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Sample records for al ecocardiograma doppler

  1. Características cinefluoroscópicas de cinco modelos de prótesis mecánicas monovalvas implantadas en la República Argentina: su valor complementario al ecocardiograma Doppler color

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    Horacio A. Prezioso

    2008-01-01

    Full Text Available La variedad de modelos de prótesis valvulares mecánicas es amplia y su reconocimiento por ecocardiografía es difícil. La cinefluoroscopia (CF puede complementar su identificación y su evaluación.Objetivos1 Describir las características cinefluoroscópicas de cada prótesis para su identificación. 2 Evaluar su función a través de la comparación de los gradientes del eco-Doppler con el ángulo de apertura del disco en la CF. 3 Reconocer la capacidad de la CF para diferenciar prótesis normales de disfuncionantes.Material y métodosSe evaluaron prospectivamente 94 prótesis (53 aórticas y 41 mitrales con ecocardiograma Doppler y cinefluoroscopia.ResultadosCon la CF se logró identificar el 100% de las prótesis. La movilidad de los discos diferenció prótesis normales de disfuncionantes. Según el eco-Doppler, 22 prótesis aórticas y 21 mitrales estudiadas eran normales.La sensibilidad y la especificidad de la fluoroscopia para diferenciar prótesis normales de disfuncionantes fue del 90% y del 81%, respectivamente.Conclusiones1 Mediante la CF se puede identificar cada modelo de prótesis monodisco. 2 La CF permite distinguir entre una prótesis normal y una disfuncionante. 3 La CF es superior al eco- Doppler para evaluar la movilidad de los discos, mientras que el ecocardiograma Doppler permite medir gradientes y áreas y semicuantificar regurgitaciones, por lo que ambos métodos deben considerarse complementarios.

  2. Características cinefluoroscópicas de ocho modelos de prótesis mecánicas bivalvas implantadas en la República Argentina: su valor complementario al ecocardiograma Doppler color

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    Tomás F. Cianciulli

    2008-01-01

    Full Text Available Los diferentes modelos de prótesis valvulares mecánicas son numerosos y su reconocimiento por ecocardiografía es difícil. La cinefluoroscopia (CF puede complementar su identificación y su evaluación.Objetivos1 Describir las características cinefluoroscópicas de cada prótesis para su identificación. 2 Evaluar su función mediante la comparación de los gradientes del eco-Doppler con el ángulo de apertura de los discos basculantes en la CF. 3 Reconocer la capacidad de la CF para diferenciar prótesis normales de prótesis disfuncionantes.Material y métodosSe evaluaron prospectivamente 219 prótesis implantadas en 191 pacientes. Se excluyeron 14 prótesis debido a la coexistencia de disfunción sistólica ventricular izquierda grave. El análisis se realizó sobre 205 prótesis (142 aórticas y 63 mitrales.ResultadosA través de las características del anillo y de los discos, mediante la CF se logró identificar el modelo de la prótesis en el 100% de las válvulas. La movilidad de los discos permitió diferenciar prótesis normales de disfuncionantes (ángulo de apertura 79,3° ± 5,4° versus 58,7° ± 15°, respectivamente. En la CF no se pudieron perfilar los discos y/o el anillo en el 3,9% de las prótesis aórticas y en el 19,2% de las mitrales.De las 142 prótesis aórticas, el eco-Doppler identificó 112 normales y 30 disfuncionantes y de las 63 prótesis mitrales identificó 52 normales y 11 disfuncionantes.Al correlacionar ambos métodos, la sensibilidad, la especificidad, el valor predictivo positivo y el valor predictivo negativo de la fluoroscopia para diferenciar prótesis normales de disfuncionantes fueron del 71%, 93%, 67% y 94%, respectivamente.Conclusiones1 Cada modelo de prótesis valvular tiene características cinefluoroscópicas que permiten su identificación. 2 La cinefluoroscopia evalúa el funcionamiento de las prótesis mecánicas y distingue una normal de una disfuncionante. 3 Cuando hay gradientes altos y

  3. Avaliação do ventrículo direito pelo ecocardiograma com doppler tecidual na embolia pulmonar aguda

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    Ana Clara Tude Rodrigues

    2013-06-01

    Full Text Available FUNDAMENTO: A avaliação da função Ventricular Direita (VD pelo ecocardiograma em pacientes com Tromboembolismo Pulmonar (TEP é complexa, frequentemente qualitativa; o Doppler tecidual tem sido utilizado para avaliação semiquantitativa dessa câmara, com algumas limitações. OBJETIVO: Avaliar a função do VD no TEP pelo ecocardiograma com Doppler tecidual, complementando com o peptídeo atrial natriurético (BNP. MÉTODOS: Foram estudados pacientes com TEP pelo ecocardiograma com Doppler tecidual e BNP até 24 horas do diagnóstico, obtendo-se as velocidades miocárdicas (s', strain, strain rate e índice de performance miocárdica do VD; disfunção do VD foi iagnosticada por hipocinesia da câmara, movimento anormal septal e relação VD/VE >1. De acordo com o BNP os pacientes foram divididos em Grupo I, BNP 50 pg/mL. RESULTADOS: De 118 pacientes, 100 (60 homens, idade = 55 ± 17 anos foram analisados; observou-se disfunção do VD em 28%, mais frequentemente no grupo II (19 vs. 9 pacientes, p < 0,001. O grupo II era mais idoso (64 ± 19 vs. 50 ± 15 anos, apresentava menor velocidade de s' (10,5 ± 3,5 vs. 13,2 ± 3,1 cm/s e maior pressão pulmonar (48 ± 11 vs. 35 ± 11 mmHg, p < 0,001 para todos. O ponto de corte de s' para disfunção do VD foi de 10,8 cm/s (especificidade = 85%, sensibilidade = 54%, com moderada correlação entre o BNP e a onda s'(r = -0,39. CONCLUSÃO: No TEP, a disfunção do VD pelo ecocardiograma se acompanha de elevação do BNP; apesar confirmar adequadamente a presença de disfunção do VD, o Doppler tecidual apresenta sensibilidade limitada para este diagnóstico.

  4. Características cinefluoroscópicas de ocho modelos de prótesis mecánicas bivalvas implantadas en la República Argentina: su valor complementario al ecocardiograma Doppler color

    OpenAIRE

    Tomás F. Cianciulli; Jorge A. Lax (Antagonista); Martín A. Beck; Fausto E. Cerruti; Gerardo E. Gigena; Saccheri, María C; Eduardo Fernández; Adriana N. Dorelle; Prezioso, Horacio A; Luis A. Vidal

    2008-01-01

    Los diferentes modelos de prótesis valvulares mecánicas son numerosos y su reconocimiento por ecocardiografía es difícil. La cinefluoroscopia (CF) puede complementar su identificación y su evaluación.Objetivos1) Describir las características cinefluoroscópicas de cada prótesis para su identificación. 2) Evaluar su función mediante la comparación de los gradientes del eco-Doppler con el ángulo de apertura de los discos basculantes en la CF. 3) Reconocer la capacidad de la CF para diferenciar p...

  5. [Doppler effect on width of characteristic line in plasma induced by pulsed laser ablating Al].

    Science.gov (United States)

    Song, Yi-Zhong; He, An-Zhi

    2005-05-01

    Aluminum (Al) plasma was induced with a pulsed Nd: YAG laser beam ablating Al target in Ar. Time-resolved information of the plasma radiation was taken with time-resolved technique, and the spectra of the radiation were recorded with an optical multi-path analyzer (OMA III ), whereupon, time-resolved spectra of the plasma radiation induced by pulsed laser were acquired. Based on the experiment data, Al resonant double lines, Al I 396.15 nm, Al I 394.40 nm, were respectively fitted with Lorentz, Gauss and their linear integrated function (abbr. Integrated function), whereupon, Lorentz and Gauss elements were separated from the experiment data profile curve. By contrasting Lorentz with Gauss curve separated, it was found that the experiment curve mainly consisted of Lorentz element, a with little Gauss. By contrasting Lorentz with Integrated fitting curve for experiment data, a visual picture of the characteristic lines broadened by Doppler effect was exhibited. According to the visual picture, the increase of full half-high width of the characteristic line broadened by Doppler effect was estimated. It was about 2 x 10(-)3 -8 x 10(-3) nm, approximating the theoretical value 6.7 x 10(-)3 nm. As a result, Doppler effect on the width of characteristic lines in the plasma could be reasonably explained by curve fitting analysis and theoretical calculation.

  6. Defects in Al-3wt%Cu after High-pressure Torsion Studied by Two-dimensional Doppler Broadening Spectroscopy

    Science.gov (United States)

    Parz, P.; Faller, M. J.; Pippan, R.; Puff, W.; Würschum, R.

    High-pressure torsion (HPT) was applied to the structural refinement of an age-hardenable Al-Cu alloy. HPT deformation gives rise to a grain refinement down to sizes of 100 nm and introduces various types of open volume defects. Positron annihilation spectroscopy (PAS), especially the chemical sensitive method of two-dimensional Doppler-broadening spectroscopy (2d-DB), was used for a detailed analysis of the deformation-induced vacancy-type defects and the vacancy-solute interaction. The correlation between microstructure and thermal annealing is discussed. HPT-deformed Al-3wt%Cu shows predominantly deformation-induced positron traps with a strongly reduced copper environment in comparison with the undeformed sample.

  7. Doppler obstétrico posterior al uso de Betametasona para la maduración pulmonar fetal

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    Keibis Jiménez Castillejo

    2014-04-01

    Full Text Available El objetivo de la investigación fue determinar las modificaciones del Doppler obstétrico posterior al uso de betametasona para la maduración pulmonar fetal. Se realizó una investigación de tipo explicativa, prospectiva y longitudinal con un diseño cuasi-experimental y una muestra no probabilística intencional de 106 pacientes que acudieron a la consulta Pre-natal de Alto Riesgo del Hospital Central “Dr. Urquinaona". Una vez seleccionadas las pacientes se les administró inyecciones intramusculares de betametasona (12 mg/día por dos días consecutivos. Se realizaron las mediciones de índice de pulsatilidad e índice de resistencia en las arterias uterinas, umbilical y cerebral media fetal. No se encontraron diferencias estadísticamente significativas entre las determinaciones del índice de pulsatilidad y de resistencia de las arterias uterinas (p = ns. Se observaron disminuciones significativas en el índice de pulsatilidad y de resistencia de la arteria umbilical en la segunda y tercera medición al compararla con la medición inicial (p < 0,05. Se encontraron disminuciones en el índice de pulsatilidad de la arteria cerebral media fetal en ambos periodos de estudio comparado con los valores iniciales y solo se observó una disminución significativa del índice de resistencia en la segunda medición (p < 0,05. Se concluye que el uso de betametasona para la maduración pulmonar fetal produce modificaciones en la evaluación Doppler de las arterias umbilical y cerebral media fetal. Obstetric doppler after use of Betamethasone for fetal lung maturation Abstract The objective of research was to determine modifications of obstetric Doppler after to fetal lung maturation. An explicative, prospective and longitudinal research was done with a quasi-experimental design and an intentional non probabilistic sample of 106 patients who assisted to High Risk Antenatal Consult at Hospital Central “Dr. Urquinaona". Once patients were selected

  8. Papel do ecocardiograma na avaliação ventricular do coração transplantado versus rejeição cardíaca

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    Gabriel Antonio Stanisci Miguel

    2012-11-01

    Full Text Available FUNDAMENTO: O Transplante Cardíaco (TC é uma alternativa para os indivíduos com doença cardíaca terminal. Na evolução pós-transplante, a ocorrência de episódios de Rejeição Cardíaca (RC é evento frequente que aumenta a morbimortalidade, sendo necessário o emprego de exame não invasivo com boa acurácia para seu diagnóstico, pois a Biópsia Endomiocárdica (BEM não é um procedimento isento de complicações. OBJETIVO: Comparar parâmetros obtidos com o princípio Doppler, entre os pacientes transplantados com RC (TX1 e os pacientes transplantados sem rejeição (TX0; utilizando como referência o Grupo Controle (GC e observando o comportamento da função sistodiastólica ventricular esquerda expressa por meio do Índice de Performance Miocárdica (IPM. MÉTODOS: Foram realizados ecocardiogramas transtorácicos no período de janeiro de 2006 a janeiro de 2008, para a avaliação prospectiva de 47 pacientes, subdivididos em GC (36,2%, TX0 (38,3% e TX1 (25,5%, comparando-se o IPM entre eles. Para a análise dos dados foram realizados os testes exato de Fisher e o não paramétrico de Kruskal-Wallis, ambos com nível de significância de 5%. RESULTADOS: Os grupos não diferiram em relação a idade, peso, altura e superfície corpórea. Quando comparado ao GC, TX0 e TX1 apresentaram alteração da função sistodiastólica ventricular esquerda, expressa como aumento do IPM, que foi mais intenso no TX1 [0,38 (0,29 - 0,44 X 0,47 (0,43 - 0,56 X 0,58 (0,52 - 0,74 p < 0,001]. CONCLUSÃO: O ecocardiograma mostrou-se como exame de boa acurácia na detecção das alterações da função sistodiastólica do coração transplantado; entretanto, não foi confiável como método substituto da BEM para o diagnóstico seguro de RC.

  9. Doppler de las arterias pulmonares fetales posterior al uso de betametasona para la maduración pulmonar (Fetal lung arteries Doppler after to use of betamethasone for lung maturation

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    Keibis Jiménez Castillejo

    2014-06-01

    Full Text Available Resumen (español El objetivo de la investigación fue determinar las modificaciones del Doppler de las arterias pulmonares fetales posterior al uso de betametasona para la maduración pulmonar. Se realizó una investigación de tipo explicativa, prospectiva y longitudinal con un diseño cuasi-experimental y una muestra no probabilística intencional de 106 pacientes que acudieron a la consulta Pre-natal de Alto Riesgo del Hospital Central “Dr. Urquinaona". Una vez seleccionadas las pacientes se les administró inyecciones intramusculares de betametasona (12 mg/día por dos días consecutivos. Se realizaron las mediciones de índice de pulsatilidad, índice de resistencia y relación sistólico / diastólica de las arterias pulmonares fetales. Se observó disminución significativa de los valores promedio del índice de pulsatilidad en la segunda medición comparado con la medición inicial (p < 0,05. Sin embargo, el promedio de la tercera medición no mostró diferencia significativas con los valores iniciales (p = ns. El índice de resistencia disminuyó en la segunda medición para luego aumentar en la tercera medición comparado con el valor inicial (p < 0,05 para las dos mediciones. El valor promedio de la relación sistólico / diastólica presentó disminución significativa durante la segunda medición para luego presentar un aumento significativo al momento de la tercera medición comparado con el valor inicial (p < 0,05 para las dos mediciones. Se concluye que el uso de betametasona para la inducción de la maduración pulmonar produce modificaciones en las mediciones Doppler de las arterias pulmonares fetales. Abstract (english The objective of research was to determine Doppler modifications of fetal pulmonary arteries after use of betamethasone for lung maturation. An explicative, prospective and longitudinal research was done with a quasi-experimental design and an intentional non-probabilistic sample of 106 patients who assisted

  10. Evaluación de la función diastólica en la enfermedad de chagas mediante doppler tisular pulsado

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    R. A. Migliore

    2003-12-01

    Full Text Available En la etapa indeterminada de la enfermedad de Chagas las alteraciones de la función diastólica preceden a las de la función sistólica. El Doppler tisular pulsado es una nueva técnica no invasiva que permite analizar la función diastólica mediante el registro de la velocidad de estiramiento miocárdico en el eje longitudinal. Con el objetivo de evaluar la función diastólica en la enfermedad de Chagas mediante Doppler tisular pulsado fueron estudiados con ecocardiograma y Doppler 51 pacientes con serología positiva para enfermedad de Chagas (48 ± 12 años y 24 individuos normales (47 ± 15 años como grupo control. De acuerdo al patrón del flujo mitral y de vena pulmonar los pacientes con enfermedad de Chagas fueron divididos en 2 grupos: restrictivo (17 pacientes y no restrictivo (34 pacientes. La velocidad pico de la onda E del anillo lateral mitral estuvo disminuida en los pacientes con patrón no restrictivo y restrictivo (0.13 ± 0.04 m/seg, 0.11 ± 0.05 m/seg respectivamente con respecto al grupo control (0.18 ± 0.07 m/seg, pDiastolic function is early involved during the undetermined form of Chagas disease. Pulsed Doppler tissue imaging is a new technique to evaluate diastolic function by mean of the record of myocardial velocities in the longitudinal axis. With the purpose to evaluate diastolic function by pulsed Doppler tissue imaging in patients with Chagas disease, we studied with Doppler echocardiography 51 patients (age average 48 ± 12 years and 24 normal subjects (age average 47 ± 15 years as a control group. Patients were divided in two groups according to the pattern of mitral and pulmonary vein flow: restrictive (17 patients and no restrictive (35 patients. Peak velocity of E wave of the lateral mitral annulus was diminished in no restrictive and restrictive patients (0.13 ± 0.04 m/s, 0.11 ± 0.05 m/s respectively in regard to control group (0.18 ± 0.07 m/s, p<0.01. Pulsed Doppler tissue imaging was useful in the

  11. Doppler Tomography

    CERN Document Server

    Marsh, T R

    2000-01-01

    I review the method of Doppler tomography which translates binary-star line profiles taken at a series of orbital phases into a distribution of emission over the binary. I begin with a discussion of the basic principles behind Doppler tomography, including a comparison of the relative merits of maximum entropy regularisation versus filtered back-projection for implementing the inversion. Following this I discuss the issue of noise in Doppler images and possible methods for coping with it. Then I move on to look at the results of Doppler Tomography applied to cataclysmic variable stars. Outstanding successes to date are the discovery of two-arm spiral shocks in cataclysmic variable accretion discs and the probing of the stream/magnetospheric interaction in magnetic cataclysmic variable stars. Doppler tomography has also told us much about the stream/disc interaction in non-magnetic systems and the irradiation of the secondary star in all systems. The latter indirectly reveals such effects as shadowing by the a...

  12. Doppler imaging

    Energy Technology Data Exchange (ETDEWEB)

    Piskunov, N [Department of Physics and Astronomy, Uppsala University, Box 515, S-75120 Uppsala (Sweden)], E-mail: piskunov@fysast.uu.se

    2008-12-15

    In this paper, I present a short review of the history and modern status of Doppler imaging techniques, highlighting their dependence on the knowledge of the fundamental stellar parameters, the quality of stellar atmospheric models and the accuracy of spectral synthesis.

  13. Síndrome do coração partido (Síndrome de Takotsubo induzida por ecocardiograma de estresse com dobutamina Síndrome del corazón roto (síndrome de Tako-Tsubo inducido por ecocardiograma de esfuerzo con dobutamina Dobutamine stress echocardiography-induced broken heart syndrome (Takotsubo Syndrome

    Directory of Open Access Journals (Sweden)

    Francisco Juarez Cruz de Vasconcelos Filho

    2009-07-01

    Full Text Available Relatamos um caso de síndrome de Takotsubo induzida por ecocardiograma de estresse com dobutamina em uma paciente de 76 anos, hipertensa com queixas clínicas de dor precordial, em consulta cardiológica eletiva. Para exclusão de dor torácica de etiologia coronariana foi solicitado ecocardiograma de estresse com dobutamina. O exame foi realizado e, no pico do esforço máximo, o ecocardiograma mostrou acinesia apical com o eletrocardiograma mostrando supradesnivelamento do segmento ST em D1, AVL e V2. A paciente foi internada e submetida a coronariografia, que mostrou coronárias normais e VE com balonamento apical. A paciente evoluiu estável com reversão do quadro 21 dias após o quadro inicial.Relatamos un caso de síndrome de Tako-Tsubo inducido por ecocardiograma de esfuerzo con dobutamina en una paciente de 76 años, hipertensa con quejas clínicas de dolor precordial, en consulta cardiológica electiva. Para exclusión de dolor torácico de etiología coronaria se solicitó ecocardiograma de esfuerzo con dobutamina. El examen fue realizado, y en el pico de esfuerzo máximo, el ecocardiograma mostró acinesia apical con el electrocardiograma mostrando supradesnivel del segmento ST en D1, AVL y V2. La paciente fue internada y sometida a coronariografía, que mostró coronarias normales y VI con abombamiento apical. La paciente evolucionó estable con reversión del cuadro 21 días después del cuadro inicial.We report a case of dobutamine stress echocardiography-induced Takotsubo syndrome in a 76-year-old hypertensive patient with clinical complaints of chest pain in an elective visit to the cardiologist. Dobutamine-stress-echocardiography was requested to rule out chest pain of coronary origin. During the test, at peak exercise, echocardiogram showed apical akinesia and electrocardiogram showed ST-segment elevation in D1, AVL, and V2. The patient was hospitalized and underwent coronary angiography, which showed normal coronary arteries

  14. The doppler ultrasound. La ecografia Doppler

    Energy Technology Data Exchange (ETDEWEB)

    Contreras Cecilia, E.; Lozano Setien, E.; Hernandez Montero, J.; Ganado Diaz, T.; Jorquera Moya, M.; Blasco Pascual, E. (Hospital Universitario San Carlos. Madrid (Spain))

    1994-01-01

    The discovery and development of Doppler ultrasound has had a great influence on Medical practice since it allows the noninvasive study of vascular pathology, both arterial and venous, as well as the flow patterns of the different parenchyma. This article deals with the principles, limitations and interpretation of the Doppler signal, as well as the different Doppler ultrasound systems routinely employed in Medicine.

  15. Utilidad del ecocardiograma transesofágico en el intra y post operatorio de cirugía cardíaca

    Directory of Open Access Journals (Sweden)

    Miguel Tibaldi

    2001-04-01

    Full Text Available Objetivos: Analizar la utilidad del Ecocardiograma Transesofágico (ETE en la asistencia al cirujano y al cardiólogo recuperador para la toma de decisiones. Material y Métodos: Se analizaron retrospectivamente 147 pacientes (p que requirieron ETE, 110 p (75% eran hombres con una edad media de 63 años (21-88. Los procedimientos quirúrgicos realizados fueron: By Pass Ao. Co: 70p, reemplazo valvular (RV: 50p, Combinados: 5p, disección aórtica 8p, transplante cardíaco 5p, cierre de CIV: 2 p, aneurismectomía: 2p, extirpación de mixomas: 2p, miectomía: 1p, tromboendarterectomía: 1p y bicavo pulmonar anastomosis: 1p. Se dividió la muestra en 2 grupos: Grupo A: ETE intraoperatorio 104p (70.7% y Grupo B ETE postoperatorio 43p (29.3%. Las indicaciones fueron: Grupo A: p con dificultad para retirar de circulación extracorpórea (CEC (A1 49p, y p para control de procedimiento (pr (A2 55p, 24 de los cuales con plástica valvular (plv. Grupo B: p con bajo débito (B1 25p de los cuales 12 presentaban signos de taponamiento (t. Y p con signos de isquemia perioperatoria 18p. Se utilizó el test X2 para comparar variables categóricas. Resultados: Grupo A1: se detectó alteraciones de la motilidad global o regional en 41p, disfunción protésica en 4p, insuficiencia mitral 1p y obstrucción medio ventricular en 3p. Grupo A2: el ETE indicó 5 RV post plv y 4 RV no programados controlando correctamente el resto de los pr. Grupo B1: de los 12 p con signos de t, el ETE lo confirmó en 6 (50%, y de los restantes p con Bajo Gasto Cardíaco (BGC detectó t en 3p. Grupo B2: en 15p se detectó trastornos segmentarios de la motilidad requiriendo nueva revascularización. Se consideró como parámetro de utilidad del ETE a los hallazgos que condicionaron un cambio de conducta, presentando una utilidad del 67% en ésta muestra. La mortalidad en el grupo de pacientes en los cuales el ETE produjo un cambio de conducta (98p, obitaron 10 (10% y en los que no sugiri

  16. Differential doppler heterodyning technique

    DEFF Research Database (Denmark)

    Lading, Lars

    1971-01-01

    Measuring velocity without disturbing the moving object is possible by use of the laser doppler heterodyning technique. Theoretical considerations on the doppler shift show that the antenna property of the photodetector can solve an apparent conflict between two different ways of calculating the ...

  17. Ultrasonic colour Doppler imaging

    DEFF Research Database (Denmark)

    Evans, David H.; Jensen, Jørgen Arendt; Nielsen, Michael Bachmann

    2011-01-01

    Ultrasonic colour Doppler is an imaging technique that combines anatomical information derived using ultrasonic pulse-echo techniques with velocity information derived using ultrasonic Doppler techniques to generate colour-coded maps of tissue velocity superimposed on grey-scale images of tissue ...

  18. Ultrasonic colour Doppler imaging

    DEFF Research Database (Denmark)

    Evans, David H; Jensen, Jørgen Arendt; Nielsen, Michael Bachmann

    2011-01-01

    anatomy. The most common use of the technique is to image the movement of blood through the heart, arteries and veins, but it may also be used to image the motion of solid tissues such as the heart walls. Colour Doppler imaging is now provided on almost all commercial ultrasound machines, and has been......Ultrasonic colour Doppler is an imaging technique that combines anatomical information derived using ultrasonic pulse-echo techniques with velocity information derived using ultrasonic Doppler techniques to generate colour-coded maps of tissue velocity superimposed on grey-scale images of tissue...... vectors. This review briefly introduces the principles behind colour Doppler imaging and describes some clinical applications. It then describes the basic components of conventional colour Doppler systems and the methods used to derive velocity information from the ultrasound signal. Next, a number of new...

  19. Pulse subtraction Doppler

    Science.gov (United States)

    Mahue, Veronique; Mari, Jean Martial; Eckersley, Robert J.; Caro, Colin G.; Tang, Meng-Xing

    2010-01-01

    Recent advances have demonstrated the feasibility of molecular imaging using targeted microbubbles and ultrasound. One technical challenge is to selectively detect attached bubbles from those freely flowing bubbles and surrounding tissue. Pulse Inversion Doppler is an imaging technique enabling the selective detection of both static and moving ultrasound contrast agents: linear scatterers generate a single band Doppler spectrum, while non-linear scatterers generate a double band spectrum, one being uniquely correlated with the presence of contrast agents and non-linear tissue signals. We demonstrate that similar spectrums, and thus the same discrimination, can be obtained through a Doppler implementation of Pulse Subtraction. This is achieved by reconstructing a virtual echo using the echo generated from a short pulse transmission. Moreover by subtracting from this virtual echo the one generated from a longer pulse transmission, it is possible to fully suppress the echo from linear scatterers, while for non-linear scatterers, a signal will remain, allowing classical agent detection. Simulations of a single moving microbubble and a moving linear scatterer subject to these pulses show that when the virtual echo and the long pulse echo are used to perform pulsed Doppler, the power Doppler spectrum allows separation of linear and non-linear moving scattering. Similar results are obtained on experimental data acquired on a flow containing either microbubble contrast agents or linear blood mimicking fluid. This new Doppler method constitutes an alternative to Pulse Inversion Doppler and preliminary results suggest that similar dual band spectrums could be obtained by the combination of any non-linear detection technique with Doppler demodulation.

  20. Steerable Doppler transducer probes

    Energy Technology Data Exchange (ETDEWEB)

    Fidel, H.F.; Greenwood, D.L.

    1986-07-22

    An ultrasonic diagnostic probe is described which is capable of performing ultrasonic imaging and Doppler measurement consisting of: a hollow case having an acoustic window which passes ultrasonic energy and including chamber means for containing fluid located within the hollow case and adjacent to a portion of the acoustic window; imaging transducer means, located in the hollow case and outside the fluid chamber means, and oriented to direct ultrasonic energy through the acoustic window toward an area which is to be imaged; Doppler transducer means, located in the hollow case within the fluid chamber means, and movably oriented to direct Doppler signals through the acoustic window toward the imaged area; means located within the fluid chamber means and externally controlled for controllably moving the Doppler transducer means to select one of a plurality of axes in the imaged area along which the Doppler signals are to be directed; and means, located external to the fluid chamber means and responsive to the means for moving, for providing an indication signal for identifying the selected axis.

  1. Doppler cooling a microsphere

    CERN Document Server

    Barker, P F

    2010-01-01

    Doppler cooling the center-of-mass motion of an optically levitated microsphere via the velocity dependent scattering force from narrow whispering gallery mode (WGM) resonances is described. Light that is red detuned from the WGM resonance can be used to damp the center-of-mass motion in a process analogous to the Doppler cooling of atoms. Leakage of photons out of the microsphere when the incident field is near resonant with the narrow WGM resonance acts to damp the motion of the sphere. The scattering force is not limited by saturation, but can be controlled by the incident power. Cooling times on the order of seconds are calculated for a 20 micron diameter silica microsphere trapped within optical tweezers, with a Doppler temperature limit in the microKelvin regime.

  2. Pulse Doppler radar

    CERN Document Server

    Alabaster, Clive

    2012-01-01

    This book is a practitioner's guide to all aspects of pulse Doppler radar. It concentrates on airborne military radar systems since they are the most used, most complex, and most interesting of the pulse Doppler radars; however, ground-based and non-military systems are also included. It covers the fundamental science, signal processing, hardware issues, systems design and case studies of typical systems. It will be a useful resource for engineers of all types (hardware, software and systems), academics, post-graduate students, scientists in radar and radar electronic warfare sectors and milit

  3. Doppler radar physiological sensing

    CERN Document Server

    Lubecke, Victor M; Droitcour, Amy D; Park, Byung-Kwon; Singh, Aditya

    2016-01-01

    Presents a comprehensive description of the theory and practical implementation of Doppler radar-based physiological monitoring. This book includes an overview of current physiological monitoring techniques and explains the fundamental technology used in remote non-contact monitoring methods. Basic radio wave propagation and radar principles are introduced along with the fundamentals of physiological motion and measurement. Specific design and implementation considerations for physiological monitoring radar systems are then discussed in detail. The authors address current research and commercial development of Doppler radar based physiological monitoring for healthcare and other applications.

  4. The duplex-Doppler colour echography of the scrotum and testicles in adults and boys. II. the contribution of the urgent study of acute scrotum symptoms; Ecografia duples-Doppler color del escroto y el testiculo en el adulto y el nino. II. Aportacion al estudio urgente del escroto agudo

    Energy Technology Data Exchange (ETDEWEB)

    Rangel-Villalobos, E.; Jimenez-Castellanos, R.; Bustos, C.; Linares, A.; Gonzalez-Prada, F. [Hospital Universitario Virgen Macarena. Sevilla (Spain)

    1999-07-01

    To analyse the findings, contributions and limitations of the Doppler echography for the urgent study of acute scrotum symptoms, both in adults and in boys. 60 patients (22 adults and 38 boys) with acute scrotal symptomatology were examined using B mode echography, followed by a colour duplex-Doppler (CDD) echography with a lineal 7.5 MHz transducer. We compared the findings obtained with those of the healthy contralateral testicle and with surgery or clinical-echographical evolution. The most common pathology was inflammation (27%) followed by ischemic (24%) and traumatic (17%). 12% of the patients had miscellaneous conditions. To conclude, in 20% of the cases the B mode and the Doppler examination was normal, the symptoms were resolved spontaneously. After carrying out the CDD only 14 (23%) of the cases needed immediate surgery and 3 (5%) delayed surgery, the remaining 43 (72%) patients responded to the traditional treatment. The CDD allows for a safe, quick and harmless diagnosis in practically all the acute scrotum cases, for both adults and boys. Its limitations in pre-puberty patients or in cases that were atypical are overcome when put in the hands of an expert radiologist, as they need a longer exploration time and suitable Doppler equipment. The main contribution to the urgent diagnosis of acute scrotum symptoms is that it accurately establishes which patients should be chosen for immediate surgery. (Author) 33 refs.

  5. The Doppler Pendulum Experiment

    Science.gov (United States)

    Lee, C. K.; Wong, H. K.

    2011-01-01

    An experiment to verify the Doppler effect of sound waves is described. An ultrasonic source is mounted at the end of a simple pendulum. As the pendulum swings, the rapid change of frequency can be recorded by a stationary receiver using a simple frequency-to-voltage converter. The experimental results are in close agreement with the Doppler…

  6. Scanning laser Doppler vibrometry

    DEFF Research Database (Denmark)

    Brøns, Marie; Thomsen, Jon Juel

    With a Scanning Laser Doppler Vibrometer (SLDV) a vibrating surface is automatically scanned over predefined grid points, and data processed for displaying vibration properties like mode shapes, natural frequencies, damping ratios, and operational deflection shapes. Our SLDV – a PSV-500H from...

  7. Endocarditis trombótica no bacteriana bivalvular asociada a cáncer y ecocardiograma transesofágico Bivalvular non bacterial thrombotic endocarditis associated with cancer and transesophageal echocardiography

    Directory of Open Access Journals (Sweden)

    Marcelo Zylberman

    2006-06-01

    Full Text Available La endocarditis trombótica no bacteriana es la causa más frecuente de accidente cerebrovascular isquémico en pacientes con cáncer. En estos pacientes se hallaron vegetaciones valvulares hasta en el 9% de las autopsias. Sin embargo, la afección bivalvular es poco frecuente, observándose en el 9% de las endocarditis trombóticas. Se presenta una paciente con cáncer de ovario que presentó afasia e imágenes compatibles con isquemia cerebral. El ecocardiograma transtorácico fue normal. El ecocardiograma transesofágico evidenció vegetaciones en las válvulas aórtica y mitral. Se enfatiza la importancia de sospechar endocarditis trombótica no bacteriana en enfermos con cáncer y embolismo sistémico y en la escasa frecuencia de afección bivalvular.Non bacterial thrombotic endocarditis is the most frequent cause of ischemic stroke in cancer patients. Up to 9% of autopsies of cancer patients show non infectious valvular masses. However, bivalvular involvement is not frequently occurring in 9% of non bacterial thrombotic endocarditis. We report a patient with ovarian cancer who presented aphasia. The MRI was compatible with cerebral ischemia. The transthoracic echocardiogram was normal and a transesophageal echocardiogram showed vegetations in aortic and mitral valves. We emphasize the importance of suspecting non bacterial thrombotic endocarditis in patients with cancer and systemic embolism and the low frequency of bivalvular involvement.

  8. Laser Doppler flowmetry imaging

    Science.gov (United States)

    Nilsson, Gert E.; Wardell, Karin

    1994-02-01

    A laser Doppler perfusion imager has been developed that makes possible mapping of tissue blood flow over surfaces with extensions up to about 12 cm X 12 cm. The He-Ne laser beam scans the tissue under study throughout 4096 measurement sites. A fraction of the backscattered and Doppler broadened light is detected by a photo diode positioned about 20 cm above the tissue surface. After processing, a signal that scales linearly with perfusion is stored in a computer and a color coded image of the spatial tissue perfusion is shown on a monitor. A full format scan is completed in about 4.5 minutes. Algorithms for calculating perfusion profiles and averages as well as substraction of one image from another, form an integral part of the system data analysis software. The perfusion images can also be exported to other software packages for further processing and analysis.

  9. Scanning laser Doppler vibrometry

    OpenAIRE

    2016-01-01

    With a Scanning Laser Doppler Vibrometer (SLDV) a vibrating surface is automatically scanned over predefined grid points, and data processed for displaying vibration properties like mode shapes, natural frequencies, damping ratios, and operational deflection shapes. Our SLDV – a PSV-500H from Polytec Inc. – was acquired and put to operation in October 2014, paid by a sub-donation of DKK 1,5 mill. of the total VILLUM CASMaT grant. Opening possibilities of measuring complicated vibration shapes...

  10. Laser double Doppler flowmeter

    Science.gov (United States)

    Poffo, L.; Goujon, J.-M.; Le Page, R.; Lemaitre, J.; Guendouz, M.; Lorrain, N.; Bosc, D.

    2014-05-01

    The Laser Doppler flowmetry (LDF) is a non-invasive method for estimating the tissular blood flow and speed at a microscopic scale (microcirculation). It is used for medical research as well as for the diagnosis of diseases related to circulatory system tissues and organs including the issues of microvascular flow (perfusion). It is based on the Doppler effect, created by the interaction between the laser light and tissues. LDF measures the mean blood flow in a volume formed by the single laser beam, that penetrate into the skin. The size of this measurement volume is crucial and depends on skin absorption, and is not directly reachable. Therefore, current developments of the LDF are focused on the use of always more complex and sophisticated signal processing methods. On the other hand, laser Double Doppler Flowmeter (FL2D) proposes to use two laser beams to generate the measurement volume. This volume would be perfectly stable and localized at the intersection of the two laser beams. With FL2D we will be able to determine the absolute blood flow of a specific artery. One aimed application would be to help clinical physicians in health care units.

  11. Rubidium atomic line filtered (RALF) Doppler velocimetry

    Science.gov (United States)

    Fajardo, Mario E.; Molek, Christopher D.; Vesely, Annamaria L.

    2017-01-01

    We report recent improvements to our Rubidium Atomic Line Filtered (RALF) Doppler velocimetry apparatus [M.E. Fajardo, C.D. Molek, and A.L. Vesely, J. Appl. Phys. 118, 144901 (2015)]. RALF is a high-velocity and high-acceleration adaptation of the Doppler Global Velocimetry method for measuring multi-dimensional velocity vector flow fields, which was developed in the 1990s by aerodynamics researchers [H. Komine, U.S. Patent #4,919,536]. Laser velocimetry techniques in common use within the shock physics community (e.g. VISAR, Fabry-Pérot, PDV) decode the Doppler shift of light reflected from a moving surface via interference phenomena. In contrast, RALF employs a completely different physical principle: the frequency-dependent near-resonant optical transmission of a Rb/N2 gas cell, to encode the Doppler shift of reflected λ0 ≈ 780.24 nm light directly onto the transmitted light intensity. Thus, RALF is insensitive to minor changes to the optical pathlengths and transit times of the Doppler shifted light, which promises a number of practical advantages in imaging velocimetry applications. The single-point RALF proof-of-concept apparatus described here is fiber optic based, and our most recent modifications include the incorporation of a larger bandwidth detection system, and a second 780 nm laser for simultaneous upshifted-PDV (UPDV) measurements. We report results for the laser driven launch of a 10-μm-thick aluminum flyer which show good agreement between the RALF and UPDV velocity profiles, within the limitations of the admittedly poor signal:noise ratio (SNR) RALF data.

  12. Correlation between Spectral Index and Doppler Factor for a Sample of Fermi Blazars

    Indian Academy of Sciences (India)

    J. Tao; J. H. Fan; H. J. Pan; D. X. Wu; S. H. Li

    2014-09-01

    Relativistic beaming effect is important for blazars. In a very recent work, -ray Doppler factors were calculated for a sample of Fermi blazars (Fan et al. 2013). In this work, we investigated the correlation between the Doppler factor and the effective spectral index, 4OX, and found an anticorrelation between them.

  13. Comparisons between PW Doppler system and enhanced FM Doppler system

    DEFF Research Database (Denmark)

    Wilhjelm, Jens E.; Pedersen, P. C.

    1995-01-01

    This paper presents a new implementation of an echo-ranging FM Doppler system with improved performance, relative to the FM Doppler system reported previously. The use of long sweeps provides a significant reduction in peak to average power ratio compared to pulsed wave (PW) emission. A PW Doppler...... system exploits the direct relationship between arrival time of the received signal and range from the transducer. In the FM Doppler systems, a similar relationship exists in the spectral domain of the demodulated received signals, so that range is represented by frequency. Thus, a shift in location...... of moving scatterers between consecutive emissions corresponds to a frequency shift in the spectral signature. The improvement relative to the earlier version of the FM Doppler system is attained by utilizing cross-correlation of real spectra rather than of magnitude spectra for assessing flow velocity...

  14. ANL Doppler flowmeter

    Science.gov (United States)

    Karplus, H. B.; Raptis, A. C.; Lee, S.; Simpson, T.

    1985-10-01

    A flowmeter has been developed for measuring flow velocity in hot slurries. The flowmeter works on an ultrasonic Doppler principle in which ultrasound is injected into the flowing fluid through the solid pipe wall. Isolating waveguides separate the hot pipe from conventional ultrasonic transducers. Special clamp-on high-temperature transducers also can be adapted to work well in this application. Typical flows in pilot plants were found to be laminar, giving rise to broad-band Doppler spectra. A special circuit based on a servomechanism sensor was devised to determine the frequency average of such a broad spectrum. The device was tested at different pilot plants. Slurries with particulates greater than 70 microns (0.003 in.) yielded good signals, but slurries with extremely fine particulates were unpredictable. Small bubbles can replace the coarse particles to provide a good signal if there are not too many. Successful operation with very fine particulate slurries may have been enhanced by the presence of microbubbles.

  15. Laser Doppler Imaging of Microflow

    CERN Document Server

    Gross, Michel; Leng, Jacques

    2013-01-01

    We report a pilot study with a wide-field laser Doppler detection scheme used to perform laser Doppler anemometry and imaging of particle seeded microflow. The optical field carrying the local scatterers (particles) dynamic state, as a consequence of momentum transfer at each scattering event, is analyzed in the temporal frequencies domain. The setup is based on heterodyne digital holography, which is used to map the scattered field in the object plane at a tunable frequency with a multipixel detector. We show that wide-field heterodyne laser Doppler imaging can be used for quantitative microflow diagnosis; in the presented study, maps of the first-order moment of the Doppler frequency shift are used as a quantitative and directional estimator of the Doppler signature of particles velocity.

  16. Doppler characteristics of sea clutter.

    Energy Technology Data Exchange (ETDEWEB)

    Raynal, Ann Marie; Doerry, Armin Walter

    2010-06-01

    Doppler radars can distinguish targets from clutter if the target's velocity along the radar line of sight is beyond that of the clutter. Some targets of interest may have a Doppler shift similar to that of clutter. The nature of sea clutter is different in the clutter and exo-clutter regions. This behavior requires special consideration regarding where a radar can expect to find sea-clutter returns in Doppler space and what detection algorithms are most appropriate to help mitigate false alarms and increase probability of detection of a target. This paper studies the existing state-of-the-art in the understanding of Doppler characteristics of sea clutter and scattering from the ocean to better understand the design and performance choices of a radar in differentiating targets from clutter under prevailing sea conditions.

  17. Novel instantaneous laser Doppler velocimeter.

    Science.gov (United States)

    Avidor, J M

    1974-02-01

    A laser Doppler velocimeter capable of directly measuring instantaneous velocities is described. The new LDV uses a novel detection technique based on the utilization of a static slightly defocused spherical Fabry-Perot interferometer used in conjunction with a special mask for the detection of instantaneous Doppler frequency shifts. The essential characteristics of this LDV are discussed, and such a system recently developed is described. Results of turbulent flow measurements show good agreement with data obtained using hot wire anemometry.

  18. Doppler-like effect and doubtful expansion of universe

    CERN Document Server

    Szaraniec, E

    2003-01-01

    The distance contraction, as observed in electrical soundings over horizontally stratified earth (static system), is identified as a counterpart of Doppler shift in dynamical systems. Identification of Doppler-like effect in a stock-still systems makes it possible to give an al-ternative answer to the question about an effective cause of the Doppler shift, which sounds: the inhomogeneities. This answer opens different static as well as kinematic possibilities, which challenge established theories of expanding universe and energizing big bang.The energy propagating in stratified universe of layers exhibits a shift which could be at-tributed not only to the expansion (Hubble's theory) but alternatively to fluctuations in material properties (inhomogeneities).

  19. Color Doppler US in extra-articular rheumatoid arthritis. Early results; L'eco Doppler nell'artrite reumatoide con localizzazione extra-articolare: esperienza preliminare

    Energy Technology Data Exchange (ETDEWEB)

    Midiri, M. [Bari Politcenico, Bari (Italy). Ist. di Radiologia; Iovane, A.; Finazzo, M.; Brancatelli, G.; Gallo, C.; Lagalla, R. [Palermo Politecnico Universitario Paolo Giaccone, Palermo (Italy). Ist. di Radiologia

    1999-09-01

    The paper investigates the role of color and power Doppler imaging in staging extra-articular involvement, monitoring local inflammatory changes and drug treatment response. [Italian] Scopo del lavoro e' quello di analizzare l'introduzione dell'ecografia con color power Doppler, che offre possibilita' di integrazione dell'ecografia, con particolare riferimento alla dimostrazione del grado di coinvolgimento extra-articolare, allo stato evolutivo, della flogrosi locale e alla risposta al trattamento farmacologico.

  20. General principles of carotid Doppler ultrasonography

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Whal [Dept. of Radiology, Seoul National University College of Medicine, Seoul (Korea, Republic of)

    2014-03-15

    Carotid Doppler ultrasonography is a popular tool for evaluating atherosclerosis of the carotid artery. Its two-dimensional gray scale can be used for measuring the intima-media thickness, which is very good biomarker for atherosclerosis and can aid in plaque characterization. The plaque morphology is related to the risk of stroke. The ulceration of plaque is also known as one of the strong predictors of future embolic event risk. Color Doppler ultrasonography and pulse Doppler ultrasonography have been used for detecting carotid artery stenosis. Doppler ultrasonography has unique physical properties. The operator should be familiar with the physics and other parameters of Doppler ultrasonography to perform optimal Doppler ultrasonography studies.

  1. Papel do ecocardiograma na avaliação ventricular do coração transplantado versus rejeição cardíaca Role of echocardiography in the ventricular assessment of the transplanted heart versus heart rejection

    Directory of Open Access Journals (Sweden)

    Gabriel Antonio Stanisci Miguel

    2012-11-01

    Full Text Available FUNDAMENTO: O Transplante Cardíaco (TC é uma alternativa para os indivíduos com doença cardíaca terminal. Na evolução pós-transplante, a ocorrência de episódios de Rejeição Cardíaca (RC é evento frequente que aumenta a morbimortalidade, sendo necessário o emprego de exame não invasivo com boa acurácia para seu diagnóstico, pois a Biópsia Endomiocárdica (BEM não é um procedimento isento de complicações. OBJETIVO: Comparar parâmetros obtidos com o princípio Doppler, entre os pacientes transplantados com RC (TX1 e os pacientes transplantados sem rejeição (TX0; utilizando como referência o Grupo Controle (GC e observando o comportamento da função sistodiastólica ventricular esquerda expressa por meio do Índice de Performance Miocárdica (IPM. MÉTODOS: Foram realizados ecocardiogramas transtorácicos no período de janeiro de 2006 a janeiro de 2008, para a avaliação prospectiva de 47 pacientes, subdivididos em GC (36,2%, TX0 (38,3% e TX1 (25,5%, comparando-se o IPM entre eles. Para a análise dos dados foram realizados os testes exato de Fisher e o não paramétrico de Kruskal-Wallis, ambos com nível de significância de 5%. RESULTADOS: Os grupos não diferiram em relação a idade, peso, altura e superfície corpórea. Quando comparado ao GC, TX0 e TX1 apresentaram alteração da função sistodiastólica ventricular esquerda, expressa como aumento do IPM, que foi mais intenso no TX1 [0,38 (0,29 - 0,44 X 0,47 (0,43 - 0,56 X 0,58 (0,52 - 0,74 p BACKGROUND: Heart transplantation is an alternative for individuals with end-stage heart disease. However, episodes of heart rejection (HR are frequent and increase morbidity and mortality, requiring the use of an accurate non-invasive exam for their diagnosis, since endomyocardial biopsy (EMB is not a complication-free procedure. OBJECTIVE: To compare the parameters obtained by use of Doppler echocardiography in a group of transplanted patients with HR (TX1 and another

  2. Inverse Doppler Effects in Flute

    CERN Document Server

    Zhao, Xiao P; Liu, Song; Shen, Fang L; Li, Lin L; Luo, Chun R

    2015-01-01

    Here we report the observation of the inverse Doppler effects in a flute. It is experimentally verified that, when there is a relative movement between the source and the observer, the inverse Doppler effect could be detected for all seven pitches of a musical scale produced by a flute. Higher tone is associated with a greater shift in frequency. The effect of the inverse frequency shift may provide new insights into why the flute, with its euphonious tone, has been popular for thousands of years in Asia and Europe.

  3. Doppler peaks from active perturbations

    CERN Document Server

    Magueijo, J; Coulson, D; Ferreira, P; Magueijo, Joao; Albrecht, Andreas; Coulson, David; Ferreira, Pedro

    1995-01-01

    We examine how the qualitative structure of the Doppler peaks in the angular power spectrum of the cosmic microwave anisotropy depends on the fundamental nature of the perturbations which produced them. The formalism of Hu and Sugiyama is extended to treat models with cosmic defects. We discuss how perturbations can be ``active'' or ``passive'' and ``incoherent'' or ``coherent'', and show how causality and scale invariance play rather different roles in these various cases. We find that the existence of secondary Doppler peaks and the rough placing of the primary peak unambiguously reflect these basic properties.

  4. Doppler Ultrasound: What Is It Used for?

    Science.gov (United States)

    ... in your neck (carotid artery stenosis) A Doppler ultrasound can estimate how fast blood flows by measuring the rate of change in its pitch (frequency). During a Doppler ultrasound, a technician trained in ultrasound imaging (sonographer) presses ...

  5. Doppler tomography in fusion plasmas and astrophysics

    CERN Document Server

    Salewski, Mirko; Heidbrink, Bill; Jacobsen, Asger Schou; Korsholm, Soren Bang; Leipold, Frank; Madsen, Jens; Moseev, Dmitry; Nielsen, Stefan Kragh; Rasmussen, Jesper; Stagner, Luke; Steeghs, Danny; Stejner, Morten; Tardini, Giovani; Weiland, Markus

    2015-01-01

    Doppler tomography is a well-known method in astrophysics to image the accretion flow, often in the shape of thin discs, in compact binary stars. As accretion discs rotate, all emitted line radiation is Doppler-shifted. In fast-ion D-alpha (FIDA) spectroscopy measurements in magnetically confined plasma, the D-alpha-photons are likewise Doppler-shifted ultimately due to gyration of the fast ions. In either case, spectra of Doppler-shifted line emission are sensitive to the velocity distribution of the emitters. Astrophysical Doppler tomography has lead to images of accretion discs of binaries revealing bright spots, spiral structures, and flow patterns. Fusion plasma Doppler tomography has lead to an image of the fast-ion velocity distribution function in the tokamak ASDEX Upgrade. This image matched numerical simulations very well. Here we discuss achievements of the Doppler tomography approach, its promise and limits, analogies and differences in astrophysical and fusion plasma Doppler tomography, and what ...

  6. Ghost features in Doppler-broadened spectra of rovibrational transitions in trapped HD$^+$ ions

    CERN Document Server

    Patra, Sayan

    2016-01-01

    Doppler broadening plays an important role in laser rovibrational spectroscopy of trapped deuterated molecular hydrogen ions (HD$^+$), even at the millikelvin temperatures achieved through sympathetic cooling by laser-cooled beryllium ions. Recently, Biesheuvel \\textit{et al.} \\cite{Biesheuvel2016} presented a theoretical lineshape model for such transitions which not only considers linestrengths and Doppler broadening, but also the finite sample size and population redistribution by blackbody radiation, which are important in view of the long storage and probe times achievable in ion traps. Here, we employ the rate equation model developed by Biesheuvel \\textit{et al.} to theoretically study the Doppler-broadened hyperfine structure of the $(v,L):(0,3)\\rightarrow(4,2)$ rovibrational transition in HD$^+$ at 1442~nm. We observe prominent yet hitherto unrecognized ghost features in the simulated spectrum, whose positions depend on the Doppler width, transition rates, and saturation levels of the hyperfine compo...

  7. The Doppler Effect--A New Approach

    Science.gov (United States)

    Allen, J.

    1973-01-01

    Discusses the Doppler effect as it applies to different situations, such as a stationary source of sound with the observer moving, a stationary observer, and the sound source and observer both moving. Police radar, satellite surveillance radar, radar astronomy, and the Doppler navigator, are discussed as applications of Doppler shift. (JR)

  8. Micro-Doppler Analysis of Small UAVs

    NARCIS (Netherlands)

    Wit, J.J.M. de; Harmanny, R.I.A.; Prémel Cabic, G.

    2012-01-01

    Coherent radar measures micro-Doppler properties of moving objects. The micro-Doppler signature depends on parts of an object moving and rotating in addition to the main body motion (e.g. rotor blades) and is therefore characteristic for the type of object. In this study, the micro-Doppler signature

  9. Speckles in laser doppler perfusion imaging

    NARCIS (Netherlands)

    Rajan, Vinayakrishnan

    2007-01-01

    Laser Doppler Flowmetry (LDF) is a noninvasive diagnostic method to measure blood flow in tissue [1]. The technique is based on measuring the Doppler shift induced by moving red blood cells to the illuminating coherent light. A laser Doppler instrument often gives output signals related to the flux,

  10. Velocity-aligned Doppler spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Z.; Koplitz, B.; Wittig, C.

    1989-03-01

    The technique of velocity-aligned Doppler spectrosocopy (VADS) is presented and discussed. For photolysis/probe experiments with pulsed initiation, VADS can yield Doppler profiles for nascent photofragments that allow detailed center-of-mass (c.m.) kinetic energy distributions to be extracted. When compared with traditional forms of Doppler spectroscopy, the improvement in kinetic energy resolution is dramatic. Changes in the measured profiles are a consequence of spatial discrimination (i.e., focused and overlapping photolysis and probe beams) and delayed observation. These factors result in the selective detection of species whose velocities are aligned with the wave vector of the probe radiation k/sub pr/, thus revealing the speed distribution along k/sub pr/ rather than the distribution of nascent velocity components projected upon this direction. Mathematical details of the procedure used to model VADS are given, and experimental illustrations for HI, H/sub 2/S, and NH/sub 3/ photodissociation are presented. In these examples, pulsed photodissociation produces H atoms that are detected by sequential two-photon, two-frequency ionization via Lyman-..cap alpha.. with a pulsed laser (121.6+364.7 nm), and measuring the Lyman-..cap alpha.. Doppler profile as a function of probe delay reveals both internal and c.m. kinetic energy distributions for the photofragments. Strengths and weaknesses of VADS as a tool for investigating photofragmentation phenomena are also discussed.

  11. Single Mode, Extreme Precision Doppler Spectrographs

    Science.gov (United States)

    Schwab, Christian; Leon-Saval, Sergio G.; Betters, Christopher H.; Bland-Hawthorn, Joss; Mahadevan, Suvrath

    2014-04-01

    The `holy grail' of exoplanet research today is the detection of an earth-like planet: a rocky planet in the habitable zone around a main-sequence star. Extremely precise Doppler spectroscopy is an indispensable tool to find and characterize earth-like planets; however, to find these planets around solar-type stars, we need nearly one order of magnitude better radial velocity (RV) precision than the best current spectrographs provide. Recent developments in astrophotonics (Bland-Hawthorn & Horton 2006, Bland-Hawthorn et al. 2010) and adaptive optics (AO) enable single mode fiber (SMF) fed, high resolution spectrographs, which can realize the next step in precision. SMF feeds have intrinsic advantages over multimode fiber or slit coupled spectrographs: The intensity distribution at the fiber exit is extremely stable, and as a result the line spread function of a well-designed spectrograph is fully decoupled from input coupling conditions, like guiding or seeing variations (Ihle et al. 2010). Modal noise, a limiting factor in current multimode fiber fed instruments (Baudrand & Walker 2001), can be eliminated by proper design, and the diffraction limited input to the spectrograph allows for very compact instrument designs, which provide excellent optomechanical stability. A SMF is the ideal interface for new, very precise wavelength calibrators, like laser frequency combs (Steinmetz et al. 2008, Osterman et al. 2012), or SMF based Fabry-Perot Etalons (Halverson et al. 2013). At near infrared wavelengths, these technologies are ready to be implemented in on-sky instruments, or already in use. We discuss a novel concept for such a spectrograph.

  12. Doppler indicates of uterine artery Doppler velocimetry by placental location

    Energy Technology Data Exchange (ETDEWEB)

    Han, Sung Shik; Park, Yong Won; Cho, Jae Sung; Kwon, Hye Kyeung; Kim, Jae Wook [Yonsei University College of Medicine, Seoul (Korea, Republic of)

    2001-09-15

    Our purpose was to investigate the relation between the vascular resistance of uterine artery and placental location and to establish the reference value of Doppler index in uterine artery by placental location. Placental location and flow velocity waveforms of both uterine arteries in 7,016 pregnant women after 18 weeks gestation were examined using color Doppler ultrasonography. Placental location was classified as central and lateral placental and the uterine artery with lateral placental were divided into ipsilateral uterine artery (same side of the placental) and contralateral uterine artery (opposite side of the placenta). The uterine artery with central placental was classified as the central uterine artery. Systolic-Diastolic ratio (S/D ratio) of uterine arteries by gestational weeks were calculated and compared with the placental location and perinatal outcomes. In the lateral placental group, the S/D ratio of the contralateral uterine artery was higher than the ipsilateral one (mean=2.08+0.34 vs 1.89+0.34, p=0.0001). S/D ratio of the uterine artery decreased during second trimester and the ratio after 27 weeks was a tendency to have a constant values(ipsilateral: 1.85+ 0.34, central : 1.96+ 0.40, contralateral: 2.01+0.54). S/D ratio of the uterine artery was affected by placental location. So when we evaluate Doppler spectrum of uterine artery, placental location should be considered and we established the reference value of Doppler index of uterine artery by placental location.

  13. Azimuthal Doppler Effect in Optical Vortex Spectroscopy

    Science.gov (United States)

    Aramaki, Mitsutoshi; Yoshimura, Shinji; Toda, Yasunori; Morisaki, Tomohiro; Terasaka, Kenichiro; Tanaka, Masayoshi

    2015-11-01

    Optical vortices (OV) are a set of solutions of the paraxial Helmholtz equation in the cylindrical coordinates, and its wave front has a spiral shape. Since the Doppler shift is caused by the phase change by the movement in a wave field, the observer in the OV, which has the three-dimensional structured wave front, feels a three-dimensional Doppler effect. Since the multi-dimensional Doppler components are mixed into a single Doppler spectrum, development of a decomposition method is required. We performed a modified saturated absorption spectroscopy to separate the components. The OV and plane wave are used as a probe beam and pump beam, respectively. Although the plane-wave pump laser cancels the z-direction Doppler shift, the azimuthal Doppler shift remains in the saturated dip. The spatial variation of the dip width gives the information of the azimuthal Doppler shift. The some results of optical vortex spectroscopy will be presented.

  14. First Magnetic Doppler Images of a roAp star

    Science.gov (United States)

    Lüftinger, T.; Kochukhov, O.; Ryabchikova, T.; Weiss, W. W.; Ilyin, I.

    2007-06-01

    We present the first analysis of the magnetic field geometry and elemental abundance distributions on the surface of a rapidly oscillating Ap (roAp) star, using an elaborate magnetic Doppler Imaging (MDI) code (Piskunov et al. 2002, Kochukhov et al. 2002), inv, which allows to reconstruct simultaneously and consistently the magnetic field geometry and abundance distributions on a stellar surface without any a priori assumptions. We analysed Stokes I and V time series obtained with the SOFIN polarimeter and recovered the magnetic field and surface abundance structures of Fe and Nd (among others). These two elements are found to be anticorrelated.

  15. Avaliação funcional dos enxertos coronarianos através do ecocardiograma sob estresse farmacológico com dobutamina Functional assessment of coronary grafts on dobutamine pharmacological stress echocardiogram

    Directory of Open Access Journals (Sweden)

    Felipe José Monassa Pittella

    2006-10-01

    Full Text Available OBJETIVO: Verificar a sensibilidade, a especificidade e a acúracia diagnósticas do ecocardiograma de estresse com dobutamina (EED ao avaliar o estado funcional dos enxertos coronarianos: suficientes (SUF ou insuficientes (INS. MÉTODOS: Estudo observacional, prospectivo, que incluiu 25 pacientes submetidos a cirurgia de revascularização miocárdica (CRVM. Foram realizados o EED e a coronariografia, antes e três meses após a CRVM. O ventrículo esquerdo foi dividido em três territórios por paciente, de acordo com as três principais artérias do coração: descendente anterior (DA, circunflexa (CX e coronária direita (CD. Dos 75 territórios possíveis, 54 foram revascularizados: 25 específicos da artéria DA e 29 das artérias CX/CD. INS significa oclusão ou obstrução luminal maior ou igual a 50%. RESULTADOS: Dos 54 territórios revascularizados, em quatorze (26% os enxertos estavam INS. O EED detectou isquemia em dezesseis (28% territórios; em dez desses os enxertos estavam INS.O EED detectou isquemia em seis (15% dos quarenta territórios cujos enxertos estavam SUF. Portanto, o EED teve sensibilidade de 71,4%, especificidade de 85%, e acurácia diagnóstica de 81,4%. CONCLUSÃO: O EED é um método diagnóstico com alta especificidade e acurácia diagnóstica e boa sensibilidade, na avaliação funcional dos enxertos coronarianos.OBJECTIVE: To verify the sensitivity, specificity and diagnostic accuracy of dobutamine stress echocardiogram (DSE when assessing the functional status of coronary grafts: sufficient (SUF or insufficient (INS. METHODS: We carried out a prospective, observational study which included 25 patients submitted to coronary artery bypass grafting (CABG. The DSE and the coronary angiography were performed before the CABG and three months after the CABG. The left ventricle was divided into three territories per patient according to the three major coronary arterie: the anterior descending (AD, the circumflex (CX

  16. O papel do ecocardiograma como método isolado na indicação cirúrgica de pacientes portadores de cardiopatia congênita The role of echocardiography as an isolated method for indicating surgery in patients with congenital heart disease

    Directory of Open Access Journals (Sweden)

    Lilian Maria Lopes

    2005-05-01

    Full Text Available OBJETIVO: Determinar a acurácia diagnóstica do ecocardiograma, analisando prospectivamente, o valor do método na indicação cirúrgica sem cateterismo em portadores de cardiopatia congênita, através da comparação do diagnóstico ecocardiográfico com os achados intra-operatórios e/ou do estudo invasivo. MÉTODOS: De fevereiro/2000 a janeiro/2001, foram acompanhados 493 pacientes cardiopatas congênitos com indicação cirúrgica, submetidos a ecocardiograma com mapeamento de fluxo em cores para decisão terapêutica. Os resultados foram comparados aos achados cirúrgicos e/ou de cateterismo quando realizado para complementação diagnóstica. RESULTADOS: Dos pacientes estudados, 94,3% (465 casos foram submetidos à correção da cardiopatia congênita apenas com o ecocardiograma e sem cateterismo diagnóstico. O estudo invasivo foi realizado para complementação diagnóstica em 28 (5,6% casos, o tratamento cirúrgico realizado em mais de 95% dos casos e o cateterismo terapêutico em 3,6%. Os achados do ecocardiograma se confirmaram em 464 (94,1% dos casos, demonstrando uma alta acurácia do método. Ocorreram 8 (1,6% casos de falso positivos e 39 (7,9% casos de falso negativos. Segundo os cirurgiões, nenhum dos erros diagnósticos levaram a complicações ou afetaram os resultados cirúrgicos adversamente. CONCLUSÃO: O ecocardiograma se mostrou método sensível e seguro para indicação cirúrgica, dispensando, muitas vezes, a realização de estudo invasivo, ficando este, restrito aos casos de complementação diagnóstica ou terapêutica.OBJECTIVE: To determine the diagnostic accuracy of echocardiography for indicating surgery without catheterization in patients with congenital heart disease through a prospective analysis and comparison of the echocardiographic diagnosis with the intraoperative findings, or invasive study, or both. METHODS: From February 2000 to January 2001, 493 patients with congenital heart diseases indicated

  17. Velocity-aligned Doppler spectroscopy

    Science.gov (United States)

    Xu, Z.; Koplitz, B.; Wittig, C.

    1989-03-01

    The use of velocity-aligned Doppler spectroscopy (VADS) to measure center-of-mass kinetic-energy distributions of nascent photofragments produced in pulsed-initiation photolysis/probe experiments is described and demonstrated. In VADS, pulsed photolysis and probe laser beams counterpropagate through the ionization region of a time-of-flight mass spectrometer. The theoretical principles of VADS and the mathematical interpretation of VADS data are explained and illustrated with diagrams; the experimental setup is described; and results for the photodissociation of HI, H2S, and NH3 are presented in graphs and characterized in detail. VADS is shown to give much higher kinetic-energy resolution than conventional Doppler spectroscopy.

  18. Single mode, extreme precision Doppler spectrographs

    CERN Document Server

    Schwab, Christian; Betters, Christopher H; Bland-Hawthorn, Joss; Mahadevan, Suvrath

    2012-01-01

    The 'holy grail' of exoplanet research today is the detection of an earth-like planet: a rocky planet in the habitable zone around a main-sequence star. Extremely precise Doppler spectroscopy is an indispensable tool to find and characterize earth-like planets; however, to find these planets around solar-type stars, we need nearly one order of magnitude better radial velocity (RV) precision than the best current spectrographs provide. Recent developments in astrophotonics (Bland-Hawthorn & Horton 2006, Bland-Hawthorn et al. 2010) and adaptive optics (AO) enable single mode fiber (SMF) fed, high resolution spectrographs, which can realize the next step in precision. SMF feeds have intrinsic advantages over multimode fiber or slit coupled spectrographs: The intensity distribution at the fiber exit is extremely stable, and as a result the line spread function of a well-designed spectrograph is fully decoupled from input coupling conditions, like guiding or seeing variations (Ihle et al. 2010). Modal noise, a...

  19. Doppler tomography in fusion plasmas and astrophysics

    DEFF Research Database (Denmark)

    Salewski, Mirko; Geiger, B.; Heidbrink, W. W.;

    2015-01-01

    Doppler tomography is a well-known method in astrophysics to image the accretion flow, often in the shape of thin discs, in compact binary stars. As accretion discs rotate, all emitted line radiation is Doppler-shifted. In fast-ion Dα (FIDA) spectroscopy measurements in magnetically confined plasma......, the Dα-photons are likewise Doppler-shifted ultimately due to gyration of the fast ions. In either case, spectra of Doppler-shifted line emission are sensitive to the velocity distribution of the emitters. Astrophysical Doppler tomography has lead to images of accretion discs of binaries revealing bright...... and limits, analogies and differences in astrophysical and fusion plasma Doppler tomography and what can be learned by comparison of these applications....

  20. DOPPLER ANALYSIS IN PREGNANCY INDUCED HYPERTENSION

    Directory of Open Access Journals (Sweden)

    Tushar

    2014-12-01

    Full Text Available A study of 50 cases was conducted to evaluate the role of Colour Doppler imaging in pregnancy induced hypertension with women over 28 weeks of gestation, the initial scan was performed immediately after the diagnosis of PIH to avoid any influence of treatment on Doppler evaluation. This study was aimed to analyze the blood flow in umbilical artery, maternal uterine artery & fetal middle cerebral artery using Doppler ultrasound.

  1. Emboli detection using the Doppler ultrasound technique

    Institute of Scientific and Technical Information of China (English)

    WANG Yuanyuan; CHEN Xi; ZHANG Yu; WANG Weiqi

    2003-01-01

    Embolic detection is very important to the early diagnosis of vessel disease. The Doppler ultrasound technique is one of the common methods to detect the emboli non-invasively. When the emboli pass through the sample volume of the Doppler ultrasound instrument, there exist high intensity transient Doppler signals. Thus the emboli can be detected directly from the variation of Doppler signal amplitude. Since there may be some disturbance in the system, this general detection method has great limitation. To improve the accuracy of emboli auto-detection, several novel methods are studied to obtain the sensitive characteristic of the emboli signals using the new signal processing theories.

  2. Doppler tomography in fusion plasmas and astrophysics

    NARCIS (Netherlands)

    Salewski, M.; Geiger, B.; Heidbrink, W. W.; Jacobsen, A. S.; Korsholm, S. B.; Leipold, F.; Madsen, J.; Moseev, D.; Nielsen, S.K.; Rasmussen, J.; Stagner, L.; Steeghs, D.; Stejner, M.; Tardini, G.; Weiland, M.; ASDEX Upgrade team,

    2015-01-01

    Doppler tomography is a well-known method in astrophysics to image the accretion flow, often in the shape of thin discs, in compact binary stars. As accretion discs rotate, all emitted line radiation is Doppler-shifted. In fast-ion D-alpha (FIDA) spectroscopy measurements in magnetically confined pl

  3. Inverse Doppler Effects in Broadband Acoustic Metamaterials

    Science.gov (United States)

    Zhai, S. L.; Zhao, X. P.; Liu, S.; Shen, F. L.; Li, L. L.; Luo, C. R.

    2016-08-01

    The Doppler effect refers to the change in frequency of a wave source as a consequence of the relative motion between the source and an observer. Veselago theoretically predicted that materials with negative refractions can induce inverse Doppler effects. With the development of metamaterials, inverse Doppler effects have been extensively investigated. However, the ideal material parameters prescribed by these metamaterial design approaches are complex and also challenging to obtain experimentally. Here, we demonstrated a method of designing and experimentally characterising arbitrary broadband acoustic metamaterials. These omni-directional, double-negative, acoustic metamaterials are constructed with ‘flute-like’ acoustic meta-cluster sets with seven double meta-molecules; these metamaterials also overcome the limitations of broadband negative bulk modulus and mass density to provide a region of negative refraction and inverse Doppler effects. It was also shown that inverse Doppler effects can be detected in a flute, which has been popular for thousands of years in Asia and Europe.

  4. Observation of the Zero Doppler Effect

    Science.gov (United States)

    Ran, Jia; Zhang, Yewen; Chen, Xiaodong; Fang, Kai; Zhao, Junfei; Chen, Hong

    2016-04-01

    The normal Doppler effect has well-established applications in many areas of science and technology. Recently, a few experimental demonstrations of the inverse Doppler effect have begun to appear in negative-index metamaterials. Here we report an experimental observation of the zero Doppler effect, that is, no frequency shift irrespective of the relative motion between the wave signal source and the detector in a zero-index metamaterial. This unique phenomenon, accompanied by the normal and inverse Doppler effects, is generated by reflecting a wave from a moving discontinuity in a composite right/left-handed transmission line loaded with varactors when operating in the near zero-index passband, or the right/left-handed passband. This work has revealed a complete picture of the Doppler effect in metamaterials and may lead to potential applications in electromagnetic wave related metrology.

  5. Estimating the Doppler centroid of SAR data

    DEFF Research Database (Denmark)

    Madsen, Søren Nørvang

    1989-01-01

    After reviewing frequency-domain techniques for estimating the Doppler centroid of synthetic-aperture radar (SAR) data, the author describes a time-domain method and highlights its advantages. In particular, a nonlinear time-domain algorithm called the sign-Doppler estimator (SDE) is shown to have...... attractive properties. An evaluation based on an existing SEASAT processor is reported. The time-domain algorithms are shown to be extremely efficient with respect to requirements on calculations and memory, and hence they are well suited to real-time systems where the Doppler estimation is based on raw SAR...... data. For offline processors where the Doppler estimation is performed on processed data, which removes the problem of partial coverage of bright targets, the ΔE estimator and the CDE (correlation Doppler estimator) algorithm give similar performance. However, for nonhomogeneous scenes it is found...

  6. Inverse Doppler Effects in Broadband Acoustic Metamaterials.

    Science.gov (United States)

    Zhai, S L; Zhao, X P; Liu, S; Shen, F L; Li, L L; Luo, C R

    2016-08-31

    The Doppler effect refers to the change in frequency of a wave source as a consequence of the relative motion between the source and an observer. Veselago theoretically predicted that materials with negative refractions can induce inverse Doppler effects. With the development of metamaterials, inverse Doppler effects have been extensively investigated. However, the ideal material parameters prescribed by these metamaterial design approaches are complex and also challenging to obtain experimentally. Here, we demonstrated a method of designing and experimentally characterising arbitrary broadband acoustic metamaterials. These omni-directional, double-negative, acoustic metamaterials are constructed with 'flute-like' acoustic meta-cluster sets with seven double meta-molecules; these metamaterials also overcome the limitations of broadband negative bulk modulus and mass density to provide a region of negative refraction and inverse Doppler effects. It was also shown that inverse Doppler effects can be detected in a flute, which has been popular for thousands of years in Asia and Europe.

  7. Multiwavelength Doppler factors for Fermi-detected gamma-ray loud blazars

    Institute of Scientific and Technical Information of China (English)

    Hou-Dun Zeng; Li Zhang

    2011-01-01

    We collect a sample of 51 Fermi-detected gamma-ray loud blazars with known radio Doppler factors and study properties of the Doppler factors of blazars at optical, X-ray and gamma-ray bands. A basic assumption is that the emission from the radio to gamma-ray bands of the blazars are produced by the nonthermal radiation of accelerated particles in a jet. Our results show that (1) the Doppler factors of blazars are a function of frequency, with the Doppler factor decreasing with frequency from the radio to X-ray regions, and then increasing from the X-ray to y-ray regions which are similar to results given by Zhang et al., and (2) there are marginal correlations between the Doppler factors at radio and X-ray bands and the synchrotron peak frequency, and a strong correlation between the Doppler factor in the gamma-ray band and the synchrotron peak frequency, but no correlation in the optical band.

  8. Inversionless gain enhancing due to Doppler broadening in a closed lambda-type system

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    An analysis is made of the effect of Doppler broadening on gain without inversion (GWI) from different aspects in a closed lambda-type three-level system with an incoherent pump. It is shown that, regardless of the driving field being on resonance or not, for the counter- or co-propagating of the probe and driving fields (PDF), GWI does not monotonically decrease or increase with increasing Doppler width. Except for the case of counter-propagating PDF with off-resonance driving field, at a suitable Doppler width one can obtain a gain maximum value much larger than that without Doppler broadening; especially in the situation of the resonant driving field, the co-propagating geometry leads to a larger GWI. In addition, for the counter-propagating geometry, when Doppler width is larger enough, GWI oscillation occurs, and the oscillation amplitude and region increase with increasing Doppler width. These conclusions are very different from that obtained in previous investigation (Lukin et al, Laser Phys. 6 436 (1996)).

  9. Color doppler sonography in thickened gallbladder wall

    Energy Technology Data Exchange (ETDEWEB)

    Han, Sang Suk; Choi, Seok Jin; Seo, Chang Hae; Eun, Choong Ki [Inje Univ. College of Medicine, Kimhae (Korea, Republic of)

    1996-11-01

    The thickening of the gallbladder wall is a valuable finding for the diagnosis of cholecystitis, but may be seen in non-cholecystic disease as well as in acute or chronic cholecystitis. The purpose of this study is to determine the value of color Doppler sonography in differentiating the causes of thickened gallbladder wall. Ninety eight patients with thickened gallbladder wall(more than 3mm) which was not due to gallbladder cancer were prospectively evaluated with color Doppler sonography. Sixty-six cases, confirmed by pathologic reports and clinical records, were analyzed for correlation between thickened gallbladder wall and color flow signal according to the underlying causes. Of the 66 patients, 28 cases were cholecystitis and 38 cases had non-cholecystic causes such as liver cirrhosis, ascites, hepatitis, pancreatitis, renal failure, and hypoalbuminemia. Of the 28 patients with cholecystitis(12 acute, 16 chronic), 23(82%) had color Doppler flow signals in the thickened gallbladder wall. Of the 38 patients with non-cholecystic causes, eight(21%) had color Doppler flow signals. There was a statistically significant difference of color Doppler flow signals between the cholecystitis and non-cholecystic groups(p=0.0001). No significant difference of color Doppler flow signals was found between cases of acute and chronic cholecystitis. Of the 23 patients with color Doppler flow signals in 28 cases of cholecystitis, 18(78.3%) showed a linear pattern and five(21.7%) showed a spotty pattern. Of the eight patients with color Doppler flow signals in the 38 non-cholecystic cases, four(50%) showed a linear pattern and four(50%) showed a spotty pattern. In cholecystitis, a linear color Doppler flow signal pattern is a much more frequent finding than a spotty pattern. Color Doppler sonography is a useful and adequate method for determining whether a thickened gallbladder wall is the result of cholecystitis or has non-cholecystic causes.

  10. ANALYTICAL CALCULATIONS AND MONTE-CARLO SIMULATIONS OF LASER DOPPLER FLOWMETRY USING A CUBIC LATTICE MODEL

    NARCIS (Netherlands)

    KOELINK, MH; DEMUL, FFM; GREVE, J; GRAAFF, R; DASSEL, ACM; AARNOUDSE, JG

    1992-01-01

    In addition to the static cubic lattice model for photon migration in turbid biological media by Bonner et al. [J. Opt. Soc. Am. A 4, 423-432 (1987)], a dynamic method is presented to calculate the average absolute Doppler shift as a function of the distance between the point of injection of photons

  11. Ghost features in Doppler-broadened spectra of rovibrational transitions in trapped HD+ ions

    Science.gov (United States)

    Patra, Sayan; Koelemeij, J. C. J.

    2017-02-01

    Doppler broadening plays an important role in laser rovibrational spectroscopy of trapped deuterated molecular hydrogen ions (HD+), even at the millikelvin temperatures achieved through sympathetic cooling by laser-cooled beryllium ions. Recently, Biesheuvel et al. (2016) presented a theoretical lineshape model for such transitions which not only considers linestrengths and Doppler broadening, but also the finite sample size and population redistribution by blackbody radiation, which are important in view of the long storage and probe times achievable in ion traps. Here, we employ the rate equation model developed by Biesheuvel et al. to theoretically study the Doppler-broadened hyperfine structure of the (v, L) : (0, 3) → (4, 2) rovibrational transition in HD+ at 1442 nm. We observe prominent yet hitherto unrecognized ghost features in the simulated spectrum, whose positions depend on the Doppler width, transition rates, and saturation levels of the hyperfine components addressed by the laser. We explain the origin and behavior of such features, and we provide a simple quantitative guideline to assess whether ghost features may appear. As such ghost features may be common to saturated Doppler-broadened spectra of rotational and vibrational transitions in trapped ions composed of partly overlapping lines, our work illustrates the necessity to use lineshape models that take into account all the relevant physics.

  12. The Effect of Doppler Phenomenon on the Speed of Blood Flow

    Directory of Open Access Journals (Sweden)

    Ghaidaa Abdulrahman Khalid

    2012-01-01

    Full Text Available This research studying the phenomenon of Doppler (frequency Doppler as a method through which the direction and speed of the blood cells flows in blood vessels wear measured. This Doppler frequency is relied upon in medicine for measuring the speed of blood flow, because the blood flow is an important concept from the concepts of medicine. It represents the function and efficient of the heart and blood vessels in the body so any defect in this function will appear as a change in the speed of blood flow from the normal value assumed. As this speed changes alot in cases of disease and morbidity of the heart, so in order to identify the effect of changing the Doppler frequency on the speed of blood flow and the relationship of this frequency with the angles of transitions and receptions and the effect of changing the ultrasound transmitted frequencies on the measured velocities .The Doppler ultrasound system has been used which is more efficient and easier to be widely used as a practical application in Al Yarmouk Teaching Hospital on two subjects. The normal had a natural medical history in the blood vessels, and abnormal had carotid artery stenosis. This device will give the flow velocity of blood in the blood vessels which is useful to the examiner, the equation of Doppler as a mathematical model in the research is adopted the measured speed to clarify the amount of change in the frequency (shift in frequency. This speed was measured in five different blood vessels, large arteries (abdominal aorta and carotid artery in the neck and large veins (the inferior vena cava across the abdomen and the external Jugular vein in the neck and capillaries in the hand and fingers. Then using the measured velocities in these vessels the Doppler frequency was calculated from this mathematical model using MATLAB program, was found that as velocity of the blood increases, so does the Doppler frequency and vice versa. The greater the value of the Doppler angle

  13. Optical Doppler tomography and spectral Doppler imaging of localized ischemic stroke in a mouse model

    Science.gov (United States)

    Yu, Lingfeng; Nguyen, Elaine; Liu, Gangjun; Rao, Bin; Choi, Bernard; Chen, Zhongping

    2010-02-01

    We present a combined optical Doppler tomography/spectral Doppler imaging modality to quantitatively evaluate the dynamic blood circulation and the artery blockage before and after a localized ischemic stroke in a mouse model. Optical Doppler Tomography (ODT) combines the Doppler principle with optical coherence tomography for noninvasive localization and measurement of particle flow velocity in highly scattering media with micrometer scale spatial resolution. Spectral Doppler imaging (SDI) provides complementary temporal flow information to the spatially distributed flow information of Doppler imaging. Fast, repeated, ODT scans across an entire vessel were performed to record flow dynamic information with high temporal resolution of cardiac cycles. Spectral Doppler analysis of continuous Doppler images demonstrates how the velocity components and longitudinally projected flow-volume-rate change over time for scatters within the imaging volume using spectral Doppler waveforms. Furthermore, vascular conditions can be quantified with various Doppler-angle-independent flow indices. Non-invasive in-vivo mice experiments were performed to evaluate microvascular blood circulation of a localized ischemic stroke mouse model.

  14. Staggered Multiple-PRF Ultrafast Color Doppler.

    Science.gov (United States)

    Posada, Daniel; Poree, Jonathan; Pellissier, Arnaud; Chayer, Boris; Tournoux, Francois; Cloutier, Guy; Garcia, Damien

    2016-06-01

    Color Doppler imaging is an established pulsed ultrasound technique to visualize blood flow non-invasively. High-frame-rate (ultrafast) color Doppler, by emissions of plane or circular wavefronts, allows severalfold increase in frame rates. Conventional and ultrafast color Doppler are both limited by the range-velocity dilemma, which may result in velocity folding (aliasing) for large depths and/or large velocities. We investigated multiple pulse-repetition-frequency (PRF) emissions arranged in a series of staggered intervals to remove aliasing in ultrafast color Doppler. Staggered PRF is an emission process where time delays between successive pulse transmissions change in an alternating way. We tested staggered dual- and triple-PRF ultrafast color Doppler, 1) in vitro in a spinning disc and a free jet flow, and 2) in vivo in a human left ventricle. The in vitro results showed that the Nyquist velocity could be extended to up to 6 times the conventional limit. We found coefficients of determination r(2) ≥ 0.98 between the de-aliased and ground-truth velocities. Consistent de-aliased Doppler images were also obtained in the human left heart. Our results demonstrate that staggered multiple-PRF ultrafast color Doppler is efficient for high-velocity high-frame-rate blood flow imaging. This is particularly relevant for new developments in ultrasound imaging relying on accurate velocity measurements.

  15. Rotational Doppler effect in nonlinear optics

    Science.gov (United States)

    Li, Guixin; Zentgraf, Thomas; Zhang, Shuang

    2016-08-01

    The translational Doppler effect of electromagnetic and sound waves has been successfully applied in measurements of the speed and direction of vehicles, astronomical objects and blood flow in human bodies, and for the Global Positioning System. The Doppler effect plays a key role for some important quantum phenomena such as the broadened emission spectra of atoms and has benefited cooling and trapping of atoms with laser light. Despite numerous successful applications of the translational Doppler effect, it fails to measure the rotation frequency of a spinning object when the probing wave propagates along its rotation axis. This constraint was circumvented by deploying the angular momentum of electromagnetic waves--the so-called rotational Doppler effect. Here, we report on the demonstration of rotational Doppler shift in nonlinear optics. The Doppler frequency shift is determined for the second harmonic generation of a circularly polarized beam passing through a spinning nonlinear optical crystal with three-fold rotational symmetry. We find that the second harmonic generation signal with circular polarization opposite to that of the fundamental beam experiences a Doppler shift of three times the rotation frequency of the optical crystal. This demonstration is of fundamental significance in nonlinear optics, as it provides us with insight into the interaction of light with moving media in the nonlinear optical regime.

  16. Doppler backscatter properties of a blood-mimicking fluid for Doppler performance assessment.

    Science.gov (United States)

    Ramnarine, K V; Hoskins, P R; Routh, H F; Davidson, F

    1999-01-01

    The Doppler backscatter properties of a blood-mimickig fluid (BMF) were studied to evaluate its suitability for use in a Doppler flow test object. Measurements were performed using a flow rig with C-flex tubing and BMF flow produced by a roller pump or a gear pump. A SciMed Doppler system was used to measure the backscattered Doppler power with a root-mean-square power meter connected to the audio output. Studies investigated the dependence of the backscattered Doppler power of the BMF with: circulation time; batch and operator preparations; storage; sieve size; flow speed; and pump type. A comparison was made with human red blood cells resuspended in saline. The backscatter properties are stable and within International Electrotechnical Commission requirements. The BMF is suitable for use in a test object for Doppler performance assessment.

  17. Um Novo Indice de Doppler Tecidual para Prever Morte Cardiaca em Pacientes com Insuficiencia Cardiaca

    Directory of Open Access Journals (Sweden)

    Cristian Mornos

    2014-01-01

    Full Text Available Fundamento: Foi demonstrado que um novo índice de Doppler Tecidual, E/(E'×S', incluindo a proporção entre a velocidade diastólica precoce transmitral e a do anel mitral (E/E', e a velocidade sistólica do anel mitral (S', tem uma boa precisão como preditor da pressão de enchimento do ventrículo esquerdo. Objetivo: Investigar o valor de E/(E'×S' para prever a morte cardíaca em pacientes com insuficiência cardíaca. Métodos: Foi realizado sucessivamente o ecocardiograma em 339 pacientes hospitalizados com insuficiência cardíaca, em ritmo sinusal, após tratamento médico adequado, no momento e um mês depois da alta. O agravamento de E/(E'×S' foi definido como um aumento do valor padrão. O ponto final foi a morte cardíaca. Resultados: Durante o período de acompanhamento (35,2 ± 8,8 meses, ocorreu a morte cardíaca em 51 pacientes (15%. O melhor valor mínimo para E/(E'× S' inicial na previsão da morte cardíaca foi de 2,83 (76% de sensibilidade, 85% de especificidade. No momento da alta, 252 pacientes (74,3% apresentaram E/(E'×S' ≤ 2,83 (grupo I, e 87 (25,7% apresentaram E/(E'×S' > 2,83 (grupo II, respectivamente. A morte cardíaca foi significativamente maior no grupo II em relação ao grupo I (38 mortes, 43,7% contra 13 mortes, 5,15%, p 2,83 no momento da alta e com um agravamento após um mês apresentaram o pior prognóstico (todos p < 0,05. Conclusão: Em pacientes com insuficiência cardíaca a relação E/(E'×S' é um poderoso preditor da morte cardíaca, especialmente quando esta estiver associada com o seu agravamento.

  18. Teaching the Doppler effect in astrophysics

    Science.gov (United States)

    Hughes, Stephen W.; Cowley, Michael

    2017-03-01

    The Doppler effect is a shift in the frequency of waves emitted from an object moving relative to the observer. By observing and analysing the Doppler shift in electromagnetic waves from astronomical objects, astronomers gain greater insight into the structure and operation of our Universe. In this paper, a simple technique is described for teaching the basics of the Doppler effect to undergraduate astrophysics students using acoustic waves. An advantage of the technique is that it produces a visual representation of the acoustic Doppler shift. The equipment comprises a 40 kHz acoustic transmitter and a microphone. The sound is bounced off a computer fan and the signal collected by a DrDAQ ADC and processed by a spectrum analyser. Widening of the spectrum is observed as the fan power supply potential is increased from 4 to 12 V.

  19. High range resolution micro-Doppler analysis

    Science.gov (United States)

    Cammenga, Zachary A.; Smith, Graeme E.; Baker, Christopher J.

    2015-05-01

    This paper addresses use of the micro-Doppler effect and the use of high range-resolution profiles to observe complex targets in complex target scenes. The combination of micro-Doppler and high range-resolution provides the ability to separate the motion of complex targets from one another. This ability leads to the differentiation of targets based on their micro-Doppler signatures. Without the high-range resolution, this would not be possible because the individual signatures would not be separable. This paper also addresses the use of the micro-Doppler information and high range-resolution profiles to generate an approximation of the scattering properties of a complex target. This approximation gives insight into the structure of the complex target and, critically, is created without using a pre-determined target model.

  20. Student Microwave Experiments Involving the Doppler Effect.

    Science.gov (United States)

    Weber, F. Neff; And Others

    1980-01-01

    Described is the use of the Doppler Effect with microwaves in the measurement of the acceleration due to gravity of falling objects. The experiments described add to the repertoire of quantitative student microwave experiments. (Author/DS)

  1. High Throughput Direct Detection Doppler Lidar Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Lite Cycles, Inc. (LCI) proposes to develop a direct-detection Doppler lidar (D3L) technology called ELITE that improves the system optical throughput by more than...

  2. Doppler echocardiography in normal functioning valve prostheses.

    Science.gov (United States)

    Cha, R; Yang, S S; Salvucci, T; DiBlasi, S

    1994-09-01

    Even though there has been some criticism regarding the Doppler evaluation in prosthetic valves because of inter-observer and intra-observer variability, among other factors, and Doppler study has a tendency to have falsely high gradients compared to invasive studies, especially mechanical aortic prostheses, Doppler evaluation can provide reliable hemodynamic information about valve function. This test may be particularly useful if used serially, when baseline values are known. Doppler measurement of gradient and valve area has an expected normal range that is specific for the prosthetic type, size, anatomical position, and chronological age. Clearly, a database involving these aspects is needed to provide a more accurate normal range. This study is intended to provide guidance for echocardiographers.

  3. Teste ergométrico precoce após infarto do miocárdio: comparação com ecocardiograma, monitorização eletrocardiográfica e arteriografia coronariana Exercise testing early after myocardial infarction: comparison with echocardiography, electrocardiographic monitoring and coronary arteriography

    Directory of Open Access Journals (Sweden)

    Wagner Aparecido Leite

    2008-03-01

    Full Text Available FUNDAMENTO: O teste ergométrico precoce após infarto do miocárdio, realizado antes da alta hospitalar, é útil na estratificação de risco, na prescrição de exercício e na avaliação do prognóstico e do tratamento. OBJETIVO: O objetivo deste estudo foi comparar os achados do teste ergométrico precoce pós-infarto aos resultados do ecocardiograma, da monitorização eletrocardiográfica pelo sistema holter (24 horas e da cinecoronariografia. MÉTODOS: Avaliaram-se 60 casos (51,42 ± 9,34 anos, 46 do sexo masculino (77%. O teste ergométrico foi máximo sintoma limitante, realizado pelo protocolo de Naughton, entre o sexto dia de internação e a alta hospitalar, realizado em uso de medicação. Durante a internação, os pacientes foram submetidos a ecocardiograma, eletrocardiografia dinâmica e cinecoronariografia. Adotou-se o nível de significância de 0,05 (a=5%. RESULTADOS: O desempenho do teste ergométrico na detecção de doença coronária multiarterial foi reduzido (sensibilidade, 42%; especificidade, 69%. Não houve diferenças significativas quando se comparou a presença de isquemia no teste ergométrico com doença coronária de múltiplos vasos, arritmias ventriculares complexas na eletrocardiografia dinâmica e ocorrência de fração de ejeção inferior a 60% no ecocardiograma (p = 0,56, bem como com a presença de lesões multiarteriais, arritmias ventriculares complexas na eletrocardiografia dinâmica e fração de ejeção anormal no ecocardiograma (p = 0,36. CONCLUSÃO: Durante o teste, a presença de isquemia se associou à ocorrência de arritmias ventriculares na eletrocardiografia dinâmica, à redução da fração de ejeção no ecocardiograma e à presença de lesões coronárias multiarteriais, o que representou um indicador de elevado risco coronário.BACKGROUND: Predischarge exercise testing early after myocardial infarction is useful for risk stratification, exercise prescription, and assessment of

  4. Observation of Doppler broadening in $\\beta$-delayed proton-$\\gamma$ decay

    CERN Document Server

    Schwartz, S B; Bennett, M B; Liddick, S N; Perez-Loureiro, D; Bowe, A; Chen, A A; Chipps, K A; Cooper, N; Irvine, D; McNeice, E; Montes, F; Naqvi, F; Ortez, R; Pain, S D; Pereira, J; Prokop, C; Quaglia, J; Quinn, S J; Sakstrup, J; Santia, M; Shanab, S; Simon, A; Spyrou, A; Thiagalingam, E

    2015-01-01

    Background: The Doppler broadening of $\\gamma$-ray peaks due to nuclear recoil from $\\beta$-delayed nucleon emission can be used to measure the energies of the nucleons. This method has never been tested using $\\beta$-delayed proton emission or applied to a recoil heavier than $A=10$. Purpose: To test and apply this Doppler broadening method using $\\gamma$-ray peaks from the $^{26}$P($\\beta p\\gamma$)$^{25}$Al decay sequence. Methods: A fast beam of $^{26}$P was implanted into a planar Ge detector, which was used as a $^{26}$P $\\beta$-decay trigger. The SeGA array of high-purity Ge detectors was used to detect $\\gamma$ rays from the $^{26}$P($\\beta p\\gamma$)$^{25}$Al decay sequence. Results: Radiative Doppler broadening in $\\beta$-delayed proton-$\\gamma$ decay was observed for the first time. The Doppler broadening analysis method was verified using the 1613 keV $\\gamma$-ray line for which the proton energies were previously known. The 1776 keV $\\gamma$ ray de-exciting the 2720 keV $^{25}$Al level was observed...

  5. Optical Doppler shift with structured light

    OpenAIRE

    2011-01-01

    When a light beam with a transverse spatially varying phase is considered for optical remote sensing, in addition to the usual longitudinal Doppler frequency shift of the returned signal induced by the motion of the scatter along the beam axis, a new transversal Doppler shift appears associated to the motion of the scatterer in the plane perpendicular to the beam axis. We discuss here how this new effect can be used to enhance the current capabilities of optical measurement system...

  6. Measurements of enlarged blood pump models using Laser Doppler Anemometer.

    Science.gov (United States)

    Chua, L P; Yu, S C; Leo, H L

    2000-01-01

    In an earlier study (Chua et al., 1998, 1999a), a 5:1 enlarged model of the Kyoto-NTN Magnetically Suspended Centrifugal Blood Pump (Akamatsu et al., 1995) with five different impeller blade profiles was designed and constructed. Their respective flow characteristics with respect to (1) the three different blade profile designs: forward, radial, and backward, (2) the number of blades used, and (3) the rotating speed were investigated. Among the five impeller designs, the results obtained suggested that impellers A and C designs should be adopted if higher head is required. Impellers A and C therefore were selected for the flow in between their blades to be measured using Laser Doppler Anemometer (LDA), so as to have a better understanding of the flow physics with respect to the design parameters.

  7. with Ultrasound Color Doppler Imaging

    Directory of Open Access Journals (Sweden)

    Shin Takayama

    2012-01-01

    Full Text Available Color Doppler imaging (CDI can be used to noninvasively create images of human blood vessels and quantitatively evaluate blood flow in real-time. The purpose of this study was to assess the effects of acupuncture on the blood flow of the peripheral, mesenteric, and retrobulbar arteries by CDI. Statistical significance was defined as P values less than 0.05. Blood flow in the radial and brachial arteries was significantly lower during needle stimulation on LR3 than before in healthy volunteers, but was significantly higher after needle stimulation than before. LR3 stimulation also resulted in a significant decrease in the vascular resistance of the short posterior ciliary artery and no significant change of blood flow through the superior mesenteric artery (SMA during acupuncture. In contrast, ST36 stimulation resulted in a significant increase in blood flow through the SMA and no significant change in the vascular resistance of the retrobulbar arteries. Additionally, acupuncture at previously determined acupoints in patients with open-angle glaucoma led to a significant reduction in the vascular resistance of the central retinal artery and short posterior ciliary artery. Our results suggest that acupuncture can affect blood flow of the peripheral, mesenteric, and retrobulbar arteries, and CDI can be useful to evaluate hemodynamic changes by acupuncture.

  8. The Doppler effect in NMR spectroscopy.

    Science.gov (United States)

    Guéron, Maurice

    2003-02-01

    An NMR sample may be subject to motions, such as those due to sample spinning or to liquid flow. Is the spectrum of such a sample affected by the Doppler effect? The question arises because, instrumental dimensions being much shorter than the wavelength, it is the near-field of the precessing magnetic moment which couples to the receiver coil, rather than the radiated far-field. We expand the near-field into plane propagating waves. For each such wave there is another one with the same amplitude, propagating in the opposite direction. The Doppler shifts are therefore equal and opposite. In the model case of a small fluid sample moving with constant velocity, this leads to a distribution of Doppler shifts which is symmetrical with respect to the unshifted frequency: there is no net spectral shift. We examine the possibility of observing the Doppler distribution in this case. We also consider the case of thermal motion of a gas. We draw attention to the resolved Doppler splitting of molecular rotational transitions in a supersonic burst as observed in a microwave resonator. We also mention briefly the Doppler effect in molecular beam spectroscopy.

  9. Doppler micro sense and avoid radar

    Science.gov (United States)

    Gorwara, Ashok; Molchanov, Pavlo; Asmolova, Olga

    2015-10-01

    There is a need for small Sense and Avoid (SAA) systems for small and micro Unmanned Aerial Systems (UAS) to avoid collisions with obstacles and other aircraft. The proposed SAA systems will give drones the ability to "see" close up and give them the agility to maneuver through tight areas. Doppler radar is proposed for use in this sense and avoid system because in contrast to optical or infrared (IR) systems Doppler can work in more harsh conditions such as at dusk, and in rain and snow. And in contrast to ultrasound based systems, Doppler can better sense small sized obstacles such as wires and it can provide a sensing range from a few inches to several miles. An SAA systems comprised of Doppler radar modules and an array of directional antennas that are distributed around the perimeter of the drone can cover the entire sky. These modules are designed so that they can provide the direction to the obstacle and simultaneously generate an alarm signal if the obstacle enters within the SAA system's adjustable "Protection Border". The alarm signal alerts the drone's autopilot to automatically initiate an avoidance maneuver. A series of Doppler radar modules with different ranges, angles of view and transmitting power have been designed for drones of different sizes and applications. The proposed Doppler radar micro SAA system has simple circuitry, works from a 5 volt source and has low power consumption. It is light weight, inexpensive and it can be used for a variety of small unmanned aircraft.

  10. Doppler-radar wind-speed measurements in tornadoes: A comparison of real and simulated spectra

    Energy Technology Data Exchange (ETDEWEB)

    Bluestein, H.B.; LaDue, J.G.; Stein, H.; Speheger, D. (Oklahoma Univ., Norman, OK (United States)); Unruh, W.P. (Los Alamos National Lab., NM (United States))

    1993-01-01

    Bluestein and Unruh have discussed the advantages of using a portable doppler radar to map the wind field in tornadoes. during the spring of 1991 a storm-intercept team from the University of Oklahoma (OU) collected data near five supercell tornadoes in Oklahoma and Kansas. Details about the 1-W, 3-cm, 5-deg half-power beamwidth, CW/FM-CW Doppler radar we used and the methods of data collection and analysis are found in Bluestein and Unruh and Bluestein et al. Using the portable radar, we approximately doubled in only one year the number of tornado spectra that had been collected over a period of almost 20 years by NSSL's fixed-site Doppler radar. In this paper we will compare observed tornado wind spectra with simulated wind spectra (Zmic and Doviak 1975) in order to learn more about tornado structure.

  11. Saturn's Doppler velocimetry wind measurements with VLT/UVES

    Science.gov (United States)

    Silva, Miguel; Mota Machado, Pedro; Luz, David; Sanchez-Lavega, Agustin; Hueso, Ricardo; Peralta, Javier

    2016-10-01

    We present Doppler wind velocity results of Saturn's zonal flow at ~0.4 mbar pressure level. Our aim is help to constrain the characterization of the equatorial jet at the referred altitude and the latitudinal variation of the zonal winds, to contribute to monitor the spatial and temporal variability in order to achieve a better understanding of the dynamics of Saturn's zonal winds, which Sánchez-Lavega et al. (2003, Nature, 423, 623) have found to have strongly changed in recent years, as the planet approached southern summer solstice.The UVES/VLT instrument has been used, which simultaneously achieves high spectral resolving power and high spatial resolution. The field has been derotated in order to have the aperture aligned perpendicularly to Saturn's rotation axis. In this configuration, spatial information in the East-West direction is preserved in a set of spectra in the direction perpendicular to dispersion.The technique of absolute accelerometry (AA, Connes, 1985, ApSS 110, 211) has been applied to the backscattered solar spectrum in order to determine the Doppler shift associated with the zonal circulation. Our measurements have been made in the wavelength range of 480-680 nm. Previously we successfully adapted this Doppler velocimetry technique for measuring winds at Venus cloud tops (Machado et al. 2012).The observations consisted of 4 blocks of 15 exposures of 90 sec, plus two shorter blocks of 9 exposures, totalling 7.3 hours of telescope time. In order to cover the whole disk the aperture has been offset by 1 arcsec in the North-South direction between consecutive exposures. Most of the northern hemisphere was covered by the rings. Saturn's diameter was 17.4 arcsec, and the slit aperture was 0.3x25 arcsec. The aperture offset between consecutive exposures was 1 arcsec. Two observations blocks of 9 exposures only covered the central part of the disk, and four others covered the whole disk. The sub-terrestrial point was at -26.1 degrees South. The

  12. Ultrasonography with color Doppler and power Doppler in the diagnosis of periapical lesions

    Directory of Open Access Journals (Sweden)

    Sumit Goel

    2011-01-01

    Full Text Available Aim: To evaluate the efficacy of ultrasonography (USG with color Doppler and power Doppler applications over conventional radiography in the diagnosis of periapical lesions. Materials and Methods: Thirty patients having inflammatory periapical lesions of the maxillary or mandibular anterior teeth and requiring endodontic surgery were selected for inclusion in this study. All patients consented to participate in the study. We used conventional periapical radiographs as well as USG with color Doppler and power Doppler for the diagnosis of these lesions. Their diagnostic performances were compared against histopathologic examination. All data were compared and statistically analyzed. Results: USG examination with color Doppler and power Doppler identified 29 (19 cysts and 10 granulomas of 30 periapical lesions accurately, with a sensitivity of 100% for cysts and 90.91% for granulomas and a specificity of 90.91% for cysts and 100% for granulomas. In comparison, conventional intraoral radiography identified only 21 lesions (sensitivity of 78.9% for cysts and 45.4% for granulomas and specificity of 45.4% for cysts and 78.9% for granulomas. There was definite correlation between the echotexture of the lesions and the histopathological features except in one case. Conclusions: USG imaging with color Doppler and power Doppler is superior to conventional intraoral radiographic methods for diagnosing the nature of periapical lesions in the anterior jaws. This study reveals the potential of USG examination in the study of other jaw lesions.

  13. On the Doppler distortion of the sea-wave spectra

    Science.gov (United States)

    Korotkevich, A. O.

    2008-11-01

    Discussions on a form of a frequency spectrum of wind-driven sea waves just above the spectral maximum have continued for the last three decades. In 1958 Phillips made a conjecture that wave breaking is the main mechanism responsible for the spectrum formation [O.M. Phillips, J. Fluid Mech. 4 (1958) 426]. That leads to the spectrum decay ˜ω-5, where ω is the frequency of waves. There is a contradiction between the numerous experimental data and this spectrum. Experiments frequently show decay ˜ω-4 [Y. Toba, J. Oceanogr. Soc. Japan 29 (1973) 209; M.A. Donelan, J. Hamilton, W.H. Hui, Phil. Trans. R. Soc. London A315 (1985) 509; P.A. Hwang, et al., J. Phys. Oceanogr. 30 (1999) 2753]. There are several ways of the explanation of this phenomenon. One of them (proposed by Banner [M.L. Banner, J. Phys. Oceanogr. 20 (1990) 966]) takes into account the Doppler effect due to surface circular currents generated by underlying waves in the Phillips model. In this article the influence of the Doppler effect on an arbitrary averaged spectrum is considered using both analytic and numerical approaches. Although we mostly concentrated on the very important case of Phillips model, the developed technique and general formula can be used for the analysis of other spectra. For the particular case of Phillips spectra we got analytic asymptotics in the vicinity of spectral maximum and for high frequencies. Results were obtained for two most important angular dependences of the spectra: isotropic and strongly anisotropic. Together with the analytic investigation we performed numerical calculations in a wide range of frequencies. Both high and low frequency asymptotics are in very good agreement with the numerical results. It was shown that at least at low frequencies, the correction to the spectrum due to the Doppler shift is negligible. At high frequencies there is an asymptotic with tail ˜ω-3.

  14. Development of the doppler electron velocimeter: theory.

    Energy Technology Data Exchange (ETDEWEB)

    Reu, Phillip L.

    2007-03-01

    Measurement of dynamic events at the nano-scale is currently impossible. This paper presents the theoretical underpinnings of a method for making these measurements using electron microscopes. Building on the work of Moellenstedt and Lichte who demonstrated Doppler shifting of an electron beam with a moving electron mirror, further work is proposed to perfect and utilize this concept in dynamic measurements. Specifically, using the concept of ''fringe-counting'' with the current principles of transmission electron holography, an extension of these methods to dynamic measurements is proposed. A presentation of the theory of Doppler electron wave shifting is given, starting from the development of the de Broglie wave, up through the equations describing interference effects and Doppler shifting in electron waves. A mathematical demonstration that Doppler shifting is identical to the conceptually easier to understand idea of counting moving fringes is given by analogy to optical interferometry. Finally, potential developmental experiments and uses of a Doppler electron microscope are discussed.

  15. Wide Angle Michelson Doppler Imaging Interferometer (WAMDII)

    Science.gov (United States)

    Roberts, B.

    1986-01-01

    The wide angle Michelson Doppler imaging interferometer (WAMDII) is a specialized type of optical Michelson interferometer working at sufficiently long path difference to measure Doppler shifts and to infer Doppler line widths of naturally occurring upper atmospheric Gaussian line emissions. The instrument is intended to measure vertical profiles of atmospheric winds and temperatures within the altitude range of 85 km to 300 km. The WAMDII consists of a Michelson interferometer followed by a camera lens and an 85 x 106 charge coupled device photodiode array. Narrow band filters in a filter wheel are used to isolate individual line emissions and the lens forms an image of the emitting region on the charge coupled device array.

  16. Diabetic Nephropathy : Evaluation with Doppler Ultrasonography

    Energy Technology Data Exchange (ETDEWEB)

    Sim, Jung Suk; Kim, Seung Hyup; Kang, Heung Sik; Park, Jae Hyung; Han, Man Chung [Seoul National University College of Medicine, Seoul (Korea, Republic of)

    1996-06-15

    To compare Doppler ultrasonography with laboratory tests in evaluation of diabetic nephropathy. Fifty-five patients (mean age = 60, M : F = 26 : 29) with diabetes mellitus underwent renal Doppler ultrasonography. Resistive indices were compared with degree of proteinuria, serum creatinine level, and creatinine clearance rate. Eighteen patients who showed no proteinuria or microscopic proteinuria had a mean resistive index (RI) of 0.72 (SD, 0.05), 16 patients with macroscopic proteinuria without nephrotic syndrome had a mean RI of 0.82 (SD, 0.13), and 21 patients with nephrotic syndrome had a mean RI of 0.90 (SD, 0.12). Renal RI correlated highly with serum creatinine level (r = 0.62) and creatinine clearance rate (r = -0.43). Renal Doppler ultrasonography provides a useful indication of renal function in diabetic nephropathy but cannot offer an advantage over conventional laboratory test

  17. Análisis de perforantes de la epigástrica inferior profunda con Angio TC 3D, Eco Doppler color y Doppler simple de ultrasonidos en colgajo DIEP: resultados preliminares Analysis of deep inferior epigastric perforating vessels with 3D CT angiography, color Doppler ultrasonography and Doppler in diep flaps: preliminary results

    Directory of Open Access Journals (Sweden)

    J. Castro García

    2008-09-01

    Full Text Available Nuestro objetivo es la validación de la Angio TC tridimensional como herramienta de planificación de los colgajos DIEP, comparándolo con el Doppler de ultrasonidos (US y eco Doppler color. Entre enero de 2006 y marzo de 2007 se realiza en 11 pacientes (13 DIEP un estudio comparativo prospectivo entre el Doppler de US, eco Doppler color y Angio TC con reconstrucción tridimensional, utilizando como dato de referencia los hallazgos intraoperatorios. En dicho proceso se localiza la mejor perforante que pueda servir como pedículo al colgajo DIEP en función de su localización, calibre, trayecto y relaciones anatómicas con respecto al músculo. La Angio TC con reconstrucción tridimensional, demuestra una especificidad del 100% (IC 95% 75.3-100 lo que le convierte en una prueba con un alto valor predictivo positivo y una excelente herramienta en la planificación de los colgajos de perforantes. El eco Doppler color determinó, que tan sólo en un 46,1% (IC 95% 19,2-74,9 de los pacientes, la perforante seleccionada por la prueba de forma preoperatoria, coincidía con la perforante elegida en quirófano. Con el Doppler de US, en un 30,8 % (IC 95% 9,1-61,4 de los colgajos estudiados, coincidía la mejor perforante escogida de forma preoperatoria, con los hallazgos obtenidos tras la disección del colgajo. En el presente estudio, la Angio TC tridimensional se ha mostrado como una técnica con una gran especificidad que proporciona valiosa información, sólo comparable con la disección anatómica y por delante de pruebas como el Doppler de ultrasonidos y el eco Doppler color.The aim of this report, is to validate the Angio-CT technique with three-dimentional reconstruction as a preoperative planning tool, after comparison with Doppler ultrasound and color- Duplex. Between january 2006 and march 2007, we studied 11 consecutive patients (13 DIEP in whom a prospective comparative followed up was performed comparing, the findings observed using

  18. Observation of the inverse Doppler effect.

    Science.gov (United States)

    Seddon, N; Bearpark, T

    2003-11-28

    We report experimental observation of an inverse Doppler shift, in which the frequency of a wave is increased on reflection from a receding boundary. This counterintuitive effect has been produced by reflecting a wave from a moving discontinuity in an electrical transmission line. Doppler shifts produced by this system can be varied in a reproducible manner by electronic control of the transmission line and are typically five orders of magnitude greater than those produced by solid objects with kinematic velocities. Potential applications include the development of tunable and multifrequency radiation sources.

  19. Reversed Doppler effect in photonic crystals.

    Science.gov (United States)

    Reed, Evan J; Soljacić, Marin; Joannopoulos, John D

    2003-09-26

    Nonrelativistic reversed Doppler shifts have never been observed in nature and have only been speculated to occur in pathological systems with simultaneously negative effective permittivity and permeability. This Letter presents a different, new physical phenomenon that leads to a nonrelativistic reversed Doppler shift in light. It arises when light is reflected from a moving shock wave propagating through a photonic crystal. In addition to reflection of a single frequency, multiple discrete reflected frequencies or a 10 GHz periodic modulation can also be observed when a single carrier frequency of wavelength 1 microm is incident.

  20. Preprocessing of ionospheric echo Doppler spectra

    Institute of Scientific and Technical Information of China (English)

    FANG Liang; ZHAO Zhengyu; WANG Feng; SU Fanfan

    2007-01-01

    The real-time information of the distant ionosphere can be acquired by using the Wuhan ionospheric oblique backscattering sounding system(WIOBSS),which adopts a discontinuous wave mechanism.After the characteristics of the ionospheric echo Doppler spectra were analyzed,the signal preprocessing was developed in this paper,which aimed at improving the Doppler spectra.The results indicate that the preprocessing not only makes the system acquire a higher ability of target detection but also suppresses the radio frequency interference by 6-7 dB.

  1. Optical Doppler shift with structured light.

    Science.gov (United States)

    Belmonte, Aniceto; Torres, Juan P

    2011-11-15

    When a light beam with a transverse spatially varying phase is considered for optical remote sensing, in addition to the usual longitudinal Doppler frequency shift of the returned signal induced by the motion of the scatter along the beam axis, a new transversal Doppler shift appears associated to the motion of the scatterer in the plane perpendicular to the beam axis. We discuss here how this new effect can be used to enhance the current capabilities of optical measurement systems, adding the capacity to detect more complex movements of scatters.

  2. Magnetic Doppler Imaging of Active Stars

    CERN Document Server

    Kochukhov, O

    2007-01-01

    We present a new implementation of the magnetic Doppler imaging technique, which aims at self-consistent temperature and magnetic mapping of the surface structures in cool active stars. Our magnetic imaging procedure is unique in its capability to model individual spectral features in all four Stokes parameters. We discuss performance and intrinsic limitations of the new magnetic Doppler imaging method. A special emphasis is given to the simultaneous modelling of the magnetically sensitive lines in the optical and infrared regions and to combining information from both atomic and molecular spectral features. These two techniques may, for the first time, give us a tool to study magnetic fields in the starspot interiors.

  3. Fish embryo multimodal imaging by laser Doppler digital holography

    CERN Document Server

    Verrier, Nicolas; Picart, Pascal; Gross, Michel

    2015-01-01

    A laser Doppler imaging scheme combined to an upright microscope is proposed. Quantitative Doppler imaging in both velocity norm and direction, as well as amplitude contrast of either zebrafish flesh or vasculature is demonstrated.

  4. Operational Bright-Band Snow Level Detection Using Doppler Radar

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A method to detect the bright-band snow level from radar reflectivity and Doppler vertical velocity data collection with an atmospheric profiling Doppler radar. The...

  5. A dual frequency 10 cm Doppler weather radar

    Science.gov (United States)

    Glover, K. M.; Armstrong, G. M.; Bishop, A. W.; Banis, K. J.

    A summary is given of the design concepts underlying a new 10-cm band dual frequency Doppler weather radar under development at the Air Force Geophysics Laboratory. Primary emphasis in the design is placed on the system performance in a clutter environment, and the technique used to extend the radar's unambiguous range and velocity span is an important, but secondary, consideration. The design includes the use of fault tolerance and/or fault location methods at critical locations in the system and automated calibration techniques for quasi-continuous monitoring of system performance. The approach followed for minimizing range and velocity ambiguities used in this radar is a uniform pulse train version of the Doviak et al. (1978) dual sampling (batch) technique.

  6. Magnetic Doppler imaging considering atmospheric structure modifications due to local abundances: a luxury or a necessity?

    CERN Document Server

    Kochukhov, O; Shulyak, D

    2012-01-01

    Magnetic Doppler imaging is currently the most powerful method of interpreting high-resolution spectropolarimetric observations of stars. This technique has revealed the presence of unexpected small-scale magnetic fields on the surfaces of Ap stars. These studies were recently criticisied by Stift et al. (2012), who claimed that magnetic inversions are not robust and are undermined by neglecting a feedback on the Stokes line profiles from the local atmospheric structure in the regions of enhanced metal abundance. We show that Stift et al. misinterpreted published magnetic Doppler imaging results and neglected some of the most fundamental principles behind magnetic mapping. We demonstrate that the variation of atmospheric structure across the surface of a star with chemical spots affects the local continuum intensity but is negligible for the normalised local Stokes profiles. For the disk-integrated spectra of an Ap star with extreme abundance variations, we find that the assumption of a mean model atmosphere ...

  7. Photoacoustic Doppler effect from flowing small light-absorbing particles.

    Science.gov (United States)

    Fang, Hui; Maslov, Konstantin; Wang, Lihong V

    2007-11-01

    From the flow of a suspension of micrometer-scale carbon particles, the photoacoustic Doppler shift is observed. As predicted theoretically, the observed Doppler shift equals half of that in Doppler ultrasound and does not depend on the direction of laser illumination. This new physical phenomenon provides a basis for developing photoacoustic Doppler flowmetry, which can potentially be used for detecting fluid flow in optically scattering media and especially low-speed blood flow of relatively deep microcirculation in biological tissue.

  8. Photoacoustic Doppler flow measurement in optically scattering media

    Science.gov (United States)

    Fang, Hui; Maslov, Konstantin; Wang, Lihong V.

    2007-12-01

    We recently observed the photoacoustic Doppler effect from flowing small light-absorbing particles. Here, we apply the effect to measure blood-mimicking fluid flow in an optically scattering medium. The light scattering in the medium decreases the amplitude of the photoacoustic Doppler signal but does not affect either the magnitude or the directional discrimination of the photoacoustic Doppler shift. This technology may hold promise for a new Doppler method for measuring blood flow in microcirculation with high sensitivity.

  9. Solid breast neoplasms: Differential diagnosis with pulsed Doppler ultrasound

    NARCIS (Netherlands)

    T.J.A. Kuijpers (T. J A); A.I.M. Obdeijn (Inge-Marie); Ph.M. Kruyt (Philip); M. Oudkerk (Matthijs)

    1994-01-01

    textabstractIn this prospective study, duplex Doppler ultrasound was used in 95 consecutive patients with solid breast masses to evaluate the presence of neovascular flow. A positive Doppler signal, i.e., a Doppler shift frequency of more than 1 kHz using a 5 MHz insonating frequency, was found in 3

  10. Radar micro-doppler signatures processing and applications

    CERN Document Server

    Chen, Victor C; Miceli, William J

    2014-01-01

    Radar Micro-Doppler Signatures: Processing and applications concentrates on the processing and application of radar micro-Doppler signatures in real world situations, providing readers with a good working knowledge on a variety of applications of radar micro-Doppler signatures.

  11. On acceleration dependence of Doppler effect in light

    Indian Academy of Sciences (India)

    Sanjay M Wagh

    2013-09-01

    Using only the geometric relationships of suitable locations, we analyse Doppler effect in light to show how the acceleration of the source also contributes to the Doppler shift. We further propose that an experiment be performed using cyclotron-type devices to determine the acceleration dependence of the Doppler shift.

  12. 21 CFR 892.1550 - Ultrasonic pulsed doppler imaging system.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Ultrasonic pulsed doppler imaging system. 892.1550... system. (a) Identification. An ultrasonic pulsed doppler imaging system is a device that combines the features of continuous wave doppler-effect technology with pulsed-echo effect technology and is intended...

  13. Musculoskeletal colour/power Doppler in sports medicine

    DEFF Research Database (Denmark)

    Boesen, M I; Boesen, M; Langberg, Henning

    2010-01-01

    guidelines and recommendations are based on personal experience since no evidence in literature exists. The basic technical background of Doppler ultrasound and typical artefacts will be discussed, in order to understand and interpret the Doppler result. Recommendations for the Doppler settings are given...

  14. Spectroscopic observation of the rotational Doppler effect.

    Science.gov (United States)

    Barreiro, S; Tabosa, J W R; Failache, H; Lezama, A

    2006-09-15

    We report on the first spectroscopic observation of the rotational Doppler shift associated with light beams carrying orbital angular momentum. The effect is evidenced as the broadening of a Hanle electromagnetically induced transparency coherence resonance on Rb vapor when the two incident Laguerre-Gaussian laser beams have opposite topological charges. The observations closely agree with theoretical predictions.

  15. Method for Canceling Ionospheric Doppler Effect

    Science.gov (United States)

    Vessot, R. F. C.

    1982-01-01

    Unified transponder system with hydrogen-maser oscillators at both stations can compensate for both motional and ionospheric components of Doppler shift. Appropriate choices of frequency shift in output of mixer m3. System exploits proportionality between dispersive component of frequency shift and reciprocal of frequency to achieve cancellation of dispersive component at output.

  16. Calculating "g" from Acoustic Doppler Data

    Science.gov (United States)

    Torres, Sebastian; Gonzalez-Espada, Wilson J.

    2006-01-01

    Traditionally, the Doppler effect for sound is introduced in high school and college physics courses. Students calculate the perceived frequency for several scenarios relating a stationary or moving observer and a stationary or moving sound source. These calculations assume a constant velocity of the observer and/or source. Although seldom…

  17. Doppler-ultralydundersøgelse af underekstremitetsarteriosklerose

    DEFF Research Database (Denmark)

    Rørdam, P; von Jessen, F; Sillesen, H H;

    1992-01-01

    Arteriography, which requires resources and is not entirely without risk, has hitherto been a prerequisite for reconstructive surgery in cases of symptom-producing arteriosclerosis in the lower limbs. As an alternative, indirect Doppler ultrasonic examination has been employed but does not appear...

  18. Transcranial Doppler velocimetry in aneurysmal subarachnoid haemorrhage

    DEFF Research Database (Denmark)

    Staalsø, J M; Edsen, T; Romner, B

    2013-01-01

    -coded transcranial Doppler (TCCD), with the secondary aim of describing prediction of angiographic vasospasm and mortality. METHODS: /st>Sixty patients and 70 healthy controls were each examined in duplicate by alternating operators. A total of 939 measurements divided on 201 examination sets were conducted by four...

  19. Coherent Detection in Laser Doppler Velocimeters

    DEFF Research Database (Denmark)

    Hanson, Steen Grüner

    1974-01-01

    , but intelligible particle picture of electromagnetic waves. The analysis is carried out with special emphasis on the heterodyning process in the laser Doppler velocimeter (LDV) because the main purpose of this article is to provide a better understanding of this instrument. An aid for this purpose...

  20. [Phlegmasia alba dolens diagnosed with Doppler ultrasonography].

    Science.gov (United States)

    Wulff, C; Lorentzen, T; Christensen, E; Pedersen, E B

    1996-11-11

    Differential diagnostic problems may occur in a patient with a cold, pale and swollen leg. Especially when the peripheral blood pressure is reduced, it is particularly difficult to distinguish cases caused by venous thrombosis from those caused by arterial embolism. Colour-Doppler ultra-sonography might be helpful for establishing the correct diagnosis. A case history is presented.

  1. Investigations of Near-Zone Doppler Effects.

    Science.gov (United States)

    Prouty, Dale Austen

    Far away from an electromagnetic source the normal Doppler shifts in frequency occur--a red shift for receding and a blue shift for approaching. As indicated by previous work with an infinitesimal dipole, different frequency shifts occur when the source and observer move closer together, into the near-zone. These "near-zone Doppler effects" are investigated for general sources and subsequently two specific examples are presented. The general results show that near-zone shifts are similar to far-zone shifts, but the local phase velocity must be used, i.e. (DIAGRAM, TABLE OR GRAPHIC OMITTED...PLEASE SEE DAI). In the far zone the phase velocity is the speed of light; in the near zone it differs. Fundamentally, the distance between surfaces of constant phase in the near zone is changed. The surfaces of constant phase for the waves are no longer spherical, but more ellipsoidal or spheroidal, so that a moving observer sees a different frequency shift. Two specific examples are presented to indicate the actual magnitude of near-zone effects. The examples include a prolate spheroidal antenna and a circular aperture. Once the magnitude of the effects is determined, the measurability of near-zone Doppler effects is discussed. The investigation concentrates on Fresnel zone effects due to the measurement problem. Finally, it is shown that for an electrically large wire antenna (the spheroidal example) near-zone Doppler effects are measurable.

  2. Tissue Doppler imaging reproducibility during exercise.

    Science.gov (United States)

    Bougault, V; Nottin, S; Noltin, S; Doucende, G; Obert, P

    2008-05-01

    Tissue Doppler imaging (TDI) is an echocardiographic technique used during exercising to improve the accuracy of a cardiovascular diagnostic. The validity of TDI requires its reproducibility, which has never been challenged during moderate to maximal intensity exercising. The present study was specifically designed to assess the transmitral Doppler and pulsed TDI reproducibility in 19 healthy men, who had undergone two identical semi-supine maximal exercise tests on a cycle ergometer. Systolic (S') and diastolic (E') tissue velocities at the septal and lateral walls as well as early transmitral velocities (E) were assessed during exercise up to maximal effort. The data were compared between the two tests at 40 %, 60 %, 80 % and 100 % of maximal aerobic power. Despite upper body movements and hyperventilation, good quality echocardiographic images were obtained in each case. Regardless of exercise intensity, no differences were noticed between the two tests for all measurements. The variation coefficients for Doppler variables ranged from 3 % to 9 % over the transition from rest to maximal exercise. The random measurement error was, on average, 5.8 cm/s for E' and 4.4 cm/s for S'. Overall, the reproducibility of TDI was acceptable. Tissue Doppler imaging can be used to accurately evaluate LV diastolic and/or systolic function for this range of exercise intensity.

  3. Doppler Shift Compensation Schemes in VANETs

    Directory of Open Access Journals (Sweden)

    F. Nyongesa

    2015-01-01

    Full Text Available Over the last decade vehicle-to-vehicle (V2V communication has received a lot of attention as it is a crucial issue in intravehicle communication as well as in Intelligent Transportation System (ITS. In ITS the focus is placed on integration of communication between mobile and fixed infrastructure to execute road safety as well as nonsafety information dissemination. The safety application such as emergence alerts lays emphasis on low-latency packet delivery rate (PDR, whereas multimedia and infotainment call for high data rates at low bit error rate (BER. The nonsafety information includes multimedia streaming for traffic information and infotainment applications such as playing audio content, utilizing navigation for driving, and accessing Internet. A lot of vehicular ad hoc network (VANET research has focused on specific areas including channel multiplexing, antenna diversity, and Doppler shift compensation schemes in an attempt to optimize BER performance. Despite this effort few surveys have been conducted to highlight the state-of-the-art collection on Doppler shift compensation schemes. Driven by this cause we survey some of the recent research activities in Doppler shift compensation schemes and highlight challenges and solutions as a stock-taking exercise. Moreover, we present open issues to be further investigated in order to address the challenges of Doppler shift in VANETs.

  4. Exact classical Doppler effect derived from the photon emission process

    CERN Document Server

    Lin, Chyi-Lung; Hsieh, Shang-Lin; Tsai, Chun-Ming

    2016-01-01

    The concept of photon is not necessary only applied to the relativistic Doppler theory. It may also work well for classical theory. As conservation of momentum and energy are physical laws, if applying these laws gives the exact relativistic Doppler effect, it should also give the exact classical Doppler effect. So far the classical Doppler effect is only obtained by using some approximation, as derived by Fermi in 1932. We show that the exact classical Doppler effect can be derived from the photon emission process in the exact treatment and reveal that these results are the same as those derived from the wave theory of light.

  5. Polarimetric Doppler spectrum of backscattered echoes from nonlinear sea surface damped by natural slicks

    Science.gov (United States)

    Yang, Pengju; Guo, Lixin

    2016-11-01

    Based on the Lombardini et al. model that can predict the hydrodynamic damping of rough sea surfaces in the presence of monomolecular slicks and the "choppy wave" model (CWM) that can describe the nonlinear interactions between ocean waves, the modeling of time-varying nonlinear sea surfaces damped by natural or organic sea slicks is presented in this paper. The polarimetric scattering model of second-order small-slope approximation (SSA-II) with tapered wave incidence is utilized for evaluating co- and cross-polarized backscattered echoes from clean and contaminated CWM nonlinear sea surfaces. The influence of natural sea slicks on Doppler shift and spectral bandwidth of radar sea echoes is investigated in detail by comparing the polarimetric Doppler spectra of contaminated sea surfaces with those of clean sea surfaces. A narrowing of Doppler spectra in the presence of oil slicks is observed for both co- and cross-polarization, which is qualitatively consistent with wave-tank measurements. Simulation results also show that the Doppler shifts in slicks can increase or decrease, depending on incidence angles and polarizations.

  6. Power and color Doppler ultrasound settings for inflammatory flow

    DEFF Research Database (Denmark)

    Torp-Pedersen, Søren; Christensen, Robin; Szkudlarek, Marcin

    2015-01-01

    OBJECTIVE: To determine how settings for power and color Doppler ultrasound sensitivity vary on different high- and intermediate-range ultrasound machines and to evaluate the impact of these changes on Doppler scoring of inflamed joints. METHODS: Six different types of ultrasound machines were used....... On each machine, the factory setting for superficial musculoskeletal scanning was used unchanged for both color and power Doppler modalities. The settings were then adjusted for increased Doppler sensitivity, and these settings were designated study settings. Eleven patients with rheumatoid arthritis (RA......: Power Doppler was more sensitive on half of the machines, whereas color Doppler was more sensitive on the other half, using both factory settings and study settings. There was an average increase in Doppler sensitivity, despite modality, of 78% when study settings were applied. Over the 6 machines, 2...

  7. ESTIMATION OF DOPPLER CENTROID FREQUENCY IN SPACEBORNE SCANSAR

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Doppler centroid frequency is an essential parameter in the imaging processing of the Scanning mode Synthetic Aperture Radar(ScanSAR).Inaccurate Doppler centroid frequency will result in ghost images in imaging result.In this letter,the principle and algorithms of Doppler centroid frequency estimation are introduced.Then the echo data of ScanSAR system is analyzed.Based on the algorithms of energy balancing and correlation Doppler estimator in the estimation of Doppler centroid fequency in strip mode SAR,an improved method for Doppler centroid frequency estimation in ScanSAR is proposed.The method has improved the accuracy of Doppler centroid fequency estimation in ScanSAR by zero padding between burst data.Finally,the proposed method is validated with the processing of ENVironment SATellite Advanced Synthetic Aperture Radar(ENVISAT ASAR)wide swath raw data.

  8. Correlação da função diastólica com a capacidade máxima de exercício ao teste ergométrico Correlación de la función diastólica con la capacidad máxima de ejercicio al test ergométrico Correlation between diastolic function and maximal exercise capacity on exercise test

    Directory of Open Access Journals (Sweden)

    Maria Estefânia Bosco Otto

    2011-02-01

    Full Text Available FUNDAMENTO: O aumento da pressão de capilar pulmonar (PCP é um dos mecanismos de intolerância ao exercício. A avaliação da função diastólica pelo ecocardiograma (ECO é capaz de estimar a PCP. OBJETIVO: Identificar variáveis determinantes da capacidade de exercício em paciente submetidos a teste ergométrico (TE de rotina, ECO convencional e doppler tecidual (DT. MÉTODOS: Foram estudados, retrospectivamente, 640 pacientes submetidos a TE e ao ECO e DT. Pacientes com fração de ejeção 10 foi considerada uma estimativa de aumento da PCP. A capacidade máxima de esforço foi avaliada pelo número de equivalentes metabólicos (MET. Para análise, os pacientes foram divididos em dois grupos: MET 7 (n = 572. O escore de Morise demonstrou uma população de baixo risco (60% para doença coronária (DAC. RESULTADOS: O número de pacientes com E/e’ > 10 foi significativamente maior no grupo MET 7(41,7% vs 9,4%, p = 0,001, bem como a presença de algum grau de disfunção diastólica (76,6% vs 34,1% p = 0,001. Pela análise de regressão logística, as variáveis independentes de baixa capacidade de exercício (MET FUNDAMENTO: El aumento de la presión de capilar pulmonar (PCP es uno de los mecanismos de intolerancia al ejercicio. La evaluación de la función diastólica por el ecocardiograma (ECO es capaz de estimar la PCP. OBJETIVO: Identificar variables determinantes de la capacidad de ejercicio en paciente sometido a test ergométrico (TE de rutina, ECO convencional y doppler tisular (DT. MÉTODOS: Fueron estudiados, retrospectivamente, 640 pacientes sometidos a TE y al ECO y DT. Pacientes con fracción de eyección 10 fue considerada una estimativa de aumento de la PCP. La capacidad máxima de esfuerzo fue evaluada por el número de equivalentes metabólicos (MET. Para análisis, los pacientes fueron divididos en dos grupos: MET 7 (n = 572. El escore de Morise demostró una población de bajo riesgo (60% para enfermedad coronaria

  9. Superharmonic microbubble Doppler effect in ultrasound therapy

    Science.gov (United States)

    Pouliopoulos, Antonios N.; Choi, James J.

    2016-08-01

    The introduction of microbubbles in focused ultrasound therapies has enabled a diverse range of non-invasive technologies: sonoporation to deliver drugs into cells, sonothrombolysis to dissolve blood clots, and blood-brain barrier opening to deliver drugs into the brain. Current methods for passively monitoring the microbubble dynamics responsible for these therapeutic effects can identify the cavitation position by passive acoustic mapping and cavitation mode by spectral analysis. Here, we introduce a new feature that can be monitored: microbubble effective velocity. Previous studies have shown that echoes from short imaging pulses had a Doppler shift that was produced by the movement of microbubbles. Therapeutic pulses are longer (>1 000 cycles) and thus produce a larger alteration of microbubble distribution due to primary and secondary acoustic radiation force effects which cannot be monitored using pulse-echo techniques. In our experiments, we captured and analyzed the Doppler shift during long therapeutic pulses using a passive cavitation detector. A population of microbubbles (5  ×  104-5  ×  107 microbubbles ml-1) was embedded in a vessel (inner diameter: 4 mm) and sonicated using a 0.5 MHz focused ultrasound transducer (peak-rarefactional pressure: 75-366 kPa, pulse length: 50 000 cycles or 100 ms) within a water tank. Microbubble acoustic emissions were captured with a coaxially aligned 7.5 MHz passive cavitation detector and spectrally analyzed to measure the Doppler shift for multiple harmonics above the 10th harmonic (i.e. superharmonics). A Doppler shift was observed on the order of tens of kHz with respect to the primary superharmonic peak and is due to the axial movement of the microbubbles. The position, amplitude and width of the Doppler peaks depended on the acoustic pressure and the microbubble concentration. Higher pressures increased the effective velocity of the microbubbles up to 3 m s-1, prior to the onset of

  10. [Color-Doppler semiology in transplanted kidney].

    Science.gov (United States)

    Rivolta, R; Castagnone, D; Burdick, L; Mandelli, C; Mangiarotti, R

    1993-05-01

    Color-encoded duplex ultrasonography (CEDU) makes a more accurate technique in kidney graft monitoring by combining real-time US with pulsed Doppler studies of renal vasculature. It is a non-invasive and easy technique. Suitable to study the whole renal artery and vein, CEDU also allows the qualitative and quantitative assessment of the intrarenal vasculature and therefore the easy diagnosis of such vessel dysfunctions as arteriovenous fistulas following biopsy. Moreover, Doppler spectral analysis can be used to distinguish among different causes of renal allograft dysfunction--i.e. rejection, cyclosporine nephrotoxicity or acute tubular necrosis. The value of the resistive index for the differential diagnosis is discussed. CEDU allows a more reliable measurement of renal blood flow thanks to the more precise evaluation of renal artery diameter and mean flow velocity.

  11. Transcranial Doppler sonography in familial hemiplegic migraine

    Energy Technology Data Exchange (ETDEWEB)

    Pierelli, F.; Pauri, F.; Cupini, L.M.; Fiermonte, G.; Rizzo, P.A. (Universita la Sapienza, Roma (Italy))

    1991-02-01

    A patient affected by familial hemiplegic migraine underwent transcranial Doppler sonography twice: the first during a spontaneous attack with right hemiparesis and aphasia, the second during a headachefree period. During the attack the following haemodynamic changes were seen: (a) bilateral increase in the middle cerebral artery and anterior cerebral artery blood flow velocities (this increase was more pronounced on the left side), (b) decreased systo-diastolic ratio and pulsatility index on the right side, (c) increased systo-diastolic ratio and pulsatility index on the left side. The results indicate that during the attack in this familial hemiplegic migraine patient, a diffuse vasoconstriction of the basal cerebral arteries developed. Moreover, transcranial Doppler sonography data suggest that a prolonged vasoconstriction of the peripheral arterioles could play a role in determining the neurological symptoms in this syndrome. 13 refs., 1 figs., 1 tab.

  12. Color Doppler US of the penis

    Energy Technology Data Exchange (ETDEWEB)

    Bertolotto, Michele (ed.) [Trieste Univ. Ospedale di Cattinara (Italy). Dept. Radiology

    2008-07-01

    This book provides a comprehensive reference and practical guide on the application of US to penile diseases and conditions. After introductory chapters on technical requirements and penile anatomy, subsequent chapters offer a systematic overview of the diverse applications of color Doppler US. The topics covered include erectile dysfunction, Peyronie's disease, priapism, trauma, tumors, the postoperative penis, inflammation, and fibrosis. Each topic is introduced by a clinical overview with the purpose of clarifying the problems and elucidating what the urologist may expect from color Doppler US. Thereafter, performance of the US study is explained and the pathological anatomy reviewed. High-quality images obtained with high-end US equipment are included. Each chapter also contains a section on the diagnostic information provided by other imaging modalities, and in particular MRI. (orig.)

  13. Renal duplex Doppler ultrasound findings in diabetics

    Energy Technology Data Exchange (ETDEWEB)

    Shim, Hyang Yee; Kim, Young Geun; Kook, Cheol Keu; Yoon, Chong Hyun; Lee, Shin Hyung; Lee, Chang Joon [National Medical Center, Seoul (Korea, Republic of)

    1993-12-15

    The correlation between clinical-laboratory findings and renal duplex Doppler ultrasound findings was studied in 45 patients with diabetes mellitus to see the role of duplex Doppler ultrasound in the detection of diabetic nephropathy. The resistive indices in patients with elevated serum creatinine, BUN, proteinuria, and systolic blood pressure levels were statistically significantly higher than those in patients with normal levels (p<0.05). Also resistive indics in patients with retinopathy were higher than that in patients without retinopathy (p<0.05). But the ultrasound morphologic changes of kidney such as renal length, cortical eye-catching, and corticomedullarycontrast were not well correlated with clinical-laboratory data and resistive index. The resistive index of the kidney in conjunction with clinical-laboratory data in diabetics may be helpful in the evaluation of diabetic nephropathy

  14. Colour Doppler ultrasound of the penis

    Energy Technology Data Exchange (ETDEWEB)

    Wilkins, C.J.; Sriprasad, S.; Sidhu, P.S. E-mail: paulsidhu@compuserve.com

    2003-07-01

    Because it is a superficial structure, the penis is ideally suited to ultrasound imaging. A number of disease processes, including Peyronie's disease, penile fractures and penile tumours, are clearly visualized with ultrasound. An assessment of priapism can also be made using spectral Doppler waveform technology. Furthermore, dynamic assessment of cavernosal arterial changes after pharmaco-stimulation allows diagnosis of arterial and venogenic causes for impotence. This pictorial review illustrates the range of diseases encountered with ultrasound of the penis.

  15. Doppler Lidar Wind Value-Added Product

    Energy Technology Data Exchange (ETDEWEB)

    Newsom, R. K. [DOE ARM Climate Research Facility, Washington, DC (United States); Sivaraman, C. [DOE ARM Climate Research Facility, Washington, DC (United States); Shippert, T. R. [DOE ARM Climate Research Facility, Washington, DC (United States); Riihimaki, L. D. [DOE ARM Climate Research Facility, Washington, DC (United States)

    2015-07-01

    Wind speed and direction, together with pressure, temperature, and relative humidity, are the most fundamental atmospheric state parameters. Accurate measurement of these parameters is crucial for numerical weather prediction. Vertically resolved wind measurements in the atmospheric boundary layer are particularly important for modeling pollutant and aerosol transport. Raw data from a scanning coherent Doppler lidar system can be processed to generate accurate height-resolved measurements of wind speed and direction in the atmospheric boundary layer.

  16. Doppler Lidar for Wind Measurements on Venus

    Science.gov (United States)

    Singh, Upendra N.; Emmitt, George D.; Yu, Jirong; Kavaya, Michael J.

    2010-01-01

    NASA Langley Research Center has a long history of developing 2-micron laser transmitter for wind sensing. With support from NASA Laser Risk Reduction Program (LRRP) and Instrument Incubator Program (IIP), NASA Langley Research Center has developed a state-of-the-art compact lidar transceiver for a pulsed coherent Doppler lidar system for wind measurement. The transmitter portion of the transceiver employs the high-pulse-energy, Ho:Tm:LuLiF, partially conductively cooled laser technology developed at NASA Langley. The transceiver is capable of 250 mJ pulses at 10 Hz. It is very similar to the technology envisioned for coherent Doppler lidar wind measurements from Earth and Mars orbit. The transceiver is coupled to the large optics and data acquisition system in the NASA Langley VALIDAR mobile trailer. The large optics consists of a 15-cm off-axis beam expanding telescope, and a full-hemispheric scanner. Vertical and horizontal vector winds are measured, as well as relative backscatter. The data acquisition system employs frequency domain velocity estimation and pulse accumulation. It permits real-time display of the processed winds and archival of all data. This lidar system was recently deployed at Howard University facility in Beltsville, Mary-land, along with other wind lidar systems. Coherent Doppler wind lidar ground-based wind measurements and comparisons with other sensors will be presented. A simulation and data product for wind measurement at Venus will be presented.

  17. Precise Doppler Monitoring of Barnard's Star

    CERN Document Server

    Choi, Jieun; Marcy, Geoffrey W; Howard, Andrew W; Fischer, Debra A; Johnson, John A; Isaacson, Howard; Wright, Jason T

    2012-01-01

    We present 248 precise Doppler measurements of Barnard's Star (Gl 699), the second nearest star system to Earth, obtained from Lick and Keck Observatories during 25 years between 1987 and 2012. The early precision was 20 \\ms{} but was 2 \\ms{} during the last 8 years, constituting the most extensive and sensitive search for Doppler signatures of planets around this stellar neighbor. We carefully analyze the 136 Keck radial velocities spanning 8 years by first applying a periodogram analysis to search for nearly circular orbits. We find no significant periodic Doppler signals with amplitudes above $\\sim$2 \\ms{}, setting firm upper limits on the minimum mass (\\msini) of any planets with orbital periods from 0.1 to 1000 days. Using a Monte Carlo analysis for circular orbits, we determine that planetary companions to Barnard's Star with masses above 2 \\mearth{} and periods below 10 days would have been detected. Planets with periods up to 2 years and masses above 10 \\mearth{} (0.03 \\mjup) are also ruled out. A sim...

  18. ULTRASSONOGRAFIA DOPPLER EM OBSTETRÍCIA DE PEQUENOS ANIMAIS: REVISÃO DE LITERATURA

    Directory of Open Access Journals (Sweden)

    Victor José Correia Santos

    2015-06-01

    Full Text Available Considering the recent advances in diagnostic imaging used in pets, Doppler ultrasonography is emerging as an important and suitable noninvasive tool for the assessment of blood flow, used for the study of the estrous cycle in bitches and queens, as well as diagnosis and monitoring of the pregnancy, on fetal viability study and on detection of malignancy in breast tissues in this species. On males, the studies about the use of Doppler technology in prostate and testicular tissues are brand new, nevertheless with great prospects for its applicability. Therefore, this review aims to describe the use of ultrasound Doppler technique in veterinary reproduction and obstetrics of small animals, as well as to show a brief background about the different presentation modes of Doppler technology, which can be used in veterinary medicine for pets. Considerando os recentes avanços em diagnóstico por imagem para animais de companhia, a ultrassonografia Doppler está se destacando como uma importante e adequada ferramenta não invasiva para a avaliação do fluxo sanguíneo, utilizada para o estudo do ciclo estral em cadelas e gatas, assim como no diagnóstico e acompanhamento da gestação, no estudo da viabilidade fetal e na detecção da malignidade em tecidos mamários nestas espécies. Em machos, os estudos com a técnica Doppler em tecidos prostáticos e testiculares são recentes, com grandes perspectivas para sua aplicabilidade. Dessa forma, esta revisão tem como objetivo descrever o uso da técnica de ultrassonografia Doppler em reprodução e obstetrícia veterinária de pequenos animais, além de trazer um breve histórico a respeito dos diferentes modos de apresentação da tecnologia, que podem ser utilizadas em medicina veterinária de animais de companhia.

  19. Doppler effect in resonant photoemission from SF6: correlation between Doppler profile and Auger emission anisotropy.

    Science.gov (United States)

    Kitajima, M; Ueda, K; De Fanis, A; Furuta, T; Shindo, H; Tanaka, H; Okada, K; Feifel, R; Sorensen, S L; Gel'mukhanov, F; Baev, A; Agren, H

    2003-11-21

    Fragmentation of the SF6 molecule upon F 1s excitation has been studied by resonant photoemission. The F atomiclike Auger line exhibits the characteristic Doppler profile that depends on the direction of the photoelectron momentum relative to the polarization vector of the radiation as well as on the photon energy. The measured Doppler profiles are analyzed by the model simulation that takes account of the anisotropy of the Auger emission in the molecular frame. The Auger anisotropy extracted from the data decreases with an increase in the F-SF5 internuclear distance.

  20. Doppler-compensated three-photon electromagnetically induced transparency

    CERN Document Server

    Carr, Christopher; Sargsyan, Armen; Sarkisyan, David; Adams, Charles S; Weatherill, Kevin J

    2012-01-01

    We demonstrate Doppler-compensated bright and dark states in a resonant four-level atomic system. The spectral features are the result of electromagnetically induced transparency (EIT) and absorption (EIA) and are sub-Doppler due to the compensation of Doppler shifts with AC Stark shifts. We demonstrate the effect using a three-photon cascade system to Rydberg states in Cs vapor, however, the results apply to any four-level cascade or N-type system.

  1. Analysis on rotational Doppler Effect based on modal expansion method

    CERN Document Server

    Zhou, Hailong; Zhang, Pei; Zhang, Xinliang

    2015-01-01

    We theoretically investigate the optical rotational Doppler Effect using modal expansion method. We find that the frequency shift content is only determined by the surface of spinning object and the reduced Doppler shift is linear to the change of mode index. The theoretical model makes us better understand the physical processes of rotational Doppler Effect. It can provide theoretical guidance for many related applications, such as detection of rotating bodies, detection of OAM and frequency shift.

  2. New insights from inside-out Doppler tomography

    CERN Document Server

    Kotze, Enrico J

    2015-01-01

    We present preliminary results from our investigation into using an 'inside-out' velocity space for creating a Doppler tomogram. The aim is to transpose the inverted appearance of the Cartesian velocity space used in normal Doppler tomography. In a comparison between normal and inside-out Doppler tomograms of cataclysmic variables, we show that the inside-out velocity space has the potential to produce new insights into the accretion dynamics in these systems.

  3. Range-instantaneous Doppler imaging of inverse synthetic aperture sonar

    Institute of Scientific and Technical Information of China (English)

    XU Jia; JIANG Xingzhou; TANG Jingsong

    2003-01-01

    Because the existing range-Doppler algorithm in inverse synthetic aperture sonar (ISAS) is based on target model of uniform motion, it may be invalidated for maneuvering targets due to the time-varying changes of both individual scatter′s Doppler and imaging projection plane. To resolve the problem, a new range-instantaneous Doppler imaging method is proposed for imaging maneuvering targets based on time-frequency analysis. The proposed approach is verified using real underwater acoustic data.

  4. Influence of Doppler Bin Width on GNSS Detection Probabilities

    CERN Document Server

    Geiger, Bernhard C

    2011-01-01

    The acquisition stage in GNSS receivers determines Doppler shifts and code phases of visible satellites. Acquisition is thus a search in two continuous dimensions, where the digital algorithms require a partitioning of the search space into cells. We present analytic expressions for the acquisition performance depending on the partitioning of the Doppler frequency domain. In particular, the impact of the number and width of Doppler bins is analyzed. The presented results are verified by simulations.

  5. Reexamination of the Doppler effect through Maxwell's equations.

    Science.gov (United States)

    Guo, Wei; Aktas, Yildirim

    2012-08-01

    In this work, the electric field emitted from a moving source, an electric point dipole, is analyzed for the purpose of illustrating the physics behind the Doppler effect. It is found that if the (translational) motion of the source is nonrelativistic, the Doppler effect is realized in two steps: the motion of the source first causes the dyadic Green function associated with the electric field to acquire an oscillation frequency in the far-field region of the source, and then the frequency leads to the Doppler effect. It is also demonstrated that the Doppler effect is observable only in the far-field region of the source.

  6. EUV Doppler Imaging for CubeSat Platforms Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Mature the design and fabricate the Flare Initiation Doppler Imager (FIDI) instrument to demonstrate low-spacecraft-resource EUV technology (most notably,...

  7. Evaluating Peripheral Vascular Injuries: Is Color Doppler Enough for Diagnosis?

    Directory of Open Access Journals (Sweden)

    Mohd Lateef Wani

    2014-03-01

    Full Text Available Background:: Vascular injury poses a serious threat to limb and life. Thus, diagnosis should be made immediately with minimally invasive methods. Doppler is a good aid in diagnosis of vascular injury. Methods:: The present prospective study was conducted on 150 patients who presented with soft signs (the signs which are suggestive but not confirmatory of vascular injury. They were subjected to color Doppler examination before exploration. The patients with the features of vascular injury on color Doppler were subjected to exploration. On the other hand, those who had normal Doppler were subjected to CT- angiography. Then, the findings of the exploration were matched with those of color Doppler. The data were analyzed using the SPSS statistical software. Results:: Out of the 150 Doppler examinations, 110 (73.33% were reported as positive, while 40 were reported as negative for vascular injury. These were subjected to CT-angiography and seven of them had the features of vascular injury on CT-angiography. All the patients with positive Doppler or CT angiography findings were subjected to exploration. Doppler had a sensitivity of 94% and specificity of 82.5% in diagnosis of vascular injury using Binary classification test. Conclusions:: Color Doppler is an easily available, reliable, and handy method of diagnosing a vascular injury. It has a very high sensitivity and specificity in diagnosis of vascular injuries.

  8. Burst Format Design for Optimum Joint Estimation of Doppler-Shift and Doppler-Rate in Packet Satellite Communications

    Directory of Open Access Journals (Sweden)

    Luca Giugno

    2007-05-01

    Full Text Available This paper considers the problem of optimizing the burst format of packet transmission to perform enhanced-accuracy estimation of Doppler-shift and Doppler-rate of the carrier of the received signal, due to relative motion between the transmitter and the receiver. Two novel burst formats that minimize the Doppler-shift and the Doppler-rate Cramér-Rao bounds (CRBs for the joint estimation of carrier phase/Doppler-shift and of the Doppler-rate are derived, and a data-aided (DA estimation algorithm suitable for each optimal burst format is presented. Performance of the newly derived estimators is evaluated by analysis and by simulation, showing that such algorithms attain their relevant CRBs with very low complexity, so that they can be directly embedded into new-generation digital modems for satellite communications at low SNR.

  9. Mobile fiber-optic laser Doppler anemometer.

    Science.gov (United States)

    Stieglmeier, M; Tropea, C

    1992-07-20

    A laser Doppler anemometer (LDA) has been developed that combines the compactness and low power consumption of laser diodes and avalanche photodiodes with the flexibility and possibility of miniaturization by using fiber-optic probes. The system has been named DFLDA for laser diode fiber LDA and is especially suited for mobile applications, for example, in trains, airplanes, or automobiles. Optimization considerations of fiber-optic probes are put forward and several probe examples are described in detail. Measurement results from three typical applications are given to illustrate the use of the DFLDA. Finally, a number of future configurations of the DFLDA concept are discussed.

  10. Neutral wind results from TIMED Doppler interferometer

    Science.gov (United States)

    Killeen, T.; Gablehouse, R.; Gell, D.; Johnson, R.; Niciejewski, R.; Ortland, D.; Wu, Q.; Skinner, W.; Solomon, S.; Kafkalidis, J.

    2003-04-01

    Since the launch of the NASA Thermosphere-Ionosphere-Mesosphere Energetics and Dynamics (TIMED) satellite in December 2001, the TIMED Doppler Interferometer (TIDI) has been collecting lower thermosphere and mesospheric data for over a year. After adjustments to the spectral sampling scheme and operational mode, the instrument has been optimized. Efforts have also been made to improve the instrument performance. Preliminary neutral winds from O2 (0-0) have been analyzed. Tidal features and their seasonal variation are shown clearly in the wind data, which are quantitatively consistent with model prediction. We will report our progress on these efforts.

  11. [Color Doppler sonography of focal abdominal lesions].

    Science.gov (United States)

    Licanin, Zoran; Lincender, Lidija; Djurović, V; Salihefendić, Nizama; Smajlović, Fahrudin

    2004-01-01

    Color Doppler sonography (CDS--spectral, color and power), harmonic imaging techniques (THI, PHI), possibility of 3D analysis of picture, usage of contrast agents, have raised the values of ultrasound as a diagnostic method to a very high level. THI--non-linear gray scale modality, is based on the processing of higher reflected frequencies, that has improved a picture resolution, which is presented with less artifacts and limiting effects of obesity and gases. Ultrasound contrast agents improve analysis of micro and macro circulation of the examined area, and with the assessment of velocity of supply in ROI (wash in), distribution and time of signal weakening (wash out), are significantly increasing diagnostic value of ultrasound. Besides the anatomical and topographic presentation of examined region (color, power), Color Doppler sonography gives us haemodynamic-functional information on vascularisation of that region, as well as on pathologic vascularisation if present. Avascular aspect of a focal pathologic lesion corresponds to a cyst or haematoma, while coloration and positive spectral curve discover that anechogenic lesions actually represents aneurysms, pseudoaneurysms or AVF. In local inflammatory lesion, abscess in an acute phase, CDS shows first increased, and then decreased central perfusion, while in a chronic phase, a pericapsular vascularisation is present. Contribution of CDS in differentiation of hepatic tumors (hemangioma, HCC and metastasis) is very significant. Central color dots along the peripheral blood vessels and the blush phenomenon are characteristics of capillary hemangioma, peritumoral vascular ring "basket" of HCC, and "detour" sign of metastasis. The central artery, RI from 0.45 to 0.60 and radial spreading characterize FNH. Hepatic adenoma is characterized by an intratumoral vein, and rarely by a vascular hallo. Further on, blood velocity in tumor defined by Color Doppler, distinguishes malignant from benign lesion, where 40 cm/s is a

  12. Applications of Doppler optical coherence tomography

    Science.gov (United States)

    Xu, Zhiqiang

    A major development in biomedical imaging in the last decade has been optical coherence tomography (OCT). This technique enables microscale resolution, depth resolved imaging of the detailed morphology of transparent and nontransparent biological tissue in a noncontact and quasi-noninvasive way. In the first part of this dissertation, we will describe the development and the performance of our home-made OCT systems working with different wavelength regions based on free-space and optical fiber Michelson interferometers. The second part will focus on Doppler OCT (DOCT), an important extension of OCT, which enables the simultaneous evaluation of the structural information and of the fluid flow distribution at a localized position beneath the sample surface. Much effort has been spent during the past few years in our laboratory aimed at providing more accurate velocity measurements with an extended dynamic range. We also applied our technique in different research areas such as microfluidics and hemodynamics. Investigations on the optical properties of the biological tissues (such as absorption and scattering) corresponding to different center wavelengths, have been performed in our laboratory. We used a 10 femtosecond Ti:sapphire laser centered at about 810 nm associated with a free-space Michelson interferometer. The infrared sources were centered at about 1310 and 1560 nm with all-fiber interferometers. Comparative studies using three different sources for several in vitro biological tissues based on a graphical method illustrated how the optical properties affect the quality of the OCT images in terms of the penetration depth and backscattering intensity. We have shown the advantage of working with 810-nm emission wavelength for good backscattering amplitude and contrast, while sources emitting at 1570 nm give good penetration depth. The 1330-nm sources provide a good compromise between the two. Therefore, the choice of the source will ultimately determine the

  13. Doppler spectral characteristics of infrainguinal vein bypasses

    DEFF Research Database (Denmark)

    Nielsen, Tina G; von Jessen, F; Sillesen, H;

    1993-01-01

    With the aim of assessing the velocity profile of femoropopliteal and femorocrural vein bypasses, 128 patients undergoing infrainguinal vein bypass surgery entered a postoperative Duplex surveillance protocol, which included clinical assessment and Duplex scanning, using Doppler spectral analysis...... of arteriovenous fistulas the initially antegrade diastolic velocity was replaced by a retrograde flow within 3 months, whereas a forward flow in diastole was sustained in grafts with patent fistulas. Abnormal Duplex findings in 31 patients led to angiography and revision in 13 cases. Four revised grafts failed...

  14. Check list Doppler and duplex sonography. 4. rev. ed.; Checkliste Doppler- und Duplexsonografie

    Energy Technology Data Exchange (ETDEWEB)

    Kopp, Helmut [MED-Facharztzentrum, Mainz (Germany). Praxis fuer Gefaessmedizin; Ludwig, Malte [Benedictus Krankenhaus Tutzing (Germany). Gefaesszentrum

    2012-11-01

    Check list Doppler and duplex sonography includes 4 parts: (1) Basic information: technical fundamentals, equipment premises, hemodynamics. (2) Flow schemata and pitfalls. (3) Special vascular regions: arteries in the upper and lower extremities, veins in the upper and lower extremities, abdominal arteries, abdominal veins, ex-cranial brain sustaining arteries, intra-cranial brain sustaining arteries. (4) Attachment: diagnostic criteria and case studies.

  15. Cognitive dysfunction in congestive heart failure: transcranial Doppler evidence of microembolic etiology Disfunção cognitiva na insuficiência cardíaca congestiva: evidência de etiologia microembólica ao Doppler transcraniano

    Directory of Open Access Journals (Sweden)

    Pedro A.P. Jesus

    2006-06-01

    Full Text Available Cognitive symptoms are common in patients with congestive heart failure (CHF and are usually attributed to low cerebral blood flow. In the present study, we aimed to evaluate global cognitive function (Mini Mental State Exam MMSE in relation to both cardiac function (evaluated by echocardiogram and cerebrovascular hemodynamics (evaluated by transcranial Doppler TCD in CHF patients. In 83 patients studied, no correlation was found between echocardiographic parameters and MMSE scores. In contrast, a significant correlation was found between right middle cerebral artery (RMCA mean flow velocity and MMSE score (r=0.231 p=0.039, as well as between RMCA pulsatility index and MMSE score (r s= -0.292 p=0.015. After excluding patients with a previous history of stroke, only RMCA pulsatility index correlated with MMSE score (r s=-0,314 p=0,007. The relationship between high cerebrovascular resistance and worse cognitive scores suggest that microembolism may be responsible for a significant proportion of cognitive symptoms in CHF patients.Sintomas cognitivos são comuns em pacientes com insuficiência cardíaca congestiva (ICC e são geralmente atribuídos a um regime de baixo fluxo sanguíneo cerebral. Neste estudo, objetivamos avaliar a função cognitiva global (Mini Exame do Estado Mental MEEM em pacientes com ICC e sua relação com o grau de disfunção cardíaca (avaliada pelo ecocardiograma e a hemodinâmica cerebral (avaliada pelo Doppler transcraniano DTC. Em 83 pacientes estudados, nenhuma correlação foi encontrada entre a pontuação no MEEM e parâmetros ecocardiográficos. Em contraste, uma correlação significativa foi encontrada entre a velocidade média na artéria cerebral média direita (ACMD e a pontuação no MEEM (r=0,231 p=0,039, assim como entre o índice de pulsatilidade na ACMD e a pontuação no MEEM (r s=-0,292 p=0,015. Após excluir pacientes com histórico prévio de acidente vascular encefálico, somente o índice de

  16. Doppler ultrasound scan during normal gestation: umbilical circulation; Ecografia Doppler en la gestacion normal: circulacion umbilical

    Energy Technology Data Exchange (ETDEWEB)

    Ruiz, T.; Sabate, J.; Martinez-Benavides, M. M.; Sanchez-Ramos, J. [Hospital Virgen Macarena. Sevilla (Spain)

    2002-07-01

    To determine normal umbilical circulation patterns by means of Doppler ultrasound scan in a healthy gestating population without risk factors and with normal perinatal results, and to evaluate any occurring modifications relative to gestational age by obtaining records kept during pregnancy. One hundred and sixteen pregnant women carrying a single fetus have been studied. These women had no risk factors, with both clinical and analytical controls, as well as ultrasound scans, all being normal. There were performed a total of 193 Doppler ultrasound scans between weeks 15 and 41 of gestation, with blood-flow analysis in the arteries and vein of the umbilical cord. The obtained information was correlated with parameters that evaluate fetal well-being (fetal monitoring and/or oxytocin test) and perinatal result (delivery type, birth weight, Apgar score). Statistical analysis was performed with the programs SPSS 6.0.1 for Windows and EPIINFO 6.0.4. With pulsed Doppler, the umbilical artery in all cases demonstrated a biphasic morphology with systolic and diastolic components and without retrograde blood flow. As the gestation period increased, there was observed a progressive decrease in resistance along with an increase in blood-flow velocity during the diastolic phase. The Doppler ultrasound scan is a non-invasive method that permits the hemodynamic study of umbilical blood circulation. A knowledge of normal blood-flow signal morphology, as well as of the normal values for Doppler indices in relation to gestational age would permit us to utilize this method in high-risk pregnancies. (Author) 30 refs.

  17. Initial Results from the XUV Doppler Telescope

    Science.gov (United States)

    Kano, R.; Hara, H.; Kobayashi, K.; Kumagai, K.; Nagata, S.; Sakao, T.; Shimizu, T.; Tsuneta, S.; Yoshida, T.

    We developed a unique telescope to obtain simultaneous XUV images and the velocity maps by measuring the line-of-sight Doppler shifts of the Fe XIV 211A&ring line (T = 1.8 MK): the Solar XUV Doppler Telescope (hereafter XDT). The telescope was launched by the Institute of Space and Astronautical Science with the 22nd S520 rocket on January 31, 1998, and took 14 XUV whole sun images during 5 minutes. Simultaneous observations of XDT with Yohkoh (SXT), SOHO (EIT, CDS, LASCO and MDI) were successfully carried out. The images taken with EIT, XDT and SXT are able to cover the wide temperature ranging from 1 to 10 MK, and clearly show the multi-temperature nature of the solar corona. Indeed, we notice that both the cool (1-2 MK) loops observed with EIT and XDT, and the hot (>3 MK) loops observed with SXT exist in the same active regions but in a spatially exclusive way. The XDT red-blue ratio between longer- and shorter-wavelength bands of Fe XIV 211A&ring line indicates a possible down-flow of 1.8 MK plasma near the footpoints of multiple cool loops

  18. An elementary approach to the gravitational Doppler shift

    Science.gov (United States)

    Wörner, C. H.; Rojas, Roberto

    2017-01-01

    In college physics courses, treatment of the Doppler effect is usually done far from the first introduction to kinematics. This paper aims to apply a graphical treatment to describe the gravitational redshift, by considering the Doppler effect in two accelerated reference frames and exercising the equivalence principle. This approach seems appropriate to discuss with beginner students and could serve to enrich the didactic processes.

  19. A Rayleigh Doppler Frequency Estimator Derived from Maximum Likelihood Theory

    DEFF Research Database (Denmark)

    Hansen, Henrik; Affes, Sofiene; Mermelstein, Paul

    1999-01-01

    Reliable estimates of Rayleigh Doppler frequency are useful for the optimization of adaptive multiple access wireless receivers.The adaptation parameters of such receivers are sensitive to the amount of Doppler and automatic reconfiguration to the speed of terminalmovement can optimize cell...

  20. A Rayleigh Doppler frequency estimator derived from maximum likelihood theory

    DEFF Research Database (Denmark)

    Hansen, Henrik; Affes, Sofiéne; Mermelstein, Paul

    1999-01-01

    Reliable estimates of Rayleigh Doppler frequency are useful for the optimization of adaptive multiple access wireless receivers. The adaptation parameters of such receivers are sensitive to the amount of Doppler and automatic reconfiguration to the speed of terminal movement can optimize cell...

  1. Measurement of depth of burns by laser Doppler perfusion imaging

    NARCIS (Netherlands)

    Droog, E.J.; Steenbergen, W.; Sjöberg, F.

    2001-01-01

    Laser Doppler perfusion imaging (LDPI), is a further development in laser Doppler flowmetry (LDF). Its advantage is that it enables assessment of microvascular blood flow in a predefined skin area rather than, as for LDF, in one place. In many ways this method seems to be more promising than LDF in

  2. Compressive sensing for high resolution profiles with enhanced Doppler performance

    NARCIS (Netherlands)

    Anitori, L.; Hoogeboom, P.; Chevalier, F. Le; Otten, M.P.G.

    2012-01-01

    In this paper we demonstrate how Compressive Sensing (CS) can be used in pulse-Doppler radars to improve the Doppler performance while preserving range resolution. We investigate here two types of stepped frequency waveforms, the coherent frequency bursts and successive frequency ramps, which can be

  3. The value of Doppler ultrasound in cirrhosis and portal hypertension

    NARCIS (Netherlands)

    Kok, T; van der Jagt, EJ; Haagsma, EB; Bijleveld, CMA; Jansen, PLM; Boeve, WJ

    1999-01-01

    Background: Cirrhosis and portal hypertension affect the flow profile of the liver vasculature. In these conditions Doppler ultrasound can provide important information on the hemodynamics of the portal venous system, the hepatic artery and the hepatic veins. Methods: The value of Doppler ultrasound

  4. Micro-Doppler classification of riders and riderless horses

    Science.gov (United States)

    Tahmoush, David

    2014-05-01

    Micro-range Micro-Doppler can be used to isolate particular parts of the radar signature, and in this case we demonstrate the differences in the signature between a walking horse versus a walking horse with a rider. Using micro-range micro-Doppler, we can distinguish the radar returns from the rider as separate from the radar returns of the horse.

  5. Functional Doppler optical coherence tomography for cortical blood flow imaging

    Science.gov (United States)

    Yu, Lingfeng; Liu, Gangjun; Nguyen, Elaine; Choi, Bernard; Chen, Zhongping

    2010-02-01

    Optical methods have been widely used in basic neuroscience research to study the cerebral blood flow dynamics in order to overcome the low spatial resolution associated with magnetic resonance imaging and positron emission tomography. Although laser Doppler imaging and laser speckle imaging can map out en face cortical hemodynamics and columns, depth resolution is not available. Two-photon microscopy has been used for mapping cortical activity. However, flow measurement requires fluorescent dye injection, which can be problematic. The noninvasive and high resolution tomographic capabilities of optical coherence tomography make it a promising technique for mapping depth resolved cortical blood flow. Here, we present a functional Doppler optical coherence tomography (OCT) imaging modality for quantitative evaluation of cortical blood flow in a mouse model. Fast, repeated, Doppler OCT scans across a vessel of interest were performed to record flow dynamic information with a high temporal resolution of the cardiac cycles. Spectral Doppler analysis of continuous Doppler images demonstrates how the velocity components and longitudinally projected flow-volume-rate change over time, thereby providing complementary temporal flow information to the spatially distributed flow information of Doppler OCT. The proposed functional Doppler OCT imaging modality can be used to diagnose vessel stenosis/blockage or monitor blood flow changes due to pharmacological agents/neuronal activities. Non-invasive in-vivo mice experiments were performed to verify the capabilities of function Doppler OCT.

  6. New Approaches For Asteroid Spin State and Shape Modeling From Delay-Doppler Radar Images

    Science.gov (United States)

    Raissi, Chedy; Lamee, Mehdi; Mosiane, Olorato; Vassallo, Corinne; Busch, Michael W.; Greenberg, Adam; Benner, Lance A. M.; Naidu, Shantanu P.; Duong, Nicholas

    2016-10-01

    Delay-Doppler radar imaging is a powerful technique to characterize the trajectories, shapes, and spin states of near-Earth asteroids; and has yielded detailed models of dozens of objects. Reconstructing objects' shapes and spins from delay-Doppler data is a computationally intensive inversion problem. Since the 1990s, delay-Doppler data has been analyzed using the SHAPE software. SHAPE performs sequential single-parameter fitting, and requires considerable computer runtime and human intervention (Hudson 1993, Magri et al. 2007). Recently, multiple-parameter fitting algorithms have been shown to more efficiently invert delay-Doppler datasets (Greenberg & Margot 2015) - decreasing runtime while improving accuracy. However, extensive human oversight of the shape modeling process is still required. We have explored two new techniques to better automate delay-Doppler shape modeling: Bayesian optimization and a machine-learning neural network.One of the most time-intensive steps of the shape modeling process is to perform a grid search to constrain the target's spin state. We have implemented a Bayesian optimization routine that uses SHAPE to autonomously search the space of spin-state parameters. To test the efficacy of this technique, we compared it to results with human-guided SHAPE for asteroids 1992 UY4, 2000 RS11, and 2008 EV5. Bayesian optimization yielded similar spin state constraints within a factor of 3 less computer runtime.The shape modeling process could be further accelerated using a deep neural network to replace iterative fitting. We have implemented a neural network with a variational autoencoder (VAE), using a subset of known asteroid shapes and a large set of synthetic radar images as inputs to train the network. Conditioning the VAE in this manner allows the user to give the network a set of radar images and get a 3D shape model as an output. Additional development will be required to train a network to reliably render shapes from delay-Doppler

  7. Multiscale modeling to evaluate proposed space-based Doppler lidar sampling strategies

    Science.gov (United States)

    Emmitt, G. D.

    1985-01-01

    A proposal has been made to place a pulsed Doppler lidar on a space platform (Huffaker, et al., 1980; Emmitt, 1982) in a low earth orbit (200 to 800 km) to measure the atmospheric winds with a spatial resolution commensurate with the current continental rawinsonde network density - i.e., 300 to 500 km resolution. In the case of the space-based doppler lidar, the full range of space scales applies. Single shot pulses with dimensions of 10 x 1000 meters are used to sample areas 100,000 x 100,000 meters to resolved mass flow structure with wavelength of 1 million meters. Simulation studies, therefore, require an equally broad range of atmospheric models. A general circulation model is appropriate to answer questions regarding the impact of a global wind measuring system upon synoptic forecasts. Since the nominal resolution of the spacebased system is expected to be a few 100's of kilometers, then a numerical model with mesoscale dynamics is required. The meaning of an average Doppler shift within a laser pulse volume must be evaluated with models of turbulent/convective scale motions and aerosol gradients. Examples of how models on all these scales have been applied in an ongoing simulation study are presented. In particular, the uncertainties in a mesoscale wind estimate are separated into those arising from pulse scale variances and those due to sample distribution within a prescribed resolution volume. Trade-offs between accuracy and representativeness are discussed in terms of the model results.

  8. Transcranial power M-mode Doppler ultrasound for diagnosis of patent foramen ovale

    Science.gov (United States)

    Moehring, Mark; Spencer, Merrill

    2005-04-01

    Patent foramen ovale (PFO) is a right-to-left shunt (RLS) which communicates blood from the right to left atrium of the heart. PFO has been associated with stroke and, more recently, with migraine headache. Diagnosis of RLS can be accomplished effectively with transcranial power M-mode Doppler ultrasound (PMD). PMD is a modality which can be performed without the sedation required by the more invasive diagnostic technique using transesophageal echocardiography. PMD for this application consists of 2 MHz pulse Doppler ultrasound with placement of sample gates at 2 mm intervals along the single-transducer beam axis, and 8 kHz pulse repetition rate (PMD100M, Spencer Technologies). Doppler power versus depth is constructed every 4ms, using 33 sample gates. Bubble microemboli injected in the venous system and moving across a PFO present as high intensity tracks on a PMD image, as emboli transit from the heart to the brain and through the observed cerebral vasculature. Use of PMD in this context has been reported in the clinical literature [M. P. Spencer, M. A. Moehring, J. Jesurum et al, J. Neuroimaging 14, 342-349 (2004)]. This talk surveys the basic technical features of PMD for sensing PFO-related showers of bubble microemboli, and how these features provide clues to the severity of PFO.

  9. Use of GPS network data for HF Doppler measurements interpretation

    CERN Document Server

    Petrova, Inna R; Latypov, Ruslan R

    2014-01-01

    The method of measurement of Doppler frequency shift of ionospheric signal - HF Doppler technique - is one of well-known and widely used methods of ionosphere research. It allows to research various disturbances in the ionosphere. There are some sources of disturbances in the ionosphere. These are geomagnetic storms, solar flashes, metrological effects, atmospheric waves. This method allows to find out the influence of earthquakes, explosions and other processes on the ionosphere, which occur near to the Earth. HF Doppler technique has the high sensitivity to small frequency variations and the high time resolution, but interpretation of results is difficult. In this work we make an attempt to use GPS data for Doppler measurements interpretation. Modeling of Doppler frequency shift variations with use of TEC allows to separate ionosphere disturbances of medium scale.

  10. One way Doppler extractor. Volume 1: Vernier technique

    Science.gov (United States)

    Blasco, R. W.; Klein, S.; Nossen, E. J.; Starner, E. R.; Yanosov, J. A.

    1974-01-01

    A feasibility analysis, trade-offs, and implementation for a One Way Doppler Extraction system are discussed. A Doppler error analysis shows that quantization error is a primary source of Doppler measurement error. Several competing extraction techniques are compared and a Vernier technique is developed which obtains high Doppler resolution with low speed logic. Parameter trade-offs and sensitivities for the Vernier technique are analyzed, leading to a hardware design configuration. A detailed design, operation, and performance evaluation of the resulting breadboard model is presented which verifies the theoretical performance predictions. Performance tests have verified that the breadboard is capable of extracting Doppler, on an S-band signal, to an accuracy of less than 0.02 Hertz for a one second averaging period. This corresponds to a range rate error of no more than 3 millimeters per second.

  11. Embolic Doppler ultrasound signal detection via fractional Fourier transform.

    Science.gov (United States)

    Gençer, Merve; Bilgin, Gökhan; Aydın, Nizamettin

    2013-01-01

    Computerized analysis of Doppler ultrasound signals can aid early detection of asymptomatic circulating emboli. For analysis, physicians use informative features extracted from Doppler ultrasound signals. Time -frequency analysis methods are useful tools to exploit the transient like signals such as Embolic signals. Detection of discriminative features would be the first step toward automated analysis of embolic Doppler ultrasound signals. The most problematic part of setting up emboli detection system is to differentiate embolic signals from confusing similar wave-like patterns such as Doppler speckle and artifacts caused by tissue movement, probe tapping, speaking etc. In this study, discrete version of fractional Fourier transform is presented as a solution in the detection of emboli in digitized Doppler ultrasound signals. An accurate set of parameters are extracted using short time Fourier transform and fractional Fourier transform and the results are compared to reveal detection quality. Experimental results prove the efficiency of fractional Fourier transform in which discriminative features becomes more evident.

  12. Limits on Planetary Companions from Doppler Surveys of Nearby Stars

    CERN Document Server

    Howard, Andrew W

    2016-01-01

    Most of our knowledge of planets orbiting nearby stars comes from Doppler surveys. For spaced-based, high-contrast imaging missions, nearby stars with Doppler-discovered planets are attractive targets. The known orbits tell imaging missions where and when to observe, and the dynamically-determined masses provide important constraints for the interpretation of planetary spectra. Quantifying the set of planet masses and orbits that could have been detected will enable more efficient planet discovery and characterization. We analyzed Doppler measurements from Lick and Keck Observatories collected by the California Planet Survey. We focused on stars that are likely targets for three space-based planet imaging mission concepts studied by NASA--WFIRST-AFTA, Exo-C, and Exo-S. The Doppler targets are primarily F8 and later main sequence stars, with observations spanning 1987-2014. We identified 76 stars with Doppler measurements from the prospective mission target lists. We developed an automated planet search and a ...

  13. Doplerovi brodski navigacioni brzinomjeri / Maritime navigational Doppler logs

    Directory of Open Access Journals (Sweden)

    Milovan Unković

    2006-01-01

    Full Text Available Doplerovi navigacioni brodski brzinomjeri rade na principu Doplerovog efekta. Doplerov predajni projektor emituje snop ultrazvučnih vibracija u vodi, a drugi (ili isti projektor prima odbijeni signal od dna ili od sloja vode. U ovom radu opisana je teorija Doplerovog efekta, primjena te teorije na brodskim brzinomjerima, konstrukcija i karakteristike savremenih Doplerovih brzinomjera. / The Doppler maritime navigational logs are based on measurement of the Doppler effect. A Doppler log transmitting transducer emits beam of sound vibration in the water, and a second (or the same transducer receives the echo from the sea bed or -water layer. In this article describes theory of Doppler effect, using this theory in maritime logs, construction and performance of modern Doppler logs.

  14. Doppler-cancelled response to VLF gravitational waves

    Science.gov (United States)

    Caporali, A.

    1981-01-01

    The interaction of long periodic gravitational waves with a three link microwave system known as the Doppler Cancelling System is discussed. This system, which was developed for a gravitational redshift experiment, uses one-way and two-way Doppler informatin to construct the beat signal of two reference oscillators moving with respect to each other. The geometric optics approximation is used to derive the frequency shift produced on a light signal propagating in a gravitational wave space-time. The signature left on the Doppler-cancelled beat by burst and continuous gravitational waves is analyzed. A comparison is made between the response to gravitational waves of the Doppler Cancelling System and that of a Doppler tracking system which employs two-way, round-trip radio waves. A three-fold repetition of the gravitational wave form is found to be a common feature of the response functions of both systems. These two functions otherwise exhibit interesting differences.

  15. Wave heave spectra from radar Doppler velocities at extreme low grazing angles

    Science.gov (United States)

    Flampouris, Stylianos; Seemann, Joerg; Ziemer, Friedwart

    2013-04-01

    The ground based microwaves radar systems are used for the measurement of the sea surface phenomena for more than three decades. By calibrating the radar cross section, the extraction of the wave spectral characteristics is a well established empirical methodology (Ziemer et al. 1993) with theoretical background (Alpers et al. 1978) and commercial applications (Nieto et al. 2004), which provides comparable measurements with wave buoys. The transfer function is necessary mainly due to the imaging mechanisms, like shadowing and or tilt modulation (Seemann 1997). To avoid the obligatory use of a transfer function, instead of the radar cross section, the Doppler velocity, which is a direct measurement of the sea surface, could be used. In this poster, a methodology for the determination of heave spectra based on time series of Doppler velocity acquired under extreme low grazing angle conditions, is presented. We prove that for the determination of the peak frequency the analysis of the binary shadow mask is sufficient, but for the calculation of the spectral density, a transfer function is necessary because of the gaps of the time series due to the shadowing. The physical and technical limitations are discussed and the algorithm is tested with in situ measurements from the coastal area of German Bight. Both properties, peak frequency and significant wave height from radar, have significant correlation with buoy measurements.

  16. TIMED Doppler Interferometer: Overview and recent results

    Science.gov (United States)

    Killeen, T. L.; Wu, Q.; Solomon, S. C.; Ortland, D. A.; Skinner, W. R.; Niciejewski, R. J.; Gell, D. A.

    2006-10-01

    The Thermosphere-Ionosphere-Mesosphere Energetics and Dynamics (TIMED) satellite carries a limb-scanning Fabry-Perot interferometer designed to perform remote-sensing measurements of upper atmosphere winds and temperatures globally. This instrument is called the TIMED Doppler Interferometer, or TIDI. This paper provides an overview of the TIDI instrument design, on-orbit performance, operational modes, data processing and inversion procedures, and a summary of wind results to date. Daytime and nighttime neutral winds in the mesosphere and lower thermosphere/ionosphere (MLTI) are measured on TIDI using four individual scanning telescopes that collect light from various upper atmosphere airglow layers on both the cold and warm sides of the high-inclination TIMED spacecraft. The light is spectrally analyzed using an ultrastable plane etalon Fabry-Perot system with sufficient spectral resolution to determine the Doppler line characteristics of atomic and molecular emissions emanating from the MLTI. The light from all four telescopes and from an internal calibration field passes through the etalon and is combined on a single image plane detector using a Circle-to-Line Interferometer Optic (CLIO). The four geophysical fields provide orthogonal line-of-sight measurements to either side of the satellite's path and these are analyzed to produce altitude profiles of vector winds in the MLTI. The TIDI wind measurements presented here are from the molecular oxygen (0-0) band, covering the altitude region 85-105 km. The unique TIDI design allows for more extended local time coverage of wind structures than previous wind-measuring instruments from high-inclination satellites. The TIDI operational performance has been nominal except for two anomalies: (1) higher than expected background white light caused by a low-level light leak and (2) ice deposition on cold optical surfaces. Both anomalies are well understood and the instrumental modes and data analysis techniques have been

  17. Universal miniaturized signal evaluation for laser doppler anemometers; Universelle Miniatur-Signalauswertung fuer die Laser Doppler Anemometrie

    Energy Technology Data Exchange (ETDEWEB)

    Wnuck, J. von; Strunck, V.; Dopheide, D.

    1994-01-01

    A laser doppler anemometer (LDA) is a contactless optical sensor for flow rate measurement. Interference of two laser beams generates a measuring volume with interference lines in the point of intersection. A particle moving through the measuring volume with a current scatters light modulated wiith the doppler frequency, which is received by a detector. The frequency of the doppler-modulated light is proportional to the velocity of the particle. The report describes the technical details of an electronic evaluation system for laser doppler signals in the time range using programmable gate arrays by Xilinix. (orig.) [Deutsch] Ein Laser Doppler Anemometer (LDA) ist ein beruehrungsloser optischer Sensor, der Stroemungsgeschwindigkeiten misst. Die Ueberlagerung zweier Laserstrahlen erzeugt im Schnittpunkt ein Messvolumen mit Inferenzstreifen. Ein Teilchen, das sich mit einer Stroemung durch das Messvolumen bewegt, streut mit der Doppelfrequenz des Doppler moduliertes Licht, das von einem Detektor empfangen wird. Die Frequenz des Doppler-modulierten Lichts ist der Geschwindigkeit des Teilchens proportional. Hier wird die technische Realisierung einer Auswerteelektronik fuer Laser Doppler Signale im Zeitbereich mit programmierbaren Gate-Arrays von Xilinx beschrieben. (orig.)

  18. Avaliação dos tumores hepáticos ao Doppler Doppler evaluation of liver tumors

    Directory of Open Access Journals (Sweden)

    Márcio Martins Machado

    2004-10-01

    Full Text Available Os avanços recentes na ultra-sonografia têm ampliado a possibilidade de detecção de tumores hepáticos. Isto tem auxiliado na perspectiva de melhora do prognóstico destes pacientes, à medida que novas técnicas terapêuticas têm surgido. Neste artigo os autores relatam achados ao Doppler que podem auxiliar na identificação e caracterização dos tumores hepáticos, avaliando dados do Doppler colorido, pulsado e do Doppler de amplitude ("power Doppler". Fazem, também, referência a novas modalidades de imagem, como o uso da harmônica.Recent advances in ultrasound have optimized the detection of liver tumors and helped to improve the prognosis of patients with this condition as newly developed and improved therapeutic modalities have been established. The authors review important Doppler findings which may help in the identification and characterization of some hepatic tumors through the evaluation of color Doppler, pulsed Doppler and power Doppler features. New imaging methods such as the use of harmonics imaging are also reviewed.

  19. Color Doppler US of superficial adenopathies; Il color Doppler nelle adenopatie superficiali

    Energy Technology Data Exchange (ETDEWEB)

    Giovagnorio, F. [Rome Univ. (Italy). 1. Cattedra di Radiologia

    1999-03-01

    Superficial lymph node are frequently involved in different diseases. Their location makes them suitable for effective assessment with high-resolution US and color Doppler has been recently suggested as a tool for increasing sensitivity in lymph node studies. Thus the author investigated the main vascular patterns detectable in abnormal superficial lymph nodes. [Italian] Numerosa malattie con natura differente coinvolgono i linfonodi superficiali: la localizzazione ne consente l'esplorazione con ecografia con alta risoluzione e lo studio mediante eco color Doppler e' stato proposto negli ultimi anni incontrando notevole sviluppo in tempi recenti. Scopo del lavoro e' illustrare il contributo personale nella definizione dei principali quadri riscontrabili nelle diverse adenopatie superficiali.

  20. Phase Doppler anemometry as an ejecta diagnostic

    Science.gov (United States)

    Bell, D. J.; Chapman, D. J.

    2017-01-01

    When a shock wave is incident on a free surface, micron sized pieces of the material can be ejected from that surface. Phase Doppler Anemometry (PDA) is being developed to simultaneously measure the sizes and velocities of the individual shock induced ejecta particles; providing an important insight into ejecta phenomena. The results from experiments performed on the 13 mm bore light gas gun at the Institute of Shock Physics, Imperial College London are presented. Specially grooved tin targets were shocked at pressures of up to 14 GPa, below the melt on release pressure, to generate ejecta particles. These experiments are the first time that PDA has been successfully fielded on dynamic ejecta experiments. The results and current state of the art of the technique are discussed along with the future improvements required to optimise performance and increase usability.

  1. Doppler cooling and trapping on forbidden transitions.

    Science.gov (United States)

    Binnewies, T; Wilpers, G; Sterr, U; Riehle, F; Helmcke, J; Mehlstäubler, T E; Rasel, E M; Ertmer, W

    2001-09-17

    Ultracold atoms at temperatures close to the recoil limit have been achieved by extending Doppler cooling to forbidden transitions. A cloud of (40)Ca atoms has been cooled and trapped to a temperature as low as 6 microK by operating a magnetooptical trap on the spin-forbidden intercombination transition. Quenching the long-lived excited state with an additional laser enhanced the scattering rate by a factor of 15, while a high selectivity in velocity was preserved. With this method, more than 10% of precooled atoms from a standard magnetooptical trap have been transferred to the ultracold trap. Monte Carlo simulations of the cooling process are in good agreement with the experiments.

  2. Microscale Heat Conduction Models and Doppler Feedback

    Energy Technology Data Exchange (ETDEWEB)

    Hawari, Ayman I. [North Carolina State Univ., Raleigh, NC (United States); Ougouag, Abderrafi [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2015-01-22

    The objective of this project is to establish an approach for providing the fundamental input that is needed to estimate the magnitude and time-dependence of the Doppler feedback mechanism in Very High Temperature reactors. This mechanism is the foremost contributor to the passive safety of gas-cooled, graphite-moderated high temperature reactors that use fuel based on Tristructural-Isotropic (TRISO) coated particles. Therefore, its correct prediction is essential to the conduct of safety analyses for these reactors. Since the effect is directly dependent on the actual temperature reached by the fuel during transients, the underlying phenomena of heat deposition, heat transfer and temperature rise must be correctly predicted. To achieve the above objective, this project will explore an approach that accounts for lattice effects as well as local temperature variations and the correct definition of temperature and related local effects.

  3. Role of transcranial Doppler in cerebrovascular disease

    Directory of Open Access Journals (Sweden)

    Amit A Kulkarni

    2016-01-01

    Full Text Available Transcranial Doppler (TCD is the only noninvasive modality for the assessment of real-time cerebral blood flow. It complements various anatomic imaging modalities by providing physiological-flow related information. It is relatively cheap, easily available, and can be performed at the bedside. It has been suggested as an essential component of a comprehensive stroke centre. In addition to its importance in acute cerebrovascular ischemia, its role is expanding in the evaluation of cerebral hemodynamics in various disorders of the brain. The “established” clinical indications for the use of TCD include cerebral ischemia, sickle cell disease, detection of right-to-left shunts, subarachnoid hemorrhage, periprocedural or surgical monitoring, and brain death. We present the role of TCD in acute cerebrovascular ischemia, sonothrombolysis, and intracranial stenosis.

  4. The recondite intricacies of Zeeman Doppler mapping

    CERN Document Server

    Stift, M J; Cowley, C R

    2011-01-01

    We present a detailed analysis of the reliability of abundance and magnetic maps of Ap stars obtained by Zeeman Doppler mapping (ZDM). It is shown how they can be adversely affected by the assumption of a mean stellar atmosphere instead of appropriate "local" atmospheres corresponding to the actual abundances in a given region. The essenceof the difficulties was already shown by Chandrasekhar's picket-fence model. The results obtained with a suite of Stokes codes written in the Ada programming language and based on modern line-blanketed atmospheres are described in detail. We demonstrate that the high metallicity values claimed to have been found in chemically inhomogeneous Ap star atmospheres would lead to local temperature structures, continuum and line intensities, and line shapes that differ significantly from those predicted by a mean stellar atmosphere. Unfortunately, past applications of ZDM have consistently overlooked the intricate aspects of metallicity with their all-pervading effects. The erroneou...

  5. Laser Doppler vibrometry: new ENT applications

    Science.gov (United States)

    Stasche, Norbert; Baermann, M.; Kempe, C.; Hoermann, Karl; Foth, Hans-Jochen

    1996-12-01

    Common audiometry often does not really allow a reliable and objective differential diagnosis of hearing disorders such as otosclerosis, adhesive otitis, ossicular interruption or tinnitus, even though several methods might be used complementarily. In recent years, some experimental studies on middle ear mechanics established laser Doppler vibrometry (LDV) as a useful method allowing objective measurement of human tympanic membrane displacement. The present study on LDV investigated the clinical use of this new method under physiological conditions. LDV proved to be a fast, reproducible, non-invasive and very sensitive instrument to characterize ear-drum vibrations in various middle ear dysfunctions, except in tinnitus patients. For future applications, improved optical characteristics of the vibrometer might result in a better differential diagnosis of subjective and objective tinnitus, otoacoustic emissions or Morbus Meniere.

  6. Correlation and Sequential Filtering with Doppler Measurements

    Institute of Scientific and Technical Information of China (English)

    WANGJianguo; HEPeikun; HANYueqiu; WUSiliang

    2004-01-01

    Two sequential filters are developed for Doppler radar measurements in the presence of correlation between range and range rate measurement errors. Two ideal linear measurement equations with the pseudo measurements are constructed via block-partitioned Cholesky factorization and the practical measurement equationswith the pseudo measurements are obtained through the direction cosine estimation and error compensation. The resulting sequential filters make the position measurement be possibly processed before the pseudo measurement and hence the more accurate direction cosine estimate can be obtained from the filtered position estimate rather than the predicted state estimate. The numerical simulations with different rangerange rate correlation coefficients show thatthe proposed two sequential filters are almost equivalent in performance but both superior to the conventional extended Kalman filter for different correlation coefficients.

  7. Fractal fluctuations in transcranial Doppler signals

    Science.gov (United States)

    West, B. J.; Zhang, R.; Sanders, A. W.; Miniyar, S.; Zuckerman, J. H.; Levine, B. D.

    1999-03-01

    Cerebral blood flow (CBF) velocity measured using transcranial Doppler ultrasonography (TCD) is not strictly constant, but has both a systematic and random component. This behavior may indicate that the axial blood flow in the middle cerebral artery is a chaotic process. Herein we use the relative dispersion, the ratio of the standard deviation to the mean, to show by systematically aggregating the data that the correlation in the beat-to-beat CBF time series is a modulated inverse power law. This scaling of the CBF time series indicates the existence of long-time memory in the underlying control process. We argue herein that the control system has allometric properties that enable it to maintain a relatively constant brain perfusion.

  8. The Doppler peaks from a generic defect

    CERN Document Server

    Magueijo, J

    1996-01-01

    We investigate which of the exotic Doppler peak features found for textures and cosmic strings are generic novelties pertaining to defects. We find that the ``out of phase'' texture signature is an accident. Generic defects, when they generate a secondary peak structure similar to inflation, apply to it an additive shift. It is not necessary for this shift to be ``out of phase''. We also show which factors are responsible for the absence of secondary oscillations found for cosmic strings. Within this general analysis we finally consider the conditions under which topological defects and inflation can be confused. It is argued that only \\Omega=1 inflation and a defect with a horizon size coherence length have a chance to be confused. Any other inflationary or defect model always differ distinctly. (To appear in the proceedings of the XXXIth Moriond meeting, ``Microwave Background Anisotropies'')

  9. Widefield laser doppler velocimeter: development and theory.

    Energy Technology Data Exchange (ETDEWEB)

    Hansche, Bruce David; Reu, Phillip L.; Massad, Jordan Elias

    2007-03-01

    The widefield laser Doppler velocimeter is a new measurement technique that significantly expands the functionality of a traditional scanning system. This new technique allows full-field velocity measurements without scanning, a drawback of traditional measurement techniques. This is particularly important for tests in which the sample is destroyed or the motion of the sample is non-repetitive. The goal of creating ''velocity movies'' was accomplished during the research, and this report describes the current functionality and operation of the system. The mathematical underpinnings and system setup are thoroughly described. Two prototype experiments are then presented to show the practical use of the current system. Details of the corresponding hardware used to collect the data and the associated software to analyze the data are presented.

  10. Laser Doppler flowmetry in endodontics: a review.

    Science.gov (United States)

    Jafarzadeh, H

    2009-06-01

    Vascular supply is the most accurate marker of pulp vitality. Tests for assessing vascular supply that rely on the passage of light through a tooth have been considered as possible methods for detecting pulp vitality. Laser Doppler flowmetry (LDF), which is a noninvasive, objective, painless, semi-quantitative method, has been shown to be reliable for measuring pulpal blood flow. The relevant literature on LDF in the context of endodontics up to March 2008 was reviewed using PubMed and MEDLINE database searches. This search identified papers published between June 1983 and March 2008. Laser light is transmitted to the pulp by means of a fibre optic probe. Scattered light from moving red blood cells will be frequency-shifted whilst that from the static tissue remains unshifted. The reflected light, composed of Doppler-shifted and unshifted light, is returned by afferent fibres and a signal is produced. This technique has been successfully employed for estimating pulpal vitality in adults and children, differential diagnosis of apical radiolucencies (on the basis of pulp vitality), examining the reactions to pharmacological agents or electrical and thermal stimulation, and monitoring of pulpal responses to orthodontic procedures and traumatic injuries. Assessments may be highly susceptible to environmental and technique-related factors. Nonpulpal signals, principally from periodontal blood flow, may contaminate the signal. Because this test produces no noxious stimuli, apprehensive or distressed patients accept it more readily than current methods of pulp vitality assessment. A review of the literature and a discussion of the application of this system in endodontics are presented.

  11. Evaluation of Pulsed Doppler-Versus Tissue Doppler-Derived Tei Index of Right and Left Ventricle in Fetuses

    Directory of Open Access Journals (Sweden)

    Hamid Amoozgar

    2011-12-01

    Full Text Available Background: The myocardial performance index (MPI, also known as the Tei index, was introduced by Tei et al. to evaluate cardiac function in adults with dilated cardiomyopathy. This index is defined as the sum of isovolumic contraction time (ICT and isovolumic relaxation time (IRT, divided by ejection time (ET. Objectives: To determine the correlation between pulsed Doppler (PD- and tissue Doppler imaging (TDI-derived Tei indices in fetuses. Patients and Methods: Right and left ventricle PD and TDI echocardiographic data were obtained from 59 fetuses (11 pregnant women who were positive for anti-SSA-Ro or anti-SSB-La antibodies, 18 women who were referred due to dysrhythmia, and 30 women who had normal clinical findings. Results: Mean fetal gestational age was 27 ± 6.4 weeks. Mean PD Tei index of the mitral and tricuspid valve was 0.58 ± 0.05 and 0.53 ± 0.08, respectively. Mean TDI indices for the mitral and tricuspid valve were 0.56 ± 0.09 and 0.55 ± 0.08, respectively. There were no significant differences between mitral and tricuspid PD- and TDI-derived Tei indices (P = 0.87, P= 0.21, but the Bland-Altman diagrams showed no fine agreement between the indices (the mean difference ± 1 standard deviation of the right ventricular PD- and TDI-derived Tei indices was 0.24 ± 0.02 and 0.29 ± 0.04 for the left ventricle. There were no significant differences in PD- and TDI-derived Tei indexes between groups of evaluated fetuses (Mitral valve: PD-Tei P=0.69, TDI-Tei P=0.49; Tricuspid valve: PD-Tei P=0.41, TDI-Tei P=0.36. Conclusions: Although the mean values of the two indices did not differ significantly, the TDI-derived and PD-derived Tei indices did not have fine agreement.

  12. Exeqüibilidade, segurança e acurácia do ecocardiograma sob estresse com dobutamina/ atropina para detecção de doença arterial coronariana em candidatos a transplante renal Feasibility, safety and accuracy of dobutamine/atropine stress echocardiography for the detection of coronary artery disease in renal transplant candidates

    Directory of Open Access Journals (Sweden)

    Pedro Antonio Muniz Ferreira

    2007-01-01

    Full Text Available OBJETIVO: Avaliar a exeqüibilidade, a segurança e a acurácia diagnóstica do ecocardiograma sob estresse (EEDA com dobutamina/atropina em candidatos a transplante renal. MÉTODOS: Pacientes candidatos a transplante renal com e sem nefropatia diabética realizaram EEDA e cineangiocoronariografia. Consideraram-se dois pontos de corte para doença arterial coronariana (DAC: > 50% e > 70% de obstrução de uma artéria epicárdica. RESULTADOS: Cento e quarenta e oito pacientes realizaram o EEDA e a angiografia coronariana. A média de idade foi de 52±9 anos, 69% eram do sexo masculino, 27% tinham nefropatia diabética, e 73%, HVE; 63% estavam assintomáticos, 36% e 22% apresentaram obstruções coronarianas > 50% e > 70%, respectivamente. A exeqüibilidade foi de 91% e houve 2,7% de complicações maiores. Obtiveram-se as seguintes médias de sensibilidade, especificidade e acurácia, considerando obstrução coronariana > 50%: 53% (IC:45-61, 87% (IC:81-93, e 75% (IC:63-83, respectivamente. Para obstrução >70%, 71% (IC:64-92, 85% (IC:79-91 e 81% (IC:75-87. A sensibilidade para diagnosticar doença uniarterial foi 41% (IC:19-63 e doença multiarterial, 78% (IC:64-92. CONCLUSÃO: O EEDA foi exeqüível e seguro; entretanto, foi ineficiente para rastreamento de DAC, considerando obstruções > 50%, mas pode ser útil para detecção de DAC em pacientes com obstruções > 70% e doença multiarterial.OBJECTIVE: To evaluate the feasibility, safety and accuracy of dobutamine/atropine stress echocardiography (DASE for the detection of coronary artery desease (CAD in renal transplant candidates. METHODS: Patients candidates to renal transplant were submitted consecutively to DASE and coronary angiography. The adopted angiographic criteria for CAD were an obstructive lesion of > 50% and > 70%. RESULTS: 148 patients underwent the DASE and the coronary angiography. Mean age was 52 ± 9 years, 69% of the patients were males; 27% had diabetic nephropathy

  13. Use of Doppler ultrasound for non-invasive urodynamic diagnosis

    Directory of Open Access Journals (Sweden)

    Hideo Ozawa

    2009-01-01

    Full Text Available Objectives: A totally non-invasive transperineal urodynamic technique using Doppler ultrasonography has been developed. Methods: Since normal urine does not have blood cells, urine was thought not to produce the Doppler effects. However, basic studies confirmed that the decrease of pressure at high velocity (Bernouilli effect caused dissolved gas to form microbubbles, which are detected by Doppler ultrasonography. Subjects sat and the probe was advanced via remote control to achieve gentle contact with the perineal skin. The digital uroflow data signals and the color Doppler ultrasound video images were processed on a personal computer. The flow-velocity curves from two sites; the distal prostatic urethra just above the external sphincter (V1 and the sphincteric urethra (V2 were plotted against time. The parameters of both the pressure-flow studies and the Doppler ultrasound urodynamic studies were compared in men who had various degrees of obstruction. Results: Functional cross-sectional area at prostatic urethra (A1, calculated by Q max /V1, was lower in the group of bladder outlet obstruction (BOO vs. control group. Velocity ratio (VR, which was calculated by V1/V2, was the parameter having the best correlation with BOO index, though A1 had a similar correlation. This method is viable to diagnose the degree of BOO. Conclusions: The development of non-invasive Doppler ultrasound videourodynamics (Doppler UDS will dramatically expand the information on voiding function.

  14. Doppler sensitivity and its effect on transatlantic TWSTFT links

    Science.gov (United States)

    Zhang, Shengkang; Parker, Thomas; Zhang, Victor

    2017-02-01

    Some investigations have concluded that the diurnal pattern in the time comparison results of present two way satellite time and frequency transfer (TWSTFT) links may come mainly from Doppler dependent errors in the time of arrival (TOA) measurements made by the receivers of the TWSTFT modems. In this paper, several experiments were carried out to test if there is a Doppler dependent error in the ‘delay’ measurements of the receivers currently used. By simulating quantitative Doppler effects in the time transfer signal both on the carrier and the code, a type of Doppler sensitivity on the code was observed in the receivers, which has about  -0.49 ns offset in ‘delay’ measurement for a 1  ×  10-9 fractional Doppler shift. This sensitivity is basically the same for modems with different serial numbers from the same manufacture. We calculated this Doppler caused diurnal pattern in the time comparison results of the transatlantic TWSTFT link between NIST and PTB and found that it is very small and negligible, because the Doppler dependent error is almost identical in the NIST and PTB measurements and therefore it is nearly canceled in the TWSTFT difference. Commercial products are identified for technical completeness only, and no endorsement by NIST is implied.

  15. Ionospheric observations made by a time-interleaved Doppler ionosonde

    Science.gov (United States)

    Lynn, Kenneth J. W.

    2008-10-01

    Mid-latitude HF observations of ionospheric Doppler velocity as a function of frequency are reported here as observed over a quiet 24-h period by a KEL IPS71 ionosonde operating at a 5-min sampling rate. The unique time-interleaving technique used in this ionosonde provided a Doppler resolution of 0.04 Hz over a Doppler range of ±2.5 Hz at each sounding frequency via FFT processing and is described here for the first time. The time-interleaving technique can be applied to other types of ionosonde as well as to other applications. The measurements described were made at a middle latitude site (Salisbury, South Australia). Doppler variations (rate-of-change of foF2 as predicted by a simple parabolic layer model. The descending cusp in short-period TIDs is shown to mark an abrupt change with increasing frequency from negative towards positive Doppler shift with the greatest change in Doppler shift being observed below the cusp. The “smilergram” is introduced as observed in both F2 and Sporadic E. The characteristic curve in Doppler versus group height at a single frequency is described and related to changes in reflection symmetry, velocity and depth of moving ionospheric inhomogeneities.

  16. Pulsed Doppler echocardiographic analysis of mitral regurgitation after myocardial infarction.

    Science.gov (United States)

    Loperfido, F; Biasucci, L M; Pennestri, F; Laurenzi, F; Gimigliano, F; Vigna, C; Rossi, E; Favuzzi, A; Santarelli, P; Manzoli, U

    1986-10-01

    In 72 patients with previous myocardial infarction (MI), mitral regurgitation (MR) was assessed by pulsed-wave Doppler echocardiography and compared with physical and 2-dimensional echocardiographic findings. MR was found by Doppler in 29 of 42 patients (62%) with anterior MI, 11 of 30 (37%) with inferior MI (p less than 0.01) and in none of 20 normal control subjects. MR was more frequent in patients who underwent Doppler study 3 months after MI than in those who underwent Doppler at discharge (anterior MI = 83% vs 50%, p less than 0.01; inferior MI = 47% vs 27%, p = not significant). Of 15 patients who underwent Doppler studies both times, 3 (all with anterior MI) had MR only on the second study. Of the patients with Doppler MR, 12 of 27 (44%) with a left ventricular (LV) ejection fraction (EF) greater than 30% and 1 of 13 (8%) with an EF of 30% or less (p less than 0.01) had an MR systolic murmur. Mitral prolapse or eversion and papillary muscle fibrosis were infrequent in MI patients, whether or not Doppler MR was present. The degree of Doppler MR correlated with EF (r = -0.61), LV systolic volume (r = 0.47), and systolic and diastolic mitral anulus circumference (r = 0.52 and 0.51, respectively). Doppler MR was present in 24 of 28 patients (86%) with an EF of 40% or less and in 16 of 44 (36%) with EF more than 40% (p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

  17. Limits on Planetary Companions from Doppler Surveys of Nearby Stars

    Science.gov (United States)

    Howard, Andrew W.; Fulton, Benjamin J.

    2016-11-01

    Most of our knowledge of planets orbiting nearby stars comes from Doppler surveys. For spaced-based, high-contrast imaging missions, nearby stars with Doppler-discovered planets are attractive targets. The known orbits tell imaging missions where and when to observe, and the dynamically determined masses provide important constraints for the interpretation of planetary spectra. Quantifying the set of planet masses and orbits that could have been detected will enable more efficient planet discovery and characterization. We analyzed Doppler measurements from Lick and Keck Observatories by the California Planet Survey. We focused on stars that are likely targets for three space-based planet imaging mission concepts studied by NASA—WFIRST-AFTA, Exo-C, and Exo-S. The Doppler targets are primarily F8 and later main sequence stars, with observations spanning 1987-2014. We identified 76 stars with Doppler measurements from the prospective mission target lists. We developed an automated planet search and a methodology to estimate the pipeline completeness using injection and recovery tests. We applied this machinery to the Doppler data and computed planet detection limits for each star as a function of planet minimum mass and semimajor axis. For typical stars in the survey, we are sensitive to approximately Saturn-mass planets inside of 1 au, Jupiter-mass planets inside of ˜3 au, and our sensitivity declines out to ˜10 au. For the best Doppler targets, we are sensitive to Neptune-mass planets in 3 au orbits. Using an idealized model of Doppler survey completeness, we forecast the precision of future surveys of non-ideal Doppler targets that are likely targets of imaging missions. Based on observations obtained at the W. M. Keck Observatory, which is operated jointly by the University of California and the California Institute of Technology. Keck time has been granted by NASA, the University of California, and the University of Hawaii.

  18. Carotid Doppler and transcranial Doppler in diagnosing transient ischemic attack: A healthy control

    Institute of Scientific and Technical Information of China (English)

    Huiling Chen; Jinhua Qiu; Hongying Liu

    2006-01-01

    BACKGROUND: If changes of hemodynamics in internal or external cranial artery and stenosis of atherosclerosis are found early, patients with transient ischemic attack (TIA) may be treated at an early phase so as to prevent and decrease the onset of cerebral infarction. Carotid Doppler can analyze carotid canal wall, hemodynamic properties and stenosis, and changes of plaque morphology; however, transcranial Doppler (TCD)can evaluate vascular stenosis and occlusion and judge collateral circulation in cranium through detecting velocity and direction of blood flow. Can the association of them increase the diagnostic rate of TIA?OBJECTIVE: To evaluate the effect of the association of carotid Doppler and TCD on TIA in internal carotid artery.DESIGN: Contrast observational study.SETTING: Department of Neuroelectrophysiology, Central People's Hospital of Huizhou.PARTICIPANTS: A total of 54 patients with TIA in internal carotid artery were selected from the Department of Neurology of Huizhou Central People's Hospital from May 2004 to June 2005. There were 35 males and 24 females aged 46-81 years. The clinical situation was asthenia of single limb, hemiplegia, anaesthesia of single upper or lower limb, hemianesthesia, sensory disorder and aphasia. The symptoms lasted for less than 2 hours. All cases were diagnosed with CT, and those who had pathological changes of acute cerebral infarction and history of cardiac disease were excluded. Additionally, 50 healthy subjects who were regarded as control group were selected from the Department of Neurology of Huizhou Central People's Hospital. There were 30 males and 20 females aged 45-80 years. All subjects were consent.METHODS: HD15000 color Doppler ultrasound (Philips Company, USA) and Muliti-DopX2 TCD (DWL Company, Germany) were used to detect hemodynamics, stenosis and distribution of atherosclerosis in carotid artery and internal carotid artery. Evaluation of marker: Stenosis was calculated by the ratio between the minimal

  19. Computer simulation studies of pulsed Doppler signals from vortices

    Institute of Scientific and Technical Information of China (English)

    CHEN Sizhong; WANG Yuanyuan; WANG Weiqi

    2001-01-01

    A computer simulation method for pulsed Doppler signals from vortices was proposed to generate simulated vortex Doppler signals under various given circumstances. The relative waveforms, such as the maximum frequency waveform, the mean frequency waveform and the bandwidth waveform, were obtained using the short time Fourier analysis of those simulated signals. The relations were studied between several spectrum parameters obtained from these waveforms and given simulation conditions, such as the position and the size of the sample volume, the distance between two vortices, the free stream velocity and the maximum tangent velocity of the vortex. The sensitive parameters were found to detect vortices using the pulsed Doppler techniques.

  20. Ultrasonic Doppler measurement of renal artery blood flow

    Science.gov (United States)

    Freund, W. R.; Beaver, W. L.; Meindl, J. D.

    1976-01-01

    Studies were made of (1) blood flow redistribution during lower body negative pressure (LBNP), (2) the profile of blood flow across the mitral annulus of the heart (both perpendicular and parallel to the commissures), (3) testing and evaluation of a number of pulsed Doppler systems, (4) acute calibration of perivascular Doppler transducers, (5) redesign of the mitral flow transducers to improve reliability and ease of construction, and (6) a frequency offset generator designed for use in distinguishing forward and reverse components of blood flow by producing frequencies above and below the offset frequency. Finally methodology was developed and initial results were obtained from a computer analysis of time-varying Doppler spectra.

  1. Processor operated correlator with applications to laser Doppler signals

    DEFF Research Database (Denmark)

    Bisgaard, C.; Johnsen, B.; Hassager, Ole

    1984-01-01

    A 64-channel correlator is designed with application to the processing of laser Doppler anemometry signals in the range 200 Hz to 250 kHz. The correlator is processor operated to enable the consecutive sampling of 448 correlation functions at a rate up to 500 Hz. Software is described to identify...... a Doppler frequency from each correlation and the system is especially designed for transient flow signals. Doppler frequencies are determined with an accuracy of about 0.1%. Review of Scientific Instruments is copyrighted by The American Institute of Physics....

  2. Mitigating Doppler shift effect in HF multitone data modem

    Science.gov (United States)

    Sonlu, Yasar

    1989-09-01

    Digital communications over High Frequency (HF) radio channels are getting important in recent years. Current HF requirements are for data transmission at rates 2.4 kbps or more to accommodate computer data links and digital secure voice. HF modems which were produced to meet these speeds are, serial modems and parallel modems. On the other hand, the HF sky-wave communication medium, the ionosphere, has some propagation problems such as multipath and Doppler shift. The effect of Doppler shift in a parallel modem which employs Differential Quadrature Phase Shift Keying (DQPSK) modulation is considered and a correction method to mitigate the Doppler Shift effect is introduced.

  3. Interferometric millimeter wave and THz wave doppler radar

    Science.gov (United States)

    Liao, Shaolin; Gopalsami, Nachappa; Bakhtiari, Sasan; Raptis, Apostolos C.; Elmer, Thomas

    2015-08-11

    A mixerless high frequency interferometric Doppler radar system and methods has been invented, numerically validated and experimentally tested. A continuous wave source, phase modulator (e.g., a continuously oscillating reference mirror) and intensity detector are utilized. The intensity detector measures the intensity of the combined reflected Doppler signal and the modulated reference beam. Rigorous mathematics formulas have been developed to extract bot amplitude and phase from the measured intensity signal. Software in Matlab has been developed and used to extract such amplitude and phase information from the experimental data. Both amplitude and phase are calculated and the Doppler frequency signature of the object is determined.

  4. Direct laser cooling Al+ ions optical clocks

    CERN Document Server

    Zhang, J; Luo, J; Lu, Z H

    2016-01-01

    Al$^+$ ions optical clock is a very promising optical frequency standard candidate due to its extremely small blackbody radiation shift. It has been successfully demonstrated with indirect cooled, quantum-logic-based spectroscopy technique. Its accuracy is limited by second-order Doppler shift, and its stability is limited by the number of ions that can be probed in quantum logic processing. We propose a direct laser cooling scheme of Al$^+$ ions optical clocks where both the stability and accuracy of the clocks are greatly improved. In the proposed scheme, two Al$^+$ ions traps are utilized. The first trap is used to trap a large number of Al$^+$ ions to improve the stability of the clock laser, while the second trap is used to trap a single Al$^+$ ions to provide the ultimate accuracy. Both traps are cooled with a continuous wave 167 nm laser. The expected clock laser stability can reach $9.0\\times10^{-17}/\\sqrt{\\tau}$. For the second trap, in addition to 167 nm laser Doppler cooling, a second stage pulsed ...

  5. A novel multi-channel quadrature Doppler backward scattering reflectometer on the HL-2A tokamak

    Science.gov (United States)

    Shi, Zhongbing; Zhong, Wulu; Jiang, Min; Yang, Zengchen; Zhang, Boyu; Shi, Peiwan; Chen, Wei; Wen, Jie; Chen, Chengyuan; Fu, Bingzhong; Liu, Zetian; Ding, Xuantong; Yang, Qingwei; Duan, Xuru

    2016-11-01

    A novel 16-channel fixed frequency Doppler backward scattering (DBS) reflectometer system has been developed on the HL-2A tokamak. This system is based on the filter-based feedback loop microwave source (FFLMS) technique, which has lower phase noise and lower power variation compared with present tunable frequency generation and comb frequency array generation techniques [J. C. Hillesheim et al. Rev. Sci. Instrum. 80, 083507 (2009) and W. A. Peebles et al. Rev. Sci. Instrum. 81, 10D902 (2010)]. The 16-channel DBS system is comprised of four × four-frequency microwave transmitters and direct quadrature demodulation receivers. The working frequencies are 17-24 GHz and 31-38 GHz with the frequency interval of 1 GHz. They are designed to measure the localized intermediate wave-number (k⊥ρ ˜ 1-2, k⊥ ˜ 2-9 cm-1) density fluctuations and the poloidal rotation velocity profile of turbulence. The details of the system design and laboratory tests are presented. Preliminary results of Doppler spectra measured by the multi-channel DBS reflectometer systems are obtained. The plasma rotation and turbulence distribution during supersonic molecular beam injection are analyzed.

  6. Coherent optical transients observed in rubidium atomic line filtered Doppler velocimetry experiments

    Energy Technology Data Exchange (ETDEWEB)

    Fajardo, Mario E., E-mail: mario.fajardo@eglin.af.mil; Molek, Christopher D.; Vesely, Annamaria L. [Air Force Research Laboratory, Munitions Directorate, Ordnance Division, Energetic Materials Branch, AFRL/RWME, 2306 Perimeter Road, Eglin AFB, Florida 32542-5910 (United States)

    2015-10-14

    We report the first successful results from our novel Rubidium Atomic Line Filtered (RALF) Doppler velocimetry apparatus, along with unanticipated oscillatory signals due to coherent optical transients generated within pure Rb vapor cells. RALF is a high-velocity and high-acceleration extension of the well-known Doppler Global Velocimetry (DGV) technique for constructing multi-dimensional flow velocity vector maps in aerodynamics experiments [H. Komine, U.S. Patent No. 4,919,536 (24 April 1990)]. RALF exploits the frequency dependence of pressure-broadened Rb atom optical absorptions in a heated Rb/N{sub 2} gas cell to encode the Doppler shift of reflected near-resonant (λ{sub 0} ≈ 780.24 nm) laser light onto the intensity transmitted by the cell. The present RALF apparatus combines fiber optic and free-space components and was built to determine suitable operating conditions and performance parameters for the Rb/N{sub 2} gas cells. It yields single-spot velocities of thin laser-driven-flyer test surfaces and incorporates a simultaneous Photonic Doppler Velocimetry (PDV) channel [Strand et al., Rev. Sci. Instrum. 77, 083108 (2006)] for validation of the RALF results, which we demonstrate here over the v = 0 to 1 km/s range. Both RALF and DGV presume the vapor cells to be simple Beer's Law optical absorbers, so we were quite surprised to observe oscillatory signals in experiments employing low pressure pure Rb vapor cells. We interpret these oscillations as interference between the Doppler shifted reflected light and the Free Induction Decay (FID) coherent optical transient produced within the pure Rb cells at the original laser frequency; this is confirmed by direct comparison of the PDV and FID signals. We attribute the different behaviors of the Rb/N{sub 2} vs. Rb gas cells to efficient dephasing of the atomic/optical coherences by Rb-N{sub 2} collisions. The minimum necessary N{sub 2} buffer gas density ≈0.3 amagat translates into a

  7. The Doppler Effect: A Consideration of Quasar Redshifts.

    Science.gov (United States)

    Gordon, Kurtiss J.

    1980-01-01

    Provides information on the calculation of the redshift to blueshift ratio introduced by the transverse Doppler effect at relativistic speeds. Indicates that this shift should be mentioned in discussions of whether quasars are "local" rather than "cosmological" objects. (GS)

  8. Design of new seismometer based on laser Doppler effect

    Institute of Scientific and Technical Information of China (English)

    Zhenhui Du(杜振辉); Fuxiang Huang(黄福祥); Chengzhi Jiang(蒋诚志); Zhifei Tao(陶知非); Hua Gao(高华); Lina Lü(吕丽娜)

    2004-01-01

    In order to improve the resolution of seismic acquisition, a new seismic acquisition system based on tangential laser Doppler effect with an optimized differential optical configuration is proposed. The relative movement of the inertia object and the immobile frame is measured by laser Doppler effect, which can avoid the electromagnetic and thermometric interference, and the adoption of frequency-modulated (FM)transmission can improve the ability of anti-jamming. The frequency bandwidth is properly determined by analyzing the frequency of the Doppler signal. The velocity, displacement, acceleration, and frequency to be measured can be real-time acquired by frequency/velocity (F/V) converting the FM Doppler signal.A 100-dB dynamic range and the linear frequency range of 1.0 to 1000 Hz are realized.

  9. Doppler Compensation by using of Segmented Match Filter

    Directory of Open Access Journals (Sweden)

    Nader Ghadimi

    2008-09-01

    Full Text Available Match filter is one of the important parts of radar receiver. By using of Match Filter, the signal to noise ratio can be maximized so that the probability of detection is increased. Match Filter can be used as a pulse compression filter in radar receiver. Binary phase code is one of the pulse compression methods that, the compression can be down with a Match Filter in the receiver. Doppler effect is one of the problems that degrade the performance of Match Filter. In this paper, two methods “Mixer Array” and “Segmented Match Filter” are proposed for Doppler compensation. The operation of these two methods as Doppler compensation techniques are considered theoretically. The simulation is used to demonstrate the Doppler compensation performance of new techniques compared to conventional methods.

  10. [Postpartal ovarian thrombophlebitis. Value of Doppler ultrasonograph y].

    Science.gov (United States)

    Renaud-Giono, A; Giraud, J R; Poulain, P; Proudhon, J F; Grall, J Y; Moquet, P Y; Darnault, J P

    1996-01-01

    Thrombophlebitis of the ovarian vein is a well recognized but uncommon complication during the postpartum period. We report a small series and emphasize the contribution of color Doppler and the basic therapeutic measures.

  11. Multiplexed sub-Doppler spectroscopy with an optical frequency comb

    CERN Document Server

    Long, David A; Plusquellic, David F; Hodges, Joseph T

    2016-01-01

    An optical frequency comb generated with an electro-optic phase modulator and a chirped radiofrequency waveform is used to perform saturation and pump-probe spectroscopy on the $D_1$ and $D_2$ transitions of atomic potassium. With a comb tooth spacing of 200 kHz and an optical bandwidth of 2 GHz the hyperfine transitions can be simultaneously observed. Interferograms are recorded in as little as 5 $\\mu$s (a timescale corresponding to the inverse of the comb tooth spacing). Importantly, the sub-Doppler features can be measured as long as the laser carrier frequency lies within the Doppler profile, thus removing the need for slow scanning or a priori knowledge of the frequencies of the sub-Doppler features. Sub-Doppler optical frequency comb spectroscopy has the potential to dramatically reduce acquisition times and allow for rapid and accurate assignment of complex molecular and atomic spectra which are presently intractable.

  12. COLOR DOPPLER ULTRASOUND IN EVALUATION OF SCROTAL LESIONS

    Directory of Open Access Journals (Sweden)

    Desai Sanjay

    2015-11-01

    Full Text Available : Color Doppler ultrasound is a non-invasive, non-ionising and rapid method for scrotal examination. The present study is carried out to evaluate clinically suspected cases of scrotal lesions, the sensitivity, specificity of color doppler. MATERIAL AND METHODS: This prospective study comprises 120 patients of different age groups with clinical suspicion of scrotal lesions. Color doppler ultrasound was done with 7.5MHz transducer. RESULTS: Of the total 120 cases, benign conditions 111 (92.5% is more common than malignant 9 (7.5%. In benign group commonest diagnoses were hydrocele, epididymo-orchitis, varicocele and epididymal cyst. In malignant group teratocarcinoma, choriocarcinoma, seminoma, lymphoma, embryonal cell carcinoma, yolk sac tumor with teratocarcinoma. The sensitivity for diagnosing extratesticular lesions was 83.14% and for testicular lesions 88.57%. CONCLUSION: Color doppler ultrasound is helpful in differentiating extratesticular and intratesticular lesions. It should be performed in all patients with suspected scrotal lesions

  13. Aliasing-tolerant color Doppler quantification of regurgitant jets.

    Science.gov (United States)

    Stewart, S F

    1998-07-01

    Conservation of momentum transfer in regurgitant cardiac jets can be used to calculate the flow rate from color Doppler velocities. In this study, turbulent jets were simulated by finite elements; pseudocolor Doppler images were interpolated from the computations, with aliasing introduced artificially. Jets were also imaged by color Doppler in an in vitro flow system. To suppress aliasing errors, jet velocities were fitted iteratively to a fluid mechanical model constrained to match the orifice velocity (measured without aliasing by continuous-wave Doppler). At each iteration, the model was used to detect aliased velocities, which were excluded during the next iteration. Iteration continued until the flow rate calculated by the model and number of calculated nonaliased pixels were unchanged. The good correlations between measured and calculated flow rates in the experimental (R2 = 0.933) and computational studies (R2 = 0.990) suggest that this may be a clinically useful approach even in aliased images. Published by Elsevier Science Inc.

  14. Doppler electron velocimetry : notes on creating a practical tool.

    Energy Technology Data Exchange (ETDEWEB)

    Reu, Phillip L.; Milster, Tom (University of Arizona)

    2008-11-01

    The Doppler electron velocimeter (DEV) has been shown to be theoretically possible. This report attempts to answer the next logical question: Is it a practical instrument? The answer hinges upon whether enough electrons are available to create a time-varying Doppler current to be measured by a detector with enough sensitivity and bandwidth. The answer to both of these questions is a qualified yes. A target Doppler frequency of 1 MHz was set as a minimum rate of interest. At this target a theoretical beam current signal-to-noise ratio of 25-to-1 is shown for existing electron holography equipment. A detector is also demonstrated with a bandwidth of 1-MHz at a current of 10 pA. Additionally, a Linnik-type interferometer that would increase the available beam current is shown that would offer a more flexible arrangement for Doppler electron measurements over the traditional biprism.

  15. Analysis of multiple scattering effects in optical Doppler tomography

    DEFF Research Database (Denmark)

    Yura, H.T.; Thrane, L.; Andersen, Peter E.

    2005-01-01

    Optical Doppler tomography (ODT) combines Doppler velocimetry and optical coherence tomography (OCT) to obtain high-resolution cross-sectional imaging of particle flow velocity in scattering media such as the human retina and skin. Here, we present the results of a theoretical analysis of ODT where...... multiple scattering effects are included. The purpose of this analysis is to determine how multiple scattering affects the estimation of the depth-resolved localized flow velocity. Depth-resolved velocity estimates are obtained directly from the corresponding mean or standard deviation of the observed...... Doppler frequency spectrum. Thus, in the present analysis, the dependence of the mean and standard deviation of the Doppler shift on the scattering properties of the flowing medium are obtained. Taking the multiple scattering effects into account, we are able to explain previous measurements of depth...

  16. Doppler ultrasound exam of an arm or leg

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/article/003775.htm Doppler ultrasound exam of an arm or leg To use ... this page, please enable JavaScript. This test uses ultrasound to look at the blood flow in the ...

  17. Doppler Ambiguity Resolution Based on Random Sparse Probing Pulses

    Directory of Open Access Journals (Sweden)

    Yunjian Zhang

    2015-01-01

    Full Text Available A novel method for solving Doppler ambiguous problem based on compressed sensing (CS theory is proposed in this paper. A pulse train with the random and sparse transmitting time is transmitted. The received signals after matched filtering can be viewed as randomly sparse sampling from the traditional fixed-pulse repetition frequency (PRF echo signals. The whole target echo could be reconstructed via CS recovery algorithms. Through refining the sensing matrix, which is equivalent to increase the sampling frequency of target characteristic, the Doppler unambiguous range is enlarged. In particular, Complex Approximate Message Passing (CAMP algorithm is developed to estimate the unambiguity Doppler frequency. Cramer-Rao lower bound expressions are derived for the frequency. Numerical simulations validate the effectiveness of the proposed method. Finally, compared with traditional methods, the proposed method only requires transmitting a few sparse probing pulses to achieve a larger Doppler frequency unambiguous range and can also reduce the consumption of the radar time resources.

  18. Doppler bubble detection and decompression sickness: a prospective clinical trial.

    Science.gov (United States)

    Bayne, C G; Hunt, W S; Johanson, D C; Flynn, E T; Weathersby, P K

    1985-09-01

    Decompression sickness in human beings exposed to high ambient pressure is thought to follow from gas bubble formation and growth in the body during return to low pressure. Detection of Doppler-shifted ultrasonic reflections in major blood vessels has been promoted as a noninvasive and sensitive indicator of the imminence of decompression sickness. We have conducted a double-blind, prospective clinical trial of Doppler ultrasonic bubble detection in simulated diving using 83 men, of whom 8 were stricken and treated for the clinical disease. Diagnosis based only on the Doppler signals had no correlation with clinical diagnosis. Bubble scores were only slightly higher in the stricken group. The Doppler technique does not appear to be of diagnostic value in the absence of other clinical information.

  19. Estimation of amputation level with a laser Doppler flowmeter

    DEFF Research Database (Denmark)

    Gebuhr, Peter Henrik; Jørgensen, J P; Vollmer-Larsen, B;

    1989-01-01

    Leg amputation levels were decided in 24 patients suffering from atherosclerosis, using the conventional techniques of segmental blood pressure and radioisotope skin clearance. The skin microcirculation was measured and recorded before operation with a laser doppler flowmeter. A high correlation ...

  20. Doppler Signatures of the Atmospheric Circulation on Hot Jupiters

    CERN Document Server

    Showman, Adam P; Lewis, Nikole K; Shabram, Megan

    2013-01-01

    The meteorology of hot Jupiters has been characterized primarily with thermal measurements, but recent observations suggest the possibility of directly detecting the winds by observing the Doppler shift of spectral lines seen during transit. Motivated by these observations, we show how Doppler measurements can place powerful constraints on the meteorology. We show that the atmospheric circulation--and Doppler signature--of hot Jupiters splits into two regimes. Under weak stellar insolation, the day-night thermal forcing generates fast zonal jet streams from the interaction of atmospheric waves with the mean flow. In this regime, air along the terminator (as seen during transit) flows toward Earth in some regions and away from Earth in others, leading to a Doppler signature exhibiting superposed blue- and redshifted components. Under intense stellar insolation, however, the strong thermal forcing damps these planetary-scale waves, inhibiting their ability to generate jets. Strong frictional drag likewise damps...

  1. Doppler ultrasound in obstetrics and gynecology. 2. rev. and enl. ed.

    Energy Technology Data Exchange (ETDEWEB)

    Maulik, D. [Winthrop Univ. Hospital, Mineola, NY (United States). Dept. of Obstetrics and Gynecology; Zalud, I. (eds.) [Kapiolani Medical Center for Women and Children, Honolulu, HI (United States)

    2005-07-01

    The second edition of Doppler Ultrasound in Obstetrics and Gynecology has been expanded and comprehensively updated to present the current standards of practice in Doppler ultrasound and the most recent developments in the technology. Doppler Ultrasound in Obstetrics and Gynecology encompasses the full spectrum of clinical applications of Doppler ultrasound for the practicing obstetrician-gynecologist, including the latest advances in 3D and color Doppler and the newest techniques in 4D fetal echocardiography. Written by preeminent experts in the field, the book covers the basic and physical principles of Doppler ultrasound; the use of Doppler for fetal examination, including fetal cerebral circulation; Doppler echocardiography of the fetal heart; and the use of Doppler for postdated pregnancy and in cases of multiple gestation. Chapters on the use of Doppler for gynecologic investigation include ultrasound in ectopic pregnancy, for infertility, for benign disorders and for gynecologic malignancies. (orig.)

  2. Using doppler radar images to estimate aircraft navigational heading error

    Science.gov (United States)

    Doerry, Armin W [Albuquerque, NM; Jordan, Jay D [Albuquerque, NM; Kim, Theodore J [Albuquerque, NM

    2012-07-03

    A yaw angle error of a motion measurement system carried on an aircraft for navigation is estimated from Doppler radar images captured using the aircraft. At least two radar pulses aimed at respectively different physical locations in a targeted area are transmitted from a radar antenna carried on the aircraft. At least two Doppler radar images that respectively correspond to the at least two transmitted radar pulses are produced. These images are used to produce an estimate of the yaw angle error.

  3. Quantification of cardiac blood flow by Doppler technique

    OpenAIRE

    Meijboom, Erik Jan

    1985-01-01

    textabstractThe investigations described in this thesis started as part of the research program of the divisions of pediatric cardiology of the Universities of Arizona and California (San Diego). The investigations were part of an ongoing project designed by D.J. Sahn and L.M. Valdes-Cruz. This project was initiated to implement Doppler techniques in the daily practice of pediatric cardiology. New developments in medical technology made the Doppler techniques integrated into sophisticated two...

  4. Radar target recognition based on micro-Doppler effect

    Institute of Scientific and Technical Information of China (English)

    DONG Wei-guang; LI Yan-jun

    2008-01-01

    Mechanical vibration of target structures will modulate the phase function of radar backscattering, and will induce thefrequency modulation of returned signals from the target. It generates a side bands of the target body Doppler frequencyshift, which is helpful for target recognition. Based on this.a micro-Doppler atomic storehouse is built for the targetrecognition, and four kinds of common classifiers are used separately to perform the classified recognition. The simulationexperimental results show that this method has high recognition rate above 90%.

  5. Doppler visibility of coherent random noise radar systems

    Science.gov (United States)

    Li, Zhixi; Narayanan, Ram M.

    2005-05-01

    Random noise radar has recently been used in a variety of imaging and surveillance applications. These systems can be made phase coherent using the technique of heterodyne correlation. Phase coherence has been exploited to measure Doppler and thereby the velocity of moving targets. The Doppler visibility, i.e., the ability to extract Doppler information over the inherent clutter spectra, is constrained by system parameters, especially the phase noise generated by microwave components. Our paper proposes a new phase noise model for the heterodyne mixer as applicable for ultrawideband (UWB) random noise radar and for the local oscillator in the time domain. The Doppler spectra are simulated by including phase noise contamination effects and compared to our previous experimental results. A Genetic Algorithm (GA) optimization routine is applied to synthesize the effects of a variety of parameter combinations to derive a suitable empirical formula for estimating the Doppler visibility in dB. According to the phase noise analysis and the simulation results, the Doppler visibility of UWB random noise radar depends primarily on the following parameters: (a) the local oscillator (LO) drive level of the receiver heterodyne mixer; (b) the saturation current in the receiver heterodyne mixer; (c) the bandwidth of the transmit noise source, and; (d) the target velocity. Other parameters such as the carrier frequency of the receiver LO and the loaded quality factor of the LO have a small effect over the range of applicability of the model and are therefore neglected in the model formulation. The Doppler visibility curves generated from this formula match the simulation results very well over the applicable parameter range within 1 dB. Our model may therefore be used to quickly estimate the Doppler visibility of random noise radars for trade-off analysis.

  6. Venus cloud-tracked and doppler velocimetry winds from CFHT/ESPaDOnS and Venus Express/VIRTIS in April 2014

    Science.gov (United States)

    Machado, Pedro; Widemann, Thomas; Peralta, Javier; Gonçalves, Ruben; Donati, Jean-François; Luz, David

    2017-03-01

    We present new coordinated observations and measurements of the wind amplitude and its variability at Venus cloud-tops based on the two complementary techniques of Ground-based Doppler velocimetry (Widemann et al., 2007, 2008; Machado et al., 2012, 2014) and cloud-tracked winds using ESA Venus Express/ VIRTIS-M imaging at 0.38 μm (Drossart et al., 2007; Sanchez-Lavega et al., 2008; Hueso et al., 2012; Machado et al., 2014). Cloud-tracked winds trace the true atmospheric motion also responsible for the Doppler-Fizeau shift of the solar radiation on the dayside by super-rotating moving cloud-tops with respect to both the Sun and the observer (Machado et al., 2014), and based on this complementarity, we performed a new coordinated campaign in April 2014 combining both Venus Express observations and ground-based Doppler wind measurements on the dayside of Venus' cloud tops at Canada-France-Hawaii telescope at a phase angle Φ =(76 ± 0.3) ∘ . The analysis and results show (1) additional confirmation of the coherence, and complementarity, in the results provided by these techniques, on both spatial and temporal time scales of the two methods; (2) first-time estimation of the meridional component of the wind in another planet using the Doppler velocimetry technique, with evidence of a symmetrical, poleward meridional Hadley flow in both hemispheres of vbarm = 22± 15.5 ms-1; (3) spatial and temporal variability of the zonal flow with latitude and local time, with a significant increase of wind amplitude near the morning terminator previously reported in Feb. 2011 observations.

  7. Doppler cooling of a Coulomb crystal

    CERN Document Server

    Morigi, G; Morigi, Giovanna; Eschner, Juergen

    2001-01-01

    We study theoretically Doppler laser-cooling of a cluster of 2-level atoms confined in a linear ion trap. Using several consecutive steps of averaging we derive, from the full quantum mechanical master equation, an equation for the total mechanical energy of the one dimensional crystal, defined on a coarse-grained energy scale whose grid size is smaller than the linewidth of the electronic transition. This equation describes the cooling dynamics for an arbitrary number of ions and in the quantum regime. We discuss the validity of the ergodic assumption (i.e. that the phase space distribution is only a function of energy). From our equation we derive the semiclassical limit (i.e. when the mechanical motion can be treated classically) and the Lamb-Dicke limit (i.e. when the size of the mechanical wave function is much smaller than the laser wavelength). We find a Fokker-Planck equation for the total mechanical energy of the system, whose solution is in agreement with previous analytical calculations which were ...

  8. Doppler effect induced spin relaxation boom

    Science.gov (United States)

    Zhao, Xinyu; Huang, Peihao; Hu, Xuedong

    2016-03-01

    We study an electron spin qubit confined in a moving quantum dot (QD), with our attention on both spin relaxation, and the product of spin relaxation, the emitted phonons. We find that Doppler effect leads to several interesting phenomena. In particular, spin relaxation rate peaks when the QD motion is in the transonic regime, which we term a spin relaxation boom in analogy to the classical sonic boom. This peak indicates that a moving spin qubit may have even lower relaxation rate than a static qubit, pointing at the possibility of coherence-preserving transport for a spin qubit. We also find that the emitted phonons become strongly directional and narrow in their frequency range as the qubit reaches the supersonic regime, similar to Cherenkov radiation. In other words, fast moving excited spin qubits can act as a source of non-classical phonons. Compared to classical Cherenkov radiation, we show that quantum dot confinement produces a small but important correction on the Cherenkov angle. Taking together, these results have important implications to both spin-based quantum information processing and coherent phonon dynamics in semiconductor nanostructures.

  9. Muscle activity characterization by laser Doppler Myography

    Science.gov (United States)

    Scalise, Lorenzo; Casaccia, Sara; Marchionni, Paolo; Ercoli, Ilaria; Primo Tomasini, Enrico

    2013-09-01

    Electromiography (EMG) is the gold-standard technique used for the evaluation of muscle activity. This technique is used in biomechanics, sport medicine, neurology and rehabilitation therapy and it provides the electrical activity produced by skeletal muscles. Among the parameters measured with EMG, two very important quantities are: signal amplitude and duration of muscle contraction, muscle fatigue and maximum muscle power. Recently, a new measurement procedure, named Laser Doppler Myography (LDMi), for the non contact assessment of muscle activity has been proposed to measure the vibro-mechanical behaviour of the muscle. The aim of this study is to present the LDMi technique and to evaluate its capacity to measure some characteristic features proper of the muscle. In this paper LDMi is compared with standard superficial EMG (sEMG) requiring the application of sensors on the skin of each patient. sEMG and LDMi signals have been simultaneously acquired and processed to test correlations. Three parameters has been analyzed to compare these techniques: Muscle activation timing, signal amplitude and muscle fatigue. LDMi appears to be a reliable and promising measurement technique allowing the measurements without contact with the patient skin.

  10. Doppler time-of-flight imaging

    KAUST Repository

    Heide, Felix

    2015-07-30

    Over the last few years, depth cameras have become increasingly popular for a range of applications, including human-computer interaction and gaming, augmented reality, machine vision, and medical imaging. Many of the commercially-available devices use the time-of-flight principle, where active illumination is temporally coded and analyzed on the camera to estimate a per-pixel depth map of the scene. In this paper, we propose a fundamentally new imaging modality for all time-of-flight (ToF) cameras: per-pixel velocity measurement. The proposed technique exploits the Doppler effect of objects in motion, which shifts the temporal frequency of the illumination before it reaches the camera. Using carefully coded illumination and modulation frequencies of the ToF camera, object velocities directly map to measured pixel intensities. We show that a slight modification of our imaging system allows for color, depth, and velocity information to be captured simultaneously. Combining the optical flow computed on the RGB frames with the measured metric axial velocity allows us to further estimate the full 3D metric velocity field of the scene. We believe that the proposed technique has applications in many computer graphics and vision problems, for example motion tracking, segmentation, recognition, and motion deblurring.

  11. MEMS characterization using Laser Doppler Vibrometry

    Science.gov (United States)

    Lawrence, Eric M.; Speller, Kevin E.; Yu, Duli

    2003-01-01

    The use of Laser Doppler Vibrometry (LDV) technology has been at the forefront of Micro-Electro-Mechanical Systems (MEMS) research since the early 1990"s. By its nature as a sensitive laser optical technique, it is well suited for non-contact dynamic response measurements of microscopic structures. The art of the technology has culminated into the latest micro-scanning vibrometer for automated scan measurement and display of deflection shapes with sub-nanometer resolution. To exemplify the use of this technology, Polytec PI presents characterization measurements in collaboration with Applied MEMS on two of their devices used in commercial applications. LDV characterization measurements are used for validating the design of the Applied MEMS two-axis micro mirror. Scan measurements reveal distinct, isolated rotation modes about x- and y- axes that can be used to promote the mirror motion in either direction. Settling time performance is evaluated from impulse response and optimized using Input Shaping techniques. Scan measurements of a low-noise accelerometer device from Applied MEMS reveals spurious high frequency modes of support spring causing unwanted response effects. Further use of a new time domain animation feature shows ringing response of the accelerometer to step motions.

  12. Satellite Doppler Fixation and International Boundaries

    Science.gov (United States)

    Leppard, N. A. G.

    1980-01-01

    International boundaries have seldom been completely defined in geodetic terms. The existence of natural resources, which ignore the arbitrary boundaries of man, assume considerable importance when division of those resources becomes a point of issue between potential owners. This is particularly so when the boundary is illdefined in a geodetic sense. World-wide satellite reference systems, like natural resources, also have little regard for the internally less precise national or international systems. When the one is used to define the location of the other, great care must be taken to ensure equitable division, for financial gain and loss can be considerable. The definition of position is complicated by the existence of the two ephemerides for the N.N.S.S. satellites and the number of alternative reduction procedures available. The definition of the position of the Frigg Gas Field in the North Sea is an example of how the United Kingdom and Norway resolved the geodetic problem of reconciling geodetic and Doppler data.

  13. Zeeman Doppler Maps: Always Unique, Never Spurious?

    Science.gov (United States)

    Stift, Martin J.; Leone, Francesco

    2017-01-01

    Numerical models of atomic diffusion in magnetic atmospheres of ApBp stars predict abundance structures that differ from the empirical maps derived with (Zeeman) Doppler mapping (ZDM). An in-depth analysis of this apparent disagreement investigates the detectability by means of ZDM of a variety of abundance structures, including (warped) rings predicted by theory, but also complex spot-like structures. Even when spectra of high signal-to-noise ratio are available, it can prove difficult or altogether impossible to correctly recover shapes, positions, and abundances of a mere handful of spots, notwithstanding the use of all four Stokes parameters and an exactly known field geometry; the recovery of (warped) rings can be equally challenging. Inversions of complex abundance maps that are based on just one or two spectral lines usually permit multiple solutions. It turns out that it can by no means be guaranteed that any of the regularization functions in general use for ZDM (maximum entropy or Tikhonov) will lead to a true abundance map instead of some spurious one. Attention is drawn to the need for a study that would elucidate the relation between the stratified, field-dependent abundance structures predicted by diffusion theory on the one hand, and empirical maps obtained by means of “canonical” ZDM, i.e., with mean atmospheres and unstratified abundances, on the other hand. Finally, we point out difficulties arising from the three-dimensional nature of the atomic diffusion process in magnetic ApBp star atmospheres.

  14. Intrahepatic portosystemic venous shunts: diagnosis by Doppler ultrasound; Cortocircuitos venosos portosistemicos intrahepaticos: diagnostico mediante ecografia Doppler

    Energy Technology Data Exchange (ETDEWEB)

    Garofano, M. P.; Medina, A.; Lopez, G.; Garrido, C. [Hospital Universitario Virgen de las Nieves. Granada (Spain)

    2001-07-01

    Intrahepatic portosystemic venous shunts are venous vascular lesions that allow intrahepatic portal vessels to communicate with hepatic veins. They may present in patients with portal hypertension or b discovered incidentally; it is considered that the latter may be congenital or acquired. A noninvasive methods. Doppler ultrasound aids in the diagnosis of these anomalous communications by providing images of the vessels and the direction, velocity and volume of the blood flow through the shunt. We present four cases of intrahepatic portosystemic venous shunt. (Author) 8 refs.

  15. Doppler Monitoring of the WASP-47 Multiplanet System

    CERN Document Server

    Dai, Fei; Arriagada, Pamela; Butler, R Paul; Crane, Jeffrey D; Johnson, John Asher; Shectman, Stephen A; Teske, Johanna K; Thompson, Ian B; Vanderburg, Andrew; Wittenmyer, Robert A

    2015-01-01

    We present precise Doppler observations of WASP-47, a transiting planetary system featuring a hot Jupiter with both inner and outer planetary companions. This system has an unusual architecture and also provides a rare opportunity to measure planet masses in two different ways: the Doppler method, and the analysis of transit-timing variations (TTV). Based on the new Doppler data, obtained with the Planet Finder Spectrograph on the Magellan/Clay 6.5m telescope, the mass of the hot Jupiter is $370 \\pm 29~M_{\\oplus}$. This is consistent with the previous Doppler determination as well as the TTV determination. For the inner planet WASP-47e, the Doppler data lead to a mass of $12.2\\pm 3.7~ M_{\\oplus}$, in agreement with the TTV-based upper limit of $<$22~$M_{\\oplus}$ ($95\\%$ confidence). For the outer planet WASP-47d, the Doppler mass constraint of $10.4\\pm 8.4~M_{\\oplus}$ is consistent with the TTV-based measurement of $15.2^{+6.7}_{-7.6}~ M_{\\oplus}$.

  16. Low-Frequency Gravitational Wave Searches Using Spacecraft Doppler Tracking

    Directory of Open Access Journals (Sweden)

    Armstrong J. W.

    2006-01-01

    Full Text Available This paper discusses spacecraft Doppler tracking, the current-generation detector technology used in the low-frequency (~millihertz gravitational wave band. In the Doppler method the earth and a distant spacecraft act as free test masses with a ground-based precision Doppler tracking system continuously monitoring the earth-spacecraft relative dimensionless velocity $2 Delta v/c = Delta u/ u_0$, where $Delta u$ is the Doppler shift and $ u_0$ is the radio link carrier frequency. A gravitational wave having strain amplitude $h$ incident on the earth-spacecraft system causes perturbations of order $h$ in the time series of $Delta u/ u_0$. Unlike other detectors, the ~1-10 AU earth-spacecraft separation makes the detector large compared with millihertz-band gravitational wavelengths, and thus times-of-flight of signals and radio waves through the apparatus are important. A burst signal, for example, is time-resolved into a characteristic signature: three discrete events in the Doppler time series. I discuss here the principles of operation of this detector (emphasizing transfer functions of gravitational wave signals and the principal noises to the Doppler time series, some data analysis techniques, experiments to date, and illustrations of sensitivity and current detector performance. I conclude with a discussion of how gravitational wave sensitivity can be improved in the low-frequency band.

  17. Analysis of Radar Doppler Signature from Human Data

    Directory of Open Access Journals (Sweden)

    M. ANDRIĆ

    2014-04-01

    Full Text Available This paper presents the results of time (autocorrelation and time-frequency (spectrogram analyses of radar signals returned from the moving human targets. When a radar signal falls on the human target which is moving toward or away from the radar, the signals reflected from different parts of his body produce a Doppler shift that is proportional to the velocity of those parts. Moving parts of the body causes the characteristic Doppler signature. The main contribution comes from the torso which causes the central Doppler frequency of target. The motion of arms and legs induces modulation on the returned radar signal and generates sidebands around the central Doppler frequency, referred to as micro-Doppler signatures. Through analyses on experimental data it was demonstrated that the human motion signature extraction is better using spectrogram. While the central Doppler frequency can be determined using the autocorrelation and the spectrogram, the extraction of the fundamental cadence frequency using the autocorrelation is unreliable when the target is in the clutter presence. It was shown that the fundamental cadence frequency increases with increasing dynamic movement of people and simultaneously the possibility of its extraction is proportional to the degree of synchronization movements of persons in the group.

  18. Calculation of the Doppler broadening function using Fourier analysis;Calculo da funcao de alargamento Doppler utilizando analise de Fourier

    Energy Technology Data Exchange (ETDEWEB)

    Goncalves, Alessandro da Cruz

    2010-07-01

    An efficient and precise method for calculation of Doppler broadening function is very important to obtain average group microscopic cross sections, self shielding factors, resonance integrals and others reactor physics parameter. In this thesis two different methods for calculation of Doppler broadening function and interference term will be presented. The main method is based on a new integral form for Doppler broadening function {psi}(x,{zeta}) which gives a mathematical interpretation of the approximation proposed by Bethe and Placzek, as the convolution of the Lorentzian function with a Gaussian function. This interpretation besides leading to a new integral form for {psi}(x,{zeta}), enables to obtain a simple analytic solution for the Doppler broadening function. (author)

  19. Alergia ao leite de vaca: achados do ultrassom com Doppler colorido em neonatos com hematoquezia

    Directory of Open Access Journals (Sweden)

    Matias Epifanio

    2013-12-01

    Full Text Available OBJETIVO: o ultrassom (US tem sido uma importante ferramenta de diagnóstico para identificar várias causas de hemorragia gastrointestinal. Neonatos com alergia ao leite de vaca (ALV podem apresentar hematoquezia, e a confirmação do diagnóstico pode ser difícil. O objetivo deste estudo é descrever achados com ultrassom em escala de cinza e com Doppler colorido em pacientes com ALV. MÉTODOS: estudamos, retrospectivamente, 13 neonatos com ALV. Todos eles apresentaram hematoquezia severa e dor abdominal e foram submetidos a um estudo com US, com o diagnóstico de colite alérgica. O diagnóstico teve como base os achados clínicos, a recuperação após a dieta de exclusão do neonato ou da mãe, no caso de amamentação exclusiva, e o teste de provocação oral positivo. RESULTADOS: a idade média variou de um a seis meses (média = 3,53. Sete dos 13 neonatos (53,8% passaram novamente por ultrassonografia em escala de cinza e com Doppler colorido após a dieta de exclusão. Dentre eles, 12 dos 13 (92,3% mostraram anormalidades no US e no ultrassom com Doppler colorido (USDC no início. Os achados positivos que sugeriram colite foram paredes intestinais espessas e aumento na vascularização, principalmente no cólon descendente e sigmoide. Os resultados da colonoscopia e histopatológicos foram compatíveis com colite alérgica. Após uma mudança na dieta, os 13 neonatos se recuperaram e seus testes de provocação oral foram positivos. CONCLUSÃO: o US com Doppler pode ser muito útil para diagnosticar a colite secundária, como a ALV, e para excluir várias outras doenças abdominais que podem imitar essa doença.

  20. Longitudinal study of aortic isthmus Doppler in appropriately grown and small-for-gestational-age fetuses with normal and abnormal umbilical artery Doppler.

    LENUS (Irish Health Repository)

    Kennelly, M M

    2012-04-01

    To establish reference ranges using longitudinal data for aortic isthmus (AoI) Doppler indices in appropriate-for-gestational-age (AGA) fetuses and to document the longitudinal trends in a cohort of small-for-gestational-age (SGA) fetuses with normal umbilical artery Doppler and in fetuses with intrauterine growth restriction (IUGR) and abnormal umbilical artery Doppler.

  1. Interpreting laser Doppler recordings from free flaps.

    Science.gov (United States)

    Svensson, H; Holmberg, J; Svedman, P

    1993-01-01

    Although the transfer of free flaps is nowadays accomplished with an increasing degree of safety, thrombosis of the microvascular anastomoses is still a problem. In order to avoid delay in re-operating, various methods for objective blood flow monitoring have been tried, among them Laser Doppler Flowmetry (LDF). When one reviews the literature, it is apparent that opinions differ about whether or not LDF is a reliable technique for this purpose. To focus on the need to interpret continuous recordings, this paper reports our findings in six latissimus dorsi free flaps chosen from our series of LDF monitoring procedures. One uneventful flap, no. 1, had an immediate postoperative LDF value of 4.5 perfusion units (PU). LDF values improved during the recovery period and the graphic recording showed fluctuations due to normal physiological variations of the blood flow in the flap. Another uneventful flap, no. 4, showed the same pattern, though at an appreciably lower level, 2 PU, on average. Flap no. 2 had an acceptably high value of 3.5 PU despite suffering a venous thrombosis. However, the LDF recording showed no fluctuations and the value declined gradually. Another flap, no. 3, showed fluctuations and blood flow was normal although the value decreased to 2.5 PU. In flap no. 5, any value between 2 and 3.5 PU could be obtained merely by adjusting the position of the probe in the holder. In no. 6, the LDF value suddenly dropped, accompanied by a decrease in the total amount of backscattered light, indicating venous obstruction which was confirmed at re-operation.(ABSTRACT TRUNCATED AT 250 WORDS)

  2. ADEPT - Abnormal Doppler Enteral Prescription Trial

    Directory of Open Access Journals (Sweden)

    McCormick Kenny

    2009-10-01

    Full Text Available Abstract Background Pregnancies complicated by abnormal umbilical artery Doppler blood flow patterns often result in the baby being born both preterm and growth-restricted. These babies are at high risk of milk intolerance and necrotising enterocolitis, as well as post-natal growth failure, and there is no clinical consensus about how best to feed them. Policies of both early milk feeding and late milk feeding are widely used. This randomised controlled trial aims to determine whether a policy of early initiation of milk feeds is beneficial compared with late initiation. Optimising neonatal feeding for this group of babies may have long-term health implications and if either of these policies is shown to be beneficial it can be immediately adopted into clinical practice. Methods and Design Babies with gestational age below 35 weeks, and with birth weight below 10th centile for gestational age, will be randomly allocated to an "early" or "late" enteral feeding regimen, commencing milk feeds on day 2 and day 6 after birth, respectively. Feeds will be gradually increased over 9-13 days (depending on gestational age using a schedule derived from those used in hospitals in the Eastern and South Western Regions of England, based on surveys of feeding practice. Primary outcome measures are time to establish full enteral feeding and necrotising enterocolitis; secondary outcomes include sepsis and growth. The target sample size is 400 babies. This sample size is large enough to detect a clinically meaningful difference of 3 days in time to establish full enteral feeds between the two feeding policies, with 90% power and a 5% 2-sided significance level. Initial recruitment period was 24 months, subsequently extended to 38 months. Discussion There is limited evidence from randomised controlled trials on which to base decisions regarding feeding policy in high risk preterm infants. This multicentre trial will help to guide clinical practice and may also

  3. Doppler ultrasound and giant cell arteritis

    Directory of Open Access Journals (Sweden)

    Ana Marina Suelves

    2010-11-01

    Full Text Available Ana Marina Suelves1, Enrique España-Gregori1,2, Jose Tembl3, Stephanie Rohrweck1, Jose Maria Millán4, Manuel Díaz-Llopis1,4,51Service of Ophthalmology, La Fe University Hospital, Valencia, Spain; 2Department of Optics, University of Valencia, Valencia, Spain; 3Service of Neurology, La Fe University Hospital, Valencia, Spain; 4CIBERER, Ciber de Enfermedades Raras, Valencia, Spain; 5Faculty of Medicine, University of Valencia, Valencia, SpainObjective: To evaluate the utility of ultrasound in aiding the diagnosis of giant cell arteritis (GCA, in monitoring the response to corticotherapy, and in detecting early relapses.Methods: A pilot study, prospective, included 10 patients with suspected GCA. All patients underwent ultrasound examination of both temporal arteries before temporal artery biopsy (TAB, 3 weeks after starting treatment, and 3 months after diagnosis. For this study, the histological findings alone were used to define if patients were suffering from GCA. The findings on ultrasound were compared with the results of biopsy. The best place to perform TAB was observed by ultrasound.Results: All patients with positive biopsy were detected with ultrasound. No false positives were observed on ultrasound. The results presented give a sensibility, specificity, and positive predictive value of 100% for the use of ultrasound in the diagnosis of GCA. Two relapses were detected early by ultrasound during the follow-up.Conclusions: This pilot study suggests that eco-doppler may be a useful tool in diagnosis and clinic follow-up in patients with suspected GCA.Keywords: giant cell arteritis, ultrasound, temporal artery biopsy, optic nerve

  4. Trombose de prótese biológica mitral: importância do ecocardiograma transesofágico no diagnóstico e acompanhamento pós-tratamento Bioprosthetic mitral valve thrombosis: importance of transesophageal echocardiography in the diagnosis and follow-up after treatment

    Directory of Open Access Journals (Sweden)

    Adelino Parro Jr

    2004-04-01

    Full Text Available OBJETIVO: Descrever os achados clínicos e ecocardiográficos de trombose em prótese biológica mitral e o valor do ecocardiograma transesofágico (ETE no diagnóstico e monitoração da lise do trombo. MÉTODOS: Foram estudados ao ETE 111 pacientes com prótese biológica mitral, e incluídos 4 de 7 com suspeita de trombo nestas próteses (idade média = 60,2±10,2 anos; 2 homens. O diagnóstico pôde ser confirmado pela realização seriada do ETE e pela evolução clínica. Investigaram-se os aspectos morfológicos dos folhetos da prótese, e presença e característica das massas ecogênicas anexas. Foram obtidos o gradiente médio pela prótese e a área valvar. RESULTADOS: O diagnóstico de trombo em prótese biológica mitral foi realizado 48,7±55,2 meses após a cirurgia. Dois pacientes apresentaram acidente vascular encefálico isquêmico no pós-operatório imediato. O gradiente médio global estava elevado (11,4±3 mmHg e a área valvar reduzida (1,24±0,3cm². Ao ETE, em todos foram evidenciadas massas ecogênicas em face ventricular esquerda da prótese biológica mitral, sugestivas de trombo. No ETE seriado (136±233 dias, houve desaparecimento do trombo em dois casos e redução do trombo nos outros dois, após tratamento. O gradiente médio reduziu para 6,2±3 mmHg (p=0,004; IC 95%, e a área valvar aumentou para 2,07±0,4 (p=ns. CONCLUSÃO: O ETE mostrou-se útil na detecção de trombo em prótese biológica mitral e eficaz na monitoração do tratamento, em todos casos.OBJECTIVE: To report the clinical and echocardiographic findings of bioprosthetic mitral valve thrombosis and the value of transesophageal echocardiography (TEE in its diagnosis and monitoring of thrombolysis. METHODS: One hundred and eleven patients with mitral bioprostheses underwent TEE, and 4 out of 7 suspected of having a thrombus on these prostheses were included in the study (mean age = 60.2±10.2 years; 2 men. The diagnosis was confirmed with serial

  5. DOPPLER SIGNATURES OF THE ATMOSPHERIC CIRCULATION ON HOT JUPITERS

    Energy Technology Data Exchange (ETDEWEB)

    Showman, Adam P.; Lewis, Nikole K. [Department of Planetary Sciences and Lunar and Planetary Laboratory, The University of Arizona, 1629 University Boulevard, Tucson, AZ 85721 (United States); Fortney, Jonathan J. [Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States); Shabram, Megan, E-mail: showman@lpl.arizona.edu [Department of Astronomy, University of Florida, 211 Bryant Space Science Center, Gainesville, FL 32611-2055 (United States)

    2013-01-01

    The meteorology of hot Jupiters has been characterized primarily with thermal measurements, but recent observations suggest the possibility of directly detecting the winds by observing the Doppler shift of spectral lines seen during transit. Motivated by these observations, we show how Doppler measurements can place powerful constraints on the meteorology. We show that the atmospheric circulation-and Doppler signature-of hot Jupiters splits into two regimes. Under weak stellar insolation, the day-night thermal forcing generates fast zonal jet streams from the interaction of atmospheric waves with the mean flow. In this regime, air along the terminator (as seen during transit) flows toward Earth in some regions and away from Earth in others, leading to a Doppler signature exhibiting superposed blueshifted and redshifted components. Under intense stellar insolation, however, the strong thermal forcing damps these planetary-scale waves, inhibiting their ability to generate jets. Strong frictional drag likewise damps these waves and inhibits jet formation. As a result, this second regime exhibits a circulation dominated by high-altitude, day-to-night airflow, leading to a predominantly blueshifted Doppler signature during transit. We present state-of-the-art circulation models including non-gray radiative transfer to quantify this regime shift and the resulting Doppler signatures; these models suggest that cool planets like GJ 436b lie in the first regime, HD 189733b is transitional, while planets hotter than HD 209458b lie in the second regime. Moreover, we show how the amplitude of the Doppler shifts constrains the strength of frictional drag in the upper atmospheres of hot Jupiters. If due to winds, the {approx}2 km s{sup -1} blueshift inferred on HD 209458b may require drag time constants as short as 10{sup 4}-10{sup 6} s, possibly the result of Lorentz-force braking on this planet's hot dayside.

  6. Obtaining Photospheric Electric Field Maps and Poynting Fluxes from vector magnetograms and Doppler data: Tests and Data Driving Applications

    Science.gov (United States)

    Kazachenko, Maria; Fisher, George; Welsch, Brian

    Quantitative studies of the flow of magnetic energy through the solar photosphere require a knowledge of the magnetic field vector B - and knowledge of the electric field E as well. We have modified and improved the technique Fisher et al. developed in 2012, which combines a poloidal-toroidal decomposition (PTD) to determine contributions to E from Faraday's law, with additional non-inductive contributions arising from flux emergence near polarity inversion lines, determined from Doppler measurements. The new technique, which we call the ``PTD Doppler FLCT Ideal'' (or PDFI) technique, incorporates Doppler information from non-normal viewing angles, and adopts the faster and more robust FISHPACK software for solutions of the two-dimensional Poisson equations. We demonstrate the performance using synthetic data from the anelastic pseudo-spectral ANMHD simulations that were used in the recent comparison of velocity inversion techniques (Welsch et al. 2007) and the PTD inversion (Fisher et al. 2012). We find that the PDFI method has roughly 10% reconstruction errors (it predicts roughly 100% of the photospheric Poynting flux and 110% of the helicity flux rate at normal viewing angles, consistent with Fisher et al. (2012) results, and 90% of Poynting flux and 110% helicity flux at theta=30 degrees). We conclude that the PDFI method can be routinely applied to observed magnetic field data and, as an example, apply it to the 6-day HMI/SDO vector magnetogram sequence centered at AR11158, where an X2.2 flare occurred. We discuss how our electric field maps are used to drive coronal magnetic field with a global evolutionary model, or CGEM, a collaborative effort from the UC Berkeley Space Sciences Laboratory (SSL), Stanford University, and Lockheed-Martin.

  7. Color Doppler US in the acute scrotal disease

    Energy Technology Data Exchange (ETDEWEB)

    Cha, Yoo Mi; Yang, Dal Mo; Kang, Sook Wook; Kim, Hyung Sik; Lee, Young Seok; Kim, Hyeon Hoe [Chung Ang Gil Hospital, Incheon (Korea, Republic of)

    1993-12-15

    To evaluate the utility of Color doppler US in the patients with acute scrotal pain, we retrospectively analyzed 37 patients referred for Color Doppler US of the scrotum. The diagnosis was confirmed by means of appropriate response to antibiotic treatment (31 cases) or surgery (6 cases). Thirty one of 37 patients were diagnosed as inflammatory disease (24 cases of epididymitis, 7 cases of epididymo-orchitis). Twenty three of 24cases of epididymitis had increased epididymal flow, while 6 of 7 cases of epididymo-orchitis had increased epididymal and testicular flow. Five patients were confirmed as testicular torsion, and in all cases nointratesticular blood flow was identified on the symptomatic side. In one case of torsion of appendix testis, epididymis was enlarged and there were increased signals suggesting epididymitis on Color Doppler US, but was confirmed by surgery as torsion of appendix testis. Therefore, the differentiation between torsion and inflammatory disease was possible by using Color Doppler US of the scrotum in 34 of 37 cases in our study. On the basis of our results, we may conclude that Color Doppler US can simultaneously display blood flow and detailed anatomic images, and function as an effective means of evaluating patients with acute scrotal disease

  8. Influence of speckle effect on doppler velocity measurement

    Science.gov (United States)

    Zheng, Zheng; Changming, Zhao; Haiyang, Zhang; Suhui, Yang; Dehua, Zhang; Xingyuan, Zheng; Hongzhi, Yang

    2016-06-01

    In a coherent Lidar system, velocity measurement of a target is achieved by measuring Doppler frequency shift between the echo and local oscillator (LO) signals. The measurement accuracy is proportional to the spectrum width of Doppler signal. Actually, the speckle effect caused by the scattering of laser from a target will broaden the Doppler signal's spectrum and bring uncertainty to the velocity measurement. In this paper, a theoretical model is proposed to predict the broadening of Doppler spectrum with respect to different target's surface and motion parameters. The velocity measurement uncertainty caused by the broadening of spectrum is analyzed. Based on the analysis, we design a coherent Lidar system to measure the velocity of the targets with different surface roughness and transverse velocities. The experimental results are in good agreement with theoretical analysis. It is found that the target's surface roughness and transverse velocity can significantly affect the spectrum width of Doppler signal. With the increase of surface roughness and transverse velocity, the measurement accuracy becomes worse. However, the influence of surface roughness becomes weaker when the spot size of laser beam on the target is smaller.

  9. Renal Power Doppler Ultrasonographic Evaluation of Children With Acute Pyelonephritis

    Directory of Open Access Journals (Sweden)

    Ali Pahlusi

    2011-10-01

    Full Text Available Urinary tract infections are common in children. The available gold standard method for diagnosis, Tc-99m dimercaptosuccinic acid scan is expensive and exposes patients to considerable amount of radiation. This study was performed to compare and assess the efficacy of Power Doppler Ultrasound versus Tc-99m DMSA scan for diagnosis of acute pyelonephritis. A quasi experimental study was conducted on 34 children with mean age of 2.82.7 years who were hospitalized with their first episode of febrile urinary tract infection. All children were evaluated in the first 3 days of admission by Doppler Ultrasound and Tc-99m DMSA scan. Patients with congenital structural anomalies were excluded. Each kidney was divided into three zones. The comparison between efficacy of Doppler Ultrasound and DMSA scan was carried out based on number of patients and on classified renal units. Based on the number of patients enrolled; the sensitivity, specificity, positive and negative predictive values and accuracy of Doppler Ultrasound were 89%, 53%, 70%, 80% and 74%, respectively but based on the renal units, it was 66%, 81%, 46%, 91% and 79% , respectively. Although Doppler Ultrasound has the potential for identifying acute pyelonephritis in children, but it is still soon to replace DMSA scan.

  10. Laser Doppler perfusion monitoring and imaging of blood microcirculation

    Science.gov (United States)

    Nilsson, Gert E.; Wardell, Karin

    1994-07-01

    Laser Doppler perfusion monitoring is a method of assessing tissue perfusion based on measurements performed using Doppler broadening of monochromatic light scattered in moving blood cells. Ever since laser Doppler perfusion monitors became available about 15 years ago they have been used in numerous applications in both clinical and laboratory settings. The high spatial resolution has in practice manifested itself as one of the main limitations of the method. The reason for this is the difficulty in attaining reproducible values at successive measurement sites because most skin tissue possesses a substantial variation in blood flow even at adjacent measurement sites. In order to overcome this difficulty the laser Doppler perfusion imager was developed. In this camera-like device, the laser beam successively scans the tissue and the Doppler components of the backscattered light are detected by a remote photodiode. After a scanning procedure is complete, a color-coded perfusion map showing the spatial variation of skin blood flow is displayed on a monitor. The operating principle and early applications of this emerging technology are addressed in further detail.

  11. Response of a Doppler canceling system to plane gravitational waves

    Science.gov (United States)

    Caporali, A.

    1982-01-01

    This paper discusses the interaction of long periodic gravitational waves with a three-link microwave system known as the Doppler canceling system. This system, which was developed for a gravitational red-shift experiment, uses one-way and two-way Doppler information to construct the beat signal of two reference oscillators moving with respect to each other. The geometric-optics approximation is used to derive the frequency shift produced on a light signal propagating in a gravitational-wave space-time. The signature left on the Doppler-cancelled beat by bursts and continuous gravitational waves is analyzed. A comparison is made between the response to gravitational waves of the Doppler canceling system and that of a (NASA) Doppler tracking system which employs two-way, round-trip radio waves. A threefold repetition of the gravitational wave form is found to be a common feature of the response functions of both systems. These two functions otherwise exhibit interesting differences.

  12. Musculoskeletal colour/power Doppler in sports medicine: image parameters, artefacts, image interpretation and therapy

    DEFF Research Database (Denmark)

    Boesen, M I; Boesen, Mikael; Kønig, Merete Juhl;

    2010-01-01

    This review article discusses the aspects of sports medicine where musculoskeletal Doppler ultrasound has valuable contribution in diagnosis and/or treatment of some of the typical musculoskeletal sports injuries. Also, conditions where the Doppler ultrasound has no value are discussed. Some...... guidelines and recommendations are based on personal experience since no evidence in literature exists. The basic technical background of Doppler ultrasound and typical artefacts will be discussed, in order to understand and interpret the Doppler result. Recommendations for the Doppler settings are given...... in relevant sections. Ultrasound guided treatments where the Doppler result is used as a guide are mentioned and discussed....

  13. Wind measurements in Saturn's atmosphere with UVES/VLT ground-based Doppler velocimetry

    Science.gov (United States)

    Machado, Pedro; Silva, Miguel; Peralta, Javier; Luz, David; Sánchez-Lavega, Agustin; Hueso, Ricardo

    2016-04-01

    We will present preliminary Doppler wind velocity results of Saturn's zonal flow at cloud level. Our aim is help to constrain the characterization of the equatorial jet at cloud level and the latitudinal variation of the zonal winds, to measure its spatial and temporal variability, to contribute to monitor the variability in order to achieve a better understanding of the dynamics of Saturn's zonal winds, whose equatorial jet has a complex vertical structure and temporal variability (Sanchez-Lavega et al., Nature, 423, 623, 3003; Garcia-Melendo et al., Geophys. Res. Lett., 37, L22204. 2010). Finally, the complementarity with Cassini, providing an independent set of observations. The UVES/VLT instrument has been used, which simultaneously achieves high spectral resolving power and high spatial resolution. The field has been derotated in order to have the aperture aligned perpendicularly to Saturn's rotation axis. In this configuration, spatial information in the East-West direction is preserved in a set of spectra in the direction perpendicular to dispersion. The technique of absolute accelerometry (AA, Connes, 1985, ApSS 110, 211) has been applied to the backscattered solar spectrum in order to determine the Doppler shift associated with the zonal circulation. Our measurements have been made in the wavelength range of 480-680 nm. Previously we successfully adapted this Doppler velocimetry technique for measuring winds at Venus cloud tops (Machado et al. 2012). In the present study we will show the adaptation of this method for Saturn's case. Since the AA technique only allows to compare spectra where the line shifts are within the line width, in fast rotating atmospheres (as is the case of Saturn) the spectra must be compared by pairs from adjacent areas of the disk (adjacent pixels in the slit). We will use coordinated observations from the Cassini's Visible and Infrared Mapping Spectrometer (VIMS), in order to compare with the Doppler winds obtained from the UVES

  14. Selection functions in doppler planet searches

    Science.gov (United States)

    O'Toole, S. J.; Tinney, C. G.; Jones, H. R. A.; Butler, R. P.; Marcy, G. W.; Carter, B.; Bailey, J.

    2009-01-01

    We present a preliminary analysis of the sensitivity of Anglo-Australian Planet Search data to the orbital parameters of extrasolar planets. To do so, we have developed new tools for the automatic analysis of large-scale simulations of Doppler velocity planet search data. One of these tools is the two-dimensional Keplerian Lomb-Scargle (LS) periodogram that enables the straightforward detection of exoplanets with high eccentricities (something the standard LS periodogram routinely fails to do). We used this technique to redetermine the orbital parameters of HD20782b, with one of the highest known exoplanet eccentricities (e = 0.97 +/- 0.01). We also derive a set of detection criteria that do not depend on the distribution functions of fitted Keplerian orbital parameters (which we show are non-Gaussian with pronounced, extended wings). Using these tools, we examine the selection functions in orbital period, eccentricity and planet mass of Anglo-Australian Planet Search data for three planets with large-scale Monte Carlo like simulations. We find that the detectability of exoplanets declines at high eccentricities. However, we also find that exoplanet detectability is a strong function of epoch-to-epoch data quality, number of observations and period sampling. This strongly suggests that simple parametrizations of the detectability of exoplanets based on `whole-of-survey' metrics may not be accurate. We have derived empirical relationships between the uncertainty estimates for orbital parameters that are derived from least-squares Keplerian fits to our simulations and the true 99 per cent limits for the errors in those parameters, which are larger than equivalent Gaussian limits by the factors of 5-10. We quantify the rate at which false positives are made by our detection criteria, and find that they do not significantly affect our final conclusions. And finally, we find that there is a bias against measuring near-zero eccentricities, which becomes more significant

  15. Ecocardiografia modo Doppler pulsado em gatos clinicamente sadios Pulsed wave Doppler echocardiography in clinically healthy cats

    Directory of Open Access Journals (Sweden)

    R.O. Carvalho

    2006-06-01

    Full Text Available Estudou-se o fluxo sangüíneo através das quatro valvas cardíacas em 30 gatos clinicamente sadios, com idade entre um e cinco anos e peso médio de 4,08kg, por meio da ecocardiografia modo Doppler pulsado. Foram medidas a velocidade máxima e a velocidade média dos fluxos, e realizou-se uma análise qualitativa dos seus perfis. Os animais foram sedados pela combinação de quetamina (12mg/kg e acepromazina (0,04mg/kg, aplicados por via intramuscular. Observou-se correlação positiva entre os parâmetros avaliados e a freqüência cardíaca, com exceção daqueles medidos no fluxo da valva aórtica. Não se observou correlação entre velocidades máxima e média e freqüência cardíaca e entre aquelas e peso corporal, e não houve diferença entre sexos.Pulsed wave Doppler echocardiography was used to study blood flow across the cardiac valves in 30 five-year-old cats (average body weight = 4.08kg. Animals were sedated using a combination of ketamin (12mg/kg, IM and acepromazin (0.04mg/kg, IM. Peak and mean velocities were determined, and blood flow patterns were recorded at the four cardiac valves. All variables, except those characterizing aortic valve flow, were positively correlated with heart rate. Blood flow variables were not correlated, however, with body weight; and there were no differences between males and females.

  16. Magnetic Doppler imaging considering atmospheric structure modifications due to local abundances: a luxury or a necessity?

    Science.gov (United States)

    Kochukhov, O.; Wade, G. A.; Shulyak, D.

    2012-04-01

    Magnetic Doppler imaging is currently the most powerful method of interpreting high-resolution spectropolarimetric observations of stars. This technique has provided the very first maps of stellar magnetic field topologies reconstructed from time series of full Stokes vector spectra, revealing the presence of small-scale magnetic fields on the surfaces of Ap stars. These studies were recently criticised by Stift et al., who claimed that magnetic inversions are not robust and are seriously undermined by neglecting a feedback on the Stokes line profiles from the local atmospheric structure in the regions of enhanced metal abundance. We show that Stift et al. misinterpreted published magnetic Doppler imaging results and consistently neglected some of the most fundamental principles behind magnetic mapping. Using state-of-the-art opacity sampling model atmosphere and polarized radiative transfer codes, we demonstrate that the variation of atmospheric structure across the surface of a star with chemical spots affects the local continuum intensity but is negligible for the normalized local Stokes profiles except for the rare situation of a very strong line in an extremely Fe-rich atmosphere. For the disc-integrated spectra of an Ap star with extreme abundance variations, we find that the assumption of a mean model atmosphere leads to moderate errors in Stokes I but is negligible for the circular and linear polarization spectra. Employing a new magnetic inversion code, which incorporates the horizontal variation of atmospheric structure induced by chemical spots, we reconstructed new maps of magnetic field and Fe abundance for the bright Ap star α2 CVn. The resulting distribution of chemical spots changes insignificantly compared to the previous modelling based on a single model atmosphere, while the magnetic field geometry does not change at all. This shows that the assertions by Stift et al. are exaggerated as a consequence of unreasonable assumptions and

  17. Doppler tomography of the Double Periodic Variable HD 170582 at low and high stage

    CERN Document Server

    Mennickent, R E; Cabezas, M; Djurašević, G

    2016-01-01

    HD170582 is an interacting binary of the Double Periodic Variable (DPV) type, showing ellipsoidal variability with a period of 16.87 days along with a long photometric cycle of 587 days. It was recently studied by Mennickent et al. (2015), who found a slightly evolved B-type star surrounded by a luminous accretion disc fed by a Roche-lobe overflowing A-type giant. Here we extend their analysis presenting new spectroscopic data and studying the Balmer emission lines. We find orbitally modulated double-peak Halpha and Hbeta emissions whose strength also vary in the long-term. In addition, Doppler maps of the emission lines reveal sites of enhanced line emission in the 1st and 4th velocity quadrants, the first one consistent with the position of one of the bright zones detected by the light curve analysis. We find a difference between Doppler maps at high and low stage of the long cycle; evidence that the emission is optically thicker at high state in the stream-disc impact region, possibly reflecting a larger m...

  18. A misaligned prograde orbit for Kepler-13 Ab via doppler tomography

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Marshall C.; Cochran, William D.; Gullikson, Kevin [Department of Astronomy and McDonald Observatory, University of Texas at Austin, 2515 Speedway, Stop C1400, Austin, TX 78712 (United States); Albrecht, Simon; Winn, Joshua N. [Department of Physics and Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Dodson-Robinson, Sarah E., E-mail: mjohnson@astro.as.utexas.edu [Department of Physics and Astronomy, University of Delaware, 217 Sharp Lab, Newark, DE 19716 (United States)

    2014-07-20

    Transiting planets around rapidly rotating stars are not amenable to precise radial velocity observations, such as are used for planet candidate validation, as they have wide, rotationally broadened stellar lines. Such planets can, however, be observed using Doppler tomography, wherein stellar absorption line profile distortions during transit are spectroscopically resolved. This allows the validation of transiting planet candidates and the measurement of the stellar spin-planetary orbit (mis)alignment, which is an important statistical probe of planetary migration processes. We present Doppler tomographic observations that provide direct confirmation of the hot Jupiter Kepler-13 Ab and also show that the planet has a prograde, misaligned orbit with λ = 58.°6 ± 2.°0. Our measured value of the spin-orbit misalignment is in significant disagreement with the value of λ = 23° ± 4° previously measured by Barnes et al. (2011) from the gravity-darkened Kepler light curve. We also place an upper limit of 0.75 M{sub ☉} (95% confidence) on the mass of Kepler-13 C, the spectroscopic companion to Kepler-13 B, which is the proper-motion companion of the planet host star Kepler-13 A.

  19. Vascular waveform analysis of flap-feeding vessels using color Doppler ultrasonography.

    Science.gov (United States)

    Ogino, Akihiro; Onishi, Kiyoshi

    2014-01-01

    We performed vascular waveform analysis of flap-feeding vessels using color Doppler ultrasonography and evaluated the blood flow in the flaps prior to surgery. Vascular waveform analysis was performed in 19 patients. The analyzed parameters included the vascular diameter, flow volume, flow velocity, resistance index, pulsatility index, and acceleration time. The arterial waveform was classified into 5 types based on the partially modified blood flow waveform classification reported by Hirai et al.; in particular, D-1a, D-1b, and D-2 were considered as normal waveforms. They were 4 patients which observed abnormal vascular waveform among 19 patients (D-4 : 1, D-3 : 1, and Poor detect : 2). The case which presented D-4 waveform changed the surgical procedure, and a favorable outcome was achieved. Muscle flap of the case which presented D-3 waveform was partially necrosed. The case which detected blood flow poorly was judged to be the vascular obstruction of the internal thoracic artery. In the evaluation of blood flow in flaps using color Doppler ultrasonography, determination of not only basic blood flow information, such as the vascular distribution and diameter and flow velocity, but also the flow volume, vascular resistance, and arterial waveform is essential to elucidate the hemodynamics of the flap.

  20. Non-Gaussianity and CMB aberration and Doppler

    CERN Document Server

    Catena, Riccardo; Notari, Alessio; Renzi, Alessandro

    2013-01-01

    The peculiar motion of an observer with respect to the CMB rest frame induces a deflection in the arrival direction of the observed photons (also known as CMB aberration) and a Doppler shift in the measured photon frequencies. As a consequence, aberration and Doppler effects induce non trivial correlations between the harmonic coefficients of the observed CMB temperature maps. In this paper we investigate whether these correlations generate a bias on Non-Gaussianity estimators $f_{NL}$. We perform this analysis simulating a large number of temperature maps with Planck-like resolution (lmax $= 2000$) as different realizations of the same cosmological fiducial model (WMAP7yr). We then add to these maps aberration and Doppler effects employing a modified version of the HEALPix code. We finally evaluate a generalization of the Komatsu, Spergel and Wandelt Non-Gaussianity estimator for all the simulated maps, both when peculiar velocity effects have been considered and when these phenomena have been neglected. Usi...

  1. It's all in the past: Deconstructing the temporal Doppler effect.

    Science.gov (United States)

    Aksentijevic, Aleksandar; Treider, John Melvin Gudnyson

    2016-10-01

    A recent study reported an asymmetry between subjective estimates of future and past distances with passive estimation and virtual movement. The temporal Doppler effect refers to the contraction of future distance judgments relative to past ones. We aimed to replicate the effect using real and imagined motion in both directions as well as different temporal perspectives. To avoid the problem of subjective anchoring, we compared real- and imagined-, ego- and time-moving conditions to a control group. Generally, Doppler-like distortion was only observed in conditions in which the distance between the participant and a frontal target increased. No effects of temporal perspective were observed. The "past-directed temporal Doppler effect" presents a challenge for the current theories of temporal cognition by demonstrating absence of psychological movement into the future. The effect could open new avenues in memory research and serve as a starting point in a systematic examination of how the humans construct future.

  2. Rotational Doppler Effect: A Probe for Molecular Orbitals Anisotropy.

    Science.gov (United States)

    Miao, Quan; Travnikova, Oksana; Gel'mukhanov, Faris; Kimberg, Victor; Sun, Yu-Ping; Thomas, T Darrah; Nicolas, Christophe; Patanen, Minna; Miron, Catalin

    2015-05-01

    The vibrationally resolved X-ray photoelectron spectra of X2Σg+(3σg−1) and B2Σu+(2σu−1) states of N2+ were recorded for different photon energies and orientations of the polarization vector. Clear dependencies of the spectral line widths on the X-ray polarization as well as on the symmetry of the final electronic states are observed. Contrary to the translational Doppler, the rotational Doppler broadening is sensitive to the photoelectron emission anisotropy. On the basis of theoretical modeling, we suggest that the different rotational Doppler broadenings observed for gerade and ungerade final states result from a Young's double-slit interference phenomenon.

  3. Theoretical analysis and experimental verification on optical rotational Doppler effect

    Science.gov (United States)

    Zhou, Hailong; Fu, Dongzhi; Dong, Jianji; Zhang, Pei; Zhang, Xinliang

    2016-05-01

    We present a theoretical model to sufficiently investigate the optical rotational Doppler effect based on modal expansion method. We find that the frequency shift content is only determined by the surface of spinning object and the reduced Doppler shift is linear to the difference of mode index between input and output orbital angular momentum (OAM) light, and linear to the rotating speed of spinning object as well. An experiment is carried out to verify the theoretical model. We explicitly suggest that the spatial spiral phase distribution of spinning object determines the frequency content. The theoretical model makes us better understand the physical processes of rotational Doppler effect, and thus has many related application fields, such as detection of rotating bodies, imaging of surface and measurement of OAM light.

  4. Improved technique for blood flow velocity measurement using Doppler effect

    Science.gov (United States)

    Valadares Oliveira, Eduardo J.; Nantes Button, Vera L. d. S.; Maia, Joaquim M.; Costa, Eduardo T.

    2002-04-01

    The Doppler velocimeter developed allows to determine the angle between the ultrasonic beam and the velocity vector of the flow, and to calculate the precise blood flow in a vessel. Four piezoelectric transducers constitute the Doppler velocimeter. Three of these transducers are positioned to form an equilateral triangle (base of a pyramid). When these transducers move simultaneously, backward or forward from the initial position, the emitted ultrasonic beams focalize on a position (peak of the pyramid) closer or farther from the transducers faces, according to the depth of the vessel where we intend to measure de flow. The angle between the transducers allows adjusting the height of this pyramid and the position of the focus (where the three beams meet). A forth transducer is used to determine the diameter of the vessel and monitor the position of the Doppler velocimeter relative to the vessel. Simulation results showed that with this technique is possible to accomplish precise measurement of blood flow.

  5. One way Doppler Extractor. Volume 2: Digital VCO technique

    Science.gov (United States)

    Nossen, E. J.; Starner, E. R.

    1974-01-01

    A feasibility analysis and trade-offs for a one-way Doppler extractor using digital VCO techniques is presented. The method of Doppler measurement involves the use of a digital phase lock loop; once this loop is locked to the incoming signal, the precise frequency and hence the Doppler component can be determined directly from the contents of the digital control register. The only serious error source is due to internally generated noise. Techniques are presented for minimizing this error source and achieving an accuracy of 0.01 Hz in a one second averaging period. A number of digitally controlled oscillators were analyzed from a performance and complexity point of view. The most promising technique uses an arithmetic synthesizer as a digital waveform generator.

  6. Holographic laser Doppler imaging of microvascular blood flow

    CERN Document Server

    Magnain, C; Boucneau, T; Simonutti, M; Ferezou, I; Rancillac, A; Vitalis, T; Sahel, J A; Paques, M; Atlan, M

    2014-01-01

    We report on local superficial blood flow monitoring in biological tissue from laser Doppler holographic imaging. In time averaging recording conditions, holography acts as a narrowband bandpass filter, which, combined with a frequency shifted reference beam, permits frequency selective imaging in the radiofrequency range. These Doppler images are acquired with an off axis Mach Zehnder interferometer. Microvascular hemodynamic components mapping is performed in the cerebral cortex of the mouse and the eye fundus of the rat with near-infrared laser light without any exogenous marker. These measures are made from a basic inverse method analysis of local first order optical fluctuation spectra at low radiofrequencies, from 0 Hz to 100 kHz. Local quadratic velocity is derived from Doppler broadenings induced by fluid flows, with elementary diffusing wave spectroscopy formalism in backscattering configuration. We demonstrate quadratic mean velocity assessment in the 0.1 to 10 millimeters per second range in vitro ...

  7. Theoretical analysis and experimental verification on optical rotational Doppler effect

    CERN Document Server

    Zhou, Hailong; Dong, Jianji; Zhang, Pei; Zhang, Xinliang

    2016-01-01

    We present a theoretical model to sufficiently investigate the optical rotational Doppler effect based on modal expansion method. We find that the frequency shift content is only determined by the surface of spinning object and the reduced Doppler shift is linear to the difference of mode index between input and output orbital angular momentum (OAM) light, and linear to the rotating speed of spinning object as well. An experiment is carried out to verify the theoretical model. We explicitly suggest that the spatial spiral phase distribution of spinning object determines the frequency content. The theoretical model makes us better understand the physical processes of rotational Doppler effect, and thus has many related application fields, such as detection of rotating bodies, imaging of surface and measurement of OAM light.

  8. Curvelet Transform-Based Denoising Method for Doppler Frequency Extraction

    Institute of Scientific and Technical Information of China (English)

    HOU Shu-juan; WU Si-liang

    2007-01-01

    A novel image denoising method based on curvelet transform is proposed in order to improve the performance of Doppler frequency extraction in low signal-noise-ratio (SNR) environment. The echo can be represented as a gray image with spectral intensity as its gray values by time-frequency transform. And the curvelet coefficients of the image are computed. Then an adaptive soft-threshold scheme based on dual-median operation is implemented in curvelet domain. After that, the image is reconstructed by inverse curvelet transform and the Doppler curve is extracted by a curve detection scheme. Experimental results show the proposed method can improve the detection of Doppler frequency in low SNR environment.

  9. The Doppler paradigm and the APEX-EPOS-ORANGE quandary

    CERN Document Server

    Griffin, J J

    1996-01-01

    The experimental detection of the sharp lines of the \\ee Puzzle is viewed as a struggle against Doppler broadening. Gedanken experiments which are realistic in zeroth order of detail are analyzed to show that the ORANGE and EPOS/I geometries select narrower slices of a Doppler broadened line than spherically inclusive (APEX and EPOS/II --like) apparati. Roughly speaking, the latter require event-by-event Doppler reconstruction simply to regain an even footing with the former. This suggests that APEX' or EPOS/II's coincident pair distributions must be statistically superior to those of EPOS/I or ORANGE in order to support a comparable inference about sharp structure. Under present circumstances, independent alternative data is invaluable. Therefore, a corroboration of Sakai's 330.1 keV (< 3 keV wide) electron line in few MeV e^+ or e^- bombardments of U and Th targets could prove crucial.

  10. Coupling airborne laser scanning and acoustic Doppler current profiler data to model stream rating curves

    Science.gov (United States)

    Lam, N.; Lyon, S. W.; Kean, J. W.

    2015-12-01

    The rating curve enables the translation of water depth into discharge through a reference cross section. Errors in estimating stream channel geometry can therefore result in increased discharge uncertainty. This study investigates coupling national-scale airborne laser scanning (ALS) and acoustic Doppler current profiler (ADCP) bathymetric survey data for generating stream rating curves. Specifically, stream channel geometries were generated from coupled ALS and ADCP scanning data collected for a well-monitored site located in northern Sweden. These data were used to define the hydraulic geometry required by a physically-based 1-D hydraulic model. The results of our study demonstrate that the effects of potential scanning data errors on the model generated rating curve were less than the uncertainties due to stream gauging measurements and empirical rating curve fitting. Further analysis of the ALS data showed that an overestimation of the streambank elevation (the main scanning data error) was primarily due to vegetation that could be adjusted for through a root-mean-square-error bias correction. We consider these findings encouraging as hydrometric agencies can potentially leverage national-scale ALS and ADCP instrumentation to reduce the cost and effort required for maintaining and establish rating curves at gauging stations.

  11. A review of Doppler ultrasound quality assurance protocols and test devices.

    Science.gov (United States)

    Browne, Jacinta E

    2014-11-01

    In this paper, an overview of Doppler ultrasound quality assurance (QA) testing will be presented in three sections. The first section will review the different Doppler ultrasound parameters recommended by professional bodies for use in QA protocols. The second section will include an evaluation and critique of the main test devices used to assess Doppler performance, while the final section of this paper will discuss which of the wide range of test devices have been found to be most suitable for inclusion in Doppler QA programmes. Pulsed Wave Spectral Doppler, Colour Doppler Imaging QA test protocols have been recommended over the years by various professional bodies, including the UK's Institute of Physics and Engineering in Medicine (IPEM), the American Institute for Ultrasound in Medicine (AIUM), and the International Electrotechnical Commission (IEC). However, despite the existence of such recommended test protocols, very few commercial or research test devices exist which can measure the full range of both PW Doppler ultrasound and colour Doppler imaging performance parameters, particularly quality control measurements such as: (i) Doppler sensitivity (ii) colour Doppler spatial resolution (iii) colour Doppler temporal resolution (iv) colour Doppler velocity resolution (v) clutter filter performance and (vi) tissue movement artefact suppression. In this review, the merits of the various commercial and research test devices will be considered and a summary of results obtained from published studies which have made use of some of these Doppler test devices, such as the flow, string, rotating and belt phantom, will be presented.

  12. UltraFast Doppler ultrasonography for hepatic vessels of liver recipients: preliminary experiences

    Energy Technology Data Exchange (ETDEWEB)

    Hur, Bo Yun; Lee, Jae Young; Chu, A Jung; Kim, Se Hyung; Han, Joon Koo; Choi, Byung Ihn [Seoul National University Hospital, Seoul (Korea, Republic of)

    2015-01-15

    The purpose of this study was to investigate the value of UltraFast Doppler ultrasonography (US) for evaluating hepatic vessels in liver recipients. Thirty-nine liver Doppler US sessions were conducted in 20 liver recipients. Each session consisted of UltraFast and conventional liver Doppler US in a random order. We compared the velocities and phasicities of the hepatic vessels, duration of each Doppler study, occurrence of technical failures, and differences in clinical decisions. The velocities and resistive index values of hepatic vessels showed a strong positive correlation between the two Doppler studies (mean R=0.806; range, 0.710 to 0.924). The phasicities of the hepatic vessels were the same in both Doppler US exams. With respect to the duration of the Doppler US exam, there was no significant difference between the UltraFast (251±99 seconds) and conventional (231±117 seconds) Doppler studies (P=0.306). In five poor breath-holders, in whom the duration of conventional Doppler US was longer, UltraFast Doppler US (272±157 seconds) required a shorter time than conventional Doppler US (381±133 seconds; P=0.005). There was no difference between the two techniques with respect to technical failures and clinical decisions. UltraFast Doppler US is clinically equivalent to conventional Doppler US with advantages for poor breath-holders during the post-liver transplantation work-up.

  13. The US color Doppler in acute renal failure.

    Science.gov (United States)

    Nori, G; Granata, A; Leonardi, G; Sicurezza, E; Spata, C

    2004-12-01

    Imaging techniques, especially ultrasonography and Doppler, can give an effective assistance in the differential diagnosis of acute renal failure (ARF). An resistance Index (RI) value >0.75 is reported as optimal in attempting differential diagnosis between acute tubular necrosis (ANT) and prerenal ARF. In hepatorenal syndrome (HRS) RIs is very increased. In some renal vasculitis, as nodose panarteritis (PN), hemolytic-uremic syndrome (HUS), thrombotic thrombocytopenic purpura (TTP), parenchymal perfusion is reduced and RI increased. In lupus nephritis the RI values are correlated with creatinine level and normal RI are considered as a good prognostic tool. In acute primitive or secondary glomerulonephritis (GN), RI value is normal, with diffuse parenchymal hypervascularization. In acute crescentic and proliferative GN and tubulo-interstitial disease, color Doppler (CD) and power Doppler (PD) reveal a decreased renal parenchymal perfusion, which correlates with increased RI values. In acute thrombosis of renal artery, US color Doppler (DUS) reveals either an absence of Doppler signal or a tardus-parvus pulse distal to the vascular obstruction. In this situation it is possible to visualize hyperthropic perforating vessels that redirect their flow from the capsular plexus to the renal parenchyma. In acute thrombosis of the renal vein Doppler analysis of parenchymal vessels reveals remarkable RI values, sometimes with reversed diastolic flow. In postrenal ARF an adjunct to the differentiation between obstruction and non obstructive dilatation can be found through RIs. Diagnostic criteria of obstruction as reported by literature are: RI>0.70 in the obstructed kidney and, mostly, a difference in RI between the 2 kidneys >0.06-0.1.

  14. Reducing Antenna Mechanical Noise in Precision Doppler Tracking

    Science.gov (United States)

    Armstrong, J. W.; Estabrook, F. B.; Asmar, S. W.; Iess, L.; Tortora, P.

    2006-05-01

    Precision Doppler tracking of deep-space probes is central to spacecraft navigation and many radio science investigations. The most sensitive Doppler observations to date have been taken using the NASA/JPL Deep Space Network (DSN) antenna DSS 25, a 34-m-diameter beam-waveguide station especially instrumented with simultaneous X-band (approximately 8.4-GHz) and Ka-band (approximately 32-GHz) links and tropospheric scintillation calibration equipment, tracking the Cassini spacecraft. These Cassini observations achieved Doppler fractional frequency stability (Doppler frequency fluctuation divided by center frequency, Delta f / f_o ) of approximately 3 x 10^-15 at tau = 1000 s integration. In those very-high-sensitivity tracks, the leading disturbance was antenna mechanical noise: time-dependent unmodeled physical motion of the ground antenna's phase center caused by antenna sag as the elevation angle changed, unmodeled subreflector motion, wind loading, bulk motion of the antenna as it rolled over irregularities in the supporting azimuth ring, differential thermal expansion of the structure, etc. This noise has seemed irreducible at reasonable cost, since it is unclear how to build a practical, large, moving, steel structure having mechanical stability significantly better than that of current tracking stations. Here we show how the mechanical noise of a large tracking antenna can effectively be removed when two-way Doppler tracking data from an existing DSN antenna are suitably combined with simultaneous tracking data using an ancillary (smaller and stiffer) antenna. Using our method, the mechanical noise in the final Doppler observable can be reduced, substantially, to that of the stiffer antenna.

  15. Single pass Doppler positioning for Search and Rescue satellite missions

    Science.gov (United States)

    Schmid, P. E.; Vonbun, F. O.; Lynn, J. J.

    1976-01-01

    This paper describes the implementation of beacon location experiments involving the NASA Nimbus-6 and the Amateur Satellite Corporation (AMSAT) Oscar-6 and Oscar-7 spacecraft. The purpose of these experiments is to demonstrate the feasibility of determining the geographical location of a low power VHF 'distress beacon' via satellite. Doppler data collected during satellite passes is reduced in a mini-computer by means of a simple algorithm resulting in the simultaneous recovery of the unknown receiver coordinates and the unknown Doppler bias frequency. Results indicate point positioning to within a few kilometers - which is within the required accuracies for the positioning of downed aircraft for Search/Rescue missions.

  16. Experimental Verification of Doppler Effect with the Refraction Method

    Institute of Scientific and Technical Information of China (English)

    Lie FENG; Jia-bi CHEN; Jing-bin HU; Song-lin ZHUANG

    2010-01-01

    The traditional methad of measuring Dopplr Effect is either reflection or dispersion.This article clarifies that it can also verify the Doppler Effect with the refraction method.We have designed the experimental system with the method of optical heterodyne,using the refraction light beam from a prism,and made the experiment.The experimental results are in accordance with the theoreticai calculation.It is very useful in some particular case,such as in Negative-Index Materials(NIM),to verify the Doppler Effect with this method.

  17. Multigroup Free-atom Doppler-broadening Approximation. Theory

    Energy Technology Data Exchange (ETDEWEB)

    Gray, Mark Girard [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-11-06

    Multigroup cross sections at a one target temperature can be Doppler-broadened to multigroup cross sections at a higher target temperature by matrix multiplication if the group structure suf- ficiently resolves the original temperature continuous energy cross section. Matrix elements are the higher temperature group weighted averages of the integral over the lower temperature group boundaries of the free-atom Doppler-broadening kernel. The results match theory for constant and 1/v multigroup cross sections at 618 lanl group structure resolution.

  18. Aerial ultrasonic micro Doppler sonar detection range in outdoor environments.

    Science.gov (United States)

    Bradley, Marshall; Sabatier, James M

    2012-03-01

    Current research demonstrates that micro Doppler sonar has the capability to uniquely identify the presence of a moving human, making it an attractive component in surveillance systems for border security applications. Primary environmental factors that limit sonar performance are two-way spreading losses, ultrasonic absorption, and backscattered energy from the ground that appears at zero Doppler shift in the sonar signal processor. Spectral leakage from the backscatter component has a significant effect on sonar performance for slow moving targets. Sonar performance is shown to rapidly decay as the sensor is moved closer to the ground due to increasing surface backscatter levels.

  19. Miniature Laser Doppler Velocimeter for Measuring Wall Shear

    Science.gov (United States)

    Gharib, Morteza; Modarress, Darius; Forouhar, Siamak; Fourguette, Dominique; Taugwalder, Federic; Wilson, Daniel

    2005-01-01

    A miniature optoelectronic instrument has been invented as a nonintrusive means of measuring a velocity gradient proportional to a shear stress in a flow near a wall. The instrument, which can be mounted flush with the wall, is a variant of a basic laser Doppler velocimeter. The laser Doppler probe volume can be located close enough to the wall (as little as 100 micron from the surface) to lie within the viscosity-dominated sublayer of a turbulent boundary layer. The instrument includes a diode laser, the output of which is shaped by a diffractive optical element (DOE) into two beams that have elliptical cross sections with very high aspect ratios.

  20. Optical Doppler tomography based on a field programmable gate array

    DEFF Research Database (Denmark)

    Larsen, Henning Engelbrecht; Nilsson, Ronnie Thorup; Thrane, Lars

    2008-01-01

    We report the design of and results obtained by using a field programmable gate array (FPGA) to digitally process optical Doppler tomography signals. The processor fits into the analog signal path in an existing optical coherence tomography setup. We demonstrate both Doppler frequency and envelope...... extraction using the Hilbert transform, all in a single FPGA. An FPGA implementation has certain advantages over general purpose digital signal processor (DSP) due to the fact that the processing elements operate in parallel as opposed to the DSP. which is primarily a sequential processor....

  1. AL Amyloidosis

    Directory of Open Access Journals (Sweden)

    Desport Estelle

    2012-08-01

    Full Text Available Abstract Definition of the disease AL amyloidosis results from extra-cellular deposition of fibril-forming monoclonal immunoglobulin (Ig light chains (LC (most commonly of lambda isotype usually secreted by a small plasma cell clone. Most patients have evidence of isolated monoclonal gammopathy or smoldering myeloma, and the occurrence of AL amyloidosis in patients with symptomatic multiple myeloma or other B-cell lymphoproliferative disorders is unusual. The key event in the development of AL amyloidosis is the change in the secondary or tertiary structure of an abnormal monoclonal LC, which results in instable conformation. This conformational change is responsible for abnormal folding of the LC, rich in β leaves, which assemble into monomers that stack together to form amyloid fibrils. Epidemiology AL amyloidosis is the most common type of systemic amyloidois in developed countries with an estimated incidence of 9 cases/million inhabitant/year. The average age of diagnosed patients is 65 years and less than 10% of patients are under 50. Clinical description The clinical presentation is protean, because of the wide number of tissues or organs that may be affected. The most common presenting symptoms are asthenia and dyspnoea, which are poorly specific and may account for delayed diagnosis. Renal manifestations are the most frequent, affecting two thirds of patients at presentation. They are characterized by heavy proteinuria, with nephrotic syndrome and impaired renal function in half of the patients. Heart involvement, which is present at diagnosis in more than 50% of patients, leading to restrictive cardiopathy, is the most serious complication and engages prognosis. Diagnostic methods The diagnosis relies on pathological examination of an involved site showing Congo red-positive amyloid deposits, with typical apple-green birefringence under polarized light, that stain positive with an anti-LC antibody by immunohistochemistry and

  2. Positron life time and annihilation Doppler broadening measurements on transition metal complexes

    Energy Technology Data Exchange (ETDEWEB)

    Levay, B. (Eoetvoes Lorand Tudomanyegyetem, Budapest (Hungary). Fizikai Kemiai es Radiologiai Tanszek); Varhelyi, Cs. (Babes-Bolyai Univ., Cluj (Romania)); Burger, K. (Eoetvoes Lorand Tudomanyegyetem, Budapest (Hungary). Szervetlen es Analitikai Kemiai Intezet)

    1982-01-01

    Positron life time and annihilation Doppler broadening measurements have been carried out on 44 solid coordination compounds. Several correlations have been found between the annihilation life time (tau/sub 1/) and line shape parameters (L) and the chemical structure of the compounds. Halide ligands were the most active towards positrons. This fact supports the assumption on the possible formation of (e/sup +/X/sup -/) positron-halide bound state. The life time was decreasing and the annihilation energy spectra were broadening with the increasing negative character of the halides. The aromatic base ligands affected the positron-halide interaction according to their basicity and space requirement and thus they indirectly affected the annihilation parameters, too. In the planar and tetrahedral complexes the electron density on the central met--al ion affected directly the annihilation parameters, while in the octahedral mixed complexes it had only an ind--irect effect through the polarization of the halide ligands.

  3. On the precipitation sequence in a Ni-based superalloy: A Coincidence Doppler Broadening study

    Energy Technology Data Exchange (ETDEWEB)

    Macchi, C.E. [IFIMAT, UNCentro and CONICET, Pinto 399, B7000GHG Tandil (Argentina); Somoza, A. [IFIMAT, UNCentro and CICPBA, Pinto 399, B7000GHG Tandil (Argentina); Santos, G. [NIECyT, UNCentro, Pinto 399, B7000GHG Tandil (Argentina); Petkov, M. [Jet Propulsion Lab, California Institute of Technology, Pasadena, CA 91109 (United States); Lynn, K.G. [Department of Physics, Washington State University, Pullman WA 99164-2814 (United States)

    2007-07-01

    The precipitation sequence at 700 C of the Ni{sub 3}(Ti,Al)-type ordered {gamma}' phase in the commercial nickel-based superalloy Inconel X-750 was investigated using Coincidence Doppler Broadening (CDB) technique. The results obtained are discussed in terms of positron annihilation in two well-defined states: one corresponding to the matrix ({gamma} phase) and a second related to the {gamma}' precipitates. Between these two aging stages, CDB distributions corresponding to selected intermediate aging treatments could be presented exactly, within the experimental scatter, as a linear combination of the {gamma} and {gamma}' signatures. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  4. Interaction of runaway electrons with lower hybrid waves via anomalous Doppler broadening

    Science.gov (United States)

    Martín-Solís, J. R.; Sánchez, R.; Esposito, B.

    2002-05-01

    Due to the relativistic decrease of the electron cyclotron frequency, a cyclotron resonance may appear between runaway electrons and lower hybrid waves. A single particle description of the runaway dynamics [J. R. Martín-Solís et al., Phys. Plasmas 5, 2370 (1998)] is extended to analyze the effect of the interaction of runaway electrons with lower hybrid waves via anomalous Doppler broadening. The conditions under which the resonant interaction can play a role in limiting the runaway energy are established and it is shown that, under typical lower hybrid current drive operation parameters, an efficient wave-particle coupling may occur. Observations of a fast pitch angle scattering event during the current decay phase of Ohmic discharges in the Toroidal Experiment for Technically Oriented Research (TEXTOR) [R. J. E. Jaspers, Ph.D. thesis, Technical University Eindhoven (1995)] are interpreted in terms of such interaction.

  5. Predictable progressive Doppler deterioration in IUGR: does it really exist?

    LENUS (Irish Health Repository)

    Unterscheider, Julia

    2013-12-01

    An objective of the Prospective Observational Trial to Optimize Pediatric Health in IUGR (PORTO) study was to evaluate multivessel Doppler changes in a large cohort of intrauterine growth restriction (IUGR) fetuses to establish whether a predictable progressive sequence of Doppler deterioration exists and to correlate these Doppler findings with respective perinatal outcomes.

  6. Musculoskeletal colour/power Doppler in sports medicine: image parameters, artefacts, image interpretation and therapy

    DEFF Research Database (Denmark)

    Boesen, M I; Boesen, Mikael; Kønig, Merete Juhl

    2011-01-01

    guidelines and recommendations are based on personal experience since no evidence in literature exists. The basic technical background of Doppler ultrasound and typical artefacts will be discussed, in order to understand and interpret the Doppler result. Recommendations for the Doppler settings are given...

  7. High-resolution kinetic energy distributions via doppler shift measurements

    Science.gov (United States)

    Xu, Z.; Koplitz, B.; Buelow, S.; Baugh, D.; Wittig, C.

    1986-07-01

    In photolysis/probe experiments using pulsed sources, time delay produces both spatial and directional bias in the fragment distributions, thus enabling well-resolved kinetic energy distributions to be obtained from Doppler shift measurements. Data are presented for H-atoms detected using two-photon ionization, and high S/N and laser-limited kinetic energy resolution are demonstrated.

  8. Radar Micro-Doppler classification of Mini-UAVs

    NARCIS (Netherlands)

    Harmanny, R.L.A.; Prémel-Cabic, G.; Wit, J.J.M.

    2015-01-01

    The radar micro-Doppler signature of a target depends on its micro-motion, i.e., the motion of parts of a target relative to the motion of the target as a whole. These micro-motions are very characteristic considering different target classes, e.g., the slow pendulum-like motion of a bird’s wings ve

  9. Color M-mode and pulsed wave tissue Doppler echocardiography

    DEFF Research Database (Denmark)

    Møller, J E; Søndergaard, E; Poulsen, S H;

    2001-01-01

    To assess the association between color M-mode flow propagation velocity and the early diastolic mitral annular velocity (E(m)) obtained with tissue Doppler echocardiography and to assess the prognostic implications of the indexes, echocardiography was performed on days 1 and 5, and 1 and 3 months...

  10. Ultrasonography and color Doppler in juvenile idiopathic arthritis

    DEFF Research Database (Denmark)

    Laurell, Louise; Court-Payen, Michel; Nielsen, Susan;

    2012-01-01

    The wrist region is one of the most complex joints of the human body. It is prone to deformity and functional impairment in juvenile idiopathic arthritis (JIA), and is difficult to examine clinically. The aim of this study was to evaluate the role of ultrasonography (US) with Doppler in diagnosis...

  11. Ultrasonography and color Doppler in juvenile idiopathic arthritis

    DEFF Research Database (Denmark)

    Laurell, Louise; Court-Payen, Michel; Nielsen, Susan;

    2011-01-01

    hypertrophy, effusion) and by color Doppler (synovial hyperemia) before and 4 weeks after US-guided steroid injection. Results US detected 121 compartments with active disease (joints, tendon sheaths and 1 ganglion cyst). Multiple compartments were involved in 80% of the ankle regions. The talo-crural joint...

  12. A compact differential laser Doppler velocimeter using a semiconductor laser

    NARCIS (Netherlands)

    Jentink, H.W.; Beurden, van J.A.J.; Helsdingen, M.A.; Mul, de F.F.M.; Suichies, H.E.; Aarnoudse, J.G.; Greve, J.

    1987-01-01

    A small differential laser Doppler velocimeter which uses a semiconductor laser and a small number of optical components is described. In this device the light from the laser diode is split into coherent beams by means of a diffraction grating. The two first-order beams are crossed in a probe volume

  13. A range-rate extraction unit for determining Doppler effect

    Science.gov (United States)

    1970-01-01

    Active ranging technique devised for VHF or S-band radar systems divides target Doppler frequency by counter-generated number that is proportional to transmitting frequency, thus producing target velocity data in terms of speed and distance relative to target transponder.

  14. How to Study the Doppler Effect with Audacity Software

    Science.gov (United States)

    Dias, Marco Adriano; Carvalho, Paulo Simeão; Ventura, Daniel Rodrigues

    2016-01-01

    The Doppler effect is one of the recurring themes in college and high school classes. In order to contextualize the topic and engage the students in their own learning process, we propose a simple and easily accessible activity, i.e. the analysis of the videos available on the internet by the students. The sound of the engine of the vehicle…

  15. Unidirectional Rotation of Molecules Measured by the Rotational Doppler Effect

    Directory of Open Access Journals (Sweden)

    Prior Yehiam

    2013-03-01

    Full Text Available A pair of linearly polarized pump pulses induce field-free unidirectional molecular rotation, which is detected by a delayed circularly polarized probe. The polarization and spectrum of the probe are modified by the interaction with the molecules, in accordance with the Rotational Doppler Effect.

  16. Determining the Speed of Sound Using the Doppler Effect.

    Science.gov (United States)

    Gagne, Richard.

    1996-01-01

    Presents a simple but effective experiment that uses ultrasonic transducers and some basic electronics to study the speed of sound using the Doppler effect. Eliminates the noise problems associated with most sound experiments. Discusses the theory, and describes the apparatus and procedure. (JRH)

  17. Applications of doppler effect in navigation and oceanography

    Digital Repository Service at National Institute of Oceanography (India)

    Joseph, A.

    , the satellites transmit their orbital parameters and constant-frequency carriers so that a shipboard Doppler receiver and a computer can obtain an accurate position fix of the ship at the time of a satellite pass above the ship's horizon. Another domain where...

  18. UTEROPLACENTAL DOPPLER VELOCIMETRY DURING BRAXTON-HICKS CONTRACTIONS

    NARCIS (Netherlands)

    DIJKSTRA, K; AARNOUDSE, JG; Oosterhof, H.

    1992-01-01

    Pulsed-wave Doppler ultrasound was used to evaluate the influence of Braxton Hicks' contractions on flow velocity waveforms in the uterine arteries. Flow velocity waveforms were obtained from a standardized site, at the crossing of the uterine artery with the external iliac artery near the uterine w

  19. Doppler velocimetry with emphasis on the fetal cerebral circulation

    NARCIS (Netherlands)

    M.J. Noordam (Marja)

    1996-01-01

    textabstractIn this thesis the following questions were addressed: 1. Are changes in placental vascular resistance associated with alterations in arterial down stream impedance at fetal level? To this purpose placental embolization was carried-out in the fetal lamb with subsequent Doppler velocimetr

  20. Complex Doppler effect in left-handed metamaterials

    CERN Document Server

    Ziemkiewicz, David

    2014-01-01

    The Doppler shift is investigated in one-dimensional system with moving source. Theoretical findings are confirmed in numerical simulations of optical and acoustical waves propagation in simple metamaterial model, showing the reversed shift and the existence of multiple frequency modes. The properties of these waves are discussed. The effect of absorption on the phenomenon is outlined.

  1. Usefulness of Doppler Parameter in Patients with Renal Transplantation

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Yeo Chang; Shin, Byung Seok; Ohm, Joon Young; Ahn, Moon Sang [Chungnam National University Hospital, Daejeon (Korea, Republic of); Park, Mi Hyun [Dept. of Radiology, Dankook University Hospital, Cheonan (Korea, Republic of); Kim, Ho Jun [Dept. of Radiology, Konyang University Hospital, Daejeon (Korea, Republic of)

    2012-08-15

    The purpose of this study is to assess the usefulness of Doppler parameters in transplanted kidney function. Doppler parameters, including resistive index (RI), pulsatility index (PI), peak systolic velocity (PSV), and end diastolic velocity (EDV) were measured in the interlobar artery of 55 transplant recipients. Patients were grouped according to glomerular filtration rate (GFR): Group A (GFR < 30 ml / min / 1.73 m2, n = 27) and group B (GFR {>=}30 ml / min / 1.73 m2, n = 28). Doppler parameters were compared between groups and correlated with the GFR. GFR (40.1 {+-} 26.9) showed a significant negative correlation with RI (0.69{+-}.08) (p = .002, r = -.414). RI (0.72 vs. 0.67), PI (1.42 vs. 1.23), and EDV (10.5 vs. 15.3) differed significantly between groups (p < .05), however, PSV was not (36.9 vs. 47.1). Patients in group A (n = 11) with a lower RI than the mean had significantly lower PSV (31.7 vs. 45.1; p = .027) and EDV (11.1 vs. 16.7; p .017), compared with such patients in group B (n = 21). Doppler parameters are useful for evaluation of function of transplanted kidney. Even if the RI is normal, PSV and EDV may be used as hemodynamic indicators.

  2. Tethered acoustic doppler current profiler platforms for measuring streamflow

    Science.gov (United States)

    Rehmel, Michael S.; Stewart, James A.; Morlock, Scott E.

    2003-01-01

    The U.S. Geological Survey tested and refined tethered-platform designs for measuring streamflow. Platform specifications were developed, radio-modem telemetry of acoustic Doppler current profiler (ADCP) data and potential platform-hull sources were investigated, and hulls were tested and evaluated.

  3. Doppler Lidar in the Wind Forecast Improvement Projects

    Directory of Open Access Journals (Sweden)

    Pichugina Yelena

    2016-01-01

    Full Text Available This paper will provide an overview of some projects in support of Wind Energy development involving Doppler lidar measurement of wind flow profiles. The high temporal and vertical resolution of these profiles allows the uncertainty of Numerical Weather Prediction models to be evaluated in forecasting dynamic processes and wind flow phenomena in the layer of rotor-blade operation.

  4. Doppler Lidar in the Wind Forecast Improvement Projects

    Science.gov (United States)

    Pichugina, Yelena; Banta, Robert; Brewer, Alan; Choukulkar, Aditya; Marquis, Melinda; Olson, Joe; Hardesty, Mike

    2016-06-01

    This paper will provide an overview of some projects in support of Wind Energy development involving Doppler lidar measurement of wind flow profiles. The high temporal and vertical resolution of these profiles allows the uncertainty of Numerical Weather Prediction models to be evaluated in forecasting dynamic processes and wind flow phenomena in the layer of rotor-blade operation.

  5. Anomaly Detection In Additively Manufactured Parts Using Laser Doppler Vibrometery

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez, Carlos A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2015-09-29

    Additively manufactured parts are susceptible to non-uniform structure caused by the unique manufacturing process. This can lead to structural weakness or catastrophic failure. Using laser Doppler vibrometry and frequency response analysis, non-contact detection of anomalies in additively manufactured parts may be possible. Preliminary tests show promise for small scale detection, but more future work is necessary.

  6. Coronary Flow Velocity Reserve Assessed by Transthoracic Doppler

    DEFF Research Database (Denmark)

    Michelsen, Marie M; Pena, Adam; Mygind, Naja D;

    2016-01-01

    of the left anterior descending coronary artery in two-dimensional color Doppler mode, and (4) gradual, consistent increases of characteristic, well-defined flow velocity curves in pulsed-wave mode. RESULTS: The mean age (SD) was 62.1 ± 9.7 years. On the basis of the evaluations, patients were divided...

  7. Airborne Wind Profiling Algorithm for Doppler Wind LIDAR

    Science.gov (United States)

    Beyon, Jeffrey Y. (Inventor); Koch, Grady J. (Inventor); Kavaya, Michael J. (Inventor)

    2015-01-01

    Systems, methods, and devices of the present invention enable airborne Doppler Wind LIDAR system measurements and INS/GPS measurements to be combined to estimate wind parameters and compensate for instrument misalignment. In a further embodiment, the wind speed and wind direction may be computed based on two orthogonal line-of-sight LIDAR returns.

  8. Excitonic Doppler-Rabi Oscillations in a Moving Organic Slab

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    It is theoretically shown that excitonic Doppler-Rabi oscillations can occur in an organic slab moving along the axis of a high-Q cavity. Due to the √N enhancement of the vacuum Rabi frequency, this effect can be more easily observed than that in a moving two-level atom.

  9. Transcranial Doppler for detection of cerebral ischaemia during carotid endarterectomy

    DEFF Research Database (Denmark)

    Jørgensen, L G; Schroeder, T V

    1992-01-01

    We evaluated transcranial Doppler sonography (TCD) for the detection of cerebral ischaemia during carotid endarterectomy in 30 male and 14 female patients with ipsilateral focal cerebro-vascular symptoms. Surgery was performed during halothane-nitrous oxide anaesthesia with moderate hypocapnia...

  10. A Reference Optical System of Laser Doppler Longitudinal Displacement Measurement

    Institute of Scientific and Technical Information of China (English)

    张存满; 赵洋; 李达成

    2001-01-01

    In this paper, a new reference optical system is put forward to achieve longitudinal displacement measurement. An optical grating is used for frequency mixing and getting high SNR signals in the measurement. Conditions and methods for getting Doppler beat signals are presented.The experiments indicate that this optical syetem can be used to measure the longitudinal displacement with high accuracy.

  11. Venstre ventrikels diastoliske funktion vurderet med transtorakal Doppler-ekkokardiografi

    DEFF Research Database (Denmark)

    Poulsen, S H; Jensen, S E; Gøtzsche, O;

    1996-01-01

    Left ventricular diastolic dysfunction is currently recognized in patients with different heart diseases. Three abnormal filling patterns of the left ventricle detected by pulsed-Doppler echocardiography are observed in patients with heart disease. Each filling pattern is characterised by differe...

  12. A simplified study of trans-mitral Doppler patterns

    Directory of Open Access Journals (Sweden)

    Thomas George

    2008-11-01

    Full Text Available Abstract Background Trans-mitral Doppler produces complex patterns with a great deal of variability. There are several confusing numerical measures and indices to study these patterns. However trans-mitral Doppler produces readymade data visualization by pattern generation which could be interpreted by pattern analysis. By following a systematic approach we could create an order and use this tool to study cardiac function. Presentation of the hypothesis In this new approach we eliminate the variables and apply pattern recognition as the main criterion of study. Proper terminologies are also devised to avoid confusion. In this way we can get some meaningful information. Testing the hypothesis Trans-mitral Doppler should be seen as patterns rather than the amplitude. The hypothesis can be proven by logical deduction, extrapolation and elimination of variables. Trans-mitral flow is also analyzed vis-à-vis the Starling's Law applied to the left atrium. Implications of the hypothesis Trans-mitral Doppler patterns are not just useful for evaluating diastolic function. They are also useful to evaluate systolic function. By following this schema we could get useful diagnostic information and therapeutic options using simple pattern recognition with minimal measurements. This simplified but practical approach will be useful in day to day clinical practice and help in understanding cardiac function better. This will also standardize research and improve communication.

  13. ATTITUDE RATE ESTIMATION BY GPS DOPPLER SIGNAL PROCESSING

    Institute of Scientific and Technical Information of China (English)

    He Side; Milos Doroslovacki; Guo Zhenyu; Zhang Yufeng

    2003-01-01

    A method is presented for near-Earth spacecraft or aviation vehicle's attitude rate estimation by using relative Doppler frequency shift of the Global Positioning System (GPS)carrier. It comprises two GPS receiving antennas, a signal processing circuit and an algorithm.The whole system is relatively simple, the cost and wcight, as well as power consumption, are very low.

  14. New Type of 2-D Laser Doppler Vibrometer

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The fundamentals and method of 2-D laser Doppler vibrometer are introduced.The factors influencing the measuring accuracy are analyzed. Moreover, the circuit for signal processing is designed. The vibrating amplitude and frequency of 2-D vibration in wider range can be measured simultaneously in non-contact means,the measuring results are accurate.

  15. Color Doppler in the Assessment of Uteroplacental Circulation Insufficiency

    Directory of Open Access Journals (Sweden)

    Ahmad Soltani Shirazi

    2010-05-01

    Full Text Available Usage of color Doppler ultrasound in the diagnosis of uteroplacental or fetal-placental vascular insufficiency is based on the theory that many of these insufficiencies are due to small vessel disease in the uteroplacental or fetal-placental vasculature which ultimately results in fetal intrauterine growth retardation, increase in prenatal mortality and morbidity and fetal neurological development. "nIn a prospective study on patients who were sus-pected for developing uteroplacental insufficiency, color Doppler ultrasound was done and the results were compared with neonatal weight (one of the most important criteria for IUGR determination which was measured just after delivery."nDirect significant relation was showed to be present between prepartum vascular changes detected in Doppler ultrasound and prognosis of IUGR. "nThree vessel types were assessed in this study:"n1. Umbilical-middle cerebral arteries"n2. Uterine arteries"n3.Venous system (umbilical, ductus venosus, IVC, which is used to assess the compensation process in fetal circulation."nThree Doppler indices of vascular resistance were studied and their abnormalities according to the age of pregnancy were assessed.

  16. High-Energy 2-Micrometers Doppler Lidar for Wind Measurements

    Science.gov (United States)

    Koch, Grady J.; Beyon, Jeffrey Y.; Barnes, Bruce W.; Petros, Mulugeta; Yu, Jirong; Amzajerdian, Farzin; Kavaya, Michael J.; Singh, Upendra N.

    2006-01-01

    High-energy 2-micrometer wavelength lasers have been incorporated in a prototype coherent Doppler lidar to test component technologies and explore applications for remote sensing of the atmosphere. Design of the lidar is presented including aspects in the laser transmitter, receiver, photodetector, and signal processing. Calibration tests and sample atmospheric data are presented on wind and aerosol profiling.

  17. Validar: a testbed for advanced 2-micron Doppler lidar

    Science.gov (United States)

    Koch, Grady J.; Petros, Mulugeta; Barnes, Bruce W.; Beyon, Jeffrey Y.; Amzajerdian, Farzin; Yu, Jirong; Kavaya, Michael J.; Singh, Upendra N.

    2004-09-01

    High-energy 2-micron lasers have been incorporated in a breadboard coherent Doppler lidar to test component technologies and explore applications for remote sensing of the atmosphere. Design of the lidar is presented including aspects in the laser transmitter, receiver, photodetector, and signal processing. Sample data is presented on wind profiling and CO2 concentration measurements.

  18. Path-length-resolved optical Doppler perfusion monitoring

    NARCIS (Netherlands)

    Varghese, Babu; Rajan, Vinayakrishnan; Leeuwen, van Ton G.; Steenbergen, Wiendelt

    2007-01-01

    We report the first path-length-resolved perfusion measurements on human skin measured with a phase-modulated low-coherence Mach-Zehnder interferometer with spatially separated fibers for illumination and detection. Optical path lengths of Doppler shifted and unshifted light and path-length-dependen

  19. Doppler Spectrum from Moving Scatterers in a Random Environment

    DEFF Research Database (Denmark)

    Andersen, Jørgen Bach; Nielsen, Jesper Ødum; Pedersen, Gert Frølund;

    2009-01-01

    with moving traffic or indoor situations with moving people. Here we study the latter situation in detail with experimental results from a large office environment. A general theory of Doppler spectra is developed. The impact of a scatterer depends on the angular distribution of scattered energy, and uniform...

  20. Color Doppler Ultrasonography in Evaluation of the Postoperative Penis

    Directory of Open Access Journals (Sweden)

    M. Ghafouri

    2005-08-01

    Full Text Available Introduction & Background: Color Doppler ultrasonography (US is the imaging modality of choice in patients with penile diseases. Ultrasonography has a well-established role in evaluating erectile dysfunction as well as penile trauma, scarring, deformity, and tumors. The normal postoperative anatomy and the pathologic changes that can occur in cases of surgical complications can be successfully investigated with US. Gray Scale (B Mode and Color Doppler US clearly depicts the normal penile anatomy and postoperative changes. It is also effective in evaluating surgery-related complications and determining the causes of erectile dysfunction and other un-satisfactory long¬term results. Color Doppler US is the imaging modality of choice in evaluating patients who have undergone penile surgery. Here we aim to illustrate the gray-scale and color Doppler US appearance of normal penis, discuss the main penile surgical procedures, recognize the typical US features of the postopera-tive penis, and describe the US appearance of various postoperative complications. Patients & Methods: This article is the result of evaluating 42 patients referred to the radiology ward of Hashemi-Nejad Hospital, Iran University of Medical Sciences in the years 2002 to 2005 for ultrasonography of penis to assess the penis after different penile surgical procedures (urethral surgery, correction of penile mal-formations, prosthesis implantation, vascular surgery for impotence, surgical management of priapism, phallic reconstruction. The US apparatus was Esaote Technos MP, with linear multifrequency 5-8.5MHz. transducer. Results: A variety of early and late surgical complications could be identified, such as extraalbugineal patho-logic fluid collections and fibrosis. Moreover, Doppler US of the penile vessels and vascular anastomoses fol-lowing revascularization allowed direct evaluation of flow characteristics, shunt patency, and venous en-gorgement. Color Doppler US was also

  1. Role of Doppler Velocimetry in growth restricted fetuses

    Directory of Open Access Journals (Sweden)

    Dr. Khushali Gandhi

    2015-01-01

    Full Text Available Background Intra Uterine Growth Restriction (IUGR is an important and particularly challenging problem for obstetricians and pediatricians. IUGR is a leading contributor in perinatal morbidity and mortality affecting 23.8% newborns around the world and 75% are born in Asia alone. In India the incidence of low birth weight varies from 15 to 25% and more than 50% of them are IUGR. Methods The present article consists of a study of 100 cases of intrauterine growth restriction with periodic color Doppler during the period of 1st July 2011 to 30 th August, 2013 in Obstetrics and Gynecology Department of a tertiary care center. Detail history taken. General and obstetrical examination was done along with routine hematological and urine investigations. Ultrasound examination was done for growth, liquor and placental localization. Fetal well- being was assessed with Doppler studies and daily fetal movement count. Results In present study moderate to severe pregnancy induced hypertension (53.9% and lack of proper weight gain (23% are found to be the commonest causes of IUGR. Out of 69 IUGR cases having abnormal Doppler, about 63.8% had abnormality in uterine artery flow, 85.5% had abnormality in umbilical artery flow, 88.4% had abnormality in middle cerebral artery flow, 55% had abnormality in uterine and umbilical artery and 75.4% had abnormality in umbilical artery and MCA. Incidence of fetal demise (13% was higher in patients with abnormal Doppler flow compared to normal flow (3.2%. Surgical intervention in form of caesarean was required in 69.6% of patients with abnormal Doppler flow. Cerebro-placental ratio (CPR 1 where fetal demise is 2.6%. Incidence of AEDF/REDF ( Absent End Diastolic flow/Reversed End diastolic flow in IUGR was 8% that resulted in 50% loss of fetus. Conclusions Color Doppler is a useful mode to predict fetal outcome in IUGR. Color Doppler allows better understandings of hemodynamic changes in feto- placental and utero

  2. Hydronephrosis and pregnancy: study with Doppler echography. Hidronefrosis y embarazo: estudio mediante ecografia Doppler

    Energy Technology Data Exchange (ETDEWEB)

    Ripolles Gonzalez, T.R.; Ambit Capdevilla, S.; Sanguesa Nebot, C.; Lazaro, S. de; Garcia Vila, J.H.; Belloch Ugarte, V.

    1993-01-01

    An 18-month study was performed to establish the normal intrarenal resistance index during pregnancy, in order to determine whether it differed significantly depending on the week of gestation or the degree of hydronephrosis. For this purpose , the flow velocity waves obtained in right kidney were analyzed in a group of 112 patients on the basis of 209 explorations. The kidneys were classified as grade 0,I,II, or III according to the degree of hydronephrosis. Doppler signal sampling was carried out at the level of the corticomedullary junction. From the results of the study it can be deduced that the index of intrarenal resistance during pregnancy is similar to that of the general population, that there are no significant differences among the groups with different degree of hydronephrosis and that the index does not vary according to the different weeks of gestation. These findings suggest that, during pregnancy, a pathological resistance index in a kidney should not be attributed to the physiological changes associated with normal gestation. (Author) 21 refs.

  3. Tissue Doppler Findings in Patients with Pulmonary Arterial Hypertension

    Directory of Open Access Journals (Sweden)

    Firoozeh Abtahi

    2016-09-01

    Full Text Available In conclusion, our results suggested that increasing degrees of pulmonary artery systolic pressure affected timing of some tissue Doppler-derived intervals within the cardiac cycle, including IVC time, time to peak systolic myocardial velocity (Sm, and time to peak strain. Therefore, tissue Doppler imaging could be used in assessment of patients with suspected pulmonary arterial hypertension. Background: Pulmonary hypertension is an untreatable condition with poor prognosis and factors such as more elevated pulmonary arterial systolic pressure and right ventricular dysfunction are associated with a worse outcome. Objectives: Considering the limitations of the current modalities, this study aimed to find the relationship between tissue Doppler-derived systolic and diastolic parameters and elevated pulmonary arterial pressure in order to assess the routine application of tissue Doppler imaging in evaluation of pulmonary arterial hypertension. Patients and Methods: This study was conducted on 100 inpatient and outpatient individuals referred to the Department of Echocardiography in Shahid Faghihi hospital, Shiraz, Iran from July 2012 to March 2013. The individuals who had preserved right ventricular function in the presence of pulmonary arterial hypertension were included in the case group. On the other hand, the patients who did not have echocardiographic signs of pulmonary arterial hypertension were enrolled into the control group. All the patients underwent a complete transthoracic echocardiogram including 2-dimensional, color flow, and spectral Doppler as well as tissue Doppler imaging using a vivid E9 system, and the desired systolic and diastolic parameters were recorded. The relationship among these parameters was evaluated by independent sample t-test using the SPSS statistical software, version 16. Besides, P < 0.05 was considered to be statistically significant. Results: The mean time to peak strain was significantly longer in the case

  4. Ecocardiografia por Doppler tecidual no diagnóstico de rejeição após transplante cardíaco Ecocardiografía con Doppler tisular en el diagnóstico de rechazo después de transplante cardíaco Tissue doppler echocardiography in the diagnosis of heart transplantation rejection

    Directory of Open Access Journals (Sweden)

    Marcos Valério Coimbra Resende

    2011-07-01

    Full Text Available FUNDAMENTO: A biópsia endomiocárdica (BEM é o método padrão-ouro para o diagnóstico de rejeição celular (RC após transplante cardíaco (TC. OBJETIVO: Testar a hipótese de que o exame de imagem por Doppler tecidual (IDT pode detectar RC > 3A e agregar informação diagnóstica, comparado ao Doppler convencional. MÉTODOS: Cinquenta e quatro pacientes com TC foram submetidos à BEM e estudo ecocardiográfico através de IDT em até 24 horas. Comparamos os pacientes com TC e RC > 3A com pacientes com TC e RC 3A em 39/129 (30,2% das BEM. O melhor preditor isolado para o diagnóstico de RC foi a a'LAT, com sensibilidade de 76,3%, especificidade de 73,8% (p = 0,001. Na análise multivariada, a a'LAT (p = 0,001, a'SEP (p = 0,002, relação e'/a' LAT (p = 0,006, relação e'Mitral/ e'LAT (p = 0,014, SINF (p = 0,009 foram preditores de RC > 3A. Obtivemos um escore com sensibilidade de 88,2%, acurácia de 79,6%, e valor preditivo negativo de 92,9% para diagnosticar RC > 3A. O Doppler convencional (fluxo mitral e pulmonar venoso não foi relevante para predizer a RC > 3A. CONCLUSÃO: O estudo de IDT agregou informação diagnóstica para predizer RC > 3A quando comparado ao Doppler convencional. O modelo baseado em IDT pode ser tornar um método em potencial para detectar RC > 3A após TC.FUNDAMENTO: La biopsia endomiocárdica (BEM es el método gold standard para el diagnóstico de rechazo celular (RC después de transplante cardíaco (TC. OBJETIVO: Testear la hipótesis de que el examen de imagen con Doppler tisular (IDT puede detectar RC > 3A y agregar información diagnóstica, comparado al Doppler convencional. MÉTODOS: Cincuenta y cuatro pacientes con TC fueron sometidos a BEM y estudio ecocardiográfico a través de IDT en hasta 24 horas. Comparamos los pacientes con TC y RC > 3A con pacientes con TC y RC 3A en 39/129 (30,2% de las BEM. El mejor predictor aislado para el diagnóstico de RC fue la a'LAT, con sensibilidad de 76

  5. Laser Doppler anemometer studies in unsteady ventricular flows.

    Science.gov (United States)

    Phillips, W M; Furkay, S S; Pierce, W S

    1979-01-01

    The laser Doppler technique was employed to obtain intraventricular velocity distributions on the basis of in vivo confirmation of previous in vitro flow visualization predictions. The quasi-steady assumption required for quantification of flow visualization results is unsatisfactory in regions of high acceleration and fluctuating velocities are unavailable via such techniques. Mean and fluctuating velocity profiles were obtained in a pneumatically driven prosthetic ventricle with the laser Doppler anemometer and stress levels estimated. The preliminary data presented here illustrates that the technique can be applied to such flows. The measurement and data reduction schemes are applicable to a wide range of simulated cardiovascular flows. The particular application to prosthetic ventricle design should minimize the number of in vivo experiments required to develop a satisfactory blood pump and aid in tailoring pump actuation protocols for minimum thromboembolic complications.

  6. All semiconductor laser Doppler anemometer at 1.55 microm.

    Science.gov (United States)

    Hansen, René Skov; Pedersen, Christian

    2008-10-27

    We report to our best knowledge the first all semiconductor Laser Doppler Anemometer (LIDAR) for wind speed determination. We will present the design and first experimental results on a focusing coherent cw laser Doppler anemometer for measuring atmospheric wind velocities in the 10 meters to 300 meters distance range. Especially, we will demonstrate that both the output power as well as the demanding coherence properties required from the laser source can be accomplished by an all semiconductor laser. Preliminary tests at a distance of 40 meters indicate a typical signal to noise ratio of 9 dB. This result is obtained at a clear day with an up-date rate of 12 Hz.

  7. Assessment of right ventricular systolic function by tissue Doppler echocardiography

    DEFF Research Database (Denmark)

    Kjærgaard, Jesper

    2012-01-01

    myocardial velocities, but no changes in SR, strain or isovolumic acceleration could be observed [II and III]. Tissue Doppler echocardiography of the RV free wall in non-massive pulmonary embolism quantifies degree of RV dysfunction, and supports the existence of the McConnell sign of mid-ventricular RV...... structure including significant dilatation, but is well tolerated with only mild reduction in measures of global RV systolic function as estimated by 2D echocardiography in an experimental animal model. Regional RV myocardial function is also only mildly reduced. Also no differences in global or regional RV......This thesis summarizes a series of studies performed in order to assess the clinical usefulness of a novel echocardiographic technology that allows non-invasive assessment of regional right ventricular myocardial velocities and deformation: tissue Doppler echocardiography. While the technology...

  8. Study on cerebral microcirculation by Optical Doppler Tomography

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Optical Doppler Tomography (ODT) provides a novel method to measure the blood flow velocity in vessels with the diameter at micrometer scale. Rats with cranial window are used as a model, and the changes in the blood flow velocity of cerebral arterioles in sensory cortex are measured in real time with an established ODT system, under electrical stimulation and drug administration. The results show significant differences in the blood flow velocity between experimental groups and control groups, demonstrating the feasibility of ODT in the cerebral microcircula- tion study. Compared with the conventional Doppler ultrasound, ODT provides much higher spatial resolution, and thus holds a promising future in the application of the cerebral microcirculation study, especially in the observation of the blood flow velocity in micrometer scale vessels.

  9. Dynamic Navigation Method with Multisubstations Based on Doppler Shift

    Directory of Open Access Journals (Sweden)

    Jianyang Zhao

    2015-01-01

    Full Text Available The mobile terminals must be compensated for the Doppler effect in their moving communication. This special characteristic of mobile communication can be developed in some new applications. This paper proposes methods to realize mobile navigation calculation via Doppler shifts. It gives the theory of relationship between the motion parameters, like directions and speed, and frequency shifts caused by multibase stations. The simulation illustrates how to compute the movement parameters of numerical calculation and what should be care for the problem near angle 90 degree. It also gives an application with Google map and dynamical locating position and direction on a mobile phone by public wireless network. Given the simulation analysis and navigation test, the results show that this method has a good effect.

  10. Aircraft Wake Vortex Measurement with Coherent Doppler Lidar

    Directory of Open Access Journals (Sweden)

    Wu Songhua

    2016-01-01

    Full Text Available Aircraft vortices are generated by the lift-producing surfaces of the aircraft. The variability of near-surface conditions can change the drop rate and cause the cell of the wake vortex to twist and contort unpredictably. The pulsed Coherent Doppler Lidar Detection and Ranging is an indispensable access to real aircraft vortices behavior which transmitting a laser beam and detecting the radiation backscattered by atmospheric aerosol particles. Experiments for Coherent Doppler Lidar measurement of aircraft wake vortices has been successfully carried out at the Beijing Capital International Airport (BCIA. In this paper, the authors discuss the Lidar system, the observation modes carried out in the measurements at BCIA and the characteristics of vortices.

  11. Laser Doppler velocimetry using a modified computer mouse

    Science.gov (United States)

    Zaron, Edward D.

    2016-10-01

    A computer mouse has been modified for use as a low-cost laser Doppler interferometer and used to measure the two-component fluid velocity of a flowing soap film. The mouse sensor contains two vertical cavity surface emitting lasers, photodiodes, and signal processing hardware integrated into a single package, approximately 1 cm2 in size, and interfaces to a host computer via a standard USB port. Using the principle of self-mixing interferometry, whereby laser light re-enters the laser cavity after being scattered from a moving target, the Doppler shift and velocity of scatterers dispersed in the flow are measured. Observations of the boundary layer in a turbulent soap film channel flow demonstrate the capabilities of the sensor.

  12. Doppler radar fall activity detection using the wavelet transform.

    Science.gov (United States)

    Su, Bo Yu; Ho, K C; Rantz, Marilyn J; Skubic, Marjorie

    2015-03-01

    We propose in this paper the use of Wavelet transform (WT) to detect human falls using a ceiling mounted Doppler range control radar. The radar senses any motions from falls as well as nonfalls due to the Doppler effect. The WT is very effective in distinguishing the falls from other activities, making it a promising technique for radar fall detection in nonobtrusive inhome elder care applications. The proposed radar fall detector consists of two stages. The prescreen stage uses the coefficients of wavelet decomposition at a given scale to identify the time locations in which fall activities may have occurred. The classification stage extracts the time-frequency content from the wavelet coefficients at many scales to form a feature vector for fall versus nonfall classification. The selection of different wavelet functions is examined to achieve better performance. Experimental results using the data from the laboratory and real inhome environments validate the promising and robust performance of the proposed detector.

  13. Normal Doppler velocimetry of renal vasculature in Persian cats.

    Science.gov (United States)

    Carvalho, Cibele F; Chammas, Maria C

    2011-06-01

    Renal diseases are common in older cats. Decreased renal blood flow may be the first sign of dysfunction and can be evaluated by Doppler ultrasound. But previous studies suggest that the resistive index (RI) has a low sensitivity for detecting renal disease. Doppler waveforms of renal and intrarenal arteries demonstrate decreased blood flow before there are any changes in the RI. The purpose of this study was to evaluate the normal Doppler flowmetrics parameters of renal arteries (RAs), interlobar arteries (IAs) and abdominal aorta (AO) in adult healthy, Persian cats. Twenty-five Persian cats (13 females and 12 males with mean age of 30 months and an age range 12-60 months) with normal clinical examinations and biochemical tests and normal systemic blood pressure were given B-mode ultrasonographies in order to exclude all nephropathies, including polycystic kidney disease. All measurements were performed on both kidneys. Both kidneys (n=50) were examined by color mapping of the renal vasculature. Pulsed Doppler was used to examine both RAs, the IAs at cranial, middle and caudal sites, and the AO. The RI was calculated for all of the vessels. Early systolic acceleration (ESA) of RA and IA was obtained with Doppler spectral analysis. Furthermore, the ratio indices between RA/AO, and IA/RA velocities were calculated. The mean values of peak systolic velocity (PSV) and the diameter for AO were 53.17±13.46 cm/s and 0.38±0.08 cm, respectively. The mean RA diameter for all 50 kidneys was 0.15±0.02 cm. Considering the velocimetric values in both RAs, the mean PSV and RI that were obtained were 41.17±9.40 cm/s and 0.54±0.07. The RA had a mean ESA of 1.12±1.14 m/s(2) and the calculated upper limit of the reference value was 3.40 m/s(2). The mean renal-aortic ratio was 0.828±0.296. The IA showed PSV and RI values of 32.16±9.33 cm/s and 0.52±0.06, respectively. The mean ESA of all IAs was 0.73±0.61 m/s(2). The calculated upper limit of the reference value was 2.0m

  14. Ballistic Missile Warhead Recognition based on Micro-Doppler Frequency

    Directory of Open Access Journals (Sweden)

    Sun Hui-Xia

    2008-11-01

    Full Text Available To elucidate the spinning-precession signatures of ballistic warhead, the model of spinning precessionfor ballistic missile warhead is established and the mathematics of micro-Doppler signatures caused by spinning-precession is derived. Then the micro-Doppler features are analysed using high-resolution time-frequencytransform, and the model predictions match the experimental data well. Based on  different mass of warheadsand decoys, the feature, which can reflect the mass of the targets, is extracted from the time-frequency plane,proving a new method for recognising warheads and discriminating these from decoys. Finally the validityof the feature extracted in this study is verified by computer simulations even with low signal-to-noise ratio.Defence Science Journal, 2008, 58(6, pp.705-709, DOI:http://dx.doi.org/10.14429/dsj.58.1697

  15. Method of target tracking with Doppler blind zone constraint

    Institute of Scientific and Technical Information of China (English)

    Wei Han; Ziyue Tang; Zhenbo Zhu

    2013-01-01

    Doppler blind zone (DBZ) has a bad influence on the airborne early warning radar, although it has good detection per-formance for low altitude targets with pulse Doppler (PD) techno-logy. In target tracking, the blind zone can cause target tracking breakage easily. In order to solve this problem, a paral el parti-cle filter (PF) algorithm based on multi-hypothesis motion models (MHMMs) is proposed. The algorithm produces multiple possible target motion models according to the DBZ constraint. Particles are updated with the constraint in each motion model. Once the first measurement from the target which reappears from DBZ fal s into the particle cloud formed by any model, the measurement-track association succeeds and track breakage is avoided. The simulation results show that on the condition of different DBZ ranges, a high association ratio can be got for targets with different maneuverability levels, which accordingly improves the tracking quality.

  16. Augmented Reality Based Doppler Lidar Data Visualization: Promises and Challenges

    Science.gov (United States)

    Cherukuru, N. W.; Calhoun, R.

    2016-06-01

    Augmented reality (AR) is a technology in which the enables the user to view virtual content as if it existed in real world. We are exploring the possibility of using this technology to view radial velocities or processed wind vectors from a Doppler wind lidar, thus giving the user an ability to see the wind in a literal sense. This approach could find possible applications in aviation safety, atmospheric data visualization as well as in weather education and public outreach. As a proof of concept, we used the lidar data from a recent field campaign and developed a smartphone application to view the lidar scan in augmented reality. In this paper, we give a brief methodology of this feasibility study, present the challenges and promises of using AR technology in conjunction with Doppler wind lidars.

  17. Cerebrovascular reactivity in migraineurs as measured by transcranial Doppler

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, T.D.; Harpold, G.J. (Alabama Univ., Birmingham, AL (USA). School of Medicine); Troost, B.T. (Bowman Gray School of Medicine, Winston-Salem, NC (USA))

    1990-04-01

    Transcranial Doppler ultrasound is a relatively new diagnostic modality which allows the non-invasive assessment of intracranial circulation. A total of 10 migraine patients were studied and compared to healthy controls without headaches. Migraineurs during the headache-free interval demonstrated excessive cerebrovascular reactivity to CO{sub 2}, evidenced by an increase in middle cerebral artery blood flow velocity of 47% {plus minus} 15% compared to 28% {plus minus} 14% in controls. Differences between the two study groups revealed no significant decrease in middle cerebral artery blood flow velocity with hypocapnia. However, the differences between middle cerebral artery blood flow velocity during hyperventilation and CO{sub 2} inhalation were significantly different comparing migraineurs and controls. Instability of the baseline blood flow velocities was also noted in migraineurs during the interictal period. Characteristics which may allow differentiation of migraineurs from other headache populations could possibly be obtained from transcranial Doppler ultrasound flow studies. 24 refs., 2 tabs.

  18. Doppler Lidar Vertical Velocity Statistics Value-Added Product

    Energy Technology Data Exchange (ETDEWEB)

    Newsom, R. K. [DOE ARM Climate Research Facility, Washington, DC (United States); Sivaraman, C. [DOE ARM Climate Research Facility, Washington, DC (United States); Shippert, T. R. [DOE ARM Climate Research Facility, Washington, DC (United States); Riihimaki, L. D. [DOE ARM Climate Research Facility, Washington, DC (United States)

    2015-07-01

    Accurate height-resolved measurements of higher-order statistical moments of vertical velocity fluctuations are crucial for improved understanding of turbulent mixing and diffusion, convective initiation, and cloud life cycles. The Atmospheric Radiation Measurement (ARM) Climate Research Facility operates coherent Doppler lidar systems at several sites around the globe. These instruments provide measurements of clear-air vertical velocity profiles in the lower troposphere with a nominal temporal resolution of 1 sec and height resolution of 30 m. The purpose of the Doppler lidar vertical velocity statistics (DLWSTATS) value-added product (VAP) is to produce height- and time-resolved estimates of vertical velocity variance, skewness, and kurtosis from these raw measurements. The VAP also produces estimates of cloud properties, including cloud-base height (CBH), cloud frequency, cloud-base vertical velocity, and cloud-base updraft fraction.

  19. Study on cerebral microcirculation by Optical Doppler Tomography

    Institute of Scientific and Technical Information of China (English)

    MENG Jie; DING ZhiHua; YANG Yong; GUO ZhouYi

    2008-01-01

    Optical Doppler Tomography (ODT) provides a novel method to measure the blood flow velocity in vessels with the diameter at micrometer scale.Rats with cranial window are used as a model,and the changes in the blood flow velocity of cerebral arterioles in sensory cortex are measured in real time with an established ODT system,under electrical stimulation and drug administration.The results show significant differences in the blood flow velocity between experimental groups and control groups,demonstrating the feasibility of ODT in the cerebral microcircula-tion study.Compared with the conventional Doppler ultrasound,ODT provides much higher spatial resolution,and thus holds a promising future in the application of the cerebral microcirculation study,especially in the observation of the blood flow velocity in micrometer scale vessels.

  20. Performance evaluation of a thermal Doppler Michelson interferometer system.

    Science.gov (United States)

    Mani, Reza; Dobbie, Steven; Scott, Alan; Shepherd, Gordon; Gault, William; Brown, Stephen

    2005-11-20

    The thermal Doppler Michelson interferometer is the primary element of a proposed limb-viewing satellite instrument called SWIFT (Stratospheric Wind Interferometer for Transport studies). SWIFT is intended to measure stratospheric wind velocities in the altitude range of 15-45 km. SWIFT also uses narrowband tandem etalon filters made of germanium to select a line out of the thermal spectrum. The instrument uses the same technique of phase-stepping interferometry employed by the Wind Imaging Interferometer onboard the Upper Atmosphere Research Satellite. A thermal emission line of ozone near 9 microm is used to detect the Doppler shift due to winds. A test bed was set up for this instrument that included the Michelson interferometer and the etalon filters. For the test bed work, we investigate the behavior of individual components and their combination and report the results.

  1. Altered doppler flow patterns in cirrhosis patients: An overview

    Energy Technology Data Exchange (ETDEWEB)

    Iranpour, Pooya; Lall, Chandana; Houshyar, Roozbeh; Helmy, Mohammad; Yang, Albert; Ward, Garrett; Goodwin, Scott C. [Dept. of Radiology, University of California Irvine, Orange (United States); Choi, Joon Il [Dept. of Radiology, Seoul St. Mary' s Hospital, College of Medicine, The Catholic University of Korea, Seoul (Korea, Republic of)

    2016-01-15

    Doppler ultrasonography of the hepatic vasculature is an integral part of evaluating precirrhotic and cirrhotic patients. While the reversal of the portal venous flow is a well-recognized phenomenon, other flow patterns, although not as easily understood, may play an important role in assessing the disease status. This article discusses the different characteristic flow patterns observed from the portal vein, hepatic artery, and hepatic vein in patients with liver cirrhosis or related complications and procedures. Knowledge of these different flow patterns provides additional information that may reinforce the diagnosis of cirrhosis, help in staging, and offer prognostic information for determining the direction of therapy. Doppler ultrasonography is invaluable when liver transplantation is being considered and aids in the diagnosis of cirrhosis and portal hypertension.

  2. Multipath-dominant, pulsed doppler analysis of rotating blades

    CERN Document Server

    Robinson, Michael

    2012-01-01

    We present a novel angular fingerprinting algorithm for detecting changes in the direction of rotation of a target with a monostatic, stationary sonar platform. Unlike other approaches, we assume that the target's centroid is stationary, and exploit doppler multipath signals to resolve the otherwise unavoidable ambiguities that arise. Since the algorithm is based on an underlying differential topological theory, it is highly robust to distortions in the collected data. We demonstrate performance of this algorithm experimentally, by exhibiting a pulsed doppler sonar collection system that runs on a smartphone. The performance of this system is sufficiently good to both detect changes in target rotation direction using angular fingerprints, and also to form high-resolution inverse synthetic aperature images of the target.

  3. High Frequency Color Doppler Image of Choroidal Detachment

    Institute of Scientific and Technical Information of China (English)

    Jinghong Wu; Lijuan Zou; Zhongyao Wu; Lixun Cheng

    2000-01-01

    Purpose: To study the Color Doppler Image (CDI) characteristics of choroidal detachment and the applied value of CDI.Methods: Seventy-two cases (74 eyes) of choroidal detachment were studied retrospectively.Results: The typical ultragraph of chroridal detachment displayed one or several smooth hemispherical or lobuler circular thick bands, with convex side toward vitreous cavity. Most of the choroidal detachments were located before the equator, a few of them were beyond the equator. CDI displayed blood flow singnal in the band. Pulse Doppler showed the frequency spectrum features of retinal detachment band were similar to those of central retinal vessels, whereas the frequency spectum features of choroidal detachment bend resembled those of ciliary artery in some cases of retinal detachment (RD) accompanied by choroidal detachment.Conclusion: CDI could make a correct and precise diagnosis of choroidal detachment.Eye Science 2000; 16. 61 ~ 64.

  4. Gravity theories, Transverse Doppler and Gravitational Redshifts in Galaxy Clusters

    CERN Document Server

    Zhao, Hongsheng; Li, Baojiu

    2012-01-01

    There is growing interest in testing alternative gravity theories using the subtle Gravitational Redshifts in clusters of galaxies. However, current models all neglect a Transverse Doppler redshift of similar magnitude, and some models are not self-consistent. An equilibrium model would fix the Gravitational and Transverse Doppler velocity shifts to be about 6\\sigma^2/c and 3\\sigma^2/2c in order to fit the observed velocity dispersion \\sigma self-consistently. This result is from the Virial Theorem for a spherical isotropic cluster, and is insensitive to the theory of gravity. In any case, a gravitational redshift signal cannot directly distinguish between the Einsteinian and f(R) gravity theories, because the mass of the cluster dark halo must be treated as an unknown fitting parameter, whose value must vary according to the theory adopted, otherwise the system would be in equilibrium in one gravity theory and out of equilibrium in another.

  5. Scanning laser Doppler vibrometry of the middle ear ossicles.

    Science.gov (United States)

    Ball, G R; Huber, A; Goode, R L

    1997-04-01

    This paper describes measurements of the vibratory modes of the middle ear ossicles made with a scanning laser Doppler vibrometer. Previous studies of the middle ear ossicles with single-point laser Doppler measurements have raised questions regarding the vibrational modes of the ossicular chain. Single-point analysis methods do not have the ability to measure multiple points on the ossicles and, consequently, have limited ability to simultaneously record relative phase information at these points. Using a Polytec Model PSV-100, detailed measurements of the ossicular chain have been completed in the human temporal bone model. This model, when driven with a middle ear transducer, provides detailed three-dimensional data of the vibrational patterns of the middle ear ossicles. Implications for middle ear implantable devices are discussed.

  6. Using Doppler Shifts of GPS Signals To Measure Angular Speed

    Science.gov (United States)

    Campbell, Charles E., Jr.

    2006-01-01

    A method has been proposed for extracting information on the rate of rotation of an aircraft, spacecraft, or other body from differential Doppler shifts of Global Positioning System (GPS) signals received by antennas mounted on the body. In principle, the method should be capable of yielding low-noise estimates of rates of rotation. The method could eliminate the need for gyroscopes to measure rates of rotation. The method is based on the fact that for a given signal of frequency ft transmitted by a given GPS satellite, the differential Doppler shift is attributable to the difference between those components of the instantaneous translational velocities of the antennas that lie along the line of sight from the antennas to the GPS satellite.

  7. Distribution of Doppler Redshifts of Associated Absorbers of SDSS Quasars

    Indian Academy of Sciences (India)

    Cai-Juan Pan; Zhi-Fu Chen

    2013-12-01

    Doppler redshifts of a sample of Mg II associated absorbers of SDSS DR7 quasars are analysed. We find that there might be three Gaussian components in the distribution of the Doppler redshift. The first Gaussian component, with the peak being located at Dopp = -0.0074, probably arises from absorbers with outflow histories observed in the direction close to jets of quasars. The second Gaussian component, with the peak being located at Dopp = -0.0017, possibly arises from absorbers with outflow histories observed in the direction far away from jets of quasars. Whereas, the third Gaussian component, with the peak being located at Dopp = -0.0004, might arise from the random motion of absorbers with respect to quasars.

  8. Curvature affects Doppler investigation of vessels: implications for clinical practice.

    Science.gov (United States)

    Balbis, S; Roatta, S; Guiot, C

    2005-01-01

    In clinical practice, blood velocity estimations from Doppler examination of curved vascular segments are normally different from those of nearby straight segments. The observed "accelerations," sometimes considered as a sort of stochastic disturbances, can actually be related to very specific physical effects due to vessel curvature (i.e., the development of nonaxial velocity [NAV] components) and the spreading of the axial velocity direction in the Doppler sample volume with respect to the insonation axis. The relevant phenomena and their dependence on the radius of curvature of the vessels and on the insonation angle are investigated with a beam-vessel geometry as close as possible to clinical setting, with the simplifying assumptions of steady flow, mild vessel curvature, uniform ultrasonic beam and complete vessel insonation. The insonation angles that minimize the errors are provided on the basis of the study results.

  9. [The value of Doppler ultrasound studies in threatened premature labor].

    Science.gov (United States)

    Jörn, H; Funk, A; Fendel, H

    1993-01-01

    95 patients were investigated using Doppler ultrasound to evaluate its usefulness during the clinical management of patients with preterm labor, preterm rupture of membranes and incompetent cervix. Cases with additional pregnancy complications as preeclampsia or intrauterine growth retardation or infection of the amnion or the birth canal were excluded from our study. We examined the umbilical artery and the uterine arteries. Predicting preterm birth we found a sensitivity of 31.4% and a specificity of 70% for the former and a sensitivity of 34.3% and a specificity of 83.3% for the latter. As a result of our investigation we have to conclude that Doppler ultrasound is not able to predict sufficiently reliable preterm birth to use it in clinical management. Normal uterine blood flow in cases with preterm labor seems to indicate birth at term in a high degree.

  10. An ideal blood mimicking fluid for doppler ultrasound phantoms.

    Science.gov (United States)

    Samavat, H; Evans, J A

    2006-10-01

    In order to investigate the problems of detecting tumours by ultrasound it is very important to have a portable Doppler flow test object to use as a standardising tool. The flow Doppler test objects are intended to mimic the flow in human arteries. To make the test meaningful, the acoustic properties of the main test object components (tissue and blood mimic) should match closely the properties of the corresponding human tissues, while the tube should ideally have little influence. The blood mimic should also represent the haemodynamic properties of blood. An acceptable flow test object has been designed to closely mimic blood flow in arteries. We have evaluated the properties of three blood mimicking fluid: two have been described recently in the literature, the third is a local design. One of these has emerged as being particularly well matched to the necessary characteristics for in-vitro work.

  11. An ideal blood mimicking fluid for doppler ultrasound phantoms

    Directory of Open Access Journals (Sweden)

    Samavat H

    2006-01-01

    Full Text Available In order to investigate the problems of detecting tumours by ultrasound it is very important to have a portable Doppler flow test object to use as a standardising tool. The flow Doppler test objects are intended to mimic the flow in human arteries. To make the test meaningful, the acoustic properties of the main test object components (tissue and blood mimic should match closely the properties of the corresponding human tissues, while the tube should ideally have little influence. The blood mimic should also represent the haemodynamic properties of blood. An acceptable flow test object has been designed to closely mimic blood flow in arteries. We have evaluated the properties of three blood mimicking fluid: two have been described recently in the literature, the third is a local design. One of these has emerged as being particularly well matched to the necessary characteristics for in-vitro work.

  12. Aircraft Wake Vortex Measurement with Coherent Doppler Lidar

    Science.gov (United States)

    Wu, Songhua; Liu, Bingyi; Liu, Jintao

    2016-06-01

    Aircraft vortices are generated by the lift-producing surfaces of the aircraft. The variability of near-surface conditions can change the drop rate and cause the cell of the wake vortex to twist and contort unpredictably. The pulsed Coherent Doppler Lidar Detection and Ranging is an indispensable access to real aircraft vortices behavior which transmitting a laser beam and detecting the radiation backscattered by atmospheric aerosol particles. Experiments for Coherent Doppler Lidar measurement of aircraft wake vortices has been successfully carried out at the Beijing Capital International Airport (BCIA). In this paper, the authors discuss the Lidar system, the observation modes carried out in the measurements at BCIA and the characteristics of vortices.

  13. The structure of Doppler peaks induced by active perturbations

    CERN Document Server

    Magueijo, J; Ferreira, P; Coulson, D; Magueijo, Joao; Albrecht, Andreas; Ferreira, Pedro; Coulson, David

    1996-01-01

    We investigate how the qualitative structure of Doppler peaks in the angular power spectrum of the cosmic microwave anisotropy is affected by basic assumptions going into theories of structure formation. We define the concepts of ``coherent'' and ``incoherent'' fluctuations, and also of ``active'' and ``passive'' fluctuations. In these terms inflationary fluctuations are passive and coherent while topological defects are active incoherent fluctuations. Causality and scale invariance are shown to have different implementations in theories differing in the above senses. We then extend the formalism of Hu and Sugiyama to treat models with cosmic defects. Using this formalism we show that the existence or absence of secondary Doppler peaks and the rough placing of the primary peak are very sensitive to the fundamental properties defined. We claim therefore that even a rough measurement of the angular power spectrum C_l shape at 100

  14. How to study the Doppler effect with Audacity software

    Science.gov (United States)

    Adriano Dias, Marco; Simeão Carvalho, Paulo; Rodrigues Ventura, Daniel

    2016-05-01

    The Doppler effect is one of the recurring themes in college and high school classes. In order to contextualize the topic and engage the students in their own learning process, we propose a simple and easily accessible activity, i.e. the analysis of the videos available on the internet by the students. The sound of the engine of the vehicle passing by the camera is recorded on the video; it is then analyzed with the free software Audacity by measuring the frequency of the sound during approach and recede of the vehicle from the observer. The speed of the vehicle is determined due to the application of Doppler effect equations for acoustic waves.

  15. Japanese sounding rocket experiment with the solar XUV Doppler telescope

    Science.gov (United States)

    Sakao, Taro; Tsuneta, Saku; Hara, Hirohisa; Kano, Ryouhei; Yoshida, Tsuyoshi; Nagata, Shin'ichi; Shimizu, Toshifumi; Kosugi, Takeo; Murakami, Katsuhiko; Wasa, Wakuna; Inoue, Masao; Miura, Katsuhiro; Taguchi, Koji; Tanimoto, Kazuo

    1996-11-01

    We present an overview of an ongoing Japanese sounding rocket project with the Solar XUV Doppler telescope. The telescope employs a pair of normal incidence multilayer mirrors and a back-thinned CCD, and is designed to observe coronal velocity field of the whole sun by measuring line- of-sight Doppler shifts of the Fe XIV 211 angstroms line. The velocity detection limit is estimated to be better than 100 km/s. The telescope will be launched by the Institute of Space and Astronautical Science in 1998, when the solar activity is going to be increasing towards the cycle 23 activity maximum. Together with the overview of the telescope, the current status of the development of each telescope components including multilayer mirrors, telescope structure, image stabilization mechanism, and focal plane assembly, are reviewed. The observation sequence during the flight is also briefly described.

  16. Three-dimensional Doppler anemometer using a holographic optical element.

    Science.gov (United States)

    Schneider, F; Windein, W

    1988-11-01

    A new simple 3-D laser Doppler system has been developed for simultaneous measurement of the instantaneous velocity vector of a scattering particle. The system is based on the reference beam method. It uses a hologram to generate the reference beams. Only one laser operating in single mode is required as the light source. The system has been tested by measuring all the components of the Reynolds stress tensor in a round cold air jet. The results are presented.

  17. Development of Photon Doppler Velocimeter for Explosives Research

    Science.gov (United States)

    2013-01-01

    to competing methods such as VISAR and Fabry- Perot interferometry . This report describes the development of a PDV and an application of it to the...He worked in Electronic Warfare and Radar Division at DSTO on the development of fibre lasers. Shayne is currently undertaking his PhD studies in...Heterodyne theory A concept schematic demonstrating in- principle operation of a Photon Doppler Velocimeter is shown in Figure 3. Source waveguide

  18. Phase-referenced Doppler optical coherence tomography in scattering media.

    Science.gov (United States)

    Pedersen, Cameron J; Yazdanfar, Siavash; Westphal, Volker; Rollins, Andrew M

    2005-08-15

    We present a fiber-based, low-coherence interferometer that significantly reduces phase noise by incorporating a second, narrowband, continuous-wave light source as a phase reference. By incorporating this interferometer into a Doppler OCT system, we demonstrate significant velocity noise reduction in reflective and scattering samples using processing techniques amenable to real-time implementation. We also demonstrate 90% suppression of velocity noise in a flow phantom.

  19. Michelson interferometer null may confirm transverse Doppler Effect

    CERN Document Server

    Woodruff, Robert A

    2014-01-01

    We analyze fringe formation within Michelson-like experiments as viewed by relativistic inertial observers. Our analysis differs from previous work because we include optical misalignment of the beamsplitter of the interferometer due to the anamorphic geometry of relativistic Lorentz contraction. We conclude that inertial frame equivalence of Michelson-like experiments provide verification of the transverse Doppler Effect and exclude any model incorporating the relativistic Lorentz contraction effect.

  20. Laser Doppler flowmetry in diagnoses of chronic tonsillitis

    Science.gov (United States)

    Mareew, Gleb O.; Mareew, Oleg V.; Maslyakova, Galina N.; Ivliev, Igor I.; Fedosov, Ivan V.; Lychagov, Vladislav V.; Tuchin, Valery V.

    2005-06-01

    Chronic tonsillitis is one of the most common diseases in ENT all over the world. There are two ways of treatment-surgical tonsillectomy and conservative therapeutically treatment. But still doctors have no possibility to make objective decisions for this painful and tonsil-destructive operation. In this article we try to research how the degree of sclerosis in tonsillar tissue affects the blood flow in tonsils, by using laser Doppler flowmetry.

  1. Comparative analysis of renal flow using contrast power Doppler and gray-scale ultrasound

    Science.gov (United States)

    Sehgal, Chandra M.; Arger, Peter H.; Bovee, Kenneth C.; Pugh, Charles; Kirchhofer, Justin I.

    1997-05-01

    Our previous studies have shown that renal perfusion can be visualized by imaging the transit of a contrast agent through the parenchyma of the organ using gray scale (GS) and power Doppler (PD) ultrasound.However, the relative merits and the sensitivities of the two imaging methods are not known. This study compares the effectiveness of the two modes in visualizing kidney perfusion at the clinical dose of contrast agents. GS and PD images of the dog kidneys were recorded using a clinical ultrasound scanner at 4-7 MHz. A fixed longitudinal plane of the kidney was imaged by mounting the transducer on the animal with a specially designed holder. A dose of 0.1 m1/kg of Echogen was injected intravenously and GS and PD images were recorded simultaneously on two separate time-encoded video tapes during the passage of the contrast agent through the kidneys. The enhancement of GS and PD images was assessed qualitatively by three radiologists. The quantitative assessment was made by measuring the regional and global enhancements of digitized B-scan and PS images. Regional measurements were made by comparing brightness of the post contrast images with that of a pre-contrast reference image pixel by pixel. Student t-test was used to determine the statistical significance of the change. The regions representing statistically significant differences were encoded on the image in color with brightness proportional to the magnitude of change. The regions with no significant change were represented in GS. This generated a series of new images, referred to as StatMap, with color representing regions of perfusion. Changes in power Doppler images were visually detectable with high confidence in all five dogs by al three radiologists. There was no perceptible changes in B-scans. Computer analysis of PD images yielded characteristic indicator dilution curves in all five dogs with an initial rise time of 2-5 sec and a peak at 7-20 sec. The enhancement in PD lasted for 97-400 seconds. The

  2. The Doppler Effect and Spectral Energy Distribution of Blazars

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The relativistic beaming model is adopted to discuss quantitatively the observational differences between radio-selected BL Lac objects (RBLs) and X-ray-selected BL Lac objects (XBLs), and between BL Lac objects and fiat spectrum radio quasars (FSRQs). The main results are the following: (1) In the Doppler cor-rected color-color (αin ro-αin ox -αox) diagram, XBLs and FSRQs occupy separated regions,while RBLs bridge the gap between them. These properties suggest that similar in- trinsic physical processes operate in all the objects under a range of intrinsic physical conditions. (2) Our results are consistent with the results of Sambruna, Maraschi and Urry (1996) from other methods. We show the αxox introduced by Sambruna to be a good index for describing the energy distribution because it represents the intrinsic energy distribution and includes the Doppler correction. (3) The Doppler effect of relativistic beaming is the main mechanism, and the physical differences (such as magnetic fields, electron energies) are also important complementary fac-tors for understanding the relation between XBLs and RBLs;

  3. Gestational trophoblastic neoplasia: efficacy of color doppler ultrasound

    Energy Technology Data Exchange (ETDEWEB)

    Song, Sun Wha; Jee, Won Hee; Choe, Bo Young; Byun, Jae Young; Choi, Byung Gil; Shinn, Kyung Sub [Catholic Univ. College of Medicine, Seoul (Korea, Republic of)

    1997-04-01

    To evaluate the efficacy of color Doppler ultrasound (US) in the diagnosis of gestational trophoblastic neoplasia (GTN). Intralesional color flows and resistive index (RI) on color Doppler US were prospectively analyzed in 21 consecutive suspected GTN cases. RI of the intralesional artery was investigated on the basis of the presence or absence of mass and metastasis. Correlation between RI of intralesional artery and urinary {beta}-hCG was also investigated. Intralesional color flows were identified in 15 patients with GTN. On operation, intralesional color flows were observed in one of two patients in whom the presence of completely necrotic tissue was confirmed. Intralesional color flows, however, were not detected in four patients who were proved not to be GTN sufferers. Sensitivity, specificity, accuracy, positive and negative predictive values, and accuracy were 100%, 83%, 95%, 94% and 100%, respectively. Significant correlation between RI of the intralesional artery and urinary {beta}-hCG was not established (p=0.49, r=0.19). RI of this artery was not substantially different between groups with and without mass, and between groups with and without metastasis (p=0.32, p=0.82). The current study demonstrates that color Doppler US is a sensitive and useful method for the diagnosis of GTN.

  4. Thermal tests for laser Doppler perfusion measurements in Raynaud's syndrome

    Science.gov (United States)

    Kacprzak, Michal; Skora, A.; Obidzinska, J.; Zbiec, A.; Maniewski, Roman; Staszkiewicz, W.

    2004-07-01

    The laser Doppler method offers a non-invasive, real time technique for monitoring of blood perfusion in microcirculation. In practical measurements the perfusion index is given only in relative values. Thus, accurate and reproducible results can be only obtained when using a well controlled stimulation test. The aim of this study was evaluation of the thermal stimulation test, which is frequently used to investigate microcirculation in patients with Raynaud's syndrome. Three types of thermal tests, in which air or water with temperature in range 5°C - 40°C were used. Ten normal volunteers and fifteen patients with clinical symptoms of the primary Raynaud's syndrome were enrolled in this study. To estimate skin microcirculation changes during the thermal test, the multichannel laser Doppler system and laser Doppler scanner were used. The obtained results were analyzed from the point of view of the efficiency of these methods and the thermal provocative tests in differentiation of normal subjects and patient with Raynaud's syndrome.

  5. Doppler Monitoring of five K2 Transiting Planetary Systems

    CERN Document Server

    Dai, Fei; Albrecht, Simon; Arriagada, Pamela; Bieryla, Allyson; Butler, R Paul; Crane, Jeffrey D; Hirano, Teriyuki; Johnson, John Asher; Kiilerich, Amanda; Latham, David W; Narita, Norio; Nowak, Grzegorz; Palle, Enric; Ribas, Ignasi; Rogers, Leslie A; Sanchis-Ojeda, Roberto; Shectman, Stephen A; Teske, Johanna K; Thompson, Ian B; Van Eylen, Vincent; Vanderburg, Andrew; Wittenmyer, Robert A; Yu, Liang

    2016-01-01

    In an effort to measure the masses of planets discovered by the NASA {\\it K2} mission, we have conducted precise Doppler observations of five stars with transiting planets. We present the results of a joint analysis of these new data and previously published Doppler data. The first star, an M dwarf known as K2-3 or EPIC~201367065, has three transiting planets ("b", with radius $2.1~R_{\\oplus}$; "c", $1.7~R_{\\oplus}$; and "d", $1.5~R_{\\oplus}$). Our analysis leads to the mass constraints: $M_{b}=8.1^{+2.0}_{-1.9}~M_{\\oplus}$ and $M_{c}$ < $ 4.2~M_{\\oplus}$~(95\\%~conf.). The mass of planet d is poorly constrained because its orbital period is close to the stellar rotation period, making it difficult to disentangle the planetary signal from spurious Doppler shifts due to stellar activity. The second star, a G dwarf known as K2-19 or EPIC~201505350, has two planets ("b", $7.7~R_{\\oplus}$; and "c", $4.9~R_{\\oplus}$) in a 3:2 mean-motion resonance, as well as a shorter-period planet ("d", $1.1~R_{\\oplus}$). We f...

  6. Robust population transfer in atomic beams induced by Doppler shifts

    Science.gov (United States)

    Unanyan, R. G.

    2016-10-01

    The influence of photon momentum recoil on adiabatic population transfer in an atomic three-level lambda system is studied. It is shown that the Doppler frequency shifts, due to atomic motion, can play an important role in adiabatic population transfer processes of atomic internal states by a pair of laser fields. For the limiting case of slow atoms (Doppler shift much smaller than the photon recoil energy), the atoms occupy the same target state regardless of the order of switching of laser fields, while for the case of fast atoms interacting with the intuitive sequence of pulses, the target state is the intermediate atomic state. Furthermore, it is shown that this novel technique for adiabatic population transfer is related to a level crossing in the bright-intermediate state basis (rather than in the original atomic basis). It is shown that these processes are robust with respect to parameter fluctuations, such as the laser pulse area and the relative spatial offset (delay) of the laser beams. The obtained results can be used for the control of temporal evolution of atomic populations in cold atomic beams by externally adjustable Doppler shifts.

  7. Advances in precision Doppler spectroscopy on cool stars

    Directory of Open Access Journals (Sweden)

    Anglada-Escudé Guillem

    2013-04-01

    Full Text Available I describe recent advances made in Doppler spectroscopy of low mass star and discuss how they perform on public observations ontained with the HARPS spectrograph. This work is possible thanks to the recent development of the HARPS-TERRA software (Template Enhanced Radial velocity Re-analysis Application, which obtains precision RV measurements by least-squares matching each spectrum to a high SNR template built from the same observations. As a result, we obtain a substantial increase in precision compared to the traditional cross-correlation methods. The increase in precision is demonstrated with RV measurements on stable M dwarfs (80 cm/s over time-scales of years and the early detection of several very low mass candidates. Moreover, the ability of HARPS-TERRA in reproducing the observed spectra at high fidelity allows us to explore new effects including : wavelength dependence of activity induced Doppler signals, simultaneous measurement of orbital obliquities and stellar rotation profiles and, when combined with advanced Bayesian data analysis techniques, small Doppler signals likely caused by new super-Earth mass candidates in the habitable zones of nearby stars.

  8. Experiences using laser Doppler vibrometers at Chernobyl Nuclear Power Plant

    Science.gov (United States)

    Yarovoi, Leonid K.; Robur, Lubomir I.; Siegmund, Georg; Tushev, Dmitry

    2000-05-01

    The implementation of laser vibrometers into various branches of industry solves complex technical problems as well as raising the authority of laser vibrometry as unique measurement tool. From this point of view, the nuclear industry is an interesting and attractive application field with specific and rigorous exploitation conditions of measuring systems. The objective of this work was to evaluate all advantages and disadvantages of the laser Doppler vibrometry with respect to nuclear power plant (NPP) equipment examination. The Chernobyl NPP is the ideal place for these purposes. The diagnostic ability on different Chernobyl NPP systems (e.g. third power unit main circulators, bearing shaft of fifth turbo-generator and various pipelines) has been demonstrated using laser Doppler vibrometers. The measurements performed by laser vibrometers were checked by standard Chernobyl NPP vibration measurement tools. The laser Doppler vibrometers (CLV, Polytec GmbH and LDV, Kiev University) have been tested and have shown full functionality in NPP zone at 0.5 sievert/hour radiation levels, high electromagnetic fields (magnetic component up to 5 kA/m) and significant vibrations.

  9. Lab Demonstration of the Hybrid Doppler Wind Lidar (HDWL) Transceiver

    Science.gov (United States)

    Marx, Catherine T.; Gentry, Bruce; Jordan, Patrick; Dogoda, Peter; Faust, Ed; Kavaya, Michael

    2013-01-01

    The recommended design approach for the 3D Tropospheric Winds mission is a hybrid Doppler lidar which combines the best elements of both a coherent aerosol Doppler lidar operating at 2 microns and a direct detection molecular Doppler lidar operating at 0.355 microns. In support of the mission, we built a novel, compact, light-weighted multi-field of view transceiver where multiple telescopes are used to cover the required four fields of view. A small mechanism sequentially selects both the "transmit" and "receive" fields of view. The four fields are combined to stimulate both the 0.355 micron receiver and the 2 micron receiver. This version is scaled (0.2 m diameter aperture) from the space-based version but still demonstrates the feasibility of the hybrid approach. The primary mirrors were conventionally light-weighted and coated with dielectric, high reflectivity coatings with high laser damage thresholds at both 2 microns and 0.355 microns. The mechanical structure and mounts were fabricated from composites to achieve dimensional stability while significantly reducing the mass. In the laboratory, we demonstrated the system level functionality at 0.355 microns and at 2 microns, raising the Technology Readiness Level (TRL) from 2 to 4.

  10. Doppler shifts in a tornado in the solar corona

    Science.gov (United States)

    Schmieder, B.; Mein, P.; Mein, N.; Levens, P. J.; Labrosse, N.; Ofman, L.

    2017-01-01

    Context. High resolution movies in 193 Å from the Atmospheric Imaging Assembly (AIA) on the Solar Dynamic Observatory (SDO) show apparent rotation in the leg of a prominence observed during a coordinated campaign. Such structures are commonly referred to as tornadoes. Time-distance intensity diagrams of the AIA data show the existence of oscillations suggesting that the structure is rotating. Aims: The aim of this paper is to understand if the cool plasma at chromospheric temperatures inside the tornado is rotating around its central axis. Methods: The tornado was also observed in Hα with a cadence of 30 s by the MSDP spectrograph, operating at the Solar Tower in Meudon. The MSDP provides sequences of simultaneous spectra in a 2D field of view from which a cube of Doppler velocity maps is retrieved. Results: The Hα Doppler maps show a pattern with alternatively blueshifted and redshifted areas of 5 to 10'' wide. Over time the blueshifted areas become redshifted and vice versa, with a quasi-periodicity of 40 to 60 min. Weaker amplitude oscillations with periods of 4 to 6 min are superimposed onto these large period oscillations. Conclusions: The Doppler pattern observed in Hα cannot be interpreted as rotation of the cool plasma inside the tornado. The Hα velocity observations give strong constraints on the possible interpretations of the AIA tornado.

  11. Adaptive clutter rejection for ultrasound color Doppler imaging

    Science.gov (United States)

    Yoo, Yang Mo; Managuli, Ravi; Kim, Yongmin

    2005-04-01

    We have developed a new adaptive clutter rejection technique where an optimum clutter filter is dynamically selected according to the varying clutter characteristics in ultrasound color Doppler imaging. The selection criteria have been established based on the underlying clutter characteristics (i.e., the maximum instantaneous clutter velocity and the clutter power) and the properties of various candidate clutter filters (e.g., projection-initialized infinite impulse response and polynomial regression). We obtained an average improvement of 3.97 dB and 3.27 dB in flow signal-to-clutter-ratio (SCR) compared to the conventional and down-mixing methods, respectively. These preliminary results indicate that the proposed adaptive clutter rejection method could improve the sensitivity and accuracy in flow velocity estimation for ultrasound color Doppler imaging. For a 192 x 256 color Doppler image with an ensemble size of 10, the proposed method takes only 57.2 ms, which is less than the acquisition time. Thus, the proposed method could be implemented in modern ultrasound systems, while providing improved clutter rejection and more accurate velocity estimation in real time.

  12. On the Fly Doppler Broadening Using Multipole Representation

    Energy Technology Data Exchange (ETDEWEB)

    Khassenov, Azamat; Choi, Sooyoung; Lee, Deokjung [Ulsan National Institute of Science and Technology, Ulsan (Korea, Republic of)

    2015-05-15

    On the Fly Doppler broadening is the technique to avoid pre-generation of the microscopic cross section, in other words, reduce the amount of storage. Currently, there are different types of formalisms used by NJOY code to generate reaction cross section and accomplish its Doppler broadening. Single-Level Breit-Wigner (SLBW) formalism is limited to well-separated resonances, in other words, it does not consider interference between energy levels. Multi-Level Breit- Wigner formalism (MLBW) was tested as the candidate for the cross section generation in the Monte Carlo code, which is under development in UNIST. According to the results, MLBW method requires huge amount of computational time to produce cross section at certain energy point. Reich-Moore (RM) technique can generate only 0K cross section, which means that it cannot produce broaden cross section directly from resonance parameters. The first step was to convert resonance parameters given in nuclear data file into multipoles. MPR shows very high potential to be used as the formalism in the on-the-fly Doppler broadening module of MCS. One of the main reasons is that comparison of the time cost shown in Table IV supports application of multipole representation.

  13. Color Doppler sonography and angioscintigraphy in hepatic Hodgkin's lymphoma

    Institute of Scientific and Technical Information of China (English)

    Mirjana V Stojkovi(c); Vera M Artiko; Irena B Radoman; Slavko J Kne(z)evi(c); Snezana M Luki(c); Mirko D Kerkez; Nebojsa S Leki(c); Andrija A Anti(c); Marinko M (Z)vela; Vitomir I Rankovi(c); Milorad N Petrovi(c); Dragana P (S)obi(c); Vladimir B Obradovi(c)

    2009-01-01

    AIM: To estimate the characteristics of Color Doppler findings and the results of hepatic radionuclide angiography (HRA) in secondary Hodgkin's hepatic lymphoma.METHODS: The research included patients with a diagnosis of Hodgkin's lymphoma with metastatic focal lesions in the liver and controls. Morphologic characteristics of focal liver lesions and hemodynamic parameters were examined by pulsed and Color Doppler in the portal, hepatic and splenic veins were examined. Hepatic perfusion index (HPI) estimated by HRA was calculated.RESULTS: In the majority of patients, hepatomegaly was observed. Lesions were mostly hypoechoic and mixed, solitary or multiple. Some of the patients presented with dilated splenic veins and hepatofugal blood flow. A pulse wave was registered in the centre and at the margins of lymphoma. The average velocity of the pulse wave was higher at the margins ( P >0.05). A continuous venous wave was found only at the margins of lymphoma. There was no linear correlation between lymphoma size and velocity of pulse and continuous wave ( r = 390, P < 0.01). HPI was significantly lower in patients with lymphomas than in controls ( P < 0.05), pointing out increased arterial perfusion in comparison to portal perfusion.CONCLUSION: Color Doppler ultrasonography is a sensitive method for the detection of neovascularization in Hodgkin's hepatic lymphoma and estimation of its intensity. Hepatic radionuclide angiography can additionally help in the assesment of vascularisation of liver lesions.

  14. Sevoflurane Used for Color Doppler Ultrasound Examination in Children.

    Science.gov (United States)

    Fan, Conghai; Zhang, Fengchao; Huang, Xiaomei; Wen, Cheng; Shan, Chengjing

    2015-05-01

    The objective of this study is to investigate the feasibility of sevoflurane inhalation in pediatric color doppler ultrasound examination. In this study, 30 cases of children under 1 year were selected. They were all I or II levels according to American Society of Anesthesiology. Children with severe cyanotic congenital heart disease or severe pneumonia were excluded. All the children received anesthesia with sevoflurane. The University of Michigan Sedation Scale was assessed and bispectral index (BIS) was recorded before induction (T0), after induction (T1), when maintaining (T2), and when waking-up (T3). Blood pressure and heart rate were monitored during the color doppler ultrasound examination, the time to receive sedation examination and anesthesia recovery time were also recorded. (1) Score for UMSS was zero at T0 and 3 at T1; (2) BIS value was 93.18 ± 2.94 at T0 and decreased to 87.6 ± 3.9 at T1; (3) Blood pressure or heart rate did not decline obviously; (4) The time to receive sedation examination was 46.4 ± 13.1 s and anesthesia recovery time was 7.8 ± 5.3 min. In conclusion, sevoflurane can be used in pediatric color doppler ultrasound examination safely and effectively.

  15. The role of Doppler ultrasound in rheumatic diseases.

    Science.gov (United States)

    Porta, Francesco; Radunovic, Goran; Vlad, Violeta; Micu, Mihaela C; Nestorova, Rodina; Petranova, Tzvetanka; Iagnocco, Annamaria

    2012-06-01

    The use of Doppler techniques, including power, colour and spectral Doppler, has greatly increased in rheumatology in recent years. This is due to the ability of Doppler US (DUS) to detect pathological vascularization within joints and periarticular soft tissues, thereby demonstrating the presence of active inflammation, which has been reported to be correlated with the local neo-angiogenesis. In synovitis, DUS showed a high correlation with histological and MRI findings, thus it is considered a valid tool to detect pathological synovial vascularization. Moreover, it is more sensitive than clinical examination in detecting active joint inflammation and in the evaluation of response to treatment. In addition, DUS may be considered as a reference imaging modality in the assessment of enthesitis, MRI being not sensitive and histology not feasible. Moreover, it has been demonstrated to be able to detect changes in asymptomatic enthesis. In conclusion, DUS is a useful and sensitive tool in the evaluation and monitoring of active inflammation. Its widespread use in clinical rheumatological practice is recommended. The aim of this article is to review the current literature about the role of DUS in rheumatic diseases, analysing its validity, reliability and feasibility.

  16. Doppler findings in chronic ectopic pregnancy: case report.

    Science.gov (United States)

    Abramov, Y; Nadjari, M; Shushan, A; Prus, D; Anteby, S O

    1997-05-01

    Chronic ectopic pregnancy is an uncommon form of tubal pregnancy manifested as a pelvic mass with minimal symptoms and a low or absent titer of human chorionic gonadotropin. For this reason, most of the reported cases have been diagnosed only after explorative laparotomy. The value of Doppler ultrasonography for preoperative diagnosis of this entity has not yet been established. We report on a 36-year-old patient who was admitted for intermittent right lower quadrant abdominal pain of 3 months' duration, and a right adnexal mass found on pelvic examination. On Doppler ultrasonography, a right complex adnexal mass was demonstrated, characterized by extensive external vascularization, aberrant vessels and arteriovenous shunting, but with no internal blood flow. Explorative laparotomy revealed a right tubal mass adherent to the omentum, and covered by numerous enlarged and tortuous blood vessels originating in the omentum. Pathological examination of the mass revealed a chronic ectopic pregnancy. The possible contribution of Doppler-specific characteristics for the diagnosis of chronic ectopic pregnancy is described and discussed.

  17. Doppler tomography of the Double periodic variable HD 170582 at low and high stage

    Science.gov (United States)

    Mennickent, R. E.; Zharikov, S.; Cabezas, M.; Djurašević, G.

    2016-09-01

    HD 170582 is an interacting binary of the double periodic variable (DPV) type, showing ellipsoidal variability with a period of 16.87 d along with a long photometric cycle of 587 d. It was recently studied by Mennickent et al., who found a slightly evolved B-type star surrounded by a luminous accretion disc fed by a Roche lobe overflowing A-type giant. Here we extend their analysis presenting new spectroscopic data and studying the Balmer emission lines. We find orbitally modulated double-peak Hα and Hβ emissions whose strength also vary in the long term. In addition, Doppler maps of the emission lines reveal sites of enhanced line emission in the first and fourth velocity quadrants, the first one consistent with the position of one of the bright zones detected by the light-curve analysis. We find a difference between Doppler maps at high and low stage of the long cycle; evidence that the emission is optically thicker at high state in the stream-disc impact region, possibly reflecting a larger mass transfer rate. We compare the system parameters with a grid of synthetic binary evolutionary tracks and find the best-fitting model. The system is found to be semi-detached, in a conservative Case-B mass transfer stage, with age 7.68 × 107 yr and mass transfer rate 1.6 × 10-6 M⊙ yr-1. For five well-studied DPVs, the disc luminosity scales with the primary mass and is much larger than the theoretical accretion luminosity.

  18. Anomalous Doppler instability in tokamaks: first principles simulation and observations in MAST

    Science.gov (United States)

    Dendy, Richard; Lai, Alan; Chapman, Sandra

    2015-11-01

    The evolution in velocity space of minority suprathermal electron populations undergoing the anomalous Doppler instability (ADI) is investigated using fully nonlinear particle-in-cell simulations (W N Lai et al., Phys. Plasmas 20, 102122 (2013); and submitted (2015)) that self-consistently evolve particles and fields in a magnetized plasma. Electron trajectories during different stages of the ADI are captured, and are analyzed in relation to the excited electric fields and the overall velocity distribution of electrons. The time-evolution of the moments of the perpendicular electron distribution function is studied to test the range of applicability of analytical approximations that involve a quasilinear wave-driven diffusion operator. For some electrons, trapping and mirroring are observed during the saturation phase. Recent measurements of microwave and X-ray emission during edge localized mode (ELM) activity in the MAST tokamak imply acceleration of electrons parallel to the magnetic field combined with rapid acquisition of perpendicular momentum. This suggests (S J Freethy et al., Phys. Rev. Lett. 114, 125004 (2015)) that the ADI is operating on electrons accelerated by inductive electric fields generated by the initial ELM instability. Work supported in part by the RCUK Energy Programme and EPSRC.

  19. Doppler ultrasound study of penis in men with systemic sclerosis: a correlation with Doppler indices of renal and digital arteries.

    Science.gov (United States)

    Rosato, E; Barbano, B; Gigante, A; Cianci, R; Molinaro, I; Quarta, S; Digiulio, M A; Messineo, D; Pisarri, S; Salsano, F

    2013-01-01

    Erectile dysfunction (ED) prevalence in male systemic sclerosis (SSc) is high and its pathogenesis is unclear. The aim of the study is to assess correlation between Doppler ultrasound indices of penis and kidneys or digital arteries in male systemic sclerosis. Fourteen men with systemic sclerosis were enrolled in this study. Erectile function was investigated by the International Index of Erectile Function-5. Peak systolic velocity, end diastolic velocity, resistive index, pulsative index, and systolic/diastolic ratio were measured on the cavernous arteries at the peno-scrotal junction in the flaccid state, on the interlobar artery of both kidneys and all ten proper palmar digital arteries. Ten (71 percent) patients have an International Index of Erectile Function-5 less than 21. Reduction of penis peak systolic velocity was observed in all SSc subjects. Doppler indices of cavernous arteries correlate with the International Index of Erectile Function-5. The renal and digital arteries resistive index demonstrated a good correlation (p less than 0.0001) with International Index of Erectile Function-5. A positive correlation exists between penis and kidney arteries Doppler indices: end diastolic velocity (p less than 0.05, r=0.54), resistive index (p less than 0.0001, r=0.90), systolic/diastolic ratio (p less than 0.01, r=0.69). A positive correlation was observed between penis and digital arteries Doppler indices: peak systolic velocity (p less than 0.01, r=0.68), end diastolic velocity (p less than 0.01, r=0.75), resistive index (p less than 0.001, r=0.79), systolic/diastolic ratio (p less than 0.05, r=0.59). A correlation exists between arterial impairment of penis and renal or digital arteries.

  20. Dynamic color Doppler sonography in the assessment of erectile dysfunctions; Utilizzazione dell'eco color Doppler dinamico del pene nello studio delle disfunzioni erettili

    Energy Technology Data Exchange (ETDEWEB)

    Aversa, A.; Bonifacio, V.; Isidori, A.; Fabbri, A. [Rome Univ. (Italy). Cattedra di Andrologia. Dipt. di Fisiopatologia Medica; Bertucci, B. [Azienda Ospedaliera Pugliese Ciaccio, Catanzaro (Italy). Servizio di Radiologia

    1999-06-01

    The authors investigated the diagnostic accuracy of dynamic color Doppler sonography (D-CDS) in men with erectile dysfunctions (ED). Terminal microcirculation alterations and their correlation with erectile response after drug testing were investigated with power Doppler energy. Penile sonography in the flaccid state can show calcificic plaques and/or fibrosis of the corpora. Redosing of PGE{sub 1} plus phentolamine during D-CDS is a safe procedure and improves diagnostic accuracy in erectile dysfunctions, with significantly fewer non-responders than redosing of PGE{sub 1} alone. Power Doppler energy shows altered morphology of helicine arterioles otherwise missed at color Doppler and is thus recommended to make an accurate diagnosis in some men with erectile dysfunctions. [Italian] Scopo dello studio e' quello di valutare l'accuratezza diagnostica dell'eco color Doppler dinamico del pene nei soggetti affetti da disfunzione erettile. Inoltre si e' voluto verificale la presenza di alterazioni della vascolarizzazione arteriosa terminale con modulo power Doppler e come la presenza di queste alterazioni del microcircolo si correlino con la risposta erettiva della farmacoinfusione intracavernosa. Con l'eco color Doppler penieno basale e' possibile identificare placche calcifiche e/o fibrosi nei corpi cavernosi. Durante la fase dinamica con color Doppler , la re-iniezione con PGE{sub 1} e fentolamina si e' dimostrata sicura e ha migliorato l'accuratezza diagnostica riducendo il numero di soggetti con mancata risposta erettiva rispetto alla sola PGE{sub 1}. Con power Doppler sono state identificate alterazioni morfologiche delle arterioleelicine non visibili con il color Doppler consentendo la diagnosi piu' precisain alcuni casi di disfunzione erettile.

  1. Avaliação de pacientes assintomáticos com forma crônica da doença de Chagas através da análise do eletrocardiograma dinâmico, ecocardiograma e do peptídeo natriurético tipo B Evaluation of asymptomatic patients with chronic Chagas’ disease through ambulatory electrocardiogram, echocardiogram and B-Type natriuretic peptide analyses

    Directory of Open Access Journals (Sweden)

    Divina Seila de Oliveira Marques

    2006-09-01

    Full Text Available OBJETIVO: Avaliar pacientes assintomáticos com forma crônica da doença de Chagas em relação a prevalência de arritmias ventriculares, disfunção ventricular esquerda e níveis plasmáticos do peptídeo natriurético tipo B (BNP. MÉTODOS: Avaliação clínica, eletrocardiograma (ECG, índice cardiotorácico (ICT, eletrocardiograma dinâmico, ecocardiograma e dosagem BNP foram realizados em 106 pacientes do Ambulatório de Doença de Chagas, distribuídos em três grupos: GI (50-ECG normal, GIIA (31-ECG com alterações características de doença de Chagas e GIIB (25-ECG com outras alterações. RESULTADOS: Alterações eletrocardiográficas mais prevalentes no GIIA: bloqueio completo do ramo direito, bloqueio divisional ântero-superior esquerdo (35% cada e áreas inativas (32%, GIIB: alteração da repolarização inferolateral (28% e sobrecarga ventricular esquerda (24%. Os valores médios do ICT foram semelhantes (p = 0,383. A prevalência de arritmia ventricular foi maior nos grupos GIIA (77% e GIIB (75% do que no GI (46% (p = 0,002. A disfunção ventricular foi mais prevalente no GIIA (52% e GIIB (32% do que no GI (14% (p = 0,001. A disfunção sistólica foi mais prevalente no GIIA (29% do que no GIIB (20% e GI (2% (p OBJECTIVE: To evaluate asymptomatic patients with chronic Chagas’ disease to determine prevalence of ventricular arrhythmias, left ventricular dysfunction, and B-type natriuretic peptide (BNP plasma levels. METHODS: One hundred and six patients from the Chagas’ disease outpatient clinic underwent clinical evaluation, electrocardiogram (ECG, cardiothoracic index (CTI, ambulatory electrocardiogram (Holter monitoring, echocardiogram, and BNP measurement and then were distributed into three groups: GI, with normal ECG (n = 50; GIIA, with ECG changes characteristic of Chagas’ disease (n = 31; and GIIB, with other ECG changes (n = 25. RESULTS: The most common electrocardiographic changes were the following. GIIA

  2. Realizing Tunable Inverse and Normal Doppler Shifts in Reconfigurable RF Metamaterials

    Science.gov (United States)

    Ran, Jia; Zhang, Yewen; Chen, Xiaodong; Fang, Kai; Zhao, Junfei; Sun, Yong; Chen, Hong

    2015-06-01

    The Doppler effect has well-established applications in astronomy, medicine, radar and metrology. Recently, a number of experimental demonstrations of the inverse Doppler effect have begun to appear. However, the inverse Doppler effect has never been observed on an electronically reconfigurable system with an external electromagnetic wave source at radio frequencies (RF) in experiment. Here we demonstrate an experimental observation of the inverse Doppler shift on an electronically reconfigurable RF metamaterial structure, which can exhibit anomalous dispersion, normal dispersion or a stop band, depending on an applied bias voltage. Either inverse or normal Doppler shift is realized by injecting an external RF signal into the electronically reconfigurable metamaterial, on which an electronically controllable moving reflective boundary is formed. The effective velocity of this boundary and the resulting frequency shift can be tuned over a wide range by a digital switching circuit. This work is expected to open up possibilities in applying the inverse Doppler effect in wireless communications, radar and satellite navigation.

  3. Gold nanorods as a contrast agent for Doppler optical coherence tomography.

    Directory of Open Access Journals (Sweden)

    Bo Wang

    Full Text Available PURPOSE: To investigate gold nanorods (GNRs as a contrast agent to enhance Doppler optical coherence tomography (OCT imaging of the intrascleral aqueous humor outflow. METHODS: A serial dilution of GNRs was scanned with a spectral-domain OCT device (Bioptigen, Durham, NC to visualize Doppler signal. Doppler measurements using GNRs were validated using a controlled flow system. To demonstrate an application of GNR enhanced Doppler, porcine eyes were perfused at constant pressure with mock aqueous alone or 1.0×10(12 GNR/mL mixed with mock aqueous. Twelve Doppler and volumetric SD-OCT scans were obtained from the limbus in a radial fashion incremented by 30°, forming a circular scan pattern. Volumetric flow was computed by integrating flow inside non-connected vessels throughout all 12 scans around the limbus. RESULTS: At the GNR concentration of 0.7×10(12 GNRs/mL, Doppler signal was present through the entire depth of the testing tube without substantial attenuation. A well-defined laminar flow profile was observed for Doppler images of GNRs flowing through the glass capillary tube. The Doppler OCT measured flow profile was not statistically different from the expected flow profile based upon an autoregressive moving average model, with an error of -0.025 to 0.037 mm/s (p = 0.6435. Cross-sectional slices demonstrated the ability to view anterior chamber outflow ex-vivo using GNR-enhanced Doppler OCT. Doppler volumetric flow measurements were comparable to flow recorded by the perfusion system. CONCLUSIONS: GNRs created a measureable Doppler signal within otherwise silent flow fields in OCT Doppler scans. Practical application of this technique was confirmed in a constant pressure ex-vivo aqueous humor outflow model in porcine eyes.

  4. Integrated Range-Doppler Map and Extended Target Classification with Adaptive Waveform for Cognitive Radar

    Science.gov (United States)

    2014-12-01

    RANGE-DOPPLER MAP AND EXTENDED TARGET CLASSIFICATION WITH ADAPTIVE WAVEFORM FOR COGNITIVE RADAR by Jo-Yen Nieh December 2014 Dissertation...TYPE AND DATES COVERED Dissertation 4. TITLE AND SUBTITLE INTEGRATED RANGE-DOPPLER MAP AND EXTENDED TARGET CLASSIFICATION WITH ADAPTIVE WAVEFORM ...design an extended target classification scheme while determining the target’s range-and-Doppler location with the use of adaptive waveform for a

  5. Blood flow measurements during hemodialysis vascular access interventions - Catheter-based thermodilution or Doppler ultrasound?

    DEFF Research Database (Denmark)

    Heerwagen, Søren T; Hansen, Marc A; Schroeder, Torben V

    2012-01-01

    Purpose: To test the clinical performance of catheter-based thermodilution and Doppler ultrasound of the feeding brachial artery for blood flow measurements during hemodialysis vascular access interventions.Methods: Thirty patients with arteriovenous fistulas who underwent 46 interventions had...... access blood flow measured before and after every procedure. Two methods, catheter-based thermodilution and Doppler ultrasound, were compared to the reference method of ultrasound dilution. Catheter-based thermodilution and Doppler ultrasound were performed during the endovascular procedures while flow...

  6. Micro-Doppler Frequency Estimation Based on Radon-Wigner Transform

    Directory of Open Access Journals (Sweden)

    Sun Huixia

    2014-01-01

    Full Text Available A nonparametric computationally efficient algorithm is proposed for micro-Doppler frequency estimation, assuming that this non-linear micro-Doppler frequency is approximate linear frequency in short-time intervals. In this algorithm, we use Radon-Wigner transform in short-time intervals to estimate micro-Doppler frequency. Simulation results confirm the effectiveness of the proposed method.Defence Science Journal, Vol. 64, No. 1, January 2014, DOI:10.14429/dsj.64.2980

  7. Dispersed single-phase-step Michelson interferometer for Doppler imaging using sunlight.

    Science.gov (United States)

    Wan, Xiaoke; Ge, Jian

    2012-09-15

    A Michelson interferometer is dispersed with a fiber array-fed spectrograph, providing 59 Doppler sensing channels using sunlight in the 510-570 nm wavelength region. The interferometer operates at a single-phase-step mode, which is particularly advantageous in multiplexing and data processing compared to the phase-stepping mode of other interferometer spectrometer instruments. Spectral templates are prepared using a standard solar spectrum and simulated interferometer modulations, such that the correlation function with a measured 1D spectrum determines the Doppler shift. Doppler imaging of a rotating cylinder is demonstrated. The average Doppler sensitivity is ~12 m/s, with some channels reaching ~5 m/s.

  8. A New Underwater Acoustic Navigation Method Based on the Doppler Principle

    Directory of Open Access Journals (Sweden)

    Jinsong Tang

    2013-07-01

    Full Text Available In this paper, a new underwater acoustic navigation method is proposed, which is named from Doppler Acoustic Omnirange Beacon (DAOB. It is borrowed from the idea of Doppler VHF Omnirange (DVOR and based on the Doppler principle. The cause of Doppler effect in the received signal is the motion or position change of one or two sources. The effect of multipath is analyzed, and an improved signal form is presented to solve the rigorous multipath environment underwater. Some simulation is presented to verify the performance.    

  9. Coherent Doppler Laser Radar: Technology Development and Applications

    Science.gov (United States)

    Kavaya, Michael J.; Arnold, James E. (Technical Monitor)

    2000-01-01

    NASA's Marshall Space Flight Center has been investigating, developing, and applying coherent Doppler laser radar technology for over 30 years. These efforts have included the first wind measurement in 1967, the first airborne flights in 1972, the first airborne wind field mapping in 1981, and the first measurement of hurricane eyewall winds in 1998. A parallel effort at MSFC since 1982 has been the study, modeling and technology development for a space-based global wind measurement system. These endeavors to date have resulted in compact, robust, eyesafe lidars at 2 micron wavelength based on solid-state laser technology; in a factor of 6 volume reduction in near diffraction limited, space-qualifiable telescopes; in sophisticated airborne scanners with full platform motion subtraction; in local oscillator lasers capable of rapid tuning of 25 GHz for removal of relative laser radar to target velocities over a 25 km/s range; in performance prediction theory and simulations that have been validated experimentally; and in extensive field campaign experience. We have also begun efforts to dramatically improve the fundamental photon efficiency of the laser radar, to demonstrate advanced lower mass laser radar telescopes and scanners; to develop laser and laser radar system alignment maintenance technologies; and to greatly improve the electrical efficiency, cooling technique, and robustness of the pulsed laser. This coherent Doppler laser radar technology is suitable for high resolution, high accuracy wind mapping; for aerosol and cloud measurement; for Differential Absorption Lidar (DIAL) measurements of atmospheric and trace gases; for hard target range and velocity measurement; and for hard target vibration spectra measurement. It is also suitable for a number of aircraft operations applications such as clear air turbulence (CAT) detection; dangerous wind shear (microburst) detection; airspeed, angle of attack, and sideslip measurement; and fuel savings through

  10. Observing crosswind over urban terrain using scintillometer and Doppler lidar

    Directory of Open Access Journals (Sweden)

    D. van Dinther

    2014-07-01

    Full Text Available In this study, the crosswind (wind component perpendicular to a path, U⊥ is measured by a scintillometer and Doppler lidar above the urban environment of Helsinki, Finland, for 3 weeks. The scintillometer allows acquisition of a path-averaged value of U⊥ (U⊥, while the Doppler lidar allows acquisition of path-resolved U⊥ (U⊥ (x, where x is the position along the path. The goal of this study is to evaluate the applicability of scintillometer U⊥-measurements for conditions where U⊥ (x is variable. If the scintillometer is applicable in such variable-wind conditions, it can also be used in the urban environment. Two methods were applied to obtain U⊥ from the scintillometer signal; the cumulative spectrum method (relies on scintillation spectra, and the lookup table method (relies on time-lagged correlation functions. Both methods compared reasonably well with the Doppler lidar measurements, especially considering the challenging urban environment in which they were measuring; with RMSE of 0.71 and 0.73 m s−1. This indicates that both measurement technologies are able to obtain U⊥ in the complex urban environment. The in detail investigation of four cases indicate that the cumulative spectrum method is less susceptible to a variable U⊥ (x than the lookup table method. However, the lookup table method can be adjusted to improve its capabilities to obtain U⊥ for conditions where U⊥ (x is variable.

  11. Color doppler energy (CDE) : initial ten-months experience

    Energy Technology Data Exchange (ETDEWEB)

    Ro, Young Jin; Son, Hyun Ju; Lee, Suck Hong; Kim, Byung Soo [Pusan National Univ. College of Medicine, Pusan (Korea, Republic of); Han, Kook Sang; Nam, SAng Hwa; Lee, Keum Seob [Haedong Hospital, Pusan (Korea, Republic of); Shin Se Kwon [Daedong Hospital, Pusan (Korea, Republic of)

    1996-06-01

    Color Doppler imaging(CDI) has shortcomings, including random noise, aliasing, and angle dependence. To overcome these, a method using CD US, termed power doppler or Color Doppler Energy(CDE), has recently been introduced. The purpose of this study was to show the clinical usefulness of CDE. We retrospectively analyzed the CDI and CDE of 61 cases(20 renal pseudotumors, 8 musculoskeletal inflammations, 17 epididymitis or epididymo-orchitis, 3 varicoceles, 1 normal testis, 1 hepatocellualr carcinoma, 7 renal cell carcinoma, 1 renal angiomyolipoma, and 3 splenic varices). CDI and CDE scans were obtained at the same region with constant scan plane. The color gain was increased until noise first became perceptible, and scans were always obtained in such a way that the maximum amount of vascularity was shown. Thereafter, the vascularity, vascular displacement, and the vascular relationship between CDI and CDE were compared. In 17 of 20 cases of pseudotumor in the kidney, normal vascularity was identified in CDI and CDE, but was more cleary visible in CDE. In three cases, there was no visible vascularity in CDI, but normal vascularity in CDE. In eight cases of musculoskeletal inflammation and 17 cases of epididymitis with or without orchitis, the vascularity was increased due to hyperemia, which was more prominently seen in CDE than in CDI. In three varicoceles, CDE appeared to be better in demonstrating low velocity flow. In one patient who was suspected of having acute testicular torsion, CDE was helpful in excluding this suspicion. In one case of hepatocellualr carcinoma, seven cases of renal cell carcinoma, one case of renal angiomyolipoma, and three cases of splenic varices, CDE was better than CDI in showing the vascularity, vascular relationship, and vascular displacement.

  12. From HARPS to CODEX: exploring the limits of Doppler measurements

    Science.gov (United States)

    Pepe, F. A.; Lovis, C.

    2008-08-01

    Only 3 6 years ago, the Doppler technique was believed to have reached its final limitations in measuring stellar velocities and finding extra-solar planets. The 3 4 m s-1 precision level achieved, at that time, by various teams, was certainly limited by instrumental performances, but also constrained, as believed by a part of the community, by intrinsic stellar limitations. The advent of HARPS drastically changed this view. The instrument demonstrated, through its recent discoveries, that stars more 'stable' than 1 m s-1 actually exist, and that their radial velocity (RV) can be measured at that level of precision. Short-term precision of 20 cm s-1 rms and long-term precision of the order of 30 60 cm s-1 rms have been actually achieved on real stars, showing that RVs still harbor a great potential, and not only in the domain of extra-solar planets. Indeed, HARPS inspired the CODEX@ELT experiment for the direct determination of the expansion of the Universe, measuring the Doppler shift of Ly-α forest lines as a function of time. This experiment calls for a Doppler precision as low as 1 cm s-1, which in turn inspires new possibilities in the domain of extra-solar planets. We will investigate the obstacles on the way to cm s-1 precision. The discussion presented here will be based on our experience with HARPS and what we consider to be the current limitations set by the instrument, telescope, atmosphere and star. Finally, we will also provide an outlook on possible improvements and expected performances, which will finally define new scientific opportunities.

  13. From HARPS to CODEX: exploring the limits of Doppler measurements

    Energy Technology Data Exchange (ETDEWEB)

    Pepe, F A; Lovis, C [Observatoire Astronomique, Universite de Geneve, CH-1290 Sauverny (Switzerland)], E-mail: Francesco.Pepe@obs.unige.ch

    2008-08-15

    Only 3-6 years ago, the Doppler technique was believed to have reached its final limitations in measuring stellar velocities and finding extra-solar planets. The 3-4 m s{sup -1} precision level achieved, at that time, by various teams, was certainly limited by instrumental performances, but also constrained, as believed by a part of the community, by intrinsic stellar limitations. The advent of HARPS drastically changed this view. The instrument demonstrated, through its recent discoveries, that stars more 'stable' than 1 m s{sup -1} actually exist, and that their radial velocity (RV) can be measured at that level of precision. Short-term precision of 20 cm s{sup -1} rms and long-term precision of the order of 30-60 cm s{sup -1} rms have been actually achieved on real stars, showing that RVs still harbor a great potential, and not only in the domain of extra-solar planets. Indeed, HARPS inspired the CODEX at ELT experiment for the direct determination of the expansion of the Universe, measuring the Doppler shift of Ly-{alpha} forest lines as a function of time. This experiment calls for a Doppler precision as low as 1 cm s{sup -1}, which in turn inspires new possibilities in the domain of extra-solar planets. We will investigate the obstacles on the way to cm s{sup -1} precision. The discussion presented here will be based on our experience with HARPS and what we consider to be the current limitations set by the instrument, telescope, atmosphere and star. Finally, we will also provide an outlook on possible improvements and expected performances, which will finally define new scientific opportunities.

  14. Corrections to sodar Doppler winds due to wind drift

    Directory of Open Access Journals (Sweden)

    Stuart Bradley

    2015-11-01

    Full Text Available Refraction of the acoustic beam from a sodar, or translation of the beam due to the wind (known as wind drift, both affect the scattering angle and hence the Doppler shift of the return signal. Wind drift has been the subject of a number of previous studies, which have shown that errors increase with wind speed, giving about 6 % error in the estimated wind speed when the actual wind speed is 7 ms−1. Since previous studies have not treated the general case of finite angular beam width, a new analytic treatment is given here for monostatic sodars. Surprisingly, it is found that the Doppler error contributed by the transmitted beam is exactly compensated by the Doppler error contributed by the received beam, if the two beam widths are the same. If the transmitter beam width is not equal to the receiver beam width, then either over-estimation or under-estimation of wind speed results, depending on which beam is wider. This has implications for bi-static sodars, in which it is not possible to match beam widths. Contrary to this new theory, examples of field comparisons with mast instrumentation show a non-linear relationship between wind speeds measured by a sodar and wind speeds measured by mast-mounted instruments. It is proposed that this is due to the acoustic baffle clipping the received beam and changing its width, since the received beam must return at lower elevations from scattering downwind. This is shown to be feasible for a Metek sodar. The sign and magnitude of the observed non-linear dependence of estimated wind speed on actual wind speed are consistent with this proposed mechanism.

  15. Coupling Between Doppler Radar Signatures and Tornado Damage Tracks

    Science.gov (United States)

    Jedlovec, Gary J.; Molthan, Andrew L.; Carey, Lawrence; Carcione, Brian; Smith, Matthew; Schultz, Elise V.; Schultz, Christopher; Lafontaine, Frank

    2011-01-01

    On April 27, 2011, the southeastern United States was raked with several episodes of severe weather. Numerous tornadoes caused extensive damage, and tragically, the deaths of over 300 people. In Alabama alone, there were 61 confirmed tornados, 4 of them produced EF5 damage, and several were on the ground an hour or more with continuous damage tracks exceeding 80km. The use of Doppler radars covering the region provided reflectivity and velocity signatures that allowed forecasters to monitors the severe storms from beginning to end issuing hundreds of severe weather warnings throughout the day. Meteorologists from the the NWS performed extensive surveys to assess the intensity, duration, and ground track of tornadoes reported during the event. Survey activities included site visits to the affected locations, analysis of radar and satellite data, aerial surveys, and interviews with eyewitnesses. Satellite data from NASA's MODIS and ASTER instruments played a helpful role in determining the location of tornado damage paths and in the assessment. High resolution multispectral and temporal composites helped forecasters corroborate their damage assessments, determine starting and ending points for tornado touchdowns, and helped to provide forecasters with a better big-picture view of the damage region. The imagery also helped to separate damage from the April 27th tornados from severe weather that occurred earlier that month. In a post analysis of the outbreak, tornado damage path signatures observed in the NASA satellite data have been correlated to "debris ball" signatures in the NWS Doppler radars and a special ARMOR dual-polarization radar operated by the University of Alabama Huntsville during the event. The Doppler radar data indicates a circular enhanced reflectivity signal and rotational couplet in the radial velocity likely associated with the tornado that is spatially correlated with the damage tracks in the observed satellite data. An algorithm to detect and

  16. [Doppler ultrasound diagnosis in post-term pregnancy].

    Science.gov (United States)

    Jörn, H; Funk, A; Fendel, H

    1993-09-01

    The capability of Doppler flow velocimetry to predict intrauterine growth retardation is well known. The increased morbidity and mortality rate of postterm newborns is also well known. The aim of our study was to examine if Doppler flow velocimetry is able to indicate foetal jeopardy in the postterm period. Flow velocimetry of the foetal descending aorta, the umbilical artery, the uterine arteries and in 59 cases also the foetal middle cerebral artery was obtained from 167 pregnancies after 40 completed weeks of gestation. We found significant changes of normal values in prolonged pregnancy compared to third trimester normal values, examining the mean velocity of the foetal descending aorta and the S/D-ratio of the umbilical artery. No clinically significant changes were found examining the S/D-ratio of the uterine arteries and the pulsatility index of the foetal middle cerebral artery. Daily examinations of the foetal descending aorta were carried out in 23 and of the umbilical artery in 19 cases during the last four days before delivery, and in 11 cases of the foetal middle cerebral artery during the last three days before delivery. We did not find significant changes in the medians of the mean velocity of the foetal aorta, of the S/D-ratio of the umbilical artery and of the pulsatility index of the foetal middle cerebral artery. Measurement of sensitivity and positive predictive value of the four arteries examined showed, that Doppler ultrasound could not predict small for date infants or Caesarean section because of foetal distress.(ABSTRACT TRUNCATED AT 250 WORDS)

  17. Duplex Doppler ultrasound study of the temporomandibular joint.

    Science.gov (United States)

    Stagnitti, A; Marini, A; Impara, L; Drudi, F M; Lo Mele, L; Lillo Odoardi, G

    2012-06-01

    Sommario INTRODUZIONE: La fisiologia articolare dell’articolazione temporo-mandibolare (ATM) può essere esaminata sia dal punto di vista clinico che strumentale. La diagnostica per immagini ha da tempo contribuito con la risonanza magnetica (RM) e anche con la radiografia (Rx) e la tomografia computerizzata (TC) all’analisi della morfologia dei capi articolari e della cinetica condilare. L’esame duplex-ecodoppler è una metodica di largo impiego nello studio delle strutture in movimento in particolar modo a livello delle strutture del sistema vascolare. MATERIALI E METODI: È stata utilizzata un’apparecchiatura Toshiba APLIO SSA-770A, con l’uso di tecnica duplex-ecodoppler multi display, che consente la visualizzazione contemporanea dell’immagine ecografica e dei segnali Doppler utilizzando una sonda lineare del tipo phased array con cristalli trasduttori funzionanti ad una frequenza fondamentale di 6 MHz per gli spettri Doppler pulsati e 7.5 MHz per l’imaging ecografico. Sono stati esaminati nel Dipartimento di Scienze Radiologiche, Oncologiche e Anatomo-patologiche dell’Università “Sapienza” di Roma, 30 pazienti del reparto di Ortognatodonzia dell’Istituto di Odontoiatria della stessa Università. RISULTATI: Nei pazienti normali si è ottenuta un’alternanza regolare degli spettri Doppler, mentre nei soggetti con disfunzioni del complesso condilo-meniscale, si è persa la regolarità della sommatoria degli spettri di Fourier, con altezze incostanti in relazione a spostamenti irregolari del complesso condilo-meniscale. CONCLUSIONI: L’esame ecodoppler si è dimostrato, in tutti i pazienti, capace di discriminare quelli normali dai patologici e tra questi ultimi ha permesso di identificare gli aspetti più significativi delle patologie disfunzionali.

  18. Real-time and interactive virtual Doppler ultrasound

    Science.gov (United States)

    Hirji, Samira; Downey, Donal B.; Holdsworth, David W.; Steinman, David A.

    2005-04-01

    This paper describes our "virtual" Doppler ultrasound (DUS) system, in which colour DUS (CDUS) images and DUS spectrograms are generated on-the-fly and displayed in real-time in response to position and orientation cues provided by a magnetically tracked handheld probe. As the presence of complex flow often confounds the interpretation of Doppler ultrasound data, this system will serve to be a fundamental tool for training sonographers and gaining insight into the relationship between ambiguous DUS images and complex blood flow dynamics. Recently, we demonstrated that DUS spectra could be realistically simulated in real-time, by coupling a semi-empirical model of the DUS physics to a 3-D computational fluid dynamics (CFD) model of a clinically relevant flow field. Our system is an evolution of this approach where a motion-tracking device is used to continuously update the origin and orientation of a slice passing through a CFD model of a stenosed carotid bifurcation. After calibrating our CFD model onto a physical representation of a human neck, virtual CDUS images from an instantaneous slice are then displayed at a rate of approximately 15 Hz by simulating, on-the-fly, an array of DUS spectra and colour coding the resulting spectral mean velocity using a traditional Doppler colour scale. Mimicking a clinical examination, the operator can freeze the CDUS image on-screen, and a spectrogram corresponding to the selected sample volume location is rendered at a higher frame rate of at least 30 Hz. All this is achieved using an inexpensive desktop workstation and commodity graphics card.

  19. Cancer therapy and cardiotoxicity: The need of serial Doppler echocardiography

    Directory of Open Access Journals (Sweden)

    Pardo Moira

    2007-01-01

    Full Text Available Abstract Cancer therapy has shown terrific progress leading to important reduction of morbidity and mortality of several kinds of cancer. The therapeutic management of oncologic patients includes combinations of drugs, radiation therapy and surgery. Many of these therapies produce adverse cardiovascular complications which may negatively affect both the quality of life and the prognosis. For several years the most common noninvasive method of monitoring cardiotoxicity has been represented by radionuclide ventriculography while other tests as effort EKG and stress myocardial perfusion imaging may detect ischemic complications, and 24-hour Holter monitoring unmask suspected arrhythmias. Also biomarkers such as troponine I and T and B-type natriuretic peptide may be useful for early detection of cardiotoxicity. Today, the widely used non-invasive method of monitoring cardiotoxicity of cancer therapy is, however, represented by Doppler-echocardiography which allows to identify the main forms of cardiac complications of cancer therapy: left ventricular (systolic and diastolic dysfunction, valve heart disease, pericarditis and pericardial effusion, carotid artery lesions. Advanced ultrasound tools, as Integrated Backscatter and Tissue Doppler, but also simple ultrasound detection of "lung comet" on the anterior and lateral chest can be helpful for early, subclinical diagnosis of cardiac involvement. Serial Doppler echocardiographic evaluation has to be encouraged in the oncologic patients, before, during and even late after therapy completion. This is crucial when using anthracyclines, which have early but, most importantly, late, cumulative cardiac toxicity. The echocardiographic monitoring appears even indispensable after radiation therapy, whose detrimental effects may appear several years after the end of irradiation.

  20. [Doppler flowmetric fetal indices in low-risk pregnancies].

    Science.gov (United States)

    Romero Gutiérrez, G; Ponce de León, A L; Ramos Palma, S

    1999-10-01

    In order to measure the umbilical resistance and pulsatility Doppler indexes 60 pregnant women with low risk pregnancies were studied in a descriptive, observational and prospective study carried out at the Hospital de Gineco-Pediatria numero 48 del Instituto Mexicano del Seguro Social. Umbilical Doppler measurements were done of the fetal umbilical cord from the week 30 at the 40 of gestation. We carried out a total of 337 measurements and 178 (52.8%) corresponded to the resistance index and 159 (47.2%) to the pulsatility index. The average of the resistance index was 0.64 with a range average (average plus two standard deviations was 0.48-0.79) and the pulsatility index had an average value of 0.94 with an average range of 0.58-1.30. The percentil values of the resistance index were 0.52, 0.66 and 0.79 respectively in the percentil 5, 50 and 95 whereas the percentil values of the pulsatility index were 0.64, 0.94 and 1.28 respectively in the percentil 5, 50 and 95. The analysis of variance with the Bonferroni test for multiple comparisons showed that our found indexes can be applied from the week 31 to the 40 of gestation. Our findings are in according to reported by other authors and it should be kept in mind that the concept of normality of the Doppler velocimetry indexes is strictly statistical and that only its judicious use will offer the benefit to our pregnant patients to obtain products under good conditions of health.

  1. Radio wave phase scintillation and precision Doppler tracking of spacecraft

    Science.gov (United States)

    Armstrong, J. W.

    Phase scintillation caused by propagation through solar wind, ionospheric, and tropospheric irregularities is a noise process for many spacecraft radio science experiments. In precision Doppler tracking observations, scintillation can be the dominant noise process. Scintillation statistics are necessary for experiment planning and in design of signal processing procedures. Here high-precision tracking data taken with operational spacecraft (Mars Observer, Galileo, and Mars Global Surveyor) and ground systems are used to produce temporal statistics of tropospheric and plasma phase scintillation. The variance of Doppler frequency fluctuations is approximately decomposed into two propagation processes. The first, associated with distributed scattering along the sight line in the solar wind, has a smooth spectrum. The second, associated principally with localized tropospheric scattering for X-band experiments, has a marked autocorrelation peak at the two-way light time between the Earth and the spacecraft (thus a cosine-squared modulation of the fluctuation power spectrum). For X-band data taken in the antisolar hemisphere the average noise levels of this process are in good agreement with average tropospheric noise levels determined independently from water vapor radiometer observations and radio interferometic data. The variance of the process having a smooth spectrum is consistent with plasma noise levels determined independently from dual-frequency observations of the Viking spacecraft made at comparable Sun-Earth-spacecraft angles. The observations reported here are used to refine the propagation noise model for Doppler tracking of deep space probes. In particular, they can be used to predict propagation noise levels for high-precision X- and Ka-band tracking observations (e.g., atmosphere/ionosphere/ring occultations, celestial mechanics experiments, and gravitational wave experiments) to be done using the Cassini spacecraft.

  2. Abu al-Layth al-Libi

    Science.gov (United States)

    2015-02-01

    He has described at length the various methods to which the prisoners were subjected, including sleep depravation, nudity and the use of electrodes...suspects of the Riyadh bombing acknowledge their involvement on television , he was under the impression that they too had been subjugated to this... sleeping , al-Libi, al-Zawi and `Abd al-Karim managed to escape by jumping from the six-meter-tall wall of al-Ruways.38 Their breakout led to a

  3. Laser Doppler anemometer measurements using nonorthogonal velocity components: error estimates.

    Science.gov (United States)

    Orloff, K L; Snyder, P K

    1982-01-15

    Laser Doppler anemometers (LDAs) that are arranged to measure nonorthogonal velocity components (from which orthogonal components are computed through transformation equations) are more susceptible to calibration and sampling errors than are systems with uncoupled channels. In this paper uncertainty methods and estimation theory are used to evaluate, respectively, the systematic and statistical errors that are present when such devices are applied to the measurement of mean velocities in turbulent flows. Statistical errors are estimated for two-channel LDA data that are either correlated or uncorrelated. For uncorrelated data the directional uncertainty of the measured velocity vector is considered for applications where mean streamline patterns are desired.

  4. Frequency modulation via the Doppler effect in optical fibers.

    Science.gov (United States)

    Oberson, P; Huttner, B; Gisin, N

    1999-04-01

    We present the principle of optical frequency modulation via the Doppler effect obtained by rapidly stretching an optical fiber and thus modifying the optical path of the light propagating in the fiber. This procedure creates a pure frequency shift, with no degradation of the spectrum. Moreover, the effect is wavelength independent and can therefore be applied to any type of light source. We show an experimental realization in which a frequency excursion of ~100 MHz was obtained with a bobbin vibrating at 180 Hz.

  5. Geometric doppler effect: spin-split dispersion of thermal radiation.

    Science.gov (United States)

    Dahan, Nir; Gorodetski, Yuri; Frischwasser, Kobi; Kleiner, Vladimir; Hasman, Erez

    2010-09-24

    A geometric Doppler effect manifested by a spin-split dispersion relation of thermal radiation is observed. A spin-dependent dispersion splitting was obtained in a structure consisting of a coupled thermal antenna array. The effect is due to a spin-orbit interaction resulting from the dynamics of the surface waves propagating along the structure whose local anisotropy axis is rotated in space. The observation of the spin-symmetry breaking in thermal radiation may be utilized for manipulation of spontaneous or stimulated emission.

  6. CO2 measurements during transcranial Doppler examinations in headache patients

    DEFF Research Database (Denmark)

    Thomsen, L L; Iversen, Helle Klingenberg

    1994-01-01

    Transcranial Doppler (TCD) examinations are increasingly being used in studies of headache pathophysiology. Because blood velocity is highly dependent on PCO2, these parameters should be measured simultaneously. The most common way of performing measurements during TCD examinations is as end......-tidal pCO2 with a capnograph. When patients are nauseated and vomit, as in migraine, the mask or mouthpiece connected to the capnograph represents a problem. We therefore evaluated whether a transcutaneous pCO2 electrode was as useful as the capnograph for pCO2 measurements in TCD examinations. We...

  7. Fiber optic laser Doppler anemometry in swirling jets

    Science.gov (United States)

    Taghavi, R.; Rice, E. J.

    1991-01-01

    Time-averaged and fluctuating quantities are measured in a free turbulent swirling jet. Data from a two-component laser Doppler anemometry (LDA) are compared to the measurements via hot-wire and 5-hole pitot probes. To acquire the proper seeding density near the axis of a swirling jet for LDA measurements proved difficult. This is due to an imbalance of the centrifugal force and radial pressure gradient, which throws the seeding material off the axis. Despite this problem, close agreement between various measurement techniques is obtained.

  8. Synchrosqueezing an effective method for analyzing Doppler radar physiological signals.

    Science.gov (United States)

    Yavari, Ehsan; Rahman, Ashikur; Jia Xu; Mandic, Danilo P; Boric-Lubecke, Olga

    2016-08-01

    Doppler radar can monitor vital sign wirelessly. Respiratory and heart rate have time-varying behavior. Capturing the rate variability provides crucial physiological information. However, the common time-frequency methods fail to detect key information. We investigate Synchrosqueezing method to extract oscillatory components of the signal with time varying spectrum. Simulation and experimental result shows the potential of the proposed method for analyzing signals with complex time-frequency behavior like physiological signals. Respiration and heart signals and their components are extracted with higher resolution and without any pre-filtering and signal conditioning.

  9. SIRHEN : a data reduction program for photonic Doppler velocimetry measurements.

    Energy Technology Data Exchange (ETDEWEB)

    Dolan, Daniel H., III; Ao, Tommy

    2010-06-01

    SIRHEN (Sandia InfraRed HEtrodyne aNalysis) is a program for reducing data from photonic Doppler velocimetry (PDV) measurements. SIRHEN uses the short-time Fourier transform method to extract velocity information. The program can be run in MATLAB (2008b or later) or as a Windows executable. This report describes the new Sandia InfraRed HEtrodyne aNalysis program (SIRHEN; pronounced 'siren') that has been developed for efficient and robust analysis of PDV data. The program was designed for easy use within Sandia's dynamic compression community.

  10. Transcranial Doppler: Techniques and advanced applications: Part 2

    Directory of Open Access Journals (Sweden)

    Arvind K Sharma

    2016-01-01

    Full Text Available Transcranial Doppler (TCD is the only diagnostic tool that can provide continuous information about cerebral hemodynamics in real time and over extended periods. In the previous paper (Part 1, we have already presented the basic ultrasound physics pertaining to TCD, insonation methods, and various flow patterns. This article describes various advanced applications of TCD such as detection of right-to-left shunt, emboli monitoring, vasomotor reactivity (VMR, monitoring of vasospasm in subarachnoid hemorrhage (SAH, monitoring of intracranial pressure, its role in stoke prevention in sickle cell disease, and as a supplementary test for confirmation of brain death.

  11. Doppler Compensation by using of Segmented Match Filter

    OpenAIRE

    2008-01-01

    Match filter is one of the important parts of radar receiver. By using of Match Filter, the signal to noise ratio can be maximized so that the probability of detection is increased. Match Filter can be used as a pulse compression filter in radar receiver. Binary phase code is one of the pulse compression methods that, the compression can be down with a Match Filter in the receiver. Doppler effect is one of the problems that degrade the performance of Match Filter. In this paper, two methods “...

  12. Holographic laser Doppler imaging of pulsatile blood flow

    CERN Document Server

    Bencteux, Jeffrey; Kostas, Thomas; Bayat, Sam; Atlan, Michael

    2015-01-01

    We report on wide-field imaging of pulsatile motion induced by blood flow using heterodyne holographic interferometry on the thumb of a healthy volunteer, in real-time. Optical Doppler images were measured with green laser light by a frequency-shifted Mach-Zehnder interferometer in off-axis configuration. The recorded optical signal was linked to local instantaneous out-of-plane motion of the skin at velocities of a few hundreds of microns per second, and compared to blood pulse monitored by plethysmoraphy during an occlusion-reperfusion experiment.

  13. Rayleigh Doppler Lidar for Higher Tropospheric and Stratospheric Wind Observation

    Institute of Scientific and Technical Information of China (English)

    TANG Lei; WANG Cong-Rong; WU Hai-Bin; DONG Ji-Hui

    2012-01-01

    A mobile molecular Doppler wind lidar (DWL) based on the double-edge technique is described for wind measurement from 10 km to 40 km altitude.Two edge filters located in the wings of the thermally broadened molecular backscattered signal spectrum at 355 nm are employed as a frequency discriminator to determine the Doppler shift proportional to the wind velocity.The lidar operates at 355 nm with a 45 cm aperture telescope and a matching azimuth-over-elevation scanner that can provide full hemispherical pointing.Intercomparison experiments of the lidar wind profile measurement are performed with collocated pilot balloon.The results show that the standard deviation of wind speed and direction are less than l0m/s and 30° in the 5-40 km altitude range,respectively.The small mean difference and normal distribution between DWL and pilot balloon data and the transient eddy of the west-wind jet observed demonstrate that the DWL consistently measures the wind with acceptable random errors.%A mobile molecular Doppler wind lidar (DWL) based on the double-edge technique is described for wind measurement from 10 km to 40 km altitude. Two edge filters located in the wings of the thermally broadened molecular backscattered signal spectrum at 355 nm are employed as a frequency discriminator to determine the Doppler shift proportional to the wind velocity. The lidar operates at 355 nm with a 45 cm aperture telescope and a matching azimuth-over-elevation scanner that can provide full hemispherical pointing. Intercomparison experiments of the lidar wind profile measurement are performed with collocated pilot balloon. The results show that the standard deviation of wind speed and direction are less than 10m/s and 30° in the 5-40 km altitude range, respectively. The small mean difference and normal distribution between DWL and pilot balloon data and the transient eddy of the west-wind jet observed demonstrate that the DWL consistently measures the wind with acceptable random errors.

  14. Microembolus Detection by Transcranial Doppler Sonography: Review of the Literature

    Directory of Open Access Journals (Sweden)

    Vlasta Vuković-Cvetković

    2012-01-01

    Full Text Available Transcranial Doppler can detect microembolic signals which are characterized by unidirectional high intensity increase, short duration, random occurrence, and a “whistling” sound. Microembolic signals have been detected in a number of clinical settings: carotid artery stenosis, aortic arch plaques, atrial fibrillation, myocardial infarction, prosthetic heart valves, patent foramen ovale, valvular stenosis, during invasive procedures (angiography, percutaneous transluminal angioplasty, surgery (carotid, cardiopulmonary bypass, orthopedic, and in certain systemic diseases. Microembolic signals are frequent in large artery disease, less commonly detected in cardioembolic stroke, and infrequent in lacunar stroke. This article provides an overview about the current state of technical and clinical aspects of microembolus detection.

  15. Incoherent pulse Doppler lidar as the velocimeter system

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    This note reports a new type of incoherent pulse laser Doppler lidar velocimeter with iodine molecular filter as a frequency discriminator. Its transmitter subsystem applies a Nd:YAG pulse laser which is injected with a single longitudinal-mode diode pumped continuous seeder laser.The field experiment proved that this velocimeter measurement results are consistent with those measured by photoelectric velocimeter. Measurements of eight different velocities show that the standard deviation is 0.56 m/s, the range resolution is 3.75 m.

  16. Cardiac Time Intervals by Tissue Doppler Imaging M-Mode

    DEFF Research Database (Denmark)

    Biering-Sørensen, Tor; Mogelvang, Rasmus; de Knegt, Martina Chantal;

    2016-01-01

    PURPOSE: To define normal values of the cardiac time intervals obtained by tissue Doppler imaging (TDI) M-mode through the mitral valve (MV). Furthermore, to evaluate the association of the myocardial performance index (MPI) obtained by TDI M-mode (MPITDI) and the conventional method of obtaining...... MPI (MPIConv), with established echocardiographic and invasive measures of systolic and diastolic function. METHODS: In a large community based population study (n = 974), where all are free of any cardiovascular disease and cardiovascular risk factors, cardiac time intervals, including isovolumic...... the MPITDI and MPIConv measured. RESULTS: IVRT, IVRT/ET and MPI all increased significantly with increasing age in both genders (pcardiac function. MPITDI...

  17. Implementation of directional Doppler techniques using a digital signal processor.

    Science.gov (United States)

    Aydin, N; Evans, D H

    1994-07-01

    Three methods of deriving directional signals from phase quadrature Doppler signals, using digital techniques, are described. These are the phasing-filter technique, the Weaver receiver technique and the complex FFT. The basic theory behind the three methods is presented, together with the results of digital simulations. Each of the methods has been implemented in real time using a commercially available digital signal-processing board, and their relative processing times are compared. All the methods work well, and the decision to implement one or other in a specific application is likely to rest on secondary factors, such as the need to tape-record the time domain output.

  18. Corruption of radio metric Doppler due to solar plasma dynamics: S/X dual-frequency Doppler calibration for these effects

    Science.gov (United States)

    Winn, F. B.; Reinbold, S. R.; Yip, K. W.; Koch, R. E.; Lubeley, A.

    1975-01-01

    Doppler data from Mariner 6, 7, 9, and 10 and Pioneer 10 and 11 were discussed and the rms noise level for various sun-earth-probe angles were shown. The noise levels of both S- and X-band Doppler data for sun-earth-probe angles smaller than 20 deg were observed to be orders of magnitude greater than nominal. Such solar plasma-related Doppler degradation reduced the Mariner 10-Mercury 11 encounter navigation accuracy by nearly a factor of 10. Furthermore, this degradation was shown to be indirectly related to plasma dynamics and not a direct measure of the dynamics.

  19. Validation of the severity index by cardiac catheterization and Doppler echocardiography in patients with aortic sclerosis and stenosis

    Directory of Open Access Journals (Sweden)

    Rosales Joseph

    2006-03-01

    Full Text Available Abstract The severity index is a new echocardiographic measure that is thought to be an accurate indicator of aortic leaflet pathology in patients with AS. However, it has not been validated against cardiac catheterization or Doppler echocardiographic measures of AS severity nor has it been applied to patients with aortic sclerosis. The purposes of this study were to compare the severity index to invasive hemodynamics and Doppler echocardiography across the spectrum of calcific aortic valve disease, including aortic sclerosis and AS. 48 patients with aortic sclerosis and AS undergoing echocardiography and cardiac catheterization comprised the study population. The aortic valve leaflets were assessed for mobility (scale 1 to 6 and calcification (scale 1 to 4 and the severity index was calculated as the sum of the mobility and calcification scores according to the methods of Bahler et al. The severity index increased with increasing severity of aortic valve disease; the severity indices for patients with aortic sclerosis, mild to moderate AS and severe AS were 3.38 ± 1.06, 6.45 ± 2.16 and 8.38 ± 1.41, respectively. The aortic jet velocity by echocardiography and the square root of the maximum aortic valve gradient by cardiac catheterization correlated well with the severity index (r = 0.84, p

  20. Acute effects of lateral thigh foam rolling on arterial tissue perfusion determined by spectral Doppler and Power Doppler ultrasound.

    Science.gov (United States)

    T, Hotfiel; B, Swoboda; S, Krinner; C, Grim; M, Engelhardt; M, Uder; R, Hei

    2016-09-23

    Foam rolling has been developed as a popular intervention in training and rehabilitation. However, evidence on its effects on the cellular and physiological level is lacking. The aim of this study was to assess the effect of foam rolling on arterial blood flow of the lateral thigh. Twenty-one healthy participants (age 25 ± 2 years, height 177 ± 9 cm, body weight 74 ± 9 kg) were recruited from the medical and sports faculty. Arterial tissue perfusion was determined by spectral Doppler and power Doppler ultrasound, represented as peak flow (Vmax), time average velocity maximum (TAMx), time average velocity mean (TAMn), and resistive index (RI), and with semiquantitative grading that was assessed by four blind-folded investigators. Measurement values were assessed under resting conditions and twice after foam rolling exercises of the lateral thigh (0 min and 30 min post intervention). The trochanteric region, mid portion, and distal tibial insertion of the lateral thigh were representative for data analysis. Arterial blood flow of the lateral thigh increased significantly following foam rolling exercises compared to baseline (p<0.05). We detected a relative increase in Vmax of 73.6% (0 min) and 52.7 % (30 min) (p<0.001), in TAMx of 53.2% (p<0.001) and 38.3 % (p=0.002), and in TAMn of 84.4% (p<0.001) and 68.2 % (p<0.001). Semiquantitative Power Doppler scores at all portions revealed increased average grading of 1.96 after intervention and 2.04 after 30 min compared to 0.75 at baseline. Our results may contribute to the understanding of local physiological reactions to self-myofascial release.

  1. Characteristics of ionospheric plasma drifts as obtained from Doppler ionosonde measurements at magnetic equator over Indian sector

    Science.gov (United States)

    Samireddipalle, Sripathi; Banola, Sridhar; Singh, Ram

    2016-07-01

    We present equatorial plasma drifts over Tirunelveli (8.73°N, 77.70°E; Dip 0.5°N), an equatorial site over Indian region using Doppler interferometry technique of Canadian Advanced Digital Ionosonde (CADI) system. In the Doppler interferometry technique, it is possible to infer three dimensional bulk motion of the scatterers as reflected from the ionosphere at selected frequencies using spaced receivers arranged in mag. east-west, north-south directions. Spectral phases and amplitudes are calculated using FFT to identify the Doppler frequencies and their drifts. This technique produces reliable drifts when sharp refractive index gradients exists which produces higher scattering sources. The vertical drifts so obtained are compared with same drifts from Digisonde at Trivandrum. After having compared with Digisonde drifts, we studied the temporal and seasonal variability of these drifts during quiet periods for the year 2012. It is seen that vertical drifts exhibited equinoctial maximum in the Pre-Reversal-Enhancement (PRE) followed by winter and summer respectively. A comparison of these vertical drifts is made with drifts obtained from (a) virtual height measured at 4 MHz and (b) Fejer drift model. The comparison suggests that Doppler vertical drifts are relatively higher as compared to the drifts obtained from model and virtual height. However, the correlation seems to be good around evening PRE times. The zonal drifts, on the other hand, showed westward drifts during daytime with mean drifts of ~250 m/s, while they are eastward during nighttime with mean drifts of ~150 m/s. These drifts seems to be higher as compared to zonal drifts obtained in the South American sector. However, the zonal drifts so obtained showed good correlation with Equatorial Electrojet (EEJ) strength suggesting zonal drifts are influenced by E region drifts during daytime in agreement with Woodman et al., 2013 paper. The magnitude of these drifts are comparable to other independent

  2. Multiplexed photonic Doppler velocimetry for large channel count experiments

    Science.gov (United States)

    Daykin, Edward; Burk, Martin; Holtkamp, David; Miller, Edward Kirk; Rutkowski, Araceli; Strand, Oliver Ted; Pena, Michael; Perez, Carlos; Gallegos, Cenobio

    2017-01-01

    Photonic Doppler Velocimetry (PDV) is routinely employed as a means of measuring surface velocities for shockwave experimentation. Scientists typically collect ˜4 to 12 channels of PDV data and use extrapolation, assumptions, and models to determine the velocities in regions of the experiment that were not observed directly. We have designed, built and applied a new optical velocimetry diagnostic—the Multiplexed Photonic Doppler Velocimeter (MPDV)—for use on shock physics experiments that require a large number (100s) of spatial points to be measured. MPDV expands upon PDV measurement capabilities via frequency and time multiplexing using commercially available products developed for the telecommunications industry. The MPDV uses the heterodyne method to multiplex four data channels in the frequency domain combined with fiber delays to multiplex an additional four-channel dataset in the time domain, all of which are recorded onto the same digitizer input. This means that each digitizer input records data from eight separate spatial points, so that a single 4-input digitizer may record a total of 32 channels of data. Motivation for development of a multiplexed PDV was driven by requirements for an economical, high-fidelity, high channel-count optical velocimetry system. We present a survey of the methods, components, and trade-offs incorporated into this recent development in optical velocimetry.

  3. Conventional and Doppler ultrasonography on a goat with gangrenous mastitis

    Directory of Open Access Journals (Sweden)

    V.J.C. Santos

    2014-12-01

    Full Text Available Objetivou-se descrever os achados clínicos e ultrassonográficos de uma cabra leiteira apresentando mastite gangrenosa. Com a ultrassonografia convencional, observaram-se alterações consistentes com o avanço do quadro clínico, como alterações na ecogenicidade do leite e parênquima mamário. A ultrassonografia Doppler revelou aumento da velocidade de pico sistólico nos três momentos estudados, passando de 15 para 17 e 29cm/s. Houve redução, também, dos valores do índice de resistência, de 0,71 para 0,61 e 0,43. O índice de pulsatividade sofreu redução entre o segundo e o terceiro dia de observação, passando de 0,98 para 0,71. Foi possível estabelecer relação direta entre os achados ultrassonográficos e a gravidade da doença. A ultrassonografia convencional e Doppler podem ser utilizadas para o estudo hemodinâmico do úbere de cabras leiteiras, favorecendo diagnóstico e prognóstico de alterações nesse órgão.

  4. Color Doppler Ultrasonographic Features of Hashimoto's Thyroiditis

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Joo Hyuk; Kim, Mie Young; Rho, Eun Jin; Yi, Jeong Geun; Han, Chun Hwan [Kangnam General Hospital Public Corporation, Seoul (Korea, Republic of); Hwang, Hee Yong [Choong Ang Gil Hospital, Incheon (Korea, Republic of)

    1995-06-15

    Color Doppler ultrasonographic(US) features of 28 patients with Hashimato's thyroiditis were evaluated with regard to echo and color-flow patterns. Correlation of color-flow pattern with thyroid function was performed. All 28 patients showed varying degrees of diffuse enlargement of the thyroid gland and a heterogeneous echo pattern.Color-flow pattern of increased blood flow. Low to moderate, focally increased blood flow was seen in 26 patients(92.8%). Of these 26 patients, 24 patients showed subclinical hypothyroidism or euthyroidism. Two patients who showed hyperthyroidism showed several pieces of focally increased color flow, Which was noted during both systole and diastole. Diffuse, multifocal color-flow throughout thyroid gland was seen in two patients with Hashimato's thyroiditis: one with clinical hypothyroidism and the other with subclinical hypothyroidism. Even though Hashimoto's thyroiditis showed variable color-flow patterns, we believe that heterogenous parenchymal echopattern with low or moderately increased flow is a rather characteristic feature of Hashimoto's thyroiditis, and we suggest that color Doppler US provides additional information for evaluation of Hashimoto's thyroiditis

  5. The first Doppler images of the eclipsing binary SZ Piscium

    Science.gov (United States)

    Xiang, Yue; Gu, Shenghong; Cameron, A. Collier; Barnes, J. R.; Zhang, Liyun

    2016-02-01

    We present the first Doppler images of the active eclipsing binary system SZ Psc, based on the high-resolution spectral data sets obtained in 2004 November and 2006 September-December. The least-squares deconvolution technique was applied to derive high signal-to-noise profiles from the observed spectra of SZ Psc. Absorption features contributed by a third component of the system were detected in the LSD profiles at all observed phases. We estimated the mass and period of the third component to be about 0.9 M⊙ and 1283 ± 10 d, respectively. After removing the contribution of the third body from the least-squares deconvolved profiles, we derived the surface maps of SZ Psc. The resulting Doppler images indicate significant star-spot activities on the surface of the K subgiant component. The distributions of star-spots are more complex than that revealed by previous photometric studies. The cooler K component exhibited pronounced high-latitude spots as well as numerous low- and intermediate-latitude spot groups during the entire observing seasons, but did not show any large, stable polar cap, different from many other active RS CVn-type binaries.

  6. On the Doppler effect for photons in rotating systems

    CERN Document Server

    Giuliani, Giuseppe

    2015-01-01

    The analysis of the Doppler effect for photons in rotating systems, studied using the M\\"ossbauer effect, confirms the general conclusions of a previous paper dedicated to experiments with photons emitted/absorbed by atoms/nuclei in inertial flight. The wave theory of light is so deeply rooted that it has been--and currently is--applied to describe phenomena in which the fundamental entities at work are discrete (photons). The fact that the wave theory of light can describe one aspect of these phenomena can not overshadow two issues: the corpuscular theory of light, firstly applied to the Doppler effect for photons by Schr\\"odinger in 1922, is by far more complete since it describes all the features of the studied phenomena; the wave theory can be used only when the number of photons at work is statistically significant. The disregard of basic methodological criteria may appear as a minor fault. However, the historical development of quantum physics shows that the predominance of the wave theory of radiation,...

  7. Modeling of Doppler frequency shift in multipath radiochannels

    Science.gov (United States)

    Penzin, Maksim; Iyin, Nikolay

    2016-06-01

    We discuss the modeling of propagation of a quasi-monochromatic radio signal, represented by a coherent pulse sequence, in a non-stationary multipath radio channel. In such a channel, signal propagation results in the observed frequency shift for each ray (Doppler effect). The modeling is based on the assumption that during propagation of a single pulse a channel can be considered stationary. A phase change in the channel transfer function is shown to cause the observed frequency shift in the received signal. Thus, instead of measuring the Doppler frequency shift, we can measure the rate of change in the mean phase of one pulse relative to another. The modeling is carried out within the framework of the method of normal waves. The method enables us to model the dynamics of the electromagnetic field at a given point with the required accuracy. The modeling reveals that a local change in ionospheric conditions more severely affects the rays whose reflection region is in the area where the changes occur.

  8. Users Guide to the JPL Doppler Gravity Database

    Science.gov (United States)

    Muller, P. M.; Sjogren, W. L.

    1986-01-01

    Local gravity accelerations and gravimetry have been determined directly from spacecraft Doppler tracking data near the Moon and various planets by the Jet Propulsion Laboratory. Researchers in many fields have an interest in planet-wide global gravimetric mapping and its applications. Many of them use their own computers in support of their studies and would benefit from being able to directly manipulate these gravity data for inclusion in their own modeling computations. Pubication of some 150 Apollo 15 subsatellite low-altitude, high-resolution, single-orbit data sets is covered. The doppler residuals with a determination of the derivative function providing line-of-sight-gravity are both listed and plotted (on microfilm), and can be ordered in computer readable forms (tape and floppy disk). The form and format of this database as well as the methods of data reduction are explained and referenced. A skeleton computer program is provided which can be modified to support re-reductions and re-formatted presentations suitable to a wide variety of research needs undertaken on mainframe or PC class microcomputers.

  9. Doppler radar sensor positioning in a fall detection system.

    Science.gov (United States)

    Liu, Liang; Popescu, Mihail; Ho, K C; Skubic, Marjorie; Rantz, Marilyn

    2012-01-01

    Falling is a common health problem for more than a third of the United States population over 65. We are currently developing a Doppler radar based fall detection system that already has showed promising results. In this paper, we study the sensor positioning in the environment with respect to the subject. We investigate three sensor positions, floor, wall and ceiling of the room, in two experimental configurations. Within each system configuration, subjects performed falls towards or across the radar sensors. We collected 90 falls and 341 non falls for the first configuration and 126 falls and 817 non falls for the second one. Radar signature classification was performed using a SVM classifier. Fall detection performance was evaluated using the area under the ROC curves (AUCs) for each sensor deployment. We found that a fall is more likely to be detected if the subject is falling toward or away from the sensor and a ceiling Doppler radar is more reliable for fall detection than a wall mounted one.

  10. Study on characteristics of chirp about Doppler wind lidar system

    Science.gov (United States)

    Du, Li-fang; Yang, Guo-tao; Wang, Ji-hong; Yue, Chuan; Chen, Lin-xiang

    2016-11-01

    In the doppler wind lidar, usually every 4MHz frequency error will produce wind error of 1m/s of 532nm laser. In the Doppler lidar system, frequency stabilization was achieved through absorption of iodine molecules. Commands that control the instrumental system were based on the PID algorithm and coded using VB language. The frequency of the seed laser was locked to iodine molecular absorption line 1109 which is close to the upper edge of the absorption range, with long-time (>4h) frequency-locking accuracy being≤0.5MHz and long-time frequency stability being 10-9 . The experimental result indicated that the seed frequency and the pulse laser frequency have a deviation, which effect is called the laser chirp characteristics. Finally chirp test system was constructed and tested the frequency offset in time. And such frequency deviation is known as Chirp of the laser pulse. The real-time measured frequency difference of the continuous and pulsed lights was about 10MHz, long-time stability deviation was around 5MHz. After experimental testing technology mature, which can monitoring the signal at long-term with corrected the wind speed.

  11. Intrinsic physical properties and Doppler boosting effects in LSI+61303

    CERN Document Server

    Massi, M

    2014-01-01

    Our aim is to show how variable Doppler boosting of an intrinsically variable jet can explain the long-term modulation of 1667 \\pm 8 days observed in the radio emission of LSI+61303. The physical scenario is that of a conical, magnetized plasma jet having a periodical (P1) increase of relativistic particles, Nrel, at a specific orbital phase, as predicted by accretion in the eccentric orbit of LSI+61303. Jet precession (P2) changes the angle, eta, between jet axis and line of sight, thereby inducing variable Doppler boosting. The problem is defined in spherical geometry, and the optical depth through the precessing jet is calculated by taking into account that the plasma is stratified along the jet axis. The synchrotron emission of such a jet was calculated and we fitted the resulting flux density Smodel(t) to the observed flux density obtained during a 6.5-year monitoring of LSI+61303 by the Green Bank radio interferometer. Our physical model for the system LSI+61303 is not only able to reproduce the long-te...

  12. Fabrication of Two Flow Phantoms for Doppler Ultrasound Imaging.

    Science.gov (United States)

    Zhou, Xiaowei; Kenwright, David A; Wang, Shiying; Hossack, John A; Hoskins, Peter R

    2017-01-01

    Flow phantoms are widely used in studies associated with Doppler ultrasound measurements, acting as an effective experimental validation system in cardiovascular-related research and in new algorithm/instrumentation development. The development of materials that match the acoustic and mechanical properties of the vascular system is of great interest while designing flow phantoms. Although recipes that meet the flow phantom standard defined by the International Electrotechnical Commission 61685 are already available in the literature, the standard procedure for material preparations and phantom fabrications has not been well established. In this paper, two types of flow phantoms, with and without blood vessel mimic, are described in detail in terms of the material preparation and phantom fabrication. The phantom materials chosen for the two phantoms are from published phantom studies, and their physical properties have been investigated previously. Both the flow phantoms have been scanned by ultrasound scanners and images from different modes are presented. These phantoms may be used in the validation and characterization of Doppler ultrasound measurements in blood vessels with a diameter above 1 mm.

  13. Detection of Doppler Microembolic Signals Using High Order Statistics

    Directory of Open Access Journals (Sweden)

    Maroun Geryes

    2016-01-01

    Full Text Available Robust detection of the smallest circulating cerebral microemboli is an efficient way of preventing strokes, which is second cause of mortality worldwide. Transcranial Doppler ultrasound is widely considered the most convenient system for the detection of microemboli. The most common standard detection is achieved through the Doppler energy signal and depends on an empirically set constant threshold. On the other hand, in the past few years, higher order statistics have been an extensive field of research as they represent descriptive statistics that can be used to detect signal outliers. In this study, we propose new types of microembolic detectors based on the windowed calculation of the third moment skewness and fourth moment kurtosis of the energy signal. During energy embolus-free periods the distribution of the energy is not altered and the skewness and kurtosis signals do not exhibit any peak values. In the presence of emboli, the energy distribution is distorted and the skewness and kurtosis signals exhibit peaks, corresponding to the latter emboli. Applied on real signals, the detection of microemboli through the skewness and kurtosis signals outperformed the detection through standard methods. The sensitivities and specificities reached 78% and 91% and 80% and 90% for the skewness and kurtosis detectors, respectively.

  14. Magnetic Doppler imaging of the chemically peculiar star HD 125248

    CERN Document Server

    Rusomarov, N; Ryabchikova, T; Ilyin, I

    2016-01-01

    Intermediate-mass, chemically peculiar stars with strong magnetic fields give us an excellent opportunity to study the topology of their surface magnetic fields and the interplay between magnetic geometries and abundance inhomogeneities in their atmospheres. We reconstruct detailed maps of the surface magnetic field and abundance distributions for the magnetic Ap star HD 125248. We performed the analysis based on phase-resolved, four Stokes parameter spectropolarimetric observations obtained with the HARPSpol instrument. These data were interpreted with the magnetic Doppler imaging technique. We improved the atmospheric parameters of the star, T_eff = 9850K +/- 250K and logg = 4.05 +/- 0.10. We performed detailed abundance analysis and discovered vertical stratification effects for the FeII and CrII ions. We computed LSD Stokes profiles and studied their behavior with rotational phase. We improved the rotational period of the star P_rot = 9.29558(6)d. Magnetic Doppler imaging of HD 125248 showed that its magn...

  15. The first Doppler images of the eclipsing binary SZ Piscium

    CERN Document Server

    Xiang, Yue; Cameron, A Collier; Barnes, J R; Zhang, Liyun

    2015-01-01

    We present the first Doppler images of the active eclipsing binary system SZ Psc, based on the high-resolution spectral data sets obtained in 2004 November and 2006 September--December. The least-squares deconvolution technique was applied to derive high signal-to-noise profiles from the observed spectra of SZ Psc. Absorption features contributed by a third component of the system were detected in the LSD profiles at all observed phases. We estimated the mass and period of the third component to be about $0.9 M_{\\odot}$ and $1283 \\pm 10$ d, respectively. After removing the contribution of the third body from the LSD profiles, we derived the surface maps of SZ Psc. The resulting Doppler images indicate significant starspot activities on the surface of the K subgiant component. The distributions of starspots are more complex than that revealed by previous photometric studies. The cooler K component exhibited pronounced high-latitude spots as well as numerous low- and intermediate-latitude spot groups during the...

  16. An acoustic spanner and its associated rotational Doppler shift

    Energy Technology Data Exchange (ETDEWEB)

    Skeldon, K D; Wilson, C; Edgar, M; Padgett, M J [Department of Physics and Astronomy, University of Glasgow, Glasgow (United Kingdom)

    2008-01-15

    Light carries a spin angular momentum associated with its polarization and an orbital angular momentum arising from its phase cross-section. Sound, being a longitudinal wave, carries no spin component but can carry an orbital component of angular momentum when endowed with an appropriate phase structure. Here, we use a circular array of loudspeakers driven at a common angular frequency {omega}{sub s} but with an azimuthally changing phase delay to create a sound wave with helical phase fronts described by exp (il{theta}). Such waves are predicted to have an orbital angular momentum to energy ratio of l/{omega}{sub s}. We confirm this angular momentum content by measuring its transfer to a suspended 60 cm diameter acoustic absorbing tile. The resulting torque on the tile ({approx}6.1x10{sup -6} Nm) is measured from observation of the motion for various torsional pendulums. Furthermore, we confirm the helical nature of the acoustic beam by observing the rotational Doppler shift, which results from a rotation between source and observer of angular velocity {omega}{sub r}. We measure Doppler shifted frequencies of {omega}{sub s}{+-}l{omega}{sub r} depending on the direction of relative rotation.

  17. Mucosal blood flow measurements using laser Doppler perfusion monitoring

    Institute of Scientific and Technical Information of China (English)

    Dag Arne Lihaug Hoff; Hans Gregersen; Jan Gunnar Hatlebakk

    2009-01-01

    Perfusion of individual tissues is a basic physiological process that is necessary to sustain oxygenation and nutrition at a cellular level. Ischemia, or the insufficiency of perfusion, is a common mechanism for tissue death or degeneration, and at a lower threshold, a mechanism for the generation of sensory signalling including pain. It is of considerable interest to study perfusion of peripheral abdominal tissues in a variety of circumstances. Microvascular disease of the abdominal organs has been implicated in the pathogenesis of a variety of disorders, including peptic ulcer disease, inflammatory bowel disease and chest pain. The basic principle of laser Doppler perfusion monitoring (LDPM) is to analyze changes in the spectrum of light reflected from tissues as a response to a beam of monochromatic laser light emitted. It reflects the total local microcirculatory blood perfusion, including perfusion in capillaries, arterioles, venules and shunts. During the last 20-25 years, numerous studies have been performed in different parts of the gastrointestinal (GI) tract using LDPM. In recent years we have developed a multi-modal catheter device which includes a laser Doppler probe, with the intent primarily to investigate patients suffering from functional chest pain of presumed oesophageal origin. Preliminary studies show the feasibility of incorporating LDPM into such catheters for performing physiological studies in the GI tract. LDPM has emerged as a research and clinical tool in preference to other methods; but, it is important to be aware of its limitations and account for them when reporting results.

  18. The Huygens Doppler Wind Experiment: Results from Titan

    Science.gov (United States)

    Folkner, W. M.; Bird, M. K.; Dutta-Roy, R.; Allison, M.; Asmar, S. W.; Atkinson, D. H.; Edenhofer, P.; Plettemeier, D.; Tyler, L. H.; Preston, R. A.; Gurvits, L.

    2005-05-01

    The ESA Huygens Probe entered and descended for nearly 2.5 hours through the atmosphere of Titan on 14 January 2005. Huygens survived impact on the surface and continued its telemetry broadcast to the NASA Cassini spacecraft on two separate radio links, denoted Channels A and B, respectively, for an additional 1.2 hours. The instrumentation for the Huygens Doppler Wind Experiment (DWE) consisting of two Ultra-Stable Oscillators in the transmitter (TUSO) and receiver (RUSO), were implemented only in Channel A. Whereas Channel B functioned flawlessly during the entire mission, the receiver for Channel A was never able to lock onto the Huygens signal because the DWE-RUSO had not been properly programmed into the critical probe radio relay sequence. All data on Channel A, including the DWE measurements and probe telemetry, were thus lost. In spite of this setback, the Channel A signal was successfully received at many radio telescopes on Earth. The precision of these Doppler measurements, considered as an aggregate, is roughly equivalent to that which had been foreseen from the measurements on board Cassini. We present an overview of the DWE ground-based observations and the Titan wind profile derived from them.

  19. Transcranial Doppler ultrasonography: From methodology to major clinical applications

    Institute of Scientific and Technical Information of China (English)

    Antonello D’Andrea; Marianna Conte; Massimo Cavallaro; Raffaella Scarafile; Lucia Riegler; Rosangela Cocchia; Enrica Pezzullo; Andreina Carbone; Francesco Natale; Giuseppe Santoro; Pio Caso; Maria Giovanna Russo; Eduardo Bossone; Raffaele Calabrò

    2016-01-01

    Non-invasive Doppler ultrasonographic study of cerebral arteries [transcranial Doppler(TCD)] has been extensively applied on both outpatient and inpatient settings. It is performed placing a low-frequency(≤ 2 MHz) transducer on the scalp of the patient over specific acoustic windows, in order to visualize the intracranial arterial vessels and to evaluate the cerebral blood flow velocity and its alteration in many different conditions. Nowadays the most widespread indication for TCD in outpatient setting is the research of right to left shunting, responsable of so called "paradoxical embolism", most often due to patency of foramen ovale which is responsable of the majority of cryptogenic strokes occuring in patients younger than 55 years old. TCD also allows to classify the grade of severity of such shunts using the so called "microembolic signal grading score". In addition TCD has found many useful applications in neurocritical care practice. It is useful on both adults and children for day-to-day bedside assessment of critical conditions including vasospasm in subarachnoidal haemorrhage(caused by aneurysm rupture or traumatic injury), traumatic brain injury, brain stem death. It is used also to evaluate cerebral hemodynamic changes after stroke. It also allows to investigate cerebral pressure autoregulation and for the clinical evaluation of cerebral autoregulatory reserve.

  20. Color-flow Doppler sonography in Graves disease: "thyroid inferno".

    Science.gov (United States)

    Ralls, P W; Mayekawa, D S; Lee, K P; Colletti, P M; Radin, D R; Boswell, W D; Halls, J M

    1988-04-01

    Graves disease is a common diffuse abnormality of the thyroid gland usually characterized by thyrotoxicosis. We performed color-flow Doppler sonography in 16 patients with Graves disease and compared the results with those in 15 normal volunteers and 14 patients with other thyroid diseases (eight with multinodular goiter, four with focal masses, and two with papillary thyroid carcinoma). All 16 Graves disease patients exhibited a pulsatile pattern we call "thyroid inferno." This pattern consists of multiple small areas of intrathyroidal flow seen diffusely throughout the gland in both systole and diastole. In systole, both high-velocity flow (color coded white) and lower velocity flow (color coded red and blue) were noted. In diastole, fewer areas of flow and lower velocity flow were noted. Patients with Graves disease also exhibited color flow around the periphery of the gland. The inferno pattern did not occur in normal subjects or in patients with other thyroid diseases. On occasion, focal areas of intrathyroidal flow were detected in patients with multinodular goiter and focal thyroid masses. High-resolution gray-scale images did not show the small vascular channels from which the flow signal originated. Color-flow Doppler sonography shows promise as a cost-effective, noninvasive technique for diagnosing Graves disease.

  1. Transcranial Doppler ultrasonography: From methodology to major clinical applications.

    Science.gov (United States)

    D'Andrea, Antonello; Conte, Marianna; Cavallaro, Massimo; Scarafile, Raffaella; Riegler, Lucia; Cocchia, Rosangela; Pezzullo, Enrica; Carbone, Andreina; Natale, Francesco; Santoro, Giuseppe; Caso, Pio; Russo, Maria Giovanna; Bossone, Eduardo; Calabrò, Raffaele

    2016-07-26

    Non-invasive Doppler ultrasonographic study of cerebral arteries [transcranial Doppler (TCD)] has been extensively applied on both outpatient and inpatient settings. It is performed placing a low-frequency (≤ 2 MHz) transducer on the scalp of the patient over specific acoustic windows, in order to visualize the intracranial arterial vessels and to evaluate the cerebral blood flow velocity and its alteration in many different conditions. Nowadays the most widespread indication for TCD in outpatient setting is the research of right to left shunting, responsable of so called "paradoxical embolism", most often due to patency of foramen ovale which is responsable of the majority of cryptogenic strokes occuring in patients younger than 55 years old. TCD also allows to classify the grade of severity of such shunts using the so called "microembolic signal grading score". In addition TCD has found many useful applications in neurocritical care practice. It is useful on both adults and children for day-to-day bedside assessment of critical conditions including vasospasm in subarachnoidal haemorrhage (caused by aneurysm rupture or traumatic injury), traumatic brain injury, brain stem death. It is used also to evaluate cerebral hemodynamic changes after stroke. It also allows to investigate cerebral pressure autoregulation and for the clinical evaluation of cerebral autoregulatory reserve.

  2. Microphysical Retrieval from Doppler Radar Reflectivity Using Variational Data Assimilation

    Institute of Scientific and Technical Information of China (English)

    LI Yongping; ZHU Guofu; XUE Jishan

    2006-01-01

    One of the microphysical variables, the rainwater mixing ratio qr, is retrieved from the observed reflectivity of Doppler radar by a 3D variational data assimilation system. The qr as an analysis variable is obtained by minimizing a cost function defined as the difference between observed radar reflectivity and its retrieval from qr, plus the difference between qr and its background field from a mesoscale model's prediction. Covariance matrix of the background field's error is determined by the so-called NMC method. A method called the second-order auto-regression (SOAR) is used to calculate the coefficients of regressive filtering to fit in with small spatial scale such as cumulus in the process of spatial transformation. An ideal experiment demonstrates the correctness of this system and a sensitivity experiment proves that the random error of observed reflectivity has effect on the analyzed results. At last an experiment with observed data from the Doppler radar at Ma'anshan City in Anhui Province on 19 June 2002 was performed. The retrieved analysis variable qr in this test shows structures in detail, which coincide with the distribution of the echo picture observed by the radar.

  3. Extremely high-frequency micro-Doppler measurements of humans

    Science.gov (United States)

    Hedden, Abigail S.; Silvious, Jerry L.; Dietlein, Charles R.; Green, Jeremy A.; Wikner, David A.

    2014-05-01

    The development of sensors that are capable of penetrating smoke, dust, fog, clouds, and rain is critical for maintaining situational awareness in degraded visual environments and for providing support to the Warfighter. Atmospheric penetration properties, the ability to form high-resolution imagery with modest apertures, and available source power make the extremely high-frequency (EHF) portion of the spectrum promising for the development of radio frequency (RF) sensors capable of penetrating visual obscurants. Comprehensive phenomenology studies including polarization and backscatter properties of relevant targets are lacking at these frequencies. The Army Research Laboratory (ARL) is developing a fully-polarimetric frequency-modulated continuous-wave (FMCW) instrumentation radar to explore polarization and backscatter properties of in-situ rain, scattering from natural and man-made surfaces, and the radar cross section and micro-Doppler signatures of humans at EHF frequencies, specifically, around the 220 GHz atmospheric window. This work presents an overview of the design and construction of the radar system, hardware performance, data acquisition software, and initial results including an analysis of human micro-Doppler signatures.

  4. Hypercholesterolemia and Myocardial function evaluated via Tissue Doppler Imaging

    Directory of Open Access Journals (Sweden)

    Kotaru Pavan

    2009-11-01

    Full Text Available Abstract Objective To establish a link between hypercholesterolemia and myocardial dysfunction. Background Heart failure is a complex disease involving changes in systolic and diastolic function. Newer echocardiographic imaging modalities may be able to detect discreet changes in myocardial function associated with hypercholesterolemia. Therefore we sought to establish a link between hypercholesterolemia and myocardial dysfunction with tissue Doppler imaging (TDI. Methods Twenty-seven rabbits were studied: 7 were fed normal chow (group 1 and 20 a high cholesterol diet (10 with ezetimibe, 1 mg/kg/day; group 2 and 10 without, group 3. Echocardiographic images were obtained under general anesthesia. Serum cholesterol levels were obtained at baseline, 3 and 6 months and myocardial cholesterol levels measured following euthanasia. Results Doppler measurements, including E/A, E'/A' and S' were significantly lower in group 3 compared to both groups 1 and 2 but no significant differences were noted in chamber sizes or ejection fraction among the groups. Average serum cholesterol was higher in group 3 compared to groups 1 and 2 respectively (495 ± 305 mg/dl vs. 114 ± 95 mg/dl and 87 ± 37 mg/dl; p 2 = 0.17 p = 0.04, r2 = 0.37 p = 0.001 and r2 = 0.24 p = 0.01. Conclusion Cholesterol load in the serum and myocardium was significantly associated with decreased systolic and diastolic function by TDI. Moreover, lipid lowering was protective.

  5. Observations of 2D Doppler backscattering on MAST

    CERN Document Server

    Thomas, D A; Freethy, S J; Huang, B K; Shevchenko, V F; Vann, R G L

    2015-01-01

    The Synthetic Aperture Microwave Imaging (SAMI) diagnostic has conducted proof-of-principle 2D Doppler backscattering (DBS) experiments on MAST. SAMI actively probes the plasma edge using a wide (+-40 degrees vertical and horizontal) and tuneable (10-35.5 GHz) beam. The Doppler backscattered signal is digitised in vector form using an array of eight Vivaldi PCB antennas. This allows the receiving array to be focused in any direction within the field of view simultaneously to an angular range of 6-24 degrees FWHM at 10-34.5 GHz. This capability is unique to SAMI and is an entirely novel way of conducting DBS experiments. In this paper the feasibility of conducting 2D DBS experiments is explored. Initial measurements of phenomena observed on conventional DBS experiments are presented; such as momentum injection from neutral beams and an abrupt change in power and turbulence velocity coinciding with the onset of H-mode. In addition, being able to carry out 2D DBS imaging allows a measurement of magnetic pitch an...

  6. A phased array antenna for Doppler reflectometry in ASDEX upgrade

    Energy Technology Data Exchange (ETDEWEB)

    Wolf, Stefan; Lechte, Carsten; Kasparek, Walter [IGVP, Universitaet Stuttgart, D-70569 Stuttgart (Germany); Hennequin, Pascale [Laboratoire de Physique des Plasmas, CNRS, Ecole Polytech., F-91128 Palaiseau (France); Conway, Garrard; Happel, Tim [Max-Planck-Institut fuer Plasmaphysik, D-85748 Garching (Germany); Collaboration: ASDEX Upgrade Team

    2016-07-01

    In a toroidal plasma, Doppler reflectometry (DR) allows investigating electron density fluctuations with finite k {sub perpendicular} {sub to}. The injected microwave beam's frequency determines the radial position of the probed region, its tilt angle selects the wavenumber satisfying the Bragg condition for backscattering. The rotation velocity can be calculated from the Doppler shift of the backscattered signal's frequency. By varying the injected frequency, radial profiles can be reconstructed. Varying the tilt angle resolves the k {sub perpendicular} {sub to} -spectrum of the fluctuations. For DR, a pair of phased array antennas (PAAs) has been designed, built, and installed in the ASDEX Upgrade tokamak. Beam steering is done by slightly changing the injected frequency, thus, the PAAs do not need any movable parts or electronics inside the vacuum vessel. From 75 to 105 GHz, the PAAs feature 13 frequency bands, each with an angular scan range of -20 to +20 {sup circle}. So, for each angle, there are 13 radial positions to be probed. The results from PAA characterisation, commissioning, and first DR measurements are presented.

  7. On-Orbit Ephemeris Determination with Radio Doppler Validation

    Energy Technology Data Exchange (ETDEWEB)

    Dallmann, Nicholas [Los Alamos National Laboratory; Proicou, Michael Chris [Los Alamos National Laboratory; Seitz, Daniel Nathan [Los Alamos National Laboratory; Warniment, Adam [Los Alamos National Laboratory

    2016-02-09

    Multiple CubeSats are often released from the same host spacecraft into virtually the same orbit at nearly the same time. A satellite team needs the ability to identify and track its own satellites as soon as possible. However, this can be a difficult and confusing task with a large number of satellites. Los Alamos National Laboratory encountered this issue during a launch of LANL-designed CubeSats that were released with more than 20 other objects. A simple radio Doppler method used shortly after launch by the Los Alamos team to select its satellites of interest from the list of available tracked ephemerides is described. This method can also be used for automated real time ephemeris validation. For future efforts, each LANL-designed CubeSat will automatically perform orbit determination from the position, velocity, and covariance estimates provided by an added on-board GPS receiver. This self-determined ephemeris will be automatically downlinked by ground stations for mission planning, antenna tracking, Doppler-pre-correction, etc. A simple algorithm based on established theory and well suited for embedded on-board processing is presented. The trades examined in selecting the algorithm components and data formats are briefly discussed, as is the expected performance.

  8. Characterization of high resolution range and Doppler LADAR

    Science.gov (United States)

    Flores, Benjamin C.; Verdin, Berenice

    2009-08-01

    Compared to microwave radar systems, chaotic ladar has the potential for providing a range resolution well into the mm range. The purpose of this project is to determine the signal processing schemes required to extract range and Doppler information from a chaotic signal scattered by environmental targets. Specifically, a ladar would be driven into the coherence collapse through an external optical resonator, thus generating a chaotic electromagnetic field with a wide rms bandwidth of several GHz. The reflected field would be processed though optical correlation to extract range and Doppler information. Simulations show that the power spectral density properties of the field are dependent on the Lyapunov exponent of the chaotic field, which be exploited to obtain optimum range resolution. A complete statistical analysis of the wideband ambiguity function of the field reveals that the signal has better performance than noise-like signals generated via electro-optic amplitude modulation, thus allowing for high resolution imaging of terrains with pseudo random reflectivity variations.

  9. On-line. gamma. -ray investigation of the /sup 14/N + /sup 27/Al reaction at 30 Mev/u

    Energy Technology Data Exchange (ETDEWEB)

    Charvet, A.; Beraud, R.; Duffait, R.; Ollivier, T.; Meyer, M.; Kossakowski, R.; Andre, S.; Barneoud, D.; Foin, C.; Genevey, J.

    1985-03-01

    The cross-sections of target-like residues following the /sup 14/N+/sup 27/Al reaction at 30 MeV/u have been measured from in-beam and radioactive ..gamma..-ray spectra. The recoil velocities of some fragments have been estimated from the ..gamma..-ray Doppler broadening.

  10. ROLE OF DOPPLER IN PRED ICTION OF PERINATAL OUTCOME: A COMPARATIVE STUDY OF DOPPLER INDICES IN LOW RISK AND HIGH RISK PREGNANCIES

    Directory of Open Access Journals (Sweden)

    Uma

    2015-09-01

    Full Text Available AIMS AND OBJECTIVES: to evaluate Doppler abnormalities in low risk and high risk pregnancies and to determine their relation to the outcome of pregnancy . METHODS: A total of 60 no. of pregnant women without any known risk factors are included in the low risk group and 60 no. of pregnant women with pre - eclampsia or gestational hypertension or intra uterine growth restriction, are included in the high risk group. Doppler evaluation done at term and the outcome is noted in terms of mode of delivery and perinatal complications in both the groups. RESULTS: Forty percent of high risk pregnant women and 1.6 percent of low risk pregnant women are found to be associated with abnormal Doppler results. Abnormal UA - PI , in association with high risk pregnancy is significantly associated wit h abnormal mode of delivery (P - 0.0005 and perinatal complications (P - 0.0009. Abnormal MCA - PI and abnormal MCA - PI/UA - PI ratio of <1.1 are associated with perinatal complications with highest significance (P - <0.0001. High risk pregnancy with normal Doppl er results, also had perinatal complications with slightly lower significance (0.0011. CONCLUSION: There is definite association of Doppler abnormalities with high risk pregnancy. Low risk pregnancy is almost never associated with Doppler abnormalities an d it is not necessary to perform Doppler to all women. Of all the Doppler indices, the ratio of MCA - PI/ UA - PI appears to be the best predictor of poor outcome. Normal Doppler results in association with high risk pregnancy cannot ensure uncomplicated outco me.

  11. All semiconductor laser Doppler anemometer at 1.55 μm

    DEFF Research Database (Denmark)

    Hansen, Rene Skov; Pedersen, Christian

    2008-01-01

    We report to our best knowledge the first all semiconductor Laser Doppler Anemometer (LIDAR) for wind speed determination. We will present the design and first experimental results on a focusing coherent cw laser Doppler anemometer for measuring atmospheric wind velocities in the 10 meters to 300...

  12. Potential scientific research which will benefit from an airborne Doppler lidar measurement system

    Science.gov (United States)

    Frost, W.

    1980-01-01

    Areas of research which can be significantly aided by the Doppler lidar airborne system are described. The need for systematic development of the airborne Doppler lidar is discussed. The technology development associated with the systematic development of the system will have direct application to satellite systems for which the lidar also promises to be an effective instrument for atmospheric research.

  13. Explanation of the inverse Doppler effect observed in nonlinear transmission lines.

    Science.gov (United States)

    Kozyrev, Alexander B; van der Weide, Daniel W

    2005-05-27

    The theory of the inverse Doppler effect recently observed in magnetic nonlinear transmission lines is developed. We explain the crucial role of the backward spatial harmonic in the occurrence of an inverse Doppler effect and draw analogies of the magnetic nonlinear transmission line to the backward wave oscillator.

  14. Changes in superior mesenteric artery Doppler waveform during reduction of cardiac stroke volume and hypotension

    DEFF Research Database (Denmark)

    Perko, M J; Perko, Grazyna; Just, S;

    1996-01-01

    . Presented interdependencies should be taken into consideration while studying mesenteric physiology with the use of Doppler technique and while interpreting the duplex results in patients suffering from diseases that may influence flow velocity and mimic or obscure Doppler effects of the SMA stenosis....

  15. Influence of recent exercise and skin temperature on ultrasound Doppler measurements in patients with rheumatoid arthritis

    DEFF Research Database (Denmark)

    Ellegaard, Karen; Torp-Pedersen, Søren; Henriksen, Marius

    2009-01-01

    OBJECTIVE: Use of ultrasound Doppler (USD) in diagnosing and treatment monitoring of patients with RA has increased considerably. Hyperaemia is an integral part of the inflammatory response, and the amount of USD activity in an inflamed synovium may therefore be used to quantify the inflammatory...... the amount of Doppler activity might be affected by low skin temperatures....

  16. The use of pulsed-wave Doppler in prenatal diagnosis. An update

    OpenAIRE

    DEGANI, S.

    2007-01-01

    Pulsed wave Doppler ultrasound of fetal vessels confirms the similarity of human fetal circulation to the experimental animal physiology, The result of a multitude of research articles in this field is the clinical use of various components of fetal circulation in perinatal medicine. Umbilical, uterine and fetal cerebral arteries as well as the fetal venous circulation show the potential of Doppler ultrasonography.

  17. Effect of intracapsular hyperpressure on femoral head blood flow. Laser Doppler flowmetry in dogs.

    Science.gov (United States)

    Vegter, J; Klopper, P J

    1991-08-01

    Intracapsular hyperpressure in the hip joint of dogs affected femoral head blood flow, especially in the juvenile animals. Graphic recording of the laser Doppler signal curve using rapid sampling time demonstrated venous hip joint tamponade in both juvenile and adult dogs. Laser Doppler flowmetry seems to be a sensitive and reproducible method to demonstrate femoral-head blood-flow changes.

  18. Tissue Doppler assessment of right ventricular function in female patients with limited form of systemic sclerosis

    Directory of Open Access Journals (Sweden)

    Ayman Ahmed Abdelaziz

    2013-09-01

    Conclusions: Patients with limited form of SSc present with pulsed-tissue Doppler imaging indices indicative of right ventricle dysfunction, which had significant correlations with disease duration. Tissue Doppler is a valuable non-invasive tool for detecting RV myocardial involvement in patients with limited SSc.

  19. Ultralyd farve-Doppler-undersøgelse af arteria carotis. Prospektiv sammenligning med arteriografi

    DEFF Research Database (Denmark)

    Sillesen, H H; Just, S R; Hansen, Linda;

    1994-01-01

    Eleven hundred and thirty-eight patients suspected of carotid artery disease were examined prospectively by ultrasound-Doppler. In 39 cases, intra-arterial digital subtraction arteriography was performed as well as well and compared to ultrasound Doppler examination. The overall accuracy was 80% ...

  20. Radar Micro-Doppler Feature Extraction Using the Singular Value Decomposition

    NARCIS (Netherlands)

    Wit, J.J.M. de; Harmanny, R.I.A.; Molchanov, P.

    2014-01-01

    Abstract—The micro-Doppler spectrogram depends on parts of a target moving and rotating in addition to the main body motion (e.g., spinning rotor blades) and is thus characteristic for the type of target. In this study, the micro-Doppler spectrogram is exploited to distinguish between birds and smal

  1. Prenatal Doppler flow patterns and neonatal circulation in fetal growth restriction

    NARCIS (Netherlands)

    Tanis, Jozien C; Boelen, Maaike R; Schmitz, Danique M; Casarella, Lucia; van der Laan, Michelle E; Bos, Arend F; Bilardo, Caterina M

    2015-01-01

    OBJECTIVES: To investigate, in growth-restricted fetuses, whether prenatal Doppler parameters are correlated with neonatal circulatory changes. METHODS: In 43 cases of suspected FGR, serial Doppler measurements of the umbilical artery (UA) and the middle cerebral artery (MCA) were performed (last me

  2. Validation of Doppler ultrasound and magnetic resonance imaging velocity measurements by means of a test object

    NARCIS (Netherlands)

    Oostayen, J.A. van; Bezemer, R.A.; Wasser, M.N.J.M.; Teirlinck, C.J.P.M.

    1996-01-01

    Objective: To validate Doppler ultrasound and MRI mean velocity measurements in a test object in which mean velocities are known and can be chosen within a range of 10-100 cm/s in tubes of 4 and 8 mm. This validation was carried out to check the performance of a duplex Doppler ultrasound system that

  3. GLASS-FIBER SELF-MIXING DIODE-LASER DOPPLER-VELOCIMETER

    NARCIS (Netherlands)

    KOELINK, MH; SLOT, M; DEMUL, FFM; GREVE, J; GRAAFF, R; DASSEL, ACM; AARNOUDSE, JG

    1992-01-01

    A novel diode-laser Doppler velocimeter based on self-mixing feedback of Doppler-shifted light in the laser through a single glass fibre is described. The instrument can be applied, for example, to the invasive measurement of blood velocities in blood vessels, and of other industrial fluids and soli

  4. Transcranial Doppler sonography in children: Review of a seven-year experience

    Energy Technology Data Exchange (ETDEWEB)

    Hirsch, Wolfgang; Hiebsch, Wolfgang; Teichler, Heike; SchlUeter, Andreas

    2002-06-01

    AIM: We report the use of transcranial Doppler sonography (TCD) examinations in children (mean age 12.7 years; range 0.5-18 years) without an open fontanelle, using TCD equipment with a 2 MHz pulse wave transducer. Our results over a 7-year period are described. MATERIAL AND METHODS: A total of 858 children were referred from the paediatric outpatient department. All patients were divided into three groups according to the reason for referral. RESULTS: We found positive pathological results in the following: (1) headache and orthostatic dysregulation (0.4%, three out of 728); (2) acute neurological symptoms (5.4%, six out of 112); (3) other indications (22.2%, four out of 18). The positive predictive value of finding an abnormality was very low (0.50) . CONCLUSION: TCD examination is ineffective in children with non-specific headache or orthostatic dysregulation due to the specific limitations of this method. We found a higher percentage of abnormal results in children referred for other indications. However, since these children usually undergo MR imaging (and MR angiography, if necessary), in our opinion the TCD examination does not add any additional information. The value of TCD in children is not in the primary diagnosis of disease but in the follow up of known vascular processes (e.g. stenoses) or in chronic diseases including angiitis and sickle cell disease. Hirsch, W. et al. (2002)

  5. \\Lambda-enhanced Sub-Doppler Cooling of Lithium Atoms in D1 Gray Molasses

    CERN Document Server

    Grier, Andrew T; Rem, Benno S; Delehaye, Marion; Khaykovich, Lev; Chevy, Frédéric; Salomon, Christophe

    2013-01-01

    Following the bichromatic sub-Doppler cooling scheme on the D1-line of 40K recently demonstrated in (Fernandes et al. 2012), we introduce a similar technique for 7Li atoms and obtain temperatures of 60 uK while capturing all of the 5x10^8 atoms present from the previous stage. We investigate the influence of the detuning between the the two cooling frequencies and observe a threefold decrease of the temperature when the Raman condition is fulfilled. We interpret this effect as arising from extra cooling due to long-lived coherences between hyperfine states. Solving the optical Bloch equations for a simplified, \\Lambda-type three-level system we identify the presence of an efficient cooling force near the Raman condition. After transfer into a quadrupole magnetic trap, we measure a phase space density of ~10^-5. This laser cooling offers a promising route for fast evaporation of lithium atoms to quantum degeneracy in optical or magnetic traps.

  6. Color Doppler ultrasound of the hand: observations on clinical utility in rheumatoid arthritis.

    Science.gov (United States)

    Saadeh, Constantine; Gaylor, Patrick; Lee, Doohi; Malacara, Jan; Gaylor, Michael

    2004-02-01

    The use of ultrasound with color Doppler in the evaluation of rheumatoid arthritis was followed in 25 patients with joint complaints. Small joint ultrasound of the metacarpophalangeal joints (MCPs) as well as the wrists was performed with supplementation by color Doppler. In addition, 6 patients were followed for at least 3 months after start of treatment of rheumatoid arthritis using the same technique. In patients with what appeared to be definite rheumatoid arthritis, ultrasound supported this diagnosis as evidenced by the finding of cortical defects, extensor tendon sheath thickening, and synovial proliferation. Increased activity by color Doppler ultrasonography was the most common finding. Significant decrease in color Doppler activity was noted in the 6 patients who were followed up after 3 months of therapy with disease-modifying agents. Therefore, the use of ultrasound with color Doppler could aid in the diagnosis and follow up of patients with rheumatoid arthritis.

  7. Micro-Doppler Ambiguity Resolution Based on Short-Time Compressed Sensing

    Directory of Open Access Journals (Sweden)

    Jing-bo Zhuang

    2015-01-01

    Full Text Available When using a long range radar (LRR to track a target with micromotion, the micro-Doppler embodied in the radar echoes may suffer from ambiguity problem. In this paper, we propose a novel method based on compressed sensing (CS to solve micro-Doppler ambiguity. According to the RIP requirement, a sparse probing pulse train with its transmitting time random is designed. After matched filtering, the slow-time echo signals of the micromotion target can be viewed as randomly sparse sampling of Doppler spectrum. Select several successive pulses to form a short-time window and the CS sensing matrix can be built according to the time stamps of these pulses. Then performing Orthogonal Matching Pursuit (OMP, the unambiguous micro-Doppler spectrum can be obtained. The proposed algorithm is verified using the echo signals generated according to the theoretical model and the signals with micro-Doppler signature produced using the commercial electromagnetic simulation software FEKO.

  8. Quantitative Doppler measures in coiled vessels: investigation on excised umbilical veins.

    Science.gov (United States)

    Guiot, C; Roatta, S; Piccoli, E; Saccomandi, F; Todros, T

    1999-11-01

    Quantitative assessment of umbilical venous blood velocity with Doppler ultrasound (US) must cope with the coiled structure of the vein inside the cord. Both an experimental and a theoretical approach showed remarkable variations in the insonation angle when the probe was moved along the vein, provided the inclination between the Doppler probe and the cord was kept constant. Inaccurate signal processing, stochastic variability and flow disturbances could, however, mask the influence of the geometry. The above hypotheses were assessed by investigating five cords in vitro a few hours after delivery from normal pregnancies at term. The Doppler signal was sampled at different sites along each cord and the mean Doppler shift estimated by FFT spectral analysis, both directly and through the noise rejection D'Alessio's algorithm, which proved effective in improving the Doppler shift estimate in condition of low signal-to-noise ratio (SNR).

  9. The Effect of Amplitude Modulation on the Axial Resolution of Doppler-Based Ultrasonic Topography Measurement

    DEFF Research Database (Denmark)

    RezaNejad Gatabi, Javad; Das, Sayantan; Forouzbakhsh, Farshid

    2016-01-01

    of the Doppler measurement techniques. A modified Doppler measurement system that significantly improves the measurement accuracy is also presented. The fabricated sensor has 72-μm measurement accuracy using 40-kHz transducers. This technique can also be employed in cost-effective displacement measurement...... variation of the received signal. Amplitude variation significantly affects the measurement accuracy when the surface axial displacement range is comparable with the ultrasonic wavelength. This paper presents a theoretical and experimental study of the effect of amplitude modulation on the performance......Ultrasonic Doppler-based systems for surface topography measurements are attractive alternatives to the transit-time-based methods. Sensors used in Doppler systems are less dependent on the speed of the sound in air, although contemporary Doppler measurement systems are sensitive to the amplitude...

  10. A Compensation Algorithm Based on RSPWVD-Hough Transform for Doppler Expansion in Passive Radar

    Directory of Open Access Journals (Sweden)

    Guan Xin

    2013-12-01

    Full Text Available For passive radar, long integration time is used to achieve high processing gain to detect weak target. But range migration and Doppler expansion may occur for high-speed targets. Keystone transform can be used to rectify range migration introduced by radial-speed. But tangential-speed may still lead to Doppler expansion, which entails a loss of integration gain. In this paper, signal model is presented to analyze the reason for Doppler expansion. Then, a Doppler expansion compensation method is introduced based on RSPWVD-Hough transform for multi-target scenario. Simulation results show that the proposed method can compensate the energy loss caused by Doppler expansion for multi-target scene, and it achieves good performance. The proposed method is also effective for weak targets, which means it can improve the detection ability of weak target in passive radar systems.

  11. Direct measurement of Lorentz transformation with Doppler effects

    Science.gov (United States)

    Chen, Shao-Guang

    For space science and astronomy the fundamentality of one-way velocity of light (OWVL) is selfevident. The measurement of OWVL (distance/interval) and the clock synchronization with light-signal transfer make a logical circulation. This means that OWVL could not be directly measured but only come indirectly from astronomical method (Romer's Io eclipse and Bradley's sidereal aberration), furthermore, the light-year by definitional OWVL and the trigonometry distance with AU are also un-measurable. For to solve this problem two methods of clock synchronization were proposed: The direct method is that at one end of dual-speed transmissionline with single clock measure the arriving-time difference of longitudinal wave and transverse wave or ordinary light and extraordinary light, again to calculate the collective sending-time of two wave with Yang's /shear elastic-modulus ratio (E/k) or extraordinary/ordinary light refractive-index ratio (ne/no), which work as one earthquake-station with single clock measures first-shake time and the distance to epicenter; The indirect method is that the one-way wavelength l is measured by dual-counters Ca and Cb and computer's real-time operation of reading difference (Nb - Na) of two counters, the frequency f is also simultaneously measured, then l f is just OWVL. Therefore, with classical Newtonian mechanics and ether wave optics, OWVL can be measured in the Galileo coordinate system with an isotropic length unit (1889 international meter definition). Without any hypotheses special relativity can entirely establish on the metrical results. When a certain wavelength l is defined as length unit, foregoing measurement of one-way wavelength l will become as the measurement of rod's length. Let a rigidity-rod connecting Ca and Cb moves relative to lamp-house with velocity v, rod's length L = (Nb - Na) l will change follow v by known Doppler effect, i.e., L(q) =L0 (1+ (v/c) cos q), where L0 is the proper length when v= 0, v• r = v cos q

  12. Processing Doppler Lidar and Cloud Radar Observations for Analysis of Convective Mass Flux Parameterizations Using DYNAMO Direct Observations

    Science.gov (United States)

    2014-09-30

    1 DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited. Processing Doppler Lidar and Cloud Radar Observations...campaign the data gathered from the High Resolution Doppler Lidar (HRDL) and the 94-GHz cloud Doppler radar Report Documentation Page Form ApprovedOMB No...00-00-2014 to 00-00-2014 4. TITLE AND SUBTITLE Processing Doppler Lidar and Cloud Radar Observations for Analysis of Convective Mass Flux

  13. Transthoracic Doppler echocardiography to predict optimal tube pulsing window for coronary artery CT angiography

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Gang, E-mail: cjr.sungang@vip.163.com [Department of Medical Imaging, Jinan Military General Hospital, No. 25, Shifan Road, Jinan, Shandong Province 250031 (China); Li, Min, E-mail: limin22000@yahoo.com.cn [Department of Medical Imaging, Jinan Military General Hospital, No. 25, Shifan Road, Jinan, Shandong Province 250031 (China); Jiang, Xiang-sen, E-mail: jiangxiangsen123@126.com [Department of Medical Imaging, Jinan Military General Hospital, No. 25, Shifan Road, Jinan, Shandong Province 250031 (China); Li, Li, E-mail: leely1976@yahoo.com.cn [Department of Medical Imaging, Jinan Military General Hospital, No. 25, Shifan Road, Jinan, Shandong Province 250031 (China); Peng, Zhao-hui, E-mail: zhaohuipeng_R@163.com [Department of Medical Imaging, Jinan Military General Hospital, No. 25, Shifan Road, Jinan, Shandong Province 250031 (China); Mu, Nan-nan, E-mail: munannan22000@sohu.com [Department of Medical Imaging, Jinan Military General Hospital, No. 25, Shifan Road, Jinan, Shandong Province 250031 (China)

    2012-09-15

    Rationale and objective: To evaluate the feasibility of transthoracic Doppler echocardiography to determine the optimal pulsing windows for CT coronary angiography to narrow the pulsing windows further, especially in higher heart rate. Materials and methods: Doppler was performed on 135 patients before CT scanning. For Doppler, the intervals with minimal motion were evaluated during both systole and diastole integrating electrocardiogram (ECG) intervals. For CT scanning, the retrospective ECG-gating was applied and the optimal reconstruction intervals were determined. The accuracy of Doppler analysis to predict the optimal reconstruction intervals was tested. The predicted length of pulsing windows was compared between Doppler analysis and traditional prospective ECG-gating protocol (heart rate ≦ 65 bpm, 60–76%; 66–79 bpm, 30–77%; ≧80 bpm, 31–47%). Results: According to Doppler analysis, the mean length of intervals with minimal motion in systole was 106.4 ± 39.2 ms and 125.2 ± 92.0 ms in diastole. When the intervals with minimal motion during diastole > 90 ms, the optimal reconstruction intervals were located at diastole; otherwise, at systole (P < 0.001). The optimal reconstruction intervals in 93.8% (132/135) patients could be predicted accurately by Doppler analysis. If the optimal reconstruction intervals predicted by Doppler were applied as the exposure windows, the mean length of pulsing windows should has been 105.2 ± 69.4 ms (range: 26.9–510.3 ms), which was significantly shorter than that of traditional prospective ECG-gating protocol (232.0 ± 120.2 ms, range: 93.2–427.3 ms, P < 0.001). Conclusion: Doppler can help detecting the optimal pulsing windows accurately. Prospective ECG-gating incorporating Doppler analysis may narrow pulsing windows significantly while maintaining image quality.

  14. Magnetic Doppler imaging of the chemically peculiar star HD 125248

    Science.gov (United States)

    Rusomarov, N.; Kochukhov, O.; Ryabchikova, T.; Ilyin, I.

    2016-04-01

    Context. Intermediate-mass, chemically peculiar stars with strong magnetic fields provide an excellent opportunity to study the topology of their surface magnetic fields and the interplay between magnetic geometries and abundance inhomogeneities in the atmospheres of these stars. Aims: We reconstruct detailed maps of the surface magnetic field and abundance distributions for the magnetic Ap star HD 125248. Methods: We performed the analysis based on phase-resolved, four Stokes parameter spectropolarimetric observations obtained with the HARPSpol instrument. These data were interpreted with the help of magnetic Doppler imaging techniques and model atmospheres taking the effects of strong magnetic fields and nonsolar chemical composition into account. Results: We improved the atmospheric parameters of the star, Teff = 9850 ± 250 K and log g = 4.05 ± 0.10. We performed detailed abundance analysis, which confirmed that HD 125248 has abundances typical of other Ap stars, and discovered significant vertical stratification effects for the Fe ii and Cr ii ions. We computed LSD Stokes profiles using several line masks corresponding to Fe-peak and rare earth elements, and studied their behavior with rotational phase. Combining previous longitudinal field measurements with our own observations, we improved the rotational period of the star Prot = 9.29558 ± 0.00006 d. Magnetic Doppler imaging of HD 125248 showed that its magnetic field is mostly poloidal and quasi-dipolar with two large spots of different polarity and field strength. The chemical maps of Fe, Cr, Ce, Nd, Gd, and Ti show abundance contrasts of 0.9-3.5 dex. Among these elements, the Fe abundance map does not show high-contrast features. Cr is overabundant around the negative magnetic pole and has 3.5 dex abundance range. The rare earth elements and Ti are overabundant near the positive magnetic pole. Conclusions: The magnetic field of HD 125248 has strong deviations from the classical oblique dipole field

  15. Studying the recovery of as-received industrial Al alloys by positron annihilation spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Abdel-Hady, E.E. [Physics Department, Faculty of Science, El-Minia University, BO 61519, El-Minia (Egypt)]. E-mail: esamhady@link.net; Ashry, A. [Faculty of Education, Ain Shams University, Cairo (Egypt); Ismail, H. [Faculty of Education, Ain Shams University, Cairo (Egypt); El-Gamal, S. [Faculty of Education, Ain Shams University, Cairo (Egypt)

    2006-02-28

    Positron annihilation lifetime (PAL) spectroscopy, Doppler broadening of annihilation radiation (DBAR) spectroscopy and Vickers microhardness (Hv) measurements were performed to study the micro- and macro-structure variations during isochronal annealing from room temperature (RT) to 500 deg. Cof commercial pure Al (1 1 0 0), Al-Mn-Mg (3 0 0 4) and Al-Mg-Si (6 2 0 1) alloys. Three annealing stages of microstructures have been identified as recovery, partial recrystallization and complete recrystallization followed by grain growth. A positive correlation between the macroscopic mechanical properties (Hv) and positron annihilation parameters has been achieved for the three samples under investigation.

  16. Dynamics of speckles with a small number of scattering events: specific features of manifestation of the Doppler effect.

    Science.gov (United States)

    Ulyanov, Sergey S

    2014-04-01

    Spectra of intensity fluctuations of dynamic non-Gaussian speckles formed with a small number of scattering events have been studied theoretically and experimentally. A new type of manifestation of the Doppler effect has been observed. The dependence of frequency position of the Doppler peak and the shape of the Doppler spectrum on the number of scatterers has been analyzed.

  17. Multi-beam raindrop size distributions retrievals on the Doppler spectra: Influence of averaging and mean horizontal wind correction

    NARCIS (Netherlands)

    Unal, C.M.H.

    2012-01-01

    Acquiring the raindrop size distribution (DSD) from radar data is still a challenge. For profiling radar, this distribution can be estimated from the Doppler spectra. However the Doppler spectrum is not a direct measure of the DSD. The radial component of the wind shifts the Doppler spectrum related

  18. Aplicação da ultrassonografia colorida doppler em programas de transferência de embriões equinos Potential use of doppler ultrasound in equine embryo transfer programs

    Directory of Open Access Journals (Sweden)

    Jair Camargo Ferreira

    2011-06-01

    Full Text Available Os programas comerciais de transferência de embriões em éguas existem por mais de três décadas e são hoje uma das biotécnias mais utilizadas na reprodução assistida de equinos. O exame ultrassonográfico nos períodos pré e pós-cobertura de doadoras de embriões, assim como a avaliação de receptoras no momento da inovulação é de vital importância para o êxito de um programa de transferência de embriões. A ultrassonografia Doppler é uma técnica não-invasiva que permite a avaliação em tempo real da hemodinâmica do trato reprodutivo de animais de grande porte. Por fornecer detalhes anatômicos e informações imediatas sobre a fisiologia do fluxo sanguíneo de tecidos e órgãos, o exame doppler permite a avaliação do potencial ovulatório de folículos e do status funcional de corpo lúteo e útero, além de ser uma técnica auxiliar para o diagnóstico de distúrbios na hemodinâmica do sistema reprodutivo. Alterações na perfusão sanguínea dos futuros folículos dominantes são detectáveis em diferentes fases de seu desenvolvimento, como na divergência folicular e no período pré-ovulatório. A partir dessas informações, é possível determinar o princípio da atividade sexual e o momento ideal para o início de tratamentos superovulatórios e indutores de ovulação, assim como o momento mais apropriado para a realização de coberturas de éguas doadoras de embriões. A avaliação através do modo-Doppler do corpo lúteo e útero de éguas receptoras é também um instrumento auxiliar para a seleção de animais com perfil sérico de progesterona e ambiente uterino adequados para a sobrevivência do embrião e manutenção da gestação. Essa técnica pode ser útil ainda ao se avaliar a interação concepto-maternal. Apesar da aplicabilidade da tecnologia doppler dentro de programas de transferência de embriões, novos estudos visando a determinar padrões de normalidade e posterior caracterização de

  19. Zeeman-Doppler Imaging : Old Problems and New Methods

    CERN Document Server

    Carroll, T A; Strassmeier, K G; Ilyin, I

    2009-01-01

    Zeeman-Doppler Imaging (ZDI) is a powerful inversion method to reconstruct stellar magnetic surface fields. The reconstruction process is usually solved by translating the inverse problem into a regularized least-square or optimization problem. In this contribution we will emphasize that ZDI is an inherent non-linear problem and the corresponding regularized optimization is, like many non-linear problems, potentially prone to local minima. We show how this problem will be exacerbated by using an inadequate forward model. To facilitate a more consistent full radiative transfer driven approach to ZDI we describe a two-stage strategy that consist of a principal component analysis (PCA) based line profile reconstruction and a fast approximate polarized radiative transfer method to synthesize local Stokes profiles. Moreover, we introduce a novel statistical inversion method based on artificial neural networks (ANN) which provide a fast calculation of a first guess model and allows to incorporate better physical co...

  20. Zeeman-Doppler imaging: old problems and new methods

    Science.gov (United States)

    Carroll, Thorsten A.; Kopf, Markus; Strassmeier, Klaus G.; Ilyin, Ilya

    2009-04-01

    Zeeman-Doppler Imaging (ZDI) is a powerful inversion method to reconstruct stellar magnetic surface fields. The reconstruction process is usually solved by translating the inverse problem into a regularized least-square or optimization problem. In this contribution we will emphasize that ZDI is an inherent non-linear problem and the corresponding regularized optimization is, like many non-linear problems, potentially prone to local minima. We show how this problem will be exacerbated by using an inadequate forward model. To facilitate a more consistent full radiative transfer driven approach to ZDI we describe a two-stage strategy that consist of a principal component analysis (PCA) based line profile reconstruction and a fast approximate polarized radiative transfer method to synthesize local Stokes profiles. Moreover, we introduce a novel statistical inversion method based on artificial neural networks (ANN) which provide a fast calculation of a first guess model and allows to incorporate better physical constraints into the inversion process.

  1. Response of phase Doppler anemometer systems to nonspherical droplets.

    Science.gov (United States)

    Damaschke, N; Gouesbet, G; Gréhan, G; Mignon, H; Tropea, C

    1998-04-01

    The Phase Doppler Anemometer (PDA) technique measures particle diameter assuming sphericity. A means for detecting nonsphericity has usually been implemented in commercial PDA systems to avoid sizing errors if the sphericity assumption is not valid. In the present research the response of standard and planar PDA systems is examined experimentally in more detail by passing nonspherical droplets of known shape through the measurement volume. The effectiveness of nonsphericity detection schemes can be evaluated, and furthermore the influence of the droplet oscillations on the frequency and phase evolution of individual signals can be quantified. The light scattering from such particles has been simulated by using geometric optics, and the computed response of standard and planar PDA systems agrees well with the experimental observations. We conclude with some remarks concerning the possibilities of characterizing the nonsphericity with PDA systems.

  2. Ultrasonography color Doppler of the hepatic venous portal system

    Directory of Open Access Journals (Sweden)

    Juan Carlos Mantilla Suárez

    2006-08-01

    Full Text Available Color doppler ultrasonography is an imaging method that allows theassessment of the venous portal hepatic system to obtain informationfor the diagnosis of portal venous hypertension, identifying thesubtle changes of the hepatic arterial flow, spectral wave and pulsatility index, portal vein diameter, morphology of the spectral wave, direction o flow inverted and portosystemic shunts in advancedpathology as well as in the evaluation of transyugular intrahepaticportosystemic shunts (TIPS, used in the treatment of patients withesophageal bleeding varix. It is useful in diagnosis of the Budd-Chiari syndrome and the evaluation and follow up of patients with inferior vein cava filters. This article offers a review of the hepatic portal venous system and the main ultrasonographic features of portal venous hypertension, and Budd-Chiari syndrome and their causes.

  3. Externally Dispersed Interferometry for Resolution Boosting and Doppler Velocimetry

    Energy Technology Data Exchange (ETDEWEB)

    Erskine, D J

    2003-12-01

    Externally dispersed interferometry (EDI) is a rapidly advancing technique for wide bandwidth spectroscopy and radial velocimetry. By placing a small angle-independent interferometer near the slit of an existing spectrograph system, periodic fiducials are embedded on the recorded spectrum. The multiplication of the stellar spectrum times the sinusoidal fiducial net creates a moire pattern, which manifests high detailed spectral information heterodyned down to low spatial frequencies. The latter can more accurately survive the blurring, distortions and CCD Nyquist limitations of the spectrograph. Hence lower resolution spectrographs can be used to perform high resolution spectroscopy and radial velocimetry (under a Doppler shift the entire moir{acute e} pattern shifts in phase). A demonstration of {approx}2x resolution boosting (100,000 from 50,000) on the Lick Obs. echelle spectrograph is shown. Preliminary data indicating {approx}8x resolution boost (170,000 from 20,000) using multiple delays has been taken on a linear grating spectrograph.

  4. Wide angle Michelson Doppler imaging interferometer. [measuring atmospheric emissions

    Science.gov (United States)

    Shepherd, G. G.

    1980-01-01

    The optical system, stepping control, phase and modulation depth, array detector, and directions sensor are described for a specialized type of Michelson interferometer which works at sufficiently high resolution to measure the line widths and Doppler shifts of naturally occurring atmospheric emissions. With its imaging capability, the instrument can potentially supply this data independently for each element of the 100 x 100 detector array. The experiment seeks: (1) to obtain vertical profiles of atmospheric winds and temperatures as functions of latitude by observing near the limb; (2) to acquire exploratory wind and temperature data on smaller scale structures in airglow irregularities and in auroral forms; and (3) to collaborate with other Spacelab experiments, such as barium cloud releases, in providing wind and temperature data.

  5. WAMDII: The Wide Angle Michelson Doppler Imaging Interferometer

    Science.gov (United States)

    1992-01-01

    As part of an effort to learn more about the upper atmosphere and how it is linked to the weather experienced each day, NASA and NRCC are jointly sponsoring the Wide Angle Michelson Doppler Imaging Interferometer (WAMDII) Mission. WAMDII will measure atmospheric temperature and wind speed in the upper atmosphere. In addition to providing data on the upper atmosphere, the wind speed and temperature readings WAMDII takes will also be highly useful in developing and updating computer simulated models of the upper atmosphere. These models are used in the design and testing of equipment and software for Shuttles, satellites, and reentry vehicles. In making its wind speed and temperature measurements, WAMDII examines the Earth's airglow, a faint photochemical luminescence caused by the influx of solar ultraviolet energy into the upper atmosphere. During periods of high solar flare activity, the amount of this UV energy entering the upper atmosphere increases, and this increase may effect airglow emissions.

  6. Observing Molecular Spinning via the Rotational Doppler Effect

    CERN Document Server

    Korech, Omer; Gordon, Robert J; Averbukh, Ilya Sh; Prior, Yehiam

    2013-01-01

    When circularly polarized light is scattered from a rotating target, a rotational Doppler shift (RDS) emerges from an exchange of angular momentum between the spinning object and the electromagnetic field. Here, we used coherently spinning molecules to generate a shift of the frequency of a circularly polarized probe propagating through a gaseous sample. We used a linearly polarized laser pulse to align the molecules, followed by a second delayed pulse polarized at 45{\\deg} to achieve unidirectional molecular rotation. The measured RDS is orders of magnitude greater than previously observed by other methods. This experiment provides explicit evidence of unidirectional molecular rotation and paves the way for a new class of measurements in which the rotational direction of molecular reagents may be monitored or actively controlled.

  7. Genetic oscillations. A Doppler effect in embryonic pattern formation.

    Science.gov (United States)

    Soroldoni, Daniele; Jörg, David J; Morelli, Luis G; Richmond, David L; Schindelin, Johannes; Jülicher, Frank; Oates, Andrew C

    2014-07-11

    During embryonic development, temporal and spatial cues are coordinated to generate a segmented body axis. In sequentially segmenting animals, the rhythm of segmentation is reported to be controlled by the time scale of genetic oscillations that periodically trigger new segment formation. However, we present real-time measurements of genetic oscillations in zebrafish embryos showing that their time scale is not sufficient to explain the temporal period of segmentation. A second time scale, the rate of tissue shortening, contributes to the period of segmentation through a Doppler effect. This contribution is modulated by a gradual change in the oscillation profile across the tissue. We conclude that the rhythm of segmentation is an emergent property controlled by the time scale of genetic oscillations, the change of oscillation profile, and tissue shortening.

  8. Doppler effect of nonlinear waves and superspirals in oscillatory media.

    Science.gov (United States)

    Brusch, Lutz; Torcini, Alessandro; Bär, Markus

    2003-09-01

    Nonlinear waves emitted from a moving source are studied. A meandering spiral in a reaction-diffusion medium provides an example in which waves originate from a source exhibiting a back-and-forth movement in a radial direction. The periodic motion of the source induces a Doppler effect that causes a modulation in wavelength and amplitude of the waves ("superspiral"). Using direct simulations as well as numerical nonlinear analysis within the complex Ginzburg-Landau equation, we show that waves subject to a convective Eckhaus instability can exhibit monotonic growth or decay as well as saturation of these modulations depending on the perturbation frequency. Our findings elucidate recent experimental observations concerning superspirals and their decay to spatiotemporal chaos.

  9. Relativistic Doppler effect: universal spectra and zeptosecond pulses.

    Science.gov (United States)

    Gordienko, S; Pukhov, A; Shorokhov, O; Baeva, T

    2004-09-10

    We report on a numerical observation of the train of zeptosecond pulses produced by the reflection of a relativistically intense femtosecond laser pulse from the oscillating boundary of an overdense plasma because of the Doppler effect. These pulses promise to become unique experimental and technological tools since their length is of the order of the Bohr radius and the intensity is extremely high proportional, variant 10(19) W/cm(2). We present the physical mechanism, analytical theory, and direct particle-in-cell simulations. We show that the harmonic spectrum is universal: the intensity of nth harmonic scales as 1/n(p) for n<4gamma(2), where gamma is the largest gamma factor of the electron fluid boundary, and p=3 and p=5/2 for the broadband and quasimonochromatic laser pulses, respectively.

  10. Application of fiber interferometer in coherent Doppler lidar

    Institute of Scientific and Technical Information of China (English)

    Zongfeng Ma; Chunxi Zhang; Pan Ou; Guangming Luo; Zhaoyang Zhang

    2008-01-01

    @@ A novel coherent Doppler lidar (CDL) system based on single-mode fiber (SMF) components and instruments is presented to measure the speed of target. A fiber interferometer used in CDL system is reported.This fiber mixer is employed as a coherent receiver to resolve the shifts of signal-to-noise ratio (SNR) and mixing efficiency induced by backscattered field's wavefront error. For a certain wavelength, the maximum coupling efficiency between signal and SMF is determined by the ratio of pupil diameter to focal length of the coupling lens. The legible interference patterns and spectrum signals show that fiber interferometer is suitable to compensate for amplitude and phase vibrations. This robust coherent receiver can achieve improved CDL system performance with less transmitter power.

  11. Dynamic range studies and improvements for multiplexed photonic Doppler velocimetry

    Science.gov (United States)

    Miller, Edward Kirk; Lee, Kevin; Larson, Eric; Daykin, Edward

    2017-01-01

    We present studies of the dynamic range achievable with multiplexed photonic Doppler velocimetry (MPDV) measurements, and we demonstrate some techniques to extend the dynamic range. Improved dynamic range for MPDV measurements is needed in order to track the velocity of the free surface behind a cloud of ejecta, so we have undertaken theoretical and experimental studies of factors affecting dynamic range, particularly in cases where the large number of MPDV probe points precludes high illumination power on each channel. To quantify the potential dynamic range of a given MPDV configuration, we introduce a metric called the frequency-domain number of bits, FNOB, which is less stringent than the formally defined equivalent number of bits (ENOB). This new metric is simple to compute in the lab, and it is well suited to conventional PDV analysis, which does not require digitizer phase coherence beyond tens of nanoseconds.

  12. Neuroticism and vigilance revisited: A transcranial doppler investigation.

    Science.gov (United States)

    Mandell, Arielle R; Becker, Alexandra; VanAndel, Aaron; Nelson, Andrew; Shaw, Tyler H

    2015-11-01

    Selecting for vigilance assignments remains an important factor in human performance research. The current study revisits the potential relationship between vigilance performance and trait neuroticism, in light of two possible theories. The first theory suggests that neuroticism impairs vigilance performance by competing for available resources. The second theory, attentional control theory, posits that high neuroticism can result in similar or superior performance levels due to the allocation of compensatory effort. In the present study, Transcranial Doppler Sonography was used to investigate the neurophysiological underpinnings of neuroticism during a 12-min abbreviated vigilance task. Performance results were not modified by level of neuroticism, but high neuroticism was associated with higher initial CBFV levels and a greater CBFV decrement over time. These findings indicate that participants higher in neuroticism recruited additional cognitive resources in order to achieve similar performance, suggesting that there is more of an effect on processing efficiency than effectiveness.

  13. Photonic Doppler Velocimetry Multiplexing Techniques: Evaluation of Photonic Techniques

    Energy Technology Data Exchange (ETDEWEB)

    Edward Daykin

    2012-05-24

    This poster reports progress related to photonic technologies. Specifically, the authors developed diagnostic system architecture for a Multiplexed Photonic Doppler Velocimetry (MPDV) that incorporates frequency and time-division multiplexing into existing PDV methodology to provide increased channel count. Current MPDV design increases number of data records per digitizer channel 8x, and also operates as a laser-safe (Class 3a) system. Further, they applied heterodyne interferometry to allow for direction-of-travel determination and enable high-velocity measurements (>10 km/s) via optical downshifting. They also leveraged commercially available, inexpensive and robust components originally developed for telecom applications. Proposed MPDV architectures employ only commercially available, fiber-coupled hardware.

  14. Magnetic Doppler Imaging of He-strong star HD 184927

    CERN Document Server

    Yakunin, I; Bohlender, D; Kochukhov, O; Tsymbal, V

    2013-01-01

    We have employed an extensive new timeseries of Stokes I and V spectra obtained with the ESPaDOnS spectropolarimeter at the 3.6-m Canada-France-Hawaii Telescope to investigate the physical parameters, chemical abundance distributions and magnetic field topology of the slowly-rotating He-strong star HD 184927. We infer a rotation period of 9.53071+-0.00120 from H-alpha, H-beta, LSD magnetic measurements and EWs of helium lines. We used an extensive NLTE TLUSTY grid along with the SYNSPEC code to model the observed spectra and find a new value of luminosity. In this poster we present the derived physical parameters of the star and the results of Magnetic Doppler Imaging analysis of the Stokes I and V profiles. Wide wings of helium lines can be described only under the assumption of the presence of a large, very helium-rich spot.

  15. Laser Doppler flowmetry to measure changes in cerebral blood flow.

    Science.gov (United States)

    Sutherland, Brad A; Rabie, Tamer; Buchan, Alastair M

    2014-01-01

    Laser Doppler flowmetry (LDF) is a method by which relative cerebral blood flow (CBF) of the cortex can be measured. Although the method is easy to employ, LDF only measures relative CBF, while absolute CBF cannot be quantified. LDF is useful for investigating CBF changes in a number of different applications including neurovascular and stroke research. This chapter will prepare the reader for rodent experiments using LDF with two preparations. The closed skull preparation can be used to monitor CBF with an intact skull, but in adult rats, thinning of the skull is required to obtain an accurate cortical CBF signal. The open skull preparation requires a craniotomy to expose the surface of the brain and the LDF probe is held close to the surface to measure cerebral perfusion.

  16. Sub-Doppler cooling of sodium atoms in gray molasses

    Science.gov (United States)

    Colzi, Giacomo; Durastante, Gianmaria; Fava, Eleonora; Serafini, Simone; Lamporesi, Giacomo; Ferrari, Gabriele

    2016-02-01

    We report on the realization of sub-Doppler laser cooling of sodium atoms in gray molasses using the D1 optical transition (3 s 1/2 2S →3 p 1/2 2P) at 589.8 nm. The technique is applied to samples containing 3 ×109 atoms, previously cooled to 350 μ K in a magneto-optical trap, and it leads to temperatures as low as 9 μ K and phase-space densities in the range of 10-4. The capture efficiency of the gray molasses is larger than 2/3, and we observe no density-dependent heating for densities up to 1011cm-3 .

  17. Doppler ultrasound study and venous mapping in chronic venous insufficiency.

    Science.gov (United States)

    García Carriazo, M; Gómez de las Heras, C; Mármol Vázquez, P; Ramos Solís, M F

    2016-01-01

    Chronic venous insufficiency of the lower limbs is very prevalent. In recent decades, Doppler ultrasound has become the method of choice to study this condition, and it is considered essential when surgery is indicated. This article aims to establish a method for the examination, including venous mapping and preoperative marking. To this end, we review the venous anatomy of the lower limbs and the pathophysiology of chronic venous insufficiency and explain the basic hemodynamic concepts and the terminology required to elaborate a radiological report that will enable appropriate treatment planning and communication with other specialists. We briefly explain the CHIVA (the acronym for the French term "cure conservatrice et hémodynamique de l'insuffisance veineuse en ambulatoire"=conservative hemodynamic treatment for chronic venous insufficiency) strategy, a minimally invasive surgical strategy that aims to restore correct venous hemodynamics without resecting the saphenous vein.

  18. Design and performance simulation of a molecular Doppler wind lidar

    Institute of Scientific and Technical Information of China (English)

    Fahua Shen; Hyunki Cha; Jihui Dong; Dukhyeon Kim; Dongsong Sun; Sung Ok Kwon

    2009-01-01

    A mobile molecular Doppler wind lidar at an eye-safe wavelength of 355 nm based on double-edge technique is being built in Hefei (China) for wind measurement from 10-to 40-km altitude. The structure of this lidar system is described. A triple Fabry-Perot etalon is employed as a frequency discriminator whose parameters are optimized. The receiver system is designed to achieve compactness and stability by putting in a standard 19-inch socket bench. Simulation results show that within the wind speed dynamic range of ±100 m/s, the horizontal wind errors due to noise are less than 1 m/s below 20-km altitude for 100-m vertical resolution, and less than 5.5 m/s from 20 km up to 40 km for 500-m vertical resolution with 400-mJ laser energy, 30-min temporal resolution, and a 45-cm aperture telescope.

  19. Development of all-solid coherent Doppler wind lidar

    Institute of Scientific and Technical Information of China (English)

    Xiaopeng Zhu; Jiqiao Liu; Decang Bi; Jun Zhou; Weifeng Diao; Weibiao Chen

    2012-01-01

    A 1064-nm pulsed coherent Doppler lidar (CDL) prototype is developed to measure short range wind speed in the lower altitude troposphere layer The CDL system adopts an injection seeded Nd:YAG laser with the pulse duration of 80 ns,single pulse energy of 0.5 m J,and pulse repetition rate of 200 Hz.Speed calibration experiments are implemented to obtain a speed accuracy of 0.3 m/s using a hard target.Data analysis results show that the CDL system can obtain a line-of-sight wind velocity at a range of 30 to 500m with the range resolution of 40 m and 38 pulses accumulation.

  20. Zeeman Doppler maps: the true and the spurious

    CERN Document Server

    Stift, Martin J

    2016-01-01

    Numerical models of atomic diffusion in magnetic atmospheres of ApBp stars predict abundance structures that differ from the empirical abundance maps derived with (Zeeman) Doppler mapping (ZDM). Whereas both equilibrium abundance stratification calculations and stationary solutions to the time-dependent diffusion equations predict (warped) rings about the magnetic equator in dipole-like magnetic geometries, spot-like structures dominate published maps. An in-depth analysis of this apparent disagreement investigates the detectability by means of ZDM of a variety of abundance structures, including (warped) rings predicted by theory, but also some complex spot-like structures. As it turns out, a number of published maps have to be considered spurious either because strong magnetic fields have been neglected or because they are based on spectra where photon noise dominates over the signal of the alleged abundance structures. Even when spectra of high signal to noise ratio are available, it can prove altogether im...