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Evaluating the cardiac function of duchenne muscular dystrophy with Doppler Tei index  

International Nuclear Information System (INIS)

Objective: To evaluate the cardiac function of early Duchenne muscular dystrophy (DMD) by left ventricular ejection fraction (LVEF) and pulse Doppler Tei index. Methods: Twenty-eight DMD patients and fifteen normal people were studied. LVEF, E/A and Tei index were measured and calculated by M-mode and Pulse wave Doppler respectively. Results: Compared with control group, Tei index and IRT were significantly high, and there were not significant difference in LVEF(%) and E/A. Conclusion: Tei index was valuable in assessing cardiac function of early DMD. (authors)

2007-10-01

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Índice de Tei, nuevo indicador doppler para el estudio de la insuficiencia cardíaca Tei's index, a new doppler indicator for the study of heart failure  

Directory of Open Access Journals (Sweden)

Full Text Available La mayoría de los pacientes con insuficiencia cardíaca (IC presentan afectación sistólica y diastólica combinadas; un índice derivado del doppler, conocido cono índice de Tei, permite evaluar de forma no invasiva ambas alteraciones. Se estudiaron 25 pacientes con edad promedio de 55 ± 16 años con IC. Se compararon los datos obtenidos con los de un grupo de personas sanas. Se observó un incremento de IT en los pacientes con IC. Se halló una relación estadísticamente significativa entre el IT y la fracción de eyección ventricular izquierda y el tiempo de desaceleración del pico E en el flujograma mitral de doppler. Se presentaron los resultados del seguimiento de los pacientes en un período de 3 y 6 meses. Se concluyó que aquellos que presentan el índice de Tei elevado tienen una evolución desfavorable a los 6 meses.Most of the patients with heart failure present combined systolic and diastolic affectation, an index derived from doppler known as Tei's index that allow to evaluate both alterations in a non-invasive way. 25 patients aged 55 ± 16 as an average that suffered from heart failure were studied. The obtained data were compared with those of a sound group. It was observed an increase of Tei's index among patients with heart failure. It was found a statistically significant relation between the Tei's index, the left ventricular ejection fraction and the deacceleration time of peak E in the doppler's mitral flow chart. The results of the follow-up of patients in a period from 3 to 6 months were shown. It was concluded that those with an elevated Tei's index have an unfavorable evolution at 6 months.

Javier González Fernández

2004-08-01

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Índice de Tei, nuevo indicador doppler para el estudio de la insuficiencia cardíaca / Tei's index, a new doppler indicator for the study of heart failure  

Scientific Electronic Library Online (English)

Full Text Available SciELO Cuba | Language: Spanish Abstract in spanish La mayoría de los pacientes con insuficiencia cardíaca (IC) presentan afectación sistólica y diastólica combinadas; un índice derivado del doppler, conocido cono índice de Tei, permite evaluar de forma no invasiva ambas alteraciones. Se estudiaron 25 pacientes con edad promedio de 55 ± 16 años con I [...] C. Se compararon los datos obtenidos con los de un grupo de personas sanas. Se observó un incremento de IT en los pacientes con IC. Se halló una relación estadísticamente significativa entre el IT y la fracción de eyección ventricular izquierda y el tiempo de desaceleración del pico E en el flujograma mitral de doppler. Se presentaron los resultados del seguimiento de los pacientes en un período de 3 y 6 meses. Se concluyó que aquellos que presentan el índice de Tei elevado tienen una evolución desfavorable a los 6 meses. Abstract in english Most of the patients with heart failure present combined systolic and diastolic affectation, an index derived from doppler known as Tei's index that allow to evaluate both alterations in a non-invasive way. 25 patients aged 55 ± 16 as an average that suffered from heart failure were studied. The obt [...] ained data were compared with those of a sound group. It was observed an increase of Tei's index among patients with heart failure. It was found a statistically significant relation between the Tei's index, the left ventricular ejection fraction and the deacceleration time of peak E in the doppler's mitral flow chart. The results of the follow-up of patients in a period from 3 to 6 months were shown. It was concluded that those with an elevated Tei's index have an unfavorable evolution at 6 months.

González Fernández, Javier; Prohías Martínez, Juan; Anello Utrera, Hilda; Rodríguez de Armas, Lissette.

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Influência da redução da pré-carga sobre o índice de desempenho miocárdico (índice de Tei e outros parâmetros Doppler ecocardiográficos da função ventricular esquerda Influence of preload reduction on Tei index and other Doppler echocardiographic parameters of left ventricular function  

Directory of Open Access Journals (Sweden)

Full Text Available OBJETIVO: Avaliar os efeitos da redução da pré-carga induzida por uma sessão de hemodiálise sobre o índice de desempenho miocárdico (Tei e outros parâmetros ecocardiográficos de função cardíaca. MÉTODOS: Estimamos o índice de Tei e parâmetros de função sistólica e diastólica do ventrículo esquerdo (VE, antes e depois de uma sessão de hemodiálise. Incluímos no estudo indivíduos em ritmo sinusal e sem antecedentes de insuficiência coronariana ou evidências de valvopatia e derrame pericárdico. RESULTADOS: 15 pacientes (8 homens, idade 53 ± 14 anos completaram o estudo. Após ultrafiltração de 2,2 ± 1,1 litros, a onda E diminuiu (p OBJECTIVE: To assess the influence of preload reduction by hemodialysis on Doppler Tei Index of myocardial performance and other parameters of cardiac function. METHODS: The Tei index and left ventricular (LV systolic and diastolic function parameters were estimated, before and after a single hemodialysis session. Only subjects who were in sinus rhythm, without history of coronary artery disease, and no evidence of cardiac valve disease and pericardial effusion were included in the study. RESULTS: Fifteen patients (8 men, mean age 53 ± 14 years completed the study. After an ultrafiltration of 2,2 ± 1,1 liters, peak mitral E velocity decreased (p< 0,05 and A velocity remained unchanged (p = ns, resulting in reduction of E/A ratio (p< 0,01. The Tei index increased (from 0,57 ± 0,07 to 0,65 ± 0,09, p< 0,01 because of significant prolongations in isovolumetric relaxation time (from 101 ± 14 to 113 ± 17 ms, p< 0,01 and ejection time (from 271 ± 22 to 252 ± 22, p< 0,05. The isovolumetric contraction time did not vary (p = ns. There was no change in diastolic tissue Doppler parameters, while systolic velocities increased (p< 0,05. CONCLUSION: The Tei index was affected by hemodialysis-induced preload alterations, as well as other mitral inflow Doppler-derived parameters. The diastolic parameters of mitral annulus Doppler tissue were independent of preload, while systolic velocities suggested improved systolic function.

Silvio Henrique Barberato

2006-06-01

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Determinación de los valores normales del índice de Tei (índice de performance miocárdico) y otros parámetros ecocardiográficos doppler de la función ventricular izquierda en caninos sanos / Determination of tei index (index of myocardial performance) and other ecocadiography doppler parameters of left ventricular function in healthy dogs  

Scientific Electronic Library Online (English)

Full Text Available SciELO Colombia | Language: Spanish Abstract in spanish La falla cardiaca está relacionada con anormalidades en la contracción y relajación ventricular. Estudios recientes han mostrado que en la mayoría de los pacientes con insuficiencia cardiaca coexisten alteraciones de la función sistólica y diastólica, y en algunos casos la función sistólica es norma [...] l pero la falla cardiaca es generada por disfunción ventricular diastólica. El índice de performance miocárdico (tiempo de contracción isovolumétrica sumado al tiempo de eyección ventricular dividido el tiempo de eyección, "índice de Tei") ha sido descrito como una manera más efectiva para el análisis de la Disfunción Miocárdica Global que otros parámetros de función sistólica y diastólica. Con base en estos antecedentes, los autores determinaron el valor normal del índice de Tei para el ventrículo izquierdo en caninos sanos en la ciudad de Bogotá (2.600 msnm) con el objeto de utilizar dicho valor como índice de la función sisto-diastólica. Se obtuvo un valor medio de 0,33 con un desvío estándar de 0,10. Asimismo pudo verificarse que no existe correlación con la frecuencia cardiaca, peso corporal ni con la fracción de eyección ventricular izquierdo (P Abstract in english Congestive heart failure is related to contraction and relaxation ventricle abnormalities. Recent studies had shown that in the majority of the patients with congestive cardiac failure coexist alteration of systolic and diastolic function and in many cases the systolic function is normal and the car [...] diac failure is supported only by the diastolic dysfunction. A combined myocardial performance index (isovolumetric contraction time plus isovolumetric relaxation time divided by ejection time, "Tei-Index") has been described which may be more effective for analysis of global cardiac dysfunction than systolic and diastolic measures alone. Supported by these previous information, the authors determined the normal value of the left ventricular Tei index in healthy dogs at Bogota (at an altitude of 2600 mosl) in order to evaluate the systodiatolic function. A mean value of 0,33 with a standard deviation of 0,10 was obtained. No correlation exists with cardiac rate), body weight neither with ejection fraction (P> 0,05).

Iván, Álvarez; Carlos, Ortiz; Luis Eduardo, Cruz.

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Determinación del valor normal del índice de Tei del ventrículo izquierdo en caninos sanos Determination of the normal value of the left ventricular Tei index in healthy dogs  

Directory of Open Access Journals (Sweden)

Full Text Available Estudios recientes han demostrado que en la mayoría de los pacientes con insuficiencia cardiaca congestiva coexisten tanto alteración de la función sistólica como disfunción de la diastólica y, en muchos casos, la función sistólica se encuentra normal y la insuficiencia cardiaca esta sustentada solamente por la disfunción diastólica, hecho que tiene implicancias diagnósticas, terapéuticas y pronósticas. Recientemente, Tei y colaboradores propusieron un nuevo índice Doppler que permite el estudio combinado de algunos de los intervalos sistólicos y diastólicos. En base a estos antecedentes los autores determinaron el valor normal del índice de Tei para el ventrículo izquierdo en caninos sanos con el objeto de utilizar dicho valor como índice de la función sistodiatólica. Se obtuvo un valor medio de 0,372 con un desvío estándar de 0,04. Asimismo pudo verificarse que no existe correlación con la frecuencia cardiaca (P> 0,0975 ni con la tensión arterial sistólica (P> 0,0895 pero si con el acortamiento fraccional del ventrículo izquierdo (PRecent studies have showed that in the majority of the patients with congestive cardiac failure coexist alteration of systolic and diastolic function and in many cases the systolic function is normal and the cardiac failure this supported only by the diastolic dysfunction. This fact has therapeutic, diagnostic and prognostic implications. Recently, Tei and co-workers proposed a new Doppler index that permits the combined evaluation of some of the systolic and diastolic intervals. Supported by these antecedents the authors determined the normal value of the left ventricular Tei index in healthy dogs in order to evaluate the systodiatolic function. A mean value of 0,372 with a standard deviation of 0,04 was obtained. Likewise the authors could verified that not correlation exists with cardiac rate (P> 0,0975 neither with the systolic arterial pressure (P> 0,0895 but a significant correlation exists with the left ventricular fractional shortening (P<0,05.

C. Lightowler

2006-12-01

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The Tei index and asymptomatic myocarditis in children with severe dengue.  

Science.gov (United States)

This study aimed to assess myocardial involvement in infants and children with severe dengue (as per the new World Health Organization [WHO] classification 2009) using the Tei index. This prospective observational study was conducted in the Department of Pediatrics, PGIMER and the associated Dr. RML Hospital, New Delhi from August to December 2010. The study included 67 children (ages 3 months-14 years) who satisfied the WHO criteria for the diagnosis of probable dengue fever with warning signs or severe dengue and tested positive for dengue via immunoglobulin-M (IgM) capture enzyme-linked immunoassay (MAC-ELISA). The patients were subjected to a complete blood count, liver function tests, renal profile, electrocardiography, myocardial band enzymes of creatine phosphokinase (CPK-MB), chest x-ray, abdomen ultrasonography, and two-dimensional echocardiography with color-flow Doppler mapping. Ejection fraction and Tei index measurements were performed. Significantly fewer patients with severe dengue were found to have myocardial involvement at admission by ejection fraction (48 %) and E/E' (37 %), than by the Tei index (70 %). Of the 67 patients with severe dengue, one died, giving a case fatality rate of 1.5 %. At discharge, the Tei index persisted on the high side for patients with myocardial involvement, whereas the ejection fraction improved for the majority of them. Most of the patients with severe dengue had asymptomatic myocarditis, as evident by a deranged Tei index, which improved but did not normalize by the time of discharge, necessitating a longer follow-up period. For the majority of the patients, inotropic support was not required to maintain hemodynamic stability. PMID:23397334

Yadav, Dinesh Kumar; Choudhary, Sandeep; Gupta, Pankaj Kumar; Beniwal, Mukesh Kumar; Agarwal, Sheetal; Shukla, Umesh; Dubey, N K; Sankar, Jhuma; Kumar, Pradeep

2013-08-01

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Determinación del valor normal del índice de Tei del ventrículo izquierdo en caninos sanos / Determination of the normal value of the left ventricular Tei index in healthy dogs  

Scientific Electronic Library Online (English)

Full Text Available SciELO Argentina | Language: Spanish Abstract in spanish Estudios recientes han demostrado que en la mayoría de los pacientes con insuficiencia cardiaca congestiva coexisten tanto alteración de la función sistólica como disfunción de la diastólica y, en muchos casos, la función sistólica se encuentra normal y la insuficiencia cardiaca esta sustentada sola [...] mente por la disfunción diastólica, hecho que tiene implicancias diagnósticas, terapéuticas y pronósticas. Recientemente, Tei y colaboradores propusieron un nuevo índice Doppler que permite el estudio combinado de algunos de los intervalos sistólicos y diastólicos. En base a estos antecedentes los autores determinaron el valor normal del índice de Tei para el ventrículo izquierdo en caninos sanos con el objeto de utilizar dicho valor como índice de la función sistodiatólica. Se obtuvo un valor medio de 0,372 con un desvío estándar de 0,04. Asimismo pudo verificarse que no existe correlación con la frecuencia cardiaca (P> 0,0975) ni con la tensión arterial sistólica (P> 0,0895) pero si con el acortamiento fraccional del ventrículo izquierdo (P Abstract in english Recent studies have showed that in the majority of the patients with congestive cardiac failure coexist alteration of systolic and diastolic function and in many cases the systolic function is normal and the cardiac failure this supported only by the diastolic dysfunction. This fact has therapeutic, [...] diagnostic and prognostic implications. Recently, Tei and co-workers proposed a new Doppler index that permits the combined evaluation of some of the systolic and diastolic intervals. Supported by these antecedents the authors determined the normal value of the left ventricular Tei index in healthy dogs in order to evaluate the systodiatolic function. A mean value of 0,372 with a standard deviation of 0,04 was obtained. Likewise the authors could verified that not correlation exists with cardiac rate (P> 0,0975) neither with the systolic arterial pressure (P> 0,0895) but a significant correlation exists with the left ventricular fractional shortening (P

C., Lightowler; J., Barrios; O., Casalonga; B., Ditollo; M., Bartolomeo; M., Rotondaro.

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A Framework for TEI-Based Scholarly Text Editions  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In this paper, we describe an interdisciplinary project in which visualization techniques were developed for and applied to scholarly work from literary studies. The aim was to bring Christof Schöch's electronic edition of Bérardier de Bataut's Essai sur le récit (1776) to the web. This edition is based on the Text Encoding Initiative's XML-based encoding scheme (TEI P5, subset TEI-Lite). This now de facto standard applies to machine-readable texts used chiefly in the humanities and social...

Pape, Sebastian; Scho?ch, Christof; Wegner, Lutz

2010-01-01

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XML, TEI, and Digital Libraries in the Humanities.  

Science.gov (United States)

Describes the history and major features of XML and TEI, discusses their potential utility for the creation of digital libraries, and focuses on XML's application in the humanities, particularly theater and drama studies. Highlights include HTML and hyperlinks; the impact of XML on text encoding and document access; and XML and academic…

Nellhaus, Tobin

2001-01-01

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The usefulness of the TEI surgery in Thessaloniki  

Directory of Open Access Journals (Sweden)

Full Text Available It is a known fact that in every higher academic institution functions a surgery that aims at providing care or first aid to workers and students. Aim: The aim of the present study is to show the usefulness of surgery of TEI in Thessaloniki during its daily operation and the offer of valuable care and help not only to employees but to the students as well. Material - method: It is a retrospective-comparative research. The files of surgery of TEI in Thessaloniki were studied during 2005-2007. The descriptive statistics was used on the equitable study, recording, processing and analysis of these elements via the Excel program. Results-Discussion: By the retrospective-comparative study of pre-mentioned elements are pointed out following that at a three-year period 2005-2007 2391 individuals visited the surgery with the employees being 1052 (44% out of which 624 (59% were women and 428 (41% were men The students were 1399 (56% out of which 547 (41% were boys and 792 (59% were girls In the whole sample 975 (40,75% were men (students and employees and1416 (59,23% were women (students and employees. Regarding the reasons for which men and women visited the surgery headache (33%, hypertension (19%, control of arterial pressure (25%, dysmenorrhea (10%, gastralgia (6%, toothache (2%, lumbago (2%, dizziness (2% and measurement of blood glucose (1%. As regards the two sexes (men and women, it seems that women except for the dysmenorrhea visit mostly the surgery because of headaches, gastralgia, toothache, lumbago and dizziness. On the contrary, men usually visit the surgery because of hypertension, control of arterial pressure and measurement of blood glucose Conclusions: According to the information above, the usefulness of surgery is proved, which covers the real needs of health service and care for both employees and students.

Kourkouta L.

2010-04-01

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Technological Environmental Innovations (TEIs) in a chain-analytical and life-cycle-analytical perspective  

Digital Repository Infrastructure Vision for European Research (DRIVER)

"This paper is based on an empirical survey of technological environmental innovations (TEIs), i.e. new products, processes and practices that come with benign environmental effects. The survey is based on product chain analysis and innovation life cycle analysis. It turns out that most TEIs occur upstream rather than downstream, i.e. chain-upwards in the beginning rather than in the end of product chains, and in early stages of technology or product development rather than in ...

Huber, Joseph

2008-01-01

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Right Ventricular Tissue Doppler in Space Flight  

Science.gov (United States)

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.

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

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Studies of computer tomography in the space occupying lesion (SOL) of liver. Tumor enhance index (TEI)  

Energy Technology Data Exchange (ETDEWEB)

The CT number was measured in 36 patients with liver diseases by plain CT and contrast-enhanced CT to compare changes in the condition of any of the liver diseases. A simple method in which the degree of enhancement of liver tumors can be expressed was devised, whereby tumor enhance index (TEI) was established and calculated according to the diseases. In patients with primary or metastatic liver tumors, the CT number obtained by contrast-enhanced CT was significantly larger than that by plain CT (P < 0.001). TEIs were significantly higher in patients with primary or metastatic liver tumors than in patients with benign tumors (P < 0.001), and also, higher in patients with primary liver tumors than in patients with metastatic liver tumors (P < 0.05).

Chen, Kon-Min; Kawashima, Koji; Hayashi, Hiroshi; Sakaguchi, Isao (Sumitomo Bessi Hospital, Niihama, Ehime (Japan))

1984-01-01

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The TXM Platform: Building Open-Source Textual Analysis Software Compatible with the TEI Encoding Scheme  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This paper describes the rationale and design of an XML-TEI encoded corpora compatible analysis platform for text mining called TXM. The design of this platform is based on a synthesis of the best available algorithms in existing textometry software. It also relies on identifying the most relevant open-source technologies for processing textual resources encoded in XML and Unicode, for efficient full-text search on annotated corpora and for statistical data analysis. The architecture is based...

Heiden, Serge

2010-01-01

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Tissue Doppler Echocardiographic Findings of Left Ventricle in Children with Sickle-Cell Anemia  

Science.gov (United States)

Background: Sickle-cell disease (SCD) is an inherited hemoglobin childhood disorder, frequently complicated by pulmonary hypertension and cardiac involvement. Cardiovascular events and complications are the leading cause of mortality and morbidity in patients with SCD. Tissue Doppler imaging and the myocardial performance index (Tei index), are simple indices for the assessment of the cardiac function. The purpose of this study was to assess the left ventricular function in children with SCD. Methods: Sixty-four patients with SCD (mean age = 11.7 ± 5.5 years) were compared with 50 age-matched healthy controls (mean age = 11.2 ± 5.20 years). Myocardial wall motion velocities at the lateral mitral annulus and the junction between the medial mitral annulus and the interventricular septum were assessed during systole (Sa), early diastole (Ea), and late diastole (Aa) through a four-chamber view using pulsed Doppler echocardiography. The ejection fraction and shortening fraction were estimated. The Tei index was estimated via tissue Doppler echocardiography. Results: The results showed that Ea and Aa velocity in the mitral annulus and interventricular septum had no difference between the patients and controls (p value > 0.05), and nor was there any difference between the two groups as regards the Tei index, Ea/Aa, ejection fraction, and shortening fraction (p value > 0.05). Sam wave velocity, however, had a significant difference between the two groups (p value < 0.038). Conclusion: The Tei index is a sensitive indicator for the cardiac function in chronic diseases and the right ventricular function in some disorders such as SCD.

Ghaderian, Mehdi; Keikhaei, Bijan; Heidari, Morteza; Salehi, Zahra; Azizi Malamiri, Reza

2012-01-01

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Doppler Effect  

Science.gov (United States)

Doppler effect followed from water waves to sound waves to light waves. Red shift of the universe is also explored. What is doppler effect? It is the change in frequency of a wave for an observer moving relative to the source of the wave. What does that mean? Watch this: moving doppler effect video What does the doppler effect look like in a stationary and moving object? dooppler effect views What does doppler effect have to do with stars and galaxies??? View the following ...

Brown, Mrs.

2010-10-26

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Parameter study of TEIS model, two-zone model, and stanitz's equations  

International Nuclear Information System (INIS)

Recently TEIS model, two-zone model, and stanitz equations are often used for off-design performance prediction of centrifugal compressor and pump. The prediction results often agree well with experimental data. However these models and equations have some important variables which have a great influence on overall performance prediction curve. But no systematic study about these variables has been performed. So, in this paper, a systematic study about these variables' influence on overall performance prediction curve is performed. Finally the meaning of the variables and the research to be undertaken are discussed

2000-04-20

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Doppler Effect  

Science.gov (United States)

In this activity, learners use a tuning fork to explore how the Doppler effect works. They strike the tuning fork to produce a sound, then observe as the tone changes as the fork is swung back and forth. Learners also explore applications of the Doppler effect in technology.

Cosi

2009-01-01

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Left Ventricular Diastolic and Systolic Performance: A Study Using Tei Index in Adulthood Patients with Thalassemia Major  

Directory of Open Access Journals (Sweden)

Full Text Available Introduction: Cardiac complications, including heart failure, are the most important secondary ones of the thalassemia major disease, which manifests itself in adolescence and early adulthood. Appropriate, low cost diagnostic tools available as well as knowing its related factors are the most important components of therapy in these patients, given the importance of these complications, or by examining and revealing early symptoms. Thus, in this study, we intend to examine the systolic and diastolic ventricular effects in adult patients with the help of Tei index. Methods: 70 adult patients with thalassemia major were examined in this study. Frequency of Tei index and its association with factors such as age, sex, level of packed cell injection, as well as hemosiderosis were measured in two blood levels of more than 1000 ferretins. Results: In this study, 70 youth adult patients with thalassemia major with an average age of 21.3± 2.8 years were studied, 31 were male (44.4%. Tei index were abnormal in 16 patients (24%. There is no statistically significant correlation between the Tei index and one of the variables of age, gender, number and duration of blood transfusion and deferoxamine, the hemoglobin level and the number of ferretins (P>0.05. Discussion: Study on Tei index shows that many patients are subclinically involved in the disease before the onset of clinical symptoms of heart failure, the subject which raises the need for early diagnosis of the disease; and it seems that none of the demographic factors or factors related to disease cannot be considered as a main cause or warning of the disease; and the above results can be confirmed only on the basis of paraclinical tests.

Kaveh Mousavi Kani

2011-04-01

 
 
 
 
21

Doppler echocardiography  

Energy Technology Data Exchange (ETDEWEB)

This text will serve to introduce the use of Doppler in clinical cardiology in a straightforward, practical format. The work features the following categories: a review and discussion of the fundamental principles and characteristics of ultrasound; examination techniques, including continuous and pulse modes; clinical application with acquired disease the focus; congenital disease, particularly defects, stenotic lesions, and complicated lesions; and fetal clinical applications of Doppler echocardiography.

Nanda, N.C.

1985-01-01

22

Doppler echocardiography  

International Nuclear Information System (INIS)

This text will serve to introduce the use of Doppler in clinical cardiology in a straightforward, practical format. The work features the following categories: a review and discussion of the fundamental principles and characteristics of ultrasound; examination techniques, including continuous and pulse modes; clinical application with acquired disease the focus; congenital disease, particularly defects, stenotic lesions, and complicated lesions; and fetal clinical applications of Doppler echocardiography

1985-01-01

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Assesment of the TEI index of myocardial performance in dogs with doxorubicin-induced cardiomiopathy / Evaluación del índice de desempeño miocárdico de TEI en perros con cardiomiopatía inducida por doxorrubicina  

Scientific Electronic Library Online (English)

Full Text Available SciELO Chile | Language: English Abstract in spanish El desarrollo de una cardiomiopatía dosis dependiente es la principal limitación para el uso de doxorrubicina en protocolos de quimioterapia tanto en seres humanos como en animales. En estos casos, la función global del miocardio puede ser cedida, teniendo como resultado signos atribuibles a la insu [...] ficiencia cardíaca congestiva. En este estudio, nosotros investigamos la capacidad del índice de desempeño miocárdico de Tei para identificar disfunción de miocardio en perros sanos tratados con doxorrubicina a una dosis cumulativa de 210 mg/m² en un periodo de 147 días, comparándolo con otros indicadores ecográficos estándar de función sistólica y diastólica. Nuestros resultados indicaron que el índice de Tei, el tiempo de relajación isovolumétrica, el período de pre-eyección, y la relación período de pre-eyección/tiempo de eyección ventricular izquierda pudieron identificar los efectos cardiotóxicos de doxorrubicina en la función cardíaca cuando sólo 60 mg/m² habían sido administrados, mientras los parámetros estándar sistólicos y diastólicos, incluso el diámetro sistólico del ventrículo izquierdo, la fracción de eyección y la fracción de acortamiento, necesitaron por lo menos 120 mg/mg² para empeorar. Se concluye que la terapia prolongada con antraciclinas perjudica las funciones sistólica y diastólica, que pueden ser documentadas antes adicionándose el índice de Tei a la evaluación ecográfica estándar en animales que reciben doxorrubicina. Abstract in english The development of a dose-dependent cardiomyopathy is the main limitation for the use of doxorubicin in chemotherapy protocols in both humans and animals. In this setting, the global myocardial function may be compromised resulting in signs of congestive heart failure. In this study, we investigated [...] the ability of the Tei index of myocardial performance to identify myocardial dysfunction in healthy dogs receiving doxorubicin to a cumulative dose of 210 mg/m² over 147 days, comparing it with other standard echocardiographic indicators of systolic and diastolic function. Our results indicated that the Tei index, the isovolumic relaxation time, pre-ejection period and the pre-ejection period-to-left ventricular ejection time ratio were able to identify the cardiotoxic effects of doxorubicin on cardiac function when only 60 mg/m² had been administered, while the standard systolic and diastolic parameters, including left ventricular diameter at systole, ejection fraction, and fractional shortening needed at least 120 mg/mg² to deteriorate. We concluded that prolonged anthracycline therapy compromises both systolic and diastolic functions, which may be documented earlier by including the Tei index evaluation to the standard echocardiographic assessment of animals receiving doxorubicin.

MG, Sousa; D, Paulino-Junior; JPE, Pascon; GB, Pereira-Neto; R, Carareto; AA, Camacho.

24

TEI INDEX MIGHT BE THE UNIQUE ECHOCARDIOGRAPHIC PARAMETER THAT DETECTS HYPERVISCOSITY SYNDROME: ACASE REPORT  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract: Hyperviscosity syndromes are disorders of infrequent prevalence in which changes of rheological characteristics cause increased resistance to blood flow, endothelial dysfunction, tissue ischemia and bleeding. Signs of hyperviscosity syndrome become clinically overt at the point of 4 centipoise units. We present a case of patient with hyperviscosity syndrome due to Waldenstrom’s macroglobulinemia with negative records on earlier cardiovascular illnesses. Laboratory diagnostic and standard echocardiography did not show any deviation towards increased cardiovascular risk, heart failure or ischemic heart disease. However, unique clinically significant change that could be indirectly related to hyperviscosity syndrome was found with the myocardium performance index (MPI. Tei-index showed median value of 0.75 corresponding to severe grades of myocardial dysfunction earlier described in the literature for other entities. Comprehensive roles of rheological changes in relation to echocardiography, pathophysiology of myocardial performance and cardiovascular continuum might be interesting point for further investigations.

Boban Marko

2013-12-01

25

Circle K Cycles: uma diáspora à brasileira na obra de Karen Tei Yamashita  

Directory of Open Access Journals (Sweden)

Full Text Available The intent of this work is to offer a discussion of diaspora, outlined by its consensual features found in the studies of theorists William Safran (1991, Khachig Tölölyan (1996, James Clifford (1994, Robin Cohen (1995, 1999, and Paul Gilroy (1999. Here we emphasize the need of a more accurate use of the term diaspora. Simultaneously, we analyze the fictional representation of a Brazilian diasporic formation in Circle K Cycles. In this book, by Japanese-American Karen Tei Yamashita, we identify and problematize diaspora through the means of some characteristics, such as the dispersion and its reasons, the relationship with the homeland, conflicts in the hostland, the myth of return and the ethnic group consciousness.

Cláudio Roberto Vieira Braga

2009-11-01

26

TEI Piraeus students' knowledge on the beneficial applications of nuclear physics: Nuclear energy, radioactivity - consequences  

CERN Multimedia

The recent nuclear accident in Japan revealed the confusion and the inadequate knowledge of the citizens about the issues of nuclear energy, nuclear applications, radioactivity and their consequences In this work we present the first results of an ongoing study which aims to evaluate the knowledge and the views of Greek undergraduate students on the above issues. A web based survey was conducted and 131 students from TEI Piraeus answered a multiple choice questionnaire with questions of general interest on nuclear energy, nuclear applications, radioactivity and their consequences. The survey showed that students, like the general population, have a series of faulty views on general interest nuclear issues. Furthermore, the first results indicate that our educational system is not so effective as source of information on these issues in comparison to the media and internet

Pilakouta, Mirofora

2011-01-01

27

Lung Cancer Attributable to Indoor Radon Exposures in Two Radon-Prone Areas, ?tei (Romania) and Torrelodones (Spain)  

Science.gov (United States)

Radon and radon progeny are present indoors, in houses and others dwellings, representing the most important contribution to dose from natural sources of radiation. Most studies have demonstrated an increased risk of lung cancer at high concentration of radon for both smokers and nonsmokers. For medium and low concentrations which are the typical residential radon levels, recent researches have also demonstrated increased risks of lung cancer for people exposed. The work presents a comparative analysis of the radon exposure data in the two radon-prone areas, ?tei, Transylvania, (Romania), in the near of old Romanian uranium mines and in the granitic area of Torrelodones town, Sierra de Guadarrama (Spain). One important difference between the two studied areas is related to the houses built using uranium waste as construction material in ?tei area. Measurements of indoor radon were performed in 280 dwellings (Romania) and 91 dwellings (Spain) by using nuclear track detectors, CR 39. The highest value measured in ?tei area was 2650 Bq.m-3. and 366 Bq.m-3 in the Spanish region. The results are compute with the BEIR VI report estimates using the age-duration model at an exposure rate below 2650 Bq.m-3. A total of 233 lung cancer deaths were calculated in the ?tei area for a period of 13 years (1994-2006), which is 116.82% higher than observed from the national statistics. In comparison, in Torrelodones area, a number of 276 deaths caused by lung cancer were estimated along a period of 13 years, which is 2.09 times higher than the number observed by authorities. This represents a significantly evidence that elevated risk can strongly be associated with cumulated radon exposure.

Dinu, Alexandra; Cosma, Constantin; Sainz, Carlos; Poncela, Luis Santiago Quindós; Vasiliniuc, ?tefan

2009-05-01

28

Basic doppler echocardiography  

Energy Technology Data Exchange (ETDEWEB)

This book contains 12 chapters. Some of the chapter titles are: An Introduction to Doppler; Pulsed and Continuous Wabe Doppler; The Doppler Examination; Doppler Evaluation of Valvular Regurgitation; Doppler Evaluation of Valvular Stenosis; and Pulsed Doppler Analysis of Human Fetal Blood Flow.

Kisslo, J.; Adams, D.; Mark, D.B.

1986-01-01

29

Doppler and the Doppler Effect.  

Science.gov (United States)

A summary is given of Doppler's life and career. He was born 180 years ago on 29 Nov 1803 in Salzburg, Austria. He died on 17 Mar 1853 in Venice. The effect bearing his name was first announced in a presentation before the Royal Bohemian Society of the Sc...

K. Toman

1984-01-01

30

Radon and remediation measures near B?i?a-?tei old uranium mine (Romania)  

Science.gov (United States)

B?i?a-?tei mine is an open pit mine in NW Romania (West Carpathian Mountains). It was the largest surface uranium deposit in the world. Two means of uranium transport and dissemination were used over time. The first was the natural way, represented by transportation of geological sediments by Cri?ul-B?i?a River that crosses the B?i?a surface deposit. These sediments were used as building materials (stone, gravel, sand). The second way was related to the people living in this valley, who used also the uranium waste as building material. The preliminary indoor radon concentrations measured in the buildings ranged from 40 to 4000 Bq m-3 with a mean value of 241 Bq m-3. A focused radon survey facilitated the selection of 20 houses with the highest indoor radon that were therefore proposed for remediation. To find the radon sources of these houses, systematic investigations on radon were performed. The remedial measures for these 20 houses were tested on a chosen pilot house.

Cosma, Constantin; Cuco?, Alexandra; Papp, Botond; Begy, Robert; Dicu, Tiberiu; Moldovan, Mircea; Tru??, Lucia Adina; Ni??, Dan Constantin; Burghele, Bety-Denissa; Suciu, Liviu; Sainz, Carlos

2013-08-01

31

Doppler flowmeter  

Science.gov (United States)

A Doppler flowmeter impulses an ultrasonic fixed-frequency signal obliquely into a slurry flowing in a pipe and a reflected signal is detected after having been scattered off of the slurry particles, whereby the shift in frequencies between the signals is proportional to the slurry velocity and hence slurry flow rate. This flowmeter filters the Doppler frequency-shift signal, compares the filtered and unfiltered shift signals in a divider to obtain a ratio, and then further compares this ratio against a preset fractional ratio. The flowmeter utilizes a voltage-to-frequency convertor to generate a pulsed signal having a determinable rate of repetition precisely proportional to the divergence of the ratios. The pulsed signal serves as the input control for a frequency-controlled low-pass filter, which provides thereby that the cutoff frequency of the filtered signal is known. The flowmeter provides a feedback control by minimizing the divergence. With the cutoff frequency and preset fractional ratio known, the slurry velocity and hence flow will also be determinable.

Karplus, Henry H. B. (Hinsdale, IL); Raptis, Apostolos C. (Downers Grove, IL)

1983-01-01

32

Progress in Doppler instrumentation  

International Nuclear Information System (INIS)

Much progress has been made during the past two decades in the development and use of Doppler ultrasound in medical diagnosis. Doppler instruments have proven to be sensitive to blood dynamics while remaining simple to use and readily available. Future Doppler devices should provide even more information and improved clinical accuracy

1984-01-01

33

The Junkyard in the Jungle: Transnational, Transnatural Nature in Karen Tei Yamashita’s Through the Arc of the Rain Forest  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In this new millennium the relatively young field of ecocriticism has had to face important transdisciplinary, transnational, and transnatural challenges. This article attempts to demonstrate how two of the major changes that environmental criticism is currently undergoing, the transnational turn and the transnatural challenge, have both been encoded in Through the Arc of the Rain Forest (1990), the first novel published by Karen Tei Yamashita. I particularly foc...

Begoña Simal

2010-01-01

34

Assessment of the left ventricular function in patients with rheumatic heart disease combining with quantitative tissue velocity imaging and Tei index  

International Nuclear Information System (INIS)

Objective: To evaluate the clinical value of quantitative tissue velocity imaging (QTVI) and Tei index in detecting left ventricle longitudinal myocardial systolic function in patients with rheumatic mitral stenosis. Methods: 34 patients with rheumatic mitral stenosis (MS) and 36 healthy volunteers were examined by QTVI. The systole peak motion velocity (Vs) of mitral annulus on septum, lateral wall, anterior wall, inferior wall, anterior septum and posterior wall was measured respectively. The interval period of mitral annulus motion was obtained and the Tei index was calculated. Results: The left ventricular ejection fractions (LVEF) was 64.9 ±7.01%, 68.0 ± 6.81% for MS group and the control group. There was no significant difference between the two groups (P>0.05). The systole peak motion velocity (Vs) of mitral annulus on septum, lateral wall, anterior wall, inferior wall, anterior septum and posterior wall was 4.07 ± 1.44 cm/s, 5.33 ±1.72 cm/s, 4.89 ±1.71 cm/s, 4.28 ±1.21 cm/s, 3.94 ± 1.46 cm/s, 5.19 ±1.81 cm/s respectively and average velocity (AV) of mitral valve annulus was 4.61 ± 1.62 cm/s in MS group. The systole peak motion velocity (Vs) of mitral annulus on septum, lateral wall, anterior wall, inferior wall, anterior septum and posterior wall was 6.11 ± 0.96 cm/s, 8.74 ±1.40 cm/s, 8.45 ±1.33 cm/s, 6.59 ± 0.94 cm/s, 6.01 ± 1.25 cm/s, 7.70 ±1.46 cm/s respectively and average velocity (AV) of mitral valve annulus was 7.27 ±1.63 cm/s in the control group. Compared with the control group, Vs and AV of mitral valve annulus is MS group decreased dramatically and had significant difference (P<0.01). Moreover, compared with Tei index of the control group (0.21 ±3.47), Tei index of the MS group (0.50 ±0.12) had greatly increased and had significant difference (P<0.01). Conclusion: Sub-clinical damage of systolic function of the left ventricle in patients with rheumatic mitral stenosis could not be detected by LVEF. Combined use QTVI and Tei index is more sensitive and effective to evaluate the systolic function of left ventricle longitudinal myocardial and the damage of general function of the left ventricle. (authors)

2011-08-01

35

Doppler Shift Target Localization  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This paper outlines the problem of doppler-based target position and velocity estimation using a sensor network. The minimum number of doppler shift measurements at distinct generic sensor positions to have a finite number of solutions, and later, a unique solution for the unknown target position and velocity is stated analytically. Furthermore, we study the same problem where not only doppler shift measurements are collected, but also other types of measurements are available, e.g. bearing o...

2013-01-01

36

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

1988-01-01

37

Doppler Optical Navigator.  

Science.gov (United States)

The objective of this program is to determine the feasibility of techniques leading to a Doppler optical navigator for measuring instantaneous ground speed with 0.1 ft/sec accuracy for altitudes of 250 to 5000 feet. Present microwave Doppler radars are li...

A. L. Pogoda J. T. LaTourrette S. Jarrett S. Jacobs

1964-01-01

38

The Doppler Pendulum Experiment  

Science.gov (United States)

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

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

2011-01-01

39

Doppler’s Effect, Gravity and Cosmology  

Directory of Open Access Journals (Sweden)

Full Text Available We first show that Doppler’s effect implies that the time runs identically in the frames of reference of the source of light and the observer. Furthermore, we then show that the frequency shift due to the (assumed expansion of space, if any, is “indistinguishable” from that due to the motion of the source with respect to the observer; and that the shift does not depend on the distance to the source. Observed frequency shifts of cosmological sources then need to be interpreted as being only due to their motions with respect to us. This has important implications for our ideas in cosmology.  

Sanjay M. Wagh

2013-08-01

40

Differential doppler heterodyning technique  

DEFF Research Database (Denmark)

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 detected doppler frequency. It is found that the doppler frequency for this particular setup is independent of the direction of detection. Investigations of the signal-to-noise ratio (SNR) show that the maximum SNR-considering the optical setup-is obtained by measuring the frequency difference between two doppler-shifted beams rather than by measuring the shift of a single beam by comparing it with a reference beam. Measurements seem to be in agreement with the theoretical consideration

Lading, Lars

1971-01-01

 
 
 
 
41

Right Ventricular Tissue Doppler Assessment in Space During Circulating Volume Modification using the Braslet-M Device  

Science.gov (United States)

This joint U.S. - Russian work aims to establish a methodology for assessing cardiac function in microgravity in association with manipulation of central circulating volume. Russian Braslet-M occlusion cuffs were used to temporarily increase the volume of blood in the lower extremities, which effectively reduces the volume returning to the heart in the central circulation. A novel methodology was tested on the International Space Station (ISS) to assess the volume status of crewmembers by evaluating the responses to application and release of the Braslet-on-occlusion cuffs, as well as to modified Valsalva and Mueller maneuvers. Baseline echocardiographic tissue Doppler imaging (TDI) of the right ventricular free wall with no Braslet applied shows early diastolic E' (16 cm/sec), late diastolic A' (14 cm/sec), and systolic (12 cm/sec) velocities compatible with normal subjects on Earth. TDI of the RV free wall with Braslet applied shows that early diastolic E' decreased by 50% (8 cm/sec), late diastolic A' increased by 45%, and systolic S' remains unchanged. TDI of the RV free wall approximately 8 beats after the Braslet was released shows early diastolic E' (8 cm/sec), late diastolic A' (12 cm/sec), and systolic S' (13 cm/sec) velocities. During this portion of the release, early diastolic E' did not recover to baseline values but late diastolic A' and systolic S' recovered to pre-Braslet values. The pre-systolic cross-sectional area of the internal jugular vein with Braslet off was 1.07 cm(sup 2) and 1.13 cm(sup 2) 10 min after the Braslet was applied. The presystolic cross-sectional area of the common femoral vein with Braslet off was 0.50 cm(sup 2), and was 0.54 cm(sup 2) 10 min after the Braslet was applied. The right ventricular myocardial performance Tei index also was calculated for comparison with typical values found in healthy subjects on Earth. Baseline and Braslet-on values for Tei index were 0.25 and 0.22 respectively. Braslet Tei indices are within normal ranges found in healthy subjects and temporarily become greater than 0.4 during the dynamic Braslet release portion of this study. Tissue Doppler imaging of the right ventricle revealed that the Braslet influenced cardiac preload and that fluid was sequestered in the lower-extremity interstitial and vascular space after only 10 minutes of application. This report demonstrates that Braslet application affects right ventricular physiology in long-duration space flight based on TDI and that this effect is in part due to venous hemodynamics.

Hamilton, D. R.; Sargsyan, A. E.; Fincke, E. M.; Magnus, S. H.; Lonchakov, Y. V.; Alferova, I. V.; Dulchavsky, S. A.; Ebert, D.; Garcia, K.; Martin, D.; Matveev, V. P.; Voronkov, Y. I.; Melton, S. L.; Duncan, J. M.; Bogomolov, V. V.

2009-01-01

42

Doppler Lidar (DL) Handbook  

Energy Technology Data Exchange (ETDEWEB)

The Doppler lidar (DL) is an active remote sensing instrument that provides range- and time-resolved measurements of radial velocity and attenuated backscatter. The principle of operation is similar to radar in that pulses of energy are transmitted into the atmosphere; the energy scattered back to the transceiver is collected and measured as a time-resolved signal. From the time delay between each outgoing transmitted pulse and the backscattered signal, the distance to the scatterer is inferred. The radial or line-of-sight velocity of the scatterers is determined from the Doppler frequency shift of the backscattered radiation. The DL uses a heterodyne detection technique in which the return signal is mixed with a reference laser beam (i.e., local oscillator) of known frequency. An onboard signal processing computer then determines the Doppler frequency shift from the spectra of the heterodyne signal. The energy content of the Doppler spectra can also be used to determine attenuated backscatter.

Newsom, RK

2012-02-13

43

Doppler Effect Applet  

Science.gov (United States)

This applet lets students interactively experience the Doppler effect. The user can adjust the position of an "observer" relative to the wave source (a jet plane), change the plane's speed, observe how the waveforms change in frequency and wavelength as the plane passes by the observer, and listen to the change in pitch of the sound. There are also links to additional information on the Doppler effect, the physics of sound, and other sound-based applets.

44

Doppler cooling a microsphere  

CERN Multimedia

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.

Barker, P F

2010-01-01

45

Doppler Effect Model  

Science.gov (United States)

The Doppler Effect model demonstrates the shift in frequency of a wave that is produced by the motion of either the wave source or the observer of the wave (or both). In this simulation, you can explore the change in the wave that is produced by source and/or observer motion, and you can even view what the situation looks like from the perspective of the medium (the standard reference frame), the source, or the observer. The Doppler Effect model was created using the Easy Java Simulations (EJS) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_bu_Doppler.jar file will run the program if Java is installed.

Duffy, Andrew

2010-04-25

46

Laser doppler spectroscopy  

International Nuclear Information System (INIS)

The main objects of this paper will be to review the latest developments in laser Doppler techniques as well as the results of cell electrophoretic studies. Although the first cell mobility measurements were done in physiological saline, it has not been until recently that high resolution Doppler measurements of cells in high salt conditions has become routine. This important technical advance has been due to improvements in electrode materials, electrophoresis chamber designs, and heterodyne optics. These topics are considered in detail in Section IV and Section V. In Section VI various laser Doppler approaches are compared with each other as well as with microscopic, free flow analytic, and density gradient techniques. Particle studies are reviewed in Section VII and blood cell studies in the remaining sections of the paper. (orig.)

1981-01-01

47

Comparisons between PW Doppler system and enhanced FM Doppler system  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This paper presents a new implementation of an echo-ranging FM Doppler system with improved performance, relative to the FM Doppler system reported previously. The use of long sweeps provides a significant reduction in peak to average power ratio compared to pulsed wave (PW) emission. A PW Doppler system exploits the direct relationship between arrival time of the received signal and range from the transducer. In the FM Doppler systems, a similar relationship exists in the spectral domain of ...

2010-01-01

48

Rotational Doppler Effect  

CERN Document Server

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 that of a stationary observer.

Halder, A

2002-01-01

49

Doppler ion program description  

Energy Technology Data Exchange (ETDEWEB)

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.

Henline, P.

1980-12-01

50

Pulse Doppler radar  

CERN Document Server

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

Alabaster, Clive

2012-01-01

51

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

1980-01-01

52

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 ?eV, even when the ultra-high energy resolution of ?E?0.03 ?eV is attained. (author)

2001-03-01

53

Ejs Doppler Effect Model  

Science.gov (United States)

The Ejs Doppler Effect model displays the detection of sound waves from a moving source and the change in frequency of the detected wave via the Doppler effect. In addition to the wave fronts from the source a graph depicting the time of emission and time of detection of each of the wave fronts is given. The speed of sound, the velocity of the source and the position and velocity of the detector can be changed via text boxes. You can modify this simulation if you have Ejs installed by right-clicking within the plot and selecting âOpen Ejs Modelâ from the pop-up menu item. Ejs Doppler Effect model was created using the Easy Java Simulations (Ejs) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_ehu_waves_doppler.jar file will run the program if Java is installed. Ejs is a part of the Open Source Physics Project and is designed to make it easier to access, modify, and generate computer models. Additional Ejs models for wave optics are available. They can be found by searching ComPADRE for Open Source Physics, OSP, or Ejs.

Aguirregabiria, Juan

2008-08-20

54

Doppler Free Laser Spectroscopy  

Science.gov (United States)

In this experiment you will use a technique known as saturation-absorption spectroscopy to study the hyperfine structure (hfs) of rubidium. This particular method is designed to overcome the limitations imposed by the Doppler-broadening of spectral lines while avoiding the need to work at low temperatures.

2012-01-09

55

Automated measurement of fetal myocardial performance index in ultrasound Doppler waveforms  

Science.gov (United States)

We introduce an automated method for myocardial performance index (MPI), also known as Tei index, which is one of the most substantial indicators in the early screening of heart defects. Since assessing fetal cardiac functions using MPI has become a routine and significant process, there have been explicit requirements to automate MPI measurements. Due to small heart sizes of fetuses, we focus on the automation of modified MPI (Mod-MPI) which uses a single Doppler gate. The proposed method detects four valve click signals in Doppler waveforms using four image features which are extracted by vertical projection of Doppler waveforms after several transformations. To evaluate performance, 88 of fetal examinations were collected from a commercial ultrasound machine, and two clinical experts measured the Mod-MPI both manually and automatically. Quantitative comparisons based on intra-class correlation coefficients (ICC) yield that intra-observer reproducibility is higher when performing the proposed method (ICC=0.951 and 0.932 for observer 1 and 2) comparing to those of manual measurements (ICC=0.868 and 0.857 for observer 1 and observer 2). Thus, our method (ICC=0.962) reveals superior inter-observer reproducibility than that of manual method (ICC=0.597). Although mean difference from observer 2 (-0.062) is over three times larger than that of observer 1 (-0.018) due to different experiences, both of mean differences are acceptable. In conclusion, the proposed MPI measurement method can improve intra- and inter-reproducibility while providing reliable results.

Yoon, Heechul; Lee, Hyuntaek; Jeon, Kang-Won; Jung, Haekyung; Lee, Mi-Young; Won, Hye-Sung; Jeon, Eun-Jin; Yang, Eun-Ho; Choi, Jin-Young; Hong, Soon-Jae

2014-03-01

56

Quantitative Laser Doppler Flowmetry  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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...

2009-01-01

57

Doppler Radar Technology  

Science.gov (United States)

This resource provides an introduction to the function and uses of the The National Weather Service's (NWS) Weather Surveillance Doppler Radar (WSR-88D). Topics include the components of the system, an overview of the products and overlays the system creates, and some example images with captions explaining what is being shown. There are also links to radar meteorology tutorials and to information on training to use the system and interpret its imagery.

58

Holographic laser Doppler ophthalmoscopy  

CERN Document Server

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.

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

2010-01-01

59

Estudo Doppler na hipertensão portal Doppler evaluation in portal hypertension  

Directory of Open Access Journals (Sweden)

Full Text Available A ultra-sonografia e o Doppler representaram grande marco no diagnóstico da hipertensão portal. Este fato decorre do aspecto não-invasivo destes métodos, possibilitando o estudo do fígado, do baço e da circulação esplâncnica. Neste artigo os autores discutem alguns aspectos importantes avaliados pela ultra-sonografia e pelo Doppler na avaliação da hipertensão portal.Ultrasonography and Doppler ultrasonography have dramatically improved the diagnosis of portal hypertension thanks to the noninvasive visualization of the liver, spleen and splanchnic blood flow. In this article the authors discuss some important issues raised by the use of ultrasound and Doppler in the evaluation of portal hypertension.

Márcio Martins Machado

2004-02-01

60

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 ?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

1992-01-01

 
 
 
 
61

STEM Colorado: Doppler Shift  

Science.gov (United States)

This applet demonstrates the Doppler shift. The user can control the frequency of the sound source and the sound speed. The chart recorder at the bottom displays the wave crests as detected by the receiver and their frequency. It also displays the instantaneous wavelength if the ear is at rest. The user can drag the source or the receiver to any location in the display and choose the velocity of each. This is part of a larger collection of applets by STEM Colorado focused mostly on topics in astronomy.

Mccray, Richard; Koelemay, Andrew

2008-08-30

62

The Michelson Doppler Imager  

Science.gov (United States)

A joint effort of the Solar Oscillations Investigations (SOI) at Stanford University and the Lockheed-Martin Advanced Technology Center, the Michelson Doppler Imager (MDI) is aboard the Solar and Heliospheric Observatory (SOHO) spacecraft and assists in collecting data of the interior structure and dynamics of the sun. Users can find information on the instrument observable and the nature of the observing programs. The website provides MDI press releases, summary results, dissertations, preprints, and other documentation. Researchers can find daily magnetograms, synoptic charts, calibrated data, and many other archived data products.

63

Comparisons between PW Doppler system and enhanced FM Doppler system  

DEFF Research Database (Denmark)

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

Wilhjelm, Jens E.

1995-01-01

64

Diagnostyka zmian w sercu u dzieci z twardzin? – rola echokardiografii z uwzgl?dnieniem globalnego wska?nika funkcji mechanicznej lewej komory (Tei index  

Directory of Open Access Journals (Sweden)

Full Text Available Wprowadzenie: Cz?sto?? wyst?powania zmian w sercu u dzieci z twardzin? i mo?liwo?ci ich wczesnego wykrywania pozostaj? otwartym problemem klinicznym. Cel pracy: Ocena przydatno?ci echokardiografii w wykrywaniu zaburze? czynno?ci serca u dzieci z twardzin?. Materia? i metodyka: Zbadano 20 dzieci z twardzin? ograniczon? (TO w wieku 13,1±;4,2 lat oraz 20 dzieci z twardzin? uogólnion? (TU w wieku 13,6±;2,9 lat, bez klinicznych cech choroby serca. Grup? kontroln? (GK stanowi?o 20 zdrowych dzieci w wieku 13,8±;2,7 lat. U wszystkich wykonano echo 2D, M-mode i badanie dopplerowskie oraz oznaczono parametry funkcji skurczowej i rozkurczowej lewej komory (LK, w tym globalny wska?nik sprawno?ci mechanicznej LK (Tei index, wyra?ony jako suma czasu skurczu (ICT i rozkurczu izowolumetrycznego (IVRT podzielona przez czas wyrzutu z lewej komory (ET. Wyniki: Frakcja wyrzutowa LK dla TO, TU i GK wynios?a odpowiednio: 70±;10, 71±;9 i 71±;5%; p=ns. Warto?? E/A (stosunek pr?dko?ci nap?ywu do LK w fazie komorowej i przedsionkowej wynios?a 1,59±;0,3 dla TO i 1,58±;0,3 dla TU i by?a istotnie ni?sza w porównaniu z GK: 1,85±;0,3, p<0,01. Warto?? ICT dla TO wynios?a 65±;11 ms, a dla TU 64±;11 ms i by?a istotnie wy?sza w porównaniu z GK: 52±;9 ms; p<0,05. Czas IVRT by? znamiennie d?u?szy dla TO ni? dla GK: 80±;12 ms vs 69±;9 ms; p<0,05. Czas ET by? istotnie krótszy dla TU ni? dla GK: 253±;23 ms vs 271±;16 ms; p<0,05. Warto?? wska?nika Tei zarówno dla TO, jak i TU wynios?a 0,55±;0,1 i by?a istotnie wy?sza w porównaniu z GK: 0,44±;0,1, p<0,05 Wnioski: Analiza parametrów echokardiograficznych pozwala na wczesne wykrywanie zaburze? funkcji mechanicznej lewej komory u dzieci zarówno z twardzin? uogólnion?, jak i ograniczon?, bez klinicznie jawnych objawów choroby serca.

Bohdan Firek

2004-03-01

65

Segmenting Intracellular Distribution Images Derived by Fluorescent Dyes Using a Potts Model Hamiltonian  

CERN Document Server

We apply a multiresolution community detection algorithm to perform unsupervised segmentation of complex intracellular signals derived using fluorescent dyes. In our earlier work, when applying our method to benchmarks, our algorithm was shown to be one of the best and to be especially suited to the detection of camouflage images. In the current manuscript, we have explored this algorithm in a more complex scenario. The current image processing problem is framed as identifying clusters with respective average fluorescent lifetimes (FLTs) against a background or "solvent" in fluorescence lifetime imaging microscopy (FLIM) images derived using NIR fluorescent dyes. We have identified significant multiresolution structures using replica correlations in these images, where such correlations are manifested by information theoretic overlaps of the independent solutions ("replicas") attained using the proposed algorithm from different starting points. Our method is more efficient than a well-known image segmentation...

Hu, Dandan; Ronhovde, Peter; Bloch, Sharon; Achilefu, Samuel; Nussinov, Zohar

2012-01-01

66

The Junkyard in the Jungle: Transnational, Transnatural Nature in Karen Tei Yamashita’s Through the Arc of the Rain Forest  

Directory of Open Access Journals (Sweden)

Full Text Available

In this new millennium the relatively young field of ecocriticism has had to face important transdisciplinary, transnational, and transnatural challenges. This article attempts to demonstrate how two of the major changes that environmental criticism is currently undergoing, the transnational turn and the transnatural challenge, have both been encoded in Through the Arc of the Rain Forest (1990, the first novel published by Karen Tei Yamashita. I particularly focus on a significant episode in Through the Arc of the Rain Forest, when a peculiar anthropogenic ecosystem is discovered, and interpret it according to Leo Marx’s classic paradigm of “the machine in the garden.” I intend to prove that Yamashita’s novel not only revisits the old master theory but also revamps it by destabilizing the classic human-nature divide inherent in first-wave ecocriticism and by adding the transnational ingredient. Thus, the machine-in-the-garden paradigm is updated in order to incorporate the broadening of current environmental criticism, both literally (globalization and conceptually (transnatural nature. While at times Marx’s paradigm may metamorphose in intriguing ways, the old trope also corroborates its continuing validity. Though filtered by the sieve of globalization and shaken by the emergence of cyborg ecosystems, “the machine in the garden” has survived as a compelling ecocritical framework, even if it occasionally mutates into a junkyard in the jungle.

Begoña Simal

2010-03-01

67

Transversal Doppler-Fizeau effect  

International Nuclear Information System (INIS)

The relativistic calculation of the Doppler-Fizeau effect foresees a second grade redshift due to the proper time dilation of a moving object. The relevance of this relativistic effect on astrophysical observation is discussed, herein. (Auhor)

1981-01-01

68

Doppler characteristics of sea clutter.  

Energy Technology Data Exchange (ETDEWEB)

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

Raynal, Ann Marie; Doerry, Armin Walter

2010-06-01

69

Glare Spot Phase Doppler Anemometry  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The Phase Doppler anemometry has been developed to measure simultaneously the velocity and the size of droplets. The measurement of the refractive index is also necessary since it depends on the temperature and the composition of the particle and its measurement permits both to increase the quality of the diameter measurement and to obtain information on the temperature and/or the composition of the droplets. In this paper, we introduce a Glare Spot Phase Doppler Anemometry which uses two lar...

Hespel, Camille; Ren, Kuan Fang; Gre?han, Ge?rard; Onofri, Fabrice

2007-01-01

70

Laser Doppler Imaging of Microflow  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We report a pilot study with a wide-field laser Doppler detection scheme used to perform laser Doppler anemometry and imaging of particle seeded microflow. The optical field carrying the local scatterers (particles) dynamic state, as a consequence of momentum transfer at each scattering event, is analyzed in the temporal frequencies domain. The setup is based on heterodyne digital holography, which is used to map the scattered field in the object plane at a tunable frequency with a multipixel...

2006-01-01

71

Airborne Doppler lidar activities  

Science.gov (United States)

During August and September 1984, 20 research flights were conducted by the CV990 with airborne doppler lidar installed. Nine of these flights were dedicated to the Lidar project. Excellent data were obtained in the Carquenez Strait downwind of San Francisco Bay, showing the divergence of the flow as it passes into the Central Valley. The data clearly show the horizontal and vertical structure of the wind flow in the pass region and adjoining parts of the Central Valley. Data were also obtained in the vicinity of Mount Shasta in northern California, showing the flow in the lee of the isolated mountain. Preliminary analyses of these flights using the McIdas interactive graphics system have been accomplished, and procurements have been initiated for detailed scientific analyses. A partial failure of a crucial optical component resulted in contamination of a portion of the wind data that were obtained in the Mount Shasta and subsequent flights. Analyses are underway to attempt reconstruction of the data to minimize the effects of the failure. Data were obtained in conjunction with a microwave wind profiler at Penn State University. It is expected that data reconstruction will be of use in this case. Procurement has been initiated for scientific analyses of these results. The improved airborne Lidar system performed well. In most of the research flights a large number of different scan angles were used to obtain the vertical structure of the wind fields being investigated.

Fitzjarrald, D. R.; Bilbro, J. W.

1985-01-01

72

Adaptive Spectral Doppler Estimation  

DEFF Research Database (Denmark)

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 (Welchâ??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 matched filters (one for each veloc- ity component of interest) and filtering the blood process over slow-time and averaging over depth to find the PSD. The methods are tested using various experiments and simulations. First, controlled flow-rig experiments with steady laminar flow are carried out. Simulations in Field II for pul- sating flow resembling the femoral artery are also analyzed. The simulations are followed by in vivo measurement on the common carotid artery. In all simulations and experiments it was concluded that the adaptive methods display superior per- formance for short observation windows compared with the averaged periodogram. Computational costs and implementation details are also discussed.

Gran, Fredrik; Jakobsson, Andreas

2009-01-01

73

Study of an image-derived SUV and a modified SUV using mouse FDG-PET  

Energy Technology Data Exchange (ETDEWEB)

Introduction: Standard uptake value (SUV) is calculated without consideration of the differences in plasma 2-deoxy-2-[18F]fluoro-D-glucose (FDG) clearance. Its variability can be affected by changes of the amount of excreted FDG by renal function. Moreover, the estimation of SUV is quite sensitive to errors in the measurements of body weight and injected dose. This study aims to develop an image-based method to obtain an image-derived SUV (iSUV) and a modified SUV (mSUV) to overcome these problems. Methods: Thirty-one tumor-planted SCID mice were scanned in micro-positron emission tomography (PET) at {approx}60 min post FDG injection and then scanned in micro-computed tomographic (CT). Using image-based method, the body weight and injected dose were derived from the microPET/CT images to calculate iSUV. The volumes and the total activities of FDG within the bladder and the whole-body were also obtained to calculate mSUV. For the selected targets, the iSUVs and mSUVs were compared against their corresponding SUVs. Results: Compared with SUV factor (injected dose/body weight), iSUV factor had an average percentage error of -0.7%. The linear regressions between SUV and iSUV had a slope of 0.99 with correlation coefficient of 0.95. Compared with SUV and iSUV, coefficient of variation of mSUV decreased while the tumor-to-background separation of mSUV increased. Conclusions: Using this image-based method, the iSUV can replace SUV when the actual measurements were missing or unreliable. The mSUV can reduce the inter-subject variability and enhance the tumor-to-background separation in mouse FDG-PET studies.

Zheng Xiujuan, E-mail: zhengxj@eie.polyu.edu.h [Department of Electronic Information Engineering, the Hong Kong Polytechnic University, Hung Hom, Kowloon (Hong Kong); Yu, Chin-Lung; Sha Wei; Radu, Caius; Huang, Sung-Cheng [Department of Molecular and Medical Pharmacology, David Geffen School of Medicine at UCLA, University of California Los Angeles, CA (United States); Feng Dagan [Department of Electronic Information Engineering, the Hong Kong Polytechnic University, Hung Hom, Kowloon (Hong Kong); School of Information Technologies, the University of Sydney, Sydney (Australia)

2011-04-15

74

Glioma grade assessment by using histogram analysis of diffusion tensor imaging-derived maps  

International Nuclear Information System (INIS)

Current endeavors in neuro-oncology include morphological validation of imaging methods by histology, including molecular and immunohistochemical techniques. Diffusion tensor imaging (DTI) is an up-to-date methodology of intracranial diagnostics that has gained importance in studies of neoplasia. Our aim was to assess the feasibility of discriminant analysis applied to histograms of preoperative diffusion tensor imaging-derived images for the prediction of glioma grade validated by histomorphology. Tumors of 40 consecutive patients included 13 grade II astrocytomas, seven oligoastrocytomas, six grade II oligodendrogliomas, three grade III oligoastrocytomas, and 11 glioblastoma multiformes. Preoperative DTI data comprised: unweighted (B0) images, fractional anisotropy, longitudinal and radial diffusivity maps, directionally averaged diffusion-weighted imaging, and trace images. Sampling consisted of generating histograms for gross tumor volumes; 25 histogram bins per scalar map were calculated. The histogram bins that allowed the most precise determination of low-grade (LG) or high-grade (HG) classification were selected by multivariate discriminant analysis. Accuracy of the model was defined by the success rate of the leave-one-out cross-validation. Statistical descriptors of voxel value distribution did not differ between LG and HG tumors and did not allow classification. The histogram model had 88.5% specificity and 85.7% sensitivity in the separation of LG and HG gliomas; specificity was improved when cases with oligodendroglial components were omitted. Constructing histograms of preoperative radiological images over the tumor volume allows representation of the grade and enables discrimination of LG and HG gliomas which has been confirmed by histopathology. (orig.)

2011-07-01

75

Glioma grade assessment by using histogram analysis of diffusion tensor imaging-derived maps  

Energy Technology Data Exchange (ETDEWEB)

Current endeavors in neuro-oncology include morphological validation of imaging methods by histology, including molecular and immunohistochemical techniques. Diffusion tensor imaging (DTI) is an up-to-date methodology of intracranial diagnostics that has gained importance in studies of neoplasia. Our aim was to assess the feasibility of discriminant analysis applied to histograms of preoperative diffusion tensor imaging-derived images for the prediction of glioma grade validated by histomorphology. Tumors of 40 consecutive patients included 13 grade II astrocytomas, seven oligoastrocytomas, six grade II oligodendrogliomas, three grade III oligoastrocytomas, and 11 glioblastoma multiformes. Preoperative DTI data comprised: unweighted (B{sub 0}) images, fractional anisotropy, longitudinal and radial diffusivity maps, directionally averaged diffusion-weighted imaging, and trace images. Sampling consisted of generating histograms for gross tumor volumes; 25 histogram bins per scalar map were calculated. The histogram bins that allowed the most precise determination of low-grade (LG) or high-grade (HG) classification were selected by multivariate discriminant analysis. Accuracy of the model was defined by the success rate of the leave-one-out cross-validation. Statistical descriptors of voxel value distribution did not differ between LG and HG tumors and did not allow classification. The histogram model had 88.5% specificity and 85.7% sensitivity in the separation of LG and HG gliomas; specificity was improved when cases with oligodendroglial components were omitted. Constructing histograms of preoperative radiological images over the tumor volume allows representation of the grade and enables discrimination of LG and HG gliomas which has been confirmed by histopathology. (orig.)

Jakab, Andras; Berenyi, Ervin [University of Debrecen Medical and Health Science Center, Department of Biomedical Laboratory and Imaging Science, Faculty of Medicine, Debrecen (Hungary); Molnar, Peter [University of Debrecen Medical and Health Science Center, Institute of Pathology, Faculty of Medicine, Debrecen (Hungary); Emri, Miklos [University of Debrecen Medical and Health Science Center, Institute of Nuclear Medicine, Faculty of Medicine, Debrecen (Hungary)

2011-07-15

76

Image-derived input function obtained in a 3TMR-brainPET  

International Nuclear Information System (INIS)

Aim: The combination of a high-resolution MR-compatible BrainPET insert operated within a 3 T MAGNETOM Trio MR scanner is an excellent tool for obtaining an image derived input function (IDIF), due to simultaneous imaging. In this work, we explore the possibility of obtaining an IDIF from volumes of interest (VOI) defined over the carotid arteries (CAs) using the MR data. Material and methods: FDG data from three patients without brain disorders were included. VOIs were drawn bilaterally over the CAs on a MPRAGE image using a 50% isocontour (MR50VOI). CA PET/MR co-registration was examined based on an individual and combined CA co-registration. After that, to estimate the IDIF, the MR50VOI average (IDIF-A), four hottest pixels per plane (IDIF-4H) and four hottest pixels in VOI (IDIF-4V) were considered. A model-based correction for residual partial volume effects involving venous blood samples was applied, from which partial volume (PV) and spillover (SP) coefficients were estimated. Additionally, a theoretical PV coefficient (PVt) was calculated based on MR50VOI. Results: The results show an excellent co-registration between the MR and PET, with an area under the curve ratio between both co-registration methods of 1.00±0.04. A good agreement between PV and PVt was found for IDIF-A, with PV of 0.39±0.06 and PVt 0.40±0.03, and for IDIF-4H, with PV of 0.47±0.05 and PVt 0.47±0.03. The SPs were 0.20±0.03 and 0.21±0.03 for IDIF-A and IDIF-4H, respectively. Conclusion: The integration of a high resolution BrainPET in an MR scanner allows to obtain an IDIF from an MR-based VOI. This must be corrected for a residual partial volume effect

2013-02-21

77

Correlation between the Quantifiable Parameters of Whole Solitary Pulmonary Nodules Perfusion Imaging Derived with Dynamic CT and Nodules Size  

Directory of Open Access Journals (Sweden)

Full Text Available Background and objective The solitary pulmonary nodules (SPNs is one of the most common findings on chest radiographs. The blood flow patterns of the biggest single SPNs level has been studied. This assessment may be only a limited sample of the entire region of interest (ROI and is unrepresentative of the SPNs as a volume. Ideally, SPNs volume perfusion should be measured. The aim of this study is to evaluate the correlation between the quantifiableparameters of SPNs volume perfusion imaging derived with 16-slice spiral CT and 64-slice spiral CT and nodules size. Methods Sixty-five patients with SPNs (diameter?3 cm; 42 malignant; 12 active inflammatory; 11 benign underwent multi-location dynamic contrast material-enhanced serial CT scanning mode with stable table were performed; The mean values of valid sections were calculated, as the quantifiable parameters of volume SPNs perfusion imaging derived with16-slice spiral CT and 64-slice spiral CT. The correlation between the quantifiable parameters of SPNs volume perfusion imaging derived with 16-slice spiral CT and 64-slice spiral CT and nodules size were assessed by means of linear regression analysis. Results No significant correlations were found between the nodules size and each of the peak height (PHSPN (32.15 Hu±14.55 Hu?ratio of peak height of the SPN to that of the aorta (SPN-to-A ratio(13.20±6.18%, perfusion(PSPN (29.79±19.12 mLmin-1100 g-1 and mean transit time (12.95±6.53 s (r =0.081, P =0.419; r =0.089, P =0.487; r =0.167, P =0.077; r =0.023, P =0.880. Conclusion No significant correlations were found between the quantifiable parameters of SPNs volume perfusion imaging derived with 16-slice spiral CT and 64-slice spiral CT and nodules size.

Shiyuan LIU

2009-05-01

78

Differential Doppler as a diagnostic  

Energy Technology Data Exchange (ETDEWEB)

Differential Doppler compression and travel time of individual peaks in the arrival sequence (relative to an overall average) are measured for the 5500-km acoustic transmissions from a moving source at Heard Island to Christmas (Crab) Island. The differentials cannot be explained by simple adiabatic propagation models. A hybrid theory, coupling polar and temperate models at the Antarctic Front can account for some of the qualitative features. Differential Doppler could be a useful tool for identifying ray arrivals. 10 refs., 11 figs., 3 tabs.

Dzieciuch, M.; Munk, W. (Univ. of California, La Jolla, CA (United States))

1994-10-01

79

Doppler peaks from active perturbations  

CERN Document Server

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

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

1995-01-01

80

Estimation of Doppler Shift and Differential Doppler Shift.  

Science.gov (United States)

This report is concerned with the measurement of frequency (Doppler shift) by a collection of sensors which may be grouped into two or more clusters (subarrays). The signal may be a sinusoid, or it may be a narrowband gaussian process whose center frequen...

P. M. Schultheiss

1977-01-01

 
 
 
 
81

Duplex/doppler ultrasound test (image)  

Science.gov (United States)

The duplex/doppler ultrasound test examines the blood flow in the major arteries and veins in the arms and legs. The ... duplex ultrasonagraphy to visualize the blood flow and doppler ultrasonagraphy provides an audio means to hear the ...

82

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

1999-03-01

83

Pulsed Phase Shifter Improves Doppler Radar  

Science.gov (United States)

Ability of microwave Doppler radar to measure velocity of slow moving nearby target is enhanced by pulsed 90 degrees phase shifter in radar transmission line between circulator and antenna. Because of phase shifting, Doppler frequency is detected as modulation on carrier instead of baseband signal. Carrier is amplified and filtered before demodulation, resulting in strong, clean demodulated Doppler for measurement and display.

Kobayashi, H. S.; Shores, P. W.; Rozas, P.

1982-01-01

84

Doppler broadening of cross sections  

International Nuclear Information System (INIS)

Expressions for temperature dependent cross-sections in terms of resonance parameters are obtained, involving generalisations of the conventional Doppler functions, ? and ?. Descriptions of Fortran sub-routines, which calculate broadened cross-sections in accordance with the derived formulae, are included. (author)

1962-01-01

85

Doppler Shift in a Plasma.  

Science.gov (United States)

It is first shown that the ideal electron plasma (presence of protons neglected) is unique among all dispersive media in that it does not distinguish any inertial frame of reference in terms of utility. The theory of the Doppler shift in an ideal plasma i...

B. Manz

1968-01-01

86

Computer Analysis of Doppler Signals  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The paper presents solutions used to proccesa sonogram, which it is determined with accuracy atthe start of the new heart cycle.The device aplication performances are based ona simple non-directional CW Doppler unit and itscapabilities to interconect with a computer over aninterface.

2011-01-01

87

Human polarimetric micro-doppler  

Science.gov (United States)

Modern radars can pick up target motions other than just the principle target Doppler; they pick out the small micro-Doppler variations as well. These can be used to visually identify both the target type as well as the target activity. We model and measure some of the micro-Doppler motions that are amenable to polarimetric measurement. Understanding the capabilities and limitations of radar systems that utilize micro-Doppler to measure human characteristics is important for improving the effectiveness of these systems at securing areas. In security applications one would like to observe humans unobtrusively and without privacy issues, which make radar an effective approach. In this paper we focus on the characteristics of radar systems designed for the estimation of human motion for the determination of whether someone is loaded. Radar can be used to measure the direction, distance, and radial velocity of a walking person as a function of time. Detailed radar processing can reveal more characteristics of the walking human. The parts of the human body do not move with constant radial velocity; the small micro-Doppler signatures are timevarying and therefore analysis techniques can be used to obtain more characteristics. Looking for modulations of the radar return from arms, legs, and even body sway are being assessed by researchers. We analyze these techniques and focus on the improved performance that fully polarimetric radar techniques can add. We perform simulations and fully polarimetric measurements of the varying micro-Doppler signatures of humans as a function of elevation angle and azimuthal angle in order to try to optimize this type of system for the detection of arm motion, especially for the determination of whether someone is carrying something in their arms. The arm is often bent at the elbow, providing a surface similar to a dihedral. This is distinct from the more planar surfaces of the body and allows us to separate the signals from the arm (and knee) motion from the rest of the body. The double-bounce can be measured in polarimetric radar data by measuring the phase difference between HH and VV. Additionally, the cross-pol and co-pol Doppler signatures are analyzed, showing that the HH polarization may perform better on dismounts in open grass.

Tahmoush, David; Silvious, Jerry

2011-05-01

88

The micro-doppler effect in radar  

CERN Document Server

This highly practical resource provides you with thorough working knowledge of the micro-Doppler effect in radar, including its principles, applications and implementation with MATLAB codes. The book presents code for simulating radar backscattering from targets with various motions, generating micro-Doppler signatures, and analyzing the characteristics of targets. You find detailed descriptions of the physics and mathematics of the Doppler and micro-Doppler effect. Moreover, you learn how to derive rigid and non-rigid body motion induced micro-Doppler effect in radar scattering. The book prov

Chen, Victor

2011-01-01

89

Spatial weighting of Doppler reactivity feedback  

International Nuclear Information System (INIS)

The spatial weighting of the local Doppler feedback implicit in the determination of the core Doppler feedback reactivity has been investigated. Using a detailed planar PDQ7-II PWR model with local fuel-temperature feedback, the core Doppler spatial weight factor, S, has been determined for various control patterns and power levels. Assuming power-squared weighting of the local Doppler feedback, a simple analytic expression for S has been derived and, based on comparison with the PDQ7-II results, provides a convenient and accurate representation of the Doppler spatial weight factor. The sensitivity of these results to variations in the fuel rod heat transfer coefficients, fuel loading and the magnitude of the Doppler coefficient has also been evaluated. The dependence of the local Doppler coefficient on moderator temperature, boron concentration and control rod density has been determined and found to be weak. Selected comparisons with vendor analyses have been made and indicate general agreement

1977-01-01

90

Analysis of Doppler lidar data  

Science.gov (United States)

Dual Doppler lidar analyses of data taken by pulsed lidars demonstrated feasibility of deriving wind fields from coordinated lidar scans. Limited case histories of thunderstorm outflows were obtained. Co-located comparison between Marshall Space Flight Center lidar and NCAR 5.5 cm radar demonstrated desirability of lidar in cases of marginal radar reflectivity in clear air and low-elevation scans. Analysis continued on backscattered intensity and velocity measurements made from April 1983 to February 1984. A slant path method was used to calculate vertical profiles of volumetric backscatter and adsorption in the lower troposphere. High-quality VAD scans were identified as candidates for investigating feasibility of calculating horizontal motion fields using single Doppler lidar. Activities during FY-85 also included participation in Fall 1984 airborne Doppler lidar flight experiments. Preliminary data review was begun using McIdas system. Analysis of backscatter and absorpiton profiles continues. Focus is on understanding spatial and temporal variations, as well as frequency distribution, of backscatter at several tropospheric levels. Results from this study provide input to evaluation of clean/dirty airmass hypothesis of aerosol distribution. Assistance is being given to preparation of a comprehensive, global backscatter measurement plan. Analysis of data from Fall 1984 flight experiments is just beginning. Work has begun on preprocessing data to minimize errors due to electro-optic modulator malfunction during flights.

Rothermel, J.

1985-01-01

91

Avaliação dos tumores hepáticos ao Doppler Doppler evaluation of liver tumors  

Directory of Open Access Journals (Sweden)

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

Márcio Martins Machado

2004-10-01

92

Role of transcranial Doppler ultrasonography in stroke  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Transcranial Doppler sonongraphy is a non?invasive, non?ionising, inexpensive, portable and safe technique that uses a pulsed Doppler transducer for assessment of intracerebral blood flow. This article deals with the principles and technique of transcranial Doppler sonography. It gives a brief overview of its use in evaluation of intracranial steno?occlusive disease, subarachnoid haemorrhage, and extracranial diseases (including carotid artery disease and subclavian steal syndrome). The...

Sarkar, Sanjukta; Ghosh, Sujoy; Ghosh, Sandip Kumar; Collier, Andrew

2007-01-01

93

Mapping of airborne Doppler radar data  

Energy Technology Data Exchange (ETDEWEB)

Two sets of equations are derived to (1) map airborne Doppler radar data from an aircraft-relative coordinate system to an earth-relative coordinate system, and (2) remove the platform motion from the observed Doppler velocities. These equations can be applied to data collected by the National Oceanic and Atmospheric Administration WP-3D system, the National Center for Atmospheric Research Electra Doppler Radar (ELDORA) system, and other airborne radar systems.

Lee, W.; Dodge, P.; Marks, F.D. Jr.; Hildebrand, P.H. (National Center for Atmospheric Research, Boulder, CO (United States) NOAA, Miami, FL (United States))

1994-04-01

94

Detection of microemboli by transcranial Doppler ultrasound.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Doppler ultrasound detection of abnormally high-pitched signals within the arterial waveform offers a new method for diagnosis, and potentially for prediction, of embolic complications in at-risk patients. The nature of Doppler "microembolic" signals is of particular interest in patients with prosthetic heart valves, where a high prevalence of these signals is observed. Monitoring the middle cerebral artery with 2-MHz transcranial Doppler ultrasound (TC-2000, Nicolet Biomedical; Warwick, UK),...

Grosset, D. G.; Georgiadis, D.; Kelman, A. W.; Cowburn, P.; Stirling, S.; Lees, K. R.; Faichney, A.; Mallinson, A.; Quin, R.; Bone, I.; Pettigrew, L.; Brodie, E.; Mackay, T.; Wheatley, D. J.

1996-01-01

95

Doppler-free many photon spectroscopy  

International Nuclear Information System (INIS)

The probability of two-photon transitions is discussed. The experiments in Doppler-free many photon spectroscopy such as: light shift, evaluation of very narrow level structures, splitting in weak electric and magnetic fields, isotopic shift, pressure broadening and line shift at low pressures, selective population of one level in a system of closely situated levels (below Doppler width) and Doppler-free three-photon transitions are shortly described. (A.S.)

1980-01-01

96

Direct Doppler auscultation of the carotid arteries  

International Nuclear Information System (INIS)

The results of the carotid Doppler examinations and contrast arteriograms are presented. The overall sensitivity of the carotid Doppler examinations in detecting severe stenosis or occlusion of the carotid artery was 92%. The Doppler studies correctly differentiated these two conditions in 84% of the diseased vessels. In carotid arteries with stenosis greater than or equal to 50%, the sensitivity of the Doppler examinations was 90%, and these studies suggested stenosis in all but two of the 36 abnormal examinations. In two patent carotids with greater than 90% stenosis, a signal could not be elicited, presumably because of the low blood flow through the severely stenotic segment

1984-01-01

97

Extrapolation of small sample Doppler reactivity measurements  

International Nuclear Information System (INIS)

An application of 238U small sample Doppler measurements to the confirmation of LMFBR design calculations is proposed. The method uses the Doppler measurements in conjunction with 238U(n,#betta#) data to predict the radial behavior of the Doppler reactivity C/E, and includes a description of azimuthal variations by using the measured values to normalize a calculated map. The result is a spatial map which can be used, along with data from the SEFOR experiments, to test design level calculations of Doppler reactivity

1982-08-01

98

Pulsed-Doppler ultrasonic arteriography  

International Nuclear Information System (INIS)

Pulsed-Doppler ultrasonic arteriography is a relatively new procedure that permits noninvasive imaging of the arterial lumen and provides audio information regarding the velocity patterns of blood flow. It has been shown to be quite accurate for the detection of extracranial carotid arterial lesions, especially those that narrow the diameter of the arterial lumen by at least 45%. The authors' laboratory has been using an ultrasonic arteriograph since February 1977 to study more than 1,800 patients suspected of having carotid occlusive disease. This paper reviews the authors' experience with this noninvasive procedure

1984-01-01

99

Fast maximum entropy Doppler mapping  

CERN Document Server

A numerical code is described for constructing Doppler maps from the orbital variation of line profiles of (mass transfering) binaries. It uses an algorithm related to Richardson-Lucy iteration, and is much faster than the standard algorithm used for ME problems. The method has been tested on data of cataclysmic variables (including WZ Sge and SS Cyg), producing maps of up to 300X300 points. It includes an IDL-based set of routines for manipulating and plotting the input and output data, and can be downloaded from http://www.mpa-garching.mpg.de/~henk

Spruit, H C

1998-01-01

100

21 CFR 892.1550 - Ultrasonic pulsed doppler imaging system.  

Science.gov (United States)

...2009-04-01 false Ultrasonic pulsed doppler imaging system. 892.1550 Section...Devices § 892.1550 Ultrasonic pulsed doppler imaging system. (a) Identification. An ultrasonic pulsed doppler imaging system is a device that...

2009-04-01

 
 
 
 
101

Luminosity Dependence and Search Doppler  

Science.gov (United States)

The research supported by this grant covered two projects: (1) a study of the luminosity dependence of the properties of atoll sources; and (2) a search for Doppler shifts in the pulse arrival times of the anomalous pulsar 4U 0142+61. Following the discovery of kilohertz quasi-periodic oscillations (QPOS) in Sco X-1 studies of the X-ray properties of atoll sources have been dominated by searches for these QPOS, and the study of their dependence on other source properties, such as X-ray luminosity and spectral state. In the project supported by grant NAG5-3269 we have detected kHz QPOs for several atoll sources. The physical interpretation of these QPO is as yet unclear, but simple models (such as the Keplerian beat frequency model) can probably be excluded. The results of this research have been reported. We have studied the X-ray pulsations of the anomalous X-ray pulsar 4U 0142+61 using the Rossi XTE. A detailed search for Doppler shifts did not lead to a positive detection. The upper limits exclude almost all types of possible companion stars, except white dwarfs. However, the latter can be excluded since anomalous X-ray pulsars are very young objects. We therefore conclude that anomalous X-ray pulsars are single neutron stars.

VanParadijs, Johannes A.

1998-01-01

102

Color doppler sonography in thickened gallbladder wall  

Energy Technology Data Exchange (ETDEWEB)

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.

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

1996-11-01

103

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

1996-11-01

104

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)

2008-12-01

105

A Doppler-broadening lineshape parameter standard  

International Nuclear Information System (INIS)

A new scheme is introduced for the determination of lineshape parameters from Doppler-broadened annihilation spectra. The evaluation of this generalized lineshape parameter from the observed Doppler profile is equivalent to an integration over the true Doppler-broadened energy distribution multiplied by a standard weight function. Therefore, this lineshape parameter is independent of the resolution function of the #betta#-detector used. For the standard weight function a Gaussian function with a standard deviation of 0.75 keV is proposed. (Auth.)

1982-04-07

106

Compensating For Doppler Shift In Laser Instrumentation  

Science.gov (United States)

Electronic tuning system continually adjusts frequency of tunable diode laser to compensate for Doppler shift caused by motion of transmitter or receiver containing laser. Doppler-shift-compensating system intended primarily for use in transmitter or receiver of laser remote-sensing or communication system to keep frequency of received signal within frequency range of narrow-band-pass filter. By use of narrow-band filter (instead of wide-band filter required in absence of Doppler compensation), signal-to-noise ratio of laser system increased. Thus, less-powerful transmitter usable.

Schwemmer, Geary K.

1990-01-01

107

Doppler Imaging of Exoplanets and Brown Dwarfs  

CERN Document Server

Doppler Imaging produces 2D global maps of rotating objects using high-dispersion spectroscopy. When applied to brown dwarfs and extrasolar planets, this technique can constrain global atmospheric dynamics and/or magnetic effects on these objects in un- precedented detail. I present the first quantitative assessment of the prospects for Doppler Imaging of substellar objects with current facilities and with future giant ground-based telescopes. Observations will have the greatest sensitivity in K band, but the H and L bands will also be useful for these purposes. To assess the number and availability of targets, I also present a compilation of all measurements of photometric variability, rotation period (P), and projected rotational velocity (v sin i) for brown dwarfs and exoplanets. Several bright objects are already accessible to Doppler Imaging with currently available instruments. With the development of giant ground-based telescopes, Doppler Imaging will become feasible for many dozens of brown dwarfs and...

Crossfield, Ian J M

2014-01-01

108

Intensity changes in the Doppler effect  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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.

Johnson, Montgomery H.; Teller, Edward

1982-01-01

109

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)

1965-01-01

110

Doppler Shift Methods for Plasma Diagnostics,  

Science.gov (United States)

Work to develop novel advanced laser spectroscopy plasma diagnostic methods is described. The methods are based on observing the doppler shift in the absorption liners of ionic species. Two methods under study are Velocity Modulated Laser Spectroscopy and...

M. Sassi J. W. Daily

1987-01-01

111

Doppler radar imaging of spherical planetary surfaces  

Science.gov (United States)

This paper describes a technique for using echo power-spectra for making radar images of spherical planetary targets. In developing the Doppler-radar imaging system, the target's reflectivity distribution is expanded in a truncated spherical harmonic series; the distribution of echo power in rotational phase and the Doppler frequency are obtained in form of a system of linear equations which express the echo spectra as functions of the series coefficients. To estimate the coefficients from an observed phase-Doppler distribution, the inversion is cast as a least-squares problem, and is solved using singular value decompositions, yielding a linear imaging system which can be fully characterized by its impulse response as a function of latitude. Simulations were designed and used to explore the capabilities of Doppler radar imaging, and the sensitivity of imaging to such factors as subradar altitude coverage and signal-to-noise ratio was investigated.

Hudson, R. Scott; Ostro, Steven J.

1990-01-01

112

Doppler Effect of Mechanical Waves and Light  

Directory of Open Access Journals (Sweden)

Full Text Available We discussed the Doppler Effect of mechanical waves when the relative velocity is not in the direction of wave vector;and we found that the observed frequency changes with time, which is different from the results when the relativevelocity is along the wave vector direction. We showed a simple derivation of Doppler Effect equation for the light byusing time dilation principle and showed that the motion of light source and observer has the same effect on thefrequency shift

Jiacai Nie

2009-09-01

113

Carotid Doppler evaluation in cerebrovascular disease.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The Doppler technique has proven to be a useful noninvasive technique for evaluating the patency of the carotid artery in patients at risk of stroke. The data obtained from 246 carotid Doppler examinations were compared with the angiographic findings in the same patients. The sensitivity, specificity and accuracy were high when the degree of stenosis was greater than 50%, but occlusions were less reliably detected, with 8 (33%) of the 24 being misdiagnosed as high-grade stenoses. Carotid Dopp...

1983-01-01

114

Doppler velocimeter for laser accelerated targets  

International Nuclear Information System (INIS)

A doppler velocimeter utilizing a spectrograph and a short pulse laser probe is described which provides good spatial (20 ?m) and subnanosecond temporal resolution. This system has been used to measure the velocity profiles of targets ablatively accelerated to very high velocities by a high power laser beam. A unique aspect of this velocimeter is that the doppler wavelength shifts are measured directly rather than employing interferometric techniques

1980-01-01

115

Estimating the Doppler centroid of SAR data  

Digital Repository Infrastructure Vision for European Research (DRIVER)

After reviewing frequency-domain techniques for estimating the Doppler centroid of synthetic-aperture radar (SAR) data, the author describes a time-domain method and highlights its advantages. In particular, a nonlinear time-domain algorithm called the sign-Doppler estimator (SDE) is shown to have attractive properties. An evaluation based on an existing SEASAT processor is reported. The time-domain algorithms are shown to be extremely efficient with respect to requirements on calculations an...

2009-01-01

116

Color Doppler Ultrasound Indices in Endometriotic Cysts  

Directory of Open Access Journals (Sweden)

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.

Parisa Hajialioghlo

2009-01-01

117

Estimating the Doppler centroid of SAR data  

DEFF Research Database (Denmark)

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

Madsen, Søren Nørvang

1989-01-01

118

Doppler velocimetry in cavitating media.  

Science.gov (United States)

A numerical model has been developed to simulate propagation of ultrasonic beams in inhomogeneous moving media. The model is based on the ray theory of propagating waves, valid in the limit of high frequencies. The resulting equations depend only on local values of the velocity field and the speed of sound. In its implementation, the model assumes that the interactions of sound with the surrounding flow field are decoupled. This allows for applying the model in a post processing mode to flows computed by other means. The model was used to investigate beam behavior in unsteady cavitating flows. The study was motivated by reports of cavitation occurring in mitral bi-leaflet mechanical heart valves. The flow field and cavitation physics were simulated using a general purpose computer code, CFD-ACE. The ultrasonic beam model was then used to calculate the beam path, orientation, and frequency changes in the transient cavitating region. Results show that the presence of cavitation can fundamentally alter the beam propagation characteristics. Simple models that assume rectilinear propagation cannot, by definition, handle such flows. Cavitation incurs very large variations in the local sound speed, which in turn can induce very large distortions in the beam. This fact has strong ramifications regarding the accuracy of ultrasonic velocimetry when simple models are used to interpret Doppler data gathered under such flow conditions. PMID:9360085

Pindera, M Z; Siegel, J M; Makhijani, V B

1997-01-01

119

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

2010-06-01

120

Noninvasive image derived heart input function for CMRglc measurements in small animal slow infusion FDG PET studies.  

Science.gov (United States)

Absolute quantitation of the cerebral metabolic rate for glucose (CMRglc) can be obtained in positron emission tomography (PET) studies when serial measurements of the arterial [(18)F]-fluoro-deoxyglucose (FDG) input are available. Since this is not always practical in PET studies of rodents, there has been considerable interest in defining an image-derived input function (IDIF) by placing a volume of interest (VOI) within the left ventricle of the heart. However, spill-in arising from trapping of FDG in the myocardium often leads to progressive contamination of the IDIF, which propagates to underestimation of the magnitude of CMRglc. We therefore developed a novel, non-invasive method for correcting the IDIF without scaling to a blood sample. To this end, we first obtained serial arterial samples and dynamic FDG-PET data of the head and heart in a group of eight anaesthetized rats. We fitted a bi-exponential function to the serial measurements of the IDIF, and then used the linear graphical Gjedde-Patlak method to describe the accumulation in myocardium. We next estimated the magnitude of myocardial spill-in reaching the left ventricle VOI by assuming a Gaussian point-spread function, and corrected the measured IDIF for this estimated spill-in. Finally, we calculated parametric maps of CMRglc using the corrected IDIF, and for the sake of comparison, relative to serial blood sampling from the femoral artery. The uncorrected IDIF resulted in 20% underestimation of the magnitude of CMRglc relative to the gold standard arterial input method. However, there was no bias with the corrected IDIF, which was robust to the variable extent of myocardial tracer uptake, such that there was a very high correlation between individual CMRglc measurements using the corrected IDIF with gold-standard arterial input results. Based on simulation, we furthermore find that electrocardiogram-gating, i.e. ECG-gating is not necessary for IDIF quantitation using our approach. PMID:23160517

Xiong, Guoming; Paul, Cumming; Todica, Andrei; Hacker, Marcus; Bartenstein, Peter; Böning, Guido

2012-12-01

 
 
 
 
121

Retroreflector for photonic Doppler velocimetry  

Science.gov (United States)

In order to meet the goals of the Department of Defense (DoD) for smaller and more accurate weapons, numerous projects are currently investigating the miniaturization of weapons and munition fuze components. One of these efforts is to characterize the performance of small detonators. The velocity of the flyer, the key component needed to initiate a detonation sequence, can be measured using a photonic Doppler velocimeter (PDV). The purpose of this research was to develop a microelectromechanical system (MEMS) device that would act as an optimal retroreflective surface for the PDV. Two MEMS solutions were explored: one using the PolyMUMPsTM fabrication process and one in-house fabrication design using silicon on insulator (SOI) wafers. The in-house design consisted of an array of corner reflectors created using an SOI wafer. Each corner reflector consisted of three separate mirror plates which were self-assembled by photoresist pad hinges. When heated to a critical temperature (typically 140-160 °C), the photoresist pads melted and the resulting surface tension caused each mirror to rotate into place. The resulting array of corner reflectors was then coated with a thin layer of gold to increase reflectivity. Despite the successful assembly of a PolyMUMPsTM corner reflector, assembling an array of these reflectors was found to be unfeasible. Although the SOI corner reflector design was completed, these devices were not fabricated in time for testing during this research. However, the bidirectional reflectance distribution function (BRDF) and optical cross section (OCS) of commercially available retroreflective tapes were measured. These results can be used as a baseline comparison for future testing of a fabricated SOI corner reflector array.

Lagoski, Thomas J.; Coutu, Ronald A., Jr.; Starman, Lavern A.

2009-08-01

122

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

1986-01-01

123

Development of the doppler electron velocimeter: theory.  

Energy Technology Data Exchange (ETDEWEB)

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.

Reu, Phillip L.

2007-03-01

124

Doppler estimation accuracy of linear FM waveforms  

Science.gov (United States)

The single-pulse Doppler estimation accuracy of an unweighted linear FM waveform is analyzed in detail. Simple formulas are derived that predict that one-sigma Doppler estimation error for realistic radar applications. The effects of multiple target interference and nonlinearlities in the radar measurements are considered. In addition, a practical method to estimate Doppler frequency is presented. This technique uses the phase data after pulse compression, and it limits the effect of multiple target interference. In contrast, the available literature is based on the Cramer-Rao bound for Doppler accuracy, which ignores the effects of nonlinearities, multiple target interference and the question of practical implementation. A simple formula is derived that predicts the region of validity for the Cramer-Rao bound. This formula provides a criterion for minimum signal-to-noise ratio in terms of time-bandwidth product. Finally, an important concept that is demonstrated in this paper is that: the bulk of the Doppler information in a linear FM pulse is encoded in the range sidelobes after pulse compression.

Daum, F. E.

125

Doppler effect: surprises from the time domain  

Science.gov (United States)

A full understanding of Doppler, either acoustic or electromagnetic, depends on representing the effect in the time domain as well as in the frequency domain. In the time domain, the Doppler perturbation (f - f0)/f0 for a signal becomes its time-delay time derivative. A surprising physical consequence (deduced here for an acoustic reflection problem) is that the Doppler perturbation depends on ratios of distances (source-to-echoer and echoer-to-receiver) as well as on various velocities and angles. Another surprise from the time domain concerns the reverse Doppler effect observed both for electromagnetic and acoustic signals. In certain artificial environments (metamaterials with negative refractive index), radiation can be received with a lower frequency when the source approaches a receiver and with a higher frequency when receding from it. The time-delay time derivative picture represents this effect as a paradox: The time delay (hence source-to-receiver distance) increases when its time-delay time derivative is negative. The restriction of reverse Doppler to a dissipative domain may ameliorate the paradox but does not solve it.

Brill, Michael H.

2010-02-01

126

The EVE Doppler Sensitivity and Flare Observations  

Science.gov (United States)

The Extreme-ultraviolet Variability Experiment (EVE) obtains continuous EUV spectra of the Sun viewed as a star. Its primary objective is the characterization of solar spectral irradiance, but its sensitivity and stability make it extremely interesting for observations of variability on time scales down to the limit imposed by its basic 10 s sample interval. In this paper we characterize the Doppler sensitivity of the EVE data. We find that the 30.4 nm line of He II has a random Doppler error below 0.001 nm (1 pm, better than 10 km/s as a redshift), with ample stability to detect the orbital motion of its satellite, the Solar Dynamics Observatory (SDO). Solar flares also displace the spectrum, both because of Doppler shifts and because of EVE's optical layout, which (as with a slitless spectrograph) confuses position and wavelength. As a flare develops, the centroid of the line displays variations that reflect Doppler shifts and therefore flare dynamics. For the impulsive phase of the flare SOL2010-06-12, we find the line centroid to have a redshift of 16.8 +/- 5.9 km/s relative to that of the flare gradual phase (statistical errors only). We find also that high-temperature lines, such as Fe XXIV 19.2 nm, have well-determined Doppler components for major flares, with decreasing apparent blueshifts as expected from chromospheric evaporation flows.

Hudson, H. S.; Woods, T. N.; Chamberlin, P. C.; Didkovsky, L.; Del Zanna, G.

2011-01-01

127

Duplex doppler sonography in portal hypertension  

Directory of Open Access Journals (Sweden)

Full Text Available Conventional echotomography and duplex Doppler ultrasonography are noninvasive imaging techniques in measurement of hepatic blood flow. In the period from February 2002 to March 2004, 29.086 patients underwent ultrasound examination at the Institute of Radiology in Novi Sad, and 17.503 presented with symptoms of gastroenterology diseases and/or hepatobiliary tract diseases. 984 patients underwent duplex Doppler sonography. This prospective study included 50 patients with suspected or confirmed diagnosis of portal hypertension. All patients were examined using Siemens Versa Pro (3.5 MHz convex probe; B-mode, color and pulse Doppler. The following parameters were evaluated: Doppler sonoscore, congestion index and portal vein thrombosis. By analyzing gathered data, the diagnosis of portal hypertension was confirmed in 10% of patients at baseline, and in 6% of patients at last follow-up, six months later. Results of this investigation demonstrate the importance of duplex Doppler ultrasonography as an excellent noninvasive diagnostic method used for visualization of the direction and velocity of blood flow, as well as presence of portal vein thrombosis. This imaging modality is used as an initial diagnostic tool in the evaluation of the portohepatic circulation, especially in portal hypertension syndrome and in suspected portal vein thrombosis. .

Ni?iforovi? Dijana

2007-01-01

128

Doppler Simulation and Analysis of SCME Channel Model  

Directory of Open Access Journals (Sweden)

Full Text Available In this contribution, the Doppler spectral properties are simulated and analyzed based on 3GPP Spatial Channel Model extension (SCME. SCME standard channel model is applied to the system evaluation and optimization in LTE and other future communication networks. Since future mobile communication systems demand for high moving speed, the simulation and analysis of Doppler characteristics become so significant. Therefore, we focus on the simulation of Doppler spectral properties in different scenarios of SCME channel model. The simulated Doppler power spectrum and Doppler delay spectrum are applicable to characterize Doppler properties of time-varying channels.

Xiaoyan Huang

2012-10-01

129

Color Doppler ultrasonography evaluation of amblyopia  

Directory of Open Access Journals (Sweden)

Full Text Available AIM: To assess the hemodynamic changes in the extraocular orbital vessels of amblyopic patients in comparison with non-amblyopic fellow eyes, using color Doppler ultrasonography(CDU. METHODS: Thirty-six eyes of 18 pediatric patients were included in the study(20 amblyopic, 16 normal. All eyes underwent color Doppler ultrasonography examination of ophthalmic artery, central retinal artery, and posterior ciliary artery. RESULTS: The only differences between the two groups with regard to color Doppler ultrasonography parameters was the significantly lower peak systolic velocity(32.70±11.60 vs 55.01±11.68, P=0.001and end-diastolic velocity(6.83±1.91 vs 13.99±4.15, P=0.001for ophthalmic artery in amblyopic eyes.CONCLUSION: Our study showed amblyopic eyes may present a decrease in retrobulbar blood flow velocity.

Ece Turan-Vural

2013-07-01

130

Arm locking with Doppler estimation errors  

International Nuclear Information System (INIS)

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.

2010-05-01

131

Inline Ultrasonic Rheometry by Pulsed Doppler  

Energy Technology Data Exchange (ETDEWEB)

This will be a discussion of the non-invasive determination of the viscosity of a non-Newtonian fluid in laminar pipe flow over the range of shear rates present in the pipe. The procedure used requires knowledge of the flow profile in and the pressure drop along a long straight run of pipe. The profile is determined by using a pulsed ultrasonic Doppler velocimeter. This approach is ideal for making non-invasive, real-time measurements for monitoring and control. Rheograms of a shear thinning, thixotropic gel will be presented. The operating parameters and limitations of the Doppler-based instrument will be discussed. The most significant limitation is velocity gradient broadening of the Doppler spectra near the walls of the pipe. This limitation can be significant for strongly shear thinning fluids (depending also on the ratio of beam to pipe diameter and the transducer's insertion angle).

Pfund, David M.; Greenwood, Margaret S.; Bamberger, Judith A.; Pappas, Richard A.

2006-12-22

132

Inline ultrasonic rheometry by pulsed Doppler.  

Science.gov (United States)

This will be a discussion of the non-invasive determination of the viscosity of a non-Newtonian fluid in laminar pipe flow over the range of shear rates present in the pipe. The procedure used requires knowledge of the flow profile in and the pressure drop along a long straight run of pipe. The profile is determined by using a pulsed ultrasonic Doppler velocimeter. This approach is ideal for making non-invasive, real-time measurements for monitoring and control. Rheograms of a shear thinning gel will be presented. The operating parameters and limitations of the Doppler-based instrument will be discussed. The most significant limitation is velocity gradient broadening of the Doppler spectra near the walls of the pipe. This limitation can be significant for strongly shear thinning fluids (depending also on the ratio of beam to pipe diameter and the transducer's insertion angle). PMID:16808950

Pfund, David M; Greenwood, Margaret S; Bamberger, Judith A; Pappas, Richard A

2006-12-22

133

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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-aide...

2007-01-01

134

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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) estimati...

2007-01-01

135

Sub-Doppler Raman saturation spectroscopy  

International Nuclear Information System (INIS)

Sub-Doppler linewidth spectra of the Q01 (2) transition in deuterium (D2) have been obtained by using a stimulated Raman technique analogous to sub-Doppler IR saturation spectroscopy. Two experimental configurations are described that employ alternatively either three or four laser beams at two frequencies. The saturation dip is detected by using an inverse Raman technique to probe the saturated line shape. It is shown that, by delaying the pulsed measurement from the pulsed saturation, the technique can be used to study velocity relaxation processes in homonuclear diatomics or other Raman-active molecules

1980-01-01

136

Doppler diagnosis of deep venous thrombosis  

International Nuclear Information System (INIS)

The venous Doppler examination has been shown to be a sensitive test for the diagnosis of deep venous thrombosis. An experienced technologist can perform the examination in about ten minutes at the bedside or in the laboratory. Because the venous Doppler examination is subjective, it requires considerable experience of the examiner to achieve maximal accuracy. Nevertheless, with sufficient practice the technologist may employ this instrument with skill and versatility to detect both obstruction and valvular incompetence in the superficial, communicating, and deep veins of the lower and upper extremities

1984-01-01

137

A low cost Doppler system for vascular dialysis access surveillance.  

Science.gov (United States)

The National Kidney Foundation guidelines for vascular access recommend access surveillance to avoid morbidity among patients undergoing hemodialysis. Methods to detect access failure based on CW Doppler system are being proposed to implement surveillance programs at lower cost. This work describes a low cost Doppler system implemented in a PC notebook designed to carry out this task. A Doppler board samples the blood flow velocity and delivers demodulated quadrature Doppler signals. These signals are sampled by a notebook sound card. Software for Windows OS (running at the notebook) applies CFFT to consecutive 11.6 ms intervals of Doppler signals. The sonogram is presented on the screen in real time. The software also calculates the maximum and the intensity weighted mean frequency envelopes. Since similar systems employ DSP boards to process the Doppler signals, cost reduction was achieved. The Doppler board electronic circuits and routines to process the Doppler signals are presented. PMID:17272199

Molina, P S C; Moraes, R; Baggio, J F R; Tognon, E A

2004-01-01

138

Computer Vision Approach for Ultrasound Doppler Angle Estimation  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Doppler ultrasound is an important noninvasive diagnostic tool for cardiovascular diseases. Modern ultrasound imaging systems utilize spectral Doppler techniques for quantitative evaluation of blood flow velocities, and these measurements play a crucial rule in the diagnosis and grading of arterial stenosis. One drawback of Doppler-based blood flow quantification is that the operator has to manually specify the angle between the Doppler ultrasound beam and the vessel orientation, which is cal...

Saad, Ashraf A.; Loupas, Thanasis; Shapiro, Linda G.

2009-01-01

139

Ionospheric Doppler measurements by means of HF-radar techniques  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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. ...

2005-01-01

140

Low-Frequency Gravitational Wave Searches Using Spacecraft Doppler Tracking  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 gravitat...

2006-01-01

 
 
 
 
141

Absolute flow velocity components in laser Doppler flowmetry  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A method to separate a Doppler power spectrum into a number of flow velocity components, measured in absolute units (mm/s), is presented. A Monte Carlo software was developed to track each individual Doppler shift, to determine the probability, p(n), for a photon to undergo n Doppler shifts. Given this shift distribution, a mathematical relationship was developed and used to calculate a Doppler power spectrum originating from a certain combination of velocity components. The non linear Levenb...

2006-01-01

142

Doppler echocardiography: Quantitative methods of pulsed and continuous wave cardiac doppler  

Energy Technology Data Exchange (ETDEWEB)

This book is written in workbook format and presents basic physical principles involved in the Doppler flow velocity recording in both normal and abnormal states. Formulas necessary in the computation of valve gradients, valve areas, and cardiac outputs are included.

Labovitz, A.J.; Williams, G.A.

1985-01-01

143

Doppler echocardiography: Quantitative methods of pulsed and continuous wave cardiac doppler  

International Nuclear Information System (INIS)

This book is written in workbook format and presents basic physical principles involved in the Doppler flow velocity recording in both normal and abnormal states. Formulas necessary in the computation of valve gradients, valve areas, and cardiac outputs are included

1985-01-01

144

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

2005-01-01

145

A resonance spectrometer without Doppler broadening  

Energy Technology Data Exchange (ETDEWEB)

Doppler broadening and other small broadening in the resonance spectrometer are successfully removed by using a new method. The neutron capture resonance was measured for positive and negative neutron helicity states. In the difference of the two resonance spectra, the broadening was found to be almost cancelled. (orig.).

Masuda, Y.; Adachi, T. (National Lab. for High Energy Physics, Tsukuba (Japan)); Shimizu, H.M. (Dept. of Physics, Kyoto Univ. (Japan))

1992-06-01

146

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

1987-06-02

147

Parameter estimation based on Doppler frequency shifts  

Science.gov (United States)

An acoustic source generates an amplitude-modulated tone, with Doppler variations due to the relative motion between source and receiver. A method is presented for real-time estimation of tone rest frequency and minimal distance between source and receiver, using digital signal processing techniques. The algorithm presented here was implemented using a Texas Instruments TMS32010 processor.

Statman, Joseph I.; Rodemich, Eugene R.

1987-01-01

148

[Possibilities and limits of transcranial Doppler sonography].  

Science.gov (United States)

A review of our 4-years' experience with the transcranial Doppler technique in the evaluation of cerebrovascular disease is given. The physiological variations of the measured parameters and their clinical significance are presented. The diagnosis of occlusive diseases, spasms after subarachnoid haemorrhage, arteriovenous malformations and brain death are discussed. Some technical problems and limiting factors in diagnosis are summarised. PMID:2956683

Grolimund, P; Seiler, R W; Mattle, H

1987-04-01

149

A MAGNETIC CALIBRATION OF PHOTOSPHERIC DOPPLER VELOCITIES  

Energy Technology Data Exchange (ETDEWEB)

The zero point of measured photospheric Doppler shifts is uncertain for at least two reasons: instrumental variations (from, e.g., thermal drifts); and the convective blueshift, a known correlation between intensity and upflows. Accurate knowledge of the zero point is, however, useful for (1) improving estimates of the Poynting flux of magnetic energy across the photosphere, and (2) constraining processes underlying flux cancellation, the mutual apparent loss of magnetic flux in closely spaced, opposite-polarity magnetogram features. We present a method to absolutely calibrate line-of-sight (LOS) velocities in solar active regions (ARs) near disk center using three successive vector magnetograms and one Dopplergram coincident with the central magnetogram. It exploits the fact that Doppler shifts measured along polarity inversion lines (PILs) of the LOS magnetic field determine one component of the velocity perpendicular to the magnetic field, and optimizes consistency between changes in LOS flux near PILs and the transport of transverse magnetic flux by LOS velocities, assuming that ideal electric fields govern the magnetic evolution. Previous calibrations fitted the center-to-limb variation of Doppler velocities, but this approach cannot, by itself, account for residual convective shifts at the limb. We apply our method to vector magnetograms of AR 11158, observed by the Helioseismic and Magnetic Imager aboard the Solar Dynamics Observatory, and find clear evidence of offsets in the Doppler zero point in the range of 50-550 m s{sup -1}. In addition, we note that a simpler calibration can be determined from an LOS magnetogram and Dopplergram pair from the median Doppler velocity among all near-disk-center PIL pixels. We briefly discuss shortcomings in our initial implementation, and suggest ways to address these. In addition, as a step in our data reduction, we discuss the use of temporal continuity in the transverse magnetic field direction to correct apparently spurious fluctuations in resolution of the 180 Degree-Sign ambiguity.

Welsch, Brian T.; Fisher, George H. [Space Sciences Laboratory, University of California, Berkeley, CA 94720-7450 (United States); Sun, Xudong [W. W. Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA 94305 (United States)

2013-03-10

150

Doppler imaging of exoplanets and brown dwarfs  

Science.gov (United States)

Doppler imaging produces 2D global maps of rotating objects using high-dispersion spectroscopy. When applied to brown dwarfs and extrasolar planets, this technique can constrain global atmospheric dynamics and/or magnetic effects on these objects in unprecedented detail. I present the first quantitative assessment of the prospects for Doppler imaging of substellar objects with current facilities and with future giant ground-based telescopes. Observations will have the greatest sensitivity in K band, but the H and L bands will also be useful for these purposes. To assess the number and availability of targets, I also present a compilation of all measurements of photometric variability, rotation period (P), and projected rotational velocity (v sin i) for all known brown dwarfs. Several bright objects are already accessible to Doppler imaging with currently available instruments. With the development of giant ground-based telescopes, Doppler imaging will become feasible for many dozens of brown dwarfs and for the few brightest directly imaged extrasolar planets (such as ? Pic b). The present set of measurements of P, v sin i, and variability are incomplete for many objects, and the sample is strongly biased toward early-type objects (Doppler imaging. Full Table 2 is available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/566/A130

Crossfield, Ian J. M.

2014-06-01

151

The Novel Nonlinear Adaptive Doppler Shift Estimation Technique and the Coherent Doppler Lidar System Validation Lidar  

Science.gov (United States)

The signal processing aspect of a 2-m wavelength coherent Doppler lidar system under development at NASA Langley Research Center in Virginia is investigated in this paper. The lidar system is named VALIDAR (validation lidar) and its signal processing program estimates and displays various wind parameters in real-time as data acquisition occurs. The goal is to improve the quality of the current estimates such as power, Doppler shift, wind speed, and wind direction, especially in low signal-to-noise-ratio (SNR) regime. A novel Nonlinear Adaptive Doppler Shift Estimation Technique (NADSET) is developed on such behalf and its performance is analyzed using the wind data acquired over a long period of time by VALIDAR. The quality of Doppler shift and power estimations by conventional Fourier-transform-based spectrum estimation methods deteriorates rapidly as SNR decreases. NADSET compensates such deterioration in the quality of wind parameter estimates by adaptively utilizing the statistics of Doppler shift estimate in a strong SNR range and identifying sporadic range bins where good Doppler shift estimates are found. The authenticity of NADSET is established by comparing the trend of wind parameters with and without NADSET applied to the long-period lidar return data.

Beyon, Jeffrey Y.; Koch, Grady J.

2006-01-01

152

Carotid Artery Doppler Assessment In Patients Accussed Of Strokes  

Directory of Open Access Journals (Sweden)

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.

H. Mazaher

2005-08-01

153

Doppler-spectrally encoded imaging of translational objects  

Science.gov (United States)

The image of a translational target is moved by the Doppler-shifted phase of the diffraction field of the light incident on the target. However, no one has yet utilized the physical relationship between the Doppler effect and the diffraction field in microscopic imaging. Here, we demonstrate Doppler-spectral encoding of the diffraction field of a translational target. We found that the angular spectrum of the translational object was encoded by the Doppler spectrum, and the interferometric recombination of the Doppler spectrum yielded a 2-dimensional complex image. We further discovered that two Doppler effects, which are evoked by the movement of the target against a stationary source and detector, can be exploited simultaneously in synthetic aperture tomography. Doppler-spectrally encoded imaging may lead not only to label-free imaging flow cytometry of living cells but also to non-destructive imaging of products during inspection on a conveyer belt in either the sound or electromagnetic regimes.

Iwai, Hidenao; Yamauchi, Toyohiko; Miwa, Mitsuharu; Yamashita, Yutaka

2014-05-01

154

[Color-Doppler semiology in transplanted kidney].  

Science.gov (United States)

Color-encoded duplex ultrasonography (CEDU) makes a more accurate technique in kidney graft monitoring by combining real-time US with pulsed Doppler studies of renal vasculature. It is a non-invasive and easy technique. Suitable to study the whole renal artery and vein, CEDU also allows the qualitative and quantitative assessment of the intrarenal vasculature and therefore the easy diagnosis of such vessel dysfunctions as arteriovenous fistulas following biopsy. Moreover, Doppler spectral analysis can be used to distinguish among different causes of renal allograft dysfunction--i.e. rejection, cyclosporine nephrotoxicity or acute tubular necrosis. The value of the resistive index for the differential diagnosis is discussed. CEDU allows a more reliable measurement of renal blood flow thanks to the more precise evaluation of renal artery diameter and mean flow velocity. PMID:8332816

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

1993-05-01

155

A Magnetic Calibration of Photospheric Doppler Velocities  

CERN Multimedia

In solar active regions (ARs), Doppler shifts measured along polarity inversion lines (PILs) of the line-of-sight (LOS) magnetic field determine one component of the velocity perpendicular to the magnetic field. Along PILs, these velocities can be used to: (i) improve estimates of photospheric electric fields, which can, in turn, be used to derive the Poynting flux of magnetic energy across the photosphere; and (ii) constrain the physical processes underlying flux cancellation, the mutual apparent loss of magnetic flux as closely spaced, opposite-polarity magnetogram features approach each other. Unfortunately, at least two factors introduce uncertainties into the zero point of measured Doppler velocities. First, instrumental effects (e.g., thermal variations in instrument components) can cause drifts in calibrations. Second, the convective blueshift, a well-known correlation between intensity and upflows, can bias estimates of the plasma's rest wavelength. Here, we present a method to absolutely calibrate LO...

Welsch, Brian T

2012-01-01

156

Minior Actinide Doppler Coefficient Measurement Assessment  

International Nuclear Information System (INIS)

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 documented experiments are designed to support the Advanced Fuel Cycle Initiative in conducting safety analysis of advanced fast reactor or accelerator-driven transmutation systems with fuel containing high minor actinide content

2008-01-01

157

ESTADO ACTUAL DEL ULTRASONIDO DOPPLER CAROTÍDEO  

Directory of Open Access Journals (Sweden)

Full Text Available El ultrasonido Doppler es el método de imagen más utilizado en el estudio de las carótidas pues ofrece una evaluación no invasiva para detectar las placas de ateroma como causa de tromboembolismo cerebral, permite definir sus características y el grado de estenosis que producen, muchas veces constituye el único estudio antes de la cirugía o la colocación de stent. Se ha demostrado su utilidad como método de screening de riesgo cardiovascular en pacientes asintomáticos y en el diagnóstico de otras afecciones no ateroescleróticas, sin embargo, aún no existe uniformidad en la realización e interpretación del examen lo cual depende en gran medida de la falta de protocolos de examen estandarizados y que los mismos sean realizados por un personal debidamente entrenado. En este artículo se hace una revisión del estado actual de la ecografía Doppler carotídea, sus indicaciones, los protocolos de examen y los criterios diagnósticos empleados.

Hu00E9ctor Pereira Recio

2007-01-01

158

MEMS based Doppler velocity measurement system  

Science.gov (United States)

The design, fabrication, modeling and characterization of a capacitive micromachined ultrasonic transducer (cMUT) based in-air Doppler velocity measurement system using a 1 cm2 planar array are described. Continuous wave operation in a narrowband was chosen in order to maximize range, as it allows for better rejection of broadband noise. The sensor array has a 160-185 kHz resonant frequency to achieve a 10 degree beamwidth. A model for the cMUT and the acoustic system which includes electrical, mechanical, and acoustic components is provided. Furthermore, characterization of the cMUT sensor with a variety of testing procedures is provided. Laser Doppler vibrometry (LDV), beampattern, reflection, and velocity testing characterize the performance of the sensors. The sensor is capable of measuring the velocity of a moving specular reflector with a resolution of 5 cm/s, an update rate of 0.016 second, and a range of 1.5 m.

Shin, Minchul

159

ROTATIONAL DOPPLER BEAMING IN ECLIPSING BINARIES  

International Nuclear Information System (INIS)

In eclipsing binaries the stellar rotation of the two components will cause a rotational Doppler beaming during eclipse ingress and egress when only part of the eclipsed component is covered. For eclipsing binaries with fast spinning components this photometric analog of the well-known spectroscopic Rossiter-McLaughlin effect can exceed the strength of the orbital effect. Example light curves are shown for a detached double white dwarf binary, a massive O-star binary and a transiting exoplanet case, similar to WASP-33b. Inclusion of the rotational Doppler beaming in eclipsing systems is a prerequisite for deriving the correct stellar parameters from fitting high-quality photometric light curves and can be used to determine stellar obliquities as well as, e.g., an independent measure of the rotational velocity in those systems that may be expected to be fully synchronized.

2012-01-20

160

Precision Doppler measurements with steep dispersion.  

Science.gov (United States)

Controlling the group velocity of light is a valuable resource for quantum and classical optical processing and high performance sensor technologies. In this context, slow-light (SL) and the associated steep dispersion have been proposed to increase the sensitivity of certain types of interferometers. Here, we show that the interaction of two intensity-balanced light beams in a SL medium can be used to detect Doppler shifts with extremely high sensitivity. By using this effect in a liquid crystal light-valve, we have been able to measure Doppler shifts as low as 1 ?Hz with an integration time of only 1 s. The shot noise limited sensitivity inversely depends on the steepness of the beam-coupling dispersive response. This method allows for remote sensing of very slowly moving objects with a linear response over 5 orders of magnitude. PMID:24104661

Bortolozzo, Umberto; Residori, Stefania; Howell, John C

2013-08-15

 
 
 
 
161

Doppler diagnosis of intracranial artery occlusive disorders.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Pulsed wave 2 MHz Doppler with acoustical focusing was used to obtain blood flow velocity recordings through the intact cranium in 11 patients with occlusive disease of major intracranial arteries. Increased blood flow velocities were recorded from stenoses of the carotid siphon and of the middle cerebral, anterior cerebral and basilar arteries. A clear, inverse relationship existed between angiographical residual lumen diameter and flow velocity. The Kendall rank correlation coefficient (Tau...

Lindegaard, K. F.; Bakke, S. J.; Aaslid, R.; Nornes, H.

1986-01-01

162

Sub-Nyquist Radar via Doppler Focusing  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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-Nyqui...

Bar-ilan, Omer; Eldar, Yonina C.

2012-01-01

163

Color Doppler imaging of cervicocephalic fibromuscular dysplasia  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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-bead...

Arning Christian; Grzyska Ulrich

2004-01-01

164

Tecnología Doppler y movimientos respiratorios fetales  

Digital Repository Infrastructure Vision for European Research (DRIVER)

La tecnología ultrasónica Doppler ha resultado ser una herramienta fundamental para la evaluación de la fisiología fetal, dando información importante sobre el estado hemodinámico fetal. Teniendo en cuenta que no sólo el desarrollo y crecimiento normal del feto y su bienestar intraútero depende de una adecuada función de la circulación útero placentaria y feto placentaria, sino de otras estructuras orgánicas, es por lo que este método abre una línea de investigación dentro del ...

2008-01-01

165

Turbulence measurements using the laser Doppler velocimeter.  

Science.gov (United States)

The photomultiplier signal representing the axial velocity of water within a glass pipe is considered. It is shown that with proper analysis of the photomultiplier signal, the turbulent information that can be obtained in liquid flows is equivalent to results obtained in recent hot film studies. In shear flows the signal from the laser Doppler velocimeter contains additional information which may be related to the average shear.

Dunning, J. W., Jr.; Berman, N. S.

1971-01-01

166

Developments in laser Doppler blood perfusion monitoring  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This paper reviews the development and use of laser Doppler perfusion monitors and imagers. Despite their great success and almost universal applicability in microcirculation research, they have had great difficulty in converting to widespread clinical application. The enormous interest in microvascular blood perfusion coupled with the 'ease of use' of the technique has led to 2000+ publications citing its use. However, useful results can only be achieved with an understanding of the basic pr...

2003-01-01

167

ADEPT - Abnormal Doppler Enteral Prescription Trial  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Abstract Background Pregnancies complicated by abnormal umbilical artery Doppler blood flow patterns often result in the baby being born both preterm and growth-restricted. These babies are at high risk of milk intolerance and necrotising enterocolitis, as well as post-natal growth failure, and there is no clinical consensus about how best to feed them. Policies of both early milk feeding and late milk feeding are widely used. This randomised controlled trial aims to determin...

Leaf Alison; Dorling Jon; Kempley Steve; McCormick Kenny; Mannix Paul; Brocklehurst Peter

2009-01-01

168

Doppler Effect and Properties of Light  

Science.gov (United States)

In this experiment, students explore the diffraction of light into different wavelengths (colors) by using a diffraction grating and shoe box to create and measure a visible spectrum. The concepts of diffraction, electromagnetic waves, wavelength, and the electromagnetic spectrum are introduced. The activity also includes a discussion of red shift, blue shift, and the Doppler effect. Information about solar radiation and the roles of stratospheric and tropospheric ozone is included.

Robison, David

169

Estimating SAR Doppler Shifts From Homogeneous Targets  

Science.gov (United States)

Algorithm that processes some of information in synthetic-aperture-radar (SAR) echoes from homogeneous targets yields optimal estimates of Doppler frequency shifts. Helps in further processing to extract as much information as possible about targets. Used to improve radiometric calibrations, to estimate direction of radar antenna, and to determine speeds of moving targets more accurately. Also helpful in measurements of speeds of ocean currents and of wind shears at airports.

Jin, Michael Y.; Chang, C. Y.

1991-01-01

170

The Doppler Peaks from Cosmic Texture  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We compute the angular power spectrum of temperature anisotropies on the microwave sky in the cosmic texture theory, with standard recombination assumed. The spectrum shows `Doppler' peaks analogous to those in scenarios based on primordial adiabatic fluctuations such as `standard CDM', but at quite different angular scales. There appear to be excellent prospects for using this as a discriminant between inflationary and cosmic defect theories.

Crittenden, R. G.; Turok, N. G.

1995-01-01

171

Single mode, extreme precision Doppler spectrographs  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 (B...

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

2012-01-01

172

Princípios físicos do Doppler em ultra-sonografia Physical principles of Doppler ultrasonography  

Directory of Open Access Journals (Sweden)

Full Text Available A ultra-sonografia Doppler é um método relativamente recente dentro da rotina veterinária que fornece informações em tempo real da arquitetura vascular e dos aspectos hemodinâmicos dos vasos sanguíneos examinados em diversos órgãos vitais. Pode determinar a presença, a direção e o tipo de fluxo sanguíneo. Esta revisão de literatura compila as informações sobre os princípios físicos da ultra-sonografia Doppler. A ampliação do conhecimento desta tecnologia possibilita a melhor compreensão das aplicações e limitações deste método diagnóstico, que tem se tornado rotina na medicina veterinária de pequenos animais.Doppler ultrasonography is a relatively new diagnostic tool in veterinary medicine that provides real time details about vascular architecture and hemodynamic aspects of examinated blood vessels in several internal organs. Doppler can identify the presence, direction and type of blood flow. This literature review provides information about the physical principles of Doppler ultrasonography. The enlargement of expertise about this technology lead to a better comprehension of its use and limitations as a diagnostic technique, which already becomes usual in veterinary medicine of small animals.

Cibele Figueira Carvalho

2008-06-01

173

Renal transplant evaluation with power Doppler sonography.  

Science.gov (United States)

This study was performed to determine if the marked variation we had previously noted in the power Doppler sonographic appearance of renal transplants correlated with disease, 22 renal transplants were scanned with power Doppler at 5 MHz, with biopsies being taken within 1 h in 17 kidneys and within 48 h in four other kidneys. Biopsy was not performed in one kidney with distal ureteral obstruction. Biopsy results were complex with many coexistent abnormalities; classification was based upon the predominant abnormality. Cortical vascularity was subjectively evaluated as normal, decreased or markedly decreased, and graded as 0, 1 or 2, respectively, and was compared with biopsy results, serum creatinine levels and resistive index. Cortical vascularity gradings were: 0 (12 cases); 1 (7 cases); and 2 (3 cases). The large number of disease categories (cellular rejection, 11 cases; vascular rejection, 5 cases; IgA nephropathy, 1 case; cyclosporin toxicity, 3 cases; obstruction, 1 case; and lupus nephropathy, 1 case) in relation to the number of vascular grades and number of kidneys precluded statistical analysis of cortical vascularity for rejection. However, vascularity did not appear to correlate with rejection, the three severest cases of vascular rejection having normal (grade 0) vascularity. There was no statistically significant correlation of vascular grade with creatinine levels or resistive index. In conclusion, subjective analysis of the power Doppler sonographic appearance of renal transplants does not appear to aid in their evaluation. PMID:9059293

Hilborn, M D; Bude, R O; Murphy, K J; Platt, J F; Rubin, J M

1997-01-01

174

Acute hemodialysis effects on doppler echocardiographic indices.  

Science.gov (United States)

Conventional echocardiographic (ECHO) parameters of systolic and diastolic func-tion of the left ventricular (LV) have been shown to be load dependent. However, the impact of pre-load reduction on tissue Doppler (TD) parameters of LV function is incompletely understood. To evaluate the effect of a single hemodialysis (HD) session on LV systolic and diastolic function using pulsed Doppler echocardiography and pulsed tissue Doppler imaging (TDI), we studied 81chronic HD patients (40 males; mean age 52.4 ± 16.4 years) with these tools. ECHO parameters were obtained 30 min before and 30 min after HD. Fluid volume removed by HD was 1640 ± 730 cm [3] . HD led to reduction in LV end-diastolic volume (P flow velocity (P flow after HD was noted. Early and late diastolic (E') TDI velocities and the ratio of early to late TDI diastolic velocities (E'/A') on the lateral side of the mitral annulus decreased signi-ficantly after HD (P = 0.013; P = 0.007 and P = 0.008, respectively). Velocity of flow progres-sion (Vp) during diastole was not affected by pre-load reduction. Pulmonary artery systolic pressure and the diameter of the inferior vena cava decreased significantly (P flow progression was minimally affected by pre-load reduction in HD patients. PMID:24969184

Abid, Leila; Rekik, Hajer; Jarraya, Fayçal; Kharrat, Ilyes; Hachicha, Jamil; Kammoun, Samir

2014-01-01

175

Uncertainty quantification of doppler coefficient for MONJU  

International Nuclear Information System (INIS)

Uncertainty of Doppler coefficient is quantified for the Monju core. Component-wise uncertainties are quantified as follows. Note that the following uncertainties correspond to the 2? reliability. Uncertainty due to the nuclear data and numerical method is estimated at 1% as systematic component and at 7% as statistical component. Uncertainty due to the fission product nuclear data is estimated at 3% as statistical component. Uncertainty in a high temperature range is negligible. Uncertainty in a coolant-voided situation is negligible. Uncertainty due to fuel depletion is negligible. Uncertainty due to control rod position is estimated at 1.7% as statistical component. Uncertainty due to approximated treatment of temperature dependence of Doppler coefficient is estimated at 3% as statistical component. Uncertainty due to averaged fuel temperature is estimated at 0.8% as systematic component and at 1.2% as statistical component. Uncertainty due to the approximated treatment of temperature spatial distribution is estimated at 1.5% as systematic component. Uncertainty for Doppler coefficient is estimated at 11.7%. (author)

2011-01-01

176

Doppler Lidar for Wind Measurements on Venus  

Science.gov (United States)

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.

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

2010-01-01

177

Doppler angle correction in the measurement of intrarenal parameters  

Directory of Open Access Journals (Sweden)

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 is produced only when the Doppler angle is 0°, so that the emission sound beam is parallel to the direction of blood flow at the sampled artery. Therefore, the Doppler angle correction should be routinely applied and displayed on renal color duplex sonography.Keywords: color duplex sonography, blood flow velocity, Doppler angle, Doppler shift, kidney

Mennitt K

2011-03-01

178

Doppler lidar atmospheric wind sensor - Reevaluation of a 355-nm incoherent Doppler lidar  

Science.gov (United States)

Reliable Nd:YAG laser technology and currently available optical sensors are presently used to reevaluate the performance of an incoherent Doppler lidar system operating at 354.7 nm. This system makes a more efficient use of output laser power than heretofore possible through a matching of the usable and detectable field of view of the Fabry-Perot interferometer receiver with that of the transmitter. Major advantages accrue to this system from the lower output power requirement, which is a primary cost driver for the prospective Spaceborne Doppler Wind Lidar.

Rees, David; Mcdermid, I. Stuart

1990-01-01

179

Principales aplicaciones del Doppler color transvaginal Main applications of transvaginal color doppler  

Directory of Open Access Journals (Sweden)

Full Text Available Se realiza una revisión bibliográfica acerca de esta novedosa técnica ecográfica (doppler color. Se indican sus principales aplicaciones en Obstetricia durante el primer trimestre del embarazo debido a sus manifiestas ventajas sobre otras técnicas. Se destaca también la importancia que tiene para la detección y control de afecciones de la esfera ginecológica.A bibliographic review is made on this novel echographic technique (doppler color. Its main applications in Obstetrics during the first trimester of pregnancy are suggested due to its advantages upon other techniques. The importance of this technique for the detection and control of disorders within the gynecologic field are also highlighted.

Miguel Pérez Ramírez

1997-12-01

180

Rotational Doppler effect in left-handed materials  

CERN Document Server

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 energy flow but a downstream momentum flow. In the anomalous dispersion region, however, the rotational Doppler effect produces a downstream energy flow but a upstream momentum flow. We theoretically predict that the rotational Doppler effect can induce a transfer of angular momentum of the LHM to orbital angular momentum of the beam.

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

2008-01-01

 
 
 
 
181

Is tissue Doppler echocardiography the Holy Grail for the intensivist?  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Assessment of left ventricular diastolic function in the critically ill patient remains a difficult issue in clinical practice. Combined use of routine transmitral and pulmonary venous Doppler patterns in conjunction with tissue Doppler imaging have been claimed to allow bedside diagnosis of diastolic dysfunction. Although in the previous issue of Critical Care it was clearly demonstrated there might be a difference in load dependency of the early myocardial tissue Doppler velocity between la...

2007-01-01

182

Active Region Moss: Doppler Shifts from Hinode/EIS Observations  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Studying the Doppler shifts and the temperature dependence of Doppler shifts in moss regions can help us understand the heating processes in the core of the active regions. In this paper we have used an active region observation recorded by the Extreme-ultraviolet Imaging Spectrometer (EIS) onboard Hinode on 12-Dec-2007 to measure the Doppler shifts in the moss regions. We have distinguished the moss regions from the rest of the active region by defining a low density cut-of...

Tripathi, Durgesh; Mason, Helen E.; Klimchuk, James A.

2012-01-01

183

Doppler US evaluation of the hypertensive portal system  

International Nuclear Information System (INIS)

In patients with known portal hypertension, pulsed Doppler US was used for qualitative and directional evaluation of flow in the portal venous system and collateral vessels. Most patients had normal hepatopetal flow. Doppler US revealed the following abnormal blood flow patterns: hepatofugal portal flow, bidirectional portal flow, intrahepatic portal shunting, flow in portasystemic collaterals, and hepatic vein obstruction. Doppler US can provide important clinical information in the evaluation of portal hypertension

1986-12-05

184

Influence of Doppler Bin Width on GNSS Detection Probabilities  

CERN Document Server

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

Geiger, Bernhard C

2011-01-01

185

Applications of Doppler ultrasound in clinical vascular disease  

Science.gov (United States)

Doppler ultrasound has become the most useful and versatile noninvasive technique for objective evaluation of clinical vascular disease. Commercially available continuous-wave instruments provide qualitative and quantitative assessment of venous and arterial disease. Pulsed Doppler ultrasound was developed to provide longitudinal and transverse cross-sectional images of the arterial lumen with a resolution approaching that of conventional X-ray techniques. Application of Doppler ultrasound in venous, peripheral arterial, and cerebrovascular diseases is reviewed.

Barnes, R. W.; Hokanson, D. E.; Sumner, D. S.; Strandness, D. E., Jr.

1975-01-01

186

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

2010-01-01

187

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

Science.gov (United States)

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

Wani, Mohd Lateef; Sheikh, Mohamad Tufail; Nayeem-ul-Hassan; Irshad, Ifat; Ahangar, Abdul Gani; Ganie, Farooq Ahmad; Sheikh, Mohd Tafazul; Wani, Shadab Nabi

2014-01-01

188

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

Directory of Open Access Journals (Sweden)

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.

Luca Giugno

2007-05-01

189

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

Directory of Open Access Journals (Sweden)

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.

Zanier Francesca

2007-01-01

190

Anemometrie Laser a Effect Doppler Miniaturise a Diode Laser (Laser Doppler Anemometer Miniaturized with Diode Laser).  

Science.gov (United States)

An 11 by 4 by 4 cm miniaturized laser Doppler anemometer system using laser diodes is described. The system was tested with a velocity profile of a free jet. The use of synthetic resin optics would improve the miniaturization and reduce the cost of this t...

S. Damp H. Pfeifer

1989-01-01

191

VW Hyi: optical spectroscopy and Doppler tomography  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We present high quality optical spectroscopy of the SU UMa-subtype dwarf nova, VW Hyi taken while the system was in quiescence. An S-wave is executed by the emission cores of the Hydrogen Balmer lines and by the emission lines of He I, Ca II, Fe II and He II. Using Doppler tomography we show it originates in the accretion stream-disc impact region. The He II emission is strongly phase-dependent, suggesting it originates exclusively within a hot cavity at the initial impact. ...

Smith, Amanda J.; Haswell, Carole A.; Hynes, Robert I.

2006-01-01

192

Doppler cooling to the Quantum limit  

CERN Document Server

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.

Chalony, Maryvonne; Klappauf, Bruce; Wilkowski, David

2011-01-01

193

Dealiasing Doppler velocites using edge detection  

Science.gov (United States)

This study presents a new algorithm to dealias folded Doppler velocities in S, C, and X-Band radars using a new boundary detection technique on the raw velocity field as a whole, rather than the traditional gate by gate methodology used in more popular and widespread algorithms. Several different types of precipitation events are used to compare and contrast the final output of the new boundary based algorithm. The results are then compared to the NEXRAD dealiasing algorithm as defined by Eilts and Smith (1989) and an objective manual unfolding by radar manipulation software called SoloII.

Meech, Scott P.

194

Doppler cooling of a Coulomb crystal  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We study theoretically Doppler laser cooling of a cluster of two-level atoms confined in a linear ion trap. Using several consecutive steps of averaging we derive, from the full quantum-mechanical master equation, an equation for the total mechanical energy of a one-dimensional crystal, defined on a coarse-grained energy scale whose grid size is smaller than the linewidth of the electronic transition. This equation describes the cooling dynamics for an arbitrary number of ions in the quantum ...

Morigi, Giovanna

2001-01-01

195

Tecnología Doppler y movimientos respiratorios fetales  

Scientific Electronic Library Online (English)

Full Text Available SciELO Venezuela | Language: Spanish Abstract in spanish La tecnología ultrasónica Doppler ha resultado ser una herramienta fundamental para la evaluación de la fisiología fetal, dando información importante sobre el estado hemodinámico fetal. Teniendo en cuenta que no sólo el desarrollo y crecimiento normal del feto y su bienestar intraútero depende de u [...] na adecuada función de la circulación útero placentaria y feto placentaria, sino de otras estructuras orgánicas, es por lo que este método abre una línea de investigación dentro del campo de la fisiología fetal. El propósito de esta revisión es exponer de forma clara los conceptos relacionados con el desarrollo y fisiología de la respiración fetal abordando técnicas no invasivas de evaluación del bienestar fetal como la tecnología Doppler color y con la cual es posible estudiar el movimiento del líquido amniótico a través del flujo transnasal. Es pues factible analizar, cualitativa y cuantitativamente, las ondas de velocidad de dicho flujo a través del análisis espectral de los movimientos respiratorios fetales, relacionados íntimamente con la máxima producción de esteroides fetales responsables de la madurez pulmonar fetal. Se presentan las diferentes metodologías y recursos diagnósticos aplicados en los últimos años en la evaluación de los movimientos respiratorios en el bienestar fetal y su importancia. Se realiza una breve descripción de la fisiología y desarrollo del sistema respiratorio fetal. Abstract in english Doppler ultrasound technology has been the main tool for monitoring fetal physiology, giving important information about fetal haemodinamic status. We are aware that normal fetal growing and development and its intra womb wellbeing depends on an accurate uterus - placental blood circulation as fetal [...] - placental, but with other organic structures, and this is the reason why this method opens a wide investigation line in the field of fetal physiology. Our purpose is to expose clearly the concepts involved in fetal breath development and physiology with non invasive techniques of fetal wellbeing such as color Doppler technology, by witch is possible to study the movement of amniotic flux through transnasal flux, as we can evaluate qualitatively and quantitatively by the velo-city waves of such flux through the spectral analysis of fetal breath movements, closely related to the higher production of fetal steroids responsible of fetal lung maturation. Different methodologies are presented and diagnostic resources applied in this last years over the breath movements and its relation to fetal wellbeing and its importance. We also do a description of fetal breath system development and physiology.

Marisol, García Noguera de Yegüez; Efraín, Inaudy Bolívar.

196

Signal broadening in the laser Doppler velocimeter.  

Science.gov (United States)

Critical review of a recent paper in which Denison, Stevenson, and Fox (1971) discussed the sources of spectral broadening in the laser Doppler velocimeter. It is pointed out that, in their discussion, the above-mentioned authors indicated that the spread in wave vectors of the incident and detected fields and the finite length of time a scattering center stayed in the sample volume each contributed separately and independently to the observed spectral width of the scattered radiation. This statement is termed incorrect, and it is shown that the two effects are one and the same.

Angus, J. C.; Edwards, R. V.; Dunning, J. W., Jr.

1971-01-01

197

Solar Doppler shifts - Sources of continuous spectra  

Science.gov (United States)

Oscillation observations can be used to study nonoscillatory solar phenomena that exhibit Doppler shifts. The paper discusses several effects of these phenomena and their associated temporal and spatial power spectra: (1) they limit the signal-to-noise ratio and sometimes detectability of oscillation modes; (2) there is the potential for better understanding and/or detection of solar phenomena; (3) large-scale convection may spatially modulate oscillation modes, leading to a continuous background spectrum; and (4) in regions of the spectrum where the resolution to separate modes is lacking one can determine upper limits for the integrated effects of modes.

Duvall, T. L., Jr.; Harvey, J. W.

1986-01-01

198

Using Spectral Edge To Measure Doppler Shift  

Science.gov (United States)

New pulsed-laser ranging systems implement spectral-edge technique making high-resolution measurements of Doppler frequency shift in signals backscattered from targets. Pulsed laser emits at ultraviolet, visible, or infrared wavelength suitable for generation of desired target. Optical filter ("edge" filter) has sharp spectral transmission function such that middle frequency of laser emission lies on steep portion of slope ("edge") on one side of peak. Frequency inferred from relative amplitudes of signal with and without filtering. Intended for use in measuring velocities of solid and diffuse moving targets like wind, clouds, aerosols, or rain. Applications include measurements of wind shear from airports and aircraft.

Korb, Lawrence

1992-01-01

199

Doppler Tomographic Observations of Kepler-13b  

Science.gov (United States)

We present Doppler tomographic observations of the transiting planet Kepler-13b (aka KOI-13b), a highly inflated hot Jupiter orbiting the Teff =8500 K primary of a hierarchical triple stellar system. As the planet transits the rapidly rotating host star, it successively blocks regions of the stellar disk with different radial velocities, causing a ``bump'' in the stellar spectral line shape, which we resolve spectroscopically. The manner in which this perturbation moves across the stellar line during the transit gives information on the relative alignment between the stellar spin and planetary orbital angular momentum vectors. This is a powerful statistical probe of planetary migration processes, as the expected spin-orbit misalignment distributions from dynamically cold migration (disk interactions) and dynamically hot migration (planet-planet scattering, Kozai cycles) are significantly different: the former will lead to primarily aligned orbits; the latter to a wide distribution. Doppler tomography also promises to be a powerful technique for confirming transiting planet candidates around rapidly rotating stars like Kepler-13A, which are not amenable to radial velocity follow-up and thus are currently a poorly sampled region of parameter space.

Johnson, Marshall C.; Cochran, William D.

2014-01-01

200

Color Doppler Ultrasonographic Features of Hashimoto's Thyroiditis  

International Nuclear Information System (INIS)

Color Doppler ultrasonographic(US) features of 28 patients with Hashimato's thyroiditis were evaluated with regard to echo and color-flow patterns. Correlation of color-flow pattern with thyroid function was performed. All 28 patients showed varying degrees of diffuse enlargement of the thyroid gland and a heterogeneous echo pattern.Color-flow pattern of increased blood flow. Low to moderate, focally increased blood flow was seen in 26 patients(92.8%). Of these 26 patients, 24 patients showed subclinical hypothyroidism or euthyroidism. Two patients who showed hyperthyroidism showed several pieces of focally increased color flow, Which was noted during both systole and diastole. Diffuse, multifocal color-flow throughout thyroid gland was seen in two patients with Hashimato's thyroiditis: one with clinical hypothyroidism and the other with subclinical hypothyroidism. Even though Hashimoto's thyroiditis showed variable color-flow patterns, we believe that heterogenous parenchymal echopattern with low or moderately increased flow is a rather characteristic feature of Hashimoto's thyroiditis, and we suggest that color Doppler US provides additional information for evaluation of Hashimoto's thyroiditis

1995-06-01

 
 
 
 
201

Ambiguity resolution for satellite Doppler positioning systems  

Science.gov (United States)

The implementation of satellite-based Doppler positioning systems frequently requires the recovery of transmitter position from a single pass of Doppler data. The least-squares approach to the problem yields conjugate solutions on either side of the satellite subtrack. It is important to develop a procedure for choosing the proper solution which is correct in a high percentage of cases. A test for ambiguity resolution which is the most powerful in the sense that it maximizes the probability of a correct decision is derived. When systematic error sources are properly included in the least-squares reduction process to yield an optimal solution the test reduces to choosing the solution which provides the smaller valuation of the least-squares loss function. When systematic error sources are ignored in the least-squares reduction, the most powerful test is a quadratic form comparison with the weighting matrix of the quadratic form obtained by computing the pseudoinverse of a reduced-rank square matrix. A formula for computing the power of the most powerful test is provided. Numerical examples are included in which the power of the test is computed for situations that are relevant to the design of a satellite-aided search and rescue system.

Argentiero, P.; Marini, J.

1979-01-01

202

Comparison of Triature Doppler Velocimetry and VISAR  

International Nuclear Information System (INIS)

Triature Photonic Doppler Velocimetry (TDV) is an adaptation of Photonic Doppler Velocimetry (PDV) that rejects common-mode data noise after splitting PDV three ways, with each signal 120o out of phase from each other. Testing has demonstrated that TDV also improves temporal resolution from the typical five nanoseconds of PDV to a subnanosecond range. This paper compares the temporal response of TDV with that of PDV and VISAR (velocity interferometer system for any reflector) in an experiment with a subnanosecond (?120-picosecond rise time) shock source. Laboratory tests were performed using a high-power laser on targets of copper and aluminum. A Buce Marshall fast VISAR with a single-point PDV and a prototype TDV were used. A special probe that combined PDV, TDV, and fast VISAR made simultaneous velocity measurements. Breakout velocities of 1.3 km/second on copper and 2.5 km/second on aluminum were observed, where TDV resolved rise times of ?200 ps. This resolution was better than that of a fast VISAR, which can achieve ?500 ps temporal resolution. Test methods and results are presented.

2009-09-06

203

Comparison of Triature Doppler Velocimetry and Visar  

International Nuclear Information System (INIS)

Triature Photon Doppler Velocimetry (TDV) is an adaptation of Photonic Doppler Velocimetry (PDV) that rejects common-mode data noise after splitting PDV three ways, with each signal 1200 out of phase from each other. Testing has demonstrated that the TDV also improves temporal resolution from the typical five-nanoseconds of PDV to a subnanosecond range. This paper compares the temporal response of TDV with that of PDV and VISAR [velocity interferometer system for any reflector] in an experiment with a subnanosecond (?120-picosecond rise time) shock source. Laboratory tests were performed using a high-power laser on targets of copper and aluminum. A fast VISAR with a single-point PDV and a prototype TDV were used. A special probe that combined PDV, TDV, and fast VISAR made simultaneous velocity measurements. Breakout velocities of 1.3 km/second on copper and 2.5 km/second on aluminum were observed, where TDV resolved rise times of ?200 ps. This resolution was better than that of a fast VISAR, which can achieve ?500 ps temporal resolution. Test methods and results are presented.

2010-08-01

204

Doppler broadening measurements in ?-irradiated LiF  

International Nuclear Information System (INIS)

Positron annihilation in ?-irradiated LiF crystals is studied by investigation of the Doppler broadening of the 511 keV annihilation line. The change of the lineshape parameter S with the radiation dose is interpreted in terms of the Sonder's model. The validity of the model in interpretation of results of Doppler broadening measurements is discussed. (author)

1985-12-16

205

Weighted least squares formulas for multiple Doppler radar analysis  

Science.gov (United States)

An algorithm is developed for the analysis of multiple Doppler radar data in meteorological applications. The algorithm is based on the least squares linear solutions for the variable parameters of a local particle velocity field. The computational sequence for the algorithm is described, and some factors influencing the covariance of Doppler measurement errors are discussed.

Wilson, F. W., Jr.

1983-01-01

206

Cervicocranial artery dissection. Detection by Doppler ultrasound and MR angiography  

International Nuclear Information System (INIS)

Purpose: To evaluate pulsed Doppler ultrasound and MR angiography (MRA) in the diagnosis of cervicocranial dissection. Material and Methods: Fourteen patients with cervicocranial artery dissection were examined over a 3-year period. Twelve patients had dissection of the extracranial part of the internal carotid artery, and 2 had vertebral artery dissection. All patients were examined with pulsed Doppler ultrasound. In addition, all patients had conventional angiography (n=9) and/or MR imaging including MRA (n=9). Results: Doppler ultrasound disclosed unspecific abnormalities in 11 of 14 dissected vessels; 3 patients had false-negative Doppler findings. MRA showed vessel abnormalities in 9 of 9 patients; 2 vessels were occluded, and 7 vessels had changes typical of dissection (double lumen and/or string sign). Twelve patients had follow-up examinations with pulsed Doppler ultrasound (n=12), conventional angiography (n=3), and MRA/MR (n=11). Follow-up Doppler showed complete or partial normalization in 6 of 9 patients, all confirmed by either angiography or MRA. Conclusion: Our findings suggest that Doppler ultrasound may be used in follow-up of pathologic Doppler findings in known dissections, and that MRA may replace angiography in the confirmative diagnosis of cervicocranial dissection. (orig.)

1996-07-01

207

Analysis of Doppler effect with JAERI-Fast set  

International Nuclear Information System (INIS)

Temperature dependence of group cross sections in the JAERI-Fast set versions I, IR, II and IIR has been tested from the analysis of Doppler experiments performed with two different methods. One is Doppler reactivity measurement for the whole core of SEFOR assembly, and the other sample Doppler reactivity measurement for natural UO_2 in FCA assemblies V-1, V-2, VI-1 and VI-2, ZPR-6-7, ZPR-3-47, and ZPPR-2 and 3. Doppler effects were calculated with one- and two-dimensional diffusion 1-st order perturbation code DOPP2D. The results calculated with the JAERI-Fast set versions II and IIR are in good agreement with the experimental ones. In these calculation, resonance heterogeneity effect, stainless-stell buffer effect and plate heterogeneity effect are considered, and these effects contribute significantly to Doppler effect. (auth.)

1977-01-01

208

Doppler-cancelled response to VLF gravitational waves  

Science.gov (United States)

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

Caporali, A.

1981-01-01

209

Ionospheric Doppler measurements by means of HF-radar techniques  

Directory of Open Access Journals (Sweden)

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.

D. Altadill

2005-06-01

210

Rotational Doppler effect in x-ray photoionization  

International Nuclear Information System (INIS)

The energy of the photoelectron experiences a red or blue Doppler shift when the molecule recedes from the detector or approaches him. This results in a broadening of the photoelectron line due to the translational thermal motion. However, the molecules also have rotational degrees of freedom and we show that the translational Doppler effect has its rotational counterpart. This rotational Doppler effect leads to an additional broadening of the spectral line of the same magnitude as the Doppler broadening caused by translational thermal motion. The rotational Doppler broadening as well as the rotational recoil broadening is sensitive to the molecular orbital from which the photoelectron is ejected. This broadening should be taken into account in analysis of x-ray photoemission spectra of super-high resolution and it can be directly observed using x-ray pump-probe spectroscopy.

2010-11-01

211

Breast Discharge: Ultrasound and Doppler Evaluation  

International Nuclear Information System (INIS)

Nipple discharge causes discomfort and anxiety to many women. Nipple discharge is most commonly associated with endocrine alterations and/or medications. These often result in duct ectasia and/or fibrocystic changes that may lead to discharge from one or several ducts. The most common cause of clinically significant discharge is intra ductal growth of the ductal epithelium, due to hyperplasia, micro papillary proliferation, solitary papillomas and/or ductal carcinoma (both in situ and invasive). The aim of the study was to evaluate the role of the gray-scale ultrasound and colour Doppler in the diagnosis of intra ductal pathology in patients with nipple discharge. Patients and Methods: One hundred and seven patients were included in the study, (age range 23-65 years). Standard mammographic views were taken. Ultrasound evaluation was performed for all cases; ductography for 20 cases and ductoscopy for 3 cases. US guided fine needle biopsy was done in 7 cases; microducectomy of affected duct was done in 20 cases and major duct excision in 5 cases. Fibro-optic Ductoscopy is performed for 3 cases. Results: Revision of biopsy specimens of 17 cases with intraluminal masses detected by US revealed: Six cases with intraductal carcinoma, intraductal papilloma in 7 cases, 1 case of ductal papillomatosis. Three cases showed atypical cells: Intra ductal papilloma with atypia in 2 cases, proliferative hyperplasia with atypia in one case. Eighty eight cases had simple duct ectasia (51 bilateral multiple and 37 focal duct ectasia). No dilated ducts were detected in 2 cases. Fibro-optic Ductoscopy confirmed the presence of intra ductal papilloma in one case, carcinoma in one case, no intra ductal masses in the third case. A 6 months follow-up was requested for all cases with no detected intra luminal pathology. Ultrasound examination is highly sensitive (100%) but less specific (82.4%) in diagnosis of intra ductal pathology. Colour and power Doppler are sensitive (94%) in detecting flow in intra ductal echogenic masses to differentiate them from insipissated secretions. Colour and power Doppler raises specificity and diagnostic accuracy to 100%. Ductography is an under used procedure that is sensitive (100%) but less specific (60%) in characterization of intra ductal filling defects. Conclusion: Ultrasonography is a mandatory complement to mammography in these cases, US guided fine needle biopsy is minimally invasive technique in confirming the diagnosis of suspicious mass. Ultrasound may also be a guide to fib ro-optic decapitates.

2008-09-01

212

Principales aplicaciones del Doppler color transvaginal / Main applications of transvaginal color doppler  

Scientific Electronic Library Online (English)

Full Text Available SciELO Cuba | Language: Spanish Abstract in spanish Se realiza una revisión bibliográfica acerca de esta novedosa técnica ecográfica (doppler color). Se indican sus principales aplicaciones en Obstetricia durante el primer trimestre del embarazo debido a sus manifiestas ventajas sobre otras técnicas. Se destaca también la importancia que tiene para l [...] a detección y control de afecciones de la esfera ginecológica. Abstract in english A bibliographic review is made on this novel echographic technique (doppler color). Its main applications in Obstetrics during the first trimester of pregnancy are suggested due to its advantages upon other techniques. The importance of this technique for the detection and control of disorders withi [...] n the gynecologic field are also highlighted.

Miguel, Pérez Ramírez; Inés, Fernández Fernández; Eusebio, Mulet Matos.

213

Laser Doppler vibrometer employing active frequency feedback  

International Nuclear Information System (INIS)

We present a heterodyne Michelson interferometer for vibration measurement in which feedback is used to obviate the need to unwrap phase data. The Doppler shift of a vibrating target mirror is sensed interferometrically and compensated by means of a voltage-controlled oscillator driving an acousto-optic modulator. For frequencies within the servo bandwidth, the oscillator control voltage provides a direct measurement of the target velocity. Outside the servo bandwidth, phase-sensitive detection is used to evaluate high-frequency displacements. This approach is of great interest for the frequently-occurring situation where vibration amplitudes at low frequency exceed an optical wavelength, but knowledge of the vibration spectrum at high frequency is important as well

2008-09-20

214

Implementation of Doppler backscattering for MAST  

CERN Document Server

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...

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

2014-01-01

215

Pulsed laser Doppler measurements of wind shear  

Science.gov (United States)

There is a need for a sensor at the airport that can remotely detect, identify, and track wind shears near the airport in order to assure aircraft safety. To determine the viability of a laser wind-shear system, the NASA pulsed coherent Doppler CO2 lidar (Jelalian et al., 1972) was installed in a semitrailer van with a rooftop-mounted hemispherical scanner and was used to monitor thunderstorm gust fronts. Wind shears associated with the gust fronts at the Kennedy Space Center (KSC) between 5 July and 4 August 1978 were measured and tracked. The most significant data collected at KSC are discussed. The wind shears were clearly visible in both real-time velocity vs. azimuth plots and in postprocessing displays of velocities vs. position. The results indicate that a lidar system cannot be used effectively when moderate precipitation exists between the sensor and the region of interest.

Dimarzio, C.; Harris, C.; Bilbro, J. W.; Weaver, E. A.; Burnham, D. C.; Hallock, J. N.

1979-01-01

216

The Doppler peaks from a generic defect  

CERN Document Server

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'')

Magueijo, J

1996-01-01

217

Laser Doppler vibrometry: new ENT applications  

Science.gov (United States)

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

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

1996-12-01

218

Cyclotron maser using the anomalous Doppler effect  

Science.gov (United States)

The operation of an anomalous-Doppler-effect cyclotron-resonance maser using a waveguide partially filled with dielectric as the slow-wave system is reported. The device investigated is similar to that of Didenko et al. (1983) and comprises a 300-mm-long 50-mm-o.d. 30-mm-i.d. waveguide with fabric-laminate dielectric, located 150 mm from the cathode in a 500-mm-long region of uniform 0-20-kG magnetic field, and a coaxial magnetic-insulation gun producing a 13-mm-i.d. 25-mm-o.d. hollow electron beam. Radiation at 12 + or - 1 mm wavelength and optimum power 20 MW is observed using hot-carrier detectors, with a clear peak in the power-versus-magnetic-field curve at about 6.4 kG.

Didenko, A. N.; Borisov, A. R.; Fomenko, G. P.; Shlapakovskii, A. S.; Shtein, Iu. G.

1983-11-01

219

Morfologia duplex Doppler dos principais vasos sanguíneos abdominais em pequenos animais Duplex Doppler morphology of major abdominal blood vessels in small animals  

Directory of Open Access Journals (Sweden)

Full Text Available A ultra-sonografia duplex Doppler é capaz de fornecer informações anatômicas e hemodinâmicas em tempo real. O conhecimento do espectro Doppler normal de cada vaso sanguíneo é importante na sua identificação, pois cada vaso possui um sinal Doppler específico. Reconhecer as alterações de morfologia do espectro somente é possível mediante o conhecimento das variações na normalidade. O objetivo deste artigo foi revisar as informações publicadas em literatura que descrevem o padrão Doppler normal dos principais vasos sanguíneos abdominais de pequenos animais.Duplex Doppler ultrasonography is able to provide real time anatomic and hemodynamic information. The complete knowledge of the normal Doppler spectrum of each blood vessel is important to their identification, since each vessel has a specific Doppler sign. Recognizing the changes in the morphology of Doppler spectrum is only possible based on previous knowledge of its variations. This is a literature review about Doppler pattern of the major abdominal blood vessels in small animals.

Cibele Figueira Carvalho

2008-06-01

220

Role of colour doppler sonography in adnexal masses  

Directory of Open Access Journals (Sweden)

Full Text Available Objective: To evaluate the role of colour Doppler sonography in differentiating between benign and malignant adnexal masses. Materials & Methods: One hundred women diagnosed with adnexal masses underwent colour Doppler sonography. Resistance index (RI and Pulsatility index (PI were calculated in each case and lowest RI and PI obtained at any point in the mass were considered for analysis. Masses which were completely a vascular were considered as benign. Histopathological diagnosis was obtained in each case. Sensitivity, specificity, positive predictive value, negative predictive value and accuracy of colour Doppler were calculated. Results: Mean RI and Mean PI were significantly lower in malignant masses (0.34 & 0.95 respectively as compared to benign masses (0.72 & 1.97 respectively. Out of 81 benign cases, Doppler could correctly diagnose 78 cases as benign, but labelled 3 cases as malignant which were actually benign. Out of 19 malignant cases, 16 cases were correctly diagnosed, whereas 3 cases were missed by Doppler. Our study showed a sensitivity of 84.2%, specificity of 96.3%, positive predictive value of 84.2%, negative predictive value of 96.3% and accuracy of 94% for colour Doppler. Conclusion: Colour Doppler sonography is helpful in differentiating benign from malignant adnexal masses.

Shazia Ashraf Khan, Aamina Banoo

2014-04-01

 
 
 
 
221

Calibrated image-derived input functions for the determination of the metabolic uptake rate of glucose with [18F]-FDG PET  

DEFF Research Database (Denmark)

PURPOSE: We investigated the use of a simple calibration method to remove bias in previously proposed approaches to image-derived input functions (IDIFs) when used to calculate the metabolic uptake rate of glucose (K(m)) from dynamic [(18)F]-FDG PET scans of the thigh. Our objective was to obtain nonbiased, low-variance K(m) values without blood sampling. MATERIALS AND METHODS: We evaluated eight previously proposed IDIF methods. K(m) values derived from these IDIFs were compared with Km values calculated from the arterial blood samples (gold standard). We used linear regression to extract calibration parameters to remove bias. Following calibration, cross-validation and bootstrapping were used to estimate the mean square error and variance. RESULTS: Three of the previously proposed methods failed mainly because of zero-crossings of the IDIF. The remaining five methods were improved by calibration, yielding unbiased Km values. The method with the lowest SD yielded an SD of 0.0017/min--that is, below 10% of the muscle K(m) value in this study. CONCLUSION: Previously proposed IDIF methods can be improved by using a simple calibration procedure. The calibration procedure may be used in other studies, thus obviating the need for arterial blood sampling, once the calibration parameters have been established in a subgroup of participants. The method has potential for use in other parts of the body as it is robust with regard to partial volume effects.

Christensen, Anders N; Reichkendler, Michala H

2014-01-01

222

Characterization of the image-derived carotid artery input function using independent component analysis for the quantitation of [18F] fluorodeoxyglucose positron emission tomography images  

International Nuclear Information System (INIS)

We previously developed a noninvasive technique for the quantification of fluorodeoxyglucose (FDG) positron emission tomography (PET) images using an image-derived input function obtained from a manually drawn carotid artery region. Here, we investigate the use of independent component analysis (ICA) for more objective identification of the carotid artery and surrounding tissue regions. Using FDG PET data from 22 subjects, ICA was applied to an easily defined cubical region including the carotid artery and neighboring tissue. Carotid artery and tissue time activity curves and three venous samples were used to generate spillover and partial volume-corrected input functions and to calculate the parametric images of the cerebral metabolic rate for glucose (CMRgl). Different from a blood-sampling-free ICA approach, the results from our ICA approach are numerically well matched to those based on the arterial blood sampled input function. In fact, the ICA-derived input functions and CMRgl measurements were not only highly correlated (correlation coefficients >0.99) to, but also highly comparable (regression slopes between 0.92 and 1.09), with those generated using arterial blood sampling. Moreover, the reliability of the ICA-derived input function remained high despite variations in the location and size of the cubical region. The ICA procedure makes it possible to quantify FDG PET images in an objective and reproducible manner

2007-12-07

223

Processor operated correlator with applications to laser Doppler signals  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

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

2009-01-01

224

Ultrasonic Doppler measurement of renal artery blood flow  

Science.gov (United States)

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

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

1976-01-01

225

Pulse-Doppler Signal Processing with Quadrature Compressive Sampling  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Quadrature compressive sampling (QuadCS) is a newly introduced sub-Nyquist sampling for acquiring inphase and quadrature (I/Q) components of radio-frequency signals. For applications to pulse-Doppler radars, the QuadCS outputs can be arranged in 2-dimensional data similar to that by Nyquist sampling. This paper develops a compressive sampling pulse-Doppler (CoSaPD) processing scheme from the sub-Nyquist samples. The CoSaPD scheme follows Doppler estimation/detection and rang...

Liu, Chao; Xi, Feng; Chen, Shengyao; Liu, Zhong

2013-01-01

226

Measurement depth and volume in laser Doppler flowmetry  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A new method for estimating the measurement depth and volume in laser Doppler flowmetry (LDF) is presented. The method is based on Monte Carlo simulations of light propagation in tissue. The contribution from each individual Doppler shift is calculated and thereby multiple Doppler shifts are handled correctly. Different LDF setups for both probe based (0.0, 0.25, 0.5, and 1.2 mm source-detector separation) and imaging systems (0.5 and 2.0 mm beam diameter) are considered, at the wavelengths 5...

Fredriksson, Ingemar; Larsson, Marcus; Stro?mberg, Tomas

2009-01-01

227

An audit of a hospital-based Doppler ultrasound quality control protocol using a commercial string Doppler phantom.  

Science.gov (United States)

Results from a four-year audit of a Doppler quality assurance (QA) program using a commercially available Doppler string phantom are presented. The suitability of the phantom was firstly determined and modifications were made to improve the reliability and quality of the measurements. QA of Doppler ultrasound equipment is very important as data obtained from these systems is used in patient management. It was found that if the braided-silk filament of the Doppler phantom was exchanged with an O-ring rubber filament and the velocity range below 50 cm/s was avoided for Doppler quality control (QC) measurements, then the maximum velocity accuracy (MVA) error and intrinsic spectral broadening (ISB) results obtained using this device had a repeatability of 18 ± 3.3% and 19 ± 3.5%, respectively. A consistent overestimation of the MVA of between 12% and 56% was found for each of the tested ultrasound systems. Of more concern was the variation of the overestimation within each respective transducer category: MVA errors of the linear, curvilinear and phased array probes were in the range 12.3-20.8%, 32.3-53.8% and 27-40.7%, respectively. There is a dearth of QA data for Doppler ultrasound; it would be beneficial if a multicentre longitudinal study was carried out using the same Doppler ultrasound test object to evaluate sensitivity to deterioration in performance measurements. PMID:24156827

Cournane, S; Fagan, A J; Browne, J E

2014-05-01

228

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.)

2005-01-01

229

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

Energy Technology Data Exchange (ETDEWEB)

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.)

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

230

Doppler electron velocimetry : notes on creating a practical tool.  

Energy Technology Data Exchange (ETDEWEB)

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.

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

2008-11-01

231

Ambiguity Of Doppler Centroid In Synthetic-Aperture Radar  

Science.gov (United States)

Paper discusses performances of two algorithms for resolution of ambiguity in estimated Doppler centroid frequency of echoes in synthetic-aperture radar. One based on range-cross-correlation technique, other based on multiple-pulse-repetition-frequency technique.

Chang, Chi-Yung; Curlander, John C.

1991-01-01

232

Determining variability of ophthalmic arterial Doppler signals using Lyapunov exponents.  

Science.gov (United States)

The new method presented in this study was directly based on the consideration that ophthalmic arterial Doppler signals are chaotic signals. This consideration was tested successfully using the nonlinear dynamics tools, like the computation of Lyapunov exponents. Multilayer perceptron neural network (MLPNN) architecture was formulated and used as a basis for determining variabilities such as stenosis, ocular Behcet disease, and uveitis disease in the physical state of ophthalmic arterial Doppler signals. The computed Lyapunov exponents of the ophthalmic arterial Doppler signals were used as inputs of the MLPNN. Receiver operating characteristic (ROC) curve was used to assess the performance of the detection process. The ophthalmic arterial Doppler signals were classified with the accuracy varying from 93.75% to 97.06%. The results confirmed that the proposed MLPNN trained with Levenberg-Marquardt algorithm has potential in detecting stenosis, Behcet disease and uveitis disease in ophthalmic arteries. PMID:16136650

Ubeyli, Elif Derya; Güler, Inan

2005-06-01

233

The Doppler Effect: A Consideration of Quasar Redshifts.  

Science.gov (United States)

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)

Gordon, Kurtiss J.

1980-01-01

234

Coherent Doppler Lidar for Precision Navigation of Spacecrafts  

Science.gov (United States)

A fiber-based coherent Doppler lidar, utilizing an FMCW technique, has been developed and its capabilities demonstrated through two successful helicopter flight test campaigns. This Doppler lidar is expected to play a critical role in future planetary exploration missions because of its ability in providing the necessary data for soft landing on the planetary bodies and for landing missions requiring precision navigation to the designated location on the ground. Compared with radars, the Doppler lidar can provide significantly higher precision velocity and altitude data at a much higher rate without concerns for measurement ambiguity or target clutter. Future work calls for testing the Doppler lidar onboard a rocket-powered free-flyer platform operating in a closed-loop with the vehicle s guidance, navigation, and control (GN&C) unit.

Amzajerdian, Farzin; Pierrottet, Diego; Petway, Larry; Hines, Glenn; Lockhard, George; Barnes, Bruce

2011-01-01

235

Doppler Compensation by using of Segmented Match Filter  

Directory of Open Access Journals (Sweden)

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.

Nader Ghadimi

2008-09-01

236

The Martian Interior Structure from Landed Probe Doppler Tracking  

Science.gov (United States)

InSight carries a seismometer and other instruments including the Rotation and Interior Structure Experiment for precision Doppler tracking. It will constrain interior models by measuring the change in the spin axis direction as a function of time.

Asmar, S. W.; Folkner, W. M.; Dehant, V.; Banerdt, W. B.; Smrekar, S. E.

2014-06-01

237

Value of intraplacental villous artery Doppler measurements in severe preeclampsia.  

Directory of Open Access Journals (Sweden)

Full Text Available Blood flow velocity waveforms were recorded by color Doppler ultrasound from intraplacental villous and umbilical arteries in 20 normal and 23 severe preeclamptic pregnancies. The results of the resistance index measurements in intraplacental villous arteries were 0.51 +/- 0.037 and 0.55 +/- 0.052 in healthy controls and preeclamptics respectively, which was not significantly different. Resistance indices showed a decrease through the umbilical cord from fetus to placenta in both groups. We also noted that Doppler examination of the umbilical cord might be an early indicator of fetal compromise. Detectable intraplacental villous flows were in normal limits even in patients with abnormally high umbilical resistance indices and failure to detect villous artery color Doppler flow signals is probably associated with fetal compromise. We conclude that Doppler measurements from the intraplacental arteries cannot be used in clinical management of patients with severe preeclampsia.

Lacin S

1996-10-01

238

Quantitative Measurement of the Doppler Shift at an Ultrasonic Frequency  

Science.gov (United States)

Discussed is a Doppler shift laboratory experiment for an introductory college physics course. Ultrasonic transducers and a digital phase detector circuit "black box" are used to overcome room noise and "standing waves" and to produce an observable frequency shift. (SL)

Nerbun, R. C.; Leskovec, R. A.

1976-01-01

239

Doppler Shift and Spread Study for Ionospherically Propagated Signals.  

Science.gov (United States)

Modern, High Frequency (HF) communication techniques, such as spread spectrum and frequency hopping, require precise signal frequency information. The predominant HF propagation path is via the ionosphere, which often produces Doppler frequency shift and ...

N. Malachias

1994-01-01

240

DELAY-DOPPLER PERFORMANCE OF HYPERBOLIC FREQUENCY MODULATION WAVEFORMS  

Directory of Open Access Journals (Sweden)

Full Text Available Doppler effect plays a vital role and cannot be neglected for high velocity radars. When the velocity between the target and radar is very high compared to the velocity of transmitted waveform, then the received signal suffers Doppler distortion and will not match with the matched filter. Due to this, linear frequency modulation waveform suffers from a considerable signal loss. Use of hyperbolic frequency modulation eliminates this adverse effect. In this paper hyperbolic frequency modulation waveform is shown as Doppler-invariant when compared with linear frequency modulation. The desired Doppler-invariant property of the hyperbolic frequency modulation is very attractive for radars employing pulse compression techniques. Schematic ambiguity diagrams are presented for linear frequency modulation and hyperbolic frequency modulation waveforms

A.NAGAJYOTHI

2013-11-01

 
 
 
 
241

WIMS-AECL calculations for the Doppler coefficient of reactivity  

International Nuclear Information System (INIS)

The Doppler coefficient of reactivity is an important parameter in the evaluation of reactor transients. The Doppler feedback, associated with changes in fuel temperature when a reactor goes from hot zero power to hot full power, is a relatively small effect which is difficult to measure directly. WIMS-AECL calculations of the Doppler coefficient of reactivity are in excellent agreement with those predicted by MCNP-3A. It is shown that the WIMS-AECL lattice code, together with the WIMS ENDF/B-V data library, can predict the Doppler coefficient of light-water reactor fuel with good accuracy. The results can be used in SLOWPOKE, MAPLE, or other reactor calculations. 7 refs., 8 tabs

1992-06-07

242

Laser Doppler instrument measures fluid velocity without reference beam  

Science.gov (United States)

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.

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

1971-01-01

243

Using doppler radar images to estimate aircraft navigational heading error  

Energy Technology Data Exchange (ETDEWEB)

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.

Doerry, Armin W. (Albuquerque, NM); Jordan, Jay D. (Albuquerque, NM); Kim, Theodore J. (Albuquerque, NM)

2012-07-03

244

Doppler ultrasonographic changes in the canine kidney during normovolaemic anaemia  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The haemodynamics of the canine left renal artery (LRA) and interlobar artery (ILA) were evaluated in eleven fasted, healthy, conscious beagles with severe acute (haematocrit [Hct] 16%), moderate chronic (Hct 26%) and mild chronic (Hct 34%) normovolaemic anaemia using Doppler ultrasound. Heart rate, peak systolic velocity (PSV), end diastolic velocity (EDV), time-averaged mean velocity (TAVmean), pulsatility index (PI) and resistive index (RI) were recorded. Doppler values in the dogs followi...

2006-01-01

245

Convolution of a Doppler line by a Gaussian instrument function  

Science.gov (United States)

A simple and direct method is obtained for assessing the distortion of a Doppler line by a Gaussian instrument function. It is suggested that a close approximation to the width of a Gaussian instrument function, or an almost Gaussian function, may be obtained by measuring a line with a Doppler absorption coefficient. The method is applicable to diode laser measurements, and may be used whenever a Gaussian instrument function is a reasonable approximation to real conditions

Fridovich, B.; Devi, V. M.; Das, P. P.

1980-01-01

246

Transcranial Doppler ultrasound and cerebral angiography - alternative or complementary  

International Nuclear Information System (INIS)

Transcranial Doppler ultrasound is a noninvasive method of recording the flow velocity of larger intracranial vessels. The impact on diagnosis of cerebravascular occlusive disease is not yet evaluated. We present 15 patients, age range 39-73 years, who suffered from completed stroke. The findings of transcranial Doppler ultrasound and of cerebral angiography are presented. The value of both methods in treatment strategy is discussed. (orig.)

1985-01-01

247

Doppler hemodynamic study in evaluation of liver metastases  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The color Doppler spectral analyses can be usefully in description of the liver circulation as one from non-invasive methods. Using color Doppler B mod ultrasound (Toshiba Core Vision) with duplex ultrasound we founded difference in liver circulation between patients with colon cancer and liver metastasis in comparison with those without metastases. We suggested this non invasive method for early detection of occult liver metastasis presence. .

Stoj?i?-?eni? S.; Šarenac-Kova? R.; Kerkez M.; Juriši? V.

2007-01-01

248

Prospects for Doppler cooling of three-electronic-level molecules  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Analogous to the extension of laser cooling techniques from two-level to three-level atoms, Doppler cooling of molecules with an intermediate electronic state is considered. In particular, we use a rate-equation approach to simulate cooling of SiO+, in which population buildup in the intermediate state is prevented by its short lifetime. We determine that Doppler cooling of SiO+ can be accomplished without optically repumping from the intermediate state, at the cost of causi...

Nguyen, J. H. V.; Odom, B.

2010-01-01

249

Color Doppler Sonography in Healthy Old Persons, Vertebral Arteries  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Recently, color Doppler sonography is widely used in evaluating diseases obstructing brain arteries. This study aimed at providing normal rates of hemodynamic parameters in vertebral arteries of older patients using color Doppler sonography. This prospective study conducted on 31 healthy old people ranges from 60 to 96 years. Angle corrected flow velocities and luminal diameters were measured and waveform parameters calculated in all vertebral arteries. It was possible to visualize V2 S...

Abolhassan Shakeri; Masoud Nemati; Moslem Shakeri; Mohamad Goldust

2012-01-01

250

A simplified study of trans-mitral Doppler patterns  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Abstract Background Trans-mitral Doppler produces complex patterns with a great deal of variability. There are several confusing numerical measures and indices to study these patterns. However trans-mitral Doppler produces readymade data visualization by pattern generation which could be interpreted by pattern analysis. By following a systematic approach we could create an order and use this tool to study cardiac function. Presentation of the hypothesis In this ...

Thomas George

2008-01-01

251

Blood flow measurement by laser Doppler method in orofacial region  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Laser Doppler is a noninvasive, objective, reproducible and painless method for measuring blood flow in tissue microcirculation. This method is based on the Doppler effect, the change in frequency of light reflecting from blood cells in motion. Light from helium-neon laser through optical fibers and probes is directed to the surface of the tissue in which the flow is measured. Light portion is reflected from the cells in motion and changes the frequency while another portion is reflecte...

Grga ?urica; Dželetovi? Bojan; Živkovi? Slavoljub; Kršljak Elena

2010-01-01

252

Doppler-insensitive differential excitation of isotopic atoms  

International Nuclear Information System (INIS)

The differential excitation of two very similar isotopic atoms with overlapping Doppler, but not natural, linewidths is studied theoretically. It is found that the addition of a nuclear radiofrequency pulse to a laser pulse sequence can, in principle, achieve complete differential excitation when one isotope has zero nuclear spin and the other has an integer-plus-half nuclear spin. This differential excitation is insensitive to Doppler shifts and applies equally to all velocity classes of atoms in the sample. (author)

1981-05-28

253

Doppler angle correction in the measurement of intrarenal parameters  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 an...

2011-01-01

254

Digital Extraction Of Doppler Shift In An Advanced Receiver  

Science.gov (United States)

Report describes demonstration of ability of Advanced Receiver II (ARX II) to extract Doppler shifts in radio telemetry signals from spacecraft by digital processing. Frequency of sampling clock fixed and derived from frequency-and-timing subsystem. Although this can result in noninteger number of samples per symbol, it enables digital extraction of Doppler shift. ARX II operates with older receiver called "Block IV". ARX II performed at least as well as, and in most cases better than, Block IV.

Hinedi, Sami M.; Kinman, Peter W.; Bevan, Roland P.; Del Castillo, Hector M.; La Belle, Remi C.

1992-01-01

255

ULTRASONOGRAFÍA DOPPLER EN EMBARAZOS DE TÉRMINO CON OLIGOHIDROAMNIOS AISLADO  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Objetivos: Evaluar la unidad feto placentaria, mediante ecografía Doppler fetal, en pacientes embarazadas de término con oligohidroamnios aislado (OHA) y comparar los resultados en embarazadas con líquido amniótico normal. Método: Estudio transversal de 19 pacientes con embarazo de término y OHA sin patología asociada. Se compara la evaluación del Doppler con un grupo control de embarazadas con líquido amniótico normal. Como objetivo principal se mide el índice de pulsatilidad (IP)...

2010-01-01

256

Analysis of Radar Doppler Signature from Human Data  

Directory of Open Access Journals (Sweden)

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.

M. ANDRI?

2014-04-01

257

[Quantification by transthoracic Doppler of tricuspid valve insufficiencies].  

Science.gov (United States)

Various methods are available today for the quantification of regurgitation by transthoracic Doppler. The present review deals with their respective usefulness in tricuspid insufficiency (TI). Despite their contribution in the domain of mitral and aortic insufficiency, precise quantification methods remain of very limited value regarding the tricuspid orifice, and this because of practical difficulties of application. Evaluations of the severity of TI is based, essentially, on a semiquantitative approach. Cartography of the regurgitation stream, by colour Doppler, is the chief method, despite its limitations which are clearly emphasised by the effects of the contrast test. The discovery, by pulsed Doppler, of laminar systolic flow is a sign of capital importance. It is indicative of massive TI and of particular anatomical and hemodynamic conditions, but it is uncommon. Systolic reversal of flow in the inferior vena cava is a good sign of severity but lacks specificity. In contrast, measurement of maximum velocities of TI, while essential for the evaluation of pulmonary pressures, is of no value in terms of the quantification of regurgitation. Transthoracic Doppler data must be taken together with those of transthoracic echocardiography, the esophageal approach offering nothing special, being essentially useful in lesion evaluation. The quantification of TI, by transthoracic Doppler, has derived only very little benefit from the current orientation of Doppler methods. PMID:1416770

Hadjian, O; Bertrand, B; Defaye, P; Vanzetto, G; Contard, M; Denis, B

1992-05-01

258

Low-Frequency Gravitational Wave Searches Using Spacecraft Doppler Tracking  

Directory of Open Access Journals (Sweden)

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.

Armstrong J. W.

2006-01-01

259

VW Hyi: optical spectroscopy and Doppler tomography  

CERN Document Server

We present high quality optical spectroscopy of the SU UMa-subtype dwarf nova, VW Hyi taken while the system was in quiescence. An S-wave is executed by the emission cores of the Hydrogen Balmer lines and by the emission lines of He I, Ca II, Fe II and He II. Using Doppler tomography we show it originates in the accretion stream-disc impact region. The He II emission is strongly phase-dependent, suggesting it originates exclusively within a hot cavity at the initial impact. We map the ionization structure of the stream-disc interaction region. One possible interpretation of this is that the Balmer hotspot lies downstream of the He II hotspot in the outer accretion disc, with the He I and Ca II hotspots at intermediate locations between the two. This suggests that Balmer emission is suppressed until material has cooled somewhat downstream of the impact site and is able to recombine. We favour a phase offset of 0.15+/-0.04 between the photometric ephemeris and inferior conjunction of the mass donor. The white d...

Smith, A J; Hynes, R I; Smith, Amanda J.; Haswell, Carole A.; Hynes, Robert I.

2006-01-01

260

Color Doppler imaging of cervicocephalic fibromuscular dysplasia  

Directory of Open Access Journals (Sweden)

Full Text Available 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 the distal extracranial part of internal carotid artery (ICA or vertebral artery (VA, and 3. (optional: Direct and/or indirect criteria of stenosis. Results CDI detected FMD in 39 vessels (37 ICA and 2 VA segments of 21 patients. 16 patients had bilateral manifestation on ICA, one of those also on VA, bilaterally. CDI disclosed 4 symptomatic high-grade ICA stenoses, 3 of them underwent endovascular treatment. 5 patients with moderate symptomatic ICA stenoses got medical treatment. In 6 patients FMD was the most likely cause of headache and in one patient FMD was diagnosed as a cause of vertigo. Conclusions CDI may be used for detection of cervicocephalic FMD. Due to the unfavourable localisation of FMD for CDI, the sensitivity of CDI is lower in comparison to angiography. However, high-grade FMD stenoses that require invasive treatment can be recognized on the basis of indirect hemodynamic criteria.

Grzyska Ulrich

2004-07-01

 
 
 
 
261

Doppler interferometry study of unstable detonations  

Science.gov (United States)

Near-limit detonations are highly unstable and characterized by very large longitudinal velocity fluctuations that can range from 0.4 to 1.8 times the normal Chapman-Jouguet value. The period of the fluctuations also varies over a wide range from a few to a hundred tube diameters. In an attempt to establish a criterion for detonation limits, the velocity fluctuations of near-limit detonations are studied. A novel microwave Doppler technique based on a single coaxial mode has been developed for this purpose to give an unambiguous quasi-continuous velocity measurement of the detonation wave over the entire length of its travel. The near-limit unstable behavior in the detonable stoichiometric mixtures of hydrocarbons (C2H2, C2H4, C2H6, C3H8) with O2, air or N2O, tested in this work, have been characterized by four distinct modes of unstable behavior. This classification allows a qualitative description of the wide range of velocity fluctuations occurring near the detonation limit, including galloping waves.

Lee, J. J.; Dupré, G.; Knystautas, R.; Lee, J. H.

1995-10-01

262

Muscle activity characterization by laser Doppler Myography  

Science.gov (United States)

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.

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

2013-09-01

263

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

1993-01-01

264

Measuring velocities by laser Doppler interferometry  

International Nuclear Information System (INIS)

The advanced development of two optical velocimeters, the VISAR (velocity interferometer system for any reflector) and the Fabry--Perot systems, that greatly increase the sensitivity and resolution of measurements of shock and particle velocities is described. Both operate by measuring the Doppler shift in the frequency of light reflected from the moving body. In either case the system output produces velocity information directly, and this information can then be integrated to determine the position at any time. The VISAR output is recorded on fast oscilloscopes that can be set to observe different portions of the velocity history. The Fabry--Perot system has less flexibility, sensitivity, and time resolution than the VISAR, but its output is recorded directly on photographic film and is much simpler to analyze. Both systems are compatible with most of our other diagnostics and measure velocities to about 1% accuracy with time resolutions of a few nanoseconds. They can record velocity features over distances as small as 2.5 ?m even though the interferometers may be located over 30 m from the test object

1979-03-01

265

Optimizing Doppler Surveys for Planet Yield  

CERN Multimedia

One of the most promising methods of discovering nearby, low-mass planets in the habitable zones of stars is the precision radial velocity technique. However, there are many challenges that must be overcome to efficiently detect low-amplitude Doppler signals. This is both due to the required instrumental sensitivity and the limited amount of observing time. In this paper, we examine statistical and instrumental effects on precision radial velocity detection of extrasolar planets, an approach by which we maximize the planet yield in a fixed amount of observing time available on a given telescope. From this perspective, we show that G and K dwarfs observed at 400-600 nm are the best targets for surveys complete down to a given planet mass and out to a specified orbital period. Overall we find that M dwarfs observed at 700-800 nm are the best targets for habitable-zone planets, particularly when including the effects of systematic noise floors. Also, we give quantitative specifications of the instrumental stabil...

Bottom, Michael; Johnson, John Asher; Blake, Cullen H

2013-01-01

266

High-momentum analysis in Doppler spectroscopy  

International Nuclear Information System (INIS)

Unique information about the chemical vicinity of positron annihilation sites is provided by the contribution of high electron momenta to the Doppler spectrum, since this momentum range is characteristic for the annihilation with core electrons and hence element specific. However, the corresponding energy region in the spectrum is overlaid by a huge background caused by the annihilation radiation itself and the Compton spectrum of other gamma lines having an energy above 511 keV. Usually these backgrounds are reduced by measuring both annihilation quanta in coincidence. By mathematically analyzing the background contributions, we open another possibility to obtain the high-momentum region employing one single germanium detector. A necessary precondition is employing either background-free positron beams or a low-background positron source, e.g. 68Ge, instead of the widely used positron emitter 22Na. The 68Ge-source emits positrons with an endpoint energy of about 1.9 MeV, where as the contribution of gamma quanta having higher energies than the annihilation radiation at 511 keV is negligible low. When analyzing spectra from metals and semiconductors according to the described background subtraction, the same information contained in the momentum range up to 35 x 10-3m0c or beyond can be extracted, as if the spectra were measured employing a coincidence setup with two Ge-detectors

2008-10-31

267

High-momentum analysis in Doppler spectroscopy  

Energy Technology Data Exchange (ETDEWEB)

Unique information about the chemical vicinity of positron annihilation sites is provided by the contribution of high electron momenta to the Doppler spectrum, since this momentum range is characteristic for the annihilation with core electrons and hence element specific. However, the corresponding energy region in the spectrum is overlaid by a huge background caused by the annihilation radiation itself and the Compton spectrum of other gamma lines having an energy above 511 keV. Usually these backgrounds are reduced by measuring both annihilation quanta in coincidence. By mathematically analyzing the background contributions, we open another possibility to obtain the high-momentum region employing one single germanium detector. A necessary precondition is employing either background-free positron beams or a low-background positron source, e.g. {sup 68}Ge, instead of the widely used positron emitter {sup 22}Na. The {sup 68}Ge-source emits positrons with an endpoint energy of about 1.9 MeV, where as the contribution of gamma quanta having higher energies than the annihilation radiation at 511 keV is negligible low. When analyzing spectra from metals and semiconductors according to the described background subtraction, the same information contained in the momentum range up to 35 x 10{sup -3}m{sub 0}c or beyond can be extracted, as if the spectra were measured employing a coincidence setup with two Ge-detectors.

Haaks, Matz [Helmholtz Institut fuer Strahlen- und Kernphysik, Nussallee 14-16, 53155 Bonn (Germany)], E-mail: haaks@iskp.uni-bonn.de; Staab, Torsten E.M. [Helmholtz Institut fuer Strahlen- und Kernphysik, Nussallee 14-16, 53155 Bonn (Germany)

2008-10-31

268

Single mode, extreme precision Doppler spectrographs  

CERN Multimedia

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...

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

2012-01-01

269

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

Energy Technology Data Exchange (ETDEWEB)

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

Goncalves, Alessandro da Cruz

2010-07-01

270

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)

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.

Kennelly, M M

2012-04-01

271

ADEPT - Abnormal Doppler Enteral Prescription Trial  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Background Pregnancies complicated by abnormal umbilical artery Doppler blood flow patterns often result in the baby being born both preterm and growth-restricted. These babies are at high risk of milk intolerance and necrotising enterocolitis, as well as post-natal growth failure, and there is no clinical consensus about how best to feed them. Policies of both early milk feeding and late milk feeding are widely used. This randomised controlled trial aims to determine whether a policy of early initiation of milk feeds is beneficial compared with late initiation. Optimising neonatal feeding for this group of babies may have long-term health implications and if either of these policies is shown to be beneficial it can be immediately adopted into clinical practice. Methods and Design Babies with gestational age below 35 weeks, and with birth weight below 10th centile for gestational age, will be randomly allocated to an "early" or "late" enteral feeding regimen, commencing milk feeds on day 2 and day 6 after birth, respectively. Feeds will be gradually increased over 9-13 days (depending on gestational age using a schedule derived from those used in hospitals in the Eastern and South Western Regions of England, based on surveys of feeding practice. Primary outcome measures are time to establish full enteral feeding and necrotising enterocolitis; secondary outcomes include sepsis and growth. The target sample size is 400 babies. This sample size is large enough to detect a clinically meaningful difference of 3 days in time to establish full enteral feeds between the two feeding policies, with 90% power and a 5% 2-sided significance level. Initial recruitment period was 24 months, subsequently extended to 38 months. Discussion There is limited evidence from randomised controlled trials on which to base decisions regarding feeding policy in high risk preterm infants. This multicentre trial will help to guide clinical practice and may also provide pointers for future research. Trial registration Current Controlled Trials ISRCTN: 87351483

McCormick Kenny

2009-10-01

272

Hands-Free Transcranial Color Doppler Probe  

Science.gov (United States)

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.

Chin, Robert; Madala, Srihdar; Sattler, Graham

2012-01-01

273

Single Mode, Extreme Precision Doppler Spectrographs  

Science.gov (United States)

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.

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

2014-04-01

274

DOPPLER SIGNATURES OF THE ATMOSPHERIC CIRCULATION ON HOT JUPITERS  

International Nuclear Information System (INIS)

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 ?2 km s–1 blueshift inferred on HD 209458b may require drag time constants as short as 104-106 s, possibly the result of Lorentz-force braking on this planet's hot dayside.

2013-01-01

275

Tissue Doppler echocardiography – A case of right tool, wrong use  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Background The developments in echocardiography or ultrasound cardiography (UCG have improved our clinical capabilities. However, advanced hardware and software capabilities have resulted in UCG facilities of dubious clinical benefits. Is tissue Doppler echocardiography (TDE is one such example? Presentation of the hypothesis TDE has been touted as advancement in the field of echocardiography. The striking play of colors, impressive waveforms and the seemingly accurate velocity values could be deceptive. TDE is a clear case of inappropriate use of technology. Testing the hypothesis To understand this, a comparison between flow Doppler and tissue Doppler is made. To make clinically meaningful velocity measurements with Doppler, we need prior knowledge of the line of motion. This is possible in blood flow but impossible in the complex myocardial motion. The qualitative comparison makes it evident that Doppler is best suited for flow studies. Implications of the hypothesis As of now TDE is going backwards using an indirect method when direct methods are better. The work on TDE at present is only debatable 'research and publication' material and do not translate into tangible clinical benefits. There are several advances like curved M-mode, strain rate imaging and tissue tracking in TDE. However these have been disappointing. This is due to the basic flaw in the application of the principles of Doppler. Doppler is best suited for flow studies and applying it to tissue motion is illogical. All data obtained by TDE is scientifically incorrect. This makes all the published papers on the subject flawed. Making diagnostic decisions based on this faulty application of technology would be unacceptable to the scientific cardiologist.

Thomas George

2004-08-01

276

Doppler broadening induced spectral shift effects on reactor safety  

International Nuclear Information System (INIS)

It is commonly accepted that the resonance reaction rate of any material increases when the temperature is raised. However, in a nuclear reactor the increase in resonance reaction rates with temperature at relatively high energy shifts the neutron spectrum in such a way that a net decrease in the neutron flux results at lower energies. This finding suggested that the spectral shift could significantly affect the Doppler reactivity change, warranting further investigations. The objective was to study the physical characteristics of this new phenomenon and its effects on reactor safety. The desirability of studying this effect was strengthened by the presence of discrepancies between the calculated and measured integral experiments. An exact Doppler broadening kernel, based on the Maxwellian distribution of nuclear velocities, and an accurate integral transport method NDCRAB, capable of including resonance overlap of all materials present in the reactor cell, were used in this study. The ZPR-6 Assembly 7 benchmark, a typical LMFBR reactor, was used to quantify the Doppler reactivity change for an increase in fuel temperature and to analyze the natural UO3 sample Doppler worth in this assembly. The quantification of the various components of the Doppler reactivity change shows that the fissile material, 239Pu, has a large negative Doppler effect and contributes a large fraction to the total negative effect. The calculated Doppler effect of the natural UO3 sample in this assembly was in good agreement with the measured value. The calculated and measured values for an increase in sample temperature from 293-0K to 11000K wre -0.887 Ih/kgU and -0.868 Ih/kgU

1980-01-01

277

Using fraction images derived from modis data for coffee crop mapping / Utilização de imagens-fração derivadas do sensor modis para o mapeamento de lavouras de café  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese A produção de café esteve intimamente ligada ao desenvolvimento econômico do Brasil e ainda hoje o café é um importante produto da agricultura nacional. O Estado de Minas Gerais responde atualmente por 52% de toda a área de café do Brasil. Dados de sensoriamento remoto podem fornecer informações par [...] a o monitoramento e o mapeamento de café de maneira mais rápida e menos onerosa do que os métodos convencionais. Nesse contexto, o objetivo deste trabalho foi avaliar a eficácia do mapeamento de áreas de café do município de Monte Santo de Minas-MG, a partir de imagens-fração derivadas do sensor MODIS, nas estações de estiagem e de chuva. Através do Modelo Linear de Mistura Espectral, foram derivadas imagens-fração de solo, café e água/sombra. Estas imagens-fração serviram como dados de entrada para a classificação automática supervisionada com o método SVM - Support Vector Machine. Os melhores resultados de Exatidão Global e Índice Kappa foram obtidos na classificação do período seco, sendo 67% e 0,41, respectivamente. Abstract in english Coffee production was closely linked to the economic development of Brazil and, even today, coffee is an important product of the national agriculture. The State of Minas Gerais currently accounts for 52% of the whole coffee area in Brazil. Remote sensing data can provide information for monitoring [...] and mapping of coffee crops, faster and cheaper than conventional methods. In this context, the objective of this study was to assess the effectiveness of coffee crop mapping in Monte Santo de Minas municipality, Minas Gerais State, Brazil, from fraction images derived from MODIS data, in both dry and rainy seasons. The Spectral Linear Mixing Model was used to derive fraction images of soil, coffee, and water/shade. These fraction images served as input data for the supervised automatic classification using the SVM - Support Vector Machine approach. The best results concerning Overall Accuracy and Kappa Index were obtained in the classification of the dry season, with 67% and 0.41, respectively.

Bispo, Rafael C.; Lamparelli, Rubens A. C.; Rocha, Jansle V..

278

Cerebral blood flow with [15O]water PET studies using an image-derived input function and MR-defined carotid centerlines  

International Nuclear Information System (INIS)

Full quantitative analysis of brain PET data requires knowledge of the arterial input function into the brain. Such data are normally acquired by arterial sampling with corrections for delay and dispersion to account for the distant sampling site. Several attempts have been made to extract an image-derived input function (IDIF) directly from the internal carotid arteries that supply the brain and are often visible in brain PET images. We have devised a method of delineating the internal carotids in co-registered magnetic resonance (MR) images using the level-set method and applying the segmentations to PET images using a novel centerline approach. Centerlines of the segmented carotids were modeled as cubic splines and re-registered in PET images summed over the early portion of the scan. Using information from the anatomical center of the vessel should minimize partial volume and spillover effects. Centerline time-activity curves were taken as the mean of the values for points along the centerline interpolated from neighboring voxels. A scale factor correction was derived from calculation of cerebral blood flow (CBF) using gold standard arterial blood measurements. We have applied the method to human subject data from multiple injections of [15O]water on the HRRT. The method was assessed by calculating the area under the curve (AUC) of the IDIF and the CBF, and comparing these to values computed using the gold standard arterial input curve. The average ratio of IDIF to arterial AUC (apparent recovery coefficient: aRC) across 9 subjects with multiple (n = 69) injections was 0.49 ± 0.09 at 0–30 s post tracer arrival, 0.45 ± 0.09 at 30–60 s, and 0.46 ± 0.09 at 60–90 s. Gray and white matter CBF values were 61.4 ± 11.0 and 15.6 ± 3.0 mL/min/100 g tissue using sampled blood data. Using IDIF centerlines scaled by the average aRC over each subjects’ injections, gray and white matter CBF values were 61.3 ± 13.5 and 15.5 ± 3.4 mL/min/100 g tissue. Using global average aRC values, the means were unchanged, and intersubject variability was noticeably reduced. This MR-based centerline method with local re-registration to [15O]water PET yields a consistent IDIF over multiple injections in the same subject, thus permitting the absolute quantification of CBF without arterial input function measurements. (paper)

2013-03-21

279

Image-derived input function derived from a supervised clustering algorithm: methodology and validation in a clinical protocol using [11C](R)-rolipram.  

Science.gov (United States)

Image-derived input function (IDIF) obtained by manually drawing carotid arteries (manual-IDIF) can be reliably used in [(11)C](R)-rolipram positron emission tomography (PET) scans. However, manual-IDIF is time consuming and subject to inter- and intra-operator variability. To overcome this limitation, we developed a fully automated technique for deriving IDIF with a supervised clustering algorithm (SVCA). To validate this technique, 25 healthy controls and 26 patients with moderate to severe major depressive disorder (MDD) underwent T1-weighted brain magnetic resonance imaging (MRI) and a 90-minute [(11)C](R)-rolipram PET scan. For each subject, metabolite-corrected input function was measured from the radial artery. SVCA templates were obtained from 10 additional healthy subjects who underwent the same MRI and PET procedures. Cluster-IDIF was obtained as follows: 1) template mask images were created for carotid and surrounding tissue; 2) parametric image of weights for blood were created using SVCA; 3) mask images to the individual PET image were inversely normalized; 4) carotid and surrounding tissue time activity curves (TACs) were obtained from weighted and unweighted averages of each voxel activity in each mask, respectively; 5) partial volume effects and radiometabolites were corrected using individual arterial data at four points. Logan-distribution volume (V T/f P) values obtained by cluster-IDIF were similar to reference results obtained using arterial data, as well as those obtained using manual-IDIF; 39 of 51 subjects had a V T/f P error of 10%. With automatic voxel selection, cluster-IDIF curves were less noisy than manual-IDIF and free of operator-related variability. Cluster-IDIF showed widespread decrease of about 20% [(11)C](R)-rolipram binding in the MDD group. Taken together, the results suggest that cluster-IDIF is a good alternative to full arterial input function for estimating Logan-V T/f P in [(11)C](R)-rolipram PET clinical scans. This technique enables fully automated extraction of IDIF and can be applied to other radiotracers with similar kinetics. PMID:24586526

Lyoo, Chul Hyoung; Zanotti-Fregonara, Paolo; Zoghbi, Sami S; Liow, Jeih-San; Xu, Rong; Pike, Victor W; Zarate, Carlos A; Fujita, Masahiro; Innis, Robert B

2014-01-01

280

New clutter-rejection algorithm for Doppler ultrasound  

Science.gov (United States)

Several strategies, known as clutter or wall Doppler filtering, were proposed to remove the strong echoes produced by stationary or slow moving tissue structures from the Doppler blood flow signal. In this study, the matching pursuit (MP) method is proposed to remove clutter components. The MP method decomposes the Doppler signal into wavelet atoms that are selected in a decreasing energy order. Thus, the high-energy clutter components are extracted first. In the present study, the pulsatile Doppler signal s(n) was simulated by a sum of random-phase sinusoids. Two types of high-amplitude clutter signals were then superimposed on s(n): a time-varying low frequency component (type 1), covering systole and early diastole, and short transient clutter signals (type 2), distributed within the whole cardiac cycle. The Doppler signals were modeled with the MP method and the most dominant atoms were subtracted until the signal-to-clutter (S/C) ratio reached a maximum. For the type 1 clutter signal, the improvement in the S/C ratio was 19.0 +/- 0.6 dB, and 72.0 +/- 4.5 atoms were required to reach this performance. For the transient type 2 clutter signal, exactly 10 atoms were required and the maximum improvement in S/C ratio was 5.5 +/- 0.5 dB. These results suggest the possibility of using this signal processing approach to implement clutter rejection filters on ultrasound commercial instruments.

Cloutier, Guy; Chen, Danmin; Durand, Louis-Gilles

2002-04-01

 
 
 
 
281

A study of doppler waveform using pulsatile flow model  

Energy Technology Data Exchange (ETDEWEB)

Through the construction of a pulsatile flow model using an artificial heart pump and stenosis to demonstrate triphasic Doppler waveform, which simulates in vivo conditions, and to evaluate the relationship between Doppler waveform and vascular compliance. The flow model was constructed using a flowmeter, rubber tube, glass tube with stenosis, and artificial heart pump. Doppler study was carried out at the prestenotic, poststenotic, and distal segments;compliance was changed by changing the length of the rubber tube. With increasing proximal compliance, Doppler waveforms show decreasing peak velocity of the first phase and slightly delayed acceleration time, but the waveform itself did not change significantly. Distal compliance influenced the second phase, and was important for the formation of pulsus tardus and parvus, which without poststenotic vascular compliance, did not develop. The peak velocity of the first phase was inversely proportional to proximal compliance, and those of the second and third phases were directly proportional to distal compliance. After constructing this pulsatile flow model, we were able to explain the relationship between vascular compliance and Doppler waveform, and also better understand the formation of pulsus tardus and parvus.

Chung, Hye Won [Seoul City Boramae Hospital, Seoul (Korea, Republic of); Chung, Myung Jin; Park, Jae Hyung; Chung, Jin Wook; Lee, Dong Hyuk; Min, Byoung Goo [Seoul National Univ. College of Medicine, Seoul (Korea, Republic of)

1997-08-01

282

Acute intrascrotal pathology in childhood: color Doppler study  

International Nuclear Information System (INIS)

To asses the utility of color Doppler ultrasound in the study of acute intrascrotal pathology in childhood. Seventy-five boys with evidence of an acute intrascrotal abnormality were studied by means of color Doppler ultrasound. A 7.5 MHz linear transducer was used. The most common findings was inflammatory disease (60%) which was indicated by the presence of hyperemia in color Doppler. Of the nine boys with testicular torsion (12%) two presented extravaginal torsion, with a complete absence of intratesticular vascularization. Intravaginal torsion was observed in seven patients, six of whom presented reduced vascularization in the abnormal testicle with respect to the healthy testicle. There was one false negative in which testicular vascularization was normal but 360 degree centigree torsion was found at surgery. In addition, there were seven cases of hydatid torsion (9.33%), four of idiopathic scrotal swelling (5.3%). two cases of intermittent torsion (2.6%) and one case of Shcolein-Henoch purpura (1.3%). The ultrasound findings were completely nornal in seven boys. Color Doppler is a rapid, noninvasive method for assessing testicular blood flow. The elevated sensitivity and specificity (85.7 and 100%, respectively, in our series) for testicular torsion make Doppler ultrasound a highly reliable method for the study of this disorder. (Author) 18 refs

1997-01-01

283

Acoustic Doppler measurements for prospecting of wind energy  

Energy Technology Data Exchange (ETDEWEB)

Results from Doppler SODAR (sound Detecting and Ranging) measurements of horizontal and vertical winds are discussed. The measurements were carried out during a wind prospecting project that aimed at finding the best location for a wind power station on Gotland, an island in the south-eastern part of Sweden. The Doppler system was rebuilt by two standard SODAR units, primarily designed for vertical monostatic soundings. The Doppler unit consisted essentially of a phase-locked-loop (PLL) circuit. The data were presented on analog 3-channel recorders. The wind velocities derived from the Doppler shift are compared with simultaneous wind measurements from double theodolite pilot balloon trackings. The test shows quite good agreement within the lowest 100 m of the atmosphere. Also a comparison is made between local variation of the boundary-layer dynamics in thermally stable stratification obtained on a SODAR record and simultaneous Doppler measurements of horizontal wind speed and direction at the 60 m level. The influence of the topography on the vertical wind component is demonstrated during some periods of strong horizontal winds. Local variations of vertical temperature structure obtained on SODAR records at two sites, separated about 40 km, in relation to profiles pilot balloon tracking data are discussed.

Salomonsson, S.; Holmgren, B.

1980-01-01

284

Response of a Doppler canceling system to plane gravitational waves  

International Nuclear Information System (INIS)

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

1982-07-15

285

Renal Power Doppler Ultrasonographic Evaluation of Children With Acute Pyelonephritis  

Directory of Open Access Journals (Sweden)

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.

Ali Pahlusi

2011-10-01

286

Blood flow measurement by laser Doppler method in orofacial region  

Directory of Open Access Journals (Sweden)

Full Text Available Laser Doppler is a noninvasive, objective, reproducible and painless method for measuring blood flow in tissue microcirculation. This method is based on the Doppler effect, the change in frequency of light reflecting from blood cells in motion. Light from helium-neon laser through optical fibers and probes is directed to the surface of the tissue in which the flow is measured. Light portion is reflected from the cells in motion and changes the frequency while another portion is reflected from the static tissue maintaining the same frequency as the initial light. The total reflected light, with changed and original frequency, reaches photo detector in the same probe where the emitter is and it is transformed into electrical impulse. In the orofacial region the laser Doppler method is used to examine blood flow in the mandible, teeth pulp and masticator muscles. A significant drawback of the laser Doppler method is its sensitivity to the ambient conditions during measuring and the fact that blood flow is measured in all blood vessels of examined microregion. Therefore, the circulation of isolated individual blood vessels can not be monitored. Laser Doppler method can give reliable indicators of blood flow in mouth tissue and method is acceptable for the patients.

Grga ?urica

2010-01-01

287

Evaluation of Solid Breast Lesions with Color Doppler Sonography and Power Doppler Imaging  

Directory of Open Access Journals (Sweden)

Full Text Available Background: The purpose of our study was to assess the potential of color Doppler (CD and Power Doppler Imaging (PDI to differentiate benign from malignant solid breast masses. Materials and Methods: Seventy-one biopsy proven solid breast masses were evaluated with CD and PDI using 7.5 MHZ Transducer. Vascularity, Resistive Index (RI and patterns of vascular distribution of masses were assigned before biopsy. Results: There were 22 cancers and 49 benign lesions. All malignant masses had vascularity in some degrees, except 3 cancers which were less than 10 mm in diameter. Most of cancers were hypervascular (15 cancers and had penetrating or diffuse vessels (14 cancers. Most of benign lesions and fibro adenomas were avascular (35 masses. 12 cancers, 2 fibro adenomas and all vascular benign lesions had RI>0.6. 7 cancers and 6 fibro adenomas had RI<0.6. By using hypervascularity to indicate malignancy sensitivity for CD and PDI was 68 percent and specificity was 90 percent and by using penetrating and diffuse vessels sensitivity was 64 percent and specificity was 82 percent. By using RI<0.6 sensitivity was 32 percent and specificity was 88 percent and by using these three criteria together sensitivity was 73 percent and specificity was 82 percent (P<0.00001. Conclusion: The vascularity and pattern of distribution and morphology of blood vessels in solid breast masses seen at PDI and CD is a potentially important feature to predict the likelihood of malignancy. But RI appears to be of limited value.

S Shahriaran

2002-09-01

288

14 CFR Appendix G to Part 121 - Doppler Radar and Inertial Navigation System (INS): Request for Evaluation; Equipment and...  

Science.gov (United States)

...Doppler Radar and Inertial Navigation System (INS): Request for Evaluation; Equipment...Doppler Radar and Inertial Navigation System (INS): Request for Evaluation; Equipment...installationâInertial Navigation Systems (INS ) or Doppler Radar System. (a)...

2009-01-01

289

Multiline Doppler Imaging of MR Ser in High State  

Science.gov (United States)

Doppler images in Balmer, He I, He II and C II lines, and simultaneous I-band photometry of the polar MR Ser are presented and analyzed. The Balmer and Helium Doppler tomograms, of this bright polar at high mass transfer state show the emission from the accretion flow and the heated surface of the companion star. As a result of a comparison between the Doppler tomograms, the ionization structure of the flow could be constrained. The highest ionization region was found in the vicinity of the magnetospheric radius. Photoionization modeling of the accretion column indicates that the Balmer and Helium emission line production in this system can be explained only by the central soft X-ray illumination. The orbital ephemeris of MR Ser has been revised.

Diaz, M. P.; Cieslinski, D.

2009-01-01

290

The Doppler paradigm and the APEX-EPOS-ORANGE quandary  

CERN Multimedia

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

Griffin, J J

1996-01-01

291

Modeling and processing of laser Doppler reactive hyperaemia signal  

Science.gov (United States)

Laser Doppler flowmetry is a non-invasive method used in the medical domain to monitor the microvascular blood cell perfusion through tissue. Most commercial laser Doppler flowmeters use an algorithm calculating the first moment of the power spectral density to give the perfusion value. Many clinical applications measure the perfusion after a vascular provocation such as a vascular occlusion. The response obtained is then called reactive hyperaemia. Target pathologies include diabetes, hypertension and peripheral arterial occlusive diseases. In order to have a deeper knowledge on reactive hyperaemia acquired by the laser Doppler technique, the present work first proposes two models (one analytical and one numerical) of the observed phenomenon. Then, a study on the multiple scattering between photons and red blood cells occurring during reactive hyperaemia is carried out. Finally, a signal processing that improves the diagnosis of peripheral arterial occlusive diseases is presented.

Humeau, Anne; Saumet, Jean-Louis; L'Huiller, Jean-Pierre

2003-07-01

292

The Doppler paradigm and the APEX-EPOS-ORANGE quandary  

International Nuclear Information System (INIS)

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

1995-09-02

293

Vein Thrombosis Associated with Umbilical Vascular Catheters with Color Doppler  

Directory of Open Access Journals (Sweden)

Full Text Available The aim of this study was to evaluate the incidence and risk factors of umbilical catheter associated thrombosis in newborn infants using color Doppler. In this analytic-descriptive study, 256 newborn infants with umbilical catheters were evaluated during a 15 month. Color Doppler ultrasonography was employed for detection of vascular thrombosis associated with the umbilical catheter placement in the first 24-48 h after admission, weekly until discharge and 72 h after discharge. Among 256 newborns, 12 cases (4.7% had vascular thrombosis. The rate of thrombosis was 6.9 and 5.7% in the umbilical artery and vein catheters, respectively. Umbilical catheters is accompanied with the risk of thrombosis. Color Doppler ultrasonography is a good way for diagnosis of this thrombosis.

Masoud Nemati

2013-01-01

294

Cardiovascular changes during SCUBA diving: an underwater Doppler echocardiographic study.  

Science.gov (United States)

AIM: Body immersion induces blood redistribution (from peripheral to intrathoracic vessels) and is a powerful autonomic stimulus (activating both parasympathetic and sympathetic systems). For these reasons, concerns have been raised about the safety of diving for subjects with previous heart disease. The aim of this study was to evaluate cardiovascular changes occurring during recreational SCUBA diving, as assessed by underwater Doppler echocardiography. METHODS: Eighteen healthy experienced divers underwent a 2D Doppler echocardiography basally, during two 15' steps of still SCUBA diving at different depths (10 m followed by 5 m) and shortly after the end of immersion. RESULTS: During dive, left ventricular (LV) diastolic volume and early left ventricular filling significantly increased (5 m vs. basal: P SCUBA diving induces LV enlargement and diastolic dysfunction. Direct underwater evaluation by Doppler echocardiography could be an appropriate tool for unmasking subjects at risk for underwater-related accidents. PMID:23638629

Marabotti, C; Scalzini, A; Menicucci, D; Passera, M; Bedini, R; L'abbate, A

2013-05-01

295

Classification of transcranial Doppler signals using artificial neural network.  

Science.gov (United States)

Transcranial Doppler signals, recorded from the temporal region of brain on 110 patients were transferred to a personal computer by using a 16-bit sound card. The fast Fourier transform (FFT) method was applied to the recorded signal from each patient. Since FFT method inherently can not offer a good spectral resolution at jet blood flows, it sometimes causes wrong interpretation of transcranial Doppler signals. To do a correct and rapid diagnosis, transcranial Doppler blood flow signals were statistically arranged so that they were classified in artificial neural network. Back propagation neural network and self-organization map algorithms of artificial neural network were used for training, whereas momentum and delta-bar-delta algorithms were used for learning. The results of these algorithms were compared in the case of classification and learning. PMID:12617361

Serhatlio?lu, Selami; Hardalaç, Firat; Güler, Inan

2003-04-01

296

Spacecraft-Doppler gravity-wave detection. I. Theory  

International Nuclear Information System (INIS)

It is the purpose of this paper to produce a self-contained summary of the methods which may be used to analyze data in the newly developing field of spacecraft-Doppler gravity-wave detection. Three algorithms are developed. The first is a near-optimal matched filter which produces a ?2 improvement in signal-to-noise ratio for purposes of detecting short bursts of gravitational radiation. The second two methods are to be used in the search for the cosmic background, the one concentrating on the spectrum of the Doppler data and the other concentrating on the autocorrelation function. It is shown that these two methods are theoretically equivalent, although the autocorrelation method may be somewhat easier to use. The gain of these algorithms is shown to be proportional?n-bar where n is the number of data points in the Doppler record

1981-02-15

297

Non-intrusive Shock Measurements Using Laser Doppler Vibrometers  

Science.gov (United States)

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.

Statham, Shannon M.; Kolaini, Ali R.

2012-01-01

298

The implications of precise timekeeping of doppler gravitational wave observations  

International Nuclear Information System (INIS)

Gravitational radiation from galactic and extragalactic astrophysical sources will induce spatial strains in the solar system, strains which can be measured directly by the Doppler radio link to distant spacecraft. Current noise sources in Pioneer and Voyager Doppler data are delineated and a comparison is made with expected signal levels from gravitational wave sources. The main conclusion is that it is possible to detect gravitational radiation with current DSN hydrogen maser systems stable in fractional frequency + or - 2 x 10 to the minus 14th power over 1000 sec. In the future, however, a serious Doppler observational program in gravitational wave astronomy will require frequency systems stable to at least 10 to the minus 16th power, but at the same time the current single frequency S-band uplink transmission will have to be replaced by a dual frequency capability

1982-01-01

299

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)

1984-01-01

300

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)

1984-01-01

 
 
 
 
301

Doppler spectroscopy, a powerful tool for studying molecular collision dynamics  

International Nuclear Information System (INIS)

The present review describes the application of Doppler spectroscopy to studies in collision dynamics. The method was originally introduced by Kinsey (J. Chem. Phys. 66, 2560 (1976)). The authors used it to obtain angular and velocity distributions of Ba(6s6p1P1) atoms scattered in the 6s6p3P2 level by collisions with argon and simple molecules. After a short review of their recent work, the authors outline those areas where Doppler spectroscopy is a valuable tool (sometimes the only tool) for exploring gas phase collision dynamics. In particular they make clear that Doppler spectroscopy should not be considered as alternative but rather as complementary to the standard way of measuring differential cross sections where a rotating mass spectrometer rather than laser induced fluorescence is used to detect the scattered particles

1994-01-22

302

Effective particle size range in laser-Doppler anemometry  

International Nuclear Information System (INIS)

The present paper points out that all existing laser-Doppler anemometer systems do not only operate within a finite range of Doppler frequencies but also work within a relatively narrow range of signal amplitudes. It is shown that this corresponds to a finite, and usually to an extremely small, range of particle diameters which contributes to the final LDA measurements. The investigation results in conclusions regarding optimum particle size distributions for laser-Doppler anemometry. If fluid velocity measurements are attempted rather than particle velocity measurements, the particles still have to satisfy well known size requirements that are flow, fluid and particle density dependent. The experimental study employs a combined optical system for simultaneous measurements of particle velocity, particle size and particle concentration. The system is used to measure those particles of a spectrum of oil droplets that contribute to the validated signal output of counter and transient recorder based LDA-electronic signal processing systems. (orig./HP)

1987-01-01

303

A new clutter rejection algorithm for Doppler ultrasound.  

Science.gov (United States)

Several strategies, known as clutter or wall Doppler filtering, were proposed to remove the strong echoes produced by stationary or slow moving tissue structures from the Doppler blood flow signal. In this study, the matching pursuit (MP) method is proposed to remove clutter components. The MP method decomposes the Doppler signal into wavelet atoms that are selected in a decreasing energy order. Thus, the high-energy clutter components are extracted first. In the present study, the pulsatile Doppler signal s(n) was simulated by a sum of random-phase sinusoids. Two types of high-amplitude clutter signals were then superimposed on s(n): time-varying low-frequency components, covering systole and early diastole, and short transient clutter signals, distributed within the whole cardiac cycle. The Doppler signals were modeled with the MP method and the most dominant atoms were subtracted from the time-domain signal s(n) until the signal-to-clutter (S/C) ratio reached a maximum. For the low-frequency clutter signal, the improvement in S/C ratio was 19.0 +/- 0.6 dB, and 72.0 +/- 4.5 atoms were required to reach this performance. For the transient clutter signal, ten atoms were required and the maximum improvement in S/C ratio was 5.5 +/- 0.5 dB. The performance of the MP method was also tested on real data recorded over the common carotid artery of a normal subject. Removing 15 atoms significantly improved the appearance of the Doppler sonogram contaminated with low-frequency clutter. Many more atoms (over 200) were required to remove transient clutter components. These results suggest the possibility of using this signal processing approach to implement clutter rejection filters on ultrasound commercial instruments. PMID:12774899

Cloutier, Guy; Chen, Danmin; Durand, Louis-Gilles

2003-04-01

304

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)

2009-12-01

305

Combining direct and coherent detection for Doppler wind lidar  

Science.gov (United States)

Using a combination of two modest sized coherent and direct detection Doppler lidars may offer significant advantages over the single detection method approaches. All space-based Doppler wind lidar proposed missions to date have been based upon a single detection scheme, either coherent (WINDSAT, LAWS, SPARCLE, JEM/CDL) or direct (Zephyr, ALADIN, ADM) detection. A hybrid detection wind lidar has been proposed and is undergoing a feasibility study. The hybrid wind lidar is currently being baselined for an airborne test bed and is funded for a weather forecasting impact evaluations at NOAA and NASA.

Emmitt, George D.

2004-11-01

306

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)

1978-10-19

307

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

1960-01-01

308

Observational limitations of the Doppler theory of quasars  

International Nuclear Information System (INIS)

This paper is mainly concerned with the hypothesis that the redshift of a quasar is entirely due to the Doppler effect arising from its high speed of ejection in a relatively nearby center of explosion. We examine the viability of this hypothesis in the light of the available data on the aligned triplets of quasars discovered by Arp and Hazard and by Saslaw. Before applying the Doppler hypothesis we consider in some detail, using computer simulations, whether such well aligned triplet configurations could have arisen by chance projection effects under the cosmological hypothesis. Even allowing for various uncertainties and selection effects, we find such a development rather unlikely

1982-09-15

309

Investigation of ionospheric effects of solar flares by Doppler method  

International Nuclear Information System (INIS)

Ionospheric effects during solar flares, recorded by the Doppler method on the Fort Collins (USA) - Havana (Cuba) route are considered. According to the data of sudden frequency deviations (SFD) approximated profiles of electron concentration in the F1 region are calculated. For the flare on the 15th February,1978 estimation of the integral flux of solar irradiation in the range of wave lengths from 100 to 1030 A equals to 0.39 erg/cm2xs. It is pointed out that Doppler measurements for flares of different types are very important for creation of reliable models of ionosphere disturbance

1980-01-01

310

Estimating SAR Doppler Shifts From Quasi-Homogeneous Targets  

Science.gov (United States)

Linear-estimator subalgorithm optimized for local terrain. Algorithm processes some of information in synthetic-aperture-radar echoes from quasi-homogeneous targets, yielding optimal estimates of Doppler frequency shifts. Differs from one described in article, "Estimating SAR Doppler Shifts From Homogeneous Targets", NPO-17869, though offers similar advantages for measurements of wind shears and speeds of ocean currents. Derivation of algorithm involves some of same terminology and simplifying assumptions, however, target area considered quasi-homogeneous in sense it consists of patchwork of subareas, each of which is homogeneous target differing from its neighbors. This assumption more realistic than assumption of homogeneity.

Jin, Michael Y.

1991-01-01

311

C IV Doppler shifts observed in active region filaments  

Science.gov (United States)

The Doppler shift properties of 21 active region filaments were studied using C IV Dopplergram data. Most are associated with corridors of weak magnetic field that separate opposite polarity strong fields seen in photospheric magnetograms. A majority of the filaments are relatively blue shifted, although several lie very close to the dividing lines between blue and red shift. Only one filament in the samples is clearly red shifted. A new calibration procedure for Dopplergrams indicates that sizable zero point offsets are often required. The center-to-limb behavior of the resulting absolute Doppler shifts suggests that filament flows are usually quite small. It is possible that they vanish.

Klimchuk, J. A.

1986-01-01

312

ULTRASONOGRAFÍA DOPPLER EN EMBARAZOS DE TÉRMINO CON OLIGOHIDROAMNIOS AISLADO  

Directory of Open Access Journals (Sweden)

Full Text Available Objetivos: Evaluar la unidad feto placentaria, mediante ecografía Doppler fetal, en pacientes embarazadas de término con oligohidroamnios aislado (OHA y comparar los resultados en embarazadas con líquido amniótico normal. Método: Estudio transversal de 19 pacientes con embarazo de término y OHA sin patología asociada. Se compara la evaluación del Doppler con un grupo control de embarazadas con líquido amniótico normal. Como objetivo principal se mide el índice de pulsatilidad (IP de las arterias renal, cerebral media y umbilical fetal, y como secundarios se evalúan los resultados neonatales. Resultados: Los resultados de la medición Doppler de IP en pacientes con OHA v/s control fueron no significativos: 2,03 v/s 2,04 en arteria renal (p >0,05, 1,37 v/s 1,35 en arteria cerebral media (p >0,05, 0,79 v/s 0,82 en arteria umbilical (p >0,05. Los objetivos secundarios no mostraron diferencias estadísticamente significativas. Conclusión: El OHA aislado en pacientes con embarazo de término no se asocia con alteración del Doppler fetal, por lo que no se relaciona con deterioro de la función placentaria.Objectives: To evaluate the fetoplacentarian unit through the fetal Doppler flow in term pregnants with oligohidramnios and to compare the fetal outcomes with term pregnants with normal amniotic fuid. Methods: We designed a transversal correlational study of 19 term patients with oligohidramnios and no other pathology. We compare the fetal Doppler values with a control pregnant group with normal amniotic fluid. Our main outcomes were renal, middle cerebral and umbilical artery PI (pulsatility index and our secondary outcomes were the neonatal results. Results: Patients with oligohidramnios PI Doppler flow values v/s control group were non significant: renal artery 2.03 v/s 2.04 (p >0.05, middle cerebral artery 1.37 v/s 1.35 (p >0.05, umbilical artery 0.79 v/s 0.82 (p>0.05. The secondary outcomes neither were statistically different. Conclusion: There is no association between the isolated oligohidramnios in a term pregnancy and fetal Doppler disorder, for what is not associated with placental dysfunction.

Marcelo Rodríguez G

2010-01-01

313

ULTRASONOGRAFÍA DOPPLER EN EMBARAZOS DE TÉRMINO CON OLIGOHIDROAMNIOS AISLADO  

Scientific Electronic Library Online (English)

Full Text Available SciELO Chile | Language: Spanish Abstract in spanish Objetivos: Evaluar la unidad feto placentaria, mediante ecografía Doppler fetal, en pacientes embarazadas de término con oligohidroamnios aislado (OHA) y comparar los resultados en embarazadas con líquido amniótico normal. Método: Estudio transversal de 19 pacientes con embarazo de término y OHA sin [...] patología asociada. Se compara la evaluación del Doppler con un grupo control de embarazadas con líquido amniótico normal. Como objetivo principal se mide el índice de pulsatilidad (IP) de las arterias renal, cerebral media y umbilical fetal, y como secundarios se evalúan los resultados neonatales. Resultados: Los resultados de la medición Doppler de IP en pacientes con OHA v/s control fueron no significativos: 2,03 v/s 2,04 en arteria renal (p >0,05), 1,37 v/s 1,35 en arteria cerebral media (p >0,05), 0,79 v/s 0,82 en arteria umbilical (p >0,05). Los objetivos secundarios no mostraron diferencias estadísticamente significativas. Conclusión: El OHA aislado en pacientes con embarazo de término no se asocia con alteración del Doppler fetal, por lo que no se relaciona con deterioro de la función placentaria. Abstract in english Objectives: To evaluate the fetoplacentarian unit through the fetal Doppler flow in term pregnants with oligohidramnios and to compare the fetal outcomes with term pregnants with normal amniotic fuid. Methods: We designed a transversal correlational study of 19 term patients with oligohidramnios and [...] no other pathology. We compare the fetal Doppler values with a control pregnant group with normal amniotic fluid. Our main outcomes were renal, middle cerebral and umbilical artery PI (pulsatility index) and our secondary outcomes were the neonatal results. Results: Patients with oligohidramnios PI Doppler flow values v/s control group were non significant: renal artery 2.03 v/s 2.04 (p >0.05), middle cerebral artery 1.37 v/s 1.35 (p >0.05), umbilical artery 0.79 v/s 0.82 (p>0.05). The secondary outcomes neither were statistically different. Conclusion: There is no association between the isolated oligohidramnios in a term pregnancy and fetal Doppler disorder, for what is not associated with placental dysfunction.

Marcelo, Rodríguez G; Gabriela, Egaña U; Rolando, Márquez A.

314

Fano-Doppler laser cooling of hybrid nanostructures.  

Science.gov (United States)

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

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

2011-09-27

315

Terminal Doppler Weather Radar (TDWR) Moving Target Simulator (MTS) at Orlando, Florida.  

Science.gov (United States)

Monitoring the performance of Doppler weather radars presents special problems since target returns cannot be verified by reference to other systems (e,g ., as ASR-9 aircraft reports can be compared with beacon replies). The Terminal Doppler Weather Radar...

W. H. Drury J. M. Frankovich

1992-01-01

316

Rain Fallspeeds and Rates Derived from Airborne Nadir-Pointing Doppler Radar Measurements.  

Science.gov (United States)

The use of vertical-incidence Doppler velocity in addition to radar reflectivity may yield information on drop size distribution and therefore result in better rainrate estimates. Doppler velocity can provide useful information on the raindrop size distri...

G. M. Heymsfield L. Tian B. Geerts

1999-01-01

317

Automated Aortic Doppler Flow Tracing for Reproducible Research and Clinical Measurements  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In clinical practice, echocardiographers are often unkeen to make the significant time investment to make additional multiple measurements of Doppler velocity. Main hurdle to obtaining multiple measurements is the time required to manually trace a series of Doppler traces. To make it easier to analyze more beats, we present the description of an application system for automated aortic Doppler envelope quantification, compatible with a range of hardware platforms. It analyses long Doppler stri...

2014-01-01

318

Utilidad del doppler transcraneal en la hemorragia subaracnoidea: Revisión / Usefulness of transcranial doppler in subarachnoid hemorrhage: Review  

Scientific Electronic Library Online (English)

Full Text Available SciELO Chile | Language: Spanish Abstract in spanish Esta revisión resume la utilidad del Doppler transcraneal (DTC) para la evaluación de la hemorragia subaracnoidea en instalaciones de una unidad de tratamiento de accidente vascular. Se presentan los principios hemodinámicos básicos. Se discute la eficiencia, las ventajas y las limitaciones del DTC [...] y los métodos de interpretación. Abstract in english This review summarizes the usefulness of transcranial Doppler (TCD) for the assessment of subarachnoid hemorrhage in the setting of a stroke unit. The basic hemodynamic principles are presented. We discuss the accuracy, the advantages and limitations of the TCD and the interpretation methods. [...

Claudio E, Scherle-Matamoros; Jesús, Pérez-Nellar.

319

Utilidad del doppler transcraneal en la hemorragia subaracnoidea: Revisión Usefulness of transcranial doppler in subarachnoid hemorrhage: Review  

Directory of Open Access Journals (Sweden)

Full Text Available Esta revisión resume la utilidad del Doppler transcraneal (DTC para la evaluación de la hemorragia subaracnoidea en instalaciones de una unidad de tratamiento de accidente vascular. Se presentan los principios hemodinámicos básicos. Se discute la eficiencia, las ventajas y las limitaciones del DTC y los métodos de interpretación.This review summarizes the usefulness of transcranial Doppler (TCD for the assessment of subarachnoid hemorrhage in the setting of a stroke unit. The basic hemodynamic principles are presented. We discuss the accuracy, the advantages and limitations of the TCD and the interpretation methods.

Claudio E Scherle-Matamoros

2011-03-01

320

Micro-Doppler Frequency Estimation Based on Radon-Wigner Transform  

Directory of Open Access Journals (Sweden)

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.

Sun Huixia

2014-01-01

 
 
 
 
321

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

LENUS (Irish Health Repository)

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.

Unterscheider, Julia

2013-12-01

322

Doppler-Sonographische Untersuchungen zur ovariellen Durchblutungsrate bei Stuten in Abhängigkeit vom Zyklus.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Ziel dieser Studie war es, die intraovarielle Durchblutung unter physiologischen Verhältnissen bei normozyklischen Stuten zu untersuchen. Dies erfolgte unter Anwendung zweier Methoden, der Auswertung von Power-Doppler-Sonographie-Aufnahmen mit Hilfe computerassistierter Pixelanalyse und, erstmalig in diesen Untersuchungen, durch Bestimmung der Doppler-Indizes (Resistance Index, RI und Pulsatility Index, PI) mittels direkter Messungen der Frequenzdifferenz (Doppler Shift) in intraovariellen A...

2006-01-01

323

Field trial of a Doppler sonar system for fisheries applications  

Science.gov (United States)

Various deployments of commercial Doppler current profiling systems have demonstrated that these instruments can detect fish and measure their swimming speeds. However, research into the possible application of Doppler sonar to fisheries problems is limited and has not taken advantage of coherent signal processing schemes. A field trial was undertaken in August 2002 to explore the capabilities of a coherent Doppler sonar when applied to detecting discrete targets. The passage of migrating salmon on the Fraser River in British Columbia provided an ideal test opportunity with fish of well-defined swimming behavior and allowed for comparisons with conventional fisheries acoustics techniques. The instrument tested was a 250-kHz sonar which provided for phase coding of transmit pulses and coherent sampling of successive acoustic returns. The field trial resulted in 11 consecutive days of Doppler sonar data acquired during the peak of the sockeye salmon (Oncorhynchus nerka) migration. A total of 7425 individual fish were identified and their swimming speed was measured with an accuracy of between 10 cms-1 and 20 cms-1, which depended on pulse length, pulse spacing, and target range. By comparison, water velocity measurements made with the same instrument can only achieve a theoretical accuracy of 60 cms-1.

Tollefsen, Cristina D. S.; Zedel, Len

2003-10-01

324

Doppler sonography in diagnosis of the acute scrotum  

Directory of Open Access Journals (Sweden)

Full Text Available Doppler sonography has been reported to be a reliable technique for diagnosing acute scrotum significantly decreasing the number of unnecessary surgeries. The aim of this paper was to demonstrate the superiority and validity of Doppler sonography over conventional sonography for differential diagnosis of the acute scrotum. In the period from 2002-2004, 300 patients underwent ultrasound examination of the testicles at the Institute of Radiology in Novi Sad. This prospective randomized study included 100 patients, whereas the target group consisted of 50 patients with the diagnosis of the acute scrotum. The control group consisted of 50 patients with the diagnosis of varicocele. The examinations were done using Siemens Versa Pro equipment and 7,5 MHz probes. On the basis of ultrasound examination, the target group was divided into three groups: 1. Inflammation, 2. Torsion, 3. Miscellaneous. Depending on the disease, the accuracy of diagnosis was confirmed by surgery, clinical findings and control sonographic examination. A functional correlation exists between Doppler diagnosis and final diagnosis in the inflammation and torsion. Resistive indexes (RI were lower in inflammation, because of hyperemia. In cases with intratesticular hyperemia, the average RI was 0,454 and in those with supratesticular hyperemia 0,575. In cases with torsion, only one patient with appendiceal torsion had normal intratesticular blood flow. In diagnostics of the acute scrotum, Doppler sonography is superior over conventional sonography and more precise in differential diagnostics. RI are good quantitative parameters of hyperemia. .

Nikoli? Olivera

2006-01-01

325

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.

2012-08-01

326

Prediction of cerebrovascular reserve by the MRI and doppler ultrasonography  

International Nuclear Information System (INIS)

We investigated acute stroke patterns on diffusion weighted images and with doppler ultrasonography studies of ICA and MCA steno-occlusive diseases in order to predict the cerbrovascular reserve (CVR), as was measured by acetazolamide (ACZ)-challenged Tc-99m ECD brain perfusion SPECT. A retrospective analysis was performed of 76 patients who underwent MRI/MRA, ACZ-challenged Tc-99m ECD brain perfusion SPECT, and carotid and vertebral artery Doppler sonography. After dividing these patients into four groups-MCA and ICA ateno-occlusions, we analyzed the relationship between the CVR and topologic MR patterns and the flow volume, as was measured by Doppler sonography. The CVRs were preserved in 26 of 76 patients. The CVRs were impaired in those cases of occlusion that were detected on MRA and also by the pattern of the territorial involvement on the diffusion weighted image (? 2 test). Yet in cases of preserved CVRs, the flow volume of the contralateral ICA, the anterior circulation, and the total cerebral flow volume were increased, as was checked by Doppler sonography (? < 0.05, t-test). As calculated by logistic regression analysis, the accuracy for predicting the preserved CVR by using the statistically significant variables was 78%. We believe that the MRI-SPECT correlation study was helpful for understanding the hemodynamics and topographic patterns of ischemia in patients with ICA and MCA steno-occlusive disease, and that the flow volume measurement, which was done by using duplex US, was useful for predicting the CVR

2005-07-01

327

Three-dimensional color Doppler imaging of the carotid artery  

Science.gov (United States)

Stroke is the third leading cause of death in the United States. It is caused by ischemic injury to the brain, usually resulting from emboli from atherosclerotic plaques. The carotid bifurcation in humans is prone to atherosclerotic disease and is a site where emboli may originate. Currently, carotid stenoses are evaluated by non-invasive duplex Doppler ultrasound, with preoperative verification by intra-arterial angiography. We have developed a system that uses a color Doppler ultrasound imaging system to acquire in-vivo 3-D color Doppler images of the human carotid artery, with the aim of increasing the diagnostic accuracy of ultrasound and decreasing the use of angiography for verification. A clinical TL Ultramark 9 color Doppler ultrasound system was modified by mounting the hand-held ultrasound scan head on a motor-driven translation stage. The stage allows planar ultrasound images to be acquired over 45 mm along the neck between the clavicle and the mandible. A 3- D image is acquired by digitizing, in synchrony with the cardiac cycle, successive color ultrasound video images as the scan head is stepped along the neck. A complete volume set of 64 frames, comprising some 15 megabytes of data, requires approximately 2 minutes to acquire. The volume image is reformatted and displayed on a Sun 4/360 workstation equipped with a TAAC-1 graphics accelerator. The 3-D image may be manipulated in real time to yield the best view of blood flow in the bifurcation.

Picot, Paul A.; Rickey, Daniel W.; Mitchell, Ross; Rankin, Richard N.; Fenster, Aaron

1991-05-01

328

Research on Fast-Doppler-Broadening of neutron cross sections  

Energy Technology Data Exchange (ETDEWEB)

A Fast-Doppler-Broadening method is developed in this work to broaden Continuous Energy neutron cross-sections for Monte Carlo calculations. Gauss integration algorithm and parallel computing are implemented in this method, which is unprecedented in the history of cross section processing. Compared to the traditional code (NJOY, SIGMA1, etc.), the new Fast-Doppler-Broadening method shows a remarkable speedup with keeping accuracy. The purpose of using Gauss integration is to avoid complex derivation of traditional broadening formula and heavy load of computing complementary error function that slows down the Doppler broadening process. The OpenMP environment is utilized in parallel computing which can take full advantage of modern multi-processor computers. Combination of the two can reduce processing time of main actinides (such as {sup 238}U, {sup 235}U) to an order of magnitude of 1{approx}2 seconds. This new method is fast enough to be applied to Online Doppler broadening. It can be combined or coupled with Monte Carlo transport code to solve temperature dependent problems and neutronics-thermal hydraulics coupled scheme which is a big challenge for the conventional NJOY-MCNP system. Examples are shown to determine the efficiency and relative errors compared with the NJOY results. A Godiva Benchmark is also used in order to test the ACE libraries produced by the new method. (authors)

Li, S.; Wang, K.; Yu, G. [Dept. of Engineering Physics, Tsinghua Univ., Beijing, 100084 (China)

2012-07-01

329

Pediatric imaging/doppler ultrasound of the chest: Extracardiac diagnosis  

International Nuclear Information System (INIS)

In this book the author spells out new diagnostic applications in pediatrics for high resolution cross-sectional ultrasonography, and demonstrates the ways in which Doppler techniques complement the cross-sectional method. This reference presents practical, step-by-step methods for non-invasive ultrasound examination of extra-cardiac anatomy and assessment of vascular blood flow

1986-01-01

330

Hypercholesterolemia and Myocardial function evaluated via Tissue Doppler Imaging  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Abstract Objective To establish a link between hypercholesterolemia and myocardial dysfunction. Background Heart failure is a complex disease involving changes in systolic and diastolic function. Newer echocardiographic imaging modalities may be able to detect discreet changes in myocardial function associated with hypercholesterolemia. Therefore we sought to establish a link between hypercholesterolemia and myocardial dysfunction with tissue Doppler imaging (TD...

2009-01-01

331

Doppler quantitative measures by region to discriminate prostate cancer.  

Science.gov (United States)

This study was conducted to assess if sonographic discrimination between healthy and cancerous prostate tissue might be improved using regional analysis of ultrasound (US) Doppler measures. A total of 39 subjects underwent 3-D Doppler sonography before radical prostatectomy. Cancer locations were identified from hematoxylin and eosin (H&E)-stained slides. Three prostate data volumes consisting of a frequency shift and power-mode Doppler US and whole mount histology images were spatially registered for each prostate, then divided into entirely 1 mL-sized regions of cancerous or noncancerous tissue. Each prostate was visually divided into a peripheral and a periurethral region within which US Doppler measures were calculated. Receiver operating characteristic (ROC) and simulated biopsy analyses within each prostate were performed. Mean speed in colored pixels (V), and speed-weighted pixel density (SWD) are good discriminators for prostate cancer in the periurethral and the peripheral regions, respectively. Using SWD in a simulated biopsy yields increased cancer detection in the peripheral region. PMID:11731043

Potdevin, T C; Moskalik, A P; Fowlkes, J B; Bude, R O; Carson, P L

2001-10-01

332

Doppler radar velocity measurements for wound ballistics experiments.  

Science.gov (United States)

Bullet velocity is a basic parameter in wound ballistics studies. It is usually measured electronically by means of a variety of solid or photoelectric barriers connected to equipment measuring the time elapsing between impulses, enabling the velocity to be calculated. With the advent of Doppler radar velocity measurement of large calibre artillery shells, the use of this equipment for wound ballistics experiments was investigated. Anaesthetized pigs were shot at a range of 9-10 metres and the velocities measured by Doppler radar and photocells were compared. A very good correspondence between the measured entry and exit velocities in low and medium velocity bullets was found, i.e. an average deviation of less than 1% (range 0-2%) between the two types of equipment. In high velocity bullets measurement of entry velocities was just as good, but in both methods measurement of the exit velocity was complicated by the cluttering of signals by fragments of tissue released from the exit wound and the deflection of the bullet, Doppler radar offers important benefits - simple set up, minimal risk of damage of equipment by stray bullets and very good accuracy - and may replace photocells and similar equipment in studies involving low and medium velocity bullets. Measurement of the exit velocity of high velocity bullets is unsatisfactory in both methods, and it is necessary to improve the Doppler radar method in order to measure that as well. PMID:7999640

Knudsen, P J; Svender, J

1994-01-01

333

Diode-pumped alexandrite laser for DIAL and Doppler lidar  

Science.gov (United States)

The problem of laser selection for spaceflight DIAL or Doppler lidar is considered. Spaceflight lidar requires tens of watts of laser output, and the low efficiency of lasers imposes costly burdens on the spacecraft platform. DIAL requires a tunable laser, and Doppler an ultraviolet laser, so the high efficiency of the Nd:YAG laser is compromised. The alexandrite laser can in principle provide higher systems efficiency for DIAL or Doppler than the Nd:YAG, being intrinsically tunable, and capable of reaching the ultraviolet with frequency doubling. High power 680 nm laser diodes are now available with sufficient power to pump alexandrite to the necessary power levels. A Q-switched laser configuration is modeled to obtain a projection laser efficiency of 13 percent. A more conservative estimate is 3.5 percent, well below the 9 percent achieved with Nd:YAG. Considering the energy savings through intrinsic tunability, frequency doubling to the ultraviolet, and extremely narrow spectral linewidth, a Doppler wind lidar system based on the alexandrite laser would have four to nine times the efficiency of the Nd:YAG alternative.

McKay, Jack A.; Wilkerson, Thomas D.

1997-10-01

334

Doppler Spectra of Bistatic Reverberation from the Sea Surface.  

Science.gov (United States)

The Doppler spectra of sea surface reverberation were investigated in a shallow water environment. A parametric array projected a narrow beam of acoustic energy at the surface and insonified on the surface a well-defined scattering area of limited extent....

W. I. Roderick

1979-01-01

335

Low Cost Coherent Doppler Lidar Data Acquisition and Processing  

Science.gov (United States)

The work described in this paper details the development of a low-cost, short-development time data acquisition and processing system for a coherent Doppler lidar. This was done using common laboratory equipment and a small software investment. This system provides near real-time wind profile measurements. Coding flexibility created a very useful test bed for new techniques.

Barnes, Bruce W.; Koch, Grady J.

2003-01-01

336

Predictive analog to digital conversion of Doppler ultrasound signals.  

Science.gov (United States)

Analog to digital conversion in multigate Doppler ultrasound systems for blood velocity measurements is a technological challenge. The echoes must be digitized at a rate determined by the system bandwidth (typically 2 MHz), and the dynamic range is large (16 bits or more) due to the presence of strong, low-frequency Doppler clutter echoes originating from slowly moving tissue. Off-the-shelf A/D converters do not meet these requirements with the transducer configuration employed by contemporary Doppler systems. Analysis reveals a 5-b reduction in required wordlength for an A/D converter in a predictive feedback loop when the maximum clutter frequency is about 1.5% of the pulse repetition frequency. The prediction error filter is recursive. Alternatively, first- and second-order DPCM (Differential Pulse Code Modulation) yield 4 and 6 b, respectively. With short input segments (from a high-resolution Color Flow Mapper), the results are, in the above order, 4, 4, and 5 b. The results are verified by processing an experimental Doppler signal. PMID:7698781

Bøe, S; Kristoffersen, K

1995-03-01

337

Pulsed laser-Doppler flowmetry for monitoring deep perfusion  

Science.gov (United States)

Measurements have been carried out using a pulsed laser-Doppler setup. The main advantage of pulsing a laser-diode is that much higher peak powers can be used, allowing a larger source-detector separation, resulting in a larger penetration depth. The method enables e.g. monitoring of cerebral perfusion as well as monitoring perfusion through organs (e.g. kidney).

Kolkman, Roy G. M.; Hondebrink, Erwin; Bolt, Rene A.; Steenbergen, Wiendelt; de Mul, Frits F. M.

2001-10-01

338

Dual beam translator for use in Laser Doppler anemometry  

Energy Technology Data Exchange (ETDEWEB)

A method and apparatus for selectively translating the path of at least one pair of light beams in a Laser Doppler anemometry device whereby the light paths are translated in a direction parallel to the original beam paths so as to enable attainment of spacial coincidence of the two intersection volumes and permit accurate measurements of Reynolds shear stress.

Brudnoy, David M. (Albany, NY)

1987-01-01

339

Doppler effect measurements on solid and liquid Sn  

International Nuclear Information System (INIS)

Neutrons at 24 keV were used to measure the integrated neutron transmission of relatively thick tin samples as a function of thickness and temperature. The effective total cross sections are plotted and discussed as a function of the Doppler effect, temperature resonance self-shielding, and thickness. 6 references

1979-06-08

340

Unidirectional Rotation of Molecules Measured by the Rotational Doppler Effect  

Directory of Open Access Journals (Sweden)

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.

Prior Yehiam

2013-03-01

 
 
 
 
341

A new technique for Doppler frequency analysis of radar signals  

Science.gov (United States)

A longstanding performance goal for Army ground surveillance radars is the automatic classification of moving ground targets on the battlefield. Limited classification has been achieved by splitting the radar Doppler spectrum into lower and higher frequency bands, thus distinguishing between targets having different radial velocities. While this is an important feature, since only certain targets (vehicles) are capable of obtaining high radial speeds, it does not provide a distinction between a moving man and vehicles having low radial speed components. That there are distinct differences in the Doppler signatures between man and vehicle is easily established by listening to typical Doppler return signals. One can clearly distinguish the step modulation of a walking man from the relatively constant or slowly changing tone of a vehicle. As to be expected, a spectrogram of a walking man shows this repetitive behavior. Most obvious is a sinewave like frequency modulation at the step frequency of the main body return power appearing as a black band near 100 Hertz. This oscillatory temporal characteristic in the Doppler shifted frequency is practically never seen in vehicular return and is the discriminant chosen for automatic classification.

Rittenbach, O. E.

1980-06-01

342

The Dark Side of the Universe: Doppler Shift  

Science.gov (United States)

This activity illustrates the Doppler effect in cosmology by use of rubber bands. Students will learn how light waves emitted from stars are red shifted if the stars are moving away from Earth (light waves are stretched, producing longer wavelengths), and blue shifted if the stars are moving towards Earth (light waves are squeezed in front of the star, producing shorter wavelengths).

343

Doppler-shifted acoustic cyclotron resonance in tungsten and molybdenum  

International Nuclear Information System (INIS)

Magnetoacoustic phenomena caused by doppler-shifted acoustic cyclotron resonance (DSACR) in tungsten and molybdenum at ultrasound propagation along crystallographical and axes are investigated. It is revealed experimentally that rate dispersion for circularly polarized waves with left and right rotation direction is equal by value and opposite by sign

1982-10-01

344

Relativistic Effect on the Classical Doppler Shift: An Annotated Bibliography.  

Science.gov (United States)

The classical problem of the Doppler shift of radiation transmitted between two bodies moving relative to each other took on a new aspect with the advent of the Space Age in 1957. When measurements are made between the earth and an artificial satellite, t...

E. J. Blau

1964-01-01

345

Analysis of multiple scattering effects in optical Doppler tomography  

DEFF Research Database (Denmark)

Optical Doppler tomography (ODT) combines Doppler velocimetry and optical coherence tomography (OCT) to obtain high-resolution cross-sectional imaging of particle flow velocity in scattering media such as the human retina and skin. Here, we present the results of a theoretical analysis of ODT where multiple scattering effects are included. The purpose of this analysis is to determine how multiple scattering affects the estimation of the depth-resolved localized flow velocity. Depth-resolved velocity estimates are obtained directly from the corresponding mean or standard deviation of the observed Doppler frequency spectrum. Thus, in the present analysis, the dependence of the mean and standard deviation of the Doppler shift on the scattering properties of the flowing medium are obtained. Taking the multiple scattering effects into account, we are able to explain previous measurements of depth-resolved retinal flow profiles where the influence of multiple scattering was observed [Yazdanfar et al., Opt. Lett. 25, 1448 (2000)]. To the best of our knowledge, no analytical model exists that are able to explain these observations.

Thrane, L.; Andersen, Peter E.

2005-01-01

346

Estimating Doppler Shifts for Synthetic-Aperture Radar  

Science.gov (United States)

Quality of synthetic-aperture-radar (SAR) imagery enhanced by pair of signal-processing techniques that compensate for relative motion between target and vehicle. Combining vehicle trajectory data with radar-parameter and raw image data, techniques generate Doppler estimates for use in constructing fully processed images.

Curlander, J. C.

1985-01-01

347

Doppler velocimetry in pregnant patients with sickle cell anemia.  

Science.gov (United States)

Women with sickle cell anemia have an increased risk of bearing low-birth-weight (LBW) progeny. To establish prognostic indicators of neonatal outcome, 15 women with sickle cell anemia were followed through their pregnancies with the use of umbilical and uterine Doppler flow velocimetry. The systolic/diastolic ratios obtained were correlated with neonatal birth weight, gestational age, and birth weight percentile. Pregravid hemoglobin levels, reticulocyte counts, dense cell numbers, percentage hemoglobin F, and indirect bilirubin and lactate dehydrogenase levels were also determined, and statistical analysis was performed to assess whether any of these parameters would be useful in conjunction with velocimetry. We report here that, in sickle cell anemia, prenatal umbilical and uterine Doppler velocimetry ratios correlate inversely and significantly with neonatal birth weight (P < 0.005 and P < 0.002, respectively). In addition, prenatal maternal HbF levels also correlate significantly with Doppler velocimetry readings, an independent indicator of LBW progeny. Neither pregravid hemoglobin levels nor dense cell concentration correlates with Doppler umbilical and uterine flow velocimetry ratios determined during pregnancy. Pregravid high levels of HbF and velocimetry readings may serve to delineate a subset of sickle cell patients who may have different requirements for prenatal care. The possible mechanism for the detrimental effects of increased levels of fetal hemoglobin has not been clearly established, but it may involve increased propensity for vasoocclusion due to the unique rheology of the human placenta. PMID:7679883

Billett, H H; Langer, O; Regan, O T; Merkatz, I; Anyaegbunam, A

1993-03-01

348

High-Energy 2-Micrometers Doppler Lidar for Wind Measurements  

Science.gov (United States)

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

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

2006-01-01

349

Usefulness of Doppler Parameter in Patients with Renal Transplantation  

Energy Technology Data Exchange (ETDEWEB)

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.

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

350

Continuous haemodynamic monitoring in children: use of transoesophageal Doppler.  

Science.gov (United States)

A wide range of invasive and non-invasive techniques for monitoring the haemodynamic condition of critically ill patients is now available. A general reluctance on the part of paediatric intensive care specialists to use pulmonary artery thermodilution catheters and the need for constant realignment of hand-held Doppler probes has necessitated the search for a technique which is relatively non-invasive and provides continuous information on the haemodynamic condition of critically ill paediatric patients. We sought to establish if transoesophageal Doppler fulfilled these criteria. Eleven children who had recently undergone cardiac surgery were studied. Median age was 39 months and weight 14.9 kg. Five simultaneous pairs of measurements of cardiac index (CI: thermodilution) and minute distance (MD: transoesophageal Doppler) were made, as a baseline, when each child was haemodynamically stable. Following a fluid challenge, five repeat pairs of measurements were made. The mean percentage changes for CI and MD were 16.4% (range 5.3-44%) and 16.6% (3.4-47.7%), respectively. The average coefficients of variation for measurements of CI and MD were 3.5% and 2.9%, respectively. The mean difference in percentage change between CI and MD was -0.5% (95% confidence interval for the bias -4% to 3%; limits of agreement -10.7 to +9.7%). Our study indicates that transoesophageal Doppler is reproducible, easy to use and provides clinically acceptable information when following changes in CI in haemodynamically stable paediatric patients. PMID:7549293

Murdoch, I A; Marsh, M J; Tibby, S M; McLuckie, A

1995-07-01

351

Doppler velocimetry of the uterine arteries in nulliparous women.  

Science.gov (United States)

The aim of this study was to evaluate the role of uterine artery Doppler velocimetry performed at 20 and 24 weeks gestation in predicting gestational hypertension and small-for-gestational age babies in a population of nulliparous women. Four hundred and fifty-six patients without risk factors for pregnancy complications and with fetuses free from structural abnormalities at ultrasonographic examination at 20 weeks gestation were considered in the study. During the routine 20 weeks ultrasound a continuous-wave Doppler examination of the uterine arteries was performed. The patients with abnormal uterine Resistance Index (RI) repeated the Doppler evaluation at 24 weeks by means of Colour Doppler equipment. Among the 419 women who completed the study an abnormal Doppler uterine arteries velocimetry was found in 8.6% of the patients. Pregnancy complications (gestational hypertension and/or small-for-gestational age babies) were observed in 56% of the patients presenting high uteroplacental RI versus 10% of those with normal uterine artery velocimetry (P = 0.0001). In the group of patients with an abnormal RI value, the presence of a diastolic notch in one or both of the uterine arteries identified a population of pregnant women at higher risk for pregnancy complications when compared with patients without notch (78% vs. 33%, P = 0.007). The knowledge of the uteroplacental resistance can help in identifying a subgroup of patients at higher risk of hypertensive disorders and small-for-gestational age babies that could benefit from prophylaxis with low dose aspirin. PMID:9131318

Frusca, T; Soregaroli, M; Valcamonico, A; Guandalini, F; Danti, L

1997-04-25

352

Non-Gaussianity and CMB aberration and Doppler  

Science.gov (United States)

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 ? 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.

Catena, Riccardo; Liguori, Michele; Notari, Alessio; Renzi, Alessandro

2013-09-01

353

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

2002-01-01

354

Ovarian and uterine periovulatory Doppler ultrasonography in bitches / Ultrassonografia Doppler ovariana e uterina em cadelas  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese Este trabalho teve como objetivo descrever as características ultrassonográficas uterinas e ovarianas, e dopplervelocimétricas das suas artérias nos dias periovulatórios em cadelas. Quinze ciclos estrais em 10 animais foram avaliados. As características ultrassonográficas, índices de resistência (IR [...] ) e índices de pulsatilidade (IP) do útero e dos ovários em cada animal foram registrados 5 dias antes e depois da ovulação (D0). Os dados foram analisados estatisticamente e os resultados foram expressos em média ± erro padrão da média (P Abstract in english This paper aims to describe the uterine and ovarian ultrasonographic characteristics and Doppler velocimetric features of their arteries in bitches during the periovulatory period. Fifteen estrous cycles in 10 animals were evaluated. The ultrasonographic characteristics, resistance indices (RI) and [...] pulsatility indices (PI) of the uterus and ovaries in each animal were recorded 5 days before and after ovulation (D0). The data were statistically analyzed, and the results were expressed as the mean ± standard error of mean (P

Barbosa, Claudia C.; Souza, Mírley B.; Scalercio, Sarah R.R.A.; Silva, Ticiana F.P.; Domingues, Sheyla F.S.; Silva, Lúcia D.M..

355

Influence of flame on phase Doppler anemometry; Iso Doppler keisoku ni okeru kaen no eikyo  

Energy Technology Data Exchange (ETDEWEB)

The objective of the present study is to clarify the influence of a flame on phase-Doppler-anemometry (PDA) and to discuss quantitatively the accuracy of droplet size and velocity measurement using a polystyrene particle with a known size and a Bunsen burner placed on the optical path of PDA to simulate the variation of the refractive index of a combusting field. It was found that the fluctuation of the flame significantly influences the measured values, especially those of size, and some scattering of data was observed, while the measured mean diameter obtained in these experiments had little difference depending on the existence of a flame in front of the PDA optics or not. Furthermore, we tried to elucidate the cause of errors by comparing the scatter of measured size with the displacement of incident laser beams. As a result, it was found that the displacement of the laser beams is related to errors caused by the interference of the flame on the optical path of PDA. 11 refs., 21 figs., 1 tab.

Tsushima, S.; Akamatsu, F.; Katsuki, M. [Osaka University, Osaka (Japan). Faculty of Engineering; Mizutani, Y. [Kinki University, Osaka (Japan). Faculty of Science and Engineering; Cho, Y.

1997-03-25

356

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

Energy Technology Data Exchange (ETDEWEB)

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.

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

1993-01-01

357

An ideal blood mimicking fluid for doppler ultrasound phantoms  

Directory of Open Access Journals (Sweden)

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

Samavat H

2006-01-01

358

Multipoint photonic doppler velocimetry using optical lens elements  

Energy Technology Data Exchange (ETDEWEB)

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.

Frogget, Brent Copely; Romero, Vincent Todd

2014-04-29

359

A positron annihilation doppler broadening study of niobium  

International Nuclear Information System (INIS)

Doppler broadening of the positron annihilation lineshape has been measured for 99.995 wt. % pure niobium in the temperature range 300-2581 K. It was found that the effect of the equilibrium vacancies upon the Doppler-broadened lineshape in pure niobium is much smaller than that normally found for other metals, in agreement with an earlier study. Furthermore, the addition of 100 at. ppm oxygen to the niobium produced no measureable effects on the lineshape, within the experimental uncertainties, either within or below the vacancy-sensitive temperature region. The results are discussed in relation to previous investigations of positron trapping at vacancies in niobium, as well as to studies of vacancy migration in metals

1985-01-01

360

Doppler reflectometry for the investigation of poloidally propagating density perturbations  

International Nuclear Information System (INIS)

A modification of microwave reflectometry is discussed where the direction of observation is tilted with respect to the normal onto the reflecting surface. The experiment is similar to scattering where a finite resolution in k-space exists but keeps the radial localization of reflectometry. The observed poloidal wavenumber is chosen by Bragg's condition via the tilt angle and the resolution in k-space is determined by the antenna pattern. From the Doppler shift of the reflected wave the poloidal propagation velocity of density perturbations is obtained. The diagnostic capabilities of Doppler reflectometry are investigated using full wave code calculations. The method offers the possibility to observe changes in the poloidal propagation velocity of density perturbations and their radial shear with a temporal resolution of about 10?s. (authors)

1999-09-01

 
 
 
 
361

Doppler broadening measurements in FRX-C/LSM  

International Nuclear Information System (INIS)

Measurements obtained in situ during field reversed configuration (FRC) formation show that the Doppler broadening ion temperature TCV is larger by a factor of two or more than the ion temperature Ti derived from pressure balance and Thomson scattering. After a time comparable to an ion-ion equilibration time, TCV and Ti come into agreement with each other. An exception to this picture occurs in the lowest fill pressure condition (2 mtorr), for which TCV > Ti is maintained throughout the FRC lifetime. Earlier Doppler broadening measurements in FRX-B and FRX-C also showed persistent, anomalously high TCV at low fill pressure. The initially high values of TCV are probably caused by convective motion generated by the radial implosion. The low fill pressure results suggest an enhanced ohmic power input to the carbon ions

1990-05-01

362

The structure of Doppler peaks induced by active perturbations  

CERN Document Server

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

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

1996-01-01

363

Doppler-broadening measurements of positronium thermalization in gases  

International Nuclear Information System (INIS)

The formation and subsequent thermalization of positronium (Ps) produced at a few eV in gases are investigated using time-resolved Doppler-broadening measurements of the annihilation photons. A static magnetic field quenches the Ps enabling Doppler energy measurements from 25 to 70 ns after the Ps is formed. Varying the gas density permits a significant range of the thermalization process to be observed. Seven different gases are studied, He, Ne, Ar, H2, N2, isobutane, and neopentane. A classical elastic scattering model fits all the gas data reasonably well. For each gas, an elastic scattering cross section and an average Ps formation energy are determined from the classical model fit. When comparisons can be made, these cross sections are often significantly smaller than most quantum-mechanical-theory predictions and most previous experimental results obtained using the angular correlation technique. Various systematic tests have been applied to the apparatus and the analysis, reinforcing the discrepancy with previous works

2003-02-01

364

Application of FFT analyzed cardiac Doppler signals to fuzzy algorithm.  

Science.gov (United States)

Doppler signals, recorded from the output of tricuspid, mitral, and aorta valves of 60 patients, were transferred to a personal computer via 16-bit sound card. The fast Fourier transform (FFT) method was applied to the recorded signal from each patient. Since FFT method inherently cannot offer a good spectral resolution at highly turbulent blood flows, it sometimes leads to wrong interpretation of cardiac Doppler signals. In order to avoid this problem, firstly six known diseased heart signals such as hypertension, mitral stenosis, mitral failure, tricuspid stenosis, aorta stenosis, aorta insufficiency were introduced to fuzzy algorithm. Then, the unknown heart diseases from 15 patients were applied to the same fuzzy algorithm in order to detect the kinds of diseases. It is observed that the fuzzy algorithm gives true results for detecting the kind of diseases. PMID:12356493

Güler, Inan; Hardalaç, Firat; Bari?çi, Necaattin

2002-11-01

365

Microwave Doppler reflectometer system in the Experimental Advanced Superconducting Tokamak.  

Science.gov (United States)

A Doppler reflectometer system has recently been installed in the Experimental Advanced Superconducting (EAST) Tokamak. It includes two separated systems, one for Q-band (33-50 GHz) and the other for V-band (50-75 GHz). The optical system consists of a flat mirror and a parabolic mirror which are optimized to improve the spectral resolution. A synthesizer is used as the source and a 20 MHz single band frequency modulator is used to get a differential frequency for heterodyne detection. Ray tracing simulations are used to calculate the scattering location and the perpendicular wave number. In EAST last experimental campaign, the Doppler shifted signals have been obtained and the radial profiles of the perpendicular propagation velocity during L-mode and H-mode are calculated. PMID:24182112

Zhou, C; Liu, A D; Zhang, X H; Hu, J Q; Wang, M Y; Li, H; Lan, T; Xie, J L; Sun, X; Ding, W X; Liu, W D; Yu, C X

2013-10-01

366

Doppler shift of laser light reflected from expanding plasmas  

International Nuclear Information System (INIS)

The Doppler shift of light reflected from a plane stratified expanding plasma is analyzed. Nonlinear effects are not considered and oblique incidence is restricted to the case of s polarization. The frequency shift is shown to consist of two components, one due to the motion of the reflecting surface, and another due to plasma flow through that surface. The shifts have a different dependence on the angle of incidence. Typically, the two contributions are comparable in laser fusion applications, being of order delta?/?approx.c/sub s//capprox.10"-"3, where c/sub s/ = (Z-italic T/sub e//M)/sup 1/2/ is the ion sound speed in the underdense plasma. In general, the Doppler shift has a time variation which induces a bandwidth in the reflected wave

1981-01-01

367

Turbulence Spectra from Doppler-shifted Spectral Lines  

CERN Document Server

Turbulence is a key element of the dynamics of astrophysical fluids, including those of interstellar medium, clusters of galaxies and circumstellar regions. Turbulent motions induce Doppler shifts of observable emission and absorption lines. In the review we discuss new techniques that relate the spectra of underlying velocity turbulence and spectra of Doppler-shifted lines. In particular, the Velocity-Channel Analysis (VCA) makes use of the channel maps, while the Velocity Coordinate Spectrum (VCS) utilizes the fluctuations measured along the velocity axis of the Position-Position Velocity (PPV) data cubes. Both techniques have solid foundations based on analytical calculations as well as on numerical testings. Among the two the VCS, which has been developed quite recently, has two advantages. First of all, it is applicable to turbulent volumes that are not spatially resolved. Second, it can be used with absorption lines that do not provide good spatial sampling of different lags over the image of turbulent ...

Lazarian, A

2006-01-01

368

Gravitational Doppler effect explored by means of a geostationary satellite  

International Nuclear Information System (INIS)

The question is discussed whether the description of the gravitational Doppler effect as a simple energy effect is consistent with its general-relativistic description as a metricntime effect. The difference between a local description and a global one is stressed. In the local description one is permitted to ignore metric effects. The global description yields a position-dependent rate of proper time in a gravitational field, and the energy, or the frequency, of a ''freely falling'' photon is described as a constant of motion. An experiment of nonlocal character measuring, simultaneously, the gravitational Doppler effect and the position-dependent rate of proper time may be performed by the use of a geostationary satellite. A simple general-relativistic of the satellite experiment is obtained by transforming the Schwarzschild metric to a rotating frame, and describing the motion of free particles nd the rates of standard clocks in the resulting metric

1980-01-01

369

Magnetic properties of C IV Doppler shift patterns. [in photosphere  

Science.gov (United States)

Coaligned pairs of C IV Dopplergrams and Fe I magnetograms are used to investigate the relationship between Doppler shift patterns observed in the transition region and magnetic field patterns observed in the photosphere. It is found that V(0) lines associated with neutral lines tend to have limbward blueshifts, and that V(0) lines associated with unipolar regions tend to have limbward redshifts. The results are consistent with the active region model of Klimchuk (1984) in which relative redshifts occur where strong vertical fields penetrate the surface, and relative blueshifts occur where these same fields have spread out to become horizontal. It is suggested that the relative blueshifts may correspond to absolute Doppler shifts of very small amplitide.

Klimchuk, James A.

1989-01-01

370

Doppler shift system. [system for measuring velocities of radiating particles  

Science.gov (United States)

A system is described for measuring velocities of radiating particles based on Doppler shift. Light from the particles is directed through a narrow band optical filter to a Fabry-Perot interferometer initially tuned to a selected center line corresponding to zero particle Doppler shift. The movable mirror of the interferometer is made to sweep about the center line by the output of a modulation oscillator. The fringe pattern output is imaged onto a pin hole through which light is directed to a photomultiplier. The output of the photomultiplier is supplied to a phase sensitive detector with the oscillator output as a reference signal and which operates in the quadrature mode. The detector's output is gain controlled and is combined with the oscillator's output to adjust the interferometer's movable mirror to acquire the line center.

Aisenberg, S. (inventor)

1974-01-01

371

Atomic Auger Doppler effects upon emission of fast photoelectrons.  

Science.gov (United States)

Studies of photoemission processes induced by hard X-rays including production of energetic electrons have become feasible due to recent substantial improvement of instrumentation. Novel dynamical phenomena have become possible to investigate in this new regime. Here we show a significant change in Auger emission following 1s photoionization of neon, which we attribute to the recoil of the Ne ion induced by the emission of a fast photoelectron. Because of the preferential motion of the ionized Ne atoms along two opposite directions, an Auger Doppler shift is revealed, which manifests itself as a gradual broadening and doubling of the Auger spectral features. This Auger Doppler effect should be a general phenomenon in high-energy photoemission of both isolated atoms and molecules, which will have to be taken into account in studies of other recoil effects such as vibrational or rotational recoil in molecules, and may also have consequences in measurements in solids. PMID:24906107

Simon, Marc; Püttner, Ralph; Marchenko, Tatiana; Guillemin, Renaud; Kushawaha, Rajesh K; Journel, Loïc; Goldsztejn, Gildas; Piancastelli, Maria Novella; Ablett, James M; Rueff, Jean-Pascal; Céolin, Denis

2014-01-01

372

Distribution of Doppler Redshifts of Associated Absorbers of SDSS Quasars  

Science.gov (United States)

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 z 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 z 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 z Dopp = - 0.0004, might arise from the random motion of absorbers with respect to quasars.

Pan, Cai-Juan; Chen, Zhi-Fu

2013-12-01

373

US-Doppler in the evaluation of hemodialysis arteriovenous fistulas  

International Nuclear Information System (INIS)

US-Doppler has recently gained attention as a noninvasive method for the functional evaluation of arteriovenous fistulas (FAV). Twenty patients with well-functioning FAV were studied, and the results compared with those from a control group of 10 healthy subjects. Time average velocity (TAV) was caculated as hemodialysis parameter, together with telesystolic (Vts) and telediastolic (Vtd) velocities, absolute (F) and normalized (FN) fluxes to the area unit (cm2 1) and resistence index (IR). All of them proved to be statistically significant indexes of FAV functionality. Doppler has thus proved to be a valuable means both to calculate FAV capacity in a patient and to establish FAV functionality. Four parameters are recommended: FN>2000 ml/min/cm2; IR50 cm/s; Vtd>35 cm/s

1989-01-01

374

Transcranial Doppler sonographic findings in middle cerebral artery disease.  

Science.gov (United States)

The transcranial Doppler sonographic findings of 61 patients with middle cerebral artery (MCA) disease were compared with those of 535 controls. According to computed tomographic, angiographic, and/or autopsy findings, the patients were classified as having MCA occlusive lesions in the central (sphenoidal) part or in peripheral branches or MCA stenosis. With MCA lesions, the MCA flow velocity (FV) was reduced. At the same time the anterior cerebral artery FV increased because of collateral flow over leptomeningeal anastomoses. Central MCA lesions showed less marked changes than did peripheral lesions. In MCA stenosis a steep rise of MCA FV appeared inside the stenotic segment. If there was a high-grade stenosis or occlusion of the internal carotid artery, a collateral circulation over the anterior part of the circle of Willis was seen in addition to the changes caused by the MCA disease. From these hemodynamic changes, transcranial Doppler sonographic diagnostic criteria for MCA occlusive and stenotic lesions were established. PMID:3277600

Mattle, H; Grolimund, P; Huber, P; Sturzenegger, M; Zurbrügg, H R

1988-03-01

375

Multipath induced errors in meteorological Doppler/interferometer location systems  

Science.gov (United States)

One application of an RF interferometer aboard a low-orbiting spacecraft to determine the location of ground-based transmitters is in tracking high-altitude balloons for meteorological studies. A source of error in this application is reflection of the signal from the sea surface. Through propagating and signal analysis, the magnitude of the reflection-induced error in both Doppler frequency measurements and interferometer phase measurements was estimated. The theory of diffuse scattering from random surfaces was applied to obtain the power spectral density of the reflected signal. The processing of the combined direct and reflected signals was then analyzed to find the statistics of the measurement error. It was found that the error varies greatly during the satellite overpass and attains its maximum value at closest approach. The maximum values of interferometer phase error and Doppler frequency error found for the system configuration considered were comparable to thermal noise-induced error.

Wallace, R. G.

1984-01-01

376

Novel data evaluation algorithm for Coincident Doppler Broadening Spectroscopy  

Science.gov (United States)

In Coincident Doppler Broadening Spectroscopy (CDBS) the sum energy of the annihilation photons is checked to be 1022 keV, to validate the measurement of an undisturbed two-gamma electron-positron decay event. The events are stored in a two-dimensional acquisition matrix. A new algorithm is presented, which optimizes the extraction of the one-dimensional CDBS spectrum from this matrix by enhanced background suppression by the use of variable size bins.

Pikart, Philip; Hugenschmidt, Christoph

2014-06-01

377

Pulsed Doppler duplex sonography and CT of portal vein thrombosis  

International Nuclear Information System (INIS)

Five patients with partial or complete portal vein thrombosis were examined by both computed tomography (CT) and pulsed Doppler duplex scanning. Duplex scanning correctly identified portal vein thrombosis in all five. Duplex sonography may be the preferred technique to detect and follow portal vein thrombosis because of lower cost, lack of need for intravenous contrast material, and easier availability for multiple follow-up examinations

1985-07-01

378

WAMDII: wide-angle Michelson Doppler imaging interferometer for Spacelab  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A wide-angle Michelson Doppler imaging interferometer (WAMDII) is described that is intended to measure upper atmospheric winds and temperatures from naturally occurring visible region emissions, using Spacelab as a platform. It is an achromatic field-widened instrument, with good thermal stability, that employs four quarterwave phase-stepped images to generate full images of velocity, temperature, and emission rate. For an apparent emission rate of 5 kR and binning into 85 X 105 pixels, the ...

Sheperd, G. G.; Gault, W. A.; Miller, D. W.; Pasturcyzk, Z.; Johnston, S. F.; Kosteniuk, P. R.; Haslett, J. W.; Kendall, D. J. W.; Wimperis, J. R.

1985-01-01

379

Transverse flow imaging based on photoacoustic Doppler bandwidth broadening  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We propose a new method to measure transverse flow velocity based on photoacoustic Doppler bandwidth broadening, which is determined by the geometry of the probe-beam and the velocity of the transverse flow. By exploiting pulsed laser excitation and raster motor scanning, three-dimensional structure and flow velocity can be imaged simultaneously. In addition, the flow direction can be determined with bidirectional scanning. In a flowing suspension of red-dyed microspheres (diameter: 6 ?m), t...

Yao, Junjie; Wang, Lihong V.

2010-01-01

380

Sonographic and colour doppler morphology in carcinoma gallbladder.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Conventional radiography has limitations in accurate diagnosis of gallbladder cancer (GBC). Ultrasonography (USG) allows correct diagnosis in 70-80% advanced and 23% early GBC. Present study was initiated to identify morphology and flow characteristics in GBC using conventional USG and Colour Doppler USG (CD-USG). In 100 patients, USG assessed morphology of mass lesion/wall thickening together with associated features. Of these, 60 cases were studied using CD-USG for intralesion...

2002-01-01

 
 
 
 
381

The Lorentz Transformation and the Transverse Doppler Effect  

Digital Repository Infrastructure Vision for European Research (DRIVER)

         According to the Lorentz transformation (LT) of the special theory of relativity (STR), the value of a wavelength or any other distance interval that is measured transverse to the velocity of a light source should be independent of the relative speed of the observer (dy=dy’). It is known from experiments with the transverse Doppler effect, however, that the wavelength of light emitted from a moving source increases uniformly in all directions

Buenker, Robert J.

2011-01-01

382

Prediction of cerebrovascular reserve by the MRI and doppler ultrasonography  

Energy Technology Data Exchange (ETDEWEB)

We investigated acute stroke patterns on diffusion weighted images and with doppler ultrasonography studies of ICA and MCA steno-occlusive diseases in order to predict the cerbrovascular reserve (CVR), as was measured by acetazolamide (ACZ)-challenged Tc-99m ECD brain perfusion SPECT. A retrospective analysis was performed of 76 patients who underwent MRI/MRA, ACZ-challenged Tc-99m ECD brain perfusion SPECT, and carotid and vertebral artery Doppler sonography. After dividing these patients into four groups-MCA and ICA ateno-occlusions, we analyzed the relationship between the CVR and topologic MR patterns and the flow volume, as was measured by Doppler sonography. The CVRs were preserved in 26 of 76 patients. The CVRs were impaired in those cases of occlusion that were detected on MRA and also by the pattern of the territorial involvement on the diffusion weighted image ({rho} < 0.05, x{sup 2} test). Yet in cases of preserved CVRs, the flow volume of the contralateral ICA, the anterior circulation, and the total cerebral flow volume were increased, as was checked by Doppler sonography ({rho} < 0.05, t-test). As calculated by logistic regression analysis, the accuracy for predicting the preserved CVR by using the statistically significant variables was 78%. We believe that the MRI-SPECT correlation study was helpful for understanding the hemodynamics and topographic patterns of ischemia in patients with ICA and MCA steno-occlusive disease, and that the flow volume measurement, which was done by using duplex US, was useful for predicting the CVR.

Lee, Hui Joong; Kim, Yong Sun [Kyungpook National University Hospital, Daegu (Korea, Republic of)

2005-07-15

383

Air tracer experiment around Mt. Tsukuba by two doppler radars  

Energy Technology Data Exchange (ETDEWEB)

A remote sensing technique of pollutant diffusion in the atmosphere was studies for a real time monitoring system in a wide area. The first experiment was carried out around Mt. Tsukuba on 25-26 October 1983, using a system of two Doppler radars and radar reflective materials (Chaff) for a trace of air pollutants. One of the two radars is the C-band (5.3 GHz) meteorological Doppler radar fixed at the Meteorological Research Institute (MRI). The other, an X-band (10 GHz) meteorological Doppler radar, was set near Noda city, about 30 km from MRI. Observation ranges of the radars were selected to be 64 km, and the obtained data were processed by computer and stored on magnetic tapes. During this project, five runs were carried out. In each run, 7-10 packs of chaff were scattered from an airplane on a line at about 1000m height with about 5 km spacing between them. Main results obtained by this experiment are as follows: (a) Radar echo of chaff could be tracked for about 1-2 h and 20-100 km; (b) Doppler velocity data were effective in avoiding interferences of ground clutter, despite the low elevation of the radar antenna so that the chaff was superimposed on the ground clutter; (c) effects of the mountain on wind field were found from horizontal distributions of echo, and the wind profile was visualized by vertical cross-section; and (d) this system has advantages, compared with conventional experiments, because 3-dimensional distributions of air pollutants, wind velocities and diffusivities over complex terrain are analyzed in detail.

Kurita, S.; Satomura, T.; Yoshikawa, T.

1986-01-01

384

Doppler Echocardiographic Assessment of Pregnant Women with Chronic Arterial Hypertension  

Digital Repository Infrastructure Vision for European Research (DRIVER)

OBJECTIVE: To assess structural and functional cardiac changes in asymptomatic pregnant women with chronic arterial hypertension (CAH). METHODS: One hundred pregnant women with CAH underwent conventional Doppler echocardiography. The Student t test was used to compare them with 29 normotensive pregnant women (NT) in their third gestational trimester. RESULTS: Systolic (SBP; mmHg) and diastolic (DBP; mmHg) blood pressure values were higher (p<0.001) in the CAH pregnant women (SBP: 139±1...

2002-01-01

385

Assessment of cardiac output by the Doppler ultrasound technique alone.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The normal range of aortic blood velocity was established in 140 healthy adults, using a non-invasive Doppler ultrasound technique. Integration of the area under the velocity-time curve for each heart beat gave stroke distance, which, when multiplied by heart rate, gave minute distance. Stroke distance and minute distance are an indication of stroke volume and cardiac output respectively and both show a progressive decline with age of about 1% per annum of adult life. Stroke distance gave the...

Haites, N. E.; Mclennan, F. M.; Mowat, D. H.; Rawles, J. M.

1985-01-01

386

Two new types of laser doppler flowmeters prototypes validation  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A fluxometria laser Doppler (LDF) é uma técnica para avaliação em tempo real do fluxo microcirculatório em tecidos biológicos. Esta técnica pode ser usada para monitorização não invasiva da microcirculação (por exemplo, avaliação da perfusão na pele), ou para monitorização da perfusão de forma invasiva (por exemplo, avaliação da perfusão no cérebro). Nesta tese, pretende-se acrescentar ao estado da arte da LDF, quando aplicada à monitorização não invasiva da perfu...

Campos, Rita Helena Pinto Oliveira

2011-01-01

387

Doppler Radar for Heartbeat Rate and Heart Rate Variability Extraction  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This paper presents a Doppler radar system used to detect the heartbeat signal from a d?istance of one meter. The proposed system is based on using a vector network analyzer and two antennas. Measurements are performed at 16 GHz for different power levels between 0 and -25 dBm. Both heartbeat rate and heart rate variability are extracted and compared to a simultaneous ECG signal.

Obeid, Dany; Sadek, Sawsan; Zaharia, Gheorghe; El Zein, Ghai?s

2011-01-01

388

Analytical theory of Doppler reflectometry in slab plasma model  

International Nuclear Information System (INIS)

Doppler reflectometry is considered in slab plasma model in the frameworks of analytical theory. The diagnostics locality is analyzed for both regimes: linear and nonlinear in turbulence amplitude. The toroidal antenna focusing of probing beam to the cut-off is proposed and discussed as a method to increase diagnostics spatial resolution. It is shown that even in the case of nonlinear regime of multiple scattering, the diagnostics can be used for an estimation (with certain accuracy) of plasma poloidal rotation profile. (authors)

2004-10-25

389

Performance assessment of the Aeolus Doppler wind lidar prototype  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The Atmospheric Dynamics Mission ADM-Aeolus of the European Space Agency ESA will be the first mission worldwide to provide global observations of wind profiles by applying a Doppler wind lidar on a satellite. In the framework of this mission an instrumental prototype was developed to evaluate the measurement principle and to analyse signal processing algorithms. This thesis introduces a simulator representing the properties of the atmosphere and the optical receiver unit. The simulator ...

Paffrath, Ulrike

2007-01-01

390

New technology in wound ballistics: the Doppler radar.  

Science.gov (United States)

The feasibility of using Doppler radar to obtain more accurate measurements of velocity and yaw angle of bullets was investigated. Anesthetized pigs were shot at a range of 9-10 meters, and velocity measurements were obtained using Doppler radar and photocells. The data from the two types of equipment was compared. Excellent correspondence was found between the measurements of entry velocities of low, medium, and high velocity bullets, i.e., an average deviation of less than 1% (range 0-2%). Measurements of exit velocities of low and medium velocity bullets corresponded just as well, but measurements of exit velocities of high velocity bullets was complicated in both methods by signal cluttering caused by fragments of tissue released from the exit wound and by the deflection of the bullet. A Doppler radar was used to follow the movements of the bullet, to determine the velocity, and, if possible, to determine when the bullet stabilizes and the exact yaw angles continuously. We were able to design a system in which even small caliber bullets could be followed for 15-20 meters. It was possible to detect yaw even with these small calibers, and the radar was not disturbed by additional equipment. Using Doppler radar to measure velocity offers important benefits--simple set up, minimal risk of damage to equipment by stray bullets, and very good accuracy. The results of measuring yaw angles of bullets are promising, as far as determining the point of stability is concerned, but further work is necessary to be able to measure the angle of yaw exactly. PMID:8606419

Knudsen, P J; Svender, J; Sørensen, O H

1996-03-01

391

An extra-heating mechanism in Doppler-cooling experiments  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In this paper we experimentally and theoretically investigate laser cooling of Strontium 88 atoms in one dimensional optical molasses. In our case, since the optical cooling dipole transition involves a $J_g=0$ groundstate, no Sisyphus-type mechanisms can occur. We are thus able to test quantitatively the predictions of the Doppler-cooling theory. We have found, in agreement with other similar experiments, that the measured temperatures are systematically larger than the the...

Chaneliere, Thierry; Meunier, Jean-louis; Kaiser, Robin; Miniatura, Christian; Wilkowski, David

2004-01-01

392

Doppler ultrasonography of hepatic artery in malignant liver tumors  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Hepatic artery is dominant compared to portal vein in liver tumor vascularization. Malignant tumors have uncontrolled growth and spread onto neighbouring tissues through a tumor vascular network. Based on this we discussed the use arterial flow parameters including systolic and diastolic speed, Doppler perfusion index, and resistance index for early detection of liver metastasis. We also discussed possibility to make differential diagnosis from other disease such as arterial stenosis, liver c...

Periši? Mirjana; Juriši? Vladimir; Kerkez Mirko

2008-01-01

393

Performance Analysis of OFDM-CDMA Systems with Doppler Spread  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Multi carrier modulation are very sensitive to rapid time-varying multi-path channel characterized by Doppler spread. Although progress has been made in the description of the time variation, there is still considerable gaps in its effect especially on diversity gain acquired by time selectivity. This paper models a general case of time-varying channel effect on the OFDM-CDMA performance. This performance is measured through the Signal to Interference and Noise Ratio SINR at the output of the...

2006-01-01

394

Doppler-free two-photon atomic spectroscopy  

Energy Technology Data Exchange (ETDEWEB)

The first and the second order Doppler effect is studied. Two-photon transition probability, selection rules of two-photon resonance and the results of the two-photon experiments are presented. Two-photon decay of the metastable 2S state of hydrogen atom is investigated. The description of measurements of energy levels in hydrogen atom and of the fundamental constants is given.

Suffczynski, M. (Polska Akademia Nauk, Warsaw. Inst. Fizyki)

1980-01-01

395

Doppler-free resonance ionization mass spectrometry of beryllium  

International Nuclear Information System (INIS)

The two-photon resonance ionization scheme employed for beryllium requires two --280-nm photons to excite the 2s6s (/sup I/S/sub 0/) state from the 2s/sup 2/ (/sup I/S/sub 0/) ground state. Ionization is then achieved from the excited state by means of a 1064-nm infrared photon from the Nd:YAG pump laser. First-order cancellation of the Doppler broadening of the two-photon transition is achieved when the two photons are separately derived from counter-propagating beams of the same wavelength. The ''Doppler-free'' line profile obtained in a spectral scan is normally super-imposed on a ''Doppler pedestal'' resulting from the abosrption of both photons from the same one of the two counter-propagating beams. To achieve the desired isotopic selectivity, it is necessary to eliminate, or greatly reduce, the Doppler pedestal. This can be done by circularly polarizing the counter-propagating beams in such a fashion that absorption of one photon from each beam would impart an allowed ?m=0 change in a /sup 1/S/sub 0/ - /sup 1/S/sub 0/ transition, while two photons from either beam would impart a forbidden change of ?m=+-2. The RIMS (Resonance Ionization Mass Spectrometry) spectrometer employed here has been described previously except for the substitution of a narrow-band pulsed dye amplifier (PDA) for the pulsed dye laser. The three-stage PDS amplifies the emission of a single-mode cw dye laser, yielding a measured bandwidth of 170 MHz at 560 nm. 20-mJ pulses from the PDA are frequency-doubled to yield --2 mJ pulses in the UV. Use of a long (--90-cm) collimating lens at the PDA output, prior to doubling, results in a nearly-collimated UV beam of about 2-mm diameter at the sample site

1987-01-01

396

MRI and colour-Doppler in sclerosing mesenteritis  

Energy Technology Data Exchange (ETDEWEB)

We present a case of sclerosing mesenteritis with fibrofatty thickening of the mesentery. Ultrasonography showed an echodense mesenteric mass and colour-Doppler displayed patent mesenteric vessels with high vascular resistance. On CT, low-density areas suggesting fatty infiltration were seen in the mesentery. MRI showed low-signal areas suggesting a fibrous component of the mesenteric mass and GRASS imaging confirmed normal patency of the mesenteric vessels. (orig.)

Bellin, M.F. [Dept. of Radiology, Hopital La Pitie, 75 Paris (France); Thi Huong Du, L.E. [Dept. of Internal Medicine, Hopital La Pitie, 75 Paris (France); Sarfaty, G. [Dept. of Radiology, Hopital La Pitie, 75 Paris (France); Mayaudon, H. [Dept. of Internal Medicine, Hopital La Pitie, 75 Paris (France); Hardin, J.M. [Dept. of Internal Medicine, Hopital de Soissons (France); Godeau, P. [Dept. of Internal Medicine, Hopital La Pitie, 75 Paris (France); Grellet, J. [Dept. of Radiology, Hopital La Pitie, 75 Paris (France)

1992-08-01

397

Murmur and Doppler alternans in critical pulmonary stenosis.  

Science.gov (United States)

Pulsus alternans is a well-recognized clinical entity in which alternating strong and weak pulses are detected. It usually is secondary to underlying myocardial failure. Murmur alternans (alternation in murmur intensity) has been described in aortic stenosis and a few right-sided lesions such as pulmonary hypertension and embolism. This report describes a case of murmur alternans in critical pulmonary stenosis that also showed Doppler alternans on echocardiography. The underlying cause was right ventricular systolic dysfunction. PMID:21748495

Atiq, Mehnaz; Akhter, Saleem; Abdul Sattar, Sheikh; Mohsin, Shazia; Aslam, Nadeem

2011-10-01

398

Graphical Representation of the Doppler Shift: Classical and Relativistic  

Science.gov (United States)

The Doppler shift is a frequency change of a repetitive effect, as measured by a receiver, due to the motion of the wave emitter, to the motion of the wave receiver, or both. A demonstration of the effect is provided by the sound of a car's horn that changes from a higher pitch to a lower pitch when a car drives past. Most derivations of the…

Rojas, R.; Fuster, G.

2007-01-01

399

Doppler-free two-photon atomic spectroscopy  

International Nuclear Information System (INIS)

The first and the second order Doppler effect is studied. Two-photon transition probability, selection rules of two-photon resonance and the results of the two-photon experiments are presented. Two-photon decay of the metastable 2S state of hydrogen atom is investigated. The description of measurements of energy levels in hydrogen atom and of the fundamental constants is given. (A.S.)

1978-04-24

400

Spread-Spectrum Carrier Estimation With Unknown Doppler Shift  

Science.gov (United States)

We present a method for the frequency estimation of a BPSK modulated, spread-spectrum carrier with unknown Doppler shift. The approach relies on a classic periodogram in conjunction with a spectral matched filter. Simulation results indicate accurate carrier estimation with processing gains near 40. A DSP-based prototype has been implemented for real-time carrier estimation for use in New Mexico State University's proposal for NASA's Demand Assignment Multiple Access service.

DeLeon, Phillip L.; Scaife, Bradley J.

1998-01-01

 
 
 
 
401

Doppler deterioration in intrauterine growth restriction: Unterscheider et al.  

Science.gov (United States)

The article below summarizes a roundtable discussion of a study published in this issue of the Journal in light of its methodology, relevance to practice, and implications for future research. Article discussed: Unterscheider J, Daly S, Geary MP, et al. Predictable progressive Doppler deterioration in IUGR-does it really exist? Am J Obstet Gynecol 2013;209:539.e1-7. PMID:24145182

Macones, George A; Cahill, Alison; Odibo, Anthony

2013-12-01

402

Doppler Tomography of Dwarf Nova IY UMa during Quiescence  

CERN Document Server

Quiescent Doppler tomography of the newly discovered deeply-eclipsing SU UMa system IY UMa reveals properties of the region where the accretion stream from the donor impacts the edge of the disc. A very strong bright spot is produced and the Keplerian disc emission in the impact region is disrupted or obscured. The differing properties of Halpha, Hbeta and He I emission will allow physical parameters of the converging flow region to be studied.

Rolfe, D J; Haswell, C A; Rolfe, Daniel J.; Abbott, Timothy M C; Haswell, Carole A.

2000-01-01

403

Estimation of Carotid Artery Pulse Wave Velocity by Doppler Ultrasonography  

Directory of Open Access Journals (Sweden)

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.

Mehdi Maerefat

2009-06-01

404

Active Region Moss: Doppler Shifts from Hinode/EIS Observations  

Science.gov (United States)

Studying the Doppler shifts and the temperature dependence of Doppler shifts in moss regions can help us understand the heating processes in the core of the active regions. In this paper we have used an active region observation recorded by the Extreme-ultraviolet Imaging Spectrometer (EIS) onboard Hinode on 12-Dec- 2007 to measure the Doppler shifts in the moss regions. We have distinguished the moss regions from the rest of the active region by defining a low density cut-off as derived by Tripathi et al. (2010). We have carried out a very careful analysis of the EIS wavelength calibration based on the method described in Young, O Dwyer and Mason (2012). For spectral lines having maximum sensitivity between log T = 5.85 and log T = 6.25 K, we find that the velocity distribution peaks at around 0 km/s with an estimated error of 4 km/s. The width of the distribution decreases with temperature. The mean of the distribution shows a blue shift which increases with increasing temperature and the distribution also shows asymmetries towards blue-shift. Comparing these results with observables predicted from different coronal heating models, we find that these results are consistent with both steady and impulsive heating scenarios. Further observational constraints are needed to distinguish between these two heating scenarios.

Tripathi, Durgesh; Mason, Helen E.; Klimchuk, James A.

2012-01-01

405

Gravitational waves from coalescing binaries and Doppler experiments  

CERN Multimedia

Doppler tracking of interplanetary spacecraft provides the only method presently available for broad-band searches of low frequency gravitational waves. The instruments have a peak sensitivity around the reciprocal of the round-trip light-time T of the radio link connecting the Earth to the space-probe and therefore are particularly suitable to search for coalescing binaries containing massive black holes in galactic nuclei. A number of Doppler experiments -- the most recent involving the probes ULYSSES, GALILEO and MARS OBSERVER -- have been carried out so far; moreover, in 2002-2004 the CASSINI spacecraft will perform three 40 days data acquisition runs with expected sensitivity about twenty times better than that achieved so far. Central aims of this paper are: (i) to explore, as a function of the relevant instrumental and astrophysical parameters, the Doppler output produced by in-spiral signals -- sinusoids of increasing frequency and amplitude (the so-called chirp); (ii) to identify the most important p...

Bertotti, B; Iess, L; Bertotti, Bruno; Vecchio, Alberto; Iess, Luciano

1999-01-01

406

New signal analysis methods for laser doppler flowmetric recordings  

Science.gov (United States)

The laser Doppler flowmetry devices give a series of information like the blood flux and some statistical parameters, automatically estimated. There are also new important attempts based on the Fourier transform of the flow flux signal which gather more information from the laser Doppler flowmetry. The amplitude spectra estimated in these articles, exhibit a series of peaks corresponding to the cardiac variation of the blood flow and noise components of the flow flux signals, dependent on the state of the tooth. The aim of our investigations is to introduce new signal processing methods, based on wavelet continuous tranform, which express in a more sensitive manner the modifications of the flow flux signal with the state of the tooth, and to introduce new quantitative parameters, defined in a previous paper. These parameters express, in a more sensitive manner the modifications of the pulp flow flux signal in relation with the pulp tooth healt, and to introduce new quantitative parameters, defined in a previous paper. These parameters express, in a sensitive way the changes of the blood flux. For practical investigations we used a series of signals recorded with the aid of a Laser Doppler Blood Flow Monitoring device (Moor Instruments) and processed with the computer.

?g?nescu, G. E., Dr; Todea, Carmen

2014-01-01

407

Advances in precision Doppler spectroscopy on cool stars  

Directory of Open Access Journals (Sweden)

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

Anglada-Escudé Guillem

2013-04-01

408

Measuring differential cross sections using the Doppler shift  

International Nuclear Information System (INIS)

We discuss two methods, one of them new, for recovering level-specific differential cross sections in crossed molecular beams experiments from the Doppler profiles of line shapes observed by laser induced fluorescence. The angular resolutions of the two methods are compared and shown to be complementary. An experiment using both methods can have moderately good angular resolution at all scattering angles. In the first method, which has previously been demonstrated experimentally, the Dopper profile is taken with the laser beam parallel to the relative velocity of the collision system. Good angular resolution is obtained between ?/4 and 3?/4. In the second method, which is proposed here, the Doppler profile is taken with the laser beam perpendicular to this relative velocity, and the best angular resolution is obtained in the regions 0 to ?/4 and 3?/4 to ?. This method requires an integral transform to recover the cross section from the Doppler profile. A practical implementation of this transform is presented along with a numerical example showing its relative insensitivity to noise in the profile

1981-07-15

409

Novel measure for the calibration of laser Doppler flowmetry devices  

Science.gov (United States)

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.

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

2014-03-01

410

Active Region Moss: Doppler Shifts from Hinode/EIS Observations  

CERN Multimedia

Studying the Doppler shifts and the temperature dependence of Doppler shifts in moss regions can help us understand the heating processes in the core of the active regions. In this paper we have used an active region observation recorded by the Extreme-ultraviolet Imaging Spectrometer (EIS) onboard Hinode on 12-Dec-2007 to measure the Doppler shifts in the moss regions. We have distinguished the moss regions from the rest of the active region by defining a low density cut-off as derived by Tripathi et al. (2010). We have carried out a very careful analysis of the EIS wavelength calibration based on the method described in Young et al. (2012). For spectral lines having maximum sensitivity between log T = 5.85 and log T = 6.25 K, we find that the velocity distribution peaks at around 0 km/s with an estimated error of 4-5 km/s. The width of the distribution decreases with temperature. The mean of the distribution shows a blue shift which increases with increasing temperature and the distribution also shows asymm...

Tripathi, Durgesh; Klimchuk, James A

2012-01-01

411

Determination of mass flow in liquid jets using phase Doppler anemometry; Massenstrommessung an Fluessigkeitsstrahlen mittels Phasen-Doppler-Anemometrie  

Energy Technology Data Exchange (ETDEWEB)

Fundamental modifications of conventional phase Doppler anemometer are described in order to measure the diameter and the velocity of a molten metal jet. These modifications result in a new kind of experimental PDA-setup called plane-PDA. Using the diameter and velocity information, it is possible to determine the mass flux of molten metal jets. Results on rigid metal bars are presented. (orig.) [Deutsch] Es werden die grundlegenden Aufbauten beschrieben, die notwendig sind, um mittels eines Phasen-Doppler-Anemometers (PDA) den Durchmesser und die (Ausfliess-)Geschwindigkeit von Fluessigkeitsstrahlen, speziell von metallischen Schmelzen, bestimmen zu koennen. Die Aenderungen muenden in eine abgewandelte Form des Standard-PDA-Aufbaus, hier: den ebenen PDA-Aufbau. Aus der Durchmesser- und der Geschwindigkeitsinformation soll der Massenstrom ausfliessender Metallschmelzen ermittelt werden. Messeregebnisse an starren Metallzylindern werden vorgestellt. (orig.)

Tillwick, J.; Dahl, H.; Uhlenwinkel, V.; Bauckhage, K.; Wriedt, T. [Bremen Univ. (Germany). Forschungsgruppe Verfahrenstechnik

1997-12-01

412

Power Doppler US patterns of vascularity and spectral Doppler US parameters in predicting malignancy in thyroid nodules  

Energy Technology Data Exchange (ETDEWEB)

Aim: The purpose of this study was to determine whether spectral Doppler ultrasound (US) parameters, including resistive index (RI) and maximal systolic velocity (MSV), or vascular pattern can be used to distinguish malignant from benign thyroid nodules. Materials and methods: We prospectively examined 169 thyroid nodules in 134 patients undergoing sonographically guided fine-needle aspiration biopsy (FNAB). Vascularity as determined by power Doppler US imaging was defined as absent, perinodular alone, or intranodular. For each nodule, the RI and MSV values were recorded as the average of the recordings obtained. Results of the FNAB and surgical pathological examination, if available, were used as a proof of final diagnosis to categorize all nodules as benign or malignant. Results: Seven nodules were excluded from study because of non-diagnostic FNAB results due to hypocellular or insufficient cytological material. Of the remaining nodules, nine were malignant (all confirmed at surgery) and 153 were benign. Of the 145 nodules with intranodular vascularity, nine (6.2%) were malignant and the remaining 136 (93.8%) were benign. The malignant nodules had a mean RI of 0.60 on intranodular and 0.58 on perinodular arteries. These values were not significantly higher than those associated with benign nodules (RI = 0.57 and RI = 0.56, respectively). Malignant nodules had a mean MSV of 20.4 cm/s on intranodular and 35.3 cm/s on perinodular arteries that were also not significantly different from those associated with benign nodules (p > 0.05). Conclusion: The results of this study indicate that Doppler US characteristics including vascular pattern, RI and MSV are not useful parameters for distinguishing malignant from benign thyroid nodules. Therefore, Doppler US characteristics including vascular pattern, RI and MSV values of thyroid nodules can not be used as a diagnostic method to determine which nodules should undergo FNAB.

Tamsel, S. [Departments of Radiology, Ege University School of Medicine, Bornova, Izmir (Turkey)]. E-mail: sadiktamsel@yahoo.com; Demirpolat, G. [Departments of Radiology, Ege University School of Medicine, Bornova, Izmir (Turkey); Erdogan, M. [Endocrinology, Ege University School of Medicine, Bornova, Izmir (Turkey); Nart, D. [Pathology, Ege University School of Medicine, Bornova, Izmir (Turkey); Karadeniz, M. [Endocrinology, Ege University School of Medicine, Bornova, Izmir (Turkey); Uluer, H. [Biostatistics, Ege University School of Medicine, Bornova, Izmir (Turkey); Ozgen, A.G. [Endocrinology, Ege University School of Medicine, Bornova, Izmir (Turkey)

2007-03-15

413

Distal left circumflex coronary artery flow reserve recorded by transthoracic Doppler echocardiography: a comparison with Doppler-wire  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Abstract Background Coronary flow reserve (CFR) recording by means of transthoracic echocardiography (TTDE) in all the main distal coronary arteries is a challenge for advanced echocardiography. Validation studies of TTDE versus Doppler-wire (DW) recordings are available for Left Anterior Descending artery (LAD) and the Posterior Descending coronary artery (PD), but lacking for the more technically challenging Left Circumflex coronary artery (LCx). Aim To evalua...

Auriti Antonio; Pristipino Christian; Cianfrocca Cinzia; Granatelli Antonino; Guido Vincenzo; Pelliccia Francesco; Greco Salvatore; Richichi Giuseppe; Santini Massimo

2007-01-01

414

Power Doppler US patterns of vascularity and spectral Doppler US parameters in predicting malignancy in thyroid nodules  

International Nuclear Information System (INIS)

Aim: The purpose of this study was to determine whether spectral Doppler ultrasound (US) parameters, including resistive index (RI) and maximal systolic velocity (MSV), or vascular pattern can be used to distinguish malignant from benign thyroid nodules. Materials and methods: We prospectively examined 169 thyroid nodules in 134 patients undergoing sonographically guided fine-needle aspiration biopsy (FNAB). Vascularity as determined by power Doppler US imaging was defined as absent, perinodular alone, or intranodular. For each nodule, the RI and MSV values were recorded as the average of the recordings obtained. Results of the FNAB and surgical pathological examination, if available, were used as a proof of final diagnosis to categorize all nodules as benign or malignant. Results: Seven nodules were excluded from study because of non-diagnostic FNAB results due to hypocellular or insufficient cytological material. Of the remaining nodules, nine were malignant (all confirmed at surgery) and 153 were benign. Of the 145 nodules with intranodular vascularity, nine (6.2%) were malignant and the remaining 136 (93.8%) were benign. The malignant nodules had a mean RI of 0.60 on intranodular and 0.58 on perinodular arteries. These values were not significantly higher than those associated with benign nodules (RI = 0.57 and RI = 0.56, respectively). Malignant nodules had a mean MSV of 20.4 cm/s on intranodular and 35.3 cm/s on perinodular arteries that were also not significantly different from those associated with benign nodules (p > 0.05). Conclusion: The results of this study indicate that Doppler US characteristics including vascular pattern, RI and MSV are not useful parameters for distinguishing malignant from benign thyroid nodules. Therefore, Doppler US characteristics including vascular pattern, RI and MSV values of thyroid nodules can not be used as a diagnostic method to determine which nodules should undergo FNAB

2007-03-01

415

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)

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.

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

416

Pulsed and Tissue Doppler Echocardiographic Changes in Patients with Thalassemia Major  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Background: Doppler echocardiographic studies of left ventricle (LV) systolic and diastolic function in patients with ?-Thalassemia Major (?-TM) had shown different patterns of systolic and diastolic dysfunction. Aim: This cross-sectional study was designed to study the LV systolic and diastolic function in patients with ?-TM using Pulsed Doppler (PD) and Tissue Doppler (TD) echocardiography. Methods: All patients were evaluated clinically and by echocardiography, The study included patien...

2010-01-01

417

Doppler Radar Speed Measurement Based On A 24 GHz Radar Sensor  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This thesis will present the implementation of an on-board speed measurement system using a single 24.1 GHz Doppler radar sensor and specialized algorithms to measure the true speed of a vehicle. Two different algorithms are implemented, the first based on estimating the Doppler power density spectrum and extracting the strongest frequency component, and the second based on correlation between the Doppler spectrum and pre-estimated theoretical spectra. The output can be displayed to the user ...

Dybedal, Joacim

2013-01-01

418

Compact, Engineered 2-Micron Coherent Doppler Wind Lidar Prototype for Field and Airborne Evaluation  

Science.gov (United States)

The state-of-the-art 2-micron coherent Doppler wind lidar breadboard at NASA/LaRC will be engineered and compactly packaged consistent with future aircraft flights. The packaged transceiver will be integrated into a coherent Doppler wind lidar system test bed at LaRC. Atmospheric wind measurements will be made to validate the packaged technology. This will greatly advance the coherent part of the hybrid Doppler wind lidar solution to the need for global tropospheric wind measurements.

Kavaya, Michael J.; Amzajerdian, Farzin; Koch, Grady J.

2006-01-01

419

A new non-invasive estimation of the stenotic aortic valve area by pulsed Doppler mapping.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A new pulsed Doppler mapping technique has been used to measure the severity of aortic valve stenosis. The Doppler examination was performed at the site of the aortic orifice in the parasternal short axis echocardiographic view and the method was based on the detection of the area of systolic flow through the stenotic orifice. This area was derived by planimetry and the measurements obtained by the Doppler method were compared with the aortic valve area calculated at catheterisation according...

Veyrat, C.; Gourtchiglouian, C.; Dumora, P.; Abitbol, G.; Sainte Beuve, D.; Kalmanson, D.

1987-01-01

420

Doppler velocity detection limitations in spectrometer-based versus swept-source optical coherence tomography  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Recent advances in Doppler techniques have enabled high sensitivity imaging of biological flow to measure blood velocities and vascular perfusion. Here we compare spectrometer-based and wavelength-swept Doppler OCT implementations theoretically and experimentally, characterizing the lower and upper observable velocity limits in each configuration. We specifically characterize the washout limit for Doppler OCT, the velocity at which signal degradation results in loss of flow information, which...

2011-01-01

 
 
 
 
421

Doppler echocardiography in the study of patients with mitral disc valve prostheses.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A combination of M mode and Doppler echocardiography was used to study patients with mitral disc valve prostheses. The probe used in these investigations consisted of a circular Doppler crystal mounted around the M mode crystal in the same plane. Because of the strong echoes produced by the prosthesis the transducer (probe) could be angled for optimum Doppler signals without losing the M mode echocardiographic recording of the prosthesis. With this equipment mean and maximum blood velocities ...

Nitter-hauge, S.

1984-01-01

422

Doppler Effects for Reflection and Refraction at Moving Interfaces for Left-handed Materials  

CERN Document Server

The Doppler effect for the reflected and refracted waves at an idealized moving interface separating two stationary left-handed materials are systemically analyzed in this letter. The theoretical formulae for Doppler shifts for the left-handed materials, which are described by Drude's dispersion model, are presented. Those formulae are examined by first-principles numerical experiments using the finite difference time domain method. Inverse Doppler effects for reflected waves from the moving interfaces are confirmed in left-handed materials.

Xiao, S; Xiao, Sanshui; Qiu, Min

2004-01-01

423

On the Use of Doppler Shift for Sea Surface Wind Retrieval From SAR  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The synthetic aperture radar (SAR) Doppler centroid has been used to estimate the scatter line-of-sight radar velocity. In weak to moderate ocean surface current environment, the SAR Doppler centroid is dominated by the directionality and strength of wave-induced ocean surface displacements. In this paper, we show how this sea state signature can be used to improve surface wind retrieval from SAR. Doppler shifts of C-band radar return signals from the ocean are thoroughly investigated by colo...

2012-01-01

424

Estimation of laser-Doppler anemometry measuring volume displacement in cylindrical pipe flow  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Laser-Doppler anemometry application in measurements of the 3-D swirl turbulent flow velocity in the cylindrical pipe, behind the axial fan, have been analysed. This paper presents a brief overview of uncertainty sources in the laser-Doppler anemometry measurements. Special attention is paid to estimation of laser-Doppler anemometry measuring volume positioning in cylindrical pipe flow due to optical aberrations, caused by the pipe wall curvature. The hypothesis, that in the central par...

2012-01-01

425

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 ...

2010-01-01

426

Assessing the quality of ionogram interpretation using the HF Doppler technique  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 and dig...

2007-01-01

427

Assessing the quality of ionogram interpretation using the HF Doppler technique  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 and digisonde...

2007-01-01

428

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

CERN Document Server

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.

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

2007-01-01