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Sample records for amplitude dos pulsos

  1. Detection of hydrocarbons in sandy sediments analyzing velocity and amplitude of electromagnetic pulses (GPR-Ground Penetrating Radar); Deteccao de hidrocarbonetos em sedimentos arenosos analisando velocidade e amplitude dos pulsos eletromagneticos (GPR)

    Energy Technology Data Exchange (ETDEWEB)

    Dourado, Tiago C.; Botelho, Marco A.B. [Universidade Federal da Bahia (UFBA), Salvador, BA (Brazil). Centro de Pesquisa em Geofisica e Geologia; Machado, Sandro L.; Amparo, Nelson S. [Universidade Federal da Bahia (UFBA), Salvador, BA (Brazil). Lab. de Geotecnia Ambiental - GeoAmb

    2004-07-01

    We estimate a hydrocarbon saturation of sandy soils on the basis of the velocity and amplitude of GPR (Ground Penetrating Radar) electromagnetic signals. We acquire CMP (Common Mid Point) data on a tank filled with clean sand. The tank, which has dimensions 1,0 m x 0,7 m x 0,7 m, has filled with water and diesel oil. The velocity decreases from 15 cm/ns for 3% water saturation to 5 cm/ns for 24% water saturation. The presence of hydrocarbon only causes small velocity variations, from 13 cm/ns to 15 cm/ns in the first case. We also investigate the AVO (amplitude variations with offset) of a dry sand/water-saturated sand interface and compare the results to those of the oil-saturated sand/water-saturated sand interface. These results are further compared to the Fresnel equations after the estimation of the reflection coefficient from the reflection hyperbole. The agreement is excellent, and the methodology can be usual to evaluate the type of saturating fluid and the corresponding saturating level. Future experiments will involve the detection and modeling of the critical and Brewster angles to obtain additional information. (author)

  2. Correlation between diurnal variation of intraocular pressure, ocular pulse amplitude and corneal structural properties Correlação entre a variação diurna da pressão intraocular, amplitude de pulso e propriedades estruturais corneanas

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    Flávia Silva Villas-Bôas

    2009-06-01

    Full Text Available PURPOSE: The purpose of this study was to evaluate the fluctuation of intraocular pressure measurements obtained by Goldmann applanation tonometry, dynamic contour tonometry, and corneal compensated non-contact tonometry during office hours in glaucoma and healthy participants. This study also aims at correlating the intraocular pressure fluctuations with fluctuations of corneal hysteresis, central corneal thickness, mean central corneal curvature and ocular pulse amplitude. METHODS: A total of 12 controls (24 eyes and 21 patients (38 eyes with open-angle glaucoma were recruited. Intraocular pressure measured by Goldmann applanation tonometry, dynamic contour tonometry and corneal compensated non-contact tonometry, ocular pulse amplitude, central corneal curvature and thickness, corneal hysteresis, and resistance factor were obtained at intervals of 2 hours, between 9 AM and 5 PM. RESULTS: Intraocular pressure fluctuated significantly throughout the day in controls and glaucoma individuals with all tonometers (POBJETIVO: Avaliar a flutuação das medidas da pressão intraocular obtidas pela tonometria de aplanação de Goldmann, tonometria de contorno dinâmico e pela tonometria de não-contato com compensação corneana durante o período ambulatorial, em participantes com glaucoma e saudáveis. Esse estudo também correlacionou as flutuações da pressão intraocular com as flutuações da histerese corneana, espessura corneana central, média da curvatura corneana central e amplitude de pulso ocular. MÉTODOS: Um total de 12 controles (24 olhos e 21 pacientes com glaucoma de ângulo aberto (38 olhos foram selecionados. A pressão intraocular medida pela tonometria de aplanação de Goldmann, tonometria de contorno dinâmico e tonometria de não-contato com compensação corneana, amplitude de pulso ocular, a curvatura central e espessura corneanas, a histerese corneana e o fator de resistência foram medidos em intervalos de 2 horas, entre 9

  3. Análise comparativa da amplitude do pulso ocular e pressão de perfusão ocular em glaucomatosos, hipertensos oculares e indivíduos normais

    OpenAIRE

    2012-01-01

    Objetivos: correlacionar pressão de perfusão ocular e amplitude do pulso ocular em três grupos: glaucomatosos, hipertensos oculares e normais; e avaliar a relação de parâmetros de pressão arterial com a pressão intraocular. Métodos: foram recrutados 90 indivíduos para a pesquisa, sendo 30 recém-diagnosticados com glaucoma, sem história prévia de tratamento antiglaucomatoso; 30 apresentavam hipertensão ocular (HO) sem sinais característicos de glaucoma na avaliação do disco óptico e no exame d...

  4. O corpo como pulso

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    Flavia Liberman

    2010-06-01

    Full Text Available O corpo é foco de muitos estudos e intervenções. Alguns paradigmas o concebem apenas em seu aspecto sensório-motor, enquanto outros transitam prioritariamente por uma dimensão psicológica. Procurando contribuir para a formulação de outras perspectivas no campo, apresentam-se aspectos da concepção de corpo de Stanley Keleman em ressonância com os estudos de Regina Favre. A partir de cenas clínicas em grupos de seminários, podemos pensar o corpo como pulso, multimídia, multifacetado, que se (des constrói permanentemente nos encontros. Articulando experiências clínicas da autora como terapeuta ocupacional e docente da graduação e em grupos de estudos, essas concepções servem como guia para uma clínica pensada, construída e balizada pelo corpo mediante utilização de abordagens corporais para a promoção de encontros plasmados por afetos e acontecimentos, na tentativa de criar corpos que possam sustentar as intensidades vividas e permitam a observação de si, a aproximação com o outro e a produção de singularidades.

  5. O corpo como pulso

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    Flavia Liberman

    Full Text Available O corpo é foco de muitos estudos e intervenções. Alguns paradigmas o concebem apenas em seu aspecto sensório-motor, enquanto outros transitam prioritariamente por uma dimensão psicológica. Procurando contribuir para a formulação de outras perspectivas no campo, apresentam-se aspectos da concepção de corpo de Stanley Keleman em ressonância com os estudos de Regina Favre. A partir de cenas clínicas em grupos de seminários, podemos pensar o corpo como pulso, multimídia, multifacetado, que se (des constrói permanentemente nos encontros. Articulando experiências clínicas da autora como terapeuta ocupacional e docente da graduação e em grupos de estudos, essas concepções servem como guia para uma clínica pensada, construída e balizada pelo corpo mediante utilização de abordagens corporais para a promoção de encontros plasmados por afetos e acontecimentos, na tentativa de criar corpos que possam sustentar as intensidades vividas e permitam a observação de si, a aproximação com o outro e a produção de singularidades.

  6. Física de película: pulsos electromagnéticos

    OpenAIRE

    Sardiña del Dedo, Alberto

    2017-01-01

    En este trabajo se abordan los pulsos electromagnéticos desde un punto de vista teórico y práctico con el objetivo final de aplicar los conocimientos adquiridos al estudio y análisis de distintos recursos filmográficos donde aparecen. De este modo, podemos distinguir en el documento dos partes distintas. En la primera de ellas, se realiza un estudio teórico necesario para comprender y poder alcanzar, en última instancia, el objetivo planteado. En primer lugar, y con cierta g...

  7. Medida no invasiva de la presión arterial central mediante tonometría por aplanamiento. Análisis de la onda de pulso

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    Dr. Alvaro Hermida Amejeiras

    2012-12-01

    Full Text Available La tonometría por aplanamiento (TA es una medida indirecta, no invasiva, reproducible y validada para estimar la forma de la onda de pulso aórtica13. La propia forma de la onda de pulso, junto con la amplitud de la misma o su duración aportan información útil para el diagnóstico y manejo de diferentes entidades nosológicas (ej. cambios asociados al envejecimiento, hipertensión arterial, cardiopatía isquémica, diabetes mellitus, hábito tabáquico,....

  8. Geração e propagação de pulsos em laser a fibra dopada com Érbio com cavidades ultralongas

    OpenAIRE

    Saito, Lúcia Akemi Miyazato

    2012-01-01

    O laser de fibra dopada com Érbio é apresentado nesta tese numa nova configuração: cavidade ultralonga, com dimensão da ordem de dezenas de quilômetros. Foram investigados os mecanismos responsáveis pela formação e evolução do pulso em cavidades com comprimentos de 16,4 m a 100,8 km operando em regime de acoplamento de modos ativo na taxa de repetição de 1 GHz. A variação da largura dos pulsos e da potência de pico nestes lasers definem três regimes de propagação no interior das cavidad...

  9. Estudo das latências e amplitudes dos potenciais evocados auditivos de média latência em indivíduos audiologicamente normais Middle latency response study of auditory evoked potentials’ amplitudes and lantencies audiologically normal individuals

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    Ivone Ferreira Neves

    2007-02-01

    Full Text Available Estudo de coorte contemporânea com corte transversal. O Potencial Evocado Auditivo de Média Latência (PEAML é gerado entre 10 e 80ms e possui múltiplos geradores, com maior contribuição da região tálamo-cortical. O estabelecimento de critérios de normalidade para os valores de latência e amplitude é necessário para uso clínico. OBJETIVOS: Analisar a latência e amplitude do PEAML em indivíduos sem alterações audiológicas, e verificar a confiabilidade da amplitude Pa-Nb. MATERIAL E MÉTODO: Foram coletados os PEAML de 25 indivíduos durante o ano de 2005 e analisados os componentes Na, Pa, Nb para cada orelha testada (A1 e A2, e posicionamento de eletrodo (C3 e C4. RESULTADOS: Observou-se diferença estatisticamente significante entre os valores médios de latência para C3A1 e C4A1 com relação aos componentes Na e Pa, não sendo encontrada esta diferença para o componente Nb e valores médios das amplitudes Na-Pa e Pa-Nb. CONCLUSÃO: Foram estabelecidos os valores das médias e desvios padrão para os parâmetros latência e amplitude dos componentes Na, Pa, Nb, e Na-Pa e Pa-Nb, nas condições C3A1, C4A1, C3A2, C4A2, proporcionando os parâmetros para a análise e interpretação deste potencial.Contemporary cohort cross-sectional study. Introduction: The auditory middle latency response (AMLR is generated between 10 and 80 ms and has multiple generators, with a greater contribution from the thalamus-cortical pathways. The establishment of normality criteria for latency and amplitude values is necessary for clinical use. AIM: to analyze the latency and amplitude of the AMLR in individuals without audiological disorders, and verify the reliability of Pa-Nb amplitude. MATERIALS AND METHODS: The AMLR of 25 individuals was collected during 2005 and the Na, Pa, Nb components were analyzed for each tested ear (A1 and A2, and electrode positioning (C3 and C4. RESULTS: A statistically significant difference was noticed among middle

  10. Pulse generator for bias materials in the plasma immerse ion implantation process; Generador de pulsos para polarizar materiales en el proceso de implantacion de iones inmersos en plasma

    Energy Technology Data Exchange (ETDEWEB)

    Lopez Callegas, Regulo; Valencia Alvarado, Raul; Munoz Castro, Arturo Eduardo; Godoy Cabrera, Oscar Gerardo [Instituto Nacional de Investigaciones Nucleares, Mexico D.F. (Mexico); Moreno Saavedra, Hilda; Gonzalez Colin, Mireya; Mariano Escamilla, Hector Fernando [Instituto Tecnologico de Toluca, Estado de Mexico (Mexico)

    2003-10-15

    The 0-10 kV pulse generator has been designed, with 100 {mu}s duration and 1-100 Hz frequencies ranges. The use of the pulse generator is in the plasma immersed ion implantation technique (P III). The process was realized in 304 austenitic stainless steel, the results were analyzed by: SEM, X-rays diffraction and hardness Vickers. The hardness was increased due to the efficiency of the pulse generator and P III process, the results obtained showed that the nitrogen inside the stainless steel was implanted and besides some nitrides was formed and therefore the hardness was increased. Also, the more adequate work pressure was determined to carry out the P III process. [Spanish] Se presenta el diseno de un generador de pulsos de alto voltaje con amplitudes controladas de hasta 10 kV, la duracion maxima de los pulsos es del orden de los 100 {mu}s y frecuencia de repeticion en el intervalo de 1-100 Hz. La aplicacion de este generador de pulsos es para el proceso de implantacion de iones en materiales inmersos en plasmas (PIII). Los analisis hechos a los aceros austeniticos cedula 304 mediante microscopia electronica de barrido, difraccion de rayos X y dureza Vickers, muestran la eficiencia obtenida con el generador de pulsos en el proceso PIII, debido a que en el acero inoxidable se presenta un incremento en el nitrogeno y conformacion de algunos nitruros, lo cual da lugar al incremento de la dureza. Asimismo, se determino la presion de trabajo mas adecuada para llevar a cabo el proceso PIII.

  11. Aptidão aeróbia e amplitude dos domínios de intensidade de exercício no ciclismo

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    Renato Aparecido Corrêa Caritá

    2013-08-01

    Full Text Available INTRODUÇÃO: A determinação dos domínios de intensidade de exercício tem importantes implicações na prescrição do treino aeróbio e na elaboração de delineamentos experimentais. OBJETIVO: Analisar os efeitos do nível de aptidão aeróbia sobre a amplitude dos domínios de intensidade de exercício durante o ciclismo. MÉTODOS: Doze ciclistas (CIC, 11 corredores (COR e oito indivíduos não treinados (NT foram submetidos aos seguintes protocolos em diferentes dias: 1 teste progressivo para determinação do limiar de lactato (LL, consumo máximo de oxigênio (VO2máx e sua respectiva intensidade (IVO2máx; 2 três testes de carga constante até a exaustão a 95, 100 e 110% IVO2máx para a determinação da potência crítica (PC; 3 testes até a exaustão para determinar a intensidade superior do domínio severo (Isup. As amplitudes dos domínios (moderado pesado severo < Isup foram expressas como percentual da Isup (VO2. RESULTADOS: A amplitude do domínio moderado foi similar entre CIC (52 ± 8% e COR (47 ± 4% e significantemente maior no CIC em relação ao NT (41 ± 7%. O domínio pesado foi significantemente menor no CIC (17 ± 6% em relação ao COR (27 ± 6% e NT (27 ± 9%. Em relação ao domínio severo não foram encontradas diferenças significantes entre os CIC (31 ± 7%, COR (26 ± 5% e NT (31 ± 7%. CONCLUSÃO: O domínio pesado de exercício é mais sensível a mudanças determinadas pelo nível de aptidão aeróbia, existindo a necessidade de que se atenda ao princípio da especificidade do movimento, quando se pretende obter um elevado grau de adaptação fisiológica.

  12. Efeito Agudo da Pressao Positiva Continua sobre a Pressao de Pulso na Insuficiencia Cardiaca Cronica

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    Monica Quintao

    2014-03-01

    Full Text Available Fundamento: Pacientes com insuficiência cardíaca (IC apresentam disfunção ventricular esquerda e redução da pressão arterial média (PAM. O aumento do estímulo adrenérgico causa vasoconstrição e resistência dos vasos, mantendo a PAM, enquanto aumenta a resistência vascular periférica e a rigidez dos vasos condutores. O aumento da pressão de pulso (PP reflete a complexa interação do coração com os sistemas arteriais e venosos. O aumento da PP é um importante marcador de risco em pacientes com insuficiência cardíaca crônica (ICC. A ventilação não invasiva (VNI tem sido utilizada para IC aguda descompensada para melhorar a congestão e a ventilação pelos efeitos respiratórios e hemodinâmicos. No entanto, nenhum desses estudos relatou o efeito da VNI na PP. Objetivo: O objetivo deste estudo foi determinar os efeitos agudos da VNI com CPAP (pressão positiva contínua nas vias aéreas sobre a PP em pacientes ambulatoriais com ICC. Métodos: Seguindo um protocolo randomizado, duplo-cego, cruzado e controlado com placebo, 23 pacientes com ICC (17 homens, 60 ± 11 anos, IMC 29 ± 5 kg/cm2, classes II e III da NYHA foram submetidos à CPAP via máscara nasal durante 30 minutos na posição reclinada. A pressão da máscara foi de 6 cmH2O, enquanto o placebo foi fixado em 0-1 cmH2O. PP e outras variáveis hemodinâmicas não invasivas foram avaliadas antes, durante e depois do placebo e do modo CPAP. Resultados: A CPAP diminuiu a frequência cardíaca de repouso (pré: 72 ± 9; pós 5 min: 67 ± 10 bpm , p < 0,01 e PAM (CPAP: 87 ± 11; controle 96 ± 11 mmHg , p < 0,05 pós 5 min. A CPAP diminuiu a PP (CPAP: 47 ± 20 pré para 38 ± 19 mmHg pós; controle: 42 ± 12 mmHg, pré para 41 ± 18 pós p < 0,05 pós 5 min. Conclusão: A VNI com CPAP diminuiu a pressão de pulso em pacientes com ICC estável. Ensaios clínicos futuros devem investigar se esse efeito está associado com melhora no desfecho clínico.

  13. Índice para la evaluación de las reflexiones mediante análisis de la onda de pulso radial

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    Gustavo J. Meschino

    2008-01-01

    Full Text Available En el presente trabajo se analiza la posibilidad de utilizar un parámetro obtenido del registro de la onda de pulso radial, el ancho de la onda sistólica, que es más sencillo de medir aún que el índice de aumentación radial y que complementaría a este último en la evaluación de la amplitud de la reflexión sistólica, directamente relacionada con el grado de disfunción endotelial y el fenómeno de aumentación aórtica.Se efectuó un estudio poblacional sobre 120 varones normotensos sanos con edades entre 17 y 65 años. Se obtuvo en ellos el registro de la onda de pulso radial en base al registro del movimiento de las paredes de la arteria mediante un sensor capacitivo aplicado sobre la zona de palpación del pulso. Cada registro se procesó y normalizó en amplitud y se calculó el índice de aumentación radial y el ancho de la onda sistólica al 50% de su altura máxima.Se halló que individuos con el mismo índice de aumentación poseían distintos valores de ancho de onda sistólica, lo cual evidencia distintos valores de amplitud de la onda reflejada. Ambos parámetros aumentaron con la edad y su correlación r resultó de 0,9.Se propone la utilización del ancho de la onda sistólica como un índice de envejecimiento alternativo, que permitiría evaluar el sistema arterial cuando la medición del índice de aumentación resultara dificultosa o la comparación entre individuos fuera ambigua.

  14. A melhoria da amplitude articular e/ou manutenção dos movimentos em pessoas portadoras de paralisia cerebral espástica através da educação física adaptada

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    Romeu Schutz

    2002-04-01

    Full Text Available Esta pesquisa relata o trabalho desenvolvido durante quatro meses, com três alunos portadores de Paralisia Cerebral (PC espástica, frequentadores da "Escola de Educação Especial Sinhara Vianna" - APAE de Palmas-Pr, na qual recebem atendimento especializado. Teve como objetivos específicos: caracterizar a prática da Educação Física Adaptada (EFA para deficientes físicos; observar as mudanças acontecidas na amplitude articular (ADM dos educandos bem como a auto-estima; adequar técnicas esportivas lúdicas para as necessidades específicas de portadores de deficiência física, propondo assim alternativas que possam auxiliar pais, professores e pessoas interessadas.Palavras Chave: Amplitude Articular; Educação Física Adaptada; Paralisia Cerebral Espástica. 

  15. Implementación de la modulación por densidad de pulsos PDM en un sistema de generación de ozono y su efecto en la curva característica de eficiencia

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    William Andrés Cifuentes Rojas

    2014-12-01

    Full Text Available Los sistemas de generación de ozono generalmente utilizan la modulación por amplitud de pulsos (PAM para variar o controlar la concentración de ozono. En este trabajo se presentan los resultados obtenidos luego de la implementación de la modulación por densidad de pulsos (PDM en la fuente de potencia de un sistema de generación de ozono y el mejoramiento logrado en la curva característica de la eficiencia. Las técnicas PAM y PDM se aplicaron en un sistema de generación de ozono con inversor push-pull auto-resonante. La amplitud de voltaje ajustada en la onda de potencia PDM se determinó de la condición de la onda PAM donde se obtuvo la máxima eficiencia en el 60 % de los puntos de operación del sistema de generación de ozono.

  16. Modelagem da bobina de Rogowski para medidas de pulsos de corrente elétrica /

    OpenAIRE

    2006-01-01

    Orientador: Vitoldo Swinka Filho Dissertaçăo (mestrado) - Universidade Federal do Paraná, Setor de Tecnologia, Programa de Pós-Graduaçăo em Engenharia - PIPE. Defesa: Curitiba, 2006 Inclui bibliografia e anexos Resumo: O presente trabalho apresenta a modelagem de sensores de corrente baseados no efeito Rogowski. O objetivo é o desenvolvimento de um sensor para detectar pulsos de corrente de alta freqüęncia que percorrem um cabo isolado com polietileno reticulado XLPE de média tensăo...

  17. Glucose disturbances in non-diabetic patients receiving acute treatment with methylprednisolone pulses Distúrbios de glicose em pacientes não diabéticos que recebem tratamento agudo com pulsos de metilprednisolona

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    Hector Eloy Tamez Perez

    2012-02-01

    como tratamento para diversas doenças autoimunes. Variáveis demográficas, antropométricas e metabólicas foram analisadas, e glicose, insulina e níveis de peptídeo C foram identificados após cada pulso de esteroide. Diferentes variáveis e a magnitude da hiperglicemia foram analisadas utilizando a correlação de Pearson. RESULTADOS: 50 pacientes foram incluídos, predominantemente mulheres (66%, n = 33. A idade média foi de 41 ± 14 anos com um IMC de 26 ± 3 kg/m². A glicose de base foi de 83 ± 10 mg/dL. Após cada pulso de esteroide, a glicose aumentou para 140 ± 28, 160 ± 38 e 183 ± 44, respectivamente (p < 0,001. Peptídeo C e concentrações de insulina aumentaram significativamente (p < 0,001. A prevalência de hiperglicemia em jejum após cada pulso foi de 68%, 94% e 98%, respectivamente. Não encontramos nenhuma correlação entre a magnitude da hiperglicemia e as variáveis estudadas. CONCLUSÃO: Os pulsos de metilprednisolona produziram aumentos significativos na glicemia de jejum na maioria dos pacientes sem diabetes. Mais estudos são necessários para definir o seu papel nas consequências em longo prazo.

  18. Avaliação do deslocamento de minhocas (Eudrilus Eugeniae submetidas a pulsos elétricos controlados Evaluation of the displacement of earthworms (Eudrilus eugeniae submitted to controlled electric pulses

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    Delly Oliveira Filho

    2005-09-01

    Full Text Available Realizou-se este trabalho com o objetivo de determinar, em laboratório, os índices de deslocamento e de separação de minhocas gigante africana (Eudrilus eugeniae do húmus, e definir as características elétricas dos pulsos elétricos que permitam melhor eficiência na separação de minhocas em escala piloto. Os testes realizados apresentavam as seguintes características: (i tensão de 100 a 500 V; (ii patamar de pulso de 2, 3 e 4 ms; (iii freqüência de 1 e 5 Hz; e (iv tempo de exposição de 1, 2, 3 e 4 h. Verificou-se que as minhocas submetidas aos pulsos elétricos se deslocam, preferencialmente, no sentido do cátodo. Nas situações estudadas o maior valor de índice de deslocamento obtido foi de 78,18% e o índice de separação, de 62,37%. A utilização de pulsos elétricos controlados, para a separação de minhocas do húmus, gera um ganho médio, ao longo da vida útil estimada, de cerca de 26% de economia financeira.The objective of this work was to determine, in laboratory, the displacement index and the separation index of earthworms (Eudrilus eugeniae from the humus, to define the characteristics of the electric pulses that allow better efficiency in the separation of earthworms in pilot scale. The tests presented the following characteristics: (i tension - 100 to 500 V; (ii pulse level - 2.3 and 4 ms; (iii frequency - 1 and 5 Hz; (iv exhibition time - 1, 2, 3 and 4 h. It was verified that the earthworms submitted to the electric pulses preferentially move towards the cathode. For the studied situations the highest value obtained for the displacement index was 78.18%, while the separation index was 63.37%. The utilization of controlled electric pulses for the earthworm separation from the substrate generate mean gain along the estimated useful life of, around 26% of economic savings.

  19. Respuesta a pulsos galvanostáticos del acero embebido en concretos de escoria activada alcalinamente

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    Willian Arnulfo Aperador-Chaparro

    2015-05-01

    Full Text Available Presenta la aplicación de la técnica de pulsos galvanostáticos en el concreto de escoria activada alcalinamente, sometido a procesos acelerados de carbonatación. Como material de referencia se utilizó el concreto Portland ordinario. La utilización de dicha técnica permitió calcular el valor de las resistencias involucradas en el proceso de forma separada, permitiendo hallar la velocidad de corrosión mediante la ecuación de Stern y Geary. Los productos de corrosión fueron determinados con la técnica de Espectrometría Mössbauer, correspondientes a magnetita, wuestite y goethita.

  20. A velocidade da onda de pulso em jovens: estudo do Rio de Janeiro

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    Oswaldo Luiz Pizzi

    2011-07-01

    Full Text Available FUNDAMENTO: A velocidade da onda de pulso (VOP pode ser marcador de comprometimento cardiovascular, porém existem poucos estudos em adultos jovens. OBJETIVO: Avaliar a associação da pressão arterial (PA, variáveis antropométricas e metabólicas, atuais e obtidas 13 anos antes, na infância e adolescência, com a VOP. MÉTODOS: Sessenta indivíduos foram acompanhados longitudinalmente e estratificados em dois grupos segundo o percentil da pressão arterial (PA obtido 13 anos antes: Grupo 1 (G1: percentil da PA 95 (n = 35, 19M, 25,4 anos. Foram submetidos a avaliação clínica, análise laboratorial e medidas da VOP pelo método Complior. RESULTADOS: G1 apresentou maior média de idade; G2 exibiu maior média de: peso, PA sistólica (PAS, PA diastólica (PAD, PA média (PAM, VOP e glicemia, e menor média de HDL-colesterol. PAS, PAM e frequência cardíaca (FC obtidas na infância e adolescência apresentaram correlação significativa com a VOP. Peso, altura, cintura, relação cintura/quadril, PAS, PAD, pressão de pulso (PP, PAM e creatinina atuais apresentaram correlação positiva e significativa com a VOP. A comparação das médias de VOP ajustadas pela PAS, PAD, PAS e PAD, PAM e PP não mostrou diferença estatisticamente significativa entre os grupos. CONCLUSÃO: O percentil da PA na infância/adolescência mostrou-se relacionado à distensibilidade arterial, avaliada pela VOP, 13 anos após. Alterações da VOP podem ser identificadas em indivíduos jovens, sugerindo que o comprometimento vascular precoce pode estar presente nessa faixa etária, relacionado também a pressão arterial, variáveis antropométricas e metabólicas.

  1. Modificações dos níveis de gonadotrofinas durante a vida reprodutiva Gonadotropin level changes during the reproductive life

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    Sebastião Freitas de Medeiros

    2007-01-01

    Full Text Available As modificações nas concentrações das gonadotrofinas ao longo da vida reprodutiva dependem de amadurecimento funcional harmônico entre conexões neurais, neurônios-GnRH no hipotálamo, gonadotropos hipofisários e células da granulosa e teca da parede folicular. As concentrações de LH e FSH sofrem variações com o período do dia, fase do ciclo menstrual e idades ginecológica e cronológica. A variação circadiana é marcante para o LH e ocorre na fase puberal, quando os pulsos têm maior freqüência e amplitude no período noturno. Na fase puberal tardia, os pulsos das gonadotrofinas ocorrem também durante o dia e perdem a variação noite-dia, permanecendo discretas alterações durante as 24 horas do dia. No ciclo menstrual, durante os anos reprodutivos, o FSH eleva-se no final da fase lútea tardia, declina na fase folicular média, eleva-se bruscamente na fase ovulatória e permanece em níveis basais até a fase lútea tardia. O LH permanece em níveis constantes durante toda a fase folicular, eleva-se no pico ovulatório e declina a níveis basais na fase lútea. Na quarta década, há modificações hipotálamo-neurais na secreção de GnRH, atenuação do retrocontrole positivo exercido pelo estradiol e diminuição na freqüência e prolongamento dos pulsos de GnRH. A hipófise responde com diminuição na densidade de receptores-GnRH, perda da sensibilidade do gonadotropo, secreção de gonadotrofinas mais básicas com maior meia-vida, diminuição na freqüência e maior amplitude dos pulsos de LH e FSH e secreção preferencial de FSH. Estas modificações, associadas à aceleração no consumo folicular, explicam a elevação monotrópica mais rápida de FSH após os 37-38 anos e a manutenção de níveis quase constantes de LH até o final do período reprodutivo. Estudos consistentes mostram que a elevação seletiva dos níveis basais de FSH na fase folicular precoce na verdade é gradual, sendo observada já na

  2. Velocidade da onda de pulso, pressão arterial e adipocitocinas em adultos jovens: estudo do Rio de Janeiro

    Directory of Open Access Journals (Sweden)

    Oswaldo Luiz Pizzi

    2013-01-01

    Full Text Available FUNDAMENTO: Dados sobre a avaliação não invasiva vascular e suas relações com variáveis de risco cardiovascular são escassos em jovens. OBJETIVO: Avaliar a relação entre a velocidade de onda de pulso e a pressão arterial,variáveis antropométricas e metabólicas, incluindo as adipocitocinas, em indivíduos adultos jovens. MÉTODOS: Foram avaliados 96 indivíduos (51 homens do estudo do Rio de Janeiro, de 26 a 35 anos (média 30,09 ± 1,92. Foram obtidos a velocidade de onda de pulso (método Complior, pressão arterial, índice de massa corporal, glicose, perfil lipídico, leptina, insulina, adiponectina e o índice de resistência à insulina HOMA-IR. Os indivíduos foram estratificados em três grupos segundo o tercil da VOP para cada sexo. RESULTADOS: O grupo com maior tercil de VOP mostrou maiores médias de pressão arterial sistólica, pressão arterial diastólica, pressão arterial média, índice de massa corporal, insulina, HOMA-IR e menores médias de adiponectina, além de maiores prevalências de diabetes mellitus/intolerância à glicose e hiperinsulinemia. Houve correlação significativa e positiva da velocidade da onda de pulso com pressão arterial sistólica, pressão arterial diastólica, pressão de pulso e pressão arterial média, índice de massa corporal, e LDL-colesterol e negativa com HDL-colesterol e adiponectina. Em modelo de regressão múltipla, após ajuste do HDL-colesterol, LDL-colesterol e adiponectina para sexo, idade, índice de massa corporal e pressão arterial média, apenas o sexo masculino e a pressão arterial média mantiveram correlação significativa com a velocidade de onda de pulso. CONCLUSÃO: A velocidade de onda de pulso em adultos jovens mostrou relação significativa com variáveis de risco cardiovascular, destacando-se o sexo masculino e a pressão arterial média como importantes variáveis no seu determinismo. Os achados sugerem que a medida da VOP pode ser útil para a

  3. A velocidade da onda de pulso em jovens: estudo do Rio de Janeiro La velocidad de la onda de pulso en jóvenes: estudio de Rio de Janeiro Pulse wave vocity in young adults: study of Rio de Janeiro

    Directory of Open Access Journals (Sweden)

    Oswaldo Luiz Pizzi

    2011-07-01

    la infancia y en la adolescencia, con la VOP. MÉTODOS: Sesenta individuos fueron seguidos longitudinalmente y estratificados en dos grupos según el percentil de la presión arterial (PA obtenido 13 años antes: Grupo 1(G1: percentil de la PA 95 (n = 35, 19M, 25,4 años. Fueron sometidos a evaluación clínica, análisis laboratorial y medidas de la VOP por el método Complior. RESULTADOS: G1 presentó un promedio mayor de edad; G2 mostró un promedio mayor de: peso, PA sistólica (PAS, PA diastólica (PAD, PA promedio (PAP, VOP y glucemia, y menor promedio de HDL-colesterol. La PAS, PAP y la frecuencia cardíaca (FC, obtenidas en la infancia y en la adolescencia presentaron una correlación significativa con la VOP. El peso, altura, cintura, relación cintura/cadera, PAS, PAD, la presión de pulso (PP, PAP y la creatinina actuales, presentaron una correlación positiva y significativa con la VOP. La comparación de los promedios de VOP ajustados por las PAS, PAD, PAS y PAD, PAP y PP no arrojó ninguna diferencia estadísticamente significativa entre los grupos. CONCLUSIÓN: El percentil de la PA en la infancia/adolescencia tuvo una relación con la distensibilidad arterial, evaluada por la VOP, 13 años después. Las alteraciones de la VOP pueden ser identificadas en individuos jóvenes, sugiriendo que el compromiso vascular en edad temprana, puede estar presente en esa franja etaria, relacionando también la presión arterial, las variables antropométricas y metabólicas.BACKGROUND: Pulse wave velocity (PWV can be a marker of cardiovascular impairment, but there are few studies in young adults. OBJECTIVE: To evaluate the association between blood pressure (BP, current anthropometric and metabolic variables and those obtained 13 years earlier, in childhood and adolescence, with PWV. METHODS: Sixty individuals were followed longitudinally and split into two groups according to the percentile of blood pressure (BP obtained 13 years earlier: Group 1 (G1: BP

  4. Estudo comparativo dos resultados da medição da amplitude articular do movimento de flexão do cotovelo através do goniómetro e observação visual

    OpenAIRE

    Coutinho, António; Santos, Sara

    2015-01-01

    Objectivos: Verificar se a experiência clínica na área da fisioterapia influencia o rigor de uma medição da amplitude articular no movimento de flexão do cotovelo utilizando o goniómetro universal e/ou a observação visual. Comparar o rigor destes dois métodos de medida de avaliação. Relevância: A integridade da amplitude do movimento de flexão do cotovelo é essencial para o desempenho normal de inúmeras actividades da vida diária. Neste sentido, existem diversos instrumentos de...

  5. Manejo intraparto del registro estresante no reactivo: un estudio randomizado controlado de oximetría de pulso (1)

    OpenAIRE

    Merino O,Paulina; Vera P-G,Claudio; Carvajal C,Jorge

    2004-01-01

    Objetivo: Evaluar si la adición de la oximetría de pulso a la evaluación fetal intraparto con cardiotocografía (CTG) y pH de cuero cabelludo, mejora la precisión del diagnóstico de la condición fetal, permitiendo una reducción segura del número de partos operatorios y de la necesidad de evaluación con pH de cuero cabelludo por sospecha de compromiso fetal. Métodos: Se realizó un estudio randomizado controlado en embarazadas de término en trabajo de parto activo y que tuvieran un monitoreo ele...

  6. Manejo intraparto del registro estresante no reactivo: un estudio randomizado controlado de oximetría de pulso (1)

    OpenAIRE

    2004-01-01

    Objetivo: Evaluar si la adición de la oximetría de pulso a la evaluación fetal intraparto con cardiotocografía (CTG) y pH de cuero cabelludo, mejora la precisión del diagnóstico de la condición fetal, permitiendo una reducción segura del número de partos operatorios y de la necesidad de evaluación con pH de cuero cabelludo por sospecha de compromiso fetal. Métodos: Se realizó un estudio randomizado controlado en embarazadas de término en trabajo de parto activo y que tuvieran un monitoreo ele...

  7. Avaliação das medidas de oximetria de pulso em indivíduos sadios com esmalte de unha Evaluación de las medidas de oximetría de pulso en individuos sanos con esmalte de uña Evaluation of pulse oximetry measurements in healthy subjects with nail polish

    Directory of Open Access Journals (Sweden)

    Solange Diccini

    2011-01-01

    Full Text Available OBJETIVO: Avaliar as alterações nas medidas da oximetria de pulso em indivíduos sadios com esmaltes de unha. MÉTODOS: Estudo transversal com 80 voluntárias sadias. As cores de esmalte utilizadas para avaliar a saturação periférica de oxigênio (SpO2 foram: café com leite, café, chocolate, vermelho e ameixa. Estas cores foram distribuídas entre as unhas dos dedos da mão esquerda. Os dedos da mão direita foram os controles. RESULTADOS: As cores vermelha (p=0,047 e café (p=0,024 mostraram valores menores na SpO2 quando comparados ao controle. As outras cores não alteraram a medida da SpO2. CONCLUSÃO: As cores vermelha e café causaram redução na medida da SpO2, porém a relevância clínica deste achado é questionável, pois os valores estavam dentro do intervalo de normalidade.OBJETIVO: Evaluar las alteraciones en las medidas de la oximetría de pulso en individuos sanos con esmalte de uña. MÉTODOS: Estudio transversal realizado con 80 voluntarias sanas. Los colores de esmalte utilizados para evaluar la saturación periférica de oxígeno (SpO2 fueron: café con leche, café, chocolate, rojo y ciruela. Estos colores fueron distribuidos entre las uñas de los dedos de la mano izquierda. Los dedos de la mano derecha fueron los controles. RESULTADOS: Los colores rojo (p=0,047 y café (p=0,024 mostraron valores menores en la SpO2 cuando fueron comparados al control. Los otros colores no alteraron la medida del SpO2. CONCLUSIÓN: Los colores rojo y café causaron reducción en la medida del SpO2, sin embargo la relevancia clínica de este hallazgo es cuestionable, pues los valores estaban dentro del intervalo de normalidad.OBJECTIVE: To evaluate the changes in measurements of pulse oximetry in healthy individuals with nail polish. METHODS: Cross sectional study with 80 healthy volunteers. The colors of enamel used to assess oxygen saturation (SpO2 were: coffee with milk, coffee, chocolate, red and plum. These colors were

  8. Valor da oximetria de pulso na avaliação da perfusão da mão para retirada da artéria radial: O teste de Allen é satisfatório?

    Directory of Open Access Journals (Sweden)

    Renato Bauab DAUAR

    1998-07-01

    Full Text Available Com o crescimento da utilização da artéria radial como enxerto em operações de revascularização tornou-se importante a avaliação fidedigna da integridade da arcada palmar em cada paciente a fim de se prevenir complicações vasculares da mão. Classicamente, utiliza-se para esta finalidade o teste de Allen, que é baseado em avaliação subjetiva da coloração da mão ao se comprimir os pulsos radial e ulnar e, portanto, mais sujeitos a erros de interpretação. Com a finalidade de avaliação objetiva, propusemos a realização do teste, analisando-se a perfusão através da oximetria de pulso, método simples e facilmente disponível em centro cirúrgico. Objetivo: Os autores apresentam uma nova proposta para avaliação da perfusão e integridade da arcada palmar com a utilização do oxímetro de pulso e comparam os dados obtidos por este método com os do teste de Allen. Método: Foram estudadas 50 artérias radiais, 50 artérias ulnares de 25 pacientes em decúbito dorsal, com idade igual ou superior a 45 anos, sendo 19 do sexo masculino e 6 do sexo feminino, em condições cardio-respiratórias estáveis e sem alterações vasculares periféricas conhecidas em membros superiores. O oxímetro utilizado foi o da marca Ohmeda, sendo o Doppler portátil de fluxo contínuo da Medical Eletronics. A princípio colocou-se o dedal do oxímetro no dedo indicador de cada mão anotando-se a saturação que chamamos de inicial. Verificou-se ao Doppler os pulsos radial e ulnar. Foi realizado o teste de Allen em cada mão comprimindo-se digitalmente ambas as artérias, com o oxímetro no 2º dedo e observando-se o desaparecimento da onda de pulso. Após isso, descomprimiu-se a artéria ulnar retornando a onda de pulso e medindo-se a saturação final. Houve queda de 0 a 2 pontos, no valor da saturação, em 96% dos casos. O Doppler foi utilizado distalmente à compressão da artéria radial mostrando não haver fluxo nesta artéria. Resultado

  9. Velocidad de la onda de pulso y la excreción urinaria de albumina en pacientes hipertensos tratados con Perindopril

    Directory of Open Access Journals (Sweden)

    J. E. Tobilli

    2002-12-01

    Full Text Available La presión arterial sistólica, la presión arterial diastólica y la excreción urinaria de albúmina (EUA han sido reconocidas como predictores de riesgo cardiovascular. Además, los trastornos de la compliance arterial (CA evaluados mediante la velocidad de la onda de pulso elevada (VOP están estrechamente relacionados con los cambios de la presión arterial y correlacionados con la mortalidad cardiovascular y la presencia de ateroesclerosis. El objetivo primario de este estudio ha sido determinar la relación entre la VOP y la EUA en un grupo de pacientes no fumadores con hipertensión esencial y secundariamente evaluar los cambios producidos por un inhibidor de la enzima convertidora de angiotensina (perindopril sobre estas dos variables. En el estudio participaron setenta pacientes (33 hombres y 37 mujeres hipertensos no fumadores, sin tratamiento previo, de 50 ± 7 años (entre 35-69. La VOP de todos los pacientes fue estudiada por medio de un dispositivo computarizado (Complior en el período basal y a los seis meses de tratamiento con perindopril. También se determinó la EUA por el método de inmunodifusión radial al inicio del tratamiento y luego de seis meses de tratamiento con perindopril (4.6 ± 1.4 mg/día. Al finalizar el estudio se observó una reducción significativa de la presión arterial sistólica (PAS (160.2 ± 10.6 vs. 131.9 ± 7.1 mmHg, p<0.01, presión arterial diastólica (PAD (100.6 ± 5 vs. 81.6 ± 4.8 mmHg, p<0.01, VOP (13.4 ± 1 vs. 9.1 ± 0.9 m/seg, p<0.01 y EUA (42.2 ± 19.3 vs.11.1 ± 3.6 mg/día, p<0.01 al comparar estos valores con los del período basal. Por otra parte, la función renal evaluada por clearance de creatinina mostró una significativa mejoría en relación a los valores iniciales (87.5 ± 22.5 vs. 102.1 ± 23.5 ml/min, p<0.01. Asimismo, se apreció una significativa correlación positiva entre la EUA y la VOP al inicio del estudio (r = 0.81; p<0.01 y después de seis meses de tratamiento

  10. Efeitos imediatos da mobilização com movimento na dor, Amplitude de movimento e actividade electromiográfica dos músculos da cintura escapular em indivíduos com síndrome do conflito subacromial

    OpenAIRE

    Patrício, Rita

    2013-01-01

    Introdução: A síndrome do conflito subacromial (SCSA) é a causa mais frequente de dor no ombro. Alterações na cinemática escapuloumeral e na activação dos músculos escapulares têm sido identificadas em pessoas com SCSA. A mobilização com movimento (MWM) é uma técnica de terapia manual, desenvolvida por Mulligan, que visa normalizar a cinemática articular. Objectivos: Determinar os efeitos imediatos da MWM na dor, na amplitude de movimento (ADM) de abdução no plano da escápula (APE), e na ampl...

  11. 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.

  12. AMPLITUDE FLUCTUATIONS IN CURVATURE SENSING: COMPARISON OF TWO SCHEMES

    Directory of Open Access Journals (Sweden)

    V. V. Voitsekhovich

    2010-01-01

    Full Text Available Se investiga la influencia de las uctuaciones en amplitud sobre la calidad de la reconstrución de fases en la medición de la curvatura. Se comparan los dos es- quemas: el que emplea dos imágenes simétricas fuera de foco (esquema de Roddier y el que emplea una sola (esquema de Hickson. Se demuestra que la precisión de la reconstrucción de fases con el esquema de Hickson se ve fuertemente afectada por uctuaciones en amplitud incluso leves, mientras que el esquema de Roddier funciona bien incluso con grandes uctuaciones en amplitud.

  13. La velocidad de la onda del pulso como método para evaluar la función endotelial

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    Eduardo J. Rusak

    2010-01-01

    Full Text Available RESUMENIntroducciónLa disfunción endotelial está presente precozmente en la aterosclerosis y constituye la basefisiopatológica de ella y de la enfermedad cardiovascular (CV. La función endotelial puedeestudiarse por ultrasonografía, que permite observar la vasodilatación mediada por flujo(VMF. También puede evaluarse por el cambio en la velocidad de la onda del pulso (VOP,que de acuerdo con la ecuación de Moens-Korteweg concuerda con los resultados obtenidospor otros métodos.ObjetivosInvestigar la función endotelial a través de las variaciones de la velocidad de la onda delpulso (VOP carótido-radial preinducción y posinducción de isquemia braquial.Material y métodosLa VOP carótido-radial se determinó en 248 pacientes hipertensos (160 mujeres, 63,6 ±12,3 años y 88 hombres, 63,1 ± 11,6 años y en 56 normotensos (38 mujeres, 63,1 ± 12,6años y 18 hombres, 56,1 ± 13,7 años. Se consideró respuesta endotelial normal la reducciónde la VOP > 5%. En pacientes con respuesta anormal se realizó la medición luego de laadministración de 5 mg de dinitrato de isosorbide sublingual con el objeto de registrar lavasodilatación no dependiente del endotelio como forma de validación del método.ResultadosLa VOP se redujo el 9,3% en promedio en el grupo de sujetos sanos, mientras que en lospacientes esta reducción fue de sólo el 1,5% (p < 0,0005. La reducción de la VOP condinitrato de isosorbide sublingual fue aún mayor que la de los individuos normales (18,2%(p < 0,0001.ConclusionesLa medición de la VOP carótido-radial preinducción y posinducción de isquemia discriminóel comportamiento endotelial entre personas normotensas e hipertensas. Este hallazgoconsolida su utilidad para la medición de la función endotelial.REV ARGENT CARDIOL 2010;78:17-22.

  14. Dos tiempos

    Directory of Open Access Journals (Sweden)

    Eduardo García Piedrahita

    1979-08-01

    Full Text Available Escena I: Un claro en la selva. En el fondo, un rancho de tierra y hojas. Suspendida de dos trozos de madera una hamaca. Troncos de árboles diseminados aquí y allá. Al lado de la puerta que da a la habitación, un fusil. Media tarde.

  15. Relación del síndrome metabólico y sus componentes con la presión del pulso en personas sin enfermedad aparente

    OpenAIRE

    Antonio J. Paragano; Rogelio Machado; Jorge Curotto Grasiosi; Suárez,Daniel H.; Diego J. Cordero; Diego Alasia; Matías Muglia; Emanuel Paragano; Antonio Abdala; Ricardo J. Esper

    2010-01-01

    RESUMENIntroducciónLa presión del pulso depende en gran medida de la rigidez arterial. Varios estudios se hancentrado en el hecho de que diversos factores, entre ellos el síndrome metabólico o suscomponentes, intermedian cambios que afectan en forma adversa las propiedades elásticasde las grandes arterias, acentuando su rigidez.ObjetivoEl propósito de este trabajo de investigación fue evaluar la influencia del síndrome metabólicoy sus componentes sobre la presión del pulso en personas sin enf...

  16. Relação da amplitude de distribuição do diâmetro dos eritrócitos (RDW com valores do eritrograma em gatos anêmicos e não anêmicos

    Directory of Open Access Journals (Sweden)

    Paulo Henrique da Silva

    2015-10-01

    Full Text Available As alterações eritrocitárias demandam decisões e norteiam a conduta do clínico quanto ao prognóstico e a terapêutica de eventuais doenças. A utilização de equipamentos automatizados que fazem a contagem celular sanguínea permite o cálculo da amplitude de distribuição dos eritrócitos (RDW- red blood cell distribution width e suas frações (RDW-CV e RDW-SD, para avaliar de forma quantitativa a heterogenicidade de cada eritrócito, em especial para a espécie felina, uma vez que é comum nestes animais a presença de anisocitose mesmo em condições normais. Ao contrário da medicina humana, em que ocorreu uma grande aceitação do RDW, na medicina veterinária ainda são poucos veterinários e laboratórios que utilizam esse parâmetro como ferramenta diagnóstica para diagnóstico diferencial laboratorial das anemias, o que pode ser devido ao desconhecimento de sua aplicação. Diante da escassa informação disponível na literatura científica sobre os valores de RDW para o gato doméstico, este estudo propôs associar os valores obtidos de RDW com os eritrócitos, hematócrito, hemoglobina e volume corpuscular médio (VCM, de 407 gatos (n=218 machos, n=189 fêmeas, sendo 335 não anêmicos e 72 anêmicos, adultos, sem raça definida. No presente estudo, os valores de RDW-SD dos gatos anêmicos aumentaram 20,4% em relação aos considerados normais, enquanto o RDWCV apresentou valores 25,2% superiores aos considerados normais para a espécie. Conclui-se que, a interpretação dos valores de RDW é uma ferramenta importante para avaliação da heterogenicidade das hemácias frente à anemia. Mesmo em animais não anêmicos, os valores aumentados de RDW podem sugerir uma alteração eritrocitária precoce.

  17. Real topological string amplitudes

    Science.gov (United States)

    Narain, K. S.; Piazzalunga, N.; Tanzini, A.

    2017-03-01

    We discuss the physical superstring correlation functions in type I theory (or equivalently type II with orientifold) that compute real topological string amplitudes. We consider the correlator corresponding to holomorphic derivative of the real topological amplitude G_{χ } , at fixed worldsheet Euler characteristic χ. This corresponds in the low-energy effective action to N=2 Weyl multiplet, appropriately reduced to the orientifold invariant part, and raised to the power g' = -χ + 1. We show that the physical string correlator gives precisely the holomorphic derivative of topological amplitude. Finally, we apply this method to the standard closed oriented case as well, and prove a similar statement for the topological amplitude F_g.

  18. Simulación de la propagación de pulsos ópticos en guías de ondas microestructuradas

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    Sonia Valbuena-Duarte

    2014-01-01

    Full Text Available Se estudia la propagación de pulsos ópticos por el método de diferencias finitas en guías de onda estructuradas tipo ridge para aplicaciones en sistemas de transmisión de óptica en la región de 1,55 μm. Con la transformación de las ecuaciones de Maxwell de su forma continua a una formulación discreta para el sistema en estudio y con las condiciones de contorno apropiadas se implementó un algoritmo en Matlab que permitió visualizar el comportamiento del pulso al propagarse en la geometría del guía ridge . Se realizaron simulaciones variando la longitud de onda, el ancho de la región del núcleo y el índice de refracción de los materiales obteniéndose resultados similares a los reportados en la literatura. Este estudio permite proponer una geometría apropiada y sugerir materiales para confeccionar este tipo de guía de onda para aplicaciones en sistemas de comunicaciones ópticas.

  19. Protostring scattering amplitudes

    Science.gov (United States)

    Thorn, Charles B.

    2016-11-01

    We calculate some tree-level scattering amplitudes for a generalization of the protostring, which is a novel string model implied by the simplest string bit models. These bit models produce a light-cone world sheet which supports s integer moded Grassmann fields. In the generalization we supplement this Grassmann world-sheet system with d =24 -s transverse coordinate world-sheet fields. The protostring corresponds to s =24 and the bosonic string to s =0 . The interaction vertex is a simple overlap with no operator insertions at the break/join point. Assuming that s is even we calculate the multistring scattering amplitudes by bosonizing the Grassmann fields, each pair equivalent to one compactified bosonic field, and applying Mandelstam's interacting string formalism to a system of s /2 compactified and d uncompactified bosonic world-sheet fields. We obtain all amplitudes for open strings with no oscillator excitations and for closed strings with no oscillator excitations and zero winding number. We then study in detail some simple special cases. Multistring processes with maximal helicity violation have much simpler amplitudes. We also specialize to general four-string amplitudes and discuss their high energy behavior. Most of these models are not covariant under the full Lorentz group O (d +1 ,1 ). The exceptions are the bosonic string whose Lorentz group is O (25 ,1 ) and the protostring whose Lorentz group is O (1 ,1 ). The models in between only enjoy an O (1 ,1 )×O (d ) spacetime symmetry.

  20. Protostring Scattering Amplitudes

    CERN Document Server

    Thorn, Charles B

    2016-01-01

    We calculate some tree level scattering amplitudes for a generalization of the protostring, which is a novel string model implied by the simplest string bit models. These bit models produce a lightcone worldsheet which supports $s$ integer moded Grassmann fields. In the generalization we supplement this Grassmann worldsheet system with $d=24-s$ transverse coordinate worldsheet fields. The protostring corresponds to $s=24$ and the bosonic string to $s=0$. The interaction vertex is a simple overlap with no operator insertions at the break/join point. Assuming that $s$ is even we calculate the multi-string scattering amplitudes by bosonizing the Grassmann fields, each pair equivalent to one compactified bosonic field, and applying Mandelstam's interacting string formalism to a system of $s/2$ compactified and $d$ uncompactified bosonic worldsheet fields. We obtain all amplitudes for open strings with no oscillator excitations and for closed strings with no oscillator excitations and zero winding number. We then ...

  1. Estimación de los parámetros de rendimiento para un rectificador controlado monofásico mediante la técnica PWM de múltiples pulsos

    Directory of Open Access Journals (Sweden)

    Mario Cruz Cruz

    2008-01-01

    Full Text Available En este artículo se presenta la aplicación de la técnica de modulación por ancho de pulso (PWM de múltiples pulsos para el control de un rectificador semicontrolado monofásico, que permite la estimación de los parámetros de rendimiento como son la eficiencia, el factor de forma, el factor de rizo y el factor de potencia. Para la implementación de la etapa de control se utilizaron amplificadores operacionales y un microcontrolador PIC16F84, mientras que la etapa de potencia consta de un arreglo de diodos y power MOSFETs. A partir de las pruebas realizadas en el rectificador con carga resistiva, se obtienen graficas comparativas de los parámetros evaluados para diferente número y ancho de los pulsos. Estos resultados pueden ser comparados con los obtenidos en la aplicación de la técnica tradicional de control por ángulo de fase, permitiendo de esta manera, comprobar que la técnica PWM de múltiples pulsos mejora los parámetros de rendimiento del rectificador.

  2. Estimación de la velocidad de propagación aórtica basada en el análisis de la onda de pulso radial

    National Research Council Canada - National Science Library

    Fernando Clara; Gustavo Blanco; Alfredo Casarini; Pablo Corral; Gustavo Meschino; Adriana Scandurra

    2011-01-01

    Se exploró la posibilidad de utilizar la morfología del registro de onda de pulso radial obtenida mediante un transductor de movimiento para evaluar la velocidad de propagación aórtica. Se efectuó...

  3. Estimación de la velocidad de propagación aórtica basada en el análisis de la onda de pulso radial Velocity estimation of aortic propagation based on radial pulse wave analysis

    National Research Council Canada - National Science Library

    Fernando Clara; Gustavo Blanco; Alfredo Casarini; Pablo Corral; Gustavo Meschino; Adriana Scandurra

    2011-01-01

    Se exploró la posibilidad de utilizar la morfología del registro de onda de pulso radial obtenida mediante un transductor de movimiento para evaluar la velocidad de propagación aórtica. Se efectuó...

  4. A course in amplitudes

    Science.gov (United States)

    Taylor, Tomasz R.

    2017-05-01

    This a pedagogical introduction to scattering amplitudes in gauge theories. It proceeds from Dirac equation and Weyl fermions to the two pivot points of current developments: the recursion relations of Britto, Cachazo, Feng and Witten, and the unitarity cut method pioneered by Bern, Dixon, Dunbar and Kosower. In ten lectures, it covers the basic elements of on-shell methods.

  5. Red Blood Cell Distribution Width (RDW in thorougbred horses from 12 to 24 months of age/ Valores da amplitude de distribuição do tamanho dos eritrócitos (RDW – Red Cell Distribution Width em equinos da raça puro sangue inglês (PSI de ambos os sexos de 12 a 24 meses de idade

    Directory of Open Access Journals (Sweden)

    Raimundo Souza Lopes

    2001-05-01

    Full Text Available The purpose of this study was to establish reference values for red blood cell distribution width (RDW in health horses. We obtained blood samples through jugular punctured from 90 clinicaly health thorougbred horses between 12 and 24 months of age. Blood was obtained in a Cell-Dyn 3500 (Abbott Diagnostic cell counter. Mean ± standart deviation values for RDW in male horses were 26,90 ± 1,41, whereas in females values were 26,89 ± 1,75. There were no differences in the RDW values between sexes, therefore, our reference values can be used in both males and females.O objetivo do presente estudo foi estabelecer valores da amplitude de distribuição do tamanho dos eritrócitos (RDW em eqüinos clinicamente sadios. Foram utilizadas 90 amostras de sangue de eqüinos da raça Puro Sangue Inglês (PSI, clinicamente sadios de 12 a 24 meses de idade, obtidas por venipunção jugular em tubos à vácuo contendo EDTA 10%. Posteriormente as amostras foram processadas no contador automático de células Cell-Dyn 3500 (Abbott Diagnostic. Os valores médios e o desvios-padrão para o RDW (% de machos foi de 26,90 ± 1,41 e para as fêmeas de 26,89 ± 1,75. Os resultados demonstram não haver diferenças nos valores de RDW para machos e fêmeas, podendo ser utilizados como referência para ambos os sexos.

  6. Influencia de los parámetros de procesados en micro-perforado con pulsos ultracortos Influence of processing parameters on micro-perforated with ultrashort pulses

    Directory of Open Access Journals (Sweden)

    S Ceballos P

    2011-12-01

    Full Text Available En este trabajo se emplearon pulsos láser ultracortos (110 fs, 1 kHz; hasta1.1 mJ/pulso para el micro-perforado de acero. El procesado con estos pulsos permitió obtener agujeros circulares, con medidas precisas y sin alteración mecánica ni química apreciable de las zonas adyacentes. Los agujeros se realizaron utilizando el sistema de trepanado óptico (Helical Drilling Optics,HDO de la empresa TGSW-Stuttgart, el cual permitió generar estructuras no sólo de gran profundidad sino además de diámetro variable, gracias a que se pudo variar hasta tres parámetros de proceso simultáneamente (velocidad de rotacion del haz, inclinación y descentrado del haz respecto del eje opticomientras se ejecutaba el procesado. En el presente trabajo se estudió principalmente la influencia de la longitud de onda del láser, en la geometría de las micro-perforaciones. Para ello se realizó la micro-perforación con pulsos láser con la longitud de onda fundamental (λ= 790nm y la del segundo armónico(λ= 395nm, se utilizó un conjunto específico de elementos ópticos para la HDO en cada caso y se compararon los resultados obtenidos lo cual arrojó que no hay ventajas notables al usar el segundo armónico. Se mencionan deficiencias en el dispositivo experimental que impidieron evaluar la influencia de la longitud de onda con total precisión.In this work, ultra short laser pulses (110 fs, 1 kHz; up to 1.1 mJ/pulse were used for micromachining steel samples. Processing with ultra-short laserpulses allowed achieving circular micro holes, with precise measurements and no signi cant chemical or mechanical disruption of adjacent areas. The heli-cal drilling optics system by TGSW-Stuttgart is used to generate the holes.This system allowed producing high aspect ratio and complex structures with variable diameter throughout the hole. To did this, up to three processing pa-rameters may be changed at the same time (beam rotation speed, angle and of the beam and

  7. Atividade elétrica dos músculos cervicais e amplitude de movimento da coluna cervical em indivíduos com e sem DTM Electrical activity of cervical muscles and range of movement of cervical column in individuals with and without DTM

    Directory of Open Access Journals (Sweden)

    Jovana de Moura Milanesi

    2011-12-01

    Full Text Available O objetivo da pesquisa foi avaliar a atividade elétrica e a dor à palpação dos músculos cervicais, a amplitude de movimento (ADM da coluna cervical e a relação entre atividade elétrica e ADM cervical em indivíduos com e sem desordem temporomandibular (DTM. Participaram do estudo 53 voluntários, sendo 24 com DTM e 29 sem, de ambos os gêneros, com 18 a 32 anos de idade. A DTM foi diagnosticada pelo critério de diagnóstico em pesquisa para DTM (Research Diagnostic Criteria for Temporomandibular Disorders. A eletromiografia dos músculos esternocleidomastoídeo (ECOM e trapézio superior foi realizada bilateralmente, na situação de repouso, com frequência de 2 KHz e filtro passa-faixa de 10-1000 Hz. As medidas de ADM de flexão, extensão, lateroflexão e rotação foram realizadas com um flexímetro e a comparação entre os grupos contou com o teste de Mann Whitney. O teste de Spearman foi aplicado para a correlação entre as variáveis, com nível de significância de 5%. Não foi verificada nenhuma diferença na ADM cervical entre os grupos. A atividade elétrica demonstrou-se significativamente maior nos músculos ECOM direito (p=0,0130, trapézio superior direito (p=0,0334 e esquerdo (p=0,0335 no grupo DTM em relação ao grupo controle. Não houve correlação significante entre atividade elétrica e ADM cervical. A dor nos músculos cervicais apresentou-se significativamente maior apenas no músculo ECOM direito (p=0,0055. Conclui-se que os grupos estudados registraram diferença na atividade elétrica dos músculos cervicais, sendo esta maior em indivíduos com DTM.The aim of the research was to evaluate the electrical activity and pain on palpation of the cervical muscles, the cervical range of motion (ROM and the relationship between electrical activity and ROM in individuals with and without temporomandibular disorder (TMD. Fifty three volunteers took part in the study, being 24 with TMD and 29 without, both genders

  8. Weak Boson Production Amplitude Zeros; Equalities of the Helicity Amplitudes

    CERN Document Server

    Mamedov, F

    2002-01-01

    We investigate the radiation amplitude zeros exhibited by many Standard Model amplitudes for triple weak gauge boson production processes. We show that $WZ\\gamma$ production amplitudes have especially rich structure in terms of zeros, these amplitudes have zeros originating from several different sources. It is also shown that TYPE I current null zone is the special case of the equality of the specific helicity amplitudes.

  9. Periods and Superstring Amplitudes

    CERN Document Server

    Stieberger, S

    2016-01-01

    Scattering amplitudes which describe the interaction of physical states play an important role in determining physical observables. In string theory the physical states are given by vibrations of open and closed strings and their interactions are described (at the leading order in perturbation theory) by a world-sheet given by the topology of a disk or sphere, respectively. Formally, for scattering of N strings this leads to N-3-dimensional iterated real integrals along the compactified real axis or N-3-dimensional complex sphere integrals, respectively. As a consequence the physical observables are described by periods on M_{0,N} - the moduli space of Riemann spheres of N ordered marked points. The mathematical structure of these string amplitudes share many recent advances in arithmetic algebraic geometry and number theory like multiple zeta values, single-valued multiple zeta values, Drinfeld, Deligne associators, Hopf algebra and Lie algebra structures related to Grothendiecks Galois theory. We review the...

  10. 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.

  11. Quantitative Seismic Amplitude Analysis

    OpenAIRE

    Dey, A. K.

    2011-01-01

    The Seismic Value Chain quantifies the cyclic interaction between seismic acquisition, imaging and reservoir characterization. Modern seismic innovation to address the global imbalance in hydrocarbon supply and demand requires such cyclic interaction of both feed-forward and feed-back processes. Currently, the seismic value chain paradigm is in a feed-forward mode. Modern seismic data now have the potential to yield the best images in terms of spatial resolution, amplitude accuracy, and incre...

  12. Wrist immobilization after carpal tunnel release: a prospective study Avaliação prospectiva da imobilização do pulso após descompressão cirúrgica do nervo mediano no túnel do carpo

    Directory of Open Access Journals (Sweden)

    Roberto S. Martins

    2006-09-01

    Full Text Available This prospective study evaluates the possible advantages of wrist imobilization after open carpal tunnel release comparing the results of two weeks immobilization and no immobilization. Fifty two patients with idiopathic carpal tunnel syndrome were randomly selected in two groups after open carpal tunnel release. In one group (A, n=26 the patients wore a neutral-position wrist splint continuosly for two weeks. In the other group (B, n=26 no wrist immobilization was used. Clinical assessment was done pre-operatively and at 2 weeks follow-up and included the two-point discrimination test at the second finger and two questionnaires as an outcome measurement of symptoms severity and intensity. All the patients presented improvement in the postoperative evaluations in the three analyzed parameters. There was no significant difference between the two groups for any of the outcome measurements at the final follow-up. We conclude that wrist immobilization in the immediate post-operative period have no advantages when compared with no immobilization in the end result of carpal tunnel release.Neste estudo prospectivo avaliamos se há vantagens na imobilização pós-operatória do pulso após a cirurgia para o tratamento da síndrome do túnel do carpo comparando este tratamento com a ausência de imobilização. Cinqüenta e dois pacientes portadores de síndrome do túnel do carpo idiopática foram randomizados em dois grupos após a cirurgia. Em um grupo (grupo A, n=26 os pacientes utilizaram uma tala em posição neutra para imobiliza��ão do pulso por duas semanas. No outro grupo (B, n=26, nenhum tipo de imobilização foi adotada. A avaliação foi realizada antes da cirurgia e repetida após duas semanas e incluiu a mensuração da sensibilidade discriminatória no segundo dedo e dois questionários que avaliaram a gravidade e intensidade dos sintomas. Em todos os pacientes houve melhora nos parâmetros avaliados. Não houve diferen

  13. Efeito do processo de desidratação osmótica a pulso de vácuo na transferência de massa e nas propriedades reológicas e de cor de fatias de manga Influence of pulsed vacuum osmotic dehydration on mass transfer, color and rheological properties of mango slices

    Directory of Open Access Journals (Sweden)

    Ana Paula Ito

    2007-08-01

    Full Text Available O presente trabalho teve como objetivo estudar as propriedades reológicas, de cor e a cinética do processo de desidratação osmótica, a pulso de vácuo, de fatias de manga. As fatias de manga foram imersas em soluções hipertônicas de sacarose, nas concentrações de 45, 55 e 65 ºBrix com temperatura controlada (20 e 30 ºC. No início do processo, aplicou-se ou não um pulso de vácuo, utilizando as pressões de 50 e 100 mbar por 10 minutos. As frutas foram desidratadas por 5 horas, sendo avaliadas em diferentes tempos em relação à perda de peso, perda de água, ganho de sólidos, a w, cor e propriedades reológicas (tensão e deformação na ruptura. O aumento da concentração e da temperatura da solução causou um aumento na perda de peso e de água enquanto que a incorporação de solutos foi favorecida em baixas concentrações e altas temperaturas e com a aplicação do pulso de vácuo. O amaciamento do produto, caracterizado pela diminuição da tensão máxima de ruptura, e o aumento da deformação na ruptura da amostra ocorreram nas condições de maior incorporação de solutos. Não houve alteração dos parâmetros de cor das mangas durante o processo de desidratação.The aim of this work was to study rheological and colour properties and process kinetics of mango slices subject to pulsed vacuum osmotic dehydration. The slices were immersed in osmotic sucrose solutions (45, 55 and 65 ºBrix at 20 or 30 ºC. At the beginning, a sub-atmospheric pressure was applied or not to the solid-liquid system (50 or 100 mbar of pressure for 10 minutes followed by an atmospheric pressure operation up to 5 hours. Fruit samples were evaluated after pre-determined times in terms of weight loss, water loss, solids gain, a w, colour and rheological properties (stress and strain at rupture. The concentration and temperature increases lead to a weight and water reduction. Solid gain was favoured by lower concentration and a higher

  14. Evaluación del comportamiento del intervalo desde el inicio del QRS al inicio de la onda de pulso radial y carotídeo con el resultado del tilt test

    Directory of Open Access Journals (Sweden)

    Alejandro M. Villamil

    2009-01-01

    Full Text Available RESUMENIntroducciónEl tilt test (TT es un método diagnóstico de rutina para evaluar la función autonómica depacientes con síncope. Debido a su tasa elevada de resultados falsos negativos y al tiempoque insume, el desarrollo de nuevas metodologías que puedan facilitar el diagnóstico haganado una importancia creciente. Un equipo desarrollado en la Argentina permitió estableceruna metodología confiable, reproducible y no invasiva para la medición de la velocidadde onda de pulso carotídeo y radial durante un TT convencional y determinar si tiene elpotencial de predecir precozmente el resultado de esta prueba.ObjetivoEvaluar la utilidad del retraso en la aparición de la onda de pulso desde el inicio del QRSpara predecir el resultado del tilt test.Material y métodosSe realizó un estudio observacional en pacientes consecutivos derivados para el estudio desíncope a través de la realización de un TT. Durante la prueba se registraron simultáneamentela presión arterial y la frecuencia cardíaca y la onda de pulso radial y carotídeo medianteun polígrafo diseñado especialmente. Se evaluó la capacidad del retraso en la aparición de la onda de pulso desde el inicio del QRS para predecir el resultado del TT medianteanálisis univariado y multivariado. La capacidad para predecir el resultado de la prueba seevaluó a través del análisis de curvas ROC.ResultadosSe incluyeron 43 pacientes, 24 (55,8% mujeres. El TT fue positivo en 18 pacientes (11mujeres. En el análisis univariado, el cambio de la presión arterial sistólica (p = 0,02 ydiastólica (p < 0,01 a los 10 minutos, el uso de IECA/ARA II (p = 0,01 y el retraso de laonda de pulso carotídeo (p < 0,01 estuvieron relacionados con el resultado del TT. En elanálisis multivariado, sólo el retraso del pulso carotídeo fue un predictor significativo delresultado (p = 0,036. El estadístico C del retraso del pulso carotídeo fue de 0,88 (IC 95%0,76 a 0,99.ConclusionesLa medición del

  15. Uso de la frecuencia del pulso en la estimación de la carga de trabajo Evaluación de una actividad de movilización de cargas

    OpenAIRE

    Castillo-Martínez, Juan A; Cubillos, Angela

    2014-01-01

    Introducción: la frecuencia del pulso es un indicador directo del estado del sistema cardiovascular, además de ser un indicador indirecto de la energía gastada en la ejecución de una tarea. El pulso de una persona es el número de pulsaciones registradas en una arteria periférica por unidad de tiempo, que se manifiesta como una onda de presión que se mueve a lo largo de los vasos sanguíneos, los cuales son flexibles. “En las grandes ramas arteriales, su velocidad es de 7 a 10 m/s y en las arte...

  16. Relación del pulso hidrológico con la estratigrafía del sedimento del complejo de humedales de Ayapel, Colombia

    Directory of Open Access Journals (Sweden)

    Alex Rúa

    2014-01-01

    Full Text Available El pulso hidrológico y la transferencia de masa entre los tributarios y humedales conectan los ambientes terrestres con los reotróficos. La interacción agua- sedimento en humedales de la sabana atlántica colombiana es prácticamente desconocida a escala multidecadal. Por esta razón, se realizaron tres correlaciones estratigráficas entre nueve perfiles de sedimento (13-30 cm del complejo de humedales de Ayapel (CHA que abarcaron ca. 110-600 a BP. Las correlaciones enmarcaron (i zonas de alta presión antrópica, (ii hidrodinámica principal y (iii aportes de materia orgánica (MO. El CHA se extiende 150 km2 de los cuales >84 % comprendió sedimento mineral óxico susceptible de diagénesis temprana. En contraste, el sedimento reducido en estratos anaerobios de algunos humedales menores indicó metanogénesis. La intensidad del pulso hidrológico se relacionó con el registro estratigráfico del rizoma de Eichhornia crassipes. Arena y grava sedimentaron bajo flujo turbulento cerca del tributario Quebradona, mientras el limo se cementó con arcilla en la zona léntica o con arena en caños de conexión. El viento sobre la lámina de agua somera favoreció la resuspensión y transporte del sedimento proveniente de los tributarios. Por esta razón, se propusieron tasas netas de sedimentación relativamente lentas en la boca de Quebradona (ca. 0,15 cm a-1, caños (ca. 0,1 cm a-1 y humedales temporales (ca. 0,05 cm a-1. Además se constató que el sedimento del CHA exportó los productos de degradación de MO a la cuenca baja del Río San Jorge y la atmósfera.

  17. Estimación de la velocidad de propagación aórtica basada en el análisis de la onda de pulso radial

    Directory of Open Access Journals (Sweden)

    Fernando Clara

    2011-06-01

    Full Text Available Se exploró la posibilidad de utilizar la morfología del registro de onda de pulso radial obtenida mediante un transductor de movimiento para evaluar la velocidad de propagación aórtica. Se efectuó el registro de onda de pulso en arteria radial mediante un transductor apoyado sobre la zona de palpación del pulso, sobre un conjunto de 167 voluntarios varones sanos normotensos de edades comprendidas entre la 2ª y la 7ª década. Se identificó en los registros la onda reflejada y se definió un coeficiente de velocidad como el cociente entre la talla del individuo y el tiempo transcurrido entre el máximo de la onda sistólica y el instante de llegada de dicha onda. Se halló que en los normotensos el coeficiente mencionado aumentó en forma lineal con la edad, en una proporción similar al aumento de velocidad de propagación aórtica medido con otros métodos. Se repitió el procedimiento en otro conjunto de 125 varones hipertensos sin otros factores de riesgo, de edades entre la 3ª y la 7ª década, hallándose valores similares a los normotensos solamente en la 3ª década, a partir de la cual se registró un incremento significativo de dicho índice. Tales hallazgos sustentan la factibilidad de utilizar tal tipo de registros para evaluar indirectamente la velocidad de propagación junto con el índice de aumentación, un parámetro habitualmente utilizado en el análisis de onda de pulso.

  18. Relación del síndrome metabólico y sus componentes con la presión del pulso en personas sin enfermedad aparente

    Directory of Open Access Journals (Sweden)

    Antonio J. Paragano

    2010-01-01

    Full Text Available RESUMENIntroducciónLa presión del pulso depende en gran medida de la rigidez arterial. Varios estudios se hancentrado en el hecho de que diversos factores, entre ellos el síndrome metabólico o suscomponentes, intermedian cambios que afectan en forma adversa las propiedades elásticasde las grandes arterias, acentuando su rigidez.ObjetivoEl propósito de este trabajo de investigación fue evaluar la influencia del síndrome metabólicoy sus componentes sobre la presión del pulso en personas sin enfermedad aparente.Material y métodosSe seleccionaron al azar 1.155 individuos sin enfermedad demostrable. Se registraron lasvariables que definen el síndrome metabólico (ATP III: en mg/dl y en ayunas, colesterolHDL ≤ 40/50 (hombres/mujeres, triglicéridos ≥ 150, glucemia ≥ 100, perímetro de la cintura(cm ≥ 102/88 (hombres/mujeres y presión arterial sistólica/diastólica ≥ 130/85 mm Hg.Se compararon los valores de la presión del pulso obtenidos al agrupar a los participantespor sexo y edad. Se estableció la frecuencia de los factores que definen el síndrome metabólicoy mediante regresión lineal se ajustó la presión del pulso por sexo, edad y por el conjunto deellos. A continuación se determinó el valor ajustado de la presión del pulso correspondientea cada factor del síndrome metabólico y se comparó con el de sujetos normales. Finalmente,se calculó la presión del pulso ajustada de acuerdo con las posibles combinaciones de tres omás factores (criterio diagnóstico de síndrome metabólico y se comparó con la de individuosen los que no se hallaba presente ningún componente del síndrome.ResultadosCaracterísticas generales de los 1.155 individuos: hombres 62%, edad 38 ± 9 años (rango20-66, perímetro de la cintura 89 ± 13 cm, triglicéridos 107 ± 74 mg/dl, glucemia 82 ± 16mg/dl, colesterol HDL 48 ± 13 mg/dl, presión arterial sistólica 124 ± 14 mm Hg, diastólica78 ± 9 mm Hg, presión del pulso 46 ± 9 mm Hg

  19. Análisis de la estabilidad de un convertidor buck multicelular de dos celdas

    Directory of Open Access Journals (Sweden)

    Julián Pelaéz

    2014-12-01

    Full Text Available En este trabajo se presenta un convertidor multicelular con dos células bajo un modo de modulación (PWM de control de voltaje por ancho de pulso. El convertidor buck multicelular obtenido puede ser utilizado como un circuito electrónico de potencia para aplicaciones de alta tensión; donde los dispositivos semiconductores tienen la capacidad de cambiar solo a niveles de bajo voltaje. El análisis de estabilidad se ha hecho para un control puramente proporcional y más tarde, se ha extendido para un control Proporcional-Integral (PI. Los resultados de la simulación demuestran la validez del análisis.

  20. PULSE AMPLITUDE DISTRIBUTION RECORDER

    Science.gov (United States)

    Cowper, G.

    1958-08-12

    A device is described for automatica1ly recording pulse annplitude distribution received from a counter. The novelty of the device consists of the over-all arrangement of conventional circuit elements to provide an easy to read permanent record of the pulse amplitude distribution during a certain time period. In the device a pulse analyzer separates the pulses according to annplitude into several channels. A scaler in each channel counts the pulses and operates a pen marker positioned over a drivable recorder sheet. Since the scalers in each channel have the sanne capacity, the control circuitry permits counting of the incoming pulses until one scaler reaches capacity, whereupon the input is removed and an internal oscillator supplies the necessary pulses to fill up the other scalers. Movement of the chart sheet is initiated wben the first scaler reaches capacity to thereby give a series of marks at spacings proportional to the time required to fill the remaining scalers, and accessory equipment marks calibration points on the recorder sheet to facilitate direct reading of the number of external pulses supplied to each scaler.

  1. CHY formula and MHV amplitudes

    CERN Document Server

    Du, Yi-jian; Wu, Yong-shi

    2016-01-01

    In this paper, we study the relation between the Cachazo-He-Yuan (CHY) formula and the maximal-helicity-violating (MHV) amplitudes of Yang-Mills and gravity in four dimensions. We prove that only one special rational solution of the scattering equations found by Weinzierl support the MHV amplitudes. Namely, localized at this solution, the integrated CHY formula reproduces the Parke-Taylor formula for Yang-Mills amplitudes as well as the Hodges formula for gravitational amplitudes. This is achieved by developing techniques, in a manifestly M\\"obius covariant formalism, to explicitly compute relevant reduced Pfaffians/determinants. We observe and prove two interesting properties (or identities), which facilitate the computations. We also check that all the other $(n-3)!-1$ solutions to the scattering equations do not support the MHV amplitudes, and prove analytically that this is indeed true for the other special rational solution proposed by Weinzierl, that actually supports the anti-MHV amplitudes.

  2. Amplitude dependent closest tune approach

    CERN Document Server

    Tomas Garcia, Rogelio; Franchi, Andrea; Maclean, Ewen Hamish; CERN. Geneva. ATS Department

    2016-01-01

    Recent observations in the LHC point to the existence of an amplitude dependent closest tune approach. However this dynamical behavior and its underlying mechanism remain unknown. This effect is highly relevant for the LHC as an unexpectedly closest tune approach varying with amplitude modifies the frequency content of the beam and, hence, the Landau damping. Furthermore the single particle stability would also be affected by this effect as it would modify how particles with varying amplitudes approach and cross resonances. We present analytic derivations that lead to a mechanism generating an amplitude dependent closest tune approach.

  3. Graviton amplitudes from collinear limits of gauge amplitudes

    Energy Technology Data Exchange (ETDEWEB)

    Stieberger, Stephan, E-mail: stephan.stieberger@mpp.mpg.de [Max-Planck-Institut für Physik, Werner-Heisenberg-Institut, 80805 München (Germany); Taylor, Tomasz R. [Department of Physics, Northeastern University, Boston, MA 02115 (United States)

    2015-05-11

    We express all tree-level graviton amplitudes in Einstein's gravity as the collinear limits of a linear combination of pure Yang–Mills amplitudes in which each graviton is represented by two gauge bosons, each of them carrying exactly one half of graviton's momentum and helicity.

  4. On the Period-Amplitude and Amplitude-Period Relationships

    Science.gov (United States)

    Wilson, Robert M.; Hathaway, David H.

    2008-01-01

    Examined are Period-Amplitude and Amplitude-Period relationships based on the cyclic behavior of the 12-month moving averages of monthly mean sunspot numbers for cycles 0.23, both in terms of Fisher's exact tests for 2x2 contingency tables and linear regression analyses. Concerning the Period-Amplitude relationship (same cycle), because cycle 23's maximum amplitude is known to be 120.8, the inferred regressions (90-percent prediction intervals) suggest that its period will be 131 +/- 24 months (using all cycles) or 131 +/- 18 months (ignoring cycles 2 and 4, which have the extremes of period, 108 and 164 months, respectively). Because cycle 23 has already persisted for 142 months (May 1996 through February 2008), based on the latter prediction, it should end before September 2008. Concerning the Amplitude-Period relationship (following cycle maximum amplitude versus preceding cycle period), because cycle 23's period is known to be at least 142 months, the inferred regressions (90-percent prediction intervals) suggest that cycle 24's maximum amplitude will be about less than or equal to 96.1 +/- 55.0 (using all cycle pairs) or less than or equal to 91.0 +/- 36.7 (ignoring statistical outlier cycle pairs). Hence, cycle 24's maximum amplitude is expected to be less than 151, perhaps even less than 128, unless cycle pair 23/24 proves to be a statistical outlier.

  5. 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 + ...

  6. Closed string amplitudes as single-valued open string amplitudes

    Energy Technology Data Exchange (ETDEWEB)

    Stieberger, Stephan, E-mail: stephan.stieberger@mpp.mpg.de [Max-Planck-Institut für Physik, Werner-Heisenberg-Institut, 80805 München (Germany); Taylor, Tomasz R. [Department of Physics, Northeastern University, Boston, MA 02115 (United States)

    2014-04-15

    We show that the single trace heterotic N-point tree-level gauge amplitude A{sub N}{sup HET} can be obtained from the corresponding type I amplitude A{sub N}{sup I} by the single-valued (sv) projection: A{sub N}{sup HET}=sv(A{sub N}{sup I}). This projection maps multiple zeta values to single-valued multiple zeta values. The latter represent a subclass of multiple zeta values originating from single-valued multiple polylogarithms at unity. Similar relations between open and closed string amplitudes or amplitudes of different string vacua can be established. As a consequence the α{sup ′}-expansion of a closed string amplitude is dictated by that of the corresponding open string amplitude. The combination of single-valued projections, Kawai–Lewellen–Tye relations and Mellin correspondence reveal a unity of all tree-level open and closed superstring amplitudes together with the maximally supersymmetric Yang–Mills and supergravity theories.

  7. Correlación entre la oximetría de pulso y la gasometría arterial en el paciente de alto riesgo

    Directory of Open Access Journals (Sweden)

    Blas Hernández Suárez

    1998-09-01

    Full Text Available Se realiza un análisis del valor de la saturación arterial de la hemoglobina, en un estudio prospectivo de 20 pacientes pediátricos programados para corregir su defecto anatómico cardiovascular, a los cuales se les realizaron 20 tomas de muestra para gasometría arterial y monitoreo continuo con oxímetro de pulso. Se hace además, una reseña histórica sobre saturometría transcutánea; se relacionan las características técnicas de los equipos utilizados. Se analizan los datos obtenidos, los cuales son comparados y se concluye en que las mediciones de saturometría transcutánea es un gran paso de avance en el monitoreo respiratorio y hemodinámico en el paciente de alto riesgo al que se le efectúa cirugía, además lo no invasivo lo hace la mejor y más económica elección en los quirófanos.An analysis of the value of the arterial saturation of hemoglobin was carried out in a prospective study of 20 pediatric patients, programmed to correct their cardiovascular anatomic defect; 20 samples were taken from them for blood gas analysis, and a continuous monitoring with a pulse oxymeter was ordered. Also a short story about percutaneous saturation measuring, is made; the technical characteristics of the equipment used, are listed. The data obtained are analyzed and compared, and it is concluded that the percutaneous saturation measurements are a great advancement in the respiratory and hemodynamical monitoring of the high risk patient to whom surgery is done; also, its non-invasive characteristics makes it the best and most economic choice in the operating room.

  8. 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 ...

  9. Positive Amplitudes In The Amplituhedron

    CERN Document Server

    Arkani-Hamed, Nima; Trnka, Jaroslav

    2014-01-01

    The all-loop integrand for scattering amplitudes in planar N = 4 SYM is determined by an "amplitude form" with logarithmic singularities on the boundary of the amplituhedron. In this note we provide strong evidence for a new striking property of the superamplitude, which we conjecture to be true to all loop orders: the amplitude form is positive when evaluated inside the amplituhedron. The statement is sensibly formulated thanks to the natural "bosonization" of the superamplitude associated with the amplituhedron geometry. However this positivity is not manifest in any of the current approaches to scattering amplitudes, and in particular not in the cellulations of the amplituhedron related to on-shell diagrams and the positive grassmannian. The surprising positivity of the form suggests the existence of a "dual amplituhedron" formulation where this feature would be made obvious. We also suggest that the positivity is associated with an extended picture of amplituhedron geometry, with the amplituhedron sitting...

  10. Model selection for amplitude analysis

    CERN Document Server

    Guegan, Baptiste; Stevens, Justin; Williams, Mike

    2015-01-01

    Model complexity in amplitude analyses is often a priori under-constrained since the underlying theory permits a large number of amplitudes to contribute to most physical processes. The use of an overly complex model results in reduced predictive power and worse resolution on unknown parameters of interest. Therefore, it is common to reduce the complexity by removing from consideration some subset of the allowed amplitudes. This paper studies a data-driven method for limiting model complexity through regularization during regression in the context of a multivariate (Dalitz-plot) analysis. The regularization technique applied greatly improves the performance. A method is also proposed for obtaining the significance of a resonance in a multivariate amplitude analysis.

  11. Influência do pulso de inundação na fenologia foliar e conteúdo de clorofila em duas espécies da floresta de Igapó da Amazônia Central, Brasil

    OpenAIRE

    ΜΑΙΑ,Lúcia Alencar; Piedade, Maria Teresa F.

    2002-01-01

    Com o objetivo de verificar a influência da dinâmica do pulso de inundação na fenologia foliar e conteúdo de clorofilas a, b e total, 15 indivíduos adultos de duas espécies típicas das cotas mais baixas da floresta de igapó, Eschweilera tenuifolia e Hevea spruceana, foram estudados no baixo curso do rio Tarumã-Mirim, Amazonas, Brasil. A fenologia foliar foi acompanhada em observações semanais de campo de julho de 1993 a dezembro de 1...

  12. O Índice de Perfusão da Oximetria de Pulso na Avaliação da Função Endotelial na Aterosclerose

    Directory of Open Access Journals (Sweden)

    Igor Alexandre Côrtes de Menezes

    2014-04-01

    Full Text Available Fundamento: A disfunção endotelial se caracteriza por um fenômeno vascular, com importância evidente em todos os processos da aterogênese. Interessa, assim, a busca por métodos de avaliação da disfunção endotelial mais acurados, práticos e menos dispendiosos, objetivando melhoria na prevenção e tratamento das doenças ateroscleróticas. Objetivo: Verificar o potencial do índice de perfusão derivado da oximetria de pulso (IPP como método de avaliação da disfunção endotelial em pacientes portadores de aterosclerose Métodos: Foram selecionados 18 pacientes controles e 24 pacientes portadores de doenças ateroscleróticas, em tratamento otimizado, selecionados em Unidades Básicas de Saúde. Foram avaliados os valores do IPP antes a após a aplicação de um estímulo vasodilatador dependente do endotélio - a hiperemia reativa. Também foram analisados os valores do IPP especificamente no período que possui a maior contribuição do óxido nítrico para a vasodilatação (IPP90-120. Os resultados do IPP foram discutidos, por meio da literatura, estimando o seu potencial diagnóstico e prognóstico. Resultados: A resposta vasodilatadora dependente do endotélio mensurada pelo IPP foi significantemente menor em indivíduos com aterosclerose em comparação aos controles a partir de 45 segundos após a hiperemia reativa. Foram observados, do mesmo modo, valores menores do IPP90-120 em pacientes com aterosclerose [35% (4% - 53% vs. 73% (55% - 169%; p < 0,001]. Tais valores se mantiveram menores tanto em indivíduos masculinos quanto femininos. Conclusões: Os resultados do IPP, demonstrados na avaliação de pacientes ateroscleróticos, associados ao baixo custo da aparelhagem, tornam esse método atraente para futuros ensaios e possível contribuição na prevenção e tratamento das doenças ateroscleróticas.

  13. Computing Maximally Supersymmetric Scattering Amplitudes

    Science.gov (United States)

    Stankowicz, James Michael, Jr.

    This dissertation reviews work in computing N = 4 super-Yang--Mills (sYM) and N = 8 maximally supersymmetric gravity (mSUGRA) scattering amplitudes in D = 4 spacetime dimensions in novel ways. After a brief introduction and overview in Ch. 1, the various techniques used to construct amplitudes in the remainder of the dissertation are discussed in Ch. 2. This includes several new concepts such as d log and pure integrand bases, as well as how to construct the amplitude using exactly one kinematic point where it vanishes. Also included in this chapter is an outline of the Mathematica package on shell diagrams and numerics.m (osdn) that was developed for the computations herein. The rest of the dissertation is devoted to explicit examples. In Ch. 3, the starting point is tree-level sYM amplitudes that have integral representations with residues that obey amplitude relations. These residues are shown to have corresponding residue numerators that allow a double copy prescription that results in mSUGRA residues. In Ch. 4, the two-loop four-point sYM amplitude is constructed in several ways, showcasing many of the techniques of Ch. 2; this includes an example of how to use osdn. The two-loop five-point amplitude is also presented in a pure integrand representation with comments on how it was constructed from one homogeneous cut of the amplitude. On-going work on the two-loop n-point amplitude is presented at the end of Ch. 4. In Ch. 5, the three-loop four-point amplitude is presented in the d log representation and in the pure integrand representation. In Ch. 6, there are several examples of four- through seven-loop planar diagrams that illustrate how considerations of the singularity structure of the amplitude underpin dual-conformal invariance. Taken with the previous examples, this is additional evidence that the structure known to exist in the planar sector extends to the full theory. At the end of this chapter is a proof that all mSUGRA amplitudes have a pole at

  14. Scattering Amplitudes in Gauge Theories

    CERN Document Server

    Schubert, Ulrich

    2014-01-01

    This thesis is focused on the development of new mathematical methods for computing multi-loop scattering amplitudes in gauge theories. In this work we combine, for the first time, the unitarity-based construction for integrands, and the recently introduced integrand-reduction through multivariate polynomial division. After discussing the generic features of this novel reduction algorithm, we will apply it to the one- and two-loop five-point amplitudes in ${\\cal N}=4$ sYM. The integrands of the multiple-cuts are generated from products of tree-level amplitudes within the super-amplitudes formalism. The corresponding expressions will be used for the analytic reconstruction of the polynomial residues. Their parametric form is known a priori, as derived by means of successive polynomial divisions using the Gr\\"obner basis associated to the on-shell denominators. The integrand reduction method will be exploited to investigate the color-kinematic duality for multi-loop ${\\cal N}=4$ sYM scattering amplitudes. Our a...

  15. Effects of manual chest compression and descompression maneuver on lung volumes, capnography and pulse oximetry in patients receiving mechanical ventilation Efeitos da manobra de compressão e descompressão torácica nos volumes pulmonares, capnografia e oximetria de pulso em pacientes submetidos à ventilação mecânica

    Directory of Open Access Journals (Sweden)

    Fabiana Della Via

    2012-10-01

    Full Text Available OBJECTIVES: The aims of this study were to evaluate whether there are changes in lung volumes, capnography, pulse oximetry and hemodynamic parameters associated with manual chest compression-decompression maneuver (MCCD in patients undergoing mechanical ventilation (MV. Method: A prospective study of 65 patients undergoing to MV after 24 hours. All patients received bronchial hygiene maneuvers and after 30 minutes they were submitted to ten repetitions of the MCCD during 10 consecutive respiratory cycles in the right hemithorax and than in the left hemithorax. The data were collected before the application of the maneuver and after 1, 5, 10, 15, 20, 25, 30, 35 and 40 minutes following application of the maneuver. RESULTS: There were statistical significant (pOBJETIVOS: Avaliar a presença de alterações nos volumes pulmonares, oximetria de pulso, capnografia e alterações hemodinâmicas associadas à intervenção da manobra de compressão e descompressão torácica (MCDT nos pacientes submetidos à ventilação mecânica (VM. Método: Tratou-se de um estudo prospectivo em que foram incluídos 65 pacientes em VM há mais de 24 horas. O protocolo consistiu na aplicação de manobras de higiene brônquica e, após 30 minutos, os pacientes eram submetidos a dez repetições da MCDT em dez respirações consecutivas no hemitórax direito e, posteriormente, no hemitórax esquerdo, coletando os dados antes e após a aplicação da manobra nos tempos 1, 5, 10, 15, 20, 25, 30, 35 e 40 minutos. RESULTADOS: Constatou-se aumento significante (p<0,001 do volume corrente inspiratório (pré: 458,2±132,1 ml; pós 1 minuto: 557,3±139,1; pós 40 minutos: 574,4±151, volume minuto corrente (pré: 7,0±2,7 L/min; pós 1 minuto: 8,7±3,3; pós 40 minutos: 8,8±3,8 e oximetria de pulso (pré: 97,4±2,2%; pós 1 minuto: 97,9±1,8; pós 40 minutos: 98,2±1,6; p<0,05. Ocorreu redução no CO2 expirado (pré: 35,1±9,0 mmHg; pós 1 minuto: 31,5±8,2; pós 40

  16. Factorization of Chiral String Amplitudes

    CERN Document Server

    Huang, Yu-tin; Yuan, Ellis Ye

    2016-01-01

    We re-examine a closed-string model defined by altering the boundary conditions for one handedness of two-dimensional propagators in otherwise-standard string theory. We evaluate the amplitudes using Kawai-Lewellen-Tye factorization into open-string amplitudes. The only modification to standard string theory is effectively that the spacetime Minkowski metric changes overall sign in one open-string factor. This cancels all but a finite number of states: As found in earlier approaches, with enough supersymmetry (e.g., type II) the tree amplitudes reproduce those of the massless truncation of ordinary string theory. However, we now find for the other cases that additional fields, formerly thought to be auxiliary, describe new spin-2 states at the two adjacent mass levels (tachyonic and tardyonic). The tachyon is always a ghost, but can be avoided in the heterotic case.

  17. Factorization of chiral string amplitudes

    Science.gov (United States)

    Huang, Yu-tin; Siegel, Warren; Yuan, Ellis Ye

    2016-09-01

    We re-examine a closed-string model defined by altering the boundary conditions for one handedness of two-dimensional propagators in otherwise-standard string theory. We evaluate the amplitudes using Kawai-Lewellen-Tye factorization into open-string amplitudes. The only modification to standard string theory is effectively that the spacetime Minkowski metric changes overall sign in one open-string factor. This cancels all but a finite number of states: as found in earlier approaches, with enough supersymmetry (e.g., type II) the tree amplitudes reproduce those of the massless truncation of ordinary string theory. However, we now find for the other cases that additional fields, formerly thought to be auxiliary, describe new spin-2 states at the two adjacent mass levels (tachyonic and tardyonic). The tachyon is always a ghost, but can be avoided in the heterotic case.

  18. 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.

  19. 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.

  20. Employing Helicity Amplitudes for Resummation

    CERN Document Server

    Moult, Ian; Tackmann, Frank J; Waalewijn, Wouter 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 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 m...

  1. Scattering amplitudes in gauge theories

    Energy Technology Data Exchange (ETDEWEB)

    Henn, Johannes M. [Institute for Advanced Study, Princeton, NJ (United States). School of Natural Sciences; Plefka, Jan C. [Humboldt-Universitaet, Berlin (Germany). Inst. fuer Physik

    2014-03-01

    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.

  2. 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 dire

  3. Extracting amplitudes from photoproduction data

    Science.gov (United States)

    Workman, R. L.

    2011-09-01

    We consider the problems associated with amplitude extraction, from meson photoproduction data, over the first resonance regions. The notion of a complete experiment has motivated the FROST program at Jefferson Lab. Exercises applied to pion photoproduction data illustrate the problems to be confronted in any attempt to extract underlying resonance signals from these data (without introducing a model for the resonant process).

  4. Lista dos estoicos antigos

    Directory of Open Access Journals (Sweden)

    Luís Márcio Fontes

    2016-03-01

    Full Text Available Lista dos antigos estoicos confeccionada nos seminários Viva Vox por Luís Márcio Fontes e Aldo Dinucci. Apresentada em formato banner, para fins didáticos, com o estabelecimento dos nomes de filósofos e personagens históricos antigos.

  5. Validade de um monitor digital de pulso para mensuração de pressão arterial em comparação com um esfigmomanômetro de mercúrio Validity of a wrist digital monitor for blood pressure measurement in comparison to a mercury sphygmomanometer

    Directory of Open Access Journals (Sweden)

    Ana M. B. Menezes

    2010-03-01

    Full Text Available FUNDAMENTO: Medidas válidas da pressão arterial, em situações clínicas e na comunidade, são essenciais para a monitoração dessa variável em nível populacional. OBJETIVO: Avaliar a validade de um monitor digital de pulso para mensuração da pressão arterial em adolescentes, em comparação com um esfigmomanômetro de mercúrio. MÉTODOS: Um estudo de validação foi realizado na cidade de Pelotas, região sul do Brasil. A pressão arterial foi medida duas vezes, utilizando-se dois esfigmomanômetros diferentes: um aparelho digital de pulso OMRON e um aparelho de mesa BD de mercúrio. Metade da amostra foi medida primeiro através do manômetro digital e depois pelo de mercúrio, enquanto a outra metade foi avaliada na ordem inversa. A concordância entre as duas medidas foi avaliada através do método de Bland & Altman. RESULTADOS: 120 adolescentes com idade entre 14 e 15 anos foram incluídos no estudo (50% de cada sexo. A pressão sistólica média entre os meninos foi de 113,7 mmHg (DP 14,2 usando o manômetro de mercúrio e 115,5 mmHg (DP 15,2 usando o aparelho digital. Os valores equivalentes para a pressão diastólica foram 61,5 mmHg (DP 9,9 e 69,6 mmHg (10,2, respectivamente. Entre as meninas, a pressão sistólica média foi de 104,7 mmHg (DP 10,1 usando o manômetro de mercúrio e 102,4 mmHg (DP 11.9 usando o aparelho digital. Os valores equivalentes para a pressão diastólica foram 60,0 mmHg (DP 10,4 e 65,7 mmHg (DP 7,7, respectivamente. CONCLUSÕES: O manômetro digital apresentou alta concordância com o manômetro de mercúrio para medir a pressão arterial sistólica. A concordância foi menor para a pressão arterial diastólica. O uso de equações de correção pode ser uma alternativa para estudos utilizando esse monitor digital de pulso em adolescentes.BACKGROUND: Valid measurements of blood pressure, both at clinical and community settings, are essential for monitoring this variable at the population level

  6. Gauge and Gravity Amplitude Relations

    CERN Document Server

    Carrasco, John Joseph M

    2015-01-01

    In these lectures I talk about simplifications and universalities found in scattering amplitudes for gauge and gravity theories. In contrast to Ward identities, which are understood to arise from familiar symmetries of the classical action, these structures are currently only understood in terms of graphical organizational principles, such as the gauge-theoretic color-kinematics duality and the gravitational double-copy structure, for local representations of multi-loop S-matrix elements. These graphical principles make manifest new relationships in and between gauge and gravity scattering amplitudes. My lectures will focus on arriving at such graphical organizations for generic theories with examples presented from maximal supersymmetry, and their use in unitarity-based multi-loop integrand construction.

  7. High Amplitude Secondary Mass Drive

    Energy Technology Data Exchange (ETDEWEB)

    DYCK,CHRISTOPHER WILLIAM; ALLEN,JAMES J.; HUBER,ROBERT JOHN; SNIEGOWSKI,JEFFRY J.

    2000-07-06

    In this paper we describe a high amplitude electrostatic drive for surface micromachined mechanical oscillators that may be suitable for vibratory gyroscopes. It is an advanced design of a previously reported dual mass oscillator (Dyck, et. al., 1999). The structure is a 2 degree-of-freedom, parallel-plate driven motion amplifier, termed the secondary mass drive oscillator (SMD oscillator). During each cycle the device contacts the drive plates, generating large electrostatic forces. Peak-to-peak amplitudes of 54 {micro}m have been obtained by operating the structure in air with an applied voltage of 11 V. We describe the structure, present the analysis and design equations, and show recent results that have been obtained, including frequency response data, power dissipation, and out-of- plane motion.

  8. Infrared singularities in QCD amplitudes

    CERN Document Server

    Gardi, Einan

    2009-01-01

    We review recent progress in determining the infrared singularity structure of on-shell scattering amplitudes in massless gauge theories. We present a simple ansatz where soft singularities of any scattering amplitude of massless partons, to any loop order, are written as a sum over colour dipoles, governed by the cusp anomalous dimension. We explain how this formula was obtained, as the simplest solution to a newly-derived set of equations constraining the singularity structure to all orders. We emphasize the physical ideas underlying this derivation: the factorization of soft and collinear modes, the special properties of soft gluon interactions, and the notion of the cusp anomaly. Finally, we briefly discuss potential multi-loop contributions going beyond the sum-over-dipoles formula, which cannot be excluded at present.

  9. Pulse amplitude modulated chlorophyll fluorometer

    Energy Technology Data Exchange (ETDEWEB)

    Greenbaum, Elias; Wu, Jie

    2015-12-29

    Chlorophyll fluorometry may be used for detecting toxins in a sample because of changes in micro algae. A portable lab on a chip ("LOAC") based chlorophyll fluorometer may be used for toxin detection and environmental monitoring. In particular, the system may include a microfluidic pulse amplitude modulated ("PAM") chlorophyll fluorometer. The LOAC PAM chlorophyll fluorometer may analyze microalgae and cyanobacteria that grow naturally in source drinking water.

  10. All-Multiplicity Amplitudes with Massive Scalars

    CERN Document Server

    Forde, D; Forde, Darren; Kosower, David A.

    2005-01-01

    We compute two infinite series of tree-level amplitudes with a massive scalar pair and an arbitrary number of gluons. We provide results for amplitudes where all gluons have identical helicity, and amplitudes with one gluon of opposite helicity. These amplitudes are useful for unitarity-based one-loop calculations in nonsupersymmetric gauge theories generally, and QCD in particular.

  11. Crisis in Amplitude Control Hides in Multistability

    Science.gov (United States)

    Li, Chunbiao; Sprott, Julien Clinton; Xing, Hongyan

    2016-12-01

    A crisis of amplitude control can occur when a system is multistable. This paper proposes a new chaotic system with a line of equilibria to demonstrate the threat to amplitude control from multistability. The new symmetric system has two coefficients for amplitude control, one of which is a partial amplitude controller, while the other is a total amplitude controller that simultaneously controls the frequency. The amplitude parameter rescales the basins of attraction and triggers a state switch among different states resulting in a failure of amplitude control to the desired state.

  12. Calculation of multi-loop superstring amplitudes

    Science.gov (United States)

    Danilov, G. S.

    2016-12-01

    The multi-loop interaction amplitudes in the closed, oriented superstring theory are obtained by the integration of local amplitudes. The local amplitude is represented by a sum over the spinning string local amplitudes. The spinning string local amplitudes are given explicitly through super-Schottky group parameters and through interaction vertex coordinates on the (1| 1) complex, non-split supermanifold. The obtained amplitudes are free from divergences. They are consistent with the world-sheet spinning string symmetries. The vacuum amplitude vanishes along with 1-, 2- and 3-point amplitudes of massless states. The vanishing of the above-mentioned amplitude occurs after the integration of the corresponding local amplitude has been performed over the super-Schottky group limiting points and over interaction vertex coordinate, except for those (3| 2) variables which are fixed due to SL(2)-symmetry.

  13. Velocidad de la onda de pulso y la excreción urinaria de albumina en pacientes hipertensos tratados con Perindopril Pulse wave velocity and urinary albumin excretion in hypertensive patients treated with perindopril

    Directory of Open Access Journals (Sweden)

    J. E. Tobilli

    2002-12-01

    Full Text Available La presión arterial sistólica, la presión arterial diastólica y la excreción urinaria de albúmina (EUA han sido reconocidas como predictores de riesgo cardiovascular. Además, los trastornos de la compliance arterial (CA evaluados mediante la velocidad de la onda de pulso elevada (VOP están estrechamente relacionados con los cambios de la presión arterial y correlacionados con la mortalidad cardiovascular y la presencia de ateroesclerosis. El objetivo primario de este estudio ha sido determinar la relación entre la VOP y la EUA en un grupo de pacientes no fumadores con hipertensión esencial y secundariamente evaluar los cambios producidos por un inhibidor de la enzima convertidora de angiotensina (perindopril sobre estas dos variables. En el estudio participaron setenta pacientes (33 hombres y 37 mujeres hipertensos no fumadores, sin tratamiento previo, de 50 ± 7 años (entre 35-69. La VOP de todos los pacientes fue estudiada por medio de un dispositivo computarizado (Complior en el período basal y a los seis meses de tratamiento con perindopril. También se determinó la EUA por el método de inmunodifusión radial al inicio del tratamiento y luego de seis meses de tratamiento con perindopril (4.6 ± 1.4 mg/día. Al finalizar el estudio se observó una reducción significativa de la presión arterial sistólica (PAS (160.2 ± 10.6 vs. 131.9 ± 7.1 mmHg, pSystolic and diastolic blood pressures and urinary albumin excretion (UAE have been recognized as predictors for cardiovascular risk. Furthermore, arterial compliance (AC disorders assessed by increased aortic pulse wave velocity (PWV are closely related to changes in blood pressure and strongly correlated with cardiovascular mortality and presence or extent of atherosclerosis. Our purpose in the present study was to determine a relationship between AC using PWV and UAE in a group of non-smoking patients with essential hypertension, and the level of interaction of ACE inhibition on

  14. Calibrated heat-pulse method for the assessment of maize water uptake Desenvolvimento do método do "pulso de calor" para determinação da absorção hídrica em milho

    Directory of Open Access Journals (Sweden)

    Antonio Odair Santos

    2000-03-01

    Full Text Available Plant water requirements are important aspects of crop production to be determined in the field, in order to judiciously manage crop water usage. Water uptake by field grown maize (Zea mays L., under well-watered conditions was verified with the heat-pulse system. The temperature difference between two radially inserted thermocouples, one 9 mm above and the other 4 mm below a heater piercing the maize stem, was measured every 0.3 seconds following emission of a heat-pulse. Comparisons of the heat-pulse system outputs, lysimetric measurement and transpiration model estimates were monitored on an hourly and daily basis. At normal and low atmospheric demand daily and hourly values of heat-pulse outputs and lysimetric measurement showed good agreement. Hourly agreement of a modified Penman-Monteith energy balance equation estimate and heat-pulse outputs showed accordance between measurement of sap flow and the plant water-loss theory. Study of the relationship between maize canopy water loss rate and heat velocity in the stem showed that these two parameters were proportional and a calibration factor of 1.51 for full soil foliage coverage was verified.A determinação a campo das necessidades hídricas de plantas é um aspecto importante da produção agrícola, para o manejo correto do uso da água pelos cultivos. A absorção de água por uma cultura de milho (Zea mays L., cultivado a campo, em condições de não limitação hídrica, foi verificada através da técnica do pulso de calor. Após a emissão de um pulso, procedeu-se a medições, a cada 0,3 segundos, do diferencial de temperatura entre dois termopares, inseridos radialmente no caule da planta. O primeiro foi colocado 9 mm acima e o segundo 4 mm abaixo de uma fonte de calor ("heater". Foram feitas comparações entre as medições feitas pela técnica do pulso de calor, lisímetro e estimativas da transpiração computadas em modelo, numa base horária e diária. Comparações entre

  15. Estimación de la velocidad de propagación aórtica basada en el análisis de la onda de pulso radial Velocity estimation of aortic propagation based on radial pulse wave analysis

    Directory of Open Access Journals (Sweden)

    Fernando Clara

    2011-06-01

    Full Text Available Se exploró la posibilidad de utilizar la morfología del registro de onda de pulso radial obtenida mediante un transductor de movimiento para evaluar la velocidad de propagación aórtica. Se efectuó el registro de onda de pulso en arteria radial mediante un transductor apoyado sobre la zona de palpación del pulso, sobre un conjunto de 167 voluntarios varones sanos normotensos de edades comprendidas entre la 2ª y la 7ª década. Se identificó en los registros la onda reflejada y se definió un coeficiente de velocidad como el cociente entre la talla del individuo y el tiempo transcurrido entre el máximo de la onda sistólica y el instante de llegada de dicha onda. Se halló que en los normotensos el coeficiente mencionado aumentó en forma lineal con la edad, en una proporción similar al aumento de velocidad de propagación aórtica medido con otros métodos. Se repitió el procedimiento en otro conjunto de 125 varones hipertensos sin otros factores de riesgo, de edades entre la 3ª y la 7ª década, hallándose valores similares a los normotensos solamente en la 3ª década, a partir de la cual se registró un incremento significativo de dicho índice. Tales hallazgos sustentan la factibilidad de utilizar tal tipo de registros para evaluar indirectamente la velocidad de propagación junto con el índice de aumentación, un parámetro habitualmente utilizado en el análisis de onda de pulso.We analyzed the possibility of using the radial pulse wave morphology, obtained by a movement transducer, to evaluate the aortic pulse wave velocity. The radial pulse wave signals were obtained by using a transducer, located on the pulse palpation area, in 167 healthy normotensive male volunteers, ages 20 to 70. The reflected wave was identified in every case. Also, a speed coefficient was defined as the ratio between the individual's height and the time between the maximum systolic wave and the arrival time of the reflected wave. We found that the

  16. A cidade dos outros

    Directory of Open Access Journals (Sweden)

    Ernesto Venturini

    2009-08-01

    Full Text Available Os percursos costumeiros dentro da cidade em que vivemos desenham nosso "mapa da cidade". A tipologia deste mapa depende fundamentalmente de nosso nível social. Examinou-se, anteriormente, o mapa da cidade dos pacientes que saíram do hospital psiquiátrico, para avaliar os efeitos da desinstitucionalização. Hoje, examina-se como vive o clandestino dentro das cidades italianas. O mapa do clandestino se baseia na degradação; evidencia mecanismos de intolerância e de acolhida; permite entender como as pessoas se enrijecem em suas posições ou, ao contrário, como as identidades dos sujeitos interagem e favorecem mudanças e emancipação. A escolha se funda na disponibilidade dos sujeitos e é fortemente influenciada pelas políticas públicas de respeito dos direitos das pessoas.

  17. Velocidade da onda de pulso, pressão arterial e adipocitocinas em adultos jovens: estudo do Rio de Janeiro Pulse wave velocity, blood pressure and adipocytokines in young adults: the Rio de Janeiro study

    Directory of Open Access Journals (Sweden)

    Oswaldo Luiz Pizzi

    2012-01-01

    Full Text Available FUNDAMENTO: Dados sobre a avaliação não invasiva vascular e suas relações com variáveis de risco cardiovascular são escassos em jovens. OBJETIVO: Avaliar a relação entre a velocidade de onda de pulso e a pressão arterial,variáveis antropométricas e metabólicas, incluindo as adipocitocinas, em indivíduos adultos jovens. MÉTODOS: Foram avaliados 96 indivíduos (51 homens do estudo do Rio de Janeiro, de 26 a 35 anos (média 30,09 ± 1,92. Foram obtidos a velocidade de onda de pulso (método Complior, pressão arterial, índice de massa corporal, glicose, perfil lipídico, leptina, insulina, adiponectina e o índice de resistência à insulina HOMA-IR. Os indivíduos foram estratificados em três grupos segundo o tercil da VOP para cada sexo. RESULTADOS: O grupo com maior tercil de VOP mostrou maiores médias de pressão arterial sistólica, pressão arterial diastólica, pressão arterial média, índice de massa corporal, insulina, HOMA-IR e menores médias de adiponectina, além de maiores prevalências de diabetes mellitus/intolerância à glicose e hiperinsulinemia. Houve correlação significativa e positiva da velocidade da onda de pulso com pressão arterial sistólica, pressão arterial diastólica, pressão de pulso e pressão arterial média, índice de massa corporal, e LDL-colesterol e negativa com HDL-colesterol e adiponectina. Em modelo de regressão múltipla, após ajuste do HDL-colesterol, LDL-colesterol e adiponectina para sexo, idade, índice de massa corporal e pressão arterial média, apenas o sexo masculino e a pressão arterial média mantiveram correlação significativa com a velocidade de onda de pulso. CONCLUSÃO: A velocidade de onda de pulso em adultos jovens mostrou relação significativa com variáveis de risco cardiovascular, destacando-se o sexo masculino e a pressão arterial média como importantes variáveis no seu determinismo. Os achados sugerem que a medida da VOP pode ser útil para a

  18. Velocidade da onda de pulso, pressão arterial e adipocitocinas em adultos jovens: estudo do Rio de Janeiro Pulse wave velocity, blood pressure and adipocytokines in young adults: the Rio de Janeiro study

    Directory of Open Access Journals (Sweden)

    Oswaldo Luiz Pizzi

    2013-01-01

    Full Text Available FUNDAMENTO: Dados sobre a avaliação não invasiva vascular e suas relações com variáveis de risco cardiovascular são escassos em jovens. OBJETIVO: Avaliar a relação entre a velocidade de onda de pulso e a pressão arterial,variáveis antropométricas e metabólicas, incluindo as adipocitocinas, em indivíduos adultos jovens. MÉTODOS: Foram avaliados 96 indivíduos (51 homens do estudo do Rio de Janeiro, de 26 a 35 anos (média 30,09 ± 1,92. Foram obtidos a velocidade de onda de pulso (método Complior, pressão arterial, índice de massa corporal, glicose, perfil lipídico, leptina, insulina, adiponectina e o índice de resistência à insulina HOMA-IR. Os indivíduos foram estratificados em três grupos segundo o tercil da VOP para cada sexo. RESULTADOS: O grupo com maior tercil de VOP mostrou maiores médias de pressão arterial sistólica, pressão arterial diastólica, pressão arterial média, índice de massa corporal, insulina, HOMA-IR e menores médias de adiponectina, além de maiores prevalências de diabetes mellitus/intolerância à glicose e hiperinsulinemia. Houve correlação significativa e positiva da velocidade da onda de pulso com pressão arterial sistólica, pressão arterial diastólica, pressão de pulso e pressão arterial média, índice de massa corporal, e LDL-colesterol e negativa com HDL-colesterol e adiponectina. Em modelo de regressão múltipla, após ajuste do HDL-colesterol, LDL-colesterol e adiponectina para sexo, idade, índice de massa corporal e pressão arterial média, apenas o sexo masculino e a pressão arterial média mantiveram correlação significativa com a velocidade de onda de pulso. CONCLUSÃO: A velocidade de onda de pulso em adultos jovens mostrou relação significativa com variáveis de risco cardiovascular, destacando-se o sexo masculino e a pressão arterial média como importantes variáveis no seu determinismo. Os achados sugerem que a medida da VOP pode ser útil para a

  19. Amplitude recruitment of cochlear potential

    Institute of Scientific and Technical Information of China (English)

    LI Xingqi; SUN Wei; SUN Jianhe; YU Ning; JIANG Sichang

    2001-01-01

    Intracellular recordings were made from outer hair cells (OHC) and the cochlear microphonics (CM) were recorded from scala media (SM) in three turn of guinea pig cochlea,the compound action potential (CAP) were recorded at the round window (RW) before and after the animal were exposed to white noise. The results suggest that the nonlinear properties with “saduration” of Input/output (I/O) function of OHC AC recepter potential and CM were founded; the nonlinear properties with “Low”, “Platean” and “high” of CAP also were investigated. After explosion, the threshold shift of CAP has about 10 dB. The I/O of OHC responses and CM were changed in a linearizing (i.e., nonlinearity loss), the “platean” of I/O CAP disappeared and the growth rate of CAP amplitude were larger than before explosion. The response amplitude recruitment of OHC appears to result from reduction in gain (i.e., hearing loss); It was due to the nonlinear growth function of OHC receptor potentials was changed in linearzing that the basilar membrance motion was changed in linearizing. Since intensity coding in the inner ear depends on an interactions of nonlinear basilar membrance and nerve fibers. So that it must lead to a linearizing of CAP as input responses.

  20. Relations Between Helicity Coupling Amplitude and L-S Coupling Amplitude

    Institute of Scientific and Technical Information of China (English)

    WU Ning; RUAN Tu-Nan

    2001-01-01

    Relations between helicity coupling amplitude and L-S coupling amplitude are discussed. The equivalence condition for these two kinematic analysis methods and the limitations of the L-S coupling amplitude are also studied in this paper.``

  1. 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...

  2. Holonomy-flux spinfoam amplitude

    CERN Document Server

    Perini, Claudio

    2012-01-01

    We introduce a holomorphic representation for the Lorentzian EPRL spinfoam on arbitrary 2-complexes. The representation is obtained via the Ashtekar-Lewandowski-Marolf-Mour\\~ao-Thiemann heat kernel coherent state transform. The new variables are classical holonomy-flux phase space variables $(h,X)\\simeq \\mathcal T^*SU(2)$ of Hamiltonian loop quantum gravity prescribing the holonomies of the Ashtekar connection $A=\\Gamma + \\gamma K$, and their conjugate gravitational fluxes. For small heat kernel `time' the spinfoam amplitude is peaked on classical space-time geometries, where at most countably many curvatures are allowed for non-zero Barbero-Immirzi parameter. We briefly comment on the possibility to use the alternative flipped classical limit.

  3. 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.

  4. Constructing amplitudes from their soft limits

    Science.gov (United States)

    Boucher-Veronneau, Camille; Larkoski, Andrew J.

    2011-09-01

    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.

  5. A Note on Loop Amplitudes in QED

    CERN Document Server

    Brandhuber, Andreas; Vincon, Massimiliano

    2009-01-01

    We consider the two-loop four-point amplitude in N=2 super QED, and show that there exists an approximate recursive structure similar to that captured by the ABDK/BDS ansatz for MHV amplitudes in N=4 super Yang-Mills. Furthermore, we present a simple relation between the box coefficients of one-loop photon MHV amplitudes in (super) QED, and sums of box coefficients of one-loop MHV amplitudes in (super) Yang-Mills.

  6. Tsunami Focusing and Leading Amplitude

    Science.gov (United States)

    Kanoglu, U.

    2016-12-01

    Tsunamis transform substantially through spatial and temporal spreading from their source region. This substantial spreading might result unique maximum tsunami wave heights which might be attributed to the source configuration, directivity, the waveguide structures of mid-ocean ridges and continental shelves, focusing and defocusing through submarine seamounts, random focusing due to small changes in bathymetry, dispersion, and, most likely, combination of some of these effects. In terms of the maximum tsunami wave height, after Okal and Synolakis (2016 Geophys. J. Int. 204, 719-735), it is clear that dispersion would be one of the reasons to drive the leading wave amplitude in a tsunami wave train. Okal and Synolakis (2016), referring to this phenomenon as sequencing -later waves in the train becoming higher than the leading one, considered Hammack's (1972, Ph.D. Dissertation, Calif. Inst. Tech., 261 pp) formalism, in addition to LeMéhauté and Wang's (1995 Water waves generated by underwater explosion, World Scientific, 367 pp), to evaluate linear dispersive tsunami propagation from a circular plug uplifted on an ocean of constant depth. They identified transition distance, as the second wave being larger, performing parametric study for the radius of the plug and the depth of the ocean. Here, we extend Okal and Synolakis' (2016) analysis to an initial wave field with a finite crest length and, in addition, to a most common tsunami initial wave form of N-wave (Tadepalli and Synolakis, 1994 Proc. R. Soc. A: Math. Phys. Eng. Sci. 445, 99-112). First, we investigate the focusing feature in the leading-depression side, which enhance tsunami wave height as presented by Kanoglu et al. (2013 Proc. R. Soc. A: Math. Phys. Eng. Sci. 469, 20130015). We then discuss the results in terms of leading wave amplitude presenting a parametric study and identify a simple relation for the transition distance. The solution presented here could be used to better analyze dispersive

  7. Quantum Amplitude Amplification and Estimation

    CERN Document Server

    Brassard, G; Mosca, M; Tapp, A; Brassard, Gilles; Hoyer, Peter; Mosca, Michele; Tapp, Alain

    2000-01-01

    Consider a Boolean function $\\chi: X \\to \\{0,1\\}$ that partitions set $X$ between its good and bad elements, where $x$ is good if $\\chi(x)=1$ and bad otherwise. Consider also a quantum algorithm $\\mathcal A$ such that $A \\ket{0} = \\sum_{x\\in X} \\alpha_x \\ket{x}$ is a quantum superposition of the elements of $X$, and let $a$ denote the probability that a good element is produced if $A \\ket{0}$ is measured. If we repeat the process of running $A$, measuring the output, and using $\\chi$ to check the validity of the result, we shall expect to repeat $1/a$ times on the average before a solution is found. *Amplitude amplification* is a process that allows to find a good $x$ after an expected number of applications of $A$ and its inverse which is proportional to $1/\\sqrt{a}$, assuming algorithm $A$ makes no measurements. This is a generalization of Grover's searching algorithm in which $A$ was restricted to producing an equal superposition of all members of $X$ and we had a promise that a single $x$ existed such tha...

  8. Dinámica de la producción primaria fitoplanctónica en un lago tropical (ciénaga Escobillitas a lo largo del pulso de inundación

    Directory of Open Access Journals (Sweden)

    Yimmy Montoya

    2010-01-01

    Full Text Available En comparación con los ecosistemas acuáticos de zonas templadas, los lagos de inundación tropicales son sistemas altamente complejos, numerosos pero poco conocidos. Esta investigación evaluó la variación de la producción primaria y la biomasa fitoplanctónica en una estación en la ciénaga Escobillitas del complejo cenagoso de Ayapel, ubicado al norte de Colombia. Se presentó variación de la producción primaria en relación con el pulso de inundación, ya que esta osciló entre 0 (aguas altas en ascenso 2007 y 191.6 mgC m-2 d-1 (aguas altas en descenso 2007 con un valor medio de 108.6 mgC m-2 d-1. Se encontró la mayor producción primaria bruta en aguas altas en descenso, condición acompañada por un mayor registro de biomasa algal, reducción en la eficiencia fotosintética, bajos valores de respiración y de las relaciones P/B y P/R. Entre ciclos hidrológicos consecutivos se presenta variación de los patrones de producción primaria, ya que para la fase de aguas altas en ascenso, en el 2006 se presentó una baja biomasa, con una alta PPB, acompañados de la mayor eficiencia fotosintética y altos valores de la respiración, En contraste, para el mismo periodo hidrológico del pulso de inundación pero en el año 2007, se presentó un aumento de la biomasa, reducción de la PPB, de la eficiencia fotosintética, de la relación P/B y de la respiración. El sistema acuático oscila entre euproductivo y oligoproductivo, lo cual es indicador de una alta dinámica trófica.

  9. O ecologismo dos pobres

    Directory of Open Access Journals (Sweden)

    Juan Martinez ALIER

    1997-12-01

    Full Text Available O ecologísmo tem colocado em cheque as leis capitalistas de mercado, principalmente na sua fase globalizada, devido à apropriação e exploração inconsequente dos recursos naturais. Ao mesmo tempo tem apontado que o meio ambiente não se reduz ao tratamento somente cientifico da natureza. O presente artigo ressalta aspectos importantes do ecologísmo como a participação das mulheres, o marxismo, o neo-narodnismo, etc. e é rico em exemplos de problemas ambientais decorrentes das relações de produção. O ecologísmo dos pobres é apontado como uma perspectiva necessária às lutas ambientais no Terceiro Mundo.

  10. Discontinuities of multi-Regge amplitudes

    CERN Document Server

    Fadin, V S

    2014-01-01

    In the BFKL approach, discontinuities of multiple production amplitudes in invariant masses of produced particles are discussed. It turns out that they are in evident contradiction with the BDS ansatz for $n$-gluon amplitudes in the planar $N$=4 SYM at $n\\ge 6$. An explicit expression for the NLO discontinuity of the two-to-four amplitude in the invariant mass of two produced gluons is is presented.

  11. 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.

  12. DVCS amplitude with kinematical twist-3 terms

    CERN Document Server

    Radyushkin, A V

    2000-01-01

    We 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 we include the operators of twist-3 which appear as total derivatives of twist-2 operators. Our results are equivalent to a Wandzura-Wilczek approximation for twist-3 skewed parton distributions. We 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.

  13. 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...... Feynman diagrams. The study of multiloop scattering amplitudes is crucial for the new era of precision phenomenology at the Large Hadron Collider (LHC) at CERN. Loop-level scattering amplitudes can be reduced to a basis of linearly independent integrals whose coefficients are extracted from generalized...

  14. Tomando el pulso a la perspectiva de género: un estudio de caso en una institución universitaria de formación de profesorado de educación física

    Directory of Open Access Journals (Sweden)

    María PRAT GRAU

    2012-01-01

    Full Text Available Esta investigación tiene como principal objetivo explorar cómo se aborda la perspectiva de género en la formación de profesorado de Educación Física de una institución universitaria. Las políticas de igualdad en el contexto universitario europeo nos sitúan en el marco idóneo para revisar la cuestión de género en la formación del profesorado, ya que en muchas ocasiones se ha considerado como un aspecto marginal de los planes de estudio, y se ha relegado a una asignatura optativa. Así pues, se pretende tomar el pulso a la situación actual e indagar sobre las actitudes del profesorado hacia las cuestiones de género, a la vez que valorar su tratamiento pedagógico en la formación universitaria de los futuros profesionales de Educación Física.

  15. Secondary threshold amplitudes for sinuous streak breakdown

    Science.gov (United States)

    Cossu, Carlo; Brandt, Luca; Bagheri, Shervin; Henningson, Dan S.

    2011-07-01

    The nonlinear stability of laminar sinuously bent streaks is studied for the plane Couette flow at Re = 500 in a nearly minimal box and for the Blasius boundary layer at Reδ*=700. The initial perturbations are nonlinearly saturated streamwise streaks of amplitude AU perturbed with sinuous perturbations of amplitude AW. The local boundary of the basin of attraction of the linearly stable laminar flow is computed by bisection and projected in the AU - AW plane providing a well defined critical curve. Different streak transition scenarios are seen to correspond to different regions of the critical curve. The modal instability of the streaks is responsible for transition for AU = 25%-27% for the considered flows, where sinuous perturbations of amplitude below AW ≈ 1%-2% are sufficient to counteract the streak viscous dissipation and induce breakdown. The critical amplitude of the sinuous perturbations increases when the streamwise streak amplitude is decreased. With secondary perturbations amplitude AW ≈ 4%, breakdown is induced on stable streamwise streaks with AU ≈ 13%, following the secondary transient growth scenario first examined by Schoppa and Hussain [J. Fluid Mech. 453, 57 (2002)]. A cross-over, where the critical amplitude of the sinuous perturbation becomes larger than the amplitude of streamwise streaks, is observed for streaks of small amplitude AU < 5%-6%. In this case, the transition is induced by an initial transient amplification of streamwise vortices, forced by the decaying sinuous mode. This is followed by the growth of the streaks and final breakdown. The shape of the critical AU - AW curve is very similar for Couette and boundary layer flows and seems to be relatively insensitive to the nature of the edge states on the basin boundary. The shape of this critical curve indicates that the stability of streamwise streaks should always be assessed in terms of both the streak amplitude and the amplitude of spanwise velocity perturbations.

  16. Dos cupas complutenses

    Directory of Open Access Journals (Sweden)

    Stylow, Armin U.

    2006-12-01

    Full Text Available Publication of two cupae from the ancient territory of Complutum. One was found in excavations in Alcalá de Henares (Madrid and is unpublished; of the other one, which came to light in the church of Alovera (Guadalajara, a new reading is given.Se publican dos cupas del antiguo territorio de Complutum, una, inédita, encontrada en excavación en Alcalá de Henares (Madrid, y la segunda, procedente de la iglesia de Alovera (Guadalajara, con una nueva lectura.

  17. Sustentabilidad a dos tiempos

    OpenAIRE

    Santiago Jiménez, María Evelinda

    2012-01-01

    Este trabajo revisa los hechos y documentos de organismos mundiales que conformaron el discurso del desarrollo sustentable. Así también, describe cómo el desarrollo sustentable cobra bajo dos lecturas o concepciones muy diferentes efectos, en la sociedad y en el planeta, muy distintos: una construida desde los conceptos desarrollistas y otra que construye un discurso alternativo que toma en cuenta las representaciones sociales y modos de producción de las comunidades originarias donde se hall...

  18. Geoeconomia dos emergentes

    OpenAIRE

    Pinto, Pedro

    2010-01-01

    Mercados decisivos para a recuperação da economia global, até porque muito mais imunes às consequências da crise fi nanceira, os países emergentes apresentam taxas de crescimento mais altas face aos principais países desenvolvidos e têm desempenhado um papel fundamental na consolidação dos volumes de comércio internacional e de crescimento da economia mundial ao longo desta última década.

  19. BCFW construction of the Veneziano amplitude

    Energy Technology Data Exchange (ETDEWEB)

    Fotopoulos, Angelos, E-mail: foto@to.infn.it [Dipartimento di Fisica Teorica dell Universita di Torino and INFN Sezione di Torino, via P. Giuria 1, I-10125 Torino (Italy)

    2011-06-10

    In this paper we demonstrate how one can compute the Veneziano amplitude for bosonic string theory using the Britto-Cachazo-Feng-Witten method. We use an educated ansatz for the cubic amplitude of two tachyons and an arbitrary level string state.

  20. BCFW construction of the Veneziano amplitude

    Science.gov (United States)

    Fotopoulos, Angelos

    2011-06-01

    In this paper we demonstrate how one can compute the Veneziano amplitude for bosonic string theory using the Britto-Cachazo-Feng-Witten method. We use an educated ansatz for the cubic amplitude of two tachyons and an arbitrary level string state.

  1. Interlimb coupling strength scales with movement amplitude.

    Science.gov (United States)

    Peper, C Lieke E; de Boer, Betteco J; de Poel, Harjo J; Beek, Peter J

    2008-05-23

    The relation between movement amplitude and the strength of interlimb interactions was examined by comparing bimanual performance at different amplitude ratios (1:2, 1:1, and 2:1). For conditions with unequal amplitudes, the arm moving at the smaller amplitude was predicted to be more strongly affected by the contralateral arm than vice versa. This prediction was based on neurophysiological considerations and the HKB model of coupled oscillators. Participants performed rhythmic bimanual forearm movements at prescribed amplitude relations. After a brief mechanical perturbation of one arm, the relaxation process back to the initial coordination pattern was examined. This analysis focused on phase adaptations in the unperturbed arm, as these reflect the degree to which the movements of this arm were affected by the coupling influences stemming from the contralateral (perturbed) arm. The thus obtained index of coupling (IC) reflected the relative contribution of the unperturbed arm to the relaxation process. As predicted IC was larger when the perturbed arm moved at a larger amplitude than did the unperturbed arm, indicating that coupling strength scaled with movement amplitude. This result was discussed in relation to previous research regarding sources of asymmetry in coupling strength and the effects of amplitude disparity on interlimb coordination.

  2. 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

  3. Off-shell amplitudes and Grassmannians

    Science.gov (United States)

    Bork, L. V.; Onishchenko, A. I.

    2017-09-01

    The Grassmannian representation for gauge-invariant amplitudes for arbitrary number of legs with one of them being off-shell is derived for the case of N = 4 SYM. The obtained formula are successfully checked against known BCFW results for MHV n , NMHV4 and NMHV5 amplitudes.

  4. 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 n

  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. The DosS-DosT/DosR Mycobacterial Sensor System

    Directory of Open Access Journals (Sweden)

    Santhosh Sivaramakrishnan

    2013-07-01

    Full Text Available DosS/DosR is a two-component regulatory system in which DosS, a heme-containing sensor also known as DevS, under certain conditions undergoes autophosphorylation and then transfers the phosphate to DosR, a DNA-binding protein that controls the entry of Mycobacterium tuberculosis and other mycobacteria into a latent, dormant state. DosT, a second sensor closely related to DosS, is present in M. tuberculosis and participates in the control of the dormancy response mediated by DosR. The binding of phosphorylated DosR to DNA initiates the expression of approximately fifty dormancy-linked genes. DosT is accepted to be a gas sensor that is activated in the ferrous state by the absence of an oxygen ligand or by the binding of NO or CO. DosS functions in a similar fashion as a gas sensor, but contradictory evidence has led to the suggestion that it also functions as a redox state sensor. This review focuses on the structure, biophysical properties, and function of the DosS/DosT heme sensors.

  7. The Lorentzian proper vertex amplitude: Asymptotics

    CERN Document Server

    Engle, Jonathan; Zipfel, Antonia

    2015-01-01

    In previous work, the Lorentzian proper vertex amplitude for a spin-foam model of quantum gravity was derived. In the present work, the asymptotics of this amplitude are studied in the semi-classical limit. The starting point of the analysis is an expression for the amplitude as an action integral with action differing from that in the EPRL case by an extra `projector' term which scales linearly with spins only in the asymptotic limit. New tools are introduced to generalize stationary phase methods to this case. For the case of boundary data which can be glued to a non-degenerate Lorentzian 4-simplex, the asymptotic limit of the amplitude is shown to equal the single Feynman term, showing that the extra term in the asymptotics of the EPRL amplitude has been eliminated.

  8. 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.

  9. Uma tipologia dos games

    Directory of Open Access Journals (Sweden)

    Branco, Marsal Alves

    2006-01-01

    Full Text Available Este artigo traz uma diferente concepção acerca da tipologia dos games. Partimos da concepção que narratologia e ludologia devem estar relacionadas, como já aponta Frasca, contudo, esta articulação ainda não dá conta de algumas especificidades dos games. A partir disso, propomos alguns movimentos: a existência de um conceito de narrativa específico que é formado pela ação de três diferentes dimensões; uma dimensão genérica ou de gênero narrativo propriamente dito; uma dimensão ludológica; e uma terceira dimensão, que é a dimensão tecnológica. This article presents a different conception concerning the tipology of games. We begin from the conception that narrative and ludology should be relates, as mentioned by frasca, however, this articulation hasn't given an account on some specificities of the game yet. From this, we propose some movements: The existence of a specific narrative concept which is formed by the action of three diferrent dimensions; a generic or narrative sort of dimension; a ludologic dimension; and a third dimension, which is the technological dimension.

  10. A Medicina dos Sintomas

    Directory of Open Access Journals (Sweden)

    Bárbara Bontempo de Menezes

    2015-09-01

    Full Text Available Gilson Dantas, médico e doutor em sociologia, aponta os vieses da prática médica atual na publicação «A Medicina dos Sintomas». O autor defende a tese de que o erro está no método, e não é à toa, nem por má vontade dos profissionais. Acima de tudo, o método praticado nos consultórios públicos e privados do país serviria ao capitalismo de várias maneiras. Dantas começa descrevendo o atendimento imediatista, que permite o pronto retorno do trabalhador a seu posto de trabalho. Nesta prática, prevalece uma abordagem rápida em que a comunicação é pautada puramente pelos sintomas. O paciente é reduzido a sua parte com problema ou até mesmo ao problema de sua parte. Promove-se o consumo de exames e prescreve-se a dependência de medicamentos, atendendo aos interesses de uma das indústrias mais lucrativas do mundo. Esse círculo se fecha com a produção de novos sintomas gerados pelos tratamentos químicos propostos (iatrogenia e, assim, novas demandas por serviços desse mesmo tipo.

  11. dos estudios de caso

    Directory of Open Access Journals (Sweden)

    Daniel Kersffeld

    2013-01-01

    Full Text Available La UNASUR se ha destacado desde sus inicios en la compleja labor de mediación y resolución de conflictos internacionales. Para ello, esta entidad multilateral ha apelado a distintas fórmulas políticas tendientes al encausamiento de problemáticas y conflictos apartados del camino de la institucionalidad y de los medios tradicionales de resolución. Con todo, y pese a la búsqueda de caminos alternativos, han sido las cumbres presidenciales la principal herramienta destinada a encontrar soluciones innovadoras y respetuosas del orden democrático y constitucional de los países sudamericanos. En este artículo se analiza de manera específica la actuación de la unasur en dos casos de profunda gravedad institucional: el intento de golpe de Estado ocurrido en Ecuador el 30 de septiembre de 2010 y el derrocamiento del ex presidente Fernando Lugo en Paraguay en junio de 2012. Luego de analizar estos dos casos extremos, y las implicancias políticas generadas, se avanza en una visión comprensiva acerca del éxito o el fracaso del papel político de la unasur como instancia de resolución de conflictos a nivel internacional.

  12. Holographic corrections to meson scattering amplitudes

    Energy Technology Data Exchange (ETDEWEB)

    Armoni, Adi; Ireson, Edwin, E-mail: 746616@swansea.ac.uk

    2017-06-15

    We compute meson scattering amplitudes using the holographic duality between confining gauge theories and string theory, in order to consider holographic corrections to the Veneziano amplitude and associated higher-point functions. The generic nature of such computations is explained, thanks to the well-understood nature of confining string backgrounds, and two different examples of the calculation in given backgrounds are used to illustrate the details. The effect we discover, whilst only qualitative, is re-obtainable in many such examples, in four-point but also higher point amplitudes.

  13. Hidden simplicity of gauge theory amplitudes

    Energy Technology Data Exchange (ETDEWEB)

    Drummond, J M, E-mail: drummond@lapp.in2p3.f [LAPTH, Universite de Savoie, CNRS, B.P. 110, F-74941 Annecy-le-Vieux, Cedex (France)

    2010-11-07

    These notes were given as lectures at the CERN Winter School on Supergravity, Strings and Gauge Theory 2010. We describe the structure of scattering amplitudes in gauge theories, focussing on the maximally supersymmetric theory to highlight the hidden symmetries which appear. Using the Britto, Cachzo, Feng and Witten (BCFW) recursion relations we solve the tree-level S-matrix in N=4 super Yang-Mills theory and describe how it produces a sum of invariants of a large symmetry algebra. We review amplitudes in the planar theory beyond tree level, describing the connection between amplitudes and Wilson loops, and discuss the implications of the hidden symmetries.

  14. Hidden simplicity of gauge theory amplitudes

    Science.gov (United States)

    Drummond, J. M.

    2010-11-01

    These notes were given as lectures at the CERN Winter School on Supergravity, Strings and Gauge Theory 2010. We describe the structure of scattering amplitudes in gauge theories, focussing on the maximally supersymmetric theory to highlight the hidden symmetries which appear. Using the Britto, Cachzo, Feng and Witten (BCFW) recursion relations we solve the tree-level S-matrix in \\ {N}=4 super Yang-Mills theory and describe how it produces a sum of invariants of a large symmetry algebra. We review amplitudes in the planar theory beyond tree level, describing the connection between amplitudes and Wilson loops, and discuss the implications of the hidden symmetries.

  15. Holographic Corrections to Meson Scattering Amplitudes

    CERN Document Server

    Armoni, Adi

    2016-01-01

    We compute meson scattering amplitudes using the holographic duality between confining gauge theories and string theory, in order to consider holographic corrections to the Veneziano amplitude and associated higher-point functions. The generic nature of such computations is explained, thanks to the well-understood nature of confining string backgrounds, and two different examples of the calculation in given backgrounds are used to illustrate the details. The effect we discover, whilst only qualitative, is re-obtainable in many such examples, in four-point but also higher point amplitudes.

  16. Softness and Amplitudes' Positivity for Spinning Particles

    CERN Document Server

    Bellazzini, Brando

    2016-01-01

    We derive positivity bounds for scattering amplitudes of particles with arbitrary spin using unitarity, analyticity and crossing symmetry. The bounds imply the positivity of certain low-energy coefficients of the effective action that controls the dynamics of the light degrees of freedom. We show that low-energy amplitudes strictly softer than $O(p^4)$ do not admit unitary ultraviolet completions unless the theory is free. This enforces a bound on the energy growth of scattering amplitudes in the region of validity of the effective theory. We discuss explicit examples including the Goldstino from spontaneous supersymmetry breaking, and the theory of a spin-1/2 fermion with a shift symmetry.

  17. Target tracking based on frequency spectrum amplitude

    Institute of Scientific and Technical Information of China (English)

    Guo Huidong; Zhang Xinhua; Xia Zhijun

    2006-01-01

    The amplitude of frequency spectrum can be integrated with probabilistic data association (PDA) to distinguish the target with clutter echoes, especially in low SNR underwater environment. A new target-tracking algorithm is presented which adopts the amplitude of frequency spectrum to improve target tracking in clutter. The probabilistic density distribution of frequency spectrum amplitude is analyzed. By simulation, the results show that the algorithm is superior to PDA. This approach enhances stability for the association probability and increases the performance of target tracking.

  18. Dos estudios de casos

    Directory of Open Access Journals (Sweden)

    Hernán Guillermo Salazar Morales

    1989-04-01

    Full Text Available RESUMEN A continuación se presenta dos casos de estudio en donde se puede apreciar a la forma  como se establecen  las relaciones en una organización y lo que una DECISION  puede llegar a incidir en el desarrollo de las operaciones de una empresa. Decisiones basadas en la intuición, o en corazonadas, frecuentemente conducen en dirección equivocada, ocasionando pérdidas en tiempo, personal y dinero. El proceso de toma de decisiones deben ser TAREAS ESTRUCTURADAS que se sustenten con hechos. Su ejecución debe hacerse secuencialmente y cumplir con cada uno de sus pasos. El diseño de los  casos está orientado para que  sirvan como material de aplicación en la asignatura de  taller de planeación.

  19. Open String Amplitudes in Various Gauges

    CERN Document Server

    Fuji, H; Suzuki, H; Fuji, Hiroyuki; Nakayama, Shinsaku; Suzuki, Hisao

    2007-01-01

    Recently, Schnabl constructed the analytic solution of the open string tachyon. Subsequently, the absence of the physical states at the vacuum was proved. The development relies heavily on the use of the gauge condition different from the ordinary one. It was shown that the choice of gauge simplifies the analysis drastically. When we perform the calculation of the amplitudes in Schnabl gauge, we find that the off-shell amplitudes of the Schnabl gauge is still very complicated. In this paper, we propose the use of the propagator in the modified Schnabl gauge and show that this modified use of the Schnabl gauge simplifies the computation of the off-shell amplitudes drastically. We also compute the amplitudes of open superstring in this gauge.

  20. Scattering Amplitudes via Algebraic Geometry Methods

    CERN Document Server

    Søgaard, Mads; Damgaard, Poul Henrik

    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 Feynman diagrams. The study of multiloop scattering amplitudes is crucial for the new era of precision phenomenology at the Large Hadron Collider (LHC) at CERN. Loop-level scattering amplitudes can be reduced to a basis of linearly independent integrals whose coefficients are extracted from generalized 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 ...

  1. Off-shell Amplitudes in Superstring Theory

    CERN Document Server

    Sen, Ashoke

    2014-01-01

    Computing the renormalized masses and S-matrix elements in string theory, involving states whose masses are not protected from quantum corrections, requires defining off-shell amplitude with certain factorization properties. While in the bosonic string theory one can in principle construct such an amplitude from string field theory, there is no fully consistent field theory for superstring and heterotic string theory. In this paper we give a practical construction of off-shell amplitudes satisfying the desired factorization property using the formalism of picture changing operators. We describe a systematic procedure for dealing with the spurious singularities of the integration measure that we encounter when the supermoduli space is not holomorphically projected. This procedure is also useful for computing on-shell amplitudes, as we demonstrate by computing the effect of Fayet-Iliopoulos D-terms in four dimensional heterotic string theory compactifications using this formalism.

  2. Feynman Amplitudes in Mathematics and Physics

    OpenAIRE

    Bloch, Spencer

    2015-01-01

    These are notes of lectures given at the CMI conference in August, 2014 at ICMAT in Madrid. The focus is on some mathematical questions associated to Feynman amplitudes, including Hodge structures, relations with string theory, and monodromy (Cutkosky rules).

  3. Stora's fine notion of divergent amplitudes

    CERN Document Server

    Várilly, Joseph C

    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.

  4. Open string amplitudes of closed topological vertex

    CERN Document Server

    Takasaki, Kanehisa

    2016-01-01

    The closed topological vertex is the simplest "off-strip" case of non-compact toric Calabi-Yau threefolds with acyclic web diagrams. By the diagrammatic method of topological vertex, open string amplitudes of topological string theory therein can be obtained by gluing a single topological vertex to an "on-strip" subdiagram of the tree-like web diagram. If non-trivial partitions are assigned to just two parallel external lines of the web diagram, the amplitudes can be calculated with the aid of techniques borrowed from the melting crystal models. These amplitudes are thereby expressed as matrix elements, modified by simple prefactors, of an operator product on the Fock space of 2D charged free fermions. This fermionic expression can be used to derive $q$-difference equations for generating functions of special subsets of the amplitudes. These $q$-difference equations may be interpreted as the defining equation of a quantum mirror curve.

  5. Amplitudes for left-handed strings

    CERN Document Server

    Siegel, W

    2015-01-01

    We consider a class of string-like models introduced previously where all modes are left-handed, all states are massless, T-duality is manifest, and only a finite number of orders in the string tension can appear. These theories arise from standard string theories by a singular gauge limit and associated change in worldsheet boundary conditions. In this paper we show how to calculate amplitudes by using the gauge parameter as an infrared regulator. The amplitudes produce the Cachazo-He-Yuan delta-functions after some modular integration; the Mason-Skinner string-like action and amplitudes arise from the zero-tension (infinite-slope) limit. However, without the limit the amplitudes have the same problems as found in the Mason-Skinner formalism.

  6. Interferência da coloração de esmaltes de unha e do tempo na oximetria de pulso em voluntários sadios Interference of nail polish colors and time on pulse oximetry in healthy volunteers

    Directory of Open Access Journals (Sweden)

    Mara Harumi Miyake

    2003-12-01

    Full Text Available INTRODUÇÃO: A oximetria de pulso é um método não invasivo de mensuração da saturação periférica da oxiemoglobina (SpO2. É freqüentemente utilizado em unidades de emergência, de terapia intensiva e em centro cirúrgico. A leitura da oximetria de pulso tem acurácia limitada na presença de metaemoglobina, carboxiemoglobina, anemia, vasoconstrição periférica, esmalte de unha, luz fluorescente e movimentação. OBJETIVO: Avaliar a interferência da coloração de esmalte de unha e do tempo sobre a SpO2 em indivíduos sadios. MÉTODO: Participaram do estudo 61 voluntárias sadias, com idades entre 18 e 32 anos. Foi avaliada SpO2 nas seguintes colorações de esmaltes: base (dedo mínimo, rosa claro (dedo anular, rosa claro com cintilante (dedo médio e vermelha (polegar. O indicador não recebeu esmalte. Foi analisado o tempo para cada coloração de esmalte, a cada minuto até completar cinco minutos. RESULTADOS: Quando comparadas as medidas da SpO2 com o controle, as colorações base (p = 0,56, rosa claro (p = 0,56 e rosa claro com cintilante (p = 0,37 não apresentaram diferença estatisticamente significante. A SpO2 apresentou variação significante na cor vermelha (p BACKGROUND: Pulse oximetry is a noninvasive method to measure the saturation of peripheral oxyhaemoglobin (SpO2. It's usually used in emergency, intensive care and operating room units. Pulse oximeter readings have limited accuracy in the presence of methemoglobin, carboxyhemoglobin, anaemia, peripheral vasoconstriction, nail polish, fluorescent light, and motion. OBJECTIVES: To evaluate the interferences of the color of nail polishes and time on SpO2 in healthy individuals. METHODS: Sixty-one healthy female volunteers, ages ranging from 18 to 32 years. The nail polish colors used to evaluate SpO2 were: base coat on the little finger, light pink on the ring finger, sparkling light pink on the medium finger and red on the thumb. The index finger was used as control

  7. Evaluación sensorial de láminas de mango (Manguifera indica L. cv. Keitt fortificadas con cloruro de calcio mediante deshidratación osmótica con pulsos de vacío

    Directory of Open Access Journals (Sweden)

    Richard Alejandro Gómez

    2013-12-01

    Full Text Available Se evaluó el efecto de la fortificación con cloruro de calcio (CaCl2 de láminas de mango por medio de la deshidratación osmótica con pulsos de vacío, sobre los atributos sensoriales color, sabor y textura (dureza. Se utilizaron frutos de mango del cultivar Keitt cosechados en estado de madurez fisiológica a partir de los cuales se obtuvieron láminas de 4 x 4 x 0,5 cm. Las láminas de mango se sometieron a 4 tratamientos osmóticos que incluían distintas soluciones con concentraciones de CaCl2 (0; 0,5; 1,5 y 2,5 %, durante 24 horas, aplicando pulsos de vacío. La preferencia de las láminas de mango fortificadas se determinó utilizando una escala hedónica de 9 puntos (desde 9: ‘gusta extremadamente’, pasando por 5: ‘ni gusta ni disgusta’, hasta 1: ‘disgusta extremadamente’. En la prueba participó un panel de 100 consumidores no entrenados, de ambos sexos y con edades entre 18 y 50 años. A cada panelista se les entregó simultáneamente 4 muestras codificadas con números aleatorios de tres dígitos y se les pidió que probaran y calificaran los atributos color, sabor y textura (dureza, según su apreciación y de acuerdo a la escala. Para el análisis de los datos se utilizó el análisis no paramétrico de Kruskal-Wallis. Las diferencias entre los tratamientos se determinaron mediante una prueba de rangos. Se aplicó un análisis de correlación entre las variables sensoriales a través de la prueba de rangos de Spearman. El panel detectó que el color de las láminas sometidas al tratamiento con 2,5 % CaCl2 varió significativamente (p ≤ 0,01 con relación a los demás. Un aumento de la concentración de CaCl2 hizo más amargas y duras las láminas de mango. Hubo correlación altamente positiva entre la preferencia del sabor y la dureza y con el color de las muestras. Las láminas con 0 % CaCl2 fueron las más aceptadas a nivel sensorial, pero para la fortificación con calcio las de mayor aceptabilidad fueron las

  8. Evaluación sensorial de láminas de mango (Manguifera indica L. cv. Keitt fortificadas con cloruro de calcio mediante deshidratación osmótica con pulsos de vacío

    Directory of Open Access Journals (Sweden)

    Richard Alejandro Gómez

    2013-12-01

    Full Text Available Se evaluó el efecto de la fortificación con cloruro de calcio (CaCl2 de láminas de mango por medio de la deshidratación osmótica con pulsos de vacío, sobre los atributos sensoriales color, sabor y textura (dureza. Se utilizaron frutos de mango del cultivar Keitt cosechados en estado de madurez fisiológica a partir de los cuales se obtuvieron láminas de 4 x 4 x 0,5 cm. Las láminas de mango se sometieron a 4 tratamientos osmóticos que incluían distintas soluciones con concentraciones de CaCl2 (0; 0,5; 1,5 y 2,5 %, durante 24 horas, aplicando pulsos de vacío. La preferencia de las láminas de mango fortificadas se determinó utilizando una escala hedónica de 9 puntos (desde 9: 'gusta extremadamente', pasando por 5: 'ni gusta ni disgusta', hasta 1: 'disgusta extremadamente'. En la prueba participó un panel de 100 consumidores no entrenados, de ambos sexos y con edades entre 18 y 50 años. A cada panelista se les entregó simultáneamente 4 muestras codificadas con números aleatorios de tres dígitos y se les pidió que probaran y calificaran los atributos color, sabor y textura (dureza, según su apreciación y de acuerdo a la escala. Para el análisis de los datos se utilizó el análisis no paramétrico de Kruskal-Wallis. Las diferencias entre los tratamientos se determinaron mediante una prueba de rangos. Se aplicó un análisis de correlación entre las variables sensoriales a través de la prueba de rangos de Spearman. El panel detectó que el color de las láminas sometidas al tratamiento con 2,5 % CaCl2 varió significativamente (p ≤ 0,01 con relación a los demás. Un aumento de la concentración de CaCl2 hizo más amargas y duras las láminas de mango. Hubo correlación altamente positiva entre la preferencia del sabor y la dureza y con el color de las muestras. Las láminas con 0 % CaCl2 fueron las más aceptadas a nivel sensorial, pero para la fortificación con calcio las de mayor aceptabilidad fueron las sometidas a los

  9. Mechanical models of amplitude and frequency modulation

    Energy Technology Data Exchange (ETDEWEB)

    Bellomonte, L; Guastella, I; Sperandeo-Mineo, R M [GRIAF - Research Group on Teaching/Learning Physics, DI.F.TE.R. -Dipartimento di Fisica e Tecnologie Relative, University of Palermo, Viale delle Scienze, Edificio 18, 90128 Palermo (Italy)

    2005-05-01

    This paper presents some mechanical models for amplitude and frequency modulation. The equations governing both modulations are deduced alongside some necessary approximations. Computer simulations of the models are carried out by using available educational software. Amplitude modulation is achieved by using a system of two weakly coupled pendulums, whereas the frequency modulation is obtained by using a pendulum of variable length. Under suitable conditions (small oscillations, appropriate initial conditions, etc) both types of modulation result in significantly accurate and visualized simulations.

  10. Simple parametrization of the. pi. -N amplitude

    Energy Technology Data Exchange (ETDEWEB)

    McLeod, R.J.; Afnan, I.R.

    1985-07-01

    We present a simple parametrization of the S-, P-, and D-wave ..pi..-N amplitudes using separable potentials for T/sub ..pi../<1 GeV. The effect of the inelasticity is included in the Green's function while maintaining consistency with unitarity. The P/sub 11/ amplitude is written as a pole plus nonpole in order to describe pion absorption in A> or =2.

  11. Feynman amplitudes and limits of heights

    Science.gov (United States)

    Amini, O.; Bloch, S. J.; Burgos Gil, J. I.; Fresán, J.

    2016-10-01

    We investigate from a mathematical perspective how Feynman amplitudes appear in the low-energy limit of string amplitudes. In this paper, we prove the convergence of the integrands. We derive this from results describing the asymptotic behaviour of the height pairing between degree-zero divisors, as a family of curves degenerates. These are obtained by means of the nilpotent orbit theorem in Hodge theory.

  12. Nucleon distribution amplitudes from lattice QCD

    Energy Technology Data Exchange (ETDEWEB)

    Goeckeler, M. [Regensburg Univ. (Germany). Inst. fuer Theoretische Physik; Horsley, R. [Edinburgh Univ. (United Kingdom). School of Physics; Kaltenbrunner, T. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (DE). John von Neumann-Inst. fuer Computing NIC] (and others)

    2008-04-15

    We calculate low moments of the leading-twist and next-to-leading twist nucleon distribution amplitudes on the lattice using two flavors of clover fermions. The results are presented in the MS scheme at a scale of 2 GeV and can be immediately applied in phenomenological studies. We find that the deviation of the leading-twist nucleon distribution amplitude from its asymptotic form is less pronounced than sometimes claimed in the literature. (orig.)

  13. Vowel identification by amplitude and phase contrast.

    Science.gov (United States)

    Molis, Michelle R; Diedesch, Anna; Gallun, Frederick; Leek, Marjorie R

    2013-02-01

    Vowel identification is largely dependent on listeners' access to the frequency of two or three peaks in the amplitude spectrum. Earlier work has demonstrated that, whereas normal-hearing listeners can identify harmonic complexes with vowel-like spectral shapes even with very little amplitude contrast between "formant" components and remaining harmonic components, listeners with hearing loss require greater amplitude differences. This is likely the result of the poor frequency resolution that often accompanies hearing loss. Here, we describe an additional acoustic dimension for emphasizing formant versus non-formant harmonics that may supplement amplitude contrast information. The purpose of this study was to determine whether listeners were able to identify "vowel-like" sounds using temporal (component phase) contrast, which may be less affected by cochlear loss than spectral cues, and whether overall identification improves when congruent temporal and spectral information are provided together. Five normal-hearing and five hearing-impaired listeners identified three vowels over many presentations. Harmonics representing formant peaks were varied in amplitude, phase, or a combination of both. In addition to requiring less amplitude contrast, normal-hearing listeners could accurately identify the sounds with less phase contrast than required by people with hearing loss. However, both normal-hearing and hearing-impaired groups demonstrated the ability to identify vowel-like sounds based solely on component phase shifts, with no amplitude contrast information, and they also showed improved performance when congruent phase and amplitude cues were combined. For nearly all listeners, the combination of spectral and temporal information improved identification in comparison to either dimension alone.

  14. Employing Helicity Amplitudes for Resummation in SCET

    CERN Document Server

    Moult, Ian; Tackmann, Frank J; Waalewijn, Wouter J

    2016-01-01

    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.

  15. Quartic amplitudes for Minkowski higher spin

    CERN Document Server

    Bengtsson, Anders K H

    2016-01-01

    The problem of finding general quartic interaction terms between fields of higher helicities on the light-front is discussed from the point of view of calculating the corresponding amplitudes directly from the cubic vertices using BCFW recursion. Amplitude based no-go results that has appeared in the literature are reviewed and discussed and it is pointed out how they may perhaps be circumvented.

  16. Amplitude metrics for cellular circadian bioluminescence reporters.

    Science.gov (United States)

    St John, Peter C; Taylor, Stephanie R; Abel, John H; Doyle, Francis J

    2014-12-01

    Bioluminescence rhythms from cellular reporters have become the most common method used to quantify oscillations in circadian gene expression. These experimental systems can reveal phase and amplitude change resulting from circadian disturbances, and can be used in conjunction with mathematical models to lend further insight into the mechanistic basis of clock amplitude regulation. However, bioluminescence experiments track the mean output from thousands of noisy, uncoupled oscillators, obscuring the direct effect of a given stimulus on the genetic regulatory network. In many cases, it is unclear whether changes in amplitude are due to individual changes in gene expression level or to a change in coherence of the population. Although such systems can be modeled using explicit stochastic simulations, these models are computationally cumbersome and limit analytical insight into the mechanisms of amplitude change. We therefore develop theoretical and computational tools to approximate the mean expression level in large populations of noninteracting oscillators, and further define computationally efficient amplitude response calculations to describe phase-dependent amplitude change. At the single-cell level, a mechanistic nonlinear ordinary differential equation model is used to calculate the transient response of each cell to a perturbation, whereas population-level dynamics are captured by coupling this detailed model to a phase density function. Our analysis reveals that amplitude changes mediated at either the individual-cell or the population level can be distinguished in tissue-level bioluminescence data without the need for single-cell measurements. We demonstrate the effectiveness of the method by modeling experimental bioluminescence profiles of light-sensitive fibroblasts, reconciling the conclusions of two seemingly contradictory studies. This modeling framework allows a direct comparison between in vitro bioluminescence experiments and in silico ordinary

  17. 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)

  18. Amplitude Modulations of Acoustic Communication Signals

    Science.gov (United States)

    Turesson, Hjalmar K.

    2011-12-01

    In human speech, amplitude modulations at 3 -- 8 Hz are important for discrimination and detection. Two different neurophysiological theories have been proposed to explain this effect. The first theory proposes that, as a consequence of neocortical synaptic dynamics, signals that are amplitude modulated at 3 -- 8 Hz are propagated better than un-modulated signals, or signals modulated above 8 Hz. This suggests that neural activity elicited by vocalizations modulated at 3 -- 8 Hz is optimally transmitted, and the vocalizations better discriminated and detected. The second theory proposes that 3 -- 8 Hz amplitude modulations interact with spontaneous neocortical oscillations. Specifically, vocalizations modulated at 3 -- 8 Hz entrain local populations of neurons, which in turn, modulate the amplitude of high frequency gamma oscillations. This suggests that vocalizations modulated at 3 -- 8 Hz should induce stronger cross-frequency coupling. Similar to human speech, we found that macaque monkey vocalizations also are amplitude modulated between 3 and 8 Hz. Humans and macaque monkeys share similarities in vocal production, implying that the auditory systems subserving perception of acoustic communication signals also share similarities. Based on the similarities between human speech and macaque monkey vocalizations, we addressed how amplitude modulated vocalizations are processed in the auditory cortex of macaque monkeys, and what behavioral relevance modulations may have. Recording single neuron activity, as well as, the activity of local populations of neurons allowed us to test both of the neurophysiological theories presented above. We found that single neuron responses to vocalizations amplitude modulated at 3 -- 8 Hz resulted in better stimulus discrimination than vocalizations lacking 3 -- 8 Hz modulations, and that the effect most likely was mediated by synaptic dynamics. In contrast, we failed to find support for the oscillation-based model proposing a

  19. Palavras dos editores

    Directory of Open Access Journals (Sweden)

    Nelkis de la Orden Medina

    2005-12-01

    Full Text Available Este número da revista RESI está sendo editado em conjunto por mim e pelo novo editor Jorge Muniz Barreto. A revista tem agora nova sede, o Departamento de Informática e de Estatística da Universidade Federal de Santa Catarina. No que a me diz respeito, tenho a satisfação após estes 4 anos de trabalho de ter contribuído no lançamento e consolidação da revista, a qual considero uma ferramenta útil no âmbito universitário. Agradeço a todos os que fizeram possível a realização deste projeto: aos membros do conselho editorial, ao corpo de avaliadores e principalmente aos autores de trabalhos publicados. Gostaria de agradecer ao novo editor sua excelente disposição para aceitar este desafio e lhe desejo uma gestão editorial de muito sucesso. Tenho a certeza que estamos iniciando uma nova etapa da revista que permitirá um crescimento maior da mesma, na qual continuaremos a colaborar de forma permanente. Campo Largo, dezembro de 2005. Nelkis de la Orden Medina, Editora-Chefe. Repletos de idealismo iniciamos com a edição 6 da Revista Eletrônica de Sistemas de Informação nossa atuação como Editor-Chefe. Esperamos honrar os sucessos obtidos pela revista nos cinco números anteriores, e tornar RESI, cada vez mais útil a seus leitores. Para isto temos planos e contamos além do Conselho Editorial e Revisores, ouvir também a opinião dos leitores de modo informal. Para isto criamos um MSN-Space onde os leitores poderão colocar suas sugestões (operacional e conhecer alguns membros tanto do conselho como revisores. Para vê-lo acessem:http://spaces.msn.com/members/resireveletron Os trabalhos apresentados dão continuidade ao estilo das edições anteriores. São seis artigos, abordando assuntos relacionados à Sistemas de Informação. Estes artigos enriquecem o acervo de trabalhos publicados na revista RESI e mostram o panorama das pesquisas que estão sendo desenvolvidas no Brasil e países amigos. Dentre os planos para o ano

  20. Ligadura de ducto arterioso persistente en un cocker spaniel de dos meses de edad: reporte de caso

    Directory of Open Access Journals (Sweden)

    Ximena Escobar Correa

    2016-06-01

    Full Text Available El presente artículo reporta el caso de una hembra canina cocker spaniel entera de dos meses de edad, que fue llevada a la Clínica para Pequeños Animales de la Universidad Nacional de Colombia, con tos de seis días de evolución, poca ganancia de peso e historial de soplo cardiaco detectado con anterioridad en un centro veterinario. Tras realizar el examen médico, se perciben estertores en ambos campos pulmonares, aumento del reflejo tusígeno, pulso yugular positivo, un soplo cardiaco 6/6 y aumento del tiempo de llenado capilar. Se diagnostica la persistencia de ducto arterioso mediante ecocardiografía, por lo cual se plantea la ligadura del ducto como tratamiento definitivo. La paciente se recuperó satisfactoriamente del procedimiento quirúrgico sin tener ningún tipo de complicación; en el postoperatorio presentó tos que se resolvió a los pocos días con ayuda de un tratamiento con furosemida (2 mg/kg TID IM. Tres meses después de realizarse el procedimiento quirúrgico la paciente se encontraba clínicamente sana, sin ninguna manifestación de origen cardiaco.

  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. Spinfoam cosmology with the proper vertex amplitude

    CERN Document Server

    Vilensky, Ilya

    2016-01-01

    The proper vertex amplitude is derived from the EPRL 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.

  3. A description of seismic amplitude techniques

    Science.gov (United States)

    Shadlow, James

    2014-02-01

    The acquisition of seismic data is a non-invasive technique used for determining the sub surface geology. Changes in lithology and fluid fill affect the seismic wavelet. Analysing seismic data for direct hydrocarbon indicators (DHIs), such as full stack amplitude anomalies, or amplitude variation with offset (AVO), can help a seismic interpreter relate the geophysical response to real geology and, more importantly, to distinguish the presence of hydrocarbons. Inversion is another commonly used technique that attempts to tie the seismic data back to the geology. Much has been written about these techniques, and attempting to gain an understanding on the theory and application of them by reading through various journals can be quite daunting. The purpose of this paper is to briefly outline DHI analysis, including full stack amplitude anomalies, AVO and inversion and show the relationship between all three. The equations presented have been included for completeness, but the reader can pass over the mathematical detail.

  4. Scattering Amplitudes and Worldsheet Models of QFTs

    CERN Document Server

    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.

  5. Analytic representations of Yang-Mills amplitudes

    Science.gov (United States)

    Bjerrum-Bohr, N. E. J.; Bourjaily, Jacob L.; Damgaard, Poul H.; Feng, Bo

    2016-12-01

    Scattering amplitudes in Yang-Mills theory can be represented in the formalism of Cachazo, He and Yuan (CHY) as integrals over an auxiliary projective space-fully localized on the support of the scattering equations. Because solving the scattering equations is difficult and summing over the solutions algebraically complex, a method of directly integrating the terms that appear in this representation has long been sought. We solve this important open problem by first rewriting the terms in a manifestly Möbius-invariant form and then using monodromy relations (inspired by analogy to string theory) to decompose terms into those for which combinatorial rules of integration are known. The result is the foundations of a systematic procedure to obtain analytic, covariant forms of Yang-Mills tree-amplitudes for any number of external legs and in any number of dimensions. As examples, we provide compact analytic expressions for amplitudes involving up to six gluons of arbitrary helicities.

  6. 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...

  7. Speech production in amplitude-modulated noise

    DEFF Research Database (Denmark)

    Macdonald, Ewen N; Raufer, Stefan

    2013-01-01

    The Lombard effect refers to the phenomenon where talkers automatically increase their level of speech in a noisy environment. While many studies have characterized how the Lombard effect influences different measures of speech production (e.g., F0, spectral tilt, etc.), few have investigated...... 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...

  8. 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...

  9. On Arbitrary Phases in Quantum Amplitude Amplification

    CERN Document Server

    Hoyer, P

    2000-01-01

    We consider the use of arbitrary phases in quantum amplitude amplification which is a generalization of quantum searching. We prove that the phase condition in amplitude amplification is given by $\\tan(\\phi/2)=\\tan(\\phi/2)(1-2a)$, where $\\phi$ and $\\phi$ are the phases used and where $a$ is the success probability of the given algorithm. Thus the choice of phases depends nontrivially and nonlinearly on the success probability. Utilizing this condition, we give methods for constructing quantum algorithms that succeed with certainty and for implementing arbitrary rotations. We also conclude that phase errors of order up to $\\frac{1}{\\sqrt{a}}$ can be tolerated in amplitude amplification.

  10. Nonlinear (Super)Symmetries and Amplitudes

    CERN Document Server

    Kallosh, Renata

    2016-01-01

    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_{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\\geq 5 supergravity, to the D3 brane, and the UV completion of constrained multiplets in string theory.

  11. Analytic Representations of Yang-Mills Amplitudes

    CERN Document Server

    Bjerrum-Bohr, N E J; Damgaard, Poul H; Feng, Bo

    2016-01-01

    Scattering amplitudes in Yang-Mills theory can be represented in the formalism of Cachazo, He and Yuan (CHY) as integrals over an auxiliary projective space---fully localized on the support of the scattering equations. Because solving the scattering equations is difficult and summing over the solutions algebraically complex, a method of directly integrating the terms that appear in this representation has long been sought. We solve this important open problem by first rewriting the terms in a manifestly Mobius-invariant form and then using monodromy relations (inspired by analogy to string theory) to decompose terms into those for which combinatorial rules of integration are known. The result is a systematic procedure to obtain analytic, covariant forms of Yang-Mills tree-amplitudes for any number of external legs and in any number of dimensions. As examples, we provide compact analytic expressions for amplitudes involving up to six gluons of arbitrary helicities.

  12. Modified π π amplitude with σ pole

    Science.gov (United States)

    Bydžovský, P.; Kamiński, R.; Nazari, V.

    2014-12-01

    A set of well-known once subtracted dispersion relations with imposed crossing symmetry condition is used to modify unitary multichannel S (π π , K K ¯, and η η ) and P (π π , ρ 2 π , and ρ σ ) wave amplitudes mostly below 1 GeV. Before the modifications, these amplitudes significantly did not satisfy the crossing symmetry condition and did not describe the π π threshold region. Moreover, the pole of the S wave amplitude related with the f0(500 ) meson (former f0(600 ) or σ ) had much smaller imaginary part and bigger real one in comparison with those in the newest Particle Data Group Tables. Here, these amplitudes are supplemented by near threshold expansion polynomials and refitted to the experimental data in the effective two pion mass from the threshold to 1.8 GeV and to the dispersion relations up to 1.1 GeV. In result the self consistent, i.e., unitary and fulfilling the crossing symmetry condition, S and P wave amplitudes are formed and the σ pole becomes much narrower and lighter. To eliminate doubts about the uniqueness of the so obtained sigma pole position short and purely mathematical proof of the uniqueness of the results is also presented. This analysis is addressed to a wide group of physicists and aims at providing a very effective and easy method of modification of, many presently used, π π amplitudes with a heavy and broad σ meson without changing of their original mathematical structure.

  13. 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.

  14. Topographic quantitative EEG amplitude in recovered alcoholics.

    Science.gov (United States)

    Pollock, V E; Schneider, L S; Zemansky, M F; Gleason, R P; Pawluczyk, S

    1992-05-01

    Topographic measures of electroencephalographic (EEG) amplitude were used to compare recovered alcoholics (n = 14) with sex- and age-matched control subjects. Delta, alpha, and beta activity did not distinguish the groups, but regional differences in theta distribution did. Recovered alcoholics showed more uniform distributions of theta amplitudes in bilateral anterior and posterior regions compared with controls. Because a minimum of 5 years had elapsed since the recovered alcoholic subjects fulfilled DSM-III-R criteria for alcohol abuse or dependence, it is unlikely these EEG theta differences reflect the effects of withdrawal.

  15. 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.

  16. 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 initial tensile strength and the fatigue life, the probability distributions for the residual tensile strength in both the crack initiation and the crack propagation stages of fatigue are determined. The method is illustrated for two-amplitude loads by means of experimental results obtained by testing...

  17. Probability amplitude in quantum like games

    CERN Document Server

    Grib, A A; Starkov, K

    2003-01-01

    Examples of games between two partners with mixed strategies, calculated by the use of the probability amplitude are given. The first game is described by the quantum formalism of spin one half system for which two noncommuting observables are measured. The second game corresponds to the spin one case. Quantum logical orthocomplemented nondistributive lattices for these two games are presented. Interference terms for the probability amplitudes are analyzed by using so called contextual approach to probability (in the von Mises frequency approach). We underline that our games are not based on using of some microscopic systems. The whole scenario is macroscopic.

  18. 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)....

  19. New structures in scattering amplitudes: A review

    Science.gov (United States)

    Benincasa, Paolo

    2014-02-01

    We review some recent developments in the understanding of field theories in the perturbative regime. In particular, we discuss the notions of analyticity, unitarity and locality, and therefore the singularity structure of scattering amplitudes in general interacting theories. We describe their tree-level structure and their on-shell representations, as well as the links between the tree-level structure itself and the structure of the loop amplitudes. Finally, we describe the on-shell diagrammatics recently proposed both on general grounds and in the remarkable example of planar supersymmetric theories.

  20. DOS cones along atomic chains

    Science.gov (United States)

    Kwapiński, Tomasz

    2017-03-01

    The electron transport properties of a linear atomic chain are studied theoretically within the tight-binding Hamiltonian and the Green’s function method. Variations of the local density of states (DOS) along the chain are investigated. They are crucial in scanning tunnelling experiments and give important insight into the electron transport mechanism and charge distribution inside chains. It is found that depending on the chain parity the local DOS at the Fermi level can form cone-like structures (DOS cones) along the chain. The general condition for the local DOS oscillations is obtained and the linear behaviour of the local density function is confirmed analytically. DOS cones are characterized by a linear decay towards the chain which is in contrast to the propagation properties of charge density waves, end states and Friedel oscillations in one-dimensional systems. We find that DOS cones can appear due to non-resonant electron transport, the spin–orbit scattering or for chains fabricated on a substrate with localized electrons. It is also shown that for imperfect chains (e.g. with a reduced coupling strength between two neighboring sites) a diamond-like structure of the local DOS along the chain appears.

  1. ANÁLISE DO CONTEÚDO INFORMATIVO DOS PARECERES DOS AUDITORES DOS TRIBUNAIS DE CONTAS DOS ESTADOS BRASILEIROS

    Directory of Open Access Journals (Sweden)

    Francisca Francivânia Rodrigues

    2014-09-01

    Full Text Available Este estudo objetiva descrever o conteúdo informativo dos pareceres prévios emitidos pelos auditores dos tribunais de contas dos estados brasileiros divulgados no período de 2008 a 2010. Para isso, realiza-se um estudo descritivo, com abordagem predominantemente qualitativa, por meio de pesquisa documental e análise de conteúdo, com consultas aos sites oficiais dos tribunais de contas estaduais. O universo da pesquisa corresponde às 27 unidades federativas do Brasil, excluídas aquelas que não possuíam nos sites oficiais de seus tribunais de contas todas as informações propostas para o estudo - tratando-se dos estados do Acre, Amapá, Rondônia, Roraima, Maranhão e Piauí -, resultando em uma amostra de 21 unidades federativas. Os resultados apontam que os tribunais de contas dos estados das regiões Centro-Oeste, Sudeste e Sul apresentaram maior assiduidade quanto à divulgação do parecer de auditoria nos seus sites. Verifica-se, também, que há inúmeras ordenações feitas pelos auditores aos órgãos públicos no que concerne à aplicação das normas referentes à contabilidade do setor público. Ao final, conclui-se que existem divergências no conteúdo informacional dos pareceres prévios dos tribunais de contas dos estados brasileiros, embora tratem de matéria similar. Vê-se, também, que os gestores públicos das unidades federativas do Brasil descumpriram, em alguns quesitos, a Lei nº 4.320/1964, a Lei nº 101/2000 e a Constituição Federal.

  2. Dos chalets, en Suecia

    Directory of Open Access Journals (Sweden)

    Erskine, Ralph

    1968-04-01

    Full Text Available Villa Engström, at Sorunda This house, of semi-spheric shape, has besically only one floor level, without basement. However, the guest room and the attic are a kind of second floor within the cupula. This is an experiment, with a view to the possible mass construction of this prototype. The various rooms are grouped in two blocks, one comprising the bedrooms, which are cellular type and of minimum size, and the bathrooms; the other includes the children's room, a living room which extends into the vestibule, and guest room at a higher level. Villa Ström, near Stockholm This house is practically cube shaped, with ample terraces, which are structurally independent of the central volume. A principal aim has been to obtain fine views in all directions, and also to take advantage of the ground slope. This house, of original and competent design, includes indoor gardens which add colour and life to the rooms.Villa Engström, en Sorunda Esta vivienda, que presenta una «forma» semiesferica, es fundamentalmente un edificio de una sola planta, sin sótano; sin embargo, el cuarto de huéspedes y el «ático» forman como una especie de doble planta dentro de la cúpula. Se trata de una experiencia con vistas a una posible fabricación en serie. Las diferentes habitaciones se hallan agrupadas en dos bloques: uno de ellos ocupado por los dormitorios —que son de tipo celular y de tamaño mínimo—, y los cuartos de baño; y el otro que comprende un cuarto para los niños, la sala de estar —unida con el vestíbulo—, y la habitación de los huéspedes en la parte superior. Villa Ström, cerca de Estocolmo La casa es prácticamente un cubo, con terrazas amplias e independientes estructuralmente del volumen principal. En todo caso, ha dominado la doble preocupación de conseguir magníficas vistas hacia todos los alrededores y una adaptación total a la pendiente del terreno. La vivienda se ha resuelto con maestría y originalidad, procurando zonas

  3. Amplitude ratios in ρ0 leptoproductions and GPDs

    Directory of Open Access Journals (Sweden)

    Goloskokov S.V.

    2017-01-01

    Using the model results we calculate the ratio of different helicity amplitudes for a transversely polarized proton target to the leading twist longitudinal amplitude. Our results are close to the amplitude ratios measured by HERMES.

  4. Effect Of Vibration Amplitude Level On Seated Occupant Reaction Time

    National Research Council Canada - National Science Library

    Amzar Azizan; Ratchaphon Ittianuwat; Zhengqing Liu

    2015-01-01

    ... r.m.s for each volunteer. Seated volunteers were exposed to Gaussian random vibration with frequency band 1-15 Hz at two level of amplitude low vibration amplitude and medium vibration amplitude for 20-minutes in separate days...

  5. 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 am...

  6. Connected formulas for amplitudes in standard model

    Science.gov (United States)

    He, Song; Zhang, Yong

    2017-03-01

    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.

  7. Audio steganography by amplitude or phase modification

    Science.gov (United States)

    Gopalan, Kaliappan; Wenndt, Stanley J.; Adams, Scott F.; Haddad, Darren M.

    2003-06-01

    This paper presents the results of embedding short covert message utterances on a host, or cover, utterance by modifying the phase or amplitude of perceptually masked or significant regions of the host. In the first method, the absolute phase at selected, perceptually masked frequency indices was changed to fixed, covert data-dependent values. Embedded bits were retrieved at the receiver from the phase at the selected frequency indices. Tests on embedding a GSM-coded covert utterance on clean and noisy host utterances showed no noticeable difference in the stego compared to the hosts in speech quality or spectrogram. A bit error rate of 2 out of 2800 was observed for a clean host utterance while no error occurred for a noisy host. In the second method, the absolute phase of 10 or fewer perceptually significant points in the host was set in accordance with covert data. This resulted in a stego with successful data retrieval and a slightly noticeable degradation in speech quality. Modifying the amplitude of perceptually significant points caused perceptible differences in the stego even with small changes of amplitude made at five points per frame. Finally, the stego obtained by altering the amplitude at perceptually masked points showed barely noticeable differences and excellent data recovery.

  8. Hyperlogarithms and periods in Feynman amplitudes

    CERN Document Server

    Todorov, Ivan

    2016-01-01

    The role of hyperlogarithms and multiple zeta values (and their generalizations) in Feynman amplitudes is being gradually recognized since the mid 1990's. The present lecture provides a concise introduction to a fast developing subjects that attracts the attention to a wide range of specialists - from number theorists to particle physicists.

  9. Polynomial structures in one-loop amplitudes

    NARCIS (Netherlands)

    Britto, R.; Feng, B.; Yang, G.

    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 (4-2epsilon)-dimensional master integrals; these formulas

  10. Integral coefficients for one-loop amplitudes

    NARCIS (Netherlands)

    Britto, R.; Feng, B.

    2008-01-01

    We present a set of algebraic functions for evaluating the coefficients of the scalar integral basis of a general one-loop amplitude. The functions are derived from unitarity cuts, but the complete cut-integral procedure has been carried out in generality so that it never needs to be repeated. Where

  11. Amplitude Correction Factors of KVN Observations

    CERN Document Server

    Lee, Sang-Sung; Oh, Chung Sik; Kim, Hyo Ryoung; Kim, Jongsoo; Jung, Taehyun; Oh, Se-Jin; Roh, Duk-Gyoo; Jung, Dong-Kyu; Yeom, Jae-Hwan

    2015-01-01

    We report results of investigation of amplitude calibration for very long baseline interferometry (VLBI) observations with Korean VLBI Network (KVN). Amplitude correction factors are estimated based on comparison of KVN observations at 22~GHz correlated by Daejeon hardware correlator and DiFX software correlator in Korea Astronomy and Space Science Institute (KASI) with Very Long Baseline Array (VLBA) observations at 22~GHz by DiFX software correlator in National Radio Astronomy Observatory (NRAO). We used the observations for compact radio sources, 3C~454.3 and NRAO~512, which are almost unresolved for baselines in a range of 350-477~km. Visibility data of the sources obtained with similar baselines at KVN and VLBA are selected, fringe-fitted, calibrated, and compared for their amplitudes. We found that visibility amplitudes of KVN observations should be corrected by factors of 1.10 and 1.35 when correlated by DiFX and Daejeon correlators, respectively. These correction factors are attributed to the combinat...

  12. Holographic corrections to the Veneziano amplitude

    Science.gov (United States)

    Armoni, Adi; Ireson, Edwin

    2017-08-01

    We propose a holographic computation of the 2 → 2 meson scattering in a curved string background, dual to a QCD-like theory. We recover the Veneziano amplitude and compute a perturbative correction due to the background curvature. The result implies a small deviation from a linear trajectory, which is a requirement of the UV regime of QCD.

  13. The CMU Baryon Amplitude Analysis Program

    Science.gov (United States)

    Bellis, Matt

    2007-05-01

    The PWA group at Carnegie Mellon University has developed a comprehensive approach and analysis package for the purpose of extracting the amplitudes for photoproduced baryon resonances. The end goal is to identify any missing resonances that are predicted by the constituent quark model, but not definitively observed in experiments. The data comes from the CEBAF Large Acceptance Spectrometer (CLAS) at Jefferson Lab.

  14. Generalised Unitarity for Dimensionally Regulated Amplitudes

    CERN Document Server

    Bobadilla, W J Torres; Mastrolia, P; Mirabella, E

    2015-01-01

    We present a novel set of Feynman rules and generalised unitarity cut-conditions for computing one-loop amplitudes via d-dimensional integrand reduction algorithm. Our algorithm is suited for analytic as well as numerical result, because all ingredients turn out to have a four-dimensional representation. We will apply this formalism to NLO QCD corrections.

  15. Consonant confusions in amplitude-expanded speech.

    Science.gov (United States)

    Freyman, R L; Nerbonne, G P

    1996-12-01

    The perceptual consequences of expanding the amplitude variations in speech were studied under conditions in which spectral information was obscured by signal correlated noise that had an envelope correlated with the speech envelope, but had a flat amplitude spectrum. The noise samples, created individually from 22 vowel-consonant-vowel nonsense words, were used as maskers of those words, with signal-to-noise ratios ranging from -15 to 0 dB. Amplitude expansion was by a factor of 3.0 in terms of decibels. In the first experiment, presentation level for speech peaks was 80 dB SPL. Consonant recognition performance for expanded speech by 50 listeners with normal hearing was as much as 30 percentage points poorer than for unexpanded speech and the types of errors were dramatically different, especially in the midrange of S-N ratios. In a second experiment presentation level was varied to determine whether reductions in consonant levels produced by expansion were responsible for the differences between conditions. Recognition performance for unexpanded speech at 40 dB SPL was nearly equivalent to that for expanded speech at 80 dB SPL. The error patterns obtained in these two conditions were different, suggesting that the differences between conditions in Experiment 1 were due largely to expanded amplitude envelopes rather than differences in audibility.

  16. 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 am...

  17. Particle Distribution Modification by Low Amplitude Modes

    Energy Technology Data Exchange (ETDEWEB)

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

    2009-08-28

    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.

  18. 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.

  19. Taming Tree Amplitudes In General Relativity

    CERN Document Server

    Benincasa, Paolo; Cachazo, Freddy; 10.1088/1126-6708/2007/11/057

    2008-01-01

    We give a proof of BCFW recursion relations for all tree-level amplitudes of gravitons in General Relativity. The proof follows the same basic steps as in the BCFW construction and it is an extension of the one given for next-to-MHV amplitudes by one of the authors and P. Svr\\v{c}ek in hep-th/0502160. The main obstacle to overcome is to prove that deformed graviton amplitudes vanish as the complex variable parameterizing the deformation is taken to infinity. This step is done by first proving an auxiliary recursion relation where the vanishing at infinity follows directly from a Feynman diagram analysis. The auxiliary recursion relation gives rise to a representation of gravity amplitudes where the vanishing under the BCFW deformation can be directly proven. Since all our steps are based only on Feynman diagrams, our proof completely establishes the validity of BCFW recursion relations. This means that many results in the literature that were derived assuming their validity become true statements.

  20. Taming tree amplitudes in general relativity

    Science.gov (United States)

    Benincasa, Paolo; Boucher-Veronneau, Camille; Cachazo, Freddy

    2007-11-01

    We give a proof of BCFW recursion relations for all tree-level amplitudes of gravitons in General Relativity. The proof follows the same basic steps as in the BCFW construction and it is an extension of the one given for next-to-MHV amplitudes by one of the authors and P. Svrcek in hep-th/0502160. The main obstacle to overcome is to prove that deformed graviton amplitudes vanish as the complex variable parameterizing the deformation is taken to infinity. This step is done by first proving an auxiliary recursion relation where the vanishing at infinity follows directly from a Feynman diagram analysis. The auxiliary recursion relation gives rise to a representation of gravity amplitudes where the vanishing under the BCFW deformation can be directly proven. Since all our steps are based only on Feynman diagrams, our proof completely establishes the validity of BCFW recursion relations. This means that many results in the literature that were derived assuming their validity become true statements.

  1. Estrategias reproductivas de la vegetación y sus respuestas al pulso de la inundación en las zonas inundables de la Amazonía Central

    Directory of Open Access Journals (Sweden)

    M.T.F. Piedade

    2010-01-01

    Full Text Available Los humedales o áreas que sufren largos períodos de inundaciones periódicas, asociadas a los grandes ríos, cubren aproximadamente el 6% de la Amazonia Brasileña. Precisamente en esta región se encuentran localizados los bosques inundados con mayor extensión y diversidad vegetal del mundo. En esos ambientes, la altura de la columna de agua puede fluctuar durante todo el año, llegando a valores promedio de hasta 10 m. La previsibilidad y duración del pulso de las inundaciones, la abrupta transición en las condiciones ambientales a lo largo del gradiente topográfico en los márgenes de los ríos principales y la intensidad de las corrientes de agua y la dinámica de los sedimentos representan una fuerte presión selectiva sobre las poblaciones de plantas y sus sistemas de reproducción. En este trabajo se examina y discute cómo el ciclo del agua influye en las estrategias de reproducción sexual y asexual que conducen a la realización del ciclo de vida de las plantas, permitiendo el mantenimiento de sus poblaciones. También se abordan las posibles restricciones sobre los procesos de germinación, el establecimiento de plántulas y la formación de bancos de semillas. Además, se indican algunas lagunas en el conocimiento existente sobre las estrategias reproductivas de la vegetación en las planicies de inundación de la Amazonía Central y se proponen líneas futuras de investigación. Se enfatiza en las especies herbáceas, debido a la gran variedad de formas de vida y estrategias reproductivas y su fuerte dinámica temporal y espacial en respuesta al ciclo hidrológico. El estudio de la vegetación de los ambientes inundados presentados aquí es relevante, especialmente, debido a los efectos previstos en las poblaciones de estas comunidades ante los escenarios de cambio climático previstos para la Amazonia.

  2. Quantitative laryngeal electromyography: turns and amplitude analysis.

    Science.gov (United States)

    Statham, Melissa McCarty; Rosen, Clark A; Nandedkar, Sanjeev D; Munin, Michael C

    2010-10-01

    Laryngeal electromyography (LEMG) is primarily a qualitative examination, with no standardized approach to interpretation. The objectives of our study were to establish quantitative norms for motor unit recruitment in controls and to compare with interference pattern analysis in patients with unilateral vocal fold paralysis (VFP). Retrospective case-control study We performed LEMG of the thyroarytenoid-lateral cricoarytenoid muscle complex (TA-LCA) in 21 controls and 16 patients with unilateral VFP. Our standardized protocol used a concentric needle electrode with subjects performing variable force TA-LCA contraction. To quantify the interference pattern density, we measured turns and mean amplitude per turn for ≥10 epochs (each 500 milliseconds). Logarithmic regression analysis between amplitude and turns was used to calculate slope and intercept. Standard deviation was calculated to further define the confidence interval, enabling generation of a linear-scale graphical "cloud" of activity containing ≥90% of data points for controls and patients. Median age of controls and patients was similar (50.7 vs. 48.5 years). In controls, TA-LCA amplitude with variable contraction ranged from 145-1112 μV, and regression analysis comparing mean amplitude per turn to root-mean-square amplitude demonstrated high correlation (R = 0.82). In controls performing variable contraction, median turns per second was significantly higher compared to patients (450 vs. 290, P = .002). We first present interference pattern analysis in the TA-LCA in healthy adults and patients with unilateral VFP. Our findings indicate that motor unit recruitment can be quantitatively measured within the TA-LCA. Additionally, patients with unilateral VFP had significantly reduced turns when compared with controls.

  3. ABJM amplitudes and the positive orthogonal Grassmannian

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Yu-tin [School of Natural Sciences, Institute for Advanced Study,Princeton, NJ 08540 (United States); Wen, CongKao [Centre for Research in String Theory, Department of Physics,Queen Mary University of London, Mile End Road, London E1 4NS (United Kingdom)

    2014-02-25

    A remarkable connection between perturbative scattering amplitudes of four dimensional planar SYM, and the stratification of the positive Grassmannian, was revealed in the seminal work of Arkani-Hamed et al. Similar extension for three-dimensional ABJM theory was proposed. Here we establish a direct connection between planar scattering amplitudes of ABJM theory, and singularities thereof, to the stratification of the positive orthogonal Grassmannian. In particular, scattering processes are constructed through on-shell diagrams, which are simply iterative gluing of the fundamental four-point amplitude. Each diagram is then equivalent to the merging of fundamental OG{sub 2} orthogonal Grassmannian to form a larger OG{sub k}, where 2k is the number of external particles. The invariant information that is encoded in each diagram is precisely this stratification. This information can be easily read off via permutation paths of the on-shell diagram, which also can be used to derive a canonical representation of OG{sub k} that manifests the vanishing of consecutive minors as the singularity of all on-shell diagrams. Quite remarkably, for the BCFW recursion representation of the tree-level amplitudes, the on-shell diagram manifests the presence of all physical factorization poles, as well as the cancellation of the spurious poles. After analytically continuing the orthogonal Grassmannian to split signature, we reveal that each on-shell diagram in fact resides in the positive cell of the orthogonal Grassmannian, where all minors are positive. In this language, the amplitudes of ABJM theory is simply an integral of a product of dlog forms, over the positive orthogonal Grassmannian.

  4. Eficacia de dos anestésicos tópicos, de uso dental, en pacientes pediátricos

    Directory of Open Access Journals (Sweden)

    MA Maldonado-Ramírez

    2017-03-01

    Full Text Available INTRODUCCIÓN: el dolor a la punción durante la anestesia dentallocal puede disminuir con ayuda de un anestésico tópico, evitando asociar la anestesia dental con el dolor. OBJETIVO: comparar la eficacia de dos anestésicos tópicos: a lidocaína/ prilocaína al 5% (parche y b benzocaína al 20% (gel para disminuir la sensibilidad a la punción en la mucosa oral.   MATERIALES Y MÉTODOS: se diseñó un estudio clínico comparativo con 60 pacientes entre 3 y 9 años de edad, divididos en dos grupos experimentales; la punción se realizó con aguja dental calibre 30. La intensidad del dolor se evaluó mediante la escala SEM (sound, eyes, motor contrastando los resultados con los cambios fisiológicos: saturación de oxígeno y pulso.   RESULTADOS: 60 niños de ambos géneros, de 3 a 9 años de edad, participaron en el estudio. La variable dolor-moderado se presentó en 15% de la población estudiada (9 participantes de los cuales 6 fueron femeninas y 3 masculinos, todos pertenecían al grupo benzocaína. El análisis estadístico arrojó una mayor eficacia de lidocaína/ prilocaína (P=0.025.   CONCLUSIONES: la aplicación de lidocaína/prilocaína al 5% es más eficaz para reducir el dolor que produce la punción de la aguja de anestesia dental.

  5. Amplitude Equations for Electrostatic Waves multiple species

    CERN Document Server

    Crawford, J D; Crawford, John David; Jayaraman, Anandhan

    1997-01-01

    The amplitude equation for an unstable electrostatic wave is analyzed using an expansion in the mode amplitude $A(t)$. In the limit of weak instability, i.e. $\\gamma\\to 0^+$ where $\\gamma$ is the linear growth rate, the nonlinear coefficients are singular and their singularities predict the dependence of $A(t)$ on $\\gamma$. Generically the scaling $|A(t)|=\\gamma^{5/2}r(\\gamma t)$ as orders. This result predicts the electric field scaling $|E_k|\\sim\\gamma^{5/2}$ will hold universally for these instabilities (including beam-plasma and two-stream configurations) throughout the dynamical evolution and in the time-asymptotic state. In exceptional cases, such as infinitely massive ions, the coefficients are less singular and the more familiar trapping scaling $|E_k|\\sim\\gamma^2$ is recovered.

  6. 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′.

  7. Differential equations, associators, and recurrences for amplitudes

    Science.gov (United States)

    Puhlfürst, Georg; Stieberger, Stephan

    2016-01-01

    We provide new methods to straightforwardly obtain compact and analytic expressions for ɛ-expansions of functions appearing in both field and string theory amplitudes. An algebraic method is presented to explicitly solve for recurrence relations connecting different ɛ-orders of a power series solution in ɛ 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 ɛ-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 ɛ-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. New structures in scattering amplitudes: a review

    CERN Document Server

    Benincasa, Paolo

    2013-01-01

    We review some recent developments in the understanding of field theories in the perturbative regime. In particular, we discuss the notions of analyticity, unitarity and locality, and therefore the singularity structure of scattering amplitudes in general interacting theories. We describe their tree-level structure and their on-shell representations, as well as the links between the tree-level structure itself and the structure of the loop amplitudes. Finally, we describe the on-shell diagrammatics recently proposed both on general grounds and in the remarkable example of planar supersymmetric theories. This review is partially based on lectures given at: Dipartimento di Fisica and INFN, Universit\\`a di Bologna; Departamento de F{\\i}sica de Part{\\i}culas, Universidade de Santiago de Compostela; and as part of the program Strings@ar Lectures on Advanced Topics of High Energy Physics held at the IAFE

  9. Differential Equations, Associators, and Recurrences for Amplitudes

    CERN Document Server

    Puhlfuerst, Georg

    2015-01-01

    We provide new methods to straightforwardly obtain compact and analytic expressions for epsilon-expansions of functions appearing in both field and string theory amplitudes. An algebraic method is presented to explicitly solve for recurrence relations connecting different epsilon-orders of a power series solution in epsilon 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 epsilon-expansion of specific generalized hypergeometric functions with the underlying Drinfeld associator with proper Lie algebra and monodromy representations. We also setup up our tools for computing epsilon-expansions for solutions to generic first-order Fuchsian equations (Schlesinger system). Finally, we apply our methods to systematically get compact and explicit alpha'-expansions of tree-level superstring amplitudes to any order in alpha'.

  10. Optical twists in phase and amplitude

    DEFF Research Database (Denmark)

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

    2011-01-01

    beams, the far field projection of the twisted optical beam maintains a high photon concentration even at higher values of topological charge. Optical twisters have therefore profound applications to fundamental studies of light and atoms such as in quantum entanglement of the OAM, toroidal traps......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...

  11. Multilayered models for electromagnetic reflection amplitudes

    Science.gov (United States)

    Linlor, W. I.

    1976-01-01

    The remote sensing of snowpack characteristics with surface installations or with an airborne system could have important applications in water resource management and flood prediction. To derive some insight into such applications, the electromagnetic response of multilayer snow models is analyzed. Normally incident plane waves are assumed at frequencies ranging from 10 to the 6th power to 10 to the 10th power Hz, and amplitude reflection coefficients are calculated for models having various snow-layer combinations, including ice sheets. Layers are defined by a thickness, permittivity, and conductivity; the electrical parameters are constant or prescribed functions of frequency. To illustrate the effect of various layering combinations, results are given in the form of curves of amplitude reflection coefficients, versus frequency for a variety of models. Under simplifying assumptions, the snow thickness and effective dielectric constant can be estimated from the reflection coefficient variations as a function of frequency.

  12. Integrable spin chains and scattering amplitudes

    Energy Technology Data Exchange (ETDEWEB)

    Bartels, J.; Prygarin, A. [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik; Lipatov, L.N. [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik; Petersburg Nuclear Physics Institute (Russian Federation); Sankt-Peterburgskij Univ., St. Petersburg (Russian Federation)

    2011-04-15

    In this review we show that the multi-particle scattering amplitudes in N=4 SYM at large N{sub c} and in the multi-Regge kinematics for some physical regions have the high energy behavior appearing from the contribution of the Mandelstam cuts in the complex angular momentum plane of the corresponding t-channel partial waves. These Mandelstam cuts or Regge cuts are resulting from gluon composite states in the adjoint representation of the gauge group SU(N{sub c}). In the leading logarithmic approximation (LLA) their contribution to the six point amplitude is in full agreement with the known two-loop result. The Hamiltonian for the Mandelstam states constructed from n gluons in LLA coincides with the local Hamiltonian of an integrable open spin chain. We construct the corresponding wave functions using the integrals of motion and the Baxter-Sklyanin approach. (orig.)

  13. On Triple-Cut of Scattering Amplitudes

    CERN Document Server

    Mastrolia, Pierpaolo

    2007-01-01

    It is analysed the triple-cut of one-loop amplitudes in dimensional regularisation within spinor-helicity representation. The triple-cut is defined as a difference of two double-cuts with the same particle content, and a same propagator carrying, respectively, causal and anti-causal prescription in each of the two cuts. That turns out into an effective tool for extracting the coefficients of the three-point functions (and higher-point ones) from one-loop-amplitudes. The phase-space integration is oversimplified by using residues theorem to perform the integration over the spinor variables, via the holomorphic anomaly, and a trivial integration on the Feynman parameter. The results are valid for arbitrary values of dimensions.

  14. Subleading Soft Factor for String Disk Amplitudes

    CERN Document Server

    Schwab, Burkhard U W

    2014-01-01

    We investigate the behavior of superstring disk scattering amplitudes in the presence of a soft external momentum at finite string tension. We prove that there are no $\\alpha'$-corrections to the field theory form of the subleading soft factor $S^{(1)}$. At the end of this work, we also comment on the possibility to find the corresponding subleading soft factors in closed string theory using our result and the KLT relations.

  15. Organizing Filament of Small Amplitude Scroll Waves

    Institute of Scientific and Technical Information of China (English)

    ZHOU TianShou; ZHANG SuoChun

    2001-01-01

    We theoretically analyze the organizing filament of small amplitude scroll waves in general excitable media by perturbation method and explicitly give the expressions of coefficients in Keener theory. In particular for the excitable media with equal diffusion, we obtain a close system for the motion of the filament. With an example of the Oregonator model, our results are in good agreement with those simulated by Winfree.``

  16. Ward identities for amplitudes with reggeized gluons

    Energy Technology Data Exchange (ETDEWEB)

    Bartles, J. [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik; Universidad Tecnica Federico Santa Maria, Valparaiso (Chile). Dept. de Fisica; Lipatov, L.N. [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik; St. Petersburg Nuclear Physics Institute (Russian Federation); Vacca, G.P. [INFN, Sezione di Bologna (Italy)

    2012-05-15

    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.

  17. Automation of 2-loop Amplitude Calculations

    CERN Document Server

    Jones, S P

    2016-01-01

    Some of the tools and techniques that have recently been used to compute Higgs boson pair production at NLO in QCD are discussed. The calculation relies on the use of integral reduction, to reduce the number of integrals which must be computed, and expressing the amplitude in terms of a quasi-finite basis, which simplifies their numeric evaluation. Emphasis is placed on sector decomposition and Quasi-Monte Carlo (QMC) integration which are used to numerically compute the master integrals.

  18. Automatic generation of tree level helicity amplitudes

    CERN Document Server

    Stelzer, T

    1994-01-01

    The program MadGraph is presented which automatically generates postscript Feynman diagrams and Fortran code to calculate arbitrary tree level helicity amplitudes by calling HELAS[1] subroutines. The program is written in Fortran and is available in Unix and VMS versions. MadGraph currently includes standard model interactions of QCD and QFD, but is easily modified to include additional models such as supersymmetry.

  19. Nucleon and $N^* (1535)$ Distribution Amplitudes

    CERN Document Server

    Braun, V M; Göckeler, M; Hagen, C; Horsley, R; Nakamura, Y; Pleiter, D; Rakow, P E L; Schäfer, A; Schiel, R W; Schierholz, G; Stüben, H; Zanotti, J M

    2010-01-01

    The QCDSF collaboration has investigated the distribution amplitudes and wavefunction normalization constants of the nucleon and its parity partner, the $N^* (1535)$. We report on recent progress in the calculation of these quantities on configurations with two dynamical flavors of $\\mathcal{O}(a)$-improved Wilson fermions. New data at pion masses of approximately 270 MeV helps in significantly reducing errors in the extrapolation to the physical point.

  20. 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...

  1. Connecting physical resonant amplitudes and lattice QCD

    CERN Document Server

    Bolton, Daniel R; Wilson, David J

    2015-01-01

    We present a determination of the isovector, $P$-wave $\\pi\\pi$ scattering phase shift obtained by extrapolating recent lattice QCD results from the Hadron Spectrum Collaboration using $m_\\pi =236$ MeV. The finite volume spectra are described using extensions of L\\"uscher's method to determine the infinite volume Unitarized Chiral Perturbation Theory scattering amplitude. We exploit the pion mass dependence of this effective theory to obtain the scattering amplitude at $m_\\pi= 140$ MeV. The scattering phase shift is found to be in good agreement with experiment up to center of mass energies of 1.2 GeV. The analytic continuation of the scattering amplitude to the complex plane yields a $\\rho$-resonance pole at $E_\\rho= \\left[755(2)(1)(^{20}_{02})-\\frac{i}{2}\\,129(3)(1)(^{7}_{1})\\right]~{\\rm MeV}$. The techniques presented illustrate a possible pathway towards connecting lattice QCD observables of few-body, strongly interacting systems to experimentally accessible quantities.

  2. Complete N-point superstring disk amplitude II. Amplitude and hypergeometric function structure

    Energy Technology Data Exchange (ETDEWEB)

    Mafra, Carlos R., E-mail: crmafra@aei.mpg.de [Max-Planck-Institut für Gravitationsphysik, Albert-Einstein-Institut, 14476 Potsdam (Germany); Kavli Institute for Theoretical Physics, University of California, Santa Barbara, CA 93106 (United States); Schlotterer, Oliver, E-mail: olivers@mppmu.mpg.de [Kavli Institute for Theoretical Physics, University of California, Santa Barbara, CA 93106 (United States); Max-Planck-Institut für Physik, Werner-Heisenberg-Institut, 80805 München (Germany); Stieberger, Stephan, E-mail: stephan.stieberger@mpp.mpg.de [Kavli Institute for Theoretical Physics, University of California, Santa Barbara, CA 93106 (United States); Max-Planck-Institut für Physik, Werner-Heisenberg-Institut, 80805 München (Germany)

    2013-08-21

    Using the pure spinor formalism in part I (Mafra et al., preprint [1]) we compute the complete tree-level amplitude of N massless open strings and find a striking simple and compact form in terms of minimal building blocks: the full N-point amplitude is expressed by a sum over (N−3)! Yang–Mills partial subamplitudes each multiplying a multiple Gaussian hypergeometric function. While the former capture the space–time kinematics of the amplitude the latter encode the string effects. This result disguises a lot of structure linking aspects of gauge amplitudes as color and kinematics with properties of generalized Euler integrals. In this part II the structure of the multiple hypergeometric functions is analyzed in detail: their relations to monodromy equations, their minimal basis structure, and methods to determine their poles and transcendentality properties are proposed. Finally, a Gröbner basis analysis provides independent sets of rational functions in the Euler integrals.

  3. One-loop triple collinear splitting amplitudes in QCD

    CERN Document Server

    Badger, Simon; Peraro, Tiziano

    2015-01-01

    We study the factorisation properties of one-loop scattering amplitudes in the triple collinear limit and extract the universal splitting amplitudes for processes initiated by a gluon. The splitting amplitudes are derived from the analytic Higgs plus four partons amplitudes. We present compact results for primitive helicity splitting amplitudes making use of super-symmetric decompositions. The universality of the collinear factorisation is checked numerically against the full colour six parton squared matrix elements.

  4. In-Medium Pion Valence Distribution Amplitude

    CERN Document Server

    Tsushima, K

    2016-01-01

    After a brief review of the quark-based model for nuclear matter, and some pion properties in medium presented in our previous works, we report new results for the pion valence wave function as well as the valence distribution amplitude in medium, which are presented in our recent article. We find that both the in-medium pion valence distribution and the in-medium pion valence wave function, are substantially modified at normal nuclear matter density, due to the reduction in the pion decay constant.

  5. Transition Distribution Amplitudes for gamma* gamma collisions

    CERN Document Server

    Lansberg, J P; Szymanowski, L

    2008-01-01

    We study the exclusive production of pi-pi and rho-pi in hard gamma* gamma scattering in the forward kinematical region where the virtuality of one photon provides us with a hard scale in the process. The newly introduced concept of Transition Distribution Amplitudes (TDA) is used to perform a QCD calculation of these reactions thanks to two simple models for TDAs. The sizable cross sections for rho-pi and pi-pi production may be tested at intense electron-positron colliders such as CLEO and B factories (Belle and BaBar).

  6. In-Medium Pion Valence Distribution Amplitude

    Science.gov (United States)

    Tsushima, K.; de Melo, J. P. B. C.

    2017-03-01

    After a brief review of the quark-based model for nuclear matter, and some pion properties in medium presented in our previous works, we report new results for the pion valence wave function as well as the valence distribution amplitude in medium, which are presented in our recent article. We find that both the in-medium pion valence distribution and the in-medium pion valence wave function, are substantially modified at normal nuclear matter density, due to the reduction in the pion decay constant.

  7. Information transfer for small-amplitude signals.

    Science.gov (United States)

    Kostal, Lubomir; Lansky, Petr

    2010-05-01

    We study the optimality conditions of information transfer in systems with memory in the low signal-to-noise ratio regime of vanishing input amplitude. We find that the optimal mutual information is represented by a maximum variance of the signal time course, with correlation structure determined by the Fisher information matrix. We provide illustration of the method on a simple biologically inspired model of electrosensory neuron. Our general results apply also to the study of information transfer in single neurons subject to weak stimulation, with implications to the problem of coding efficiency in biological systems.

  8. Amplitude modulation of wind turbine noise

    CERN Document Server

    Makarewicz, Rufin

    2013-01-01

    Due to swish and thump amplitude modulation, the noise of wind turbines cause more annoyance than other environmental noise of the same average level. The wind shear accounts for the thump modulation (van den Berg effect). Making use of the wind speed measurements at the hub height, as well as at the top and the bottom of the rotor disc (Fig.1), the non-standard wind profile is applied. It causes variations in the A-weighted sound pressure level, LpA. The difference between the maximum and minimum of LpA characterizes thump modulation (Fig.2).

  9. Fatigue crack growth under variable amplitude loading

    Science.gov (United States)

    Sidawi, Jihad A.

    1994-01-01

    Fatigue crack growth tests were conducted on an Fe 510 E C-Mn steel and a submerged arc welded joint from the same material under constant, variable, and random loading amplitudes. Paris-Erdogan's crack growth rate law was tested for the evaluation of m and C using the stress intensity factor K, the J-integral, the effective stress intensity factor K(sub eff), and the root mean square stress intensity factor K(sub rms) fracture mechanics concepts. The effect of retardation and residual stresses resulting from welding was also considered. It was found that all concepts gave good life predictions in all cases.

  10. Multiloop Integrand Reduction for Dimensionally Regulated Amplitudes

    CERN Document Server

    Mastrolia, P; Ossola, G; Peraro, T

    2013-01-01

    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.

  11. Analytic amplitude models for forward scattering

    CERN Document Server

    Kang, K; Ezhela, Vladimir V; Gauron, P; Kuyanov, Yu V; Lugovsky, S B; Nicolescu, Basarab; Tkachenko, N P; Kuyanov, Yu. V.

    2002-01-01

    We report on fits of a large class of analytic amplitude models for forward scattering against the comprehensive data for all available reactions. To differentiate the goodness of the fits of many possible parametrizations to a large sample of data, we developed and used a set of quantitative indicators measuring statistical quality of the fits over and beyond the typical criterion of the $\\Chi^2 /dof$. These indicators favor models with a universal $ log^2 s$ Pomeron term, which enables one to extend the fit down to $\\sqrt s = 4$ GeV.

  12. Approximate formulas for moderately small eikonal amplitudes

    CERN Document Server

    Kisselev, A V

    2015-01-01

    The eikonal approximation for moderately small scattering amplitudes is considered. With the purpose of using for their numerical estimations, the formulas are derived which contain no Bessel functions, and, hence, no rapidly oscillating integrands. To obtain these formulas, the improper integrals of the first kind which contain products of the Bessel functions J_0(z) are studied. The expression with four functions J_0(z) is generalized. The expressions for the integrals with the product of five and six Bessel functions J_0(z) are also found. The known formula for the improper integral with two functions J_nu(z) is generalized for non-integer nu.

  13. Approximate formulas for moderately small eikonal amplitudes

    Science.gov (United States)

    Kisselev, A. V.

    2016-08-01

    We consider the eikonal approximation for moderately small scattering amplitudes. To find numerical estimates of these approximations, we derive formulas that contain no Bessel functions and consequently no rapidly oscillating integrands. To obtain these formulas, we study improper integrals of the first kind containing products of the Bessel functions J0(z). We generalize the expression with four functions J0(z) and also find expressions for the integrals with the product of five and six Bessel functions. We generalize a known formula for the improper integral with two functions Jυ (az) to the case with noninteger υ and complex a.

  14. Impact Representation of Generalized Distribution Amplitudes

    CERN Document Server

    Pire, B

    2003-01-01

    We develop an impact representation for the generalized distribution amplitude which describes the exclusive hadronization of a quark-antiquark pair to a pair of mesons. Experiments such as gamma^* gamma -> pi pi and gamma^* N -> pi pi N' are shown to probe the transverse size of the hadronization region of the quark antiquark pair that one can interpret as the transverse overlap of the two emerging mesons. An astonishing feature of this description is that low energy pi pi phase shift analysis can be used for understanding some properties of quark hadronization process.

  15. The Construction of Spin Foam Vertex Amplitudes

    CERN Document Server

    Bianchi, Eugenio

    2012-01-01

    Spin foam vertex amplitudes are the key ingredient of spin foam models for quantum gravity. They 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 Barret and Crane and 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.

  16. 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.

  17. Quasi Distribution Amplitude of Heavy Quarkonia

    CERN Document Server

    Jia, Yu

    2015-01-01

    The recently-proposed quasi distributions point out a promising direction for lattice QCD to investigate the light-cone correlators, such as parton distribution functions (PDF) and distribution amplitudes (DA), directly in the $x$-space. Owing to its excessive simplicity, the heavy quarkonium can serve as an ideal theoretical laboratory to ascertain certain features of quasi-DA. In the framework of non-relativistic QCD (NRQCD) factorization, we compute the order-$\\alpha_s$ correction to both light-cone distribution amplitudes (LCDA) and quasi-DA associated with the lowest-lying quarkonia, with the transverse momentum UV cutoff interpreted as the renormalization scale. We confirm analytically that the quasi-DA of a quarkonium does reduce to the respective LCDA in the infinite-momentum limit. We also observe that, provided that the momentum of a charmonium reaches about 2-3 times its mass, the quasi-DAs already converge to the LCDAs to a decent level. These results might provide some useful guidance for the fut...

  18. Amplitude enhancement by a gold dimer

    Science.gov (United States)

    Hong, Xin; Wang, Jingxin; Jin, Zheng

    2016-10-01

    The unique optical properties such as brightness, non-bleaching, good bio-compatibility make gold particles ideal label candidates for molecular probes. Due to the strongly enhanced field, aggregation of gold nanoparticles finds themselves plenty of applications in bio-imaging. But limited by its small cross-section associated with nanometer sized particle, it is a big challenge to employ it in a single molecular detection. The field enhancement results from the effect of plasmonic coupling between two closely attached gold nanoparticle under the right excitation condition. With the aim to apply the gold dimer probe to find the molecules in our recently established optical detection method, we compared of the amplitude enhancement by the dimer relative to a single particle. The amplitude distribution under a highly focused illumination objective was calculated, whose results suggest that at the optimized excitation condition, the local field can be enhanced 190 fold. In consequence, experimental detection was carried out. Gold dimers were linked together by the hybridization of two single chain DNAs. Dimer and single particle probes were mixed together in one detection. Overwhelming contrast between these two kinds of probes were clearly exhibited in the experimental detection image. This method can provide a way to a high specific detection in early diagnosis.

  19. ABJM Amplitudes in U-gauge and a Soft Theorem

    CERN Document Server

    Chin, Seungbeom; Yun, Youngbin

    2015-01-01

    We report progress in computing and analyzing all tree amplitudes in ABJM theory. Inspired by the isomorphism between the orthogonal Grassmannian and the pure spinor geometries, we adopt a new gauge, called u-gauge, for evaluating the orthogonal Grassmannian integral for ABJM amplitudes. We carry out the integral explicitly for the 8-point amplitude and obtain the complete supersymmetric amplitude. The physical and spurious poles arise from the integral as expected from on-shell diagrams. We also derive a double scalar soft theorem of ABJM amplitudes and verify it for known amplitudes.

  20. ABJM amplitudes in U-gauge and a soft theorem

    Energy Technology Data Exchange (ETDEWEB)

    Chin, Seungbeom [Department of Physics and Astronomy, Seoul National University,Seoul 151-747 (Korea, Republic of); Lee, Sangmin [Department of Physics and Astronomy, Seoul National University,Seoul 151-747 (Korea, Republic of); Center for Theoretical Physics, Seoul National University,Seoul 151-747 (Korea, Republic of); College of Liberal Studies, Seoul National University,Seoul 151-742 (Korea, Republic of); School of Physics, Korea Institute for Advanced Study,Seoul 130-722 (Korea, Republic of); Yun, Youngbin [Department of Physics and Astronomy, Seoul National University,Seoul 151-747 (Korea, Republic of)

    2015-11-13

    We report progress in computing and analyzing all tree amplitudes in ABJM theory. Inspired by the isomorphism between the orthogonal Grassmannian and the pure spinor geometries, we adopt a new gauge, called u-gauge, for evaluating the orthogonal Grassmannian integral for ABJM amplitudes. We carry out the integral explicitly for the 8-point amplitude and obtain the complete supersymmetric amplitude. The physical and spurious poles arise from the integral as expected from on-shell diagrams. We also derive a double soft theorem of ABJM amplitudes and verify it for known amplitudes.

  1. Color-kinematic duality in ABJM theory without amplitude relations

    Science.gov (United States)

    Sivaramakrishnan, Allic

    2017-01-01

    We explicitly show that the Bern-Carrasco-Johansson color-kinematic duality holds at tree level through at least eight points in Aharony-Bergman-Jafferis-Maldacena theory with gauge group SU(N) × SU(N). At six points we give the explicit form of numerators in terms of amplitudes, displaying the generalized gauge freedom that leads to amplitude relations. However, at eight points no amplitude relations follow from the duality, so the diagram numerators are fixed unique functions of partial amplitudes. We provide the explicit amplitude-numerator decomposition and the numerator relations for eight-point amplitudes.

  2. The Prediction of Maximum Amplitudes of Solar Cycles and the Maximum Amplitude of Solar Cycle 24

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    We present a brief review of predictions of solar cycle maximum ampli-tude with a lead time of 2 years or more. It is pointed out that a precise predictionof the maximum amplitude with such a lead-time is still an open question despiteprogress made since the 1960s. A method of prediction using statistical character-istics of solar cycles is developed: the solar cycles are divided into two groups, ahigh rising velocity (HRV) group and a low rising velocity (LRV) group, dependingon the rising velocity in the ascending phase for a given duration of the ascendingphase. The amplitude of Solar Cycle 24 can be predicted after the start of thecycle using the formula derived in this paper. Now, about 5 years before the startof the cycle, we can make a preliminary prediction of 83.2-119.4 for its maximumamplitude.

  3. Spurious cross-frequency amplitude-amplitude coupling in nonstationary, nonlinear signals

    Science.gov (United States)

    Yeh, Chien-Hung; Lo, Men-Tzung; Hu, Kun

    2016-07-01

    Recent studies of brain activities show that cross-frequency coupling (CFC) plays an important role in memory and learning. Many measures have been proposed to investigate the CFC phenomenon, including the correlation between the amplitude envelopes of two brain waves at different frequencies - cross-frequency amplitude-amplitude coupling (AAC). In this short communication, we describe how nonstationary, nonlinear oscillatory signals may produce spurious cross-frequency AAC. Utilizing the empirical mode decomposition, we also propose a new method for assessment of AAC that can potentially reduce the effects of nonlinearity and nonstationarity and, thus, help to avoid the detection of artificial AACs. We compare the performances of this new method and the traditional Fourier-based AAC method. We also discuss the strategies to identify potential spurious AACs.

  4. Presynaptic spike broadening reduces junctional potential amplitude.

    Science.gov (United States)

    Spencer, A N; Przysiezniak, J; Acosta-Urquidi, J; Basarsky, T A

    1989-08-24

    Presynaptic modulation of action potential duration may regulate synaptic transmission in both vertebrates and invertebrates. Such synaptic plasticity is brought about by modifications to membrane currents at presynaptic release sites, which, in turn, lead to changes in the concentration of cytosolic calcium available for mediating transmitter release. The 'primitive' neuromuscular junction of the jellyfish Polyorchis penicillatus is a useful model of presynaptic modulation. In this study, we show that the durations of action potentials in the motor neurons of this jellyfish are negatively correlated with the amplitude of excitatory junctional potentials. We present data from in vitro voltage-clamp experiments showing that short duration voltage spikes, which elicit large excitatory junctional potentials in vivo, produce larger and briefer calcium currents than do long duration action potentials, which elicit small excitatory junctional potentials.

  5. Nonlinear amplitude dynamics in flagellar beating

    CERN Document Server

    Oriola, David; Casademunt, Jaume

    2016-01-01

    The physical basis of flagellar and ciliary beating is a major problem in biology which is still far from completely understood. The fundamental cytoskeleton structure of cilia and flagella is the axoneme, a cylindrical array of microtubule doublets connected by passive crosslinkers and dynein motor proteins. The complex interplay of these elements leads to the generation of self-organized bending waves. Although many mathematical models have been proposed to understand this process, few attempts have been made to assess the role of dyneins on the nonlinear nature of the axoneme. Here, we investigate the nonlinear dynamics of flagella by considering an axonemal sliding control mechanism for dynein activity. This approach unveils the nonlinear selection of the oscillation amplitudes, which are typically either missed or prescribed in mathematical models. The explicit set of nonlinear equations are derived and solved numerically. Our analysis reveals the spatiotemporal dynamics of dynein populations and flagell...

  6. Determination of the pion distribution amplitude

    CERN Document Server

    Huang, Tao; Wu, Xing-Gang

    2013-01-01

    Right now, we have not enough knowledge to determine the hadron distribution amplitudes (DAs) which are universal physical quantities in the high energy processes involving hadron for applying pQCD to exclusive processes. Even for the simplest pion, one can't discriminate from different DA models. Inversely, one expects that processes involving pion can in principle provide strong constraints on the pion DA. For example, the pion-photon transition form factor (TFF) can get accurate information of the pion wave function or DA, due to the single pion in this process. However, the data from Belle and BABAR have a big difference on TFF in high $Q^2$ regions, at present, they are helpless for determining the pion DA. At the present paper, we think it is still possible to determine the pion DA as long as we perform a combined analysis of the most existing data of the processes involving pion such as $\\pi \\to \\mu \\bar{\

  7. Amplitude envelope synchronization in coupled chaotic oscillators.

    Science.gov (United States)

    Gonzalez-Miranda, J M

    2002-03-01

    A peculiar type of synchronization has been found when two Van der Pol-Duffing oscillators, evolving in different chaotic attractors, are coupled. As the coupling increases, the frequencies of the two oscillators remain different, while a synchronized modulation of the amplitudes of a signal of each system develops, and a null Lyapunov exponent of the uncoupled systems becomes negative and gradually larger in absolute value. This phenomenon is characterized by an appropriate correlation function between the returns of the signals, and interpreted in terms of the mutual excitation of new frequencies in the oscillators power spectra. This form of synchronization also occurs in other systems, but it shows up mixed with or screened by other forms of synchronization, as illustrated in this paper by means of the examples of the dynamic behavior observed for three other different models of chaotic oscillators.

  8. Experimental generation of amplitude squeezed vector beams

    CERN Document Server

    Chille, Vanessa; Semmler, Marion; Banzer, Peter; Aiello, Andrea; Leuchs, Gerd; Marquardt, Christoph

    2016-01-01

    We present an experimental method for the generation of amplitude squeezed high-order vector beams. The light is modified twice by a spatial light modulator such that the vector beam is created by means of a collinear interferometric technique. A major advantage of this approach is that it avoids systematic losses, which are detrimental as they cause decoherence in continuous-variable quantum systems. The utilisation of a spatial light modulator (SLM) gives the flexibility to switch between arbitrary mode orders. The conversion efficiency with our setup is only limited by the efficiency of the SLM. We show the experimental generation of Laguerre-Gauss (LG) modes with radial indices up to 1 and azimuthal indices up to 3 with complex polarization structures and a quantum noise reduction up to -0.9dB$\\pm$0.1dB. The corresponding polarization structures are studied in detail by measuring the spatial distribution of the Stokes parameters.

  9. Speech recognition with amplitude and frequency modulations

    Science.gov (United States)

    Zeng, Fan-Gang; Nie, Kaibao; Stickney, Ginger S.; Kong, Ying-Yee; Vongphoe, Michael; Bhargave, Ashish; Wei, Chaogang; Cao, Keli

    2005-02-01

    Amplitude modulation (AM) and frequency modulation (FM) are commonly used in communication, but their relative contributions to speech recognition have not been fully explored. To bridge this gap, we derived slowly varying AM and FM from speech sounds and conducted listening tests using stimuli with different modulations in normal-hearing and cochlear-implant subjects. We found that although AM from a limited number of spectral bands may be sufficient for speech recognition in quiet, FM significantly enhances speech recognition in noise, as well as speaker and tone recognition. Additional speech reception threshold measures revealed that FM is particularly critical for speech recognition with a competing voice and is independent of spectral resolution and similarity. These results suggest that AM and FM provide independent yet complementary contributions to support robust speech recognition under realistic listening situations. Encoding FM may improve auditory scene analysis, cochlear-implant, and audiocoding performance. auditory analysis | cochlear implant | neural code | phase | scene analysis

  10. Low-amplitude vector screening solitons

    Institute of Scientific and Technical Information of China (English)

    Keqing Lu(卢克清); Xiangping Zhu(朱香平); Wei Zhao(赵卫); Yanlong Yang(杨延龙); Jinping Li(李金萍); Yanpeng Zhang(张彦鹏); Junchang Zhang(张君昌)

    2004-01-01

    We show self-coupled and cross-coupled vector beam evolution equations in the low-amplitude regime for screening solitons,which can exhibit the analytical solutions of bright-bright and dark-dark vector solitons.Our analysis indicates that these self-coupled vector solitons are obtained irrespective of the intensities of the two optical beams,whereas these cross-coupled vector solitons can be established when the intensities of the two optical beams are equal.Relevant examples are provided where the photorefractive crystal is lithium niobate(LiNbO3).The stability properties of these vector solitons have been investigated numerically and it has been found that they are stable.

  11. Low amplitude impact of damaged PBX 9501

    Science.gov (United States)

    Idar, Deanne J.; Straight, James W.; Osborn, Michael A.; Coulter, William L.; Buntain, Gregory A.

    2000-04-01

    Low amplitude impact tests on pristine and damaged, `baseline' and `aged' PBX 9501 specimens were performed to determine the critical impact-velocity threshold for violent reactions. HE damage was achieved by a single impact ranging in velocity from 36.9 to 54.4 m/s. External blast gauge and ballistic pendulum data were used to evaluate reaction violence relative to a steady-state detonation. Strain gage data were used to evaluate the response of the explosive to impact and characterize subsequent reaction profiles. Test results show that the damaged threshold 1) is lower than the pristine threshold and 2) is invariant to PBX 9501 lot-to-lot and age variables.

  12. Amplitude equations for isothermal double diffusive convection

    Energy Technology Data Exchange (ETDEWEB)

    Becerril, R.; Swift, J.B. [Center for Nonlinear Dynamics and Department of Physics, University of Texas, Austin, Texas 78712 (United States)

    1997-05-01

    Amplitude equations are derived for isothermal double diffusive convection near threshold for both the stationary and oscillatory instabilities as well as in the vicinity of the codimension-2 point. The convecting fluid is contained in a thin Hele-Shaw cell that renders the system two dimensional, and convection is sustained by vertical concentration gradients of two species with different diffusion rates. The locations of the tricritical point for the stationary instability and the codimension-2 point are found. It is shown that these points can be made well separated (in the Rayleigh number R{sub s} of the slow diffusing species) as the Lewis number varies. Hence the behavior near these points should be experimentally accessible. {copyright} {ital 1997} {ital The American Physical Society}

  13. Pion Distribution Amplitude from Lattice QCD

    CERN Document Server

    Braun, V M; Göckeler, M; Pérez-Rubio, P; Schäfer, A; Schiel, R W; Sternbeck, A

    2015-01-01

    We have calculated the second moment of the pion light-cone distribution amplitude using two flavors of dynamical (clover) fermions on lattices of different volumes, lattice spacings between $0.06 \\, \\mathrm {fm}$ and $0.08 \\, \\mathrm {fm}$ and pion masses down to $m_\\pi\\sim 150 \\, \\mathrm {MeV}$. Our result for the second Gegenbauer coefficient is $a_2 = 0.1364(154)(145)$ and for the width parameter $\\langle \\xi^2 \\rangle = 0.2361(41)(39)$. Both numbers refer to the scale $\\mu=2 \\, \\mathrm {GeV}$in the $\\overline{\\text{MS}}$ scheme, the first error is statistical including the uncertainty of the chiral extrapolation, and the second error is the estimated uncertainty coming from the nonperturbatively determined renormalization factors.

  14. Amplitude determinant coupled cluster with pairwise doubles

    CERN Document Server

    Zhao, Luning

    2016-01-01

    Recently developed pair coupled cluster doubles (pCCD) theory successfully reproduces doubly occupied configuration interaction (DOCI) with mean field cost. However, the projective nature of pCCD makes the method non-variational and thus hard to improve systematically. As a variational alternative, we explore the idea of coupled-cluster-like expansions based on amplitude determinants and develop a specific theory similar to pCCD based on determinants of pairwise doubles. The new ansatz admits a variational treatment through Monte Carlo methods while remaining size-consistent and, crucially, polynomial cost. In the dissociations of LiH, HF, H2O and N2, the method performs very similarly to pCCD and DOCI, suggesting that coupled-cluster-like ansatzes and variational evaluation may not be mutually exclusive.

  15. Automating QCD amplitudes with on-shell methods

    CERN Document Server

    Badger, Simon

    2016-01-01

    We review some of the modern approaches to scattering amplitude computations in QCD and their application to precision LHC phenomenology. We emphasise the usefulness of momentum twistor variables in parameterising general amplitudes.

  16. On the soft limit of tree-level string amplitudes

    CERN Document Server

    Bianchi, Massimo

    2016-01-01

    We study the soft behavior of string scattering amplitudes at three level with massless and massive external insertions, relying on different techniques to compute 4-points amplitudes respectively with open or closed strings.

  17. Soft behavior of string amplitudes with external massive states

    CERN Document Server

    Guerrieri, Andrea L

    2015-01-01

    We briefly discuss the soft behavior of scattering amplitudes both in string and quantum field theory. In particular we show a general argument about the validity of soft theorems for open superstring amplitudes and list some of our recent results.

  18. EFECTOS DE LA DISPERSIÓN POR MODO DE POLARIZACIÓN (PMD EN LA PROPAGACIÓN DE PULSOS A TRAVÉS DE FIBRAS ÓPTICAS EFFECTS OF POLARIZATION MODE DISPERSION (PMD ON PROPAGATION OF OPTICAL PULSES IN OPTICAL FIBERS

    Directory of Open Access Journals (Sweden)

    Ariel Leiva L

    2007-12-01

    Full Text Available En este trabajo se revisan los conceptos fundamentales de la dispersión por modo de polarización (PMD: Polarization Mode Dispersion que ocurre en fibras ópticas. PMD produce ensanchamientos aleatorios de los pulsos ópticos transmitidos a través de una fibra óptica y su efecto es considerable para velocidades de transmisión digital iguales o superiores a 10 Gbps. Se revisa la teoría de PMD y se plantea la relevancia de caracterizar el fenómeno en transmisión por fibra óptica, concluyéndose con un método de simulación de la propagación de pulsos afectados por PMD. Este trabajo constituye un punto de partida para posteriores análisis de los efectos de PMD en sistemas de transmisión, para su compensación y mediciónThis work reviews the fundamental concepts of polarization mode dispersion (PMD occurring in optical fibers. PMD broadens optical pulses transmitted through an optical fiber at random and its effect is significant for bit rates equal or exceeding 10 Gbps. The theory of PMD and relevance of characterizing this phenomenon in optical fiber transmission is presented, concluding with a simulation model of the optical pulse propagation, subject to PMD. This provides a starting point for further analysis of the effects of PMD in transmission systems and how to measure and compensate these

  19. Chiral closed strings: four massless states scattering amplitude

    Science.gov (United States)

    Leite, Marcelo M.; Siegel, Warren

    2017-01-01

    We compute the scattering amplitudes of four massless states for chiral (closed) bosonic and type II superstrings using the Kawai-Lewellen-Tye ( KLT ) factorization method. The amplitude in the chiral bosonic case is identical to a field theory amplitude corresponding to the spin-2 tachyon, massless gravitational sector and massive spin-2 tardyon states of the spectrum. Chiral type II superstrings amplitude only possess poles associated with the massless gravitational sector. We briefly discuss the extension of the calculation to heterotic superstrings.

  20. Chiral Closed strings: Four massless states scattering amplitude

    CERN Document Server

    Leite, Marcelo M

    2016-01-01

    We compute the scattering amplitudes of four massless states for chiral (closed) bosonic and type II superstrings using the Kawai-Lewellen-Tye ($KLT$) factorization method. The amplitude in the chiral bosonic case is identical to a field theory amplitude corresponding to the spin-$2$ tachyon, massless gravitational sector and massive spin-2 tardyon states of the spectrum. Chiral type II superstrings amplitude only possess poles associated with the massless gravitational sector. We briefly discuss the extension of the calculation to heterotic superstrings.

  1. Sobre a psicopatologia dos atos

    Directory of Open Access Journals (Sweden)

    Roberto Calazans

    2015-07-01

    Full Text Available Este artigo pretende apresentar a psicopatologia dos atos a partir do esquema de Jacques Lacan sobre a angústia. Diferenciamos os acting-out, a passagem ao ato, os sintomas, as inibições e a angústia fazendo uma duplicação do esquema de Lacan levando em consideração os registros do simbólico, do real e do imaginário. Esse esquema permite uma abordagem da questão dos atos do sujeito sem cair em uma perplexidade do clínico, nem na confusão entre os atos e a ação. Permite também uma melhor orientação do clínico em relação às diversas modalidades de respostas subjetivas que não se restringem à questão sintomática, que é o campo inaugural da clínica psicanalítica desde a sua fundação por Sigmund Freud. Acreditamos contribuir, assim, para um maior esclarecimento desse esquema no ensino de Lacan e para que ele possa servir de orientação para o tratamento dos atos do sujeito na clínica.

  2. Accurate Period Approximation for Any Simple Pendulum Amplitude

    Institute of Scientific and Technical Information of China (English)

    XUE De-Sheng; ZHOU Zhao; GAO Mei-Zhen

    2012-01-01

    Accurate approximate analytical formulae of the pendulum period composed of a few elementary functions for any amplitude are constructed.Based on an approximation of the elliptic integral,two new logarithmic formulae for large amplitude close to 180° are obtained.Considering the trigonometric function modulation results from the dependence of relative error on the amplitude,we realize accurate approximation period expressions for any amplitude between 0 and 180°.A relative error less than 0.02% is achieved for any amplitude.This kind of modulation is also effective for other large-amplitude logarithmic approximation expressions.%Accurate approximate analytical formulae of the pendulum period composed of a few elementary functions for any amplitude are constructed. Based on an approximation of the elliptic integral, two new logarithmic formulae for large amplitude close to 180° are obtained. Considering the trigonometric function modulation results from the dependence of relative error on the amplitude, we realize accurate approximation period expressions for any amplitude between 0 and 180°. A relative error less than 0.02% is achieved for any amplitude. This kind of modulation is also effective for other large-amplitude logarithmic approximation expressions.

  3. Comparison of superresolution effects with annular phase and amplitude filters.

    Science.gov (United States)

    Luo, Hongxin; Zhou, Changhe

    2004-12-01

    The characteristics of annular amplitude and phase filters are compared. The behavior of two-zone phase and amplitude filters as the inner zone is increased is studied in detail. Numerical simulations show that a phase filter can achieve a superresolution effect, a circular Dammann effect, and flat-topped intensity for different applications, whereas a two-zone amplitude filter can generate only a superresolution effect. The experimental results show that both amplitude and phase filters can achieve superresolution. Generally, a phase superresolution filter is recommended for its higher efficiency and its special diffraction patterns that are impossible to achieve with an amplitude filter.

  4. A Numerical Unitarity Formalism for Evaluating One-Loop Amplitudes

    CERN Document Server

    Ellis, Richard Keith; Kunszt, Z

    2008-01-01

    Recent progress in unitarity techniques for one-loop scattering amplitudes makes a numerical implementation of this method possible. We present a 4-dimensional unitarity method for calculating the cut-constructible part of amplitudes and implement the method in a numerical procedure. Our technique can be applied to any one-loop scattering amplitude and offers the possibility that one-loop calculations can be performed in an automatic fashion, as tree-level amplitudes are currently done. Instead of individual Feynman diagrams, the ingredients for our one-loop evaluation are tree-level amplitudes, which are often already known. To study the practicality of this method we evaluate the cut-constructible part of the 4, 5 and 6 gluon one-loop amplitudes numerically, using the analytically known 4, 5 and 6 gluon tree-level amplitudes. Comparisons with analytic answers are performed to ascertain the numerical accuracy of the method.

  5. 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.

  6. 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.

  7. Open string topological amplitudes and gaugino masses

    CERN Document Server

    Antoniadis, Ignatios; Taylor, T R

    2005-01-01

    We show that the genus zero topological partition function $F^{(0,h)}$, on a world-sheet with $h$ boundaries, computes the moduli-dependent couplings of the higher derivative F-terms $(\\Tr W^2)^{h-1}$, where $W$ is the gauge N=1 chiral superfield. 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 $\\Pi^n({\\rm Tr}W^2)^{h-2}$, where $\\Pi$'s represent chiral projections of non-holomorphic functions of chiral superfields. An important property of these couplings is that they violate R-symmetry for $h\\ge 3$. As a result, once supersymmetry is broken by D-term expectation values, $(\\Tr W^2)^2$ generates gaugino masses that can be hierarchically smaller than the scalar masses, behaving as $m_{1/2}\\sim m_0^4$ in string units. Similarly, $\\Pi{\\rm Tr}W^2$ g...

  8. Generating Functionals for Spin Foam Amplitudes

    CERN Document Server

    Hnybida, Jeff

    2014-01-01

    We construct a generating functional for the exact evalutation of a coherent representation of spin network amplitudes. This generating functional is defined for arbitrary graphs and depends only on a pair of spinors for each edge. The generating functional is a meromorphic polynomial in the spinor invariants which is determined by the cycle structure of the graph. The expansion of the spin network generating function is given in terms of a newly recognized basis of SU(2) intertwiners consisting of the monomials of the holomorphic spinor invariants. This basis is labelled by the degrees of the monomials and is thus discrete. It is also overcomplete, but contains the precise amount of data to specify points in the classical space of closed polyhedra, and is in this sense coherent. We call this new basis the discrete-coherent basis. We focus our study on the 4-valent basis, which is the first non-trivial dimension, and is also the case of interest for Quantum Gravity. We find simple relations between the new ba...

  9. 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.

  10. A generalized fidelity amplitude for open systems.

    Science.gov (United States)

    Gorin, T; Moreno, H J; Seligman, T H

    2016-06-13

    We consider a central system which is coupled via dephasing to an open system, i.e. an intermediate system which in turn is coupled to another environment. Considering the intermediate and far environment as one composite system, the coherences in the central system are given in the form of fidelity amplitudes for a certain perturbed echo dynamics in the composite environment. On the basis of the Born-Markov approximation, we derive a master equation for the reduction of that dynamics to the intermediate system alone. In distinction to an earlier paper (Moreno et al 2015 Phys. Rev. A 92, 030104. (doi:10.1103/PhysRevA.92.030104)), where we discussed the stabilizing effect of the far environment on the decoherence in the central system, we focus here on the possibility of using the measurable coherences in the central system for probing the open quantum dynamics in the intermediate system. We illustrate our results for the case of chaotic dynamics in the near environment, where we compare random matrix simulations with our analytical result.

  11. Surface Wave Amplitude Anomalies in the Western United States

    Science.gov (United States)

    Eddy, C.; Ekstrom, G.

    2011-12-01

    We determine maps of local surface wave amplitude factors across the Western United States for Rayleigh and Love waves at discrete periods between 25 and 125s. Measurements of raw amplitude anomalies are made from data recorded at 1161 USArray stations for minor arc arrivals of earthquakes with Mw>5.5 occurring between 2006 and 2010. We take the difference between high-quality amplitude anomaly measurements for events recorded on station pairs less than 2 degrees apart. The mean of these differences for each station pair is taken as the datum. Surface wave amplitudes are controlled by four separate mechanisms: focusing due to elastic structure, attenuation due to anelastic structure, source effects, and receiver effects. By taking the mean of the differences of amplitude anomalies for neighboring stations, we reduce the effects of focusing, attenuation, and the seismic source, thus isolating amplitude anomalies due to near-receiver amplitude effects. We determine local amplitude factors for each USArray station by standard linear inversion of the differential data set. The individual station amplitude factors explain the majority of the variance of the data. For example, derived station amplitude factors for 50s Rayleigh waves explain 92% of the variance of the data. We explore correlations between derived station amplitude factors and local amplitude factors predicted by crust and upper mantle models. Maps of local amplitude factors show spatial correlation with topography and geologic structures in the Western United States, particularly for maps derived from Rayleigh wave amplitude anomalies. A NW-SE trending high in amplitude factors in Eastern California is evident in the 50s map, corresponding to the location of the Sierra Nevada Mountains. High amplitude factors are observed in Colorado and New Mexico in the 50s-125s maps in the location of the highest peaks of the Rocky Mountains. High amplitude factors are also seen in Southern Idaho and Eastern Wyoming in

  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. Dos nuevas especies y dos nuevas variedades de Columnea (Gesneriaceae

    Directory of Open Access Journals (Sweden)

    MARISOL AMAYA-MÁRQUEZ

    2015-01-01

    Full Text Available En este artículo describimos dos nuevas especies de Gesneriaceae (género Columnea. Columnea chocoensis se encuentra distribuida en los departamentos de Chocó y Valle del Cauca en Colombia, y C. chocoensis var. altaquerensis se distribuye en el departamento de Nariño, Colombia. Columnea stilesiana fue hallada en La Serranía de Los Paraguas localizada en la Cordillera Occidental entre los departamentos de Chocó y Valle del Cauca en Colombia. Adicionalmente, aquí se considera a Columnea archidonae como variedad de C. ericae. Columnea ericae var. archidonae se distribuye en Colombia y Ecuador, en bosques de mayor altura que aquellos en los cuales se encuentra la variedad típica.

  14. Detection of combined frequency and amplitude modulation.

    Science.gov (United States)

    Moore, B C; Sek, A

    1992-12-01

    This article is concerned with the detection of mixed modulation (MM), i.e., simultaneously occurring amplitude modulation (AM) and frequency modulation (FM). In experiment 1, an adaptive two-alternative forced-choice task was used to determine thresholds for detecting AM alone. Then, thresholds for detecting FM were determined for stimuli which had a fixed amount of AM in the signal interval only. The amount of AM was always less than the threshold for detecting AM alone. The FM thresholds depended significantly on the magnitude of the coexisting AM. For low modulation rates (4, 16, and 64 Hz), the FM thresholds did not depend significantly on the relative phase of modulation for the FM and AM. For a high modulation rate (256 Hz) strong effects of modulator phase were observed. These phase effects are as predicted by the model proposed by Hartmann and Hnath [Acustica 50, 297-312 (1982)], which assumes that detection of modulation at modulation frequencies higher than the critical modulation frequency is based on detection of the lower sideband in the modulated signal's spectrum. In the second experiment, psychometric functions were measured for the detection of AM alone and FM alone, using modulation rates of 4 and 16 Hz. Results showed that, for each type of modulation, d' is approximately a linear function of the square of the modulation index. Application of this finding to the results of experiment 1 suggested that, at low modulation rates, FM and AM are not detected by completely independent mechanisms. In the third experiment, psychometric functions were again measured for the detection of AM alone and FM alone, using a 10-Hz modulation rate. Detectability was then measured for combined AM and FM, with modulation depths selected so that each type of modulation would be equally detectable if presented alone. Significant effects of relative modulator phase were found when detectability was relatively high. These effects were not correctly predicted by either a

  15. Remessas de recursos dos imigrantes

    Directory of Open Access Journals (Sweden)

    Ana Cristina Braga Martes

    2006-08-01

    Full Text Available AS REMESSAS contribuem para o desenvolvimento local e para redução da pobreza? Essa é a pergunta-chave que os estudos recentes sobre migrações internacionais têm levantado. O que se está procurando compreender é de que modo as remessas poderiam afetar positiva ou negativamente a economia dos países de origem dos imigrantes. Discutir o papel e o significado das remessas implica, assim, uma discussão em torno da existência (ou não de um "campo de positividades" do fenômeno migratório internacional. O principal objetivo deste artigo é contribuir para essa discussão por meio de um estudo empírico do caso brasileiro que adota as remessas como foco. Para tanto, é identificado o perfil das remessas e dos remetentes, assim como os objetivos e os beneficiários do dinheiro enviado. A pesquisa usa uma abordagem baseada em entrevistas em profundidade e survey não-representativo (Boston e Governador Valadares.DO REMITTANCES contribute to local development and the reduction of poverty? What are the consequences of the dollars sent by the migrants to the people, families, and organizations that receive them in the cities of origin? These are the key questions that recent studies have raised. According to some authors "migration is inevitable and has the potential to be quite positive in terms of development and reduction of poverty. The policies that have their origins in this principle will be more successful than those that attempt to oppose, intransigently, both globalization and the migration of people in space". Do current international migrations produce positive local development effects? The main objective of this article is to contribute to this discussion through an empirical study of the Brazilian case, which takes remittances as its focus. Thus, we identify who the immigrants are who send remittances from the United States to Brazil, to what ends the remittances are directed, who the beneficiaries are, and how the remittances

  16. The five gluon amplitude and one-loop integrals

    CERN Document Server

    Bern, Zvi; Kosower, David A.

    1992-01-01

    We review the conventional field theory description of the string motivated technique. This technique is applied to the one-loop five-gluon amplitude. To evaluate the amplitude a general method for computing dimensionally regulated one-loop integrals is outlined including results for one-loop integrals required for the pentagon diagram and beyond. Finally, two five-gluon helicity amplitudes are given.

  17. Amplitudes ratios in $\\rho^0$ leptoproductions and GPDs

    CERN Document Server

    Goloskokov, S V

    2016-01-01

    We investigate exclusive leptoproduction of $\\rho^0$ meson. These reactions were analyzed within the factorizing handbag approach. In our model good agreement of observables for light meson production with experimental data in a wide energy range was found. Using the model results we calculate the ratio of different helicity amplitudes for a transversely polarized proton target to the leading twist longitudinal amplitude. Our results are close to the amplitude ratios measured by HERMES.

  18. Scattering amplitudes and BCFW recursion in twistor space

    Science.gov (United States)

    Mason, Lionel; Skinner, David

    2010-01-01

    Twistor ideas have led to a number of recent advances in our understanding of scattering amplitudes. Much of this work has been indirect, determining the twistor space support of scattering amplitudes by examining the amplitudes in momentum space. In this paper, we construct the actual twistor scattering amplitudes themselves. We show that the recursion relations of Britto, Cachazo, Feng and Witten have a natural twistor formulation that, together with the three-point seed amplitudes, allows us to recursively construct general tree amplitudes in twistor space. We obtain explicit formulae for n-particle MHV and NMHV super-amplitudes, their CPT conjugates (whose representations are distinct in our chiral framework), and the eight particle N2MHV super-amplitude. We also give simple closed form formulae for the mathcal{N} = 8 supergravity recursion and the MHV and overline {text{MHV}} amplitudes. This gives a formulation of scattering amplitudes in maximally supersymmetric theories in which superconformal symmetry and its breaking is manifest. For N k MHV, the amplitudes are given by 2 n - 4 integrals in the form of Hilbert transforms of a product of n - k - 2 purely geometric, superconformally invariant twistor delta functions, dressed by certain sign operators. These sign operators subtly violate conformal invariance, even for tree-level amplitudes in mathcal{N} = 4 super Yang-Mills, and we trace their origin to a topological property of split signature space-time. We develop the twistor transform to relate our work to the ambidextrous twistor diagram approach of Hodges and of Arkani-Hamed, Cachazo, Cheung and Kaplan.

  19. Tree-level split helicity amplitudes in ambitwistor space

    Science.gov (United States)

    Chen, Bin; Wu, Jun-Bao

    2009-12-01

    We study all tree-level split helicity gluon amplitudes by using the recently proposed Britto-Cachazo-Feng-Witten recursion relation and Hodges diagrams in ambitwistor space. We pick out the contributing diagrams and find that all of them can be divided into triangles in a suitable way. We give the explicit expressions for all of these amplitudes. As an example, we reproduce the six-gluon split next-to-maximally-helicity-violating amplitudes in momentum space.

  20. Log-periodic Critical Amplitudes: A Perturbative Approach

    Science.gov (United States)

    Derrida, Bernard; Giacomin, Giambattista

    2013-06-01

    Log-periodic amplitudes appear in the critical behavior of a large class of systems, in particular when a discrete scale invariance is present. Here we show how to compute these critical amplitudes perturbatively when they originate from a renormalization map which is close to a monomial. In this case, the log-periodic amplitudes of the subdominant corrections to the leading critical behavior can also be calculated.

  1. N >= 4 Supergravity Amplitudes from Gauge Theory at One Loop

    CERN Document Server

    Bern, Z; Johansson, H

    2011-01-01

    We expose simple and practical relations between the integrated four- and five-point one-loop amplitudes of N >= 4 supergravity and the corresponding (super-)Yang-Mills amplitudes. The link between the amplitudes is simply understood using the recently uncovered duality between color and kinematics that leads to a double-copy structure for gravity. These examples provide additional direct confirmations of the duality and double-copy properties at loop level for a sample of different theories.

  2. Mass of nonrelativistic meson from leading twist distribution amplitudes

    Energy Technology Data Exchange (ETDEWEB)

    Braguta, V. V., E-mail: braguta@mail.ru [Institute for High Energy Physics (Russian Federation)

    2011-01-15

    In this paper distribution amplitudes of pseudoscalar and vector nonrelativistic mesons are considered. Using equations of motion for the distribution amplitudes, relations are derived which allow one to calculate the masses of nonrelativistic pseudoscalar and vector meson if the leading twist distribution amplitudes are known. These relations can be also rewritten as relations between the masses of nonrelativistic mesons and infinite series of QCD operators, what can be considered as an exact version of Gremm-Kapustin relation in NRQCD.

  3. EW and QCD One-Loop Amplitudes with RECOLA

    CERN Document Server

    Actis, Stefano; Hofer, Lars; Scharf, Andreas; Uccirati, Sandro

    2013-01-01

    We present the computer code RECOLA for the computation of EW and QCD amplitudes in the Standard Model at next-to-leading order. One-loop amplitudes are represented as linear combinations of tensor integrals whose coefficients are calculated by means of recursive relations similar to Dyson-Schwinger equations. A novel treatment of colour enables us to recursively construct the colour structure of the amplitude efficiently. RECOLA is linked with the library COLLIER for the computation of the tensor integrals.

  4. Amplitudes and Ultraviolet Behavior of N = 8 Supergravity

    Energy Technology Data Exchange (ETDEWEB)

    Bern, Zvi; /UCLA; Carrasco, John Joseph; /Stanford U., Phys. Dept.; Dixon, Lance J.; /SLAC /CERN; Johansson, Henrik; /Saclay, SPhT; Roiban, Radu; /Penn State U.

    2011-05-20

    In this contribution we describe computational tools that permit the evaluation of multi-loop scattering amplitudes in N = 8 supergravity, in terms of amplitudes in N = 4 super-Yang-Mills theory. We also discuss the remarkable ultraviolet behavior of N = 8 supergravity, which follows from these amplitudes, and is as good as that of N = 4 super-Yang-Mills theory through at least four loops.

  5. LARGE AMPLITUDE FREE VIBRATIONS OF LAMINATED COMPOSITE PLATES

    Institute of Scientific and Technical Information of China (English)

    Wang Haowen; Gao Zheng; Zheng Zhaochang

    2000-01-01

    This paper deals with large amplitude free flexural vibrations of laminated composite plates using a 9-node Heterosis degenerated isoparametric quadrilateral element, including the effects of transverse shear and rotary inertia. The nonlinear dynamic equations of the plates are formulated in von Karman's sense. Amplitude-frequemcy relationships are obtained through dynamic response history using the Newmark numerical integration scheme. Detailed numerical results based on various parameters are presented for orthotropic laminated plates with different boundary conditions. The rectangular anti-symmetric cross-ply plates show the softening type of nonlinearity for initial small amplitudes. The displacement amplitudes decrease and nonlinear frequencies increase with the increment of time.

  6. New relations for Einstein-Yang-Mills amplitudes

    Science.gov (United States)

    Stieberger, Stephan; Taylor, Tomasz R.

    2016-12-01

    We obtain new relations between Einstein-Yang-Mills (EYM) amplitudes involving N gauge bosons plus a single graviton and pure Yang-Mills amplitudes involving N gauge bosons plus one additional vector boson inserted in a way typical for a gauge boson of a "spectator" group commuting with the group associated to original N gauge bosons. We show that such EYM amplitudes satisfy U(1) decoupling relations similar to Kleiss-Kuijf relations for Yang-Mills amplitudes. We consider a D-brane embedding of EYM amplitudes in the framework of disk amplitudes involving open and closed strings. A new set of monodromy relations is derived for mixed open-closed amplitudes with one closed string inserted on the disk world-sheet and a number of open strings at the boundary. These relations allow expressing the latter in terms of pure open string amplitudes and, in the field-theory limit, they yield the U(1) decoupling relations for EYM amplitudes.

  7. Cluster functions and scattering amplitudes for six and seven points

    Science.gov (United States)

    Harrington, Thomas; Spradlin, Marcus

    2017-07-01

    Scattering amplitudes in planar super-Yang-Mills theory satisfy several basic physical and mathematical constraints, including physical constraints on their branch cut structure and various empirically discovered connections to the mathematics of cluster algebras. The power of the bootstrap program for amplitudes is inversely proportional to the size of the intersection between these physical and mathematical constraints: ideally we would like a list of constraints which determine scattering amplitudes uniquely. We explore this intersection quantitatively for two-loop six- and seven-point amplitudes by providing a complete taxonomy of the Gr(4, 6) and Gr(4, 7) cluster polylogarithm functions of [15] at weight 4.

  8. Twist decomposition of proton structure from BFKL and BK amplitudes

    CERN Document Server

    Motyka, Leszek

    2014-01-01

    An analysis of twist composition of Balitsky-Kovchegov (BK) amplitude is performed in the double logarithmic limit. In this limit the BK evolution of color dipole -- proton scattering is equivalent to BFKL evolution which follows from vanishing of the Bartels vertex in the collinear limit. We perform twist decomposition of the BFKL/BK amplitude for proton structure functions and find compact analytic expressions that provide accurate approximations for higher twist amplitudes. The BFKL/BK higher twist amplitudes are much smaller than those following from eikonal saturation models.

  9. Method of differential-phase/absolute-amplitude QAM

    Science.gov (United States)

    Dimsdle, Jeffrey William

    2007-07-17

    A method of quadrature amplitude modulation involving encoding phase differentially and amplitude absolutely, allowing for a high data rate and spectral efficiency in data transmission and other communication applications, and allowing for amplitude scaling to facilitate data recovery; amplitude scale tracking to track-out rapid and severe scale variations and facilitate successful demodulation and data retrieval; 2.sup.N power carrier recovery; incoherent demodulation where coherent carrier recovery is not possible or practical due to signal degradation; coherent demodulation; multipath equalization to equalize frequency dependent multipath; and demodulation filtering.

  10. Teogonia - O Nascimento dos Deuses

    OpenAIRE

    Tórma, Alan David dos Santos

    2014-01-01

    O texto grego utilizado foi o da edição inglesa de Hugh G. Evelyn-White (HESIOD, 1914). Foram consultadas a título de comparação as traduções da Teogonia de Ana Lúcia Silveira Cerqueira e Maria Therezinha Áreas Lyra (HESÍODO, 1986), José Antonio Alves Torrano (HESÍODO, 1995), Hugh G. Evelyn-White (HESIOD, 1914) e José Marcos Mariani de Macedo (MACEDO, 2010). Além disso, esta tradução se baseou pelas traduções dos Hinos Homéricos, Edvanda Bonavina da Rosa et alia (2010), e da Odisseia, de Traj...

  11. Las dos triadas de Bejarano

    Directory of Open Access Journals (Sweden)

    González Jorge Iván

    2002-08-01

    Full Text Available El artículo diseute "dos tríadas" que propone Bejarano para calificar a la teoría económica actual. La primera tríada tiene que ver con el realismo, la pertinencia y la relevancia de la teoría. Y la segunda tríada con sus dimensiones política, institucional y moral. El artículo centra la atención en esta segunda tríada, argumentando que la teoría no es apolítica, ainstitucional y amoral como afirma Bejarano. El examen crítico de la posición de Bejarano se sustenta en algunas de las tesis de: Walras, Marshall, Hicks, vickrey, Samuelson y Arrow.

  12. Impacto do internamento em unidade de cuidados intensivos na amplitude de movimento de pacientes graves: estudo piloto

    Directory of Open Access Journals (Sweden)

    Balbino Rivail Ventura Nepomuceno Júnior

    2014-03-01

    Full Text Available Objetivo: Aferir a amplitude de movimento articular de pacientes graves durante o internamento numa unidade de cuidados intensivos. Métodos: Estudo prospectivo e longitudinal, realizado em uma unidade de cuidados intensivos de um hospital público da cidade de Salvador (BA, no período de setembro a novembro de 2010. A principal variável avaliada foi a amplitude de movimento articular passiva, por meio da goniometria dos cotovelos, joelhos e tornozelos, no momento da admissão e na alta. Todos os pacientes internados no período foram incluídos, sendo excluídos aqueles com tempo de internamento <72 horas e com reduções da amplitude de movimento articular na admissão. Resultados: A amostra foi composta por 22 indivíduos, com idade média de 53,5±17,6 anos, tempo de internamento na unidade de cuidados intensivos de 13,0±6,0 e de ventilação mecânica de 12,0±6,3 dias. O APACHE II foi 28,5±7,3, sendo que a maioria dos pacientes era independente funcional previamente ao internamento, com índice de Barthel prévio de 88,8±19. As perdas de amplitude de movimento articular foram 11,1±2,1°; 11,0±2,2°; 8,4±1,7°; 9,2±1,6°; 5,8±0,9° e 5,1±1,0°; para cotovelos, joelhos e tornozelos, respectivamente do lado direito e esquerdo (p<0,001. Conclusão: Houve uma tendência de decréscimo nas amplitudes de movimento de grandes articulações, como tornozelo, joelho e cotovelo, durante o internamento em unidade de cuidados intensivos.

  13. O surgimento dos direitos republicanos

    Directory of Open Access Journals (Sweden)

    Amanda Cristina Carvalho Canezin

    2015-09-01

    Full Text Available O capítulo 8 do livro “Construindo o Estado Republicano: Democracia e reforma da Gestão Pública” do autor Luiz Carlos Bresser-Pereira, tem como tema central o republicanismo. Abordado sob uma perspectiva histórica, o surgimento dos direitos republicanos no Estado ocorreu durante o século XX, influenciado por dois importantes fatos, quais sejam a globalização e a democracia.A obra sugere um estudo sobre a origem do novo Estado democrático, bem como sobre a reforma da gestão pública, abrangendo aspectos políticos, econômicos, enfatizando o direito.O autor inicia o capítulo em análise abrangendo os direitos republicanos, retomando os ideais republicanos dos filósofos e teóricos políticos. No momento em que se observava a retomada do republicanismo notou-se que o mesmo estava efetivado em prática política de cidadãos organizados em uma sociedade civil, onde o cidadão participaria de forma efetiva no Estado ao qual faz parte.Para Bresses-Pereira, direitos republicanos são os direitos assegurados a todos os cidadãos tem ao uso público da res publica – do patrimônio público – inclusive o fluxo de recursos envolvidos nas receitas do Estado e das organizações públicas não-estatais.Denota-se assim que, os direitos republicanos são efetivados no momento em que os cidadãos acastelam o patrimônio público contra as tentativas de captura por indivíduos poderosos. A ampliação da res publica, representada por um terço e por metade da renda de todos os países, fez despertar uma cobiça ainda maior de indivíduos e grupos pelos patrimônios públicos, tornando sua proteção essencial.Novas ferramentas surgiram em defesa da res publica, quando a democracia se tornou o regime político dominante. E assim, se pode dizer que o surgimento dos direitos republicanos e a consolidação da democracia como o regime político dominante fazem parte de um mesmo processo histórico. A democracia transformou-se em “um valor

  14. 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.

  15. Scattering amplitudes in gauge theories: progress and outlook Scattering amplitudes in gauge theories: progress and outlook

    Science.gov (United States)

    Roiban, Radu; Spradlin, Marcus; Volovich, Anastasia

    2011-11-01

    This issue aims to serve as an introduction to our current understanding of the structure of scattering amplitudes in gauge theory, an area which has seen particularly rapid advances in recent years following decades of steady progress. The articles contained herein provide a snapshot of the latest developments which we hope will serve as a valuable resource for graduate students and other scientists wishing to learn about the current state of the field, even if our continually evolving understanding of the subject might soon render this compilation incomplete. Why the fascination with scattering amplitudes, which have attracted the imagination and dedicated effort of so many physicists? Part of it stems from the belief, supported now by numerous examples, that unexpected simplifications of otherwise apparently complicated calculations do not happen by accident. Instead they provide a strong motivation to seek out an underlying explanation. The insight thereby gained can subsequently be used to make the next class of seemingly impossible calculations not only possible, but in some cases even trivial. This two-pronged strategy of exploring and exploiting the structure of gauge theory amplitudes appeals to a wide audience from formal theorists interested in mathematical structure for the sake of its own beauty to more phenomenologically-minded physicists eager to speed up the next generation of analysis software. Understandably it is the maximally supersymmetric 𝒩 = 4 Yang-Mills theory (SYM) which has the simplest structure and has correspondingly received the most attention. Rarely in theoretical physics are we fortunate enough to encounter a toy model which is simple enough to be solved completely yet rich enough to possess interesting non-trivial structure while simultaneously, and most importantly, being applicable (even if only as a good approximation) to a wide range of 'real' systems. The canonical example in quantum mechanics is of course the harmonic

  16. Tratamento dos datos analíticos

    OpenAIRE

    Yebra Biurrun, María del Carmen

    2008-01-01

    Esta unidade didáctica é a primeira toma de contacto do alumnado co estudo do tratamento dos datos analíticos e a comprobación da súa calidade. Este estudo poderase completar máis adiante dentro do programa desta materia cando se presente o resto dos parámetros de calidade dos métodos analíticos. A importancia deste tema radica en que unha vez obtidos os datos analíticos, o primeiro aspecto que se ten que considerar é a verificación da calidade dos mesmos en termos de exactitude e precisió...

  17. One loop amplitude for Heterotic string on $T^2$

    CERN Document Server

    Sasmal, Soumya

    2016-01-01

    We revisit the results of one loop string amplitude calculations for the Heterotic string theory compactified on a torus with or without Wilson lines. We give the complete elliptic genus and the harmonic part of the CP-even amplitude for the gauge groups $SO(32)$, $E_8 \\times E_8$, $SO(16)^2$ and $SO(8)^4$.

  18. 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…

  19. 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.

  20. pi-pi interaction amplitudes with chiral constraints

    OpenAIRE

    Kaminski, Robert

    2000-01-01

    The pi-pi interaction amplitudes have been calculated using a three coupled channel model both with and without constraints imposed by chiral models. Roy's equations have been used to compare the amplitudes and to study the role played by chiral constraints in the pi-pi interaction.

  1. 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...

  2. Loop amplitudes in gauge theories: modern analytic approaches

    Energy Technology Data Exchange (ETDEWEB)

    Britto, Ruth, E-mail: ruth.britto@cea.fr [IPhT, CEA-Saclay, 91191 Gif-sur-Yvette Cedex (France)

    2011-11-11

    This article reviews on-shell methods for analytic computation of loop amplitudes, emphasizing techniques based on unitarity cuts. Unitarity techniques are formulated generally but have been especially useful for calculating one-loop amplitudes in massless theories such as Yang-Mills theory, QCD and QED. (review)

  3. Baryon octet distribution amplitudes in Wandzura-Wilczek approximation

    Energy Technology Data Exchange (ETDEWEB)

    Anikin, I.V. [Joint Institute of Nuclear Research, Moscow (Russian Federation). Bogoliubov Lab. of Theoretical Physics; Regensburg Univ. (Germany). Inst. fuer Theoretische Physik; Manashov, A.N. [Regensburg Univ. (Germany). Inst. fuer Theoretische Physik; Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik

    2015-12-15

    We study higher twist distribution amplitudes for the SU{sub F}(3) baryon octet. We identify independent functions for all baryons in the isospin symmetry limit and calculate the Wandzura-Wilczek contributions to the twist-4 and 5 distributions amplitudes.

  4. Amplitudes in N = 4 Super-Yang-Mills Theory

    Science.gov (United States)

    Spradlin, Marcus

    These lecture notes provide a lightning introduction to some aspects of scattering amplitudes in maximally supersymmetric theory, aimed at the audience of students attending the 2014 TASI summer school "Journeys Through the Precision Frontier: Amplitudes for Colliders". Emphasis is placed on explaining modern terminology so that students needing to delve further may more easily access the available literature.

  5. 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.

  6. Threshold amplitudes in field theories and integrable systems

    CERN Document Server

    Gorsky, A S

    1995-01-01

    We discuss the threshold tree amplitudes in diverse nonintegrable quantum field theories in the framework of integrability. The amplitudes are related to some Baker functions defined on the auxiliary spectral curves and the nullification phenomena are shown to allow a topological interpretation.

  7. Cross-Symmetric Expansion of $\\pi \\pi$ Amplitude Near Threshold

    CERN Document Server

    Bolokhov, A A; Manida, I S; Polyakov, M V; Sherman, S G

    1996-01-01

    The near-threshold expansion of the $\\pi \\pi$ amplitude is developed using the crossing-covariant independent variables. The independent threshold parameters entering the real part of the amplitude in an explicitly Lorentz-invariant way are free from restrictions of isotopic and crossing symmetries. Parameters of the expansion of the imaginary part are recovered by the perturbative unitarity relations.

  8. The Holevo capacity of a generalized amplitude-damping channel

    Institute of Scientific and Technical Information of China (English)

    Hou Li-Zhen; Fang Mao-Fa

    2007-01-01

    The Holevo capacity of a generalized amplitude-damping channel is investigated by using a numerical method.It is shown that the Holevo capacity depends on the channel parameters representing the ambient temperature and fidelity. In particular, under a special condition, the Holevo capacity of the generalized amplitude-damping channel can be written as an analytical expression.

  9. Planar Amplitudes in Maximally Supersymmetric Yang-Mills Theory

    CERN Document Server

    Anastasiou, C; Dixon, L; Kosower, D A

    2003-01-01

    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 AdS/CFT correspondence that the form of the large N_c L-loop amplitudes should be simple enough to allow a resummation to all orders.

  10. On discrete-amplitude signal analysis and its applications

    Institute of Scientific and Technical Information of China (English)

    孙洪; 姚天任

    1997-01-01

    Discrete-amplitude signal analysis is studied. A reconstruction theorem of an arbitrary signal quantized in amplitude hut continuous in time, from 2 bits of its binary representation, is devised. A new concept of discrete-amplitude multiresolution (DAM), with the signal representation precision taken as its scale, is proposed. The singularities and the residue reducing effect of 2-bit reconstruction of some discrete-time signals are investigated. Two practical examples of applying the discrete-amplitude signal analysis to data compression and signal detection are presented It is shown both analytically and practically that the discrete-amplitude signal analysis is of simple formulation, parallel processing and efficient computation, and is well suited to hardware implementation and real-time signal processing

  11. Conformal higher spin scattering amplitudes from twistor space

    CERN Document Server

    Adamo, Tim; McLoughlin, Tristan

    2016-01-01

    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 anti-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.

  12. Discontinuites of BFKL amplitudes and the BDS ansatz

    CERN Document Server

    Fadin, V S

    2015-01-01

    We perform an examination of discontinuities of multiple production amplitudes, which are required for further development of the BFKL approach. It turns out that the discontinuities of 2 $\\to$ 2 + n amplitudes obtained in the BFKL approach contradict to the BDS ansatz for amplitudes with maximal helicity violation in N = 4 supersymmetric Yang-Mills theory with large number of colours starting with n = 2. Explicit expressions for the discontinuities of the 2 $\\to$ 3 and 2 $\\to$ 4 amplitudes in the invariant mass of pairs of produced gluons are obtained in the planar N=4 SYM in the next-to-leading logarithmic approximation. These expressions can be used for checking the conjectured duality between the light-like Wilson loops and the MHV amplitudes.

  13. Discontinuities of BFKL amplitudes and the BDS ansatz

    Science.gov (United States)

    Fadin, V. S.; Fiore, R.

    2015-12-01

    We perform an examination of discontinuities of multiple production amplitudes, which are required for further development of the BFKL approach. It turns out that the discontinuities of 2 → 2 + n amplitudes obtained in the BFKL approach contradict to the BDS ansatz for amplitudes with maximal helicity violation in N = 4 supersymmetric Yang-Mills theory with large number of colors starting with n = 2. Explicit expressions for the discontinuities of the 2 → 3 and 2 → 4 amplitudes in the invariant mass of pairs of produced gluons are obtained in the planar N = 4 SYM in the next-to-leading logarithmic approximation. These expressions can be used for checking the conjectured duality between the light-like Wilson loops and the MHV amplitudes.

  14. Effective Field Theories from Soft Limits of Scattering Amplitudes.

    Science.gov (United States)

    Cheung, Clifford; Kampf, Karol; Novotny, Jiri; Trnka, Jaroslav

    2015-06-05

    We derive scalar effective field theories-Lagrangians, symmetries, and all-from on-shell scattering amplitudes constructed purely from Lorentz invariance, factorization, a fixed power counting order in derivatives, and a fixed order at which amplitudes vanish in the soft limit. These constraints leave free parameters in the amplitude which are the coupling constants of well-known theories: Nambu-Goldstone bosons, Dirac-Born-Infeld scalars, and Galilean internal shift symmetries. Moreover, soft limits imply conditions on the Noether current which can then be inverted to derive Lagrangians for each theory. We propose a natural classification of all scalar effective field theories according to two numbers which encode the derivative power counting and soft behavior of the corresponding amplitudes. In those cases where there is no consistent amplitude, the corresponding theory does not exist.

  15. The scattering amplitude for rationally extended shape invariant Eckart potentials

    Energy Technology Data Exchange (ETDEWEB)

    Yadav, Rajesh Kumar, E-mail: rajeshastrophysics@gmail.com [Department of Physics, Banaras Hindu University, Varanasi-221005 (India); Khare, Avinash, E-mail: khare@iiserpune.ac.in [Raja Ramanna Fellow, Indian Institute of Science Education and Research (IISER), Pune-411021 (India); Mandal, Bhabani Prasad, E-mail: bhabani.mandal@gmail.com [Department of Physics, Banaras Hindu University, Varanasi-221005 (India)

    2015-01-23

    Highlights: • Bound states of rationally extended Eckart potentials have been discussed. • These potentials exhibit extended shape invariant properties. • The potentials which are isospectral to the conventional Eckart potential are considered. • The scattering amplitude of these potentials has been obtained. • For a check, m=0 provide the scattering amplitude for the conventional potential. - Abstract: We consider the rationally extended exactly solvable Eckart potentials which exhibit extended shape invariance property. These potentials are isospectral to the conventional Eckart potential. The scattering amplitude for these rationally extended potentials is calculated analytically for the generalized mth (m=1,2,3,...) case by considering the asymptotic behavior of the scattering state wave functions which are written in terms of some new polynomials related to the Jacobi polynomials. As expected, in the m=0 limit, this scattering amplitude goes over to the scattering amplitude for the conventional Eckart potential.

  16. Discontinuities of BFKL amplitudes and the BDS ansatz

    Directory of Open Access Journals (Sweden)

    V.S. Fadin

    2015-12-01

    Full Text Available We perform an examination of discontinuities of multiple production amplitudes, which are required for further development of the BFKL approach. It turns out that the discontinuities of 2→2+n amplitudes obtained in the BFKL approach contradict to the BDS ansatz for amplitudes with maximal helicity violation in N=4 supersymmetric Yang–Mills theory with large number of colors starting with n=2. Explicit expressions for the discontinuities of the 2→3 and 2→4 amplitudes in the invariant mass of pairs of produced gluons are obtained in the planar N=4 SYM in the next-to-leading logarithmic approximation. These expressions can be used for checking the conjectured duality between the light-like Wilson loops and the MHV amplitudes.

  17. Bilocal expansion of Borel amplitude and hadronic tau decay width

    CERN Document Server

    Cvetic, G; Cvetic, Gorazd; Lee, Taekoon

    2001-01-01

    The singular part of Borel transform of a QCD amplitude near the infrared renormalon can be expanded in terms of higher order Wilson coefficients of the operators associated with the renormalon. In this paper we observe that this expansion gives nontrivial constraints on the Borel amplitude that can be used to improve the accuracy of the ordinary perturbative expansion of the Borel amplitude. In particular, we consider the Borel transform of the Adler function and its expansion around the first infrared renormalon due to the gluon condensate. Using the next-to-leading order Wilson coefficient of the gluon condensate operator, we obtain an exact constraint on the Borel amplitude at the first IR renormalon. We then extrapolate, using judiciously chosen conformal transformations and Pade approximants, the ordinary perturbative expansion of the Borel amplitude in such a way that this constraint is satisfied. This procedure allows us to predict the four-loop Adler function, which gives a result consistent with the...

  18. 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.)

  19. New Formulas for Amplitudes from Higher-Dimensional Operators

    CERN Document Server

    He, Song

    2016-01-01

    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.

  20. New amplitude equation of single-mode laser

    Institute of Scientific and Technical Information of China (English)

    张莉; 曹力; 吴大进

    2003-01-01

    The white-gain model and the white-loss model of a single-mode laser are investigated in the presence of crosscorrelations between the real and imaginary parts of quantum noise as well as pump noise. It was found that, like the white cubic model (2001 Chin. Phys. Lett. 18 370), the amplitude equations are all decoupled from the phase equations for the two models, and the same novel term appears in the amplitude equations of the two models. So we can put the amplitude equations of all the models into a general form, that is, the new amplitude equation. We further use this new amplitude equation to study specifically the stationary properties of the laser intensity for the white-gain model.

  1. 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.

  2. Vibration of low amplitude imaged in amplitude and phase by sideband versus carrier correlation digital holography

    CERN Document Server

    Verrier, N; Gross, M

    2015-01-01

    Sideband holography can be used to get fields images (E0 and E1) of a vibrating object for both the carrier (E0) and the sideband (E1) frequency with respect to vibration. We propose here to record E0 and E1 sequentially, and to image the correlation E1E * 0 . We show that this correlation is insensitive the phase related to the object roughness and directly reflect the phase of the mechanical motion. The signal to noise can be improved by averaging the correlation over neighbor pixel. Experimental validation is made with vibrating cube of wood and with a clarinet reed. At 2 kHz, vibrations of amplitude down to 0.01 nm are detected.

  3. Modulación por ancho de pulso (PWM) y modulación vectorial (SVM). Una introducción a las técnicas de modulación

    OpenAIRE

    Posada Contreras, Johnny

    2005-01-01

    Los conversores DC/AC tienen por objetivo la transformación de tensión DC a tensión AC de amplitud y/o frecuencia variable dependiendo de la aplicación. El proceso de conversión de voltaje se logra mediante la implementación de técnicas de modulación, las cuales actúan sobre un puente inversor monofásico o trifásico. Según las características de estas técnicas, las propiedades de eficiencia en la conversión, contenido armónico de la señal de salida y pérdidas en el puente inversor cambian. En...

  4. Perfil dos idosos que cochilam

    Directory of Open Access Journals (Sweden)

    Ariene Angelini dos Santos

    2013-12-01

    Full Text Available Esse estudo objetivou caracterizar os idosos que cochilam segundo as características sociodemográficas e de fragilidade. Estudo descritivo, transversal, recorte do projeto multicêntrico Fragilidade em Idosos Brasileiros. Foram avaliados 1.866 idosos utilizando-se questionário sociodemográfico. A fragilidade foi avaliada usando o fenótipo proposto por Fried. Os dados foram tratados com estatística descritiva. Os resultados apontaram que o perfil do idoso que cochila foi constituído predominantemente por mulheres, casadas, aposentadas, pré-frágeis, com média de idade de 73 anos, quatro anos de estudo, renda familiar mensal de 3,9 salários mínimos, com 4,4 filhos e que residiam apenas com eles. Os idosos relataram cochilar em média 5,9 dias por semana, com duração de 53,5 minutos por cochilo. Conhecer o perfil do idoso que cochila contribui para os profissionais de saúde desenvolverem ações em relação aos problemas de sono dos idosos frágeis/pré-frágeis, prevenindo, minimizando ou resolvendo esses problemas.

  5. Efeito da frequência e amplitude de vibração sobre a derriça de frutos de café Frequency and amplitude of vibration on coffee harvesting

    Directory of Open Access Journals (Sweden)

    Fábio L. Santos

    2010-04-01

    Full Text Available Parâmetros de qualidade podem alterar significativamente o preço do café; entretanto, a colheita seletiva dos frutos é frequentemente associada à boa qualidade do produto, procedimento que pode ser realizado por meio de vibrações mecânicas. Desta forma, o estudo e a avaliação do efeito localizado de fatores como frequência, amplitude e grau de maturação dos frutos, são fundamentais para construção de máquinas adequadas a este tipo de prática. O trabalho foi desenvolvido com o objetivo de se avaliar os fatores frequência, amplitude, grau de maturação, direção de excitação e número de frutos por pedúnculo, na eficiência de derriça. Para a realização dos ensaios de vibração em laboratório utilizou-se uma máquina vibradora eletromagnética. Amplitudes na faixa de 3,75 a 7,50 mm e frequências na faixa de 13,33 a 26,67 Hz foram testadas para a variedade Mundo Novo, em que os resultados mostraram que a frequência de 26,67 Hz apresentou uma eficiência maior de derriça para os frutos cereja e a amplitude de 7,5 mm indicou maior eficiência de derriça. Verificou-se, também, que o número de frutos por pedúnculo influencia a eficiência de derriça dos frutos de café da variedade Mundo Novo.Quality parameters influence directly the coffee price. However, selective coffee harvesting is frequently associated to good quality of this product. This procedure can be performed by mechanical vibration. Therefore, the study of the frequency and amplitude parameters is important for the design of a specific harvesting machine. The objective of this work was to evaluate the effect of the frequency and amplitude of vibration, the coffee variety and the ripeness condition of the fruits upon the harvesting efficiency. The vibration tests were done in laboratory using an electromagnetic shaker. The tests were done using amplitudes in the range of 3.75 to 7.50 mm and frequencies in the range of 13.33 to 16.67 Hz. Branches of

  6. O Conceito Kantiano de Metafisica dos Costumes

    Directory of Open Access Journals (Sweden)

    Joel Thiago Klein

    2009-06-01

    Full Text Available Neste texto reconstrói-se o conceito kantiano de metafísica dos costumes com o objetivo de apresentar claramente os seus aspectos essenciais, mas sem entrar em questões relativas a sua legitimidade. Nas primeiras duas partes do trabalho mostra-se como Kant reinterpreta a divisão geral da filosofia e como o conceito de uma metafísica dos costumes passa a ser visto a partir do empreendimento crítico-transcendental. Na terceira parte aponta-se para algumas nuances e ambigüidades do conceito de “Metafísica dos costumes”. Por fim, enumera-se os motivos teóricos e práticos a partir dos quais Kant defende a necessidade de uma Metafísica dos costumes.

  7. Amplitude path corrections for regional phases in China

    Energy Technology Data Exchange (ETDEWEB)

    Phillips, W.S.; Velasco, A.A.; Taylor, S.R.; Randall, G.E.

    1998-12-31

    The authors investigate the effectiveness of amplitude path corrections for regional phases on seismic event discrimination and magnitude estimation. Waveform data from digital stations in China for regional, shallow (< 50 km) events were obtained from the IRIS Data Management Center (DMC) for years 1986 to 1996 using the USGS Preliminary Determination of Epicenters (PDE) and the Chinese State Seismological Bureau (SSB) catalogs. For each event, the amplitudes for each regional phase (P{sub n}, P{sub g}, S{sub n}, L{sub g}) were measured, as well as the P{sub g} and L{sub g} coda. Measured amplitudes were corrected for source scaling using estimates of m{sub b} and for distance using a power law that accounts for attenuation and spreading. The amplitude residuals were interpolated and mapped as 2-D amplitude correction surfaces. The authors employ several methods to create the amplitude correction surfaces: a waveguide method, and two interpolation methods (Baysian kriging and a circular moving window mean smoother). They explore the sensitivities of the surfaces to the method and to regional propagation, and apply these surfaces to correct amplitude data to reduce scatter in discrimination ratios and magnitude estimates.

  8. Amplitudes of stellar oscillations the implications for asteroseismology

    CERN Document Server

    Kjeldsen, H

    1994-01-01

    There are no good predictions for the amplitudes expected from solar-like oscillations in other stars. In the absence of a definitive model for convection, which is thought to be the mechanism that excites these oscillations, the amplitudes for both velocity and luminosity measurements must be estimated by scaling from the Sun. In the case of luminosity measurements, even this is difficult because of disagreement over the solar amplitude. This last point has lead us to investigate whether the luminosity amplitude of oscillations (dL/L) can be derived from the velocity amplitude v_osc. Using linear theory and observational data, we show that p-mode oscillations in a large sample of pulsating stars satisfy (dL/L)_bol proportional to v_osc/T_eff. Using this relationship, together with the best estimate of v_osc(Sun) = (23.4 +/- 1.4) cm/s, we estimate the luminosity amplitude of solar oscillations at 550 nm to be dL/L = (4.7 +/- 0.3) ppm. Next we discuss how to scale the amplitude of solar-like (i.e., convectivel...

  9. Broadband metasurface holograms: toward complete phase and amplitude engineering

    Science.gov (United States)

    Wang, Qiu; Zhang, Xueqian; Xu, Yuehong; Gu, Jianqiang; Li, Yanfeng; Tian, Zhen; Singh, Ranjan; Zhang, Shuang; Han, Jiaguang; Zhang, Weili

    2016-09-01

    As a revolutionary three-dimensional imaging technique, holography has attracted wide attention for its ability to photographically record a light field. However, traditional phase-only or amplitude-only modulation holograms have limited image quality and resolution to reappear both amplitude and phase information required of the objects. Recent advances in metasurfaces have shown tremendous opportunities for using a planar design of artificial meta-atoms to shape the wave front of light by optimal control of both its phase and amplitude. Inspired by the concept of designer metasurfaces, we demonstrate a novel amplitude-phase modulation hologram with simultaneous five-level amplitude modulation and eight-level phase modulation. Such a design approach seeks to turn the perceived disadvantages of the traditional phase or amplitude holograms, and thus enable enhanced performance in resolution, homogeneity of amplitude distribution, precision, and signal-to-noise ratio. In particular, the unique holographic approach exhibits broadband characteristics. The method introduced here delivers more degrees of freedom, and allows for encoding highly complex information into designer metasurfaces, thus having the potential to drive next-generation technological breakthroughs in holography.

  10. Bootstrapping Multi-Parton Loop Amplitudes in QCD

    Energy Technology Data Exchange (ETDEWEB)

    Bern, Zvi; /UCLA; Dixon, Lance J.; /SLAC; Kosower, David A.; /Saclay, SPhT

    2005-07-06

    The authors present a new method for computing complete one-loop amplitudes, including their rational parts, in non-supersymmetric gauge theory. This method merges the unitarity method with on-shell recursion relations. It systematizes a unitarity-factorization bootstrap approach previously applied by the authors to the one-loop amplitudes required for next-to-leading order QCD corrections to the processes e{sup +}e{sup -} {yields} Z, {gamma}* {yields} 4 jets and pp {yields} W + 2 jets. We illustrate the method by reproducing the one-loop color-ordered five-gluon helicity amplitudes in QCD that interfere with the tree amplitude, namely A{sub 5;1}(1{sup -}, 2{sup -}, 3{sup +}, 4{sup +}, 5{sup +}) and A{sub 5;1}(1{sup -}, 2{sup +}, 3{sup -}, 4{sup +}, 5{sup +}). Then we describe the construction of the six- and seven-gluon amplitudes with two adjacent negative-helicity gluons, A{sub 6;1}(1{sup -}, 2{sup -}, 3{sup +}, 4{sup +}, 5{sup +}, 6{sup +}) and A{sub 7;1}(1{sup -}, 2{sup -}, 3{sup +}, 4{sup +}, 5{sup +}, 6{sup +}, 7{sup +}), which uses the previously-computed logarithmic parts of the amplitudes as input. They present a compact expression for the six-gluon amplitude. No loop integrals are required to obtain the rational parts.

  11. Frequency adaptation for enhanced radiation force amplitude in dynamic elastography.

    Science.gov (United States)

    Ouared, Abderrahmane; Montagnon, Emmanuel; Kazemirad, Siavash; Gaboury, Louis; Robidoux, André; Cloutier, Guy

    2015-08-01

    In remote dynamic elastography, the amplitude of the generated displacement field is directly related to the amplitude of the radiation force. Therefore, displacement improvement for better tissue characterization requires the optimization of the radiation force amplitude by increasing the push duration and/or the excitation amplitude applied on the transducer. The main problem of these approaches is that the Food and Drug Administration (FDA) thresholds for medical applications and transducer limitations may be easily exceeded. In the present study, the effect of the frequency used for the generation of the radiation force on the amplitude of the displacement field was investigated. We found that amplitudes of displacements generated by adapted radiation force sequences were greater than those generated by standard nonadapted ones (i.e., single push acoustic radiation force impulse and supersonic shear imaging). Gains in magnitude were between 20 to 158% for in vitro measurements on agar-gelatin phantoms, and 170 to 336% for ex vivo measurements on a human breast sample, depending on focus depths and attenuations of tested samples. The signal-to-noise ratio was also improved more than 4-fold with adapted sequences. We conclude that frequency adaptation is a complementary technique that is efficient for the optimization of displacement amplitudes. This technique can be used safely to optimize the deposited local acoustic energy without increasing the risk of damaging tissues and transducer elements.

  12. Variable-amplitude oscillatory shear response of amorphous materials

    Science.gov (United States)

    Perchikov, Nathan; Bouchbinder, Eran

    2014-06-01

    Variable-amplitude oscillatory shear tests are emerging as powerful tools to investigate and quantify the nonlinear rheology of amorphous solids, complex fluids, and biological materials. Quite a few recent experimental and atomistic simulation studies demonstrated that at low shear amplitudes, an amorphous solid settles into an amplitude- and initial-conditions-dependent dissipative limit cycle, in which back-and-forth localized particle rearrangements periodically bring the system to the same state. At sufficiently large shear amplitudes, the amorphous system loses memory of the initial conditions, exhibits chaotic particle motions accompanied by diffusive behavior, and settles into a stochastic steady state. The two regimes are separated by a transition amplitude, possibly characterized by some critical-like features. Here we argue that these observations support some of the physical assumptions embodied in the nonequilibrium thermodynamic, internal-variables based, shear-transformation-zone model of amorphous viscoplasticity; most notably that "flow defects" in amorphous solids are characterized by internal states between which they can make transitions, and that structural evolution is driven by dissipation associated with plastic deformation. We present a rather extensive theoretical analysis of the thermodynamic shear-transformation-zone model for a variable-amplitude oscillatory shear protocol, highlighting its success in accounting for various experimental and simulational observations, as well as its limitations. Our results offer a continuum-level theoretical framework for interpreting the variable-amplitude oscillatory shear response of amorphous solids and may promote additional developments.

  13. Color-factor symmetry and BCJ relations for QCD amplitudes

    CERN Document Server

    Brown, Robert W

    2016-01-01

    Tree-level $n$-point gauge-theory amplitudes with $n-2k$ gluons and $k$ pairs of (massless or massive) particles in the fundamental (or other) representation of the gauge group are invariant under a set of symmetries that act as momentum-dependent shifts on the color factors in the cubic decomposition of the amplitude. These symmetries lead to gauge-invariant constraints on the kinematic numerators. They also directly imply the BCJ relations among the Melia-basis primitive amplitudes previously obtained by Johansson and Ochirov.

  14. Higher Twist Distribution Amplitudes of the Nucleon in QCD

    CERN Document Server

    Braun, V M; Mahnke, N; Stein, E

    2000-01-01

    We present the first systematic study of higher-twist light-cone distribution amplitudes of the nucleon in QCD. We find that the valence three-quark state is described at small transverse separations by eight independent distribution amplitudes. One of them is leading twist-3, three distributions are twist-4 and twist-5, respectively, and one is twist-6. A complete set of distribution amplitudes is constructed, which satisfies equations of motion and constraints that follow from conformal expansion. Nonperturbative input parameters are estimated from QCD sum rules.

  15. Symmetry limit properties of decay amplitudes with mirror matter admixtures

    CERN Document Server

    Sánchez-Colón, G; Sanchez-Colon, Gabriel; Garcia, Augusto

    2006-01-01

    We extend our previous analysis on the symmetry limit properties of non-leptonic and weak radiative decay amplitudes of hyperons in a scheme of mirror matter admixtures in physical hadrons to include the two-body non-leptonic decays of $\\Omega^-$ and the two photon and two pion decays of kaons. We show that the so-called parity-conserving amplitudes predicted for all the decays vanish in the strong flavor SU(3) symmetry limit. We also establish the specific conditions under which the corresponding so-called parity-violating amplitudes vanish in the same limit.

  16. Statistical multiresolution analysis in amplitude-frequency domain

    Institute of Scientific and Technical Information of China (English)

    SUN Hong; GUAN Bao; Henri Maitre

    2004-01-01

    A concept of statistical multiresolution analysis in amplitude-frequency domain is proposed, which is to employ the wavelet transform on the statistical character of a signal in amplitude domain. In terms of the theorem of generalized ergodicity, an algorithm to estimate the transform coefficients based on the amplitude statistical multiresolution analysis (AMA) is presented. The principle of applying the AMA to Synthetic Aperture Radar (SAR) image processing is described, and the good experimental results imply that the AMA is an efficient tool for processing of speckled signals modeled by the multiplicative noise.

  17. Fatigue independent amplitude-frequency correlations in EMG signals

    CERN Document Server

    Siemienski, A; Klajner, P; Siemienski, Adam; Kebel, Alicja; Klajner, Piotr

    2006-01-01

    In order to assess fatigue independent amplitude-frequency correlations in EMG signals we asked nineteen male subjects to perform a series of isometric muscular contractions by extensors of the knee joint. Different amplitudes of the signal were due to randomly varying both the joint moment and the overall amplification factor of the EMG apparatus. Mean and median frequency, RMS and mean absolute value were calculated for every combination of joint moment and amplification at the original sampling rate of 5 kHz and at several simulated lower sampling rates. Negative Spearman and Kendall amplitude-frequency correlation coefficients were found, and they were more pronounced at high sampling rates.

  18. Nonlinear Effects in the Amplitude of Cosmological Density Fluctuations

    CERN Document Server

    Juszkiewicz, Roman; Fry, J N; Jaffe, Andrew H

    2009-01-01

    The amplitude of cosmological density fluctuations, $\\sigma_8$, has been studied and estimated by analysing many cosmological observations. The values of the estimates vary considerably between the various probes. However, different estimators probe the value of $\\sigma_8$ in different cosmological scales and do not take into account the nonlinear evolution of the parameter at late times. We show that estimates of the amplitude of cosmological density fluctuations derived from cosmic flows are systematically higher than those inferred at early epochs because of nonlinear evolution at later times. Here we derive corrections to the value of $\\sigma_8$ and compare amplitudes after accounting for this effect.

  19. Compact multigluonic scattering amplitudes with heavy scalars and fermions

    CERN Document Server

    Ferrario, P; Talavera, P; Ferrario, Paola; Rodrigo, German; Talavera, Pere

    2006-01-01

    Combining the Berends-Giele and on-shell recursion relations we obtain an extremely compact expression for the scattering amplitude of a complex scalar-antiscalar pair and an arbitrary number of positive helicity gluons. This is one of the basic building blocks for constructing other helicity configurations from recursion relations. We also show explicity that the all positive helicity gluons amplitude for heavy fermions is proportional to the scalar one, confirming in this way the recently advocated SUSY-like Ward identities relating both amplitudes.

  20. Spectroscopic amplitudes and microscopic substructure effects in nucleon capture reactions

    CERN Document Server

    Escher, J; Sherif, H S; Escher, Jutta; Jennings, Byron K.; Sherif, Helmy S.

    2001-01-01

    Spectroscopic amplitudes play an important role in nuclear capture reactions. These amplitudes are shown to include both single-particle and polarization effects: the former through their spatial dependence and the latter through their normalization (the spectroscopic factors). Coupled-channels equations are developed for the spectroscopic amplitudes. These equations serve as a convenient starting point for the derivation of several approximations: Hartree, Hartree-Fock and two different single-particle models. The single-particle models include antisymmetry in different ways, but both miss many-body effects. Therefore, cross sections calculated with either of these models need to be multiplied by the spectroscopic factor.

  1. Phase Synchronization of Coupled Rossler Oscillators: Amplitude Effect

    Institute of Scientific and Technical Information of China (English)

    LI Xiao-Wen; ZHENG Zhi-Gang

    2007-01-01

    Phase synchronization of two linearly coupled Rossler oscillators with parameter misfits is explored.It is found that depending on parameter mismatches,the synchronization of phases exhibits different manners.The synchronization regime can be divided into three regimes.For small mismatches,the amplitude-insensitive regime gives the phase-dominant synchronization; When the parameter misfit increases,the amplitudes and phases of oscillators are correlated,and the amplitudes will dominate the synchronous dynamics for very large mismatches.The lag time among phases exhibits a power law when phase synchronization is achieved.

  2. 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'.

  3. 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.

  4. 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...

  5. Next-to-Maximal Helicity Violating Amplitudes in Gauge Theory

    CERN Document Server

    Kosower, D A

    2004-01-01

    Using the novel diagrammatic rules recently proposed by Cachazo, Svrcek, and Witten, I give a compact, manifestly Lorentz-invariant form for tree-level gauge-theory amplitudes with three opposite helicities.

  6. One-Loop Corrections to Five-Gluon Amplitudes

    CERN Document Server

    Bern, Z; Kosower, D A

    1993-01-01

    We present the one-loop helicity amplitudes with five external gluons. The computation employs string-based methods, new techniques for performing tensor integrals, and improvements in the spinor helicity method.

  7. High Amplitude (delta)-Scutis in the Large Magellanic Cloud

    Energy Technology Data Exchange (ETDEWEB)

    Garg, A; Cook, K H; Nikolaev, S; Huber, M E; Rest, A; Becker, A C; Challis, P; Clocchiatti, A; Miknaitis, G; Minniti, D; Morelli, L; Olsen, K; Prieto, J L; Suntzeff, N B; Welch, D L; Wood-Vasey, W M

    2010-01-25

    The authors present 2323 High-Amplitude {delta}-Scutis (HADS) candidates discovered in the Large Magellanic Cloud (LMC) by the SuperMACHO survey (Rest et al. 2005). Frequency analyses of these candidates reveal that several are multimode pulsators, including 119 whose largest amplitude of pulsation is in the fundamental (F) mode and 19 whose largest amplitude of pulsation is in the first overtone (FO) mode. Using Fourier decomposition of the HADS light curves, they find that the period-luminosity (PL) relation defined by the FO pulsators does not show a clear separation from the PL-relation defined by the F pulsators. This differs from other instability strip pulsators such as type c RR Lyrae. They also present evidence for a larger amplitude, subluminous population of HADS similar to that observed in Fornax (Poretti et al. 2008).

  8. Movement amplitude and tempo change in piano performance

    Science.gov (United States)

    Palmer, Caroline

    2004-05-01

    Music performance places stringent temporal and cognitive demands on individuals that should yield large speed/accuracy tradeoffs. Skilled piano performance, however, shows consistently high accuracy across a wide variety of rates. Movement amplitude may affect the speed/accuracy tradeoff, so that high accuracy can be obtained even at very fast tempi. The contribution of movement amplitude changes in rate (tempo) is investigated with motion capture. Cameras recorded pianists with passive markers on hands and fingers, who performed on an electronic (MIDI) keyboard. Pianists performed short melodies at faster and faster tempi until they made errors (altering the speed/accuracy function). Variability of finger movements in the three motion planes indicated most change in the plane perpendicular to the keyboard across tempi. Surprisingly, peak amplitudes of motion before striking the keys increased as tempo increased. Increased movement amplitudes at faster rates may reduce or compensate for speed/accuracy tradeoffs. [Work supported by Canada Research Chairs program, HIMH R01 45764.

  9. Some tree-level string amplitudes in the NSR formalism

    Energy Technology Data Exchange (ETDEWEB)

    Becker, Katrin; Becker, Melanie [George P. and Cynthia W. Mitchell Institute for Fundamental Physics and Astronomy,Texas A& M University,4242 TAMU, College Station, TX 77843 (United States); Melnikov, Ilarion V. [Department of Mathematics, Harvard University,One Oxford Street, Cambridge, MA 02138 (United States); Robbins, Daniel; Royston, Andrew B. [George P. and Cynthia W. Mitchell Institute for Fundamental Physics and Astronomy,Texas A& M University,4242 TAMU, College Station, TX 77843 (United States)

    2015-12-02

    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{sup 4} effective action. Finally we use the prescription of Kawai, Lewellen and Tye (KLT) to compute the amplitudes for the closed string sector.

  10. 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.)

  11. Scattering Amplitudes/Wilson Loop Duality In ABJM Theory

    CERN Document Server

    Bianchi, Marco S; Mauri, Andrea; Penati, Silvia; Santambrogio, Alberto

    2011-01-01

    For N=6 superconformal Chern-Simons-matter theories in three dimensions, by a direct superspace Feynman diagram approach, we compute the two-loop four-point scatteringa amplitude with external chiral matter fields. We find that the result is in perfect agreement with the two-loop result for a light-like four-polygon Wilson loop. This is a nontrivial evidence of the scattering amplitudes/Wilson loop duality in three dimensions. Moreover, both the IR divergent and the finite parts of our two-loop result agree with a BDS-like ansatz for all-loop amplitudes where the scaling function is given in terms of the N=4 SYM one, according to the conjectured Bethe equations for ABJM. Consequently, we are able to make a prediction for the four-loop correction to the amplitude. We also discuss the dual conformal invariance of the two-loop result.

  12. BFKL approach and 2->5 MHV amplitude

    CERN Document Server

    Bartels, J; Lipatov, L N; Prygarin, A

    2011-01-01

    We study MHV amplitude for the 2 -> 5 scattering in the multi-Regge kinematics. The Mandelstam cut correction to the BDS amplitude is calculated in the leading logarithmic approximation (LLA) and the corresponding remainder function is given to any loop order in a closed integral form. We show that the LLA remainder function at two loops for 2 -> 5 amplitude can be written as a sum of two 2 -> 4 remainder functions due to recursive properties of the leading order impact factors. We also make some generalizations for the MHV amplitudes with more external particles. The results of the present study are in agreement with all leg two loop symbol derived by Caron-Huot as shown in a parallel paper of one of the authors with collaborators.

  13. Amplitude Equation for Instabilities Driven at Deformable Surfaces - Rosensweig Instability

    Science.gov (United States)

    Pleiner, Harald; Bohlius, Stefan; Brand, Helmut R.

    2008-11-01

    The derivation of amplitude equations from basic hydro-, magneto-, or electrodynamic equations requires the knowledge of the set of adjoint linear eigenvectors. This poses a particular problem for the case of a free and deformable surface, where the adjoint boundary conditions are generally non-trivial. In addition, when the driving force acts on the system via the deformable surface, not only Fredholm's alternative in the bulk, but also the proper boundary conditions are required to get amplitude equations. This is explained and demonstrated for the normal field (or Rosensweig) instability in ferrofluids as well as in ferrogels. An important aspect of the problem is its intrinsic dynamic nature, although at the end the instability is stationary. The resulting amplitude equation contains cubic and quadratic nonlinearities as well as first and (in the gel case) second order time derivatives. Spatial variations of the amplitudes cannot be obtained by using simply Newell's method in the bulk.

  14. Analytic computations of massive one-loop amplitudes

    Energy Technology Data Exchange (ETDEWEB)

    Badger, Simon; Yundin, Valery [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Sattler, Ralf [Berlin Univ. (Germany). Inst. fuer Physik

    2010-06-15

    We show some new applications of on-shell methods to calculate compact helicity amplitudes for t anti t production through gluon fusion. The rational and mass renormalisation contributions are extracted from two independent Feynman diagram based approaches. (orig.)

  15. N >= 4 Supergravity Amplitudes from Gauge Theory at Two Loops

    Energy Technology Data Exchange (ETDEWEB)

    Boucher-Veronneau, C.; Dixon, L.J.; /SLAC

    2012-02-15

    We present the full two-loop four-graviton amplitudes in N = 4, 5, 6 supergravity. These results were obtained using the double-copy structure of gravity, which follows from the recently conjectured color-kinematics duality in gauge theory. The two-loop four-gluon scattering amplitudes in N = 0, 1, 2 supersymmetric gauge theory are a second essential ingredient. The gravity amplitudes have the expected infrared behavior: the two-loop divergences are given in terms of the squares of the corresponding one-loop amplitudes. The finite remainders are presented in a compact form. The finite remainder for N = 8 supergravity is also presented, in a form that utilizes a pure function with a very simple symbol.

  16. Some tree-level string amplitudes in the NSR formalism

    CERN Document Server

    Becker, Katrin; 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.

  17. 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.

  18. The QCD triple Pomeron coupling from string amplitudes

    CERN Document Server

    Bialas, A; Peschanski, R

    1998-01-01

    Using the recent solution of the triple Pomeron coupling in the QCD dipole picture as a closed string amplitude with six legs, its analytical form in terms of hypergeometric functions and numerical value are derived.

  19. Cluster Functions and Scattering Amplitudes for Six and Seven Points

    CERN Document Server

    Harrington, Thomas

    2015-01-01

    Scattering amplitudes in planar super-Yang-Mills theory satisfy several basic physical and mathematical constraints, including physical constraints on their branch cut structure and various empirically discovered connections to the mathematics of cluster algebras. The power of the bootstrap program for amplitudes is inversely proportional to the size of the intersection between these physical and mathematical constraints: ideally we would like a list of constraints which determine scattering amplitudes uniquely. We explore this intersection quantitatively for two-loop six- and seven-point amplitudes by providing a complete taxonomy of the Gr(4,6) and Gr(4,7) cluster polylogarithm functions of arXiv:1401.6446 at weight 4.

  20. High Amplitude (delta)-Scutis in the Large Magellanic Cloud

    National Research Council Canada - National Science Library

    Garg, A; Cook, K H; Nikolaev, S; Huber, M E; Rest, A; Becker, A C; Challis, P; Clocchiatti, A; Miknaitis, G; Minniti, D; Morelli, L; Olsen, K; Prieto, J L; Suntzeff, N B; Welch, D L; Wood-Vasey, W M

    2010-01-01

    ... (LMC) by the SuperMACHO survey (Rest et al. 2005). Frequency analyses of these candidates reveal that several are multimode pulsators, including 119 whose largest amplitude of pulsation is in the fundamental (F...

  1. Quantized amplitudes in a nonlinear resonant electrical circuit

    CERN Document Server

    Cretin, B

    2008-01-01

    We present a simple nonlinear resonant analog circuit which demonstrates quantization of resonating amplitudes, for a given excitation level. The system is a simple RLC resonator where C is an active capacitor whose value is related to the current in the circuit. This variation is energetically equivalent to a variation of the potential energy and the circuit acts as a pendulum in the gravitational field. The excitation voltage, synchronously switched at the current frequency, enables electrical supply and keeping the oscillation of the system. The excitation frequency has been set to high harmonic of the fundamental oscillation so that anisochronicity can keep constant the amplitude of the circuit voltage and current. The behavior of the circuit is unusual: different stable amplitudes have been measured depending on initial conditions and excitation frequency, for the same amplitude of the excitation. The excitation frequency is naturally divided by the circuit and the ratio is kept constant without external...

  2. Non-perturbative QCD amplitudes in quenched and eikonal approximations

    Energy Technology Data Exchange (ETDEWEB)

    Fried, H.M. [Physics Department, Brown University, Providence, RI 02912 (United States); Grandou, T., E-mail: Thierry.Grandou@inln.cnrs.fr [Université de Nice-Sophia Antipolis, Institut Non Linéaire de Nice, UMR 6618 CNRS 7335, 1361 routes des Lucioles, 06560 Valbonne (France); Sheu, Y.-M., E-mail: ymsheu@alumni.brown.edu [Université de Nice-Sophia Antipolis, Institut Non Linéaire de Nice, UMR 6618 CNRS 7335, 1361 routes des Lucioles, 06560 Valbonne (France)

    2014-05-15

    Even though approximated, strong coupling non-perturbative QCD amplitudes remain very difficult to obtain. In this article, in eikonal and quenched approximations at least, physical insights are presented that rely on the newly-discovered property of effective locality. The present article also provides a more rigorous mathematical basis for the crude approximations used in the previous derivation of the binding potential of quarks and nucleons. Furthermore, the techniques of Random Matrix calculus along with Meijer G-functions are applied to analyze the generic structure of fermionic amplitudes in QCD. - Highlights: • We discuss the physical insight of effective locality to QCD fermionic amplitudes. • We show that an unavoidable delta function goes along with the effective locality property. • The generic structure of QCD fermion amplitudes is obtained through Random Matrix calculus.

  3. Amplitude fluctuations in the Berezinskii-Kosterlitz-Thouless phase

    CERN Document Server

    Jakubczyk, Pawel

    2016-01-01

    We analyze the interplay of thermal amplitude and phase fluctuations in a $U(1)$ symmetric two-dimensional $\\phi^4$-theory. To this end, we derive coupled renormalization group equations for both types of fluctuations. Discarding the amplitude fluctuations, the expected Berezinskii-Kosterlitz-Thouless (BKT) phase characterized by a finite phase stiffness and an algebraic decay of order parameter correlations is recovered at low temperatures. However, in contrast to the widespread expectation, amplitude fluctuations are not innocuous, since their mass vanishes due to a strong renormalization by phase fluctuations. Even at low temperatures the amplitude fluctuations lead to a logarithmic renormalization group flow of the phase stiffness, which ultimately vanishes. Hence, the BKT phase is strictly speaking replaced by a symmetric phase with a finite correlation length, which is however exponentially large at low temperatures. The vortex-driven BKT transition is then rounded to a crossover, which may be practical...

  4. High Amplitude \\delta-Scutis in the Large Magellanic Cloud

    CERN Document Server

    Garg, A; Nikolaev, S; Huber, M E; Rest, A; Becker, A C; Challis, P; Clocchiatti, A; Miknaitis, G; Minniti, D; Morelli, L; Olsen, K; Prieto, J L; Suntzeff, N B; Welch, D L; Wood-Vasey, W M

    2010-01-01

    We present 2323 High-Amplitude \\delta-Scuti (HADS) candidates discovered in the Large Magellanic Cloud (LMC) by the SuperMACHO survey (Rest et al. 2005). Frequency analyses of these candidates reveal that several are multimode pulsators, including 119 whose largest amplitude of pulsation is in the fundamental (F) mode and 19 whose largest amplitude of pulsation is in the first overtone (FO) mode. Using Fourier decomposition of the HADS light curves, we find that the period-luminosity (PL) relation defined by the FO pulsators does not show a clear separation from the PL-relation defined by the F pulsators. This differs from other instability strip pulsators such as type c RR Lyrae. We also present evidence for a larger amplitude, subluminous population of HADS similar to that observed in Fornax (Poretti et al. 2008).

  5. 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.

  6. Os organismos geneticamente modificados e a rotulagem dos alimentos - uma análise a partir dos direitos dos consumidores

    Directory of Open Access Journals (Sweden)

    Marcello Vitor Rocha Cota

    2015-11-01

    Full Text Available Ao longo do presente trabalho serão analisados os organismos geneticamente modificados (OGMs frente aos riscos à saúde alimentar e ao meio ambiente, sobretudo o princípio da precaução e a rotulagem dos produtos. A partir de uma dimensão comparativa de três realidades distintas, isto é, a estadunidense, a europeia, com ênfase mercado ao português, e a brasileira – sob um prisma ambiental, a rotulagem dos produtos será confrontada com os direitos dos consumidores, embora em determinadas ocasiões, diante da inexistência de informações adequadas e claras dos produtos, que estão sendo ofertados e consumidos, os consumidores não sabem o que estão consumindo.

  7. Abordagem contingencial no gerenciamento dos recursos humanos

    OpenAIRE

    Pacheco Junior, Waldemar

    2004-01-01

    Tese (doutorado) - Universidade Federal de Santa Catarina, Centro Tecnológico. Programa de Pós-Graduação em Engenharia de Produção. O capital humano é tido como um dos fatores estratégicos às organizações, porém, um dos grandes desafios sob o ponto de vista do gerenciamento é o de melhor aproveitar o potencial dos trabalhadores, em face das dificuldades de encontrar formas de congruência entre objetivos de empresa e pessoas nela inseridas. Tal problema é normalmente uma decorrência de dese...

  8. Estrutura temporal dos tipos de xuro

    OpenAIRE

    Reboredo Nogueira, Juan Carlos

    2013-01-01

    Esta unidade didáctica forma parte do curso de Análise Económica dos Mercados Financeiros I que se imparte no primeiro cuadrimestre do Máster en Economía: Organización Industrial e Mercados Financeiros. Esta unidade ten como obxectivo analizar a estrutura temporal dos tipos de xuro, é dicir a relación existente entre os tipos de xuro a diferentes prazos. En particular, estudarase a curva cupón cero, a súa utilidade no proceso de valoración dos activos financeiros e os diferentes mé...

  9. 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.)

  10. Effect Of Vibration Amplitude Level On Seated Occupant Reaction Time

    Directory of Open Access Journals (Sweden)

    Amzar Azizan

    2015-08-01

    Full Text Available The past decade has seen the rapid development of vibration comfort in the automotive industry. However little attention has been paid to vibration drowsiness. Eighteen male volunteers were recruited for this experiment. Before commencing the experiment total transmitted acceleration measured at interfaces between the seat cushion and seatback to human body was adjusted to become 0.2 ms-2 r.m.s and 0.4 ms-2 r.m.s for each volunteer. Seated volunteers were exposed to Gaussian random vibration with frequency band 1-15 Hz at two level of amplitude low vibration amplitude and medium vibration amplitude for 20-minutes in separate days. For the purpose of drowsiness measurement volunteers were asked to complete 10-minutes PVT test before and after vibration exposure and rate their subjective drowsiness by giving score using Karolinska Sleepiness Scale KSS before vibration every 5-minutes interval and following 20-minutes of vibration exposure. Strong evidence of drowsiness was found as there was a significant increase in reaction time and number of lapse following exposure to vibration in both conditions. However the effect is more apparent in medium vibration amplitude. A steady increase of drowsiness level can also be observed in KSS in all volunteers. However no significant differences were found in KSS between low vibration amplitude and medium vibration amplitude. The results of this investigation suggest that exposure to vibration has an adverse effect on human alertness level and more pronounced at higher vibration amplitude. Taken together these findings suggest a role of vibration in promoting drowsiness especially at higher vibration amplitude.

  11. Twistor-Space Recursive Formulation of Gauge-Theory Amplitudes

    CERN Document Server

    Bena, I; Kosower, D A

    2004-01-01

    Using twistor space intuition, Cachazo, Svrcek and Witten presented novel diagrammatic rules for gauge-theory amplitudes, expressed in terms of maximally helicity-violating (MHV) vertices. We define non-MHV vertices, and show how to use them to give a recursive construction of these amplitudes. We also use them to illustrate the equivalence of various twistor-space prescriptions, and to determine the associated combinatoric factors.

  12. Bootstrapping a Five-Loop Amplitude from Steinmann Relations

    CERN Document Server

    Caron-Huot, Simon; McLeod, Andrew; von Hippel, Matt

    2016-01-01

    The analytic structure of scattering amplitudes is restricted by Steinmann relations, which enforce the vanishing of certain discontinuities of discontinuities. We show that these relations dramatically simplify the function space for the hexagon function bootstrap in planar maximally supersymmetric Yang-Mills theory. Armed with this simplification, along with the constraints of dual conformal symmetry and Regge exponentiation, we obtain the complete five-loop six-particle amplitude.

  13. Weak measurements measure probability amplitudes (and very little else)

    Science.gov (United States)

    Sokolovski, D.

    2016-04-01

    Conventional quantum mechanics describes a pre- and post-selected system in terms of virtual (Feynman) paths via which the final state can be reached. In the absence of probabilities, a weak measurement (WM) determines the probability amplitudes for the paths involved. The weak values (WV) can be identified with these amplitudes, or their linear combinations. This allows us to explain the "unusual" properties of the WV, and avoid the "paradoxes" often associated with the WM.

  14. Three-point disc amplitudes in the RNS formalism

    Science.gov (United States)

    Becker, Katrin; Becker, Melanie; Robbins, Daniel; Su, Ning

    2016-06-01

    We calculate all tree level string theory vacuum to Dp-brane disc amplitudes involving an arbitrary RR-state and two NS-NS vertex operators. This computation was earlier performed by K. Becker, Guo, and Robbins for the simplest case of a RR-state of type C (p - 3). Here we use the aid of a computer to calculate all possible three-point amplitudes involving a RR-vertex operator of type C (p + 1 + 2 k).

  15. Leading Twist Parton Distribution Amplitudes in Heavy Vector Mesons

    Directory of Open Access Journals (Sweden)

    Gao Fei

    2016-01-01

    Full Text Available We employed QCD’s Dyson-Schwinger equations (DSEs for heavy quarks and obtained the leading twist parton distribution amplitudes (PDAs in heavy vector mesons J/Ψ and ϒ. We found that all of the amplitudes are narrower than the asymptotic form, while they deviate from δ function. This indicates that the interaction between the two continent quarks are still important in the mesons consisted of charm and bottom quarks.

  16. Experimental observation of partial amplitude death in coupled chaotic oscillators

    Institute of Scientific and Technical Information of China (English)

    Liu Wei-Qing; Yang Jun-Zhong; Xiao Jing-Hua

    2006-01-01

    The dynamics of coupled Lorenz circuits is investigated experimentally. The partial amplitude death reported in Phys. Rev. E 72, 057201 (2005) is verified by physical experiments with electronic circuits. With the increase of coupling constant, the coupled circuits undergo the transition from the breakdown of both the reflection symmetry and the translational symmetry to the partial amplitude death. Its stability is also confirmed by analysing the effects of noise.

  17. Effects of Amplitude Compression on Relative Auditory Distance Perception

    Science.gov (United States)

    2013-10-01

    human sound localization (pp. 36-200). Cambridge, MA: The MIT Press. Carmichel, E. L., Harris, F. P., & Story, B. H. (2007). Effects of binaural ...auditory distance perception by reducing the level differences between sounds . The focus of the present study was to investigate the effect of amplitude...create stimuli. Two levels of amplitude compression were applied to the recordings through Adobe Audition sound editing software to simulate military

  18. Subharmonic and fundamental high amplitude excitation of an axisymmetric jet

    Science.gov (United States)

    Raman, Ganesh; Rice, Edward J.

    1989-01-01

    The effect of simultaneous excitation at the fundamental and subharmonic frequencies on the behavior of a circular jet shear layer is studied. Attention is given to the effect of the initial phase difference, the Strouhal number pair, and amplitudes of the fundamental and subharmonic tones. High-amplitude excitation devices which can provide a wide range of forcing conditions when used in conjunction with equipment that produces complex waveforms are used.

  19. Reflection Amplitudes of ADE Toda Theories and Thermodynamic Bethe Ansatz

    CERN Document Server

    Ahn, C; Kim, C; Rim, C; Yang, B; Ahn, Changrim; Kim, Chanju; Rim, Chaiho; Yang, Bedl

    2000-01-01

    We study the ultraviolet asymptotics in affine Toda theories. These models are considered as perturbed non-affine Toda theories. We calculate the reflection amplitudes, which relate different exponential fields with the same quantum numbers. Using these amplitudes we derive the quantization condition for the vacuum wave function, describing zero-mode dynamics, and calculate the UV asymptotics of the effective central charge. These asymptotics are in a good agreement with thermodynamic Bethe ansatz results.

  20. 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....

  1. 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.

  2. 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)

  3. 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.

  4. Kinematics and amplitude evolution of global coronal extreme ultraviolet waves

    Institute of Scientific and Technical Information of China (English)

    Ting Li; Jun Zhang; Shu-Hong Yang; Wei Liu

    2012-01-01

    With the observations of the Solar-Terrestrial Relations Observatory (STEREO) and the Solar Dynamics Observatory (SDO),we analyze in detail the kinematics of global coronal waves together with their intensity amplitudes (so-called "perturbation profiles").We use a semi-automatic method to investigate the perturbation profiles of coronal waves.The location and amplitude of the coronal waves are calculated over a 30° sector on the sphere,where the wave signal is strongest.The position with the strongest perturbation at each time is considered as the location of the wave front.In all four events,the wave velocities vary with time for most of their lifetime,up to 15 min,while in the event observed by the Atmospheric Imaging Assembly there is an additional early phase with a much higher velocity.The velocity varies greatly between different waves from 216 to 440 km s-1.The velocity of the two waves initially increases,subsequently decreases,and then increases again.Two other waves show a deceleration followed by an acceleration.Three categories of amplitude evolution of global coronal waves are found for the four events.The first is that the amplitude only shows a decrease.The second is that the amplitude initially increases and then decreases,and the third is that the amplitude shows an orderly increase,a decrease,an increase again and then a decrease.All the extreme ultraviolet waves show a decrease in amplitude while propagating farther away,probably because the driver of the global coronal wave (coronal mass ejection) is moving farther away from the solar surface.

  5. 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

  6. Estudo dos ruidos articulares atraves da tecnica artrosonografica dos joelhos normais de individuos jovens

    OpenAIRE

    Roberto Natalino Ricarte

    1987-01-01

    Resumo: Os ruídos articulares do joelho esquerdo normal de 43 indivíduos jovens de ambos os sexos, sendo 20 do sexo masculino e 23 do sexo feminino, foram analisados através da técnica artrosonográfica. As gravações destes ruídos obtidas em uma sala acústica, onde buscamos diminuir e foram evitar os possiveis ruidos extrinsecos as gravaçoes. Estes ruidos foram transportados posteriormente para um gravador de rolo acoplado a um eletromiógrafo, de onde obtivemos a análise dos ruídos articulares...

  7. 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.

  8. 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.

  9. 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.

  10. BENEFÍCIOS DOS PARQUES URBANOS

    Directory of Open Access Journals (Sweden)

    Raphael Tavares Pacheco Martins

    2014-07-01

    Full Text Available Esta pesquisa teve como objetivo apresentar o tema e analisar os benefícios gerados pelos parques urbanos. Para a sua realização foi definido como zona de estudo a região norte do estado do Rio de Janeiro. Os outros objetivos foram a qualificação e a definição das funções do parque e a elucidação da sua contribuição para a melhoria da qualidade de vida. Além do lazer, outras funções socioambientais relevantes são desempenhadas pelos parques urbanos destacando-se a psicológica, a reconstrução da tranquilidade, a recomposição do temperamento, atenuante de ruídos e condicionador do microclima, impondo a sua inclusão no planejamento e nas políticas públicas das cidades. A pesquisa foi estruturada por um levantamento histórico e uma revisão bibliográfica. Um dos principais efeitos dos parques urbanos é a amenização climática, com contribuições positivas para o microclima local. No passar dos anos por conta dos grandes lucros as empresas privadas levaram o conjunto urbano para um crescimento desordenado e minimizando a função social dos parques urbanos, criando problemas sociais, esquecendo-se dos valores pessoais, históricos, culturais alem da dimensão sensorial e psicológica.

  11. 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.

  12. Amplitude of Accommodation and its Relation to Refractive Errors

    Directory of Open Access Journals (Sweden)

    Abraham Lekha

    2005-01-01

    Full Text Available Aims: To evaluate the relationship between amplitude of accommodation and refractive errors in the peri-presbyopic age group. Materials and Methods: Three hundred and sixteen right eyes of 316 consecutive patients in the age group 35-50 years who attended our outpatient clinic were studied. Emmetropes, hypermetropes and myopes with best-corrected visual acuity of 6/6 J1 in both eyes were included. The amplitude of accommodation (AA was calculated by measuring the near point of accommodation (NPA. In patients with more than ± 2 diopter sphere correction for distance, the NPA was also measured using appropriate soft contact lenses. Results: There was a statistically significant difference in AA between myopes and hypermetropes ( P P P P P P >0.5. Conclusion: Our study showed higher amplitude of accommodation among myopes between 35 and 44 years compared to emmetropes and hypermetropes

  13. Amplitude envelope onsets and developmental dyslexia: A new hypothesis.

    Science.gov (United States)

    Goswami, Usha; Thomson, Jennifer; Richardson, Ulla; Stainthorp, Rhona; Hughes, Diana; Rosen, Stuart; Scott, Sophie K

    2002-08-06

    A core difficulty in developmental dyslexia is the accurate specification and neural representation of speech. We argue that a likely perceptual cause of this difficulty is a deficit in the perceptual experience of rhythmic timing. Speech rhythm is one of the earliest cues used by infants to discriminate syllables and is determined principally by the acoustic structure of amplitude modulation at relatively low rates in the signal. We show significant differences between dyslexic and normally reading children, and between young early readers and normal developers, in amplitude envelope onset detection. We further show that individual differences in sensitivity to the shape of amplitude modulation account for 25% of the variance in reading and spelling acquisition even after controlling for individual differences in age, nonverbal IQ, and vocabulary. A possible causal explanation dependent on perceptual-center detection and the onset-rime representation of syllables is discussed.

  14. 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; Mazur, M A; Morganti, M; Neri, N; Paoloni, E; Rizzo, G; Walsh, J J; Haire, M; Biesiada, J; Elmer, P; Lau, Y P; Lu, C; Olsen, J; Smith, A J S; Telnov, A V; Baracchini, E; Bellini, F; Cavoto, G; D'Orazio, A; del Re, D; Di Marco, E; Faccini, R; Ferrarotto, F; Ferroni, F; Gaspero, M; Jackson, P D; Li Gioi, L; Mazzoni, M A; Morganti, S; Piredda, G; Polci, F; Renga, F; Voena, C; Ebert, M; Hartmann, T; Schröder, H; Waldi, R; Adye, T; Castelli, G; Franek, B; Olaiya, E O; Ricciardi, S; Roethel, W; Wilson, F F; Aleksan, R; Emery, S; Escalier, M; Gaidot, A; Ganzhur, S F; Hamel de Monchenault, G; Kozanecki, W; Vasseur, G; Yèche, Ch; Zito, M; Chen, X R; Liu, H; Park, W; Purohit, M V; Wilson, J R; Allen, M T; Aston, D; Bartoldus, R; Bechtle, P; Berger, N; Claus, R; Coleman, J P; Convery, M R; Dingfelder, J C; Dorfan, J; Dubois-Felsmann, G P; Dunwoodie, W; Field, R C; Glanzman, T; Gowdy, S J; Graham, M T; Grenier, P; Hast, C; Hryn'ova, T; Innes, W R; Kaminski, J; Kelsey, M H; Kim, H; Kim, P; Kocian, M L; Leith, D W G S; Li, S; Luitz, S; Luth, V; Lynch, H L; MacFarlane, D B; Marsiske, H; Messner, R; Muller, D R; O'Grady, C P; Ofte, I; Perazzo, A; Perl, M; Pulliam, T; Ratcliff, B N; Roodman, A; Salnikov, A A; Schindler, R H; Schwiening, J; Snyder, A; Stelzer, J; Su, D; Sullivan, M K; Suzuki, K; Swain, S K; Thompson, J M; Va'vra, J; van Bakel, N; Wagner, A P; Weaver, M; Wisniewski, W J; Wittgen, M; Wright, D H; Yarritu, A K; Yi, K; Young, C C; Burchat, P R; Edwards, A J; Majewski, S A; Petersen, B A; Wilden, L; Ahmed, S; Alam, M S; Bula, R; Ernst, J A; Jain, V; Pan, B; Saeed, M A; Wappler, F R; Zain, S B; Bugg, W; Krishnamurthy, M; Spanier, S M; Eckmann, R; Ritchie, J L; Ruland, A M; Schilling, C J; Schwitters, R F; Izen, J M; Lou, X C; Ye, S; Bianchi, F; Gallo, F; Gamba, D; Pelliccioni, M; Bomben, M; Bosisio, L; Cartaro, C; Cossutti, F; Della Ricca, G; Lanceri, L; Vitale, L; Azzolini, V; Lopez-March, N; Martinez-Vidal, F; Milanes, D A; Oyanguren, A; Albert, J; Banerjee, Sw; Bhuyan, B; Hamano, K; Kowalewski, R; Nugent, I M; Roney, J M; Sobie, R J; Back, J J; Harrison, P F; Ilic, J; Latham, T E; Mohanty, G B; Pappagallo, M; Band, H R; Chen, X; Dasu, S; Flood, K T; Hollar, J J; Kutter, P E; Pan, Y; Pierini, M; Prepost, R; Wu, S L; Neal, H

    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.

  15. Amplitude Analysis of the B+- ->phi K*(892)+- Decay

    CERN Document Server

    Aubert, B; Boutigny, D; Karyotakis, Yu; Lees, J P; Poireau, V; Prudent, X; Tisserand, V; Zghiche, A; Garra Tico, J; Graugès-Pous, E; López, 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-Sánchez, P; Hawkes, C M; Watson, A T; Held, T; Koch, H; Lewandowski, B; Pelizaeus, M; Schröder, T; Steinke, M; Walker, D; Asgeirsson, D J; Çuhadar-Dönszelmann, 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 A; 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, C; 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; Bequilleux, J; Davier, M; Grosdidier, G; Höcker, A; Lepeltier, V; Le Diberder, F R; 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; Flächer, 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, Gallieno; 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 E; 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; La Vaissière, C de; Hamon, O; Leruste, P; Malcles, J; Ocariz, J; Pérez, 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; Mazur, M A; Morganti, M; Neri, N; Paoloni, E; Rizzo, G; Walsh, J J; Haire, M; Biesiada, J; Elmer, P; Lau, Y P; Lü, C; Olsen, J; Smith, A J S; Telnov, A V; Baracchini, E; Bellini, F; Cavoto, G; D'Orazio, A; Del Re, D; Di Marco, E; Faccini, R; Ferrarotto, F; Ferroni, F; Gaspero, M; Jackson, P D; Li Gioi, L; Mazzoni, M A; Morganti, S; Piredda, G; Polci, F; Renga, F; Voena, C; Ebert, M; Hartmann, T; Schröder, H; Waldi, R; Adye, T; Castelli, G; Franek, B; Olaiya, E O; Ricciardi, S; Röthel, W; Wilson, F F; Aleksan, R; Emery, S; Escalier, M; Gaidot, A; Ganzhur, S F; Hamel de Monchenault, G; Kozanecki, W; Vasseur, G; Yéche, C; Zito, M; Chen, X R; Liu, H; Park, W; Purohit, M V; Wilson, J R; Allen, M T; Aston, D; Bartoldus, R; Bechtle, P; Berger, N; Claus, R; Coleman, J P; Convery, M R; Dingfelder, J C; Dorfan, J; Dubois-Felsmann, G P; Dunwoodie, W; Field, R C; Glanzman, T; Gowdy, S J; Graham, M T; Grenier, P; Hast, C; Hrynóva, T; Innes, W R; Kaminski, J; Kelsey, M H; Kim, H; Kim, P; Kocian, M L; Leith, D W G S; Li, S; Luitz, S; Lüth, V; Lynch, H L; MacFarlane, D B; Marsiske, H; Messner, R; Müller, D R; O'Grady, C P; Ofte, I; Perazzo, A; Perl, M; Pulliam, T; Ratcliff, B N; Roodman, A; Salnikov, A A; Schindler, R H; Schwiening, J; Snyder, A; Stelzer, J; Su, D; Sullivan, M K; Suzuki, K; Swain, S K; Thompson, J M; Vavra, J; Van Bakel, N; Wagner, A P; Weaver, M; Wisniewski, W J; Wittgen, M; Wright, D H; Yarritu, A K; Yi, K; Young, C C; Burchat, P R; Edwards, A J; Majewski, S A; Petersen, B A; Wilden, L; Ahmed, S; Alam, M S; Bula, R; Ernst, J A; Jain, V; Pan, B; Saeed, M A; Wappler, F R; Zain, S B; Bugg, W; Krishnamurthy, M; Spanier, S M; Eckmann, R; Ritchie, J L; Ruland, A M; Schilling, C J; Schwitters, R F; Izen, J M; Lou, X C; Ye, S; Bianchi, F; Gallo, F; Gamba, D; Pelliccioni, M; Bomben, M; Bosisio, L; Cartaro, C; Cossutti, F; Della Ricca, G; Lanceri, L; Vitale, L; Azzolini, V; Lopez-March, N; Martínez-Vidal, F; Milanes, D A; Oyanguren, A; Albert, J; Banerjee, Sw; Bhuyan, B; Hamano, K; Kowalewski, R V; Nugent, I M; Roney, J M; Sobie, R J; Back, J J; Harrison, P F; Ilic, J; Latham, T E; Mohanty, G B; Pappagallo, M; Band, H R; Chen, X; Dasu, S; Flood, K T; Hollar, J J; Kutter, P E; Pan, Y; Pierini, M; Prepost, R; Wu, S L; Neal, H

    2007-01-01

    We perform an amplitude analysis of B+- -> phi(1020) K*(892)+- decay with a sample of about 384 million BBbar pairs recorded with the BABAR detector. Overall, twelve parameters are measured, including the fractions of longitudinal f_L and parity-odd transverse f_perp 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 f_L=0.49+-0.05+-0.03, f_perp=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.

  16. Measuring the local pressure amplitude in microchannel acoustophoresis

    DEFF Research Database (Denmark)

    Barnkob, Rune; Augustsson, Per; Laurell, Thomas

    2010-01-01

    A new method is reported on how to measure the local pressure amplitude and the Q factor of ultrasound resonances in microfluidic chips designed for acoustophoresis of particle suspensions. The method relies on tracking individual polystyrene tracer microbeads in straight water-filled silicon...... of the microbeads. From the curve fits we obtain the acoustic energy density, and hence the pressure amplitude as well as the acoustophoretic force. By plotting the obtained energy densities as a function of applied frequency, we obtain Lorentzian line shapes, from which the resonance frequency and the Q factor...... for each resonance peak are derived. Typical measurements yield acoustic energy densities of the order of 10 J/m3, pressure amplitudes of 0.2 MPa, and Q factors around 500. The observed half wavelength of the transverse acoustic pressure wave is equal within 2% to the measured width w = 377 m...

  17. Kernel Phase and Kernel Amplitude in Fizeau Imaging

    CERN Document Server

    Pope, Benjamin J S

    2016-01-01

    Kernel phase interferometry is an approach to high angular resolution imaging which enhances the performance of speckle imaging with adaptive optics. Kernel phases are self-calibrating observables that generalize the idea of closure phases from non-redundant arrays to telescopes with arbitrarily shaped pupils, by considering a matrix-based approximation to the diffraction problem. In this paper I discuss the recent history of kernel phase, in particular in the matrix-based study of sparse arrays, and propose an analogous generalization of the closure amplitude to kernel amplitudes. This new approach can self-calibrate throughput and scintillation errors in optical imaging, which extends the power of kernel phase-like methods to symmetric targets where amplitude and not phase calibration can be a significant limitation, and will enable further developments in high angular resolution astronomy.

  18. Finite amplitude effects on drop levitation for material properties measurement

    Science.gov (United States)

    Ansari Hosseinzadeh, Vahideh; Holt, R. Glynn

    2017-05-01

    The method of exciting shape oscillation of drops to extract material properties has a long history, which is most often coupled with the technique of acoustic levitation to achieve non-contact manipulation of the drop sample. We revisit this method with application to the inference of bulk shear viscosity and surface tension. The literature is replete with references to a "10% oscillation amplitude" as a sufficient condition for the application of Lamb's analytical expressions for the shape oscillations of viscous liquids. Our results show that even a 10% oscillation amplitude leads to dynamic effects which render Lamb's results inapplicable. By comparison with samples of known viscosity and surface tension, we illustrate the complicating finite-amplitude effects (mode-splitting and excess dissipation associated with vorticity) that can occur and then show that sufficiently small oscillations allow us to recover the correct material properties using Lamb's formula.

  19. Convergence of transition amplitudes obtained with the Schwinger variational principle

    CERN Document Server

    Rodríguez, V D

    2016-01-01

    An exactly solvable time-dependent quantum mechanical problem is employed to study the convergence properties of transition amplitudes calculated by using the Schwinger variational principle. A detailed comparison between the amplitudes approximated by the perturbative series and by their associated Schwinger variational principles is performed. The much better performance obtained by the variational principle is documented through different case studies. For a given order of the Schwinger principle, it is observed that the transition amplitudes do not converge to the exact one for large perturbations. The latter is true even though large combinations of unperturbed states with constant coefficients are taken as trial wave functions. As a matter of fact, it is shown that the improvement of the method comes from using better trial wave functions and increasing the order of the Schwinger principle employed.

  20. Mammalian cycles: internally defined periods and interaction-driven amplitudes.

    Science.gov (United States)

    Ginzburg, L R; Krebs, C J

    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.

  1. Disc amplitudes, picture changing and space-time actions

    CERN Document Server

    Becker, Katrin; Robbins, Daniel

    2011-01-01

    We study in detail the procedure for obtaining couplings of D-branes to closed string fields by evaluating string theory disc amplitudes. We perform a careful construction of the relevant vertex operators and discuss the effects of inserting the boundary state which encodes the presence of the D-brane. We confront the issue of non-decoupling of BRST-exact states and prove that the problem is evaded for the computations we need, thus demonstrating that our amplitudes are automatically gauge-invariant and independent of the distribution of picture charge. Finally, we compute explicitly the two-point amplitudes of two NS-NS fields or one NS-NS and one R-R field on the disc, and we carefully compare all the lowest order terms with predictions from supergravity.

  2. Optimization of phase contrast in bimodal amplitude modulation AFM

    Directory of Open Access Journals (Sweden)

    Mehrnoosh Damircheli

    2015-04-01

    Full Text Available Bimodal force microscopy has expanded the capabilities of atomic force microscopy (AFM by providing high spatial resolution images, compositional contrast and quantitative mapping of material properties without compromising the data acquisition speed. In the first bimodal AFM configuration, an amplitude feedback loop keeps constant the amplitude of the first mode while the observables of the second mode have not feedback restrictions (bimodal AM. Here we study the conditions to enhance the compositional contrast in bimodal AM while imaging heterogeneous materials. The contrast has a maximum by decreasing the amplitude of the second mode. We demonstrate that the roles of the excited modes are asymmetric. The operational range of bimodal AM is maximized when the second mode is free to follow changes in the force. We also study the contrast in trimodal AFM by analyzing the kinetic energy ratios. The phase contrast improves by decreasing the energy of second mode relative to those of the first and third modes.

  3. The Appell function F1 and Regge string scattering amplitudes

    Directory of Open Access Journals (Sweden)

    Jen-Chi Lee

    2014-12-01

    Full Text Available We show that each 26D open bosonic Regge string scattering amplitude (RSSA can be expressed in terms of one single Appell function F1 in the Regge limit. This result enables us to derive infinite number of recurrence relations among RSSA at arbitrary mass levels, which are conjectured to be related to the known SL(5,C dynamical symmetry of F1. In addition, we show that these recurrence relations in the Regge limit can be systematically solved so that all RSSA can be expressed in terms of one amplitude. All these results are dual to high energy symmetries of fixed angle string scattering amplitudes discovered previously [4–8].

  4. Top Quark Amplitudes with an Anomolous Magnetic Moment

    Energy Technology Data Exchange (ETDEWEB)

    Larkoski, Andrew J.; Peskin, Michael E.; /SLAC

    2011-06-23

    The anomalous magnetic moment of the top quark may be measured during the first run of the LHC at 7 TeV. For these measurements, it will be useful to have available tree amplitudes with t{bar t} and arbitrarily many photons and gluons, including both QED and color anomalous magnetic moments. In this paper, we present a method for computing these amplitudes using the Britto-Cachazo-Feng-Witten recursion formula. Because we deal with an effective theory with higher-dimension couplings, there are roadblocks to a direct computation with the Britto-Cachazo-Feng-Witten method. We evade these by using an auxiliary scalar theory to compute a subset of the amplitudes.

  5. Top quark amplitudes with an anomalous magnetic moment

    Science.gov (United States)

    Larkoski, Andrew J.; Peskin, Michael E.

    2011-02-01

    The anomalous magnetic moment of the top quark may be measured during the first run of the LHC at 7 TeV. For these measurements, it will be useful to have available tree amplitudes with tt¯ and arbitrarily many photons and gluons, including both QED and color anomalous magnetic moments. In this paper, we present a method for computing these amplitudes using the Britto-Cachazo-Feng-Witten recursion formula. Because we deal with an effective theory with higher-dimension couplings, there are roadblocks to a direct computation with the Britto-Cachazo-Feng-Witten method. We evade these by using an auxiliary scalar theory to compute a subset of the amplitudes.

  6. General mechanism for amplitude death in coupled systems.

    Science.gov (United States)

    Resmi, V; Ambika, G; Amritkar, R E

    2011-10-01

    We introduce a general mechanism for amplitude death in coupled synchronizable dynamical systems. It is known that when two systems are coupled directly, they can synchronize under suitable conditions. When an indirect feedback coupling through an environment or an external system is introduced in them, it is found to induce a tendency for antisynchronization. We show that, for sufficient strengths, these two competing effects can lead to amplitude death. We provide a general stability analysis that gives the threshold values for onset of amplitude death. We study in detail the nature of the transition to death in several specific cases and find that the transitions can be of two types--continuous and discontinuous. By choosing a variety of dynamics, for example, periodic, chaotic, hyperchaotic, and time-delay systems, we illustrate that this mechanism is quite general and works for different types of direct coupling, such as diffusive, replacement, and synaptic couplings, and for different damped dynamics of the environment.

  7. String amplitudes: from field theories to number theory

    CERN Document Server

    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...

  8. On the four-dimensional formulation of dimensionally regulated amplitudes

    Energy Technology Data Exchange (ETDEWEB)

    Fazio, A.R. [Universidad Nacional de Colombia, Departamento de Fisica, Bogota (Colombia); Mastrolia, P. [Universita di Padova, Dipartimento di Fisica e Astronomia, Padua (Italy); Max-Planck-Institut fuer Physik, Munich (Germany); INFN, Padova (Italy); Mirabella, E. [Max-Planck-Institut fuer Physik, Munich (Germany); Torres Bobadilla, W.J. [Universidad Nacional de Colombia, Departamento de Fisica, Bogota (Colombia); Universita di Padova, Dipartimento di Fisica e Astronomia, Padua (Italy); INFN, Padova (Italy)

    2014-12-01

    Elaborating on the four-dimensional helicity scheme, we propose a pure four-dimensional formulation (FDF) of the d-dimensional regularization of one-loop scattering amplitudes. In our formulation particles propagating inside the loop are represented by massive internal states regulating the divergences. The latter obey Feynman rules containing multiplicative selection rules which automatically account for the effects of the extra-dimensional regulating terms of the amplitude. We present explicit representations of the polarization and helicity states of the four-dimensional particles propagating in the loop. They allow for a complete, four-dimensional, unitarity-based construction of d-dimensional amplitudes. Generalized unitarity within the FDF does not require any higher-dimensional extension of the Clifford and the spinor algebra. Finally we show how the FDF allows for the recursive construction of d-dimensional one-loop integrands, generalizing the four-dimensional open-loop approach. (orig.)

  9. Optimization of phase contrast in bimodal amplitude modulation AFM.

    Science.gov (United States)

    Damircheli, Mehrnoosh; Payam, Amir F; Garcia, Ricardo

    2015-01-01

    Bimodal force microscopy has expanded the capabilities of atomic force microscopy (AFM) by providing high spatial resolution images, compositional contrast and quantitative mapping of material properties without compromising the data acquisition speed. In the first bimodal AFM configuration, an amplitude feedback loop keeps constant the amplitude of the first mode while the observables of the second mode have not feedback restrictions (bimodal AM). Here we study the conditions to enhance the compositional contrast in bimodal AM while imaging heterogeneous materials. The contrast has a maximum by decreasing the amplitude of the second mode. We demonstrate that the roles of the excited modes are asymmetric. The operational range of bimodal AM is maximized when the second mode is free to follow changes in the force. We also study the contrast in trimodal AFM by analyzing the kinetic energy ratios. The phase contrast improves by decreasing the energy of second mode relative to those of the first and third modes.

  10. Thermodynamic constraints on the amplitude of quantum oscillations

    Science.gov (United States)

    Shekhter, Arkady; Modic, K. A.; McDonald, R. D.; Ramshaw, B. J.

    2017-03-01

    Magneto-quantum oscillation experiments in high-temperature superconductors show a strong thermally induced suppression of the oscillation amplitude approaching the critical dopings [B. J. Ramshaw et al., Science 348, 317 (2014), 10.1126/science.aaa4990; H. Shishido et al., Phys. Rev. Lett. 104, 057008 (2010), 10.1103/PhysRevLett.104.057008; P. Walmsley et al., Phys. Rev. Lett. 110, 257002 (2013), 10.1103/PhysRevLett.110.257002]—in support of a quantum-critical origin of their phase diagrams. We suggest that, in addition to a thermodynamic mass enhancement, these experiments may directly indicate the increasing role of quantum fluctuations that suppress the quantum oscillation amplitude through inelastic scattering. We show that the traditional theoretical approaches beyond Lifshitz-Kosevich to calculate the oscillation amplitude in correlated metals result in a contradiction with the third law of thermodynamics and suggest a way to rectify this problem.

  11. Predicting Soil Moisture in the Field from Amplitude Temperature

    Science.gov (United States)

    Al-Kayssi, A. W.

    2009-04-01

    Measurements of amplitude temperature and soil moisture content of sandy loam and silty clay loam soils were conducted in Al-Mada'in Research Station south of Baghdad during the period from the 1st of February to the 30th of April, 2004. Exponential regression relations were developed between amplitude temperature and volumetric moisture content for soil depths of 0.5, 3.0, 7.5 and 15cm below surface, which was highly significant (R2>0.96). A good linear regression between measured and predicted soil moisture contents was deduced for each depth (r>0.97). Soil moisture content was successfully predicted from the regression line when amplitude temperature was known.

  12. FPGA-based amplitude and phase detection in DLLRF

    Institute of Scientific and Technical Information of China (English)

    LIU Rong; WANG Zheng; PAN Wei-Min; WANG Guang-Wei; LIN Hai-Ying; SHA Peng; ZENG Ri-Hua

    2009-01-01

    The new generation particle accelerator requires a highly stable radio frequency (RF) system. The stability of the RF system is realized by the Low Level RF (LLRF) subsystem which controls the amplitude and phase of the RF signal. The detection of the RF signal's amplitude and phase is fundamental to LLRF controls. High-speed ADC (Analog to Digital Converter), DAC (Digital to Analog Converter) and FPGA (Field Programmable Gate Array) play very important roles in digital LLRF control systems. This paper describes the implementation of real-time amplitude and phase detection based of the FPGA with an analysis of the main factors that affect the detection accuracy such as jitter, algorithm's defects and non-linearity of devices, which is helpful for future work on high precision detection and control.

  13. 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.

  14. Air-segmented amplitude-modulated multiplexed flow analysis.

    Science.gov (United States)

    Inui, Koji; Uemura, Takeshi; Ogusu, Takeshi; Takeuchi, Masaki; Tanaka, Hideji

    2011-01-01

    Air-segmentation is applied to amplitude-modulated multiplexed flow analysis, which we proposed recently. Sample solutions, the flow rates of which are varied periodically, are merged with reagent and/or diluent solution. The merged stream is segmented by air-bubbles and, downstream, its absorbance is measured after deaeration. The analytes in the samples are quantified from the amplitudes of the respective wave components in the absorbance. The proposed method is applied to the determinations of a food dye, phosphate ions and nitrite ions. The air-segmentation is effective for limiting amplitude damping through the axial dispersion, resulting in an improvement in sensitivity. This effect is more pronounced at shorter control periods and longer flow path lengths.

  15. RECOLA: REcursive Computation of One-Loop Amplitudes

    CERN Document Server

    Actis, Stefano; Hofer, Lars; Lang, Jean-Nicolas; Scharf, Andreas; Uccirati, Sandro

    2016-01-01

    We present the Fortran95 program Recola for the perturbative computation of next-to-leading-order transition amplitudes in the Standard Model of particle physics. The code provides numerical results in the 't Hooft-Feynman gauge. It uses the complex-mass scheme and allows for a consistent isolation of resonant contributions. Dimensional regularization is employed for ultraviolet and infrared singularities, with the alternative possibility of treating collinear and soft singularities in mass regularization. Recola supports various renormalization schemes for the electromagnetic and a dynamical Nf-flavour scheme for the strong coupling constant. The calculation of next-to-leading-order squared amplitudes, summed over spin and colour, is supported as well as the computation of colour- and spin-correlated leading-order squared amplitudes needed in the dipole subtraction formalism.

  16. 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

  17. Amplitudes and Correlators to Ten Loops Using Simple, Graphical Bootstraps

    CERN Document Server

    Bourjaily, Jacob L; Tran, Vuong-Viet

    2016-01-01

    We introduce two new graphical-level relations among possible contributions to the four-point correlation function and scattering amplitude in planar, maximally supersymmetric Yang-Mills theory. When combined with the rung rule, these prove powerful enough to fully determine both functions through ten loops. This then also yields the full five-point amplitude to eight loops and the parity-even part to nine loops. We derive these rules, illustrate their applications, compare their relative strengths for fixing coefficients, and survey some of the features of the previously unknown nine and ten loop expressions. Explicit formulae for amplitudes and correlators through ten loops are available at: http://goo.gl/JH0yEc.

  18. Amplitudes and correlators to ten loops using simple, graphical bootstraps

    Science.gov (United States)

    Bourjaily, Jacob L.; Heslop, Paul; Tran, Vuong-Viet

    2016-11-01

    We introduce two new graphical-level relations among possible contributions to the four-point correlation function and scattering amplitude in planar, maximally supersymmetric Yang-Mills theory. When combined with the rung rule, these prove powerful enough to fully determine both functions through ten loops. This then also yields the full five-point amplitude to eight loops and the parity-even part to nine loops. We derive these rules, illustrate their applications, compare their relative strengths for fixing coefficients, and survey some of the features of the previously unknown nine and ten loop expressions. Explicit formulae for amplitudes and correlators through ten loops are available at: http://goo.gl/JH0yEc.

  19. Amplitude-Modulated Bursting: A Novel Class of Bursting Rhythms

    Science.gov (United States)

    Vo, Theodore; Kramer, Mark A.; Kaper, Tasso J.

    2016-12-01

    We report on the discovery of a novel class of bursting rhythms, called amplitude-modulated bursting (AMB), in a model for intracellular calcium dynamics. We find that these rhythms are robust and exist on open parameter sets. We develop a new mathematical framework with broad applicability to detect, classify, and rigorously analyze AMB. Here we illustrate this framework in the context of AMB in a model of intracellular calcium dynamics. In the process, we discover a novel family of singularities, called toral folded singularities, which are the organizing centers for the amplitude modulation and exist generically in slow-fast systems with two or more slow variables.

  20. Baryon-to-meson transition distribution amplitudes: formalism and models

    CERN Document Server

    Pire, B; Szymanowski, L

    2016-01-01

    In specific kinematics, hard exclusive amplitudes may be factorized into a short distance dominated part computable in a perturbative way on the one hand, and universal, confinement related hadronic matrix elements on the other hand. The extension of this description to processes such as backward meson electroproduction and forward meson production in antiproton-nucleon scattering leads to define new hadronic matrix elements of three quark operators on the light cone, the nucleon-to-meson transition distribution amplitudes, which shed a new light on the nucleon structure.

  1. Radial convection of finite ion temperature, high amplitude plasma blobs

    DEFF Research Database (Denmark)

    Wiesenberger, M.; Madsen, Jens; Kendl, Alexander

    2014-01-01

    We present results from simulations of seeded blob convection in the scrape-off-layer of magnetically confined fusion plasmas. We consistently incorporate high fluctuation amplitude levels and finite Larmor radius (FLR) effects using a fully nonlinear global gyrofluid model. This is in line...... with conditions found in tokamak scrape-off-layers (SOL) regions. Varying the ion temperature, the initial blob width, and the initial amplitude, we found an FLR dominated regime where the blob behavior is significantly different from what is predicted by cold-ion models. The transition to this regime is very...

  2. Enhanced electroweak penguin amplitude in B-->VV decays

    CERN Document Server

    Beneke, Martin; Yang, D

    2006-01-01

    We discuss a novel electromagnetic penguin contribution to the transverse helicity amplitudes in B decays to two vector mesons, which is enhanced by two powers of mB/Lambda relative to the standard penguin amplitudes. This leads to unique polarization signatures in penguin-dominated decay modes such as B-->rho K* similar to polarization effects in the radiative decay B-->K*gamma, and offers new opportunities to probe the magnitude and chirality of flavour-changing neutral current couplings to photons.

  3. Four-Derivative Brane Couplings from String Amplitudes

    CERN Document Server

    Becker, Katrin; Robbins, Daniel

    2011-01-01

    We evaluate the string theory disc amplitude of one Ramond-Ramond field C^(p-3) and two Neveu-Schwarz B-fields in the presence of a single Dp-brane in type II string theory. From this amplitude we extract the four-derivative (or equivalently order (alpha')^2) part of the Dp-brane action involving these fields. We show that the new couplings are invariant under R-R and NS-NS gauge transformations and compatible with linear T-duality.

  4. Three-Point Disc Amplitudes in the RNS Formalism

    CERN Document Server

    Becker, Katrin; Robbins, Daniel; Su, Ning

    2016-01-01

    We calculate all tree level string theory vacuum to Dp-brane disc amplitudes involving an arbitrary RR-state and two NS-NS vertex operators. This computation was earlier performed by K. Becker, Guo, and Robbins for the simplest case of a RR-state of type C_{p-3}. Here we use the aid of a computer to calculate all possible three-point amplitudes involving a RR-vertex operator of type C_{p+1+2k}.

  5. A class of amplitude modulating and invisible inhomogeneous media

    CERN Document Server

    Vial, Benjamin; Horsley, Simon A R; Philbin, Thomas G; Hao, Yang

    2016-01-01

    We propose a general method to arbitrarily manipulate the amplitude of an electromagnetic wave propagating in a two-dimensional medium, without introducing any scattering. This leads to a whole class of isotropic spatially varying permittivity and permeability profiles that are invisible while shaping the field magnitude. In addition, we propose a metamaterial structure working in the infrared that demonstrates deep sub-wavelength control of the electric field amplitude and strong reduction of the scattering. This work offers an alternative strategy to achieve invisibility with isotropic materials and paves the way for tailoring the propagation of light at the nanoscale.

  6. Explaining the discrepancy between forced fold amplitude and sill thickness.

    Science.gov (United States)

    Hoggett, Murray; Jones, Stephen M.; Reston, Timothy; Magee, Craig; Jackson, Christopher AL

    2017-04-01

    Understanding the behaviour of Earth's surface in response to movement and emplacement of magma underground is important because it assists calculation of subsurface magma volumes, and could feed into eruption forecasting. Studies of seismic reflection data have observed that the amplitude of a forced fold above an igneous sill is usually smaller than the thickness of the sill itself. This observation implies that fold amplitude alone provides only a lower bound for magma volume, and an understanding of the mechanism(s) behind the fold amplitude/sill thickness discrepancy is also required to obtain a true estimate of magma volume. Mechanisms suggested to explain the discrepancy include problems with seismic imaging and varying strain behaviour of the host rock. Here we examine the extent to which host-rock compaction can explain the fold amplitude/sill thickness discrepancy. This mechanism operates in cases where a sill is injected into the upper few kilometres of sedimentary rock that contain significant porosity. Accumulation of sediment after sill intrusion reduces the amplitude of the forced fold by compaction, but the sill itself undergoes little compaction since its starting porosity is almost zero. We compiled a database of good-quality 2D and 3D seismic observations where sill thickness has been measured independently of forced fold geometry. We then backstripped the post-intrusion sedimentary section to reconstruct the amplitude of the forced fold at the time of intrusion. We used the standard compaction model in which porosity decays exponentially below the sediment surface. In all examples we studied, post-sill-emplacement compaction can explain all of the fold amplitude/sill thickness discrepancy, subject to uncertainty in compaction model parameters. This result leads directly to an improved method of predicting magma volume from fold amplitude, including how uncertainty in compaction parameters maps onto uncertainty in magma volume. Our work implies

  7. Closed-Form Decomposition of One-Loop Massive Amplitudes

    CERN Document Server

    Britto, Ruth; Mastrolia, Pierpaolo

    2008-01-01

    We present formulas for the coefficients of 2-, 3-, 4- and 5-point master integrals for one-loop massive amplitudes. The coefficients are derived from unitarity cuts in D dimensions. The input parameters can be read off from any unitarity-cut integrand, as assembled from tree-level expressions, after simple algebraic manipulations. The formulas presented here are suitable for analytical as well as numerical evaluation. Their validity is confirmed in two known cases of helicity amplitudes contributing to gg -> gg and gg -> gH, where the masses of the Higgs and the fermion circulating in the loop are kept as free parameters.

  8. All tree amplitudes of supersymmetric Einstein-Yang-Mills theory

    CERN Document Server

    Adamo, Tim; Roehrig, Kai A; Skinner, David

    2015-01-01

    We present a new formula for all tree amplitudes in four dimensional supergravity coupled to super Yang-Mills. 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. We sketch how these amplitudes may be obtained from a four-dimensional (ambi)twistor string.

  9. Non-perturbative QCD amplitudes in quenched and eikonal approximations

    Science.gov (United States)

    Fried, H. M.; Grandou, T.; Sheu, Y.-M.

    2014-05-01

    Even though approximated, strong coupling non-perturbative QCD amplitudes remain very difficult to obtain. In this article, in eikonal and quenched approximations at least, physical insights are presented that rely on the newly-discovered property of effective locality. The present article also provides a more rigorous mathematical basis for the crude approximations used in the previous derivation of the binding potential of quarks and nucleons. Furthermore, the techniques of Random Matrix calculus along with Meijer G-functions are applied to analyze the generic structure of fermionic amplitudes in QCD.

  10. Combining Fixed-Order Helicity Amplitudes With Resummation Using SCET

    CERN Document Server

    Stewart, Iain W; Waalewijn, Wouter J

    2012-01-01

    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.

  11. Recursive generation of one-loop SM amplitudes

    Energy Technology Data Exchange (ETDEWEB)

    Actis, Stefano [Paul Scherrer Institut, Wuerenlingen (Switzerland); Paul Scherrer Institut, Villigen (Switzerland); Denner, Ansgar; Hofer, Lars; Scharf, Andreas [Universitaet Wuerzburg (Germany); Uccirati, Sandro [Universita di Torino, Turin (Italy)

    2013-07-01

    We introduce the computer code Recola for the recursive generation of tree-level and one-loop amplitudes in the full Standard Model, including electroweak corrections. The presented algorithm for the calculation of one-loop amplitudes uses Dyson-Schwinger recursion relations to determine the coefficients of the tensor integrals. As a first application of Recola we discuss Z+2jets production at the LHC and present results for the next-to-leading-order electroweak corrections to the dominant partonic channels.

  12. Baryon-to-Meson Transition Distribution Amplitudes: Formalism and Models

    Science.gov (United States)

    Pire, B.; Semenov-Tian-Shansky, K.; Szymanowski, L.

    2017-03-01

    In specific kinematics, hard exclusive amplitudes may be factorized into a short distance dominated part computable in a perturbative way on the one hand, and universal, confinement related hadronic matrix elements on the other hand. The extension of this description to processes such as backward meson electroproduction and forward meson production in antiproton-nucleon scattering leads to define new hadronic matrix elements of three quark operators on the light cone, the nucleon-to-meson transition distribution amplitudes, which shed a new light on the nucleon structure.

  13. 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.

  14. Measurements of Tune Shifts with Amplitude at LEP

    CERN Document Server

    Müller, A S

    1999-01-01

    The beam orbit system of the LEP electron-positron collider is able to store the beam position over 1000 turns following a deflection by a horizontal kicker. A precise analysis of such 1000-turn data for many beam position monitors was used to study the dependence of the tune on the horizontal amplitude. The horizontal tune shift with amplitude was determined from the decay of the beam oscillation for various LEP optics. This parameter turned out to be an important issue for the LEP high energy optics.

  15. Damping and Frequency Shift of Large Amplitude Electron Plasma Waves

    DEFF Research Database (Denmark)

    Thomsen, Kenneth; Juul Rasmussen, Jens

    1983-01-01

    The initial evolution of large-amplitude one-dimensional electron waves is investigated by applying a numerical simulation. The initial wave damping is found to be strongly enhanced relative to the linear damping and it increases with increasing amplitude. The temporal evolution of the nonlinear...... damping rate γ(t) shows that it increases with time within the initial phase of propagation, t≲π/ωB (ωB is the bounce frequency), whereafter it decreases and changes sign implying a regrowth of the wave. The shift in the wave frequency δω is observed to be positive for t≲π/ωB; then δω changes sign...

  16. Finite Amplitude Electron Plasma Waves in a Cylindrical Waveguide

    DEFF Research Database (Denmark)

    Juul Rasmussen, Jens

    1978-01-01

    The nonlinear behaviour of the electron plasma wave propagating in a cylindrical plasma waveguide immersed in an infinite axial magnetic field is investigated using the Krylov-Bogoliubov-Mitropolsky perturbation method, by means of which is deduced the nonlinear Schrodinger equation governing...... the long-time slow modulation of the wave amplitude. From this equation the amplitude-dependent frequency and wavenumber shifts are calculated, and it is found that the electron waves with short wavelengths are modulationally unstable with respect to long-wavelength, low-frequency perturbations...

  17. Relativistic motion of charged particles in the interaction of short pulses of intense laser light with plasma; Movimiento relativista de particulas cargadas en la interaccion de pulsos cortos de luz laser intensa con plasma

    Energy Technology Data Exchange (ETDEWEB)

    Gomez R, F

    2004-07-01

    interval d{tau} of the electron that per se is an invariant, it is proportional to a certain interval d{eta}. In the chapter 3 it will see that the movement analysis of the charged particles in the electromagnetic field presents serious mathematical difficulties, where the integration of the movement equations results extraordinarily complex and it can only be integrated in most of the cases by numerical means. We will present the procedure used for the deduction of the equations of motion of a charged particle in the interaction of a laser light pulse and a homogeneous magnetic field in arbitrary direction, with the addition of an harmonic term of force. In this chapter it is not sought to make a meticulous discussion of the involved physics and only we will present the algebraic procedure. In the chapter 4 we will present the integration method of the Lorentz force, and we will obtain the exact solution for the case of a pulse of a plane wave elliptically polarized of arbitrary amplitude spreading along an external magnetic field. The solution method will allow to decrease the solutions to the case in which we have an infinite waves train reported by Ondarza (10) and so the corresponding solutions will be obtained reported in the literature by other authors. The main contribution in this part will be the one of obtaining an exact solution for the problem of the interaction of an electromagnetic pulse, modulated by a form of gaussian type, and a charged particle. The above-mentioned approaches in acceptable measure to real situations in well-known experiments. It will be found that when the form of the pulse is introduced to modulate the electromagnetic field, an amplification of the resonance zone in the solutions appears. Such resonance depends of the external magnetic field that fixes by turns the cyclotron frequency, and of the number of optical cycles that compose the encircling one that modulates the pulse form. In the chapter 5 it will see the case of small

  18. AS DIMENSÕES DOS MODELOS MENTAIS DOS EMPREENDEDORES E SEUS IMPACTOS SOBRE O DESEMPENHO ORGANIZACIONAL

    Directory of Open Access Journals (Sweden)

    Deonir de Toni

    Full Text Available Este trabalho objetiva identificar as dimensões e variáveis básicas dos modelos mentais dos empreendedores, bem como os seus impactos sobre o desempenho de suas empresas. Para isso, foi realizada uma pesquisa qualitativa com seis empreendedores, e uma pesquisa quantitativa com 113 empresas do setor metalomecânico na Serra Gaúcha. Dentre as contribuições deste trabalho, destaca-se, primeiramente a proposição de um modelo teórico no qual se identificam sete dimensões dos modelos mentais dos empreendedores relacionadas ao desempenho organizacional. Uma segunda contribuição é a proposição de uma escala para a mensuração dos modelos mentais dos dirigentes das empresas. Os resultados da pesquisa confirmam que a escala proposta se ajustou bem às dimensões identificadas na revisão da literatura e que dentre as sete dimensões apresentadas, as que estão relacionadas ao conhecimento, ao relacionamento, à missão e à estratégia, à criatividade e à vocação apresentaram um impacto significativo sobre o desempenho das organizações analisadas. Verificou-se que 27,5% do poder explicativo do desempenho organizacional pode estar associado às dimensões formadoras dos modelos mentais dos empreendedores.

  19. Amplitude analysis of D0->K+K-pi+pi-

    CERN Document Server

    Artuso, M; Mountain, R; Skwarnicki, T; Stone, S; Zhang, L M; Gershon, T; Bonvicini, G; Cinabro, D; Lincoln, A; Smith, M J; Zhou, P; Zhu, J; Naik, P; Rademacker, J; Asner, D M; Edwards, K W; Randrianarivony, K; Tatishvili, G; Briere, R A; Vogel, H; Onyisi, P U E; Rosner, J L; Alexander, J P; Cassel, D G; Das, S; Ehrlich, R; Gibbons, L; Gray, S W; Hartill, D L; Heltsley, B K; Kreinick, D L; Kuznetsov, V E; Patterson, J R; Peterson, D; Riley, D; Ryd, A; Sadoff, A J; Shi, X; Sun, W M; Yelton, J; Rubin, P; Lowrey, N; Mehrabyan, S; Selen, M; Wiss, J; Libby, J; Kornicer, M; Mitchell, R E; Besson, D; Pedlar, T K; Cronin-Hennessy, D; Hietala, J; Dobbs, S; Metreveli, Z; Seth, K K; Tomaradze, A; Xiao, T; Martin, L; Powell, A; Spradlin, P; Wilkinson, G; Ge, J Y; Miller, D H; Shipsey, I P J; Xin, B; Adams, G S; Napolitano, J; Ecklund, K M; Insler, J; Muramatsu, H; Park, C S; Pearson, L J; Thorndike, E H; Ricciardi, S; Thomas, C

    2012-01-01

    The first flavor-tagged amplitude analysis of the decay D0 to the self-conjugate final state K+K-pi+pi- is presented. Data from the CLEO II.V, CLEO III, and CLEO-c detectors are used, from which around 3000 signal decays are selected. The three most significant amplitudes, which contribute to the model that best fits the data, are phirho0, K1(1270)+-K-+, and non-resonant K+K-pi+pi-. Separate amplitude analyses of D0 and D0-bar candidates indicate no CP violation among the amplitudes at the level of 5% to 30% depending on the mode. In addition, the sensitivity to the CP-violating parameter gamma/phi3 of a sample of 2000 B+ -> D0-tilde(K+K-pi+pi-)K+ decays, where D0-tilde is a D0 or D0-bar, collected at LHCb or a future flavor facility, is estimated to be (11.3 +/- 0.3) degrees using the favored model.

  20. One-loop corrections from higher dimensional tree amplitudes

    Science.gov (United States)

    Cachazo, Freddy; He, Song; Yuan, Ellis Ye

    2016-08-01

    We show how one-loop corrections to scattering amplitudes of scalars and gauge bosons can be obtained from tree amplitudes in one higher dimension. Starting with a complete tree-level scattering amplitude of n + 2 particles in five dimensions, one assumes that two of them cannot be "detected" and therefore an integration over their LIPS is carried out. The resulting object, function of the remaining n particles, is taken to be four-dimensional by restricting the corresponding momenta. We perform this procedure in the context of the tree-level CHY formulation of amplitudes. The scattering equations obtained in the procedure coincide with those derived by Geyer et al. from ambitwistor constructions and recently studied by two of the authors for bi-adjoint scalars. They have two sectors of solutions: regular and singular. We prove that the contribution from regular solutions generically gives rise to unphysical poles. However, using a BCFW argument we prove that the unphysical contributions are always homogeneous functions of the loop momentum and can be discarded. We also show that the contribution from singular solutions turns out to be homogeneous as well.

  1. The accretion rate dependence of burst oscillation amplitude

    CERN Document Server

    Ootes, Laura S; Galloway, Duncan K; Wijnands, Rudy

    2016-01-01

    Neutron stars in low mass X-ray binaries exhibit oscillations during thermonuclear bursts, attributed to asymmetric brightness patterns on the burning surfaces. All models that have been proposed to explain the origin of these asymmetries (spreading hotspots, surface waves, and cooling wakes) depend on the accretion rate. By analysis of archival RXTE data of six oscillation sources, we investigate the accretion rate dependence of the amplitude of burst oscillations. This more than doubles the size of the sample analysed previously by Muno et al. (2004), who found indications for a relationship between accretion rate and oscillation amplitudes. We find that burst oscillation signals can be detected at all observed accretion rates. Moreover, oscillations at low accretion rates are found to have relatively small amplitudes ($A_\\text{rms}\\leq0.10$) while oscillations detected in bursts observed at high accretion rates cover a broad spread in amplitudes ($0.05\\leq A_\\text{rms}\\leq0.20$). In this paper we present t...

  2. Finite amplitude wave interaction with premixed laminar flames

    Science.gov (United States)

    Aslani, Mohamad; Regele, Jonathan D.

    2014-11-01

    The physics underlying combustion instability is an active area of research because of its detrimental impact in many combustion devices, such as turbines, jet engines, and liquid rocket engines. Pressure waves, ranging from acoustic waves to strong shocks, are potential sources of these disturbances. Literature on flame-disturbance interactions are primarily focused on either acoustics or strong shock wave interactions, with little information about the wide spectrum of behaviors that may exist between these two extremes. For example, the interaction between a flame and a finite amplitude compression wave is not well characterized. This phenomenon is difficult to study numerically due to the wide range of scales that need to be captured, requiring powerful and efficient numerical techniques. In this work, the interaction of a perturbed laminar premixed flame with a finite amplitude compression wave is investigated using the Parallel Adaptive Wavelet Collocation Method (PAWCM). This method optimally solves the fully compressible Navier-Stokes equations while capturing the essential scales. The results show that depending on the amplitude and duration of a finite amplitude disturbance, the interaction between these waves and premixed flames can produce a broad range of responses.

  3. Generalized quantum counting algorithm for non-uniform amplitude distribution

    Science.gov (United States)

    Tan, Jianing; Ruan, Yue; Li, Xi; Chen, Hanwu

    2017-03-01

    We give generalized quantum counting algorithm to increase universality of quantum counting algorithm. Non-uniform initial amplitude distribution is possible due to the diversity of situations on counting problems or external noise in the amplitude initialization procedure. We give the reason why quantum counting algorithm is invalid on this situation. By modeling in three-dimensional space spanned by unmarked state, marked state and free state to the entire Hilbert space of n qubits, we find Grover iteration can be regarded as improper rotation in the space. This allows us to give formula to solve counting problem. Furthermore, we express initial amplitude distribution in the eigenvector basis of improper rotation matrix. This is necessary to obtain mathematical analysis of counting problem on various situations. Finally, we design four simulation experiments, the results of which show that compared with original quantum counting algorithm, generalized quantum counting algorithm wins great satisfaction from three aspects: (1) Whether initial amplitude distribution is uniform; (2) the diversity of situations on counting problems; and (3) whether phase estimation technique can get phase exactly.

  4. Maximally Supersymmetric Planar Yang-Mills Amplitudes at Five Loops

    CERN Document Server

    Bern, Z; Johansson, H; Kosower, D A

    2007-01-01

    We present an ansatz for the planar five-loop four-point amplitude in maximally supersymmetric Yang-Mills theory in terms of loop integrals. This ansatz exploits the recently observed correspondence between integrals with simple conformal properties and those found in the four-point amplitudes of the theory through four loops. We explain how to identify all such integrals systematically. We make use of generalized unitarity in both four and D dimensions to determine the coefficients of each of these integrals in the amplitude. Maximal cuts, in which we cut all propagators of a given integral, are an especially effective means for determining these coefficients. The set of integrals and coefficients determined here will be useful for computing the five-loop cusp anomalous dimension of the theory which is of interest for non-trivial checks of the AdS/CFT duality conjecture. It will also be useful for checking a conjecture that the amplitudes have an iterative structure allowing for their all-loop resummation, w...

  5. 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...

  6. Mirror symmetry, toric branes and topological string amplitudes as polynomials

    Energy Technology Data Exchange (ETDEWEB)

    Alim, Murad

    2009-07-13

    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.)

  7. CORRELATION BETWEEN AMPLITUDE AND FREQUENCY FLUCTUATIONS OF SPONTANEOUS OTOACOUSTIC EMISSIONS

    NARCIS (Netherlands)

    VANDIJK, P; WIT, HP; TUBIS, A; TALMADGE, CL; LONG, GR

    1994-01-01

    The normalized cross-correlation function between the amplitude and frequency fluctuations of 11 spontaneous otoacoustic emissions was measured. A significant correlation was found in seven subjects. The correlation coefficient ranged from -0.37 to +0.65 across subjects. In four subjects, the amplit

  8. 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 dat

  9. Focusing Light through Random Photonic Media by Binary Amplitude Modulation

    CERN Document Server

    Akbulut, Duygu; van Putten, Elbert G; Vos, Willem L; Mosk, Allard P

    2011-01-01

    We study the focusing of light through random photonic materials using wavefront shaping. We explore a novel approach namely binary amplitude modulation. To this end, the light incident to a random photonic medium is spatially divided into a number of segments. We identify the segments that give rise to fields that are out of phase with the total field at the intended focus and assign these a zero amplitude, whereas the remaining segments maintain their original amplitude. Using 812 independently controlled segments of light, we find the intensity at the target to be 75 +/- 6 times enhanced over the average intensity behind the sample. We experimentally demonstrate focusing of light through random photonic media using both an amplitude only mode liquid crystal spatial light modulator and a MEMS-based spatial light modulator. Our use of Micro Electro-Mechanical System (MEMS)-based digital micromirror devices for the control of the incident light field opens an avenue to high speed implementations of wavefront ...

  10. Amplitude Scaling of Asymmetry-Induced Transport: A Second Look

    Science.gov (United States)

    Eggleston, D. L.; Carrillo, B.

    2000-10-01

    Our initial experiments(D.L. Eggleston, in Non-Neutral Plasma Physics III, AIP Conference Proceedings 498, 1999, pp. 241-249.) on asymmetry-induced transport in non-neutral plasmas found the radial particle flux at small radii to be proportional to φ^2, where φ is the applied asymmetry amplitude. However, other researchers(Jason M. Kriesel and C. Fred Driscoll, op. cit., pp. 256-265.), using the global expansion rate as a measure of the transport, have observed a φ^1 scaling when the rigidity (the ratio of the axial bounce to the azimuthal rotation frequency) is in the range 1 - 10. In an effort to resolve this discrepancy, we have extended our measurements to different radii and asymmetry frequencies. Although the results to date are generally in agreement with those previously reported (φ^2 scaling at low asymmetry amplitudes falling off to a weaker scaling at higher amplitudes), we have observed some cases where the low amplitude scaling is closer to φ^1. However, both the φ^2 and φ^1 cases have rigidities less than ten. Instead, we find that the φ^1 cases are characterized by an induced flux that is comparable in magnitude but opposite in sign to the background flux.

  11. Closed-form decomposition of one-loop massive amplitudes

    NARCIS (Netherlands)

    Britto, R.; Feng, B.; Mastrolia, P.

    2008-01-01

    We present formulas for the coefficients of 2-, 3-, 4-, and 5-point master integrals for one-loop massive amplitudes. The coefficients are derived from unitarity cuts in D dimensions. The input parameters can be read off from any unitarity-cut integrand, as assembled from tree-level expressions,

  12. Superstring amplitudes as a Mellin transform of supergravity

    Energy Technology Data Exchange (ETDEWEB)

    Stieberger, Stephan, E-mail: stephan.stieberger@mpp.mpg.de [Max-Planck-Institut für Physik, Werner-Heisenberg-Institut, 80805 München (Germany); Taylor, Tomasz R. [Department of Physics, Northeastern University, Boston, MA 02115 (United States)

    2013-08-01

    At the tree level, the maximally helicity violating amplitudes of N gauge bosons in open superstring theory and of N gravitons in supergravity are known to have simple representations in terms of tree graphs. For superstrings, the graphs encode integral representations of certain generalized Gaussian hypergeometric functions of kinematic invariants while for supergravity, they represent specific kinematic expressions constructed from spinor-helicity variables. We establish a superstring/supergravity correspondence for this class of amplitudes, by constructing a mapping between the positions of gauge boson vertices at the disk boundary and the helicity spinors associated to gravitons. After replacing vertex positions by a larger set of (N(N−3))/2 coordinates, the superstring amplitudes become (multiple) Mellin transforms of supergravity amplitudes, from the projective space into the dual Mellin space of (N(N−3))/2 kinematic invariants. Similarly, inverse Mellin transforms transmute open superstrings into supergravity. We elaborate on the properties of multiple Mellin and inverse Mellin transforms in the framework of superstring/supergravity correspondence.

  13. Quantum Corrections to Scattering Amplitude in Conical Space-time

    CERN Document Server

    Shiraishi, Kiyoshi

    2015-01-01

    It is known that the vacuum polarization of zero-point field arises around a conical singularity generated by an infinite, straight cosmic string. In this paper we study quantum electromagnetic corrections to the gravitational Aharonov-Bohm effect around a cosmic string. We find the scattering amplitude from a conical defect for charged Klein-Gordon field.

  14. One-Loop Corrections from Higher Dimensional Tree Amplitudes

    CERN Document Server

    Cachazo, Freddy; Yuan, Ellis Ye

    2015-01-01

    We show how one-loop corrections to scattering amplitudes of scalars and gauge bosons can be obtained from tree amplitudes in one higher dimension. Starting with a complete tree-level scattering amplitude of n+2 particles in five dimensions, one assumes that two of them cannot be "detected" and therefore an integration over their LIPS is carried out. The resulting object, function of the remaining n particles, is taken to be four-dimensional by restricting the corresponding momenta. We perform this procedure in the context of the tree-level CHY formulation of amplitudes. The scattering equations obtained in the procedure coincide with those derived by Geyer et al from ambitwistor constructions and recently studied by two of the authors for bi-adjoint scalars. They have two sectors of solutions: regular and singular. We prove that the contribution from regular solutions generically gives rise to unphysical poles. However, using a BCFW argument we prove that the unphysical contributions are always homogeneous f...

  15. Exact Amplitude--Based Resummation QCD Predictions and LHC Data

    CERN Document Server

    Ward, B F L; Yost, S A

    2014-01-01

    We present the current status of the comparisons with the respective data of the predictions of our approach of exact amplitude-based resummation in quantum field theory as applied to precision QCD calculations as needed for LHC physics, using the MC Herwiri1.031. The agreement between the theoretical predictions and the data exhibited continues to be encouraging.

  16. An Amplitude Spectral Capon Estimator with a Variable Filter Length

    DEFF Research Database (Denmark)

    Nielsen, Jesper Kjær; Smaragdis, Paris; Christensen, Mads Græsbøll;

    2012-01-01

    The filter bank methods have been a popular non-parametric way of computing the complex amplitude spectrum. So far, the length of the filters in these filter banks has been set to some constant value independently of the data. In this paper, we take the first step towards considering the filter...

  17. Precise Radial Velocities of Polaris: Detection of Amplitude Growth

    CERN Document Server

    Lee, Byeong-Cheol; Han, Inwoo; Park, Myeong-Gu; Kim, Kang-Min

    2008-01-01

    We present a first results from a long-term program of a radial velocity study of Cepheid Polaris (F7 Ib) aimed to find amplitude and period of pulsations and nature of secondary periodicities. 264 new precise radial velocity measurements were obtained during 2004-2007 with the fiber-fed echelle spectrograph Bohyunsan Observatory Echelle Spectrograph (BOES) of 1.8m telescope at Bohyunsan Optical Astronomy Observatory (BOAO) in Korea. We find a pulsational radial velocity amplitude and period of Polaris for three seasons of 2005.183, 2006.360, and 2007.349 as 2K = 2.210 +/- 0.048 km/s, 2K = 2.080 +/- 0.042 km/s, and 2K = 2.406 +/- 0.018 km/s respectively, indicating that the pulsational amplitudes of Polaris that had decayed during the last century is now increasing rapidly. The pulsational period was found to be increasing too. This is the first detection of a historical turnaround of pulsational amplitude change in Cepheids. We clearly find the presence of additional radial velocity variations on a time scal...

  18. Simulation of transients of high amplitude in pipe systems

    NARCIS (Netherlands)

    Boersma, J.M.; Looijmans, K.N.H.

    1999-01-01

    Fast high-amplitude transients ask for a non-linear modelling approach in which large density variations and heat exchange can be considered. Operation of safety-valves, relief valves, the occurrence of valve failure and the start-up or shutdown of rotating equipment in industrial pipe systems can l

  19. Nonlinear Saturation Amplitude in Classical Planar Richtmyer-Meshkov Instability

    Science.gov (United States)

    Liu, Wan-Hai; Wang, Xiang; Jiang, Hong-Bin; Ma, Wen-Fang

    2016-04-01

    The classical planar Richtmyer-Meshkov instability (RMI) at a fluid interface supported by a constant pressure is investigated by a formal perturbation expansion up to the third order, and then according to definition of nonlinear saturation amplitude (NSA) in Rayleigh-Taylor instability (RTI), the NSA in planar RMI is obtained explicitly. It is found that the NSA in planar RMI is affected by the initial perturbation wavelength and the initial amplitude of the interface, while the effect of the initial amplitude of the interface on the NSA is less than that of the initial perturbation wavelength. Without marginal influence of the initial amplitude, the NSA increases linearly with wavelength. The NSA normalized by the wavelength in planar RMI is about 0.11, larger than that corresponding to RTI. Supported by the National Natural Science Foundation of China under Grant Nos. 11472278 and 11372330, the Scientific Research Foundation of Education Department of Sichuan Province under Grant No. 15ZA0296, the Scientific Research Foundation of Mianyang Normal University under Grant Nos. QD2014A009 and 2014A02, and the National High-Tech ICF Committee

  20. Local integrands for two-loop QCD amplitudes

    CERN Document Server

    Badger, Simon; Peraro, Tiziano

    2016-01-01

    In this talk we review the recent computation of the five- and six-gluon two-loop amplitudes in Yang-Mills theory using local integrands which make the infrared pole structure manifest. We make some remarks on the connection with BCJ relations and the all-multiplicity structure.

  1. Educing GPDs from Amplitudes of Hard Exclusive Processes

    CERN Document Server

    Polyakov, M V

    2007-01-01

    The dual parametrization of generalized parton distributions (GPDs) is considered in details. We discuss which part of information about hadron structure encoded in GPDs [part of total GPD image] can be restored from the known amplitude of a hard exclusive process. The physics content of this partial image is analyzed.

  2. Remote identification of the vibration amplitude of ship hull

    Directory of Open Access Journals (Sweden)

    A. N. Pinchuk

    2014-01-01

    Full Text Available The aim is to develop the methodological support to determine vibration amplitude of the ship hull remotely using a coherent radar centimeter range based on the variation of the Doppler signal spectrum reflected from a vibrating surface.The paper presents a synthesized mathematical model of the radio signal reflected from the vibrating surface. It is the signal of coherent radar of continuous radiation with a known carrier frequency and the amplitude of the radiated signal. In the synthesis it was believed that the displacement in the radial direction with respect to the vibrating surface radar was sinusoidal.The dependences of the vibration amplitude on the value of the normalized Doppler radio signal spectrum at the second harmonic frequency are obtained. Cycle results of field experiments to study the variability of the sea surface, determining the level of its roughness, allows us to establish that the energy of surface waves of gravitational-capillary range has a high correlation with the wind speed. It is proved that the ratio of the spectral density levels at vibration frequency and its multiple frequencies is specified by the index of phase modulation linearly related to the amplitude of vibration of the ship hull.The results are significant for radar (radar detection of water targets using the coherent radar of centimeter range, ensuring the correct records of noise generated by the scattering of radio waves from the water surface.

  3. Regge amplitudes from AdS/CFT duality

    CERN Document Server

    Peschanski, R

    2002-01-01

    String theory has long ago been initiated by the quest for a theoretical explanation of the observed high-energy ``Regge behaviour'' of strong interaction amplitudes, but this 35-years-old puzzle is still unsoved. We discuss how modern tools like the AdS/CFT correspondence give a new insight on the problem.

  4. The sunrise amplitude equation applied to an Egyptian temple

    CERN Document Server

    Sparavigna, Amelia Carolina

    2012-01-01

    An equation, fundamental for solar energy applications, can be used to determine the sunrise amplitude at given latitude. It is therefore suitable for being applied to archaeoastronomical calculations concerning the orientation of towns, worship places and buildings. Here it is discussed the case of the Great Temple of Amarna, Egypt, oriented toward the sunrise on the winter solstice.

  5. Journeys through the Precision Frontier: Amplitudes for Colliders

    CERN Document Server

    Petriello, Frank; TASI 2014; TASI2014; 2014 Theoretical Advanced Study Institute in Elementary Particle Physics

    2014-01-01

    This volume is a compilation of the lectures at TASI 2014. The coverage focuses on modern calculational techniques for scattering amplitudes, and on the phenomenology of QCD in hadronic collisions. Introductions to flavor physics, dark matter, and physics beyond the Standard Model are also provided. The lectures are accessible to graduate students at the initial stages of their research careers.

  6. A convergence theorem for asymptotic expansions of Feynman amplitudes

    Energy Technology Data Exchange (ETDEWEB)

    Mabouisson, A.P.C. [Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil)

    1999-06-01

    The Mellin representations of Feynman integrals is revisited. From this representation, and asymptotic expansion for generic Feynman amplitudes, for any set of invariants going to zero or to {infinity}, may be obtained. In the case of all masses going to zero in Euclidean metric, we show that the truncated expansion has a rest compatible with convergence of the series. (author)

  7. 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...

  8. The universal expression for the amplitude square in quantum electrodynamics

    CERN Document Server

    Karplyuk, K S

    2015-01-01

    The universal expression for the amplitude square |u_f M u_i|^2 for any matrix of interaction M is derived. It has obvious covariant form. It allows the avoidance of calculation of products of the Dirac's matrices traces and allows easy calculation of cross-sections of any different processes with polarized and unpolarized particles.

  9. Oscillations of a Simple Pendulum with Extremely Large Amplitudes

    Science.gov (United States)

    Butikov, Eugene I.

    2012-01-01

    Large oscillations of a simple rigid pendulum with amplitudes close to 180[degrees] are treated on the basis of a physically justified approach in which the cycle of oscillation is divided into several stages. The major part of the almost closed circular path of the pendulum is approximated by the limiting motion, while the motion in the vicinity…

  10. Volume Functions of Historical Texts and the Amplitude Correlation Principle.

    Science.gov (United States)

    Fomenko, Anatoliy T.; Rachev, Svetlozar T.

    1990-01-01

    Proposes an empirico-statistical model to differentiate dependent and independent historical texts. Formulates a regard for information principle and an amplitude correlation principle. Experimentally examines and validates the model and both principles using specific historical texts. Includes tables and graphs. Appends further discussion of the…

  11. 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.

  12. The effect of speed of processing training on microsaccade amplitude.

    Directory of Open Access Journals (Sweden)

    Stephen Layfield

    Full Text Available Older adults experience cognitive deficits that can lead to driving errors and a loss of mobility. Fortunately, some of these deficits can be ameliorated with targeted interventions which improve the speed and accuracy of simultaneous attention to a central and a peripheral stimulus called Speed of Processing training. To date, the mechanisms behind this effective training are unknown. We hypothesized that one potential mechanism underlying this training is a change in distribution of eye movements of different amplitudes. Microsaccades are small amplitude eye movements made when fixating on a stimulus, and are thought to counteract the "visual fading" that occurs when static stimuli are presented. Due to retinal anatomy, larger microsaccadic eye movements are needed to move a peripheral stimulus between receptive fields and counteract visual fading. Alternatively, larger microsaccades may decrease performance due to neural suppression. Because larger microsaccades could aid or hinder peripheral vision, we examine the distribution of microsaccades during stimulus presentation. Our results indicate that there is no statistically significant change in the proportion of large amplitude microsaccades during a Useful Field of View-like task after training in a small sample of older adults. Speed of Processing training does not appear to result in changes in microsaccade amplitude, suggesting that the mechanism underlying Speed of Processing training is unlikely to rely on microsaccades.

  13. The Dynamics of Large-Amplitude Motion in Energized Molecules

    Energy Technology Data Exchange (ETDEWEB)

    Perry, David S. [Univ. of Akron, OH (United States). Dept. of Chemistry

    2016-05-27

    Chemical reactions involve large-amplitude nuclear motion along the reaction coordinate that serves to distinguish reactants from products. Some reactions, such as roaming reactions and reactions proceeding through a loose transition state, involve more than one large-amplitude degree of freedom. Because of the limitation of exact quantum nuclear dynamics to small systems, one must, in general, define the active degrees of freedom and separate them in some way from the other degrees of freedom. In this project, we use large-amplitude motion in bound model systems to investigate the coupling of large-amplitude degrees of freedom to other nuclear degrees of freedom. This approach allows us to use the precision and power of high-resolution molecular spectroscopy to probe the specific coupling mechanisms involved, and to apply the associated theoretical tools. In addition to slit-jet spectra at the University of Akron, the current project period has involved collaboration with Michel Herman and Nathalie Vaeck of the Université Libre de Bruxelles, and with Brant Billinghurst at the Canadian Light Source (CLS).

  14. Os conflitos dos últimos 25 anos (I)

    OpenAIRE

    Moita, Luis

    2005-01-01

    Existem razões para admitir que as grandes transformações do ordenamento internacional têm estado associadas a guerras. Foi assim com a Guerra dos Trinta Anos, que não se limitou a um conflito religioso entre católicos e protestantes, mas constituiu uma guerra internacional de grande dimensão, envolvendo a Suécia, a França e o Império dos Habsburgos, e dela resultou uma nova Europa progressivamente assente em Estados nações. Foi assim com as guerras revolucionárias francesas e as do período n...

  15. Estudo do perfil dos turistas luxemburgueses

    OpenAIRE

    Leal, Kelen

    2012-01-01

    Dissertação de Mestrado em Marketing e Promoção Turística apresentada à ESTM - Escola Superior de Turismo e Tecnologia do Mar do Instituto Politécnico de Leiria Perante a atual evolução dos mercados turísticos e a mudança no comportamento do turista, torna-se fundamental conhecer profundamente as necessidades, as motivações e as preferências dos consumidores-turistas, de modo a obter uma eficaz capacidade de resposta às necessidades e preferências da procura. Com o aumento da competitiv...

  16. OS DIREITOS DOS TRABALHADORES COMO DIREITOS FUNDAMENTAIS

    OpenAIRE

    Vecchi, Ipojucan Demétrius

    2012-01-01

    O objetivo do presente texto é tentar responder, sumariamente diante das limitações próprias de um artigo, ao seguinte questionamento: quais as consequências do reconhecimento dos direitos dos trabalhadores como direitos fundamentais albergados pela Constituição Federal Brasileira de 1988? No momento em que a Ordem Constitucional de um Estado Democrático de Direito, fundado na dignidade humana e no valor social do trabalho, entre outros princípios fundamentais, eleva ao patamar de direitos fu...

  17. Relativistic motion of charged particles in the interaction of short pulses of intense laser light with plasma; Movimiento relativista de particulas cargadas en la interaccion de pulsos cortos de luz laser intensa con plasma

    Energy Technology Data Exchange (ETDEWEB)

    Gomez R, F

    2004-07-01

    interval d{tau} of the electron that per se is an invariant, it is proportional to a certain interval d{eta}. In the chapter 3 it will see that the movement analysis of the charged particles in the electromagnetic field presents serious mathematical difficulties, where the integration of the movement equations results extraordinarily complex and it can only be integrated in most of the cases by numerical means. We will present the procedure used for the deduction of the equations of motion of a charged particle in the interaction of a laser light pulse and a homogeneous magnetic field in arbitrary direction, with the addition of an harmonic term of force. In this chapter it is not sought to make a meticulous discussion of the involved physics and only we will present the algebraic procedure. In the chapter 4 we will present the integration method of the Lorentz force, and we will obtain the exact solution for the case of a pulse of a plane wave elliptically polarized of arbitrary amplitude spreading along an external magnetic field. The solution method will allow to decrease the solutions to the case in which we have an infinite waves train reported by Ondarza (10) and so the corresponding solutions will be obtained reported in the literature by other authors. The main contribution in this part will be the one of obtaining an exact solution for the problem of the interaction of an electromagnetic pulse, modulated by a form of gaussian type, and a charged particle. The above-mentioned approaches in acceptable measure to real situations in well-known experiments. It will be found that when the form of the pulse is introduced to modulate the electromagnetic field, an amplification of the resonance zone in the solutions appears. Such resonance depends of the external magnetic field that fixes by turns the cyclotron frequency, and of the number of optical cycles that compose the encircling one that modulates the pulse form. In the chapter 5 it will see the case of small

  18. Capela Santa Maria dos Anjos: uma obra alternativa

    Directory of Open Access Journals (Sweden)

    Edite Galote Carranza

    2017-04-01

    Full Text Available Celebrando cem anos de nascimento da arquiteta Lina Bo Bardi, seu trabalho continua incitando a curiosidade de pesquisadores, artistas e arquitetos de todo o mundo, devido tanto à qualidade, à subjetividade artística, às ideias, aos ideais e à filosofia de fundo como à amplitude da obra nas áreas de cenografia, design, crítica, museologia e arquitetura. Entre suas obras arquitetônicas, a Capela Santa Maria dos Anjos, de 1978, em Vargem Grande Paulista, SP, merece maior atenção. Embora possa ser considerada singela, a Capela é uma obra densa e representativa da Arquitetura Alternativa ao status quo arquitetônico paulista. Este artigo analisa a Capela e sua relação com os conceitos de nacional-popular e Te-Ato, a fé franciscana e as culturas erudita e popular, a fim de contribuir para o melhor entendimento da obra que dialoga com a cena cultural e política da época.

  19. Measuring finite-frequency body-wave amplitudes and traveltimes

    Science.gov (United States)

    Sigloch, Karin; Nolet, Guust

    2006-10-01

    We have developed a method to measure finite-frequency amplitude and traveltime anomalies of teleseismic P waves. We use a matched filtering approach that models the first 25 s of a seismogram after the P arrival, which includes the depth phases pP and sP. Given a set of broad-band seismograms from a teleseismic event, we compute synthetic Green's functions using published moment tensor solutions. We jointly deconvolve global or regional sets of seismograms with their Green's functions to obtain the broad-band source time function. The matched filter of a seismogram is the convolution of the Green's function with the source time function. Traveltimes are computed by cross-correlating each seismogram with its matched filter. Amplitude anomalies are defined as the multiplicative factors that minimize the RMS misfit between matched filters and data. The procedure is implemented in an iterative fashion, which allows for joint inversion for the source time function, amplitudes, and a correction to the moment tensor. Cluster analysis is used to identify azimuthally distinct groups of seismograms when source effects with azimuthal dependence are prominent. We then invert for one source time function per group. We implement this inversion for a range of source depths to determine the most likely depth, as indicated by the overall RMS misfit, and by the non-negativity and compactness of the source time function. Finite-frequency measurements are obtained by filtering broad-band data and matched filters through a bank of passband filters. The method is validated on a set of 15 events of magnitude 5.8 to 6.9. Our focus is on the densely instrumented Western US. Quasi-duplet events (`quplets') are used to estimate measurement uncertainty on real data. Robust results are achieved for wave periods between 24 and 2 s. Traveltime dispersion is on the order of 0.5 s. Amplitude anomalies are on the order of 1 db in the lowest bands and 3 db in the highest bands, corresponding to

  20. Joint inversion of surface and borehole magnetic amplitude data

    Science.gov (United States)

    Li, Zelin; Yao, Changli; Zheng, Yuanman; Yuan, Xiaoyu

    2016-04-01

    3D magnetic inversion for susceptibility distribution is a powerful tool in quantitative interpretation of magnetic data in mineral exploration. However, the inversion and interpretation of such data are faced with two problems. One problem is the poor imaging results of deep sources when only surface data are inverted. The other is the unknown total magnetization directions of sources when strong remanence exists. To deal with these problems simultaneously, we propose a method through the joint inversion of surface and borehole magnetic amplitude data. In this method, we first transform both surface and borehole magnetic data to magnetic amplitude data that are less sensitive to the directions of total magnetization, and then preform a joint inversion of the whole amplitude data to generate a 3D susceptibility distribution. The amplitude inversion algorithm uses Tikhonov regularization and imposes a positivity constraint on the effective susceptibility defined as the ratio of magnetization magnitude over the geomagnetic field strength. In addition, a distance-based weighting function is used to make the algorithm applicable to joint data sets. To solve this positivity-constraint inversion problem efficiently, an appropriate optimization method must be chosen. We first use an interior-point method to incorporate the positivity constraint into the total objective function, and then minimize the objective function via a Gauss-Newton method due to the nonlinearity introduced by the positivity constraint and the amplitude data. To further improve the efficiency of the inversion algorithm, we use a conjugate gradient method to carry out the fast matrix-vector multiplication during the minimization. To verify the utility of the proposed method, we invert the synthetic and field data using three inversion methods, including the joint inversion of surface and borehole three-component magnetic data, the inversion of surface magnetic amplitude data, and the proposed joint

  1. The Correlation between Electroencephalography Amplitude and Interictal Abnormalities: Audit study

    Directory of Open Access Journals (Sweden)

    Sami F. Al-Rawas

    2014-10-01

    Full Text Available Objectives: The aim of this study was to establish the relationship between background amplitude and interictal abnormalities in routine electroencephalography (EEG. Methods: This retrospective audit was conducted between July 2006 and December 2009 at the Department of Clinical Physiology at Sultan Qaboos University Hospital (SQUH in Muscat, Oman. A total of 1,718 electroencephalograms (EEGs were reviewed. All EEGs were from patients who had been referred due to epilepsy, syncope or headaches. EEGs were divided into four groups based on their amplitude: group one ≤20 μV; group two 21–35 μV; group three 36–50 μV, and group four >50 μV. Interictal abnormalities were defined as epileptiform discharges with or without associated slow waves. Abnormalities were identified during periods of resting, hyperventilation and photic stimulation in each group. Results: The mean age ± standard deviation of the patients was 27 ± 12.5 years. Of the 1,718 EEGs, 542 (31.5% were abnormal. Interictal abnormalities increased with amplitude in all four categories and demonstrated a significant association (P <0.05. A total of 56 EEGs (3.3% had amplitudes that were ≤20 μV and none of these showed interictal epileptiform abnormalities. Conclusion: EEG amplitude is an important factor in determining the presence of interictal epileptiform abnormalities in routine EEGs. This should be taken into account when investigating patients for epilepsy. A strong argument is made for considering long-term EEG monitoring in order to identify unexplained seizures which may be secondary to epilepsy. It is recommended that all tertiary institutions provide EEG telemetry services.

  2. Dos realizaciones prefabricadas en Bolonia/Italia

    Directory of Open Access Journals (Sweden)

    Salas, Julián

    1981-04-01

    Full Text Available Se describen dos obras realizadas mediante elementos prefabricados en Bolonia (Italia por la empresa Grandi Lavori. Se trata de un conjunto de tres grandes torres con proyecto del profesor Kenzo Tange y una construcción-piloto en el recinto ferial.

  3. Consistentie met MS-DOS software

    NARCIS (Netherlands)

    Olsthoorn TN

    1988-01-01

    Zonder de keuze van een zekere standaard-lijn ten aanzien van de software die men zelf gebruikt, kan nauwelijks efficient met een computer worden gewerkt. Onder UNIX en op de Macintosh is het gebruik van programma's en de uitwisseling van gegevens daartussen gestandaardiseerd. Onder MS-DOS

  4. A Teoria dos Conjuntos de Cantor

    Directory of Open Access Journals (Sweden)

    Antônio Acra Freiria

    1992-07-01

    Full Text Available No final dos anos 50 e começo doe anos 60, houve uma reformulação significativa da Matemática no Brasil. Sob a bandeira do modernismo, seus defensores buscaram inovações no ensino da Matemática. Dessa forma, os reformistas se concentraram essencialmente na linguagem abusiva e no formalismo da Teoria dos Conjuntos, o que trouxe mais danos do que benefícios do ensino da Matemática de 1º e 2ºgraus. A linguagem formal da Teoria dos Conjuntos é porém sua parte menos importante. A teoria criada por Cantor tão logo revelou-se como o fundamento de toda a Matemática, possibilitando o desenvolvimento de novas disciplinas, como a Topologia, a Algebra Abstrata, a Teoria da Medida e Integração, a Teoria da Probabilidade e a Análise Funcional. O objetivo deste trabalho é um relato sucinto de como surgiu essa teoria, apresentando o "Conjunto de Cantor" como um dos mais ricos exemplos de "Conjunto perfeito" encontrados na literatura matemática.

  5. PERFIL E EXPECTATIVAS DOS ALUNOS CONCLUINTES DOS CURSOS TECNICOS INTEGRADOS DO IFRN, CAMPUS APODI

    Directory of Open Access Journals (Sweden)

    Saara Ramila Gurgel de Oliveira

    2014-11-01

    Full Text Available Este trabalho teve por finalidade caracterizar o perfil e as expectativas dos alunos dos terceiros e quartos anos dos cursos técnicos integrado de Zootecnia e Biocombustíveis do Instituto Federal de Educação, Ciência e Tecnologia do Rio Grande do Norte – Campus Apodi. A pesquisa foi realizada com 138 alunos, através da aplicação de questionários com perguntas abertas e fechadas. A análise dos dados foi realizada de maneira descritiva e os mesmos apresentados em percentuais. Os principais resultados mostraram que as mulheres são maioria (60,9% e que a idade média foi de 17,4 anos. 99,3% dos alunos afirmaram querer cursar uma faculdade e a Universidade Federal do Rio Grande do Norte foi a instituição mais citada. Os cursos mais citados pelos discentes foram: Medicina, Ciência e tecnologia, Engenharia química, Engenharia civil, Direito e Medicina veterinária. Quanto a prática profissional, 89,9% dos alunos a realizam na forma de projetos de pesquisa ou extensão e 10,1% na forma de estágios. Mais de 97% dos estudantes estão satisfeitos com as disciplinas, porém 64,5% não estão satisfeitos com a quantidade de aulas práticas dos cursos. Quanto ao mercado de trabalho, 58,8% acreditam que há boas oportunidades. Dessa forma, conclui-se que são necessárias medidas para qualificar o ensino dos alunos, todavia, as mesmas dependem de uma gestão democrática que analise a opinião de toda a comunidade escolar.

  6. Solubilidade e disponibilidade dos micronutrientes em fertilizantes

    Directory of Open Access Journals (Sweden)

    F. Vale

    1999-06-01

    Full Text Available A legislação brasileira exige que os micronutrientes nos fertilizantes sejam garantidos pelo teor total presente. Isto abre um precedente para a utilização de produtos não considerados como fontes de micronutrientes na fabricação dos fertilizantes. Todavia, a eficiência agronômica desses produtos é ainda duvidosa. Objetivou-se realizar um trabalho para caracterizar a solubilidade e a disponibilidade dos micronutrientes em trinta fertilizantes comerciais, por meio do uso de cinco extratores químicos: a água e soluções de ácido cítrico a 2%, de citrato neutro de amônio na diluição 1 + 9, de DTPA 0,005 mol L-1 e de EDTA 0,005 mol L-1. Os resultados mostraram a baixa solubilidade dos micronutrientes metálicos (cobre, ferro, manganês e zinco dos fertilizantes tipo "fritas". O ácido cítrico a 2% mostrou-se promissor na caracterização da disponibilidade de cobre, manganês e zinco para as plantas. Para o ferro não houve uma definição entre os extratores estudados. O boro teve boa solubilidade, tanto nos fertilizantes solúveis, como nos insolúveis em água, e a garantia pelo teor total mostrou-se bom indicativo da disponibilidade do elemento. Para o molibdênio a solubilidade foi maior para os fertilizantes com baixo teor do elemento. A garantia dos micronutrientes catiônicos pelo teor total, conforme exige a legislação, não indicou a sua real disponibilidade nos fertilizantes comerciais, mostrando a necessidade de uma definição de extratores para esse fim.

  7. TASI 2014: Lectures on Gauge and Gravity Amplitude Relations

    Science.gov (United States)

    Carrasco, John Joseph M.

    In these lectures I talk about simplifications and universalities found in scattering amplitudes for gauge and gravity theories. In contrast to Ward identities, which are understood to arise from familiar symmetries of the classical action, these structures are currently only understood in terms of graphical organizational principles, such as the gauge-theoretic color-kinematics duality and the gravitational double-copy structure, for local representations of multi-loop S-matrix elements. These graphical principles make manifest new relationships in and between gauge and gravity scattering amplitudes. My lectures will focus on arriving at such graphical organizations for generic theories with examples presented from maximal supersymmetry, and their use in unitarity-based multiloop integrand construction.

  8. Large amplitude electromagnetic solitons in intense laser plasma interaction

    Institute of Scientific and Technical Information of China (English)

    Li Bai-Wen; Ishiguro S; Skoric M M

    2006-01-01

    This paper shows that the standing, backward- and forward-accelerated large amplitude relativistic electromagnetic solitons induced by intense laser pulse in long underdense collisionless homogeneous plasmas can be observed by particle simulations. In addition to the inhomogeneity of the plasma density, the acceleration of the solitons also depends upon not only the laser amplitude but also the plasma length. The electromagnetic frequency of the solitons is between about half and one of the unperturbed electron plasma frequency. The electrostatic field inside the soliton has a one-cycle structure in space, while the transverse electric and magnetic fields have half-cycle and one-cycle structure respectively.Analytical estimates for the existence of the solitons and their electromagnetic frequencies qualitatively coincide with our simulation results.

  9. Fast calculation of HELAS amplitudes using graphics processing unit (GPU)

    CERN Document Server

    Hagiwara, K; Okamura, N; Rainwater, D L; Stelzer, T

    2009-01-01

    We use the graphics processing unit (GPU) for fast calculations of helicity amplitudes of physics processes. As our first attempt, we compute $u\\overline{u}\\to n\\gamma$ ($n=2$ to 8) processes in $pp$ collisions at $\\sqrt{s} = 14$TeV by transferring the MadGraph generated HELAS amplitudes (FORTRAN) into newly developed HEGET ({\\bf H}ELAS {\\bf E}valuation with {\\bf G}PU {\\bf E}nhanced {\\bf T}echnology) codes written in CUDA, a C-platform developed by NVIDIA for general purpose computing on the GPU. Compared with the usual CPU programs, we obtain 40-150 times better performance on the GPU.

  10. Symbol rate identification for auxiliary amplitude modulation optical signal

    Science.gov (United States)

    Wei, Junyu; Dong, Zhi; Huang, Zhiping; Zhang, Yimeng

    2016-09-01

    In this paper, we creatively propose and demonstrate a method for symbol rate identification (SRI) of auxiliary amplitude modulation (AAM) optical signal based on asynchronous delay-tap sampling (ADTS) and average magnitude difference function (AMDF). The method can accurately estimate symbol rate and has large transmission impairments tolerance. Furthermore, it can be realized in the digital signal processor (DSP) with low logical resources because of multiplication-free. In order to improve the accuracy of SRI, the peak to valley ratio (PTVR) of AMDF is introduced into our method for blind chromatic dispersion (CD) compensation. The results of the numerical simulations show that the overall maximum SRI error is smaller 0.079% for return-to-zero (RZ) on-off keying (OOK), RZ differential phase-shift keying (DPSK), RZ differential quadrature phase-shift keying (DQPSK) and RZ 16-ary quadrature amplitude modulation (QAM) with 50% duty cycles.

  11. On-Shell Diagrams for N = 8 Supergravity Amplitudes

    CERN Document Server

    Heslop, Paul

    2016-01-01

    We define recursion relations for N = 8 supergravity amplitudes using a generalization of the on-shell diagrams developed for planar N = 4 super-Yang-Mills. Although the recursion relations generically give rise to non-planar on-shell diagrams, we show that at tree-level the recursion can be chosen to yield only planar diagrams, the same diagrams occurring in the planar N = 4 theory. This implies non-trivial identities for non-planar diagrams as well as interesting relations between the N = 4 and N = 8 theories. We show that the on-shell diagrams of N = 8 supergravity obey equivalence relations analogous to those of N = 4 super-Yang-Mills, and we develop a systematic algorithm for reading off Grassmannian integral formulae directly from the on-shell diagrams. We also show that the 1-loop 4-point amplitude of N = 8 supergravity can be obtained from on-shell diagrams.

  12. Harmonic R-matrices for scattering amplitudes and spectral regularization

    Energy Technology Data Exchange (ETDEWEB)

    Ferro, Livia; Plefka, Jan [Humboldt-Universitaet, Berlin (Germany). Inst. fuer Physik; Lukowski, Tomasz [Humboldt-Universitaet, Berlin (Germany). Inst. fuer Physik; Humboldt-Universitaet, Berlin (Germany). Inst. fuer Mathematik; Humboldt-Univ. Berlin (Germany). IRIS Adlershof; Meneghelli, Carlo [Hamburg Univ. (Germany). Fachbereich 11 - Mathematik; Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany). Theory Group; Staudacher, Matthias [Humboldt-Universitaet, Berlin (Germany). Inst. fuer Mathematik; Humboldt-Universitaet, Berlin (Germany). Inst. fuer Physik; Max-Planck-Institut fuer Gravitationsphysik (Albert-Einstein-Institut), Potsdam (Germany)

    2012-12-15

    Planar N=4 super Yang-Mills appears to be integrable. While this allows to find this theory's exact spectrum, integrability has hitherto been of no direct use for scattering amplitudes. To remedy this, we deform all scattering amplitudes by a spectral parameter. The deformed tree-level four-point function turns out to be essentially the one-loop R-matrix of the integrable N=4 spin chain satisfying the Yang-Baxter equation. Deformed on-shell three-point functions yield novel three-leg R-matrices satisfying bootstrap equations. Finally, we supply initial evidence that the spectral parameter might find its use as a novel symmetry-respecting regulator replacing dimensional regularization. Its physical meaning is a local deformation of particle helicity, a fact which might be useful for a much larger class of non-integrable four-dimensional field theories.

  13. Evaluation of the Cachazo-He-Yuan gauge amplitude

    Science.gov (United States)

    Lam, C. S.; Yao, York-Peng

    2016-05-01

    The Cachazo-He-Yuan (CHY) formula for n -gluon scattering is known to give the same amplitude as the one obtained from Feynman diagrams, though the former contains neither vertices nor propagators explicitly. The equivalence was shown by indirect means, not by a direct evaluation of the (n -3 )-dimensional integral in the CHY formula. The purpose of this paper is to discuss how such a direct evaluation can be carried out. There are two basic difficulties in the calculation: how to handle the large number of terms in the reduced Pfaffian, and how to carry out the integrations in the presence of a σ dependence much more complicated than the Parke-Taylor form found in a CHY double-color scalar amplitude. We have solved both of these problems, and have formulated a method that can be applied to any n . Many examples are provided to illustrate these calculations.

  14. Amplitude analysis of resonant production in three pions

    CERN Document Server

    Jackura, Andrew; Szczepaniak, Adam

    2016-01-01

    We present some results on the analysis of three pion resonances. The analyses are motivated by the recent release of the largest data set on diffractively produced three pions by the COMPASS collaboration. We construct reaction amplitudes that satisfy fundamental $S$-matrix principles, which allows the use of models that have physical constraints to be used in fitting data. The models are motivated by the isobar model that satisfy unitarity constraints. The model consist of a Deck production amplitude with which final state interactions are constrained by unitarity. We employ the isobar model where two of the pions form a quasi-stable particle. The analysis is performed in the high-energy, single Regge limit. We specifically discuss the examples of the three pion $J^{PC}=2^{-+}$ resonance in the $\\rho\\pi$ and $f_2\\pi$ channels.

  15. Hexagon Wilson loop = six-gluon MHV amplitude

    CERN Document Server

    Drummond, J M; Korchemsky, G P; Sokatchev, E

    2008-01-01

    We compare the two-loop corrections to the finite part of the light-like hexagon Wilson loop with the recent numerical results for the finite part of the MHV six-gluon amplitude in N=4 SYM theory by Bern, Dixon, Kosower, Roiban, Spradlin, Vergu and Volovich (arXiv:0803.1465 [hep-th]) and demonstrate that they coincide within the error bars and, at the same time, they differ from the BDS ansatz by a non-trivial function of (dual) conformal kinematical invariants. This provides strong evidence that the Wilson loop/scattering amplitude duality holds in planar N=4 SYM theory to all loops for an arbitrary number of external particles.

  16. Thermal lens spectrometry: Optimizing amplitude and shortening the transient time

    Science.gov (United States)

    Silva, Rubens; de Araújo, Marcos A. C.; Jali, Pedro; Moreira, Sanclayton G. C.; Alcantara, Petrus; de Oliveira, Paulo C.

    2011-06-01

    Based on a model introduced by Shen et al. for cw laser induced mode-mismatched dual-beam thermal lens spectrometry (TLS), we explore the parameters related with the geometry of the laser beams and the experimental apparatus that influence the amplitude and time evolution of the transient thermal lens (TL) signal. By keeping the sample cell at the minimum waist of the excitation beam, our results show that high amplitude TL signals, very close to the optimized value, combined with short transient times may be obtained by reducing the curvature radius of the probe beam and the distance between the sample cell and the detector. We also derive an expression for the thermal diffusivity which is independent of the excitation laser beam waist, considerably improving the accuracy of the measurements. The sample used in the experiments was oleic acid, which is present in most of the vegetable oils and is very transparent in the visible spectral range.

  17. Thermal lens spectrometry: Optimizing amplitude and shortening the transient time

    Directory of Open Access Journals (Sweden)

    Rubens Silva

    2011-06-01

    Full Text Available Based on a model introduced by Shen et al. for cw laser induced mode-mismatched dual-beam thermal lens spectrometry (TLS, we explore the parameters related with the geometry of the laser beams and the experimental apparatus that influence the amplitude and time evolution of the transient thermal lens (TL signal. By keeping the sample cell at the minimum waist of the excitation beam, our results show that high amplitude TL signals, very close to the optimized value, combined with short transient times may be obtained by reducing the curvature radius of the probe beam and the distance between the sample cell and the detector. We also derive an expression for the thermal diffusivity which is independent of the excitation laser beam waist, considerably improving the accuracy of the measurements. The sample used in the experiments was oleic acid, which is present in most of the vegetable oils and is very transparent in the visible spectral range.

  18. Calculating eustatic amplitude of Middle Permian from reefs

    Institute of Scientific and Technical Information of China (English)

    WU; Yasheng; (吴亚生); FAN; Jiasong; (范嘉松)

    2002-01-01

    Methods for calculating ancient eustatic change amplitudes according to reef fabric- facies are proposed, with a new method for determining sediment-loading subsidence. Compared with methods based on non-reefal deposits, these methods are more accurate in restoration of original sediment thickness, determination of sediment-loading subsidence, as well as restoration of ancient water depth. According to the reef in Guangxi, China, the amplitude of sea-level rise during Middle Permian (Neoschwagerina-Yabeina zone) is 249.5 m. According to the coeval reef of the Guadalupe Mountains, New Mexico and Texas, the coeval sea-level rise is 247 m. With these effective methods available, it is feasible to establish more accurate eustatic curve of Phanerozoic.

  19. Photoinduced Enhancement of the Charge Density Wave Amplitude

    Science.gov (United States)

    Singer, A.; Patel, S. K. K.; Kukreja, R.; Uhlíř, V.; Wingert, J.; Festersen, S.; Zhu, D.; Glownia, J. M.; Lemke, H. T.; Nelson, S.; Kozina, M.; Rossnagel, K.; Bauer, M.; Murphy, B. M.; Magnussen, O. M.; Fullerton, E. E.; Shpyrko, O. G.

    2016-07-01

    Symmetry breaking and the emergence of order is one of the most fascinating phenomena in condensed matter physics. It leads to a plethora of intriguing ground states found in antiferromagnets, Mott insulators, superconductors, and density-wave systems. Exploiting states of matter far from equilibrium can provide even more striking routes to symmetry-lowered, ordered states. Here, we demonstrate for the case of elemental chromium that moderate ultrafast photoexcitation can transiently enhance the charge-density-wave (CDW) amplitude by up to 30% above its equilibrium value, while strong excitations lead to an oscillating, large-amplitude CDW state that persists above the equilibrium transition temperature. Both effects result from dynamic electron-phonon interactions, providing an efficient mechanism to selectively transform a broad excitation of the electronic order into a well-defined, long-lived coherent lattice vibration. This mechanism may be exploited to transiently enhance order parameters in other systems with coupled degrees of freedom.

  20. Multisensory interaction in vibrotactile detection and discrimination of amplitude modulation

    DEFF Research Database (Denmark)

    Teodorescu, Kinneret; Bouchigny, Sylvain; Hoffmann, Pablo F.

    2011-01-01

    Perception of vibration during drilling demands integration of haptic and auditory information with force information. In this study we explored the ability to detect and discriminate changes in vibrotactile stimuli amplitude based either on purely haptic feedback or together with congruent...... synthesized auditory cues in groups of naive subjects and expert surgeons. Our results point toward the complex influence of multimodal experience during vibration perception. First, in naive subjects, we showed that detection and discrimination of amplitude change in complex vibro-tactile stimulus...... is selectively sensitive to combination of modality and previous experience. In the domain of discrimination, our results suggest that bi-modal performance is always better than uni-modal performance regardless of order of experience. Second, experiments with expert surgeons revealed that expertise in complex...