquist-Shannon threshold. Interpolation may theoretically reduce such amplitude distortions; however, its accuracy would depend on the implemented algorithm and it is not verifiable in real data sets, since the actual amplitude information is limited to the sampled values. Moreover, re-sampling the interpolated signal simply reintroduces the initial problem, when a new sampling rate is selected. Our analysis suggests that, in order to limit the maximum peak amplitude error within 5%, the sampling rate selected during data acquisition must be at least 12 times the signal central frequency, which is higher than the commonly adopted standards.

  11. Quantitative Analysis of GPR Signals: Transmitted Wavelet, Amplitude Decay, and Sampling-Related Amplitude Distortions

    Science.gov (United States)

    Dossi, M.; Forte, Emanuele; Pipan, M.

    2018-03-01

    We study the importance of accurately recording signal amplitudes for the quantitative analysis of GPR data sets. Specifically, we measure the peak amplitudes of signals emitted by GPR antennas with different central frequencies and study their amplitude decay with distance, in order to extrapolate the peak amplitude of the wavelet initially transmitted by each antenna. The purpose is to compare the reference and reflected amplitudes in order to accurately estimate the subsurface EM impedance contrasts. Moreover, we study how sampling-related amplitude distortions can affect the quantitative analysis, and subsequently the resulting subsurface models, even in the absence of aliasing effects. The well-known Nyquist-Shannon theorem gives practical lower limits for the sampling rate in order to preserve the spectral content of a digitized signal; however, we show that it does not prevent possible amplitude distortions. In particular, we demonstrate that significant and unrecoverable loss of amplitude information occurs even at sampling rates well above the Nyquist-Shannon threshold. Interpolation may theoretically reduce such amplitude distortions; however, its accuracy would depend on the implemented algorithm and it is not verifiable in real data sets, since the actual amplitude information is limited to the sampled values. Moreover, re-sampling the interpolated signal simply reintroduces the initial problem, when a new sampling rate is selected. Our analysis suggests that, in order to limit the maximum peak amplitude error within 5%, the sampling rate selected during data acquisition must be at least 12 times the signal central frequency, which is higher than the commonly adopted standards.

  12. Microwave Imaging using Amplitude-only Data

    DEFF Research Database (Denmark)

    Rubæk, Tonny; Zhurbenko, Vitaliy

    2010-01-01

    This paper discuss how the performance of an imaging system is affected when the phase information of the measurements are removed from the data, leaving only amplitude information as input for the imaging algorithm. Simulated data are used for this purpose, and the images resulting from using...... amplitude-only data are compared with images obtained using the same data sets in which the phase information has been retained. In addition to this, some modifications for the imaging algorithm is presented which to some extent counters the effects of excluding the phase information in the reconstruction....

  13. Unifying relations for scattering amplitudes

    Science.gov (United States)

    Cheung, Clifford; Shen, Chia-Hsien; Wen, Congkao

    2018-02-01

    We derive new amplitudes relations revealing a hidden unity among a wideranging variety of theories in arbitrary spacetime dimensions. Our results rely on a set of Lorentz invariant differential operators which transmute physical tree-level scattering amplitudes into new ones. By transmuting the amplitudes of gravity coupled to a dilaton and two-form, we generate all the amplitudes of Einstein-Yang-Mills theory, Dirac-Born-Infield theory, special Galileon, nonlinear sigma model, and biadjoint scalar theory. Transmutation also relates amplitudes in string theory and its variants. As a corollary, celebrated aspects of gluon and graviton scattering like color-kinematics duality, the KLT relations, and the CHY construction are inherited traits of the transmuted amplitudes. Transmutation recasts the Adler zero as a trivial consequence of the Weinberg soft theorem and implies new subleading soft theorems for certain scalar theories.

  14. Evidencias de compromiso cerebral en el estadio crónico de la enfermedad de Chagas obtenidas por medio del potencial P300 y de electroencefalografía cuantificada P300 event related potentials and qEEG evidenced a cerebral dysfunction in human chronic Chagas disease

    Directory of Open Access Journals (Sweden)

    JULIO OSCAR PROST

    2000-06-01

    Full Text Available Es reconocido el compromiso del sistema nervioso periférico en la etapa crónica de la enfermedad de Chagas, incorporándose últimamente evidencias tomográficas y neuropsicológicas de compromiso cerebral. Con el objetivo de evaluar dicho compromiso por medio del potencial P 300 y la electroencefalografía cuantificada (EEGc se estudiaron 35 pacientes (26 a 55 años, comparados con un grupo control de similar número y edad (29 a 55 años. Se observó: latencia de la onda P 3 mayor en el grupo en estudio (331,24 ± 24,02 contra 318,86 ± 23,18 (p=0,01716. El EEGc mostró diferencias en la potencia relativa de la banda Beta 1, menor en los pacientes (p=1,62834E5 y en la frecuencia dominante, 1 Hz menor en los chagasicos (p=0,01077. El análisis multivariado discrimina tres subpoblaciones: una normal, una de enfermos con incremento alfa y otra de enfermos con decremento alfa e incremento delta y theta (p=0,00004. La proporción de resultados patológicos fue del 20 % en los EEGc y el 11,43 % en los potenciales cognitivos. No se correlacionó el compromiso neurológico y el cardíaco. Se concluye que existen francos indicadores electrofisiológicos de compromiso cerebral en el estadio crónico de la enfermedad de Chagas, hallazgo que refuerza a los obtenidos por otros métodos.It is already known the involvement of the peripheral nervous system in chronical stages of Chagas disease. Tomographic and neuropsychological evidence of brain compromise has been included recently. In order to evaluate the neurophysiological counterpart of cerebral involvement, we studied P300 evoked potential and quantified EEG (qEEG of 35 patients (2655 years, and compared to an equal number of control subjects (2955 years. We have found increased P300 latency compared to the control group (331.24 ± 24.02 vs 318.86 ± 23.18 (p=0.01716. qEEG showed lower relative Beta 1 power in the patients group (p=1.6E5, and the principal frequency 1 Hz slower in the same group (p=0

  15. Scattering amplitudes in gauge theories

    CERN Document Server

    Henn, Johannes M

    2014-01-01

    At the fundamental level, the interactions of elementary particles are described by quantum gauge field theory. The quantitative implications of these interactions are captured by scattering amplitudes, traditionally computed using Feynman diagrams. In the past decade tremendous progress has been made in our understanding of and computational abilities with regard to scattering amplitudes in gauge theories, going beyond the traditional textbook approach. These advances build upon on-shell methods that focus on the analytic structure of the amplitudes, as well as on their recently discovered hidden symmetries. In fact, when expressed in suitable variables the amplitudes are much simpler than anticipated and hidden patterns emerge.   These modern methods are of increasing importance in phenomenological applications arising from the need for high-precision predictions for the experiments carried out at the Large Hadron Collider, as well as in foundational mathematical physics studies on the S-matrix in quantum ...

  16. Motivic amplitudes and cluster coordinates

    International Nuclear Information System (INIS)

    Golden, J.K.; Goncharov, A.B.; Spradlin, M.; Vergu, C.; Volovich, A.

    2014-01-01

    In this paper we study motivic amplitudes — objects which contain all of the essential mathematical content of scattering amplitudes in planar SYM theory in a completely canonical way, free from the ambiguities inherent in any attempt to choose particular functional representatives. We find that the cluster structure on the kinematic configuration space Conf n (ℙ 3 ) underlies the structure of motivic amplitudes. Specifically, we compute explicitly the coproduct of the two-loop seven-particle MHV motivic amplitude A 7,2 M and find that like the previously known six-particle amplitude, it depends only on certain preferred coordinates known in the mathematics literature as cluster X-coordinates on Conf n (ℙ 3 ). We also find intriguing relations between motivic amplitudes and the geometry of generalized associahedrons, to which cluster coordinates have a natural combinatoric connection. For example, the obstruction to A 7,2 M being expressible in terms of classical polylogarithms is most naturally represented by certain quadrilateral faces of the appropriate associahedron. We also find and prove the first known functional equation for the trilogarithm in which all 40 arguments are cluster X-coordinates of a single algebra. In this respect it is similar to Abel’s 5-term dilogarithm identity

  17. Accommodative Amplitude in School-Age Children

    Directory of Open Access Journals (Sweden)

    Ikaunieks Gatis

    2017-10-01

    Full Text Available In children, intensive near-work affects the accommodation system of the eye. Younger children, due to anatomical parameters, read at smaller distance than older children and we can expect that the accommodation system of younger can be affected more than that of older children. We wanted to test this hypothesis. Some authors showed that the norms of amplitude of accommodation (AA developed by Hofstetter (1950 not always could be applied for children. We also wanted to verify these results. A total of 106 (age 7-15 children participated in the study. Distance visual acuity was measured for all children and only data of children with good visual acuity 1.0 or more (dec. units were analysed (73 children. Accommodative amplitude was measured before and after lessons using subjective push-up technique (with RAF Near Point Ruler. The results showed that the amplitude of accommodation reduced significantly (p < 0.05 during the day and decrease of AA was similar in different age groups (about ~0.70 D. Additional measurements are needed to verify that the observed changes in AA were associated with fatigue effect. The results showed lower accommodation values compared to average values calculated according to the Hofstetter equation (p < 0.05.

  18. Nonsinglet pentagons and NMHV amplitudes

    Directory of Open Access Journals (Sweden)

    A.V. Belitsky

    2015-07-01

    Full Text Available Scattering amplitudes in maximally supersymmetric gauge theory receive a dual description in terms of the expectation value of the super Wilson loop stretched on a null polygonal contour. This makes the analysis amenable to nonperturbative techniques. Presently, we elaborate on a refined form of the operator product expansion in terms of pentagon transitions to compute twist-two contributions to NMHV amplitudes. To start with, we provide a novel derivation of scattering matrices starting from Baxter equations for flux-tube excitations propagating on magnon background. We propose bootstrap equations obeyed by pentagon form factors with nonsinglet quantum numbers with respect to the R-symmetry group and provide solutions to them to all orders in 't Hooft coupling. These are then successfully confronted against available perturbative calculations for NMHV amplitudes to four-loop order.

  19. Shape of Pion Distribution Amplitude

    Energy Technology Data Exchange (ETDEWEB)

    Radyushkin, Anatoly

    2009-11-01

    A scenario is investigated in which the leading-twist pion distribution amplitude $\\varphi_\\pi (x)$ is approximated by the pion decay constant $f_\\pi$ for all essential values of the light-cone fraction $x$. A model for the light-front wave function $\\Psi (x, k_\\perp)$ is proposed that produces such a distribution amplitude and has a rapidly decreasing (exponential for definiteness) dependence on the light-front energy combination $ k_\\perp^2/x(1-x)$. It is shown that this model easily reproduces the fit of recent large-$Q^2$ BaBar data on the photon-pion transition form factor. Some aspects of scenario with flat pion distribution amplitude are discussed.

  20. Large amplitude oscillatory elongation flow

    DEFF Research Database (Denmark)

    Rasmussen, Henrik K.; Laillé, Philippe; Yu, Kaijia

    2008-01-01

    A filament stretching rheometer (FSR) was used for measuring the elongation flow with a large amplitude oscillative elongation imposed upon the flow. The large amplitude oscillation imposed upon the elongational flow as a function of the time t was defined as epsilon(t) =(epsilon) over dot(0)t...... with a molecular weight of 145 kg/ mol was subjected to the oscillative flow. The onset of the steady periodic regime is reached at the same Hencky strain as the onset of the steady elongational viscosity ( Lambda = 0). The integral molecular stress function formulation within the 'interchain pressure' concept...

  1. The activation of p38 MAPK primarily contributes to UV-induced RhoB expression by recruiting the c-Jun and p300 to the distal CCAAT box of the RhoB promoter

    Energy Technology Data Exchange (ETDEWEB)

    Ahn, Jiwon [Genome Research Center, KRIBB, Daejeon 305-806 (Korea, Republic of); Department of Microbiology, Chungnam National University, Daejeon 305-764 (Korea, Republic of); Choi, Jeong-Hae; Won, Misun [Genome Research Center, KRIBB, Daejeon 305-806 (Korea, Republic of); Kang, Chang-Mo [Laboratory of Cytogenetics and Tissue Regeneration, KIRAMS, Seoul 139-706 (Korea, Republic of); Gyun, Mi-Rang [Genome Research Center, KRIBB, Daejeon 305-806 (Korea, Republic of); Functional Genomics, Korea University of Science and Technology, Daejeon 305-350 (Korea, Republic of); Park, Hee-Moon [Department of Microbiology, Chungnam National University, Daejeon 305-764 (Korea, Republic of); Kim, Chun-Ho, E-mail: chkim@kirams.re.kr [Laboratory of Cytogenetics and Tissue Regeneration, KIRAMS, Seoul 139-706 (Korea, Republic of); Chung, Kyung-Sook, E-mail: kschung@kribb.re.kr [Genome Research Center, KRIBB, Daejeon 305-806 (Korea, Republic of)

    2011-06-03

    Highlights: {yields} Regulation of transcriptional activation of RhoB is still unclear. {yields} We examine the effect of p38 MAPK inhibition, and c-Jun and RhoB depletion on UV-induced RhoB expression and apoptosis. {yields} We identify the regions of RhoB promoter necessary to confer UV responsiveness using pRhoB-luciferase reporter assays. {yields} c-Jun, ATF2 and p300 are dominantly associated with NF-Y on the distal CCAAT box. {yields} The activation of p38 MAPK primarily contribute to UV-induced RhoB expression by recruiting the c-Jun and p300 proteins on distal CCAAT box of RhoB promoter. -- Abstract: The Ras-related small GTP-binding protein RhoB is rapidly induced in response to genotoxic stresses caused by ionizing radiation. It is known that UV-induced RhoB expression results from the binding of activating transcription factor 2 (ATF2) via NF-Y to the inverted CCAAT box (-23) of the RhoB promoter. Here, we show that the association of c-Jun with the distal CCAAT box (-72) is primarily involved in UV-induced RhoB expression and p38 MAPK regulated RhoB induction through the distal CCAAT box. UV-induced RhoB expression and apoptosis were markedly attenuated by pretreatment with the p38 MAPK inhibitor. siRNA knockdown of RhoB, ATF2 and c-Jun resulted in decreased RhoB expression and eventually restored the growth of UV-irradiated Jurkat cells. In the reporter assay using luciferase under the RhoB promoter, inhibition of RhoB promoter activity by the p38 inhibitor and knockdown of c-Jun using siRNA occurred through the distal CCAAT box. Immunoprecipitation and DNA affinity protein binding assays revealed the association of c-Jun and p300 via NF-YA and the dissociation of histone deacetylase 1 (HDAC1) via c-Jun recruitment to the CCAAT boxes of the RhoB promoter. These results suggest that the activation of p38 MAPK primarily contributes to UV-induced RhoB expression by recruiting the c-Jun and p300 proteins to the distal CCAAT box of the RhoB promoter in

  2. Scattering Amplitudes from Intersection Theory.

    Science.gov (United States)

    Mizera, Sebastian

    2018-04-06

    We use Picard-Lefschetz theory to prove a new formula for intersection numbers of twisted cocycles associated with a given arrangement of hyperplanes. In a special case when this arrangement produces the moduli space of punctured Riemann spheres, intersection numbers become tree-level scattering amplitudes of quantum field theories in the Cachazo-He-Yuan formulation.

  3. Employing Helicity Amplitudes for Resummation

    NARCIS (Netherlands)

    Moult, I.; Stewart, I.W.; Tackmann, F.J.; Waalewijn, W.J.

    2015-01-01

    Many state-of-the-art QCD calculations for multileg processes use helicity amplitudes as their fundamental ingredients. We construct a simple and easy-to-use helicity operator basis in soft-collinear effective theory (SCET), for which the hard Wilson coefficients from matching QCD onto SCET are

  4. Employing helicity amplitudes for resummation

    International Nuclear Information System (INIS)

    Moult, Ian; Stewart, Iain W.; Tackmann, Frank J.; Waalewijn, Wouter J.; Amsterdam Univ.

    2015-08-01

    Many state-of-the-art QCD calculations for multileg processes use helicity amplitudes as their fundamental ingredients. We construct a simple and easy-to-use helicity operator basis in soft-collinear effective theory (SCET), for which the hard Wilson coefficients from matching QCD onto SCET are directly given in terms of color-ordered helicity amplitudes. Using this basis allows one to seamlessly combine fixed-order helicity amplitudes at any order they are known with a resummation of higher-order logarithmic corrections. In particular, the virtual loop amplitudes can be employed in factorization theorems to make predictions for exclusive jet cross sections without the use of numerical subtraction schemes to handle real-virtual infrared cancellations. We also discuss matching onto SCET in renormalization schemes with helicities in 4- and d-dimensions. To demonstrate that our helicity operator basis is easy to use, we provide an explicit construction of the operator basis, as well as results for the hard matching coefficients, for pp → H+0,1,2 jets, pp → W/Z/γ+0,1,2 jets, and pp → 2,3 jets. These operator bases are completely crossing symmetric, so the results can easily be applied to processes with e + e - and e - p collisions.

  5. Scattering amplitudes in gauge theories

    International Nuclear Information System (INIS)

    Henn, Johannes M.; Plefka, Jan C.

    2014-01-01

    First monographical text on this fundamental topic. Course-tested, pedagogical and self-contained exposition. Includes exercises and solutions. At the fundamental level, the interactions of elementary particles are described by quantum gauge field theory. The quantitative implications of these interactions are captured by scattering amplitudes, traditionally computed using Feynman diagrams. In the past decade tremendous progress has been made in our understanding of and computational abilities with regard to scattering amplitudes in gauge theories, going beyond the traditional textbook approach. These advances build upon on-shell methods that focus on the analytic structure of the amplitudes, as well as on their recently discovered hidden symmetries. In fact, when expressed in suitable variables the amplitudes are much simpler than anticipated and hidden patterns emerge. These modern methods are of increasing importance in phenomenological applications arising from the need for high-precision predictions for the experiments carried out at the Large Hadron Collider, as well as in foundational mathematical physics studies on the S-matrix in quantum field theory. Bridging the gap between introductory courses on quantum field theory and state-of-the-art research, these concise yet self-contained and course-tested lecture notes are well-suited for a one-semester graduate level course or as a self-study guide for anyone interested in fundamental aspects of quantum field theory and its applications. The numerous exercises and solutions included will help readers to embrace and apply the material presented in the main text.

  6. Positivity of spin foam amplitudes

    International Nuclear Information System (INIS)

    Baez, John C; Christensen, J Daniel

    2002-01-01

    The amplitude for a spin foam in the Barrett-Crane model of Riemannian quantum gravity is given as a product over its vertices, edges and faces, with one factor of the Riemannian 10j symbols appearing for each vertex, and simpler factors for the edges and faces. We prove that these amplitudes are always nonnegative for closed spin foams. As a corollary, all open spin foams going between a fixed pair of spin networks have real amplitudes of the same sign. This means one can use the Metropolis algorithm to compute expectation values of observables in the Riemannian Barrett-Crane model, as in statistical mechanics, even though this theory is based on a real-time (e iS ) rather than imaginary-time e -S path integral. Our proof uses the fact that when the Riemannian 10j symbols are nonzero, their sign is positive or negative depending on whether the sum of the ten spins is an integer or half-integer. For the product of 10j symbols appearing in the amplitude for a closed spin foam, these signs cancel. We conclude with some numerical evidence suggesting that the Lorentzian 10j symbols are always nonnegative, which would imply similar results for the Lorentzian Barrett-Crane model

  7. Discontinuity formulas for multiparticle amplitudes

    International Nuclear Information System (INIS)

    Stapp, H.P.

    1976-03-01

    It is shown how discontinuity formulas for multiparticle scattering amplitudes are derived from unitarity and analyticity. The assumed analyticity property is the normal analytic structure, which was shown to be equivalent to the space-time macrocausality condition. The discontinuity formulas to be derived are the basis of multi-particle fixed-t dispersion relations

  8. Seismic amplitude processing and inversion

    Science.gov (United States)

    Dev, Ashwani

    2008-10-01

    Hydrocarbon exploration requires reliable seismic amplitudes to identify oil and gas reservoirs. Erroneous seismic amplitude processing can potentially generate large economic losses. Correct seismic amplitude processing is pre-requisite for any amplitude dependent analysis. The accuracy of the subsurface image and estimation of the elastic properties of subsurface sediments depends upon the reliability of the amplitudes. Geophone groups are wavenumber filters that change the seismic amplitudes because of a wavenumber dependent information loss. Numerically defined filters deconvolve the recording group response from horizontal and the vertical component seismic data recorded with groups of uniform and non-uniform geophone sensitivity, different group lengths and spacing, and noise. The filtering effect of an array increases as the group length increases, and only the wavenumber range defined by the group interval can be correctly compensated for the group effect. A rigorous, explicit spatial antialias filter is designed and applied by removing the energy above the first Nyquist wavenumber in the horizontal slowness-frequency domain. The filter removes the spatially aliased frequencies selectively at each slowness. The aliased energy is dispersive and present at both small and large horizontal slownesses. The filter can be explicitly applied to regularly spaced or irregularly spaced traces and is independent of any event linearity assumption. An integrative interpretation approach defines the effect of the structural setting on gas hydrate and free-gas accumulation at a site at the East Casey fault zone in the Gulf of Mexico. At a well location, hydrates are interpreted as fracture fillings with maximum saturation ˜30% of the available pore space. Two low acoustic impedance (Ip) free-gas features terminating at the bottom simulating reflector (BSR) are interpreted from the 3D seismic data and the derived Ip volumes. The 2D Ip profile shows a contrast in BSR

  9. Periodic instantons and scattering amplitudes

    International Nuclear Information System (INIS)

    Khlebnikov, S.Yu.; Rubakov, V.A.; Tinyakov, P.G.

    1991-04-01

    We discuss the role of periodic euclidean solutions with two turning points and zero winding number (periodic instantons) in instanton induced processes below the sphaleron energy E sph . We find that the periodic instantons describe certain multiparticle scattering events leading to the transitions between topologically distinct vacua. Both the semiclassical amplitudes and inital and final states of these transitions are determined by the periodic instantons. Furthermore, the corresponding probabilities are maximal among all states of given energy. We show that at E ≤ E sph , the periodic instantons can be approximated by infinite chains of ordinary instantons and anti-instantons, and they naturally emerge as deformations of the zero energy instanton. In the framework of 2d abelian Higgs model and 4d electroweak theory we show, however, that there is not obvious relation between periodic instantons and two-particle scattering amplitudes. (orig.)

  10. Forward amplitude in pion deuteron

    International Nuclear Information System (INIS)

    Ferreira, E.M.; Munguia, G.A.P.; Rosa, L.P.; Thome, Z.D.

    1979-06-01

    The data on total cross section for πd scattering is analysed in terms of a single scattering calculation with Fermi motion dependence, in order to obtain a criterion to fix the value of the energy entering the two body meson nucleon amplitude. It is found that the prescription derived from the non-relativistic three body kinematics gives reasonable results. The introduction of a shift in the energy value, possibly representing nuclear binding effects, leads to a very good fitting of the data. The results are compared with those obtained in direct calculations of Faddeev equations and with the Brueckner model of fixed scatterers. (Author) [pt

  11. Superstring amplitudes and contact interactions

    International Nuclear Information System (INIS)

    Greensite, J.

    1987-08-01

    We show that scattering amplitudes computed from light-cone superstring field theory are divergent at tree level. The divergences can be eliminated, and supersymmetry restored, by the addition of certain counter terms to the light-cone Hamiltonian. These counter terms have the form of local contact interactions, whose existence we had previously deduced on grounds of vacuum stability, and closure of the super-Poincare algebra. The quartic contact interactions required in Type I and Type IIB superstring theories are constructed in detail. (orig.)

  12. Amplitude modulation reflectometer for FTU

    International Nuclear Information System (INIS)

    Zerbini, M.; Buratti, P.; Centioli, C.; Amadeo, P.

    1995-06-01

    Amplitude modulation (AM) reflectometry is a modification of the classical frequency sweep technique which allows to perform unambiguous phase delay measurements. An eight-channel AM reflectometer has been realized for the measurement of density profiles on the FTU tokamak in the range. The characteristics of the instrument have been determined in extensive laboratory tests; particular attention has been devoted to the effect of interference with parasitic reflections. The reflectometer is now operating on FTU. Some examples of the first experimental data are discussed

  13. Expansion of Einstein-Yang-Mills amplitude

    Science.gov (United States)

    Fu, Chih-Hao; Du, Yi-Jian; Huang, Rijun; Feng, Bo

    2017-09-01

    In this paper, we study from various perspectives the expansion of tree level single trace Einstein-Yang-Mills amplitudes into linear combination of color-ordered Yang-Mills amplitudes. By applying the gauge invariance principle, a programable recursive construction is devised to expand EYM amplitude with arbitrary number of gravitons into EYM amplitudes with fewer gravitons. Based on this recursive technique we write down the complete expansion of any single trace EYM amplitude in the basis of color-order Yang-Mills amplitude. As a byproduct, an algorithm for constructing a polynomial form of the BCJ numerator for Yang-Mills amplitudes is also outlined in this paper. In addition, by applying BCFW recursion relation we show how to arrive at the same EYM amplitude expansion from the on-shell perspective. And we examine the EYM expansion using KLT relations and show how to evaluate the expansion coefficients efficiently.

  14. Constructing Amplitudes from Their Soft Limits

    Energy Technology Data Exchange (ETDEWEB)

    Boucher-Veronneau, Camille; Larkoski, Andrew J.; /SLAC

    2011-12-09

    The existence of universal soft limits for gauge-theory and gravity amplitudes has been known for a long time. The properties of the soft limits have been exploited in numerous ways; in particular for relating an n-point amplitude to an (n-1)-point amplitude by removing a soft particle. Recently, a procedure called inverse soft was developed by which 'soft' particles can be systematically added to an amplitude to construct a higher-point amplitude for generic kinematics. We review this procedure and relate it to Britto-Cachazo-Feng-Witten recursion. We show that all tree-level amplitudes in gauge theory and gravity up through seven points can be constructed in this way, as well as certain classes of NMHV gauge-theory amplitudes with any number of external legs. This provides us with a systematic procedure for constructing amplitudes solely from their soft limits.

  15. Grassmannian geometry of scattering amplitudes

    CERN Document Server

    Arkani-Hamed, Nima; Cachazo, Freddy; Goncharov, Alexander; Postnikov, Alexander; Trnka, Jaroslav

    2016-01-01

    Outlining a revolutionary reformulation of the foundations of perturbative quantum field theory, this book is a self-contained and authoritative analysis of the application of this new formulation to the case of planar, maximally supersymmetric Yang–Mills theory. The book begins by deriving connections between scattering amplitudes and Grassmannian geometry from first principles before introducing novel physical and mathematical ideas in a systematic manner accessible to both physicists and mathematicians. The principle players in this process are on-shell functions which are closely related to certain sub-strata of Grassmannian manifolds called positroids - in terms of which the classification of on-shell functions and their relations becomes combinatorially manifest. This is an essential introduction to the geometry and combinatorics of the positroid stratification of the Grassmannian and an ideal text for advanced students and researchers working in the areas of field theory, high energy physics, and the...

  16. Relative amplitude preservation processing utilizing surface consistent amplitude correction. Part 3; Surface consistent amplitude correction wo mochiita sotai shinpuku hozon shori. 3

    Energy Technology Data Exchange (ETDEWEB)

    Saeki, T. [Japan National Oil Corporation, Tokyo (Japan). Technology Research Center

    1996-10-01

    For the seismic reflection method conducted on the ground surface, generator and geophone are set on the surface. The observed waveforms are affected by the ground surface and surface layer. Therefore, it is required for discussing physical properties of the deep underground to remove the influence of surface layer, preliminarily. For the surface consistent amplitude correction, properties of the generator and geophone were removed by assuming that the observed waveforms can be expressed by equations of convolution. This is a correction method to obtain records without affected by the surface conditions. In response to analysis and correction of waveforms, wavelet conversion was examined. Using the amplitude patterns after correction, the significant signal region, noise dominant region, and surface wave dominant region would be separated each other. Since the amplitude values after correction of values in the significant signal region have only small variation, a representative value can be given. This can be used for analyzing the surface consistent amplitude correction. Efficiency of the process can be enhanced by considering the change of frequency. 3 refs., 5 figs.

  17. T-wave amplitude is related to physical fitness status.

    Science.gov (United States)

    Arbel, Yaron; Birati, Edo Y; Shapira, Itzhak; Topilsky, Yan; Wirguin, Michal; Canaani M D, Jonathan

    2012-07-01

    Abnormalities in repolarization may reflect underlying myocardial pathology and play a prominent role in arrhythmogenesis The T-wave amplitude has been associated with cardiovascular outcome in patients with acute myocardial infarction (MI) Additionally, T-wave amplitude is considered a predictor of arrhythmias, as well as being related to an individual's inflammatory status. The combined influence of different variables, such as inflammation, cardiovascular risk factors and physical fitness status, on the T-wave amplitude has not been evaluated to date. The aim of this study was to identify factors that affect the T-wave amplitude. Data from 255 consecutive apparently healthy individuals included in the Tel Aviv Medical Center Inflammation Survey (TAMCIS) were reviewed. All patients had undergone a physical examination and an exercise stress test, and different inflammatory and metabolic biomarkers (fibrinogen, potassium, and high-sensitivity C-reactive protein) were measured. Multivariate stepwise analysis revealed that the body mass index and the resting heart rate were significantly associated with the T-wave amplitude (β=-0.34, P physical fitness and not to his/her inflammatory status. ©2012, Wiley Periodicals, Inc.

  18. Composite superstring model for hadron amplitudes

    Energy Technology Data Exchange (ETDEWEB)

    Kudryavtsev, V.A. [Petersburg Nuclear Physics Institute, P.O. Box 188300, Gatchina (Russian Federation)

    2010-01-15

    Hadron dynamics is formulated in terms of interacting composite strings. These composite string amplitudes give other possible solution of duality equations for crossing channels in addition to classical string amplitudes. The composite strings carry quark flavour and spin degrees of freedom on edging two-dimensional surfaces. Consistent composite string models with extended N=3 Virasoro superconformal symmetry are found. Simple amplitudes for interaction of pi and K-mesons in this model are represented.

  19. New relations for graviton-matter amplitudes

    CERN Multimedia

    CERN. Geneva

    2018-01-01

    I report on recent progress in finding compact expressions for scattering amplitudes involving gravitons and gluons as well as massive scalar and fermionic matter particles. At tree level the single graviton emission amplitudes may be expressed as linear combination of purely non-gravitational ones. At the one-loop level recent results on all four point Einstein-Yang-Mills amplitudes with at most one opposite helicity state using unitarity methods are reported. 

  20. On the singularities of massive superstring amplitudes

    International Nuclear Information System (INIS)

    Foda, O.

    1987-01-01

    Superstring one-loop amplitudes with massive external states are shown to be in general ill-defined due to internal on-shell propagators. However, we argue that since any massive string state (in the uncompactified theory) has a finite lifetime to decay into massless particles, such amplitudes are not terms in the perturbative expansion of physical S-matrix elements: These can be defined only with massless external states. Consistent massive amplitudes repuire an off-shell formalism. (orig.)

  1. On the singularities of massive superstring amplitudes

    Energy Technology Data Exchange (ETDEWEB)

    Foda, O.

    1987-06-04

    Superstring one-loop amplitudes with massive external states are shown to be in general ill-defined due to internal on-shell propagators. However, we argue that since any massive string state (in the uncompactified theory) has a finite lifetime to decay into massless particles, such amplitudes are not terms in the perturbative expansion of physical S-matrix elements: These can be defined only with massless external states. Consistent massive amplitudes repuire an off-shell formalism.

  2. DVCS amplitude with kinematical twist-3 terms

    International Nuclear Information System (INIS)

    Radyushkin, A.V.; Weiss, C.

    2000-01-01

    The authors compute the amplitude of deeply virtual Compton scattering (DVCS) using the calculus of QCD string operators in coordinate representation. To restore the electromagnetic gauge invariance (transversality) of the twist-2 amplitude they include the operators of twist-3 which appear as total derivatives of twist-2 operators. The results are equivalent to a Wandzura-Wilczek approximation for twist-3 skewed parton distributions. They find that this approximation gives a finite result for the amplitude of a longitudinally polarized virtual photon, while the amplitude for transverse polarization is divergent, i.e., factorization breaks down in this term

  3. Robust seismic images amplitude recovery using curvelets

    NARCIS (Netherlands)

    Moghaddam, Peyman P.; Herrmann, Felix J.; Stolk, C.C.

    2007-01-01

    In this paper, we recover the amplitude of a seismic image by approximating the normal (demigration-migration) operator. In this approximation, we make use of the property that curvelets remain invariant under the action of the normal operator. We propose a seismic amplitude recovery method that

  4. Correlation of amplitude modulation to inflow characteristics

    DEFF Research Database (Denmark)

    Aagaard Madsen, Helge; Bertagnolio, Franck; Fischer, Andreas

    2014-01-01

    Amplitude modulation (AM) of noise from wind turbines and its more extreme version named “other amplitude modulation” OAM have been investigated intensively during the last few years due to the additional annoyance impact this type of noise has compared to broad band noise. In a recent published...

  5. On the singularities of massive superstring amplitudes

    NARCIS (Netherlands)

    Foda, O.

    1987-01-01

    Superstring one-loop amplitudes with massive external states are shown to be in general ill-defined due to internal on-shell propagators. However, we argue that since any massive string state (in the uncompactified theory) has a finite lifetime to decay into massless particles, such amplitudes are

  6. Amplitude image processing by diffractive optics.

    Science.gov (United States)

    Cagigal, Manuel P; Valle, Pedro J; Canales, V F

    2016-02-22

    In contrast to the standard digital image processing, which operates over the detected image intensity, we propose to perform amplitude image processing. Amplitude processing, like low pass or high pass filtering, is carried out using diffractive optics elements (DOE) since it allows to operate over the field complex amplitude before it has been detected. We show the procedure for designing the DOE that corresponds to each operation. Furthermore, we accomplish an analysis of amplitude image processing performances. In particular, a DOE Laplacian filter is applied to simulated astronomical images for detecting two stars one Airy ring apart. We also check by numerical simulations that the use of a Laplacian amplitude filter produces less noisy images than the standard digital image processing.

  7. Temporal Control of Metabolic Amplitude by Nocturnin

    Directory of Open Access Journals (Sweden)

    Jeremy J. Stubblefield

    2018-01-01

    Full Text Available The timing of food intake and nutrient utilization is critical to health and regulated partly by the circadian clock. Increased amplitude of circadian oscillations and metabolic output has been found to improve health in diabetic and obesity mouse models. Here, we report a function for the circadian deadenylase Nocturnin as a regulator of metabolic amplitude across the day/night cycle and in response to nutrient challenge. We show that mice lacking Nocturnin (Noct−/− display significantly increased amplitudes of mRNA expression of hepatic genes encoding key metabolic enzymes regulating lipid and cholesterol synthesis, both over the daily circadian cycle and in response to fasting and refeeding. Noct−/− mice have increased plasma triglyceride throughout the night and increased amplitude of hepatic cholesterol levels. Therefore, posttranscriptional control by Nocturnin regulates the amplitude of these critical metabolic pathways, and loss of this activity results in increased metabolic flux and reduced obesity.

  8. A mechanistic ultrasonic vibration amplitude model during rotary ultrasonic machining of CFRP composites.

    Science.gov (United States)

    Ning, Fuda; Wang, Hui; Cong, Weilong; Fernando, P K S C

    2017-04-01

    Rotary ultrasonic machining (RUM) has been investigated in machining of brittle, ductile, as well as composite materials. Ultrasonic vibration amplitude, as one of the most important input variables, affects almost all the output variables in RUM. Numerous investigations on measuring ultrasonic vibration amplitude without RUM machining have been reported. In recent years, ultrasonic vibration amplitude measurement with RUM of ductile materials has been investigated. It is found that the ultrasonic vibration amplitude with RUM was different from that without RUM under the same input variables. RUM is primarily used in machining of brittle materials through brittle fracture removal. With this reason, the method for measuring ultrasonic vibration amplitude in RUM of ductile materials is not feasible for measuring that in RUM of brittle materials. However, there are no reported methods for measuring ultrasonic vibration amplitude in RUM of brittle materials. In this study, ultrasonic vibration amplitude in RUM of brittle materials is investigated by establishing a mechanistic amplitude model through cutting force. Pilot experiments are conducted to validate the calculation model. The results show that there are no significant differences between amplitude values calculated by model and those obtained from experimental investigations. The model can provide a relationship between ultrasonic vibration amplitude and input variables, which is a foundation for building models to predict other output variables in RUM. Copyright © 2016 Elsevier B.V. All rights reserved.

  9. Speech production in amplitude-modulated noise

    DEFF Research Database (Denmark)

    Macdonald, Ewen N; Raufer, Stefan

    2013-01-01

    the consequences of temporally fluctuating noise. In the present study, 20 talkers produced speech in a variety of noise conditions, including both steady-state and amplitude-modulated white noise. While listening to noise over headphones, talkers produced randomly generated five word sentences. Similar...... to previous studies, talkers raised the level of their voice in steady-state noise. While talkers also increased the level of their voice in amplitude-modulated noise, the increase was not as large as that observed in steady-state noise. Importantly, for the 2 and 4 Hz amplitude-modulated noise conditions...

  10. Deficient fear conditioning in psychopathy as a function of interpersonal and affective disturbances

    Directory of Open Access Journals (Sweden)

    Ralf eVeit

    2013-10-01

    Full Text Available The diminished fear reactivity is one of the most valid physiological findings in psychopathy research. In a fear conditioning paradigm, with faces as conditioned stimulus (CS and electric shock as unconditioned stimulus (US, we investigated a sample of 14 high psychopathic violent offenders. Event related potentials, skin conductance responses (SCR as well as subjective ratings of the CSs were collected. This study assessed to which extent the different facets of the psychopathy construct contribute to the fear conditioning deficits observed in psychopaths. Participants with high scores on the affective facet subscale of the Psychopathy Checklist-Revised (PCL-R showed weaker conditioned fear responses and lower N100 amplitudes compared to low scorers. In contrast, high scorers on the affective facet rated the CS+ (paired more negatively than low scorers regarding the CS- (unpaired. Regarding the P300, high scores on the interpersonal facet were associated with increased amplitudes to the CS+ compared to the CS-, while the opposed pattern was found with the antisocial facet. Both, the initial and terminal contingent negative variation indicated a divergent pattern: participants with pronounced interpersonal deficits, showed increased cortical negativity to the CS+ compared to the CS-, whereas a reversed CS+/CS- differentiation was found in offenders scoring high on the antisocial facet. The present study revealed that deficient fear conditioning in psychopathy was most pronounced in offenders with high scores on the affective facet. Event related potentials suggest that participants with distinct interpersonal deficits showed increased information processing, whereas the antisocial facet was linked to decreased attention and interest to the CS+. These data indicate that an approach to the facets of psychopathy can help to resolve ambiguous findings in psychopathy research and enables a more precise and useful description of this disorder.

  11. Analytic continuation of dual Feynman amplitudes

    International Nuclear Information System (INIS)

    Bleher, P.M.

    1981-01-01

    A notion of dual Feynman amplitude is introduced and a theorem on the existence of analytic continuation of this amplitude from the convergence domain to the whole complex is proved. The case under consideration corresponds to massless power propagators and the analytic continuation is constructed on the propagators powers. Analytic continuation poles and singular set of external impulses are found explicitly. The proof of the theorem on the existence of analytic continuation is based on the introduction of α-representation for dual Feynman amplitudes. In proving, the so-called ''trees formula'' and ''trees-with-cycles formula'' are established that are dual by formulation to the trees and 2-trees formulae for usual Feynman amplitudes. (Auth.)

  12. Effective string theory and QCD scattering amplitudes

    International Nuclear Information System (INIS)

    Makeenko, Yuri

    2011-01-01

    QCD string is formed at distances larger than the confinement scale and can be described by the Polchinski-Strominger effective string theory with a nonpolynomial action, which has nevertheless a well-defined semiclassical expansion around a long-string ground state. We utilize modern ideas about the Wilson-loop/scattering-amplitude duality to calculate scattering amplitudes and show that the expansion parameter in the effective string theory is small in the Regge kinematical regime. For the amplitudes we obtain the Regge behavior with a linear trajectory of the intercept (d-2)/24 in d dimensions, which is computed semiclassically as a momentum-space Luescher term, and discuss an application to meson scattering amplitudes in QCD.

  13. Transition amplitudes within the stochastic quantization scheme

    International Nuclear Information System (INIS)

    Hueffel, H.

    1993-01-01

    Quantum mechanical transition amplitudes are calculated within the stochastic quantization scheme for the free nonrelativistic particle, the harmonic oscillator and the nonrelativistic particle in a constant magnetic field; we close with free Grassmann quantum mechanics. (authors)

  14. An analysis of heavy ion scattering amplitudes

    International Nuclear Information System (INIS)

    Marty, C.

    1979-01-01

    A heurisht method is derived for the analysis of light heavy ion systems. It consists in splitting an oscillatory amplitude into subamplitudes each of them being smooth, at least in modulus. Applications are given

  15. A new type time-amplitude converter

    International Nuclear Information System (INIS)

    Mou Haiwei; Han Jian; Li Zhongwei

    2004-01-01

    The time-amplitude converter is used mostly in nuclear physics experiments where require fast time measurement, such as the identify of particles, the measurement of excitated life-span and flying time of nucleon, and so on. According to the requirement of experiment, a new type time-amplitude converter composing of IC has been developed. It is precision is 100 ns. It has the merits of stable performance, higher precision and so on. (authors)

  16. Employing helicity amplitudes for resummation in SCET

    International Nuclear Information System (INIS)

    Moult, Ian; Stewart, Iain W.; Tackmann, Frank J.; Waalewijn, Wouter J.; Nikhef, Amsterdam

    2016-05-01

    Helicity amplitudes are the fundamental ingredients of many QCD calculations for multi-leg processes. We describe how these can seamlessly be combined with resummation in Soft-Collinear Effective Theory (SCET), by constructing a helicity operator basis for which the Wilson coefficients are directly given in terms of color-ordered helicity amplitudes. This basis is crossing symmetric and has simple transformation properties under discrete symmetries.

  17. Scattering amplitudes of regularized bosonic strings

    Science.gov (United States)

    Ambjørn, J.; Makeenko, Y.

    2017-10-01

    We compute scattering amplitudes of the regularized bosonic Nambu-Goto string in the mean-field approximation, disregarding fluctuations of the Lagrange multiplier and an independent metric about their mean values. We use the previously introduced Lilliputian scaling limit to recover the Regge behavior of the amplitudes with the usual linear Regge trajectory in space-time dimensions d >2 . We demonstrate a stability of this minimum of the effective action under fluctuations for d <26 .

  18. Effective gluon interactions from superstring disk amplitudes

    Energy Technology Data Exchange (ETDEWEB)

    Oprisa, D.

    2006-05-15

    In this thesis an efficient method for the calculation of the N-point tree-level string amplitudes is presented. Furthermore it is shown that the six-gluon open-superstring disk amplitude can be expressed by a basis of six triple hypergeometric functions, which encode the full {alpha}' dependence. In this connection material for obtaining the {alpha}' expansion of these functions is derived. Hereby many Euler-Zagier sums are calculated including multiple harmonic series. (HSI)

  19. The Cepheid bump progression and amplitude equations

    International Nuclear Information System (INIS)

    Kovacs, G.; Buchler, J.R.

    1989-01-01

    It is shown that the characteristic and systematic behavior of the low-order Fourier amplitudes and phases of hydrodynamically generated radial velocity and light curves of Cepheid model sequences is very well captured not only qualitatively but also quantitatively by the amplitude equation formalism. The 2:1 resonance between the fundamental and the second overtone plays an essential role in the behavior of the models 8 refs

  20. Maximum human objectively measured pharmacologically stimulated accommodative amplitude

    Directory of Open Access Journals (Sweden)

    Grzybowski A

    2018-01-01

    Full Text Available Andrzej Grzybowski,1,2 Ronald A Schachar,3 Magdalena Gaca-Wysocka,2 Ira H Schachar,4 Barbara K Pierscionek5 1Institute for Research in Ophthalmology, Foundation for Ophthalmology Development, Poznan, 2Department of Ophthalmology, University of Warmia and Mazury, Olsztyn, Poland; 3Department of Physics, University of Texas, Arlington, TX, 4Byers Eye Institute of Stanford University, Palo Alto, CA, USA; 5School of Science and Technology, Nottingham Trent University, Nottingham, UK Purpose: To measure the maximum, objectively measured, accommodative amplitude, produced by pharmacologic stimulation.Methods: Thirty-seven healthy subjects were enrolled, with a mean age of 20.2±1.1 years, corrected visual acuity of 20/20, and mean spherical equivalent refraction (SER =–0.83±1.60 diopters. For each subject, the right pupil was dilated with phenylephrine 10%. After 30 minutes, the pupil was measured, the left eye was patched, and the right eye was autorefracted. Pilocarpine 4% was then instilled in the right eye, followed by phenylephrine. At 45 minutes after the pilocarpine, autorefraction and pupil size were again measured.Results: Mean pupil size pre- and postpilocarpine was 8.0±0.8 mm and 4.4±1.9 mm, respectively. Pre- and postpilocarpine, the mean SER was –0.83±1.60 and –10.55±4.26 diopters, respectively. The mean pilocarpine-induced accommodative amplitude was 9.73±3.64 diopters. Five subjects had accommodative amplitudes ≥14.00 diopters. Accommodative amplitude was not significantly related to baseline SER (p-value =0.24, pre- or postpilocarpine pupil size (p-values =0.13 and 0.74, or change in pupil size (p-value =0.37. Iris color did not statistically significantly affect accommodative amplitude (p-value =0.83.Conclusion: Following topically applied pilocarpine, the induced objectively measured accommodation in the young eye is greater than or equal to the reported subjectively measured voluntary maximum accommodative

  1. Scattering amplitudes in open superstring theory

    Energy Technology Data Exchange (ETDEWEB)

    Schlotterer, Oliver

    2011-07-15

    The present thesis deals with the theme field of the scattering amplitudes in theories of open superstrings. Especially two different formalisms for the handling of superstrings are introduced and applied for the calaculation of tree-level amplitudes - the Ramond- Neveu-Schwarz (RNS) and the Pure-Spinor (PS) formalism. The RNS approach is proved as flexible in order to describe compactification of the initially ten flat space-time dimensions to four dimensions. We solve the technical problems, which result from the interacting basing world-sheet theory with conformal symmetry. This is used to calculate phenomenologically relevant scattering amplitudes of gluons and quarks as well as production rates of massive harmonic vibrations, which were already identified as virtual exchange particles on the massless level. In the case of a low string mass scale in the range of some Tev the string-specific signatures in parton collisions can be observed in the near future in the LHC experiment at CERN and indicated as first experimental proof of the string theory. THose string effects occur universally for a wide class of string ground states respectively internal geometries and represent an elegant way to avoid the so-called landscape problem of the string theory. A further theme complex in this thesis is based on the PS formalism, which allows a manifestly supersymmetric treatment of scattering amplitudes in ten space-time dimension with sixteen supercharges. We introduce a family of superfields, which occur in massless amplitudes of the open string and can be naturally identified with diagrams of three-valued knots. Thereby we reach not only a compact superspace representation of the n-point field-theory amplitude but can also write the complete superstring n-point amplitude as minimal linear combination of partial amplitudes of the field theory as well as hypergeometric functions. The latter carry the string effects and are analyzed from different perspectives, above all

  2. Direct amplitude detuning measurement with ac dipole

    Directory of Open Access Journals (Sweden)

    S. White

    2013-07-01

    Full Text Available In circular machines, nonlinear dynamics can impact parameters such as beam lifetime and could result in limitations on the performance reach of the accelerator. Assessing and understanding these effects in experiments is essential to confirm the accuracy of the magnetic model and improve the machine performance. A direct measurement of the machine nonlinearities can be obtained by characterizing the dependency of the tune as a function of the amplitude of oscillations (usually defined as amplitude detuning. The conventional technique is to excite the beam to large amplitudes with a single kick and derive the tune from turn-by-turn data acquired with beam position monitors. Although this provides a very precise tune measurement it has the significant disadvantage of being destructive. An alternative, nondestructive way of exciting large amplitude oscillations is to use an ac dipole. The perturbation Hamiltonian in the presence of an ac dipole excitation shows a distinct behavior compared to the free oscillations which should be correctly taken into account in the interpretation of experimental data. The use of an ac dipole for direct amplitude detuning measurement requires careful data processing allowing one to observe the natural tune of the machine; the feasibility of such a measurement is demonstrated using experimental data from the Large Hadron Collider. An experimental proof of the theoretical derivations based on measurements performed at injection energy is provided as well as an application of this technique at top energy using a large number of excitations on the same beam.

  3. Spinfoam cosmology with the proper vertex amplitude

    Science.gov (United States)

    Vilensky, Ilya

    2017-11-01

    The proper vertex amplitude is derived from the Engle-Pereira-Rovelli-Livine vertex by restricting to a single gravitational sector in order to achieve the correct semi-classical behaviour. We apply the proper vertex to calculate a cosmological transition amplitude that can be viewed as the Hartle-Hawking wavefunction. To perform this calculation we deduce the integral form of the proper vertex and use extended stationary phase methods to estimate the large-volume limit. We show that the resulting amplitude satisfies an operator constraint whose classical analogue is the Hamiltonian constraint of the Friedmann-Robertson-Walker cosmology. We find that the constraint dynamically selects the relevant family of coherent states and demonstrate a similar dynamic selection in standard quantum mechanics. We investigate the effects of dynamical selection on long-range correlations.

  4. Optical twists in phase and amplitude

    DEFF Research Database (Denmark)

    Daria, Vincent R.; Palima, Darwin; Glückstad, Jesper

    2011-01-01

    Light beams with helical phase profile correspond to photons having orbital angular momentum (OAM). A Laguerre-Gaussian (LG) beam is an example where its helical phase sets a phase-singularity at the optical axis and forms a ring-shaped transverse amplitude profile. Here, we describe a unique bea...... for cold atoms and for optical manipulation of microscopic particles.......Light beams with helical phase profile correspond to photons having orbital angular momentum (OAM). A Laguerre-Gaussian (LG) beam is an example where its helical phase sets a phase-singularity at the optical axis and forms a ring-shaped transverse amplitude profile. Here, we describe a unique beam...... where both phase and amplitude express a helical profile as the beam propagates in free space. Such a beam can be accurately referred to as an optical twister. We characterize optical twisters and demonstrate their capacity to induce spiral motion on particles trapped along the twisters’ path. Unlike LG...

  5. Cut-constructible part of QCD amplitudes

    International Nuclear Information System (INIS)

    Britto, Ruth; Feng Bo; Mastrolia, Pierpaolo

    2006-01-01

    Unitarity cuts are widely used in analytic computation of loop amplitudes in gauge theories such as QCD. We expand upon the technique introduced in hep-ph/0503132 to carry out any finite unitarity cut integral. This technique naturally separates the contributions of bubble, triangle and box integrals in one-loop amplitudes and is not constrained to any particular helicity configurations. Loop momentum integration is reduced to a sequence of algebraic operations. We discuss the extraction of the residues at higher-order poles. Additionally, we offer concise algebraic formulas for expressing coefficients of three-mass triangle integrals. As an application, we compute all remaining coefficients of bubble and triangle integrals for nonsupersymmetric six-gluon amplitudes

  6. Nonlinear (super)symmetries and amplitudes

    Energy Technology Data Exchange (ETDEWEB)

    Kallosh, Renata [Physics Department, Stanford University,382 Via Pueblo Mall, Stanford, CA 94305-4060 (United States)

    2017-03-07

    There is an increasing interest in nonlinear supersymmetries in cosmological model building. Independently, elegant expressions for the all-tree amplitudes in models with nonlinear symmetries, like D3 brane Dirac-Born-Infeld-Volkov-Akulov theory, were recently discovered. Using the generalized background field method we show how, in general, nonlinear symmetries of the action, bosonic and fermionic, constrain amplitudes beyond soft limits. The same identities control, for example, bosonic E{sub 7(7)} scalar sector symmetries as well as the fermionic goldstino symmetries. We present a universal derivation of the vanishing amplitudes in the single (bosonic or fermionic) soft limit. We explain why, universally, the double-soft limit probes the coset space algebra. We also provide identities describing the multiple-soft limit. We discuss loop corrections to N≥5 supergravity, to the D3 brane, and the UV completion of constrained multiplets in string theory.

  7. Amplitude-modulated fiber-ring laser

    DEFF Research Database (Denmark)

    Caputo, J. G.; Clausen, Carl A. Balslev; Sørensen, Mads Peter

    2000-01-01

    Soliton pulses generated by a fiber-ring laser are investigated by numerical simulation and perturbation methods. The mathematical modeling is based on the nonlinear Schrödinger equation with perturbative terms. We show that active mode locking with an amplitude modulator leads to a self-starting......Soliton pulses generated by a fiber-ring laser are investigated by numerical simulation and perturbation methods. The mathematical modeling is based on the nonlinear Schrödinger equation with perturbative terms. We show that active mode locking with an amplitude modulator leads to a self......-starting of stable solitonic pulses from small random noise, provided the modulation depth is small. The perturbative analysis leads to a nonlinear coupled return map for the amplitude, phase, and position of the soliton pulses circulating in the fiber-ring laser. We established the validity of this approach...

  8. Scaling of saturation amplitudes in baroclinic instability

    International Nuclear Information System (INIS)

    Shepherd, T.G.

    1994-01-01

    By using finite-amplitude conservation laws for pseudomomentum and pseudoenergy, rigorous upper bounds have been derived on the saturation amplitudes in baroclinic instability for layered and continuously-stratified quasi-geostrophic models. Bounds have been obtained for both the eddy energy and the eddy potential enstrophy. The bounds apply to conservative (inviscid, unforced) flow, as well as to forced-dissipative flow when the dissipation is proportional to the potential vorticity. This approach provides an efficient way of extracting an analytical estimate of the dynamical scalings of the saturation amplitudes in terms of crucial non-dimensional parameters. A possible use is in constructing eddy parameterization schemes for zonally-averaged climate models. The scaling dependences are summarized, and compared with those derived from weakly-nonlinear theory and from baroclinic-adjustment estimates

  9. Relativistic amplitudes in terms of wave functions

    International Nuclear Information System (INIS)

    Karmanov, V.A.

    1978-01-01

    In the framework of the invariant diagram technique which arises at the formulation of the fueld theory on the light front the question about conditions at which the relativistic amplitudes may be expressed through the wave functions is investigated. The amplitudes obtained depend on four-vector ω, determining the light front surface. The way is shown to find such values of the four-vector ω, at which the contribution of diagrams not expressed through wave functions is minimal. The investigation carried out is equivalent to the study of the dependence of amplitudes of the old-fashioned perturbation theory in the in the infinite momentum frame on direction of the infinite momentum

  10. Scattering Amplitudes and Worldsheet Models of QFTs

    CERN Multimedia

    CERN. Geneva

    2016-01-01

    I will describe recent progress on the study of scattering amplitudes via ambitwistor strings and the scattering equations. Ambitwistor strings are worldsheet models of quantum field theories, inspired by string theory. They naturally lead to a representation of amplitudes based on the scattering equations. While worldsheet models and related ideas have had a wide-ranging impact on the modern study of amplitudes, their direct application at loop level is a very recent success. I will show how a major difficulty in the loop-level story, the technicalities of higher-genus Riemann surfaces, can be avoided by turning the higher-genus surface into a nodal Riemann sphere, with the nodes representing the loop momenta. I will present new formulas for the one-loop integrands of gauge theory and gravity, with or without supersymmetry, and also some two-loop results.

  11. Amplitude Models for Discrimination and Yield Estimation

    Energy Technology Data Exchange (ETDEWEB)

    Phillips, William Scott [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-09-01

    This seminar presentation describes amplitude models and yield estimations that look at the data in order to inform legislation. The following points were brought forth in the summary: global models that will predict three-component amplitudes (R-T-Z) were produced; Q models match regional geology; corrected source spectra can be used for discrimination and yield estimation; three-component data increase coverage and reduce scatter in source spectral estimates; three-component efforts must include distance-dependent effects; a community effort on instrument calibration is needed.

  12. High energy multi-gluon exchange amplitudes

    International Nuclear Information System (INIS)

    Jaroszewicz, T.

    1980-11-01

    We examine perturbative high energy n-gluon exchange amplitudes calculated in the Coulomb gauge. If n exceeds the minimum required by the t-channel quantum numbers, such amplitudes are non-leading in lns. We derive a closed system of coupled integral equations for the corresponding two-particle n-gluon vertices, obtained by summing the leading powers of ln(N μ psup(μ)), where psup(μ) is the incident momentum and Nsup(μ) the gauge-defining vector. Our equations are infra-red finite, provided the external particles are colour singlets. (author)

  13. Singularity Structure of Maximally Supersymmetric Scattering Amplitudes

    DEFF Research Database (Denmark)

    Arkani-Hamed, Nima; Bourjaily, Jacob L.; Cachazo, Freddy

    2014-01-01

    We present evidence that loop amplitudes in maximally supersymmetric (N=4) Yang-Mills theory (SYM) beyond the planar limit share some of the remarkable structures of the planar theory. In particular, we show that through two loops, the four-particle amplitude in full N=4 SYM has only logarithmic ...... singularities and is free of any poles at infinity—properties closely related to uniform transcendentality and the UV finiteness of the theory. We also briefly comment on implications for maximal (N=8) supergravity theory (SUGRA)....

  14. Gluon scattering amplitudes at strong coupling

    Energy Technology Data Exchange (ETDEWEB)

    Alday, Luis F. [Institute for Theoretical Physics and Spinoza Institute, Utrecht University, 3508 TD Utrecht (Netherlands); Maldacena, Juan [School of Natural Sciences, Institute for Advanced Study, Princeton, NJ 08540 (United States)

    2007-06-15

    We describe how to compute planar gluon scattering amplitudes at strong coupling in N = 4 super Yang Mills by using the gauge/string duality. The computation boils down to finding a certain classical string configuration whose boundary conditions are determined by the gluon momenta. The results are infrared divergent. We introduce the gravity version of dimensional regularization to define finite quantities. The leading and subleading IR divergencies are characterized by two functions of the coupling that we compute at strong coupling. We compute also the full finite form for the four point amplitude and we find agreement with a recent ansatz by Bern, Dixon and Smirnov.

  15. Chiral symmetry constraints on resonant amplitudes

    Science.gov (United States)

    Bruns, Peter C.; Mai, Maxim

    2018-03-01

    We discuss the impact of chiral symmetry constraints on the quark-mass dependence of meson resonance pole positions, which are encoded in non-perturbative parametrizations of meson scattering amplitudes. Model-independent conditions on such parametrizations are derived, which are shown to guarantee the correct functional form of the leading quark-mass corrections to the resonance pole positions. Some model amplitudes for ππ scattering, widely used for the determination of ρ and σ resonance properties from results of lattice simulations, are tested explicitly with respect to these conditions.

  16. Scattering Amplitudes via Algebraic Geometry Methods

    DEFF Research Database (Denmark)

    Søgaard, Mads

    This thesis describes recent progress in the understanding of the mathematical structure of scattering amplitudes in quantum field theory. The primary purpose is to develop an enhanced analytic framework for computing multiloop scattering amplitudes in generic gauge theories including QCD without...... unitarity cuts. We take advantage of principles from algebraic geometry in order to extend the notion of maximal cuts to a large class of two- and three-loop integrals. This allows us to derive unique and surprisingly compact formulae for the coefficients of the basis integrals. Our results are expressed...

  17. The Joint Position-Amplitude Formulation for Hurricane State Estimation

    Science.gov (United States)

    Ravela, S.; Williams, J.; Emanuel, K.

    2008-12-01

    Classical formulations of data assimilation, whether sequential, ensemble-based or variational, are amplitude adjustment methods. Such approaches can perform poorly when forecast locations of weather systems are displaced from their observations. Compensating position errors by adjusting amplitudes can produce unacceptably 'distorted' states, adversely affecting analysis, verification and subsequent forecasts. There are many sources of position error. It is non-trivial to decompose position error into constituent sources and yet correcting position errors during assimilation can be essential for operationally predicting strong, localized weather events such as tropical cyclones. We will argue and show that if we assume a perfect world where forecast errors do not have position errors and have a Gaussian uncertainty, then in the real world, the bias or variance induced by position errors is the only reason for suboptimal performance of contemporary assimilation methods. Therefore, we propose a method that accounts for both position and amplitude errors using a variational approach. We show that the objective can be solved for position and amplitude decision variables using stochastic methods, thus corresponding with ensemble data assimilation. We then show that if an Euler-Lagrange approximation is made, can solve the objective nearly as well in two steps. This approach is entirely consistent with contemporary data assimilation practice. In the two-step approach, the first step is field alignment, where the current model state is aligned with observations by adjusting a continuous field of local displacements, subject to certain constraints. The second step is amplitude adjustment, where contemporary assimilation approaches are used. We will then demonstrate several choices of constraints on the displacement field, first starting with fluid-like viscous constraints and then proceeding to a multiscale wavelet representation that allows better balance in the

  18. The effect of music amplitude on the relaxation response.

    Science.gov (United States)

    Staum, M J; Brotons, M

    2000-01-01

    The purposes of this study were (a) to ascertain how 3 different volume levels of music affect the relaxation response both psychologically (preference scores and self-report) and physiologically (heart rate), (b) to determine the amplitude preference for relaxation among young adults, and (c) to compare differences in preference response between music and nonmusic majors and between the genders. One hundred forty-four college-age music and nonmusic majors were participants in this study. Subjects listened to 27 minutes of music while relaxing. The amplitude of the music was changed every 3 minutes in a randomized order so that each subject received loud (80-90 dB) medium (70-80 dB) or soft (60-70 dB) music 3 times each during the experimental period for a total of 9 amplitude changes. A sample of subjects wore a small heart rate monitor on their wrist and chest during the procedure. Simultaneously with the selected listening, they were encouraged to turn a dial on a Continuous Response Digital Interface (CRDI) indicating their amplitude preference for relaxation. Self-report information was gathered at the beginning and end of the experiment. Results of the CRDI analyses indicate that overall, subjects showed overwhelming preference for the soft music in comparison to medium or loud. Males, however, preferred the loud music more than females, and music majors preferred softer music over non-majors who preferred louder music. There were no differences attributed to amplitude level in the analysis of heart rate data. Analysis of the self report data yielded a wide variety of responses concerning their individual preferences, not always consistent with the empirical measures. Overall, there was an increase in relaxation reported over the duration of the experiment. Response differentiation to loudness levels indicates a long line of useful research not only on relaxation and stress reduction in health related fields, but also on the effects of background amplitude of

  19. Stora's fine notion of divergent amplitudes

    Directory of Open Access Journals (Sweden)

    Joseph C. Várilly

    2016-11-01

    Full Text Available Stora and coworkers refined the notion of divergent quantum amplitude, somewhat upsetting the standard power-counting recipe. This unexpectedly clears the way to new prototypes for free and interacting field theories of bosons of any mass and spin.

  20. Ward identities for amplitudes with reggeized gluons

    International Nuclear Information System (INIS)

    Bartles, J.; Vacca, G.P.

    2012-05-01

    Starting from the effective action of high energy QCD we derive Ward identities for Green's functions of reggeized gluons. They follow from the gauge invariance of the effective action, and allow to derive new representations of amplitudes containing physical particles as well as reggeized gluons. We explicitly demonstrate their validity for the BFKL kernel, and we present a new derivation of the kernel.

  1. Particle Distribution Modification by Low Amplitude Modes

    International Nuclear Information System (INIS)

    White, R.B.; Gorelenkov, N.; Heidbrink, W.W.; Van Zeeland, M.A.

    2009-01-01

    Modification of a high energy particle distribution by a spectrum of low amplitude modes is investigated using a guiding center code. Only through resonance are modes effective in modifying the distribution. Diagnostics are used to illustrate the mode-particle interaction and to find which effects are relevant in producing significant resonance, including kinetic Poincare plots and plots showing those orbits with time averaged mode-particle energy transfer. Effects of pitch angle scattering and drag are studied, as well as plasma rotation and time dependence of the equilibrium and mode frequencies. A specific example of changes observed in a DIII-D deuterium beam distribution in the presence of low amplitude experimentally validated Toroidal Alfven (TAE) eigenmodes and Reversed Shear Alfven (RSAE) eigenmodes is examined in detail. Comparison with experimental data shows that multiple low amplitude modes can account for significant modification of high energy beam particle distributions. It is found that there is a stochastic threshold for beam profile modification, and that the experimental amplitudes are only slightly above this threshold.

  2. Connected formulas for amplitudes in standard model

    Energy Technology Data Exchange (ETDEWEB)

    He, Song [CAS Key Laboratory of Theoretical Physics,Institute of Theoretical Physics, Chinese Academy of Sciences,Beijing 100190 (China); School of Physical Sciences, University of Chinese Academy of Sciences,No. 19A Yuquan Road, Beijing 100049 (China); Zhang, Yong [Department of Physics, Beijing Normal University,Beijing 100875 (China); CAS Key Laboratory of Theoretical Physics,Institute of Theoretical Physics, Chinese Academy of Sciences,Beijing 100190 (China)

    2017-03-17

    Witten’s twistor string theory has led to new representations of S-matrix in massless QFT as a single object, including Cachazo-He-Yuan formulas in general and connected formulas in four dimensions. As a first step towards more realistic processes of the standard model, we extend the construction to QCD tree amplitudes with massless quarks and those with a Higgs boson. For both cases, we find connected formulas in four dimensions for all multiplicities which are very similar to the one for Yang-Mills amplitudes. The formula for quark-gluon color-ordered amplitudes differs from the pure-gluon case only by a Jacobian factor that depends on flavors and orderings of the quarks. In the formula for Higgs plus multi-parton amplitudes, the massive Higgs boson is effectively described by two additional massless legs which do not appear in the Parke-Taylor factor. The latter also represents the first twistor-string/connected formula for form factors.

  3. Scattering amplitudes in super-renormalizable gravity

    International Nuclear Information System (INIS)

    Donà, Pietro; Giaccari, Stefano; Modesto, Leonardo; Rachwał, Lesław; Zhu, Yiwei

    2015-01-01

    We explicitly compute the tree-level on-shell four-graviton amplitudes in four, five and six dimensions for local and weakly nonlocal gravitational theories that are quadratic in both, the Ricci and scalar curvature with form factors of the d’Alembertian operator inserted between. More specifically we are interested in renormalizable, super-renormalizable or finite theories. The scattering amplitudes for these theories turn out to be the same as the ones of Einstein gravity regardless of the explicit form of the form factors. As a special case the four-graviton scattering amplitudes in Weyl conformal gravity are identically zero. Using a field redefinition, we prove that the outcome is correct for any number of external gravitons (on-shell n−point functions) and in any dimension for a large class of theories. However, when an operator quadratic in the Riemann tensor is added in any dimension (with the exception of the Gauss-Bonnet term in four dimensions) the result is completely altered, and the scattering amplitudes depend on all the form factors introduced in the action.

  4. Fatigue Reliability under Multiple-Amplitude Loads

    DEFF Research Database (Denmark)

    Talreja, R.

    1979-01-01

    A method to determine the fatigue of structures subjected to multiple-amplitude loads is presented. Unlike the more common cumulative damage methods, which are usually based on fatigue life data, the proposed method is based on tensile strength data. Assuming the Weibull distribution for the init...

  5. Kaon decay amplitudes using staggered fermions

    International Nuclear Information System (INIS)

    Sharpe, S.R.

    1986-12-01

    A status report is given of an attempt, using staggered fermions to calculate the real and imaginary parts of the amplitudes for K → ππ,. Semi-quantitative results are found for the imaginary parts, and these suggest that ε' might be smaller than previously expected in the standard model

  6. Effect of Stress Amplitude on the Damping of Recycled Aggregate Concrete.

    Science.gov (United States)

    Liang, Chaofeng; Liu, Tiejun; Xiao, Jianzhuang; Zou, Dujian; Yang, Qiuwei

    2015-08-14

    Damping characterizes the energy dissipation capacity of materials and structures, and it is affected by several external factors such as vibrating frequency, stress history, temperature, and stress amplitude. This study investigates the relationship between the damping and the stress amplitude of environment-friendly recycled aggregate concrete (RAC). First, a function model of a member's loss factor and stress amplitude was derived based on Lazan's damping-stress function. Then, the influence of stress amplitude on the loss tangent of RAC was experimentally investigated. Finally, parameters used to determine the newly derived function were obtained by numerical fitting. It is shown that the member's loss factor is affected not only by the stress amplitude but also by factors such as the cross section shapes, boundary conditions, load types, and loading positions. The loss tangent of RAC increases with the stress amplitude, even at low stress amplitude. The damping energy exponent of RAC is not identically equal to 2.0, indicating that the damping is nonlinear. It is also found that the energy dissipation capacity of RAC is superior to that of natural aggregate concrete (NAC), and the energy dissipation capacity can be further improved by adding modified admixtures.

  7. Differential equations, associators, and recurrences for amplitudes

    Directory of Open Access Journals (Sweden)

    Georg Puhlfürst

    2016-01-01

    Full Text Available We provide new methods to straightforwardly obtain compact and analytic expressions for ϵ-expansions of functions appearing in both field and string theory amplitudes. An algebraic method is presented to explicitly solve for recurrence relations connecting different ϵ-orders of a power series solution in ϵ of a differential equation. This strategy generalizes the usual iteration by Picard's method. Our tools are demonstrated for generalized hypergeometric functions. Furthermore, we match the ϵ-expansion of specific generalized hypergeometric functions with the underlying Drinfeld associator with proper Lie algebra and monodromy representations. We also apply our tools for computing ϵ-expansions for solutions to generic first-order Fuchsian equations (Schlesinger system. Finally, we set up our methods to systematically get compact and explicit α′-expansions of tree-level superstring amplitudes to any order in α′.

  8. Modified amplitude of the gravitational wave spectrum

    International Nuclear Information System (INIS)

    Ghayour, Basem; Suresh, P K

    2012-01-01

    The spectrum of thermal gravitational waves is obtained by including the high-frequency thermal gravitons created from extra-dimensional effects and is a new feature of the spectrum. The amplitude and spectral energy density of gravitational waves in a thermal vacuum state are found to be enhanced. The amplitude of the waves is modified in the frequency range (10 −16 –10 8 Hz) but the corresponding spectral energy density is less than the upper bound of various estimated results. With the addition of higher frequency thermal waves, the obtained spectral energy density of the wave in the thermal vacuum state does not exceed the upper bound put by the nucleosynthesis rate. The existence of cosmologically originated thermal gravitational waves due to extra dimension is not ruled out. (paper)

  9. Loop Amplitude Diagrams in Manifest, Maximal Supergravity

    Science.gov (United States)

    Karlsson, Anna

    The issue of finiteness of maximal supergravity has been subject to research for quite some time. Here, we approach that question through an examination of how to describe amplitude diagrams in D = 11 maximal supergravity from a field theory point of view. The strength of the formulation is the presence of manifest supersymmetry through the use of pure spinors. An initial analysis of what the subsequent characteristics turn out to be, partly in lower dimensions through dimensional reduction, gives at hand results that agree with previous work, pointing towards a first divergence for the 7-loop contribution to the 4-point amplitude in four dimensions. The text is mainly based on and may be regarded as an introduction to the main points presented there.

  10. Scattering Amplitudes via Algebraic Geometry Methods

    DEFF Research Database (Denmark)

    Søgaard, Mads

    unitarity cuts. We take advantage of principles from algebraic geometry in order to extend the notion of maximal cuts to a large class of two- and three-loop integrals. This allows us to derive unique and surprisingly compact formulae for the coefficients of the basis integrals. Our results are expressed...... in terms of certain linear combinations of multivariate residues and elliptic integrals computed from products of tree-level amplitudes. Several explicit examples are provided...

  11. A brief introduction to modern amplitude methods

    CERN Document Server

    Dixon, Lance J.

    2014-12-10

    I provide a basic introduction to modern helicity amplitude methods, including color organization, the spinor helicity formalism, and factorization properties. I also describe the BCFW (on-shell) recursion relation at tree level, and explain how similar ideas - unitarity and on-shell methods - work at the loop level. These notes are based on lectures delivered at the 2012 CERN Summer School and at TASI 2013.

  12. Phase analysis of amplitude binary mask structures

    Science.gov (United States)

    Puthankovilakam, Krishnaparvathy; Scharf, Toralf; Herzig, Hans Peter; Vogler, Uwe; Bramati, Arianna; Voelkel, Reinhard

    2016-03-01

    Shaping of light behind masks using different techniques is the milestone of the printing industry. The aerial image distribution or the intensity distribution at the printing distances defines the resolution of the structure after printing. Contrast and phase are the two parameters that play a major role in shaping of light to get the desired intensity pattern. Here, in contrast to many other contributions that focus on intensity, we discuss the phase evolution for different structures. The amplitude or intensity characteristics of the structures in a binary mask at different proximity gaps have been analyzed extensively for many industrial applications. But the phase evolution from the binary mask having OPC structures is not considered so far. The mask we consider here is the normal amplitude binary mask but having high resolution Optical Proximity Correction (OPC) structures for corners. The corner structures represent a two dimensional problem which is difficult to handle with simple rules of phase masks design and therefore of particular interest. The evolution of light from small amplitude structures might lead to high contrast by creating sharp phase changes or phase singularities which are points of zero intensity. We show the phase modulation at different proximity gaps and can visualize the shaping of light according to the phase changes. The analysis is done with an instrument called High Resolution Interference Microscopy (HRIM), a Mach-Zehnder interferometer that gives access to three-dimensional phase and amplitude images. The current paper emphasizes on the phase measurement of different optical proximity correction structures, and especially on corners of a binary mask.

  13. Deep Inelastic Scattering at the Amplitude Level

    International Nuclear Information System (INIS)

    Brodsky, Stanley J.

    2005-01-01

    The deep inelastic lepton scattering and deeply virtual Compton scattering cross sections can be interpreted in terms of the fundamental wavefunctions defined by the light-front Fock expansion, thus allowing tests of QCD at the amplitude level. The AdS/CFT correspondence between gauge theory and string theory provides remarkable new insights into QCD, including a model for hadronic wavefunctions which display conformal scaling at short distances and color confinement at large distances

  14. Transversity Amplitudes in Hypercharge Exchange Processes

    International Nuclear Information System (INIS)

    Aguilar Benitez de Lugo, M.

    1979-01-01

    ' In this work we present several techniques developed for the extraction of the. Transversity amplitudes governing quasi two-body meson baryon reactions with hypercharge exchange. We review the methods used in processes having a pure spin configuration, as well as the more relevant results obtained with data from K p and Tp interactions at intermediate energies. The predictions of the additive quark model and the ones following from exchange degeneracy and etoxicity are discussed. We present a formalism for amplitude analysis developed for reactions with mixed spin configurations and discuss the methods of parametric estimation of the moduli and phases of the amplitudes, as well as the various tests employed to check the goodness of the fits. The calculation of the generalized joint density matrices is given and we propose a method based on the generalization of the idea of multipole moments, which allows to investigate the structure of the decay angular correlations and establishes the quality of the fits and the validity of the simplifying assumptions currently used in this type of studies. (Author) 43 refs

  15. Differential equations for Feynman graph amplitudes

    International Nuclear Information System (INIS)

    Remiddi, E.

    1997-01-01

    It is by now well established that, by means of the integration by part identities all the integrals occurring in the evaluation of a Feynman graph of given topology can be expressed in terms of a few independent master integrals. It is shown in this paper that the integration by part identities can be further used for obtaining a linear system of first-order differential equations for the master integrals themselves. The equations con then be used for the numerical evaluation of the amplitudes as well as for investigating their analytic properties, such as the asymptotic and threshold behaviours and the corresponding expansions (and for analytic integration purposes, when possible). The new method is illustrated through its somewhat detailed application to the case of the one-loop self-mass amplitude, by explicitly working out expansions and quadrature formulas, both in arbitrary continuous dimension n and in the n→4 limit. It is then shortly discussed which features of the new method are expected to work in the more general case of multi-point, multi-loop amplitudes

  16. Amplitude analysis for hypercharge exchange reactions

    CERN Document Server

    Barger, V

    1972-01-01

    The s channel helicity non-flip amplitudes for the line reversed reactions pi N to K( Sigma , Lambda ) and KN to pi ( Sigma , Lambda ) are determined directly from cross-section and polarization data at 4 GeV/c. Rigorous bounds are obtained on the magnitudes of the flip amplitudes, whose phases are assumed to be given by an exchange degenerate K*-K** Regge trajectory. The solution for the non-flip amplitude is unique and shows the following characteristics: (i) Im K* ( Delta lambda =0) has a 'cross-over' zero at t approximately=-0.15 in both Sigma and Lambda reactions, (ii) Im K** ( Delta lambda =0) has an approximate double zero near t approximately=-0.6 in Sigma reactions and a positive minimum there in Lambda reactions, (iii) Re K* ( Delta lambda =0) and Re K** ( Delta lambda =0) are less peripheral in character than their imaginary counter-part and have similar behaviour at alpha =0 to simple Regge poles. (12 refs).

  17. Cascaded Amplitude Modulations in Sound Texture Perception

    Directory of Open Access Journals (Sweden)

    Richard McWalter

    2017-09-01

    Full Text Available Sound textures, such as crackling fire or chirping crickets, represent a broad class of sounds defined by their homogeneous temporal structure. It has been suggested that the perception of texture is mediated by time-averaged summary statistics measured from early auditory representations. In this study, we investigated the perception of sound textures that contain rhythmic structure, specifically second-order amplitude modulations that arise from the interaction of different modulation rates, previously described as “beating” in the envelope-frequency domain. We developed an auditory texture model that utilizes a cascade of modulation filterbanks that capture the structure of simple rhythmic patterns. The model was examined in a series of psychophysical listening experiments using synthetic sound textures—stimuli generated using time-averaged statistics measured from real-world textures. In a texture identification task, our results indicated that second-order amplitude modulation sensitivity enhanced recognition. Next, we examined the contribution of the second-order modulation analysis in a preference task, where the proposed auditory texture model was preferred over a range of model deviants that lacked second-order modulation rate sensitivity. Lastly, the discriminability of textures that included second-order amplitude modulations appeared to be perceived using a time-averaging process. Overall, our results demonstrate that the inclusion of second-order modulation analysis generates improvements in the perceived quality of synthetic textures compared to the first-order modulation analysis considered in previous approaches.

  18. Ethnic differences in electrocardiographic amplitude measurements

    International Nuclear Information System (INIS)

    Mansi, Ishak A.; Nash, Ira S.

    2004-01-01

    There is a controversy regarding ethnic differences in electrocardiographic (ECG) patterns because of the potentially confounding socioeconomic, nutritional, environmental and occupational factors. We reviewed the first 1000 medical files of a multiethnic community, where all individuals shared similar living conditions. Only healthy adults age 15 to 60 years were included. Wave amplitudes were measured manually from the standard 12lead ECG. Minnesota coding was used. ECG from 597 subjects were included in the study: 350 Saudi Arabians, 95 Indians, 17 Sri-Lankans, 39 Filipinos, and 57 Caucasians; 349 were men. the mean +-SD of Sokolow-Lyon voltage (SLV) in men was signifcantly different among ethnic groups (2.9+-0.86, 2.64+-0.79, 2.73+-0.72, 3.23+-0.61, 2.94+-0.6, 2.58+-0.79 mV, P=0.0006, for Saudi's, Indians, Jordanians, Filipinos, Sri-Lankans, and Caucasians, respectively). SLV was similar among ethnic groups in women. The prevalence of early transition pattern was also different among ethnic groups in men but not women (15.8%, 34.6%, 17.9%, 21.7%, 35.3%, 26.8% in Suadi, Indian, Jordanian, Filipino, Sri-Lankan, and Caucasian, respectively, P=0.037). T wave amplitude was significantly different among ethnic groups in selected lead. ECG wave amplitude differs with ethnic region even when other factors are similar. Using SLV of 3.5 mV as a criterion may overestimate the incidence of left ventricular hypertrophy in some ethnic groups. The pattern of high R wave in lead V1is common in healthy adults in certain ethnic groups. T wave height differs with ethnic origin and sex. (author)

  19. From correlation functions to scattering amplitudes

    Science.gov (United States)

    Eden, Burkhard; Korchemsky, Gregory P.; Sokatchev, Emery

    2011-12-01

    We study the correlation functions of half-BPS protected operators in mathcal{N} = {4} super-Yang-Mills theory, in the limit where the positions of adjacent operators become light-like separated. We compute the loop corrections by means of Lagrangian insertions. The divergences resulting from the light-cone limit are regularized by changing the dimension of the integration measure over the insertion points. Switching from coordinates to dual momenta, we show that the logarithm of the correlation function is identical with twice the logarithm of the matching MHV gluon scattering amplitude. We present a number of examples of this new relation, at one and two loops.

  20. Inlaying vertex function and scattering amplitude

    International Nuclear Information System (INIS)

    Naito, S.

    1997-01-01

    Scattering processes among strings are analyzed by using fundamental equations of three types, which divide the whole complex z-plane into various types of N punctured ring domains plus various unpunctured ring domains, where internal strings freely propagate. In order to calculate scattering amplitudes (among physical particles) in Witten close-quote s quantum string field theory, we derive and apply the open-quotes Gluing theorem,close-quote close-quote mathematical proof of which is given (in operator forms) by constructing various (inlint) conformal mapping operators. copyright 1997 American Institute of Physics

  1. Multiloop integrand reduction for dimensionally regulated amplitudes

    Science.gov (United States)

    Mastrolia, Pierpaolo; Mirabella, Edoardo; Ossola, Giovanni; Peraro, Tiziano

    2013-12-01

    We present the integrand reduction via multivariate polynomial division as a natural technique to encode the unitarity conditions of Feynman amplitudes. We derive a recursive formula for the integrand reduction, valid for arbitrary dimensionally regulated loop integrals with any number of loops and external legs, which can be used to obtain the decomposition of any integrand analytically with a finite number of algebraic operations. The general results are illustrated by applications to two-loop Feynman diagrams in QED and QCD, showing that the proposed reduction algorithm can also be seamlessly applied to integrands with denominators appearing with arbitrary powers.

  2. Getting superstring amplitudes by degenerating Riemann surfaces

    International Nuclear Information System (INIS)

    Matone, Marco; Volpato, Roberto

    2010-01-01

    We explicitly show how the chiral superstring amplitudes can be obtained through factorisation of the higher genus chiral measure induced by suitable degenerations of Riemann surfaces. This powerful tool also allows to derive, at any genera, consistency relations involving the amplitudes and the measure. A key point concerns the choice of the local coordinate at the node on degenerate Riemann surfaces that greatly simplifies the computations. As a first application, starting from recent ansaetze for the chiral measure up to genus five, we compute the chiral two-point function for massless Neveu-Schwarz states at genus two, three and four. For genus higher than three, these computations include some new corrections to the conjectural formulae appeared so far in the literature. After GSO projection, the two-point function vanishes at genus two and three, as expected from space-time supersymmetry arguments, but not at genus four. This suggests that the ansatz for the superstring measure should be corrected for genus higher than four.

  3. The Construction of Spin Foam Vertex Amplitudes

    Directory of Open Access Journals (Sweden)

    Eugenio Bianchi

    2013-01-01

    Full Text Available Spin foam vertex amplitudes are the key ingredient of spin foam models for quantum gravity. These fall into the realm of discretized path integral, and can be seen as generalized lattice gauge theories. They can be seen as an attempt at a 4-dimensional generalization of the Ponzano-Regge model for 3d quantum gravity. We motivate and review the construction of the vertex amplitudes of recent spin foam models, giving two different and complementary perspectives of this construction. The first proceeds by extracting geometric configurations from a topological theory of the BF type, and can be seen to be in the tradition of the work of Barrett, Crane, Freidel and Krasnov. The second keeps closer contact to the structure of Loop Quantum Gravity and tries to identify an appropriate set of constraints to define a Lorentz-invariant interaction of its quanta of space. This approach is in the tradition of the work of Smolin, Markopoulous, Engle, Pereira, Rovelli and Livine.

  4. Wrist proprioception: amplitude or position coding?

    Directory of Open Access Journals (Sweden)

    Francesca Marini

    2016-10-01

    Full Text Available This work examines physiological mechanisms underlying the position sense of the wrist, namely the codification of proprioceptive information related to pointing movements of the wrist towards kinesthetic targets. Twenty-four healthy subjects participated to a robot-aided assessment of their wrist proprioceptive acuity to investigate if the sensorimotor transformation involved in matching targets located by proprioceptive receptors relies on amplitude or positional cues. A joint position matching test was performed in order to explore such dichotomy. In this test, the wrist of a blindfolded participant is passively moved by a robotic device to a preset target position and, after a removal movement from this position, the participant has to actively replicate and match it as accurately as possible. The test involved two separate conditions: in the first the matching movements started from the same initial location; in the second one the initial location was randomly assigned. Target matching accuracy, precision and bias in the two conditions were then compared. Overall results showed a consistent higher performance in the former condition than in the latter, thus supporting the hypothesis that the joint position sense is based on vectorial or amplitude coding rather than positional.

  5. Scattering amplitudes with off-shell quarks

    Science.gov (United States)

    van Hameren, A.; Kutak, K.; Salwa, T.

    2013-11-01

    We present a prescription to calculate manifestly gauge invariant tree-level scattering amplitudes for arbitrary scattering processes with off-shell initial-state quarks within the kinematics of high-energy scattering. Consider the embedding of the process, in which the off-shell u-quark is replaced by an auxiliary quark qA, and an auxiliary photon γA is added in final state. The momentum flow is as if qA carries momentum k1 and the momentum of γA is identical to 0. γA only interacts via Eq. (3), and qA further only interacts with gluons via normal quark-gluon vertices. qA-line propagators are interpreted as iℓ̸1/(2ℓ1ṡp), and are diagonal in color space. Sum the squared amplitude over helicities of the auxiliary photon. For one helicity, simultaneously assign to the external qA-quark and to γA the spinor and polarization vector |ℓ1], {, {}. Multiply the amplitude with √{-x1k12/2}. For the rest, normal Feynman rules apply.Some remarks are at order. Regarding the momentum flow, we stress, as in [20], that momentum components proportional to k1 do not contribute in the eikonal propagators, and there is a freedom in the choice of the momenta flowing through qA-lines.Regarding the sum over helicities, one might argue that only one of them leads to a non-zero result for given helicity of the final-state quark, but there may, for example, be several identical such quarks in the final state with different helicities.In case of more than one quark in the final state with the same flavor as the off-shell quark, the rules as such admit graphs with γA-propagators. These must be omitted. They do not survive the limit Λ→∞ in the derivation, since the γA-propagators are suppressed by 1/Λ.The rules regarding the qA-line could be elaborated further like in [20], leading to simplified vertices for gluons attached to this line and reducing the numerator of the eikonal propagators to 1. Formulated as above, however, the prescription is more straightforward and

  6. Chronotype description: In search of a solid subjective amplitude scale.

    Science.gov (United States)

    Oginska, Halszka; Mojsa-Kaja, Justyna; Mairesse, Olivier

    2017-01-01

     scale indicated mediocre fit: chi-square/degree of freedom = 3.00, root mean square error of approximation = 0.09, standardized root mean square residual = 0.08, comparative fit index = 0.87, Tucker-Lewis index = 0.82. However, the results of Rasch analysis showed good fit statistics for all items: OUTFIT mean squares range from 0.63 to 1.34 and INFIT mean square range from 0.64 to 1.40. All observed values were ≤1.4, which confirmed the new scale as being unidimensional.f If to consider the chronotype in the context of the classical Borbely's two-process model of sleep regulation, it may be assumed that ME dimension relates to the tempo of increasing of sleep pressure during the day, that is, it reflects the homeostatic component of the diurnal rhythm of sleepiness. As to the amplitude, it may be supposed that more distinct rhythm (large amplitude) stands for greater vulnerability to the time of day - it resounds the circadian component of the sleep proneness. It seems that distinct diurnal changes of arousal indicate emotional lability and may be associated with emotional responsiveness, which in turn manifests itself in a characteristic style of coping with stressful situations. One may therefore consider the diurnal variability of arousal as a factor increasing individual susceptibility to mood swings and affective disorders.

  7. A Logarithmic-Amplitude Polar Diagram

    Directory of Open Access Journals (Sweden)

    Trond Andresen

    2001-04-01

    Full Text Available A polar diagram where the amplitude of the transfer function is on a logarithmic scale, is presented. This gives a one-size-fits-all diagram with no need for zooming in and out, and no need for additional reasoning about infinite-radius encirclements when there are poles on the imaginary axis - as opposed to what is usually neccessary with the standard polar (Nyquist- diagram. All properties needed for stability considerations are upheld, such as encirclements, gain and phase margins. The path for s in the loop transfer function is carefully chosen with regard to possible poles on the imaginary axis. Small excursions into the right half plane in the form of arcs of different-sized logarithmic spirals result in corresponding large but finite arcs that do not overlap in the logarithmic polar plots.

  8. Subleading soft graviton theorem for loop amplitudes

    Science.gov (United States)

    Sen, Ashoke

    2017-11-01

    Superstring field theory gives expressions for heterotic and type II string loop amplitudes that are free from ultraviolet and infrared divergences when the number of non-compact space-time dimensions is five or more. We prove the subleading soft graviton theorem in these theories to all orders in perturbation theory for S-matrix elements of arbitrary number of finite energy external states but only one external soft graviton. We also prove the leading soft graviton theorem for arbitrary number of finite energy external states and arbitrary number of soft gravitons. Since our analysis is based on general properties of one particle irreducible effective action, the results are valid in any theory of quantum gravity that gives finite result for the S-matrix order by order in perturbation theory without violating general coordinate invariance.

  9. Geological characteristics of low-amplitude faults

    Energy Technology Data Exchange (ETDEWEB)

    Matveyev, A.K.; Kozel' skiy, I.T.; Mazor, Yu.R.; Shimorina, Ye.F.; Stefanova, Ye.I.

    1982-01-01

    It is indicated that the faults which developed in the coal mass of the Kuznetsk Basin change the mineralogical-petrographic properties of the sedimentary rocks and coals. This results in a corresponding change in physical properties. The established local transformations of rocks associated with the formation of a fault (intensification of microfracturing in the quartz grains, increase in the content of quartz with structural defect, change in structural-textural features of rocks; decrease in the quantity of swelling blocks in mixed-stratified formations of the series montmorillonite-hydromica; change in the inner structure of coal, etc.) can be used to create new methods and techniques aimed at finding low amplitude disorders.

  10. Polynomial structures in one-loop amplitudes

    International Nuclear Information System (INIS)

    Britto, Ruth; Feng Bo; Yang Gang

    2008-01-01

    A general one-loop scattering amplitude may be expanded in terms of master integrals. The coefficients of the master integrals can be obtained from tree-level input in a two-step process. First, use known formulas to write the coefficients of (4-2ε)-dimensional master integrals; these formulas depend on an additional variable, u, which encodes the dimensional shift. Second, convert the u-dependent coefficients of (4-2ε)-dimensional master integrals to explicit coefficients of dimensionally shifted master integrals. This procedure requires the initial formulas for coefficients to have polynomial dependence on u. Here, we give a proof of this property in the case of massless propagators. The proof is constructive. Thus, as a byproduct, we produce different algebraic expressions for the scalar integral coefficients, in which the polynomial property is apparent. In these formulas, the box and pentagon contributions are separated explicitly.

  11. More on the duality correlators/amplitudes

    Energy Technology Data Exchange (ETDEWEB)

    Eden, Burkhard [Durham University, Science Laboratories, South Rd, Durham DH1 3LE (United Kingdom); Korchemsky, Gregory P., E-mail: gregory.korchemsky@cea.fr [Institut de Physique Theorique (Unite de Recherche Associee au CNRS URA 2306), CEA Saclay, 91191 Gif-sur-Yvette Cedex (France); Sokatchev, Emery [LAPTH (Laboratoire d' Annecy-le-Vieux de Physique Theorique, UMR 5108), Universite de Savoie, CNRS, B.P. 110, F-74941 Annecy-le-Vieux (France)

    2012-03-19

    We continue the study of n-point correlation functions of half-BPS protected operators in N=4 super-Yang-Mills theory, in the limit where the positions of the adjacent operators become light-like separated. We compute the l-loop corrections by making l Lagrangian insertions. We argue that there exists a simple relation between the (n+l)-point Born-level correlator with l Lagrangian insertions and the integrand of the n-particle l-loop MHV scattering amplitude, as obtained by the recent momentum twistor construction of Arkani-Hamed et al. We present several examples of this new duality, at one and two loops.

  12. Amplitude correlations for inelastic proton scattering from 48Ti

    International Nuclear Information System (INIS)

    Chou, B.H.; Mitchell, G.E.; Bilpuch, E.G.; Westerfeldt, C.R.

    1981-01-01

    The magnitudes and relative signs of inelastic proton channel amplitudes were determined for three decay channels for 45 5/2 + resonances in 49 V. The reduced widths in each channel follow a Porter-Thomas distribution, but extremely large amplitude correlations are observed - for one pair of channel amplitudes the relative sign is positive for 43 of 45 resonances. These results provide the first direct test of the Krieger-Porter reduced width amplitude distribution. (orig.)

  13. Correlations for reduced-width amplitudes in 49V

    International Nuclear Information System (INIS)

    Chou, B.H.; Mitchell, G.E.; Bilpuch, E.G.; Westerfeldt, C.R.

    1980-01-01

    Measurement of the relative sign of inelastic proton-channel amplitudes permits the determination of amplitude correlations. Data were obtained for 45 5/2 + resonances in 49 V. Although the reduced widths in each channel followed a Porter-Thomas distribution, large amplitude correlations were observed. The results are compared with the reduced-width--amplitude distribution of Krieger and Porter. This is the first direct test of the Krieger-Porter distribution

  14. MHV Vertices And Tree Amplitudes In Gauge Theory

    Energy Technology Data Exchange (ETDEWEB)

    Cachazo, Freddy; Svrcek, Peter; Witten, Edward E-mail: witten@ias.edu

    2004-09-01

    As an alternative to the usual Feynman graphs, tree amplitudes in Yang-Mills theory can be constructed from tree graphs in which the vertices are tree level MHV scattering amplitudes, continued off shell in a particular fashion. The formalism leads to new and relatively simple formulas for many amplitudes, and can be heuristically derived from twistor space. (author)

  15. MHV Vertices And Tree Amplitudes In Gauge Theory

    International Nuclear Information System (INIS)

    Cachazo, Freddy; Svrcek, Peter; Witten, Edward

    2004-01-01

    As an alternative to the usual Feynman graphs, tree amplitudes in Yang-Mills theory can be constructed from tree graphs in which the vertices are tree level MHV scattering amplitudes, continued off shell in a particular fashion. The formalism leads to new and relatively simple formulas for many amplitudes, and can be heuristically derived from twistor space. (author)

  16. A Clinical Research Study of Cognitive Dysfunction and Affective Impairment after Isolated Brainstem Stroke

    Directory of Open Access Journals (Sweden)

    Xiujuan Fu

    2017-12-01

    Full Text Available Although the function of the cerebellum in neurocognition has been well-documented, the similar role of the brainstem has yet to be fully elucidated. This clinical research study aimed to combine data relating to neuropsychological assessments and P300 to explore cognitive dysfunction and affective impairment following brainstem stroke. Thirty-four patients with isolated brainstem stroke and twenty-six healthy controls were recruited; for each patient, we collated data pertaining to the P300, Addenbrooke's Cognitive Examination III (ACE-III, Montreal Cognitive Assessment Chinese version (MoCA, trail-making test (TMT, Symbol Digit Modalities Test (SDMT, Wechsler Adult Intelligence Scale-Digit Spans (DS, Stroop test, Self Rating Depression Scale (SDS, and Self Rating Anxiety Scale (SAS. Significance was analyzed using an independent T-test or the Mann-Whitney U-test. Correlation was analyzed using Pearson's correlation analysis or Spearman's correlation analysis. Collectively, data revealed that brainstem stroke caused mild cognitive impairment (MCI, and that visuospatial, attention, linguistic, and emotional disturbances may occur after isolated brainstem stroke. Cognitive decline was linked to P300 latency, ACE-III, and MoCA; P300 latency was correlated with ACE-III. Patients with right brainstem lesions were more likely to suffer memory decline. The present study provides initial data relating to the role of the brainstem in neurocognition, and will be useful for further understanding of vascular cognitive and affective impairment.

  17. Roll dynamics of a ship sailing in large amplitude head waves

    NARCIS (Netherlands)

    Daalen, E.F.G.; Gunsing, M.; Grasman, J.; Remmert, J.

    2014-01-01

    Some ship types may show significant rolling when sailing in large-amplitude (near) head waves. The dynamics of the ship are such that the roll motion is affected by the elevation of the encountering waves. If the natural roll period (without forcing) is about half the period of the forcing by the

  18. Monodromies and the structure of gauge and gravity amplitudes

    Energy Technology Data Exchange (ETDEWEB)

    Vanhove, Pierre [IPhT - Institut de Physique Theorique, Orme des Merisiers bat. 774, PC 136, CEA/DSM/IPhT, CEA/Saclay, F-91191 Gif-sur-Yvette Cedex (France); Institut des Hautes Etudes Scientifiques - IHES, Le Bois-Marie 35, route de Chartres 91440 Bures-sur-Yvette (France)

    2010-07-01

    We show that different color-ordered tree-level amplitudes in gauge theories satisfy monodromy relations. These relations imply the existence of minimal basis of amplitude and provide the numerator factors of the amplitude for a parametrisation of the tree-level amplitude using only cubic vertices. Applications to supergravity amplitudes follow straightforwardly through the KLT-relations. Through the cuts, these tree-level relations give rise to non-trivial identities at loop level. At higher loop this constrains the critical ultraviolet behaviour of the four-graviton amplitude in N=8 supergravity to all order in perturbation. We argue this implies that the four-graviton N=8 amplitudes has a seven-loop logarithmic divergence in four dimensions. (author)

  19. Effects of amplitude modulation on perception of wind turbine noise

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Ki Seop; Lee, Soo Gab; Gwak, Doo Young [Dept. of Mechanical and Aerospace Engineering, Seoul National University, Seoul (Korea, Republic of); Seong, Yeol Wan [Ammunition Engineering Team, Defense Agency for Technology and Quality, Daejeon (Korea, Republic of); Lee, Seung Hoon [Aerodynamics Research Team, Korea Aerospace Research Institute, Daejeon (Korea, Republic of); Hong, Ji Young [Transportation Environmental Research Team, Green Transport and Logistics Institute, Korea Railroad Research Institute, Uiwang (Korea, Republic of)

    2016-10-15

    Wind turbine noise is considered to be easily detectable and highly annoying at relatively lower sound levels than other noise sources. Many previous studies attributed this characteristic to amplitude modulation. However, it is unclear whether amplitude modulation is the main cause of these properties of wind turbine noise. Therefore, the aim of the current study is to identify the relationship between amplitude modulation and these two properties of wind turbine noise. For this investigation, two experiments were conducted. In the first experiment, 12 participants determined the detection thresholds of six target sounds in the presence of background noise. In the second experiment, 12 participants matched the loudness of modified sounds without amplitude modulation to that of target sounds with amplitude modulation. The results showed that the detection threshold was lowered as the modulation depth increased; additionally, sounds with amplitude modulation had higher subjective loudness than those without amplitude modulation.

  20. Effects of amplitude modulation on perception of wind turbine noise

    International Nuclear Information System (INIS)

    Yoon, Ki Seop; Lee, Soo Gab; Gwak, Doo Young; Seong, Yeol Wan; Lee, Seung Hoon; Hong, Ji Young

    2016-01-01

    Wind turbine noise is considered to be easily detectable and highly annoying at relatively lower sound levels than other noise sources. Many previous studies attributed this characteristic to amplitude modulation. However, it is unclear whether amplitude modulation is the main cause of these properties of wind turbine noise. Therefore, the aim of the current study is to identify the relationship between amplitude modulation and these two properties of wind turbine noise. For this investigation, two experiments were conducted. In the first experiment, 12 participants determined the detection thresholds of six target sounds in the presence of background noise. In the second experiment, 12 participants matched the loudness of modified sounds without amplitude modulation to that of target sounds with amplitude modulation. The results showed that the detection threshold was lowered as the modulation depth increased; additionally, sounds with amplitude modulation had higher subjective loudness than those without amplitude modulation

  1. The pulsed amplitude unit for the SLC

    International Nuclear Information System (INIS)

    Rolfe, J.; Browne, M.J.; Jobe, R.K.

    1987-02-01

    There is a recurring requirement in the SLC for the control of devices such as magnets, phase shifters, and attenuators on a beam-by-beam basis. The Pulsed Amplitude Unit (PAU) is a single width CAMAC module developed for this purpose. It provides digitally programmed analog output voltages on a beam-by-beam basis. Up to 32 preprogrammed values of output voltage are available from the single analog output of the module, and any of these values can be associated with any of the 256 possible SLC beam definitions. A 12-bit Analog-to-Digital Converter (ADC) digitizes an analog input signal at the appropriate beam time and stores it in a buffer memory. This feature is normally used to monitor the response of the device being controlled by the PAU at each beam time. Initial application of the PAU is a part of the system that controls the output of Klystrons in the SLC. The PAU combines several different functions in a single module. In order to accommodate these functions in a single width CAMAC module, field programmed logic is used extensively. Field Programmable Logic Arrays, Programmed Array Logic, and a Field Programmable Logic Sequencer are employed

  2. Gearbox Vibration Signal Amplitude and Frequency Modulation

    Directory of Open Access Journals (Sweden)

    Fakher Chaari

    2012-01-01

    Full Text Available Gearboxes usually run under fluctuating load conditions during service, however most of papers available in the literature describe models of gearboxes under stationary load conditions. Main task of published papers is fault modeling for their detection. Considering real situation from industry, the assumption of stationarity of load conditions cannot be longer kept. Vibration signals issued from monitoring in maintenance operations differ from mentioned models (due to load non-stationarity and may be difficult to analyze which lead to erroneous diagnosis of the system. The objective of this paper is to study the influence of time varying load conditions on a gearbox dynamic behavior. To investigate this, a simple spur gear system without defects is modeled. It is subjected to a time varying load. The speed-torque characteristic of the driving motor is considered. The load variation induces speed variation, which causes a variation in the gearmesh stiffness period. Computer simulation shows deep amplitude modulations with sidebands that don't differ from those obtained when there is a defective tooth. In order to put in evidence the time varying load effects, Short Time Fourier Transform and then Smoothed Wigner-Ville distribution are used. Results show that the last one is well suited for the studied case.

  3. An amplitude modulated radio frequency plasma generator

    Science.gov (United States)

    Lei, Fan; Li, Xiaoping; Liu, Yanming; Liu, Donglin; Yang, Min; Xie, Kai; Yao, Bo

    2017-04-01

    A glow discharge plasma generator and diagnostic system has been developed to study the effects of rapidly variable plasmas on electromagnetic wave propagation, mimicking the plasma sheath conditions encountered in space vehicle reentry. The plasma chamber is 400 mm in diameter and 240 mm in length, with a 300-mm-diameter unobstructed clear aperture. Electron densities produced are in the mid 1010 electrons/cm3. An 800 W radio frequency (RF) generator is capacitively coupled through an RF matcher to an internally cooled stainless steel electrode to form the plasma. The RF power is amplitude modulated by a waveform generator that operates at different frequencies. The resulting plasma contains electron density modulations caused by the varying power levels. A 10 GHz microwave horn antenna pair situated on opposite sides of the chamber serves as the source and detector of probe radiation. The microwave power feed to the source horn is split and one portion is sent directly to a high-speed recording oscilloscope. On mixing this with the signal from the pickup horn antenna, the plasma-induced phase shift between the two signals gives the path-integrated electron density with its complete time dependent variation. Care is taken to avoid microwave reflections and extensive shielding is in place to minimize electronic pickup. Data clearly show the low frequency modulation of the electron density as well as higher harmonics and plasma fluctuations.

  4. Effective anisotropy through traveltime and amplitude matching

    KAUST Repository

    Wang, Hui

    2014-08-05

    Introducing anisotropy to seismic wave propagation reveals more realistic physics of our Earth\\'s subsurface as compared to the isotropic assumption. However wavefield modeling, the engine of seismic inverse problems, in anisotropic media still suffers from computational burdens, in particular with complex anisotropy such as transversely isotropic (TI) and Orthorhombic anisotropy. We develop effective isotropic velocity and density models to package the effects of anisotropy such that the wave propagation behavior using these effective models approximate those of the original anisotropic model. We build these effective models through the high frequency asymptotic approximation based on the eikonal and transport equations. We match the geometrical behavior of the wave-fields, given by traveltimes, from the anisotropic and isotropic eikonal equations. This matching yields the effective isotropic velocity that approximates the kinematics of the anisotropic wavefield. Equivalently, we calculate the effective densities by equating the anisotropic and isotropic transport equations. The effective velocities and densities are then fed into the isotropic acoustic variable density wave equation to obtain cheaper anisotropic wavefields. We justify our approach by testing it on an elliptical anisotropic model. The numerical results demonstrate a good matching of both traveltime and amplitude between anisotropic and effective isotropic wavefields.

  5. Casimir amplitudes in topological quantum phase transitions.

    Science.gov (United States)

    Griffith, M A; Continentino, M A

    2018-01-01

    Topological phase transitions constitute a new class of quantum critical phenomena. They cannot be described within the usual framework of the Landau theory since, in general, the different phases cannot be distinguished by an order parameter, neither can they be related to different symmetries. In most cases, however, one can identify a diverging length at these topological transitions. This allows us to describe them using a scaling approach and to introduce a set of critical exponents that characterize their universality class. Here we consider some relevant models of quantum topological transitions associated with well-defined critical exponents that are related by a quantum hyperscaling relation. We extend to these models a finite-size scaling approach based on techniques for calculating the Casimir force in electromagnetism. This procedure allows us to obtain universal Casimir amplitudes at their quantum critical points. Our results verify the validity of finite-size scaling in these systems and confirm the values of the critical exponents obtained previously.

  6. Open string topological amplitudes and gaugino masses

    International Nuclear Information System (INIS)

    Antoniadis, I.; Narain, K.S.; Taylor, T.R.

    2005-09-01

    We discuss the moduli-dependent couplings of the higher derivative F-terms (TrW 2 ) h-1 , where W is the gauge N =1 chiral superfield. They are determined by the genus zero topological partition function F (0,h) , on a world-sheet with h boundaries. By string duality, these terms are also related to heterotic topological amplitudes studied in the past, with the topological twist applied only in the left-moving supersymmetric sector of the internal N =(2,0) superconformal field theory. The holomorphic anomaly of these couplings relates them to terms of the form Π n (TrW 2 ) h-2 , where Π's represent chiral projections of non-holomorphic functions of chiral superfields. An important property of these couplings is that they violate R-symmetry for h ≥ 3. As a result, once supersymmetry is broken by D-term expectation values, (TrW 2 ) 2 generates gaugino masses that can be hierarchically smaller than the scalar masses, behaving as m 1/2 ∼ m 0 4 in string units. Similarly, ΠTrW 2 generates Dirac masses for non-chiral brane fermions, of the same order of magnitude. This mechanism can be used for instance to obtain fermion masses at the TeV scale for scalar masses as high as m 0 ∼ O (10 13 ) GeV. We present explicit examples in toroidal string compactifications with intersecting D-branes. (author)

  7. Efficient reverse time migration with amplitude encoding

    Science.gov (United States)

    Hu, Jiangtao; Wang, Huazhong; Zhao, Lei; Shao, Yu; Wang, Meixia; Osen, Are

    2015-08-01

    Reverse time migration (RTM) is an accurate seismic imaging method for imaging the complex subsurface structure. Traditional common shot RTM suffers from low efficiency due to the large number of single shot gathers, especially for marine seismic data. Phase encoding is commonly used to reduce the computational cost of RTM. Phase encoding in the frequency domain is usually related to time shift in the time domain. Therefore, phase-encoding-based RTM needs time padding to avoid information loss which degrades the efficiency of the time-domain wavefield extrapolator. In this paper, an efficient time-domain RTM scheme based on the amplitude encoding is proposed. This scheme uses the orthogonal cosine basis as the encoding function, which has similar physical meaning to plane wave encoding (i.e. plane-wave components with different surface shooting angles). The proposed scheme can generate a qualified imaging result as well as common shot RTM but with less computational cost. Since this scheme does not need time padding, it is more efficient than the phase encoding schemes and can be conveniently implemented in the time domain. Numerical examples on the Sigsbee2a synthetic dataset demonstrate the feasibility of the proposed method.

  8. Electroweak amplitudes in chiral quark models

    International Nuclear Information System (INIS)

    Fiolhais, Manuel

    2004-01-01

    After referring to some basic features of chiral models for baryons, with quarks and mesons, we describe how to construct model states representing physical baryons. We consider soliton models such as the Linear Sigma Model or the Chromodielectric Model, and bag models such as the Cloudy Bag Model. These models are solved approximately using variational approaches whose starting point is a mean-field description. We go beyond the mean-field description by introducing quantum fluctuations in the mesonic degrees of freedom. This is achieved, in a first step, by using a quantum state to represent meson clouds and, secondly, by performing an angular momentum and isospin projection from the mean-field state (actually a coherent state). Model states for baryons (nucleon, Delta, Roper) constructed in this way are used to determine several physical properties. I this seminar we paid a particular attention to the nucleon-delta electromagnetic and weak transition, presenting the model predictions for the electromagnetic and axial amplitudes

  9. Casimir amplitudes in topological quantum phase transitions

    Science.gov (United States)

    Griffith, M. A.; Continentino, M. A.

    2018-01-01

    Topological phase transitions constitute a new class of quantum critical phenomena. They cannot be described within the usual framework of the Landau theory since, in general, the different phases cannot be distinguished by an order parameter, neither can they be related to different symmetries. In most cases, however, one can identify a diverging length at these topological transitions. This allows us to describe them using a scaling approach and to introduce a set of critical exponents that characterize their universality class. Here we consider some relevant models of quantum topological transitions associated with well-defined critical exponents that are related by a quantum hyperscaling relation. We extend to these models a finite-size scaling approach based on techniques for calculating the Casimir force in electromagnetism. This procedure allows us to obtain universal Casimir amplitudes at their quantum critical points. Our results verify the validity of finite-size scaling in these systems and confirm the values of the critical exponents obtained previously.

  10. A tactile P300 brain-computer interface

    NARCIS (Netherlands)

    Brouwer, A.M.; Erp, J.B.F. van

    2010-01-01

    De werking van de eerste Brain-Computer-Interface gebaseerd op tactiele EEG response wordt gedemonstreerd en het effect van het aantal gebruikte vibro-tactiele tactoren en stimulus-timing parameters wordt onderzocht

  11. P300-based brain computer interface experimental setup

    NARCIS (Netherlands)

    Arboleda, C.; Garcia Cossio, E.; Posada, A.; Torres, R.

    2009-01-01

    A Brain-Computer interface (BCI) is a communication system that enables the generation of a control signal from brain signals such as sensorymotor rhythms and evoked potentials; therefore, it constitutes a novel communication option for people with severe motor disabilities (such as Amyotrophic

  12. Transversity Amplitudes in Hypercharge Exchange Processes; Amplitudes de transversidad en procesos de intercambio de hipercarga

    Energy Technology Data Exchange (ETDEWEB)

    Aguilar Benitez de Lugo, M.

    1979-07-01

    In this work we present several techniques developed for the extraction of the. Transversity amplitudes governing quasi two-body meson baryon reactions with hypercharge exchange. We review the methods used In processes having a pure spin configuration, as well as the more relevant results obtained with data from K{sup p} and Tp interactions at intermediate energies. The predictions of the additive quark model and the ones following from exchange degeneracy and etoxicity are discussed. We present a formalism for amplitude analysis developed for reactions with mixed spin configurations and discuss the methods of parametric estimation of the moduli and phases of.the amplitudes, as well as the various tests employed to check the goodness of the fits. The calculation of the generalized joint density matrices is given and we propose a method based on the generalization of the idea of multipole moments, which allows to investigate the structure of the decay angular correlations and establishes the quality of the fits and the validity of the simplifying assumptions currently used in this type of studies. (Author) 43 refs.

  13. Secure communication based on multi-input multi-output chaotic system with large message amplitude

    International Nuclear Information System (INIS)

    Zheng, G.; Boutat, D.; Floquet, T.; Barbot, J.P.

    2009-01-01

    This paper deals with the problem of secure communication based on multi-input multi-output (MIMO) chaotic systems. Single input secure communication based on chaos can be easily extended to multiple ones by some combinations technologies, however all the combined inputs possess the same risk to be broken. In order to reduce this risk, a new secure communication scheme based on chaos with MIMO is discussed in this paper. Moreover, since the amplitude of messages in traditional schemes is limited because it would affect the quality of synchronization, the proposed scheme is also improved into an amplitude-independent one.

  14. Anisotropic amplitude variation of the bottom-simulating reflector beneath fracture-filled gas hydrate deposit

    Digital Repository Service at National Institute of Oceanography (India)

    Sriram, G.; Dewangan, P.; Ramprasad, T.; RamaRao, P.

    and densities across the GHSZ govern the amplitude variation with angle (AVA) of BSRs which can be studied from the multi-channel seismic data. AVA patterns can be classified into four categories (I-IV) depending on the intercept and gradient [Ostrander... is to remove the known factors other than reflection that can affect the amplitude of the reflection. Another important factor in the AVA analysis is the choice of an appropriate rock-physics model that governs the relationship between the P- and S...

  15. Investigation of boiling water reactor stability and limit-cycle amplitude

    International Nuclear Information System (INIS)

    Damiano, B.; March-Leuba, J.A.; Euler, J.A.

    1991-01-01

    Galerkin's method has been applied to a boiling water reactor (BWR) dynamics model consisting of the point kinetics equations, which describe the neutronics, and a feedback transfer function, which describes the thermal hydraulics. The result is a low-order approximate solution describing BWR behavior during small-amplitude limit-cycle oscillations. The approximate solution has been used to obtain a stability condition, show that the average reactor power must increase during limit-cycle oscillations, and qualitatively determine how changes in transfer function values affect the limit-cycle amplitude. 6 refs., 2 figs., 2 tabs

  16. SU-F-T-253: Volumetric Comparison Between 4D CT Amplitude and Phase Binning Mode

    Energy Technology Data Exchange (ETDEWEB)

    Yang, G; Ma, R; Reyngold, M [Memorial Sloan-Kettering Cancer Center, Commack, NY (United States); Li, X; Xiong, W; Gewanter, R [Memorial Sloan-Kettering Cancer Center, Rockville Center, NY (United States); Yorke, E; Mageras, G; Wu, A; Deasy, J; Hunt, M [Memorial Sloan-Kettering Cancer Center, New York, NY (United States); Tang, X [Memorial Sloan-Kettering Cancer Center, West Harrison, NY (United States); Chan, M [Memorial Sloan-Kettering Cancer Center, Basking Ridge, NJ (United States)

    2016-06-15

    Purpose: Motion artifact in 4DCT images can affect radiation treatment quality. To identify the most robust and accurate binning method, we compare the volume difference between targets delineated on amplitude and phase binned 4DCT scans. Methods: Varian RPM system and CT scanner were used to acquire 4DCTs of a Quasar phantom with embedded cubic and spherical objects having superior-inferior motion. Eight patients’ respiration waveforms were used to drive the phantom. The 4DCT scan was reconstructed into 10 phase and 10 amplitude bins (2 mm slices). A scan of the static phantom was also acquired. For each waveform, sphere and cube volumes were generated automatically on each phase using HU thresholding. Phase (amplitude) ITVs were the union of object volumes over all phase (amplitude) binned images. The sphere and cube volumes measured in the static phantom scan were V{sub sphere}=4.19cc and V{sub cube}=27.0cc. Volume difference (VD) and dice similarity coefficient (DSC) of the ITVs, and mean volume error (MVE) defined as the average target volume percentage difference between each phase image and the static image, were used to evaluate the performance of amplitude and phase binning. Results: Averaged over the eight breathing traces, the VD and DSC of the internal target volume (ITV) between amplitude and phase binning were 3.4%±3.2% (mean ± std) and 95.9%±2.1% for sphere; 2.1%±3.3% and 98.0% ±1.5% for cube, respectively.For all waveforms, the average sphere MVE of amplitude and phase binning was 6.5% ± 5.0% and 8.2%±6.3%, respectively; and the average cube MVE of amplitude and phase binning was 5.7%±3.5%and 12.9%±8.9%, respectively. Conclusion: ITV volume and spatial overlap as assessed by VD and DSC are similar between amplitude and phase binning. Compared to phase binning, amplitude binning results in lower MVE suggesting it is less susceptible to motion artifact.

  17. The Effect of Amplitude Modulation on the Axial Resolution of Doppler-Based Ultrasonic Topography Measurement

    DEFF Research Database (Denmark)

    RezaNejad Gatabi, Javad; Das, Sayantan; Forouzbakhsh, Farshid

    2016-01-01

    Ultrasonic Doppler-based systems for surface topography measurements are attractive alternatives to the transit-time-based methods. Sensors used in Doppler systems are less dependent on the speed of the sound in air, although contemporary Doppler measurement systems are sensitive to the amplitude...... variation of the received signal. Amplitude variation significantly affects the measurement accuracy when the surface axial displacement range is comparable with the ultrasonic wavelength. This paper presents a theoretical and experimental study of the effect of amplitude modulation on the performance...... of the Doppler measurement techniques. A modified Doppler measurement system that significantly improves the measurement accuracy is also presented. The fabricated sensor has 72-μm measurement accuracy using 40-kHz transducers. This technique can also be employed in cost-effective displacement measurement...

  18. Relative amplitude preservation processing utilizing surface consistent amplitude correction. Part 4; Surface consistent amplitude correction wo mochiita sotai shinpuku hozon shori. 4

    Energy Technology Data Exchange (ETDEWEB)

    Saeki, T. [Japan National Oil Corp., Tokyo (Japan). Technology Research Center

    1997-10-22

    Discussions were given on seismic exploration from the ground surface using the reflection method, for surface consistent amplitude correction from among effects imposed from the ground surface and a surface layer. Amplitude distribution on the reflection wave zone is complex. Therefore, items to be considered in making an analysis are multiple, such as estimation of spherical surface divergence effect and exponential attenuation effect, not only amplitude change through the surface layer. If all of these items are taken into consideration, burden of the work becomes excessive. As a method to solve this problem, utilization of amplitude in initial movement of a diffraction wave may be conceived. Distribution of the amplitude in initial movement of the diffraction wave shows a value relatively close to distribution of the vibration transmitting and receiving points. The reason for this is thought because characteristics of the vibration transmitting and receiving points related with waveline paths in the vicinity of the ground surface have no great difference both on the diffraction waves and on the reflection waves. The lecture described in this paper introduces an attempt of improving the efficiency of the surface consistent amplitude correction by utilizing the analysis of amplitude in initial movement of the diffraction wave. 4 refs., 2 figs.

  19. The Association Between P3 Amplitude at Age 11 and Criminal Offending at Age 23

    Science.gov (United States)

    Gao, Yu; Raine, Adrian; Venables, Peter H.; Mednick, Sarnoff A.

    2014-01-01

    Reduced P3 amplitude to targets is an information-processing deficit associated with adult antisocial behavior and may reflect dysfunction of the temporal-parietal junction. This study aims to examine whether this deficit precedes criminal offending. From a birth cohort of 1,795 children, 73 individuals who become criminal offenders at age 23 and 123 noncriminal individuals were assessed on P3 amplitude. The two groups did not differ on gender, ethnicity, and social adversity. P3 amplitude was measured over the temporal-parietal junction during a visual continuous performance task at age 11, together with antisocial behavior. Criminal convictions were assessed at age 23. Reduced P3 amplitude at age 11 was associated with increased antisocial behavior at age 11. Criminal offenders showed significantly reduced P3 amplitudes to target stimuli compared to controls. Findings remained significant after controlling for antisocial behavior and hyperactivity at age 11 and alcoholism at age 23. P3 deficits at age 11 are associated with adult crime at age 23, suggesting that reduced P3 may be an early neurobiological marker for cognitive and affective processes subserved by the temporal-parietal junction that place a child at risk for adult crime. PMID:22963083

  20. Tensor exchange amplitudes in K +- N charge exchange reactions

    International Nuclear Information System (INIS)

    Svec, M.

    1979-01-01

    Tensor (A 2 ) exchange amplitudes in K +- N charge exchange (CEX) are constructed from the K +- N CEX data supplemented by information on the vector (rho) exchange amplitudes from πN sca tering. We observed new features in the t-structure of A 2 exchange amplitudes which contradict the t-de pendence anticipated by most of the Regge models. The results also provide evidence for violation of weak exchange degeneracy

  1. Improved pion pion scattering amplitude from dispersion relation formalism

    International Nuclear Information System (INIS)

    Cavalcante, I.P.; Coutinho, Y.A.; Borges, J. Sa

    2005-01-01

    Pion-pion scattering amplitude is obtained from Chiral Perturbation Theory at one- and two-loop approximations. Dispersion relation formalism provides a more economic method, which was proved to reproduce the analytical structure of that amplitude at both approximation levels. This work extends the use of the formalism in order to compute further unitarity corrections to partial waves, including the D-wave amplitude. (author)

  2. Efficient analytic computation of higher-order QCD amplitudes

    International Nuclear Information System (INIS)

    Bern, Z.; Chalmers, G.; Dunbar, D.C.; Kosower, D.A.

    1995-01-01

    The authors review techniques simplifying the analytic calculation of one-loop QCD amplitudes with many external legs, for use in next-to-leading-order corrections to multi-jet processes. Particularly useful are the constraints imposed by perturbative unitarity, collinear singularities and a supersymmetry-inspired organization of helicity amplitudes. Certain sequences of one-loop helicity amplitudes with an arbitrary number of external gluons have been obtained using these constraints

  3. Ambitwistor strings and reggeon amplitudes in N=4 SYM

    Directory of Open Access Journals (Sweden)

    L.V. Bork

    2017-11-01

    Full Text Available We consider the description of reggeon amplitudes (Wilson lines form factors in N=4 SYM within the framework of four dimensional ambitwistor string theory. The latter is used to derive scattering equations representation for reggeon amplitudes with multiple reggeized gluons present. It is shown, that corresponding tree-level string correlation function correctly reproduces previously obtained Grassmannian integral representation of reggeon amplitudes in N=4 SYM.

  4. Phase and amplitude control system for Stanford Linear Accelerator

    International Nuclear Information System (INIS)

    Yoo, S.J.

    1983-01-01

    The computer controlled phase and amplitude detection system measures the instantaneous phase and amplitude of a 1 micro-second 2856 MHz rf pulse at a 180 Hz rate. This will be used for phase feedback control, and also for phase and amplitude jitter measurement. The program, which was originally written by John Fox and Keith Jobe, has been modified to improve the function of the system. The software algorithms used in the measurement are described, as is the performance of the prototype phase and amplitude detector system

  5. Analytic all-plus-helicity gluon amplitudes in QCD

    Science.gov (United States)

    Dunbar, David C.; Godwin, John H.; Jehu, Guy R.; Perkins, Warren B.

    2017-12-01

    We detail the calculation of two-loop all-plus-helicity amplitudes for pure Yang-Mills theory. The four-dimensional unitarity methods and augmented recursion techniques we have developed, together with a knowledge of the singular structure of the amplitudes, allow us to compute these in compact analytic forms. Specifically we present the computation and analytic results for the six- and seven-gluon leading color two-loop amplitudes, these being the first QCD two-loop amplitudes beyond five points.

  6. Proof of the fundamental BCJ relations for QCD amplitudes

    International Nuclear Information System (INIS)

    Cruz, Leonardo de la; Kniss, Alexander; Weinzierl, Stefan

    2015-01-01

    The fundamental BCJ-relation is a linear relation between primitive tree amplitudes with different cyclic orderings. The cyclic orderings differ by the insertion place of one gluon. The coefficients of the fundamental BCJ-relation are linear in the Lorentz invariants 2p i p j . The BCJ-relations are well established for pure gluonic amplitudes as well as for amplitudes in N=4 super-Yang-Mills theory. Recently, it has been conjectured that the BCJ-relations hold also for QCD amplitudes. In this paper we give a proof of this conjecture. The proof is valid for massless and massive quarks.

  7. Amplitude dependent damping in single crystalline high purity molybdenum

    International Nuclear Information System (INIS)

    Zelada-Lambri, G.I; Lambri, O.A; Garcia, J.A; Lomer, J.N

    2004-01-01

    Amplitude dependent damping measurements were performed on high purity single crystalline molybdenum at several different constant temperatures between room temperature and 1273K. The employed samples were single crystals with the orientation, having a residual resistivity ratio of about 8000. Previously to the amplitude dependent damping tests, the samples were subjected to different thermomechanical histories. Amplitude dependent damping effects appear only during the first heating run in temperature where the samples have the thermomechanical state of the deformation process at room temperature. In the subsequent run-ups in temperature, i.e, after subsequent annealings, amplitude dependent damping effects were not detected (au)

  8. Source-Space Cross-Frequency Amplitude-Amplitude Coupling in Tinnitus

    Directory of Open Access Journals (Sweden)

    Oliver Zobay

    2015-01-01

    Full Text Available The thalamocortical dysrhythmia (TCD model has been influential in the development of theoretical explanations for the neurological mechanisms of tinnitus. It asserts that thalamocortical oscillations lock a region in the auditory cortex into an ectopic slow-wave theta rhythm (4–8 Hz. The cortical area surrounding this region is hypothesized to generate abnormal gamma (>30 Hz oscillations (“edge effect” giving rise to the tinnitus percept. Consequently, the model predicts enhanced cross-frequency coherence in a broad range between theta and gamma. In this magnetoencephalography study involving tinnitus and control cohorts, we investigated this prediction. Using beamforming, cross-frequency amplitude-amplitude coupling (AAC was computed within the auditory cortices for frequencies (f1,f2 between 2 and 80 Hz. We find the AAC signal to decompose into two distinct components at low (f1,f230 Hz frequencies, respectively. Studying the correlation of AAC with several key covariates (age, hearing level (HL, tinnitus handicap and duration, and HL at tinnitus frequency, we observe a statistically significant association between age and low-frequency AAC. Contrary to the TCD predictions, however, we do not find any indication of statistical differences in AAC between tinnitus and controls and thus no evidence for the predicted enhancement of cross-frequency coupling in tinnitus.

  9. Generalization of experimental data on amplitude and frequency of oscillations induced by steam injection into a subcooled pool

    Energy Technology Data Exchange (ETDEWEB)

    Villanueva, Walter; Li, Hua [Division of Nuclear Power Safety, Royal Institute of Technology (KTH), Roslagstullsbacken 21, SE-10691 Stockholm (Sweden); Puustinen, Markku [Nuclear Engineering, LUT School of Energy Systems, Lappeenranta University of Technology (LUT), FIN-53851 Lappeenranta (Finland); Kudinov, Pavel, E-mail: pavel@safety.sci.kth.se [Division of Nuclear Power Safety, Royal Institute of Technology (KTH), Roslagstullsbacken 21, SE-10691 Stockholm (Sweden)

    2015-12-15

    Highlights: • Available data on steam injection into subcooled pool is generalized. • Scaling approach is proposed on amplitude and frequency of chugging oscillations. • The scaled amplitude has a maximum at Froude number Fr ≈ 2.8. • The scaled frequency has a minimum at Fr ≈ 6. • Both amplitude and frequency has a strong dependence on pool bulk temperature. - Abstract: Steam venting and condensation into a subcooled pool of water through a blowdown pipe can undergo a phenomenon called chugging, which is an oscillation of the steam–water interface inside the blowdown pipe. The momentum that is generated by the oscillations is directly proportional to the oscillations’ amplitude and frequency, according to the synthetic jet theory. Higher momentum can enhance pool mixing and positively affect the pool's pressure suppression capacity by reducing thermal stratification. In this paper, we present a generalization of available experimental data on the amplitude and frequency of oscillations during chugging. We use experimental data obtained in different facilities at different scales to suggest a scaling approach for non-dimensional amplitude and frequency of the oscillations. We demonstrate that the Froude number Fr (which relates the inertial forces to gravitational forces) can be used as a scaling criterion in this case. The amplitude has maximum at Fr ≈ 2.8. There is also a strong dependence of the amplitude on temperature; the lower the bulk temperature is the higher the scaled amplitude. A known analytical theory can only capture the decreasing trend in amplitude for Fr > 2.8 and fails to capture the increasing trend and the temperature dependence. Similarly, there is a minimum of the non-dimensional frequency at Fr ≈ 6. A strong dependence on temperature is also observed for Fr > 6; the lower the bulk temperature is the higher the scaled frequency. The known analytical theory is able to capture qualitatively the general trend in

  10. Gauge theory amplitudes in twistor space and holomorphic anomaly

    Energy Technology Data Exchange (ETDEWEB)

    Cachazo, Freddy [School of Natural Sciences, Institute for Advanced Study, Princeton NJ 08540 (United States)]. E-mail: cachazo@ias.edu; Witten, Edward [School of Natural Sciences, Institute for Advanced Study, Princeton NJ 08540 (United States); Svrcek, Peter [Department of Physics, Joseph Henry Laboratories, Princeton NJ 08540 (United States)

    2004-10-01

    We show that, in analyzing differential equations obeyed by one-loop gauge theory amplitudes, one must take into account a certain holomorphic anomaly. When this is done, the results are consistent with the simplest twistor-space picture of the available one-loop amplitudes. (author)

  11. Automated force controller for amplitude modulation atomic force microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Miyagi, Atsushi, E-mail: atsushi.miyagi@inserm.fr, E-mail: simon.scheuring@inserm.fr; Scheuring, Simon, E-mail: atsushi.miyagi@inserm.fr, E-mail: simon.scheuring@inserm.fr [U1006 INSERM, Université Aix-Marseille, Parc Scientifique et Technologique de Luminy, 163 Avenue de Luminy, 13009 Marseille (France)

    2016-05-15

    Atomic Force Microscopy (AFM) is widely used in physics, chemistry, and biology to analyze the topography of a sample at nanometer resolution. Controlling precisely the force applied by the AFM tip to the sample is a prerequisite for faithful and reproducible imaging. In amplitude modulation (oscillating) mode AFM, the applied force depends on the free and the setpoint amplitudes of the cantilever oscillation. Therefore, for keeping the applied force constant, not only the setpoint amplitude but also the free amplitude must be kept constant. While the AFM user defines the setpoint amplitude, the free amplitude is typically subject to uncontrollable drift, and hence, unfortunately, the real applied force is permanently drifting during an experiment. This is particularly harmful in biological sciences where increased force destroys the soft biological matter. Here, we have developed a strategy and an electronic circuit that analyzes permanently the free amplitude of oscillation and readjusts the excitation to maintain the free amplitude constant. As a consequence, the real applied force is permanently and automatically controlled with picoNewton precision. With this circuit associated to a high-speed AFM, we illustrate the power of the development through imaging over long-duration and at various forces. The development is applicable for all AFMs and will widen the applicability of AFM to a larger range of samples and to a larger range of (non-specialist) users. Furthermore, from controlled force imaging experiments, the interaction strength between biomolecules can be analyzed.

  12. Online measurement method for pulse amplitude in pulsed extraction columns

    International Nuclear Information System (INIS)

    Wang Xinghai; Li Shichang; Chen Jing

    2009-01-01

    Online measurement of pulse amplitude by air purge was studied. The pulse amplitude in a pulsed extraction column was calculated online by measurement of characteristic parameters of the signal's curve. The method can be used for calculation of different pulsed extraction columns. (authors)

  13. Time-varying interaction leads to amplitude death in coupled ...

    Indian Academy of Sciences (India)

    2013-09-05

    Sep 5, 2013 ... phenomenon called amplitude death even in diffusively coupled identical oscillators. ... [16] or by using conjugate coupling [11], amplitude death can occur without mismatch in oscillators. Several ..... [2] K Kaneko, Theory and applications of coupled map lattices (John Wiley and Sons, New York,. 1993).

  14. Coupled Higgs field equation and Hamiltonian amplitude equation ...

    Indian Academy of Sciences (India)

    Abstract. In this paper, coupled Higgs field equation and Hamiltonian amplitude equation are studied using the Lie classical method. Symmetry reductions and exact solutions are reported for Higgs equation and Hamiltonian amplitude equation. We also establish the travelling wave solutions involving parameters of the ...

  15. Investigating the amplitude of interactive footstep sounds and soundscape reproduction

    DEFF Research Database (Denmark)

    Turchet, Luca; Serafin, Stefania

    2013-01-01

    In this paper, we study the perception of amplitude of soundscapes and interactively generated footstep sounds provided both through headphones and a surround sound system. In particular, we investigate whether there exists a value for the amplitude of soundscapes and footstep sounds which is con...

  16. Abnormal Selective Attention Normalizes P3 Amplitudes in PDD

    Science.gov (United States)

    Hoeksma, Marco R.; Kemner, Chantal; Kenemans, J. Leon; van Engeland, Herman

    2006-01-01

    This paper studied whether abnormal P3 amplitudes in PDD are a corollary of abnormalities in ERP components related to selective attention in visual and auditory tasks. Furthermore, this study sought to clarify possible age differences in such abnormalities. Children with PDD showed smaller P3 amplitudes than controls, but no abnormalities in…

  17. Miracles in Scattering Amplitudes: from QCD to Gravity

    Energy Technology Data Exchange (ETDEWEB)

    Volovich, Anastasia [Brown Univ., Providence, RI (United States)

    2016-10-09

    The goal of my research project "Miracles in Scattering Amplitudes: from QCD to Gravity" involves deepening our understanding of gauge and gravity theories by exploring hidden structures in scattering amplitudes and using these rich structures as much as possible to aid practical calculations.

  18. Multiphoton states and amplitude k-th power squeezing

    International Nuclear Information System (INIS)

    Buzek, V.; Jex, I.

    1991-01-01

    On the basis of the work of d'Ariano and coworkers a new type of multiphoton states is introduced. Amplitude k-th power squeezing of the multiphoton states are analysed. In particular, it is shown that even if the multiphoton states do not exhibit ordinary squeezing they can be amplitude k-th power squeezed

  19. Double logarithmic asymptotics of quark amplitudes with flavour exchange

    International Nuclear Information System (INIS)

    Kirschner, R.

    1982-01-01

    Results on the quark scattering and annihilation amplitudes in the Regge region are presented. The perturbative contribution to those amplitudes in the double logarithmic approximation are calculated. In the calculations a method based on dispersion relations and gauge invariance is used. (M.F.W.)

  20. Conformal higher spin scattering amplitudes from twistor space

    Energy Technology Data Exchange (ETDEWEB)

    Adamo, Tim [Blackett Laboratory, Imperial College, London, SW7 2AZ (United Kingdom); Hähnel, Philipp; McLoughlin, Tristan [School of Mathematics, Trinity College Dublin, College Green, Dublin 2 (Ireland)

    2017-04-04

    We use the formulation of conformal higher spin (CHS) theories in twistor space to study their tree-level scattering amplitudes, finding expressions for all three-point (MHV)-bar amplitudes and all MHV amplitudes involving positive helicity conformal gravity particles and two negative helicity higher spins. This provides the on-shell analogue for the covariant coupling of CHS fields to a conformal gravity background. We discuss the restriction of the theory to a ghost-free unitary subsector, analogous to restricting conformal gravity to general relativity with a cosmological constant. We study the flat-space limit and show that the restricted amplitudes vanish, supporting the conjecture that in the unitary sector the S-matrix of CHS theories is trivial. However, by appropriately rescaling the amplitudes we find non-vanishing results which we compare with chiral flat-space higher spin theories.

  1. Planar amplitudes in maximally supersymmetric Yang-Mills theory.

    Science.gov (United States)

    Anastasiou, C; Dixon, L; Bern, Z; Kosower, D A

    2003-12-19

    The collinear factorization properties of two-loop scattering amplitudes in dimensionally regulated N=4 super-Yang-Mills theory suggest that, in the planar ('t Hooft) limit, higher-loop contributions can be expressed entirely in terms of one-loop amplitudes. We demonstrate this relation explicitly for the two-loop four-point amplitude and, based on the collinear limits, conjecture an analogous relation for n-point amplitudes. The simplicity of the relation is consistent with intuition based on the anti-de Sitter/conformal field theory correspondence that the form of the large-N(c) L-loop amplitudes should be simple enough to allow a resummation to all orders.

  2. New formulas for amplitudes from higher-dimensional operators

    Science.gov (United States)

    He, Song; Zhang, Yong

    2017-02-01

    In this paper we study tree-level amplitudes from higher-dimensional operators, including F 3 operator of gauge theory, and R 2, R 3 operators of gravity, in the Cachazo-He-Yuan formulation. As a generalization of the reduced Pfaffian in Yang-Mills theory, we find a new, gauge-invariant object that leads to gluon amplitudes with a single insertion of F 3, and gravity amplitudes by Kawai-Lewellen-Tye relations. When reduced to four dimensions for given helicities, the new object vanishes for any solution of scattering equations on which the reduced Pfaffian is non-vanishing. This intriguing behavior in four dimensions explains the vanishing of graviton helicity amplitudes produced by the Gauss-Bonnet R 2 term, and provides a scattering-equation origin of the decomposition into self-dual and anti-self-dual parts for F 3 and R 3 amplitudes.

  3. High Frequency Amplitude Detector for GMI Magnetic Sensors

    Directory of Open Access Journals (Sweden)

    Aktham Asfour

    2014-12-01

    Full Text Available A new concept of a high-frequency amplitude detector and demodulator for Giant-Magneto-Impedance (GMI sensors is presented. This concept combines a half wave rectifier, with outstanding capabilities and high speed, and a feedback approach that ensures the amplitude detection with easily adjustable gain. The developed detector is capable of measuring high-frequency and very low amplitude signals without the use of diode-based active rectifiers or analog multipliers. The performances of this detector are addressed throughout the paper. The full circuitry of the design is given, together with a comprehensive theoretical study of the concept and experimental validation. The detector has been used for the amplitude measurement of both single frequency and pulsed signals and for the demodulation of amplitude-modulated signals. It has also been successfully integrated in a GMI sensor prototype. Magnetic field and electrical current measurements in open- and closed-loop of this sensor have also been conducted.

  4. Simplicity in the structure of QED and gravity amplitudes

    Energy Technology Data Exchange (ETDEWEB)

    Badger, Simon [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Bjerrum-Bohr, N.E.J. [Institute for Advanced Study, Princeton, NJ (United States). School of Natural Sciences; Vanhove, Pierre [Institut des Hautes Etudes Scientifiques IHES, Bures sur Yvette (France); CEA, IPhT, CNRS, URA, Gif-sur-Yvette, (France). Inst. de Physique Theorique

    2008-11-15

    We investigate generic properties of one-loop amplitudes in unordered gauge theories in four dimensions. For such theories the organisation of amplitudes in manifestly crossing symmetric expressions poses restrictions on their structure and results in remarkable cancellations. We show that one-loop multi-photon amplitudes in QED with at least eight external photons are given only by scalar box integral functions. This QED 'no-triangle' property is true for all helicity configurations and has similarities to the 'notriangle' property found in the case of maximal N=8 supergravity. Results are derived both via a world-line formalism as well as using on-shell unitarity methods. We show that the simple structure of the loop amplitude originates from the extremely good BCFW scaling behaviour of the QED tree-amplitude. (orig.)

  5. Conformal higher spin scattering amplitudes from twistor space

    Science.gov (United States)

    Adamo, Tim; Hähnel, Philipp; McLoughlin, Tristan

    2017-04-01

    We use the formulation of conformal higher spin (CHS) theories in twistor space to study their tree-level scattering amplitudes, finding expressions for all three-point \\overline{MHV} amplitudes and all MHV amplitudes involving positive helicity conformal gravity particles and two negative helicity higher spins. This provides the on-shell analogue for the covariant coupling of CHS fields to a conformal gravity background. We discuss the restriction of the theory to a ghost-free unitary subsector, analogous to restricting conformal gravity to general relativity with a cosmological constant. We study the flat-space limit and show that the restricted amplitudes vanish, supporting the conjecture that in the unitary sector the S-matrix of CHS theories is trivial. However, by appropriately rescaling the amplitudes we find non-vanishing results which we compare with chiral flat-space higher spin theories.

  6. Gauge and Gravity Amplitudes from Trees to Loops

    DEFF Research Database (Denmark)

    Huang, Rijun

    This thesis describes two subjects that I mainly work on during my PhD study. They are both about scattering amplitudes, covering gravity and gauge theories, tree and loop level, with or without supersymmetry. The rst subject is Kawai-Lewellen-Tye(KLT) relation in field theory, which mysteriously...... relates Yang-Mills amplitudes to gravity amplitudes. Based on many known works about KLT and super-KLT relations, we provide a complete map between super-gravity amplitudes and super-Yang-Mills amplitudes for any number of supersymmetry that allowed in 4-dimensional theory. We also provide an explanation...... a special type of two-loop and three-loop diagrams where equations of maximal unitarity cut de ne complex curve. Geometry genus of complex curve is a topological invariant, and characterizes the property of curve. We compute the genus of complex curve for some two-loop and three-loop diagrams from...

  7. Nuclear-Mechanical Coupling: Small Amplitude Mechanical Vibrations and High Amplitude Power Oscillations in Nuclear Reactors

    International Nuclear Information System (INIS)

    Suarez Antola, R.

    2008-11-01

    The cores of nuclear reactors, including its structural parts and cooling fluids, are complex mechanical systems able to vibrate in a set of normal modes and frequencies, if suitable perturbed. The cyclic variations in the strain state of the core materials may produce changes in density. Changes in density modify the reactivity. Changes in reactivity modify thermal power. Modifications in thermal power produce variations in temperature fields. Variations in temperature produce variations in strain due to thermal-elastic effects. If the variation of the temperature field is fast enough and if the Doppler Effect and other stabilizing prompt effects in the fuel are weak enough, a fast oscillatory instability could be produced, coupled with mechanical vibrations of small amplitude. A recently constructed, simple mathematical model of nuclear reactor kinetics, that improves the one due to A.S. Thompson, is reviewed. It was constructed in order to study, in a first approximation, the stability of the reactor: a nonlinear nuclear-thermal oscillator (that corresponds to reactor point kinetics with thermal-elastic feedback and with frozen delayed neutron effects) is coupled nonlinearly with a linear mechanical-thermal oscillator (that corresponds to the first normal mode of mechanical vibrations excited by thermo-elastic effects). This mathematical model is studied here from the standpoint of mechanical vibrations. It is shown how, under certain conditions, a suitable mechanical perturbation could elicit fast and growing oscillatory instabilities in the reactor power. Applying the asymptotic method due to Krylov, Bogoliubov and Mitropolsky, analytical formulae that may be used in the calculation of the time varying amplitude and phase of the mechanical oscillations are given, as functions of the mechanical, thermal and nuclear parameters of the reactor. The consequences for the mechanical integrity of the reactor are assessed. Some conditions, mainly, but not exclusively

  8. 'String amplitudes': What can we do about the divergent integrals?

    International Nuclear Information System (INIS)

    Amano, Kaoru

    1990-01-01

    The rules for perturbative construction of scattering amplitude constitute the most well-established part of the string theory. They lead to neat integral expressions that represent the amplitude as the sum over the geometry of the string world sheet. However, if one really tries to evaluate the expression, one has to go a long way from there, for the integral does not represent the amplitude in any direct way. The present report focuses on this problem. A study is made to show that the traditional integrals purporting to be string amplitudes are divergent and to identify a remedy. Obviously, any divergent amplitude is not acceptable in a case like the one-loop four-point amplitude. Although the origin of the divergences seems to relate to physical singularities, the integral fails to give imaginary part required for unitarity but only gives infinities which are not desired. Respecting the observation that the integral representation corresponds to the Euclidean Feynman integral, one may modify the integral by postulating an offshell integral for a certain Euclidean, then continuing the function analytically, and defining the physical amplitude by the limit value of the function. This would take one to the correct Minkowskian expression. Some examples are also shown. (N.K.)

  9. Fringe image analysis based on the amplitude modulation method.

    Science.gov (United States)

    Gai, Shaoyan; Da, Feipeng

    2010-05-10

    A novel phase-analysis method is proposed. To get the fringe order of a fringe image, the amplitude-modulation fringe pattern is carried out, which is combined with the phase-shift method. The primary phase value is obtained by a phase-shift algorithm, and the fringe-order information is encoded in the amplitude-modulation fringe pattern. Different from other methods, the amplitude-modulation fringe identifies the fringe order by the amplitude of the fringe pattern. In an amplitude-modulation fringe pattern, each fringe has its own amplitude; thus, the order information is integrated in one fringe pattern, and the absolute fringe phase can be calculated correctly and quickly with the amplitude-modulation fringe image. The detailed algorithm is given, and the error analysis of this method is also discussed. Experimental results are presented by a full-field shape measurement system where the data has been processed using the proposed algorithm. (c) 2010 Optical Society of America.

  10. Correlation between vibration amplitude and tool wear in turning: Numerical and experimental analysis

    Directory of Open Access Journals (Sweden)

    Balla Srinivasa Prasad

    2017-02-01

    Full Text Available In this paper, a correlation between vibration amplitude and tool wear when in dry turning of AISI 4140 steel using uncoated carbide insert DNMA 432 is analyzed via experiments and finite element simulations. 3D Finite element simulations results are utilized to predict the evolution of cutting forces, vibration displacement amplitudes and tool wear in vibration induced turning. In the present paper, the primary concern is to find the relative vibration and tool wear with the variation of process parameters. These changes lead to accelerated tool wear and even breakage. The cutting forces in the feed direction are also predicted and compared with the experimental trends. A laser Doppler vibrometer is used to detect vibration amplitudes and the usage of Kistler 9272 dynamometer for recording the cutting forces during the cutting process is well demonstrated. A sincere effort is put to investigate the influence of spindle speed, feed rate, depth of cut on vibration amplitude and tool flank wear at different levels of workpiece hardness. Empirical models have been developed using second order polynomial equations for correlating the interaction and higher order influences of various process parameters. Analysis of variance (ANOVA is carried out to identify the significant factors that are affecting the vibration amplitude and tool flank wear. Response surface methodology (RSM is implemented to investigate the progression of flank wear and displacement amplitude based on experimental data. While measuring the displacement amplitude, R-square values for experimental and numerical methods are 98.6 and 97.8. Based on the R-square values of ANOVA it is found that the numerical values show good agreement with the experimental values and are helpful in estimating displacement amplitude. In the case of predicting the tool wear, R-square values were found to be 97.69 and 96.08, respectively for numerical and experimental measures while determining the tool

  11. Amplitude Modulation in the δ Sct star KIC 7106205

    Directory of Open Access Journals (Sweden)

    Bowman Dominic. M.

    2015-01-01

    Full Text Available The δ Sct star KIC 7106205 showed amplitude modulation in a single p mode, whilst all other p and g modes remained stable in amplitude and phase over 1470 d of the Kepler dataset. The data were divided into 30 time bins of equal length and a series of consecutive Fourier transforms was calculated. A fixed frequency, calculated from a least-squares fit of all data, allowed amplitude and phase for every mode in each time bin to be tracked. The missing p mode energy was not transferred to any other visible modes.

  12. Renormalization Scale-Fixing for Complex Scattering Amplitudes

    Energy Technology Data Exchange (ETDEWEB)

    Brodsky, Stanley J.; /SLAC; Llanes-Estrada, Felipe J.; /Madrid U.

    2005-12-21

    We show how to fix the renormalization scale for hard-scattering exclusive processes such as deeply virtual meson electroproduction by applying the BLM prescription to the imaginary part of the scattering amplitude and employing a fixed-t dispersion relation to obtain the scale-fixed real part. In this way we resolve the ambiguity in BLM renormalization scale-setting for complex scattering amplitudes. We illustrate this by computing the H generalized parton distribution at leading twist in an analytic quark-diquark model for the parton-proton scattering amplitude which can incorporate Regge exchange contributions characteristic of the deep inelastic structure functions.

  13. Direct Calculation of the Scattering Amplitude Without Partial Wave Analysis

    Science.gov (United States)

    Shertzer, J.; Temkin, A.; Fisher, Richard R. (Technical Monitor)

    2001-01-01

    Two new developments in scattering theory are reported. We show, in a practical way, how one can calculate the full scattering amplitude without invoking a partial wave expansion. First, the integral expression for the scattering amplitude f(theta) is simplified by an analytic integration over the azimuthal angle. Second, the full scattering wavefunction which appears in the integral expression for f(theta) is obtained by solving the Schrodinger equation with the finite element method (FEM). As an example, we calculate electron scattering from the Hartree potential. With minimal computational effort, we obtain accurate and stable results for the scattering amplitude.

  14. Einstein-Yang-Mills from pure Yang-Mills amplitudes

    OpenAIRE

    Nandan, Dhritiman; Plefka, Jan; Schlotterer, Oliver; Wen, Congkao

    2016-01-01

    We present new relations for scattering amplitudes of color ordered gluons and gravitons in Einstein-Yang-Mills theory. Tree-level amplitudes of arbitrary multiplicities and polarizations involving up to three gravitons and up to two color traces are reduced to partial amplitudes of pure Yang-Mills theory. In fact, the double-trace identities apply to Einstein-Yang-Mills extended by a dilaton and a B-field. Our results generalize recent work of Stieberger and Taylor for the single graviton ca...

  15. Scattering Amplitudes: The Most Perfect Microscopic Structures in the Universe

    Energy Technology Data Exchange (ETDEWEB)

    Dixon, Lance J.; /CERN /SLAC

    2011-11-04

    This article gives an overview of many of the recent developments in understanding the structure of relativistic scattering amplitudes in gauge theories ranging from QCD to N = 4 super-Yang-Mills theory, as well as (super)gravity. I also provide a pedagogical introduction to some of the basic tools used to organize and illuminate the color and kinematic structure of amplitudes. This article is an invited review introducing a special issue of Journal of Physics A devoted to 'Scattering Amplitudes in Gauge Theories'.

  16. Do patients having a decrease in SNAP amplitude during the course of MMN present with a different condition?

    Science.gov (United States)

    Delmont, Emilien; Benaïm, Charles; Launay, Mael; Sacconi, Sabrina; Soriani, Marie-Hélène; Desnuelle, Claude

    2009-11-01

    A decrease in sensory nerve action potentials (SNAP) amplitude has been recently reported in some patients during the course of multifocal motor neuropathy with conduction blocks (MMNCB). It is not known if those patients have different clinical expression and disability when compared with typical MMNCB. Clinical, biological and electrophysiological assessments were performed in 15 patients fitting the diagnosis criteria of MMNCB, including normal SNAP amplitude at initial examination. Patients presenting with nerve entrapment or associated disease causative of sensory neuropathy were excluded. Median time of follow-up was 3 years (1-17 years). At the last examination, four patients had at least one SNAP amplitude below 50% of normal value. None had clinically objective sensory loss. Clinical and electrophysiological data obtained at the last examination were compared between patients with normal SNAP amplitude and patients with decreased SNAP amplitude. No difference between both population in term of age, sex, disease duration, anti-GM1 antibody titers, CSF data and number of conduction blocks was noted. In contrast, patients with decreased SNAP amplitude had worse overall neuropathy limitation scale (ONLS) scores (7 vs. 2; p = 0.02), a higher number of affected nerves (12.5 vs. 4; p = 0.018), a higher number of affected limb regions (6 vs. 2; p = 0.019) and lower median CMAP amplitude (2 mV vs. 6.5 mV; p = 0.04). They were all dependent on higher doses of IVIg (1.4 g/(kg 4 weeks vs. 0.6; p = 0.018). A reduction in SNAP amplitude during the course of MMNCB is associated with a more severe disease and a more prominent axonal loss. This result needs to be confirmed in a larger cohort.

  17. Vocal responses of austral forest frogs to amplitude and degradation patterns of advertisement calls.

    Science.gov (United States)

    Penna, Mario; Moreno-Gómez, Felipe N; Muñoz, Matías I; Cisternas, Javiera

    2017-07-01

    Degradation phenomena affecting animal acoustic signals may provide cues to assess the distance of emitters. Recognition of degraded signals has been extensively demonstrated in birds, and recently studies have also reported detection of degraded patterns in anurans that call at or above ground level. In the current study we explore the vocal responses of the syntopic burrowing male frogs Eupsophus emiliopugini and E. calcaratus from the South American temperate forest to synthetic conspecific calls differing in amplitude and emulating degraded and non-degraded signal patterns. The results show a strong dependence of vocal responses on signal amplitude, and a general lack of differential responses to signals with different pulse amplitude modulation depths in E. emiliopugini and no effect of relative amplitude of harmonics in E. calcaratus. Such limited discrimination of signal degradation patterns from non-degraded signals is likely related to the burrowing habits of these species. Shelters amplify outgoing and incoming conspecific vocalizations, but do not counteract signal degradation to an extent comparable to calling strategies used by other frogs. The limited detection abilities and resultant response permissiveness to degraded calls in these syntopic burrowing species would be advantageous for animals communicating in circumstances in which signal alteration prevails. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Available pressure amplitude of linear compressor based on phasor triangle model

    Science.gov (United States)

    Duan, C. X.; Jiang, X.; Zhi, X. Q.; You, X. K.; Qiu, L. M.

    2017-12-01

    The linear compressor for cryocoolers possess the advantages of long-life operation, high efficiency, low vibration and compact structure. It is significant to study the match mechanisms between the compressor and the cold finger, which determines the working efficiency of the cryocooler. However, the output characteristics of linear compressor are complicated since it is affected by many interacting parameters. The existing matching methods are simplified and mainly focus on the compressor efficiency and output acoustic power, while neglecting the important output parameter of pressure amplitude. In this study, a phasor triangle model basing on analyzing the forces of the piston is proposed. It can be used to predict not only the output acoustic power, the efficiency, but also the pressure amplitude of the linear compressor. Calculated results agree well with the measurement results of the experiment. By this phasor triangle model, the theoretical maximum output pressure amplitude of the linear compressor can be calculated simply based on a known charging pressure and operating frequency. Compared with the mechanical and electrical model of the linear compressor, the new model can provide an intuitionistic understanding on the match mechanism with faster computational process. The model can also explain the experimental phenomenon of the proportional relationship between the output pressure amplitude and the piston displacement in experiments. By further model analysis, such phenomenon is confirmed as an expression of the unmatched design of the compressor. The phasor triangle model may provide an alternative method for the compressor design and matching with the cold finger.

  19. External Ear Resonant Amplitude and Frequency of 3-7 Year Old Children

    Directory of Open Access Journals (Sweden)

    Amir Hossein Zare

    2004-06-01

    Full Text Available Objective: To measure external ear resonant amplitude and frequency in children (3-7 years old and to compare with adult measures. Method and materials: The external ear resonance peak amplitude and frequency of 63 children 3-7 years old were recorded. All of the children had normal tympanogram and there was no cerumen in external auditory canal. 20 adult of 21-24 years old (10 male , 10 female were selected in order to compare with children that had normal tympanogram. The tests included : 1-otoscopy 2- tympanometry 3-microphone probe tube test. Results: The average of resonance peak frequency for children and adult is 4200 Hz and 3200 Hz , respectively. The resonance frequency of children had significantly diffrence with average of resonance frequency in adults. The average of resonance peak amplitude for children and adult is 17.70 dB and 17.17 dB , respectively. Conclusion: Resonant frequency and amplitude affect the hearing aid prescription and fitting process and calculating insertion gain; so, this measures seem should be considered in children hearing aid fitting.

  20. A pulse amplitude discriminator with very low-power consuming

    International Nuclear Information System (INIS)

    Deng Changming; Liu Zhengshan; Zhang Zhiyong; Cheng Chang

    2000-01-01

    A low-power pulse amplitude discriminator is described. The discriminator circuit is mainly composed of an integrated voltage comparator, MAX921, and owns the characters of very low-power and low operating voltage

  1. Interaction amplitudes of hadrons as composite superconformal strings

    International Nuclear Information System (INIS)

    Kudryavtsev, V.A.

    1995-01-01

    Construction of hadron interaction amplitudes is discussed in terms of the recently proposed new string dynamics. Inclusion of the nucleon and the flavor characterizing hadron quantum numbers into dynamics of composite superconformal strings is discussed

  2. Amplitude chimeras and chimera death in dynamical networks

    International Nuclear Information System (INIS)

    Zakharova, Anna; Kapeller, Marie; Schöll, Eckehard

    2016-01-01

    We find chimera states with respect to amplitude dynamics in a network of Stuart- Landau oscillators. These partially coherent and partially incoherent spatio-temporal patterns appear due to the interplay of nonlocal network topology and symmetry-breaking coupling. As the coupling range is increased, the oscillations are quenched, amplitude chimeras disappear and the network enters a symmetry-breaking stationary state. This particular regime is a novel pattern which we call chimera death. It is characterized by the coexistence of spatially coherent and incoherent inhomogeneous steady states and therefore combines the features of chimera state and oscillation death. Additionally, we show two different transition scenarios from amplitude chimera to chimera death. Moreover, for amplitude chimeras we uncover the mechanism of transition towards in-phase synchronized regime and discuss the role of initial conditions. (paper)

  3. Bessel–Gauss resonator with internal amplitude filter

    CSIR Research Space (South Africa)

    Litvin, IA

    2008-05-01

    Full Text Available The authors investigate a conventional resonator configuration, using only spherical curvature optical elements, for the generation of Bessel–Gauss beams. This is achieved through the deployment of a suitable amplitude filter at a Fourier plane...

  4. OCT Amplitude and Speckle Statistics of Discrete Random Media

    NARCIS (Netherlands)

    Almasian, Mitra; van Leeuwen, Ton G.; Faber, Dirk J.

    2017-01-01

    Speckle, amplitude fluctuations in optical coherence tomography (OCT) images, contains information on sub-resolution structural properties of the imaged sample. Speckle statistics could therefore be utilized in the characterization of biological tissues. However, a rigorous theoretical framework

  5. Some tree-level string amplitudes in the NSR formalism

    International Nuclear Information System (INIS)

    Becker, Katrin; Becker, Melanie; Melnikov, Ilarion V.; Robbins, Daniel; Royston, Andrew B.

    2015-01-01

    We calculate tree level scattering amplitudes for open strings using the NSR formalism. We present a streamlined symmetry-based and pedagogical approach to the computations, which we first develop by checking two-, three-, and four-point functions involving bosons and fermions. We calculate the five-point amplitude for massless gluons and find agreement with an earlier result by Brandt, Machado and Medina. We then compute the five-point amplitudes involving two and four fermions respectively, the general form of which has not been previously obtained in the NSR formalism. The results nicely confirm expectations from the supersymmetric F 4 effective action. Finally we use the prescription of Kawai, Lewellen and Tye (KLT) to compute the amplitudes for the closed string sector.

  6. Amplitudes, recursion relations and unitarity in the Abelian Higgs model

    Science.gov (United States)

    Kleiss, Ronald; Luna, Oscar Boher

    2017-12-01

    The Abelian Higgs model forms an essential part of the electroweak standard model: it is the sector containing only Z0 and Higgs bosons. We present a diagram-based proof of the tree-level unitarity of this model inside the unitary gauge, where only physical degrees of freedom occur. We derive combinatorial recursion relations for off-shell amplitudes in the massless approximation, which allows us to prove the cancellation of the first two orders in energy of unitarity-violating high-energy behaviour for any tree-level amplitude in this model. We describe a deformation of the amplitudes by extending the physical phase space to at least 7 spacetime dimensions, which leads to on-shell recursion relations à la BCFW. These lead to a simple proof that all on-shell tree amplitudes obey partial-wave unitarity.

  7. The zerology of kaon-nucleon forward scattering amplitudes

    International Nuclear Information System (INIS)

    Dumbrajs, O.

    1981-01-01

    It has been realized for a long time that zeros of the forward kaon-nucleon scattering amplitudes are useful in correlating different low and high-energy scattering parameters and in providing a consistency test of available data. The simplest possibility of exploring zeros is to evaluate the ordinary dispersion relations in the complex energy plane. The more natural way of bringing zeros of amplitudes into play is to consider either one of the more sophisticated forms of dispersion relations: i) phase dispersion relations, ii) inverse-amplitude dispersion relations, iii) logarithmic dispersion relations, or to apply the maximum modulus theorem and a factorization theorem. The author concentrates on the use of logarithmic dispersion relations because this approach seems to be the most convenient one for future extensions to nonforward scattering data analyses based on the zeros of the amplitude. (Auth.)

  8. Laser beam complex amplitude measurement by phase diversity.

    Science.gov (United States)

    Védrenne, Nicolas; Mugnier, Laurent M; Michau, Vincent; Velluet, Marie-Thérèse; Bierent, Rudolph

    2014-02-24

    The control of the optical quality of a laser beam requires a complex amplitude measurement able to deal with strong modulus variations and potentially highly perturbed wavefronts. The method proposed here consists in an extension of phase diversity to complex amplitude measurements that is effective for highly perturbed beams. Named camelot for Complex Amplitude MEasurement by a Likelihood Optimization Tool, it relies on the acquisition and processing of few images of the beam section taken along the optical path. The complex amplitude of the beam is retrieved from the images by the minimization of a Maximum a Posteriori error metric between the images and a model of the beam propagation. The analytical formalism of the method and its experimental validation are presented. The modulus of the beam is compared to a measurement of the beam profile, the phase of the beam is compared to a conventional phase diversity estimate. The precision of the experimental measurements is investigated by numerical simulations.

  9. Euclidean to Minkowski Bethe-Salpeter amplitude and observables

    Energy Technology Data Exchange (ETDEWEB)

    Carbonell, J. [Universite Paris-Sud, IN2P3-CNRS, Institut de Physique Nucleaire, Orsay Cedex (France); Frederico, T. [Instituto Tecnologico de Aeronautica, DCTA, Sao Jose dos Campos (Brazil); Karmanov, V.A. [Lebedev Physical Institute, Moscow (Russian Federation)

    2017-01-15

    We propose a method to reconstruct the Bethe-Salpeter amplitude in Minkowski space given the Euclidean Bethe-Salpeter amplitude - or alternatively the light-front wave function - as input. The method is based on the numerical inversion of the Nakanishi integral representation and computing the corresponding weight function. This inversion procedure is, in general, rather unstable, and we propose several ways to considerably reduce the instabilities. In terms of the Nakanishi weight function, one can easily compute the BS amplitude, the LF wave function and the electromagnetic form factor. The latter ones are very stable in spite of residual instabilities in the weight function. This procedure allows both, to continue the Euclidean BS solution in the Minkowski space and to obtain a BS amplitude from a LF wave function. (orig.)

  10. Euclidean to Minkowski Bethe-Salpeter amplitude and observables

    International Nuclear Information System (INIS)

    Carbonell, J.; Frederico, T.; Karmanov, V.A.

    2017-01-01

    We propose a method to reconstruct the Bethe-Salpeter amplitude in Minkowski space given the Euclidean Bethe-Salpeter amplitude - or alternatively the light-front wave function - as input. The method is based on the numerical inversion of the Nakanishi integral representation and computing the corresponding weight function. This inversion procedure is, in general, rather unstable, and we propose several ways to considerably reduce the instabilities. In terms of the Nakanishi weight function, one can easily compute the BS amplitude, the LF wave function and the electromagnetic form factor. The latter ones are very stable in spite of residual instabilities in the weight function. This procedure allows both, to continue the Euclidean BS solution in the Minkowski space and to obtain a BS amplitude from a LF wave function. (orig.)

  11. Stora's fine notion of divergent amplitudes

    International Nuclear Information System (INIS)

    Várilly, Joseph C.; Gracia-Bondía, José M.

    2016-01-01

    Stora and coworkers refined the notion of divergent quantum amplitude, somewhat upsetting the standard power-counting recipe. This unexpectedly clears the way to new prototypes for free and interacting field theories of bosons of any mass and spin.

  12. The super-correlator/super-amplitude duality: Part II

    CERN Document Server

    Eden, Burkhard; Korchemsky, Gregory P; Sokatchev, Emery

    2013-01-01

    We continue the study of the duality between super-correlators and scattering super-amplitudes in planar N=4 SYM. We provide a number of further examples supporting the conjectured duality relation between these two seemingly different objects. We consider the five- and six-point one-loop NMHV and the six-point tree-level NNMHV amplitudes, obtaining them from the appropriate correlators of strength tensor multiplets in N=4 SYM. In particular, we find exact agreement between the rather non-trivial parity-odd sector of the integrand of the six-point one-loop NMHV amplitude, as obtained from the correlator or from BCFW recursion relations. Together these results lead to the conjecture that the integrands of any N^kMHV amplitude at any loop order in planar N=4 SYM can be described by the correlators of stress-tensor multiplets.

  13. Stora's fine notion of divergent amplitudes

    Energy Technology Data Exchange (ETDEWEB)

    Várilly, Joseph C., E-mail: joseph.varilly@ucr.ac.cr [Escuela de Matemática, Universidad de Costa Rica, San José 11501 (Costa Rica); Gracia-Bondía, José M. [Departamento de Física Teórica, Universidad de Zaragoza, Zaragoza 50009 (Spain); Departamento de Física, Universidad de Costa Rica, San Pedro 11501 (Costa Rica)

    2016-11-15

    Stora and coworkers refined the notion of divergent quantum amplitude, somewhat upsetting the standard power-counting recipe. This unexpectedly clears the way to new prototypes for free and interacting field theories of bosons of any mass and spin.

  14. Field theory amplitudes in a space with SU(2) fuzziness

    Science.gov (United States)

    Komaie-Moghaddam, H.; Fatollahi, A. H.; Khorrami, M.

    2008-02-01

    The structure of transition amplitudes in field theory in a three-dimensional space whose spatial coordinates are noncommutative and satisfy the SU(2) Lie algebra commutation relations is examined. In particular, the basic notions for constructing the observables of the theory as well as subtleties related to the proper treatment of δ distributions (corresponding to conservation laws) are introduced. Explicit examples are given for scalar field theory amplitudes in the lowest order of perturbation.

  15. Amplitude Modulated Sinusoidal Signal Decomposition for Audio Coding

    DEFF Research Database (Denmark)

    Christensen, M. G.; Jacobson, A.; Andersen, S. V.

    2006-01-01

    In this paper, we present a decomposition for sinusoidal coding of audio, based on an amplitude modulation of sinusoids via a linear combination of arbitrary basis vectors. The proposed method, which incorporates a perceptual distortion measure, is based on a relaxation of a nonlinear least......-squares minimization. Rate-distortion curves and listening tests show that, compared to a constant-amplitude sinusoidal coder, the proposed decomposition offers perceptually significant improvements in critical transient signals....

  16. Examining the time dependence of DAMA's modulation amplitude

    Science.gov (United States)

    Kelso, Chris; Savage, Christopher; Sandick, Pearl; Freese, Katherine; Gondolo, Paolo

    2018-03-01

    If dark matter is composed of weakly interacting particles, Earth's orbital motion may induce a small annual variation in the rate at which these particles interact in a terrestrial detector. The DAMA collaboration has identified at a 9.3σ confidence level such an annual modulation in their event rate over two detector iterations, DAMA/NaI and DAMA/LIBRA, each with ˜ 7 years of observations. This data is well fit by a constant modulation amplitude for the two iterations of the experiment. We statistically examine the time dependence of the modulation amplitudes, which "by eye" appear to be decreasing with time in certain energy ranges. We perform a chi-squared goodness of fit test of the average modulation amplitudes measured by the two detector iterations which rejects the hypothesis of a consistent modulation amplitude at greater than 80, 96, and 99.6% for the 2-4, 2-5 and 2-6 keVee energy ranges, respectively. We also find that among the 14 annual cycles there are three ≳ 3σ departures from the average in our estimated data in the 5-6 keVee energy range. In addition, we examined several phenomenological models for the time dependence of the modulation amplitude. Using a maximum likelihood test, we find that descriptions of the modulation amplitude as decreasing with time are preferred over a constant modulation amplitude at anywhere between 1σ and 3σ , depending on the phenomenological model for the time dependence and the signal energy range considered. A time dependent modulation amplitude is not expected for a dark matter signal, at least for dark matter halo morphologies consistent with the DAMA signal. New data from DAMA/LIBRA-phase2 will certainly aid in determining whether any apparent time dependence is a real effect or a statistical fluctuation.

  17. Superstring vertex operators and scattering amplitudes on arbitrary Riemann surfaces

    International Nuclear Information System (INIS)

    Aldazabel, G.; Nunez, C.; Iengo, R.; Bonini, M.

    1987-12-01

    The construction of scattering amplitudes involving arbitrary bosonic mass level states is considered in both the closed superstring and in the heterotic string theories, at any order of perturbation. From massless particle scattering on a general Riemann surface, the super-covariant form of the vertex operators is derived via factorization. The super-covariant rules, including the normal ordering prescriptions, to be used in computing amplitudes, are automatically given by this procedure. (author). 22 refs, 1 fig

  18. Schwinger's effective Lagrangian from reflection and transmission amplitudes

    International Nuclear Information System (INIS)

    Warke, C.S.

    1992-01-01

    The reflection and transmission amplitudes are defined from the asymptotic form of the solution of Dirac equation of a charged fermion in the presence of uniform time independent external electromagnetic field (E, H). Schwinger's effective Lagrangian is derived from the reflection and transmission amplitudes. It is found that both the real and imaginary parts of the effective Lagrangian agree with Schwinger's expressions derived from the elegant method of proper time formalism. (author). 14 refs

  19. Lectures on scattering amplitudes via AdS/CFT

    Energy Technology Data Exchange (ETDEWEB)

    Alday, L.F. [Institute for Theoretical Physics and Spinoza Institute, Utrecht University (Netherlands)

    2008-08-05

    We review recent progress on computing scattering amplitudes of planar N=4 super Yang-Mills at strong coupling by using the AdS/CFT duality. We consider in detail the scattering of four gluons and do explicit computations by using both, dimensional regularization and a cut-off in the radial direction. The later scheme is particularly appropriate for understanding the conformal properties of the amplitudes. (Abstract Copyright [2008], Wiley Periodicals, Inc.)

  20. Three Point Tree Level Amplitude in Superstring Theory

    CERN Document Server

    Hatefi, Ehsan

    2011-01-01

    In order to check the definite amplitude and the exact zero result of the amplitude of three massless points $(CAA)$ in both string theory and field theory side for $p=n$ case and to find all gauge field couplings to R-R closed string, we investigate the disk level S-matrix element of one Ramond-Ramond field and two gauge field vertex operators in the world volume of BPS branes.

  1. Multiple pole in the electron--hydrogen-atom scattering amplitude

    International Nuclear Information System (INIS)

    Amusia, M.Y.; Kuchiev, M.Y.

    1982-01-01

    It is demonstrated that the amplitude for electron--hydrogen-atom forward scattering has the third-order pole at the point E = -13.6 eV, E being the energy of the incident electron. The coefficients which characterize the pole are calculated exactly. The invalidity of the Born approximation is proved. The contribution of the pole singularity to the dispersion relation for the scattering amplitude is discussed

  2. Fatigue life assessment under multiaxial variable amplitude loading

    International Nuclear Information System (INIS)

    Morilhat, P.; Kenmeugne, B.; Vidal-Salle, E.; Robert, J.L.

    1996-06-01

    A variable amplitude multiaxial fatigue life prediction method is presented in this paper. It is based on a stress as input data are the stress tensor histories which may be calculated by FEM analysis or measured directly on the structure during the service loading. The different steps of he method are first presented then its experimental validation is realized for log and finite fatigue lives through biaxial variable amplitude loading tests using cruciform steel samples. (authors). 9 refs., 7 figs

  3. All about the money – External performance monitoring is affected by monetary, but not by socially conveyed feedback cues in more antisocial individuals

    Directory of Open Access Journals (Sweden)

    Daniela Melitta Pfabigan

    2011-09-01

    Full Text Available This study investigated the relationship between feedback processing and antisocial personality traits measured by the PSSI questionnaire (Kuhl & Kazén, 1997 in a healthy undergraduate sample. While event-related potentials (Feedback Related Negativity [FRN], P300 were recorded, participants encountered expected and unexpected feedback during a gambling task. As recent findings suggest learning problems and deficiencies during feedback processing in clinical populations of antisocial individuals, we performed two experiments with different healthy participants in which feedback about monetary gains or losses consisted either of social-emotional (facial emotion displays or non-social cues (numerical stimuli. Since the FRN and P300 are both sensitive to different aspects of feedback processing we hypothesized that they might help to differentiate between individuals scoring high and low on an antisocial trait measure.In line with previous evidence FRN amplitudes were enhanced after negative and after unexpected feedback stimuli. Crucially, participants scoring high on antisocial traits displayed larger FRN amplitudes than those scoring low only in response to expected and unexpected negative numerical feedback, but not in response to social-emotional feedback - irrespective of expectancy. P300 amplitudes were not modulated by antisocial traits at all, but by subjective reward probabilities. The present findings indicate that individuals scoring high on antisociality attribute higher motivational salience to monetary compared to emotional-social feedback which is reflected in FRN amplitude enhancement. Contrary to recent findings, however, no processing deficiencies concerning social-emotional feedback stimuli were apparent in those individuals. This indicates that stimulus salience is an important aspect in learning and feedback processes in individuals with antisocial traits which has potential implications for therapeutic interventions in

  4. Mapping Pn amplitude spreading and attenuation in Asia

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Xiaoning [Los Alamos National Laboratory; Phillips, William S [Los Alamos National Laboratory; Stead, Richard J [Los Alamos National Laboratory

    2010-12-06

    Pn travels most of its path in the mantle lid. Mapping the lateral variation of Pn amplitude attenuation sheds light on material properties and dynamics of the uppermost region of the mantle. Pn amplitude variation depends on the wavefront geometric spreading as well as material attenuation. We investigated Pn geometric spreading, which is much more complex than a traditionally assumed power-law spreading model, using both synthetic and observed amplitude data collected in Asia. We derived a new Pn spreading model based on the formulation that was proposed previously to account for the spherical shape of the Earth (Yang et. al., BSSA, 2007). New parameters derived for the spreading model provide much better correction for Pn amplitudes in terms of residual behavior. Because we used observed Pn amplitudes to construct the model, the model incorporates not only the effect of the Earth's spherical shape, but also the effect of potential upper-mantle velocity gradients in the region. Using the new spreading model, we corrected Pn amplitudes measured at 1, 2, 4 and 6 Hz and conducted attenuation tomography. The resulting Pn attenuation model correlates well with the regional geology. We see high attenuation in regions such as northern Tibetan Plateau and the western Pacific subduction zone, and low attenuation for stable blocks such as Sichuan and Tarim basins.

  5. Scattering amplitudes and Wilson loops in twistor space

    Science.gov (United States)

    Adamo, Tim; Bullimore, Mathew; Mason, Lionel; Skinner, David

    2011-11-01

    This paper reviews the recent progress in twistor approaches to Wilson loops, amplitudes and their duality for {N}=4 super-Yang-Mills. Wilson loops and amplitudes are derived from first principles using the twistor action for maximally supersymmetric Yang-Mills theory. We start by deriving the MHV rules for gauge theory amplitudes from the twistor action in an axial gauge in twistor space, and show that this gives rise to the original momentum space version given by Cachazo, Svrček and Witten. We then go on to obtain from these the construction of the momentum twistor space loop integrand using (planar) MHV rules and show how it arises as the expectation value of a holomorphic Wilson loop in twistor space. We explain the connection between the holomorphic Wilson loop and certain light-cone limits of correlation functions. We give a brief review of other ideas in connection with amplitudes in twistor space: twistor-strings, recursion in twistor space, the Grassmannian residue formula for leading singularities and amplitudes as polytopes. This paper is an invited review for a special issue of Journal of Physics A: Mathematical and Theoretical devoted to ‘Scattering amplitudes in gauge theories’.

  6. A proposed physical analog for a quantum probability amplitude

    Science.gov (United States)

    Boyd, Jeffrey

    What is the physical analog of a probability amplitude? All quantum mathematics, including quantum information, is built on amplitudes. Every other science uses probabilities; QM alone uses their square root. Why? This question has been asked for a century, but no one previously has proposed an answer. We will present cylindrical helices moving toward a particle source, which particles follow backwards. Consider Feynman's book QED. He speaks of amplitudes moving through space like the hand of a spinning clock. His hand is a complex vector. It traces a cylindrical helix in Cartesian space. The Theory of Elementary Waves changes direction so Feynman's clock faces move toward the particle source. Particles follow amplitudes (quantum waves) backwards. This contradicts wave particle duality. We will present empirical evidence that wave particle duality is wrong about the direction of particles versus waves. This involves a paradigm shift; which are always controversial. We believe that our model is the ONLY proposal ever made for the physical foundations of probability amplitudes. We will show that our ``probability amplitudes'' in physical nature form a Hilbert vector space with adjoints, an inner product and support both linear algebra and Dirac notation.

  7. String scattering amplitudes and deformed cubic string field theory

    Directory of Open Access Journals (Sweden)

    Sheng-Hong Lai

    2018-01-01

    Full Text Available We study string scattering amplitudes by using the deformed cubic string field theory which is equivalent to the string field theory in the proper-time gauge. The four-string scattering amplitudes with three tachyons and an arbitrary string state are calculated. The string field theory yields the string scattering amplitudes evaluated on the world sheet of string scattering whereas the conventional method, based on the first quantized theory brings us the string scattering amplitudes defined on the upper half plane. For the highest spin states, generated by the primary operators, both calculations are in perfect agreement. In this case, the string scattering amplitudes are invariant under the conformal transformation, which maps the string world sheet onto the upper half plane. If the external string states are general massive states, generated by non-primary field operators, we need to take into account carefully the conformal transformation between the world sheet and the upper half plane. We show by an explicit calculation that the string scattering amplitudes calculated by using the deformed cubic string field theory transform into those of the first quantized theory on the upper half plane by the conformal transformation, generated by the Schwarz–Christoffel mapping.

  8. Mapping Pn Amplitude Spreading and Attenuation in Asia (Invited)

    Science.gov (United States)

    Yang, X.; Phillips, W. S.; Stead, R. J.

    2010-12-01

    Pn travels most of its path in the mantle lid. Mapping the lateral variation of Pn amplitude attenuation sheds light on material properties and dynamics of the uppermost region of the mantle. Pn amplitude variation depends on the wavefront geometric spreading as well as material attenuation. We investigated Pn geometric spreading, which is much more complex than a traditionally assumed power-law spreading model, using both synthetic and observed amplitude data collected in Asia. We derived a new Pn spreading model based on the formulation that was proposed previously to account for the spherical shape of the Earth (Yang et. al., BSSA, 2007). New parameters derived for the spreading model provide much better correction for Pn amplitudes in terms of residual behavior. Because we used observed Pn amplitudes to construct the model, the model incorporates not only the effect of the Earth's spherical shape, but also the effect of potential upper-mantle velocity gradients in the region. Using the new spreading model, we corrected Pn amplitudes measured at 1, 2, 4 and 6 Hz and conducted attenuation tomography. The resulting Pn attenuation model correlates well with the regional geology. We see high attenuation in regions such as northern Tibetan Plateau and the western Pacific subduction zone, and low attenuation for stable blocks such as Sichuan and Tarim basins.

  9. Scattering amplitudes and Wilson loops in twistor space

    Energy Technology Data Exchange (ETDEWEB)

    Adamo, Tim; Mason, Lionel [Mathematical Institute, 24-29 St. Giles' , Oxford OX1 3LB (United Kingdom); Bullimore, Mathew [Rudolf Peierls Centre for Theoretical Physics, 1 Keble Road, Oxford OX1 3NP (United Kingdom); Skinner, David, E-mail: adamo@maths.ox.ac.uk [Perimeter Institute for Theoretical Physics, 31 Caroline Street North, Waterloo, Ontario N2 L 2Y5 (Canada)

    2011-11-11

    This paper reviews the recent progress in twistor approaches to Wilson loops, amplitudes and their duality for N=4 super-Yang-Mills. Wilson loops and amplitudes are derived from first principles using the twistor action for maximally supersymmetric Yang-Mills theory. We start by deriving the MHV rules for gauge theory amplitudes from the twistor action in an axial gauge in twistor space, and show that this gives rise to the original momentum space version given by Cachazo, Svrcek and Witten. We then go on to obtain from these the construction of the momentum twistor space loop integrand using (planar) MHV rules and show how it arises as the expectation value of a holomorphic Wilson loop in twistor space. We explain the connection between the holomorphic Wilson loop and certain light-cone limits of correlation functions. We give a brief review of other ideas in connection with amplitudes in twistor space: twistor-strings, recursion in twistor space, the Grassmannian residue formula for leading singularities and amplitudes as polytopes. This paper is an invited review for a special issue of Journal of Physics A: Mathematical and Theoretical devoted to 'Scattering amplitudes in gauge theories'. (review)

  10. The open superstring 6-point amplitude with manifest symmetries

    International Nuclear Information System (INIS)

    Barreiro, Luiz Antonio; Medina, Ricardo; Stieberger, Stephan

    2011-01-01

    Full text: The general tree level amplitude for massless bosons states of open superstrings has been known for a long time ago. It is clear how to obtain this general formula using vertex operators in the Ramond-Neveu-Schwarz formalism. From the beginning of the eighties the explicit expression for this formula has been known in the case of 3 and 4-point amplitudes. In that decade an attempt (with partial success) was done, by Kitazawa, to obtain the corresponding 5-point amplitude. Only in 2002 a complete and correct expression for this amplitude was obtained. Its low energy expansion was compared to the corresponding one from the low energy effective Lagrangian of the open superstring, finding a perfect match. A few years later, in 2005, it was realized that the 5-point formula could be written in a very much compact form, as a sum of two terms: each of them consisting of a momentum factor and a kinematic expression. This constituted a generalization of the 4-point amplitude case, which had been known to be cast in only one momentum factor multiplied by one kinematic expression. For this simplification to happen, known symmetries of the (tree level) scattering amplitudes were implemented in a manifest form. These symmetries are (on-shell) gauge symmetry, cyclic symmetry and twisting symmetry (or world sheet parity). In the recent years it has been realized that the N-point amplitude can be written as a sum of (N - 3)! terms (where N > 3). This result not only agrees with the 3, 4 and 5-point results, but also with the 6-point result which had been obtained by 2005, written as a sum of six terms. The expression that up to now has been obtained for the 6-point amplitude is quite complicated and, besides knowing that it consists of six terms, is not very illuminating. In this work we report on the recent result of writing the 6-point amplitude with gauge, cyclic and twisting symmetries manifest. Not only because of the manifest symmetries this result is important

  11. Amplitude normalization reduces cervical vestibular evoked myogenic potential (cVEMP) amplitude asymmetries in normal subjects: proof of concept.

    Science.gov (United States)

    McCaslin, Devin L; Fowler, Andrea; Jacobson, Gary P

    2014-03-01

    The cervical vestibular evoked myogenic potential (cVEMP) is an acoustically synchronized, signal averaged, brief inhibitory response of a contracted muscle usually resulting from an acoustic stimulus. The cVEMP is recorded from the tonically contracted sternocleidomastoid muscle (SCM). The presence and amplitude of the cVEMP is related to both the integrity of the sacculo-collic pathway and magnitude of electromyographic (EMG) activity at the time of recording. Measurement variables include the absolute latency of the primary positive going component (referred to as P13) and interaural (i.e., left versus right) latency differences. Also measured is the peak-to-peak interaural amplitude asymmetry (IAA; percent difference in amplitude, left versus right). It is known that the amplitude of the cVEMP is positively correlated with the magnitude of tonic EMG from which the evoked potential is extracted. Thus, if EMG amplitude is uncontrolled, one cannot determine whether cVEMP asymmetries are occurring due to unilateral end organ disease or asymmetric tonic EMG activity. Two methods have been suggested to control for tonic EMG activity. These include (1) patient self-monitoring of EMG activity with biofeedback and (2) mathematical correction (i.e., amplitude normalization) of the left and right cVEMP waveforms. Currently, it is unknown how effective amplitude normalization techniques are at reducing cVEMP amplitude asymmetry in the presence of varying levels of EMG. The purpose of this investigation was to determine whether the use of amplitude correction techniques would reduce significantly the P13-N23 IAA data in otologically and neurologically intact adults when the level of EMG was varied between right and left sides. A prospective, repeated measures design was used for three different investigations in which cVEMPs were recorded and then processed using amplitude correction. Subjects were 20 otologically and neurologically health young adults between 21 and 29 yr

  12. Ultrasonic velocity and amplitude characterization of magnetorheological fluids under magnetic fields

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez-Lopez, J., E-mail: jaimerl@caend.upm-csic.es [Centro de Acustica Aplicada y Ensayos No Destructivos, UPM-CSIC, 28006 Madrid (Spain); Elvira Segura, L.; Montero de Espinosa Freijo, F. [Centro de Acustica Aplicada y Ensayos No Destructivos, UPM-CSIC, 28006 Madrid (Spain)

    2012-01-15

    Variations in velocity of sound and amplitude of the signal of a commercial magnetorheological fluid under different magnetic fields are studied experimentally. Different factors such as orientation, uniformity, geometry and intensity of the magnetic field are investigated. An increase in the change of MR fluid acoustical properties is obtained when the magnetic field intensity is risen. In addition, these properties show an opposite behavior when a magnetic field is applied parallel or perpendicular to the ultrasound propagation. Experiments using an electromagnet and permanent magnets as the source of magnetic field are also compared. Properties such as anisotropy in sound velocity and amplitude make these materials interesting regarding applications. - Highlights: > First sound attenuation measurements as function of the magnetic field in MR fluids. > Sound velocity and attenuation anisotropy due to the microstructure is detected. > Geometry, intensity and uniformity of the magnetic field affect sound propagation.

  13. Retrieving impulse response function amplitudes from the ambient seismic field

    Science.gov (United States)

    Viens, Loïc; Denolle, Marine; Miyake, Hiroe; Sakai, Shin'ichi; Nakagawa, Shigeki

    2017-07-01

    Seismic interferometry is now widely used to retrieve the impulse response function of the Earth between two distant seismometers. The phase information has been the focus of most passive imaging studies, as conventional seismic tomography uses traveltime measurements. The amplitude information, however, is harder to interpret because it strongly depends on the distribution of ambient seismic field sources and on the multitude of processing methods. Our study focuses on the latter by comparing the amplitudes of the impulse response functions calculated between seismic stations in the Kanto sedimentary basin, Japan, using several processing techniques. This region provides a unique natural laboratory to test the reliability of the amplitudes with complex wave propagation through the basin, and dense observations from the Metropolitan Seismic Observation network. We compute the impulse response functions using the cross correlation, coherency and deconvolution techniques of the raw ambient seismic field and the cross correlation of 1-bit normalized data. To validate the amplitudes of the impulse response functions, we use a shallow Mw 5.8 earthquake that occurred on the eastern edge of Kanto Basin and close to a station that is used as the virtual source. Both S and surface waves are retrieved in the causal part of the impulse response functions computed with all the different techniques. However, the amplitudes obtained from the deconvolution method agree better with those of the earthquake. Despite the expected wave attenuation due to the soft sediments of the Kanto Basin, seismic amplification caused by the basin geometry dominates the amplitudes of S and surface waves and is captured by the ambient seismic field. To test whether or not the anticausal part of the impulse response functions from deconvolution also contains reliable amplitude information, we use another virtual source located on the western edge of the basin. We show that the surface wave amplitudes

  14. An overlooked effect of systemic anticholinergics: alteration on accommodation amplitude

    Directory of Open Access Journals (Sweden)

    Mehmet Ali Sekeroglu

    2016-05-01

    Full Text Available AIM: To investigate the effect of oral solifenacin succinate, tolterodine-L-tartarate and oxybutinin hydrochloride (HCl on accommodation amplitude. METHODS: Female overactive bladder syndrome (OAB patients who were planned to use oral anticholinergics, patients that uses solifenacin succinate 5 mg (Group I, n=25, tolterodine-L-tartarate 4 mg (Group II, n=25, and oxybutinin HCl 5 mg b.i.d (Group III, n=25 and age matched healthy female subjects (Group IV, n=25 were recruited and complete ophthalmological examination and accommodation amplitude assessment were done at baseline and 4wk after initiation of treatment. RESULTS: The mean age of 100 consecutive female subjects was 51.6±5.7 (40-60y and there were no statistically significant difference with regard to the mean age (P=0.107 and baseline accommodation amplitude (P=0.148 between study groups. All treatment groups showed a significant decrease in accommodation amplitude following a 4-week course of anticholinergic treatment (P=0.008 in Group I, P=0.002 in Group II, P=0.001 in Group III, but there was no statistically significant difference in Group IV (P=0.065. CONCLUSION: A 4-week course of oral anticholinergic treatment have statistically significant effect on accommodation amplitude. Clinicians should avoid both overestimating this result, as this would unnecessarily restrict therapeutic possibilities, and also underestimating it which may lead to drug intolerance.

  15. 2-vertex Lorentzian spin foam amplitudes for dipole transitions

    Science.gov (United States)

    Sarno, Giorgio; Speziale, Simone; Stagno, Gabriele V.

    2018-04-01

    We compute transition amplitudes between two spin networks with dipole graphs, using the Lorentzian EPRL model with up to two (non-simplicial) vertices. We find power-law decreasing amplitudes in the large spin limit, decreasing faster as the complexity of the foam increases. There are no oscillations nor asymptotic Regge actions at the order considered, nonetheless the amplitudes still induce non-trivial correlations. Spin correlations between the two dipoles appear only when one internal face is present in the foam. We compute them within a mini-superspace description, finding positive correlations, decreasing in value with the Immirzi parameter. The paper also provides an explicit guide to computing Lorentzian amplitudes using the factorisation property of SL(2,C) Clebsch-Gordan coefficients in terms of SU(2) ones. We discuss some of the difficulties of non-simplicial foams, and provide a specific criterion to partially limit the proliferation of diagrams. We systematically compare the results with the simplified EPRLs model, much faster to evaluate, to learn evidence on when it provides reliable approximations of the full amplitudes. Finally, we comment on implications of our results for the physics of non-simplicial spin foams and their resummation.

  16. New formulas for amplitudes from higher-dimensional operators

    Energy Technology Data Exchange (ETDEWEB)

    He, Song [CAS Key Laboratory of Theoretical Physics, Institute of Theoretical Physics,Chinese Academy of Sciences, Beijing 100190 (China); School of Physical Sciences, University of Chinese Academy of Sciences,No.19A Yuquan Road, Beijing 100049 (China); Zhang, Yong [Department of Physics, Beijing Normal University,Beijing 100875 (China); CAS Key Laboratory of Theoretical Physics, Institute of Theoretical Physics,Chinese Academy of Sciences, Beijing 100190 (China)

    2017-02-06

    In this paper we study tree-level amplitudes from higher-dimensional operators, including F{sup 3} operator of gauge theory, and R{sup 2}, R{sup 3} operators of gravity, in the Cachazo-He-Yuan formulation. As a generalization of the reduced Pfaffian in Yang-Mills theory, we find a new, gauge-invariant object that leads to gluon amplitudes with a single insertion of F{sup 3}, and gravity amplitudes by Kawai-Lewellen-Tye relations. When reduced to four dimensions for given helicities, the new object vanishes for any solution of scattering equations on which the reduced Pfaffian is non-vanishing. This intriguing behavior in four dimensions explains the vanishing of graviton helicity amplitudes produced by the Gauss-Bonnet R{sup 2} term, and provides a scattering-equation origin of the decomposition into self-dual and anti-self-dual parts for F{sup 3} and R{sup 3} amplitudes.

  17. All Tree-level Amplitudes in Massless QCD

    Energy Technology Data Exchange (ETDEWEB)

    Dixon, Lance J.; /CERN /SLAC; Henn, Johannes M.; Plefka, Jan; Schuster, Theodor; /Humboldt U., Berlin

    2010-10-25

    We derive compact analytical formulae for all tree-level color-ordered gauge theory amplitudes involving any number of external gluons and up to three massless quark-anti-quark pairs. A general formula is presented based on the combinatorics of paths along a rooted tree and associated determinants. Explicit expressions are displayed for the next-to-maximally helicity violating (NMHV) and next-to-next-to-maximally helicity violating (NNMHV) gauge theory amplitudes. Our results are obtained by projecting the previously-found expressions for the super-amplitudes of the maximally supersymmetric Yang-Mills theory (N = 4 SYM) onto the relevant components yielding all gluon-gluino tree amplitudes in N = 4 SYM. We show how these results carry over to the corresponding QCD amplitudes, including massless quarks of different flavors as well as a single electroweak vector boson. The public Mathematica package GGT is described, which encodes the results of this work and yields analytical formulae for all N = 4 SYM gluon-gluino trees. These in turn yield all QCD trees with up to four external arbitrary-flavored massless quark-anti-quark-pairs.

  18. Estimates of the number of large amplitude gusts

    Energy Technology Data Exchange (ETDEWEB)

    Ramsdell, J.V.

    1978-03-01

    Preliminary estimates are presented of the number of occurrences of large amplitude gusts for use in the design of wind energy conversion systems. Existing turbulence information has been combined with an assumed wind speed distribution to arrive at the estimates. The number of large amplitude gusts per year is treated as a function of the annual mean wind speed and terrain roughness. This treatment is based upon the assumptions that the atmosphere has neutral stability during high winds and that the gustiness is induced by flow over surface roughness elements. Large gusts during thunderstorms and other severe weather phenomena are not treated. The results of the study are presented in tabular form as a function of gust amplitude and hourly average wind speed.

  19. Mammalian cycles: internally defined periods and interaction-driven amplitudes

    Science.gov (United States)

    Krebs, CJ

    2015-01-01

    The cause of mammalian cycles—the rise and fall of populations over a predictable period of time—has remained controversial since these patterns were first observed over a century ago. In spite of extensive work on observable mammalian cycles, the field has remained divided upon what the true cause is, with a majority of opinions attributing it to either predation or to intra-species mechanisms. Here we unite the eigenperiod hypothesis, which describes an internal, maternal effect-based mechanism to explain the cycles’ periods with a recent generalization explaining the amplitude of snowshoe hare cycles in northwestern North America based on initial predator abundance. By explaining the period and the amplitude of the cycle with separate mechanisms, a unified and consistent view of the causation of cycles is reached. Based on our suggested theory, we forecast the next snowshoe hare cycle (predicted peak in 2016) to be of extraordinarily low amplitude. PMID:26339557

  20. Einstein-Yang-Mills from pure Yang-Mills amplitudes

    International Nuclear Information System (INIS)

    Nandan, Dhritiman; Plefka, Jan; Schlotterer, Oliver; Wen, Congkao

    2016-01-01

    We present new relations for scattering amplitudes of color ordered gluons and gravitons in Einstein-Yang-Mills theory. Tree-level amplitudes of arbitrary multiplicities and polarizations involving up to three gravitons and up to two color traces are reduced to partial amplitudes of pure Yang-Mills theory. In fact, the double-trace identities apply to Einstein-Yang-Mills extended by a dilaton and a B-field. Our results generalize recent work of Stieberger and Taylor for the single graviton case with a single color trace. As the derivation is made in the dimension-agnostic Cachazo-He-Yuan formalism, our results are valid for external bosons in any number of spacetime dimensions. Moreover, they generalize to the superamplitudes in theories with 16 supercharges.

  1. BFKL Pomeron, Reggeized gluons and Bern-Dixon-Smirnov amplitudes

    CERN Document Server

    Bartels, J; Sabio Vera, Agustin

    2009-01-01

    After a brief review of the BFKL approach to Regge processes in QCD and in supersymmetric (SUSY) gauge theories we propose a strategy for calculating the next-to-next-to-leading order corrections to the BFKL kernel. They can be obtained in terms of various cross-sections for Reggeized gluon interactions. The corresponding amplitudes can be calculated in the framework of the effective action for high energy scattering. In the case of N=4 SUSY it is also possible to use the Bern-Dixon-Smirnov (BDS) ansatz. For this purpose the analytic properties of the BDS amplitudes at high energies are investigated, in order to verify their self-consistency. It is found that, for the number of external particles being larger than five, these amplitudes, beyond one loop, are not in agreement with the BFKL approach which predicts the existence of Regge cuts in some physical channels.

  2. One-Loop BPS amplitudes as BPS-state sums

    CERN Document Server

    Angelantonj, Carlo; Pioline, Boris

    2012-01-01

    Recently, we introduced a new procedure for computing a class of one-loop BPS-saturated amplitudes in String Theory, which expresses them as a sum of one-loop contributions of all perturbative BPS states in a manifestly T-duality invariant fashion. In this paper, we extend this procedure to all BPS-saturated amplitudes of the form \\int_F \\Gamma_{d+k,d} {\\Phi}, with {\\Phi} being a weak (almost) holomorphic modular form of weight -k/2. We use the fact that any such {\\Phi} can be expressed as a linear combination of certain absolutely convergent Poincar\\'e series, against which the fundamental domain F can be unfolded. The resulting BPS-state sum neatly exhibits the singularities of the amplitude at points of gauge symmetry enhancement, in a chamber-independent fashion. We illustrate our method with concrete examples of interest in heterotic string compactifications.

  3. arXiv New relations for graviton-matter amplitudes

    CERN Document Server

    Plefka, Jan

    We present new relations for scattering amplitudes of color ordered gluons, massive quarks and scalars minimally coupled to gravity. Tree-level amplitudes of arbitrary matter and gluon multiplicities involving one graviton are reduced to partial amplitudes in QCD or scalar QCD. The obtained relations are a direct generalization of the recently found Einstein-Yang-Mills relations. The proof of the new relation employs a simple diagrammatic argument trading the graviton-matter couplings to an `upgrade' of a gluon coupling with a color-kinematic replacement rule enforced. The use of the Melia-Johansson-Ochirov color basis is a key element of the reduction. We comment on the generalization to multiple gravitons in the single color trace case.

  4. Einstein-Yang-Mills from pure Yang-Mills amplitudes

    Energy Technology Data Exchange (ETDEWEB)

    Nandan, Dhritiman; Plefka, Jan [Institut für Physik and IRIS Adlershof, Humboldt-Universität zu Berlin,Zum Großen Windkanal 6, D-12489 Berlin (Germany); Schlotterer, Oliver [Max-Planck-Institut für Gravitationsphysik, Albert-Einstein-Institut,Am Mühlenberg 1, D-14476 Potsdam (Germany); Wen, Congkao [I.N.F.N. Sezione di Roma Tor Vergata,Via della Ricerca Scientifica, 00133 Roma (Italy)

    2016-10-14

    We present new relations for scattering amplitudes of color ordered gluons and gravitons in Einstein-Yang-Mills theory. Tree-level amplitudes of arbitrary multiplicities and polarizations involving up to three gravitons and up to two color traces are reduced to partial amplitudes of pure Yang-Mills theory. In fact, the double-trace identities apply to Einstein-Yang-Mills extended by a dilaton and a B-field. Our results generalize recent work of Stieberger and Taylor for the single graviton case with a single color trace. As the derivation is made in the dimension-agnostic Cachazo-He-Yuan formalism, our results are valid for external bosons in any number of spacetime dimensions. Moreover, they generalize to the superamplitudes in theories with 16 supercharges.

  5. Simplifying one-loop amplitudes in superstring theory

    Energy Technology Data Exchange (ETDEWEB)

    Bianchi, Massimo; Consoli, Dario [Dipartimento di Fisica, Università di Roma “Tor Vergata”,INFN Sezione di Roma “Tor Vergata”,Via della Ricerca Scientifica, 00133 Roma (Italy)

    2016-01-08

    We show that 4-point vector boson one-loop amplitudes, computed in http://dx.doi.org/10.1088/1126-6708/2006/12/010 in the RNS formalism, around vacuum configurations with open unoriented strings, preserving at least N=1 SUSY in D=4, satisfy the correct supersymmetry Ward identities, in that they vanish for non MHV configurations (++++) and (−+++). In the MHV case (−−++) we drastically simplify their expressions. We then study factorisation and the limiting IR and UV behaviours and find some unexpected results. In particular no massless poles are exposed at generic values of the modular parameter. Relying on the supersymmetric properties of our bosonic amplitudes, we extend them to manifestly supersymmetric super-amplitudes and compare our results with those obtained in the D=4 hybrid formalism, pointing out difficulties in reconciling the two approaches for contributions from N=1,2 sectors.

  6. Control of amplitude chimeras by time delay in oscillator networks

    Science.gov (United States)

    Gjurchinovski, Aleksandar; Schöll, Eckehard; Zakharova, Anna

    2017-04-01

    We investigate the influence of time-delayed coupling in a ring network of nonlocally coupled Stuart-Landau oscillators upon chimera states, i.e., space-time patterns with coexisting partially coherent and partially incoherent domains. We focus on amplitude chimeras, which exhibit incoherent behavior with respect to the amplitude rather than the phase and are transient patterns, and we show that their lifetime can be significantly enhanced by coupling delay. To characterize their transition to phase-lag synchronization (coherent traveling waves) and other coherent structures, we generalize the Kuramoto order parameter. Contrasting the results for instantaneous coupling with those for constant coupling delay, for time-varying delay, and for distributed-delay coupling, we demonstrate that the lifetime of amplitude chimera states and related partially incoherent states can be controlled, i.e., deliberately reduced or increased, depending upon the type of coupling delay.

  7. Expression of relativistic amplitudes in terms of wave functions

    International Nuclear Information System (INIS)

    Karmanov, V.A.

    1978-01-01

    The conditions under which relativistic amplitudes may be expressed in terms of the wave functions are analyzed within the framework of the invariant diagram technique which appears on formulation of field theory on the light front. The amplitudes depend on the 4-vector ω which defines the surface of the light front. A rule is formulated for the determination of those values of the 4-vector ω for which the diagram contribution, which cannot be expressed in terms of the wave functions, is minimum. The present investigation is equivalent to a study of the dependence of the amplitudes of the old fashioned perburbation theory in the infinite momentum depending on the direction of the infinite momentum

  8. Anomalous Amplitude Attenuation Method to Enhance Seismic Resolution

    Directory of Open Access Journals (Sweden)

    Muchlis .

    2015-05-01

    Full Text Available Anomalous Amplitude Attenuation (AAA is a method to process seismic data with multilevel processing (multi step flow. AAA is indicated for identifying anomalous seismic amplitude (amplitude noise such as: spike noise, noise and noised trace. AAA is a filter applied to the data in the frequency domain, range, both in CMP/CDP, offset or gather shot. Processing of the data depends on how the sensor (the geophone receives seismic waves, and then set the data back into the format demultiplex (SEG-Y and then processed according to the rules (flowchart seismic reflection processing.This method has been applied to improve the old seismic data of an exploration company in prospecting the unseen structure in prospecting the hydrocarbon trapped within sedimentary rock subsurface.

  9. Amplitude analysis of the B+/--->phiK*(892)+/- decay.

    Science.gov (United States)

    Aubert, B; Bona, M; Boutigny, D; Karyotakis, Y; Lees, J P; Poireau, V; Prudent, X; Tisserand, V; Zghiche, A; Garra Tico, J; Grauges, E; Lopez, L; Palano, A; Eigen, G; Stugu, B; Sun, L; Abrams, G S; Battaglia, M; Brown, D N; Button-Shafer, J; Cahn, R N; Groysman, Y; Jacobsen, R G; Kadyk, J A; Kerth, L T; Kolomensky, Yu G; Kukartsev, G; Lopes Pegna, D; Lynch, G; Mir, L M; Orimoto, T J; Ronan, M T; Tackmann, K; Wenzel, W A; del Amo Sanchez, P; Hawkes, C M; Watson, A T; Held, T; Koch, H; Lewandowski, B; Pelizaeus, M; Schroeder, T; Steinke, M; Walker, D; Asgeirsson, D J; Cuhadar-Donszelmann, T; Fulsom, B G; Hearty, C; Mattison, T S; McKenna, J A; Khan, A; Saleem, M; Teodorescu, L; Blinov, V E; Bukin, A D; Druzhinin, V P; Golubev, V B; Onuchin, A P; Serednyakov, S I; Skovpen, Yu I; Solodov, E P; Todyshev, K Yu; Bondioli, M; Curry, S; Eschrich, I; Kirkby, D; Lankford, A J; Lund, P; Mandelkern, M; Martin, E C; Stoker, D P; Abachi, S; Buchanan, C; Foulkes, S D; Gary, J W; Liu, F; Long, O; Shen, B C; Zhang, L; Paar, H P; Rahatlou, S; Sharma, V; Berryhill, J W; Campagnari, C; Cunha, A; Dahmes, B; Hong, T M; Kovalskyi, D; Richman, J D; Beck, T W; Eisner, A M; Flacco, C J; Heusch, C A; Kroseberg, J; Lockman, W S; Schalk, T; Schumm, B A; Seiden, A; Williams, D C; Wilson, M G; Winstrom, L O; Chen, E; Cheng, C H; Fang, F; Hitlin, D G; Narsky, I; Piatenko, T; Porter, F C; Andreassen, R; Mancinelli, G; Meadows, B T; Mishra, K; Sokoloff, M D; Blanc, F; Bloom, P C; Chen, S; Ford, W T; Hirschauer, J F; Kreisel, A; Nagel, M; Nauenberg, U; Olivas, A; Smith, J G; Ulmer, K A; Wagner, S R; Zhang, J; Gabareen, A M; Soffer, A; Toki, W H; Wilson, R J; Winklmeier, F; Zeng, Q; Altenburg, D D; Feltresi, E; Hauke, A; Jasper, H; Merkel, J; Petzold, A; Spaan, B; Wacker, K; Brandt, T; Klose, V; Kobel, M J; Lacker, H M; Mader, W F; Nogowski, R; Schubert, J; Schubert, K R; Schwierz, R; Sundermann, J E; Volk, A; Bernard, D; Bonneaud, G R; Latour, E; Lombardo, V; Thiebaux, Ch; Verderi, M; Clark, P J; Gradl, W; Muheim, F; Playfer, S; Robertson, A I; Xie, Y; Andreotti, M; Bettoni, D; Bozzi, C; Calabrese, R; Cecchi, A; Cibinetto, G; Franchini, P; Luppi, E; Negrini, M; Petrella, A; Piemontese, L; Prencipe, E; Santoro, V; Anulli, F; Baldini-Ferroli, R; Calcaterra, A; de Sangro, R; Finocchiaro, G; Pacetti, S; Patteri, P; Peruzzi, I M; Piccolo, M; Rama, M; Zallo, A; Buzzo, A; Contri, R; Lo Vetere, M; Macri, M M; Monge, M R; Passaggio, S; Patrignani, C; Robutti, E; Santroni, A; Tosi, S; Chaisanguanthum, K S; Morii, M; Wu, J; Dubitzky, R S; Marks, J; Schenk, S; Uwer, U; Bard, D J; Dauncey, P D; Flack, R L; Nash, J A; Nikolich, M B; Panduro Vazquez, W; Tibbetts, M; Behera, P K; Chai, X; Charles, M J; Mallik, U; Meyer, N T; Ziegler, V; Cochran, J; Crawley, H B; Dong, L; Eyges, V; Meyer, W T; Prell, S; Rosenberg, E I; Rubin, A E; Gao, Y Y; Gritsan, A V; Guo, Z J; Lae, C K; Denig, A G; Fritsch, M; Schott, G; Arnaud, N; Béquilleux, J; Davier, M; Grosdidier, G; Höcker, A; Lepeltier, V; Le Diberder, F; Lutz, A M; Pruvot, S; Rodier, S; Roudeau, P; Schune, M H; Serrano, J; Sordini, V; Stocchi, A; Wang, W F; Wormser, G; Lange, D J; Wright, D M; Bingham, I; Chavez, C A; Forster, I J; Fry, J R; Gabathuler, E; Gamet, R; Hutchcroft, D E; Payne, D J; Schofield, K C; Touramanis, C; Bevan, A J; George, K A; Di Lodovico, F; Menges, W; Sacco, R; Cowan, G; Flaecher, H U; Hopkins, D A; Paramesvaran, S; Salvatore, F; Wren, A C; Brown, D N; Davis, C L; Allison, J; Barlow, N R; Barlow, R J; Chia, Y M; Edgar, C L; Lafferty, G D; West, T J; Yi, J I; Anderson, J; Chen, C; Jawahery, A; Roberts, D A; Simi, G; Tuggle, J M; Blaylock, G; Dallapiccola, C; Hertzbach, S S; Li, X; Moore, T B; Salvati, E; Saremi, S; Cowan, R; Dujmic, D; Fisher, P H; Koeneke, K; Sciolla, G; Sekula, S J; Spitznagel, M; Taylor, F; Yamamoto, R K; Zhao, M; Zheng, Y; Mclachlin, S E; Patel, P M; Robertson, S H; Lazzaro, A; Palombo, F; Bauer, J M; Cremaldi, L; Eschenburg, V; Godang, R; Kroeger, R; Sanders, D A; Summers, D J; Zhao, H W; Brunet, S; Côté, D; Simard, M; Taras, P; Viaud, F B; Nicholson, H; De Nardo, G; Fabozzi, F; Lista, L; Monorchio, D; Sciacca, C; Baak, M A; Raven, G; Snoek, H L; Jessop, C P; LoSecco, J M; Benelli, G; Corwin, L A; Honscheid, K; Kagan, H; Kass, R; Morris, J P; Rahimi, A M; Regensburger, J J; Wong, Q K; Blount, N L; Brau, J; Frey, R; Igonkina, O; Kolb, J A; Lu, M; Rahmat, R; Sinev, N B; Strom, D; Strube, J; Torrence, E; Gagliardi, N; Gaz, A; Margoni, M; Morandin, M; Pompili, A; Posocco, M; Rotondo, M; Simonetto, F; Stroili, R; Voci, C; Ben-Haim, E; Briand, H; Calderini, G; Chauveau, J; David, P; Del Buono, L; de la Vaissière, Ch; Hamon, O; Leruste, Ph; Malclès, J; Ocariz, J; Perez, A; Gladney, L; Biasini, M; Covarelli, R; Manoni, E; Angelini, C; Batignani, G; Bettarini, S; Carpinelli, M; Cenci, R; Cervelli, A; Forti, F; Giorgi, M A; Lusiani, A; Marchiori, G

    2007-11-16

    We perform an amplitude analysis of B+/--->phi(1020)K*(892)+/- decay with a sample of about 384 x 10(6) BB[over ] pairs recorded with the BABAR detector. Overall, twelve parameters are measured, including the fractions of longitudinal fL and parity-odd transverse f perpendicular amplitudes, branching fraction, strong phases, and six parameters sensitive to CP violation. We use the dependence on the Kpi invariant mass of the interference between the JP=1(-) and 0+ Kpi components to resolve the discrete ambiguity in the determination of the strong and weak phases. Our measurements of fL=0.49+/-0.05+/-0.03, f perpendicular=0.21+/-0.05+/-0.02, and the strong phases point to the presence of a substantial helicity-plus amplitude from a presently unknown source.

  10. Amplitude saturation of MEMS resonators explained by autoparametric resonance

    International Nuclear Information System (INIS)

    Van der Avoort, C; Bontemps, J J M; Steeneken, P G; Le Phan, K; Van Beek, J T M; Van der Hout, R; Hulshof, J; Fey, R H B

    2010-01-01

    This paper describes a phenomenon that limits the power handling of MEMS resonators. It is observed that above a certain driving level, the resonance amplitude becomes independent of the driving level. In contrast to previous studies of power handling of MEMS resonators, it is found that this amplitude saturation cannot be explained by nonlinear terms in the spring constant or electrostatic force. Instead we show that the amplitude in our experiments is limited by nonlinear terms in the equation of motion which couple the in-plane length-extensional resonance mode to one or more out-of-plane (OOP) bending modes. We present experimental evidence for the autoparametric excitation of these OOP modes using a vibrometer. The measurements are compared to a model that can be used to predict a power-handling limit for MEMS resonators

  11. Electromagnetic energies of nuclei and the nuclear Compton amplitude

    International Nuclear Information System (INIS)

    Friar, J.L.

    1976-01-01

    The electromagnetic energy of a nucleus is derived in perturbation theory, which relates this quantity to the amplitude for the forward scattering of virtual photons on a nucleus (nuclear Compton amplitude). Through the use of the gauge invariance of this amplitude, the energy is separated into Coulomb and transverse components. Our formalism, although basically nonrelativistic, admits corrections of order (v/c) 2 to the nuclear charge operator. The energy is further separated into one-body terms, related to the n--p mass difference, and two-body terms which lead to the Breit interaction and the nuclear Lamb shift. These results are then related to electron scattering sum rules in the manner of Cottingham. Mesonic contributions to the electromagnetic energy are also discussed

  12. Amplitude Noise Reduction of Ion Lasers with Optical Feedback

    Science.gov (United States)

    Herring, Gregory C.

    2011-01-01

    A reduction in amplitude noise on the output of a multi-mode continuous-wave Ar-ion laser was previously demonstrated when a fraction of the output power was retroreflected back into the laser cavity. This result was reproduced in the present work and a Fabry-Perot etalon was used to monitor the longitudinal mode structure of the laser. A decrease in the number of operating longitudinal cavity modes was observed simultaneously with the introduction of the optical feedback and the onset of the amplitude noise reduction. The noise reduction is a result of a reduced number of lasing modes, resulting in less mode beating and amplitude fluctuations of the laser output power.

  13. String amplitudes: from field theories to number theory

    CERN Multimedia

    CERN. Geneva

    2017-01-01

    In a variety of recent developments, scattering amplitudes hint at new symmetries of and unexpected connections between physical theories which are otherwise invisible in their conventional description via Feynman diagrams or Lagrangians. Yet, many of these hidden structures are conveniently accessible to string theory where gauge interactions and gravity arise as the low-energy excitations of open and closed strings. In this talk, I will give an intuitive picture of gravity as a double copy of gauge interactions and extend the web of relations to scalar field theories including chiral Lagrangians for Goldstone bosons. The string corrections to gauge and gravity amplitudes beyond their point-particle limit exhibit elegant mathematical structures and offer a convenient laboratory to explore modern number-theoretic concepts in a simple context. As a common theme with Feynman integrals, string amplitudes introduce a variety of periods and special functions including multiple zeta values and polylogarithms, orga...

  14. Mammalian cycles: internally defined periods and interaction-driven amplitudes

    Directory of Open Access Journals (Sweden)

    LR Ginzburg

    2015-08-01

    Full Text Available The cause of mammalian cycles—the rise and fall of populations over a predictable period of time—has remained controversial since these patterns were first observed over a century ago. In spite of extensive work on observable mammalian cycles, the field has remained divided upon what the true cause is, with a majority of opinions attributing it to either predation or to intra-species mechanisms. Here we unite the eigenperiod hypothesis, which describes an internal, maternal effect-based mechanism to explain the cycles’ periods with a recent generalization explaining the amplitude of snowshoe hare cycles in northwestern North America based on initial predator abundance. By explaining the period and the amplitude of the cycle with separate mechanisms, a unified and consistent view of the causation of cycles is reached. Based on our suggested theory, we forecast the next snowshoe hare cycle (predicted peak in 2016 to be of extraordinarily low amplitude.

  15. PASTA - An RF Phase and Amplitude Scan and Tuning Application

    CERN Document Server

    Galambos, J; Deibele, C; Henderson, S

    2005-01-01

    To assist the beam commissioning in the Spallation Neutron Source (SNS) linac, a general purpose RF tuning application has been written to help set RF phase and amplitude. It follows the signature matching procedure described in Ref.* The method involves varying an upstream Rf cavity amplitude and phase settings and comparing the measured downstream beam phase responses to model predictions. The model input for cavity phase and amplitude calibration and for the beam energy are varied to best match observations. This scheme has advantages over other RF tuning techniques of not requiring intercepting devices (e.g. Faraday Cups), and not being restricted to a small linear response regime near the design values. The application developed here is general and can be applied to different RF structure types in the SNS linac. Example applications in the SNS Drift Tube Linac (DTL) and Coupled Cavity Linac (CCL) structures will be shown.

  16. Large-amplitude Longitudinal Oscillations in a Solar Filament

    Science.gov (United States)

    Zhang, Q. M.; Li, T.; Zheng, R. S.; Su, Y. N.; Ji, H. S.

    2017-06-01

    In this paper, we report our multiwavelength observations of the large-amplitude longitudinal oscillations of a filament observed on 2015 May 3. Located next to active region 12335, the sigmoidal filament was observed by the ground-based Hα telescopes from the Global Oscillation Network Group and by the Atmospheric Imaging Assembly instrument on board the Solar Dynamics Observatory. The filament oscillations were most probably triggered by the magnetic reconnection in the filament channel, which is characterized by the bidirectional flows, brightenings in EUV and soft X-ray, and magnetic cancellation in the photosphere. The directions of oscillations have angles of 4°-36° with respect to the filament axis. The whole filament did not oscillate in phase as a rigid body. Meanwhile, the oscillation periods (3100-4400 s) have a spatial dependence, implying that the curvature radii (R) of the magnetic dips are different at different positions. The values of R are estimated to be 69.4-133.9 Mm, and the minimum transverse magnetic field of the dips is estimated to be 15 G. The amplitudes of S5-S8 grew with time, while the amplitudes of S9-S14 damped with time. The oscillation amplitudes range from a few to ten Mm, and the maximum velocity can reach 30 km s-1. Interestingly, the filament experienced mass drainage southward at a speed of ˜27 km s-1. The oscillations continued after the mass drainage and lasted for more than 11 hr. After the mass drainage, the oscillation phases did not change much. The periods of S5-S8 decreased, while the periods of S9-S14 increased. The amplitudes of S5-S8 damped with time, while the amplitudes of S9-S14 grew. Most of the damping (growing) ratios are between -9 and 14. We offer a schematic cartoon to explain the complex behaviors of oscillations by introducing thread-thread interaction.

  17. Scattering amplitudes and contact interactions in Witten's superstring field theory

    International Nuclear Information System (INIS)

    Wendt, C.

    1989-01-01

    The four-massless-particle scattering amplitudes are calculated for Witten's covariant superstring field theory. The picture-changing effects of the Ramond sector propagator and of the three-boson vertex are displayed. The results agree with the first-quantized prescription of Friedan, Martinec and Shenker except for the four-boson amplitude, where an extra divergent contact term appears. The addition of a four-boson counterterm to Witten's action cancels the extra term, and is also necessary for gauge invariance of the action to order g 2 . (orig.)

  18. Photoacoustic microbeam-oscillator with tunable resonance direction and amplitude

    Science.gov (United States)

    Wu, Qingjun; Li, Fanghao; Wang, Bo; Yi, Futing; Jiang, J. Z.; Zhang, Dongxian

    2018-01-01

    We successfully design one photoacoustic microbeam-oscillator actuated by nanosecond laser, which exhibits tunable resonance direction and amplitude. The mechanism of laser induced oscillation is systematically analyzed. Both simulation and experimental results reveal that the laser induced acoustic wave propagates in a multi-reflected mode, resulting in resonance in the oscillator. This newly-fabricated micrometer-sized beam-oscillator has an excellent actuation function, i.e., by tuning the laser frequency, the direction and amplitude of actuation can be efficiently altered, which will have potential industrial applications.

  19. Large Amplitude Oscillatory Extension of Soft Polymeric Networks

    DEFF Research Database (Denmark)

    Bejenariu, Anca Gabriela; Rasmussen, Henrik K.; Skov, Anne Ladegaard

    2010-01-01

    sing a filament stretching rheometer (FSR) surrounded by a thermostatic chamber and equipped with a micrometric laser it is possible to measure large amplitude oscillatory elongation (LAOE) on elastomeric based networks with no base flow as in the LAOE method for polymer melts. Poly(dimethylsilox......sing a filament stretching rheometer (FSR) surrounded by a thermostatic chamber and equipped with a micrometric laser it is possible to measure large amplitude oscillatory elongation (LAOE) on elastomeric based networks with no base flow as in the LAOE method for polymer melts. Poly...

  20. Amplitudes do calor específico para sistemas competitivos

    OpenAIRE

    Isidorio de Sena Junior, Marcone

    2010-01-01

    Neste trabalho, usamos téecnicas de teoria de campos escalares e argumentos de grupo de renormalização para determinarmos a razão entre as amplitudes críticas do calor específico para sistemas competitivos arbitrários. Os resultados são obtidos pela primeira vez na literatura em primeira ordem na expansão em loops. Utilizamos um campo (parâmetro de ordem) de N componentes com simetria O(N). Calculamos as amplitudes críticas primeiramente para os casos anisotrópicos e isotrópico...

  1. Numerical construction of 'optimal' nonoscillating amplitude and phase functions

    International Nuclear Information System (INIS)

    Matzkin, A.; Lombardi, M.

    2002-01-01

    A numerical recipe for the construction of nonoscillating amplitude and phase functions for potentials with a single minimum is given. We give different examples illustrating the recipe, showing the usefulness of the procedure for the construction of basis functions in bound-state scattering processes, such as those described by quantum defect theory. The resulting amplitude and accumulated phase functions are coined as 'optimal' nonoscillating (as a function of the space and energy variables) because they are the counterpart for the quantum problem of the classical action for the analog semiclassical problem

  2. From maximal to minimal supersymmetry in string loop amplitudes

    Science.gov (United States)

    Berg, Marcus; Buchberger, Igor; Schlotterer, Oliver

    2017-04-01

    We calculate one-loop string amplitudes of open and closed strings with N = 1 , 2 , 4 supersymmetry in four and six dimensions, by compactification on Calabi-Yau and K3 orbifolds. In particular, we develop a method to combine contributions from all spin structures for arbitrary number of legs at minimal supersymmetry. Each amplitude is cast into a compact form by reorganizing the kinematic building blocks and casting the worldsheet integrals in a basis. Infrared regularization plays an important role to exhibit the expected factorization limits. We comment on implications for the one-loop string effective action.

  3. Asymptotic behaviour of physical amplitudes in a finite field theory

    International Nuclear Information System (INIS)

    Helayel Neto, J.A.; Rajpoot, S.; Smith, A.W.

    1987-01-01

    Using the N=4 super-Yang-Mills theory softly broken by supersymmetric N=1 mass terms for matter superfields, we compute the one-loop chiral + chiral → antichiral + antichiral scattering amplitude directly in superspace. By suitable choices of the mass parameters, on can endow the model with a hierarchy of light and heavy particles, and the decoupling of the heavy sector from light-light physical amplitude is studied. We also analyze the high-energy limit of the cross-section for a two physical scalar scattering and find a (logs) behaviour, which then respects the Froissart bound. (author) [pt

  4. Amplitude of primeval fluctuations from cosmological mass density reconstructions

    Science.gov (United States)

    Seljak, Uros; Bertschinger, Edmund

    1994-01-01

    We use the POTENT reconstruction of the mass density field in the nearby universe to estimate the amplitude of the density fluctuation power spectrum for various cosmological models. We find that sigma(sub 8) Omega(sub m sup 0.6) = 1.3(sub -0.3 sup +0.4), almost independently of the power spectrum. This value agrees well with the Cosmic Background Explorer (COBE) normalization for the standard cold dark matter model, while alternative models predict an excessive amplitude compared with COBE. Flat, low Omega(sub m) models and tilted models with spectral index n less than 0.8 are particularly discordant.

  5. Combining fixed-order helicity amplitudes with resummation using SCET

    Energy Technology Data Exchange (ETDEWEB)

    Stewart, Ian W. [Massachusetts Institute of Technology, Cambridge, MA (United States). Center for Theoretical Physics; Tackmann, Frank J. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany). Theory Group; Waalewijn, Wouter J. [California Univ., San Diego, La Jolla, CA (United States). Dept. of Physics

    2012-11-15

    We discuss how to construct a simple and easy-to-use helicity operator basis in Soft-Collinear Effective Theory (SCET), for which the hard Wilson coefficients from matching QCD onto SCET are directly given in terms of the color-ordered QCD helicity amplitudes. This provides an interface to seamlessly combine fixed-order helicity amplitudes, which are the basic building blocks of state-of-the-art next-to-leading order calculations for multileg processes, with a resummation of higher-order logarithmic corrections using SCET.

  6. On tree amplitudes of supersymmetric Einstein-Yang-Mills theory

    Energy Technology Data Exchange (ETDEWEB)

    Adamo, Tim; Casali, Eduardo; Roehrig, Kai A.; Skinner, David [Department of Applied Mathematics & Theoretical Physics, University of Cambridge,Wilberforce Road, Cambridge, CB3 0WA United Kingdom (United Kingdom)

    2015-12-29

    We present a new formula for all single trace tree amplitudes in four dimensional super Yang-Mills coupled to Einstein supergravity. Like the Cachazo-He-Yuan formula, our expression is supported on solutions of the scattering equations, but with momenta written in terms of spinor helicity variables. Supersymmetry and parity are both manifest. In the pure gravity and pure Yang-Mills sectors, it reduces to the known twistor-string formulae. We show that the formula behaves correctly under factorization and sketch how these amplitudes may be obtained from a four-dimensional (ambi)twistor string.

  7. Amplitude Dependent Internal Friction in a Mg-Al-Zn Alloy Studied after Thermal and Mechanical Treatment

    Directory of Open Access Journals (Sweden)

    Zuzanka Trojanová

    2017-10-01

    Full Text Available The amplitude-dependent internal friction of continuously-cast and rolled AZ31 magnesium alloy was measured in this study. Samples were annealed and quenched step by step; immediately after the treatment, the amplitude dependence of the logarithmic decrement was measured. Changes in the microstructure due to thermomechanical treatment were reflected in changes in the damping. Internal friction is influenced by the dislocation substructure and its modification due to solute atoms migration, microplastic deformation, and twins’ formation. Internal friction in the rolled sheets is affected by the rolling texture.

  8. Preservation of motor maps with increased motor evoked potential amplitude threshold in RMT determination.

    Science.gov (United States)

    Lucente, Giuseppe; Lam, Steven; Schneider, Heike; Picht, Thomas

    2018-02-01

    Non-invasive pre-surgical mapping of eloquent brain areas with navigated transcranial magnetic stimulation (nTMS) is a useful technique linked to the improvement of surgical planning and patient outcomes. The stimulator output intensity and subsequent resting motor threshold determination (rMT) are based on the motor-evoked potential (MEP) elicited in the target muscle with an amplitude above a predetermined threshold of 50 μV. However, a subset of patients is unable to achieve complete relaxation in the target muscles, resulting in false positives that jeopardize mapping validity with conventional MEP determination protocols. Our aim is to explore the feasibility and reproducibility of a novel mapping approach that investigates how an increase of the MEP amplitude threshold to 300 and 500 μV affects subsequent motor maps. Seven healthy subjects underwent motor mapping with nTMS. RMT was calculated with the conventional methodology in conjunction with experimental 300- and 500-μV MEP amplitude thresholds. Motor mapping was performed with 105% of rMT stimulator intensity using the FDI as the target muscle. Motor mapping was possible in all patients with both the conventional and experimental setups. Motor area maps with a conventional 50-μV threshold showed poor correlation with 300-μV (α = 0.446, p motor area maps (α = 0.974, p motor area mapping with nTMS without losing precision.

  9. A Cascaded Approach for Correcting Ionospheric Contamination with Large Amplitude in HF Skywave Radars

    Directory of Open Access Journals (Sweden)

    Yajun Li

    2014-01-01

    Full Text Available Ionospheric phase perturbation with large amplitude causes broadening sea clutter’s Bragg peaks to overlap each other; the performance of traditional decontamination methods about filtering Bragg peak is poor, which greatly limits the detection performance of HF skywave radars. In view of the ionospheric phase perturbation with large amplitude, this paper proposes a cascaded approach based on improved S-method to correct the ionospheric phase contamination. This approach consists of two correction steps. At the first step, a time-frequency distribution method based on improved S-method is adopted and an optimal detection method is designed to obtain a coarse ionospheric modulation estimation from the time-frequency distribution. At the second correction step, based on the phase gradient algorithm (PGA is exploited to eliminate the residual contamination. Finally, use the measured data to verify the effectiveness of the method. Simulation results show the time-frequency resolution of this method is high and is not affected by the interference of the cross term; ionospheric phase perturbation with large amplitude can be corrected in low signal-to-noise (SNR; such a cascade correction method has a good effect.

  10. Electrophysiological changes in 12-year-old children born MLP: reduced VEP amplitude in MLP children.

    Science.gov (United States)

    Raffa, Lina H; Nilsson, Josefin; Dahlgren, Jovanna; Grönlund, Marita Andersson

    2017-09-01

    To study the electrophysiological changes in relation to fundus morphology in moderate-to-late preterm (MLP) children with no previous history of retinopathy of prematurity. Visual acuity (VA), refraction and fundus variables measured by optical coherence tomography, pattern reversal visual evoked potentials and full-field electroretinography (ff-ERG) were obtained from 22 twelve-year-old MLP children (11 male, 11 female) and 21 full-term controls. There were no significant differences between the MLP and control groups in VA, refraction or optic disc parameters. There was a trend for thinner papillary retinal nerve fibre layer in the MLP group. Visual evoked potential amplitudes (P100) were lower in the MLP group than in controls, that is, right eye p=0.0027, left eye p=0.0037. No differences in latencies were found. After Bonferroni adjustment for multiple testing, no ff-ERG differences were noted between MLP and controls. Lower gestational age was correlated with smaller light-adapted 3.0 b-wave amplitudes (p=0.0076, r=0.565). Our results indicate that moderate premature birth may affect visual evoked potential amplitudes without clear retinal structural changes in MLP children at 12 years of age. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

  11. Upper Extremity Freezing and Dyscoordination in Parkinson’s Disease: Effects of Amplitude and Cadence Manipulations

    Directory of Open Access Journals (Sweden)

    April J. Williams

    2013-01-01

    Full Text Available Purpose. Motor freezing, the inability to produce effective movement, is associated with decreasing amplitude, hastening of movement, and poor coordination. We investigated how manipulations of movement amplitude and cadence affect upper extremity (UE coordination as measured by the phase coordination index (PCI—only previously measured in gait—and freezing of the upper extremity (FO-UE in people with Parkinson's disease (PD who experience freezing of gait (PD + FOG, do not experience FOG (PD-FOG, and healthy controls. Methods. Twenty-seven participants with PD and 18 healthy older adults made alternating bimanual movements between targets under four conditions: Baseline; Fast; Small; SmallFast. Kinematic data were recorded and analyzed for PCI and FO-UE events. PCI and FO-UE were compared across groups and conditions. Correlations between UE PCI, gait PCI, FO-UE, and Freezing of Gait Questionnaire (FOG-Q were determined. Results. PD + FOG had poorer coordination than healthy old during SmallFast. UE coordination correlated with number of FO-UE episodes in two conditions and FOG-Q score in one. No differences existed between PD−/+FOG in coordination or number of FO-UE episodes. Conclusions. Dyscoordination and FO-UE can be elicited by manipulating cadence and amplitude of an alternating bimanual task. It remains unclear whether FO-UE and FOG share common mechanisms.

  12. Mirror symmetry, toric branes and topological string amplitudes as polynomials

    International Nuclear Information System (INIS)

    Alim, Murad

    2009-01-01

    The central theme of this thesis is the extension and application of mirror symmetry of topological string theory. The contribution of this work on the mathematical side is given by interpreting the calculated partition functions as generating functions for mathematical invariants which are extracted in various examples. Furthermore the extension of the variation of the vacuum bundle to include D-branes on compact geometries is studied. Based on previous work for non-compact geometries a system of differential equations is derived which allows to extend the mirror map to the deformation spaces of the D-Branes. Furthermore, these equations allow the computation of the full quantum corrected superpotentials which are induced by the D-branes. Based on the holomorphic anomaly equation, which describes the background dependence of topological string theory relating recursively loop amplitudes, this work generalizes a polynomial construction of the loop amplitudes, which was found for manifolds with a one dimensional space of deformations, to arbitrary target manifolds with arbitrary dimension of the deformation space. The polynomial generators are determined and it is proven that the higher loop amplitudes are polynomials of a certain degree in the generators. Furthermore, the polynomial construction is generalized to solve the extension of the holomorphic anomaly equation to D-branes without deformation space. This method is applied to calculate higher loop amplitudes in numerous examples and the mathematical invariants are extracted. (orig.)

  13. Mimicking an amplitude damping channel for Laguerre Gaussian Modes

    CSIR Research Space (South Africa)

    Dudley, Angela L

    2010-10-01

    Full Text Available amplitude damping channel for single photons, given by Eq. 1, is verified by means of classical light carrying OAM. The evolution of the classical electric field in the interferometer can be described similarly to Eq. 1. Therefore, by measuring the power...

  14. Acute Effect of Caffeine on Amplitude of Accommodation and Near ...

    African Journals Online (AJOL)

    Caffeine is widely consumed in kola nuts and in other products in Sub-Saharan Africa. We examined the acute effect of caffeine on the amplitude of accommodation and near point of convergence of healthy Nigerians. Forty volunteers between ages of 20 and 27 years with refractive power± 0.50 DS were employed.

  15. Statistical amplitude scale estimation for quantization-based watermarking

    NARCIS (Netherlands)

    Shterev, I.D.; Lagendijk, I.L.; Heusdens, R.

    2004-01-01

    Quantization-based watermarking schemes are vulnerable to amplitude scaling. Therefore the scaling factor has to be accounted for either at the encoder, or at the decoder, prior to watermark decoding. In this paper we derive the marginal probability density model for the watermarked and attacked

  16. Path integral approach to the quantum fidelity amplitude.

    Science.gov (United States)

    Vaníček, Jiří; Cohen, Doron

    2016-06-13

    The Loschmidt echo is a measure of quantum irreversibility and is determined by the fidelity amplitude of an imperfect time-reversal protocol. Fidelity amplitude plays an important role both in the foundations of quantum mechanics and in its applications, such as time-resolved electronic spectroscopy. We derive an exact path integral formula for the fidelity amplitude and use it to obtain a series of increasingly accurate semiclassical approximations by truncating an exact expansion of the path integral exponent. While the zeroth-order expansion results in a remarkably simple, yet non-trivial approximation for the fidelity amplitude, the first-order expansion yields an alternative derivation of the so-called 'dephasing representation,' circumventing the use of a semiclassical propagator as in the original derivation. We also obtain an approximate expression for fidelity based on the second-order expansion, which resolves several shortcomings of the dephasing representation. The rigorous derivation from the path integral permits the identification of sufficient conditions under which various approximations obtained become exact. © 2016 The Authors.

  17. Time-varying interaction leads to amplitude death in coupled ...

    Indian Academy of Sciences (India)

    A new form of time-varying interaction in coupled oscillators is introduced. In this interaction, each individual oscillator has always time-independent self-feedback while its interaction with other oscillators are modulated with time-varying function. This interaction gives rise to a phenomenon called amplitude death even in ...

  18. A pulse amplitude dividing circuit for nuclear applications

    International Nuclear Information System (INIS)

    Ediss, C.; McQuarrie, S.A.

    1981-01-01

    A pulse dividing circuit has been developed to provide analogue and digital outputs proportional to the ratio of the amplitudes of two nuclear pulses. Input pulses ranging from 200 mV to 10 V may be processed by the device. The pulse dividing circuit has been successfully incorporated as part of a small gamma camera. (orig.)

  19. Coupled Higgs field equation and Hamiltonian amplitude equation ...

    Indian Academy of Sciences (India)

    (G /G)-expansion method for finding exact travelling wave solutions of Higgs field equa- tion. Section 3.2 is devoted to find travelling wave solutions of Hamiltonian amplitude equation. In §4, some conclusions are given. 2. Lie symmetry analysis. Lie's method [8–10] is an effective method and is the simplest among group ...

  20. Monodromy relations in higher-loop string amplitudes

    Science.gov (United States)

    Hohenegger, S.; Stieberger, S.

    2017-12-01

    New monodromy relations of loop amplitudes are derived in open string theory. We particularly study N-point (planar and non-planar) one-loop amplitudes described by a world-sheet cylinder and derive a set of relations between subamplitudes of different color orderings. Various consistency checks are performed by matching α‧-expansions of planar and non-planar amplitudes involving elliptic iterated integrals with the resulting periods giving rise to two sets of multiple elliptic zeta values. The latter refer to the two homology cycles on the once-punctured complex elliptic curve and the monodromy equations provide relations between these two sets of multiple elliptic zeta values. Furthermore, our monodromy relations involve new objects for which we present a tentative interpretation in terms of open string scattering amplitudes in the presence of a non-trivial gauge field flux. Finally, we provide an outlook on how to generalize the new monodromy relations to the non-oriented case and beyond the one-loop level. Comparing a subset of our results with recent findings in the literature we find therein several serious issues related to the structure and significance of monodromy phases and the relevance of missed contributions from contour integrations.