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

    Directory of Open Access Journals (Sweden)

    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. 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.

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

    OpenAIRE

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

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

    OpenAIRE

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

    2008-01-01

    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 ...

  5. Transcranial Doppler for patent foramen ovale screening: is there a good correlation with transesophageal echocardiography? Doppler transcraniano contrastado para triagem de forame oval patente: existe boa correlação com ecocardiograma transesofágico?

    Directory of Open Access Journals (Sweden)

    Marcos Christiano Lange

    2008-12-01

    Full Text Available Right-to-left shunt (RLS can be identified by contrast-enhanced transcranial Doppler (cTCD in patent foramen ovale (PFO patients. AIM: To evaluate cTCD for PFO screening comparing it to cTEE. METHOD: 45 previous cTCD performed for PFO diagnosis and correlated its findings with cTEE. Patients were submitted to a cTCD standardized technique and were divided in two groups according to RLS: Group 1, patients with a positive RLS and Group 2 when RLS was negative. RESULTS: 29 (65% patients were included in group 1 and 16 (35% in group 2. PFO confirmation by cTEE was performed in 28 (62% patients. cTCD had a 92.85% sensitivity, 82.35% specificity, 89.65% positive predictive value and 87.5% negative predictive value when compared to cTEE for PFO diagnosis. CONCLUSION: Standardized technique cTCD allows for RLS visualization in PFO patients with a good correlation with cTEE and can be used as a screening test before cTEE.A comunicação direita-esquerda (CDE pode ser identificada por Doppler transcraniano contrastado (DTCc em pacientes com forame oval patente (FOP. OBJETIVOS: Analisar o DTCc para triagem de FOP comparado a ecocardiografia transesofágica (ETEc. MÉTODO: Realizamos 45 exames de DTCc para diagnóstico de FOP e correlacionamos com os achados do ETEc. Os pacientes foram submetidos a técnica padronizada e divididos em dois grupos conforme a positividade do exame. RESULTADOS: 29 (65% pacientes foram incluídos no grupo 1 (CDE positiva e 16 (35% no grupo 2 (CDE negativa. A confirmação do FOP pelo ETEc ocorreu em 28 (62% pacientes. O DTCc apresentou sensibilidade de 92,85%, especificidade de 82,35%, valor preditivo positivo de 89,65% e valor preditivo negativo de 87,5% comparado ao ETEc para o diagnóstico de FOP. CONCLUSÃO: A técnica padronizada de DTCc possibilita a visualização de CDE em pacientes com FOP com boa correlação com o ETEc.

  6. Electron Emission by Doppler-Mediated Formation of Doubly Excited H -** in Grazing Incidence of Protons on Clean Al(111)

    Czech Academy of Sciences Publication Activity Database

    Lörinčík, Jan; Šroubek, Zdeněk; Aumayr, H.; Winter, H. P.

    2001-01-01

    Roč. 54, č. 5 (2001), s. 633-639. ISSN 0295-5075 R&D Projects: GA AV ČR IAA1067801 Institutional research plan: CEZ:AV0Z4040901 Keywords : ion scattering from surfaces * Doppler-mediated formation * Al(111) Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.304, year: 2001

  7. O ecocardiograma na terapia de ressincronização cardíaca El ecocardiograma en la terapia de resincronización cardiaca Echocardiography in cardiac resynchronization therapy

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    Viviane Cordeiro Veiga

    2009-10-01

    Full Text Available A terapia de ressincronização cardíaca (TRC tem sido uma opção efetiva nos pacientes com insuficiência cardíaca avançada. No entanto 20% a 30% dos pacientes não apresentam benefícios nessa terapêutica. Critérios clínicos, eletrocardiográficos e ecocardiográficos têm sido estudados na tentativa de selecionar os pacientes que serão beneficiados com a ressincronização cardíaca, mas o ecocardiograma tem papel importante tanto na seleção quanto na avaliação e otimização dessa terapêutica. O objetivo desta revisão é descrever os principais parâmetros ecocardiográficos utilizados na avaliação da terapia de ressincronização cardíaca.La terapia de resincronización cardiaca (TRC viene siendo una opción efectiva en los pacientes con insuficiencia cardiaca avanzada. Sin embargo, del 20% al 30% de los pacientes no presentan beneficios en esa terapéutica. Criterios clínicos, electrocardiográficos y ecocardiográficos están siendo estudiados en el intento de seleccionar a los pacientes que se beneficiarán con la resincronización cardiaca, pero lo ecocardiograma juega un rol importante tanto en la selección como en la evaluación y la optimización de esa terapéutica. El objetivo de esta revisión es describir los principales parámetros ecocardiográficos utilizados en la evaluación de la terapia de resincronización cardiaca.Cardiac resynchronization therapy has been an effective option in patients with advanced heart failure. However, 20 to 30% of the patients do not benefit from this therapy. Clinical, electrocardiographic and echocardiographic criteria have been studied in an attempt to select patients who will benefit from a cardiac resynchronization therapy, and the echocardiogram is important both in the selection and in the evaluation and optimization of the therapy. The objective of this review is to describe the main echocardiographic parameters used in the evaluation of the cardiac resynchronization

  8. 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

  9. Betabloqueador tópico pode determinar resultados inconclusivos no ecocardiograma sob estresse com dobutamina em pacientes com glaucoma Topical betablocker use can result in inconclusive dobutamine stress echocardiography in patients with glaucoma

    Directory of Open Access Journals (Sweden)

    Adriana Cordovil

    2007-07-01

    Full Text Available O ecocardiograma sob estresse com dobutamina é um método bem estabelecido para avaliar doença arterial coronária, cuja sensibilidade tem sido potencializada pela adição de atropina no final do protocolo. Indivíduos com glaucoma, doença com alta prevalência em pacientes cardiopatas com mais de 40 anos, não podem se beneficiar do uso de atropina por ser contra-indicada neste grupo. Além disso, estes indivíduos são tratados freqüentemente com betabloqueadores tópicos (colírios, que podem exercer efeitos sistêmicos diminuindo a freqüência cardíaca, pressão arterial e capacidade pulmonar. O objetivo do nosso trabalho foi verificar se a ocorrência de um possível efeito sistêmico causado por estes colírios, causando baixa resposta cronotrópica, poderia determinar resultados inconclusivos no ecocardiograma sob estresse pela dobutamina nestes pacientes com glaucoma.Dobutamine stress echocardiography is a well-established method to assess coronary artery disease, of which sensitivity has been enhanced by adding atropine at the end of the protocol. Individuals with glaucoma, a disease with a high prevalence in patients with cardiac diseases older than 40 years, cannot benefit from the use of atropine as it is contraindicated for this group of patients. Additionally, these individuals are often treated with topical betablockers (eye drops, which can have systemic effects by decreasing cardiac frequency, blood pressure and pulmonary capacity. The aim of our study was to verify whether a possible systemic effect caused by the use of these eye drops, yielding a low chronotropic response, could result in inconclusive dobutamine stress echocardiography in patients with glaucoma.

  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 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

    Directory of Open Access Journals (Sweden)

    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

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

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    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

  13. Doppler tracking

    Science.gov (United States)

    Thomas, Christopher Jacob

    This study addresses the development of a methodology using the Doppler Effect for high-resolution, short-range tracking of small projectiles and vehicles. Minimal impact on the design of the moving object is achieved by incorporating only a transmitter in it and using ground stations for all other components. This is particularly useful for tracking objects such as sports balls that have configurations and materials that are not conducive to housing onboard instrumentation. The methodology developed here uses four or more receivers to monitor a constant frequency signal emitted by the object. Efficient and accurate schemes for filtering the raw signals, determining the instantaneous frequencies, time synching the frequencies from each receiver, smoothing the synced frequencies, determining the relative velocity and radius of the object and solving the nonlinear system of equations for object position in three dimensions as a function of time are developed and described here.

  14. Doppler-like effect and doubtful expansion of universe

    OpenAIRE

    Szaraniec, Edward

    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 theo...

  15. Clinical Doppler ultrasound

    International Nuclear Information System (INIS)

    The authors begin with the basics: how Doppler signals are formed, reflected, and refracted - and how those facts apply to clinical practice; anatomy (blood and blood flow), the Doppler equation (explained from a radiologic, rather than a mathematical, perspective); and approaches to Doppler signal production. The available methods of signal processing - including audio, multifilter analysis, zero-crossing detection, autocorrelation, and the Fast Fourier Transform, as well as more sophisticated techniques of duplex and color flow imaging - are covered with an eye to helping the ultrasonographer obtain the most reliable and artifact-free information from every Doppler reading

  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. Test measurements of modernized version of two-detector Doppler spectrometer

    International Nuclear Information System (INIS)

    Basing on electronic analogue modules in adding and subtracting branches of pulses, a modernized two-detector Doppler spectrometer has been constructed using only one multichannel analyser. Doppler spectra for Al. Ni, Ag have been measured. ACARFIT computer program was used to compare the Doppler and angular correlation of annihilation radiation results. (author)

  18. Planetary Doppler Imaging

    Science.gov (United States)

    Murphy, N.; Jefferies, S.; Hart, M.; Hubbard, W. B.; Showman, A. P.; Hernandez, G.; Rudd, L.

    2014-12-01

    Determining the internal structure of the solar system's gas and ice giant planets is key to understanding their formation and evolution (Hubbard et al., 1999, 2002, Guillot 2005), and in turn the formation and evolution of the solar system. While internal structure can be constrained theoretically, measurements of internal density distributions are needed to uncover the details of the deep interior where significant ambiguities exist. To date the interiors of giant planets have been probed by measuring gravitational moments using spacecraft passing close to, or in orbit around the planet. Gravity measurements are effective in determining structure in the outer envelope of a planet, and also probing dynamics (e.g. the Cassini and Juno missions), but are less effective in probing deep structure or the presence of discrete boundaries. A promising technique for overcoming this limitation is planetary seismology (analogous to helioseismology in the solar case), postulated by Vorontsov, 1976. Using trapped pressure waves to probe giant planet interiors allows insight into the density and temperature distribution (via the sound speed) down to the planetary core, and is also sensitive to sharp boundaries, for example at the molecular to metallic hydrogen transition or at the core-envelope interface. Detecting such boundaries is not only important in understanding the overall structure of the planet, but also has implications for our understanding of the basic properties of matter at extreme pressures. Recent Doppler measurements of Jupiter by Gaulme et al (2011) claimed a promising detection of trapped oscillations, while Hedman and Nicholson (2013) have shown that trapped waves in Saturn cause detectable perturbations in Saturn's C ring. Both these papers have fueled interest in using seismology as a tool for studying the solar system's giant planets. To fully exploit planetary seismology as a tool for understanding giant planet structure, measurements need to be made

  19. 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...... weaknesses, perhaps the greatest being that in conventional systems, the velocities measured and thus displayed are the components of the flow velocity directly towards or away from the transducer, while ideally the method would give information about the magnitude and direction of the three-dimensional flow...... 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...

  20. Cosmology with Doppler Lensing

    OpenAIRE

    Bacon, David; Andrianomena, Sambatra; Clarkson, Chris; Bolejko, C.; Maartens, Roy

    2014-01-01

    Doppler lensing is the apparent change in object size and magnitude due to peculiar velocities. Objects falling into an overdensity appear larger on its near side, and smaller on its far side, than typical objects at the same redshifts. This effect dominates over the usual gravitational lensing magnification at low redshift. Doppler lensing is a promising new probe of cosmology, and we explore in detail how to utilize the effect with forthcoming surveys. We present cosmological simulations of...

  1. Rotational Doppler Effect

    OpenAIRE

    Halder, Amit

    2002-01-01

    A monochromatic linear source of light is rotated with certain angular frequency and when such light is analysed after reflection then a change of frequency or wavelength may be observed depending on the location of the observer. This change of frequency or wavelength is different from the classical Doppler effect [1] or relativistic Doppler effect [2]. The reason behind this shift in wavelength is that a certain time interval observed by an observer in the rotating frame is different from th...

  2. Ultrasonic Doppler Modes

    Science.gov (United States)

    Tortoli, Piero; Fidanzati, Paolo; Luca, Bassi

    Any US equipment includes Doppler facilities capable of providing information about moving structures inside the human body. In most cases, the primary interest is in the investigation of blood flow dynamics, since this may be helpful for early diagnosis of cardiovascular diseases. However, there is also an increasing interest in tracking the movements of human tissues, since such movements can give an indirect evaluation of their elastic properties, which are valuable indicators of the possible presence of pathologies. This paper aims at presenting an overview of the different ways in which the Doppler technique has been developed and used in medical ultrasound (US), from early continuous wave (CW) systems to advanced pulsed wave (PW) colour-Doppler equipment. In particular, the most important technical features and clinical applications of CW, single-gate PW, multi-gate PW and flow-imaging systems are reviewed. The main signal processing approaches used for detection of Doppler frequencies are described, including time-domain and frequency-domain (spectral) methods, as well as novel strategies like, e.g., harmonic Doppler mode, which have been recently introduced to exploit the benefits of US contrast agents.

  3. 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.

  4. Doppler-suuntima-algoritmi

    OpenAIRE

    Rekis, Matti

    2014-01-01

    Doppler-ilmiö aiheuttaa havaitsijan ja signaalilähteen välisen suhteellisen liikkeen seurauksena taajuusvääristymää lähteen alkuperäisestä signaalista. Tämä mm. doppler-siirtymäksi kutsuttu vääristymä voidaan havaita signaalilähteen taajuudessa, aallonpituudessa ja vaiheessa. Doppler-siirtymän suuruuteen ja suuntaan vaikuttaa se, kasvaako vai pieneneekö havaitsijan ja lähteen välinen etäisyys sekä niiden välinen suhteellinen nopeus. Tätä ilmiötä voidaan hyödyntää mm. radiolähettimen paikantam...

  5. 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

  6. Doppler ion program description

    International Nuclear Information System (INIS)

    The Doppler spectrometer is a conventional Czerny-Turner grating spectrometer with a 1024 channel multiple detector. Light is dispersed across the detector, and its output yields a spectrum covering approximately 200 A. The width of the spectral peak is directly proportional to the temperature of the emitting ions, and determination of the impurity ion temperature allows one to infer the plasma ion temperature. The Doppler ion software system developed at General Atomic uses a TRACOR Northern 1710-31 and an LSI-11/2. The exact configuration of Doublet III is different from TRACOR Northern systems at other facilities

  7. Doppler Cooling a Microsphere

    OpenAIRE

    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...

  8. Polarimetric Doppler Weather Radar

    Science.gov (United States)

    Bringi, V. N.; Chandrasekar, V.

    2001-10-01

    This work provides a detailed introduction to the principles of Doppler and polarimetric radar, focusing in particular on their use in the analysis of weather systems. The authors first discuss underlying topics such as electromagnetic scattering, polarization, and wave propagation. They then detail the engineering aspects of pulsed Doppler polarimetric radar, before examining key applications in meteorology and remote sensing. The book is aimed at graduate students of electrical engineering and atmospheric science as well as practitioners involved in the applications of polarimetric radar.

  9. Doppler blood flow indicator

    OpenAIRE

    Byrtus, David

    2014-01-01

    This bachelor´s thesis deals with basis of ultra-acoustics. The project presents basic information about Doppler effect. It describes the methods of processing and analyzing of velocity and direction of blood at doppler’s systems with modulated and unmodulated carrier wave. The project presents the system design of non-directional doppler indicator with unmodulated carrier wave for 8 MHz frequency, generating intensity of ultrasound 100 mW/cm2 and diameter D-shaped transmitting transducer 8 m...

  10. Doppler-musical instrument

    International Nuclear Information System (INIS)

    We propose a possible ultra-high energy resolution backscattering spectrometer optimized to spallation neutron source. A combination of multi monochromator crystal and Doppler drive provides considerable neutron flux, together with the reasonable energy range -30 < E < 30 μeV, even when the ultra-high energy resolution of ΔE∼0.03 μeV is attained. (author)

  11. HF Doppler observations

    Energy Technology Data Exchange (ETDEWEB)

    Kikuchi, T.; Sugiuchi, H.; Ishimine, T.; Maeno, H.; Honma, S.

    1986-12-01

    This paper reports the solar flare and geomagnetic storm effects on the frequency of JJY signals received at Okinawa (f = 15 MHz) and Kokubunji (f = 5 and 8 MHz) during the period of June-September 1982. The increase in the electron density due to solar flares is deduced from the Doppler frequency deviation of 1 Hz as 2 x 10/sup 15/ electrons/m/sub 2/ below the reflection height. The result is in good agreement with the observation of the total electron content by the Faraday rotation measurements. On July 13, 1982, an abrupt increase of 0.8 Hz in frequency followed by a decrease of 0.6 Hz was observed in association with the huge storm sudden commencement. This fact indicates a successive transmission of westward electric field of 1.5 mV/m and eastward electric field of 1.1 mV/m from the outer magnetosphere to the low latitude ionosphere. It is shown that the decreases in Doppler frequency were associated with geomagnetic bays. The strength of the electric field (1.8 mV/m) derived from the Doppler frequency deviation is 20% of that of the electric field which is required to produce ionospheric electric currents responsible for the geomagnetic field variation on the ground. The large amplitude Doppler frequency oscillations of period of 1-1.5 h were observed at Kokubunji and Okinawa with a delay time of 20-25 min during the geomagnetic storm on September 6, 1982. It is suggested that the large-scale TID (Travelling Ionospheric Disturbance) with a phase velocity of 600 m/s and a wavelength of 2000 km is produced at high latitudes and is propagated to low latitudes.

  12. Quantitative Laser Doppler Flowmetry

    OpenAIRE

    Fredriksson, Ingemar

    2009-01-01

    Laser Doppler flowmetry (LDF) is virtually the only non-invasive technique, except for other laser speckle based techniques, that enables estimation of the microcirculatory blood flow. The technique was introduced into the field of biomedical engineering in the 1970s, and a rapid evolvement followed during the 1980s with fiber based systems and improved signal analysis. The first imaging systems were presented in the beginning of the 1990s. Conventional LDF, although unique in many aspects an...

  13. Laser Doppler imaging, revisited

    OpenAIRE

    Atlan, Michael; Gross, Michel

    2006-01-01

    International audience We present a detection scheme designed to perform laser Doppler imaging in a wide-field configuration, aimed at slow flows characterization. The optical field which carries a spectral information about the local scatterers dynamic state that results from momentum transfer at each scattering event, is analyzed in the temporal frequencies domain. The setup is based on heterodyne off-axis digital holography.

  14. Holographic laser Doppler ophthalmoscopy

    CERN Document Server

    Simonutti, Manuel; Sahel, J A; Gross, Michel; Samson, Benjamin; Magnain, Caroline; Atlan, Michael; 10.1364/OL.35.001941

    2010-01-01

    We report laser Doppler ophthalmoscopic fundus imaging in the rat eye with near-IR heterodyne holography. Sequential sampling of the beat of the reflected radiation against a frequency-shifted optical local oscillator is made onto an array detector. Wide-field maps of fluctuation spectra in the 10 Hz to 25 kHz band exhibit angiographic contrasts in the retinal vascular tree without requirement of an exogenous marker.

  15. Impacto do ecocardiograma transesofágico intraoperatório na mortalidade em cirurgia de revascularização do miocárdio com circulação extracorpórea

    Directory of Open Access Journals (Sweden)

    Marcello Fonseca Salgado Filho

    2013-10-01

    Full Text Available OBJETIVO: avaliar as taxas de mortalidade e morbidade de doentes submetidos à revascularização do miocárdio (RVM com circulação extracorpórea (CEC que utilizaram rotineiramente o ecocardiograma transesofágico intraoperatório (ETEio. MÉTODOS: estudo retrospectivo, observacional com avaliação de prontuários de 360 doentes no período entre abril de 2010 a abril de 2012. Foram analisados: idade, peso, altura sexo, EUROscore, diabete melito, fração de ejeção e artérias acometidas. Os desfechos foram compilados no intra e no pós-operatório (infarto do miocárdio, acidente vascular cerebral, disfunção renal, hemodiálise, fibrilação atrial, tempo de internação no centro de tratamento intensivo. RESULTADOS: foram incluídos 53 doentes, com 27 recebendo a monitoração. Foram excluídos 307 porque não foram operados pela mesma equipe cirúrgica. Os dois grupos foram homogêneos quanto a idade, peso e sexo, porém, a fração ejeção foi menor no grupo que recebeu o ecotransesofágico (G ETEio: 56,3%; G Não ETEio: 65,9% ± 11; p=0,01. Nos doentes em que não foi utilizado o ETEio, a mortalidade foi maior (G ETEio: 0% e G Não ETEio: 7,6%; p=0,01. Não houve diferença significativa entre os grupos quanto à incidência de acidente vascular encefálico, infarto agudo do miocárdio, fibrilação atrial aguda e lesão renal. CONCLUSÃO: a utilização do ecocardiograma transesofágico intraoperatório em pacientes submetidos à revascularização do miocárdio, com circulação extracorpórea, diminuiu a mortalidade perioperatória; orientou quanto a utilização dos fármacos inotrópicos e vasodilatadores e contribuiu para uma melhor evolução dos doentes.

  16. 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.

  17. Calculation of doppler coefficient of reactivity by WIMS code

    International Nuclear Information System (INIS)

    The Doppler coefficient of reactivity is an important factor in prediction of several transients in light water reactors. Some of the past studies raised the question about the 10% uncertainty that traditionally was taken in calculations of Doppler coefficient by LWR lattice code. In order to bridge the gap of lack of accurate benchmark problem to evaluate the accuracy of Doppler effect, Mosteller et al. proposed a computational benchmark problem of Doppler coefficient to evaluate the accuracy and consistency of LWR lattice physics code. In this paper we present the results obtained from WIMS-D4 lattice code and compare it with those obtained by CELL-2 lattice code part of the EPRI-PRESS reactor physics package. The results obtained from the Monte Carlo code MCNP-3A served as reference for both cases, and was taken from ref 1. (authors). 4 refs., 2 figs., 1 tab

  18. Laser doppler perfusion imaging

    Energy Technology Data Exchange (ETDEWEB)

    Waardell, K.

    1992-01-01

    Recording of tissue perfusion is important in assessing the influence of peripheral vascular diseases on the microcirculation. This thesis reports on a laser doppler perfusion imager based on dynamic light scattering in tissue. When a low power He-Ne laser beam sequentally scans the tissue, moving blood cells generate doppler components in the back-scattered light. A fraction of this light is detected by a photodetector and converted into an electrical signal. In the processor, a signal proportional to the tissue perfusion at each measurement site is calculated and stored. When the scanning procedure is completed, a color-coded perfusion image is presented on a monitor. To convert important aspects of the perfusion image into more quantitative parameters, data analysis functions are implemented in the software. A theory describing the dependence of the distance between individual measurement points and detector on the system amplification factor is proposed and correction algorithms are presented. The performance of the laser doppler perfusion imager was evaluated using a flow simulator. A linear relationship between processor output signal and flow through the simulator was demonstrated for blood cell concentrations below 0.2%. The median sampling depth of the laser beam was simulated by a Monte Carlo technique and estimated to 235 {mu}m. The perfusion imager has been used in the clinic to study perfusion changes in port wine stains treated with argon laser and to investigate the intensity and extension of the cutaneous axon reflex response after electrical nerve stimulation. The fact that perfusion can be visualized without touching the tissue implies elimination of sterilization problems, thus simplifying clinical investigations of perfusion in association with diagnosis and treatment of peripheral vascular diseases. 22 refs.

  19. Laser doppler perfusion imaging

    Energy Technology Data Exchange (ETDEWEB)

    Waardell, K.

    1992-11-01

    Recording of tissue perfusion is important in assessing the influence of peripheral vascular diseases on the microcirculation. This thesis reports on a laser doppler perfusion imager based on dynamic light scattering in tissue. When a low power He-Ne laser beam sequentally scans the tissue, moving blood cells generate doppler components in the back-scattered light. A fraction of this light is detected by a photodetector and converted into an electrical signal. In the processor, a signal proportional to the tissue perfusion at each measurement site is calculated and stored. When the scanning procedure is completed, a color-coded perfusion image is presented on a monitor. To convert important aspects of the perfusion image into more quantitative parameters, data analysis functions are implemented in the software. A theory describing the dependence of the distance between individual measurement points and detector on the system amplification factor is proposed and correction algorithms are presented. The performance of the laser doppler perfusion imager was evaluated using a flow simulator. A linear relationship between processor output signal and flow through the simulator was demonstrated for blood cell concentrations below 0.2%. The median sampling depth of the laser beam was simulated by a Monte Carlo technique and estimated to 235 {mu}m. The perfusion imager has been used in the clinic to study perfusion changes in port wine stains treated with argon laser and to investigate the intensity and extension of the cutaneous axon reflex response after electrical nerve stimulation. The fact that perfusion can be visualized without touching the tissue implies elimination of sterilization problems, thus simplifying clinical investigations of perfusion in association with diagnosis and treatment of peripheral vascular diseases. 22 refs.

  20. Laser doppler perfusion imaging

    International Nuclear Information System (INIS)

    Recording of tissue perfusion is important in assessing the influence of peripheral vascular diseases on the microcirculation. This thesis reports on a laser doppler perfusion imager based on dynamic light scattering in tissue. When a low power He-Ne laser beam sequentally scans the tissue, moving blood cells generate doppler components in the back-scattered light. A fraction of this light is detected by a photodetector and converted into an electrical signal. In the processor, a signal proportional to the tissue perfusion at each measurement site is calculated and stored. When the scanning procedure is completed, a color-coded perfusion image is presented on a monitor. To convert important aspects of the perfusion image into more quantitative parameters, data analysis functions are implemented in the software. A theory describing the dependence of the distance between individual measurement points and detector on the system amplification factor is proposed and correction algorithms are presented. The performance of the laser doppler perfusion imager was evaluated using a flow simulator. A linear relationship between processor output signal and flow through the simulator was demonstrated for blood cell concentrations below 0.2%. The median sampling depth of the laser beam was simulated by a Monte Carlo technique and estimated to 235 μm. The perfusion imager has been used in the clinic to study perfusion changes in port wine stains treated with argon laser and to investigate the intensity and extension of the cutaneous axon reflex response after electrical nerve stimulation. The fact that perfusion can be visualized without touching the tissue implies elimination of sterilization problems, thus simplifying clinical investigations of perfusion in association with diagnosis and treatment of peripheral vascular diseases. 22 refs

  1. 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.

  2. 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.

  3. Doppler Beats or Interference Fringes?

    Science.gov (United States)

    Kelly, Paul S.

    1979-01-01

    Discusses the following: another version of Doppler beats; alternate proof of spin-1 sin-1/2 problems; some mechanisms related to Dirac's strings; Doppler redshift in oblique approach of source and observer; undergraduate experiment on noise thermometry; use of the time evolution operator; resolution of an entropy maximization controversy;…

  4. Adaptive Spectral Doppler Estimation

    DEFF Research Database (Denmark)

    Gran, Fredrik; Jakobsson, Andreas; Jensen, Jørgen Arendt

    2009-01-01

    In this paper, 2 adaptive spectral estimation techniques are analyzed for spectral Doppler ultrasound. The purpose is to minimize the observation window needed to estimate the spectrogram to provide a better temporal resolution and gain more flexibility when designing the data acquisition sequence....... The methods can also provide better quality of the estimated power spectral density (PSD) of the blood signal. Adaptive spectral estimation techniques are known to pro- vide good spectral resolution and contrast even when the ob- servation window is very short. The 2 adaptive techniques are tested and...... compared with the averaged periodogram (Welch’s method). The blood power spectral capon (BPC) method is based on a standard minimum variance technique adapted to account for both averaging over slow-time and depth. The blood amplitude and phase estimation technique (BAPES) is based on finding a set of...

  5. Dual-Doppler Feasibility Study

    Science.gov (United States)

    Huddleston, Lisa L.

    2012-01-01

    When two or more Doppler weather radar systems are monitoring the same region, the Doppler velocities can be combined to form a three-dimensional (3-D) wind vector field thus providing for a more intuitive analysis of the wind field. A real-time display of the 3-D winds can assist forecasters in predicting the onset of convection and severe weather. The data can also be used to initialize local numerical weather prediction models. Two operational Doppler Radar systems are in the vicinity of Kennedy Space Center (KSC) and Cape Canaveral Air Force Station (CCAFS); these systems are operated by the 45th Space Wing (45 SW) and the National Weather Service Melbourne, Fla. (NWS MLB). Dual-Doppler applications were considered by the 45 SW in choosing the site for the new radar. Accordingly, the 45th Weather Squadron (45 WS), NWS MLB and the National Aeronautics and Space Administration tasked the Applied Meteorology Unit (AMU) to investigate the feasibility of establishing dual-Doppler capability using the two existing systems. This study investigated technical, hardware, and software requirements necessary to enable the establishment of a dual-Doppler capability. Review of the available literature pertaining to the dual-Doppler technique and consultation with experts revealed that the physical locations and resulting beam crossing angles of the 45 SW and NWS MLB radars make them ideally suited for a dual-Doppler capability. The dual-Doppler equations were derived to facilitate complete understanding of dual-Doppler synthesis; to determine the technical information requirements; and to determine the components of wind velocity from the equation of continuity and radial velocity data collected by the two Doppler radars. Analysis confirmed the suitability of the existing systems to provide the desired capability. In addition, it is possible that both 45 SW radar data and Terminal Doppler Weather Radar data from Orlando International Airport could be used to alleviate any

  6. High Resolution Doppler Lidar

    Science.gov (United States)

    1996-01-01

    This Grant supported the development of an incoherent lidar system to measure winds and aerosols in the lower atmosphere. During this period the following activities occurred: (1) an active feedback system was developed to improve the laser frequency stability; (2) a detailed forward model of the instrument was developed to take into account many subtle effects, such as detector non-linearity; (3) a non-linear least squares inversion method was developed to recover the Doppler shift and aerosol backscatter without requiring assumptions about the molecular component of the signal; (4) a study was done of the effects of systematic errors due to multiple etalon misalignment. It was discovered that even for small offsets and high aerosol loadings, the wind determination can be biased by as much as 1 m/s. The forward model and inversion process were modified to account for this effect; and (5) the lidar measurements were validated using rawinsonde balloon measurements. The measurements were found to be in agreement within 1-2 m/s.

  7. Lorentz invariance and the rotor Doppler shift experiments

    International Nuclear Information System (INIS)

    It is shown that 'Rotor Doppler shift Experiments' provide a way to distinguish Einstein's Special Relativity (SR) from Lorentz's Aether Theory (LAT). Misconceptions in previous papers involving the Doppler shift experiments are examined. The theoretical and experimental data available on rotor Doppler shift experiments are analysed. Two models of SR violating theories are used to predict the output of a recently proposed experiment by Torr and Kolen. The first one corresponds to (strict) LAT and the other to an extended form of LAT. Contrary to the first, the second theory leads to results in agreement with the preliminary experimental data of Torr et al indicating a breakdown both of SR and strict LAT. (Author)

  8. 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

  9. Current-induced spin wave Doppler shift

    Science.gov (United States)

    Bailleul, Matthieu

    2010-03-01

    In metal ferromagnets -namely Fe, Co and Ni and their alloys- magnetism and electrical transport are strongly entangled (itinerant magnetism). This results in a number of properties such as the tunnel and giant magnetoresistance (i.e. the dependence of the electrical resistance on the magnetic state) and the more recently addressed spin transfer (i.e. the ability to manipulate the magnetic state with the help of an electrical current). The spin waves, being the low-energy elementary excitations of any ferromagnet, also exist in itinerant magnets, but they are expected to exhibit some peculiar properties due the itinerant character of the carriers. Accessing these specific properties experimentally could shed a new light on the microscopic mechanism governing itinerant magnetism, which -in turn- could help in optimizing material properties for spintronics applications. As a simple example of these specific properties, it was predicted theoretically that forcing a DC current through a ferromagnetic metal should induce a shift of the frequency of the spin waves [1,2]. This shift can be identified to a Doppler shift undergone by the electron system when it is put in motion by the electrical current. We will show how detailed spin wave measurements allow one to access this current-induced Doppler shift [3]. From an experimental point of view, we will discuss the peculiarities of propagating spin wave spectroscopy experiments carried out at a sub-micrometer length-scale and with MHz frequency resolution. Then, we will discuss the measured value of the Doppler shift in the context of both the old two-current model of spin-polarized transport and the more recent model of adiabatic spin transfer torque. [4pt] [1] P.Lederer and D.L. Mills, Phys.Rev. 148, 542 (1966).[0pt] [2] J. Fernandez-Rossier et al., Phys. Rev. B 69, 174412 (2004)[0pt] [3] V. Vlaminck and M. Bailleul, Science 322, 410 (2008).

  10. 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.

  11. 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

  12. Doppler Ultrasound Doppler and their applications in maternal medicine

    International Nuclear Information System (INIS)

    In this paper the technical aspects and physical principles of Doppler ultrasound are discussed, as well as the analysis that can be made from the quantitative and qualitative data. Finally, its utility in perinatal medicine is reviewed with emphasis in the clinical implications

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

    DEFF Research Database (Denmark)

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

    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...

  14. 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...

  15. Implementation of Doppler backscattering for MAST

    CERN Document Server

    Hillesheim, J C; Peebles, W A; Meyer, H; Meakins, A; Field, A R; Dunai, D; Carr, M; Hawkes, N

    2014-01-01

    A sixteen channel millimeter-wave diagnostic system, covering the frequency range 30-75 GHz, has been installed on MAST [B. Lloyd et al., Nucl. Fusion 43, 1665 (2003)] and has been successfully used for both Doppler backscattering (DBS) and conventional (normal-incidence) fluctuation reflectometry. DBS has become a well-established and versatile diagnostic technique for the measurement of intermediate- k ($k_{\\bot} \\rho_i \\sim 1$, and higher) density fluctuations and flows in magnetically confined fusion experiments. The $180^{\\circ}$ backscattering for DBS requires three dimensional wave-vector matching between the launched beam and the plasma fluctuations inducing the scattering, which are expected to be highly elongated along the magnetic field. The large pitch angle in MAST means that DBS implementation depends strongly on the capability to accurately launch the probing beam at a toroidal and poloidal angle that is matched to the magnetic field at the scattering location. We report on the scattering consi...

  16. 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 ...

  17. Anomalous Doppler effects in bulk phononic crystal

    International Nuclear Information System (INIS)

    Doppler effects in simple cubic phononic crystal are studied theoretically and numerically. In addition to observing Doppler shifts from a moving source's frequencies inside the gap, we find that Doppler shifts can be multi-order, anisotropic, and the dominant order of shift depends on the band index that the source's frequency is in.

  18. Three-dimensional power doppler imaging

    International Nuclear Information System (INIS)

    Three-dimensional (3-D) ultrasonographic imaging techniques have recently shown rapid development and their clinical application has begun to attract considerable attention. Power Doppler sonography is known to be more sensitive than color Doppler for detecting blood flow, and there is also less noise and clutter. This paper describes the basic principles and initial clinical experience of 3-D power Doppler sonography

  19. 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)

  20. Reverse Doppler Effect of Sound

    OpenAIRE

    Lee, Sam Hyeon; Park, Choon Mahn; Seo, Yong Mun; Wang, Zhi Guo; Kim, Chul Koo

    2009-01-01

    We report observation of reverse Doppler effect in a double negative acoustic metamaterial. The metamaterial exhibited negative phase velocity and positive group velocity. The dispersion relation is such that the wavelength corresponding to higher frequency is longer. We observed that the frequency was down-shifted for the approaching source, and up-shifted when the source receded.

  1. 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

  2. Segurança e exeqüibilidade do ecocardiograma sob estresse com dobutamina e atropina em pacientes octogenários Safety and feasibility of dobutamine-atropine stress echocardiography in octogenarian patients

    Directory of Open Access Journals (Sweden)

    José Sebastião de Abreu

    2005-09-01

    Full Text Available OBJETIVO: Verificar a exeqüibilidade e segurança do ecocardiograma sob estresse com dobutamina e atropina (EED em octogenários. MÉTODOS: Avaliaram-se 5.467 EED, distribuídos entre grupo dos octogenários (GI=203 e grupo controle (GII=5.264. A idade média no GI=83±3 (80-95 e no GII=59±11 (17-79 anos. Os parâmetros resultantes do EED, coletados prospectivamente, foram comparados e analisados. RESULTADOS: O percentual de pacientes que atingiram freqüência cardíaca máxima foi em GI=63,5% e GII=41% (GI vs. GII; pOBJECTIVE: To assess the feasibility and safety of dobutamine-atropine stress echocardiography (DASE in octogenarians. METHODS: We evaluated 5,467 DASE which were distributed in two groups: group I (GI with 203 DASE performed in octogenarians, and group II (GII, the control group, with 5,264 DASE. The mean age of GI and GII was 83±3 (80-95 and 59±11 (17-79 years, respectively. DASE parameters that were prospectively collected, were compared and analyzed. RESULTS: The percentage of patients that achieved maximum heart rate was 63.5% in GI and 41% in GII (p<0.001, and GI patients required less atropine compared to GII (GI=47%, GII=78%, p<0.001.The presence of chest pain (GI=13%, GII=15.6%, p=0.429 and DASE positive for myocardial ischemia (GI=20.7%, GII=16.9%, p=0.296 were not statistically different between the two groups. However, concomitant positive DASE and absence of chest pain (GI=17%, GII=11%, p=0.029 was higher in GI. The incidence of premature beats in GI was higher than in GII (GI=47.8%, GII=27.6%, p<0.001, and there were more supraventricular tachyarrhythmias (ST in GI than in GII (GI=5.9%, GII=1.9%, p=0.001. Out of 11 ST that happened in GI, 9 reverted spontaneously. There weren't either deaths or acute myocardial infarction. Ventricular fibrillation only happened in GII (2 cases, 0.03%. CONCLUSION: In the present study, octogenarians achieved maximum heart rate more frequently despite the lesser amount of atropine

  3. 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.

  4. 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.

  5. Causality and the Doppler Peaks

    OpenAIRE

    Turok, Neil

    1996-01-01

    Could cosmic structure have formed by the action of causal physics within the standard hot big bang, or was a prior period of inflation required? Recently there has been some discussion of whether causal sources could reproduce the pattern of Doppler peaks of the standard scale-invariant adiabatic theory. This paper gives a rigorous definition of causality, and a causal decomposition of a general source. I present an example of a simple causal source which mimics the standard adiabatic theory...

  6. Doppler Imaging of Ap Stars

    OpenAIRE

    Kuschnig, R.

    1998-01-01

    Doppler imaging, a technique which inverts spectral line profile variations of an Ap star into a two-dimensional abundance maps, provides new observational constraints on diffusion mechanism in the presence of a global magnetic field. A programme is presented here with the aim to obtain abundance distributions of at least five elements on each star, in order to study how different diffusion processes act under influence of a stellar magnetic field. The importance of this multi-element approac...

  7. [Doppler echocardiography in endomyocardial fibrosis].

    Science.gov (United States)

    Tello, R; Cuan, V; Abundes, A; Navarro, J; García Lara, J; Astudillo, R; Ariza, H; Cuan, M

    1994-01-01

    Twelve patients with endomyocardial fibrosis with angiographic and/or histologic corroboration were studied with Doppler echocardiography with the purpose of describing the echocardiographic features and identify the affected sites. The average age was 41 years (range 16 to 59 years), 2 men and 10 women. Three patients (25%) had isolated right ventricular involvement, one patient (8%) left ventricular, 8 patients (66%) both ventricular. Our Doppler echocardiographic findings were: right atrium enlargement (91%), right ventricle outflow dilatation (83%), paradoxical septal motion (83%), left atrial enlargement (33%), mitral and tricuspid valve prolapse (50%), pericardial effusion (41%), mitral regurgitation (75%), tricuspid regurgitation (100%), apex obliteration (50%) and a restrictive type flow pattern (50%). Doppler echocardiography is a useful method for the diagnosis of endomyocardial fibrosis, the finding of normal or small ventricles associated with apex obliteration and enlarged atria, mitral or tricuspid regurgitation and a restrictive type flow pattern are characteristics of this disease. In our population, the isolated or predominantely right ventricular involvement is the most common finding as it represented 83% of the cases. PMID:7979815

  8. 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...

  9. 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

    OpenAIRE

    Adelino Parro Jr; Marta Lancia Carramona; Caio Augusto Ferreira Amaral; José Luiz Balthazar Jacob; José Carlos Nicolau

    2004-01-01

    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 morfol...

  10. 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.

  11. Doppler tomography in fusion plasmas and astrophysics

    DEFF Research Database (Denmark)

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

    2015-01-01

    spots, spiral structures and flow patterns. Fusion plasma Doppler tomography has led 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 can be learned by comparison of these applications....

  12. Observation of the Zero Doppler Effect

    OpenAIRE

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

    2016-01-01

    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 i...

  13. Avaliação da anastomose de artéria torácica interna esquerda com artéria interventricular anterior pela ecodopplercardiografia Evaluation of left internal thoracic artery anastomosis with left anterior descending coronary artery by Doppler echocardiography

    Directory of Open Access Journals (Sweden)

    Adelaide Arruda

    1997-12-01

    Full Text Available OBJETIVO: Avaliar o valor do ecocardiograma Doppler(ECO transtorácico na identificação de perviabilidade da anastomose entre artéria torácica interna esquerda (ATIE e interventricular anterior, realizada pela técnica de revascularização miocárdica pela minitoracotomia sem circulação extracorpórea. MÉTODOS: Estudaram-se os primeiros 12 pacientes, consecutivos, no período de pós-operatório intra-hospitalar pelo ECO, utilizando-se transdutores de 5MHz, pela via paraesternal esquerda, preferencialmente. Foram analisadas velocidades máximas e integrais de velocidade dos componentes sistólico e diastólico das curvas espectrais de fluxo Doppler. Todos pacientes foram submetidos à cinecoronariografia, enquanto hospitalizados. RESULTADOS: O ECO foi exeqüível em 93% dos pacientes. Nos com anastomose pérvia (6/7, observou-se ao estudo Doppler amplo componente diastólico (padrão A. Naqueles com anastomose obstruída (4/4 o padrão observado foi de predomínio sistólico (padrão B (p=0,003*. CONCLUSÃO: O ECO da ATIE anastomosada com a artéria interventricular anterior, após cirurgia de revascularização miocárdica pela técnica de minitoracotomia, permitiu caracterizar precocemente, com precisão, a perviabilidade da anastomose.PURPOSE: To study the value of Doppler echocardiography as a tool for the evaluation of left internal thoracic artery graft (LITAG patency in patients who underwent coronary revascularization using minimally invasive bypass surgery without extracorporeal circulation. METHODS: The first 12 consecutive patients were studied after coronary artery bypass surgery using a 5MHz Doppler transducer. Doppler signals for the systolic and diastolic flow velocities were preferably obtained in the second intercostal space. All patients underwent coronary angiography while hospitalized. RESULTS: The exam was feasible in 93% of patients. Doppler flow pattern was predominantly diastolic (pattern A in patients with patent

  14. The Next Generation Airborne Polarimetric Doppler Radar

    Science.gov (United States)

    Vivekanandan, J.; Lee, Wen-Chau; Loew, Eric; Salazar, Jorge; Chandrasekar, V.

    2013-04-01

    NCAR's Electra Doppler radar (ELDORA) with a dual-beam slotted waveguide array using dual-transmitter, dual-beam, rapid scan and step-chirped waveform significantly improved the spatial scale to 300m (Hildebrand et al. 1996). However, ELDORA X-band radar's penetration into precipitation is limited by attenuation and is not designed to collect polarimetric measurements to remotely estimate microphysics. ELDORA has been placed on dormancy because its airborne platform (P3 587) was retired in January 2013. The US research community has strongly voiced the need to continue measurement capability similar to the ELDORA. A critical weather research area is quantitative precipitation estimation/forecasting (QPE/QPF). In recent years, hurricane intensity change involving eye-eyewall interactions has drawn research attention (Montgomery et al., 2006; Bell and Montgomery, 2006). In the case of convective precipitation, two issues, namely, (1) when and where convection will be initiated, and (2) determining the organization and structure of ensuing convection, are key for QPF. Therefore collocated measurements of 3-D winds and precipitation microphysics are required for achieving significant skills in QPF and QPE. Multiple radars in dual-Doppler configuration with polarization capability estimate dynamical and microphysical characteristics of clouds and precipitation are mostly available over land. However, storms over complex terrain, the ocean and in forest regions are not observable by ground-based radars (Bluestein and Wakimoto, 2003). NCAR/EOL is investigating potential configurations for the next generation airborne radar that is capable of retrieving dynamic and microphysical characteristics of clouds and precipitation. ELDORA's slotted waveguide array radar is not compatible for dual-polarization measurements. Therefore, the new design has to address both dual-polarization capability and platform requirements to replace the ELDORA system. NCAR maintains a C-130

  15. Airborne Differential Doppler Weather Radar

    Science.gov (United States)

    Meneghini, R.; Bidwell, S.; Liao, L.; Rincon, R.; Heymsfield, G.; Hildebrand, Peter H. (Technical Monitor)

    2001-01-01

    The Precipitation Radar aboard the Tropical Rain Measuring Mission (TRMM) Satellite has shown the potential for spaceborne sensing of snow and rain by means of an incoherent pulsed radar operating at 13.8 GHz. The primary advantage of radar relative to passive instruments arises from the fact that the radar can image the 3-dimensional structure of storms. As a consequence, the radar data can be used to determine the vertical rain structure, rain type (convective/stratiform) effective storm height, and location of the melting layer. The radar, moreover, can be used to detect snow and improve the estimation of rain rate over land. To move toward spaceborne weather radars that can be deployed routinely as part of an instrument set consisting of passive and active sensors will require the development of less expensive, lighter-weight radars that consume less power. At the same time, the addition of a second frequency and an upgrade to Doppler capability are features that are needed to retrieve information on the characteristics of the drop size distribution, vertical air motion and storm dynamics. One approach to the problem is to use a single broad-band transmitter-receiver and antenna where two narrow-band frequencies are spaced apart by 5% to 10% of the center frequency. Use of Ka-band frequencies (26.5 GHz - 40 GHz) affords two advantages: adequate spatial resolution can be attained with a relatively small antenna and the differential reflectivity and mean Doppler signals are directly related to the median mass diameter of the snow and raindrop size distributions. The differential mean Doppler signal has the additional property that this quantity depends only on that part of the radial speed of the hydrometeors that is drop-size dependent. In principle, the mean and differential mean Doppler from a near-nadir viewing radar can be used to retrieve vertical air motion as well as the total mean radial velocity. In the paper, we present theoretical calculations for the

  16. Microwave Doppler radar in unobtrusive health monitoring

    International Nuclear Information System (INIS)

    This article frames the use of microwave Doppler radar in the context of ubiquitous, non-obstructive health monitoring. The use of a 24GHz CW (continuous wave) Doppler radar based on a commercial off-the-shelf transceiver for remote sensing of heart rate and respiration rate based on the acquisition and processing of the signals delivered by the radar is briefly presented

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

    International Nuclear Information System (INIS)

    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 γ-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. (invited review)

  18. 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.

  19. 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.

  20. 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

    2016-01-01

    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. PMID:27578317

  1. 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.

  2. Color doppler sonography in thickened gallbladder wall

    International Nuclear Information System (INIS)

    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

  3. LISA data analysis: Doppler demodulation

    International Nuclear Information System (INIS)

    The orbital motion of the laser interferometer space antenna (LISA) produces amplitude, phase and frequency modulations of a gravitational wave signal. The modulations have the effect of spreading a monochromatic gravitational wave signal across a range of frequencies. The modulations encode useful information about the source location and orientation, but they also have the deleterious effect of spreading a signal across a wide bandwidth, thereby reducing the strength of the signal relative to the instrument noise. We describe a simple method for removing the dominant, Doppler component of the signal modulation. The demodulation reassembles the power from a monochromatic source into a narrow spike and provides a quick way to determine the sky locations and frequencies of the brightest gravitational wave sources

  4. 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

  5. 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.

  6. Color doppler ultrasonography diagnosis of intramuscular hemangioma

    International Nuclear Information System (INIS)

    Objective: To analyze the clinical application of color Doppler ultrasonography in diagnosing intramuscular hemangioma. Methods: The color Doppler ultrasonographic characteristics of 17 cases with intramuscular hemangioma were analyzed retrospectively. Results: Seventeen patients with intramuscular hemangima were examined and diagnosed, and all these cases were confirmed by pathology after operation. The diagnostic accurate rate was 100%. Conclusion: Intramuscular hemangioma possesses typical characteristics in two-dimensional ultrasound. On the base of two-dimensional image, Color Doppler Flow Imaging can show blood vessel distribution of intramuscular hemangioma. So intramuscular hemangioma can be measured accurately. (authors)

  7. Preliminary simulation study of doppler reflectometry

    International Nuclear Information System (INIS)

    A preliminary simulation study of Doppler reflectometry is performed. The simulations solve Maxwell's equations by a finite difference time domain (FDTD) code method in two dimensions. A moving corrugated metal target is used as a plasma cutoff layer to study the basic features of Doppler reflectometry. We examined the effects of the full width at half maximum (FWHM) of the electromagnetic waves and the corrugation depth of the metal target. Furthermore, the effect of a nonuniform plasma is studied using this FDTD analysis. The Doppler shift and velocity are compared with those obtained from FDTD analysis of a uniform plasma. (author)

  8. Carotid Artery Doppler Assessment In Patients Accussed Of Strokes

    OpenAIRE

    H. Mazaher; S. Sharif Kashani

    2005-01-01

    Carotid Doppler ultrasound assessment mostly indicated in patients accussed of TIAs or in younger patients with nonpersistant neurologic deficits. This assessment should be consisted of gray scale sonography, color Doppler Sonography, spectral Doppler sonography and power Doppler sonography. By gray scale sonography atherosclerotic plaques assessed from the point of Homogenousity, degree of echogenicity, surface regularity, calcification, length, Thichkness and sites of involvement. In color ...

  9. Steering A Radar Beam Toward The Zero-Doppler Line

    Science.gov (United States)

    Chang, Chi-Yung; Curlander, John C.

    1994-01-01

    Algorithm computes angles needed to aim radar beam from airborne or spaceborne platform toward Doppler line projected on ground for which Doppler shift of radar return is zero. Devised to reduce Doppler errors and simplify processing of data from synthetic-aperture-radar system. Applicable to aiming of other radio or optical instruments toward their zero-Doppler lines on ground.

  10. 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...

  11. 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...

  12. INSTANTANEOUS DOPPLER FREQUENCY FOR SQUINT SAR IMAGING

    Institute of Scientific and Technical Information of China (English)

    Liu Guangyan; Huang Shunji

    2003-01-01

    Instantaneous Doppler frequency for squint SAR imaging has been found with ChirpScaling Algorithm (CSA). Because the azimuth sample is not perpendicular to the range sample,the range signal must impact on the azimuth signal in the squint SAR data processing, andthe different slant range targets have different Doppler frequencies. From the mathematicalmodel of SAR echo signal, this paper carefully analyzes the instantaneous azimuth frequency, theinstantaneous Doppler frequency component of the azimuth frequency and the impact of rangechirp on azimuth frequency, which explains that Doppler frequency should be properly selected forcorrect SAR imaging in the squint SAR. The results of point target simulation experiments showthat the way is reasonable for the squint SAR and can effectively complete range compressionand azimuth focusing, and improve images' quality.

  13. 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)

  14. Doppler coefficient measurements in Zebra Core 5

    International Nuclear Information System (INIS)

    Measurements using a central hot loop in Zebra Core 5 are described. Results are given for the Doppler coefficients found in a number of assemblies with PuO2 and 16% PuO2/84% depleted UO2 pins, loaded with different combinations of steel, sodium or void pins. The mixed oxide results are in general about 20% more negative than was calculated using the FD2 data set, but agreement is good if the plutonium contributions in the calculations are omitted. The small positive Doppler coefficient calculated for Pu239 was not observed, and two measurements indicated instead a small negative effect. The Doppler effect in the mixed oxide systems was found to vary approximately as 1/T. The results from the empty loop and non-fissile assemblies indicate either a small negative Doppler effect in steel or alternatively the presence of an unexplained expansion effect. (author)

  15. Intensity changes in the Doppler effect

    OpenAIRE

    Johnson, Montgomery H.; Teller, Edward

    1982-01-01

    When a source moves in any direction, the source strength and the frequencies are altered by the Doppler effect. It is shown that the source strength divided by the cube of the frequency is a Lorentz invariant.

  16. Laser Doppler flowmetry in microvascular surgery

    OpenAIRE

    Adrichem, Léon

    1992-01-01

    textabstractIn the first part of this thesis, describing clinical and experimental studies, laser Doppler flowmetry is evaluated as diagnostic tool to assess tissue microcirculation after various microvascular operations. The second part concerns the application of laser Doppler flowmetry to investigate and to objectivate the negative effects of cigarette smoking upon the microcirculation under normal circumstances as well as after microvascular operative procedures. Success of plastic and re...

  17. Speckles in laser Doppler perfusion imaging

    OpenAIRE

    Rajan, V; Varghese, B.; Leeuwen, van; W. Steenbergen

    2006-01-01

    We report on the quantitative influence of speckles in laser Doppler perfusion imaging. The influence of speckles on the signal amplitude and on the Doppler spectrum is demonstrated experimentally for particle suspensions with different scattering levels and various beam widths. It is shown that the type of tissue affects the instrumental response through the effect of lateral light diffusion on the number of speckles involved in the detection process. These effects are largest for narrow beams.

  18. Optical Doppler shift with structured light

    OpenAIRE

    Belmonte A.; Belmonte, Aniceto; de Torres, Juan P; Torres J.P.

    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...

  19. 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.

  20. Doppler synthetic aperture hitchhiker imaging

    International Nuclear Information System (INIS)

    In this paper we consider passive airborne receivers that use backscattered signals from sources of opportunity transmitting single-frequency or ultra-narrowband waveforms. Because of its combined passive synthetic aperture and the single-frequency nature of the transmitted waveforms, we refer to the system under consideration as Doppler synthetic aperture hitchhiker (DSAH). We present a novel image formation method for DSAH. Our method first correlates the windowed signal obtained from one receiver with the windowed, filtered, scaled and translated version of the received signal from another receiver. This processing removes the transmitter-related variables from the phase of the Fourier integral operator that maps the radiance of the scene to the correlated signal. Next, we use microlocal analysis to reconstruct the scene radiance by the weighted backprojection of the correlated signal. The image reconstruction method is applicable to both cooperative and non-cooperative sources of opportunity using one or more airborne receivers. It has the desirable property of preserving the visible edges of the scene radiance. Additionally, it is an analytic reconstruction technique that can be made computationally efficient. We present numerical simulations to demonstrate the performance of the image reconstruction method and to verify the theoretical results

  1. Color Doppler Ultrasound Indices in Endometriotic Cysts

    Directory of Open Access Journals (Sweden)

    Parisa Hajialioghlo

    2009-01-01

    Full Text Available Problem statement: There have been considerable interests on using non-invasive techniques to detect endometriosis. A few studies were evaluated the Doppler ultrasound findings of endometriosis. This study aimed to characterize the grayscale and Doppler ultrasound findings of endometriosis. Approach: During present prospective study, gray scale and Doppler ultrasound findings of 37 women with final diagnosis of endometriosis were evaluated. Patients with probable diagnosis of endometriosis underwent conventional transvaginal and color Doppler assessment. After laparascopic confirmation of endometriosis, gray scale and color Doppler ultrasonographic data of patients considered for analysis. Results: Finally data of 37 subjects' data with suspected endometriosis was analyzed. Twenty nine of lesions were endometriosis, five hydrosalpinx, four paraovarian adhesion cysts and one peritoneal inclusion cyst according to laparoscopic exploration. Out of 29 endometriotic cysts, flow was detected in 58.62%. The mean of RI and PI were 0.67±0.15 (0.46-1.00 and 1.49±0.85 (0.66-3.11, respectively. Conclusion: In our experience, transvaginal sonography with color Doppler interrogation is a useful technique in the diagnosis of pathologic ovarian conditions, including cystic endometriosis.

  2. 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.

  3. Monte Carlo analysis of doppler reactivity coefficient for UO2 pin cell geometry

    International Nuclear Information System (INIS)

    Monte Carlo analysis has been performed to investigate the impact of the exact resonance elastic scattering model on the Doppler reactivity coefficient for the UO2 pin cell geometry with the parabolic temperature profile. As a result, the exact scattering model affects the coefficient similarly for both the flat and parabolic temperature profiles; it increases the contribution of uranium-238 resonance capture in the energy region from ∼16 eV to ∼150 eV and does uniformly in the radial direction. Then the following conclusions hold for both the exact and asymptotic resonance scattering models. The Doppler reactivity coefficient is well reproduced with the definition of the effective fuel temperature (equivalent flat temperature) proposed by Grandi et al. In addition, the effective fuel temperature volume-averaged over the entire fuel region negatively overestimates the reference Doppler reactivity coefficient but the calculated one can be significantly improved by dividing the fuel region into a few equi-volumes. (author)

  4. Doppler evaluation of valvular regurgitation

    International Nuclear Information System (INIS)

    The many examples described in this chapter show that there are several major points to keep in mind when examining patients for the presence of valvular insufficiency. One practical point not previously emphasized is that the audible output may be more sensitive than the spectral display. It is not infrequent that a given lesion is heard by audio but cannot be adequately recorded on the spectral hard copy. Interpretation in these cases is often difficult and, in our experience, usually involves a tradeoff. Accepting audio evidence of a regurgitant lesion without hard-copy confirmation increases the sensitivity of the procedure but will also result in an increased number of false-positive diagnoses. Currently, we require hard-copy confirmation before we will report definite evidence of valvular regurgitation. Second, it is important for the operator to take time to search for small regurgitant jets. When searching for insufficiency by pulsed wave with an instrument that has a variable sample volume size, one should not routinely begin the examination with a sample volume size that is as large as possible. Although this may seem desirable for locating small jets, the operator must remember that this process will frequently result in a loss of system sensitivity. Third, the opertor should expect regurgitant jets to exceed a velocity of 1.5m/sec and result in aliasing when in pulsed wave mode. This is certainly true in most adults, since regurgitant lesions are located far enough away from the transducer to cause the Nyquist limit to be exceeded. Thus, in almost every instance, pulsed Doppler operators should expect aliasing of regurgitant lesion. Fourth, particularly beginners should be prepared to switch back and forth between pulsed and continuous wave modes

  5. 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.

  6. 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.

  7. Doppler effects on velocity spectra observed by MST radars

    Science.gov (United States)

    Scheffler, A. O.; Liu, C. H.

    1986-01-01

    Recently, wind data from mesophere-stratosphere-troposphere (MST) radars have been used to study the spectra of gravity waves in the atmosphere (Scheffler and Liu, 1985; VanZandt et al., 1985). Since MST radar measures the line-of-sight Doppler velocities, it senses the components of the wave-associated velocities along its beam directions. These components are related through the polarization relations which depend on the frequency and wave number of the wave. Therfore, the radar-observed velocity spectrum will be different from the original gravity-wave spectrum. Their relationship depends on the frequency and wave number of the wave as well as the propagation geometry. This relation can be used to interpret the observed data. It can also be used to test the assumption of gravity-wave spectrum (Scheffler and Liu, 1985). In deriving this relation, the background atmosphere has been assumed to be motionless. Obviously, the Doppler shift due to the background wind will change the shape of the gravity-wave power spectrum as well as its relation with the radar-observed spectrum. Here, researcher's investigate these changes.

  8. Arm locking with Doppler estimation errors

    Energy Technology Data Exchange (ETDEWEB)

    Yu Yinan; Wand, Vinzenz; Mitryk, Shawn; Mueller, Guido, E-mail: yinan@phys.ufl.ed [Department of Physics, University of Florida, Gainesville, FL 32611 (United States)

    2010-05-01

    At the University of Florida we developed the University of Florida LISA Interferometer Simulator (UFLIS) in order to study LISA interferometry with hardware in the loop at a system level. One of the proposed laser frequency stabilization techniques in LISA is arm locking. Arm locking uses an adequately filtered linear combination of the LISA arm signals as a frequency reference. We will report about experiments in which we demonstrated arm locking using UFLIS. During these experiments we also discovered a problem associated with the Doppler shift of the return beam. The initial arm locking publications assumed that this Doppler shift can perfectly be subtracted inside the phasemeter or adds an insignificant offset to the sensor signal. However, the remaining Doppler knowledge error will cause a constant change in the laser frequency if unaccounted for. Several ways to circumvent this problem have been identified. We performed detailed simulations and started preliminary experiments to verify the performance of the proposed new controller designs.

  9. 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

  10. Gallblader varices in children with portal cavernoma: duplex-Doppler and color Doppler ultrasound studies

    International Nuclear Information System (INIS)

    To determine the prevalence of varices in the gallbladder wall, observed by duplex-Doppler and color Doppler ultrasound, in children with cavernoma of the portal vein. Nineteen patients with portal hypertension were studied prospectively by duplex-Doppler and color Doppler ultrasound: 12 of the patients had developed a cavernoma of the portal vein. The presence of peri vesicular varices was assessed in the group of patients with portal cavernoma. Duplex-Doppler and color Doppler ultrasound disclosed the presence of varices in gallbladder wall in nine of the 12 patients (75%). The varices appeared as anechoic and serpiginous areas, and Doppler ultrasound revealed slowed venous flow. However, the three patients in whom gallbldder varices were not detected presented collateral gastric ciculation and spontaneous splenorenal shunt. Gallbladder varices are common in children with portal vein cavernoma; they present hepatopetal flow. Their developments is not related to the size of the portal cavernoma, the presence of spontaneous portosystemic shunts, or endoscopic obliteration of gastric and esophageal varices. The detection of gallbladder varices in patients with portal hypertension who are to undergo biliary surgery is highly important for the surgeon, helping to avoid perioperative complications. (Author) 15 refs

  11. 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

  12. Ultrasonographic Doppler Use for Female Reproduction Management.

    Science.gov (United States)

    Bollwein, Heinrich; Heppelmann, Maike; Lüttgenau, Johannes

    2016-03-01

    Transrectal color Doppler ultrasonography is a useful technique to get new information about physiologic and pathophysiologic alterations of the uterus and ovaries in female cattle. During all reproductive stages characteristic changes in uterine blood flow are observed. Cows with puerperal disturbances show delayed decrease in uterine blood flow in the first few weeks postparturition compared with healthy cows. Measurement of follicular blood flow is used to identify normally developing follicles and predict superovulatory response. Determination of luteal blood is more reliable than B-mode sonography to distinguish between functional and nonfunctional corpora lutea. Color Doppler ultrasonography is a promising tool to improve reproductive management in female cattle. PMID:26922117

  13. 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.

  14. Doppler string phantom for assessment of clinical doppler ultrasound velocity measurement

    OpenAIRE

    Yi Zhang; Ted Lynch; Hangiandreou, Nicholas J.

    2014-01-01

    Purpose: The Doppler string phantom provides accurate velocity of the string motion; it can be used to calibrate Doppler ultrasound (US) velocity measurements and to evaluate variations due to intrinsic spectral broadening. We developed a semi‐automated method to estimate the mode velocity (Vmode) and peak velocity (Vmax) based on duplex US images from a string phantom, and use them to assess clinical Doppler US velocity measurement.Methods: Steady motion of a rubber O‐ring (20 – 110 cm/s) in...

  15. 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 ...

  16. Analisis Efek Doppler pada Sistem Komunikasi ITS-Sat

    Directory of Open Access Journals (Sweden)

    Agriniwaty Paulus

    2013-09-01

    Full Text Available Analisa efek Doppler ini menggunakan pemrograman Matlab dengan citra yang berukuran 160 128 piksel, pada eksentrisitas (e satelit yang diasumsikan 0 sehingga bentuk lintasannya circular, dengan ketinggian 700 km dari stasiun bumi, sudut inklinasi sebesar 53° dan sinyal informasi ditransmisikan pada transmisi downlink dengan frekuensi carrier 2.4 GHz. Doppler shift terbesar terjadi saat satelit berada pada posisi terjauh dari terminal bumi yakni sebesar 51.077 KHz. Untuk  menghilangkan efek Doppler maka data output dikompensasi dengan invers dari efek Doppler tersebut. Berdasarkan hasil simulasi diperoleh bahwa BER untuk frekuensi Doppler maksimum maupun minimum adalah mendekati atau hampir sama yaitu 0.5001 dan 0.4998, dan dalam keadaan tanpa terkena Doppler shift yaitu ± 0.0197 untuk SNR 0 sampai 10 dB. Sedangkan dari segi kualitas citra, diperoleh bahwa untuk Doppler shift maksimum, kualitas citra lebih baik dibandingkan saat Doppler shift minimum.

  17. 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...

  18. 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.

  19. Rotational Doppler effect in left-handed materials

    OpenAIRE

    Luo, Hailu; Wen, Shuangchun; Shu, Weixing; Tang, Zhixiang; Zou, Yanhong; Fan, Dianyuan

    2008-01-01

    We explain the rotational Doppler effect associated with light beams carrying with orbital angular momentum in left-handed materials (LHMs). We demonstrate that the rotational Doppler effect in LHMs is unreversed, which is significantly different from the linear Doppler effect. The physics underlying this intriguing effect is the combined contributions of negative phase velocity and inverse screw of wave-front. In the normal dispersion region, the rotational Doppler effect induces a upstream ...

  20. Keplerian periodogram for Doppler exoplanets detection: optimized computation and analytic significance thresholds

    OpenAIRE

    Baluev, Roman V.

    2014-01-01

    We consider the so-called Keplerian periodogram, in which the putative detectable signal is modelled by a highly non-linear Keplerian radial velocity function, appearing in Doppler exoplanetary surveys. We demonstrate that for planets on high-eccentricity orbits the Keplerian periodogram is far more efficient than the classic Lomb-Scargle periodogram and even the multiharmonic periodograms, in which the periodic signal is approximated by a truncated Fourier series. We provide new numerical al...

  1. Equipment for flow measurements according to the ultrasonic Doppler method

    International Nuclear Information System (INIS)

    An instrument for flow measurements according to the ultrasonic Doppler method is described. It consists of an applicator with an ultrasonic oscillator and, connected to it, a Doppler instrument for the Doppler flow record. The angle of incidence of the ultrasonic beam may be taken into account, flow measurement independent of the angle thus becoming possible. (RW)

  2. 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.

  3. Applications of doppler effect in navigation and oceanography

    Digital Repository Service at National Institute of Oceanography (India)

    Joseph, A.

    . The Doppler effect is also used in sports, through Doppler radar systems to measure ball speed. Navigation technology received a boost in the 1960s with the introduction of the satellite navigation system, which applies the Doppler effect. In this system...

  4. 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.

  5. Fifty Years of HF Doppler Observations

    OpenAIRE

    Ogawa, T.; T. Ichinose

    2009-01-01

    High frequency Doppler observations of the ionosphere began in August of 1957 in Kyoto. The number of the observation points worldwide were about 40 in 1980 and are about 20 at present. By this method the movement of the ionosphere reflection height and electron density below the height can be observed. Such variations are occurred by a wide variety of sources.

  6. HF Doppler Radar Observations of Geomagnetic Pulsations

    Czech Academy of Sciences Publication Activity Database

    Fišer, Jiří; Chum, Jaroslav

    Prague : Matfyzpress, 2014, s. 304-309. ISBN 978-80-7378-276-4. [Week of Doctoral Students /23./ : focused on physical study branches. Prague (CZ), 03.06.2014-05.06.2014] R&D Projects: GA ČR(CZ) GAP209/12/2440 Institutional support: RVO:68378289 Keywords : Doppler sounding * ionosphere * geomagnetic pulsations Subject RIV: DG - Athmosphere Sciences, Meteorology

  7. Ultrasonic Doppler color in glaucoma: Concordance study

    International Nuclear Information System (INIS)

    Our study demonstrates that US color Doppler is a non invasive, reliable and reproducible method for the evaluation of the orbitary flow in normal and glaucomatous patients. However is suggested that every group evaluates the inter and intraobserver variability because of the lack of universal reference velocity measurements

  8. 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.

  9. The Doppler effect measurement on 238U

    International Nuclear Information System (INIS)

    The UO2 sample was irradiated in the RB zero power reactor in order to determine the Doppler effect on the 238 U by measuring the change in the 238 capture cross section with temperature. The measurement was meant to verify the indigenous developed computer codes and nuclear data library

  10. Measurements of the Doppler effect at Phenix

    International Nuclear Information System (INIS)

    A measurement of the Doppler effect has been performed at Phenix. Large corrections were necessary. Thus the measurement has been done again on another way. Results agree. A comparison has been made with the results of a theoretical calculation performed with the CARNAVAL IV ''formulaire''

  11. 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.

  12. Doppler speedometer for micro-organisms

    International Nuclear Information System (INIS)

    Objective of Investigations: Development and creation of the Doppler speedometer for micro-organisms which allows to evaluate, in a real temporal scale, variations in the state of water suspension of micro-organisms under the effect of chemical, physical and other external actions. Statement of the Problem The main problem is absence of reliable, accessible for users and simple, in view of application, Doppler speedometers for micro-organisms. Nevertheless, correlation Doppler spectrometry in the regime of heterodyning the supporting and cell-scattered laser radiation is welt known. The main idea is that the correlation function of photo-current pulses bears an information on the averages over the assembly of cell velocities. For solving the biological problems, construction of auto-correlation function in the real-time regime with the delay time values comprising, function in the real-time regime with the delay time values comprising, nearly, 100 me (10 khz) or higher is needed. Computers of high class manage this problem using but the program software. Due to this, one can simplify applications of the proposed techniques provided he creates the Doppler speedometer for micro-organism on a base of the Pentium. Expected Result Manufactured operable mock-up of the Doppler speedometer for micro-organisms in a form of the auxiliary computer block which allows to receive an information, in the real time scale, on the results of external effects of various nature on the cell assembly in transparent medium with a small volume of the studied cell suspension

  13. An electronic Doppler signal generator for assessing continuous-wave ultrasonic Doppler flowmeters

    Science.gov (United States)

    Smallwood, R. H.; Dixon, P.

    1986-03-01

    The design and performance of the electric Doppler signal generator are described. The features of the CW ultrasonic Doppler flowmeter, which operates in the 2-10 MHz range, that are relevant to the design of the generator are examined. Methods for evaluating the bandwidth, dynamic range, directional separation, and linearity of the zero-crossing detector are discussed. The use of a polyphase network as a phase shifter to generate a single sideband (SSB) signal is analyzed. The SSB generation is performed at a frequency of 100 kHz and the advantages of generation at this frequency are stated. The selection of proper SSB signals for the system is investigated. The performance of the Doppler signal generator is evaluated with a frequency analyzer; sideband rejection ratios and phase error in the quadrature oscillator are calculated. The Doppler generator was applied to a CW flowmeter and output signal levels were measured. The test reveals that the Doppler signal generator's performance exceeds the flowmeter requirements; rejection of the unwanted sideband exceeds 40 dB for Doppler frequencies up to 10 kHz, which is the minimum upper frequency for 10 MHz flowmeters.

  14. Doppler string phantom for assessment of clinical doppler ultrasound velocity measurement

    Directory of Open Access Journals (Sweden)

    Yi Zhang

    2014-03-01

    Full Text Available Purpose: The Doppler string phantom provides accurate velocity of the string motion; it can be used to calibrate Doppler ultrasound (US velocity measurements and to evaluate variations due to intrinsic spectral broadening. We developed a semi‐automated method to estimate the mode velocity (Vmode and peak velocity (Vmax based on duplex US images from a string phantom, and use them to assess clinical Doppler US velocity measurement.Methods: Steady motion of a rubber O‐ring (20 – 110 cm/s in a CIRS Doppler String phantom (Model 043 was studied using GE LOGIQ E9 system with a 9L probe. 5 s of Doppler spectral data was averaged to generate a mean spectral profile. It was fitted by a Gaussian function and Vmode was defined as the velocity of the Gaussian peak, while Vmax is defined as the velocity at which the spectral profile falls to within 1 SD of the background. Vmode and Vmax were evaluated against the prescribed motor velocity. Repeatability and variation to scanning parameters were analyzed and reported in % range, i.e. (max – min / mean.Results: Vmode and Vmax had good repeatability over six days (6.0% for Vmode, 2.9% for Vmax. Gain, compression, scale, sample volume (SV depth and length, frequency and beam steering all had minimal impact on Vmode and Vmax (variations ≤ 4.4%. Doppler angle θ had minimal effect on Vmode (2.2% but a strong effect on Vmax (26% increase as θ increased from 10° to 60°. Vmode was linearly correlated with but overestimated the motor velocity (Pearson’s r = 1.05, R2 = 1.Conclusion: This study developed a simple yet robust Vmode and Vmax estimation method. Combined with a string phantom, these velocity estimators are shown to be a useful tool to evaluate clinical Doppler US system performance. For the tested system, only Doppler angle has an appreciable impact on Vmax estimation.--------------------------------------------Cite this article as: Zhang Y, Lynch T, Hangiandreou NJ. Doppler string phantom

  15. Carotid Artery Doppler Assessment In Patients Accussed Of Strokes

    Directory of Open Access Journals (Sweden)

    H. Mazaher

    2005-08-01

    Full Text Available Carotid Doppler ultrasound assessment mostly indicated in patients accussed of TIAs or in younger patients with nonpersistant neurologic deficits. This assessment should be consisted of gray scale sonography, color Doppler Sonography, spectral Doppler sonography and power Doppler sonography. By gray scale sonography atherosclerotic plaques assessed from the point of Homogenousity, degree of echogenicity, surface regularity, calcification, length, Thichkness and sites of involvement. In color Doppler sonography hypoechoic Plaques which could not be identified in gray scale sonogarphy, arterial tortusity, Better and faster detection of Dis-turbed flow for flow spectrum analysis are assessed. Flow spectrum analysis and degree of stenosis in carotid arteries are assessed by Spectral Doppler sonography. Finally the main indication of carotid power Doppler sonography is differentiation Of high grade stenosis from occlusion.

  16. 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) with wrist involvement were scanned on the 6 machines, each with 4 settings, generating 264 Doppler images for scoring and color quantification. Doppler sensitivity was measured with a quantitative assessment of Doppler activity: color fraction. Higher color fraction indicated higher sensitivity...

  17. 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.

  18. 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

  19. 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.)

  20. Minior Actinide Doppler Coefficient Measurement Assessment

    Energy Technology Data Exchange (ETDEWEB)

    Nolan E. Hertel; Dwayne Blaylock

    2008-04-10

    The "Minor Actinide Doppler Coefficient Measurement Assessment" was a Department of Energy (DOE) U-NERI funded project intended to assess the viability of using either the FLATTOP or the COMET critical assembly to measure high temperature Doppler coefficients. The goal of the project was to calculate using the MCNP5 code the gram amounts of Np-237, Pu-238, Pu-239, Pu-241, AM-241, AM-242m, Am-243, and CM-244 needed to produce a 1E-5 in reactivity for a change in operating temperature 800C to 1000C. After determining the viability of using the assemblies and calculating the amounts of each actinide an experiment will be designed to verify the calculated results. The calculations and any doncuted experiments are designed to support the Advanced Fuel Cycle Initiative in conducting safety analysis of advanced fast reactor or acceoerator-driven transmutation systems with fuel containing high minor actinide content.

  1. Laser Doppler measurement of cutaneous blood flow

    International Nuclear Information System (INIS)

    Laser Doppler velocimetry is an instrument system which has only recently been applied to the evaluation and quantitation of perfusion in the micro-vascular bed. The instrument is based on the Doppler principle, but uses low power laser light rather than the more commonly used ultrasound, and has a sample volume of approximately 1 mm/sup 3/. As it is non-invasive, it can be used on any skin surface or exposed microvascular bed and provides a continuous semi-quantitative measure of microcirculatory perfusion, it has a number of advantages as compared to other cutaneous blood flow measurement techniques. Initial studies have shown that it is easily used, and it has demonstrated good correlation with both xenon radio-isotope clearance and microsphere deposition techniques. Areas of current evaluation and utilization are in most major areas of medicine and surgery and include plastic, vascular and orthopaedic surgery, dermatology, gastro-enterology, rheumatology, burns and anaesthesiology

  2. Transcranial Doppler sonography in familial hemiplegic migraine

    International Nuclear Information System (INIS)

    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

  3. Color Doppler US of the penis

    International Nuclear Information System (INIS)

    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.)

  4. Design of a Doppler reflectometer for KSTAR

    Energy Technology Data Exchange (ETDEWEB)

    Lee, K. D., E-mail: kdlee@nfri.re.kr; Nam, Y. U.; Seo, Seong-Heon; Kim, Y. S. [National Fusion Research Institute, Yuseong, Daejeon 305-333 (Korea, Republic of)

    2014-11-15

    A Doppler reflectometer has been designed to measure the poloidal propagation velocity on the Korea Superconducting Tokamak Advanced Research (KSTAR) tokamak. It has the operating frequency range of V-band (50-75 GHz) and the monostatic antenna configuration with extraordinary mode (X-mode). The single sideband modulation with an intermediate frequency of 50 MHz is used for the heterodyne measurement with the 200 MHz in-phase and quadrature (I/Q) phase detector. The corrugated conical horn antenna is used to approximate the Gaussian beam propagation and it is installed together with the oversized rectangular waveguides in the vacuum vessel. The first commissioning test of the Doppler reflectometer system on the KSTAR tokamak is planned in the 2014 KSTAR experimental campaign.

  5. Renal duplex Doppler ultrasound findings in diabetics

    International Nuclear Information System (INIS)

    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

  6. Single mode, extreme precision Doppler spectrographs

    OpenAIRE

    Schwab, Christian; Leon-Saval, Sergio G.; 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 & Ho...

  7. 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.

  8. Doppler Findings in Intrapartum Fetal Distress

    OpenAIRE

    Khatereh Tooba; Laleh Eslamian

    2011-01-01

    The umbilical vein (UV) has a non pulsating and even pattern in normal fetuses. Pulsation of UV has been described in severely growth restricted fetuses with chronic hypoxia. We wanted to see whether UV pulsations could also be seen in fetuses with heart deceleration during labor, as an adjunctive measure to assess the intra partum hypoxia. In a prospective study Doppler examination was performed on 34 fetuses with normal cardiotocography (CGT) and 26 fetuses with abnormal CTGs (GA>37w and ce...

  9. 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.

  10. El doppler en podología

    OpenAIRE

    Albiol Ferrer, Josep Maria; Giralt de Veciana, Enrique; Hernández Galayo, Fco. Javier (Francisco Javier); Novel Martí, Virginia; Padrós Sánchez, Carolina; Valero, L.

    1990-01-01

    El sistema doppler por ultrasonido es un método de exploración incruento y no invasivo, que permite tener acceso a los fenómenos hemodinamicos producido en el interior de los vasos. Es un sistema de relativa sencillez de manejo, pero que utilizado correelamente aporta datos fidedignos de la velocidad del flujo como del estado de la pared de los vasos.

  11. Sub-Nyquist Radar via Doppler Focusing

    OpenAIRE

    Bar-Ilan, Omer; Eldar, Yonina C.

    2012-01-01

    We investigate the problem of a monostatic pulse-Doppler radar transceiver trying to detect targets, sparsely populated in the radar's unambiguous time-frequency region. Several past works employ compressed sensing (CS) algorithms to this type of problem, but either do not address sample rate reduction, impose constraints on the radar transmitter, propose CS recovery methods with prohibitive dictionary size, or perform poorly in noisy conditions. Here we describe a sub-Nyquist sampling and re...

  12. Colour Doppler ultrasound of the penis

    International Nuclear Information System (INIS)

    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

  13. Color Doppler imaging of cervicocephalic fibromuscular dysplasia

    OpenAIRE

    Grzyska Ulrich; Arning Christian

    2004-01-01

    Abstract Background Fibromuscular dysplasia (FMD) is a possible cause of stroke, especially in middle-aged women. However, only few reports are available on ultrasonographic detection and monitoring. Methods Among the 15,000 patients who underwent color Doppler imaging (CDI) of the cervicocephalic arteries during the study period, all cases fulfilling ultrasound criteria of FMD were included into the case series. Criteria of FMD were: 1. Segmental string-of-beads pattern, 2. Localization in t...

  14. Poincare's relativistic Doppler-Fizeau formula

    OpenAIRE

    Pierseaux, Yves

    2006-01-01

    We deduce from Poincare's ellipsoidal wavefronts a relativistic Doppler-Fizeau formula that is not the same as 1905 Einstein's one. Longitudinally, Einstein's formula and Poincare's formula are the same. The question of an experimental test is connected with the possibility or the impossibility of directly measuring the relativistic transverse effect. Hasselkamp's 1978 experiment becomes a crucial experiment because Poincare's relativistic kinematics predicts an expansion of sapce directly co...

  15. Doppler-free magnetic optical activity

    OpenAIRE

    Giraud-Cotton, S.; Kaftandjian, V.P.; Talin, B.

    1980-01-01

    The theory of Doppler-free magnetic optical activity associated with a single absorption line is presented. The transmission of tunable laser light, linearly polarized, through a dilute gaseous medium along a steady magnetic field is studied in the presence of a second counterpropagating saturating laser. The third order non linear susceptibility is calculated for a two-level system exhibiting a normal Zeeman effect, with arbitrary J values.

  16. Blazar sequence - an artefact of Doppler boosting

    OpenAIRE

    Nieppola, E.; Valtaoja, E.; Tornikoski, M.; Hovatta, T.; Kotiranta, M.

    2008-01-01

    The blazar sequence is a scenario in which the bolometric luminosity of the blazar governs the appearance of its spectral energy distribution. The most prominent result is the significant negative correlation between the synchrotron peak frequencies and the synchrotron peak luminosities of the blazar population. Observational studies of the blazar sequence have, in general, neglected the effect of Doppler boosting. We study the dependence of both the synchrotron peak frequency and luminosity ...

  17. Doppler cooling to the Quantum limit

    OpenAIRE

    Chalony, Maryvonne; Kastberg, Anders; Klappauf, Bruce; Wilkowski, David

    2011-01-01

    Doppler cooling on a narrow transition is limited by the noise of single scattering events. It shows novel features, which are in sharp contrast with cooling on a broad transition, such as a non-Gaussian momentum distribution, and divergence of its mean square value close to the resonance. We have observed those features using 1D cooling on an intercombination transition in strontium, and compared the measurements with theoretical predictions and Monte Carlo simulations. We also find that for...

  18. 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.

  19. COLOUR DOPPLER EVALUATION OF ACUTE RENAL COLIC

    Directory of Open Access Journals (Sweden)

    Vallepu Ramaiah

    2016-05-01

    Full Text Available AIMS Can Doppler index–RI be a predictor of renal colics impending obstruction in acute and emergency clinical settings. To compare the results of RI in cases of obstructive, nondilated and normal kidneys. METHODS A total of 90 patients were included in this prospective study. The patients were grouped into three categories based on the clinical settings. Group 1 with acute unilateral obstruction were 44, group 2 who were presented with flank pain without stone disease were 26 and group 3 were 20 patients with sonologically normal kidneys. Grey scale ultrasonography and colour Doppler study carried out in all the groups and index – RI value were compared. RESULTS The study showed differences in RI values among the groups (0.726±0.04, 0.63±0.039 and 0.608±0.03 respectively. CONCLUSION In acute and emergency clinical setting, grey scale ultrasonography and interrogation with colour Doppler index– RI improved the assessment and detection of impending obstructive uropathy.

  20. 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...

  1. 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.

  2. Noninvasive In-vivo Measurements of Microvessels by Reflection-Type Micro Multipoint Laser Doppler Velocimeter

    Science.gov (United States)

    Ishida, Hiroki; Andoh, Tsugunobu; Akiguchi, Shunsuke; Hachiga, Tadashi; Ishizuka, Masaru; Shimizu, Tadamichi; Shirakawa, Hiroki; Kuraishi, Yasushi

    2012-03-01

    We have developed a micro multipoint laser Doppler velocimeter (µ-MLDV) that enables selective collection of Doppler interference photons. In previous report [H. Ishida et al.: Rev. Sci. Instrum. 82 (2011) 076104], developed the reflection-type µ-MLDV, and showed the results of demonstrations performed on transparent artificial flow channels. In this study, we attempted to perform in-vivo experiments using animals. It can measure absolute velocity and generate tomographs of blood vessels courses. The present system can perform noninvasive in-vivo measurements with a detection limit of about 0.5 mm/s and a spatial resolution in the x-y plane of 125 µm. It is thus able to image venulae. It was used to image venulae in a mouse ear and a subcutaneous blood vessel in a mouse abdomen at a depth of about 1.0 mm below the skin.

  3. Doppler angle correction in the measurement of intrarenal parameters

    Directory of Open Access Journals (Sweden)

    Mennitt K

    2011-03-01

    Full Text Available Jing Gao¹, Keith Hentel¹, Qiang Zhu², Teng Ma², George Shih¹, Kevin Mennitt¹, Robert Min¹¹Department of Radiology, New York Presbyterian Hospital, Weill Cornell Medical College, NY, USA; ²Division of Diagnostic Ultrasound, Department of Radiology, Beijing Tongren Hospital, Capital Medical University, Beijing, ChinaBackground: The aim of this study was to assess differences in intrarenal artery Doppler parameters measured without and with Doppler angle correction.Methods: We retrospectively reviewed color duplex sonography in 30 normally functioning kidneys (20 native kidneys in 10 subjects and 10 transplanted kidneys in 10 subjects performed between January 26, 2010 and July 26, 2010. There were 10 age-matched men and10 age-matched women (mean 39.8 ± 12.2, range 21–60 years in this study. Depending on whether the Doppler angle was corrected in the spectral Doppler measurement, Doppler parameters including peak systolic velocity (PSV, end-diastolic velocity (EDV, and resistive index (RI measured at the interlobar artery of the kidney were divided into two groups, ie, initial Doppler parameters measured without Doppler angle correction (Group 1 and remeasured Doppler parameters with Doppler angle correction (Group 2. Values for PSV, EDV, and RI measured without Doppler angle correction were compared with those measured with Doppler angle correction, and were analyzed statistically with a paired-samples t-test.Results: There were statistical differences in PSV and EDV at the interlobar artery in the upper, mid, and lower poles of the kidney between Group 1 and Group 2 (all P < 0.001. PSV and EDV in Group 1 were significantly lower than in Group 2. RI in Group 1 was the same as that in Group 2 in the upper, mid, and lower poles of the kidneys.Conclusion: Doppler angle correction plays an important role in the accurate measurement of intrarenal blood flow velocity. The true flow velocity converted from the maximum Doppler velocity shift

  4. Recommendations for terminology and display for doppler echocardiography

    International Nuclear Information System (INIS)

    Doppler echocardiography has recently emerged as a major noninvasive technique with many applications in cardiology. To a large extent, this has been based upon a combination of clinical and engineering advances which now make possible the use of quantitative Doppler echocardiography in combination with two-dimensional imaging for measurement of volume flows, transvalve gradients, and other physiologic flow parameters which reflect cardiac function. It was the purpose of this Committee to provide a glossary of terms which could be used in standard fashion for papers and discussions related to Doppler echocardiography. As part of its task, the Committee also undertook an attempt to recommend a standard for display of Doppler information which would be useful, both for manufacturers and for clinicians. The document, therefore, includes: Section I, the Committee's recommendations for Doppler display. Section II, the glossary of Doppler terms, related to engineering and to clinical applications

  5. Spacecraft Doppler Tracking as a Xylophone Detector of Gravitational Radiation

    Science.gov (United States)

    Tinto, M.

    1995-01-01

    Spacecraft Doppler tracking is discussed for detecting gravitational waves in which Doppler data recorded on the ground are linearly combined with Doppler measurements made on board a spacecraft. A new method is derived for removing from combined data the frequency fluctuations due to the Earth troposphere, ionosphere, and mechanical vibrations of the antenna on the ground. The remaining non-zero gravitational wave signal could be used for detecting gravitational waves.

  6. Ionospheric Doppler measurements by means of HF-radar techniques

    OpenAIRE

    D. Altadill; Bianchi, C

    2005-01-01

    Studies of the dynamics of the ionosphere and its related phenomena are mainly based on Doppler Drift measurements. The time variation (ionisation/recombination) of plasma density, thermospheric wind and others can be observed by means of HF-radars. The technique of Doppler Drift measurements is a quite complex technique that is now affordable by means of an advanced ionospheric sounder. The combination of vertical sounding and interferometric Doppler detection discloses the Doppl...

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

    OpenAIRE

    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 capacities in low and high speed situations. We derive a Doppler frequency estimator using the maximum likelihood method and Jakes model (1974) of a Rayleigh fading channel. This estimator requires an FF...

  8. 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.

  9. 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.

  10. Doplerovi brodski navigacioni brzinomjeri / Maritime navigational Doppler logs

    OpenAIRE

    Milovan Unković

    2006-01-01

    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 trans...

  11. Minimally destructive, Doppler measurement of a quantized, superfluid flow

    OpenAIRE

    Kumar, A.; Anderson, N.; Phillips, W. D.; Eckel, S.; Campbell, G. K.; Stringari, S.

    2015-01-01

    The Doppler effect, the shift in the frequency of sound due to motion, is present in both classical gases and quantum superfluids. Here, we perform an in-situ, minimally destructive measurement, of the persistent current in a ring-shaped, superfluid Bose-Einstein condensate using the Doppler effect. Phonon modes generated in this condensate have their frequencies Doppler shifted by a persistent current. This frequency shift will cause a standing-wave phonon mode to be "dragged" along with the...

  12. Interpretation of Doppler blood flow velocity waveforms using neural networks.

    OpenAIRE

    Baykal, N; Reggia, J. A.; Yalabik, N.; Erkmen, A.; Beksac, M. S.

    1994-01-01

    Doppler umbilical artery blood flow velocity waveform measurement is used in perinatal surveillance for the evaluation of pregnancy status. There is an ongoing debate on the predictive value of Doppler measurements concerning the critical effect of the selection of parameters for the evaluation of Doppler output. In this paper, we describe how neural network methods can be used both to discover relevant classification features and subsequently to classify patients. Classification accuracy var...

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

    OpenAIRE

    Zhou, Hailong; Dong, Jianji; 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...

  14. Angular distributions by the conventional and the Doppler shift method

    International Nuclear Information System (INIS)

    The angular distribution of elastically scattered metastable Ne*(3P2) has been measured by the conventional and the Doppler shift method. The conventional method shows a good angular resolution and signal to noise ratio. For the Doppler shift method, the angular resolution and the signal to noise ratio are much worse. By Monte Carlo-calculations it is shown that the influence of the residual velocity profiles of the supersonic atomic beams is large for the Doppler method, but can nearly be neglected for the conventional method. For nonsymmetric systems (such as Na2-Xe) and for inelastic processes the Doppler method is expected to be more successful. (Auth.)

  15. Eliminating Doppler Effects in Synthetic-Aperture Radar Optical Processors

    Science.gov (United States)

    Constantindes, N. J.; Bicknell, T. J.

    1984-01-01

    Pair of photodetectors generates correction signals. Instrument detects Doppler shifts in radar and corrects processing parameters so ambiguities caused by shifts not manifested as double or overlapping images.

  16. ALS Association

    Science.gov (United States)

    ... toward a world without ALS! Walk to Defeat ALS® Walk to Defeat ALS® draws people of all ... We need your help. I Will Advocate National ALS Registry The National ALS Registry is a congressionally ...

  17. 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.

  18. 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

  19. Coherent Detection in Laser Doppler Velocimeters

    DEFF Research Database (Denmark)

    Hanson, Steen Grüner

    1974-01-01

    The possibility of heterodyning between electromagnetic waves scattered by particles separated in space is explained from a classical point of view and from a quantum mechanical point of view. The last description being carried out using only the Heisenberg uncertainty principle and a rather coarse......, 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 is...

  20. Transmission media effects on precise Doppler tracking

    Science.gov (United States)

    Callahan, P. S.

    1978-01-01

    The effects of the transmission media - the earth's troposphere and ionosphere, and the solar wind - on precise Doppler tracking are discussed. The charged particle effects can be largely removed by dual frequency observations; however there are limitations to these corrections (besides system noise and/or finite integration times) including the effects of magnetic fields, diffraction, and differential refraction, all of which must be carefully evaluated. The earth's troposphere can contribute an error of delta f/f approximately 10 to the minus 14th power.

  1. Moessbauer spectroscopy - applications of the Doppler principle

    International Nuclear Information System (INIS)

    Moessbauer spectroscopy is an experimental method based on the application of the Doppler principle in the velocity modulation system for variation of γ-ray energy. The object of observations is a resonating nucleus. From Moessbauer spectra one can gain information on the electronic and magnetic environment (based on hyperfine interactions) and on the vibrational states of atoms (based on the Debey-Waller factor). It is a typical microscopic method which has found applications in all disciplines of natural sciences as well as in medicine, art, archaeology and materials science. (author) 5 figs., 37 refs

  2. Doppler cooling to the quantum limit.

    Science.gov (United States)

    Chalony, M; Kastberg, A; Klappauf, B; Wilkowski, D

    2011-12-01

    Doppler cooling on a narrow transition is limited by the noise of single scattering events. It shows novel features, which are in sharp contrast with cooling on a broad transition, such as a non-gaussian momentum distribution, and divergence of its mean square value close to the resonance. We have observed those features using 1D cooling on an intercombination transition in strontium, and compared the measurements with theoretical predictions and Monte Carlo simulations. We also find that for very a narrow transition, cooling can be improved using a dipole trap, where the clock shift is canceled. PMID:22242994

  3. Doppler cooling and trapping on forbidden transitions

    OpenAIRE

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

    2001-01-01

    Ultracold atoms at temperatures close to the recoil limit have been achieved by extending Doppler cooling to forbidden transitions. A cloud of ^40Ca atoms has been cooled and trapped to a temperature as low as 6 \\mu K by operating a magneto-optical 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 1...

  4. Doppler cooling to the Quantum limit

    CERN Document Server

    Chalony, Maryvonne; Klappauf, Bruce; Wilkowski, David

    2011-01-01

    Doppler cooling on a narrow transition is limited by the noise of single scattering events. It shows novel features, which are in sharp contrast with cooling on a broad transition, such as a non-Gaussian momentum distribution, and divergence of its mean square value close to the resonance. We have observed those features using 1D cooling on an intercombination transition in strontium, and compared the measurements with theoretical predictions and Monte Carlo simulations. We also find that for very a narrow transition, cooling can be improved using a dipole trap, where the clock shift is canceled.

  5. Doppler term in the galaxy two-point correlation function: wide-angle, velocity, Doppler lensing and cosmic acceleration effects

    OpenAIRE

    Raccanelli, Alvise; Bertacca, Daniele; Jeong, Donghui; Neyrinck, Mark C.; Szalay, Alexander S.

    2016-01-01

    We study the parity-odd part (that we shall call Doppler term) of the linear galaxy two-point correlation function that arises from wide-angle, velocity, Doppler lensing and cosmic acceleration effects. As it is important at low redshift and at large angular separations, the Doppler term is usually neglected in the current generation of galaxy surveys. For future wide-angle galaxy surveys such as Euclid, SPHEREx and SKA, however, we show that the Doppler term must be included. The effect of t...

  6. 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.

  7. Windowed multipole for cross section Doppler broadening

    Science.gov (United States)

    Josey, C.; Ducru, P.; Forget, B.; Smith, K.

    2016-02-01

    This paper presents an in-depth analysis on the accuracy and performance of the windowed multipole Doppler broadening method. The basic theory behind cross section data is described, along with the basic multipole formalism followed by the approximations leading to windowed multipole method and the algorithm used to efficiently evaluate Doppler broadened cross sections. The method is tested by simulating the BEAVRS benchmark with a windowed multipole library composed of 70 nuclides. Accuracy of the method is demonstrated on a single assembly case where total neutron production rates and 238U capture rates compare within 0.1% to ACE format files at the same temperature. With regards to performance, clock cycle counts and cache misses were measured for single temperature ACE table lookup and for windowed multipole. The windowed multipole method was found to require 39.6% more clock cycles to evaluate, translating to a 7.9% performance loss overall. However, the algorithm has significantly better last-level cache performance, with 3 fewer misses per evaluation, or a 65% reduction in last-level misses. This is due to the small memory footprint of the windowed multipole method and better memory access pattern of the algorithm.

  8. Musculoskeletal colour/power Doppler in sports medicine

    DEFF Research Database (Denmark)

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

    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...

  9. Monitoring and Analysis of Respiratory Patterns Using Microwave Doppler Radar

    OpenAIRE

    ,

    2014-01-01

    Noncontact detection characteristic of Doppler radar provides an unobtrusive means of respiration detection and monitoring. This avoids additional preparations, such as physical sensor attachment or special clothing, which can be useful for certain healthcare applications. Furthermore, robustness of Doppler radar against environmental factors, such as light, ambient temperature, interference from other signals occupying the same bandwidth, fading effects, reduce environmental constraints and ...

  10. Diagnosis of aortic dissection by color-coded doppler

    International Nuclear Information System (INIS)

    Using a new ultrasound technique, the Color-Coded Doppler Echocardiography, the thoracic extension of a previously diagnosed dissecting aneurysm of the abdominal aorta was detected in an asymptomatic patient. The Color-Coded Doppler seems to be a reliable method in diagnosing aortic dissecting aneurysm and the technique of choice for the follow-up of the chronic forms of disease

  11. The Doppler and gravitational components of the cosmological redshift

    International Nuclear Information System (INIS)

    We decompose the cosmological redshift in the standard Friedmann cosmologies into two shifts: a Doppler shift attributable to the recession of the galaxies, and a gravitational shift attributable to the curvature of the universe. For galaxies nearby enough for their recessional motion to be non-relativistic, we interpret our results for the Doppler and gravitational shifts with the aid of Birkhoff's theorem. (author)

  12. A study for developing an ultrasonic Doppler flowmeter

    Science.gov (United States)

    Biermans, M.; Bregman, R.

    1984-06-01

    The system parameters for low cost ultrasonic Doppler flowmeters for medical applications were investigated. A flowmeter was built. A phase locked loop is used to find the correct Doppler shift. Laboratory and field tests prove the success of the development, although very often insufficient reflectors exist in the liquids. The accuracy is + or - 5%; the reproducibility is + or - 0.5%.

  13. Doppler weather radar with predictive wind shear detection capabilities

    Science.gov (United States)

    Kuntman, Daryal

    1991-01-01

    The status of Bendix research on Doppler weather radar with predictive wind shear detection capability is given in viewgraph form. Information is given on the RDR-4A, a fully coherent, solid state transmitter having Doppler turbulence capability. Frequency generation data, plans, modifications, system characteristics and certification requirements are covered.

  14. 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.

  15. "An analysis of the classical Doppler Effect"[1] revisited

    OpenAIRE

    Rothenstein, Bernhard; Nafornita, Corina

    2004-01-01

    After having shown that the formula which describes the Doppler effect in the general case holds only in the case of the "very high" frequency assumption, we derive free of assumptions Doppler formulas for two scenarios presented in the revisited paper.

  16. 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

  17. Ionospheric Doppler measurements by means of HF-radar techniques

    Directory of Open Access Journals (Sweden)

    D. Altadill

    2005-06-01

    Full Text Available Studies of the dynamics of the ionosphere and its related phenomena are mainly based on Doppler Drift measurements. The time variation (ionisation/recombination of plasma density, thermospheric wind and others can be observed by means of HF-radars. The technique of Doppler Drift measurements is a quite complex technique that is now affordable by means of an advanced ionospheric sounder. The combination of vertical sounding and interferometric Doppler detection discloses the Doppler sources. The echo signal contains the Doppler shift in frequency imposed on the wave carrier by each point source where the signal is reflected. Other phenomena like environmental noise and the intrinsic error of the measurements that, together with the change in time of the refractive index, affect the measurements in various ways impeding to better quantify the results.

  18. 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 ...

  19. 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.

  20. 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.

  1. 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'')

  2. Spacecraft Doppler tracking with a VLBI antenna

    Science.gov (United States)

    Comoretto, G.; Iess, L.; Bertotti, B.; Brenkle, J. P.; Horton, T.

    1990-01-01

    Preliminary results are reported from Doppler-shift measurements to the Voyager-2 spacecraft at a distance of 26 AU, obtained using the 32-m VLBI antenna at Medicina (Italy) during July and August 1988. The apparatus comprises the el-az antenna, an S-X-band receiver, a hydrogen maser to generate the reference signal, a Mark III VLBI terminal, and a digital tone extractor capable of isolating a tone of known frequency from a noisy signal and giving its phase and amplitude. A signal transmitted in S-band from the NASA Deep Space Network (DSN) station in Australia and retransmitted coherently in X-band by Voyager, was received 7 h 6 min later at Medicina and at the DSN station in Madrid. Sample data are presented graphically and shown to be of generally high quality; further in-depth analysis is under way.

  3. Microscale Heat Conduction Models and Doppler Feedback

    International Nuclear Information System (INIS)

    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.

  4. 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.

  5. Position finding using simple Doppler sensors

    Directory of Open Access Journals (Sweden)

    S. Schelkshorn

    2007-06-01

    Full Text Available An increasing number of modern applications and services is based on the knowledge of the users actual position. Depending on the application a rough position estimate is sufficient, e. g. services in cellular networks that use the information about the users actual cell. Other applications, e. g. navigation systems use the GPS-System for accurate position finding. Beyond these outdoor applications a growing number of indoor applications requires position information. The previously mentioned methods for position finding (mobile cell, GPS are not usable for these indoor applications.

    Within this paper we will present a system that relies on the simultaneous measurement of doppler signals at four different positions to obtain position and velocity of an unknown object. It is therefore suiteable for indoor usage, extendig already existing wireless infrastructure.

  6. DC coupled Doppler radar physiological monitor.

    Science.gov (United States)

    Zhao, Xi; Song, Chenyan; Lubecke, Victor; Boric-Lubecke, Olga

    2011-01-01

    One of the challenges in Doppler radar systems for physiological monitoring is a large DC offset in baseband outputs. Typically, AC coupling is used to eliminate this DC offset. Since the physiological signals of interest include frequency content near DC, it is not desirable to simply use AC coupling on the radar outputs. While AC coupling effectively removes DC offset, it also introduces a large time delay and distortion. This paper presents the first DC coupled IQ demodulator printed circuit board (PCB) design and measurements. The DC coupling is achieved by using a mixer with high LO to RF port isolation, resulting in a very low radar DC offset on the order of mV. The DC coupled signals from the PCB radar system were successfully detected with significant LNA gain without saturation. Compared to the AC coupled results, the DC coupled results show great advantages of less signal distortion and more accurate rate estimation. PMID:22254704

  7. 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...

  8. 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.

  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. Doppler cooling and trapping on forbidden transitions

    CERN Document Server

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

    2001-01-01

    Ultracold atoms at temperatures close to the recoil limit have been achieved by extending Doppler cooling to forbidden transitions. A cloud of ^40Ca atoms has been cooled and trapped to a temperature as low as 6 \\mu K by operating a magneto-optical 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 pre-cooled atoms from a standard magneto-optical trap have been transferred to the ultracold trap. Monte-Carlo simulations of the cooling process are in good agreement with the experiments.

  11. 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. PMID:11580503

  12. Ultrasonic intrusion sensor using the Doppler effect; Choonpa Doppler hoshiki shinnyu sensor

    Energy Technology Data Exchange (ETDEWEB)

    Kani, H.; Iwasaki, N.; Goto, M. [Nippon Soken, Inc., Tokyo (Japan); Tsuzuki, T.; Nakamura, T. [Denso Corp., Aichi (Japan)

    1997-10-01

    For vehicle anti-theft alarm systems which cope with vehicle and car component theft, EU initiated vehicle security regulations from Jan 1997. Also, the insurance industry has instituted the insurance certification of vehicle anti-theft alarm systems. We have developed an ultrasonic intrusion sensor using the doppler effect for vehicle anti-theft alarm systems specifically for these EU regulations and insurance certification. 2 refs., 7 figs., 1 tab.

  13. Wind Field Measurements With Airborne Doppler Lidar

    Science.gov (United States)

    Menzies, Robert T.

    1999-01-01

    In collaboration with lidar atmospheric remote sensing groups at NASA Marshall Space Flight Center and National Oceanic and Atmospheric Administration (NOAA) Environmental Technology Laboratory, we have developed and flown the Multi-center Airborne Coherent Atmospheric Wind Sensor (MACAWS) lidar on the NASA DC-8 research aircraft. The scientific motivations for this effort are: to obtain measurements of subgrid scale (i.e. 2-200 km) processes and features which may be used to improve parameterizations in global/regional-scale models; to improve understanding and predictive capabilities on the mesoscale; and to assess the performance of Earth-orbiting Doppler lidar for global tropospheric wind measurements. MACAWS is a scanning Doppler lidar using a pulsed transmitter and coherent detection; the use of the scanner allows 3-D wind fields to be produced from the data. The instrument can also be radiometrically calibrated and used to study aerosol, cloud, and surface scattering characteristics at the lidar wavelength in the thermal infrared. MACAWS was used to study surface winds off the California coast near Point Arena, with an example depicted in the figure below. The northerly flow here is due to the Pacific subtropical high. The coastal topography interacts with the northerly flow in the marine inversion layer, and when the flow passes a cape or point that juts into the winds, structures called "hydraulic expansion fans" are observed. These are marked by strong variation along the vertical and cross-shore directions. The plots below show three horizontal slices at different heights above sea level (ASL). Bottom plots are enlargements of the area marked by dotted boxes above. The terrain contours are in 200-m increments, with the white spots being above 600-m elevation. Additional information is contained in the original.

  14. Avaliação ultra-sonográfica e ao Doppler dos TIPS (anastomose portossistêmica intra-hepática transjugular Ultrasonographic Doppler evaluation of TIPS (transjugular intrahepatic portosystemic shunt

    Directory of Open Access Journals (Sweden)

    Márcio Martins Machado

    2004-04-01

    Full Text Available A anastomose portossistêmica intra-hepática transjugular (TIPS compreende a técnica mais recente e mais popular para o alívio da hipertensão portal sintomática, especialmente para os casos com varizes e hemorragia digestiva alta, e menos comumente para o tratamento da ascite refratária. Os TIPS podem apresentar complicações após sua colocação, como as estenoses e oclusões. A ultra-sonografia e o Doppler permitem o estudo dos TIPS de uma forma não invasiva. Neste artigo os autores relatam os achados recentes à ultra-sonografia e ao Doppler nos casos de funcionamento normal e anormal (estenoses/oclusões dos TIPS.Transjugular intrahepatic portosystemic shunts (TIPS are the most recent and popular technique for the relief of symptomatic portal hypertension, particularly in patients with varices and gastrointestinal bleeding and less often in patients with refractory ascites. TIPS may be complicated by stenosis or occlusion of the stent. Sonography with Doppler provides a noninvasive method for monitoring patients with TIPS. The authors report the recent sonographic and Doppler findings in patients with normal functioning TIPS and patients with stenosis or occlusion of TIPS.

  15. 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.

    2012-01-01

    Introduction The anatomy and physiology of the temporomandibular joint can be studied clinically and by diagnostic imaging. Magnetic resonance imaging (MRI), radiography (X-ray) and computed tomography (CT) have thus for many years contributed to the study of the kinetics in the mandibular condyle. However, also duplex Doppler ultrasound (US) examination is widely used in the study of structures during movement, particularly vascular structures. Materials and methods A total of 30 patients were referred by the Department of Orthodontics to the Department of Radiological, Oncological and Pathological Sciences, University of Rome “La Sapienza”. All patients underwent duplex Doppler ultrasound (US) examination of the temporomandibular joint using Toshiba APLIO SSA-770A equipment and duplex Doppler multi-display technique, which allows simultaneous display of US images and color Doppler signals. A linear phased array probe with crystal elements was used operating at a basic frequency of 6 MHz during pulsed Doppler spectral analysis and 7.5 MHz during US imaging. Results In normal patients a regular alternation in the spectral Doppler waveforms was obtained, while in patients with temporomandibular joint meniscus dysfunction there was no regularity in the sum of the Fourier series with an unsteady waveform pattern related to irregular movements of the temporomandibular joint. Conclusions In all cases duplex Doppler US examination proved able to differentiate between normal and pathological patients and among the latter this technique permitted identification of the most significant aspects of the dysfunctional diseases. PMID:23397016

  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) PMID:3766410

  17. Structural, thermal, and radiation induced effects in NiAl

    International Nuclear Information System (INIS)

    First authors results of the studies on defects in NiAl in the composition range 47 at.% Ni < 53 at.% have been presented. Positron annihilation experiments were performed on samples slowly cooled quenched or irradiated with protons. The combined positron lifetime and Doppler broadening data show the coexistence of different vacancy-type defects. (author). 15 refs, 3 figs

  18. 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.

  19. [Feasibility study of the Doppler exploration of the renal artery].

    Science.gov (United States)

    Milon, P; Clavier, E; Genevois, A; Benozio, M

    1990-03-01

    Using arteriography as a reference, the authors investigate the feasibility of pulsed doppler exploration of the normal or pathological renal arteries in 46 successive patients. The poor sensitivity of pulsed doppler, mainly due to the considerable anatomical variations of the renal pedicle, does not currently allow using this technique for the detection of renal arterial stenosis. When combined with angiography, pulsed doppler becomes a definite asset in therapeutic radiology to help in the choice of a treatment and in follow-up. PMID:2191123

  20. Sub-Doppler laser cooling of potassium atoms

    CERN Document Server

    Landini, M; Carcagni', L; Trypogeorgos, D; Fattori, M; Inguscio, M; Modugno, G

    2011-01-01

    We investigate sub-Doppler laser cooling of bosonic potassium isotopes, whose small hyperfine splitting has so far prevented cooling below the Doppler temperature. We find instead that the combination of a dark optical molasses scheme that naturally arises in this kind of systems and an adiabatic ramping of the laser parameters allows to reach sub-Doppler temperatures for small laser detunings. We demonstrate temperatures as low as 25(3)microK and 47(5)microK in high-density samples of the two isotopes 39K and 41K, respectively. Our findings will find application to other atomic systems.

  1. Sub-Doppler laser cooling of potassium atoms

    Energy Technology Data Exchange (ETDEWEB)

    Landini, M. [LENS and Dipartimento di Fisica e Astronomia, Universita di Firenze, I-50019 Sesto Fiorentino (Italy); INFN, Sezione di Firenze, I-50019 Sesto Fiorentino (Italy); Dipartimento di fisica, Universita di Trento, I-38123 Povo (Trento) (Italy); Roy, S.; Carcagni, L.; Trypogeorgos, D. [LENS and Dipartimento di Fisica e Astronomia, Universita di Firenze, I-50019 Sesto Fiorentino (Italy); Fattori, M.; Inguscio, M.; Modugno, G. [LENS and Dipartimento di Fisica e Astronomia, Universita di Firenze, I-50019 Sesto Fiorentino (Italy); INFN, Sezione di Firenze, I-50019 Sesto Fiorentino (Italy)

    2011-10-15

    We investigate the sub-Doppler laser cooling of bosonic potassium isotopes, whose small hyperfine splitting has so far prevented cooling below the Doppler temperature. We find instead that the combination of a dark optical molasses scheme that naturally arises in this kind of system and an adiabatic ramping of the laser parameters allows us to reach sub-Doppler temperatures for small laser detunings. We demonstrate temperatures as low as 25{+-}3 {mu}K and 47{+-}5 {mu}K in high-density samples of the two isotopes {sup 39}K and {sup 41}K, respectively. Our findings should find application to other atomic systems.

  2. Procedures for quality control in Doppler ultrasound equipment

    International Nuclear Information System (INIS)

    Different international recommendations suggest an application of quality control programs in ultrasound equipment. However, procedures and reference values for Doppler test are not yet well defined. This work aims to present quantitative and qualitative tests for evaluation of quality control at Doppler ultrasound equipment. The following tests were performed: Doppler Signal Sensitivity; Color Flow Sensitivity; Flow Sensitivity at Depth; Color Flow B-Mode Image Congruency; Directional Discrimination; Accuracy of Flow Velocity Readout and Accuracy of Sample Gate Positioning. The values found will be used as baseline for comparisons over time. (author)

  3. Rotational Doppler Effect and Barnett Field in Spinning NMR

    Science.gov (United States)

    Chudo, Hiroyuki; Harii, Kazuya; Matsuo, Mamoru; Ieda, Jun'ichi; Ono, Masao; Maekawa, Sadamichi; Saitoh, Eiji

    2015-04-01

    We report the observation of the rotational Doppler effect using nuclear magnetic resonance (NMR). We have developed a coil-spinning technique that enables measurements by rotating a detector and fixing a sample. We found that the rotational Doppler effect gives rise to NMR frequency shifts equal to the rotation frequency. We formulate the rotational Doppler effect and the Barnett field using a vector model for the nuclear magnetic moment. This formulation reveals that, with just the sample rotating, both effects cancel each other, thereby explaining the absence of an NMR frequency shift in conventional sample-spinning NMR measurements.

  4. Coherent Doppler wind lidars in a turbulent atmosphere

    CERN Document Server

    Banakh, Viktor

    2013-01-01

    Radiophysical tools for measuring atmospheric dynamics include sodars, Doppler radars, and Doppler lidars. Among these, coherent Doppler lidars (CDLs) have been considered the best for remote measurement of wind turbulence. This is important not only for understanding the exchange processes in the boundary layer, but also in the applied aspect, such as aviation safety. CDLs significantly extend possibilities of experimental investigation of not only wind turbulence, but also coherent structures such as aircraft wake vortices. The authors of this book conducted field tests of the developed meth

  5. Considerations pertinent to the Doppler effect for space reactors

    International Nuclear Information System (INIS)

    This paper describes various theoretical aspects pertinent to the estimation of the Doppler effect for space reactors. The distinct characteristics of space reactors give rise to various issues that are not present in the more thoroughly studied Doppler effect of fast breeder reactors. Key issues concerning the existing resonance data and computational models are extensively discussed. Calculations of the Doppler coefficient for a generic space reactor design having features of current designs have also been carried out to illustrate various aspects of practical importance

  6. 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.

  7. 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

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

    International Nuclear Information System (INIS)

    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/N2 gas cell to encode the Doppler shift of reflected near-resonant (λ0 ≈ 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/N2 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/N2 vs. Rb gas cells to efficient dephasing of the atomic/optical coherences by Rb-N2 collisions. The minimum necessary N2 buffer gas density ≈0.3 amagat translates into a smallest useful velocity range of 0 to 2

  9. Analysis of multiple scattering effects in optical Doppler tomography

    DEFF Research Database (Denmark)

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

    2005-01-01

    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......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...

  10. Laser Doppler instrument measures fluid velocity without reference beam

    Science.gov (United States)

    Bourquin, K. R.; Shigemoto, F. H.

    1971-01-01

    Fluid velocity is measured by focusing laser beam on moving fluid and measuring Doppler shift in frequency which results when radiation is scattered by particles either originally present or deliberately injected into moving fluid.

  11. Numerical studies of HF Doppler variations caused by ionospheric disturbances

    Science.gov (United States)

    Takefu, M.; Hiroshige, N.

    HF Doppler variations caused by ionospheric disturbances are studied using an ionosphere model containing sinusoidal traveling electron density fluctuations. The present study uses a more realistic ionosphere model and a more accurate numerical method than previous works using corrugated specular reflector models. The study gives a clue to estimate the TID-associated fluctuations of ionospheric electron density by means of HF Doppler measurements. It is shown that some kinds of characteristic HF Doppler traces result depending on the wavelength of the disturbance and its traveling direction. Numerical results suggest that more or less 5 percent of the background electron density can explain most of the quasi-periodic variations on the observed HF Doppler records.

  12. 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...

  13. 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.

  14. Apparatus and method for noninvasive particle detection using doppler spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Sinha, Dipen N.

    2016-05-31

    An apparatus and method for noninvasively detecting the presence of solid particulate matter suspended in a fluid flowing through a pipe or an oil and gas wellbore are described. Fluid flowing through a conduit containing the particulate solids is exposed to a fixed frequency (>1 MHz) of ultrasonic vibrations from a transducer attached to the outside of the pipe. The returning Doppler frequency shifted signal derived from the scattering of sound from the moving solid particles is detected by an adjacent transducer. The transmitted signal and the Doppler signal are combined to provide sensitive particulate detection. The magnitude of the signal and the Doppler frequency shift are used to determine the particle size distribution and the velocity of the particles. Measurement of the phase shift between the applied frequency and the detected Doppler shifted may be used to determine the direction of motion of the particles.

  15. 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...

  16. Modifications and Moving Measurements of Mobile Doppler LIDAR

    Science.gov (United States)

    Liu, Bing-Yi; Liu, Zhi-Shen; Song, Xiao-Quan; Wu, Song-Hua; Bi, De-Cang; Wang, Xi-Tao; Yin, Qi-Wei; Reitebuch, Oliver

    2010-10-01

    In the last annual report of ID. 5291 LIDAR Cal/Val, a mobile Doppler lidar had been developed for 3D wind measurements by the Chinese partners from Ocean Remote Sensing Institute, Ocean University of China. In this year, in order to further improve the mobility of the mobile Doppler lidar for lidar calibration and validation, both GPS and inertial navigation system are integrated on the vehicle for performing measurements during movement. The modifications of the system and the results of the moving measurements are presented. This work simplifies the construction of the mobile Doppler system and makes the lidar more flexible for ground-based wind measurements and validation with the ADM-Aeolus spaceborne Doppler lidar.

  17. 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)

  18. 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.

  19. 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.

  20. Calculation of the Doppler broadening function using Fourier analysis

    International Nuclear Information System (INIS)

    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 ψ(x,ζ) 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 ψ(x,ζ), enables to obtain a simple analytic solution for the Doppler broadening function. (author)

  1. Laser Doppler technology applied to atmospheric environmental operating problems

    Science.gov (United States)

    Weaver, E. A.; Bilbro, J. W.; Dunkin, J. A.; Jeffreys, H. B.

    1976-01-01

    Carbon dioxide laser Doppler ground wind data were very favorably compared with data from standard anemometers. As a result of these measurements, two breadboard systems were developed for taking research data: a continuous wave velocimeter and a pulsed Doppler system. The scanning continuous wave laser Doppler velocimeter developed for detecting, tracking and measuring aircraft wake vortices was successfully tested at an airport where it located vortices to an accuracy of 3 meters at a range of 150 meters. The airborne pulsed laser Doppler system was developed to detect and measure clear air turbulence (CAT). This system was tested aboard an aircraft, but jet stream CAT was not encountered. However, low altitude turbulence in cumulus clouds near a mountain range was detected by the system and encountered by the aircraft at the predicted time.

  2. Ultrasonic Doppler methods to extract signatures of a walking human.

    Science.gov (United States)

    Mehmood, Asif; Sabatier, James M; Damarla, Thyagaraju

    2012-09-01

    Extraction of Doppler signatures that characterize human motion has attracted a growing interest in recent years. These Doppler signatures are generated by various components of the human body while walking, and contain unique features that can be used for human detection and recognition. Although, a significant amount of research has been done in radio frequency regime for human Doppler signature extraction, considerably less has been done in acoustics. In this work, 40 kHz ultrasonic sonar is employed to measure the Doppler signature generated by the motion of body segments using different electronic and signal processing schemes. These schemes are based on both analog and digital demodulation with homodyne and heterodyne receiver circuitry. The results and analyses from these different schemes are presented. PMID:22979839

  3. 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.)

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

    International Nuclear Information System (INIS)

    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.)

  5. 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 ...

  6. Intrauterine growth retardation : prediction of perinatal distress by doppler ultrasound

    OpenAIRE

    Reuwer, P.J.H.M.; Rietman, G.W.; Sijmens, E.A.; Tiel, M.W.M. van; Bruinse, H.W.

    1987-01-01

    To investigate the ability of umbilical artery Doppler findings to identify true cases at risk of fetal distress among 51 pregnancies clinically judged to be compromised by intrauterine growth retardation (IUGR) Doppler data were related to pregnancy outcome, which was classified into three groups—group 1, healthy babies with normal placental function (16 fetuses), group 2, fetuses with definite signs of placental failure (30), and group 3, non-classifiable pregnancies (5). Group 2 was subdiv...

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

    OpenAIRE

    Petrova, Inna R.; Bochkarev, Vladimir V.; 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...

  8. Fetal echo doppler for early detection of congenital heart block

    OpenAIRE

    Bergman, Gunnar

    2010-01-01

    Background: Fetal echo Doppler methods detecting prolonged atrioventricular (AV) time intervals, a mechanical PR interval corresponding to the electrical PR interval in ECG, have been proposed for surveillance of pregnancies at risk of complete congenital heart block (CCHB). The aim of this thesis was; to validate these Doppler methods by comparing AV time intervals from left ventricular inflow (MV), inflow and aortic outflow (MV-Ao) and superior vena cava and aortic flow ...

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

    Science.gov (United States)

    Doerry, Armin W.; Jordan, Jay D.; Kim, Theodore J.

    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.

  10. Diagnosis of cervical cancer with transvaginal color Doppler sonography

    OpenAIRE

    Li-bo DENG; Wei ZHOU; Chang, Shu-Fang; Ming-jie LIN

    2011-01-01

    Objective To investigate the imaging features of cervical cancer by transvaginal color Doppler sonography(TVCS),and evaluate the diagnostic value of TVCS.Methods A hundred and thirty cases of cervical intraepithelial neoplasia(CIN) grade Ⅰ-Ⅱ and cervical cancer,diagnosed by Thinprep cytologic test(TCT),cervical biopsy and pathological examination,received TVCS examination.The image characters and color Doppler flow imaging(CDFI) were collected and analyzed.Another 41 cases with normal cervice...

  11. Color doppler ultrasound diagonosis in cesarean scar pregnancy

    International Nuclear Information System (INIS)

    Objective: To study the sonographic characteristics of cesarean scar pregnancy(CSP), and the value of color Doppler in the diagnosis of CSP. Methods: Twelve cases of CSP were all confirmed by transabdominal and transvaginal ultrasound. Results: The ultrasonogram of CSP could be divided into gestational sac type and mixed mass type. Conclusion: Color Doppler can give guidance to the early diagnosis, treatment and following-up of CSP because of the sonographic specifity of CSP. (authors)

  12. Doppler Tomography in Cataclysmic Variables: an historical perspective

    OpenAIRE

    Echevarria, J.

    2012-01-01

    To mark the half-century anniversary of this newly-born field of Cataclysmic Variables, a special emphasis is made in this review, on the Doppler Effect as a tool in astrophysics. The Doppler Effect was in fact, discovered almost 170 years ago, and has been since, one of the most important tools which helped to develop modern astrophysics. We describe and discuss here, its use in Cataclysmic Variables which, combined with another important tool, the tomography, first devised for medical purpo...

  13. Physiological and pathophysiological cerebrovascular regulation monitored by transcranial doppler

    OpenAIRE

    Hellström, Gunnar

    1997-01-01

    PHYSIOLOGICAL AND PATHOPHYSIOLOGICAL CEREBROVASCULAR REGULATION MONITORED BY TRANSCRANIAL DOPPLER Thesis by Gunnar Hellström, M D., Department of Clinical Neuroscience, Division of Neurology, Karolinska Hospital and Insbtute, Stocknolm, Sweden Transcranial Doppler ultrasonography (TCD) became available in the middle of the 1980s as a new technique for examinmg cerebral circulation. With this technique it is possible to measure the velocity of blood flow in major ...

  14. Experimental Observation of Reversed Doppler Effects in Acoustic Metamaterials

    OpenAIRE

    Zhai, Shilong; Zhao, Xiaopeng; Liu, Song; Luo, Chunrong

    2015-01-01

    This paper reports an experimental observation of broadband reversed Doppler effects using an acoustic metamaterial with seven flute-like double-meta-molecule clusters. Simulations and experiments verify that this locally resonant acoustic metamaterial with simultaneous negative elastic modulus and mass density can realize negative refraction in a broad frequency range. The constructed metamaterial exhibits broadband reversed Doppler effects. The frequency shift increases continuously as the ...

  15. Doppler velocimetry for predicting fetal death in a twin pregnancy.

    OpenAIRE

    Soikkeli, Pia; Dubiel, Mariusz; Gudmundsson, Saemundur

    2002-01-01

    Diagnosis of discordant twins is easily accomplished with modern ultrasound equipment, though diagnosing twin-to-twin transfusion syndrome (TTS) at an early stage might be a problem. The possibility of excluding TTS by Doppler ultrasound is demonstrated in a case with early severe growth restriction of one fetus. Characteristic blood velocity changes in a dying fetus are also illustrated. The Doppler technique has become an accepted method in obstetrics for antenatal surveillance, perm...

  16. 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%.

  17. Multiple and dependent scattering effects in Doppler optical coherence tomography

    OpenAIRE

    Kalkman, J; Bykov, A. V.; Faber, D.J.; Leeuwen, van

    2010-01-01

    Doppler optical coherence tomography (OCT) is a technique to image tissue morphology and to measure flow in turbid media. In its most basic form, it is based on single (Mie) scattering. However, for highly scattering and dense media multiple and concentration dependent scattering can occur. For Intralipid solutions with varying scattering strength, the effect of multiple and dependent scattering on the OCT signal attenuation and Doppler flow is investigated. We observe a non-linear increase i...

  18. Narrowing of EIT resonance in a Doppler Broadened Medium

    OpenAIRE

    Javan, Ali; Kocharovskaya, Olga; Lee, Hwang; Scully, Marlan O.

    2001-01-01

    We derive an analytic expression for the linewidth of EIT resonance in a Doppler broadened system. It is shown here that for relatively low intensity of the driving field the EIT linewidth is proportional to the square root of intensity and is independent of the Doppler width, similar to the laser induced line narrowing effect by Feld and Javan. In the limit of high intensity we recover the usual power broadening case where EIT linewidth is proportional to the intensity and inversely proporti...

  19. Precision Measuring of Velocities via the Relativistic Doppler Effect

    OpenAIRE

    Ozernoy, Leonid M.

    1997-01-01

    Just as the ordinary Doppler effect serves as a tool to measure radial velocities of celestial objects, so can the relativistic Doppler effect be implemented to measure a combination of radial and transverse velocities by using recent improvements in observing techniques. A key element that makes a further use of this combination feasible is the periodicity in changes of the orbital velocity direction for the source. Two cases are considered: (i) a binary star; and (ii) a solitary star with t...

  20. 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.

  1. Doppler findings in intrapartum fetal distress.

    Science.gov (United States)

    Eslamian, Laleh; Tooba, Khatereh

    2011-01-01

    The umbilical vein (UV) has a non pulsating and even pattern in normal fetuses. Pulsation of UV has been described in severely growth restricted fetuses with chronic hypoxia. We wanted to see whether UV pulsations could also be seen in fetuses with heart deceleration during labor, as an adjunctive measure to assess the intra partum hypoxia. In a prospective study Doppler examination was performed on 34 fetuses with normal cardiotocography (CGT) and 26 fetuses with abnormal CTGs (GA>37w and cervical dilatation>3cm). Perinatal outcome was assessed according to presence or absence of UV pulsations. The 2 groups were similar regarding gestational age, cervical dilatation, Umbilical artery blood pH, S/D ratio,Pulsatility Index( PI) and Resistance Index (RI). Intraabdominal UV pulsation were present in 6 (23.1%) of abnormal CTG group but no case were seen in normal CTG group (P= 0.005). Five of 6 (83.3%) fetuses with UV pulsation underwent cesarean delivery. The rate of cesarean delivery was 90% in abnormal CTG group without pulsation and 14.7% in normal CTG group. The frequency of Apgar score Apgar sore <7or NICU admission were seen. PMID:22009812

  2. Muscle activity characterization by laser Doppler Myography

    International Nuclear Information System (INIS)

    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

  3. New developments in photon Doppler velocimetry

    International Nuclear Information System (INIS)

    Photon Doppler velocimetry (PDV) has made the transition among many experimental groups from being a new diagnostic to being routinely fielded as a means of obtaining velocity data in high-speed test applications. Indeed, research groups both within and outside of the shock physics community have taken note of PDV's robust, high-performance measurement capabilities. As PDV serves as the primary diagnostic in an increasing number of experiments, it will continue to find new applications and enable the measurement of previously un-measurable phenomena. This paper provides a survey of recent developments in PDV system design and feature extraction as well as a discussion of new applications for PDV. More specifically, changes at the system level have enabled the collection of data sets that are far richer than those previously attainable in terms of spatial and temporal coverage as well as improvements over PDV's previously measurable velocity ranges. And until recently, PDV data have been analyzed almost exclusively in the frequency-domain; although the use of additional data analysis techniques is beginning to show promise, particularly as it pertains to extracting information from a PDV signal about surface motion that is not along the beam's axis.

  4. Hydronephrosis and pregnancy: study with Doppler echography

    International Nuclear Information System (INIS)

    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

  5. 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.

  6. Evaluating microcirculation by pulsatile laser Doppler signal

    Science.gov (United States)

    Chao, P. T.; Jan, M. Y.; Hsiu, H.; Hsu, T. L.; Wang, W. K.; Wang, Y. Y. Lin

    2006-02-01

    Laser Doppler flowmetry (LDF) is a popular method for monitoring the microcirculation, but it does not provide absolute measurements. Instead, the mean flux response or energy distribution in the frequency domain is generally compared before and after stimulus. Using the heartbeat as a trigger, we investigated whether the relation between pressure and flux can be used to discriminate different microcirculatory conditions. We propose the following three pulsatile indices for evaluating the microcirculation condition from the normalized pressure and flux segment with a synchronized-averaging method: peak delay time (PDT), pressure rise time and flux rise time (FRT). The abdominal aortic blood pressure and renal cortex flux (RCF) signals were measured in spontaneously hypertensive rats (SHR) and Wistar Kyoto rats (WKY). The mean value of the RCF did not differ between SHR and WKY. However, the PDT was longer in SHR (87.14 ± 5.54 ms, mean ± SD) than in WKY (76.92 ± 2.62 ms; p discriminate RCF signals that cannot be discriminated using traditional methods.

  7. A test and simulation device for Doppler-based fetal heart rate monitoring

    OpenAIRE

    Mert, Ahmet; Mana SEZDİ; Akan, Aydin

    2015-01-01

    The Doppler effect is the preferred technique in fetal heart rate (FHR) monitoring devices. The main objective of the recent studies on the Doppler FHR has been to improve the accuracy. On the other hand, a reliable fetal heart simulator becomes essential for testing Doppler FHR monitoring devices. The motivation of this study is to design a reliable system that will be used to test Doppler FHR monitors. This device generates a similar Doppler frequency shift of fetal cardiac activity includi...

  8. 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.

  9. 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.

  10. 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 $15.2^{+6.7}_{-7.6}~ M_{\\oplus}$.

  11. 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

  12. Analysis of airborne Doppler lidar, Doppler radar and tall tower measurements of atmospheric flows in quiescent and stormy weather

    Science.gov (United States)

    Bluestein, H. B.; Doviak, R. J.; Eilts, M. D.; Mccaul, E. W.; Rabin, R.; Sundara-Rajan, A.; Zrnic, D. S.

    1986-01-01

    The first experiment to combine airborne Doppler Lidar and ground-based dual Doppler Radar measurements of wind to detail the lower tropospheric flows in quiescent and stormy weather was conducted in central Oklahoma during four days in June-July 1981. Data from these unique remote sensing instruments, coupled with data from conventional in-situ facilities, i.e., 500-m meteorological tower, rawinsonde, and surface based sensors, were analyzed to enhance understanding of wind, waves and turbulence. The purposes of the study were to: (1) compare winds mapped by ground-based dual Doppler radars, airborne Doppler lidar, and anemometers on a tower; (2) compare measured atmospheric boundary layer flow with flows predicted by theoretical models; (3) investigate the kinematic structure of air mass boundaries that precede the development of severe storms; and (4) study the kinematic structure of thunderstorm phenomena (downdrafts, gust fronts, etc.) that produce wind shear and turbulence hazardous to aircraft operations. The report consists of three parts: Part 1, Intercomparison of Wind Data from Airborne Lidar, Ground-Based Radars and Instrumented 444 m Tower; Part 2, The Structure of the Convective Atmospheric Boundary Layer as Revealed by Lidar and Doppler Radars; and Part 3, Doppler Lidar Observations in Thunderstorm Environments.

  13. 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.

  14. Doppler Findings in Intrapartum Fetal Distress

    Directory of Open Access Journals (Sweden)

    Khatereh Tooba

    2011-08-01

    Full Text Available The umbilical vein (UV has a non pulsating and even pattern in normal fetuses. Pulsation of UV has been described in severely growth restricted fetuses with chronic hypoxia. We wanted to see whether UV pulsations could also be seen in fetuses with heart deceleration during labor, as an adjunctive measure to assess the intra partum hypoxia. In a prospective study Doppler examination was performed on 34 fetuses with normal cardiotocography (CGT and 26 fetuses with abnormal CTGs (GA>37w and cervical dilatation>3cm. Perinatal outcome was assessed according to presence or absence of UV pulsations. The 2 groups were similar regarding gestational age, cervical dilatation, Umbilical artery blood pH, S/D ratio,Pulsatility Index( PI and Resistance Index (RI. Intraabdominal UV pulsation were present in 6 (23.1% of abnormal CTG group but no case were seen in normal CTG group (P= 0.005. Five of 6 (83.3% fetuses with UV pulsation underwent cesarean delivery. The rate of cesarean delivery was 90% in abnormal CTG group without pulsation and 14.7% in normal CTG group. The frequency of Apgar score <7 was more in fetuses with UV pulsations (16.7% vs 5% although not statistically significant. NICU admission was considerably more in UV pulsation group (33% vs 5%, P= 0.123. After exclusion of LBW fetuses the UV pulsation was present in 4 (19% of abnormal CTG group, who 3 of them underwent cesarean section. Neither umbilical artery pH<7 nor Apger score <7 or NICU admission were seen in these 4 neonates. Pulsation in UV was seen in 23% of fetuses with abnormal CTG during intra partum period. Cesarean delivery and NICU admission was increased in fetuses with UV pulsations, although not statistically significant. When LBW fetuses were excluded no case of UA pH<7, Apgar sore <7or NICU admission were seen.

  15. Hands-Free Transcranial Color Doppler Probe

    Science.gov (United States)

    Chin, Robert; Madala, Srihdar; Sattler, Graham

    2012-01-01

    Current transcranial color Doppler (TCD) transducer probes are bulky and difficult to move in tiny increments to search and optimize TCD signals. This invention provides miniature motions of a TCD transducer probe to optimize TCD signals. The mechanical probe uses a spherical bearing in guiding and locating the tilting crystal face. The lateral motion of the crystal face as it tilts across the full range of motion was achieved by minimizing the distance between the pivot location and the crystal face. The smallest commonly available metal spherical bearing was used with an outer diameter of 12 mm, a 3-mm tall retaining ring, and 5-mm overall height. Small geared motors were used that would provide sufficient power in a very compact package. After confirming the validity of the basic positioning concept, optimization design loops were completed to yield the final design. A parallel motor configuration was used to minimize the amount of space wasted inside the probe case while minimizing the overall case dimensions. The distance from the front edge of the crystal to the edge of the case was also minimized to allow positioning of the probe very close to the ear on the temporal lobe. The mechanical probe is able to achieve a +/-20deg tip and tilt with smooth repeatable action in a very compact package. The enclosed probe is about 7 cm long, 4 cm wide, and 1.8 cm tall. The device is compact, hands-free, and can be adjusted via an innovative touchscreen. Positioning of the probe to the head is performed via conventional transducer gels and pillows. This device is amendable to having advanced software, which could intelligently focus and optimize the TCD signal.

  16. Right Ventricular Tissue Doppler in Space Flight

    Science.gov (United States)

    Hamilton, Douglas R.; Barratt, Michael R.; Sargsyan, Ashot E.; Ebert, Douglas; Garcia, Kathleen M.; Martin, David S.; Dulchavsky, Scott A.; Duncan, J. Michael

    2009-01-01

    Tissue Doppler (TD) registers movement of a given sample of cardiac tissue throughout the cardiac cycle. TD spectra of the right ventricle (RV) were obtained from a long-duration ISS crewmember as a portion of an ongoing experiment ("Braslet" test objective). To our knowledge, this is the first report of RV TD conducted in space flight, and the data represent reproducibility and fidelity of this application in space and serve as the first "space normal" data set. Methods RV TD was performed by astronaut scientists remotely guided by an ultrasound expert from Mission Control Center, Houston, TX. In four of the subjects, RV TD was acquired from the free wall near the tricuspid annulus in two separate sessions 4 to 7 days apart. A fifth subject had only one session. All digital DICOM frames were exported for off-line analysis. Systolic (S ), early diastolic (E ) and late diastolic (A ) velocities were measured. RV Tei-index was calculated using diastolic and systolic time intervals as a combined measure of myocardial performance. Results and Discussion The mean values from the first 4 subjects (8 sessions) were used as the on-orbit reference data, and subject 5 was considered as a hypothetical patient for comparison (see Table). The greatest difference was in the early diastolic A (31 %) yet the standard deviation (a) for A amongst the reference subjects was 2.25 (mean = 16.02). Of interest is the Tei index, a simple and feasible indicator of overall ventricular function; it was similar amongst all the subjects. The late diastolic A seems to compensate for the variance in E . Normal Tei index for the RV is < 0.3, yet our data show all but one subject consistently above this level, notwithstanding their nominal responses to daily exercise in microgravity. These data remind us that the physiology of RV preload in altered gravity environments is still not completely understood.

  17. Comparison between oscillometric- and Doppler-ABI in elderly individuals

    Directory of Open Access Journals (Sweden)

    Takahashi I

    2013-03-01

    Full Text Available Ikuno Takahashi,1,3 Kyoji Furukawa,2 Waka Ohishi,1 Tetsuya Takahashi,3 Masayasu Matsumoto,3 Saeko Fujiwara11Department of Clinical Studies, 2Department of Statistics, Radiation Effects Research Foundation (RERF, Hiroshima, Japan; 3Department of Clinical Neuroscience and Therapeutics, Hiroshima University, Hiroshima, JapanAbstract: Peripheral arterial disease (PAD generally remains under-recognized, mainly due to the specialized technical skills required to detect the low values of the ankle-brachial index (ABI. As a simpler and faster alternative to the standard method using continuous-wave Doppler ultrasound, we evaluated automated oscillometric ABI measurement by VP-2000 with an elderly cohort of 113 subjects (age range, 61 to 88 years. The standard deviation in ABIs measured by the Doppler method was statistically greater than that measured by the oscillometric method for each of the two legs (P < 0.001. Correlations in ABIs between the two methods were 0.46 for the left leg and 0.61 for the right leg; this result appears to have been caused by interobserver variation in the Doppler ABI measurements. While the trend showing greater differences between average oscillometric- and Doppler-ABIs was significant at the lower ABI ranges, there was little indication of differences in measurements having an average ABI > 1.1. The difference between the methods was suggestively larger in subjects who were smokers than in non-smokers (P = 0.09, but the difference was not affected by other potential atherosclerotic risk factors, including age at examination (P > 0.50. A larger difference at lower ABIs led to better PAD detection by the Doppler method compared to the oscillometric method (sensitivity = 50%, specificity = 100%, although the overall agreement was not small (Cohen's Kappa = 0.65. Our findings indicate that oscillometric devices can provide more accurate estimation of the prevalence of PAD in elderly individuals than the conventional Doppler

  18. 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.

  19. Re-Normalization Method of Doppler Lidar Signal for Error Reduction

    International Nuclear Information System (INIS)

    In this paper, we presented a re-normalization method for the fluctuations of Doppler signals from the various noises mainly due to the frequency locking error for a Doppler lidar system. For the Doppler lidar system, we used an injection-seeded pulsed Nd:YAG laser as the transmitter and an iodine filter as the Doppler frequency discriminator. For the Doppler frequency shift measurement, the transmission ratio using the injection-seeded laser is locked to stabilize the frequency. If the frequency locking system is not perfect, the Doppler signal has some error due to the frequency locking error. The re-normalization process of the Doppler signals was performed to reduce this error using an additional laser beam to an Iodine cell. We confirmed that the renormalized Doppler signal shows the stable experimental data much more than that of the averaged Doppler signal using our calibration method, the reduced standard deviation was 4.838 Χ 10-3

  20. 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.

  1. 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.

  2. Comparison Value of Platelet Count /Splenic Diameter Ratio vs Portal System Doppler Study Results for Prediction/Screening of Esophageal Varices

    Directory of Open Access Journals (Sweden)

    Roozbeh Barikbin

    2009-01-01

    Full Text Available "nIntroduction: It is currently recommended that all patients with liver cirrhosis undergo upper gastrointestinal endoscopy (UGIE to identify those who have esophageal varices (EV that carry a high risk of bleeding and may benefit from prophylactic measures. In the future, this social and medical burden will increase due to the greater number of patients with chronic liver disease and their improved survival. "nAIM: To compare value of platelet count/spleen diameter ratio (PC/SD ratio Vs Doppler sonography for the prediction/screening of esophageal varices (EV in cirrhotic patients. "nMaterials and Methods: In this two-year prospective study, patients with liver cirrhosis referred to Al -Zahra hospital were enrolled. Patients underwent detailed clinical examination, blood tests (hematology, liver function tests, ultrasonography and Doppler sonography of the hepato-portal system. The size of esophageal varices were assessed at UGIE; Paquet's grades 0 – III were classified as group A (0-I; no or mild EV and group B (II-III; moderate to severe EV. PC/SD ratio was also measured. The degree of esophageal varices were assessed at UGIE. The relationship of the presence and the degree of EVs with PC/SD ratio and Doppler results were evaluated. "nResults: 50 consecutive cirrhotic patients (age range, 52.1 ±16.2 years; 41 male and 9 female were enrolled. 19 (38% patients were placed in group A (no or mild EV while 31(62% had endoscopic evidence of moderate to severe esophageal varices (group B. PC/SD ratio ROC area under the curve was significant and could significantly predict high risk EV but Doppler ROC area under the curve was not significant but was near significant(AUC=0.64 . PC/SD ratio was more sensitive and has more NPV than Doppler results. "nConclusion: The PC/SD ratio and Doppler results are independently associated with the presence of EV and can predict its severity in patients with cirrhosis. Although Doppler results were very

  3. 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...

  4. Modeling HF Doppler effects of geomagnetic sudden commencements

    International Nuclear Information System (INIS)

    A model has been proposed to explain the ionospheric effects of the sudden commencements as measured with a Doppler sounder. The model consists of two different sources of electric fields generated in the ionosphere during the sudden commencement: a westward electromagnetically induced electric field generated in the F region due to the change of magnetic field and an eastward dynamo electrostatic field set up in the dynamo region and transferred along the geomagnetic field lines to the F region. The change of Doppler frequency shifts during the sudden commencement (ssc) is due to the vertical motion of the charged particles forced by these two opposing electric fields. The theoretical Doppler shifts were calculated on the basis of this model, and four observed ssc's and scf's were used to check the validity of the model

  5. An introduction and guide to effective Doppler assessment.

    Science.gov (United States)

    Benbow, Maureen

    2014-12-01

    Accurate and timely diagnosis of leg ulceration is an essential factor in making evidence-based, effective decisions regarding patient management with the aim of swift wound healing and/or referral to the appropriate specialty. Nurses are professionally responsible for ensuring that patients receive the appropriate assessment and evidence-based management. This article examines the most up-to-date guidance on Doppler ultrasound as a key element of this assessment. Approaches to assessment will be explored, with emphasis on the need to include a Doppler ultrasound as one key element of a larger, holistic assessment. An introduction to the ankle-brachial pressure index (ABPI) will be given, followed by a step-by-step guide to standard procedures for carrying out a full Doppler ultrasound. Alternative options for measuring ABPI are also provided. PMID:25478852

  6. Resting Doppler ankle brachial pressure index measurement: a literature review.

    Science.gov (United States)

    Sihlangu, Dorcus; Bliss, Julie

    2012-07-01

    Peripheral vascular disease (PVD) is under-diagnosed in primary and acute settings. The use of Doppler ankle brachial pressure index (ABPI) is effective in diagnosing PVD , aid in determining aetiology of leg ulcers and is cost efficient in reducing the effects of atherosclerosis and cardiovascular events. The aim of this literature review was to review practitioners' experience in using Doppler ABPI, different skills used to measure ABPI and to examine practitioners' confidence in ABPI. The findings identified variation in method for Doppler measurement: including position of the artery, arm measurement, resting period and type of equipment for measuring blood pressure, variations in practitioners' training and experience have demonstrated variability in ABPI results. Although limited in number, the studies have demonstrated knowledge gap, and the need for training among health professionals. PMID:22875182

  7. Three-dimensional laser cooling at the Doppler limit

    CERN Document Server

    Chang, Rockson; Bouton, Quentin; Fang, Yami; Klafka, Tobias; Audo, Kevin; Aspect, Alain; Westbrook, Christoph I; Clément, David

    2014-01-01

    Many predictions of the theory of Doppler cooling of 2-level atoms, notably the celebrated minimum achievable temperature $T_D=\\hbar \\Gamma/2 k_B$, have never been verified in a three-dimensional geometry. Here, we show that, despite their degenerate level structure, we can use Helium-4 atoms to achieve a situation in which these predictions can be verified. We make measurements of atomic temperatures, magneto-optical trap sizes, and the sensitivity of optical molasses to a power imbalance in the laser beams, finding excellent agreement with the Doppler theory. We show that the special properties of Helium, particularly its small mass and narrow transition linewidth, prevent effective sub-Doppler cooling with red-detuned optical molasses.

  8. 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. PMID:27137615

  9. Non-intrusive Shock Measurements Using Laser Doppler Vibrometers

    Science.gov (United States)

    Statham, Shannon M.; Kolaini, Ali R.

    2012-01-01

    Stud mount accelerometers are widely used by the aerospace industry to measure shock environments during hardware qualification. The commonly used contact-based sensors, however, interfere with the shock waves and distort the acquired signature, which is a concern not actively discussed in the community. To alleviate these interference issues, engineers at the Jet Propulsion Laboratory are investigating the use of non-intrusive sensors, specifically Laser Doppler Vibrometers, as alternatives to the stud mounted accelerometers. This paper will describe shock simulation tests completed at the Jet Propulsion Laboratory, compare the measurements from stud mounted accelerometers and Laser Doppler Vibrometers, and discuss the advantages and disadvantages of introducing Laser Doppler Vibrometers as alternative sensors for measuring shock environments.

  10. A Human Gait Classification Method Based on Radar Doppler Spectrograms

    Directory of Open Access Journals (Sweden)

    Fok Hing Chi Tivive

    2010-01-01

    Full Text Available An image classification technique, which has recently been introduced for visual pattern recognition, is successfully applied for human gait classification based on radar Doppler signatures depicted in the time-frequency domain. The proposed method has three processing stages. The first two stages are designed to extract Doppler features that can effectively characterize human motion based on the nature of arm swings, and the third stage performs classification. Three types of arm motion are considered: free-arm swings, one-arm confined swings, and no-arm swings. The last two arm motions can be indicative of a human carrying objects or a person in stressed situations. The paper discusses the different steps of the proposed method for extracting distinctive Doppler features and demonstrates their contributions to the final and desirable classification rates.

  11. Doppler Tomography in Cataclysmic Variables: an historical perspective

    CERN Document Server

    Echevarria, J

    2012-01-01

    To mark the half-century anniversary of this newly-born field of Cataclysmic Variables, a special emphasis is made in this review, on the Doppler Effect as a tool in astrophysics. The Doppler Effect was in fact, discovered almost 170 years ago, and has been since, one of the most important tools which helped to develop modern astrophysics. We describe and discuss here, its use in Cataclysmic Variables which, combined with another important tool, the tomography, first devised for medical purposes 70 years ago, helped to devise the astronomical Doppler Tomography, developed only two decades ago. A discussion is made since the first trailed spectra provided a one dimensional analysis of these binaries; on the establishment of a 2D velocity profiling of the accretion discs; and unto modern techniques, which include Roche Tomography, time modulation and 3D imaging.

  12. 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.

  13. 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 ...

  14. 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. PMID:26263315

  15. 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.

  16. 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...

  17. 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. PMID:27395440

  18. Effect of surface reflectivity on photonic Doppler velocimetry measurement

    International Nuclear Information System (INIS)

    While photonic Doppler velocimetry (PDV) is becoming a common diagnostic for tracking velocity in shock physical experiments, its validity on measuring surfaces with different reflectivity is not studied. This paper investigates the effects of surface reflectivity on PDV measurement for tracking back free surface velocity in laser shock processing. Credible measurement results for coarse polished surfaces with low reflectivity are obtained, whereas fine polished surfaces with relatively high reflectivity lead to heterodyne fringes with high frequency and corresponding unreasonably fast velocities. This phenomenon reported in the paper is somewhat inconsistent with the general view that PDV has remarkable robustness to large changes in surface reflectivity. The reason might be ascribed to multiple reflections of light, which cause the generation of multiple Doppler shifts. The mixing of the reference light and those Doppler-shifted lights brings out high frequency heterodyne fringes resulting in high velocity. Low surface reflectivity is better suited for PDV measurements. (paper)

  19. Doppler term in the galaxy two-point correlation function: wide-angle, velocity, Doppler lensing and cosmic acceleration effects

    CERN Document Server

    Raccanelli, Alvise; Jeong, Donghui; Neyrinck, Mark C; Szalay, Alexander S

    2016-01-01

    We study the parity-odd part (that we shall call Doppler term) of the linear galaxy two-point correlation function that arises from wide-angle, velocity, Doppler lensing and cosmic acceleration effects. As it is important at low redshift and at large angular separations, the Doppler term is usually neglected in the current generation of galaxy surveys. For future wide-angle galaxy surveys such as Euclid, SPHEREx and SKA, however, we show that the Doppler term must be included. The effect of these terms is dominated by the magnification due to relativistic aberration effects and the slope of the galaxy redshift distribution and it generally mimics the effect of the local type primordial non-Gaussianity with the effective nonlinearity parameter $f_{\\rm NL}^{\\rm eff}$ of a few, we show that this would affect forecasts on measurements of $f_{\\rm NL}$ at low-redshift. Our results show that a survey at low redshift with large number density over a wide area of the sky could detect the Doppler term with a signal-to-...

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

    International Nuclear Information System (INIS)

    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.

  1. 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.

  2. Fano-Doppler laser cooling of hybrid nanostructures.

    Science.gov (United States)

    Ridolfo, Alessandro; Saija, Rosalba; Savasta, Salvatore; Jones, Philip H; Iatì, Maria Antonia; Maragò, Onofrio M

    2011-09-27

    Laser cooling the center-of-mass motion of systems that exhibit Fano resonances is discussed. We find that cooling occurs for red or blue detuning of the laser frequency from resonance depending on the Fano factor associated with the resonance. The combination of the Doppler effect with the radiation cross-section quenching typical of quantum interference yields temperatures below the conventional Doppler limit. This scheme opens perspectives for controlling the motion of mesoscopic systems such as hybrid nanostructures at the quantum regime and the exploration of motional nonclassical states at the nanoscale. PMID:21806014

  3. Accommodations assessment: Spaceborne Doppler lidar wind measuring system

    Science.gov (United States)

    1981-01-01

    An accommodations analysis performed by the MSFC Preliminary Design Office for a spaceborne Doppler lidar wind measuring system is summarized. A dedicated, free-flying spacecraft design concept is described. Mass and beginning-of-life power requirements are estimated at 2260 kg and 6.0 - 8.5 kW respectively, to support a pulsed, CO2, Doppler lidar having a pulse energy of 10 J, pulse rate of 8 Hz, and efficiency of approximately 5%. Under the assumptions of the analysis, such a system would provide wind measurements on a global scale, with accuracies of a few meters per second.

  4. 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.

  5. Emitter location accuracy using TDOA and differential Doppler

    Science.gov (United States)

    Chestnut, P. C.

    1982-03-01

    The time difference of arrival (TDOA) and the differential Doppler methods for locating a radio or sonar transmitter are described, and some relationships between the accuracy of their measurements and the accuracy of the location estimates obtained from the measurements are presented. The formula for the one-sigma width of the lines of constant TDOA and the differential Doppler on the surface of the earth is used to characterize emitter location accuracy. The derived relations can be used by the systems engineer to evaluate proposed systems and to determine system specifications to satisfy given requirements on emitter location accuracy.

  6. Doppler shifts in the coma of Comet P/Halley

    International Nuclear Information System (INIS)

    The relative radial velocities across 70-100 arcsecs of the coma of Comet P/Halley were measured on four days in 1985-1986 on coude CCD spectrograms in order to search for detectable Doppler shifts. The measurements show a trend of positive velocity with respect to projected distance from the nucleus. The shifts are most clearly observed at r = 1.1 AU, where the relative velocity at 10000 km amounted to 3-4 km/s. The Doppler shifts represent an integration through the whole coma. It is suggested that a proper model of the comet is needed to convert the shifts into true outflow velocities. 14 refs

  7. Spectral fine structure effects on material and doppler reactivity worth

    International Nuclear Information System (INIS)

    New formulations concerning the fine structure effects on the reactivity worth of resonances are developed and conclusions are derived following the extension to more general types of perturbations which include: the removal of resonance material at finite temperatures and the temperature variation of part of the resonance material. It is concluded that the flux method can overpredict the reactivity worth of resonance materials more than anticipated. Calculations on the Doppler worth were carried out; the results can be useful for asessing the contribution of the fine structure effects to the large discrepancy that exists between the calculated and measured small sample Doppler worths. (B.G.)

  8. Imaging doppler lidar for wind turbine wake profiling

    Science.gov (United States)

    Bossert, David J.

    2015-11-19

    An imaging Doppler lidar (IDL) enables the measurement of the velocity distribution of a large volume, in parallel, and at high spatial resolution in the wake of a wind turbine. Because the IDL is non-scanning, it can be orders of magnitude faster than conventional coherent lidar approaches. Scattering can be obtained from naturally occurring aerosol particles. Furthermore, the wind velocity can be measured directly from Doppler shifts of the laser light, so the measurement can be accomplished at large standoff and at wide fields-of-view.

  9. Calculation results and experimental testing of doppler feedback coefficients

    International Nuclear Information System (INIS)

    The Doppler feedback coefficients are calculated by the interpolation and group collapsing method from multigroup self-shielding factors and infinite dilution cross sections rather than effective resonance integrals by using resonance data base. Since many updated sets of multigroup data are in existence to be selected, the calculation process can be simplified. The heterogeneous effects are taken into account by equivalence relation. The computer code of Doppler feedback coefficients is created on computer CYBER-825 and PDP-11. The results calculated are in good agreement with the experiments

  10. Catheterization-Doppler discrepancies in nonsimultaneous evaluations of aortic stenosis.

    Science.gov (United States)

    Aghassi, Payam; Aurigemma, Gerard P; Folland, Edward D; Tighe, Dennis A

    2005-05-01

    Prior validation studies have established that simultaneously measured catheter (cath) and Doppler mean pressure gradients (MPG) correlate closely in evaluation of aortic stenosis (AS). In clinical practice, however, cath and Doppler are rarely performed simultaneously; which may lead to discrepant results. Accordingly, our aim was to ascertain agreement between these methods and investigate factors associated with discrepant results. We reviewed findings in 100 consecutive evaluations for AS performed in 97 patients (mean age 72 +/- 10 yr) in which cath and Doppler were performed within 6 weeks. We recorded MPG, aortic valve area (AVA), cardiac output, and ejection fraction (EF) by both methods. Aortic root diameter, left ventricular end-diastolic dimension (LVIDd) and posterior wall thickness (PWT) were measured by echocardiography and gender, heart rate, and heart rhythm were also recorded. An MPG discrepancy was defined as an intrapatient difference > 10 mmHg. Mean pressure gradients by cath and Doppler were 36 +/- 22 mmHg and 37 +/- 20 mmHg, respectively (P = 0.73). Linear regression showed good correlation (r = 0.82) between the techniques. An MPG discrepancy was found in 36 (36%) of 100 evaluations; in 19 (53%) of 36 evaluations MPG by Doppler was higher than cath, and in 17 (47%) of 36, it was lower. In 33 evaluations, EF differed by >10% between techniques. Linear regression analyses revealed that EF difference between studies was a significant predictor of MPG discrepancy (P = 0.004). Women had significantly higher MPG than men by both cath and Doppler (43 +/- 25 mmHg versus 29 +/- 15 mmHg [P = 0.001]; 42 +/- 23 mmHg versus 32 +/- 15 mmHg [P = 0.014], respectively). Women exhibited discrepant results in 23 (47%) of 49 evaluations versus 13 (25%) of 51 evaluations in men (P = 0.037). After adjustment for women's higher MPG, there was no statistically significant difference in MPG discrepancy between genders (P = 0.22). No significant interactions between

  11. Determination of Doppler Effect on nuclear resonances of uranium-238

    International Nuclear Information System (INIS)

    This paper deals with theoretical and experimental study of Doppler effect on 238U resonances. The chosen experimental method was based on measuring gamma activities of irradiated UO2 samples with natural uranium since this activity depends on the total absorption in 238U dependent on the temperature of the sample. Special electrical heater was used for heating the samples irradiated in the core of RB reactor. Due to significant perturbation of neutron flux caused by the presence of the heater it was necessary to develop a model for calculation of Doppler effect on 238U in the used sample. Scintillation NaI(Tl) detector was used for gamma activity measurements

  12. Void effects on BWR Doppler and void reactivity feedback

    International Nuclear Information System (INIS)

    The significance of steam voids and control rods on the Doppler feedback in a gadolinia shimmed BWR is demonstrated. The importance of bypass voids when determining void feedback is also shown. Calculations were done using a point model, i.e., feedback was expressed in terms of reactivity coefficients which were determined for individual four-bundle configurations and then appropriately combined to yield reactor results. For overpower transients the inclusion of the void effect of control rods is to reduce Doppler feedback. For overpressurization transients the inclusion of the effect of bypass void wil increase the reactivity due to void collapse. (author)

  13. 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.

  14. Prenatal color Doppler ultrasonographic diagnosis of fetal tetralogy of Fallot

    International Nuclear Information System (INIS)

    Objective: To investigate the sonographic findings of tetralogy of Fallot in fetuses. Methods: The data of color Doppler ultrasonography and follow-up results of 5 fetal tetralogy of Fallot were analyzed retrospectively, and their abnormal ultrasound imaging characteristic were summarized. Results: Two cases were proved tetralogy of Fallot by autopsy, and three cases were confirmed to be tetralogy of Fallot by echocardiography after birth. The image features were the main aorta situated above the ventricular septal defect, pulmonary stenosis, no obvious thickening of the right wall. Conclusion: Fetal tetralogy of Fallot have characteristic ultrasound images, prenatal color Doppler ultrasonographic can diagnoses fetal tetralogy of Fallot correctly and has important clinical value. (authors)

  15. Special Theory of Relativity through the Doppler Effect

    OpenAIRE

    Moriconi, M.

    2006-01-01

    We present the special theory of relativity taking the Doppler effect as the starting point, and derive several of its main effects, such as time dilation, length contraction, addition of velocities, and the mass-energy relation, and assuming energy and momentum conservation, we discuss how to introduce the 4-momentum in a natural way. We also use the Doppler effect to explain the "twin paradox", and its version on a cylinder. As a by-product we discuss Bell's spaceship paradox, and the Loren...

  16. The Dependence of the Resonance Integral on the Doppler Effect

    International Nuclear Information System (INIS)

    The Doppler sensitive contributions to the resonance integral for metal and oxide cylinders have been calculated using tables compiled by Adler, Hinman and Nordheim. The temperatures 20, 200, 350, 500 and 650 deg C have been investigated for the pure metal and 20, 300, 600, 900 and 1200 deg C for the oxide. Contributions from the separate resonances in the resolved region and for certain energies in the unresolved region are accounted for in detail. Integration over adequate statistical distributions has been carried out for the resonance parameters in the unresolved region. The increase in the resonance integral at elevated temperatures due to the Doppler effect is given separately in tables and diagrams

  17. The case of the Doppler effect for photons revisited

    International Nuclear Information System (INIS)

    A detailed account is presented of the Doppler effect as a photon phenomenon, complementing a recent paper by Giuliani (2013 Eur. J. Phys. 34 1035–47). The essence of Schrödinger's pioneering derivation (1922 Phys. Z. 23 301–3) of a Doppler formula in terms of the corpuscular theory of light, using energy–momentum conservation, is related. Some neglected references that put the whole scene around the Ives–Stilwell experiment into a more precise perspective are highlighted. Atoms as clocks and particle–wave complementarity are also discussed briefly. (paper)

  18. Avaliação ultra-sonográfica e ao Doppler dos TIPS (anastomose portossistêmica intra-hepática transjugular) Ultrasonographic Doppler evaluation of TIPS (transjugular intrahepatic portosystemic shunt)

    OpenAIRE

    Márcio Martins Machado; Ana Cláudia Ferreira Rosa; Nestor de Barros; Murilo Tavares Daher; Renato Tavares Daher; Letícia Martins Azeredo; Luciana Mendes de Oliveira Cerri; William Abrão Saad; Giovanni Guido Cerri

    2004-01-01

    A anastomose portossistêmica intra-hepática transjugular (TIPS) compreende a técnica mais recente e mais popular para o alívio da hipertensão portal sintomática, especialmente para os casos com varizes e hemorragia digestiva alta, e menos comumente para o tratamento da ascite refratária. Os TIPS podem apresentar complicações após sua colocação, como as estenoses e oclusões. A ultra-sonografia e o Doppler permitem o estudo dos TIPS de uma forma não invasiva. Neste artigo os autores relatam os ...

  19. Discovery of a Doppler-limited CO line in the upper mesosphere of Venus - A new dynamical probe

    Science.gov (United States)

    Buhl, David; Chin, Gordon; Goldstein, Jeffrey J.

    1991-01-01

    The presence of CO in the upper atmosphere of Venus is a consequence of the photochemistry of CO2, the dominant atmospheric constituent. In December 1989 the J = 1-2 transition of CO was observed at 230 GHz. In addition to the broad absorption line first reported by Kakar et al. (1976), a narrow absorption feature at the center of the line due to upper mesospheric CO, where the temperature profile starts to exhibit diurnal variation with altitude. The narrow feature is approximately 600 kHz wide and is predominantly Doppler-broadened. The Doppler core provides a new means of measuring wind velocities at these altitudes in the atmosphere of Venus. Detection of small Doppler shifts in the line core can in principle be used to measure winds with an accuracy of 10 m/s. Results are presently limited by the 17 kHz uncertainty in the measured rest frequency, corresponding to a systematic error in wind velocity up to 22 m/s, and the absence of laboratory measurements of the pressure shift in CO by CO2.

  20. Multi-beam raindrop size distributions retrievals on the Doppler spectra: Influence of averaging and mean horizontal wind correction

    OpenAIRE

    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 to the raindrop size distribution along the Doppler velocity interval. Furthermore, the Doppler spectrum may be broadened by turbulence effect. The Doppler spectra of rain are modelled using Rayle...

  1. Doppler-shifted cyclotron resonance of fast ions with circularly polarized shear Alfven waves

    International Nuclear Information System (INIS)

    The Doppler-shifted cyclotron resonance between fast ions and shear Alfven waves (SAWs) has been experimentally investigated with a test-particle fast-ion (Li+) beam launched in the helium plasma of the Large Plasma Device [Gekelman et al., Rev. Sci. Instrum. 62, 2875 (1991)]. Left- or right-hand circularly polarized SAWs are launched by an antenna with four current channels. A collimated fast-ion energy analyzer characterizes the resonance by measuring the nonclassical spreading of the averaged beam signal. Left-hand circularly polarized SAWs resonate with the fast ions but right-hand circularly polarized SAWs do not. The measured fast-ion profiles are compared with simulations by a Monte Carlo Lorentz code that uses the measured wave field data.

  2. Narrow-Band Searches for Gravitational Radiation with Spacecraft Doppler Tracking

    Science.gov (United States)

    Tinto, M.; Armstrong, J. W.

    1997-01-01

    We discuss a filtering technique for reducing the two-way Doppler frequency fluctuations of noise sources localized in space that affect the sensitivity of spacecraft Doppler tracking searches for gravitational radiation.

  3. Acoustic doppler methods for remote measurements of ocean flows - a review

    Digital Repository Service at National Institute of Oceanography (India)

    Joseph, A.

    The evolution of acoustic doppler methods for remote measurements of ocean flows has been briefly reviewed in historical perspective. Both Eulerian and profiling methods have been discussed. Although the first acoustic Doppler current meter has been...

  4. IMPROVING THE RELIABILITY OF VENOUS DOPPLER FLOW MEASUREMENTS: RELEVANCE OF COMBINED ECG, TRAINING AND REPEATED MEASURES

    OpenAIRE

    STAELENS, Anneleen; Tomsin, Kathleen; OBEN, Jolien; Mesens, Tinne; Grieten, Lars; Gyselaers, Wilfried

    2014-01-01

    The nature of venous Doppler waves is highly variable. An additional electrocardiogram (ECG) improves the interpretation of venous Doppler wave characteristics and allows measurement of venous pulse transit time. The purpose of this study was to assess the reproducibility of ECG-guided repeated measurements of venous Doppler flow characteristics before and after sonographer training and the inter-and intra-observer variability. In four groups of 25 healthy women, venous Doppler flow measureme...

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

    OpenAIRE

    Bo Yun Hur; Jae Young Lee; A Jung Chu; Se Hyung Kim; Joon Koo Han; Byung Ihn Choi

    2015-01-01

    Purpose: The purpose of this study was to investigate the value of UltraFast Doppler ultrasonography (US) for evaluating hepatic vessels in liver recipients. Methods: 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 dec...

  6. Design and Implementation of High Frequency Ultrasound Pulsed-Wave Doppler Using FPGA

    OpenAIRE

    Hu, Chang-Hong; Zhou, Qifa; Shung, K. Kirk

    2008-01-01

    The development of a field-programmable gate array (FPGA)-based pulsed-wave Doppler processing approach in pure digital domain is reported in this paper. After the ultrasound signals are digitized, directional Doppler frequency shifts are obtained with a digital-down converter followed by a low-pass filter. A Doppler spectrum is then calculated using the complex fast Fourier transform core inside the FPGA. In this approach, a pulsed-wave Doppler implementation core with reconfigurable and rea...

  7. Efficient material characterization by means of the Doppler effect in microwaves

    OpenAIRE

    Pinchuk, Roman

    2007-01-01

    Subject of this thesis is the efficient material characterization and defects detection by means of the Doppler effect with microwaves. The first main goal of the work is to develop a prototype of a microwave Doppler system for Non-Destructive Testing (NDT) purposes. Therefore it is necessary that the Doppler system satisfies the following requirements: non-expensive, easily integrated into industrial process, allows fast measurements. The Doppler system needs to include software for hardware...

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

    OpenAIRE

    Jinsong Tang; Kun Fang; Sen Zhang

    2013-01-01

    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 presen...

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

    OpenAIRE

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

    2015-01-01

    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 reconfigur...

  10. Classification of Small UAVs and Birds by Micro-Doppler Signatures

    NARCIS (Netherlands)

    Molchanov, P.; Egiazarian, K.; Astola, J.; Harmanny, R.I.A.; Wit, J.J.M. de

    2013-01-01

    The problem of unmanned aerial vehicles classification using continuous wave radar is considered in this paper. Classification features are extracted from micro-Doppler signature. Before the classification, the micro-Doppler signature is filtered and aligned to compensate the Doppler shift caused by

  11. 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.

  12. Doppler Effect Associated with the Reflection of Light on a Moving Mirror

    OpenAIRE

    Rothenstein, Bernhard; Damian, Ioan

    2005-01-01

    The Doppler Effect associated with the reflection on a moving mirror is reduced to two Doppler Effect experiments involving the incoming incident ray and the outgoing reflected ray or vice-versa. The dependence of the corresponding Doppler factors on the incidence angle on the stationary mirror.

  13. Color Doppler Ultrasonographic Findings of Vascular Leiomyoma: Pathologic Correlation

    International Nuclear Information System (INIS)

    To evaluate the distribution of color flow signals on color Doppler ultrasonography of vascular leiomyomas and to correlate them with pathologic findings. We retrospectively analyzed color Doppler ultrasonographic images and pathologic slides of six vascular leiomyomas. We classified the patterns of distribution of color flow signals into localized compact cluster types and non-cluster types, and the pathologic findings into three subtypes: solid, venous and cavernous. All cases showed well-defined homogenous hypoechoic subcutaneous masses on gray-scale ultrasonography. Three cases showed localized compact cluster types on color Doppler ultrasonography, one in each subtype (solid, venous and cavernous). For the three non-cluster types, again there was on in each subtype. In addition, on pathologic analysis the zone of the localized compact cluster of color flow signals coincided with a cluster of larger, vascular caliber masses. Localized compact clusters of color flow signals on color Doppler ultrasonography were seen in 50% of our cases and correlated with a cluster of larger vascular caliber in the mass. But the pattern of distribution of color flows didn't show a correlation with pathologic type

  14. HF Doppler Acoustic Imaging of the Ocean Surface and Interior

    Science.gov (United States)

    Pinkel, Robert; Smith, Jerome A.

    2004-11-01

    HF phased array Doppler sonar represents a new tool for obtaining Three-dimensional (r,q,t) images of the oceanic surface and interior velocity field. While the capabilities of the approach are unique, the design constraints are also unusual. Examples of both are presented in this work.

  15. 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.

  16. Ultrasonography and color Doppler in juvenile idiopathic arthritis

    DEFF Research Database (Denmark)

    Laurell, Louise; Court-Payen, Michel; Nielsen, Susan; Zak, Marek; Fasth, Anders

    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...

  17. 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.

  18. Worldwide network for ionospheric Doppler sounding operated by IAP Prague

    Czech Academy of Sciences Publication Activity Database

    Šindelářová, Tereza; Laštovička, Jan; Chum, Jaroslav; Baše, Jiří; Hruška, František

    ARISE, 2015. [ARISE2 Kickoff Meeting. 05.10.2014-09.10.2015, Collioure] R&D Projects: GA ČR GP13-09778P; GA ČR GC15-07281J Institutional support: RVO:68378289 Keywords : Doppler sounding * ionosphere Subject RIV: DG - Athmosphere Sciences, Meteorology

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

    DEFF Research Database (Denmark)

    Hansen, Henrik; Affes, Sofiéne; Mermelstein, Paul

    1999-01-01

    capacities in low and high speed situations. We derive a Doppler frequency estimator using the maximum likelihood method and Jakes model (1974) of a Rayleigh fading channel. This estimator requires an FFT and simple post-processing only. Its performance is verified through simulations and found to yield good...

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

    DEFF Research Database (Denmark)

    Hansen, Henrik; Affes, Sofiene; Mermelstein, Paul

    1999-01-01

    capacities in low and high speed situations.We derive a Doppler frequency estimatorusing the maximum likelihood method and Jakes model [\\ref{Jakes}] of a Rayleigh fading channel. This estimator requires an FFT and simple post-processing only. Its performance is verifiedthrough simulations and found to yield...

  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. Usefulness of Doppler Parameter in Patients with Renal Transplantation

    International Nuclear Information System (INIS)

    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.

  3. Doppler-free spectroscopy on tantalum atomic beam

    International Nuclear Information System (INIS)

    We demonstrate the usefulness of an atomic beam source for refractory metals in Doppler-free spectroscopy. The splittings between seven hyperfine components of the weak 578.01 nm transition in TaI are measured to +- 1 MHz. The hyperfine A and B coefficients for the upper and lower level are determined from the observed splittings. (orig.)

  4. Enhanced color Doppler sonography of eye and orbit tumors

    International Nuclear Information System (INIS)

    They investigated the diagnostic efficacy of the administration of a sonography (US) contrast agent to study eye and orbit tumors at different stages. They administered Levovist (Schering), an air micro bubble stabilized by fatty acid, which is specific for angiographic indications. Baseline color Doppler US was performed on 24 selected patients and tumor vascularization patterns were classified into 3 classes. Color Doppler signal enhancement was assessed after contrast agent administration and the signal-to-noise ratio (SNR) was improved in 70 % of cases, which helped identify vascular patterns and improved flow metric accuracy. The Doppler effect was also improved and vascular signal was always enhanced. The SNR was improved also by the postcontrast detection of small vessels missed on baseline scans. Doppler signal enhancement was proportional to precontrast vascularization and depended on tumor size, with poor results in lesions < 5 mm. In contrast, vascular signal spots with increased postcontrast echogenicity sometimes caused excessive noise affecting the results. No correlation was found between signal enhancement and lesion histotype or between signal and lesion site. Treated lesions exhibited poorer contrast agent enhancement. The examination technique must be accurate and the various parameters set optimally, especially the velocity scale, gain and filtration; the unit must feature adequate recording capabilities. To conclude, they believe that the routine use of i.v. US contrast agents will play a major role in improving diagnostic imaging in oculistics also thanks to the lack of untoward reactions and to the ease of contrast agent preparation

  5. Sub-Doppler resolution with double coherently driving fields

    CERN Document Server

    Dong, P; Hai, T S; Gao, J Y; Dong, Po; Hai, Tang Sing; Gao, Jin-Yue

    2000-01-01

    We propose a four-level model where sub-Doppler resolution as well as enhanced absorption of a weak probe field are realized by using two coherently driving fields. We show that spectral resolution can be improved by modifying the coherent fields intensity and frequencies.

  6. 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.

  7. The lineshape problem in Doppler-width thermometry

    Science.gov (United States)

    Domenica De Vizia, Maria; Moretti, Luigi; Castrillo, Antonio; Fasci, Eugenio; Gianfrani, Livio

    2011-09-01

    Typically eliminated in any experiment of time and frequency metrology, the Doppler broadening effect can be regarded as a gift of nature for the purpose of measuring the thermodynamic temperature of a gaseous sample. Nevertheless, Doppler-width retrieval from highly-accurate absorption spectra is surely not an easy task as it requires an adequate knowledge of the lineshape function, accounting for the different mechanisms that contribute to the overall linewidth. Semiclassical theories provide several possibilities, more or less accurate in reproducing the observed profiles. Here, the influence of the choice of the lineshape model in Doppler-width thermometry is investigated in the physical situation of self-colliding ? O molecules. A large number of absorption profiles were simulated, using the uncorrelated version of the speed-dependent Galatry profile and setting different values for the gas pressure, the signal-to-noise ratio and the Dicke-narrowing parameter. Spectral analysis was performed by means of different models, in order to retrieve the zero-pressure value of the Doppler width. It turned out that precision and accuracy can be pushed to extreme levels provided that the signal-to-noise ratio is sufficiently high (namely, larger than 50,000) and that a speed-dependent lineshape model is used.

  8. Estimation of amputation level with a laser Doppler flowmeter

    DEFF Research Database (Denmark)

    Gebuhr, Peter Henrik; Jørgensen, J P; Vollmer-Larsen, B; Nielsen, S L; Alsbjørn, 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...... was found between the successful amputation levels and the maximal blood perfusion of the skin measured in this way....

  9. Doppler Spectrum from Moving Scatterers in a Random Environment

    DEFF Research Database (Denmark)

    Andersen, Jørgen Bach; Nielsen, Jesper Ødum; Pedersen, Gert Frølund; Bauch, Gerhard; Dietl, Guido

    2009-01-01

    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...

  10. 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.

  11. Noise Studies of Externally Dispersed Interferometry for Doppler Velocimetry

    International Nuclear Information System (INIS)

    Externally Dispersed Interferometry (EDI) is the series combination of a fixed-delay field-widened Michelson interferometer with a dispersive spectrograph. This combination boosts the spectrograph performance for both Doppler velocimetry and high resolution spectroscopy. The interferometer creates a periodic comb that multiplies against the input spectrum to create moire fringes, which are recorded in combination with the regular spectrum. Both regular and high-frequency spectral components can be recovered from the data--the moire component carries additional information that increases the signal to noise for velocimetry and spectroscopy. Here we present simulations and theoretical studies of the photon limited Doppler velocity noise in an EDI. We used a model spectrum of a 1600K temperature star. For several rotational blurring velocities 0, 7.5, 15 and 25 km/s we calculated the dimensionless Doppler quality index (Q) versus wavenumber v. This is the normalized RMS of the derivative of the spectrum and is proportional to the photon-limited Doppler signal to noise ratio

  12. 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...

  13. 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.

  14. 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.

  15. 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)

  16. 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…

  17. 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.

  18. 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.

  19. Solar Supergranulation Waves Detected in Surface Doppler Shift

    CERN Document Server

    Schou, J

    2002-01-01

    Recently Gizon, Duvall and Schou (2002) suggested that supergranulation has a wave-like component. In this paper I show that the same phenomenon can be observed using surface Doppler shift data, thereby confirming their observations. I am also able to measure the dispersion relation to lower wavenumbers and to extend the results for rotation and meridional flows beyond +/-70 degrees latitude.

  20. Laser Doppler velocimetry in Microchannels using integrated optical waveguides.

    NARCIS (Netherlands)

    Pandraud, G.; Berg, van den A.; Semenov, S.N.

    2000-01-01

    The possibility of laser Doppler velocimetry (LDV) in microchannels, where particles are suspended in a liquid, and where oscillating or evanescent guided coherent light wave is present, is examined theoretically. The conditions for the observation of the transverse and longitudinal collective phore

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

    OpenAIRE

    Prior Yehiam; Averbukh Ilya Sh; Gordon Robert; Steinitz Uri; Korech Omer

    2013-01-01

    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.

  2. 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.

  3. Generalized Doppler effect in spaces with a transport along paths

    OpenAIRE

    Iliev, Bozhidar Z.

    2004-01-01

    An analog of the classical Doppler effect is investigated in spaces (manifolds) whose tangent bundle is endowed with a transport along paths, which, in particular, can be parallel one. The obtained results are valid irrespectively to the particles mass, i.e. they hold for massless particles (e.g. photons) as well as for massive ones.

  4. 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

  5. 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

  6. 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.

  7. Doppler ultrasound scan during normal gestation: umbilical circulation

    International Nuclear Information System (INIS)

    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

  8. Non-Gaussianity and CMB aberration and Doppler

    International Nuclear Information System (INIS)

    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 fNL. 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. Using the value v/c = 1.23 × 10−3 for our peculiar velocity, we found that the aberration/Doppler induced non-Gaussian signal is at most of about half of the cosmic variance σ for fNL both in a full-sky and in a cut-sky experimental configuration, for local, equilateral and orthogonal estimators. We conclude therefore that when estimating fNL it is safe to ignore aberration and Doppler effects if the primordial map is already Gaussian. More work is necessary however to assess whether a map which contains non-Gaussianity can be significantly distorted by a peculiar velocity

  9. Doppler detection of decompression bubbles with computer assisted digitization of ultrasonic signals

    Science.gov (United States)

    Butler, B. D.; Robinson, R.; Fife, C.; Sutton, T.

    1991-01-01

    The use of an inexpensive, commercially available audio digitizer in conjunction with a PC to digitize Doppler bubble signals for visual and electronic evaluation is reported. This device can be operated simultaneously with Doppler audio monitoring. Precordial and arterial Doppler recordings of gas bubbles were obtained from anesthetized dogs after intravascular infusion or following decompression. Additional evaluations were conducted on Doppler bubble recordings obtained from human decompression studies. The device can be used in real-time or for later signal analysis. Accompanying menu-driven software provides for numerous signal modification options and visual displays. This device can provide a simultaneous visual display of Doppler signals normally available only for audio evaluation.

  10. 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

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

    Science.gov (United States)

    Kjærgaard, Jesper

    2012-03-01

    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 is a promising tool for improving our understanding of right ventricular hemodynamics, several aspects of the technology must be evaluated. The accuracy and reproducibility of the technology is evaluated in vitro, and normal values, impact of changes in loading of the right ventricle, response to exercise and pharmacological pulmonary vasodilatation is established in normal subjects. The diagnostic and prognostic importance of adding tissue Doppler echocardiography to conventional echocardiographic and clinical parameters was evaluated in studies on patients with diseases associated with different modes of impact on right ventricular hemodynamics: pulmonary embolism, Arrhythmogenic right ventricular cardiomyopathy and pulmonary regurgitation, the latter in an animal model. The conclusions of the thesis are: Color tissue Doppler echocardiography accurately measures velocities, SR and strain in vitro. No systematic bias between ultrasound systems can be found, and accuracy of the measurements is good. However, the reproducibility of measurements in a test-retest design can limit the usefulness of the technology in daily clinical use, as 25% to 80% of change would be needed for the technology to identify a change in individual patients [I]. Normal values of tissue Doppler based measurements of RV regional velocities, SR and strain exist, and apply to both sexes and in all age groups with the exception of slightly decreasing values in strain with increasing age. Increasing preload and afterload changes regional 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

  12. Micro-Doppler analysis of multiple frequency continuous wave radar signatures

    Science.gov (United States)

    Anderson, Michael G.; Rogers, Robert L.

    2007-04-01

    Micro-Doppler refers to Doppler scattering returns produced by non rigid-body motion. Micro-Doppler gives rise to many detailed radar image features in addition to those associated with bulk target motion. Targets of different classes (for example, humans, animals, and vehicles) produce micro-Doppler images that are often distinguishable even by nonexpert observers. Micro-Doppler features have great potential for use in automatic target classification algorithms. Although the potential benefit of using micro-Doppler in classification algorithms is high, relatively little experimental (non-synthetic) micro-Doppler data exists. Much of the existing experimental data comes from highly cooperative targets (human or vehicle targets directly approaching the radar). This research involved field data collection and analysis of micro-Doppler radar signatures from non-cooperative targets. The data was collected using a low cost Xband multiple frequency continuous wave (MFCW) radar with three transmit frequencies. The collected MFCW radar signatures contain data from humans, vehicles, and animals. The presented data includes micro-Doppler signatures previously unavailable in the literature such as crawling humans and various animal species. The animal micro-Doppler signatures include deer, dog, and goat datasets. This research focuses on the analysis of micro-Doppler from noncooperative targets approaching the radar at various angles, maneuvers, and postures.

  13. 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.

  14. Scanning laser doppler velocimeter using iodine iodine-vapor discriminator

    International Nuclear Information System (INIS)

    This paper presents a scanning laser doppler velocimeter (SLDV) that is able to measure the velocity over two dimensions. SDV can be used to measure the 2-D velocity of a rotating disk or fluid by using the molecular iodine absorption line (1109) as the frequency discrimination to determine the doppler shift of the target backscattering. The laser source, a narrow line-width Nd:YAG laser at the second harmonic, is frequency locked to the 1109 line as the frequency reference by a digital PID servo with the frequency jitter less than 1 MHz for arbitrarily long periods. Experimental results show that SDV is capable of mapping the speed vector of the target, and the measurement uncertainty of the rotating disk speed is less than 0.25 m/s.

  15. Phonon Properties of Materials from Neutron Resonance Doppler Broadening Measurements

    Science.gov (United States)

    Eric Lynn, J.

    2002-12-01

    At low temperatures the Doppler broadened widths of neutron resonances are strongly affected by the phonon characteristics of the material used for making the cross-section measurement. The Doppler width can be expressed in terms of the moments of the phonon spectrum carried by the atomic species with the resonant cross-section. Cross-section measurements made with tungsten and tantalum metals are reviewed here and compared with phonon information obtained by other methods. Applications of the method to a plutonium-gallium alloy and to some lanthanum barium cuprates are described briefly. We discuss possible extensions of the technique and how an epithermal flight path at the SNS may be advantageous.

  16. HF Doppler observations of acoustic waves excited by the earthquake

    Science.gov (United States)

    Ichinose, T.; Takagi, K.; Tanaka, T.; Okuzawa, T.; Shibata, T.; Sato, Y.; Nagasawa, C.; Ogawa, T.

    1985-01-01

    Ionospheric disturbances caused by the earthquake of a relatively small and large epicentral distance have been detected by a network of HF-Doppler sounders in central Japan and Kyoto station, respectively. The HF-Doppler data of a small epicentral distance, together with the seismic data, have been used to formulate a mechanism whereby ionospheric disturbances are produced by the Urakawa-Oki earthquake in Japan. Comparison of the dynamic spectra of these data has revealed experimentally that the atmosphere acts as a low-pass filter for upward-propagating acoustic waves. By surveying the earthquakes for which the magnitude M is larger than 6.0, researchers found the ionospheric effect in 16 cases of 82 seismic events. As almost all these effects have occurred in the daytime, it is considered that it may result from the filtering effect of the upward-propagating acoustic waves.

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

    DEFF Research Database (Denmark)

    Kjærgaard, Jesper

    2012-01-01

    right ventricular hemodynamics: pulmonary embolism, Arrhythmogenic right ventricular cardiomyopathy and pulmonary regurgitation, the latter in an animal model. The conclusions of the thesis are: Color tissue Doppler echocardiography accurately measures velocities, SR and strain in vitro. No systematic......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 is a...... promising tool for improving our understanding of right ventricular hemodynamics, several aspects of the technology must be evaluated. The accuracy and reproducibility of the technology is evaluated in vitro, and normal values, impact of changes in loading of the right ventricle, response to exercise and...

  18. 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.

  19. Ionospheric S-shaped Doppler fluctuations produced by the tornadoes

    Science.gov (United States)

    Hung, R. J.; Rao, G. L.; Smith, R. E.

    1974-01-01

    A three-dimensional nine element HF-CW Doppler sounder array has been used to detect ionospheric disturbances which may be due to tornadoes. The typical events chosen in the present study occurred on November 20 and 27, 1973. Both events are apparently associated with tornadoes sighted in the Huntsville, Alabama area. The Doppler records show S-shaped waves rather than the quasi-sinusoidal waves observed in conjunction with and apparently due to thunderstorms. The wave-periods are in the range of 6 to 8 minutes instead of the 3 to 5 minute periods associated with thunderstorms. Dissipation of waves is mostly due to the evanescent effect and they cannot propagate very far from the path of the tornado center. A theory is presented which is in good agreement with the observations.

  20. Imaging, Doppler, and spectroscopic radars from 95 to 700 GHz

    Science.gov (United States)

    Cooper, Ken B.

    2016-05-01

    Imaging, Doppler, and spectroscopic radars from 95 to 700 GHz, all using the frequency-modulated continuous-wave technique, are in various stages of development for both defense and science applications at the Jet Propulsion Laboratory. For standoff security screening, a 340 GHz imaging radar now achieves an 8.3 Hz frame, and it has been tested using power-efficient MMIC-based active multiplier sources into its front end. That system evolved from a 680 GHz security radar platform, which has also been modified to operate in a Doppler mode for probing the dynamics of blowing sand and sensing small-amplitude target vibrations. Meanwhile, 95 and 183 GHz radars based on similar RF architectures are currently being developed to probe cometary jets in space and, using a differential absorption technique, humidity inside upper-tropospheric clouds.

  1. Multipoint photonic doppler velocimetry using optical lens elements

    Science.gov (United States)

    Frogget, Brent Copely; Romero, Vincent Todd

    2014-04-29

    A probe including a fisheye lens is disclosed to measure the velocity distribution of a moving surface along many lines of sight. Laser light, directed to the surface and then reflected back from the surface, is Doppler shifted by the moving surface, collected into fisheye lens, and then directed to detection equipment through optic fibers. The received light is mixed with reference laser light and using photonic Doppler velocimetry, a continuous time record of the surface movement is obtained. An array of single-mode optical fibers provides an optic signal to an index-matching lens and eventually to a fisheye lens. The fiber array flat polished and coupled to the index-matching lens using index-matching gel. Numerous fibers in a fiber array project numerous rays through the fisheye lens which in turn project many measurement points at numerous different locations to establish surface coverage over a hemispherical shape with very little crosstalk.

  2. 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

  3. 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.

  4. High Frequency Color Doppler Image of Choroidal Detachment

    Institute of Scientific and Technical Information of China (English)

    JinghongWu; LijuanZou; 等

    2002-01-01

    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.

  5. Ultrasonic Doppler Velocimetry Measurements on the Madison Dynamo Experiment

    Science.gov (United States)

    Jacobson, C. M.; Forest, C. B.; Kendrick, R. D.; Nornberg, M. D.; Parada, C. A.; Spence, E. J.

    2006-10-01

    The Madison Dynamo Experiment is used to study the generation of magnetic fields in a homogeneous fluid. Flows of liquid sodium in the one-meter-diameter spherical vessel are generated by two counter-rotating impellers. Both the shape and magnitude of the velocity field must be well-understood to predict whether the magnetic field will grow or decay. Ultrasonic Doppler Velocimetry (UDV) is used to measure components of the velocity field in a dimensionally-identical water version of the experiment. Several ultrasonic transducers are used to simultaneously measure the flow along several chords of the vessel. Both neutral density polystyrene beads and air bubbles are used to reflect the ultrasonic pulses. UDV measurements, supplemented by two-component Laser Doppler Velocimetry measurements, are used in a fitting routine to model the flow in terms of spherical harmonics.

  6. 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....... Eight patients had a temporary shunt owing to contralateral occlusion or a stump pressure below 40 mmHg, and/or EEG flattening. Transcranial Doppler sonography was followed intra-operatively together with electro-encephalography (EEG), internal carotid artery (ICA) pressures and cerebral blood flow (CBF...... Vmean clamp: Vmean pre-clamp ratio of less than 0.6 showed an accuracy with respect to CBF below 20 ml 100 g-1 min-1 of 89%. AVmeanclamp:Vmean pre-clamp ratio below 0.4 detected all all patients with EEG flattening (n = 3) (accuracy 97%). The corresponding level of accuracy obtained with stump pressure...

  7. Altered Doppler flow patterns in cirrhosis patients: an overview

    Directory of Open Access Journals (Sweden)

    Pooya Iranpour

    2016-01-01

    Full Text Available 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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

  14. Theoretical model for Sub-Doppler Cooling with EIT System

    Science.gov (United States)

    He, Peiru; Tengdin, Phoebe; Anderson, Dana; Rey, Ana Maria; Holland, Murray

    2016-05-01

    We propose a of sub-Doppler cooling mechanism that takes advantage of the unique spectral features and extreme dispersion generated by the so-called Electromagnetically Induced Transparency (EIT) effect, a destructive quantum interference phenomenon experienced by atoms with Lambda-shaped energy levels when illuminated by two light fields with appropriate frequencies. By detuning the probe lasers slightly from the ``dark resonance'', we observe that atoms can be significantly cooled down by the strong viscous force within the transparency window, while being just slightly heated by the diffusion caused by the small absorption near resonance. In contrast to polarization gradient cooling or EIT sideband cooling, no external magnetic field or external confining potential are required. Using a semi-classical method, analytical expressions, and numerical simulations, we demonstrate that the proposed EIT cooling method can lead to temperatures well below the Doppler limit. This work is supported by NSF and NIST.

  15. 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.

  16. 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

  17. Separation of Doppler radar-based respiratory signatures.

    Science.gov (United States)

    Lee, Yee Siong; Pathirana, Pubudu N; Evans, Robin J; Steinfort, Christopher L

    2016-08-01

    Respiration detection using microwave Doppler radar has attracted significant interest primarily due to its unobtrusive form of measurement. With less preparation in comparison with attaching physical sensors on the body or wearing special clothing, Doppler radar for respiration detection and monitoring is particularly useful for long-term monitoring applications such as sleep studies (i.e. sleep apnoea, SIDS). However, motion artefacts and interference from multiple sources limit the widespread use and the scope of potential applications of this technique. Utilising the recent advances in independent component analysis (ICA) and multiple antenna configuration schemes, this work investigates the feasibility of decomposing respiratory signatures into each subject from the Doppler-based measurements. Experimental results demonstrated that FastICA is capable of separating two distinct respiratory signatures from two subjects adjacent to each other even in the presence of apnoea. In each test scenario, the separated respiratory patterns correlate closely to the reference respiration strap readings. The effectiveness of FastICA in dealing with the mixed Doppler radar respiration signals confirms its applicability in healthcare applications, especially in long-term home-based monitoring as it usually involves at least two people in the same environment (i.e. two people sleeping next to each other). Further, the use of FastICA to separate involuntary movements such as the arm swing from the respiratory signatures of a single subject was explored in a multiple antenna environment. The separated respiratory signal indeed demonstrated a high correlation with the measurements made by a respiratory strap used currently in clinical settings. PMID:26358241

  18. Preoperative risk assessment for carotid occlusion by transcranial Doppler ultrasound.

    OpenAIRE

    Schneweis, S; Urbach, H; Solymosi, L; Ries, F

    1997-01-01

    OBJECTIVES: An endovascular carotid balloon occlusion test with continuous intracranial monitoring by transcranial Doppler sonography was performed in 55 patients for prediction of tolerance of a required permanent occlusion of the carotid artery. METHODS: Blood flow velocities of the ipsilateral middle cerebral artery during occlusion were recorded and compared with clinical tolerance during an occlusion test as well as with postoperative outcome after an eventual permanent occlusion. To str...

  19. HF Bistatic Ocean Doppler Spectra: Simulation Versus Experimentation

    OpenAIRE

    GROSDIDIER, Samuel; FORGET, Philippe; Barbin, Yves; GUERIN, Charles-Antoine

    2013-01-01

    We simulate the Doppler spectra that can be obtained under experimental conditions from bistatic high-frequency oceanic radar. For this, we combine the bistatic second-order theory with the characteristics of the full radar system, such as antenna patterns, range attenuation, and postprocessing of the received signal. Because of the sharp variation of the bistatic geometry at short range, we show that it is crucial to take these effects into account for the correct interpretation of the first...

  20. Doppler selection of HF radiosignals on long paths

    Science.gov (United States)

    Zalizovskii, A. V.; Galushko, V. G.; Kashcheev, A. S.; Koloskov, A. V.; Yampolski, Yu. M.; Egorov, I. B.; Popov, A. V.

    2007-10-01

    The long-term registration of the Doppler spectra of HF radiosignals has been performed on the Moscow-Akademik Vernadsky Ukrainian Antarctic station path. It has been revealed that the spectra are split when the solar terminator crosses direct and return radio lines. The spectral and energy characteristics of direct and return signals have been calculated within the scope of the asymptotic theory of long-range propagation of decametric radiowaves.

  1. Doppler images of DI Piscium during 2004-2006

    Science.gov (United States)

    Lindborg, M.; Hackman, T.; Mantere, M. J.; Korhonen, H.; Ilyin, I.; Kochukhov, O.; Piskunov, N.

    2014-02-01

    Aims: DI Psc (HD 217352) is a Li-rich, rapidly rotating single K giant. We set out to study the spot configuration and activity level by calculating surface temperature maps of the star. Methods: We apply the Doppler imaging method on high-resolution optical spectroscopy obtained during 2004-2006. Results: In July-August 2004, no clear spot structures were visible, but the spot coverage increased in July 2005, and cool spots emerged, especially at intermediate latitudes. Later on in September 2006, the spot coverage increased and cool spots were visible on both sides of the equator. However, the map of 2006 suffers from bad phase coverage, meaning it is not possible to draw definite conclusions on the spot locations during that season. Conclusions: Compared with earlier Doppler maps of DI Psc and temperature maps obtained for other late-type stars with similar rotation rates, DI Psc seems to be in a low activity state especially during the observing season of July-August 2004. During the 2005 and 2006 observing seasons, the spot activity seen in the spectral line profiles and inferred from Doppler images increases, and the temperature contrast in our last map is more comparable to what was reported in an earlier study. Therefore, it can be concluded that the spot activity level of the star is variable over time. However, the present and previous Doppler images form too short a time series to draw conclusions about a possible activity cycle in DI Psc. Based on observations made with the Nordic Optical Telescope, operated on the island of La Palma jointly by Denmark, Finland, Iceland, Norway, and Sweden in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias.

  2. Meckel's Diverticulum: Doppler Ultrasound and the tree sign

    International Nuclear Information System (INIS)

    Mecker's diverticulum is considered the most frequent congenital anomaly of the gastrointestinal tract, affecting 2% of the popular population. Failure of the obliteration of the viteline duct in the embryogenesis age causes this alteration. Abdominal pain, hemorrhage and obstruction are the clinical expression of this entity. The case of a young 16 years old male, with acute abdomen in whom the ultrasound Doppler color tool made the diagnosis of Meckel's diverticulitis is reported. The tree sign: an ultrasonographic sign is illustrated

  3. Observing Molecular Spinning via the Rotational Doppler Effect

    OpenAIRE

    Korech, Omer; Steinitz, Uri; 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 unidire...

  4. Autonomous beam alignment for coherent Doppler lidar with multielement detectors.

    Science.gov (United States)

    Frehlich, R

    1999-11-20

    Autonomous beam alignment for coherent Doppler lidar requires accurate information about optical misalignment and optical aberrations. A multielement heterodyne detector provides the required information without a loss in overall system performance. The effects of statistical variations from the random backscattered field (speckle field) are determined with computer simulations for both ground-based operation with a fixed calibration target and for space-based operation with random target backscatter. PMID:18324236

  5. Laser Doppler imaging for intraoperative human brain mapping

    OpenAIRE

    Raabe, A; Van De Ville, D.; Leutenegger, M.; Szelényi, A; Hattingen, E; R. Gerlach; Seifert, V.; Hauger, C.; Lopez, A; Leitgeb, R.; Unser, M.; Martin-Williams, E.J.; Lasser, T.

    2009-01-01

    The identification and accurate location of centers of brain activity are vital both in neuro-surgery and brain research. This study aimed to provide a non-invasive, non-contact, accurate, rapid and user-friendly means of producing functional images intraoperatively. To this end a full field Laser Doppler imager was developed and integrated within the surgical microscope and perfusion images of the cortical surface were acquired during awake surgery whilst the patient performed a predet...

  6. Doppler echocardiographic evaluation of the normal human fetal heart.

    OpenAIRE

    Allan, L D; Chita, S K; Al-Ghazali, W; Crawford, D. C.; Tynan, M

    1987-01-01

    Pulsed wave Doppler estimates of blood flow velocity were made across the mitral, tricuspid, aortic, and pulmonary valves in a series of 120 normal fetuses (gestational age 16-36 weeks). In 36 of these the data were obtained in all four sites. The maximum and mean velocities were calculated for each valve and these values were plotted against gestational age. There was little change in these values throughout pregnancy. The orifice dimensions of the valves were measured by cross sectional ech...

  7. Aerosol/Cloud Measurements Using Coherent Wind Doppler Lidars

    Directory of Open Access Journals (Sweden)

    Royer Philippe

    2016-01-01

    LEOSPHERE has recently developed aerosol/cloud detection and characterization on WINDCUBE long range Coherent Wind Doppler Lidars (CWDL. These new features combine wind and backscatter intensity informations (Carrier-to-Noise Ratio CNR in order to detect (aerosol/cloud base and top, PBL height and to characterize atmospheric structures (attenuated backscatter, depolarization ratio. For each aerosol/cloud functionality the method is described, limitations are discussed and examples are given to illustrate the performances.

  8. Wind Measurements with High Energy 2 Micron Coherent Doppler Lidar

    Science.gov (United States)

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

    2004-01-01

    A coherent Doppler lidar based on an injection seeded Ho:Tm:YLF pulsed laser was developed for wind measurements. A transmitted pulse energy over 75 mJ at 5 Hz repetition rate has been demonstrated. Designs are presented on the laser, injection seeding, receiver, and signal processing subsystems. Sample data of atmospheric measurements are presented including a wind profile extending from the atmospheric boundary layer (ABL) to the free troposphere.

  9. Ultrasonic doppler flowmeter-guided occipital nerve block

    OpenAIRE

    Na, Se Hee; Kim, Tae Wan; Oh, Se-Young; Kweon, Tae Dong; Yoon, Kyung Bong; Yoon, Duck Mi

    2010-01-01

    Background Greater occipital nerve block is used in the treatment of headaches and neuralgia in the occipital area. We evaluated the efficacy of ultrasonic doppler flowmeter-guided occipital nerve block in patients experiencing headache in the occipital region in a randomized, prospective, placebo-controlled study. Methods Twenty-six patients, aged 18 to 70, with headache in the occipital region, were included in the study. Patients received a greater occipital nerve block performed either un...

  10. Doppler velocimetry with emphasis on the fetal cerebral circulation

    OpenAIRE

    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 velocimetry in the fetal descending aorta (chapter 2). 2. What happens to the human fetal cerebral circulation relative to normal and raised umbilical placental resistance? To answer this question, the human...

  11. Color Doppler in the Assessment of Uteroplacental Circulation Insufficiency

    OpenAIRE

    Ahmad Soltani Shirazi

    2011-01-01

    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 ins...

  12. 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.

  13. The next generation airborne polarimetric Doppler weather radar

    OpenAIRE

    Vivekanandan, J.; W.-C. Lee; E. Loew; Salazar, J. L.; Grubišić, V.; J. Moore; Tsai, P

    2014-01-01

    Results from airborne field deployments emphasized the need to obtain concurrently high temporal and spatial resolution measurements of 3-D winds and microphysics. A phased array radar on an airborne platform using dual-polarization antenna has the potential for retrieving high resolution, collocated 3-D winds and microphysical measurements. Recently, ground-based phased array radar (PAR) demonstrated the high time resolution estimation of accurate Doppler velocity and reflecti...

  14. The next generation airborne polarimetric Doppler weather radar

    OpenAIRE

    Vivekanandan, J.; W.-C. Lee; E. Loew; Salazar, J. L.; Grubišić, V.; J. Moore; Tsai, P

    2014-01-01

    Results from airborne field deployments emphasized the need to obtain concurrently high temporal and spatial resolution measurements of 3-D winds and microphysics. A phased array radar on an airborne platform using dual-polarization antenna has the potential for retrieving high-resolution, collocated 3-D winds and microphysical measurements. Recently, ground-based phased array radar (PAR) has demonstrated the high time-resolution estimation of accurate Doppler velocity and...

  15. Radiation pressure on a moving body: beyond the Doppler effect

    OpenAIRE

    Horsley, S. A. R.; Artoni, M.; La Rocca, G. C.

    2011-01-01

    The dependence of macroscopic radiation pressure on the velocity of the object being pushed is commonly attributed to the Doppler effect. This need not be the case, and here we highlight velocity-dependent radiation pressure terms that have their origins in the mixing of s and p polarizations brought about by the Lorentz transformation between the lab and the material rest frame, rather than in the corresponding transformation of frequency and wavevector. The theory we develop may be relevant...

  16. Probing Lorentz violation with Doppler-shift experiments

    OpenAIRE

    Lane, Charles D.

    2005-01-01

    We analyze Doppler-effect experiments in terms of a general framework for violations of Lorentz symmetry: the Standard-Model Extension. These experiments are found to be sensitive to heretofore unprobed combinations of Lorentz-violation coefficients associated with protons and electrons. New bounds at the level of $10^{-11}$ and $10^{-8}$ for proton coefficients and $10^{-2}$ for electron coefficients emerge from a recent experiment.

  17. Doppler effect in the oscillator radiation process in the medium

    OpenAIRE

    Gevorgian, Lekdar; Vardanyan, Valeri

    2011-01-01

    The purpose of this paper is to investigate the radiation process of the charged particle passing through an external periodic field in a dispersive medium. In the optical range of spectrum we will consider two cases: first, the source has not eigenfrequency, and second, the source has eigenfrequency. In the first case, when the Cherenkov radiation occurs, the non-zero eigenfrequency produces a paradox for Doppler effect. It is shown that the absence of the eigenfrequency solves the paradox k...

  18. HF doppler sounder measurements of the ionospheric signatures of small scale ULF waves

    Science.gov (United States)

    Baddeley, L. J.; Yeoman, T. K.; Wright, D. M.

    2005-07-01

    An HF Doppler sounder, DOPE (DOppler Pulsation Experiment) with three azimuthally-separated propagation paths is used to provide the first statistical examination of small scale-sized, high m waves where a direct measurement of the azimuthal wavenumber m, is made in the ionosphere. The study presents 27 events, predominantly in the post-noon sector. The majority of events are Pc4 waves with azimuthal m numbers ranging from 100 to 200, representing some of the smallest scale waves ever observed in the ionosphere. 4 Pc5 waves are observed in the post-noon sector. The fact that measurements for the wave azimuthal m number and the wave angular frequency are available allows the drift-bounce resonance condition to be used to hypothesise potential particle populations which could drive the waves through either a drift or drift-bounce resonance interaction mechanism. These results are compared with the statistical study presented by Baddeley et al. (2004) which investigated the statistical likelihood of such driving particle populations occurring in the magnetospheric ring current. The combination of these two studies indicates that any wave which requires a possible drift resonance interaction with particles of energies >60 keV, is statistically unlikely to be generated by such a mechanism. The evidence presented in this paper therefore suggests that in the pre-noon sector the drift-bounce resonance mechanism is statistically more likely implying an anti-symmetric standing wave structure while in the post-noon sector both a drift or drift-bounce resonance interaction is statistically possible, indicating both symmetric and anti-symmetric standing mode structures. A case study is also presented investigating simultaneous observations of a ULF wave in ground magnetometer and DOPE data. The event is in the lower m range of the statistical study and displays giant pulsation (Pg) characteristics. Keywords. Ionosphere (Ionosphere-magnetosphere interactions) Magnetospheric

  19. 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.

  20. Estimating a modified Grubb's exponent in healthy human brains with near infrared spectroscopy and transcranial Doppler

    International Nuclear Information System (INIS)

    The relationship between cerebral blood volume (CBV) and flow (CBF) has been widely studied. One of the most significant early studies was by Grubb et al (1974 Stroke 5 630–9), who conducted hypercapnia studies in primates with positron emission tomography (PET) and empirically found CBV = 0.8 CBF0.38. The exponent used here has since been known as the Grubb's exponent. In this paper, we define a similar exponent known as the modified Grubb's exponent, G', which is based on CBV and cerebral blood flow velocity (CBFV) estimated by near infrared spectroscopy (NIRS) and transcranial Doppler respectively, i.e. G' = log(CBV/CBV0)/log(CBFV/CBFV0), where CBV0 and CBFV0 are baseline values. The aim of this study was to estimate the nominal value of the modified Grubb's exponent in healthy human brains. We conducted hypercapnia and hypocapnia studies on 14 healthy adult subjects. The correlation coefficient between log(CBV/CBV0) and log(CBFV/CBFV0) is 0.71 (p < 0.0001). We found a modified Grubb's exponent of 0.13 (the 95% confidence bounds are 0.10 and 0.17) which is expectedly lower than the conventional Grubb's exponents estimated by other techniques. The modified Grubb's exponent is a simple measure to quantify the hemodynamics between local CBV and global CBFV in the brain and as such may provide insight on brain physiology. Both NIRS and transcranial Doppler techniques are non-invasive and portable, facilitating future studies in other population groups such as brain-injured patients

  1. Laser spectroscopy of multi-level doppler broadened atomic system

    International Nuclear Information System (INIS)

    Doppler broadened atomic vapor system can be easily prepared for spectroscopy study than an atomic beam system can be. Vapor cell and hollow cathode discharge lamps are widely used in the experiment. The possibility for observing the trapped state in a Doppler broadened Λ system was examined and confirmed by our early experiment where counter-propagating laser beams are used. For the measurement of the hyperfine structure constants of high-lying levels of heavy elements, we compared the co-propagating and counter-propagating beams in a Doppler broadened ladder systems. It was shown that the counter-propagating beams give a stronger and narrower signal than that from the co-propagating beams. Our treatment also considers the power broadening of the transition. For some photo-ionization experiments, it is necessary to pump two thermally populated levels simultaneously to the higher level and then to the auto-ionizing levels. A technique is proposed to avoid the trapped state and to increase the ionization efficiency.

  2. 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...

  3. Doppler Monitoring of five K2 Transiting Planetary Systems

    DEFF Research Database (Denmark)

    Dai, Fei; Winn, Joshua N.; 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. 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.

  5. On the Fly Doppler Broadening Using Multipole Representation

    International Nuclear Information System (INIS)

    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

  6. Modelling nonstationary Doppler noise in exoplanetary radial velocity data

    Science.gov (United States)

    Baluev, Roman V.

    2015-08-01

    We construct a new class of analytic nonstationary noise models for exoplanetary Doppler data. The observable correlated noise is represented as a convolution of a parent activity process with a given memory function. The model honours the casuality principle, meaning that only past values of the activity may affect the observable value. This model does not approximate detailedly any real stellar activity phenomena, but it becomes mathematically simple, simultaneously satisfying the basic natural principles of physical sensibility and self-consistency.Additionally, we develop a new type of periodograms that can be used to detect periodic modulations in the Doppler noise characteristics, rather than in the observed radial velocity curve itself. We present first results of applying this technique to public Doppler time series available for a set of planet-hosting stars.This work was supported by the Russian Foundation for Basic Research (project No. 14-02-92615 KO_a), the UK Royal Society International Exchange grant IE140055, by the President of Russia grant for young scientists (No. MK-733.2014.2), by the programme of the Presidium of Russian Academy of Sciences P21, and by the Saint Petersburg State University research grant 6.37.341.2015.

  7. Doppler lidar sampling strategies and accuracies: Regional scale

    Science.gov (United States)

    Emmitt, G. D.

    1985-01-01

    It has been proposed that a Doppler lidar be placed in a polar orbit and scanned to provide estimates of lower tropospheric winds twice per day and with a spatial resolution of 300 km. Initial feasibility studies conducted primarily by NOAA and NASA presented an optimistic outlook for a space based lidar. The technology appeared within reach and initial computer simulations suggested that acceptable accuracies could be obtained. Those early studies exposed, however, several potential problem areas which included: (1) the algorithms for computing the wind vectors did not perform well when there were coherent gradients in the wind fields; and (2) the lifetime and power requirements of the lidar put severe restrictions on the pulse repetition frequency (PRF). These two basic problems are currently being addressed by a Doppler lidar simulation study focussed upon three primary objectives: (1) to develop optimum scan parameters and shot patterns for a satellite-based Doppler lidar; (2) to develop robust algorithms for computing wind vectors from lidar returns; and (3) to evaluate the impact of coherent mesoscale structures (wind gradients, clouds, aerosols) on up-scale wind estimates. An overview is provided of the simulation efforts with particular emphasis upon rationale and methodology. Since this research is currently underway, any results shown are meant only as evidence of progress.

  8. Doppler radar wind field retrieval over the Po Valley

    Directory of Open Access Journals (Sweden)

    Y. K. Goh

    2006-01-01

    Full Text Available Although methods of using multiple Doppler radars to study wind fields have long been proposed, and many research studies have been made, very few operational radar operators adopt methods which require the use of specific scanning strategies to allow the extraction of wind information. Here we report a collaborative study on dual-Doppler radars based on two Doppler radars in the Po valley, Italy. Unusually, the radars are only about 90 km apart, though operated by the same authority. The wind field syntheses are carried out on a 30 km by 30 km region where the two radars have overlapping scan coverage. An iterative method based on the linear wind model and the equation of mass continuity is used to construct the wind fields. The methodology has been validated by two different methods. The first method is to reconstruct the radial wind observed by each radar, and the second method is calculating and comparing the along-track component with that derived from the observations. Both two comparisons show good agreement with the original data.

  9. Estimation of Carotid Artery Pulse Wave Velocity by Doppler Ultrasonography

    Directory of Open Access Journals (Sweden)

    Mehdi Maerefat

    2009-06-01

    Full Text Available Background: Pulse wave velocity (PWV is widely used for estimating the stiffness of an artery. Various invasive and non-invasive methods have been developed to determine PWV over the years. In the present research, the non-invasive estimation of the PWV of large arteries was used as an index for arterial stiffness. Methods: A dynamic model based on the Navier-Stokes equations coupled to elasticity equations was introduced for the PWV in arteries with elastic walls. This system of equations was completed by clinical information obtained from the Doppler ultrasound images of the carotid artery of 40 healthy male volunteers. For this purpose, the Doppler ultrasound images were recorded and saved in a computer; and subsequently center-line blood velocity, arterial wall thickness, and arterial radius were measured by offline processing. Results: The results from the analytic solution of the completed equations showed that the mean value of PWV for the group of healthy volunteers was 2.35 m/s when the mean arterial radius was used as the neutral radius and 5.00 m/s when the end-diastole radius was used as the neutral radius. It is noteworthy that the latter value closely complies with that reported by other researchers. Conclusion: By applying this method, a non-invasive clinical and local evaluation of the common carotid artery stiffness via a Doppler ultrasound measurement will be possible.

  10. Echobiometrics kidney and renal artery triplex doppler of canine fetuses

    Directory of Open Access Journals (Sweden)

    M.A.R. Feliciano

    2014-04-01

    Full Text Available The aim of this study was to assess the sogographic parameters and biometry of canine fetal kidneys using the B mode, and to determinate the vascular index of the fetal renal arteries using the Doppler Triplex. Twenty four Shi-tzu and Pug, weighting between 4 and 10kg, aging between 4 and 6 years old were evaluated. The B mode, the fetal renal echobiometry and regularity of the renal surface, echotexture and cortex:medular ratio were evaluated during the 5th, 6th, 7th and 8th weeks of pregnancy. At the same time point of the B mode evaluation, the Doppler Triplex was carried out to assess the sistolic peak velocity (SPV, end diastolic velocity (EDV, vascular resistive (RI and pulsatility index (PI. B mode revealed no fetal renal abnormalities and echobiometry showed important measurements during fetal development (P0.05. B mode and Doppler Triplex were important tools for the assessment of fetal renal development, using echobiometry and renal arterial index in canie fetuses.

  11. Color Doppler in the Assessment of Uteroplacental Circulation Insufficiency

    Directory of Open Access Journals (Sweden)

    Ahmad Soltani Shirazi

    2011-05-01

    Full Text Available Color Doppler ultrasound in diagnosis of uteroplacental"nor fetal placental vascular insufficiency is based on"nthe theory that many of these insufficiencies are"ndue to small vessel disease in uteroplacental or fetal"nplacental vasculature which ultimately results in fetal"nintrauterine growth retardation, increase in prenatal"nmortality and morbidity and fetal neurological"ndevelopment."nIn a prospective study on patients who were suspected"nfor developing uteroplacental insufficiency, color"nDoppler ultrasound was done and the results were"ncompared with the neonatal weight which was"nmeasured just after delivery."nAbstracts"nS66 Iran J Radiol 2011, 8 (Supp.1"nDirect significant correlation was showed to be present"nbetween prepartum vascular changes detected in"nDoppler ultrasound and the prognosis of IUGR."nThree vessel types were assessed in this study: 1-"numbilical -middle cerebral arteries 2-uterine arteries"n3-venous system (umblical vein, ductus venosus, IVC,"nwhich are used to assess the compensation process in"nfetal circulation.

  12. Multi-beam Laser Doppler Vibrometer with fiber sensing head

    Science.gov (United States)

    Phua, P. B.; Fu, Y.; Guo, M.; Liu, H.

    2012-06-01

    Laser Doppler vibrometry (LDV) is a well known technique to measure the motions, vibrations and mode shapes of structures and machine components. Photodetector-based LDV can only offer a point-wise measurement. However, it is possible to scan the laser beam to build up a vibrometric image. These scanning laser Doppler vibrometers (SLDV) assume that the measurement conditions remain invariant while multiple and identical, sequential measurements are performed. This assumption makes SLDVs impractical to do measurement on transient events. In this paper, we introduce a new method of generating multiple laser beams with different frequency shifts. The laser beams are projected on different points, and the reflected beams interfere with a common reference beam. The cross-talk among object beams can be bypassed with a proper selection of frequency shifts. A simultaneous vibration measurement on multiple points is realized using a single photodetector. Based on the proposed spatial-encoding technology, a self-synchronized prototype of fiber-based multipoint laser Doppler vibrometer at 1550nm wavelength is developed. An addition red pilot laser is used for aiming purpose. It has the flexibility to measure the vibration of different points on various surfaces. The prototype is used to measure the vibration of different points on a cantilever beam and a plate. The measured results match well with simulation results using finite element method (FEM).

  13. 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;

  14. [Minimally invasive hemodynamic monitoring with esophageal echoDoppler].

    Science.gov (United States)

    Monge, M I; Estella, A; Díaz, J C; Gil, A

    2008-01-01

    Hemodynamic monitoring is a key element in the care of the critical patients, providing an unquestionable aid in the attendance to diagnosis and the choice of the adequate treatment. Minimally invasive devices have been emerging over the past few years as an effective alternative to classic monitoring tools. The esophageal echoDoppler is among these. It makes it possible to obtain continuous and minimally invasive monitoring of the cardiac output in addition to other useful parameters by measuring the blood flow rate and the diameter of the thoracic descending aorta, which provides a sufficiently extensive view of the hemodynamic state of the patient and facilitates early detection of the changes produced by a sudden clinical derangement. Although several studies have demonstrated the usefulness of the esophageal Doppler in the surgical scene, there is scarce and dispersed evidence in the literature on its benefits in critical patients. Nevertheless, its advantages make it an attractive element to take into account within the diagnostic arsenal in the intensive care. The purpose of the following article is to describe how it works, its degree of validation with other monitoring methods and the role of esophageal echoDoppler as a minimally invasive monitoring tool for measuring cardiac output in the daily clinical practice, contributing with our own experience in the critical patient. PMID:18221711

  15. Novel measure for the calibration of laser Doppler flowmetry devices

    Science.gov (United States)

    Dunaev, Andrey V.; Zherebtsov, Evgeny A.; Rogatkin, Dmitrii A.; Stewart, Neil A.; Sokolovski, Sergei G.; Rafailov, Edik U.

    2014-03-01

    The metrological basis for optical non-invasive diagnostic devices is an unresolved issue. A major challenge for laser Doppler flowmetry (LDF) is the need to compare the outputs from individual devices and various manufacturers to identify variations useful in clinical diagnostics. The most common methods for instrument calibration are simulants or phantoms composed of colloids of light-scattering particles which simulate the motion of red blood cells based on Brownian motion. However, such systems have limited accuracy or stability and cannot calibrate for the known rhythmic components of perfusion (0.0095-1.6 Hz). To solve this problem, we propose the design of a novel technique based on the simulation of moving particles using an electromechanical transducer, in which a precision piezoelectric actuator is used (e.g., P-602.8SL with maximum movement less than 1 mm). In this system, Doppler shift is generated in the layered structure of different solid materials with different optical light diffusing properties. This comprises a fixed, light transparent upper plane-parallel plate and an oscillating fluoroplastic (PTFE) disk. Preliminary studies on this experimental setup using the LDF-channel of a "LAKK-M" system demonstrated the detection of the linear portion (0-10 Hz with a maximum signal corresponding to Doppler shift of about 20 kHz) of the LDF-signal from the oscillating frequency of the moving layer. The results suggest the possibility of applying this technique for the calibration of LDF devices.

  16. Considerations pertinent to the Doppler effect for space reactors

    International Nuclear Information System (INIS)

    Because of the potential importance of the Doppler effect to the safety considerations of compact fast spectrum reactors for space applications, extensive investigations have been carried out. The purpose of this paper is two-fold. First, the magnitude of the Doppler reactivity of such reactors will be estimated. Secondly, some relevant questions concerning the fundamental nature of the problems will be addressed. In the present study, a generic space reactor design having features of current designs is examined. In R-Z geometry, the reactor consists of 3 core regions which are made of UN with various enrichments mixed in with a W/Re matrix and coolant channels filled with 7Li and surrounded by Mo-vessel and beryllium oxide reflector along with external control drums made of B4C in the radial direction and accompanied by axial regions. The axial region above the core contains BeO with W/Re structure. The enrichment increases as a function of radius to provide an approximately constant power distribution in the core regions. Hence, the temperature distribution is also expected to be approximately constant in various core regions. The Doppler reactivities will be given for various radial and axial regions

  17. Uranium dioxide crystalline binding effect on Doppler broadening

    International Nuclear Information System (INIS)

    When the crystalline bindings are weak, the Doppler broadening of resonances can be obtained with the same formula as for the free gas. But the physical temperature must be replaced by an effective temperature which is higher. The effective temperature depends on the physical temperature and on a parameter theta which is called the Debye temperature. For uranium dioxide, the value of theta seems top be high and not well known. This fact can infer important consequences in reactor physics. For a light water reactor, the reactivity effect of a theta value increasing from 0 K to 620 K can reach -215.10-5 at room temperature and affect the temperature coefficient of the reactor for 15%. For knowing the Debye temperature with a good accuracy we deduced a theta value from Doppler experiments which were performed in a critical facility. We obtained a value of 615 K which is in good agreement with theoretical computations using several crystal vibration models. This high value imposes to take into account the crystalline bindings in Doppler broadening calculations

  18. Positron trapping defects in Pt, Al, and Al-0.1-at.% Mg following d-Be neutron irradiation

    International Nuclear Information System (INIS)

    Specimens of Al, Al--Mg, and Pt were irradiated using the Davis d-Be neutron source which has a spectrum peaking at approx. 15 MeV. Lifetime and Doppler-broadening measurements have been made on these specimens for three fluences in the as-irradiated state and for subsequent anneals to 5000C. Saturation of positron trapping at the higher fluences was observed in the Pt specimen, with the average trap size increasing after annealing through stage III (vacancy migration). Surviving traps after 5000C are presumed to be voids. The Al and Al--Mg showed some trapping introduced by the room-temperature irradiaion, but complete recovery is seen at 5000C. These trapping sites are assumed to be small vacancy clusters or small dislocation loops. Some loops of very low concentration were observed near grain boundaries in the as-irradiated specimen of Al by TEM

  19. Turbulence as observed by concurrent measurements made at NSSL using weather radar, Doppler radar, Doppler lidar and aircraft

    Science.gov (United States)

    Lee, Jean T.

    1987-01-01

    As air traffic increases and aircraft capability increases in range and operating altitude, the exposure to weather hazards increases. Turbulence and wind shears are two of the most important of these hazards that must be taken into account if safe flight operations are to be accomplished. Beginning in the early 1960's, Project Rough Rider began thunderstorm investigations. Past and present efforts at the National Severe Storm Laboratory (NSSL) to measure these flight safety hazards and to describe the use of Doppler radar to detect and qualify these hazards are summarized. In particular, the evolution of the Doppler-measured radial velocity spectrum width and its applicability to the problem of safe flight is presented.

  20. Accuracy of doppler ultrasound in diagnosis of endometrial carcinoma

    International Nuclear Information System (INIS)

    Objective: To determine the accuracy of Doppler ultrasound in the diagnosis of endometrial carcinoma in patients presenting with post-menopausal bleeding while taking histopathological findings as the gold standard. Methods: The cross-sectional study was done at the Department of Radiology, Bahawal Victoria Hospital, Bahawalpur, from April 1 to September 30, 2009, and comprised 128 patients above 50 years of age having history of post-menopausal bleeding and who were referred to the department. Name, age and hospital registration number were recorded on a proforma. Doppler ultrasound was performed and endometrial thickness and uterine artery resistive index were recorded on transabdominal ultrasonography. Patients with endometrial thickness of more than 5mm and uterine artery resistive index of less than 0.7 were considered to be having endometrial carcinoma. Histopathology findings were also recorded using the hospital registration number of the patient. The findings of Doppler ultrasound scan were validated with the findings of histopathology. Results: Of the 128 patients, 48 (37.5%) were between the ages of 51 and 55 years; 46 (35.93%) were in the 56-60 age group; and 34 (26.57%) were over 65 years. On the basis of Doppler ultrasound findings, 106 (82.8%) patients were diagnosed as having endometrial carcinoma, while 22 (17.19%) were declared negative. Ultrasonography results were compared with histopathology findings. The percentages of true positive, true negative, false positive and false negative were calculated. There were 103 (80.47%) true positive; 12 (9.37%) false positive; 10 (7.81%) true negative; and 3 (2.35%) false negative. Specificity, sensitivity, positive predictive value and negative predictive value were found to be 97.16%, 76%, 89.56% and 76.92% respectively. Conclusion: The use of Doppler ultrasonography in non-invasive diagnosis of endometrial carcinoma in patients presenting with post-menopausal bleeding was quite useful with good

  1. 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.

  2. Shigeo Satomura: 60 years of Doppler ultrasound in medicine.

    Science.gov (United States)

    Coman, Ioan M; Popescu, Bogdan A

    2015-01-01

    This year we celebrate 60 years since Shigeo Satomura published the first measurements of the Doppler shift of ultrasonic signals from a beating heart. He demonstrated that Doppler signals can be retrieved from heart movements when insonated with 3 MHz ultrasonic waves. Later, togheter with Ziro Kaneko, he constructed the first Doppler flowmeter to measure the blood flow velocities in peripheral and extracranial brain-supplying vessels using ultrasounds. They proved that ultrasonic Doppler signals from arteries and veins can be recorded from the surface of the skin and pioneered transcutaneous flow analysis in systole and diastole in both normal and diseased blood vessels. These were the first medical applications of Doppler sonography and impressive technologic innovations have been continuing ever since. Over time, Doppler techniques became a key player in diagnostic ultrasound for hemodynamic assessment, replacing cardiac catheterization in many clinical settings. PMID:26699126

  3. Preoperative evaluation of ovarian masses with color Doppler and its correlation with pathological finding

    Directory of Open Access Journals (Sweden)

    Isha Khurana

    2016-07-01

    Conclusions: Color Doppler is a good non-invasive modality to differentiate benign from malignant lesions. Vascularity is most sensitive and RI is most specific. Thus, color Doppler and spectral Doppler tremendously increased the reliability in diagnosing a malignant ovarian tumor. Color Doppler served as an important tool to rule out malignancy in solid tumors if they failed to show any intra-tumoral vascularity. B-Mode USG in combination with color Doppler and spectral Doppler is proposed as the first and foremost diagnostic modality in patients with ovarian tumor, so as to establish the definite diagnosis of malignancy early in the course of the disease. [Int J Reprod Contracept Obstet Gynecol 2016; 5(7.000: 2084-2092

  4. Echocardiographic reference ranges for normal cardiac Doppler data: results from the NORRE Study.

    OpenAIRE

    Caballero, Luis; kou, Seisyou; DULGHERu; Gonjilashvili, Natalia; Athanassopoulos, George D.; Barone, Daniele; Baroni, Monica; Cardim, Nuno; Gomez De Diego, Jose Juan; Oliva, Maria Jose; Hagendorff, Andreas; Hristova, Krasimira; Lopez, Teresa; Magne, Julien; Martinez, Christophe

    2015-01-01

    AIMS: Reference values for Doppler parameters according to age and gender are recommended for the assessment of heart physiology, specifically for left ventricular (LV) diastolic function. In this study, we report normal reference ranges for Doppler parameters obtained in a large group of healthy volunteers. Echocardiographic data were acquired using state-of-the-art cardiac ultrasound equipment following Doppler acquisition and measurement protocols approved by the European Association of Ca...

  5. A review of Doppler Ultrasound Quality Assurance Protocols and Test Devices

    OpenAIRE

    Browne, Jacinta

    2014-01-01

    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...

  6. 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.

  7. Study on Zero-Doppler Centroid Control for GEO SAR Ground Observation

    OpenAIRE

    2014-01-01

    In geosynchronous Earth orbit SAR (GEO SAR), Doppler centroid compensation is a key step for imaging process, which could be performed by the attitude steering of a satellite platform. However, this zero-Doppler centroid control method does not work well when the look angle of radar is out of an expected range. This paper primarily analyzes the Doppler properties of GEO SAR in the Earth rectangular coordinate. Then, according to the actual conditions of the GEO SAR ground observation, the eff...

  8. 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

  9. Velocity Variation Assessment of Red Blood Cell Aggregation with Spectral Domain Doppler Optical Coherence Tomography

    OpenAIRE

    Xu, Xiangqun; Yu, Lingfeng; Chen, Zhongping

    2010-01-01

    We propose spectral domain Doppler optical coherence tomography (SD-D-OCT) to qualitatively measure red blood cell aggregation. Variance/standard deviation (SD) of the Doppler frequency spectrum in Doppler variance imaging of flowing blood under shearing conditions was developed as a new aggregation index. In in vitro microchannel-flow experiments, porcine blood at various hematocrits with aggregation characteristics induced by dextran 500 or at the presence of plasma fibrinogen was measured ...

  10. Maximum Likelihood Estimator For Doppler Parameter And Cramer Rao Bound In ZP-OFDM UWA Channel

    OpenAIRE

    Lyonnet, Bastien; Siclet, Cyrille; Brossier, Jean-Marc

    2010-01-01

    A Doppler estimation system using a maximum likelihood criterion is presented in the context of underwater acoustic communications between moving transmitter/receiver. We simulate the method for the estimation of the Doppler effect induced by an underwater acoustic channel (UWA) using Zero Padded-Orthogonal Frequency Division Multiplexing (ZP-OFDM). Among the wide range of physical processes that impact OFDM communications through the underwater environment, Doppler effect is an important cau...

  11. Evaluation of a combined reflectance photoplethysmography and laser Doppler flowmetry surface probe

    OpenAIRE

    Z Abdollahi; Phillips, J. P.; Kyriacou, P. A.

    2013-01-01

    This study presents evaluation of a system combining laser Doppler flowmetry and photoplethysmography (PPG) in a single probe for the simultaneous measurement of perfusion and blood flow in the finger. A cuff sphygmomanometer was used to partially occlude the arteries supplying the hand to investigate the effect of low pressure on photoplethysmographic and laser Doppler signals and also on calculated arterial blood oxygen saturation values (SpO2). Red and infrared PPG and Doppler signals were...

  12. Post-Newtonian Theory for Precision Doppler Measurements of Binary Star Orbits

    OpenAIRE

    Kopeikin, S. M.; Ozernoy, L. M.

    1998-01-01

    The determination of velocities of stars from precise Doppler measurements is described here using relativistic theory of astronomical reference frames so as to determine the Keplerian and post-Keplerian parameters of binary systems. We apply successive Lorentz transformations and the relativistic equation of light propagation to establish the exact treatment of Doppler effect in binary systems both in special and general relativity theories. As a result, the Doppler shift is a sum of (1) lin...

  13. Doppler-Free Spectroscopy of Weak Transitions: An Analytical Model Applied to Formaldehyde

    CERN Document Server

    Zeppenfeld, M; Pinkse, P W H; Rempe, G

    2007-01-01

    Experimental observation of Doppler-free signals for weak transitions can be greatly facilitated by an estimate for the expected amplitude of the signal. We derive an analytical model which allows the Doppler-free signal amplitude to be estimated for small Doppler-free signals. Application of this model to formaldehyde allows the amplitude of experimentally observed Doppler-free signals to be reproduced to within a factor of two and the relative amplitude of different lines to be reproduced to within a few percent.

  14. Assessing the quality of ionogram interpretation using the HF Doppler technique

    OpenAIRE

    D. Buresova; V. Krasnov; Drobzheva, Ya.; J. Lastovicka; Chum, J.; Hruska, F.

    2007-01-01

    The first joint common volume measurements by the Digisonde Portable Sounder (DPS-4) and a new Doppler type system has been run at the Pruhonice ionospheric observatory (49.99° N, 14.54° E) since January 2004. The measurement of the Doppler shift is carried out continuously on a frequency of 3.6 MHz, thus the radio wave is reflected predominantly from the ionospheric F layer. To compare digisonde measurements with the Doppler data, a phase path was calculated from both Doppler...

  15. 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.    

  16. Non-Doppler Redshift and Dark Matter in the Coma Cluster

    OpenAIRE

    Zheng, Yi-Jia

    2013-01-01

    In 1929 Zwicky proposed a tired light theory to interpret the Hubble law (Hubble 1929). The key of the tired light theory is to interpret the observed redshift of galaxy as the non-Doppler effect. But the derivation of the dark matter in the Coma cluster proposed by Zwicky in 1933 was based on the interpretation that redshifts of galaxies were the Doppler effect, and the non-Doppler effect was not considered at all. However, if there is a reasonable non-Doppler effect and the great majority o...

  17. HF Doppler radar observations of low-latitude spread F

    Science.gov (United States)

    Reddi, C. R.; Sarma, M. S. S. R. K. N.; Niranjan, K.

    2009-06-01

    HF (5.5 MHz) Doppler radar observations of nonspread F and spread F echoes over Visakhapatnam (17.7°N, 83.3°E; dip 20°) are presented. The echoes appearing suddenly and nearly simultaneously in 16 successive range bins at 7.5 km intervals in association with spread F have been investigated. Two to five episodes of spread F activity were found to appear at intervals of 1-2 hours during individual nights. At the time of onset of spread F conditions, the Doppler velocity for each range bin changed rapidly from a negative maximum to a positive maximum followed by a gradual decrease to a steady ±10-15 m/s or to a large negative velocity and then again to a large positive. At the time of small constant velocity or velocity change from negative to positive, the spread F echoes were weak or even below the detection level of the radar. This disappearance in the higher ranges causes the decrease in range extent of spread F echoes. The positive and negative maximum velocities of spread F were in the range of +70 to -60 m/s. The maximum upward and downward velocity is not the same in all events of spread F activity. The width of the Doppler velocity spectrum for spread F echoes was found to vary with velocity. For zero velocity the width was a minimum of 50 m/s in contrast to 25 m/s for nonspread F events. These features were consistently observed for all spread F incidences. The observed results are compared with already reported HF/VHF observations and are discussed in the light of equatorial plasma dynamics during the growth phase of Rayleigh Taylor instability leading the incidence of spread F.

  18. Pulmonary Impedance and Pulmonary Doppler Trace in the Perioperative Period.

    Science.gov (United States)

    Tousignant, Claude; Van Orman, Jordan R

    2015-09-01

    Pulmonary hypertension and associated vascular changes may frequently accompany left-sided heart disease in the adult cardiac surgical population. Perioperative assessment of right ventricular function using echocardiography is well established. In general, understanding the constraints upon which the right ventricle must work is mostly limited to invasive monitoring consisting of pulmonary artery pressures, cardiac output, and pulmonary vascular resistance. The latter 2 measurements assume constant (mean) flows and pressures. The systolic and diastolic pressures offer a limited understanding of the pulsatile constraints, which may become significant in disease. In normal physiology, pressure and flow waves display near-similar contours. When left atrial pressure and pulmonary vascular resistance are increased, changes in pulmonary arterial compliance will result in elevated impedance to right ventricular ejection. Pressure reflections, the result of strong reflectors, return more quickly in a noncompliant system. They augment pulmonary artery pressure causing a premature reduction in flow. As a result, pressure and flow waves will now be dissimilar. The impact of vascular changes on right ventricular ejection can be assessed using pulmonary artery Doppler spectral imaging. The normal flow velocity profile is rounded at its peak. Earlier peaks and premature reductions in flow will make it appear more triangular. In some cases, the flow pattern may appear notched. The measurement of acceleration time, the time from onset to peak flow velocity is an indicator of constraint to ejection; shortened times have been associated with increased pulmonary vascular resistance and pressure. Understanding the changes in the pulmonary arterial system in disease and the physics of the hemodynamic alterations are essential in interpreting pulmonary artery Doppler data. Analyzing pulmonary artery Doppler flow signals may assist in the evaluation of right ventricular function in

  19. Colour doppler ultrasound assessment of the normal neonatal hip

    International Nuclear Information System (INIS)

    To determine the morphology and hemodynamic characteristics of the arterial vessels of the proximal femur according to specific anatomic regions in asymptomatic neonates in 2 pediatric-based health care institutions. Forty-three neonates (29 female, 14 male; age range, 2 d-3 mo; median age, 3 d) were enrolled in the study. Thirty-two (37%) of 86 hips were classified as Graf type IIA joints (mean alpha angle, 56.0o ± 2.7o), and 54 (63%) were classified as type I joints (mean alpha angle, 65.0o ± 4.6o). Colour and spectral Doppler imaging identified vessels running along the acetabular labrum, epiphyseal vessels, and femoral neck. We showed 4 different patterns of vascularity of the hips: radial, parallel, mixed radial-parallel, and indeterminate, however, they were not related to the hip maturity (P = .3, coronal plane; P = .62, transverse plane) or to the amount of colour pixels identified in each region (P = .35). The mean number of pixels in the ligamentum teres region was significantly higher than that in other regions of interest (P =.03). Except for the acetabular labrum arteries, Doppler spectrum waveforms of proximal femur arteries presented with low resistivity. There was a tendency towards females' acetabular arteries presenting with lower peak systolic velocities than males' acetabular arteries (P =.06). Colour Doppler spectrum waveforms and intensity of vascularity in normal neonatal hips differ according to the anatomic region under evaluation. This observation deserves further investigation on its role on the physiopathogenesis of neonatal hip disorders. (author)

  20. Colour doppler ultrasound assessment of the normal neonatal hip

    Energy Technology Data Exchange (ETDEWEB)

    Ortiz-Neira, C.L. [Dept. of Diagnostic Imaging, Alberta Children' s Hospital, Calgary, Alberta (Canada)], E-mail: clara.ortiz@calgaryhealthregion.ca; Laffan, E.; Daneman, A. [Dept. of Diagnostic Imaging, The Hospital for Sick Children, Toronto, Ontario (Canada); Fong, K. [Dept. of Diagnostic Imaging, Mount Sinai Hospital, Toronto, Ontario (Canada); Roposch, A. [Dept. of Orthopedic Surgery, The Hospital for Sick Children, Toronto, Ontario (Canada); Great Ormond Street Hospital, Inst. of Child Health, Univ. College London, London (United Kingdom)

    2009-04-15

    To determine the morphology and hemodynamic characteristics of the arterial vessels of the proximal femur according to specific anatomic regions in asymptomatic neonates in 2 pediatric-based health care institutions. Forty-three neonates (29 female, 14 male; age range, 2 d-3 mo; median age, 3 d) were enrolled in the study. Thirty-two (37%) of 86 hips were classified as Graf type IIA joints (mean alpha angle, 56.0{sup o} {+-} 2.7{sup o}), and 54 (63%) were classified as type I joints (mean alpha angle, 65.0{sup o} {+-} 4.6{sup o}). Colour and spectral Doppler imaging identified vessels running along the acetabular labrum, epiphyseal vessels, and femoral neck. We showed 4 different patterns of vascularity of the hips: radial, parallel, mixed radial-parallel, and indeterminate, however, they were not related to the hip maturity (P = .3, coronal plane; P = .62, transverse plane) or to the amount of colour pixels identified in each region (P = .35). The mean number of pixels in the ligamentum teres region was significantly higher than that in other regions of interest (P =.03). Except for the acetabular labrum arteries, Doppler spectrum waveforms of proximal femur arteries presented with low resistivity. There was a tendency towards females' acetabular arteries presenting with lower peak systolic velocities than males' acetabular arteries (P =.06). Colour Doppler spectrum waveforms and intensity of vascularity in normal neonatal hips differ according to the anatomic region under evaluation. This observation deserves further investigation on its role on the physiopathogenesis of neonatal hip disorders. (author)

  1. 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

  2. Assessment of resistive index in acute epididymitis on doppler sonography

    International Nuclear Information System (INIS)

    This study was aimed to review findings of gray-scale ultrasonography and to assess the diagnostic value of the resistive index (RI) in patients with acute epididymitis by comparing with that in normal volunteers. Gray-scale ultrasonogram was reviewed in nine patients with acute epididymitis for echogenicity, size and reactive hydrocele. Normal values of resistive index (RI) were obtained in 20 epididymides from 10 volunteers (aged 20-28, mean 23.7). Nine patients of epididymitis (aged 18-67, mean 37.2) were examinated with color Doppler sonography and RI was measured at 11 sites on epididymal arteries. For the prediction of acute epididymitis, accuracy, sensitivity and specificity were calculated at the cut-off value of RI in 0.65 and 0.70. Gray-scale ultrasonography showed echogenicity that was variable among the 9 cases (hyperechoic 2 cases, isoechoic 2, hypoechoic 5), enlargement of epididymis in 8, and reactive hydrocele in 8 cases. Normal volunteers displayed color Doppler signals in 14 out of 20. The range of RI in normal volunteers were between 0.64 and 1.00 (mean, 0.79 ± SD 0.10). In patients with acute epididymitis, color Doppler signals were detected in all patients. The range of RI in epididymitis were 0.40-0.68 (mean, 0.56 ± SD 0.10). At cut-off RI value of 0.65, accuracy was 88%, sensitivity 81.1%, and specificity 92.7%. At cut-off value of 0.70 accuracy was 92%, sensitivity 100%, and specificity 85.7%. In addition to the findings of gray-scale ultrasonography, resistive index and color flow changes are valuable in diagnosing acute epididymitis

  3. Assessment of resistive index in acute epididymitis on doppler sonography

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Seung Mun; Cho, Kyoung Sik; Choi, Hyo Kyeong; Lee, Moon Gyu; Auh, Yong Ho; Kim, Chung Soo [Asan Medical Center University of Ulsan, College of Medicine, Seoul (Korea, Republic of)

    1995-06-15

    This study was aimed to review findings of gray-scale ultrasonography and to assess the diagnostic value of the resistive index (RI) in patients with acute epididymitis by comparing with that in normal volunteers. Gray-scale ultrasonogram was reviewed in nine patients with acute epididymitis for echogenicity, size and reactive hydrocele. Normal values of resistive index (RI) were obtained in 20 epididymides from 10 volunteers (aged 20-28, mean 23.7). Nine patients of epididymitis (aged 18-67, mean 37.2) were examinated with color Doppler sonography and RI was measured at 11 sites on epididymal arteries. For the prediction of acute epididymitis, accuracy, sensitivity and specificity were calculated at the cut-off value of RI in 0.65 and 0.70. Gray-scale ultrasonography showed echogenicity that was variable among the 9 cases (hyperechoic 2 cases, isoechoic 2, hypoechoic 5), enlargement of epididymis in 8, and reactive hydrocele in 8 cases. Normal volunteers displayed color Doppler signals in 14 out of 20. The range of RI in normal volunteers were between 0.64 and 1.00 (mean, 0.79 {+-} SD 0.10). In patients with acute epididymitis, color Doppler signals were detected in all patients. The range of RI in epididymitis were 0.40-0.68 (mean, 0.56 {+-} SD 0.10). At cut-off RI value of 0.65, accuracy was 88%, sensitivity 81.1%, and specificity 92.7%. At cut-off value of 0.70 accuracy was 92%, sensitivity 100%, and specificity 85.7%. In addition to the findings of gray-scale ultrasonography, resistive index and color flow changes are valuable in diagnosing acute epididymitis.

  4. 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.

  5. 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

  6. 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.

  7. Doppler prediction of adverse perinatal outcome in intrauterine growth restriction

    Directory of Open Access Journals (Sweden)

    Nina Mahale

    2015-02-01

    Full Text Available Background: Objective of current study was to determine and compare the diagnostic performance of Doppler ultrasonography of the fetal Middle Cerebral Artery (MCA and Umbilical Artery (UA for prediction of adverse perinatal outcome in suspected intrauterine growth restriction (IUGR. Methods: Fifty singleton pregnancies in third trimester of pregnancy with suspected intrauterine growth restriction were examined with Doppler ultrasonography of fetal MCA and UA. Results: Twenty patients of the fifty included patients had at least one major or minor adverse outcome. Major adverse outcome included perinatal deaths which included both intrauterine deaths and early neonatal deaths, hypoxic ischemic encephalopathy, intraventricular hemorrhage, periventricular leukomalacia, pulmonary hemorrhage, necrotizing enterocolitis and septicemia. Minor outcomes included cesarean section for fetal distress, Apgar score below 7 at 5 minutes and admission to Neonatal Intensive Care Unit (NICU for treatment. MCA PI is the most sensitive(90% index in predicting any adverse perinatal outcome i.e. including both major and minor outcomes, Positive Predictive Value (PPV and specificity being greatest for MCA/UA PI (96.6%, 93.7%. For the major adverse outcome most sensitive (86.6% most specific (91.4% and with highest PPV (81.2% and NPV (94.1%, is MCA/UA PI. Ratio of MCA/UAPI is more sensitive (90% than PI of both the arteries alone for overall prediction of adverse perinatal outcome. Conclusions: Thus we conclude that the Doppler studies of the multiple vessels in the fetoplacental unit can help in the monitoring of the compromised fetus and can help us predicting neonatal morbidity. This may be helpful in determining the optimal time of deliveries in pregnancies complicated by IUGR. [Int J Reprod Contracept Obstet Gynecol 2015; 4(1.000: 119-130

  8. Renal Doppler ultrasound in patients with hypertension and metabolic syndrom.

    Science.gov (United States)

    Lubomirova, Mila; Djerassi, Regina; Kiperova, Boryana; Boyanov, Mihail; Christov, Vladimir

    2007-01-01

    Evaluation of the renal changes by conventional and Doppler ultrasound (US) was performed in patients with hypertension and obesity. 67 persons were examined and divided in 3 groups. Group I includes 27 patients--15 M and 12 F, average age 52+/-4.87 with well controlled diabetes mellitus type II and hypertension, Ccr.--139+/-1.31. Group II includes 20 patients--9 M and 11 F, average age 53+/-7 with well controlled hypertension without diabetes, with Ccr 128+/-7.8. Group III--20) pts. 8 F and 12 M, average age 54+/-5 with uncontrolled hypertension without diabetes, with Ccr 128+/-7.8. All examined pts. were with BMI>30 and hyperlipidemia--total cholesterol>6.5 mmol/l. Tests for microalbuminuria were negative in all 3 groups. In all three groups, using conventional US, the following parameters were detected by Aloca 4000 machine: renal (RV) and parenchyma (PV) volumes as well as Doppler parameters RI, PI, Vmax, Vmin, and Vmean. There were no significant differences between RV and PV of all examined groups: Group I--254+/-53, Group II--238+/-38, Group III--263+/-38, p=0.1. The strong correlation between renal volumes and BMI was found (Pearson's r 0.58). There were no significant differences between Vmax, Vmin, Vmean in all three groups. RI is normal <0.7 in all examined patients: Group I--0.63+/-0.06, Group II--0.61+/-0.02, Group III--0.66+/-0.03. RI in group III was significantly higher, p<0.05 compared to RI indices detected in other two groups but remains at normal levels. Intrarenal hemodynamics exhibited no difference in all examined groups. Analysis of the Doppler spectrum of the intrarenal arteries provides an accurate information about renal vascular changes but has no significant advantages in patients with hypertension and obesity with normal renal function and signs of hypertensive nephropathy "benign nephrosclerosis". Nevertheless Duplex Doppler Ultrasound is a noninvasive method which is an important part of the diagnostic algorithm in patients with

  9. 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.

  10. Investigations on the Doppler broadening of neutron resonance of hafnium

    International Nuclear Information System (INIS)

    In addition to earlier investigations of the resonance absorption of Hfsub(nat) investigations on the Doppler effect on resonance absorption have been performed at temperatures up to 5000C. Hf is considered as a burnable poison for HTR's. Hot-to-cold ratios have been measured with the aid of a slowing down lead spectrometer. Calculation for the hafnium resonance integral using the computer program GAROL with our set of resonance parameters are also presented. These calculations give also a way to determine the resonance integral for infinite dilution. (orig.)

  11. Doppler-shifted self-reflected wave from a semiconductor

    Science.gov (United States)

    Schuelzgen, Alex; Hughes, S.; Peyghambarian, Nasser

    1997-06-01

    We report the first experimental observation of a self- reflected wave inside a very dense saturable absorber. An intense femtosecond pulse saturates the absorption and causes a density front moving into the semiconductor sample. Due to the motion of the boundary between saturated and unsaturated areas of the sample the light reflected at this boundary is red-shifted by the Doppler effect. The spectrally shifted reflection makes it possible to distinguish between surface reflection and self-reflection and is used to proof the concept of the dynamic nonlinear skin effect experimentally. Quite well agreement with model calculations is found.

  12. 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.

  13. 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.

  14. Sub-Doppler cooling of sodium atoms in gray molasses

    OpenAIRE

    Colzi, Giacomo; Durastante, Gianmaria; Fava, Eleonora; Serafini, Simone; Lamporesi, Giacomo; Ferrari, Gabriele

    2015-01-01

    We report on the realization of sub-Doppler laser cooling of sodium atoms in gray molasses using the D1 optical transition ($3s\\, ^2S_{1/2} \\rightarrow 3p\\, ^2P_{1/2}$) at 589.8 nm. The technique is applied to samples containing $3\\times10^9$ atoms, previously cooled to 350 $\\mu$K in a magneto-optical trap, and it leads to temperatures as low as 9 $\\mu$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 densi...

  15. Doppler cooling of an optically dense cloud of trapped atoms

    CERN Document Server

    Schmidt, P O; Werner, J; Binhammer, T; Görlitz, A; Pfau, T; Schmidt, Piet O.; Hensler, Sven; Binhammer, Thomas; G\\"{o}rlitz, Axel; Pfau, Tilman

    2002-01-01

    We have studied a general technique for laser cooling a cloud of polarized trapped atoms down to the Doppler temperature. A one-dimensional optical molasses using polarized light cools the axial motional degree of freedom of the atoms in the trap. Cooling of the radial degrees of freedom can be modelled by reabsorption of scattered photons in the optically dense cloud. We present experimental results for a cloud of chromium atoms in a magnetic trap. A simple model based on rate equations shows quantitative agreement with the experimental results. This scheme allows us to readily prepare a dense cloud of atoms in a magnetic trap with ideal starting conditions for evaporative cooling.

  16. Using microwave Doppler radar in automated manufacturing applications

    Science.gov (United States)

    Smith, Gregory C.

    Since the beginning of the Industrial Revolution, manufacturers worldwide have used automation to improve productivity, gain market share, and meet growing or changing consumer demand for manufactured products. To stimulate further industrial productivity, manufacturers need more advanced automation technologies: "smart" part handling systems, automated assembly machines, CNC machine tools, and industrial robots that use new sensor technologies, advanced control systems, and intelligent decision-making algorithms to "see," "hear," "feel," and "think" at the levels needed to handle complex manufacturing tasks without human intervention. The investigator's dissertation offers three methods that could help make "smart" CNC machine tools and industrial robots possible: (1) A method for detecting acoustic emission using a microwave Doppler radar detector, (2) A method for detecting tool wear on a CNC lathe using a Doppler radar detector, and (3) An online non-contact method for detecting industrial robot position errors using a microwave Doppler radar motion detector. The dissertation studies indicate that microwave Doppler radar could be quite useful in automated manufacturing applications. In particular, the methods developed may help solve two difficult problems that hinder further progress in automating manufacturing processes: (1) Automating metal-cutting operations on CNC machine tools by providing a reliable non-contact method for detecting tool wear, and (2) Fully automating robotic manufacturing tasks by providing a reliable low-cost non-contact method for detecting on-line position errors. In addition, the studies offer a general non-contact method for detecting acoustic emission that may be useful in many other manufacturing and non-manufacturing areas, as well (e.g., monitoring and nondestructively testing structures, materials, manufacturing processes, and devices). By advancing the state of the art in manufacturing automation, the studies may help

  17. 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.

  18. Relativity and Exoplanets: Gravitational Microlensing, Doppler Beaming, and More

    Science.gov (United States)

    Gaudi, Scott

    2016-03-01

    Perhaps surprisingly, the theories of both special and general relativity play important roles in several areas of exoplanet research. I will review the most important and intriguing of these applications. The most obvious case is gravitational microlensing, which has become a fairly routine method of finding planets, and is poised to become even more important in the next decade. I will also briefly survey the numerous other areas where relativity plays a role in exoplanet theory and observations, including photometric Doppler beaming, general relativistic precession, transits of compact objects, and even (potentially) gravitational wave experiments.

  19. Multigroup Free-atom Doppler-broadening Approximation. Experiment

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-11-06

    The multigroup energy Doppler-broadening approximation agrees with continuous energy Dopplerbroadening generally to within ten percent for the total cross sections of 1H, 56Fe, and 235U at 250 lanl. Although this is probably not good enough for broadening from room temperature through the entire temperature range in production use, it is better than any interpolation scheme between temperatures proposed to date, and may be good enough for extrapolation from high temperatures. The method deserves further study since additional improvements are possible.

  20. Aerosol/Cloud Measurements Using Coherent Wind Doppler Lidars

    Science.gov (United States)

    Royer, Philippe; Boquet, Matthieu; Cariou, Jean-Pierre; Sauvage, Laurent; Parmentier, Rémy

    2016-06-01

    The accurate localization and characterization of aerosol and cloud layers is crucial for climate studies (aerosol indirect effect), meteorology (Planetary Boundary Layer PBL height), site monitoring (industrial emissions, mining,…) and natural hazards (thunderstorms, volcanic eruptions). LEOSPHERE has recently developed aerosol/cloud detection and characterization on WINDCUBE long range Coherent Wind Doppler Lidars (CWDL). These new features combine wind and backscatter intensity informations (Carrier-to-Noise Ratio CNR) in order to detect (aerosol/cloud base and top, PBL height) and to characterize atmospheric structures (attenuated backscatter, depolarization ratio). For each aerosol/cloud functionality the method is described, limitations are discussed and examples are given to illustrate the performances.

  1. Wind climatology observed over Kalpakkam using Doppler sodar

    International Nuclear Information System (INIS)

    Acoustic remote sensing of the prevailing winds in the boundary layer finds an important application in studying the problems related to air pollution meteorology. Analysis of the seasonal variation of vertical and horizontal wind speed with altitude is made using the Doppler sodar data collected at an atomic research centre, Kalpakkam. A pictorial representation of horizontal wind flow for each season is given in the form of wind roses at three lower levels of probing, namely 100, 300 and 500 m. Such analysis would prove to be a basic reference material for taking necessary meaningful emergency measures in similar climatic regions. (author). 18 refs., 10 figs

  2. Duplex Color Doppler Sonogram of the Orbital Diseases

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Kil Woo; Kim, Chul Soo; Park, Won [Hallym University College of Medicine, Chuncheon (Korea, Republic of)

    1996-06-15

    To evaluate the clinical significance of the color Doppler ultrasound at glaucoma and diseases associated with intraocular hypertension, diabetic retinopathy, central retinal vessel occlusion, and other ocular diseases. We performed color Doppler ultrasound in 194 eyes of the 121 patients consisting of 62 normal, 46 primary open angle glaucoma (POAG), 27 ocular hypertension (OH), 14 normotensive glaucoma (NTG), 13 secondary glaucoma (SG), 13 proliferating diaetic retinopathy (PDR), 10 central retinal venous obstruction (CRVO),5 retinal detachment, and 4 others. The ophthalmic artery flow velocity was measured with the real time Doppler ultrasound using 5{approx}10 MHz linear probe. Sample volume size ranged from 1 to 1.5 mm. Angle corrections were selected below 60 degree. Results were statistically analyzed with paired t-test. Mean peak systolic velocities in the ophthalmic and central retinal arteries among 62 normal eyes were 36.4 {+-} 1 cm / sec and 5.9 {+-}0.3 cm / sec. Mean peak systolic velocities were 32.4 {+-} 2 cm / sec in the POAG, 35.9 {+-} 2 cm / sec in OH, 32.9 {+-}4 cm / sec in the NTG, 42.6 {+-} 3 cm / sec in the PDR, 36.4 {+-} 3 cm / sec in the SG, and 35.2 {+-} 3 in the CRVO. Innormal subjects, mean peak systolic velocity in ophthalmic artery was decreased with increasing age but no statistically significant difference was seen with Paired t-test. Comparing flow velocities between the normal and the glaucomatous lesions showed statistically no significant difference for mean peak systolic velocity. No significant difference was noted between right and left eyes but significant difference between male and female patients with Paired t-test. Mean resistive indices were 0.73 in ophthalmic artery and 0.65 in central retinal artery. Mean sample volume settings were 3.1 cm in depth for ophthalmic artery and 2.7 cm in depth for centralretinal artery. Color Doppler ultrasonogram of the orbit could diagnose the carotid cavernous fistula and the retinal

  3. Duplex Color Doppler Sonogram of the Orbital Diseases

    International Nuclear Information System (INIS)

    To evaluate the clinical significance of the color Doppler ultrasound at glaucoma and diseases associated with intraocular hypertension, diabetic retinopathy, central retinal vessel occlusion, and other ocular diseases. We performed color Doppler ultrasound in 194 eyes of the 121 patients consisting of 62 normal, 46 primary open angle glaucoma (POAG), 27 ocular hypertension (OH), 14 normotensive glaucoma (NTG), 13 secondary glaucoma (SG), 13 proliferating diaetic retinopathy (PDR), 10 central retinal venous obstruction (CRVO),5 retinal detachment, and 4 others. The ophthalmic artery flow velocity was measured with the real time Doppler ultrasound using 5∼10 MHz linear probe. Sample volume size ranged from 1 to 1.5 mm. Angle corrections were selected below 60 degree. Results were statistically analyzed with paired t-test. Mean peak systolic velocities in the ophthalmic and central retinal arteries among 62 normal eyes were 36.4 ± 1 cm / sec and 5.9 ±0.3 cm / sec. Mean peak systolic velocities were 32.4 ± 2 cm / sec in the POAG, 35.9 ± 2 cm / sec in OH, 32.9 ±4 cm / sec in the NTG, 42.6 ± 3 cm / sec in the PDR, 36.4 ± 3 cm / sec in the SG, and 35.2 ± 3 in the CRVO. Innormal subjects, mean peak systolic velocity in ophthalmic artery was decreased with increasing age but no statistically significant difference was seen with Paired t-test. Comparing flow velocities between the normal and the glaucomatous lesions showed statistically no significant difference for mean peak systolic velocity. No significant difference was noted between right and left eyes but significant difference between male and female patients with Paired t-test. Mean resistive indices were 0.73 in ophthalmic artery and 0.65 in central retinal artery. Mean sample volume settings were 3.1 cm in depth for ophthalmic artery and 2.7 cm in depth for centralretinal artery. Color Doppler ultrasonogram of the orbit could diagnose the carotid cavernous fistula and the retinal detachment correctly

  4. Doppler imaging of the helium-variable star a Cen

    OpenAIRE

    Bohlender, David A.; Rice, J. B.; P. Hechler

    2010-01-01

    The helium-peculiar star a Cen exhibits line profile variations of elements such as iron, nitrogen and oxygen in addition to its well-known extreme helium variability. New high S/N, high-resolution spectra are used to perform a quantitative measurement of the abundances of the star and determine the relation of the concentrations of the heavier elements on the surface of the star to the helium concentration and the magnetic field orientation. Doppler images have been created using programs de...

  5. Dual measurement terminal fall speeds and multiple Doppler winds

    Science.gov (United States)

    Grosh, R. C.

    1983-01-01

    It is shown that radar-derived terminal fall speed measurements can be useful in determining vertical air velocity in the middle troposphere by means of a network of Doppler radars. The theoretical principles of the dual measurement technique are described, and the relationship between measurement accuracies and theoretical estimates of terminal fall speeds is discussed. It is demonstrated that the use of differential reflectivity to estimate terminal fall speeds can reduce the standard error of vertical velocity estimates by 40-50 percent.

  6. 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...... inflammation in the ankle region of JIA patients. The talo-crural joint was not always involved. Disease was frequently found in compartments difficult to evaluate clinically. US enabled exact guidance of steroid injections, gave a low rate of subcutaneous atrophy and was proved valuable for follow...

  7. Doppler Images and Chromospheric Variability of TWA 6

    OpenAIRE

    Skelly, M. B.; Unruh, Y. C.; Cameron, A. Collier; Barnes, J. R.; Donati, J.-F; Lawson, W. A.; Carter, B. D.

    2008-01-01

    We present Doppler imaging and Balmer line analysis of the weak-line T Tauri star TWA 6. Using this data we have made one of the first attempts to measure differential rotation in a T Tauri star, and the first detection of a slingshot prominence in such a star. We also show the most direct evidence to date of the existence of solar-type plages in a star other than the Sun. Observations were made over six nights: 11-13th February 2006 and 18-20th February 2006, when spectra were taken with the...

  8. Current-induced spin-wave Doppler shift.

    Science.gov (United States)

    Vlaminck, Vincent; Bailleul, Matthieu

    2008-10-17

    Spin transfer appears to be a promising tool for improving spintronics devices. Experiments that quantitatively access the magnitude of the spin transfer are required for a fundamental understanding of this phenomenon. By inductively measuring spin waves propagating along a permalloy strip subjected to a large electrical current, we observed a current-induced spin wave Doppler shift that we relate to the adiabatic spin transfer torque. Because spin waves provide a well-defined system for performing spin transfer, we anticipate that they could be used as an accurate probe of spin-polarized transport in various itinerant ferromagnets. PMID:18927387

  9. Sub-Doppler laser cooling and magnetic trapping of erbium

    CERN Document Server

    Berglund, Andrew J; McClelland, Jabez J

    2008-01-01

    We investigate cooling mechanisms in magneto-optically and magnetically trapped erbium. We find efficient sub-Doppler cooling in our trap, which can persist even in large magnetic fields due to the near degeneracy of two Lande g factors. Furthermore, a continuously loaded magnetic trap is demonstrated where we observe temperatures below 25 microkelvin. These favorable cooling and trapping properties suggest a number of scientific possibilities for rare-earth atomic physics, including narrow linewidth laser cooling and spectroscopy, unique collision studies, and degenerate bosonic and fermionic gases with long-range magnetic dipole coupling.

  10. Effect of window reflections on photonic Doppler velocimetry measurements

    Energy Technology Data Exchange (ETDEWEB)

    Ao, T.; Dolan, D. H. [Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States)

    2011-02-15

    Photonic Doppler velocimetry (PDV) has rapidly become a standard diagnostic for measuring velocities in dynamic compression research. While free surface velocity measurements are fairly straightforward, complications occur when PDV is used to measure a dynamically loaded sample through a window. Fresnel reflections can severely affect the velocity and time resolution of PDV measurements, especially for low-velocity transients. Shock experiments of quartz compressed between two sapphire plates demonstrate how optical window reflections cause ringing in the extracted PDV velocity profile. Velocity ringing is significantly reduced by using either a wedge window or an antireflective coating.

  11. Effect of window reflections on photonic Doppler velocimetry measurements

    International Nuclear Information System (INIS)

    Photonic Doppler velocimetry (PDV) has rapidly become a standard diagnostic for measuring velocities in dynamic compression research. While free surface velocity measurements are fairly straightforward, complications occur when PDV is used to measure a dynamically loaded sample through a window. Fresnel reflections can severely affect the velocity and time resolution of PDV measurements, especially for low-velocity transients. Shock experiments of quartz compressed between two sapphire plates demonstrate how optical window reflections cause ringing in the extracted PDV velocity profile. Velocity ringing is significantly reduced by using either a wedge window or an antireflective coating.

  12. Effect of window reflections on photonic Doppler velocimetry measurements

    Science.gov (United States)

    Ao, T.; Dolan, D. H.

    2011-02-01

    Photonic Doppler velocimetry (PDV) has rapidly become a standard diagnostic for measuring velocities in dynamic compression research. While free surface velocity measurements are fairly straightforward, complications occur when PDV is used to measure a dynamically loaded sample through a window. Fresnel reflections can severely affect the velocity and time resolution of PDV measurements, especially for low-velocity transients. Shock experiments of quartz compressed between two sapphire plates demonstrate how optical window reflections cause ringing in the extracted PDV velocity profile. Velocity ringing is significantly reduced by using either a wedge window or an antireflective coating.

  13. 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.

  14. Optical spectroscopy and Doppler tomography of Cygnus X-2

    OpenAIRE

    Elebert, P.; Callanan, P.J.; Torres, M. A. P.; Garcia, M. R.

    2009-01-01

    We present phase resolved optical spectroscopy and Doppler tomography of V1341 Cygni, the optical counterpart to the neutron star low mass X-ray binary Cygnus X-2. We derive a radial velocity curve for the secondary star, finding a projected radial velocity semi-amplitude of K2 = 79 +/- 3 km/s, leading to a mass function of 0.51 +/- 0.06 Msun, ~30% lower than the previous estimate. We tentatively attribute the lower value of K2 (compared to that obtained by other authors) to variations in the...

  15. 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.

  16. 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

  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. 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...

  19. 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.

  20. Doppler imaging of the helium-variable star a Cen

    CERN Document Server

    Bohlender, David A; Hechler, P

    2010-01-01

    The helium-peculiar star a Cen exhibits line profile variations of elements such as iron, nitrogen and oxygen in addition to its well-known extreme helium variability. New high S/N, high-resolution spectra are used to perform a quantitative measurement of the abundances of the star and determine the relation of the concentrations of the heavier elements on the surface of the star to the helium concentration and the magnetic field orientation. Doppler images have been created using programs described in earlier papers by Rice and others. An alternative surface abundance mapping code has been used to model the helium line variations after our Doppler imaging of certain individual helium lines produced mediocre results. We confirm the long-known existence of helium-rich and helium-poor hemispheres on a Cen and we measure a difference of more than two orders of magnitude in helium abundance from one side of the star to the other. Helium is overabundant by a factor of about 5 over much of the helium-rich hemispher...